juice extraction systems

8/15/2019 Juice Extraction Systems

1/19

1

FE11JUICE EXTRACTION SYSTEMS: Mills and Diffusers - The Brazilian Experience

By

J.L. OLIVERIO, A.C.R. D AVILA, A.N. FABER, P.A. SOARES

DEDINI S/A Indústrias de Base

Rod. Rio Claro-Piracicaba, km 26,3, CEP 13412-900, Piracicaba - São Paulo – Brazil

Email: [email protected]

KEYWORDS: juice extraction; diffuser; modular diffuser; chainless diffuser, crusher;milling unit/tandem

AbstractFor cane juice extraction, two systems are used worldwide: milling

tandem or diffuser. In Brazil, the preference has been for the mills

solution. Data from the 2004/2005 milling season shows that, out of a

total of 347 mills in operation, 341 use mills and 6 the diffuser,

corresponding to 1.7% of the extraction systems. Since 2003, the

sucro-energy industry in Brazil has grown considerably, from 320

million tonnes of processed cane to 620 million in 2010/11, and new

Greenfield projects were implemented. In 2011, 455 mills had already

decided on the extraction system, with 32 mills using diffusers built or

contracted, representing 7%. Therefore, there has been a significantincrease of diffusers and a growth even more expressive if we

consider only the Greenfield projects defined since 2004: 108

decisions have been made, and 25 diffusers have been built or

contracted, accounting for 23.1% of the choices. Given the typical

characteristics of the sugarcane industry in Brazil, with plants

designed for expansion and high milling capacities, one of the factors

that contributed to the increased choice for the diffuser solution was a

new product, the chainless modular diffuser, which is expandible and

more easily applicable to process large amounts of sugarcane. This

paper presents a technical comparative review of both extraction

systems, milling and diffusion, their basic characteristics, operationaldata, recommended use for one or other system, and ratio of

investments and costs between milling tandem and diffusers.. Taking

into account that the sector will continue to grow in Brazil – forecasted

to reach up to 1.2 billion tonnes of cane in the 2020 season and nearly

100 new Greenfield projects to be implemented – this work seems to

be opportune and may serve as a guide for future decision-making on

extraction systems, mills or diffuser, either for the new mills or

expansion of the existing ones.


2/19

2

SISTEMAS DE EXTRAÇÃO DE CALDO: Moendas e Difusores – A ExperiênciaBrasileira

Por

J.L. OLIVERIO, A.C.R. D AVILA, A. N. FABER, P.A. SOARES

DEDINI S/A Indústrias de Base Rod. Rio Claro-Piracicaba, km 26,3, CEP 13412-900, Piracicaba - São Paulo – Brazil

Email: [email protected]

PALAVRA-CHAVE: extração do caldo; difusor; difusor modular; difusor sem corrente,moenda; unidade de moagem/tandem

ResumoPara a extração do caldo de cana, dois sistemas são hoje utilizados no

mundo todo: moendas e difusores. No Brasil, a preferência tem sido

pela solução com moendas. Um levantamento feito sobre a safra

2004/2005 mostrou que de um total de 347 usinas em operação, 341

optaram por moendas, e 6 por difusores, o que corresponde a 1.7%

dos sistemas de extração. A partir de 2003, a indústria sucroalcooleira

brasileira cresceu significativamente, de 320 milhões de toneladas de

cana processada para 620 milhões em 2010/11, e novos projetos

“greenfield” foram implantados. Em 2011, 455 usinas há haviam

decidido sobre o sistema de extração empregado, com 32 usinas já

com difusores implantados ou contratados, representando 7%.

