Soybean Report

8/2/2019 Soybean Report

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Introduction

RAMA PHOSPHATE LTD,MUMBAI:

Rama Phosphates Limited is one of the leading fertilizer manufacturing companiesin India. It is a public limited company with stocks listed on stock exchanges.

Rama Phosphates is in existence for last 25 years and one of its units at Pune is in

existence for last 40 years and pioneer in India. RPL is listed public limitedcompany in Bombay Stock Exchange.

INDOREFERTILIZER DIVISION :

The Company has state-of-the-art manufacturing facility for production of Single

Super Phosphate in both Granule and Powder form and Sulphuric Acid which isused mainly for captive consumption and also to cater requirement of localcustomers in its place of operations at Indore, Pune and Udaipur.

The Companys Indore plant has installed capacity of 1,65,000 MT of SSP and

1,02,000 MT of Sulphuric Acid. The Company has state-of-the-art solvent

extraction plant which includes seed crushing, packing and distribution facilities as

also in-house captive power generation which is generated by exo-thermic heatproduced in the process of manufacturing Sulphuric Acid.

The Turbo generator power generation is one of the most efficient powerproducing system with all imported equipments from KKK, Japan and Germany.

The entire power requirement of the unit is fully met with generated power and

thus there is no need for the company to purchase power from outside agencies. In

addition, company has stand-by Diesel Generator system which can cater to the

entire requirement of the plant at its peak level.

The Company is in the field of manufacture and sale of phosphatic fertilizers and

Soya oil. The phosphatic fertilizer has good demand amongst small and medium

sized farmers, as it is one of the cheapest fertilizers. This fertilizer is also useful forgrowing various cash-crops grown in almost in all parts of the country. The recent

trend of mixing phosphatic fertilizers with nitrogenous fertilizers is also becoming

popular, which results in higher consumption of SSP.

On the other hand, sale of phosphatic fertilizers depends on purchasing power of

farmers and vagaries of monsoon. The viability of the industry primarily dependent

on policies framed by the Government.


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SULPHURIC ACID PRODUCTION

PLANT CAPACITY:-

The Companys Sulphuric Acid plant is set up with DCDA technology and one of

the pioneers of Sulphuric Acid plant in M.P. with total capacity of 265 TPD

including Battery Grade Acid

Procedure for the Production of Sulphuric Acid:

Sulphuric acid is produced by double contact absorption process. Sulphur is the

main raw material. Sulphur is melted, filtered and then oxidized to SO2.

SO2 is further oxidized to SO3 by passing through a catalytic converter having

vanadium pentoxide v2o5 as catalyst. The converted SO3 is absorbed in

concentrated sulphuric acid. Then the absorbed sulphuric acid is converted to

sulphuric acid.


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H2SO4

Melting pit Burner Filter

Convertor ISuperheater

Convertor II

bed

Heat exchanger (ST) Convertor IIIbed

Heat exchanger

economiserI.P.A.T.Heat exchanger (ST)

Heat exchanger (ST) Convertor IV

bed

economiser

Chimney F.A.T.

Drying

tower


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Description of the main steps:

The flow diagram of the DCDA process contains the following equipments

1. Melting pit

2. Burner

3. Converter

4. Absorber

5. Scrubber

The raw material used for the large scale manufacture of sulphuric acid is sulphur.

Sulphur comes from ores of sulphur situated in other states.

1. Melting Pit

The sulphur obtained may contain impurities like Selenium, Tellurium, ash, mud

etc. so

sulphur is to be purified to about100%. The purification is done by melting. When

sulphur ismelted the impurities present in it remain in the molten sulphur itself.

Sulphur has a meltingpoint of 1300C.

Sulphur is stored in a sulphur go down. With the help of workers it is transferred to

a silo. For melting the sulphur steam coils are used. The high pressure steam melts

the sulphur at a temperature of 140-1500C and 6.27kg/cm2. The velocity of the

molten sulphur is maintained in a specified value so that the easy flow of sulphur is

achieved. The specific gravity Of molten sulphur is 1.8. The impurities in the

sulphuric acid raises temperature of sulphur from 130-1500C. In order to neutralize

the acid impurities, which are produced by the contact of molten sulphur with


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atmospheric oxygen, sulphurous acid, hydrated lime is added. The undissolved

impurities are separated by settling in the melting pit itself.

