Report II

VOLUME I: MAIN REPORT

Expellers in India and Expelling Operations

As part of Preparing Status Reports on Themes Related to Technical and Scientific

Utilization of Biofuel Utilization

Department of Science and Technology

Government of India

Submitted by

InsPIRE Network for Environment

June 2012

Principal Investigator

Shankar Haldar Project Team

Aniruddha Bhattacharjee

Vineet Jain

Principal Advisor

Sudhir Singhal

Acknowledgement

InsPIRE Network for Environment (formerly known as Winrock International India), New

Delhi is thankful to the Department of Science and Technology (DST) for awarding it the

opportunity to work under the project entitled “Preparing Status Reports on Themes Related

to Technical and Scientific Aspects of Biofuels Utilization”, and for extending its valuable

support and co-operation during the assignment.

InsPIRE would like to extend a special word of gratitude to Prof. D.V. Singh and Mr. Rajeev

Sharma for their guidance and constant support during the preparation of this report.

Grateful thanks to Ms. Meenakshi Gusain for carrying out the entire work of typing,

formatting and collating the report.

We are particularly grateful to Cdr Dahake, Scientist-in-Charge, and his colleagues, of the

Mechanical Engineering Research & Development Organization, Ludhiana (Unit of CMERI,

Durgapur) for some of the most useful discussions on the subject of expellers and for

facilitating our interaction with Dr. B.K. Yaduvanshi, whose PhD dissertation has been of

great value in making of this report. We would also like to thank all the expeller

manufacturers who spent time with us and shared their information on expeller design and

its operations.

The authors thank Dr. Kinsuk Mitra, President, InsPIRE Network for Environment for his

help in successfully carrying out this study.

InsPIRE Network for Environment

New Delhi

Contents

Volume I

Acknowledgement

Executive Summary i

Chapter 1: Introduction 1

Chapter 2: Oilseeds for Biodiesel Production 3

2.1 Biodiesel production processes 3 2.2 Oilseeds 6

2.2.1 Chemical Composition 6

2.2.2 Oilseeds for Biodiesel Production 9

2.2.3 Non-edible Oilseeds - Jatropha curcas and Pongamia Pinnata 9

2.3 Availability of Oilseeds in India 9 2.4 Features of Jatropha curcas 11 2.5 Plantation and Seed Output 12

Chapter 3: Elements of Expelling Process 13

3.1 Pre-treatment 17 3.1.1 Seed Cleaning 17

3.1.2 Seed Drying 17

3.1.3 Size Reduction 17

3.1.4 Rolling 17

3.1.5 Hull Removal 17

3.1.6 Heating/ Drying 18

3.1.7 Conditioning 18

3.1.8 Extruding 19

3.2 Important Parameters 19 3.3 Parameters affecting Oil Quantity 19 3.4 Parameters affecting Oil Quality 20

Chapter 4: Types of Expellers and their Design Features 21

4.1 Types of Expellers 21 4.1.1 Non-Motorized Expelling 22

4.1.2 Motorised Expellers 22

4.1.3 Heavy Duty Industrial Expellers 22

4.2 Ghanis - Traditional Indian Expellers 24 4.2.1 Granite Ghani 24

4.2.2 Wooden Ghani 24

4.2.3 Bengal Ghani 25

4.2.4 Recent evolution in Ghani technology 25

4.3 Ram presses 25 4.3.1 Efficiency and Expression data of Some Ram Presses 26

4.4 Mechanized Presses 28 4.4.1 Principle of Screw Press 28

4.4.2 Cylinder‐hole type 29

4.4.3 Strainer Type 30

4.5 Common Motorized Screw Presses 31 4.5.1 TinyTech Expeller 31

4.5.2 Sundhara Expeller 32

4.5.3 The Sayari expeller 32

4.5.4 Komet Oil Expellers 33

Chapter 5: Current Expellers 35

5.1 Screw Press – Hand Operated 35 5.2 Screw Press - Motorised 36 5.3 Heavy Duty Industrial Expellers 38

Chapter 6: Jatropha Oil Expellers 42

6.1 Mini Oil Expeller for Jatropha and Pongamia 42 6.2 Screw-Pressing of Jatropha seeds 44

6.2.1 Influence of RPM 45

6.2.2 Influence of Restriction Size 46

6.2.3 Influence of Moisture Content 46

6.2.4 Influence of Hull Fraction 47

6.2.5 Influence of Seed Preheating and Cooking 48

6.2.7 Conclusions 48

6.3 Studies on Parametric Standardization of Mechanical Oil Expression of Jatropha Seeds 48 6.3.1 Seed Moisture Content 49

6.3.2 Seed kernel – Hull Mixtures 53

6.3.3 Modified wormset configuration 55

6.3.4 Recommendation based on the experimental results 55

6.4 Performance test of a Screw-press machine for extracting Jatropha oil 56 6.5 Optimization of Mechanical Extraction of Jatropha seeds 56

6.5.1 Conclusions 57

6.6 Gas Assisted Mechanical Expression (GAME) Technology for Hydraulic Press 57 6.6.1 Description of GAME process 58

6.6.2 Hydraulic Press 59

6.6.3 Influence of Pressure and Temperature 59

6.6.4 Experiments to demonstrate GAME Process 60

Chapter 7: Site Visits 61

7.1 Site Visit 1 – Goyum Screw Press 61 Brief Description 61

Product Range 62

Key Points Discussed 62

7.2 Site Visit 2 – Gobind Expeller Company 63 Brief Description 63

Product Range 63

Key Points Discussed 63

7.3 Site Visit 3 – Nitya Engineers 64 Brief Description 64

Product Range 64

Key Points Discussed 65

7.4 Site Visit 4 – Mohit International 65 Brief Description 65

Product Range 65

Key Points Discussed 65

7.5 Site Visit 5 – Guru Teg Engineering Company 66 Brief Description 66

Product Range 66

Key Points Discussed 66

7.6 Site Visit 6 - MERADO 66 Brief Description 67

Key Points Discussed 67

Chapter 8: Some Recent Publications on Oil Expelling 69

8.1 Optimizing Mechanical Oil Extraction of Jatropha curcas L. Seeds with respect to Press capacity, 69 Oil recovery and Energy efficiency 8.2 Oil Expression from Jatropha Seeds using a Screw Press Expeller 69 8.3 Physical Properties of Jatropha curcas L. Kernels after Heat Treatments 70 8.4 Hydraulic Pressing of Oilseeds: Experimental Determination and Modeling of Yield and Pressing 70 Rates 8.5 Development of a Small Capacity Double Stage Compression Screw Press for Oil Expression 71 8.6 Twin-Screw Extruder for Oil Processing of Sunflower Seeds: Thermo-Mechanical Pressing and 71 Solvent Extraction in a Single Step 8.7 Gas assisted oilseed pressing 72 8.8 Gas Assisted Mechanical Expression of Cocoa Butter from Cocoa Nibs and Edible Oils from Oilseeds 73 8.9 Oil Extraction of Oleic Sunflower Seeds by Twin Screw Extruder: Influence of Screw Configuration 73 and Operating Conditions 8.10 Gas-Assisted Oilseed Pressing - Design of and Tests with a Novel High-Pressure Screw Press 74 8.11 Effects of Compressive Stress, Feeding Rate and Speed of Rotation on Palm Kernel Oil Yield 74 8.12 A New Twin-Screw Press Design for Oil Extraction of Dehulled Sunflower Seeds 75 8.13 Oil Expression Characteristics of Rapeseed for a Small Capacity Screw Press 76 8.14 A Twin-screw Extruder for Oil Extraction: I. Direct Expression of Oleic Sunflower seeds 76 8.15 Seed Oil Extraction using a Solar Powered Screw Press 77 8.16 Effect of Pre-Treatments on Mechanical Oil Expression of Soybean using a Commercial Oil Expeller 77 8.17 Dry Extrusion as an Aid to Mechanical Expelling of Oil from Soybeans 78 8.18 Recovery of Sunflower Oil with a Small Screw Expeller 78 8.19 Mechanical Expression of Oil from Linseed (Linum Usitatissimum L) 79 8.20 Processing Factors affecting Yield and Quality of Mechanically Expressed Groundnut Oil 79 8.21 Enzymatic Pretreatment to Enhance Oil Extraction from Fruits and Oilseeds: A Review 80 8.22 Enzymatic Hydrolysis of Soybean for Solvent and Mechanical Oil Extraction 80 8.23 Mechanical Expression of Oil from Melon Seeds 80 8.24 Supercritical CO2 Extraction of Fatty Oil from Flaxseed and Comparison with Screw Press 81 Expression and Solvent Extraction Processes 8.25 Comparative Evaluation of the Digester–Screw Press and a Hand-Operated Hydraulic Press for 81 Palm Fruit Processing 8.26 Design and Development of Secondary Controlled Industrial Palm Kernel Nut Vegetable Oil 82 Expeller Plant for Energy Saving and Recuperation 8.27 Energy Analysis in the Screw Pressing of Whole and Dehulled Flaxseed 82 8.28 Design and Testing of a Solar Photovoltaic Operated Multi-Seeds Oil Press 83

Chapter 9: Findings and Discussion 84

Chapter 10: Suggestions for Further Research 87

Presentation made at Review Meeting

List of Tables

Table 2.1: Biodiesel Projections 4 Table 2.2: Main Oilseeds and their Uses 6 Table 2.3: Chemical compositions of some common Vegetable Oils 7 Table 2.4: Properties of Jatropha Oil and Standard Diesel 10 Table 2.5: Properties of Pongamia Oil and Standard Diesel 10 Table 2.6: Differences between Jatropha and Pongamia 11 Table 2.7: Average Seed Yield of Jatropha 12 Table 4.1: Comparative analysis of different categories of expellers 23 Table 4.2: Brief overview of designs 27 Table 4.3: Characteristics of Seed Varieties 27 Table 4.4: Results for High Performance Test for Varieties 1, 2 and 3 28 Table 4.5: Results for High expression test for Varieties 1, 2 and 3 28 Table 6.1: Interactive effect of speed and compression ratio on Oil recovery and SEC of a) Pongamia 43

Seeds; b) Jatropha Seeds Table 6.2: BT50 specifications 44 Table 6.3: Impact of cooking on Oil Recovery 48 Table 6.4: Efficiency of Oil Expression under Different Wormset Configuration 55

List of Figures

Figure 2.1: General steps in Biodiesel Production 5 Figure 3.1: Hydraulic Press 14 Figure 3.2: Screw Press 15 Figure 4.1: A standard heavy duty industrial expeller 23 Figure 4.2: Traditional Indian Ghani used for oil expelling 24 Figure 4.3: Crushing oil seeds using motorized Ghani 25 Figure 4.4: Bielenberg Ram Press

10 26

Figure 4.5: A standard small-scale screw press and its mechanical parts, showing the 29 Figure 4.6: Schematic of a Cylinder-hole type press

6 29

Figure 4.7: A schematic of a standard filter press 30 Figure 4.8: Examples of a) Cylinder-hole type – Danish BT Press; b) Strainer type – Sundhara Oil Expeller

6 31

Figure 4.9: The Tinytech expeller with boiler and filter press 31 Figure 4.10: Sundhara expeller from the side, visible is the cage composed 32 Figure 4.11: The Sayari Expeller 33 Figure 4.12: Sectional view of a standard Komet Expeller 33 Figure 5.1: A simple hand operated expeller (Rajkumar Agro) and its operational details 35 Figure 5.2: Goyum 20 Oil Expeller 36 Figure 5.3: Goyum-100 Oil Expeller 37 Figure 5.4: Super Oil Expeller, Gobind Expellers, Ludhiana 38 Figure 5.5: Model 1500, Goyum Expellers, Ludhiana 40 Figure 5.6: ZY32 expeller from Hebei Nanpi Machinery Manufacture Co. Ltd. 41 Figure 6.1: Schematic Diagram of Oil Expeller 43 Figure 6.2: Influence of screw speed for BT 50 a) Oil recovery and throughput; b) Energy requirement 45 Figure 6.3: Influence of restriction size on Oil recovery and throughput for a) BT50; b) Sayari Press 46 Figure 6.4: Influence of Moisture Content on Oil recovery and throughput for a) BT50 press; b) Sayari Press

47 Figure 6.5: Influence of Hull content on Oil recovery and throughput for BT50 press 47 Figure 6.6: Technical Details of 1 TPD MERADO Make Oil Expeller 49 Figure 6.7: Efficiency of Oil Expression of Water Sprinkled, Water Soaked, and Steamed Whole Jatropha

Seeds 50 Figure 6.8: Specific Power consumption of Oil Expeller on Whole Jatropha Seed 51 Figure 6.9: Expeller Throughput at different Seed Moisture content of Whole Jatropha Seed 52 Figure 6.10: Efficiency of Oil Expression of Dehulled Jatropha Seeds under Different Moisture Content 54 Figure 6.11: Mechanical screw press for oil extraction and installed sensor, (a) feeding hopper, (b) housing, (c)

screw press, (d) oil outlet holes, (e) heating, (f) nozzle, (g) press cake outlet, (i) cohesion zone, (h) oil collector, (k) coupling, (l) speed alternator, (M) motor, (T1-T5) temperature sensors, (T5) temperature sensor (IR), (ω) rotational speed 57

Figure 6.12: Principle of GAME Process 58 Figure 6.13: Schematic representation of Hydraulic Press 59

Contents

Volume II

ANNEXURE

1. Khan, L.M. and Hanna, M.A. Expression of Oil from Oilseeds-A Review. J. agric. Engng Res.

(1983) 28.

2. Boateng, C.O. et al., Comparative exergy analyses of Jatropha curcas oil extraction methods:

Solvent and mechanical extraction processes. Energy Conversion and Management 55 (2012).

3. Achaya, K.T., Ghani: A traditional method of oil processing in India, FAO Corporate

Document Repository (1994)

4. Uziak, J. and Loukanov, I. A., Performance Evaluation of Commonly Used Oil Ram Press

Machines, International Commission of Agricultural Engineering, October 2007. Available at:

5. Henning, R.K., The Jatropha System: An integrated approach of rural development. June

2009.

6. Reddy, S.S., et al. Studies on the effect of compression ratio and speed on oil recovery and

energy consumption in mini oil expeller for Pongamia and Jatropha seed oil expulsion.

eNREE, Volume 7 (2), April-June 2010.

7. Beerens, P., Screw-pressing of Jatropha seeds for fuelling purposes in less developed

countries, Eindhoven University of Technology, August 2007.

8. Yaduvanshi, B.K., Studies on Parametric Standardization of Mechanical oil Expression of

Jatropha Seeds. PhD Thesis, G.B. Pant University of Agriculture and Technology, 2008.

9. Harmanto, A., et al. Performance Test of a Screw-Press Machine for Extracting Jatropha

curcas Seed into Crude Oil as an Alternative Energy Source. Indonesian Journal of

Agriculture 2(1), 2009: 35-40.

10. Karaj, S. and Muller, J. Optimization of mechanical extraction of Jatropha curcas seeds. Focus

Cropping and Machinery, University of Hohenheim. 2009.

11. Willems, P., Gas Assisted Mechanical Expression of Oilseeds, Universiteit Twente,

Nederland, 2007.

12. Theory of Oil Extraction, Position Statement by Goyum Screw Press, Ludhiana

13. Jatropha Expellers designed and developed by MERADO, Ludhiana

14. Commercial Expellers Profile

14.1 Goyum Screw Press, Ludhiana

14.2 Gobind Expeller Company, Ludhiana

14.3 Nitya Engineers, Ludhiana

14.4 Mohit International, Ludhiana

14.5 Guru Teg Engineering Company, Ludhiana

i

Executive Summary

Expelling operations have come a long way since its inception many centuries ago. From the

simple rural ‘Ghanis’ that were time-intensive and low in capacity, expelling equipment

manufactured today, including in India, boasts of high capacity, high workmanship and

operational efficiency, and, low power consumption. India has always been blessed with a

richness of agricultural produce and the same has inspired industrious individuals to design

expellers that are employed today in crushing a wide array of oilseeds.

The country’s biodiesel sector on the other hand is likely to depend entirely on non-food

oilseeds, in particular on seeds like Jatropha curcas. The plant has had its share of laurels

and criticism, but the truth remains that from the point of view of rural economics,

enterprise creation and India’s natural climatology, Jatropha is bound to be a key resource

in fuelling the country’s biodiesel output. Till date, availability of Jatropha seeds has at best

been sporadic. The expelling industry in India therefore is yet to design an expeller that

could be put to use exclusively for expelling Jatropha oilseeds with high expelling efficiency

and minimal power consumption. Whatever little expelling has been carried out over the

last few years has been carried out on equipment fabricated for seeds like groundnut,

mustard and cottonseed, etc. If the government’s ambitious plans for 20% biodiesel

blending by 2017 are to come to fruition, this niche sector requires a critical analysis. There

is immense amount of work to be done in terms of understanding the physico-mechanical

conditions to be standardized for efficient expelling of Jatropha seeds. Design modifications

on current expellers need to be identified for the purpose as does the field of pre- and post-

processing of seedcake.

Expeller manufacturers in the country have honed their equipments to stellar levels of

output, but, little or no research appears to have been carried out in this area of equipment

design and the knowledge base is a bare minimum. It appears that the subject does not

attract any interest either in the universities or in the industry sector. This report therefore

attempts to capture various aspects crucial to expelling of oil from Jatropha seeds and

highlights the design features of currently available expelling equipment. While not

exhaustive, the report has endeavoured to collect all available information of a scientific

nature in this area, and to the extent possible, specifically for Jatropha. The report therefore

is expected to play a role in initiation of R & D activities in the country, and, prepare for a

situation where large scale availability of Jatropha would call for efficient expelling

operations.

The report has a chapter on basics of oil seeds where the potential for various oil seeds used

for biodiesel production and some statistics related to its availability, including projections,

are presented. The schematics of the basic process employed for production of biodiesel is

described and the chemical composition of some common vegetable oil seeds is given. A

brief description of features of Jatropha is also included.

ii

The elements of expelling process are described in detail in a separate chapter and a brief

description of various kinds of presses e.g. the hydraulic press, the ghani, and the screw

press is also given. The chapter includes details of the various pre-treatments which are

required by the oleaginous material and the parameters of the press operation affecting the

quality and quantity of oil expelled.

The various types of expellers and their design features including a comparative analysis of

different categories of expellers are included in a separate Chapter. Starting from the ghanis

– the traditional Indian expeller – to the Ram presses, the mechanized presses, the common

motorized screw presses, etc. are covered. Examples of various commercial expellers are

also given.

There is a specific chapter on Jatropha Oil expellers. In this, apart from the schematics of the

various kinds of expellers employed, the influence of various process parameters like

machine rpm, restriction size, influence of moisture content of the seeds, influence of the

hull fraction, effect of seed preheating and cooking, etc. is also covered. Relevant

information from a very recent PhD dissertation from a renowned Indian Agricultural

University is shared. Information of Gas Assisted Mechanical Expression (GAME)

technology for hydraulic press where the oil seeds are saturated with super-critical carbon-

di-oxide before mechanical pressing is also described. In this process, CO2 replaces part of

the oil during pressing thereby increasing the oil yield.

The site visits carried out in connection to preparation of this report and the discussions

held are described in a separate chapter. A brief summary of some additional research

papers on oil expelling from all over the world, with particular emphasis on the design

features and parameters, is included.

The concluding chapters bring out the findings of the exercise of making this report and

specific suggestions for further research required to be carried out for Jatropha curcas

expellers, in order to maximise their efficiencies and oil yields are given. Volume II of this

report covers some specific literature, including research dissertations, which are of

considerable interest to expelling operation and with particular reference to Jatropha curcas.

Considerable additional information can be accessed from these.

1

Introduction

Biodiesel today is a viable alternative to conventional diesel. Improved methods of

production and breakthroughs in alternative feedstock are rapidly cementing its position as

a mainstream alternative. The benefits of using biodiesel are numerous and amongst others

include aspects of various kinds of environmental benefits, rural employment, strategic and

economic requirements, etc. The importance of biodiesel can be well understood by the fact

that in USA alone, in the year 2011, over one billion gallons of biodiesel was produced and

sold. In 2012, this figure is expected to touch 1.6 billion gallons. Manufacturers and policy

makers, worldwide, have therefore stepped up their participation in the global biodiesel

sector, to incorporate all possible methods for mainstreaming the use of biodiesel. The bulk

of the biodiesel today is produced from seed oils. Expelling of oil from the seeds is an age

old process and has been extensively used. A higher efficiency of expelling is clearly

desirable not only to maximize the availability of the feedstock for biodiesel production but

also to minimize the net energy consumption of the process. New research is therefore

necessary to optimize various parameters of this process. Although the basic principles of

expelling are virtually the same for all oil seeds, the optimization of the process for specific

oil seeds is highly desirable. Very little information exists specifically on expelling of oil

from Jatropha seeds. As Indian focus is on Jatropha, a better understanding of expelling oil

from it would benefit all concerned. It appears that not much work has yet been done on this

subject.

