UNIVERSITY OF NAIROBI

FACULTY OF ENGINEERING

DEPARTMENT OF MECHANICAL AND MANUFACTURING ENGINEERING

TITLE: JATROPHA OIL PRESSING MACHINE

PROJECT CODE: FML 01/12

BY

OMOTE MAKORI GEOFFREY F18/2699/2007

MWANGI DENNIS F18/1850/2007

SUPERVISOR: PROF. LUTI.F.MAKAU

Project report submitted in partial fulfillment of the

requirement for the award of the degree

of

Bachelor of Science in MECHANICAL ENGINEERING

of the University of Nairobi.

Submitted on: May, 2012

i

DECLARATION AND CERTIFICATION

This BSc. work is our original work and has not been presented for a degree award in this or any

other university.

…………………………. ……………………………..

OMOTE M GEOFFREY MWANGI DENNIS

F18/2699/2007 F18/1850/2007

This report has been submitted to the Department of Mechanical and Manufacturing Engineering

University of Nairobi with my approval as supervisor:

Prof. LUTI F. MAKAU

Sign

……………………………………………………………...

Date

………………………………………………………………

ii

ACKNOWLEDGEMENT

We express our sincere appreciation to Prof. Luti F. Makau for his guidance, advice, criticism,

systematic supervision, encouragements, and insight throughout this project.

We express our deep gratitude to Mrs. Lorna Omoudo C.E.O (Vanilla Jatropha foundation) for

her great help and effort during this project.

We also give special thanks go to our class colleagues for their valuable support and aid.

We also thank our beloved families for their great support and encouragement throughout this

project.

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TABLE OF CONTENTS

DECLARATION AND CERTIFICATION .................................................................................................... i

ACKNOWLEDGEMENT ........................................................................................................................ ii

LIST OF FIGURES ................................................................................................................................ vi

LIST OF TABLES ............................................................................................................................... viii

ABSTRACT ......................................................................................................................................... ix

CHAPTER 1: INTRODUCTION ...............................................................................................................1

1.1 ENERGY ............................................................................................................................................... 1

1.2 OBJECTIVES ......................................................................................................................................... 4

CHAPTER 2: LITERATURE REVIEW .......................................................................................................5

2.1BACKGROUND ...................................................................................................................................... 5

2.2 THE PLANT ........................................................................................................................................... 8

2.2.1 Sowing and germination ................................................................................................. 8

2.2.2 How it is planted ........................................................................................................... 10

2.2.3 Uses of the Jatropha curcas and its oil .......................................................................... 10

2.3 OIL EXTRACTION ................................................................................................................................ 10

2.3.1 Oil Extraction Efficiency .............................................................................................. 12

2.3.2 Oil as fuel...................................................................................................................... 12

2.4 ADVANTAGES OF USING JATROPHA OIL .......................................................................................... 12

CHAPTER 3: CASE STUDY .................................................................................................................. 13

3.1 INTRODUCTION ................................................................................................................................. 13

3.2 METHODOLOGY OF THE RESEARCH .................................................................................................. 14

3.3 ECONOMIC VIABILITY OF BIODIESEL ................................................................................................. 16

3.4 PRICE COMPETITIVENESS OF BIODIESEL ........................................................................................... 16

3.4.1 Price of Jatropha seeds and oil ..................................................................................... 16

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3.4.2 Jatropha biodiesel profitability production. .................................................................. 16

3.5 EXPECTED YIELD ................................................................................................................................ 17

3.6 REVENUE AND OPPORTUNITY COST OF JATROPHA PRODUCTION .................................................. 17

3.7 CONTRIBUTION OF JATROPHA TO IMPROVEMENT OF LOCAL LIVELIHOODS ................................... 18

3.8 JATROPHA OIL LOCAL LIVELIHOOD IMPROVEMENTS ....................................................................... 18

3.6 GOVERNMENT POLICY ON JATROPHA BIODIESEL PRODUCTION FOR THE IMPROVEMENT OF LOCAL

LIVELIHOOD ............................................................................................................................................. 20

CHAPTER 4: JATROPHA SEED OIL EXTRACTION AND CAKE DRAINAGE SYSTEMS.................................. 21

4.1 JATROPHA SEED OIL EXTRACTION ............................................................................................... 21

4.1.1 Komet Oil Presses .......................................................................................................................... 21

4.1.2 Rosedowns Oil Presses ................................................................................................. 22

4.1.3 Vincent Screw Presses .................................................................................................. 23

4.1.4 Strainer type screw presses ........................................................................................... 24

4.2 CAKE DRAINAGE SYSTEMS ................................................................................................................ 25

4.2.1 Nozzle cake drainage system ........................................................................................ 25

4.2.3 Conical drainage system ............................................................................................... 26

CHAPTER 5: PRELIMINARY AND DETAILED DESIGN OF THE OIL EXTRACTION MACHINE ...................... 27

5.1 PRELIMINARY DESIGN ....................................................................................................................... 27

5.1.1 Design Tree................................................................................................................... 27

5.1.2 Skeleton ........................................................................................................................ 28

5.1.3 Main Body .................................................................................................................... 29

5.1.4 Screw Shaft ................................................................................................................... 29

5.1.5 Vessel............................................................................................................................ 30

5.1.6 Hopper .......................................................................................................................... 30

5.1.7 Tank .............................................................................................................................. 31

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5.1.8 Cone .............................................................................................................................. 31

5.1.9 Drive system ................................................................................................................. 32

5.2 DESIGNED MACHINE OUTLOOK ........................................................................................................ 34

5.3 DETAIL DESIGN CALCULATIONS ........................................................................................................ 35

5.3.1 Experiment 1: oil cake ratio of pressed seeds ............................................................... 35

5.3.2 Experiment 2: Determining the density of the Jatropha seeds ..................................... 36

5.3.3 Calculation of revolutions per second of the pressing shaft. ........................................ 36

5.4 THREAD DESIGNING .......................................................................................................................... 37

5.5 HOW THE THREADS WERE PLACED ON THE SHAFT .......................................................................... 39

CHAPTER 6. DISCUSSION AND CONCLUSION ..................................................................................... 44

CASE STUDY ............................................................................................................................................. 44

THE OIL PRESS MACHINE ........................................................................................................................ 44

FABRICATION OF THE OIL PRESS MACHINE ............................................................................................ 45

TESTING OF THE OIL PRESS MACHINE .................................................................................................... 47

CONCLUSION ................................................................................................................................... 48

RECOMMENDATIONS ............................................................................................................................. 50

REFERENCES .................................................................................................................................... 51

APPENDIX A ..................................................................................................................................... 53

APPENDIX B ..................................................................................................................................... 71

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LIST OF FIGURES

Figure2.1 : A picture of Jatropha mature seeds [22] ..................................................................................... 5

Figure2.2: Global indication of the most suitable climate conditions for the growth of Jatropha ................ 6

Figure2.3: Photo of Jatropha seeds ............................................................................................................... 7

Figure3.1: A map showing Kambu area (central point of the case study) [21] .......................................... 15

Figure3.2: Cow peas grown at Kambu ........................................................................................................ 18

Figure3.3: Picture of the Jatropha oil lamp ................................................................................................. 19

Figure4.1: Detailed Picture of Screw Press Manufactured by Oekotec, IBG-Monforts [16] ..................... 21

Figure4.2: Detailed views of the screw shaft of Rosedowns Screw Presses [17] ....................................... 23

Figure4.3: Detailed Drawing of Screw Press Manufactured by Rosedowns [17] ...................................... 23

Figure4.4: Screw with Resistor Bars manufactured by Vincent Corporation [18] ..................................... 24

Figure4.5: Strainer Type Screw Press [19] ................................................................................................. 24

Figure4.6: Nozzle cake drainage system ..................................................................................................... 26

Figure4.7: Conical drainage system ............................................................................................................ 26

Figure5.1: Design tree ................................................................................................................................. 27

Figure5.2: Photo of the skeleton ................................................................................................................. 28

Figure5.3: Shaft........................................................................................................................................... 30

Figure5.4: Vessel ........................................................................................................................................ 30

Figure5.5: Hopper ....................................................................................................................................... 31

Figure5.6: Tank ........................................................................................................................................... 31

Figure5.7: Cone........................................................................................................................................... 32

Figure5.8: Drive system .............................................................................................................................. 33

Figure5.9: Fully assembled machine .......................................................................................................... 34

Figure5.10: Experimental seeds pressing diagram ..................................................................................... 35

Figure5.11: How to generate thread profile at a pitch of 140mm ............................................................... 37

vii

Figure5.12: How to generate the thread profile at a pitch of 120mm ......................................................... 38

Figure5.13: Resultant thread profile ........................................................................................................... 39

Figure5.14: An annular disk that was cut to form threads on the shaft....................................................... 39

Figure5.15: Showing how cut annular disc was cut to form threads .......................................................... 40

viii

LIST OF TABLES

Table2.1: Table to compare their relative efficiencies of extraction [4] ..................................................... 11

Table5.1: Summary of thread length profiles for given pitches .................................................................. 38

Table5.2: Typical parts of the machine ....................................................................................................... 43

ix

ABSTRACT

The objectives of the project were:

1. Designing, Fabrication and Testing of an electric powered Jatropha Curcas oil extraction

set-up suitable for a remote setting.