The overflow from the melting pit is collected in a dirty pit. From the dirty pit

sulphur is

pumped to leaf filter . The leaf filter is in horizontal inclined position. The filterate

from the leaf filter are collected in a clean pit. The temperature of molten sulphur

is maintained at a value of 1300C and at a pressure of 2.5kg/cm2. If the

temperature is below 1300C the pumping of molten sulphur becomes difficult and

above that temperature causes firing of molten sulphur

.2. Burner

The molten sulphur reacted with compressed air gives sulphur di oxide gas. A

furnace is used for burning molten sulphur and compressed air. The furnace is a

horizontal,cylindrical vessel. The furnace is made up of carbon steel, acid proof

bricks and fire resistant bricks.

S+O2->SO2

The above reaction takes place.

Molten Sulphur is pumped from a storage tank through heated lines and sprayed in

to the furnace using burners. Dry air from air drying tower is introduced into the

furnace. The temperature of furnace is kept at about 950-10200C, otherwise

leakage of sulphur takes place.

The conversion is exactly 10.5% by mole SO2

Waste Heat Boiler-1

Before the gases are fed to the first stage of the converter, they are adjusted to

minimum temperature at which catalyst rapidly increases the speed of reaction,

usually 425 to 4400C.

For that purpose a waste heat boiler has shell side and tube side. SO2 gas at a

temperature of 10000C is passed through the tube side and water is passed through


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shell side. Thus by the principle of heat transfer the temperature of SO2 gas is

reduced to about 4350C and water gets converted to steam.

But there is a chance for reduction the temperature below this value. So the outlet

of the waste heat boiler is given to a mixing chamber where mixing of SO2 fromboiler and furnace takes place. As a result the temperature of SO2 can be kept at

4350C.

TABLE Showing per pass conversion of SO3 in convertor

Location Temperature C Equivalent conversion

Gas entering 1st pass 430Gas leaving 1st pass 600

Rise in temperature 170 60%

Gas entering 2nd pass 430

Gas leaving 2nd pass 520

Rise in temperature 90 28%

Gas entering 3rd pass 430 6%

Gas leaving 3rd pass 450Rise in temperature 20

Gas entering 4th pass 430

Gas leaving 4th pass 445 5.75%

Rise in temperature 15

TOTAL 99.75%

3. Convertor

The chemical conversion of sulphur dioxide to sulphur trioxide is designed to

maximize the conversion by taking into consideration that


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1. Equilibrium is an inverse function of temperature and a direct function of the

oxygen to the sulphur dioxide ratio

2. Rate of reaction is a direct function of temperature.

3. Gas composition and amount of catalyst affect the rate of conversion and the

kinetics of the reaction.

4. Removal of sulphur dioxide formed allows more sulphur dioxide to be

converted.

The commercialization of these basic conditions makes possible high overall

conversion by using a multipass convertor. A four pass convertor is used for

conversion in the sulphuric acid plant.

It has 4 beds of rings (RASCHIG) and start type materials coated with vanadium

pentoxie (V2O5)catalyst for better conversion. The conversion takes place in two

stages.

Stage-1

Sulphur dioxide gas from the mixing chambers is given to the 1st layer of the 4

pass convertor. The conversion reaction is

2SO2+O2->2SO3

This reaction is highly exothermic. Thus the temperature increases to 6000C. If this

conversion stream is directly given to the 2nd

layer of the convertor then the

catalytic bed may be spoiled. In order to avoid that condition the outlet from the

first layer is given to a super heater.

Super Heater

The gaseous stream from the first stage of the convertor is given to the tube side of

the superheater and stream is passed through the shell side. Then the temperature is

reduced to 4250C. The outlet of the superheater is given to the second bed of the

convertor where 28% of conversion of SO2 to SO3 takes place. The conversion

raises the temperature of gas to 5200C. For cooling this gas before it is given to the

third layer a hot heat exchanger is used.


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Hot Heat Exchanger

The outlet from the 2nd layer of the catalytic convertor is given to the tube side of

the hot heat exchanger. Hot gas is passed through the shell side. Thus the

temperature of SO3 gas reduces to 430

0

C. The gas stream from the hot heatexchanger is given to the third layer of the convertor. In the third layer 6%

conversion of SO2 to SO3 takes place and the temperature rises to 4500C. This

completes the first stage of conversion of SO2 to SO3. for absorption of

converted SO3 its temperature should be reduced. Thus a heat exchanger and an

economizer are used.

Cold Heat Exchanger

The outlet from the third layer of the catalytic convertor is given to the tube side of

the cold heat exchanger and cold gas is passed through the shell side. Then the

temperature of the SO3 gas decreases to 3300C from 450

0C.

Economiser-1

For the further reduction of the temperature to 1800C an economizer is used. In the

economizer gas is flowing through the tube side and water is flowing through the

shell side.Thus the temperature is reduced to 1800C.