This report brings out information available from the internet and from various other

sources related to expelling of oil with reference to Jatropha seeds. If we visualize large scale

application of Jatropha seeds in India, it is imperative to do optimization of the design and

process of the expellers. Like oilseeds themselves, extracting oil from oilseeds is not a new

practice. Rural populations in India and other countries have been doing so for several

centuries – primarily for domestic uses like extracting oil from mustard seeds for cooking or

for domestic lighting. However, it is only in the last few decades that commercial

exploitation of oilseeds has caught the fancy of industrialists around the world, for

environmental and cost benefits. There are two basic methods of oil extraction from oilseeds:

through expelling operations and through solvent extraction processes. Solvent Extraction

processes are relatively new and are currently undergoing significant research. This method

is capital intensive and justifies itself for large-scale industrial production. The infrastructure

it calls for is highly technical and regular operations need to be monitored closely for quality

output. Oilseed Expelling on the other hand has been in the foray for long and thus enjoys a

fair degree of research and operational improvements. From small-scale manual expelling

for rural populations, manufacturers around the world are now capable of fabricating

equipment to extract the maximum possible oil from the oilseeds. Coupled with the

introduction of motorized industrial expelling equipment and advances made in optimizing

CHAPTER 1

2

pre-expelling seed preparation, oilseeds are now rightly regarded as a major feedstock for

economical biodiesel production.

As per the requirements of DST, this report covers following aspects related to oil expelling:

Inventorization of various expellers that are being used, their capacities and expelling

mechanisms with respect to Pongamia and Jatropha seeds.

Study of current expellers to identify their key features including length of crushing

chambers, slot sizes in the crushing chambers, worms and their design, feeding

mechanisms, nature of drives, etc.

Assessment of the efficiencies and undertaking a comparative analysis of the expellers.

Detailed study of the expelling process including feeding mechanisms, steam heating

through the use of boiler, crushing including the need for more than one round of

crushing, seed cake handling mechanism, etc. and undertake an energy balance and

cost benefit analysis study to identify the processes which offer the maximum potential

for efficiency improvement.

This report contains a Chapter each on Oilseeds for Biodiesel Production, The Elements of

Expelling Process, Types of Expellers and their Design Features, Current Expellers, Specific

Information on Jatropha Oil Expellers, Summary of Findings, and, Suggestions for Further

Research. In addition, a brief summary of the various site visits made in connection with

eliciting information on this subject from manufacturers and researchers is given. Literature

including research dissertations of specific interest to expelling, with particular reference to

Jatropha, is covered in a separate volume as an annexure to this report. A chapter on recent

publications in the area of Oil expelling, including from Jatropha, has been added in this

report to draw attention towards some of the research activities being carried out in this

area. Some publications are on oilseeds other than Jatropha, but very useful information on

research parameters can be drawn from them.

3

Oilseeds for Biodiesel Production

2.1 BIODIESEL PRODUCTION PROCESSES

Most oilseeds used for biodiesel production yield oil that is initially unfit to be treated

as commercial scale I.C. Engine fuel. Due to its applications in engines, commercial

biodiesel must conform to certain physico-chemical characteristics, failing which,

improper performance and/or equipment failure may result. Thus the oil extracted

through expelling or solvent extraction is subjected to a series of procedural steps to

obtain commercial grade biodiesel.

Currently there are multiple technologies used for this process. Each process has its

own set of operational requirements and limitations, but most have unit operations

and a general flow of operations as depicted in the schematic on next page.

Average biodiesel production capacity for the main producers in the world is

estimated to be 17.6 MN L. for 2008-10. A bulk of this is attributed to USA and the

European Union. It is interesting to note that a growth rate of nearly 27% is predicted

for India for 2011-20 which would make the country one of the major producers in the

world. 1

1 Chapter 3: Biofuels. OECD FAO Agricultural Outlook 2011-2020. Available at: http://www.agri-outlook.org/dataoecd/23/56/48178823.pdf

CHAPTER 2

4

Table 2.1: Biodiesel Projections1

Production(MN L) Growth

(%)1 Domestic Use (MNL)

Growth (%)

1

Share in Diesel Type Fuel Use (%) NET Trade (MN L)20

Average 2008-10est

2020 2011-20 Average

2008-10est 2020 2011-20

Energy Shares Volume Shares Average

2008-10est 2020 Average

2008-10est 2020

Average 2008-10est

2020

North America

Canada 236 594 6.57 202 672 3.65 0.4 1.6 0.5 2.0 34 -78

United States 1 658 4 002 2.24 909 4 575 5.39 0.3 1.3 0.4 1.6 748 -755

Western Europe

European Union 9 184 17 610 5.17 10 802 19 794 4.75 3.9 6.6 4.9 8.1 -1 619 -2184

Of which second generation 0 2 190 … … … … … … … … … …

Oceania Developed

Australia 627 719 1.14 627 719 1.14 2.7 2.7 3.4 3.3 0 0

Other Developed

South Africa 57 100 3.65 57 100 3.66 0.0 0.0 0.0 0.0 0 0

Sub-Saharian Africa

Mozambique 51 80 1.85 0 32 1.47 0.0 0.0 0.0 0.0 51 48

Tanzania 50 31 -0.13 0 58 159.22 0.0 0.0 0.0 0.0 50 3

Latin America and Caribbean

Argentia 1 576 3 231 3.36 247 656 2.13 1.9 4.0 2.3 5.0 1 329 2576

Brazil 1 550 3 139 2.66 1 550 3 139 2.66 2.7 4.0 3.4 5.0 0 0

Columbia 302 768 4.88 228 430 4.77 1.6 4.0 2.0 5.0 75 338

Peru 174 130 3.74 174 315 4.35 1.6 4.0 2.0 5.0 0 -185

Asia and Pacific

India 179 3 293 26.87 241 3 291 26.87 0.0 0.1 0.0 0.1 -61 2

Indonesia 369 811 6.65 272 1 100 14.37 1.3 5.7 1.7 7.0 98 -289

Malaysia 765 1 331 3.96 206 500 8.35 1.6 4.0 2.0 5.0 559 831

Philippines 158 271 03.97 158 200 1.70 0.0 0.0 0.0 0.0 0 71

Thailand 584 1 697 8.15 561 1 200 5.67 1.9 4.0 2.3 5.0 24 497

Turkey 62 52 5.54 62 187 3.39 0.0 0.0 0.0 0.0 0 -135

Vietnam 8 100 17.76 0 100 17.93 0.0 0.0 0.0 0.0 8 0

Total 17608 41 917 5.99 16 314 40 938 6.44 2.0 3.8 2.5 4.7 2111 2737

1. Least-Squares growth rate (see glossary).

2. For total net trade exports are shown.

3. Data not available.

5

BIODIESEL PRODUCTION PROCESS

Figure 2.1: General steps in Biodiesel Production2

2 National Biodiesel Board (NBB)

Catalyst

Methanol

Vegetable Oils, Used

Cooking Oil, Animal Fats

Neutralizing Acid

Catalyst-Mixing

Transesterification

Neutralization

Purification

Crude Biodiesel

Phase Separation

Methanol

Recovery

Recycled

Methanol

Re-neutralization Methanol-Recovery

Quality Control Methyl Ester

Pharmaceutical

Glycerin

Glycerin Purification

Crude

Glycerin

6

2.2 OILSEEDS

In the simplest of terms, oilseeds are plant seeds that exhibit a tangible presence of natural

oil content. This oil is present within the cell walls of the seeds. The oil content usually

varies from 10 % – 45 % by weight of the seed kernel.

The use of oilseeds has been known to mankind for several centuries. Archaeologists have

demonstrated evidence that about 4000 years ago, ancient settlers in North America boiled

Hickory Nuts to extract its oil and used it as a food source. Closer home, groundnut oil,

mustard oil, soybean and sunflower oil etc. have long been used in India for their qualities

as food additives

Table 2.2 presents a brief overview of some of the oilseeds found around the world and their

common uses.

Table 2.2: Main Oilseeds and their Uses3

Oil source Uses

Palm The most widely produced tropical oil, also used to make biofuel

Soybean Accounts for about half of worldwide edible oil production

Rapeseed One of the most widely used cooking oils, canola is a variety (cultivar) of

rapeseed

Sunflower seed A common cooking oil, also used to make biodiesel

Cottonseed A major food oil, often used in industrial food processing

Palm kernel From the seed of the African palm tree

Peanut Mild-flavored cooking oil

Coconut Used in soaps and cooking

Olive Used in cooking, cosmetics, soaps and as a fuel for traditional oil lamps

2.2.1 Chemical Composition

With advances in chemical analysis, detailed scientific research could be carried out on

oilseeds to establish their chemical composition. Over the years, this composition has been

well documented. All oilseeds have been found to contain oil that is a structural

assimilation of triglycerides. These are various forms of fatty acids, such as mono/poly –

unsaturated acids, linked to glycerol through carbon bonds. The number and combination

of such fatty acids gives rise to oils of varying compositions and physical-chemical

properties. Table 2.3 (as shown on next page) takes a look at the chemical compositions of

some common vegetable oils:

3 Vegetable fats and oils. Available at: http://en.wikipedia.org/wiki/Vegetable_fats_and_oils

7

Table 2.3: Chemical compositions of some common Vegetable Oils

Copra Palm

Kernels Sunflower

seed Groundnut

Rapeseed Cotton

seed Sesame

seed Soya Bean

Palm Oil

High Erucic

Low Erucic

Oil Content % 65-68 44-53 25-48 45-55 - 36-50 15-24 44-54

Melting point C 23 to 26 24 to 26 -16 to -18 -2 C -9 -20 -2 to 2 -4 to 0 -23 to -20 33-41

Major Fatty Acid Composition %

Name Structure

Caproic C 6(0) 0-1 0-1 - - - - - - -

Caprylic C 8(0) 3-15 2-5 - - - - - - -

Capric C10(0) 6-15 3-5 - - - - - - -

Cauric C12(0) 41-56 44-51 - - - - - - - -

Myristic C14(0) 13-23 15-17 trace trace trace trace trace-2 trace trace

Palmitic C16(0) 4-12 7-10 3-10 6-16 1-6 2-6 17-29 7-12 7-12 42-46

Palmitoleic C16(1) - - 0-1 0-1 0-3 trace 0-2 trace trace -

Stearic C18(0) 1-5 2-3 1-10 1-7 0-3 1-3 1-4 3-6 2-6 4-5

Oleic C18(1) 3-12 12-19 14-65 36-72 8-50 50-66 13-44 35-50 15-33 37.4

Linoleic C18(2) 1-4 1-3 20-75 13-45 13-29 17-30 33-58 35-50 43-58 9-15

Linolenic C18(3) trace trace trace 0-1 5-16 6-14 0-2 0-1 5-11 -

Arachidic C20(0) trace trace 0-1 1-3 0-3 0-1 trace trace 0-1 -

Eicosenoic C20(1) trace trace trace 0-2 3-13 1-4 trace trace trace -

Behenic C22(0) - - 0-2 2-5 0-2 trace trace trace trace

Erucic C22(1) - - trace trace 5-60 trace-5 trace - - -

Docosadienoic C22(2) - - - - 0-2 - - - - -

Lignoceric C24(0) - - trace 1-3 trace trace trace - - -

8

Copra Palm

Kernels Sunflower

seed Groundnut

Rapeseed Cotton

seed Sesame

seed Soya Bean

Palm Oil

High Erucic

Low Erucic

Tetracosenoic C24(1) - - - - - 0-3 trace - - -

Specific Sample Composition

Saturated 91 85 17 17 6 - 34 15 15 53

Monosaturated 7 13 29 61 86 - 26 40 25 38

Polyunsaturated 2 2 52 22 8 - 40 45 60 9

Note: *Cotton seed oil also contains up to 1% cyclopropenoid fatty acids ** This denotes the number of carbon atoms followed in parenthesis by the number of durable bonds

9

2.2.2 Oilseeds for Biodiesel Production

Theoretically, all oilseeds could be extracted for their oil content which could then be

used for biodiesel production. In fact, back in the early days of the Internal

Combustion engine, Rudolf Diesel (Paris World Exhibition, 1900) ran his first

experimental diesel engine on peanut oil.4

Over the last century, the transportation fuel sector has witnessed unprecedented

growth, and with it an unparalleled consumption of fuel. But with rising carbon

emissions and the very real threat of catastrophic climate change, the demand for

alternatives has picked up once again.

Fortunately, research has established vegetable oil from oilseeds as a viable, less

polluting alternative to gasoline and petro-diesel. As compared to the latter, it is

known that straight vegetable oils, or SVOs, when used in conjunction with petro-

diesel, have better lubrication properties and lower emissions.

It is however important to understand that not all oilseeds are commercially viable as

feedstock for biodiesel production. Most oilseeds are valuable food components (as

cooking oil) and therefore cannot be weaned away for producing biodiesel.

However, they remain in demand for their environment friendly properties. This

predicament, a key component of the wide-ranging Food vs. Fuel Debate, led to the

search for even more alternatives.

2.2.3 Non-edible Oilseeds - Jatropha curcas and Pongamia Pinnata

The solution to the oilseed problem in India was finally narrowed down to two

species of hardy plants - Jatropha curcas and Pongamia pinnata. These oil-bearing

species find favor in the tropical/semi-tropical belt of Indonesia, Malaysia, India,

Southern China, Sub-Saharan Africa and parts of South America. The climatic conditions

here, combined with stretches of wasteland/degraded land, make the regions ideal

for Jatropha and Pongamia plantations.

In Europe and North America, temperate conditions and the unavailability of fallow

land has restricted the spread of these two plants. Instead, these regions depend

upon other oilseeds - rapeseed, soybean and sunflower seeds – and also employ

fresh and waste cooking oils for their biodiesel output.

2.3 AVAILABILITY OF OILSEEDS IN INDIA

India is a major producer and consumer of oilseeds. Mustard, sunflower, cottonseed,

copra and soybean are grown in large quantities in the country. Possessing vast areas

of arable land with good rainfall gives the country near-perfect conditions for the

4 http://www.jatrophabiodiesel.org/bioDiesel.php

10

cultivation of oilseeds. By USDA estimates, the country’s total oilseed output for FY

2009-10 was 34.9 million tons.5

In India, plants like Jatropha curcas and Pongamia Pinnata are preferred for biodiesel

production. Oils from these plants, as shown in Tables 2.4 and 2.5 conform closely

with the properties of conventional diesel.

Table 2.4: Properties of Jatropha Oil and Standard Diesel

Specification Standard specification

of Jatropha oil

Standard specification

of Diesel

Specific gravity 0.9186 0.82/0.84

Flash point 240/110°C 50°C

Carbon residue 0.64 0.15 or less

Cetane value 51.0 > 50.0

Distillation point 295°C 350°C

Kinematics Viscosity 50.73 cp > 2.7 cp

Sulpher % 0.13 % 1.2 % or less

Calorific value 9,470 kcal/kg 10,170 kcal/kg

Pour point 8°C 10°C

Colour 4.0 4 or less

Table 2.5: Properties of Pongamia Oil and Standard Diesel

Property Pongamia Oil Petroleum

diesel

Viscosity (cp) (30°C)52.6 5.51 3.60

Specific gravity (15°C/4°C 0.917 0.841

Solidfying Point (°C) 2.0 0.14

Cetane Value 51.0 47.8

Flash Point (°C) 110 80

Carbon Residue (%) 0.64 0.05

Distillation (°C) 284 to295 350

Sulfur (%) 0.13 to 0.16 1.0

It is however important to note that Jatropha is a crop that is easier to be grown on a

plantation-scale basis as compared to Pongamia. Studies have shown that Jatropha

requires less water, has a shorter gestation period and yields more seeds per hectare

5 USDA GAIN Report, India Oilseeds and Products Annual, 2010, http://gain.fas.usda.gov/Recent%20GAIN%20Publications/Oilseeds%20and%20Products%20Annual_New%20Delhi_India_4-15-2010.pdf

11

of plantation6. Moreover, several studies have been conducted on the suitability of

Jatropha oil for biodiesel production, while the same level of effort has not yet been

afforded to Pongamia.

Table 2.6: Differences between Jatropha and Pongamia7

Jatropha curcas Pongamia Pinata

Minimum gestation –only 1 year Gestation is more-about 6 years

A bushy shrub and by pruning the growing

height may be maintained to a practical limit for

harvesting and other operations

A large tree-block plantation in

agricultural lands is not preferred. Due to

its height seed collection becomes difficult.

Processing is comparatively easier due to low-

density oil, thus liked by processors.

Due to higher density processing is more

cumbersome comparative to Jatropha oil.

Even without transesterification the oil can be

utilized for running a standard diesel engine

Esterification is necessary

High oil content - upto 40 % Low oil content – upto 27 – 34 %

Seed yield and oil yield is higher per ha of land Seed yield is less comparative to Jatropha

This report will therefore discuss the prospects of Jatropha oilseeds for biodiesel

production in the country.

2.4 FEATURES OF JATROPHA CURCAS

Jatropha curcas is a tall bush/small tree up to 6 m in height and belongs to the

Euphorbia family. It is native to Central America and was probably distributed by

Portuguese seafarers via the Cape Verde Islands and former Portuguese Guinea

(now Guinea Bissau) to other countries in Africa and Asia.

Its seeds are toxic and they contain about 35% of non-edible oil. This oil can be used

for manufacture of candles and soap, in the cosmetics industry, for cooking and

lighting by itself or as a diesel/paraffin substitute. The species is planted as a hedge

(living fence) by farmers all over the world around homesteads, gardens and fields

because it is not browsed by animals and requires very little water.

Being rich in nitrogen, the seed cake is an excellent source of plant nutrients. Various

parts of the plant are of medicinal value, its bark contains tannin, the flowers attract

bees and thus the plant has honey production potential. Like all trees, Jatropha

removes carbon from the atmosphere, stores it in the woody tissues and assists in the

build-up of soil carbon.

6 Cultivation of Jatropha Curcas, http://biodiesel.nedfi.com/media/download_gallery/Cultivation%20of%20Jatropha%20curcas.pdf

12

2.5 PLANTATION AND SEED OUTPUT

Being a non-edible crop, Jatropha can be planted along the hedges of agricultural

patches or along roads, railway tracks, on fallow lands etc. It is recommended that

Jatropha seedlings be planted with the onset of monsoon with a boundary spacing of

3m X 2m around consecutive seedlings. In Hilly areas, pits may be dug of size 30cm

X 30cm X 30cm and supplemented with organic manure.7

On one hectare (10,000 m2) of planted area therefore, roughly 1665 seedlings can be

sown. The average seed yield of the plant, as evidenced by studies is shown below:

Table 2.7: Average Seed Yield of Jatropha

Year of Publishing Per Plant Yield (kg) Per Hectare yield (kg)

2nd year 0.5 – 1.0 1500

3rd year 1.0 – 3.0 2500

4th to 6th year 3.0 – 5.0 6000

7th to 10th year 3.5 – 5.5 6500

It can thus be seen that Jatropha has considerable potential for biodiesel in the

country and therefore appropriate efforts to optimize the expelling process of Oil

from it are required to be done.

13

Elements of Expelling Process

Until the eighteenth century, technology for oil extraction was limited to combined leverage

and the use of animal power. In the eighteenth century, wind and water power largely

replaced animal power to assist in oil extraction. Large wind-driven stamper mills became

popular in Europe.

In 1795, J. Bramah of England invented the hydraulic press for oil extraction. Oilseeds were

milled, cooked, and wrapped in filters cloths woven from horse-hair. The oilseeds wrapped

in filter cloths were manually loaded into perforated, horizontal boxes below the head block

and above the ram of the press. The boxes were pressed together using upward hydraulic

pressure on the ram. The oil was pressed out through the filter cloths surrounding the

oilseeds. The filter cloths and spent cake were manually removed from the hydraulic press.

The residual oil in spent cake was approximately 10%.

In 1801, the first cottonseed oil mill was constructed in the United States using hydraulic

presses. By the 1870s, technology had advanced to large hydraulic presses with up to 16

press boxes and up to 400 tons of force. German companies were producing hydraulic cage

presses, with rams pressing the oilseeds inside of vertical slotted barrels that did not require

filter cloths by late 1800s. By the end of the nineteenth century, hydraulic press oil mills

were the standard technology for oil extraction.

Alfred French (French Oil Mill Machinery Company, Ohio) was a pioneer in advanced

hydraulic press technology. Design innovations to his credit include automatic cake-

trimming machine for automating the sizing of the cakes prior to pressing, change valve

which allowed the hydraulic press to change pressures near the end of the pressing cycle to

squeeze additional oil, and two-pass pressing (Take final residual oil in cake below 5%).

Hydraulic press oil mills were in use till 1950s and have been mostly replaced with

continuous screw presses and continuous solvent extraction plants, both of which require

far less labor and can process at much higher rates. The olive oil industry is the only oilseed

industry still using hydraulic presses. This is possible because of the price premium paid for

natural olive oil, processed without the use of heat or chemicals. 7

7 Kemper, T.G., Chapter on Oil Extraction. Bailey’s Industrial Oil and Fat Products, Sixth Edition, 2005, John Wiley & Sons, Inc.