2. Technical and Economic Analysis of small scale Farming and oil extraction of Jatropha

Curcas.

Jatropha curcas in recent years has become a famous plant all over the world due to its unique

ability to produce oil which can be used as bio-diesel. The current demand for energy in the

world especially crude oil has led to sky rocketing of petroleum all over the world affecting

mostly the developing parts of the world due to their rising demand for energy to accelerate their

growth and also the use of foreign exchange currency to procure this important product.

Therefore Jatropha Curcas has attracted a lot of research to ascertain that its oil could actually

replace the current crude oil in providing energy all over the world.

Design of a small Jatropha oil extraction machine was done taking into consideration the cost

and mobility of the machine. The machine had to have a good capacity for pressing seeds in

order for it to cater for all seasons whether the seeds were available in abundance or not. The

Fabrication was done in the University of Nairobi Mechanical Engineering Workshop taking a

time span of about six weeks. The machine was made using local materials mainly being mild

steel since other materials were mostly expensive and some were un-available. Other intrinsic

parts and standardized parts like bearings and pulleys were bought and fitted onto the machine.

Testing of the machine was done using harvested Jatropha Curcas seeds by first adding a small

amount of water to them. The normal practice is to heat the seeds using hot steam but this was

not possible in our case so we opted for water. The prime mover used was a lathe machine which

was connected to the pressing shaft via a belt and pulley system. The results of the test have been

discussed in detail in the project report. The machine capacity which is a theoretical estimate was

100 kilograms per hour while the machine is running at a speed of 30 revolutions per minute.

The prime mover used is a 2 horse power motor. This was determined by calculations which

have been clearly indicated in chapter 5 of the project report.

From the testing results obtained we came up with some recommendations on how to further

improve the design for it to work effectively. The recommendations were design of an effective

power transmission system which would ensure efficient pressing of seeds and Design of an

adjustable cone shaft assembly to be able to control the pressures while pressing the seeds.

These in our view will help the machine work more effectively and produce better results.

1

CHAPTER 1: INTRODUCTION

1.1 ENERGY

Energy is the source of life, however there is a limited supply of energy on earth. Thus,

renewable energy utilization must be widespread all over the world otherwise the end of life

would be unavoidable. One other important reason to prefer renewable energy is the

environmental pollution depending on the emission of the burning of fossil fuels. These

emissions such as carbon dioxide and sulphur cause greenhouse effect which lead to

contamination and warming of the Earth.

Therefore, the utilization technologies of the renewable energy resources must be encouraged

and developed to increase the demand for renewable energy types. Renewable energy resources

are inexhaustible and environmentally friendly, since the energy which is reversed back comes

from the sunlight, wind, falling water, waves, geothermal heat, or biomass, in other words they

are part of nature. Each type of renewable energy has its own special advantages.

From the early ages, the energy need of the world has been partially compensated by renewable

energy types.

Until the mid-1800s, mostly wood was used as an energy source. Also, many large plants and

mills were located near the streams to generate electricity during the industrial era in Europe and

North America. In the mid-1850s, as the fossil fuel usage, which are mainly coal and oil,

increased, production plants were not limited to locate by rivers or streams because instead of

water, fossil fuels were started to be used in manufacturing. As a result, industry started to grow

up at the locations that are closer to the sources of markets, seaports and raw materials. From

1950‟s to present, the amount of renewable energy consumption has increased. Increase in

amount and variety of renewable energy resources is directly proportional with the increase in

population, which leads to increase in energy demand. The renewable energy sources are

growing in importance, but combined still make up less than 15% of world's energy

consumption.

There are basically five types of renewable energies.

I. Solar Energy

II. Wind Energy

2

III. Geothermal Energy

IV. Hydro Electricity

V. Biomass Energy

We are mainly concerned with the Biomass renewable energy source which includes trees,

agricultural crops and associated residues like plant fiber, animal wastes, and organic industrial

waste. Emission from burning of biomass is carbon dioxide neutral since it absorbs the same

amount of carbon dioxide when growing as a plant. Biomass can be used as a solid fuel, or

converted into liquid or gaseous forms. It can be used to produce electric power, heat, chemicals,

or fuels.

The Jatropha Curcas plant has emerged in recent years to be one of the best viable sources of

Biomass renewable energy. The unpredictability of the Fossil fuels commonly used in terms of

global prices, diminishing reserves and pollution of the Earth‟s atmosphere has led to the intense

exploration and research for a new and viable renewable source of energy. The Jatropha Curcas

plant has shown signs that it is capable of producing clean and safe oil which has properties close

to those of the existing fossil fuels and is easily blended with other chemicals to form bio-diesel

which can be used in Industrial machines and cars.

In Kenya the use of Fossil fuels is becoming difficult day by day for the vast majority of the

Kenyan population since as we know Kenya imports all of the fuel it uses and thus making the

population vulnerable to price changes every now and then which negatively affect the economy

and increases the poverty level in the country since all the money is used to obtain fuel for day to

day use.

Thus the use of Jatropha oil couldn‟t have come at a better time than this when the country is

going through these hard times. The plant exists in some arid and semi-arid parts of the country

where there is no significant farming of cash crops or any subsistence farming is taking place.

Also the population in these places is economically poor and the extraction of this oil would not

only cater for their energy needs but it would also be a source of income when they sell the oil to

other users.

Therefore there is an urgent need for the country to start exploiting the potential that this plant

has. The fabrication of a small scale Jatropha oil press machine which would be mobile such that

it would be easy to move around from place to place would facilitate the extraction of the oil to

3

cater for the energy needs of the people living in these arid and semi-arid areas where this plant

exists.

The Jatropha Curcas plant exists in mostly the coastal areas, Ukambani region (Kibwezi area)

and parts of Nyanza province (Homabay and its surroundings).

4

1.2 OBJECTIVES

The main objectives of this project were:

1. Designing, Fabrication and Testing of an electric powered Jatropha Curcas oil extraction

set-up suitable for a remote setting.

2. Technical and Economic Analysis of Small scale Farming of Jatropha curcas.

5

CHAPTER 2: LITERATURE REVIEW

2.1BACKGROUND

Jatropha is actually a genus of nearly 175 species of shrubs, low-growing plants, and trees.

However, discussions of Jatropha as a biodiesel are actually talking about a particular species of

the plant, Jatropha curcas, which is also called Barbados nut in Central America and has been

known as Physic nut or Pourghere in parts of Africa and Asia. Jatropha curcas is a perennial

shrub that, on average, grows approximately three to five meters in height. It has smooth grey

bark. The leaves are large and usually pale green and the plant produces flowers. Fruits are

produced in winter or throughout the year depending on temperature and soil moisture. The

curcas fruit contains 37.5% shell and 62.5% seed [1]. Seeds are said to resemble castor in seed

shape and black in color. They are 42% husk and 58% kernel [1]. Seeds are encased within green

capsules in the plant‟s fruit. Seeds often become mature when the capsules change from green to

yellow.

Figure2.1 : A picture of Jatropha mature seeds [22]

Jatropha curcas can be grown from either seed or cutting. For plants started as seed, germination

is achieved within nine days and yielding begins between nine and twelve months. However,

effective yields as approximated in numerous studies only can be obtained after about two years.