4. Inter-pass absorption tower

The SO3 gas from economizer-1 is absorbed in an interpass absorption tower. It is

cylindrical in shape and the gas is absorbed in 98.5% sulphuric acid. The acid is

sprayed from the top of the IPAT and gas is given through bottom. The temp of

IPAT is 700c.

In order to reduce the temperature of sulphuric acid before it is sprayed to IPAT

and FAT a plate cooler is used. Water is passed through the plates and acid is

passed in between the plates. Thus the transfer of heat takes place and as a result ofthis temperature of acid is reduced and water become steam.

Stage-2

The unabsorbed SO3 gas from the interpass absorption tower is given to the 4th

bed of the catalytic convertor which is at a temperature of 4300C and 5.75%


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conversion of SO2 to SO3 takes place in the second stage and temperature is

increased due to exothermic reaction.

Economiser-2

It is similar to that of economizer-1 and having so3 gas in the tube side and water

in the shellside. Reduction of temperature takes place and the outlet from

economizer-2 has a temp of 1800C. The outlet gas is absorbed in final absorption

tower.

4. b. Final absorption tower

Second stage absorption of SO3 gas is done in the final absorption tower. It is

similar to IPAT sulphuric acid at 98.5% concentration and reduced temperature is

sprayed from the top of the FAT and SO3 gas from the economizer-2 is given to thebottom of FAT absorption of so3 results.

The outlet of both the IPAT and FAT has the formula H2S2O7 (oleum)

SO3+H2S2O7->H2S2O7

The oleum is collected in acid pumping tank.

5. Pollution Control (Scrubber Unit)

Gases from the final absorption tower contains SO2.SO3 atmospheric pollutant.

Gases from the final absorption tower are taken to a packed scrubber. During

normal operation the gasses passes through dry scrubber. During start up or

disturbed conditions caustic solution from the solution tank is fed to the foot of the

scrubber by gravity. SO2 from the gases is absorbed in the circulating stream of

caustic solution. Scrubbed gases are vented to atmosphere through a 26 meter tall

chimney. The specified limit is 300ppm SO2, 100mg/Nm3 of SO3, as prescribed

by the pollution control standards.


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SINGLE SUPER PHOSPHATE

INTRODUCTION:

To maintain a high level of animal and crop production, land usually requires the

application of phosphate to supplement that occurring naturally. In New Zealand

and Australia this is supplied mainly as superphosphate fertiliser.

Superphosphate is manufactured by reacting insoluble phosphate rock with sulfuric

acid to form a mixture of soluble mono-calcium phosphate and calcium sulphate

(approximately 9% phosphorous) which is able to be used by plants. In many other

parts of the world it is more cost effective to use triple superphosphate fertiliser. Inthis process phosphate rock is reacted with phosphoric acid to produce a product

with 21% phosphorous. Triple superphosphate plants are more capitalintensive but

with a more concentrated product these plants can service a greater area. However,

this product does not contain sulfur whereas superphosphate contains 13% sulphur.

In many parts of the world areas of sulfur deficiency are showing up, and

there is a trend back to single superphosphate. Other .high analysis. Fertilisers are

also available, such as di-ammonium phosphate (DAP) which contains 20%

phosphorous and 18% nitrogen.

THE MANUFACTURE OF SUPERPHOSPHATE:

The basic reaction in the manufacture of superphosphate is the reaction of

insoluble phosphate rock with sulfuric acid to form the soluble calcium di-

hydrogen phosphate, Ca(H2PO4)2. This is described by the following equation:

PO43-

+ H2SO4 H2PO4-+ SO4

2-

The phosphate rock, imported from Nauru, Jordan, Morocco, Israel and the USA,

is mainly fluorapatite, Ca5(PO4)3F and is equivalent to 70 - 85% Ca3(PO4)2 by

weight.

The actual composition of the phosphate rock varies with the source. The sulfuric

acid is produced on the site as described in the previous section. The reactions

occurring during the production of superphosphate are complex and are

usually summarised as follows:


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1. Ca5(PO4)3F + 5H2SO4 5CaSO4 + 3H3PO4 + HF

2. Ca5(PO4)3F + 7H3PO4 + 5H2O 5Ca(H2 PO4)H2O + HF

These reactions can be combined to give the overall equation:

2Ca5(PO4)3F + 7H2SO4 + 3H2O 7CaSO4 + 3Ca(H2PO4)2 +2HF

There are other reactions occurring at the same time. For example, virtually all the

HF reacts with other silica minerals associated with the fluorapatite (silicates,

quartz) to form silicon tetrafluoride. These gaseous emissions are recovered as

hydrofluosilicic acid (H2SiF6) in the scrubbing system. Carbonates in the rock also

react with sulfuric acid.

The production of superphosphate consists of three distinct steps. See the process

flow diagram.