CHAPTER 3

14

Figure 3.1: Hydraulic Press8

Screw Press was invented in 1900 by Valerius D. Anderson in Cleveland, Ohio. It was a

radical departure and significant technological advancement over the hydraulic presses

being used at the time. The mechanical screw press used a vertical feeder and a horizontal

screw with increasing body diameter to impart pressure on the oleaginous material as it

proceeded along the length of the screw. The barrel surrounding the screw was slotted along

its length, allowing the increasing internal pressure to first expel air and then expel the oil

through the barrel. The expelled oil was collected in a trough under the screw, and the de-

oiled cake was discharged at the end of the screw. The primary advantage of the mechanical

screw press was that it allowed continuous oil extraction and could process large quantities

of oleaginous materials with minimal labor.8

Khan and Hanna (1983)8 state that the pressure, temperature, pressing time and moisture

content are the factors which affect oil yield during expression processing of oil seeds. They

also indicate that research is still needed to determine if these factors affect the screw-

pressing process in the same way and to the same extent as they do in a static pressing

operation. (Annexure 1).

8 Khan, L.M. and Hanna, M.A. Expression of Oil from Oilseeds-A Review. J. agric. Engng Res. (1983) 28.

15

Figure 3.2: Screw Press

Improvements in mechanical screw press design have been mostly limited to developing

materials of construction that extend wearing part life. Screw and barrel parts that once

lasted three months before requiring replacement may now last up to two years.

Additionally, mechanical screw presses have been built to much larger scale, going from

initial capacities of 5 tons per day up to present-day capacities of over 100 tons per day for

full pressing and over 800 tons per day for pre-pressing applications.

The key to full-press performance is to apply maximum pressure to a thin cross section of

the oleaginous material to squeeze out as much of the oil as possible. As a result, full presses

create tremendous heat. It is common for full presses to use water-cooled shafts and water-

cooled or oil-cooled barrels to dissipate the heat to maintain adequate internal friction and

pressure. 8

The disadvantages of expellers are listed as follows:

The press must operate continuously for at least eight hours; intermittent operation is

unsatisfactory.

Oil from an expeller contains more impurities than oil from a batch press and must be

filtered to obtain clean oil.

Maintenance costs are high and it requires skilled mechanics.

Another method for oil removal is solvent extraction, where a solvent is added to pre-

crushed seeds in which the oil dissolves. The oil can later be recovered from the solvent. In

industrial oil mills mechanical expression and solvent extraction are often combined to

obtain the highest yields. The oil recovery from mechanical extraction is limited to 90-95% of

the oil present in the seeds, whereas solvent extraction can yield up to 99%. Solvent

extraction is a complex, large scale solution involving dangerous chemicals.9

9 Beerens, P. and Eijck, J.V. Oil Pressing and Purification. In: The Jatropha Handbook. FACT Foundation. April 2010. Available at: http://www.fact-foundation.com/en/Knowledge_and_Expertise/Handbooks

16

Adriaans (2006)10 concludes that solvent extraction is only economical at a large scale

production of more than 50 ton bio-diesel per day. Furthermore he does not recommend the

conventional n-hexane solvent extraction because of environmental impacts (generation of

waste water, higher specific energy consumption and higher emissions of volatile organic

compounds) and human health impacts (working with hazardous and inflammable

chemicals). Using aqueous enzymatic oil extractions greatly reduces these problems as do

the use of supercritical solvents (mainly supercritical CO2) or bio-renewable solvents as bio-

ethanol and isopropyl alcohol.11

According to a study by Boateng et al. (2012)12, mechanical extraction method though low in

oil yield, upgrades the oil making it possess high useful energy to do work compared to

solvent extraction. Based on Thermodynamics, efficiency of Solvent extraction of J. curcas oil

was found to be 79% and 96% for Mechanical extraction. The pre-treatment of J. curcas seeds

for oil extraction was found to contribute to 24% of the total internal exergy destroyed for

solvent extraction processes and 66% for mechanical extraction. This indicates that, the pre-

treatment unit alone degrades quality energy in the J. curcas seeds before actual oil

extraction. When the pre-treatment unit processes are improved, mechanical extraction

would be more exergetically efficient. (Annexure 2)

Appropriate technology selection is mainly a trade-off between the acceptable complexity,

costs of technology and the required oil quality. Production scale is an important limiting

factor in the choice of technology. For small pressing capacities, in the range of 1-10 kg

seed/hr, ram presses and expellers are both suitable options. For pressing more than 10

kg/hr, hand-operated presses are no longer possible and expellers should be used.10

Henning (2000)13 stated that engine driven screw presses extract 75-80% of the available oil,

while the manual ram presses only achieved 60-65%. Oil extraction efficiencies calculated

from data reported in more recent studies are found to generally correspond to these ranges,

although the efficiency range of engine driven screw presses can be broadened to 70-80%.

This broader range corresponds to the fact that seeds can be subjected to a different number

of extractions through the expeller. Up to three passes is common practice. Pretreatment of

the seeds, like cooking, can increase the oil yield of screw pressing up to 89% after single

pass and 91% after dual pass.12

From the various sets of information available, it is seen that conflicting conclusions have

been drawn. It is therefore necessary to optimize the parameters through actual research

such that an acceptable set of data is available for operation of expellers in India.

10 T. Adriaans. Suitability of solvent extraction for Jatropha curcas. Eindhoven: FACT Foundation, 9 (2006) 11 Achten, W.M.J, et al. Jatropha bio-diesel production and use. Biomass and Bioenergy, Vol. 32, 2008 12 Boateng, C.O. et al., Comparative exergy analyses of Jatropha curcas oil extraction methods: Solvent and mechanical extraction processes. Energy Conversion and Management 55 (2012). 13 R.K. Henning. The Jatropha booklet—a guide to the Jatropha system and its dissemination in Zambia. (1st ed)bagani GbR, Weissensberg (2000)

17

3.1 PRE-TREATMENT

Oleaginous materials require varying degrees of seed preparation prior to the oil

extraction process. Seed cleaning, seed drying, size reduction, hull removal,

heating/drying, flaking, and extruding are all potential unit processes involved in

seed preparation.

3.1.1 Seed Cleaning

Foreign material is generally removed twice, once prior to storage and again as the

oleaginous material enters the continuous process for oil expelling to reduce machine

wear. The foreign material to be removed may consist of a combination of weed

seeds, sticks, pods, dust, soil, sand, stones, and tramp metal. The most common way

to remove stones and sand is by thresher or a (vibrating) sieve. The choice between

manual and mechanized sieving depends on production capacity.10

3.1.2 Seed Drying

The moisture of oleaginous materials often needs to be reduced to minimize

degradation in storage and to enhance the effectiveness of downstream unit

operations. For example, soybeans are often received at 13% moisture and need to be

dried to 10% moisture to facilitate hull removal.8

3.1.3 Size Reduction

Most oleaginous materials require size reduction prior to further processing.

Exceptions are canola, rapeseed, and corn germ, which are already sufficiently small

in size. For most oleaginous materials, they need to be broken into pieces 2 to 3 mm

across to enhance the downstream unit processes of hull removal, heating/drying,

and flaking.8

3.1.4 Rolling

Rolling a seed generally results in an improvement in oil extraction by increasing the

surface area of the seed while at the same time retaining channels for the flow of oil.

The flakes should be very fine and preferably thinner than 0.1 mm. Rolling before

processing in a bridge press is said to increase oil yields by 10% for palm kernel,

groundnut and sunflower.14

3.1.5 Hull Removal

The hull fraction is high in fiber content and low in oil and protein content. The

process of removing the seed coat of soybeans is commonly referred to as dehulling,

and the process of removing the seed coat from sunflower seeds and delinted

14 Ch 3: Oil extraction, Small Scale Vegetable Oil Extraction. Available at: http://www.appropedia.org/Original:Small_Scale_Vegetable_Oil_Extraction_5#Small-scale_oilseed_processing

18

cottonseed is commonly referred to as decortication. In both dehulling and

decortication, the process has two distinct stages. In the first stage, aspiration is used

to remove the lighter hull fraction from the heavier meats fraction. A certain amount

of small meats particles are also aspirated away with the hulls stream. In the second

stage of dehulling, the fine meats are separated from the hulls through various

means of hull agitation and screening.

Dehulling can be carried out at an elevated temperature and has the advantage of

fewer fine meats particles being aspirated away with the hull fraction in the first

stage of dehulling and, therefore, requires less separation of meats from the hull

fraction in the second stage of dehulling.8

3.1.6 Heating/ Drying

With the exception of cold pressing, all oil extraction processes require that the

oleaginous materials be heated and sometimes further dried before oil extraction. In

order to enhance the downstream unit operation of flaking, oleaginous materials are

typically heated in the range of 60–75°C temperature. By heating and softening the

oleaginous materials, it enables the oleaginous material to stretch and flatten in the

flaking operation with a minimum of fragmented particles being created.

Oleaginous materials are often heated to temperatures of 110–150°C temperature,

and dried to as low as 3% moisture. The high temperature decreases the viscosity of

the oil, making it easier to expel. The high degree of drying largely ruptures the

cellular structure of the oleaginous material as the internal moisture vaporizes and

expands. The low final moisture maximizes friction within the full press to maximize

internal pressure. These functions all improve de-oiling and allow residual oil in cake

to be minimized. Seeds can also be sun dried (3 weeks).8

3.1.7 Conditioning

Conditioning or 'cooking' oilseeds involves heating the oilseed in the presence of

water. The water may be that which is naturally present in the seed, or it may be

added. The changes brought about by conditioning are complex but include the

coalescence of the small droplets of oil, present in the seed, into drops large enough

to flow easily from the seed. In addition, higher processing temperatures improve oil

flow by reducing the viscosity of the oil.

Oilseeds are nearly always conditioned before large-scale expelling. Small-scale

expellers minimize the need for pre-treatment by using a relatively fast wormshaft

speed which shears the oilseed as it passes through the expeller and produces

frictional heating within the expeller barrel. This assists oil expulsion by raising the

temperature of the oilseed. However, even when using a small-scale expeller, oil

extraction will be assisted by heating and/or steaming the oilseed before expelling.

19

Heat treatment is essential for some seeds with a low fibre content such as

groundnuts; they must be heated and moisturized before expelling or the machine

will produce an oily paste instead of oil and cake.15

3.1.8 Extruding

Dry extruder can be used to enhance the performance of a full press. Dry extruders

use electrical power to generate internal friction to heat the product as high as 150

degree centigrade temperature. When the extruded product exits the dry extruder, it

is liquid-like in consistency with thorough cell rupture. The principle advantage of

dry extruder preparation is that no expensive stacked-tray cookers or steam boiler

are required, and the total capital investment for facilities under 100 tons per day in

size is significantly less than for traditional full-press.8

3.2 IMPORTANT PARAMETERS

When designing or installing a facility to press jatropha seeds it is useful to know the

main variables affecting the oil recovery and oil quality. Table 3.1 summarizes the

influence and impact of the variables. This information pertains to expelling process

in general and may not apply to specific cases. It is seen from this table, that a trade-

off between oil recovery, throughput and energy consumption per liter of oil is

required to be carried out vis-à-vis the design parameters of the press.

Table 3.1: Effect of Press parameters on Process Parameters10

Press Parameters Oil recovery Pressure Temperature Throughput Energy/ liter

RPM -

Restriction size

Seed treatments

Heating - -

Flaking -

Moisture content

Hull fraction

Boiling

* Upward arrows indicate increase of a variable and downward arrows indicate decrease

3.3 PARAMETERS AFFECTING OIL QUANTITY

The amount of oil that can be recovered from the seeds is affected by: 10

Throughput: the amount of material that is processed per unit of time (kg/hr).

Higher throughput gives lower oil recovery per kg of seeds, due to shorter

20

residence time in the press. Throughput can be affected by changing the

rotational speed of the screw.

Oil point pressure: the pressure at which the oil starts to flow from the seeds. If

seeds can, for example, be manipulated so that the oil point pressure is reduced,

it becomes easier to extract the oil.

Pressure: at higher pressure more oil is recovered from the seeds. However, the

higher pressure forces more solid particles through the oil outlet of the press.

This makes cleaning more difficult. Typical operating pressures for engine‐driven

presses are in a range of 50‐150 bar.

Nozzle size: smaller nozzle size leads to higher pressure and therefore higher oil

yield. An optimum should be found for each individual press.

Moisture content of the seeds: this is related to storage. An optimal moisture

content of 2‐6% was identified. Moisture content of > 8% should be considered

too humid and needs more drying.

Hull content of the seeds: This is a difficult variable. Ideally one would like to

press jatropha without its hull. However, the hull appears vital to pressure

build‐up inside the press. Removal of the hull would require less energy for

pressing and result in zero presence of hull fibers in the crude oil. Unfortunately

seeds without a hull turn into a paste inside standard expellers, which sticks to

the worm and keeps rotating along with it. Adaptation of the press is required to

increase the friction with the press chamber.

3.4 PARAMETERS AFFECTING OIL QUALITY

The oil quality is affected by: 10

Moisture content of seeds: according to fuel norms the water content in SVO

should be below 0.08%. High moisture content might also increase the formation

of FFA during storage.

Process temperature: the friction inside the expeller generates heat, which is

passed on to the oil and press cake. Above certain temperatures phosphor is

formed, which leads to carbon deposits on fuel injectors and combustion

chambers. For rapeseed oil, for example, the maximum temperature of the oil

during the process is 55‐60°C. For Jatropha the exact temperature at which

phosphor starts to dissolve in the oil has not yet been determined. A value

comparable to rapeseed is expected.

Hull content of the seeds: lower hull fraction in the seeds leads to lower

pressures and thus less hull fraction in the crude oil. Partial dehulling is a

direction for further investigation.

Pressure: higher pressure leads to higher temperature and more solid particles in

the crude oil.

21

Types of Expellers and their Design Features

Expelling has been an operation prevalent in India for several centuries and still continues to

support rural households. With the advent of the possibilities and benefits with biodiesel,

mechanized expelling has taken shape and India has in fact established a name for itself in

the manufacture of expelling equipments. The chapter discusses the various types of

expellers in use today and their key features.

4.1 TYPES OF EXPELLERS

Different categorizations can be made for presses:

Continuous operation vs. batch operation

Manually driven vs. engine‐driven, where for the latter a distinction can be

made between electrical engines and diesel engines

Cold‐pressed vs. hot‐pressed.

Most hand operated presses operate in batches. Ram presses use the combination of

piston and cylinder to crush the seeds and squeeze out the oil. Operation of the press

is easy and can be done manually. Expellers, on the other hand, can be operated in a

continuous way.

For rural applications in developing countries, both manual and small

engine‐powered presses are viable, depending on the location and the application.

Soap or medicinal oil can be made in small quantities with a hand press. In case of

fuel production processes, engine‐powered presses are more sensible.

The third distinction is between cold pressing and hot pressing. Cold‐pressed means

the temperature of the oil does not exceed 55‐60°C during the process. For hot

pressing, external heat is often applied to seeds or press and the temperature can

increase to over 100°C. Hand operated presses fall in the category of cold pressing.

Due to the higher pressures and friction in an engine driven expeller, cold‐pressing

temperatures will be exceeded. Cold pressing is most desirable for jatropha, although

it is not always possible due to high friction in the expeller.10

Another broad classification for expellers can be

Non-Motorized Expelling

Motorized Small Scale Expelling

Heavy Duty Industrialized Expelling

CHAPTER 4

22

4.1.1 Non-Motorized Expelling

Non-motorized expellers are simple mechanical devices that are hand/animal

operated. These equipments work on the principle of mechanical compression and

require no electricity or fuel for operation. They are fabricated using inexpensive

components that can often be manufactured locally.

Non-motorized expellers are used in rural settlements for domestic crushing of

oilseeds, such as copra (dried coconut meal), mustard, groundnut, soybean etc. Being

hand operated, these devices have low expelling capacities of about 2 - 5 kg/hr, or 20 – 30

kg/day.15

Types of Non-Motorized Expellers

Ghanis

Ram Presses

Screw Presses

4.1.2 Motorised Expellers

Motorized small scale expellers are complex machines that house several

components. Such expellers have a solid metal chamber that houses the heat-

treated/case hardened screw shaft which is used to compress oilseeds. The screw

shaft is driven by a gear box assembly, which is in turn draws power from an electric

motor or a standalone diesel engine set.

The types of small-scale motorized expellers are:

Motorized Single Presses (Ram presses): A variation to the hand-operated ram

presses that use an electric motor (or standalone diesel generator set) as a

power source.

Motorized Screw Presses: Instead of a ram piston, the seeds are crushed using a

wormshaft.

4.1.3 Heavy Duty Industrial Expellers

Mainstream industrial expellers are complex machines that are built to handle

several tons of feedstock while demonstrating continuous (uninterrupted) operation.

Although expensive to set up, industrial scale expellers are economical when

processing large amounts of oilseeds, and achieve good expelling efficiency.

Industrial expellers are assembled as multi-function units. Fig. 4.1 demonstrates a

typical unit manufactured by Guruteg Expellers, Ludhiana, India.

15 Principals of extraction, Minor Oil Crops, FAO Corporate Document Repository, 1992 http://www.fao.org/docrep/x5043e/x5043E03.HTM

23

Figure 4.1: A standard heavy duty industrial expeller16

A comparative analysis of these three categories of expellers is as under:

Table 4.1: Comparative analysis of different categories of expellers

Parameter Manual Presses Small Scale Industrial

Presses Heavy duty Industrial Presses

Feedstock

handling capacity

15 – 20 kg/hr

(0.4 – 0.5 TPD)

40 – 400 kg/hr

(1 – 10 TPD)

500 – 10,000+ kg/hr

(10 – 300+ TPD)

Auxiliary

components

None Decorticator, de-huller, pre-

steaming chamber

Decorticator, de-huller, pre-

steaming chamber, conveyor

and elevator assembly

Maintenance and

Repair

Minimal. Most

components can

be rectified or

replaced locally.

Wormshaft failure can be

addressed by skilled local

metal workers. Replacement

is expensive. Regular

maintenance requires no

special training.

Wormshaft failure and/or

gearbox failure may require

specialized attention. Regular

maintenance is facilitated to be

easy.

Expelling

efficiency

50 – 60 % of total

oil content

80 – 90 % total oil content 90 – 94 % of total oil content

Power

Consumption

- 5 – 30 HP Motors 30 – 150+ HP Motors

Labor Required 1 - 2 2 – 3 2 – 5

Floor Space

Requirement

10 – 15 sq. ft. 20 – 30 sq. ft (main expeller)

15 – 20 sq. ft (auxillary

equipments)

80 – 100 sq. ft or more

(including all equipments)

Equipment &

Installation cost.

USD 130 – 160 USD 2000 - 3000 USD 8000 – 15,000 or more

16 Guruteg Expeller, Ludhiana

24

4.2 GHANIS - TRADITIONAL INDIAN EXPELLERS

Ghanis are simple mechanical arrangements that have a central depression (mortar)

where the oilseeds are fed into. These are then crushed by a heavy overhead crusher

(pestle) that grinds down on the seeds while rotating (and partially revolving)

around the vertical axis.

Figure 4.2: Traditional Indian Ghani used for oil expelling

The grinding motion is achieved (usually) by employing cattle or buffaloes that carry

wooden beams fixed to the top of the pestle at one end, and to their harnesses at the

other. The oil seeps out of a hole at the bottom of the mortar while the seedcake left

behind is scooped out by hand.

There are several regional variations in designs which probably arose from the

nature of the oilseeds that were regionally available for crushing. A paper on use of

Ghani in India by Dr. Achaya is attached as Annexure 3.

4.2.1 Granite Ghani

The large granite Ghani of southern India has a capacity of crushing 35 to 40 kgs of

oilseeds/hour and requires two animals yoked side by side and two operators, one for

the animals and the other near the mortar. The load-beam is curved, very long and

rides on a strong outer groove on the mortar. These Ghanis have an operational life

of four to five years, after which the pit gets too worn out to be useful.

4.2.2 Wooden Ghani

The wooden Ghani of western India has a capacity of 8 to 15 kg. It has an oil outlet at

the base of the pit (which is kept plugged during crushing) and frequently has the

operator seated on the load-beam.

25

4.2.3 Bengal Ghani

The Bengal Ghani has a small capacity of only 5 to 10 kg per charge and is usually

used to crush a mixture of rapeseeds and mustard seeds. The pit is small and the

pestle is tall and has a stout base. The operation is prolonged so as to permit slow

enzymatic liberation of several pungent alkyl iso-thiocyanates in the warm, moist

conditions that prevail inside the pit. Punjab Ghanis are of similarly small capacities

but generally carry a short pestle.

4.2.4 Recent evolution in Ghani technology

Figure 4.3 shows motorized expellers that are

currently used at rural locations with access to

electricity or fuel supply to power the machines.

Modern Ghani units can press about 100 kg of oilseeds

in an average working day (TinyTech Expelling).