Portanto, houve um aumento significativo de difusores e um

crescimento ainda mais expressivo se considerarmos apenas os projetos “greenfield” definidos desde 2004: 108 decisões já foram

tomadas, e 25 difusores foram implantados ou contratados,

respondendo por 23.1% das escolhas. Dadas as características da

indústria canavieira no Brasil, com plantas previstas para expansão e

elevadas capacidades de moagem, um dos fatores que contribuíram

para o aumento das opções por difusores foi o difusor modular sem

corrente, que é expansível e mais facilmente aplicável para processar

grandes quantidades de cana-de-açúcar. Este trabalho apresenta uma

análise técnica comparativa de ambos os sistemas de extração,

moagem e difusão, suas características básicas, dados operacionais,

uso recomendado para este ou aquele sistema, e a relação entreinvestimentos e custos de um tandem de moendas e difusor.

Considerando-se que o setor deverá continuar a crescer no Brasil – as

projeções indicam 1.2 bilhões de toneladas de cana na safra de 2020, e

cerca de 100 novos projetos “greenfield” a serem implantados – este

trabalho parece ser oportuno e poderá servir como um guia para

futuras decisões a serem tomadas quanto ao sistema de extração,

moendas ou difusor, tanto para novas usinas como para a expansão

das existentes.


3/19

3

Introduction

Extraction of sugarcane juice began in the first half of the 16 th century in the Brazilian

territory with the purpose of supplying sugar to the European countries and the incipient

domestic market. The expedition of Martin Afonso de Souza, in 1532, started cane cultivation

and implemented the first sugar mill in the state of São Paulo, the Engenho Eramos (a smallmill producing sugar and rum), in São Vicente. After that pioneer unit and to reduce transport

costs, sugar was produced in states nearer to Europe, in the current states of Pernambuco,

Bahia and Rio Janeiro. In this initial stage, the mills installed in São Paulo and Rio de Janeiro

states already showed the ability to make the sugar industry a profitable activity.

The first mills had a similar design, based on family farming activities. For centuries

sugar mills have evolved: initially, juice extraction was achieved by low efficiency and low

capacity mills driven by animal traction and/or water wheels; later by steam machines; and

finally they were mostly driven by steam turbines. (UNICA, 2012). This structure remained

until 1975, when the Brazilian government launched the ProAlcohol Program.

The National Alcohol Program – ProAlcohol was implemented to reduce the country’s

vulnerability to the oil crises. The goal of this program was to use ethanol to replace gasoline

from petroleum as a fuel for Otto-cycle engines in light vehicles. This program was supported

by the World Bank and led to the expansion of sugarcane crops and juice extraction units,

which began to meet the juice demand for sugar production in addition to the volumes

required to produce anhydrous ethanol to be blended with gasoline, and hydrous ethanol to be

used exclusively in 100% ethanol-powered vehicles (E100). Soon after the second world oil

crisis in 1984, national production of light vehicles reached its peak with 95.4% of the

engines running on hydrous ethanol. With the softening of the oil crisis and domestic

problems in the Brazilian economy, the production of ethanol-powered vehicles began to

decline in 1989, and production fell to the minimum level of 1.02% of new vehicles running

on hydrous ethanol in 2001. (UNICADATA, 2012)In the early ProAlcohol period, focus was on capacity increase, without major

technological advancements but, in the second half of the 1980s, capacity increases came

from the combination of increased capacity of juice extraction and processing equipment with

technological improvements, which ensured higher extraction yields and better extraction of

the sugars contained in sugarcane, associated with major technological advancements in cane

cultivation with the introduction of new and more resistant cane varieties.

With the advent of the flexible-fuel technology (Flex) for light vehicles in 2003, which

can run on both hydrous ethanol (E100) or gasoline “C” (E18 to E25), a new phase of high

demand for sugarcane took place in order to produce fuel ethanol. Ethanol was used as a fuel

and additive to gasoline, replacing more polluting substances, such as MBTE and lead. This

phase is marked by the ethanol production in a free market: the final consumer dictatesdemand and decision on consumption, based on the economic advantage offered by each fuel.

The free market requires that high-performance and high-capacity extraction systems are

implemented, so that economies of scale and the optimum use of the feedstock can be

attained. The consolidation of the Flex technology occurred simultaneously with the Brazilian

regulation of electricity exports to the domestic grid and the global acceptance of

sustainability principles for energy generation and utilisation.