Step 1 - Phosphate rock blending and grinding

Phosphate rock from different sources have different phosphate, fluoride and silica

contents. These rocks are mixed in the blending plant to produce a product with a


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total phosphate concentration of 15%. The phosphate rock mixture is passed

through a hammer mill which reduces the particle size to 0.5cm or less. The

coarsely ground rock is then passed through an air swept roller mill (Bradley Mill)

to attain a rock grist of approximately 75% less than 75 microns. The powdered

rock is stored in a large hopper. The powder handling system is fitted with a dust

collection system.

Step 2 - Superphosphate manufacture

The ground rock and sulfuric acid are reacted in a horizontal mixer. The feed rates

are approximately:

Phosphate rock - 25 tonnes/hour 98% Sulfuric acid - 14.5 tonnes/hour

Water - 6 tonnes/hour

A continuous flow of the sloppy mix drops out of the mixer into the Broadfield

Den. The den consists of a slowly moving floor (approx. 300 mm/min) to enable

setting of the cake and reciprocating sides, which prevent the superphosphate

adhering to the walls. The partially matured superphosphate cake is cut out of the

den with a rotatingcutter wheel after a retention time of approximately 30 minutes.Additives such as limestone, potassium chloride (potash) and ammonium sulphate

may be added to the superphosphate before it is worked further in the conditioner.

The conditioner consists of a set of rotating paddles which break-up and knead the

product. Water is usually added to improve the product consistency for

granulation.

Step 3 - Granulation

The granulation process is important in producing superphosphate of the required

physical properties. The granulation circuit consists of a pulveriser, granulation

drum and classifier. The pulveriser breaks up any lumps in the product before it is

fed to the granulation drum. The granulation drum rolls and agglomerates the

superphosphate to form granules. The incline of the drum and the feed ratedetermine the retention time and bed depth. The granules are passed out of the end

of the drum and through a classifier (wire screen). Oversize granules (>6 mm) are

recycled through the drum via the pulveriser while the finished product is

conveyed to the product stores. The superphosphate continues to cure in the store

for about two weeks and the product is .dressed. (Oversize is passed through a

hammer mill after screening) before dispatch. Trace elements and other nitrogen or


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potassium-containing compounds can be dryblended with superphosphate to give

complete fertilisers to meet different requirements.

UTILITIES:

A drying tower is used to to dry the air in which the molten sulfur is burned. This

is a packed tower in which air is blown counter-current against a stream of

concentrated sulfuric acid, which absorbs any moisture. The heat generated by the

exothermic reaction between molten sulfur and oxygen is recovered in a waste heat

boiler to produce steam which is then used for process heating and also to drive a

steam turbine which produces electricity. The electricity is used on site and any

excess is exported to the local power supplier. In addition a gas scrubber is used to

prevent any hydrofluosilicic acid from being released into the atmosphere.

THE ROLE OF THE LABORATORY:

The laboratory is responsible both for quality control and for research. Firstly, the

laboratory monitors the exact composition of the phosphate rock blend (which

varies significantly depending on the source of the rock). This is important as the

physical properties of the finished product (particle size, dryness, friability, etc.)

which are critical if the fertilizer is to be easily spread and interact with the soil in a

satisfactory way depend on these parameters.

ENVIRONMENTAL IMPLICATIONS:

The most significant potential environmental hazards are dust (from the grinding of

phosphate rock) and gaseous hydrofluosilicic acid (from the reaction between

hydrofluoric acid and silica or quartz) emissions. These are both carefully

monitored, and a dust catcher and gas scrubber are used.


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SOYBAEN OIL EXTRACTION

INTRODUCTION

Soybean oil processors comprise the largest share of the vegetable oil industry,producing about 75 percent of the domestic supply of vegetable oil. Vegetable oils

are used almost entirely for human consumption, although small quantities are

used for industrial purposes such as in paints, resins, and animal feeds. According

to the 1992 Census of Manufactures, the most recent year for which complete data

are available, 221 establishments make up the industries in these four SIC

codes. In 1995, these industries employed 19,500 people and had a total value of

industry shipments of Rs.42885 million.

About half of these establishments use a solvent extract process to produce

vegetable oils. The others use a mechanical extraction process. However, data

reported by the Bureau of the Census group both types of establishments together.

The establishments that use solvent extraction processes produce hexane

emissionsone of two sources of air pollution for this industry. The other source,particulate emissions, is not the subject of the NESHAP. To produce crude

vegetable oil, processors prepare the oilseeds for extraction and then extract the oil

using the solvent hexane, which EPA lists as a hazardous air pollutant. This

industry profile report is organized as follows.

Section 2 includes a detailed description of the production process for vegetable

oils, with discussions of individual oil products, oilseed inputs, and costs of

production.