Figure 4.3: Crushing oil seeds using motorized Ghani

An example of the modern Ghani is the one produced by TinyTech Plants, Rajkot.

It has been developed by the manufacturer after

extensive research and incorporates several

improvements to maximize efficiency. A few details

of the machine are as under:

Power Source : 2 HP Motor @ 12 rpm

Power Transfer through : Reduction gearbox

Base frame dimensions : 600 mm X 600 mm

Construction Material : Iron and Steel

4.3 RAM PRESSES

Ram presses are mechanical compressors that have a piston worked by a hand-

operated lever. The piston presses down on the oilseeds that are housed in a

perforated cylindrical chamber. An adjustable choke at the outlet is used to regulate

the pressure on the seeds.

26

The most well‐known representative of this category is the Bielenberg ram press.

Based on an existing design of a ram press that was expensive, inconvenient and

inefficient, Carl Bielenberg made the design of his press that would be cheap,

durable, locally maintainable and easy to use.

These presses can be manufactured by local workshops in rural areas, leading to

good quality at an attractive price. The Bielenberg press was originally designed to

press sunflower seeds. It is applicable for Jatropha seeds as well, although with

reduced efficiency. The capacity is limited to 2‐3 kg/hr. At a recovery rate of 70‐80%

and an oil density of 0.918 kg/litre this means < 1litre/hr.10

Figure 4.4: Bielenberg Ram Press10

4.3.1 Efficiency and Expression data of Some Ram Presses

The original Beilenberg press required two individuals for operation. However the

design has since undergone several improvements. Today there are 5 – 6 more kinds

of hand operated ram press in use, primarily in rural Africa (eg. Benin, Zimbabwe,

Mali, Senegal etc.)17

A brief overview of these designs is presented in Table 4.2

17 J. Uziak and I. A. Loukanov: Performance Evaluation of Commonly Used Oil Ram Press Machines, Department of mechanical Engineering, University of Botswana, October 2007. http://www.cigrjournal.org/index.php/Ejounral/article/view/906/900

27

Table 4.2: Brief overview of designs

Ram Press Mass Piston Handle No. of Bushing Cage

(kg) Diameter Length operators shape

(mm) (m)

Bielenberg 100 50 2.00 2 Bronze Tapered

CAPU (BP-35) 60 40 1.70 1 Bronze Tapered

Camartec (BP-30) 40 30 1.00 1 None Straight

ApproTEC 90 32 1.67 1 Bronze Tapered

IAE 48 32 1.30 1 Boiler-

pipe

Straight

RAM-32 (JH32), (FI-32) +26 32 0.98 1 None Tapered

In an analysis conducted in the University of Botswana18, the operational efficiencies

of 6 manual ram presses were evaluated. Three different varieties of sunflower seeds

were used:

Variety 1 - PNR7225,

Variety 2 - PNR7369 (hybrid seeds), and

Variety 3 - Peredovik (open-pollinated seed)

The oil contents of the seeds chosen were:

Table 4.3: Characteristics of Seed Varieties

Variety Moisture Oil content Crude fibre Crude protein

content (%) (%) (%)

(%)

PNR 7225 (hybrid) 6 42 16 21

PNR 7369 (hybrid) 7 45 17 19

Peredovik (open pollinated) 5 45 13 23

Russian 4 (open pollinated) 7 - 10 35 18 24

Record (open pollinated) 8 41 16 20

The ram presses were evaluated for two requirements:

High Production – to evaluate maximum crushing capacity and,

High Expression – to evaluate maximum oil expelling capacity

28

Table 4.4: Results for High Performance Test for Varieties 1, 2 and 3

Press

type/

Hours per

55 kg

Litres/hour Litres per

55 kg

Expression Rate

(%)

Efficiency (%)

Variety 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

Camartec 6.8 4.7 5.6 1.8 2.6 1.7 12.3 12.2 9.4 20.8 20.7 15.9 49.5 45.9 37.9

CAPU-35 6.7 5.1 5.3 1.8 2.2 1.7 12.3 11.4 9.0 20.7 19.2 15.2 53.0 42.7 36.2

FI-32 5.2 4.6 6.6 2.0 2.4 1.5 10.5 11.0 9.9 17.8 18.6 16.8 42.3 41.3 40.0

Table 4.5: Results for High expression test for Varieties 1, 2 and 3

Press

type

Hours per

55 kg Liters/hour

Liters per 55

kg

Expression Rate

(%) Efficiency (%)

Variety 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

Camartec 12.7 11.2 10.2 1.2 1.3 1.0 14.6 15.0 9.7 24.7 25.4 16.5 58.8 56.4 39.2

CAPU-35 7.8 9.1 6.3 1.6 1.5 1.4 12.7 13.5 9.1 21.5 22.9 15.4 51.1 50.9 36.6

FI-32 8.3 12.1 10.6 1.3 0.9 0.9 11.2 11.4 9.4 18.9 19.2 15.9 45.0 42.7 37.9

The above tests illustrate the operational performances of the different models of

Ram Press. Further details can be seen in the complete paper attached as Annexure 4.

4.4 MECHANIZED PRESSES

Nearly all the mechanized presses that can be found on the market use a continuous

pressing process. Usually this involves an endless screw that rotates in a cage and

continuously kneads and transports the seed material from the entry funnel to a

nozzle where pressure is built up. Over the length of the screw the oil is expelled

from the seeds and flows from the side of the screw to a reservoir. All expellers can

be categorized as either ‘cylinder‐hole’ type or ‘strainer’ type.10

4.4.1 Principle of Screw Press

During the pressing process the seeds are fed into the seed hopper and then

simultaneously crushed and transported in the direction of a restriction (also referred

to as ‘die’ or ‘nozzle’) by a rotating screw (often called ‘worm’). As the feeding

section of the expeller is loosely filled with seed material, the first step of the process

consists of rolling, breaking, displacement and the removal of air from inter‐material

voids. As soon as the voids diminish the seeds start to resist the applied force

through mutual contact and deformation. The continuous transport of new material

from the hopper causes pressure to increase to a level needed to overcome the

29

nozzle. At this point the press is ‘in operation’. The built‐up pressure causes the oil to

be removed from the solid material inside the expeller.10

Figure 4.5: A standard small-scale screw press and its mechanical parts, showing the

wormshaft and driving gears

4.4.2 Cylinder‐hole type

In the ‘cylinder‐hole’ type, the oil outlet is in the form of holes at the end of the

cylindrical press cage (Figure 4‐7). The seed gets a rising compression in the direction

of the press head. The oil is pressed out of the seeds near the outlet holes and drained

from them. Special cavities near the nozzle prevent the cake/seed‐mix from sticking

to the screw. Otherwise, there would be no forward movement. The press cake is

pressed through changeable nozzles and formed to pellets. In most types of presses

the nozzle is heated to avoid blocking of the press cake. Cylinder‐hole type presses

exist for small capacities (up to approximately 200 kg/h seed). For different types of

oilseeds the press can be adjusted by changing the nozzle diameters and screw

rotation speed.10

Figure 4.6: Schematic of a Cylinder-hole type press10

30

4.4.3 Strainer Type

The strainer type press has an oil outlet over the full length of the press cage that

serves as a strainer. The strainer is actually a cylindrical cage built‐up of separate

horizontal bars or vertical rings arranged at a small interspacing. The spacing

between the strainer bars can be either fixed or adjustable. Strainer presses come

with various screw design although the principle of all screws is similar. The screw

diameter increases towards the nozzle thereby increasing the compression of the

solid material. Screws for continuous compression are made from one piece. For

some seeds, the oil recovery is higher after multiple compression steps. A screw with

multiple compression section can be used to create multiple compression stages to

increase oil outlet. For flexibility, subsections of different size and shape are often

available. Other presses are equipped with different screws.

During the flow of the seed through the press, the oil is drained via the strainer,

which surrounds the pressing space. The choke size can be adjusted to change the

pressure level and distribution. For several types of oilseeds, it is necessary to change

the gap size of the strainer bars (interspacing) where the oil comes out, to get an

optimal yield and cleanness of the vegetable oil. In addition the choke size and the

rotation speed should be adjusted when pressing different kinds of seed. Strainer

presses exist in a wide capacity range from approximately 15 kg of seed/hr to 10

tonnes of seed/hr.10

Figure 4.7: A schematic of a standard filter press10

31

Figure 4.8: Examples of a) Cylinder-hole type – Danish BT Press; b) Strainer type –

Sundhara Oil Expeller10

FACT foundation concluded that strainer presses are preferred over cylinder-hole

presses. In Table 4.6 the two expeller types are qualitatively compared in suitability

to press jatropha seeds.10

Table 4.6: Comparison between strainer and cylinder-hole press10

Attribute Cylinder hole press Strainer press

Throughput - ++

Ease of maintenance +/- +/--

Price +/- +

Oil yield +/- +

Robustness +/- +

Ease of operation - +

Wear resistance - +

4.5 COMMON MOTORIZED SCREW PRESSES

4.5.1 TinyTech Expeller

Figure 4.9: The Tinytech expeller with boiler and filter press

32

The Tinytech expeller is widely used for crushing groundnuts. It was designed with

the properties of groundnuts in mind which have low fibre content. This necessitates

pre-processing of the seeds and the expeller therefore comes with a boiler and a

cooker.18

4.5.2 Sundhara Expeller

The Sundhara expeller is a motor driven oil extractor with a worm as its key

component. This expeller was designed by German engineers by order of the

German co-operation (GTZ) to be implemented in villages in Nepal and to be

produced within the country.

Figure 4.10: Sundhara expeller from the side, visible is the cage composed

of iron bars with a worm inside

A prototype of the Sundhara expeller was sent to Mali for Jatropha oil extraction.

During the project time in 1993 another 6 expellers were imported from Nepal.19

4.5.3 The Sayari expeller

The Sayari oil expeller was developed by FAKT consulting engineers Dietz, Metzler,

Zarrate for use in Nepal. It was designed out of iron sheets instead of cast iron to

limit the weight of the heaviest parts to 40 kg. It is now built in Tanzania by

VYAHUMU Trust, Morogoro, and in Zimbabwe by POPA, Harare.19

18 Reinhard K. Henning: The Jatropha System, An integrated approach to rural development http://www.jatropha.org.za/Knowledge%20Base%20Files/The%20Jatropha%20Book%202009.pdf (Annexure 5)

33

Figure 4.11: The Sayari Expeller

The Sayari expeller is the same design as the Sundhara expeller, but it is produced in

Tanzania to extract oil from Jatropha seeds. Two private workshops produced the

press in Morogoro for a price of about Rs. 1,35,000 per unit, inclusive of the engine

(an electric motor or diesel engine). About 40 units of this expeller were produced.

An important aspect of this expeller is its maintenance, as the worm has to be

replaced regularly, usually twice a year.

4.5.4 Komet Oil Expellers

Komet Vegetable Oil Expellers are manufactured in Germany, whose range of

products covers small hand operated as well as industrial machines. According to

the product literature, Komet oil expellers feature a special cold pressing system with

a single conveying screw to squeeze oils from various oil-bearing seeds.

Figure 4.12: Sectional view of a standard Komet Expeller19

19 Kurki, A., et al. Oilseed Processing for Small scale Producers. ATTRA 2008. Available at: http:// attra.ncat.org

34

The machine operates on a gentle mechanical press principle that does not involve

mixing and tearing of the seeds. Virtually all oil-bearing seeds, nuts, and kernels can

be pressed with the standard equipment without adjusting the screws or oil outlet

holes.20

35

Current Expellers

Out of the multitude of expeller designs present in the world today, the report has so far

touched upon the ones used widely in India and in some rural regions of Africa. These

designs owe their popularity to the following guiding principles of expeller design:

Ease of operation

Crushing capacity and oil output

Cost of operation / Power Consumption

Ease of maintenance and repair and Cost of components

The following section discusses some of the common expellers in the market today.

5.1 SCREW PRESS – HAND OPERATED

TinyTech Plants, India is one of the leading manufacturers of small-scale rural

expellers. One of its designs for the hand-operated screw press is highlighted below.

The design was arrived at after several optimization tests, with the result that the

product today is lightweight, inexpensive and reliable in the long run.

Figure 5.1: A simple hand operated expeller (Rajkumar Agro) and its operational details

Key Features

Type of Press Light-weight screw press

Weight 6 Kgs

Dimensions 16" x 10" x 4.5"

Operation Mode Manual

Metal Mild Steel

Crushing Capacity 1- 2 kg/hr

Cost (INR) INR 5000

Cost (INR) USD 155

CHAPTER 5

36

5.2 SCREW PRESS - MOTORISED

The typical operational figures for small scale expellers are as following (for crushing

mustard/cotton/groundnut seeds):

Category 1

Crushing Capacity 1 – 5 TPD (24 hrs)

Motor Rating 3 Phase 5 – 7.5 HP

Screwshaft speed 1440 – 1450 RPM

A typical example of the above category is the Goyum 20 Oil Expeller.

Figure 5.2: Goyum 20 Oil Expeller

Some key features of this expeller are:

Exterior Dimensions (LXBXH) : 2185 X 685 X 1422 mm

Construction Material used : Cast Iron (Body and Base)

Gear Box : Single Reduction Spur Gear assembly

Screwshaft used : Case-hardened worm gear

Motor Rating : 3 Phase 7.5 HP @ 1440 rpm

Crushing Capacity : 3 TPD

Approximate Cost : 1200 – 1400 USD (INR 55,000 – 65,000)

37

Category 2

Crushing Capacity 5 – 10 TPD (24 hrs)

Motor Rating 3 Phase 20 - 30 HP

Screwshaft speed 1440 – 1450 RPM

An example of the above category would be the Goyum Model-100 Oil Expeller.

Figure 5.3: Goyum-100 Oil Expeller

Some key features of the Model-100 are:

Exterior Dimensions (LXBXH) : 2175 X 1200 X 2600 mm

Construction Material used : Steel (Body and Base)

Gear Box : Double Reduction, cast steel helical Gear assembly

Screwshaft used : Case-hardened worm gear with

hard face discharge and compression rings

Motor Rating : 3 Phase 25 HP @ 1440 rpm

Crushing Capacity : 8- 10 TPD

Approximate Cost : 2000 - 2500 USD (INR 95,000 – 115,000)

38

5.3 HEAVY DUTY INDUSTRIAL EXPELLERS

The operational characteristics of heavy-duty industrial expellers are as under:

Category 1

Crushing Capacity 10– 50 TPD

Motor Rating 3 Phase 30 - 100 HP

Example: Super Oil Expeller, Gobind Expellers, Ludhiana

The Super Oil Expeller screw press is suitable for crushing a wide variety of seeds –

cottonseed, sunflower, linseed, soyabean, groundnut seed etc. It also houses a special

crammer shaft that assists in optimal crushing.

Figure 5.4: Super Oil Expeller, Gobind Expellers, Ludhiana

Other key features of the equipment are:

Exterior Dimensions (LXBXH) : 3429 X 2159 X 3175 mm

Construction Material used : Cast Iron (Body and Base)

Motor Rating : 3 Phase 75 HP @ 960 rpm

Crushing Capacity : 30 – 40 TPD (Pre-press)

20 – 25 TPD (Full press)

39

Category 2

Crushing Capacity 50– 100 TPD

Motor Rating 3 Phase 30 - 100 HP

Example: Model 600, Goyum Expellers, Ludhiana

The model 600 is a high capacity screw press that has the following features:

Triple Reduction Gear Box with helical gears of cast steel and pinion shafts of

special steel. Gearbox aligned with all the bodies on a single fabricated base

Auxiliary Kettle for pre-cooking of seeds

Two chambers of Cast Steel, vertically hinged, each 36" long

Cake thickness can be adjusted without stopping the machine

Hard faced Worm Assembly, discharge ring and compression ring

Water cooled main wormshaft that can be withdrawn without disturbing the

gearbox

Has a Crammer Shaft for extra cramming of oilseeds

Some key specifications of the Model 600 are:

Exterior Dimensions (LXBXH) : 3429 X 2159 X 3175 mm

Construction Material used : Mild Steel (Body and Base)

Motor Rating (for expeller) : 3 Phase 100 HP @ 1440 rpm

Motor Rating (for kettle) : 3 Phase 20 HP @ 1440 rpm

Crushing Capacity : 50 – 60 TPD (Pre-press)

30 TPD (Full press)

Category 3

Crushing Capacity 100 – 200+ TPD

Motor Rating 3 Phase 30 - 100 HP

Example 1: Model 1500, Goyum Expellers, Ludhiana

The model 1500 is the top-end model of Goyum Expellers. It has all the features of

the previously cited Model 600, besides having the crammer shaft driven by a

separate 3 HP motor.

40

Figure 5.5: Model 1500, Goyum Expellers, Ludhiana

Some key specifications of the Model 1500 are:

Component Length Width Height Weight

Expeller (Crushing chamber) 4877 mm (16’) 1295 mm (7’) 1980 mm (6.6’) 1.5 tons

Kettle (for cooking seeds) 2134 mm (7’) 2134 mm (7’) 3180 mm (12.6’) 6 tons

Base Structure 3050 mm (10’) 3050 mm (10’) 2150 mm (7’) 1.5 tons

Construction Material used : Mild Steel (Body and Base)

Motor Rating (for expeller) : 3 Phase 170 HP @ 1440 rpm

Motor Rating (for kettle) : 3 Phase 20 HP @ 1440 rpm

Crushing Capacity : 140 - 150 TPD (Pre-press)

50 - 50 TPD (Full press)

Approximate Cost : 11000 USD

The manufacturer claims an expelling efficiency of 6 – 7% oil retention in seed cakes

after crushing.

Example 2: ZY32 – Hebei Nanpi Machinery Manufacture Co. Ltd.

ZY32 expeller is a Chinese high capacity unit useful for crushing a large number of

oilseeds such as sunflower, groundnut, castor seeds etc. It is manufactured by the

Hebei Nanpi Machinery Manufacture Co. Ltd, China.

41

Figure 5.6: ZY32 expeller from Hebei Nanpi Machinery Manufacture Co. Ltd.

A few important parameters of the unit are as under:

Component Length Width Height Weight

Expeller (Crushing

chamber)

4100 mm

(13.4’)

2270 mm

(7.45’)

3850 mm

(12.6’)

1.1 tons

Motor Rating (for expeller) : 3–phase 110 HP

Motor Rating (for kettle) : 3-phase 20 HP

Crushing Capacity : 220 - 260 TPD

It is important to note that as compared to Indian designs, the expelling efficiency for

the ZY32 stands at of 16 – 20% oil retention in seed cakes after crushing.

Also in the Chinese expeller, the entire screw is made from hardened high carbon

steel as compared to case hardened components for Indian equipments. Therefore it

cannot be repaired by welding as the high carbon content acts as a deterrent. The

expeller is thus costly to repair in case of screw failure as an entirely new screw

needs to be incorporated.

A few units of the ZY32 have been installed at a few plants in Karnataka, as it is

claimed to demonstrate very low power consumption.

42

Jatropha Oil Expellers

This chapter summarizes the work done specifically in designing Jatropha Oil Expellers

where parametric research studies have been carried out after fabricating machines with

specific designs. The focus of interest on Jatropha at present is in India and some African

countries where significant prospects for Jatropha expelling are expected. The reports from

where information for this chapter has been taken are reported in full in the Annexure. This

is to convey detailed information of such studies to future researchers and to those who

wish to manufacture expellers specifically for Jatropha seeds. It may be stated here that not

all results match. This means that the local factors will impact the designs of such machines.

During the discussions held with various manufacturers in India, it was consistently stated

by them that their existing machines with existing designs have been utilized for expelling

Jatropha seeds and no design changes whatsoever have been incorporated in their machines.

As and when large scale Jatropha expelling is required, it may be useful or even necessary to

consider the information provided in this literature for the optimization of the expelling

operation.

6.1 MINI OIL EXPELLER FOR JATROPHA AND PONGAMIA

This section is based on a study conducted at the Central Research Institute for

Dryland Agriculture, India (Annexure 6).20 In this work, a mini oil expeller was

fabricated to find out the effect of variation in compression ratio of the oil chamber

and speed of the screw shaft on oil recovery and energy consumption during oil

extraction of Pongamia and Jatropha seeds.

The modified oil expeller consisted of a separate arrangement for changing the

compression ratio. This was achieved by increasing the gap between the screw and

the inner surface of the oil chamber at the feed end. It facilitated the movement of

crushed cake towards the choke end along a shaft, whereas in a conventional

expeller, the shaft is tapered at the outer end. This unique arrangement increases

radial stress on the material.

It was also designed to work at variable shaft speeds. The barrel was made of a

number of single, circular mild-steel plates joined together by two, hollow mild-steel

rods passing through these plates. Between the plates lay 0.025 mm-thick

spacers/shims to facilitate flow of expressed oil during operation of the press. A

relatively large number of shims were provided in the plug section and the ram

20 Reddy, S.S., et al. Studies on the effect of compression ratio and speed on oil recovery and energy consumption in mini oil expeller for Pongamia and Jatropha seed oil expulsion. eNREE, Volume 7 (2), April-June 2010.