From 2006, the sustainability concepts, in their broad aspect, especially with the

introduction of mechanical harvesting of green cane, became a key impact factor on the mills

and juice extraction systems: the mills should process a new raw material, chopped cane with

high contents of vegetable and mineral impurities. This is the current situation, in which some

paradigms regarding burned and clean sugarcane have already been broken, and a newlearning process has began, of how to handle the new raw material, coupled with


4/19


5/19

5

Fig. 2 – Objective of the extraction system

Figure 3 shows how the mill units perform extraction in successive and gradual

compression stages. The combined arrangement of a series of mills forms what we call

“milling tandem” or “milling train”, where imbibition water is added in counter-current to the

bagasse as shown in Figure 4. The combination of imbibition with mechanical crushing

allows attaining extraction rates similar to those of diffusers. (Wever and Oliverio, 2006)

Fig. 3 – Juice extraction by mill

Fig. 4 – Arrangement of 6 mills forming a milling tandem

Figure 5 shows the operating principle of a diffuser, in which the liquid percolates

through a bed consisting of the cane fibrous material, the prepared sugarcane, employing

gravity as driving force. Since the goal is to extract sugars, the extraction liquid is the

imbibition water.. In order that the equipment operates continuously, it is necessary that the

cane bed moves continuously, and in counter-current to the imbibition water, enriched with

the sugar extracted (which is indicated by brix as the amount of dissolved solids in the

solution). Sugars are the predominant dissolved solids in the water solution.


6/19

6

Fig. 5 – Juice extraction by lixiviation and diffusion (Oliverio, 2011)

Figure 6 illustrates different types of diffusers. In Brazil, the most popular diffuser

type until 2006 was the linear one with fixed screen deck. The chains in this equipment are

necessary to drag the bed forward (Oliverio, 2011).

Fig. 6 – Commercial types of diffusers

Another way to move the bed has been developed recently and is based on the

principle that when the frictional force between a support plate and the bed is not exceeded, it

can be displaced but, if the movement of the support plate exceeds the frictional force, the

support plate will move without carrying the bed. The cane bed is dragged in a continuousforth-and-back motion of the parallel support plates or tracks that comprise the screen deck.

Forward and reverse hydraulic cylinders drive each track. Figure 7 illustrates the operating

principle of this equipment, and shows the interior of the chainless diffuser. The screen deck

is made of parallel tracks; they can be expanded by the addition of an even number of tracks.


7/19


8/19

8

Fig. 8 – Complete juice extraction system by diffusion – cane diffuser

We understand that, in the near future, the bagasse diffuser solution may be

reintroduced to the Brazilian market, as these systems can deliver up to 70% of absolute juiceof good quality for sugar production and the mixed juice that can be sent for ethanol

production by means of an optimised juice treatment system designed for each final product.

This may result in a new technical and economic optimisation of the future mills.

Cane juice mill: historical evolution

Today we can distinguish two types of cane-processing plants in Brazil: those

producing sugar, ethanol and bioelectricity and those designed for energy production, ethanol

and electricity, referred to in Brazil as distillery or ethanol mill. According to the block

diagram below (Figures 9 and 10), we can see that, in both cases, there is the juice extractionstage present. However, the optimised design of both types of plants requires different

considerations for all processing steps, because the optimum characteristics of the extracted

juice that is aimed at sugar production are not necessarily the same of those required for

ethanol production. Optimisation of the extracted juice will influence the definition and

characteristics of the mills unitary operations, requiring a customised project for each specific

case (Olivério, 2011).


9/19

9

Fig. 9 – Typical mill diagram for sugar / ethanol / electricity production

Fig. 10 - Typical mill diagram for ethanol / electricity production

In Brazil, until 1968, all juice extraction systems consisted of mills, and the first

bagasse diffuser was introduced to the Brazilian market by Dedini Company in 1967, with a

capacity for 100 tonnes of cane/hour (TCH) in São Francisco Mill, Charqueada, SP. In 1983,

the same company installed a second and a third diffuser, both for cane, in Galo Bravo Mill,

Ribeirão Preto, SP, with a capacity for 150 TCH, and in Coamo Distillery, PR, currentlyinstalled at DECOIL Mill.