6

Generally, multiplication of the Jatropha plant occurs through cuttings rather than by seeds

because such a process produces faster results. Since Jatropha is a perennial plant ploughing and

planting are not needed regularly. Through estimations the shrub will live approximately forty to

fifty years and will produce seeds three times per annum [2].

The plant is indigenous to parts of Central America and especially Mexico which is

believed to be the plant‟s origin; however it has spread to other tropical and subtropical regions

in Africa and Asia (see Figure 2 for the regions in which Jatropha is cultivated). Specifically,

Jatropha is being grown in Benin, Brazil, China, Egypt, Ethiopia, Ghana, Guinea, India,

Madagascar, Mali, Mexico, Mozambique, Namibia, Senegal, South Africa, Sudan, Tanzania,

Uganda, Zambia, Zimbabwe and most recently Kenya.[3]

Figure2.2: Global indication of the most suitable climate conditions for the growth of

Jatropha

As evident by the number of countries in which it is being cultivated, Jatropha curcas grows in a

7

variety of climates and soils. There are reports that the plant can be established in gravelly,

sandy, degraded or acidic soil however such a contention lacks scientific consensus [4]. Some

studies have highlighted the stunted growth of the plant in areas with heavy metal contamination.

There is also some evidence that Jatropha curcas has the possibility for reclaiming marginal soils

by re-anchoring the soil with its substantial root system. In theory, the plant‟s deep roots would

recycle nutrients, and reduce the possibility of erosion [5]. Research studies in parts of India

have demonstrated that soil structure increased 18 months after Jatropha curcas was planted yet

despite this evidence it is widely known biologically that rooting patterns vary based on

propagation method (i.e the method by which the plant was cultivated either by cuttings or by

seed germination).While plants originating from seeds improved soil quality (because they grew

a thick primary tap root), plants propagated by cuttings never developed a primary root system

and therefore had little effect on soil quality (and were less hardy in sandy areas).

Figure2.3: Photo of Jatropha seeds

8

2.2 THE PLANT

2.2.1 Sowing and germination

Germination is fast, under good conditions and is complete in ten days. Germination is epigean

(cotyledons emerge above ground). Soon after the first leaves have formed, the cotyledons

wither and fall off. In the nursery, seeds can be sown in germination beds or in containers.

Although the seedlings grow very fast they should stay in the nursery for 3 months until they are

30-40 cm tall. By then the plants have developed their repellant smell and will not be browsed by

animals. Physic nut can be established from nursery seedlings, bare root or containerized, by

direct sowing, trans-planting of wildings or planting of cuttings. The choice of propagation

method depends on use. Plants propagated by seeds are generally preferred for the establishment

of long-lived plantations for oil production. Direct sowing should only be used in areas with high

rainfall and the seeds must be sown after the beginning of the rainy season when sufficient

rainfall is certain. For quick establishment of hedges and plantations for erosion control, directly

planted cuttings are best suited. Cuttings of 30 cm length have been found to have the highest

survival rate. Plants propagated by cuttings will normally produce seed within one year of

planting and growth is rapid.

A unique feature of Jatropha curcas is its natural high level of toxicity, which acts as a deterrent

to pests. This defense though, should not be overstated; The assumed tolerance of Jatropha

curcas to pests and diseases that have been reported are merely based on observations of singular

and solitary trees, and do not apply in general to Jatropha curcas grown in plantations. The toxic

characteristics of Jatropha curcas caused by constituents in leaves, stems, fruits and seeds may

suppress damaging effects from some predators, but certainly not all. In plantations, especially

under humid conditions, serious problems have been reported with fungi, viruses and the attack

of insects. Despite these reservations, Jatropha is comparatively hardier than other oil-producing

crops. In addition to the plant‟s ability to grow in poor soil and deter pests, it also adapts well in

vary rainfall conditions. The plant is resistant to a high degree of aridity and also can survive

with a large amount of rainfall; very little irrigation is necessary.

The current distribution shows that introduction of the plant has been most successful in

9

the drier regions of the tropics with annual rainfall of 300-1000 mm. It occurs mainly at lower

altitudes (0-500 m) in areas with average annual temperatures well above 20°C but can grow at

higher altitudes and tolerates slight frost. It grows on well-drained soils with good aeration and is

well adapted to marginal soils with low nutrient content. Jatropha curcas is also highly adaptable

which has led to its cultivation for a number of purposes throughout the world. Yet uncertainties

abound here as well; because the plant has not been domesticated (i.e. has wide genetic variation

and has not been cultivated on a large scale), none of these studies assume the close planting of a

number of the shrubs in a singular location like a plantation. Some scholars speculate that

clustering would reduce the plants adaptability to highly arid climates.

While there are a number of reasons Jatropha curcas is grown, arguably the biggest one is

as a potential biodiesel fuel. Jatropha curcas is attractive to investors in part because of the

biological characteristics of the seed‟s oil. Because the oil has low acidity and good oxidation

stability as compared to soybean oil, lower viscosity as compared to castor oil, less of a

processing cost than corn ethanol, and better cold properties as compared to palm, it is

potentially very valuable. Additionally, the use of non-edible vegetable oils compared to edible

oils is very significant because of the tremendous demand for edible oils as food and they are far

too expensive to be used as fuel at present. Despite the potential benefits to this oil over other

biodiesels, the higher viscosity when compared to traditional diesel put Jatropha curcas at a

competitive disadvantage.

Figure 2.4: Photo of Jatropha plantation in Kambu area

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2.2.2 How it is planted

The Jatropha tree mostly grows in any type of soil be it in areas with good fertile soils or in areas

where the soil is poor for example in arid and semi-arid regions.

The tree is spaced 2 by 2 meters apart and can be planted using the seeds or by use of cuttings.

Plants that can be intercropped with Jatropha include tomatoes, pepper and Napier grass.

2.2.3 Uses of the Jatropha curcas and its oil

There are numerous uses for Jatropha curcas products apart from producing biodiesel and some

of these uses are age-old. For instance, Jatropha curcas was traditionally used as a hedging plant

in parts of India to protect agriculture and livestock and it was used in some areas in Africa as a

grave marker. In addition to the seeds being used for the production of oil as a fuel source or for

lighting and cooking, the seeds have also been used as insecticide. Once de-shelled, the glycerin

within the almond of the seed can be used to make soap. The pressed cakes that remain after oil

has been extracted are often used as organic fertilizer because of their high concentration of

nitrogen. In addition, the Jatropha wood and the seed cakes both can be used as firewood or

charcoal and also to build traditional houses in some parts of Africa [5]. Due to the toxicity of

the plant, the oil extract could be used as a natural pesticide if cultivated correctly. Jatropha has

also been used for much time as a natural remedy and medicine: Jatropha curcas is a little known

herbal drug of Unani medicines. It is a potential source of herbal drug in dental complaints. The

milky sap of Jatropha curcas is used in Mesoamerica for the treatment of different dermato-

mucosal diseases. Historically, the leaves of the plant have been used to make tea to treat malaria

and the sap is often used by some cultures to stop bleeding. In aggregate, there are numerous

uses to the plant when considering it in holistic terms, making it an attractive candidate to many

investors and farmers. [5]

2.3 OIL EXTRACTION

Oil has to be extracted in order to be processed and refined. The theoretical maximum amount of

oil in a Jatropha curcas seed is 44% (44g oil per 100g Jatropha seed kernels). There are various

methods by which oil can be extracted from the Jatropha curcas seed ranging greatly in both cost

and efficiency. The oil extraction methods can be divided into three primary categories: [9] [10]

11

1. Crushing the seeds with a press

2. Aqueous enzymatic oil extraction

3. Three phase partitioning

Examine the Table to compare their relative efficiencies of extraction

Table2.1: Table to compare their relative efficiencies of extraction [4]

Method Oil Yield

Theoretical Maximum 44.00%

Presses

Hand Press 22.55%

Motor Press 22.98%

Industrial Press 27.00%

Aqueous Oil Extraction

Basic AOE 16.72%

AOE with sonication 29.48%

Aqueous Enzymatic Oil Extraction

(AEOE) 28.16%

AEOE with sonication 32.56%

Three Phase

Partitioning

Basic TPP 36.08%

Enzyme Assisted Three Phase

Partitioning (EATPP) 40.48%

EATPP with sonication 42.68%

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2.3.1 Oil Extraction Efficiency

The method we are mainly concerned with at this juncture is by use of the Mechanical Press

which is mainly used many small-scale production centers (such as in Mali or Tanzania), where

oil is extracted using the manual ram-press and the electric screw-press.