CHAPTER 6

43

section. This was necessary because maximum pressure was applied in this section.

The schematic diagram of the oil expeller is shown in following figure.

Figure 6.1: Schematic Diagram of Oil Expeller21

The main observations made in the study are shown in the following tables. It can be

observed that oil recovery rises with increase in compression ratio. This is because

increase in pressure on cell walls facilitates release of oil from both Pongamia and

Jatropha seeds. However, oil recovery in case of Pongamia seeds was found to

increase in the compression range of 14 to 18.5:1, till 45 rpm, and then fall for all

subsequently higher speeds. In case of Jatropha, maximum oil recovery of 29.1% was

obtained at 20:1 compression ratio and 45 rpm. Higher compression ratio in Jatropha

compared to Pongamia at maximum oil expelling efficiency can be attributed to the

harder outer coat in Jatropha.

Table 6.1: Interactive effect of speed and compression ratio on Oil recovery and SEC of

a) Pongamia Seeds; b) Jatropha Seeds21

Seep(rpm)

Compression ratio

14:1 15.5:1 17:1 18.5:1 20:1 21.5:1

Oil Reco. (%)

SEC (watt)

Oil Reco. (%)

SEC (watt)

Oil Reco. (%)

SEC (watt)

Oil Reco. (%)

SEC (watt)

Oil Reco. (%)

SEC (watt)

Oil Reco. (%)

SEC(watt)

25 20.55 425.67 20.86 425.00 23.12 369.33 24.77 349.33 25.37 312.33 24.05 365.00

35 22.24 440.67 23.01 416.00 24.29 355.00 26.39 328.33 26.38 297.33 24.82 378.33

45 23.30 410.67 24.71 408.33 25.26 349.00 28.24 310.00 29.07 288.33 26.91 327.00

55 23.72 408.33 25.67 385.67 26.62 332.00 26.92 308.33 28.14 310.67 25.32 345.67

65 22.04 420.67 24.03 411.67 24.78 360.67 26.35 315.67 25.65 325.00 24.13 355.67

Seed Variety: Commercial grade: Moisture content:14%; Oil content:36%

*SEC=Specific Energy Consumption

Seep (rpm) Compression ratio

44

14:1 15.5:1 17:1 18.5:1 20:1 21.5:1

Oil Reco.

(%)

SEC

(watt)

Oil

Reco.

(%)

SEC

(watt)

Oil

Reco.

(%)

SEC

(watt)

Oil

Reco.

(%)

SEC

(watt)

Oil

Reco.

(%)

SEC

(watt)

Oil

Reco.

(%)

SEC

(watt)

25 19.50 445.00 19.47 448.33 21.54 384.00 23.07 356.33 24.81 355.67 22.70 423.33

35 20.23 448.33 21.58 439.67 23.49 375.00 24.45 350.00 24.85 352.00 23.71 416.33

45 20.34 435.00 22.74 429.33 24.13 370.33 26.51 316.67 25.21 327.67 25.23 389.33

55 20.45 433.33 22.65 421.33 24.45 360.67 25.67 321.33 24.86 338.33 34.95 399.00

65 19.96 438.33 21.73 432.33 23.85 381.67 25.20 341.67 24.46 360.67 23.97 413.67

Seed Variety: Commercial grade: Moisture content:14%;Oil content:41%

*SEC=Specific Energy Consumption

6.2 SCREW-PRESSING OF JATROPHA SEEDS

This section draws from PhD thesis of Dr. P. Beerens submitted to Eindhoven

University of Technology in 2007 (Annexure 7).21 In this work, two distinct low

capacity screw presses were used - A Danish screw press (BT Bio Presse Type 50, BT

biopresser aps, Dybvad, Denmark) designed for smaller seeds like rapeseed and

sunflower but proved to run properly on the bigger Jatropha seeds, and a Sayari

expeller (Vyahumu Trust, Morogoro, Tanzania). The original design of Sayari

expeller (strainer press) known under the name Sundhara originates from India. It

was adapted to Tanzanian standards by engineers from GTZ in the early 90’s. In

Sayari expeller, transport sections and pressure cones are alternately positioned

along the worm shaft. Rotational speed of the Sayari expeller was 55 RPM powered

by a standard 5.5 kW electric motor.

Table 6.2: BT50 specifications22

Screw dimensions

Screw diameter 48.6mm

Screw length 160mm( groove),173 total length in contact with seed

Channel heuight H (Con…) 11.5mm

Channel width W 11 mm

Number of parallel grov 7( 6 full winding)

Flight thickness 5.75mm top, 11.6mm bottom

Angle 8 degrees

Cage diameter 50mm

Cage length 195mm

Other specifications

RPM 0-70

Engine nominal power 1.1kW

21 Peter Beerens, Screw-pressing of Jatropha seeds for fuelling purposes in less developed countries, Eindhoven University of Technology, August 2007.

45

Both screw press settings and properties of the Jatropha seeds were varied to get a

better understanding of the expression process and to find the optimal process

conditions. The variables considered include - Size of the restriction at the end of the

press chamber, rotational speed of the screw press shaft, moisture content, and hull

content of the seeds.

For the BT 50 all tests with respect to seed pre-treatment were conducted at standard

conditions which are 49 RPM, 100% hull and a restriction diameter 9mm. The

standard settings for the Sayari expeller were 55 RPM, 100% hull and a restriction

gap size of 1.8mm. These settings were selected as standard setting because they

ensured smooth running of the presses. All tests in the BT50 press were single pass,

meaning that only seeds were pressed and the press cake was not fed back for a

second run. Most tests in the Sayari expeller were dual pass tests. Because of the

higher residual oil content of the press cake from the Sayari expeller a second press

run was worthwhile.

6.2.1 Influence of RPM

A reduction in oil recovery with increased rotational speed was observed for BT50.

This effect is largely explained by the increasing throughput which implies reduced

residence time and thus less chance for the oil to flow from between the solid

material. The higher residual oil content in the material ensures that the viscosity of

the paste remains relatively low and therefore pressure build-up is also lower at

higher speed which again leads to less oil recovery.

Figure 6.2: Influence of screw speed for BT 50 a) Oil recovery and throughput; b) Energy

requirement22

Higher rotational speed requires more power and at the same time reduces

processing time. The negative slope of the upper line indicating energy input per

litre in Figure 5-2 c shows that the energy requirement is most strongly affected by

the reduction in processing time.

46

6.2.2 Influence of Restriction Size

Higher Oil recovery was observed for smaller restriction size in both BT50 and Sayari

Expeller. This can be attributed to increased pressure and friction. Obviously when

decreasing the restriction size the mixture inside the press experiences more

resistance when exiting the press cake outlet. Assuming the supply of input material

to stay more or less constant, increased compression close to the press cake outlet is

expected. The increase in throughput with decreasing restriction size can appear

conflicting at first sight. It might be contributed to better filling of the voids inside

the worm channel at higher pressure therefore enhancing the press’s performance.

Figure 6.3: Influence of restriction size on Oil recovery and throughput for a) BT50; b)

Sayari Press22

Although oil recovery is highest at smaller restriction size there is an operational

limit. The tightest setting of 0.6mm exceeded the operational limit of the Sayari press

resulting in severe jamming.

6.2.3 Influence of Moisture Content

Higher moisture content might cause increased deformability and reduced rupture

force. In addition emulsification or plasticizing effects occurring in the pressed

material at higher moisture levels reduce the viscosity and thereby decrease pressure

build-up. This pressure drop seems an appropriate explanation for the rapid decline

in oil recovery with increase in moisture content in the case of BT50 as shown in the

following figure.

47

Figure 6.4: Influence of Moisture Content on Oil recovery and throughput for a) BT50 press;

b) Sayari Press22

In case of Sayari Expeller, oil recovery after dual passing shows a slight decrease for

increasing moisture content. The effect of moisture is less than that for the BT50.

6.2.4 Influence of Hull Fraction

For BT50, when the hull content is reduced to 66% of its original value, it causes slip

in the feed section and the solid-oil mixture starts to stick to the worm. The result is a

sharp decrease in throughput which can even drop to zero.

The combined effect of a decrease in power consumption (expressed in Watt) and an

increase in throughput at comparable oil yield is increased energy efficiency of the

process (less kJ/litre) when hull fraction is reduced to 80%. Below a certain threshold

value between 66-80% hull the press performance is sharply reduced due to

deteriorating mixture conveyance.

Figure 6.5: Influence of Hull content on Oil recovery and throughput for BT50 press22

48

6.2.5 Influence of Seed Preheating and Cooking

The effect of seed preheating on oil recovery and throughout was found to be

negligible for BT50. Following table depicts the impact of cooking on oil recovery.

Table 6.3: Impact of cooking on Oil Recovery

Residual oil Oil recovery

BT 50

Normal 11.0% 79.2%

Crushed 11.9% 77.2%

Water 7022C 6.1% 89.0%

Water 80C 6.3% 88.7%

Sayari

Normal 6.9% 87.5%

Crushed 7.4% 86.4%

Water 80C 5.0% 91.2%

6.2.7 Conclusions

Moisture content has the strongest effect on oil recovery. Restriction size and rotational

speed of the screw are other influential parameters. The highest oil recovery measured

were 89% and 91% for the BT50 and Sayari press respectively. These values resulted

after one hour cooking in water of 70°C. Oil recovery values for untreated seeds under

standard circumstances were 79% and 87%. Important to note is that the Sayari

expeller requires dual passing of the material compared to single passing for the BT50.

Taking into consideration all the test results optimal oil recovery is expected at a

moisture content of 2-4% after cooking at 70°C, 100% hull content and the smallest

restriction size and lowest speed possible for a certain press type.

6.3 STUDIES ON PARAMETRIC STANDARDIZATION OF MECHANICAL

OIL EXPRESSION OF JATROPHA SEEDS

This section draws from PhD Dissertation of Dr. B.K. Yaduvanshi submitted to G.B.

Pant University of Agriculture & Technology, Pantnagar in 2008 (Annexure 8)23. The

objectives of the dissertation included standardization of parameters – seed moisture

content, effect of hull content in seed-kernel hull mixture and machine parameters

like wormset configuration and speed – for Jatropha seeds.

A MERADO make, 1 TPD mechanical oil expeller was selected for the experiments.

The technical details of the expeller are shown below. The expeller selected is

22 Yaduvanshi, B.R., Studies on Parametric Standardization of Mechanical oil Expression of Jatropha Seeds. PhD Thesis, G.B. Pant University of Agriculture and Technology, 2008.

49

basically designed for expelling oil from mustard seeds. It is powered by a 3-phase,

1440 rpm, 5.5 kW electric motor.

Figure 6.6: Technical Details of 1 TPD MERADO Make Oil Expeller23

Later in the expeller the configuration of the wormset was modified to study its effect

on extraction efficiency and additional data set collected is described in Sec 6.1.3.

This work was carried out at the Mechanical Engineering Research and Development

Organization (MERADO), Ludhiana centre of the Central Mechanical Engineering

Research Institute, Durgapur which is a constituent laboratory of the Council of

Scientific and Industrial Research, New Delhi. The main results of the study are

summarised in the following sections.

6.3.1 Seed Moisture Content

Oil could not be expelled from jatropha seeds at only initial seed moisture content of

7.3%. This indicates requirement to standardize level of seed moisture content for

adequate oil expression. Several experiments were designed to increase the seed

moisture using sprinkling, soaking and steaming processes at different temperatures.

The effect of different processes on Oil expelling efficiency, power consumption and

expeller throughput is shown in the following figures.

50

Figure 6.7: Efficiency of Oil Expression of Water Sprinkled, Water Soaked, and Steamed Whole Jatropha Seeds23

51

Figure 6.8: Specific Power consumption of Oil Expeller on Whole Jatropha Seed23

52

Figure 6.9: Expeller Throughput at different Seed Moisture content of Whole Jatropha Seed23

53

It is evident from the figures that there was higher expression of oil when seeds were

steamed as compared to soaking and water sprinkling. This may be attributed to

improvement in the oil flow through the seed material, reduced viscosity of oil

contained in the seed as well as caused volumetric expansion and rupturing of cell

walls which led to more free oil availability during the expelling process, because of

steaming process.

Overall, low as well as high moisture content in the seeds leads to reduction in

quantity of oil expelled, because at low moisture content seeds get burned in the

compression chamber and at high moisture content wormset can’t gain sufficient

grip on the seeds.

6.3.2 Seed kernel – Hull Mixtures

The observations on oil expression from different mixtures of seed kernel-hull of

jatropha seeds and at different moisture content are shown in the following figure. It

is evident from the figure that the oil expression increased with increase in moisture

content of mixture and when the mixture had 20 and 30 percent hull content; it was

highest (29.7 percent) at the kernel-hull mixture moisture content of 17.2 percent.

It was found during experiments that when only seed kernel were used, the oil could

not be expressed from the material despite it contained 61.1 percent oil. The reason

being, that a paste of kernels was formed inside the compression chamber of

expeller, which moved along with the wormset and got discharged from the expeller

outlet.

54

Figure 6.10: Efficiency of Oil Expression of Dehulled Jatropha Seeds under Different Moisture Content23

55

6.3.3 Modified wormset configuration

The effects of machine parameters like wormset speed and wormset configuration

were studied by conducting experiments with whole jatropha seeds. The

experiments were conducted at wormshaft speed of 35 and 42 rpm. Initially, 28 rpm

was also tested but there was inadequate forward motion of feedstock in the

compression chamber at this speed. Further, to observe the effect of wormset

configuration, the whole jatropha seeds were crushed using an original worm,

placing a modified spacer and putting a reverse worm in the worm assembly. The

main observations are summarised in following tables.

The wormset configurations consisting of original worm, modified spacer and

reverse worm were found to have no significant effect on oil expression from whole

jatropha seed. Higher wormset speed of 42 rpm resulted in reduced oil expression

because of reduction in retention time of feedstock in compression zone of expeller.

Table 6.4: Efficiency of Oil Expression under Different Wormset Configuration23

Parameters

Wormset Configurations

Original Worm

(Forward)

Modified

Spacer Reverse Worm

Worm Speed, rpm 35 42 35 42 35 42

Treatments T38 T39 T41 T42 T44 T45

Seed Moisture Content, % 18.5 18.5 18.4 18.7 18.5 18.3

Oil Extraction Efficiency,

% 73.0 68.7 74.0 71.6 74.2 72.0

6.3.4 Recommendation based on the experimental results

The oil expression from whole jatropha seed having initial seed moisture content of

7.3 percent is recommended for treatment with steam at 1050C for 15 minutes so that

the seed moisture content is raised to 18.2 percent. At this treatment

Oil expression was found to be higher i.e. 26.8 percent

Oil expression efficiency was found to be higher i.e. 73.3 percent.

Specific power consumption was the lowest i.e. 0.136 kW/kg

Expeller throughput was the highest (28.2 kg/h) at standard wormset speed of 35

rpm

Cost of oil expression was the lowest i.e Rs. 50.10/- per hour.

Cost of oil expression was found to be the lowest i.e. Rs. 1.80/- per kg seed.

Cost of oil expression was found to be the lowest i.e. Rs. 6.65/- per kg oil

expressed

56

6.4 PERFORMANCE TEST OF A SCREW-PRESS MACHINE FOR

EXTRACTING JATROPHA OIL

The Indonesian Center for Agricultural Engineering Research and Development

(ICAERD) developed a screw-press type of expeller that was modified from a

ground nut expelling machine made in China. The machine has a capacity of 100

kg/hour with engine diesel Yanmar 15.5 HP/2,200 rpm. Transmission system used

was V belt-pulley with rotational speed at pressing shaft of 30-50 rpm.

Considering two design parameters - rotational speed of shaft and clearance - as

crucial parameters in determining machine performance, a study by Harmanto et al.

(2009)23 aimed at obtaining optimal parameters for the press machine in order to

obtain maximum capacity and pressing efficiency. (Annexure 9)

Performance test was conducted as follows:

Rotational speed of shaft was varied with three rotational speeds, i.e., 45, 50, and

55 rpm, and three replications with materials of 25 kg dried jatropha seeds for

each replication. Several pulley sizes and gear reductions were used to control

variation of rotational speed of shaft.

Clearance (space between ring wall and press cylinder) was adjusted with three

types, i.e. 6, 7, and 8 mm because with clearance of 5 mm the machine did not

continuously function, even it was out of order. Each clearance treatment was

replicated three times with materials each of 25 kg dried jatropha seeds.

It is concluded that to obtain the maximum capacity and highest yield without

increasing yield loss of crude oil, screw-press machine should be set at configuration

with rotational speed of shaft of 50 rpm and clearance 6 mm. At this performance

condition, screw press machine had a capacity of 65 kg/hour, oil yield 28% (crude oil

weight to jatropha seed weight), and yield loss 1.3% (yield weight to jatropha seed

weight).

6.5 OPTIMIZATION OF MECHANICAL EXTRACTION OF JATROPHA

SEEDS

Experiments were carried out to optimise mechanical screw press (German screw

press type - Komet D85-1G), maximal capacity of material input was 25 kg/h,

powered by a 3.0 kW electrical motor, for Jatropha at Hohenheim University.24 The

effect of the independent variables such as screw speed and press cylinder on oil

23 Harmanto, A., et al. Performance Test of a Screw-Press Machine for Extracting Jatropha Curcas Seed into Crude Oil as an Alternative Energy Source. Indonesian Journal of Agriculture 2(1), 2009: 35-40. 24 Karaj, S. and Muller, J. Optimization of mechanical extraction of Jatropha curcas seeds. Focus Cropping and Machinery, University of Hohenheim. 2009.

57

recovery was compared. The variable tested parameter were the rotational speed (ω)

and press cylinder hole size. (Annexure 10)

Figure 6.11: Mechanical screw press for oil extraction and installed sensor, (a) feeding

hopper, (b) housing, (c) screw press, (d) oil outlet holes, (e) heating, (f) nozzle, (g) press cake

outlet, (i) cohesion zone, (h) oil collector, (k) coupling, (l) speed alternator, (M) motor, (T1-

T5) temperature sensors, (T5) temperature sensor (IR), (ω) rotational speed25

6.5.1 Conclusions

Oil recovery depends on the rotational speed of screw press (rpm) and the size of the

press cylinder holes. The chemical properties of Jatropha oil were found to be

varying with the change of pressing setups (rotational speed, press cylinder). The

optimum operation of the mechanical press could be identified by analyzing the

time, oil recovery, oil content on press cake and chemical properties such as;

kinematic viscosity and total pollution.

The recommended operation is the following setup: press cylinder holes P = 1 mm

and rotational speed 260 rpm.

6.6 GAS ASSISTED MECHANICAL EXPRESSION (GAME) TECHNOLOGY

FOR HYDRAULIC PRESS

This section is based on the PhD thesis of Dr. P. Willems submitted to University of

Twente, Netherlands in 2007.25 This work demonstrates general applicability of the

Gas Assisted Mechanical Expression (GAME) process for recovery of oil from

different oilseeds, including Jatropha, with high yields. (Annexure 11)

In GAME process, the oilseeds are saturated with supercritical CO2 before

mechanical pressing. The CO2 displaces part of the oil during the pressing and

therefore increases the oil yield. A lab scale hydraulic press was used to determine

25 Willems, P., Gas Assisted Mechanical Expression of Oilseeds, Universiteit Twente, Nederland. 2007.

58

the oil yields and expression rates that can be obtained for both conventional

expression and GAME expression under a wide range of process conditions. The

influence of pressure and temperature on the oil yield and rate of conventional

hydraulic expression of Jatropha was also examined in this work.

It is expected that an industrial scale application of GAME will be in an extruder,

since this is a continuous process and less problems are expected with containment

and dissolution of CO2. It is therefore desirable to have information of the

performance of an extruder suited for GAME. A mathematical model was also

developed in this study to make theoretical predictions about performance of such

an extruder.

6.6.1 Description of GAME process

In this process, CO2 is dissolved in the oil contained in the seeds before pressing.

After equilibration, the oil/ CO2 mixture is expressed from the seeds. It was

concluded that at the same effective mechanical pressure (absolute mechanical

pressure minus the actual CO2 pressure) the liquid content is the same in both

conventional and GAME press cakes. The liquid in the GAME press cake is saturated

with CO2 (which can be up to 30 wt% CO2), reducing the oil content compared to the

conventional cake by the same amount. The amount of this effect increases with

increasing solubility of the CO2 in the oil.

Furthermore, the dissolved CO2 reduces the viscosity of oil by an order of

magnitude, which increases the rate of pressing. After pressing, the CO2 is easily

removed from the cake and oil by depressurisation. During depressurisation of the

cake, some additional oil is removed by entrainment in the gas flow.

Figure 6.12: Principle of GAME Process26

59

6.6.2 Hydraulic Press

A schematic representation of the hydraulic press used in the experiments is shown

in the following figure.

Figure 6.13: Schematic representation of Hydraulic Press26

Seeds are placed on a sieve plate covered with fine wire mesh in a temperature

controlled (30-100 ±1 °C) pressing chamber with a diameter of 30 mm. Pressures up

to 100 MPa can be exerted by a hydraulic plunger. Most of the experiments were

performed with approximately 10 grams of seed at 40 °C with a pressing time of 10

minutes.