10/19

10

In Brazil, implementation of the new mills follows, almost in its totality, a phased

construction schedule in which investments in the industrial sector are compatible with the

agricultural sector i.e., according to the amount of cane that can be supplied, requiring that the

installed capacity be implemented in phases and expansible in the medium term. In this

context, juice extraction by mills allows more flexibility, because it just requires additional

mill units and/or the replacement of the first and last mills to achieve a significant capacity

increase. In our view, this was the main reason for the market’s almost rejection of extraction performed by diffusers until 2005.

In the 2004/2005 crop, a total of 347 mills were in operation, 340 of them using mills,

and the other 7 using diffusers, besides two other diffusers being built. In 2005/06, a total of

347 mills were in operation, and 46 new mills were designed, built or started operations in the

period.

Data collected shows that from 1967 to the end of 2005, 10 diffusers were acquired, of

which 1 is inactive, 7 in operation, and 2 being built, totalling 9 diffusers. In 2007, 13

additional units were acquired. Therefore, it was during the 2005/06 crop that the decision on

the type of extraction was made, mill or diffuser. In this period, extraction by diffusion had a

unit increase of 144%, and of 305% if expressed in nominal processing capacity, making the

2005/06 crop a milestone marking the end of the almost total rejection of diffusers in Brazil.

The same data shows that 371 mills using mill tandems were operating in the said milling

season, representing 94% of the operating extraction systems, i.e., an absolute supremacy of

extraction performed by mill tandems. Figure 11 below summarises the data collected

(Olivério, 2011).

Fig. 11 – Number of diffusers in the 2004/05 milling season

In the period of 2005 to 2012, decisions on a total of 108 extraction systems were

made, of which 71 mills acquired new juice extraction systems, among them 25 diffusers,

representing 35.2% of the choices made. In the 2010/11 crop, a total of 455 mills were

operating in the Brazilian market. Figure 12 shows the percentage of diffusion extraction

systems over these years.


11/19


12/19

12

Note: Typically, sugar extraction is reached 90% in leaching and 10% in diffusion

Fig. 13 – Typical diffuser extraction parameters

Fig. 14 – Typical mill extraction parameters

Table 1 below summarises the main process differences between diffusion and milling

extractions, which we present without the intention of exhausting the subject, but rather

presenting a guide for the first and specific selection of a real case.

Table 1 - Technical comparison between mills and diffusers

P r o c e s s P a r a m e t e r Characteristic Mill

CANE DIFFUSER

Chain and Modular Diffuser

Cane preparation

(Voigt, 2009)

Attain good

extraction rates with

85% preparation.

Accepts greater

amounts of fines or

small particles.

Requires higher preparation, over 90%. Long

fibres are desirable, but fines hinder adequate

bed percolation.


13/19

13

Impact of

mineral

impurities

Causes mill wear but

do not affect

momentary extraction

rates

Causes low impact on the apparatus

maintenance. The effect of impurities on

extraction cannot be generally quantified both

for diffusers and mills.

Impact of soil

type / bed

colmatation

(clogging)

Low impact on

extraction / Higher

wear of rollers in clay

soils

Clay soils / sludge / gels tend to prevent

adequate percolation, causing choking and

extraction losses (Rama et al., 2006)

Impact of

vegetable

impurities (Dias

Paes, 2011)

Loss of 2.3

percentage points of

capacity for every

1.0% of vegetable

impurity

Loss of 3.1 percentage points of capacity for

every 1.0% of vegetal impurities. Short fibre

and fines tend to prevent adequate percolation

Quality of

extracted juice

(Rein, 1995)

Higher levels of

suspended solids.

Requires filtration.

Lower concentrations of suspended solids.