Section 3 describes the characteristics, uses, and consumers of vegetable oils as

well as substitution possibilities.

Section 4 discusses the organization of the industry and provides facility-level and

company-level data. In addition, small businesses are reported separately for use in

evaluating the impact on small businesses to meet the requirements of the Small

Business Regulatory Enforcement and Fairness Act (SBREFA).

Section 5 contains market-level data on prices and quantities and discusses trends

and projections for the industry. The information in this report will be used as

background in developing the EIA methodologies.


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THE SUPPLY SIDE

In this section, the supply side of the vegetable oils industry is discussed. First, the

production process is described, including inputs used in the production process

and final outputs produced. Second, the types of products produced are described

in more detail. Third, by-products and co-products of the production process are

discussed as well as input substitution possibilities. Finally, data on costs of

production and economies of scale are provided.

PRODUCTION PROCESS, INPUTS, AND OUTPUTS

The production process for vegetable oils is described, from receiving oilseeds to

refining, in this section. Although the discussion concentrates on soybean oil,

differences in the production process for the other major oilseeds are noted. In

addition, this section describes oilseeds and hexane, two specialized inputs in theproduction of vegetable oil.

Production Process

Until the mid-1800s, vegetable oils were extracted from oil seeds through

mechanical or hydraulic means.

Processors use solvent extraction as the primary method for producing vegetable

oil. The same basic process used for extracting soybean oil is used for extracting

other types of vegetable oils. However, differences in the production processes for

cottonseed, corn, and peanut oil are also noted.

Preparation of Soybeans for Solvent Extraction:

Figure illustrates the steps used to prepare soybeans for solvent extraction. These

steps include receiving and storing, cleaning, drying, tempering, cracking,

dehulling, conditioning, flaking, and expanding. Each of these steps is described in

more detail below.

Receiving and storing raw soybeans. Soybeans arrive at a facility by truck or railand are sampled for moisture content, foreign matter, and damaged seeds. Then the

beans are weighed and conveyed to concrete silos or metal tanks for storage until

processing.


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Figure showing Preparation of Soybean for Solvent Exraction

Cleaning or scalping.: At the time of processing, the beans are removed from

storage and cleaned. Another term for cleaning is scalping. Foreign materials are

removed by screening, and loose hulls are removed by aspiration.

Drying: When cleaning is complete, the beans are dried to reduce their moisture to

10 or 11 percent by weight. Soybeans shipped in international trade or from

storage elevators are typically 13 percent moisture. They are dried to this level to

prevent heating in storage and shipment.

Tempering: After drying, the beans are tempered for 2 to 3 days to allow themoisture to equilibrate and the hulls to loosen. Soybeans are generally cleaned

again after drying using magnets, screens, and aspirators.

Cracking: During the process of cracking, beans are passed through a series of

corrugated rolls that are generally about 10 inches in diameter and 42 inches long.

The purpose of cracking is to break the soybeans into pieces suitable to dehulling

and flaking. Usually each bean is broken into four to six pieces. This is a very

important step. Cracking should produce a minimum of fines, which can cause

trouble with the extraction process, and no mashed beans, which adhere to hulls.

Dehulling: The purpose of dehulling is to produce high protein meal for animal

feed or flour for human consumption. Soybeans do not have to be dehulled for oil

to be extracted. However, dehulling decreases the volume that passes through the

extractor, thus increasing throughput. Beans are dehulled by screening and


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aspiration. The removed hulls may be combined with hulls from the earlier

cleaning steps and used in animal feed.

Conditioning: Cracked soybeans, with or without hulls, are then transported to

conditioners. These are vertical stack cookers or rotary horizontal cookers where

the soybeans are heated and moistened to make them pliable enough to ensure

proper flaking.

Flaking: Conditioned soybeans are fed through large, smooth-surfaced rollers and

emerge as flakes ranging in thickness from 0.2 mm (0.008 in) to 0.5 mm (0.02 in).

Expanding: Although flaking has traditionally been the final step prior to

extraction, expanders, which were introduced in the early 1980s, are now used by

most domestic soybean and cottonseed processors. Expanders mix flaked soybeans

with water and steam and press them into pellets called collets. Collets aredenser and more porous than flakes. They allow more oil to be extracted from the

soybeans and increase the throughput of the extractor. Collets also allow the

solvent to drain more freely, decreasing the energy needed for desolventizing.

Solvent Extraction Process for Soybeans.

Figure shows a flow diagram of the conventional solvent extraction process. The

process uses the solvent hexane to dissolve the oil present in the soybeans. The

mixture of oil and hexane is called miscella. There are several different types of

extractors, including rotary or deep-bed, horizontal belt, and continuous loop

extractors. Some immerse the solids in the solvent, some percolate the solvent

through the solids, and some use a combination of both immersion and percolation.