The chemical extraction methods which are Aqueous enzymatic oil extraction and Three phase

partitioning have shown through preliminary studies that they have a higher yield than crushing

the seeds with a press which can be clearly seen from the table of oil extraction efficiency.

2.3.2 Oil as fuel

It is significant to point out that, the non-edible vegetable oil of Jatropha curcas has the requisite

potential of providing a promising and commercially viable alternative to diesel oil since it has

desirable physicochemical and performance characteristics comparable to diesel. Cars could be

run with Jatropha curcas without requiring much change in design.

2.4 ADVANTAGES OF USING JATROPHA OIL

1. The higher cetane number of biodiesel compared to petro-diesel indicates potential for

higher engine performance. Tests have shown that biodiesel has similar or better fuel

consumption, horsepower, and torque and haulage rates as conventional diesel.

2. The superior lubricating properties of biodiesel increases functional engine efficiency.

3. Their higher flash point makes them safer to store.

4. The biodiesel molecules are simple hydrocarbon chains, containing no sulfur, or

aromatic substances associated with fossil fuels.

5. They contain higher amount oxygen (up to 10%) that ensures more complete

combustion of hydrocarbons.

6. Biodiesel almost completely eliminates lifecycle carbon dioxide emissions. When

compared to petro-diesel it reduces emission of particulate matter by 40%, unburned

hydrocarbons by 68%, carbon monoxide by 44%, sulphates by 100%, polycyclic

aromatic hydrocarbons (PAHs) by 80%, and the carcinogenic nitrated PAHs by

90% on an average. [8]

13

CHAPTER 3: CASE STUDY

3.1 INTRODUCTION

In recent years, the production of Jatropha curcas has been widely promoted by private

enterprises, non-governmental organizations and development agencies as one of the most viable

candidates for biodiesel feedstock in Africa.

The biofuels industry is growing rapidly as a result of high petroleum prices and increasing

concerns about global climate change. Ethanol from sugarcane in Brazil and corn in the United

States, and biodiesel from rapeseed in European Union countries have been successfully

commercialized as petroleum product substitutes with government support. In Africa, Jatropha

curcas (Jatropha) is considered to be one of the most viable candidates for biodiesel feedstock

mostly due to its adaptability to semi-arid lands. Biodiesel promoters regard this “low productive

land” (or often called “marginal” or “waste” land) to be largely available for new agricultural

development.

Jatropha is a large shrub or small tree reaching a height up to 5 meters [11]. After having been

introduced to Africa centuries ago, it is now widely observed in semi-arid lands throughout the

drier area of continent. In Kenya, Planting of Jatropha has been around Coast province and

Eastern province where it is grown as a hedge, boundary marker and in large scale. Jatropha is

also intercropped with vanilla (Vanilla planifolia) to serve as a pole for vanilla vines and to

provide shade for vanilla leaves in some part of Tanzania. In these and other African countries,

the extracted oil from Jatropha seeds has been used for soap making, lighting and for fertilizer.

Jatropha production has been promoted for its perceived economic and ecological advantages.

From the perspective of private investors, it is a newly available energy crop that is expected to

be less expensive to produce than other energy crops such as rapeseed and soybeans. This

argument is based on the availability of low-cost labor and land in Africa. Not only private

enterprises, but also non-governmental organizations and development agencies are interested in

supporting Jatropha development in Africa as a means for rural development and poverty

alleviation. Jatropha biodiesel production is expected to contribute to the improvement of rural

livelihood because the main production location for Jatropha is in semi-arid lands where poverty

levels are high and land productivity low.

14

Thus Jatropha appears to be the potential crop that enables “win-win” relationship among all the

actors in the value chain– the biofuel industry to gain profit, society as a whole to achieve

mitigation and energy security, and the producers to improve their livelihoods.

This part of the research consists of two parts. The first part discusses the viability of biodiesel

value chain in current Kenyan market conditions by examining the price competitiveness of

biodiesel in the Kenyan market and the profitability of Jatropha production as a biodiesel

feedstock in terms of expected yield, revenue and opportunity cost of production. After

presenting the results of the analysis, the second part of the research discusses how Jatropha

could positively be introduced to local communities for improvement of rural livelihoods.

3.2 METHODOLOGY OF THE RESEARCH

Data and information for this project were collected through interviews with stakeholders and

visits of Jatropha production sites in Mtito Andei. The stakeholders who are engaged in initial

experiments of Jatropha and biodiesel production in Kenya include project developers such as,

NGOs and private companies, policy makers at relevant government ministries, and local

farmers and extension officers. The production sites that were visited included the villages of

Kibwezi District, Kambu Division e.g Ngwata, Nzambani, Mangelete in Mtito-Andei. Jatropha

production started since 2005-2006 in Kenya.

15

Figure3.1: A map showing Kambu area (central point of the case study) [21]

16

3.3 ECONOMIC VIABILITY OF BIODIESEL

Biodiesel production is considered to be economically viable when it is price competitive with

other Petroleum products. The cost of biodiesel production is greatly affected by the cost of

feedstock production. As the feedstock for biodiesel could be any vegetable or animal fat,

Jatropha oil is only economically viable when it is price competitive with available alternative

oils. This section first examines the viability of biodiesel production in the current Kenyan

market, analyzing the competitiveness of biodiesel with petroleum products and the market price

of Jatropha oil and seeds in Kenya. It then examines the profitability of Jatropha production as

biodiesel feedstock for smallholder farmers.

3.4 PRICE COMPETITIVENESS OF BIODIESEL

Jatropha was first introduced in Kenya in 2005, when local farmers started small-scale

production in the Districts of kibwezi, kitui, Makueni and Malindi.

There have been no actual sales of Jatropha oil in the Kenyan market at the time of the study

(March, 2012). In order to estimate the price of biodiesel in Kenya, the price of alternative

vegetable oils that are available was used as an indicator. Palm oil is assumed to be the main

alternative to Jatropha. Crude palm oil has been the major imported vegetable oil into Kenya for

the past decade in terms of both quantity and value. The commercial price of Jatropha oil is thus

expected to be less than that of crude palm oil. In 2012 the price of palm oil is 1,434,826 tons

($1.61 billion) that is about $1.122 per kg.

3.4.1 Price of Jatropha seeds and oil

In Kenya as by the consulted N.G.O (vanilla Jatropha) the price of 1kg of seeds is ksh.15 and

that of Jatropha crude oil is ksh.100 to big companies and ksh.60 for refined oil to Jatropha

farmers and the area community at large.

3.4.2 Jatropha biodiesel profitability production.

Currently three different modes of Jatropha production are taking place in Kenya: monoculture

mixed intercropping, hedges and intercropping with vanilla. In Kibwezi District where Jatropha

production has been introduced by non-governmental organizations, some farmers are converting

their farms into Jatropha plantations, although they intercrop Jatropha with other food crops for

17

the first year when Jatropha is relatively small. Some farmers with limited landholdings have

decided to experiment with growing Jatropha as a hedge. However, the majority of farmers in the

area are observing their neighbors‟ production of this new crop to see how profitable it will be.

3.5 EXPECTED YIELD

This section estimates the yield and expected revenues of Jatropha production and analyzes the

potential economic returns of adopting Jatropha production by smallholder farmers.

Jatropha yields depend on surrounding conditions i.e. varying climate, soil fertility, landform,

altitude, and water and fertilizer inputs.

Francis, Edinger and Becker [12] estimate the annual seed production per plant to range from

about 200 grams to more than 2 kilograms. Yield varies significantly depending on the water

input, which determines the number of fruiting period per year, which can vary from one to three

kilograms per tree. From the information taken from Kambu, Jatropha farmers harvest the plant

twice a year and one plant produces between 1kilogram of seed in the rainy season and about

500 grams during the dry season in the first three years. After 5 years, the production per tree

ranges from 1.2 kilograms under rain fed conditions to 3.2 kilograms under irrigated conditions.