Extracts higher amounts of non-sugars

substances (ex: phenols, colorants,

polysaccharides, etc.) (Manechini, 2011)

Juice dilution

Allows up to 80%separation of cane

absolute juice.

Remaining mixed

juice is more diluted.

Does not allow separation of absolute juice.

Mixed juice usually with higher brix if in

tandem mill, absolute juice is extracted.

Usual imbibition

rate

Typical: 200% -

250% of fibre /

limited by the mills

operation. May use

higher imbibition

with low capacity.

Allows adjustments to achieve improved

process balance: juice brix / bagasse moisture /

extraction / energy consumption in juice

evaporation. Typical: 200% - 300% of fibre.

(Voigt, 2010)

Required juice

evaporation

Typically lower

imbibition requires

lower thermal energy,

as steam consumption

and/or waste heat

recovery from

process stream.

The learning curve of operational experience

will determine the optimum point, particularly

in mills producing ethanol and bioelectricity,

but preliminary indicators show that imbibition

may be optimised from the experience learned

from the use of the not burned and

mechanically harvested cane. (Voigt, 2010)

Sugars

extraction rates

in juice

Hardly exceeds 98%,

and tends to decline

during the milling

season.

98.5% may be achieved with two dewatering

stages, and is barely impacted by wear during

the milling season. (Delfini, 2012)


14/19

14

Thermal energy

in the system as

steam demand

Operates at 60

Celsius. Requires

lower thermal energy

in extraction

Typically operates between 80 to 90 Celsius.

Requires more thermal energy in extraction

and, usually, in evaporation for higher

imbibition water rate.

Required electric

power for drive

6000 kW installed for

a capacity of 13 000

TCD, except for

preparation

3500 kW installed for a capacity of 13 000

TCD, except for preparation. The electric

power consumption in preparation is similar to

the mills.

Bioelectricity

available for

exports

Higher electric power

demand for drive /

lower thermal energy

demand.

Lower electric power demand for drive / higher

thermal energy demand. Depending on the

cogeneration design, similar exports can be

obtained, especially in systems with low

percentage of condensation in the last

cogeneration turbine stage

Biological

contamination

(Mackrory,

1984)

Operates at lower

temperature,

enhancing biological

activity.

Operates between 80 and 90 Celsius, reducing

microbial activity and losses of reducing

sugars.

Bagasse quality

Lower concentration

of mineral impurities;higher homogeneity

of bagasse particle

sizes, higher moisture

stability.

Higher contents of mineral impurities; greater

amount of large “pieces”; moisture controlmore difficult with only one mill or one

dewatering stage. Higher difficulties in burning

and wear of conventional boilers.

Electricitygeneration /

bagasse

moisture

Bagasse moisture is

more stable and,

independent of the

level of impurities in bagasse feed; it

ensures more burning

stability in

conventional boilers

and in turbo-

generator operation.

It may require two complete dewatering millsto achieve the same stability obtained with mill

tandems.


15/19


16/19


17/19

17

Mixed juice

treatment

Allows to obtain

mixed juice for ethanol

and absolute juice for

sugar

Produces only mixed juice. In plants not

producing sugar, it allows simplified juice

treatment and less investment. Still a

controversial issue. (Manechini, 2011)

Weld

electrodes

consumption

Considered as 100%

(typically 8 - 10 g/t

cane)

20 to 35% of mill (both in diffuser and mill, it

depends on maintenance quality)

Lubricant oil

consumption

Considered as 100%

(typically 3g/t cane)

15 to 30% of mill (both in diffuser and mill, it

depends on maintenance quality)

Cost of

investment inextraction

Considered as 100%

Similar or lower than complete mill tandems

installations.

Operational

costsConsidered as 100%

For the same processing capacity, maintaining

extraction and bagasse moisture levels: 60 to

80% of the mills cost

Maintenance

costs Considered as 100%

For the same processing capacity, maintaining

extraction and bagasse moisture levels: 50 to75% of the mills cost

Assembly

costs

Traditional level, as

commonly used in

mills

Requires more care in

chains alignment

Requires more care in

tracks alignment /

pistons and clearances

control(*)

If regularly submitted to appropriate preventive maintenance, the period for total replacement of chains can be

extended to 15 – 20 years.