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Soybean Cleaning

Schematic diagram of edible soy oil production process

Rotary or deep-bed extractors have compartments or cells in which solids are

washed with successively less concentrated miscella and finally with fresh solvent.

At large facilities, these cells can be as deep as 5 meters, hence the name

deepbed.

Horizontal belt extractors convey solids through a series of solvent sprays. After

percolating through the bed, the miscella is collected in a hopper below the

conveyor.


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Continuous loop extractors are shallow-bed extractors that carry the solid material

through an enclosed vertical loop. The solids go through both percolation and

immersion, and are completely turned over, allowing the solvent to contact flakes

from both sides.

Solvent Recovery Process for Soybean Oil: The solvent recovery process is the

separation of solvent from both oil and meal. Solvent leaves the extractor both in

miscella and as residual on the defatted flakes. The process of removing solvent

from each is described below as well as a discussion of solvent losses. Vapors from

either of the desolventizing processes pass through the vapor recovery system

previously described.

Removing solvent from miscella: Solvent is removed from the miscella by double-

effect evaporation and steam stripping.

First, it passes through a long-tube vertical evaporator with a vapor dome. As themiscella passes through the tubes, it is heated, and 70 to 85 percent of the solvent

evaporates. The second-stage evaporator, which further concentrates the miscella,

is a rising film evaporator that operates under partial vacuum. Most remaining

solvent is finally removed as the oil passes through an oil stripper where, under

vacuum, it is exposed to steam and then an oil dryer. The crude oil then goes into

storage to await refining.

Vapors pass through a condenser and a mineral oil absorption system, which

removes solvent from the air before it is discharged. This system includes a packed

absorption column, a packed steam-jacketed stripping column and heat

exchangers.

Removing solvent from spent soybean flakes: Defatted flakes generally contain 35

to 40 percent solvent that must be recovered before the flakes are used. (Flakes that

have been processed with expanders may contain as little as 25 percent residual

hexane.) If the flakes will be used for animal feed, they will undergo conventional

desolventizing. If they will be used for human consumption, they will undergo

flash desolventizing, which better preserves nutritional value.

Conventional desolventizing involves conveying the spent flakes through a

desolventizer-toaster (DT), where they are toasted to about 100C (212F) andtreated with both contact and noncontact steam to remove solvent.

Flash desolventized, which is used on less than 5 percent of soybeans processed,

involves either processing flakes under vacuum with noncontact steam or passing

them through a loop using superheated hexane. Flakes are then treated with small


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quantities of steam in a rotary or agitated vessel. The flakes produced by flash

desolventizing are called whiteflakes.

Solvent loss: Processing plants recover and reuse almost all solvent. Losses may

occur, however, through leaks in equipment and process seals, and through

retention by the meal and oil. Because of the nature of the processes, hexane losses

from flash desolventizing tend to be higher than for conventional desolventizing.

Total solvent loss in a wellrun plant can be as low as 0.5 kg of solvent per metric

ton of beans processed (0.2 gal/short ton). About half of the loss usually comes

from residual solvent that remains in the meal after desolventizing. This loss

occurs during meal drying and cooling, which are described below.

Further Processing of Meals and Oil: Following the desolventizing process, meals

and oils are further processed for their respective end uses. These processes are

described briefly below.

Meal drying and cooling: Meal that has undergone desolventizing-toasting is about105C (221F) and contains 16 to 20 percent moisture. It must pass through drying

and cooling units. In the drying unit, hot air is blown into the meal from below.

Excessive heat and air velocity must be avoided to minimize the risk of fire and

excessive dust. The same process is used for cooling, except the air used is at room

temperature. During drying and cooling, the air removes some residual solvent

from the meal in addition to dust. This air may be passed through a particulate

control device before being released to the atmosphere. Once cooling and drying

are complete, the meal is ground, sized, and shipped for further processing.

Further processing of crude oil:

The oil produced by the extraction process is crude oil that contains proteinaceous

material, free fatty acids, phosphatides, and other impurities that must be removed

before the oil is used. To remove these impurities, the oil must undergo

degumming, refining, bleaching, and deodorizing. Each of these is described

below.

Degumming:Sometimes processors degum crude oil to remove phosphatides,

or vegetable gums. This process prepares the oil for long-term storage, transport, orfurther refining and also produces lecithin, a food additive. Processors degum

crude oil by mixing it with water, then they put it through settling or centrifugation

to separate the gum.