There are two rainy seasons in Kenya, and the seasons and periods vary in each region. The

average annual rainfall during two rainy seasons is 329.3mm (April-June) and 372.4mm

(October-December) in Kibwezi District.hence more harvest is seen during this two periods.

.

3.6 REVENUE AND OPPORTUNITY COST OF JATROPHA PRODUCTION

Farmers‟ decisions on starting to farm Jatropha depend upon the returns that they expect to get.

In this section we compare the revenues that Kenyan farmers are likely to obtain by growing

Jatropha with the revenue streams and profit margins of other crops they can grow on the same

land. In Kibwezi the other cash crop that is mainly grown is a cow pea which only yields once a

year. It produces about 320-680 kilograms per acre.

18

Figure3.2: Cow peas grown at Kambu

Compared to Jatropha that produces 500 kilograms to 1000 kilograms per acre, hence Jatropha

would be an attractive crop to grow for smallholder farmers in Mtito andei.

3.7 CONTRIBUTION OF JATROPHA TO IMPROVEMENT OF LOCAL

LIVELIHOODS

There are two scenarios for introducing Jatropha production to local communities.

The first scenario is large-scale production where private enterprises take initiatives to produce

large amounts of biodiesel and local populations are incorporated into the production process as

wage laborers on plantations or contract suppliers of seed.

A second scenario is the case of small-scale decentralized biodiesel production. Local

populations grow Jatropha seeds which are collected through local collection systems, and

Jatropha biodiesel produced in small oil pressing and processing facilities. Facilities could be

operated by community groups, cooperatives or private enterprises. For example in Kambu

Vanilla Jatropha NGO has opened a seed collecting Centre where it has installed a pressing

machine that presses the seeds delivered by the farmers.

3.8 JATROPHA OIL LOCAL LIVELIHOOD IMPROVEMENTS

From the above discussion, it appears that the opportunity for local populations to maximize

benefits from Jatropha is to engage not only Jatropha production but also in oil extraction.

19

Locally extracted oil can be directly used in diesel engines or as a kerosene substitute for lamps

and stoves [11].

Jatropha oil is much less expensive than kerosene so its use could contribute to savings for local

communities and poor urban households. According to a survey administered to 2,300

households in 15 rural districts and five urban centers in Kenya by the Ministry of Energy in

2000, 82% of urban and rural households used kerosene for lighting in lanterns, tin lamps and

pressure lamps, and 88% used kerosene for domestic cooking. The kerosene consumption per

household in urban areas was an average of 90 liters per year compared with 41 liters per year in

rural areas, while per capita consumption was an average of 23 liters per year in urban areas and

8.6 liters per year in rural areas. Kerosene is mainly used for lighting in rural areas and for both

lighting and cooking in urban areas [12]. Despite the reliance on kerosene by low income

households, kerosene, like other petroleum products, has become less affordable for low income

population in recent years. The landed price of kerosene has gone up by 2.5 times from ksh.35

(2005) to ksh.85 (2012).

Jatropha oil might be most competitive with kerosene when produced in rural areas close to the

source of seed supply. Special lamps and stoves designed for Jatropha oil have been developed

and tested locally.

Figure3.3: Picture of the Jatropha oil lamp

The successful promotion of Jatropha oil for cooking depends on the availability and

affordability of other energy sources (e.g. fuel wood, charcoal, liquid natural gas, etc)

20

Currently, the most promising and well developed uses of Jatropha are for soap and candle

making.

3.6 GOVERNMENT POLICY ON JATROPHA BIODIESEL PRODUCTION FOR THE

IMPROVEMENT OF LOCAL LIVELIHOOD

Government policy plays an important role in fostering growth of the biodiesel industry. Active

government support has been essential in every country where biodiesel and other biofuel

industries have been successfully established.

By supporting the biodiesel industry, governments of oil-importing countries accrue benefits

such as increased energy self-sufficiency, foreign exchange savings, and income from the growth

of agricultural sectors and new biodiesel industries. As a country without proven petroleum

resources, Kenya‟s economy is vulnerable to increases in the prices of petroleum products

Governments must make careful decisions on whether the benefits from supporting the biofuel

industry would exceed the loss of government tax revenue that would result from lower imports

of petroleum products [13]. As in other oil importing countries, biofuel policy is under

discussion in Kenya.

In Kenya, various stakeholders in biodiesel industries formed the national biodiesel committee in

January 2006 under the Ministry of Energy to have a collective voice in promoting policies such

as blending mandates, tax mandates and production subsides [14].

21

CHAPTER 4: JATROPHA SEED OIL EXTRACTION AND CAKE

DRAINAGE SYSTEMS.

4.1 JATROPHA SEED OIL EXTRACTION

The major aim of all screw press machines is to generate compression for extraction of oil in the

seeds but there are several differences in design of the pressing shaft and drainage mechanism

principles. The oil presses used in industry are described in following subsections followed by

the mechanisms used in cake drainage.

4.1.1 Komet Oil Presses

In this type of screw press, oil leaks out from the holes as represented in Figure4.1. The holes are

drilled on the vessel. The oil drainage hole has a larger diameter outside the vessel and this

diameter continues up to few millimeter thickness of the vessel. This small thickness of the

vessel is drilled with a smaller diameter. Most probably, the reason for the short length of the

smaller hole is to prevent it from choking with cake. Also, oil drainage zone is far from the cake

drainage zone. At the cake drainage zone, cake pressure is maximum. So, if the oil drainage

holes were drilled close to the cake drainage zone, then the holes can be choked with cake easily.

Dry cake extrudes from the nozzle. At the cake drainage, there is a heating system. Heat provides

higher oil yield and lower residual oil in the cake. In this type of screw presses, different kinds of

seeds can be compressed by changing the nozzle and the rotational speed of the screw shaft. [16]

Figure4.1: Detailed Picture of Screw Press Manufactured by Oekotec, IBG-Monforts [16]

22

4.1.2 Rosedowns Oil Presses

A complete system of a Rosedowns screw press is represented in Figure4.3. The system is

divided into subgroups as:

4.1.2.1 Main Gearbox:

It transmits the power of the motor to the screw shaft. Gearboxes should be separated as far as

possible for the hot and dirty environment of the pressing sections. The feeding section of the

screw shaft is the cooler and lower pressure end of the press. Therefore the best choice for the

drive position is the feeding end of the screw shaft. [17]

4.1.2.2 Feeding Section:

It is composed of mainly three parts which are the feed inlet, the horizontal feeder and vertical

feeder. Seeds are poured into the feed inlet. Then with the help of the variable speed drive of the

horizontal feeder, the flow of feed is controlled. Vertical feeder prevents bridging in the cage

inlet and ensures that the seeds pass into the vessel. [17]

4.1.2.3 Bearings:

There are two kinds of bearings. One of them is called thrust bearing and it carries the thrust

loads generated by the press. The other bearing is the discharge end bearing and it is used for

supporting the shaft when there is no load or light load inside the press. Without this bearing, the

screw shaft can hit inside the walls of the vessel. [17]

4.1.2.4 Cages:

For longer presses, the cage is divided into two parts in order to keep the main cage to a more

manageable size for maintenance operations. The inside cage is composed of lining bars

separated by spacers. The size of the spacers can be altered for different kinds of seeds by

changing the drainage gaps. [17]

4.1.2.5 Screw Shaft:

The screw shaft is the key functional part of a screw press. The screw shaft has multi-stage

compressions in order to reduce the required pressure. In recent years the multi-stage, lower

23

compression screw shaft has led to significant improvements in performance, wear life and

power consumption. As represented in figure4.2, at the compression stage, the screw shaft

becomes tapered where the inside vessel diameter decreases. Therefore, pressure increases at the

decreased annular area which results in compression of seeds. [17]

Figure4.2: Detailed views of the screw shaft of Rosedowns Screw Presses [17]

Figure4.3: Detailed Drawing of Screw Press Manufactured by Rosedowns [17]

4.1.3 Vincent Screw Presses

As represented in Figure4.4, a screw of progressively reducing pitch rotates inside a cylindrical

perforated screen. Material entering the hopper is subjected to gradually increasing pressure as it

moves toward the exit end of the press, forcing the liquid phase to extrude through the screen.