6.6.3 Influence of Pressure and Temperature

The yield was found to increase for all seeds, including Jatropha, with increasing

mechanical pressure, approaching a limit at higher pressures. Maximum yields were

higher for the dehulled seeds compared to hulled seeds since hull does not contain

significant amounts of oil and the fibre in the hull absorbs oil during the expression,

thereby lowering the overall yield.

Experiments were performed for all seeds including Jatropha at temperatures of 40,

80 and 100 °C and a constant mechanical pressure of 30 MPa. Significant influence of

temperature on the oil yield was found only at 100 °C. Around 100 °C cooking takes

place, which coagulates the protein and the oil globules.

60

6.6.4 Experiments to demonstrate GAME Process

In a typical experiment, 10 grams of seeds were placed in the press-chamber, after

which the piston was lowered on top of the seeds. The seeds were allowed to

equilibrate to the temperature of pressing for at least 30 minutes without mechanical

pressure exerted on the seeds. During this period, CO2 was allowed to dissolve in the

seeds at the required pressure.

Yields obtained with GAME were up to 30 wt% higher than conventional expression

at the same conditions (40 °C, 10-30 MPa effective mechanical pressure and 10 MPa

CO2 for GAME experiments). Yield increased significantly with CO2 pressure up to

10 MPa. At higher pressures the improvement was minimal.

Whereas hulled seed (linseed, rapeseed, palm kernel and jatropha) gave significantly

lower yields than dehulled seed (sesame, cocoa and dehulled jatropha) under

conventional conditions, the GAME yields for hulled and dehulled seeds were found

to be much closer together. During a conventional pressing operation, oil is absorbed

by the hulls. With GAME part of the absorbed oil is entrained in the CO2 during

depressurisation, because the absorption on the hulls is not very strong. The

entrainment increases the oil yield for hulled seeds to the same level as the oil yields

for the dehulled seeds. This opens up the opportunity to omit the dehulling step in

the industrial production of the oils without a significant loss in oil yields.

61

Site Visits

The activity of expeller design and manufacture in India is largely left to the manufacturers

themselves. Since India has had oil seeds for a very long time, expelling has been carried out

since then. The current designs of the expellers have largely been driven through the

experience of the manufacturers themselves. There does not appear to be any specific agency

in the country which has addressed the issue of expeller designs. It was therefore felt that

with the advent of Jatropha, the manufacturers might have addressed this requirement and

may have incorporated changes in their designs for this purpose. With this in mind site

visits were made to one manufacturer in Coimbatore and to several in Ludhiana. These two

cities apparently are the centres where expellers are made in very large numbers. A site visit

was also made to the MERADO centre in Ludhiana, which at one time had taken up large

interest in this subject.

This chapter briefly describes the site visits made in this connection and the discussions that

took place there. At the outset one thing became very clear, barring the brief interest taken

up by MERADO, no manufacturer in the country has any R&D facility or any design

capability. They have however been improving their product in terms of materials and

durability.

7.1 Site Visit 1 – Goyum Screw Press

Contact Person : Mr. Vinod Jain, Managing Director

Website : http://www.oilmillmachinery.com/

Brief Description

Goyum Screw Press was founded in 1971, to produce state-of-the-art oil machines

and equipments. Today the company is a leading manufacturer and exporter of Oil

Extraction Machines, Seed Processing Machinery, Filtration Section, Large Capacity

Expellers, Material Handling Equipment, Oil Expeller Spares, etc. The company is an

affiliated member of the prestigious Engineering Export Promotion Council of India

(EEPC). Their products have been accredited with ISO 9001:2000 certificate. They

have a wide customer base spread across USA, France, Belgium, Bulgaria, UK,

Canada, Australia, Nigeria, Ghana, Mali, Burkina Faso, Uganda, Tanzania,

Mozambique and New Zealand.

CHAPTER 7

62

Product Range

Goyum Screw Press is engaged in the manufacture and export of the following:-

Oil Extraction Machines

Seed Processing Machinery - Seed Cleaner and Decorticator

Filtration Section - Filter Press

Large Capacity Expeller

Material Handling Equipment - Mild Sheet Elevator and Screw Conveyor

Oil Expeller Spares - Gears & Pinions, Rose Down Gear Box, Hard Faced Worm,

Case Hardened Worm, Hard Faced Worm & Cone Point, Cage Bar & Cage Bar

Holder, Bronze Wheel, Pulley, Cast Steel Chambers, Duplex Pump

Oil Extraction Plants.

Key Points Discussed

In view of their considerable experience on the subject of Oil expellers, detailed

discussions were held with them. They indicated that usually double pressing of

seed cake is done, sometimes three times, to maximize oil extraction. The number of

passes depends on the type of seed. Typically, they are satisfied when the oil content

of the seed cake is about 7%. They have got actual measurements on this. They did

not have much experience on Jatropha and Karanj. However, they have done cold

pressing of Jatropha seeds in a small batch process a few times. They indicated that

“Jatropha seeds do not need too much softening, as doing so spoils the oil that comes

out”. Dehulling of seeds however is essential as it ensures that the expeller runs

smoothly and efficiently. Without dehulling extra oil would be retained in the seed

cake which would be a waste. Their comments pertain to routine seeds generally and

not Jatropha or Karanj particularly. They stress that it is critical to retail 10-15%

fibrous material in the seeds as it helps in obtaining better traction in the mill and

therefore better pressing. Fiber prevents excessive slipping of seeds in the crushing

chamber and “acts as a medium for the oil to drain out”. They did not show any

interest in solvent extraction of oil citing unfavorable economics for the process as

they “have learned”.

We asked them if they have done any measurements of power consumption in their

expellers at any time, they have not done so. We also asked them if Jatropha or

Karanj seeds need any design changes in the expellers. They said they have no idea

on that. They only used their existing expellers a few times for Jatropha. They have

not supplied any expeller for extraction oil from Jatropha.

Their approach is scientific in nature and they have brought out a brochure on theory

of Oil extraction which is attached as Annexure 12.

63

7.2 Site Visit 2 – Gobind Expeller Company

Contact Person : Mr. Amarinder Singh, Director Marketing

Mr. Gurpreet Singh, Director Sales

Website : http://www.gobindexpeller.com/index.htm

Brief Description

Gobind Expeller Company is known for break through and high efficiency in Oil mill

industry. It started its operation in 1943 in Lahore and first expeller was made in

1945 for Cottonseed crushing. Later on the company shifted its operation in

Ludhiana, where it started in 1968. In early 90’s the company penetrated in the

market of Africa, and later on in South East Asia and South America. And at present,

the company is one of the major share holders for exports of Vegetable Oil Mills from

India.

They manufacture complete range of oil mill equipments from preparation of seed to

filteration and refining of the oil. Their machineries can be used for seeds like Cotton

seed, Karanja, Sesame, Linseed and other oil seeds. The company has experience in

processing of more than 25 Oil seeds and fat bearing seeds and nuts available all over

the Globe. Working full time in this field, their Professional staff has expertise in oil

extraction of almost all the Oil bearing seeds.

Product Range

The Company has products ranging from

Seed Preparation Units (Seed Cleaner, Seed Cracker, Destoner, Copra Cutter,

Hammer Mill etc)

Oil Extracting Units

Oil Cleaning Units (Filter Press, Neutralizer Refinery, Polish Filter etc.)

Automation Units (Conveyor belt, Elevator)

Spare Parts

Key Points Discussed

They seem to have some experience of extracting oil from Jatropha a long time back.

After the initial experience there was no demand later. They stressed that it is

essential to subject Jatropha seeds to double-stage cooking before expelling. Doing so

helps regulate moisture content and improves oil output (contrary to views

expressed in previous site visits).

The manufacturer caters to customers who intend to set-up plants of a minimum of 1

Ton per Day (1 TPD). It indicated that below such capacities it is simply not

64

economical to go for a mechanized setup. The low process efficiency alone would be

a major hindrance. The efficiency has not been measured at any stage. They

explained that subsequent pressings are to be done on hot seedcake and not allow it

to cool.

They were supportive of Solvent Extraction as a viable new technology. It was of the

view that although it is expensive, solvent extraction could be carried out for large

plants (>200 TPD) immediately after pressing the seedcake once. This would ensure

good oil yields. For smaller applications, boilers (fed on seedcake as fuel) would be

workable. Depending on the size of installation however, adequate supplementary

fuel (wood pellets etc.) may have to used.

7.3 Site Visit 3 – Nitya Engineers

Contact Person : Mr. Sushil Singla

Website : http://www.oilexpellermachine.com/index.html

Brief Description

Nitya Engineers is the Oil expeller division of Nitya Enterprises. Incepted in 1992, the

company soon entered into the field of manufacturing high capacity expellers of

international quality. It is a reputed manufacturer and exporter of complete range of

oil mill machines with oil expeller, cookers, elevators, conveyors, boilers, filter

presses, seed cleaner, decorticators, etc. Major share of their revenues come from

overseas exports.

Some of their Machines have been designed and developed in collaboration with

mechanical Engg. Research and Development Organization, a unit working under

technology mission on oil seeds and pulses (Govt. of India).

Their screw presses / oil expellers can be used for extracting various types of seeds

such as Rapeseed, Sunflower, Cotton, Groudnut, Palm Kernel, Seasame, Coconut,

Castor, Neem, all kinds of edible and non-edible seeds, etc. For maximum extraction

of oil the company suggests that Cotton seed and soybean be crushed in a single

pressing while others may be pressed twice.

Product Range

Available in varying capacities, their product range includes:

Oil Extraction Machinery

Seed Preparing Machines

Oil Filtering Machines

Material Handling Equipment

65

Industrial Chains

Spare Parts for Expellers

Key Points Discussed

During discussions no specific information concerning Jatropha or Karanja expelling

was available with them. They felt that Jatropha seeds can be expelled using their

current designs.

7.4 Site Visit 4 – Mohit International

Contact Person : Mr. Kumar N. Riat / Mr. Joginder Pal/ Mr. Hira Singh

Website : http://www.expellermachine.com/

Brief Description

Mohit International was established in 2006 and their major market is in East/

Middle Africa. They are having a client base in more than 28 countries which

includes U.S.A., Canada, Australia, U.K., France, Bulgaria, Belgium, Germany, Mali,

B.Faso, Sudan, Nigeria, Sri Lanka,Tanzania, Uganda, Malaysia, etc.

Their oil mill plants / oil extraction plants / screw presses can be used for extracting

various types of seeds such as Rapeseed, Sunflower, Cotton, Groundnut, Palm

Kernel, Sesame, Coconut, Castor, Neem, all kinds of edible and non-edible seeds, etc.

Product Range

The Company has a complete range of Oil Mill Machinery and Oil Extraction

Machinery which includes Oil Expeller, Filter Press, Seed Cleaner, Hammer Mill,

Copra Cutter, Boiler, Material Handling Equipments, Neutralizer, etc.

Key Points Discussed

During discussion, again, only routine information came out. They also did not have

any experience of Jatropha or Karanj. Their expellers had provision for adjusting

crushing zone clearances, which however has not been applied by any of their

clients. They also felt that steaming is necessary for most seeds, for this purpose

‘even hot water thrown over them is sufficient’.

The company had extensive sheet metal working capability. They seem to specialize

on a robust quality of manufacturing and were proud of the fact that their machines

do not break down.

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7.5 Site Visit 5 – Guru Teg Engineering Company

Contact Person : S. Palwinder Singh Grewal

S. Gurpreet Grewal

Website : http://www.gurutegexpeller.com/index.html

Brief Description

Guru Teg Engg. Co. (A group of Industries) is engaged in manufacturing &

exporting quality oil machinery and components since 1965. Besides popularity in

Indian Market, their products are being exported to many countries like Zimbabwe,

Zambia, Burkina Faso, Mali, Dar-E-Slam, Kenya, Dominican Republic etc. So far, the

Company has installed approximately 10,500 machines in India and abroad. They are

the only manufacturers in India for 10-TPD Modern Oil Expeller developed by

MERADO Center, Ludhiana, which was supplied to all the State Federations and are

reported to be working efficiently on the website of the company.

Product Range

The products of the company includes

Oil expeller machines

Filters / Feeding pump (Filter Presses, Oil Feeding Pump)

Other products (Neutralizer Refinery, Coal - Wood - Oil – Fired, Conveyor /

Elevator)

Expeller spare parts (Bush, Gear, Pinions, Sleeve)

Key Points Discussed

During discussions it was explained that most State Government Agencies have

bought oil expellers from them. But they directly have no experience of expelling oil

from Jatropha. They also felt that since no complaints have come from the field, their

machines should be working satisfactorily. They also felt that steaming has to be

carried out as it reduces energy consumption in expelling as well as throughput

capacity of the machines. They had no views about water content in the seeds for

efficient expelling.

7.6 Site Visit 6 - MERADO

Contact Person : Commander V.R. Dahake, Scientist-in-Charge

Website : http://www.cmeri.res.in/abt/merado.html

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Brief Description

The Central Mechanical Engineering Research Institute (CMERI) was established in

1958 under the aegis of CSIR at Durgapur. To address industrial needs of Northern

Region Mechanical Engineering Research & Development Organization (MERADO),

Ludhiana was set up in 1965 as an extension centre of CMERI. MERADO has

supported local industry with state of art innovations in the area of mechanical

engineering. It has contributed towards boosting industrial growth in the region.

Key Points Discussed

MERADO has had experience of conducting actual data generation form expelling

operations including energy consumption, and optimization of expelling parameters.

The work done by MERADO with reference to expelling of Oil is contained in a note

prepared by them and given to us for the purpose of inclusion in this report. The

note is attached as Annexure 13. Discussions with them brought out that:

Steaming or cooling of seeds is important to weaken and rupture the cell walls in

seeds such that oil release can be affected by milder crushing. This also removes

excess moisture from the seeds

In this context, steaming is a better option, than (dry) cooking, as it adequately

moisturizes the seeds. They mentioned that 17% by weight moisture content is

ideal for oil seeds (not Jatropha or Karanj). Thus also increases process efficiency.

They had done work on energy consumption in expelling operations, but that

data was for other seeds.

On enquiring about net energy consumption of oil expelling, with or without

steaming, they “felt” that steaming has to be done. When asked about the

optimum time and temperature for steaming, they had no exact answers, but felt

that about 10 minutes in super-critical steam (just above 100 degree Celsius, may

be 110 degree Celsius) would be sufficient.

We particularly asked them if they were capable of doing some specific work like

energy consumption, expelling efficiency of different design/ brand of expellers,

etc., they gave positive answers. But, they indicated, that they cannot take up any

new projects as they already had more work than they could carry out with the

staff available.

They have scientific publications in this area, copies of which were not readily

available.

They were sure that solvent extraction is a good technology as it will remove all

the oil, but parameters like how much pulverization, etc., has to be done, has not

been worked out. The economies of solvent extraction have to be accurately

assessed. This will be highly related to the price of oil.

It was felt that a more detailed discussion with them at a later date would be

useful. They agreed to that. Consequently, another visit was made to them. They

were very kind to establish our interaction direct with Dr. B.K. Yaduvanshi who

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completed his PhD thesis titled ‘Studies on Parametric Standardization of

Mechanical Oil Expression of Jatropha Seeds’ under the supervision of Dr.

Kundu in MERADO. As a result, we could get in touch with him and take his

permission to reproduce his dissertation, which is given as an annexure.

69

Some Recent Publications on Oil Expelling

This chapter gives information of some recent research activity and the consequent

publications in the area of expelling of oil from the seeds. This information is expected to be

of interest to future activity in this area. The topics covered in this section include design of

Jatropha expellers, pre-treatment requirements for Jatropha and other seeds, design

innovations in expelling oil from the seeds, comparisons of oil expelling from mechanical

and solvent extraction processes and some others.

8.1 OPTIMIZING MECHANICAL OIL EXTRACTION OF JATROPHA

CURCAS L. SEEDS WITH RESPECT TO PRESS CAPACITY, OIL

RECOVERY AND ENERGY EFFICIENCY

Karaj, S. and Muller, J., University of Hohenheim, Germany

Industrial Crops and Products, Volume 34, Issue 1, July 2011

The objective of this study was to optimize the mechanical oil extraction of Jatropha

curcas seeds by increasing the efficiency of oil recovery and decreasing oil residues

in press cake. The experiments were carried out with mechanical screw press type –

Komet D85-1G. Four setups were created by parameter combination of two

different screws (16 and 21.5 mm choke ring size), with two different press

cylinders (1 and 1.5 mm bore size), three different nozzles (8, 10 and 12 mm nozzle

diameter) and three rotational speeds (low, medium and high). Oil recovery

reduced when rotational speed increases for all setups; highest oil was 89.4%

(m/m). The oil recovery was increasing when energy input increased and

decreasing when seed material throughput increased. The relations between

energy input and seed material throughput followed a strict pattern, which

correlated with oil recovery. This correlation can be used for determining the

optimal operation parameters.

8.2 OIL EXPRESSION FROM JATROPHA SEEDS USING A SCREW PRESS

EXPELLER

R. C. Pradhan, et al., Institute of Agricultural Sciences, Banaras Hindu University

Biosystems Engineering, Volume 109, Issue 2, June 2011

Experiments were conducted to determine the effects of moisture content, cooking

temperature, and cooking time on the yield of oil mechanically expressed from

Jatropha seed using a screw press expeller. A maximum oil recovery of 73.14% was

obtained when Jatropha seeds were conditioned to a dry basis (db) moisture level

of 9.69% and cooked at 110 °C for 10 min. Screw press oil recovery, residual oil,

CHAPTER 8

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pressing rate, and oil sediment content were measured at different moisture contents

for uncooked and cooked seed. At optimum processing conditions, oil recovery from

cooked seed was 7% higher than that of uncooked seed. Pressing rate decreased

from 30.92 to 29.5 kgh−1 and 31.38 to 29.87 kgh−1 for cooked and uncooked seeds,

respectively, where as sediment content increased from 4.27 to 7.86% and 4.02 to

5.27%, respectively, as moisture content decreased. Oil expressed under the

processing conditions investigated was of acceptable quality.

8.3 PHYSICAL PROPERTIES OF JATROPHA CURCAS L. KERNELS AFTER

HEAT TREATMENTS

Sirisomboon, P. and Kitchaiya, P., King Mongkut's Institute of Technology, Thailand

Biosystems Engineering, Volume 102, Issue 2, February 2009

The drying characteristic and physical properties of kernels of Jatropha curcas L.

after heat treatments were investigated. The treatments included drying at three

different temperatures (40, 60, and 80 °C) and steaming. The drying characteristics

studied included the relationship of moisture content, moisture ratio, and drying rate

to drying time. The best fit for all parameters was the logarithmic model. Important

physical properties of the kernels were measured. The kernels contained moisture

3.78, 4.01 and 2.82% wet basis at 40, 60 and 80 °C, respectively. The sphericity of

dried kernels was 0.65–0.66 and 0.53 for steamed kernels. The bulk densities of dried

kernels and steamed kernels were 403–513, and 509 kg m−3, solid densities were

951–971 and 1082 kg m−3, porosities were 46.00–59.31 and 52.86%, and specific

surface areas were 177–241 and 154 m2 m−3, respectively. The static coefficient of

friction and angle of repose of the steamed kernels were the highest because of their

half section shape, lower sphericity, more viscous surface and soft texture. Drying at

80 °C gave the highest oil yield at 47.06% and the highest acid value. Drying at 40

°C gave a lower oil yield at 36.83% but the lowest acid value. Oil yield of steamed

kernels was very low (18.13%). The temperature of the drying process had a minor

effect on viscosity and ash content but had a significant effect on free fatty acid

content and acid value. The viscosity of the kernel oil was 33.91–34.53 cSt at 40 °C.

8.4 HYDRAULIC PRESSING OF OILSEEDS: EXPERIMENTAL

DETERMINATION AND MODELING OF YIELD AND PRESSING

RATES

Willems, P., et al., University of Twente, Netherlands

Journal of Food Engineering, Volume 89, Issue 1, November 2008

The influence of pressure, temperature and moisture content on the oil yield and rate

of conventional hydraulic expression of sesame and linseed is discussed as well as

the influence of pressure and temperature for rapeseed, palm kernel, jatropha and

dehulled jatropha. Yield increased with increase in pressure and with increase in

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temperature. For both sesame and linseed maximum oil yield was obtained at a

moisture content of about 4 wt%. Maximum yields obtained were 45–55 wt%

(oil/oil) for hulled seeds (linseed, rapeseed, palm kernel and jatropha) and 70–75

wt% (oil/oil) for dehulled seeds (sesame and dehulled jatropha). Rate of

expression increased with an increase in temperature and a decrease in moisture

content. Furthermore, the rate of pressing was described by the Shirato model. The

increased creep, and thus decreased rate of pressing, observed with increased

moisture content was satisfactorily described by the Shirato model.