Caustic refining: The most common process for refining vegetable oils is caustic

refining. Oil may or may not be degummed prior to caustic refining. Caustic


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refining involves mixing the oil with an aqueous alkali solution. The alkali

neutralizes the free fatty acids, creating soapstock. The soapstock then adsorbs

colors and precipitates gums and proteinaceous materials. Soapstock is removed by

settling or centrifugation. The oil is then washed with water to remove residual

soap.

Physical refining: Physical refining, an alternative to caustic refining for some

oils, is a steam-stripping process whereby steam is injected into the oil under low

pressure and high temperature, thus vaporizing impurities. Although this process is

feasible with palm oil, it is currently infeasible for processing soybeans because of

problems with flavor stability. This method has received attention from researchers

because it has the advantage of not producing soapstock, a waste product that may

create water pollution problems.

Bleaching: The purpose of bleaching is to reduce or remove the following:pigments, oxidation products, phosphatides, soaps, and trace metals. Bleaching

also improves the flavor of the oil. The products used for soybean bleaching are

neutral earth, acid-activated earths, activated carbon, and silicates. Diatomaceous

earth or another inert material may also be used to aid filtering. The process

involves mixing the oil with the earth, heating the mixture, then filtering.

Deodorizing: Deodorizing is the final step in refining.Steam is injected through

the oil under low pressure and high temperature, removing any off-flavors or

odors.

Processing of Other Vegetable Oils:As previously mentioned, the processes for producing other types of vegetable oils

are similar to that for soybean oil. Differences are noted here.

Cottonseed Oil:

Differences in Preparation: Cottonseeds used for oil come from cotton gins where

the seeds are separated from the fibers. They must undergo an additional cleaning

step called delinting where they pass through a series of cylindrical saws to

remove any remaining cotton fiber from the seeds.

Differences in Extraction Process:

Some cottonseed processing plants use prepressing for initial oil extraction. A

mechanical screw-press, which exerts up to 2,000 pounds of pressure per square

inch, removes some of the oil. The remaining oil is removed through solvent

extraction.


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Difference in Plant Size: Soybean crushing plants are generally larger than

cottonseed crushing plants.

Corn Oil:

Differences in Preparation: Corn oil is concentrated in the germ, which can be

separated from the hull by either wet milling (used to produce starch and corn oil)

or dry milling (used to make grits, meal, and flour).36 Wet milling involves

soaking the kernels in warm water with a small amount of acid. Then the wet corn

is ground into a slurry and passed through germ separators. Here the germ is

separated, washed to remove starch, and dried.

Differences in Extraction Process: Corn oil processors remove about 80 percent of

the oil from the germ by prepressing and use solvent extraction to remove the rest.

Peanut Oil:Differences in Extraction Process: Prepressing removes about 50 percent of the oil

from peanuts. Solvent extraction removes the rest.

Inputs

The primary inputs to vegetable oil processing are the specialized inputs, oilseeds

and hexane, and the nonspecialized inputs, labor, capital, and energy. In this

section, each specialized input is described.

Oilseeds: Oilseeds are the primary input in the production of vegetable oils.

Domestically produced oilseeds include soybean, corn, cottonseed, peanut,

sunflower, safflower, and canola (rapeseed). Because oilseeds are agricultural

products, their supply is determined by many factors, including weather, disease,

costs of agricultural chemicals, prices of commodities, and government programs.

In particular, corn, soybean, and cotton production have been affected by

government programs. However, in the future, government programs will play a

less significant role in determining the supply of agricultural products. The

1995-1996 growing season was the last to be regulated under the 1990 Food,

Agriculture, Conservation and Trade Act. This

Act contained numerous provisions intended to stabilize farm income and regulate

supply through acreage restrictions and payments to farmers. The FederalAgricultural Improvement and Reform Act of 1996 (also called the 1996 Farm

Bill) legislates major changes in federal agricultural programs. It provides for a 7-

year transition period of declining government involvement in agriculture and

payments to farmers that are decoupled from production volumes.Thus, in the

future, farm programs will no longer affect the price or production of any of the

oilseeds.


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Hexane: Hexane is the solvent used commercially to extract vegetable oils. It is

not pure hexane but is a petroleum fraction that is a mixture of 6-carbon-atom

saturated hydrocarbons. The components of extraction-grade hexane vary

depending on suppliers. It will typically consist of from 50 percent to 90 percent n-

hexane by volume. It may also contain isohexane and methylcyclopentane. The

boiling point is critical and may range between 65 and 70C (149 to 158F).

Impurities such as sulfur, benzene, and other aromatic compounds must be avoided

in hexane used for extraction because they may cause odors or toxicity.