Comparative expandability: milling and diffusers

The mills capacity can be expanded more easily, allowing increase of the number

and/or size of the mills, while chain diffusers do not allow gradual expansion – it requires a

new complete line. Modular diffusers allow capacity increases by expanding the bed width.

Figure 16 summarises the main expansion possibilities and respective extraction rates for a

milling tandem system.


18/19


19/19

19

Delfini P. (2012) Cana Crua x Extração. 13º Seminário Brasileiro Agroindustrial – A Usinaem números. STAB – 24 e 25/10/2012 – Acessed on March 2013 www.stab.org.br.

Dias Paes L.A. (2011). Levantamento dos níveis de impurezas nas ultimas safras. Centro deTecnologia Canavieira – CTC, 12/5/2011.

Mackrory L. M. et al. (1984). A Comparison of Microbiological Activity Associated withMilling and Cane Diffusion. Proc. South Afr. Sugar Cane Technol. – June 1984.

Manechini C. (2011). Impurezas e qualidade da cana colhida mecanicamente. STABCANAOESTE – 12/4/2011 – Accessed on march 2013

http://stab.org.br/impurezas/Celio%20Menechini.pdf

MME/EPE (2012). Plano Decenal de Expansão de Energia 2021 / Ministério de Minas eEnergia. Empresa de Pesquisa Energética: MME/EPE, 2012: p. 282.

Olivério J.L. (2011), Sistema de Extração de Caldo: Difusor ou Moenda; SIMTEC 2011, 04

de Junho de 2011. Accessed on September 27/2011 http://www.simtec.com.br/palestras.ma S.et al. (2006). The effect of Clay Type Soil in the Diffuser at Umfolozi Mill. Proc. S. Afr.Sugar Cane Technol. , 80: 320-326

Rein P.W. (1995) A Comparison of Cane Diffusion and Milling. Proc. S. Afr. Sugar CaneTechnol., - June 1995:196-200

Schorn P.M. (2005). A Structured Approach to Sugar Factory Design. Proc. South Afr. SugarCane Technol. , 79: 273-286.

Schroder K. E. Voigt, I. and Moor, B.St.C. (2007). The Conversion of a BMA diffuser to aBosch Project Chainless Diffuser – The First Season´s experience. Proc. Int. Soc. Sugar Cane

Technol., 26: (CD-ROM). .

UNICA (2012), Setor Sucroalcooleiro, Histórico: Available: http://www.unica.com.br ; accessed on September 27, 2012.

UNICADATA (2012). Produção, Histórico de Produção e Moagem: Available:http://www.unica.com.br ; accessed on September 27, 2012.

Voigt I. (2009). The Implementation of South African Sugar Technology: The World´sLargest Sugarcane Diffusers. ProcIntSocSug Cane Tecnol Ass 82: 269-277.

Voigt I. (2010). Experience of Diffuser Performance at Very Low Imbibition Water rates. ProcIntSocSug Cane Tecnol Ass 83: 280-288

Wever H. and Olivério J.L. (2006). Métodos de Extração de Caldo; Banco Nacional deDesenvolvimento Econômico – BNDES; DEDINI, 16 -10-2006.
http://stab.org.br/impurezas/Celio%20Menechini.pdfhttp://stab.org.br/impurezas/Celio%20Menechini.pdfhttp://www.simtec.com.br/palestrashttp://www.simtec.com.br/palestrashttp://www.simtec.com.br/palestrashttp://www.unica.com.br/http://www.unica.com.br/http://www.unica.com.br/http://www.unica.com.br/http://www.unica.com.br/http://www.unica.com.br/http://www.unica.com.br/http://www.simtec.com.br/palestrashttp://stab.org.br/impurezas/Celio%20Menechini.pdf

juice extraction systems

Documents