green productivity measures to reduce hexane loss in...
TRANSCRIPT
Green Productivity Demonstration Program (GPDP) in Soybean Processing Industry
(M/s Rama Phosphates Ltd., Indore, INDIA)
(March 2002)
Asian Productivity Organisation, Japan
Prepared by
Environment Division
National Productivity Council, India
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G R E E N
P R O D U C T I V I T Y
Sponsored by
GREEN PRODUCTIVITY MEASURESTO REDUCE HEXANE LOSS
IN SOY PROCESSING INDUSTRY
GREEN PRODUCTIVITY MEASURESTO REDUCE HEXANE LOSS
IN SOY PROCESSING INDUSTRY
Large quantityof hydro carbons discharged into atmosphere.
Inadequate DTDC
Inadequate steam supply in SEP
High moisture in collets
ENVIRONMENT
Machine
Man
Method
Material
Poor recovery of Hexane
Inadequate recovery facility
Inadequate recuperation system
High bed thickness
Inadequate Design
Insufficient contact betweenDOC and steam
Less heating surface area for indirect steam
Less absorption of hexaneby Mineral oil
Fouling of condenser
Absence of rotary valveat out let
Air ingressmentImproper Condensation
Inadequate recuperation system
Fluctuation in steam pressure
Insufficient Boiler capacity
Improper Extractor Less drainage time for miscella
Mind set InadequateVacuum
Leakage through Extractor Sealing
Work instruction not duly followed
Negligence of plant periodicmaintenance
Shortage of skilled manpower
Hexane retention by residual oil
High residual oil in DOC
Power interruption
Damaged / green seed
High moisture in seed
Inadequate cooking
Improper seed preparation
Inadequate Cracking & Flaking
Improper flake thickness
Worn out flaker rollers
Insufficient plasticity
Common condensation of vapour
Improper Cleaning
Presence of foreign matter,which is being considered as seed
High solvent seed ratio
Improper flaking
Faulty quality control of flake thickness
Considering average thickness instead of standard deviation
CAUSE & EFFECT ANALYSIS FOR HEXANE LOSSES
Hexane Loss
G R E E N
P R O D U C T I V I T Y
PROBABLE CAUSES
Inadequate vacuum in DTDC & distillation
Inadequate steam supply
Inadequate condenser cooling
Inadequate size of condenser
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EFFECTS
Inadequate vacuum leads to
Poor separation of hexane in distillation &
Desolventisation
The Quality of Crude Oil & DOC may further
degrade due to high concentration of hexane.
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Inadequate desolventisation in DTDC
Inadequate steam quantity & pressure
Inadequate heating surface area
Low retention time in DT
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Inadequate desolventisation leads to
Hexane carryover along with meal dryer air,
resulting high hexane loss
.
Inadequate drainge in extractor
Inadequate drainage time
High hexane concentration in wet DOC
.
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Inadequate drainage in extractor leads to
Additional hexane carry over with wet DOC
More load to the DT
.
.
BACKGROUND:
CAUSE EFFECT ANALYSIS
India is the fifth largest producer of Soybean in the world. However, India's share in world production of
soybean is only 3%. It is evident from the statistics, that the specific raw material and chemical consumption in
Indian Soybean Processing Industries is very high compare to developed countries. This resulting in high
production cost which is great bottleneck for the survival in the competitive international market. Looking in
potential of improvement in this sector, Asian Productivity Organisation, Japan entrusted a project titled
. Subsequently, M/s Rama Phosphates
Ltd.-Oil Division (RPL), Indore was selected for detailed study. Lots of areas were identified for improvement.
The hexane loss is one of the critical areas where in-depth study was carried out to identify causes for high
consumption of hexane and their possible Green Productivity Measures to bring down the specific
consumption of hexane to the minimum possible level.