Two resistor teeth fit in each interruption of the turn as seen in Figure 8. This interruption

prevents jamming. [18]

24

Figure4.4: Screw with Resistor Bars manufactured by Vincent Corporation [18]

4.1.4 Strainer type screw presses

In strainer type of screw presses, oil rushes out from the strainers which are made up of flat

plates mounted through the screw shaft. By rotating the arm which is at the right end of the

screw press in Figure4.5, the screw shaft can be displaced forward or backward to adjust the

thickness of the cake which is extruded at the left end of the screw press. Accordingly, different

kinds of seeds can be compressed also by changing the rotational speed. [19]

Figure4.5: Strainer Type Screw Press [19]

25

4.2 CAKE DRAINAGE SYSTEMS

The common property of cake drainage systems in screw presses is the adjustability of the cake

drainage opening. Narrower openings result in low residual oil content in the cake. Also, the

opening size depends on the type of the seed.

During our research, various types of cake drainage systems are considered. Some of them are

used in conventional screw presses as presented.

Working principles of these cake drainage systems are presented in the subsections.

4.2.1 Nozzle cake drainage system

Generally, in small types of screw presses, nozzle type choke mechanism is used. In Komet Oil

Presses, this type of a choke mechanism is used [16]. In nozzle type choke mechanisms in

figure4.6, one end of the screw shaft is free and the other end has two bearings. The screw shaft

is short enough to compensate any deformation arising from buckling.

Seeds continue to accumulate at the end of the screw until the maximum pressure has been

reached. During compression, oil part of the seeds leaks from the filter and the left cake starts to

extrude out from the nozzle, at the end of the screw. Besides, the required maximum pressure

can be provided by adjusting the nozzle diameter.

In this type of choking mechanism, the maximum pressure at the end of the screw pushes the

screw backward. The resultant force is the multiplication of the axial component of the

maximum pressure and the circular area of the screw.

Since the application area of the back force is comparatively larger than in conical type of choke

mechanisms, bearing which carries the axial back force should be larger in this type of systems.

Another disadvantage for this choking system is the probability of a blockage at the entrance of

the nozzle.

26

Figure4.6: Nozzle cake drainage system

4.2.3 Conical drainage system

This type of a system in figure4.7 is both practical and economical when compared with the

equivalent systems. In Tiny tech Tiny Oil Mills, this type of a choke mechanism is used [20].

The maximum pressure and the cake thickness can be changed by adjusting axial displacement

of the screw shaft forward and backward in order to achieve the required pressure. The force

pushing the screw backward is relatively less here when compared with the nozzle type choke

mechanism since the effective pressure area is less than the normal cross section

Figure4.7: Conical drainage system

.

Rotating

shaft

Cake out

through a

nozzle

Rotating

shaft

Cone

Cake out

27

CHAPTER 5: PRELIMINARY AND DETAILED DESIGN OF THE OIL

EXTRACTION MACHINE

5.1 PRELIMINARY DESIGN

In this section, design tree and block diagram of the selected system, separation of the system

into subsystems and specifications of these subsystems are given.

5.1.1 Design Tree

In the design tree of the extraction machine, the system is separated into its subsystems to

analyze the design from top to bottom. Components of the Machine are represented. The screw

press is composed of skeleton, hopper and vessel, connection elements and drive system.

Skeleton carries the hopper and vessel body. Hopper is mounted onto the vessel. Drive system is

connected to the end of the screw shaft via a pulley. The shaft is held in position by two bearings

mounted on the skeleton

Components are represented in fig5.1

Figure5.1: Design tree

SKELETON

HOPPER VESSEL SCREW SHAFT CONE

TANK CAKE

28

Seeds are fed into the system from the hopper and pass through the screw shaft which

concentrically fitted into the vessel as oil drains out through the holes around the vessel and at

the end of the vessel the cake is drained out. The oil then drains into the tank placed just below

the vessel.

5.1.2 Skeleton

Skeleton is composed of the stand and the bearing bushings. It carries the main body (vessel,

shaft and hopper). The screw shaft is bedded with the bearings. The bearings are elevated to a

height where the screw shaft can rotate concentrically inside the vessel.

The oil tank is placed just below the main body onto which the oil drains out after it has been

squeezed out of the Jatropha seeds by the shaft.

Figure5.2: Photo of the skeleton

Main body

29

5.1.3 Main Body

The main body is composed of three parts which are the screw shaft, the vessel and the hopper.

Their functionalities are described in the following subsections.

5.1.4 Screw Shaft

The seeds are compressed in two ways. First way of compression occurs by the continuous

feeding of the seeds into the system. Newly fed seeds compress the seeds which are already

present in the system Another way compression takes place is between the inside surface of the

vessel and inside surface of the screw shaft. As the depth of the thread decreases continuously,

the distance between thread surfaces decrease as a result the seeds volume reduce as oil is

drained out. For these reasons, this type of screw shaft configuration is evaluated as the most

appropriate one for this project.

Screw shaft rotates inside the vessel. There is a small clearance between the vessel and the screw

shaft. This small clearance is necessary for avoiding the seeds penetrating between the outside

diameter of the screw shaft and the inside surface of the vessel. In such a case, friction force

between the screw shaft and vessel increases, and required torque becomes higher.

The screw shaft pitch reduces down the vessel as a result more pressure is applied on the seeds.

The seeds are fed at where the thread depth is maximum. As the seeds pass through the screw,

swept volume of each turn decreases. Under high pressure, oil is separated from the compressed

seeds and drains back to the previous turns at where the pressure is lower. Since cake has no

such fluidity property like oil, it continues to the end of the screw shaft and drained out as flakes.

At the end of the last thread on the shaft there is a cone which allows a narrow Cake to drain out

radially between it and the vessel surface. By adjusting the screw shaft in the longitudinal

direction, the gap size of the cake drainage can be reduced or increased. As the gap size is

smaller, the residual oil content of the cake becomes lower, because the compressed seed is

applied higher pressure

30

Figure5.3: Shaft

5.1.5 Vessel

The vessel has a rectangular hole which allows the seeds from the hopper into the beginning of

the screw shaft where the thread pitch is maximum. It has holes all round from which oil drains

out into the tank.

The oil drainage zone is slightly far from the cake drainage zone or in other words, the maximum

pressure zone. The reason is that, these small holes are filled and choked with compressed cake

at high pressure levels. However, on the mid zone of the vessel, pressure of the cake is not that

much high and oil can easily pass through these holes.

Figure5.4: Vessel

5.1.6 Hopper

Hopper is used to carry and canalize the seeds into the screw press. Feeding does not need any

energy; gravity is sufficient for feeding. It is a stationary part and mounted onto the vessel. The

passage hole of the hopper is large enough in order to prevent choking of the seeds into the

vessel.

Rectan

gular

ho

le

31

Figure5.5: Hopper

5.1.7 Tank

This is where the squeezed oil is drained to awaiting transfer to the storage containers. It is

placed just below the vessel and it contains lid which has many holes.

Figure5.6: Tank

5.1.8 Cone

The maximum pressure and the cake thickness can be changed by adjusting axial displacement

of the screw shaft forward and backward in order to achieve the required pressure. As a result the

amount of cake out of the cone is adjusted hence the maximum amount of fuel can be obtained.

32

Figure5.7: Cone

5.1.9 Drive system

This system comprises of a motor two horsepower, 2 pulleys (10cm and the other 250cm

diameter) and a v belt. The 250cm pulley is connected onto the pressing shaft while the other

10cm pulley is connected onto the motor shaft. The pulley connected to the pressing shaft is 25

times the diameter of the pulley connected to the motor shaft.

33

Figure5.8: Drive system

Pulley

V belt

Motor

Pulley

34

5.2 DESIGNED MACHINE OUTLOOK

Figure5.9 shows the oil pressing machine with all the parts described above assembled in it.

Figure5.9: Fully assembled machine

35

5.3 DETAIL DESIGN CALCULATIONS

5.3.1 Experiment 1: oil cake ratio of pressed seeds

An experiment was done to determine the ratio of a given volume of un-pressed seeds to the

volume of the pressed seeds.

Figure5.10: Experimental seeds pressing diagram

Using a pipe of length 152mm the seeds were put to a height of 84mm and then pressed using a

hand press until the new height of pressed seeds (cake) was found to be 15mm.