8.5 DEVELOPMENT OF A SMALL CAPACITY DOUBLE STAGE

COMPRESSION SCREW PRESS FOR OIL EXPRESSION

Singh, J. and Bargale, P.C., Indian Institute of Sugarcane Research (ICAR), Lucknow

Journal of Food Engineering, Volume 43, Issue 2, February 2000

Mechanical pressing of oilseeds is the most widely used method for oil expression in

the world. However, the mechanical oil expellers (screw presses) employed for this

purpose leave about 8–14% of the expressible oil in the deoiled cake, so that a large

quantity of edible oil is not available for human consumption. To improve the

efficiency of oil recovery, a modified oil expeller was designed and developed

based on a novel principle of single feed double stage compression.

An evaluation of the performance of the developed expeller with moisture

conditioned rapeseed samples indicated that in two passes it recovered over 90%

of the available oil at a moisture content of 7.5% (w.b.). This is in contrast to

normally required 3–5 passes in conventional oil expellers for an oil recovery of

about 80%. The throughput capacity of the expeller was 25 kg/h while its effective

capacity (two passes) was found to be 15 kg/h. The maximum barrel temperature

was 70.3°C which assured production of a good quality oil, and the deoiled cake and

the specific energy requirement was 0.05 kWh/kg of feed for the optimized pressing

conditions. An economic analysis indicated that the developed screw press could

profitably be used for small-scale processing of rapeseed in rural areas of India.

8.6 TWIN-SCREW EXTRUDER FOR OIL PROCESSING OF SUNFLOWER

SEEDS: THERMO-MECHANICAL PRESSING AND SOLVENT

EXTRACTION IN A SINGLE STEP

Kartika, I.A., et al., FATETA-IPB, Indonesia

Industrial Crops and Products, Volume 32, Issue 3, November 2010

A new application of twin-screw extruder as a machine to conduct a thermo-

mechanical pressing and a solvent extraction of sunflower oil in a single step and

in a continuous mode was studied. Experiments were conducted using a

CLEXTRAL BC 45 co-rotating twin-screw extruder and whole sunflower seeds with

72

fatty acid methyl esters as a solvent. The influences of screw rotation speed (SS), feed

rate (QS) and solvent-to-solid (S/S) ratio were examined to define the best

performance of the oil extraction yield, the oil quality and the specific mechanical

energy.

Generally, the screw rotation speed, feed rate and solvent-to-solid ratio affected oil

extraction yield. An increase of oil extraction yield was observed as screw rotation

speed and feed rate were decreased, and solvent-to-solid ratio was increased. In

addition, oil extraction yield increased as screw rotation speed and feed rate were

simultaneously increased to QS/SS ratio of 0.2. Highest oil extraction yield (98%)

with best cake meal quality (residual oil content lower than 3%) was obtained

under screw rotation speed of 185 rpm, feed rate of 30 kg/h, and solvent-to-solid

ratio of 0.55. Furthermore, the operating parameters and solvent-to-solid ratio

influenced energy input. A decrease of screw rotation speed and feed rate followed

by an increase of solvent-to-solid ratio increased energy input, particularly specific

mechanical energy input.

8.7 GAS ASSISTED OILSEED PRESSING

Voges, S., et al., Hamburg University of Technology, Germany

Separation and Purification Technology, Volume 63, Issue 1, October 2008

Recently oils from rapeseed and soybeans have gained increased importance in the

alimentary sector and as regenerative energy source. Therefore, new technologies for

enhanced oilseed expression are becoming increasingly interesting. In conventional

seed oil production oil is recovered by mechanical solid–fluid separation using a

screw press and/or by continuous solvent extraction with hexane (M. Bockisch,

Handbuch der Lebensmitteltechnologie: Nahrungsfette und -Öle, Verlag Eugen

Ulmer, Stuttgart, 1993, M. Bockisch, Fats and Oils Handbook, AOCS Press, Illinois,

1998). The new process of gas assisted oilseed pressing is a mechanical solid–fluid

separation aided by the application of a dense gas. The gas is contacted with the

oilseed before or during pressing in order to achieve lower residual oil contents.

Different experimental studies could demonstrate the effectiveness of gas assisted oil

pressing, especially using carbon dioxide. In uniaxial pressing experiments oil yield

could be increased from 27% to as much as 71%. Against this background the

omission of the solvent extraction step becomes a worthwhile option. It has been

attempted to prove theoretically and experimentally the predominant effects, which

can be divided into dissolution related and gas flow related effects. It became clear

that the dominance of one mechanism or another depends on processing conditions,

particularly residence time and dimension of the press cake.

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8.8 GAS ASSISTED MECHANICAL EXPRESSION OF COCOA BUTTER

FROM COCOA NIBS AND EDIBLE OILS FROM OILSEEDS

Venter, M.J., et al., University of Twente, Netherlands

The Journal of Supercritical Fluids, Volume 37, Issue 3, May 2006

The current methods used to recover high quality oil from oilseeds have low yields

(mechanical expression, aqueous extraction), require the use of toxic chemicals and

rigorous purification processes that can reduce the quality of the oil (solvent

extraction with hexane) or are unsuitable for the recovery of commodity oils due to

the low solubility of plant oils in environmentally benign solvents (supercritical

extraction with CO2). Gas assisted mechanical expression (GAME) utilises the

much higher solubility of supercritical CO2 in the oil to enhance the extraction

yields of mechanical expression. GAME experiments with cocoa nibs were

performed at 40–100 °C, CO2 pressures of 0–20 MPa and effective mechanical

pressures of 20–50 MPa. The maximum yield with conventional expression (71.8%)

was obtained at a mechanical pressure of 50 MPa and a temperature of 100 °C. It is

shown that GAME has a substantially higher yield than conventional mechanical

expression for the recovery of cocoa butter from cocoa nibs, with the highest yield

(87.1%) obtained at 100 °C, a CO2 pressure of 10 MPa and an effective mechanical

pressure of 50 MPa. The cocoa butter yield increases with increasing CO2 pressure

until 10 MPa but remains almost constant for higher CO2 pressures. In contrast to

conventional expression GAME also allows the recovery of cocoa butter from cocoa

nibs at temperatures below the melting point of pure cocoa butter. The cocoa butter

produced with GAME was found to be unfractionated and is therefore of the same

quality as mechanically expressed cocoa butter. Experiments with linseed and

sesame seed show that GAME performed at 40 °C with 10 MPa CO2 also results in

an increased yield of oil (71.8–83.8% for linseed, 74.3–80.2% for sesame seed) when

compared to the yield obtained with conventional mechanical expression

performed at 40 °C (38.5–45.7% for linseed, 60.1–65.6% for sesame seed). From these

results it is concluded that GAME offers a promising process for the recovery of

high-quality vegetable oils at high yields.

8.9 OIL EXTRACTION OF OLEIC SUNFLOWER SEEDS BY TWIN SCREW

EXTRUDER: INFLUENCE OF SCREW CONFIGURATION AND

OPERATING CONDITIONS

Kartika, I.A., et al., FATETA-IPB, Indonesia

Industrial Crops and Products, Volume 22, Issue 3, November 2005

The objective of this study was to investigate the effects of screw configuration,

position of screw elements and spacing between them allowing to realize oil

extraction of oleic sunflower seeds on a twin-screw extruder. Experiments were

conducted using a co-rotating twin-screw extruder (Model Clextral BC 45, France).

74

Twelve screw profiles were examined to define the best performance (oil extraction

yield, oil quality, mean residence time, and thermo-mechanical energy input) by

studying the influence of operating conditions temperature pressing, screw rotation

speed and seed input flow rate.

Generally, the position and spacing between two screw elements affected oil

extraction yield. An increase of oil extraction yield was observed when the

reversed screw elements were configured with increased spacing between

elements or/and with smaller pitch screw. In addition, more oil extraction yield

was produced as the temperature pressing, screw rotation speed and seed input

flow rate were decreased. The higher oil extraction yield was obtained under

operating conditions 80 °C, 60 rpm and 24 kg/h. Furthermore, the operating

parameters influenced energy input and mean residence time of matter. Both energy

input and mean residence time increased when the temperature pressing

increased. However, increase of screw rotation speed and seed input flow rate

decreased mean residence time. Effect of the operating parameters on oil quality

was unimportant. In all experiments tested, the oil quality was very good. The acid

value was below 2 mg KOH/g of oil and total phosphorus content was very poor,

below 40 mg/kg.

8.10 GAS-ASSISTED OILSEED PRESSING - DESIGN OF AND TESTS WITH

A NOVEL HIGH-PRESSURE SCREW PRESS

Pietsch, A. and Eggers, R., Eurotechnica GmbH, Germany

Procedia Food Science, Volume 1, 2011

Vegetable oils like rape seed or soybean oil are produced industrially in large scale.

Key process step is mechanical expression of the oil from the feed material, e.g. rape

seed. A new process for enhanced pressing of oil-seeds was designed and realized in

pilot scale. The novelty is the additional use of pressurized gasses in screw-

pressing which can modify oil yield as well as oil and cake properties. Uniaxial

gas-assisted pressing enhances oil yield significantly, but a pilot screw press with

pressure housing did not so far.

8.11 EFFECTS OF COMPRESSIVE STRESS, FEEDING RATE AND SPEED OF

ROTATION ON PALM KERNEL OIL YIELD

Akinoso, R., et al., University of Ibadan, Nigeria

Journal of Food Engineering, Volume 93, Issue 4, August 2009

Compressive stress, feeding rate and rotational speed are some of the operational

parameters that influence efficiency of an oil expeller. A 3 × 3 factorial

experimental design was employed to determine the effects of these parameters on

palm kernel oil expression using oil expeller. Obtained data were analysed

statistically by regression and ANOVA to obtain relationship between independent

75

variables; compressive stress, feeding rate and speed of operation of the oil expeller

and dependent variable; oil yield. Maximum oil yield of 46.3% was recorded at 30

MPa compressive stress, 150 kg/h feed rate and 110 rpm of rotational speed while

minimum oil yield of 16.3% was obtained at 10 MPa compressive stress, 50 kg/h

feed rate and 110 rpm of rotational speed. The developed model equation fitted well

with obtained data (R2 = 0.84) an indication that the model fits well with the data.

The results also showed that predictor correlated positively and directly proportional

to the oil yield. However, from the coefficient table, it was discovered that only the

compressive stress significantly affect the oil yield at p < 0.05.

The effects of particle size, heating temperature, heating time, applied pressure, and

duration of pressing on the yield and quality of mechanically expressed groundnut

oil were investigated.

8.12 A NEW TWIN-SCREW PRESS DESIGN FOR OIL EXTRACTION OF

DEHULLED SUNFLOWER SEEDS

Isobe, S., et al., National Food Research Institute, Japan

Journal of the American Oil Chemists' Society, Volume 69, Number 9, 1992

Transport of material in a single-screw press depends mainly on friction between the

material and the barrel’s inner surface and the screw surface during screw rotation.

Thus, a solid core component, like seed hulls, is often necessary to produce the

fraction. This sometimes causes excess frictional heat, large energy consumption and

oil deterioration. Furthermore, if single-screw presses are not configured with

breaker bars or other special equipment, they provide inadequate crushing and

mixing.

A twin-screw oil press can be expected to solve these problems because of the higher

transportation force, similar to a gear pump, and better mixing and crushing at the

twin-screw interface. A twin-screw press (screw diameter=136 mm,

length/diameter=6.5, screw speed 15–100 rpm, feed rate=50–150 kg/h) was designed

with partially intermeshing and counter-rotating screws and was tested on

dehulled sunflower seed. The results were compared to a single-screw lab-scale

press. Dehulled sun-flower seed (wt, 6.0%; oil, 58.6%) without pretreatments

(crushing or cooking) gave 93.6% oil recovery with the twin-screw press, in

contrast to 20% oil recovery with the single-screw press. The oil expressed with a

twin-screw press had less foreign material than the oil from the single-screw press.

Other properties of the oil were also good. Energy consumption of the twin-screw

press was more efficient. All results suggested that oil production from dehulled

sunflower seed with a twin-screw press is highly efficient.

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8.13 OIL EXPRESSION CHARACTERISTICS OF RAPESEED FOR A SMALL

CAPACITY SCREW PRESS

Bargale, P.C. and Singh, J., Central Institute of Agricultural Engineering, Bhopal

Journal of food science and technology, Volume 37 (2), 2000

Oil expression studies were conducted on rapeseed, employing the Mini-40 screw

press (oil expeller). With a view to maximize the oil recovery, rapeseed samples were

given four pre-treatments viz., (i) moisture conditioning through water sprinkling (ii

and iii) tap and hot water (80°C) soaking for 1 h followed by drying and (iv) direct

steaming of raw samples for 5, 10, 15 and 20 min duration. Prepared samples were

dried to moisture levels near to 5, 7, 9 and 11% (w.b.) prior to expelling in the screw

press, except for steaming. The effects of these pre-treatments were studied on oil

recovery, specific energy consumption and the press capacity. The pre-treatment of

hot water (80°C) soaking for an hour followed by drying to a moisture level of 7%

(w.b.) gave the maximum oil recovery of about 82% and was found to be the

optimum. Though the percent oil recovery was reasonably good, the low effective

capacity of the press (2.8 to 4.0 kg/h) and the frequent choking/jamming problems

encountered during press operation prevented the possibility of adoption of this

press at rural level in India.

8.14 A TWIN-SCREW EXTRUDER FOR OIL EXTRACTION: I. DIRECT

EXPRESSION OF OLEIC SUNFLOWER SEEDS

Dufaure, C., et al., Ecole Nationale Supérieure de Chimie de Toulouse Laboratoire de

Chimie Agro-Industrielle, France

Journal of The American Oil Chemists' Society, Volume 76, Number 9, 1999

Lipids are traditionally removed from seeds by mechanical crushing and solvent

extraction. During the mechanical crushing process the oilseed is cleaned, cracked,

flaked, and cooked before entering a mechanical screw press. Seventy-five percent of

the oil of sunflower seeds can be extracted by crushing, and the fatty cake then

contains about 15% of oil. The oil levels remaining in the cake can be reduced to less

than 2% by solvent extraction. However, the crude oil has to be refined as it contains

many impurities and approximately 600 ppm phosphorus. A new process, in which

sunflower seeds are pressed in a twin-screw extruder, is examined here. The screw

profile was first optimized. Oleic sunflower seeds were crushed and 80% of the oil

was removed. The resultant oil was of good quality, with acid numbers below 2 mg

KOH/g of oil and total phosphorus contents of about 100 ppm. The influence of

pressing temperature and of fresh seed moisture content was determined. High

pressing temperature and low moisture content improved oil extraction. The

quality of the meal was examined through the solubilization of its proteins in

alkaline water at 50°C. The fatty meal proteins remained quite soluble, and therefore

one can assume that they were still relatively close to their native conformation. The

77

pressing of oleaginous material in a twin-screw extruder provides a new option to

traditional processes.

8.15 SEED OIL EXTRACTION USING A SOLAR POWERED SCREW PRESS

Mpagalile, J.J., et al., Sokoine University of Agriculture, Tanzania

Industrial Crops and Products, Volume 25, Issue 1, January 2007

An efficient and economical oil expression system that can operate on solar power in

rural areas of underdeveloped and developing countries is needed. Recent

improvements in both oil extraction and solar energy technologies have indicated the

possibilities for fabricating oil extraction equipment. Thus, the objective of our study

was to develop a simple oil expression unit capable of producing high quality oil

based on solar energy in remote rural areas. A photovoltaic (PV), batch operated,

low-pressure oil press, using a 190 W, 12 V dc motor, was designed, fabricated, and

tested using coconut and groundnut as the raw material. Samples used in the

study were ground to particle size between 500 μm and 2 mm and were pressed at

12 ± 1% moisture content. The press was evaluated based on the oil extraction

efficiency (OEE), power consumption, and oil quality. The press had an average

OEE of 73% for coconuts and 70% for groundnuts after 12 min of pressing. The oil

expression efficiency was characterized by three main stages namely delayed, rapid,

and retarded. The power consumption was affected greatly by the pressing time,

with power consumption increasing with an increase in the pressing time. The

specific energy consumption was found to increase significantly after 8 min of

pressing and correlated with the compaction of the cake, which resulted in more

power being required to express the entrapped oil. The expressed oil was fresh, free

from foots, and of high quality with an average moisture content of 0.015% for

coconut oil and 0.019% for groundnut. Analyses showed that the viscosities were

42.1 MPa s (coconut oil) and 59.1 MPa s (groundnut oil), at 25 °C. Overall, the press

performed well and was comparable in performance to other types of presses.

8.16 EFFECT OF PRE-TREATMENTS ON MECHANICAL OIL EXPRESSION

OF SOYBEAN USING A COMMERCIAL OIL EXPELLER

Patil, R.T. and Ali, N., Central Institute of Agricultural Engineering, Bhopal

International Journal of Food Properties, Volume 9, Issue 2, 2006

The effect of expeller screw press and pre-treatments on the quality and quantity of

soybean oil and cake was studied using a commercial oil expeller. The pre-treatments

included whole soybean crushing, soy grits crushing, and crushing of soy grits

extruded at 135°C. The screw speeds were 28, 35, and 45 rpm. The moisture content

of soybean used in the experiment was 10% wet basis. The average capacity of the oil

expeller was found to be 145 kg/h, 110 kg/h, and 120 kg/h for whole, grits, and

extrudate, respectively at 45 rpm. The average capacity of oil expression from whole

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soybean did not vary significantly from 28 to 45 rpm. In the case of soy grits,

however, the capacity was higher when the expeller speed was lowest, i.e., 28 rpm.

In the case of extrudate, even in a single pass, the recovery was higher, i.e., to 71% at

both 45 and 35 rpm. The color of oil from soy grits was lighter followed by extrudate,

and the color of oil obtained from whole soybean was dark. The FFA in oil from all

the samples was below 1%, however the lowest percentage was for oil obtained from

extrudate at 0.5%. The urease activity of the extruded cake was 0.15 pH units, and the

protein and oil content were about 48% and 5%, respectively. The optimum process

variables for mechanical expelling of soybean were found to be extrusion as a

pretreatment and speed of expeller screw at 45 rpm, which yielded throughput

capacity 103 kg/h, oil recovery of 70.5%, and urease activity of the cake at 0.15.

8.17 DRY EXTRUSION AS AN AID TO MECHANICAL EXPELLING OF OIL

FROM SOYBEANS

Nelson, A. I., et al., University of Illinois, USA

Journal of the American Oil chemists' society, Volume 64, Number 9, 1987

A new concept is described for mechanical extraction of oil from soybeans, using dry

extrusion as a pre-treatment. It was found that coarsely ground whole soybeans at

10 to 14% moisture could be extrusion cooked so that the extrudate emerges from

the die in a semi-fluid state. The dwell time within the extruder was less than 30

seconds, and the temperature was raised to about 135 C. The semi-fluid extrudate

was immediately pressed in a continuous screw press to obtain high quality oil

and press cake. Extrusion prior to expelling greatly increased the throughput of

the expeller over the rated capacity. An oil recovery of 70% was obtained in single

pass expelling using pilot model expellers. Higher recovery rates can be expected

with commercial scale expellers. The high temperature-short time extrusion cooking

process eliminates the prolonged heating and holding of raw material in

conventional expelling. Under the experimental conditions, press cake with 50%

protein, 6% residual oil and 90% inactivation of trypsin inhibitors was obtained. The

low fat cake was easily ground in a hammer mill without the usual problems

associated with milling of whole beans. The expelled oil was remarkably stable with

an AOM stability of 15 hr, which is comparable to refined deodorized oil according

to NSPA specifications. The new procedure offers potential for producing natural

soybean oil and food grade low fat soy flour by a relatively low cost operation. It

may be adopted as an improvement to existing conventional expelling operations in

less developed countries or as a commercial or on-farm operation for producing

value added products from soybeans within the U.S.

8.18 RECOVERY OF SUNFLOWER OIL WITH A SMALL SCREW EXPELLER

Jacobsen, L.A. and Backer, L.F., North Dakota State University, USA

Energy in Agriculture, Volume 5, Issue 3, November 1986

79

Tests were run on a HANDER Oil Expeller processing oil-type sunflower seed.

Statistical comparisons were made. Tests compared different lots of sunflower seed.

Lot I had 11% (w.b.) moisture content and 39.7% oil content and Lot II had 6%

(w.b.) moisture content and 42.6% oil content. Greater expeller capacity and oil

output were observed with Lot I. Extraction efficiency was better with Lot II. Tests

also involved preheating the sunflower seeds of Lot II to 50, 60, and 75 °C before

extraction. There was a large improvement in expeller capacity and oil output

compared to seeds processed at room temperature. There was a significant

difference in the oil output and efficiency between the three preheat temperatures.

8.19 MECHANICAL EXPRESSION OF OIL FROM LINSEED (LINUM

USITATISSIMUM L)

Singh, J. and Bargale, P.C., Central Institute of Agricultural Engineering (ICAR), Bhopal

Journal Oilseeds Research, Volume 7, Number 1, 1990

Oil expression studies were conducted with linseed. The samples of linseed were

given different treatments - water sprinkling, mixing and conditioning and

soaking in water for 1 h at room temp. followed by sun drying and direct steaming

of raw samples for 5, 10, 15 and 20 min. prior to expressing through a mini-40

screw press (oil expeller). Prepared samples were allowed to have an m.c. of approx.