Various tools were applied to know the causes of hexane loss in soybean processing industry to produce
refined oil. The well-known Ishikawa Diagram (Fish-Bone Diagram) was prepared, as shown in figure, show
the various causes and their effect for hexane loss. The outcome of the study at M/s RPL is discussed below:
The hexane is used as a solvent for the extraction of oil. In India, on an average, the hexane loss is 3.0~5.0
lit/Ton of seed process. However, it can be reduced to 2.0~3.0 lit/Ton of seed process. The high hexane loss
results in high production cost, high fugitive gas emission, poor quality of DOC and crude oil. The major areas
of hexane exits in the SEP are: (I) Carryover along with crude oil, (ii) Uncondensate vapour going through final
vent of recuperation unit, (iii) Carryover with meal drying air in DTDC, (iv) Carryover with DOC and (v) hexane
emission from leakages.
There are number of reasons for high hexane loss in SEP. The possible causes of high hexane loss in SEP and
their effect are discussed below.
"Green Productivity Demonstration in Edible Oil Industry in India"
G R E E N
P R O D U C T I V I T Y
GREEN PRODUCTIVITY OPTIONS TO REDUCE EXCESS OIL CONTENT IN DOC
The possible solutions for reducing high hexane loss in SEP are:
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Ensure adequate steam supply (quantity & pressure) without interruptions by providing adequate sized
boiler(#)
Provide cold/chilled water for effective condenser cooling
Maintain optimum bed thickness and steam pressure in the desolventisation compartment of DT.
Increasing heating surface area in DT by providing more limpets
Increase the hexane drainage time in extractor
Increase mineral oil flow rate to improve recuperation (#)
Increase heating surface area of PHE to improve recuperation (#)
PROBABLE CAUSES EFFECTS
Inadequate recuperation
Inadequate absorption/release of hexane
Inadequte condenser size
.
.
Recover of hexane from recuperation system may
be poor. More fugitive hexane loss.
Inadequate crude oil stripping
Inadequate steam & Vacuum
Inadequate condenser size
.
.
Poor oil stripping leads to more hexane carryover
with crude oil resulting in more hexane loss and poor
quality of crude oil.
Increased Heat Surface Area of Plate Heat Exchange (PHE)
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Increase chilled water flow rate in vent condenser to improve recuperation (#)
Install separate condenser with steam ejector in stripper to increase vacuum (#)
Additional Steam Ejector installed for increasing vacuum in the Stripper
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COST BENEFIT ANALYSIS
OTHER BENEFITS
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The solvent ratio (solvent:seed) should be in the range of 0.8~0.9
The miscella concentration should be in the range of 26~35%
The hexane concentration in wet DOC should be in the range of 30~33%.
Retention time in DT should be more than 60 minutes
o
The temperature at top of DT should be 70~72 C.
o
The temperature in stripping should be 105 C
o
The flash point in crude oil should be more than 100 C.
Periodic replacement of spent mineral oil with fresh mineral oil
The Demonstration Unit (DU) in India having capacity to crush 400~450- TPD soybean seed, implemented five
options (marked as #) and invested directly Rs. 1.95 lakh (US$ 4,150) in SEP and indirectly Rs. 120 lakh (US$
2,55,360) for installing new higher capacity FBC Boiler. The unit gained financial saving of Rs. 12.7 lakh (US$
27,000) per annum as a result of reduction of hexane loss of 12.2% (from 4.93 lit/T to 4.3 lit/T). By installing
higher capacity boiler, the unit gained further in the reduction of oil content in DOC, high capacity utilisation in
SEP, increase in power generation & saving in steam cost and coal.
Implementation of GP options resulting in following additional benefits:
Productivity enhancements as a result of low production cost.
Better capacity utilisation of plant
Prevention of fire hazard
Higher recovery of uncondensed hexane
For Further details Contact:Director, Environment Division
NATIONAL PRODUCTIVITY COUNCIL
5-6, Institutional Area, Lodhi Road New Delhi- 110 003.
Ph. 91-11-4611243 Fax:91-11-4625013/4615002
E-mail: [email protected] Web-Site: www.npcindia.org
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