Scientists have explored the possibility of alternative solvents for vegetable oil

extraction. A desirable solvent would have the following characteristics: plentiful

supply, low toxicity, nonflammability, high solvency power, ease of separation

from extracted material, desirable boiling point, low specific heat, low latent heat

of vaporization, and high stability. The disadvantages of hexane are its

flammability and dependence on the supply of petroleum. Because ofhexanesflammability, processing plants must have very high safety standards. Researchers

have considered aqueous or supercritical carbon dioxide extraction for vegetable

oils. This method has not yet been shown to be feasible and would not be adaptable

to existing plants without major capital expenditures. At present, hexane is the best

solvent available to vegetable oil processors.

TYPES OF PRODUCTS AND SERVICES

The major domestic oil crops include soy, corn, cottonseed, peanut, and sunflower.

The minor oil crops include canola, flax seed, mustard, canola (rapeseed), and

safflower. The following section describes each of the three most significant oils:

soybean, corn, and cottonseed.

Soybean Oil: Soybean oil makes up over 75 percent of the edible fats and oils

consumed in the United States. It also has an number of industrial uses. Several

characteristics make soybean oil desirable. It has a high level of unsaturated fat, it

remains liquid over a wide temperature range, it can be partially hydrogenated, it

can be readily refined, and it contains naturally occurring antioxidants. It has twodisadvantages:

It has a relatively high content of phosphatides that must be removed in processing.

Its high polyunsaturated fatty acid content makes it susceptible to oxidation and

flavor changes.

Salad oil, cooking oils, and frying fats can be made from pure soybean oil.

Semisolid shortenings can contain mostly partially hydrogenated soybean oil with


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small amounts of completely hydrogenated palm or cottonseed oil. Soybean oil is

the primary oil used in the manufacture of margarine.

Corn Oil: Corn oil is a very high quality oil because of its high polyunsaturated

fatty acid content and its low linolenic acid content. Production of corn oil has

increased recently because of increased demand for other corn products that are

produced jointly with corn oil. These include ethanol for the fuel market and high-

fructose corn syrup.

Cottonseed Oil: Cottonseed oil is higher in saturated fats than soybean oil but has

a very low linolenic acid content. Cottonseed oil has become popular because of its

functionality and flavor. Acreage of cotton has remained stable in the United

States, while the demand for whole cotton seeds as a dairy feed and oil seed has

increased. The increased domestic demand has caused a decrease in exports.

MAJOR BY-PRODUCTS, CO-PRODUCTS, AND SUBSTITUTION

POSSIBILITIES:

A number of other commodities, such as cake or meal, hulls, and linters, are

produced jointly with vegetable oil.

In the case of corn oil, joint products also include corn starch; corn sweeteners,

including high-fructose corn syrup; corn gluten feed; and corn gluten meal. By-

products of the degumming and refining processes also include lecithin,

soapstocks, deodorizing distillates, and spent bleaching earth.

Cake and Meal: Cake or meal is the residue left after the oil is extracted from a

seed, nut, or kernel. Most cake or meal is used in high-protein animal feeds. Small

amounts of soybean meal (about 2 percent) are used for human consumption.

Hulls:Hulls are the outer covering of soybeans and oilseeds.

Hulls are removed from cottonseeds, sunflower seed, peanuts, and soybeans, but

not from canola prior to extracting oil.

They are used primarily in animal feeds.

Linters: Linters are the short fibers that adhere to cottonseeds and must be

removed prior to processing. These fibers have commercial value.

Lecithin: Lecithin is a mixed phosphatide product that results from the

degumming process. Food processors use it as a wetting and dispersing agent, an

emulsifier, and an antioxidant. Lecithin also has many uses in pharmaceuticals,


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cosmetics, animal feeds, and other industries. The supply of lecithin is two to three

times greater than the demand. To dispose of excess lecithin, processors may add it

to the meal or dispose of it in the soapstock.

Soapstock: Soapstock, a by-product of the caustic refining process, has commercial

value in animal feed and in the manufacture of soap and other chemicals. In 1992

the National Oilseed Processors Association changed the name from soapstock to

refining by-product lipid to better reflect the products use as an animal feed.

Deodorizing Distillates: Deodorizing distillates contain tocopherols and sterols,

both of which have commercial value. Tocopherols are used to manufacture

vitamin E and other antioxidants. The pharmaceutical industry uses sterols in the

production of many drugs including hormones and steroids.

Spent Bleaching Earth: Spent bleaching earth, which is a mixture of clay and oil,

must be handled with care because it is flammable. Processors can add it to animalfeed, and the oil adds calories and the clay reduces caking. It can also be burned as

a fuel, mixed with organic materials and composted, or disposed of in a landfill

after treatment with water to reduce flammability.

Documents

Soybean Report