5, 7, 9 and 11% m.c. (wb) in each case except for direct steaming. It was observed that

treatments as well as m.c. affected the oil yield significantly. One hour-soaking in

water at room temp. followed by sun drying to approx. 7% m.c. helped to reduce

the gums in oil and gave the max. oil recovery of approx. 87.96% with an energy

consumption of 0.319 kWh/kg of feed.

8.20 PROCESSING FACTORS AFFECTING YIELD AND QUALITY OF

MECHANICALLY EXPRESSED GROUNDNUT OIL

Adeeko, K.A. and Ajibola, O.O., Obafemi Awolowo University, Nigeria

Journal of Agricultural Engineering Research, Volume 45, January–April 1990

Shelled groundnuts were manually cleaned and reduced to two particle sizes (finely

and coarsely ground). The milled samples were then heated at 70°, 90°, 115°, 135°,

and 160°C for 15, 25, 35 and 45 min. Pressures of 10, 15, 20 and 25 MPa were applied

for 10 min during pressing.

Generally, oil yields from coarsely ground groundnut were higher than those from

finely ground samples, but the free fatty acid values were lower. Increasing the

temperature did not improve the oil yield after 25 min of heating. Oil yield

increased with pressures of up to 20 MPa beyond which the yield either levelled

off or decreased. The rate of oil expression was increased by an increase in

temperature, time of heating, and particle size. An increase in the heating

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temperature and time increased the free fatty acid, peroxide value, and the colour

intensity of the oil expressed.

8.21 ENZYMATIC PRETREATMENT TO ENHANCE OIL EXTRACTION

FROM FRUITS AND OILSEEDS: A REVIEW

Domínguez, H., et al., University of Santiago de Compostela, Spain

Food Chemistry, Volume 49, Issue 3, 1994

Enzymatic treatment to enhance oil recovery from olive, avocado or coconut pastes

has been used with excellent results both on a laboratory and industrial scale

(olive) obtaining the oil in shorter times and increasing the capacity of the

equipment. This treatment was tried for the extraction of oil and protein from

oilseeds on a laboratory scale (peanut, rapeseed — also in a pilot plant — sunflower

and soybean). Considering that two thirds of the total fat and oil production is

supplied by oilseeds (soybean, sunflower, rape and palm accounting for more than

70% of vegetable oils) this is a promising field for biotechnological applications. In

the present work the different processes, as well as the factors affecting their

efficiency, are discussed.

8.22 ENZYMATIC HYDROLYSIS OF SOYBEAN FOR SOLVENT AND

MECHANICAL OIL EXTRACTION

Bargale, P. C., et al., Central Institute of Agricultural Engineering, Bhopal

Journal of Food Process Engineering, Volume 23, 2000

Due to inefficient extractability of its low oil content, soybeans are often bypassed in

village-scale processing. Soygrits, flakes, and expanded collets were hydrolyzed by

proteases, cellulases, and pectinases before oil extraction by solvent and static

mechanical pressure. Driselase with multi-enzyme activity and two proteases

improved solvent extraction rates but only Driselase enhanced mechanical pressing.

Up to 58% of seed oil was pressed from enzyme-hydrolyzed flakes but 88% was

pressed from Driselase-treated collets. Either pretreatment is a feasible adjunct to

mechanical pressing in small batch operations.

8.23 MECHANICAL EXPRESSION OF OIL FROM MELON SEEDS

Ajibola, O.O., et al., Obafemi Awolowo University, Nigeria

Journal of Agricultural Engineering Research, Volume 45, January–April 1990

Investigations were conducted on the mechanical expression of oil from melon seeds

(Citrullus vulgaris) in a laboratory press. The processing variables were particle size,

moisture content, heating temperature and heating time. Physical properties such as

colour, specific gravity, refractive index and viscosity were determined.

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Coarsely ground samples gave consistently lower yields of oil than finely ground

samples. The oil yield was affected by the seed moisture content, heating

temperature and heating time. The oil yield was however, mostly dependent on

the amount of moisture reduction achieved during heating. Highest oil yields of

about 41% were obtained, at an expression pressure of 25 MPa, when samples

conditioned to initial moisture contents of 9 and 12% (wet basis) were heated to

achieve a moisture content reduction of about 5%. This yield corresponds to an

expression efficiency of about 80% when compared to melon oil content of 51%.

Further reduction in moisture content did not increase oil yield from the samples.

Melon oil was found to have a pale yellow colour, refractive index of 1.468, specific

gravity of 0.918 and viscosity of 50.1 × 10−3 kg m−1s−1. These properties were not

affected by processing conditions.

8.24 SUPERCRITICAL CO2 EXTRACTION OF FATTY OIL FROM FLAXSEED

AND COMPARISON WITH SCREW PRESS EXPRESSION AND

SOLVENT EXTRACTION PROCESSES

Pradhan, R. C., et al., Indian Institute of Technology, Delhi

Journal of Food Engineering, Volume 98, Issue 4, June 2010

Flax oil is commonly used in food due to high percentage of omega-3-fatty acid and

omega-6-fatty acid. In the present work the flax seed was extracted using green

solvent viz. supercritical CO2 and compared with soxhlet and mechanical screw

press methods. The chemical compositions of the oils were determined by CHNS

analyser, GC-FID, GC/MS and H-NMR. The supercritical CO2 process selectively

extracted the fatty oils with high percentage of omega-3-fatty acid and omega-6-fatty

acids. The chemical composition of screw press oil is close to that of supercritical

CO2 extracted oil, whereas the yield is nearly 27% less in comparison to the

supercritical CO2 method.

8.25 COMPARATIVE EVALUATION OF THE DIGESTER–SCREW PRESS

AND A HAND-OPERATED HYDRAULIC PRESS FOR PALM FRUIT

PROCESSING

Owolarafe, O.K., et al., Obafemi Awolowo University, Nigeria

Journal of Food Engineering, Volume 52, Issue 3, May 2002

In order to demonstrate the strength and possible weaknesses of the digester–

screwpress (DSP) system for small-scale oil palm fruit processing, a comparison was

made of its performance and that of the erstwhile hand-operated hydraulic

extraction system. Indices of evaluation include oil yield and quality, and operational

economics. The results indicate that the throughput of the DSP system was four

folds of that of the hydraulic system, whilst also operating at higher oil extraction

82

efficiency (89.1%). There was no significant difference between the quality of the

palm oil obtained from the two systems. However, the economic analysis of the

systems indicates that at throughput of 0.75 t/h and above, the DSP system was

more economical than the hydraulic system in terms of equipment, labour,

material and floor space requirement and revenue accruing from the processing

operation.

8.26 DESIGN AND DEVELOPMENT OF SECONDARY CONTROLLED

INDUSTRIAL PALM KERNEL NUT VEGETABLE OIL EXPELLER PLANT

FOR ENERGY SAVING AND RECUPERATION

Okoye, C.N., et al., Harbin Institute of Technology, China

Journal of Food Engineering, Volume 87, Issue 4, August 2008

This paper presents an experimental work on energy saving and recuperation in

secondary controlled industrial palm nut vegetable oil plant. It employs the

hydrostatic constant pressure rail principle to accomplish crushing, pressing and

filtering operations. The seed crushing and oil expelling operations are based on

pressure differential between the fed seeds and discharged mash resulting in an

oil recovery efficiency of 97.1%, energy saving of 53.48 KW during cylinder

retraction and the reduction in barrel temperature from 203 to 187 °C which was

effected through cooling pipes. The plant consists of an oil expeller, a filter press,

and a conveyor unit and works on a single feed, single stage compression

principle with a throughput capacity of 30 kg/h and effective capacity of 16 kg/h.

The plant mathematical model is derived and simulation on flow through hydraulic

transformer performed using SIMULINK. The experimental results not only agree

with theoretical analysis but also appears to be very efficient in energy saving and

recuperation.

8.27 ENERGY ANALYSIS IN THE SCREW PRESSING OF WHOLE AND

DEHULLED FLAXSEED

Zheng, Y., et al., North Dakota State University, USA

Journal of Food Engineering, Volume 66, Issue 2, January 2005

Specific Mechanical Energy (SME) is an important parameter of screw press design

and performance. Analysis of SME and its dissipation will improve our

understanding of temperature increase during screw pressing, and will in turn

lead to better protection of heat sensitive materials, such as alpha-linolenic acid in

flaxseed oil. SME, net enthalpy change, and heat loss were estimated from steady

state data for screw pressing whole flaxseed and flaxseed with different fraction of

hull removal (FHR). The decrease of moisture content and FHR all resulted in

significant increases of both oil and meal temperature and net enthalpy change.

Conduction dissipated up to half of the mechanical energy input, while convection

83

was low. SME increased significantly from 81.1 to 104.7 kJ/kg when the moisture

content of whole flaxseed decreased from 12.6% to 6.3%. SME when pressing

whole flaxseed was significantly higher than when pressing dehulled flaxseed.

8.28 DESIGN AND TESTING OF A SOLAR PHOTOVOLTAIC OPERATED

MULTI-SEEDS OIL PRESS

Mpagalile, J.J., et al., Sokoine University of Agriculture, Tanzania

Renewable Energy, Volume 31, 2006

Oil expression tests were conducted to evaluate the performance of a novel oil

expeller designed and fabricated to operate on a 200W solar photovoltaic (PV) power

system as a sole power source. The oil press was designed to press oilseeds meal

with intermediate moisture content of 12% (w.b.) and 0.5–2 mm particle sizes.

Freshly grated coconuts and ground peanuts were used to determine the oil

expression efficiency of the press. The oilseed samples were pressed for 12 min with

a maximum pressure of 3.0 MPa being reached at 6 min of pressing for peanuts and 8

min of pressing for coconuts. The pressure was then held for the rest of the pressing

time. The press attained an average oil expression efficiency of 73% for coconuts and

70% for peanuts. The force-vs.-deformation studies indicated that peanut press meal

was compacted at a higher rate as compared to coconuts. The observation on the

energy consumption indicated that there was a significant increase (P<0.05) in the

specific energy requirement for both coconuts and peanuts after 6 min of pressing,

which resulted from the solidification of the press cake. An average specific energy

of 36.55 and 20.35 Wh/kg was recorded for peanuts and coconuts, respectively, after

12 min of pressing.

84

Findings and Discussion

India has a huge demand of edible oil and it appears that oil is expelled from almost 40

million tons of oilseeds per year. India thus has a huge base of expelling experience for

various kinds of oilseeds, the principle being groundnut, mustard, copra, neem, etc. India

also has a very large number of expeller and other associated equipment manufacturers. A

fair amount of such equipment is exported to various countries including to the developed

countries. Expelling of Jatropha and Karanja in the country has begun only recently and

therefore the experience and knowledge specifically for expelling these is comparatively

meagre and perhaps not enough. It appears that by and large scientific input has not gone

into the design of expellers. Also, scientific understanding of the parameters and process of

expelling is not uniformly understood. Most manufacturers go by their “experience” in this

matter and seem to be satisfied about it. Our interaction with various sectors of this activity

leads us to believe that there are considerable variations in the understanding of the exact

process of expelling which lead to an inexact understanding of the expelling and extraction

efficiencies. This is definitely so for Jatropha and Pongamia and perhaps for most other

oilseeds as well.

From our interactions with various stakeholders during the preparation of this report and

from study of the information derived from the internet, several key pieces of information

were gathered. Some of these are briefly given here.

Expelling operations differ widely from place to place, and, for conventional oil seeds

expelling is usually done twice. In some cases, expelling may be carried out only once or

in some cases even three times. This depends upon the perception of the operator or as

per the advice given to him by the equipment manufacturer. The oil content remaining

in the seed cake is perhaps never measured. This parameter alone is significant and can

be very useful in determining the number of passes required for particular oil seed.

It is the general understanding that if the expelling is done “correctly”, 6 to 7% oil by

weight is retained in the seedcake. Apparently no systematic analysis has been done on

the subject by any of the expeller manufactures. They usually judge this by the amount

of the expelled oil collected by them and if it as per their expectations, they are satisfied.

This means that if the actual oil content of the seeds is on the lower side, relatively, a

higher percentage is left back in the seedcake.

The marketplace operations differ widely. With most operators, who generally own one

expeller, seedcake is continuously collected and after all the seeds are crushed, the

seedcake is put back in the expeller for a second round of expelling. This may be after

some days, or the next day if he does it on alternate days.

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In some cases, for large operations, operators employ a second expeller in series. The

seedcake, immediately after first expelling is put into the second expeller, either

manually or through a custom designed conveyor. Such operators also felt that

expelling oil from the ‘hot seedcake’ uses less power. This helps them economize on

their power bills. Apparently, no measurements worth the while have yet been made.

As a thumb rule, the operators feel that for an input of 1 ton/day, a 1 HP motor is

required in the expeller. Thus if they are expelling 100 tons/day, on a continuous basis,

they would require a 100 HP motor. In actual practice there are wide variations. It is

felt that in the absence of correct data, most expellers are over- designed in terms of

their power ratings. These therefore need to be optimized.

Since the bulk of the experience of all operators and expeller manufacturers is on

conventional edible oil seeds such as mustard, groundnut, or copra, etc., they were not

in a position to advice on the expelling of Jatropha. They, therefore, use the same

parameters in design and operation for Jatropha.

In rare cases, manufacturers have expellers where the clearances can be adjusted. But,

they advise the customers not to tamper with them as they suspect that this may result

in the breakdown of the machines if not “properly set”. They however admitted that

for seedcake expelling lower clearances can be employed, but in practice this rarely

happens.

Indian expeller manufacturers can clearly make very good quality expellers as is

evident from their export records and repeat orders from overseas. What they lack is

design know-how. Apparently there is no agency we could identity which could fill

this gap. Part knowledge exists in some places. If design know-how can be imparted to

them, they can perhaps manufacture custom – made machines for any expelling

requirement in terms of materials used, manufacturing tolerances and finish. Most of

them appeared to be exceptionally skilled and because of this attribute, their machines

have excellent durability and image in the market.

There appeared to be some awareness about the moisture content of the seeds with

respect to amount of oil expelled. But this was very general. A figure of 17% has been

quoted but apparently no one had records of how this figure was reached. Also, almost

all operators have never measured this parameter.

However, with this awareness, they advise their customers to spray hot water on the

seeds if they are ‘somewhat old’ or have been stored in the open. Or even soak them

overnight, dry them briefly, and then expel the oil. Their total concentration is only

toward expelling efficiency and clearly not towards energy savings.

It is felt that the information related to moisture content, methodology to re-moisten

them, storage conditions, etc., need to be established for maximum benefits.

86

Cooking or steaming or heating of seeds in case of Jatropha is strongly suggested by

all manufacturers. They feel that the cell walls in the seed where oil is trapped is

weakened by heating, either through exposure to steam or even through dry heat.

Consequently, they also manufacture “cookers” which they sell along with their

expellers. A variety of designs (basically each manufacturer having his own) exist. No

manufacturer was able to answer as to what is the optimum time for exposure to heat

or the temperature to which the seeds should be exposed. With the steam cookers and

the boilers employed, it appeared that a temperature if upto 108°C is reached. Some

manufacturers claim they had once measured it, but no records exist.

This subject in our opinion needs detailed attention as the benefits of expeller power

consumption would depend on it. This, it seems, may more then offset the power

consumed in cooking, but will need to be established.

The presence of “some” amount of fibre, along with the seed, was highly

recommended by the manufacturers. They felt that the absence of fibrous material

makes the seeds “slip” in the expeller without expelling all the oil. For some edible oils

they deliberately add some fibre, which basically may come from the seeds or the

kernel itself.

In conclusion it appears that in view of very large potential availability of Jatropha and

various other seeds for manufacturing biodiesel, the aspect of oil expellation needs to be

given scientific attention such that design parameters can be established and process details

worked out. This would need efforts to generate precise data to establish the design

criterion. In the absence of any available centre in the country which can address these

issues, efforts are required to either create such a centre, or empower a consortium to carry

out these tasks. This act alone would be of large benefit to this sector. It is expected to lead

to higher oil expelling efficiencies, considerable energy savings, knowledge of various

parameters of oil expelling and therefore provide a basis for design to manufacturers of oil

expellers. In view of India’s emphasis on a variety of non-edible oil seeds, which largely

have not much interest outside the country, indigenous efforts would be necessary. We thus

have to make the ordinary task of expelling oil from seeds science based.

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Suggestions for Further Research

In the preceding chapters we have seen that biodiesel is a significant and desirable product

for Indian requirements. We have also seen that a large number of manufacturers are

making expellers but for conventional edible oil purposes only. These have been made use

of, with no change in their design or operation, for the purpose of expelling oil for biodiesel

production from newer seeds such as Jatropha or Pongamia. It is also understood that no

significant design effort has so far been put to optimize these expellers for the newer seeds

and no studies conducted to specifically understand the characteristics of these seeds and

then accordingly design expellers.

In light of the enormous potential of biodiesel and consequently expelling oil from these

enormous amount of seeds, it would be relevant and of significance to put in research efforts

to maximize the expelling efficiency (maximum amount of obtained oil) and energy

economy of expellers. This information would then lead to scientific design of equipments.

In view of this, it is suggested that research studies be initiated and conducted by

organizations which can generate trustworthy data for this purpose.

Some suggested studies are:

10.1 It is commonly understood that brief exposure to heat or steam weaken the cell walls

in the seed which contain oil. Most expeller manufacturers make recommendations

for this based upon their ‘feel’ or experience. Widely different recommendations are

given in the literature available on the subject. It appears that the moisture content of

the seeds at the time of expelling has an immense effect upon energy consumption,

expelling efficiency and overall viability of operations. It is therefore suggested that a

systematic study of time- temperature exposure effects be done for Jatropha seeds

(more than one genus) to establish the exact process requirements (heat or steam)

and thereby arrive at the optimum design of the cooker.

10.2 The effect of expeller design parameters, particularly compression clearances and

speed, certainly has a profound effect on both expelling efficiency and energy

consumption. Would a smaller clearance expel more oil at the cost of relatively

higher energy consumption? How would it affect the machine durability? Will this

be able to suggest what steels to use? It is felt that these and other related parameters be

scientifically researched and a benchmark for expelling and energy efficiency worked out. This

will help the not so literate groups identify and choose correct machines for their

operations. The possibility of adjustable compression clearances will make the

machine more versatile in that it can input both the seeds and the cake, and still work

efficiently. Thus the requirements of both small and large scale expellers can be met.

10.3 It is seen that after the expelling operations, at best, about 6-7% oil by weight is still

retained in the seedcake. This also would be achieved only after 2 or even 3

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successive passes. Here, in some cases the second pass is done immediately after first

expelling (through a second independent expeller), while in other cases it would be

done after storage of the seedcake for some time, maybe a day or more.

It is therefore suggested that this information be accurately generated for each of the

successive expelling operations. This information is not available at present. The

energy consumption and therefore the viability of these expelling operations also

need to be understood.

10.4 Solvent extraction for oil from the seeds has been mooted extensively. Though

generally understood as a straight forward process step, exact information on its

application could not be found. It is therefore necessary to generate data of this

operation as applicable to oil seeds of interest.

Here, both the seed cake with different oil contents as well as direct extraction

without resorting to mechanical expelling is required to be understood. In case of the

latter, the degree of pulverizing would be important. The process parameters, the

economic viability of this process and the exact design requirements would need to

be worked out. This information will help in understanding if there is an advantage,

particularly for large-scale users, to employ both mechanical expelling for the seeds

and solvent extraction from the seedcake.

10.5 The moisture content of the seeds can vary widely, particularly for storage

conditions and the time for which seeds are stored. Several of the groups surveyed

“felt” that the ideal moisture content should be 17% and if it is lower, the oil expelled

is less. The requirements pertaining to this aspect need to be established. Also, in

case of seeds having lower than the optimum moisture content, how should the

seeds be re-humidified? How the moisture content is going to affect expelling

efficiency and energy consumption, therefore, needs to be studied.

10.6 The presence of ‘some’ fibrous matter in expelling operation is believed to be of some

importance. A complete lack makes the machine ‘slip’ as there is no ‘grip’. This needs

to be understood. Establishing this for Jatropha (or for any other seed) would also

decide on the degree of decortication / dehulling, and economics of the operation.

This information could be of benefit for designing the clearances of the expeller.

10.7 Facilities for undertaking research on designing expellers are clearly required. One or

more research centres carrying out research on expeller design should be established,

or, some existing organization identified and supported. It appears that at present,

there is a complete lack of it in the country.

10.8 Information dissemination to all sectors connected to this area is necessary and

would be of importance. This would include the manufacturers of equipment, the

users, and the facilitating/ funding institutions. Such an agency should also collect

89

feedback and incorporate necessary changes both in the process and expeller design.

Operation manual of the equipment should be prepared based upon this

information.