Hence the ratio of volume of un-pressed to pressed seeds

This ratio led to the design of the pressing shaft threads

Plunger

Pipe

Oil o

ut

36

5.3.2 Experiment 2: Determining the density of the Jatropha seeds

A jug of known dimensions was filled up with seeds and weighed

Results

Volume of the jug=0.00308m3

Weight of seeds =1.08kg

Hence density of seeds=3

Calculation of area of the shaft threads

Shaft diameter=25.4mm

Shaft with thread diameter=45.4mm

Hence the area of the shaft threads=

Taking the pitch of the first thread of the shaft to be 140mm the volume of the seeds crushed

when it is fully surrounded with seeds.

Area at entrance * pitch at entrance =

From experiment 1 the compression ratio was 1:6 but for complete compression of the seeds the

ratio was taken to be equal to1:7.

Hence the exit pitch length=140/7=20mm

Taking the pitch at exit to be 20mm

Volume at exit=

5.3.3 Calculation of revolutions per second of the pressing shaft.

Mass of seeds in entrance thread=density of seeds * volume at entry

37

=

From the project objective of designing a machine that can crush 100kg of seeds/hour

Writing in revs/second =

5.4 THREAD DESIGNING

Circumference of the 1inch diameter shaft=

Thread length for the first pitch of 140mm will be?

Figure5.11: How to generate thread profile at a pitch of 140mm

From Pythagoras theorem

Thread 2 to has a pitch of 120mm hence its thread length will be

80mm

140mm

Thread length profile

38

Figure5.12: How to generate the thread profile at a pitch of 120mm

From Pythagoras theorem

The table below summarizes the remaining thread profile lengths used for various pitches

Pitch (mm) Thread length (mm)

140 161.25

120 144.22

100 128.06

80 113.14

60 100

40 89.44

20 82.46

Table5.1: Summary of thread length profiles for given pitches

Thread length

profile

80mm

120mm

39

Resultant thread profile

Figure5.13: Resultant thread profile

5.5 HOW THE THREADS WERE PLACED ON THE SHAFT

An annular disc was cut out of a sheet metal. The inner diameter being the thread length while

the difference between the inner diameter and the outer diameter being the thread thickness.

Then the annular disk was cut and stretched on the thread profile as shown in the figure below.

Cut here

Figure5.14: An annular disk that was cut to form threads on the shaft

Resultant thread profile

40

After the disc has been cut it is stretched on the shaft as shown to form a thread on the shaft as

shown below.

Figure5.15: Showing how cut annular disc was cut to form threads

The inner diameter is given by using the thread length as the circumference of the disc

For example the annular disc for the first thread.

Circumference=161.25= πd

Therefore d=51.32mm

Stretch the annular cut disc Stretch the cut annular disc

41

A table giving details on how different materials were machined.

FIGURE PART NAME OPERATION

WIDTH ANGLE

LINE

It is made from Mild Steel.

Appropriate length cut on the power saw.

VESSEL The feed space for the seeds was cut on the

milling machine.

The holes were drilled on the pillar drill.

STAND ANGLE

LINE

It is made from Mild Steel.

Appropriate length cut on the power saw.

SHAFT The threads were Arc welded on the shaft

following a profile marked on the shaft.

42

MAIN BODY The hopper and the pipe were joined together

by Arc welding.

The hopper was carefully positioned on the

feed space.

LID Mild Steel sheet metal was used.

The holes were drilled using a Pillar Drill.

LENGTH ANGLE

LINE

It is made from Mild Steel.

The appropriate length was cut on the power

saw.

HOPPER Made from sheet metal appropriately cut.

It was joined by Arc Welding.

END PLATE Carefully cut on the Lathe machine to the right

dimensions.

It was then Arc welded on the pipe.

43

COUPLING It was cut using a Hack saw from a pipe.

The holes were drilled on the Pillar drill.

BEARING

SUPPORT

It was cut from sheet metal made from Mild

Steel using a Guillotine Machine.

TANK The sheet metal used to make it is Mild Steel.

The different parts were joined by Oxy-

Acetylene welding.

Table5.2: Typical parts of the machine

44

CHAPTER 6. DISCUSSION AND CONCLUSION

CASE STUDY

In Eastern province of Kenya in Kibwezi area, a small town known as Kambu was the centre of

our case study. Kambu is a semi-arid area with no substantial crop farming due to its

unfavourable climate which does not support the growth of most food crops. Most of the land in

this area is not cultivated and is mostly used for the pasture of domestic animals. The land

currently being cultivated is quite small and for the plants to grow there has to be some form of

irrigation. The plant that grows there in abundance is cow peas which are grown commercially.

Thus the general population of the area is poor due to lack of a sustainable economic activity

which generates a steady income for the locals. Also the rising cost of living due to inevitable

rise in fuel costs does not help alleviate the situation. The Jatropha curcas plant which has been

found to readily thrive in the area due to its preference to semi- arid conditions is the answer to

some of the problems in the area. The plant which can produce oil which can be converted to

biodiesel would give the area a clean and affordable source of energy for daily use by the locals.

It would also provide a source of income to the farmers by selling their otherwise valuable seeds

which would be used to make bio-diesel after the oil has been processed in a plant.

THE OIL PRESS MACHINE

Thus there was a need for small scale oil pressing machine which could be used to extract oil in

small quantities depending on the amount of seeds which a particular farmer has got. The

machine needed to be mobile such that it could be easily moved from one point to another. The

design of the machine was based on the fact that different farmers would have different

quantities of seed and thus the oil pressing machine needed to press a small amount of seeds or a

large amount of seeds if need be. The machine that was fabricated has a theoretical seed

pressing capacity of 100 kg/hour when it is running at a speed of 30 revolutions per minute and

its prime mover is a 2 horse power electric motor.

45

FABRICATION OF THE OIL PRESS MACHINE

Fabrication of the oil press machine was done in the University of Nairobi Mechanical

Engineering Workshop. Some of the materials needed for fabrication of the machine were

available in the workshop but most of the other materials were outsourced from hardwares and

scrap metal dealers the major material used was mild steel. The machines used to make the

machine components included lathe machines, milling machines, Guillotine machine, Pillar drill,

Folding machine, Arc welding machine and an Oxy-Acetylene gas welding machine.

The fabrication process was involving and we had to spend extra time in the workshop to ensure

that the components were completed on time. It took about six weeks to complete the various

components and finally assembly to complete the machine. The major challenge came during

assembly of the various parts to form a complete unit. Some of the components needed some

modifications like grinding or further machining to enable them to fit as expected initially. The

shaft and pipe assembly posed a major challenge when it came to assembling the two parts since

the clearances between the pipe and the shaft were too small. The bearings at each end of the

shaft mounted to the main body also brought forth major problems when it came to place the

shaft at a central position relative to the pipe for smooth running of the press since the height of

the pillow block bearing had to match the height of the centralizing bearing. Thus the pipe had to

be held at a constant position relative to the pipe and also the shaft had to be maintained at a

certain position lateral to the pipe and all this had to be maintained during welding of these parts

into position. Obviously this was a tedious process and it had to be redone several times before a

correct position could be attained so that the shaft would be able to move freely without having

any contact with the pipe to avoid locking of the system during operation.

Also due to the method of welding used to place the threads on the shaft which was by Arc-

welding the threads were not evenly shaped on the shaft due to extreme heat during the welding

which caused part of the threads to warp and also during cooling the threads assumed some

crooked positions which were otherwise corrected using a hammer and an anvil which did not

result in a very accurate profile of the thread.

The oil press machine needs a powerful prime mover with the necessary torque to create the

adequate pressures to ensure compression of the seeds to produce oil. The lack of adequate

resources handicapped us in terms of design of the gear system needed to transfer motion from

the prime mover to the shaft effectively. Gears are expensive to manufacture and equally

46

expensive to buy thus we opted to use a simple belt and pulley system which would be used to

transfer power from the prime mover to screw press.

ACTIVITY SIZE AMOUNT (Ksh)

Angle Beam 914 cm length, 2 inch beam 4,000

Cylinder 52 mm diameter, 762 mm length, class B 1,000

Shaft 762 mm length, 1inch diameter 600

2 Pulleys 25 cm diameter and 10cm dia. 1500

1 Belts V-belt, 12.5mm width ,1800mm and class

A17

4000

1 Motor 2horse power 10,000

Sheet Metal 1m by 1m, Gauge 16 3,800

2 Bearings and Fittings 1 in dia. 3,200

10 Bolts and Nuts M 10mm 500

Labour (15% total

expenses)

4290

TOTAL 32890

Table 5.3: The machine budget

47

TESTING OF THE OIL PRESS MACHINE

Testing of the oil press machine was done in the University Mechanical Engineering workshop

and harvested Jatropha Curcas seeds were used in the test run. The seeds which need to be steam

heated before undergoing pressing were soaked in water instead to prepare them for oil

extraction. The fabricated oil press machine was then connected to a lathe machine chuck by

means of a pulley and belt assembly which was used instead of a Motor which was not available.

In this assembly the machine pressed the initial seeds well and some oil could be seen dripping

from the pipe holes but as compression continued the shaft locked due to clogging near the cone

which was supposed to guide the already compressed cake outside the pipe. The belt and pulley

assembly cold not drive the shaft past this point and the belt started to slip on the pulley even

though the lathe was still driving the pulley.

The cone clearance was also a challenge since we could not exactly establish at the time the

correct clearance we should have left for optimum compression and at the same time it would be

enough for continuous flow of the compressed cake outside the pipe.

48

CONCLUSION

The objectives of the project which were design, fabrication and testing of an electric powered

Jatropha Curcas oil extraction set-up suitable for a remote setting and Technical and Economic

analysis of small scale farming of Jatropha Curcas were achieved.

The design of the oil extraction machine was primarily guided by the need to have the machine

operating in a remote setting but also for the machine to operate effectively it needs a reliable

and effective power source which is electric power. Thanks to the recent Government efforts in

rural electrification electricity would not be an issue for remote areas of the country. The

designed and fabricated oil extraction machine is ideal for the remote setting since it is mobile

and can be easily moved from one point to another, it is also made from local materials which

makes it easier to maintain and repair in cases where it breaks down. The fabricated machine has

a seeds pressing capacity of 100 kilograms in an hour while it is running at 30 revolutions in a

minute using a 2 horse power electric motor. This is quite a large capacity for a small scale

machine but the capacity could be changed accordingly depending on the type of seeds being

pressed by changing the rotating speed of the pressing shaft. The machine was tested and

actually pressed some seeds but clogging of the pipe and shaft assembly led to locking of the

system mainly due to lack of enough torque to press the seeds since we were using a belt and

pulley system and also the undetermined optimum clearance of the cone assembly on the shaft to

guide the pressed cake outside the pipe. Relevant recommendations were given in the discussion

to improve the design and overcome the problems currently experienced during testing of the

machine.

In the case study discussed in chapter 3 of the report a detailed Technical and Economic Analysis

of small scale farming of Jatropha Curcas was carried out in a small town in Eastern province

called Kambu in Kibwezi District. The analysis comprised of an Introduction introducing the

area, its population, farming practices and agricultural potential mainly focusing on the areas

currently under Jatropha farming. Also the price competitiveness of Bio- Diesel , expected yield,

revenue and opportunity cost of Jatropha production and Government policy on Jatropha bio-

diesel production are some of the topics discussed in the case study chapter. This gave us a clear

outline on what was happening on the ground and gave us guidance on how to go about the

whole oil production chain from having the Jatropha Curcas in the farm, harvesting it, extracting

49

the oil and finally making use of the oil in ways that will improve the economy of the local

community.

50

RECOMMENDATIONS

From the observations made during the test run of the oil press machine we propose the

following:

1. Design of an effective power transmission system from the prime mover to the pressing

shaft. Preferably using gears which have the capability of transferring large amounts of

torque compared to belt and chain drives.

2. Design of an adjustable cone and shaft assembly to be able to test for the optimum

clearance needed for the machine to produce the maximum amount of oil without

jamming the pressing shaft.

51

REFERENCES

1 Singh, R.N., D.K. Vyas, N.S.L. Srivastava and Madhuri Narra. 2007. “SPRERI

experience on holistic approach to utilize all parts of Jatropha curcas fruit for

energy.” Renewable Energy: in press: 1-6.

2. Van Eijck, Janske and Henny Romijn. 2008. “Prospects of Jatropha biofuels in

Tanzania: An analysis with Strategic Niche Management.” Energy Policy 36: 311-

325.

3. Henning, R. 1996. “Combating Desertification: The Jatropha Project of Mali,

West Africa, in: The Arid Lands Newsletter” Accessed at:

<http://ag.arizona.edu/OALS/ALN/aln40/jatropha.html>

4 Openshaw, Keith. 2000. “A review of Jatropha curcas: an oil plant of unfulfilled

promise.” Biomass and Bioenergy 19: 1-15.

5. Kumar, Ashwani and Satyawati Sharma. 2008. “An evaluation of multipurpose oil

seed crop for industrial uses (Jatropha curcas L.): A review.” Industrial Crops and

Products: in press: 1-8.

6. Calvin, M.(1985). Fuel Oils from Higher plants: Prepared for the U.S. Department

of Energy.

7. Shah, Shweta, Aparna Sharma, and M.N. Gupta. 2005. “Extraction of oil from

Jatropha curcas L. seed kernels by combination of ultrasonication and aqueous

enzymatic oil extraction.” Bioresource Technology 96: 121-123.

8. Jatropha Curcas - Multipurpose plants and Source of Energy for Future by, Edgar

Munch and Joachim Kiefer (GTZ).

9. Forson, F.K., E.K. Oduro, E. Hammond-Donkoh. 2004. “Performance of Jatropha

oil blends in a diesel engine.” Renewable Energy 29: 1135-1145.

10. Tamalampudi, Sriappareddy, Mahabubur Rahman Talukder, Shinji Hama, Takao

Numata, Akihiko Kondo, and Hideki Fukuda. 2008. “Enzymatic production of

biodiesel from Jatropha oil: A comparative study of immobilized-whole cell and

commercial lipases as a biocatalyst.” Biochemical Engineering Journal 39: 185-

189

11. Heller, J., 1996. Physic nut. Jatropha curcas L. Promoting the conservation and

use of

underutilized and neglected crops. 1. Institute of Plant Genetics and Crop Plant

Research,

52

Gatersleben / International Plant Genetic Resources Institute, Rome.

12. Kenya, 2002e. Study on Kenya‟s energy demand, supply and policy strategy for

households,

small scale industries and service establishments. Final report, September. p.16.

Ministry of

Energy, Government of Kenya, Nairobi.

14. Kituyi, E., 2006. Towards Sustainable Production and Consumption of Biofuels in

Kenya:

Some Issues to Consider. Discussion paper, Vol. 1 No.1. November,

Environmental

Chemistry Division, University of Nairobi, Nairobi.

15. Henning, R.K., 2002. Using the Indigenous Knowledge of Jatropha. The use of

Jatropha

curcas oil as raw material and fuel. Local Pathways to Global Development.

Indigenous

Knowledge Notes, 47, August. The World Bank, Washington, D.C. Available at:

http://siteresources.worldbank.org/EXTINDKNOWLEDGE/Resources/iknt47.pdf.

16. Webpage of IBG Monforts Oekotec GmbH & Co. KG,

http://www.oekotec.ibg-monforts.de, Accessed at 18.04.2012

17. Webpage of De Smet Rosedowns, www.rosedowns.co.uk, Accessed at

18.04.2012

18. http://vincentcorp.com, Accessed at 20.04.2012

19. Ferchau, E., “Equipment of Decentralized Cold Pressing of Oil Seeds”,

2000, Webpage of Folkecenter For Renewable Energy, www.folkecenter.dk

20. Webpage of Tinytech Plants, http://www.tinytechindia.com/oil.htm,

Accessed at 20.04.2012

21. Gichuki, F.N. (2000a) „Makueni District profile: Farm development, 1989-98‟,

Drylands Research Working Paper No. 1. Drylands Research, Crewkerne,

United Kingdom.

22 Webpage of

vanillajatrophafoundation,http://www.jatrophavanillafoundation.com//album.htm,

Accessed at 16.05.2012

53

APPENDIX A

All dimensions in millimeters

54

55

56

57

58

59

0

60

61

62

63

64

65

66

67

68

69

70

71

APPENDIX B

MACHINE PHOTOS

SIDE VIEW

72

PLAN VIEW

73

SIDE VIEWS

74

TANK