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CASE STUDIES- 5

CLEANER PRODUCTION CASE STUDY REFINED EDIBLE OIL & VANASPATI MANUFACTURING

1. INTRODUCTION
2. PROCESS DESCRIPTION
- Degumming
- Neutralisation:
- Bleaching:
-Hydrogenation

- Post Neutralisation
-Post Bleaching
-De-odorisation
-Final filtration
-Filling and chilling
3. STUDY FOCUS AREAS
4. CP OPPORTUNITIES THAT REDUCED ENVRIONMENTAL LOAD AND ACCRUED ECONOMIC BENEFITS
5. POLLUTION STATUS BEFORE AND AFTER CP IMPLEMENTATION:



1. INTRODUCTION

This is a case of M/s. Ashwin Vanaspati Industries Ltd., located in Vadodara and engaged in production of vanaspati & edible oil with a production capacity of 60T/day of vanaspati and 30T/day of various types of refined oil.

The unit has identified Cleaner production as a way to reduce their pollution load to ETP and conserve resources. This case study outlines the results of the study under taken by them for soya bean oil.

2. PROCESS DESCRIPTION
Edible oil procured from extractors is processed to produce vanaspati and refined oil. The various processes/operations involved are described below in brief.
Degumming:

The crude oil contains free fatty acids & gums, it is degummed using phosphoric acid or any other suitable degumming agent.

Neutralisation:

After degumming the free fatty acid are neutralised with alkali. The reaction with alkali produces soap stock which is seperated from oil by washing with hot water to remove excess caustic. The soap stock is then seperated and taken to the acid oil recovery section where it is acidified with sulfuric acid to recover acid oil.

Bleaching:

The neutralised oil is bleached using activated earth and carbon at an elevated temperature to remove the colour.
The bleached oil is filtered using filter press to remove the spent earth and the oil for further processing. Filter press is being cleaned after every batch using steam.

Hydrogenation:

The filtered oil is taken in a closed reactor and hydrogen gas is continuously sparged in presence of Nickel catalyst at elevated temperature. This is performed to reduce the content of unsaturated oil.
Excess hydrogen gas is compressed and stored in bullets. It is then recycled to the process. The hydrogenated oil is filtered to remove the spent catalyst, which is recovered and reused.

Post Neutralisation:

The filtered mass is again neutralised with caustic lye to remove the free fatty acids formed during the hydrogenation reaction. Soap stock, which is formed as a result of post neutralisation, is sent to acid oil recovery section. The neutralised hydrogenated oil is washed with water for removing any traces of alkali present. The wash water is drained to the ETP.

Post Bleaching:

The neutralised mass is further bleached with activated earth and carbon to remove the colour. Then the mass is filtered to remove the spent earth and carbon.

De-odorisation:

Odor producing substances are removed in this step with the help of live steam and citric acid under high vacuum & at high temperature..

Final filtration:

The de-odorised oil is further filtered in the filter press to remove any fine particles, and then the required vitamins are added in final filtered mass to improve the quality of the product.

Filling and chilling:
The product is filled in the tins and is kept in chilling room for 24 hours to produce the required granulating property. The product Vanaspati is also packed in pouches of 1000 ml, 500 ml, 200 mol, 100 ml & 50 ml.


3. STUDY FOCUS AREAS
The unit observed that its caustic consumption for removal of fatty acids far exceeds the requirement specified by the quality control department. This excess consumption is not only entailing caustic loss but also oil loss as the excess caustic is saponifying oil other than free fatty acid and excess acid consumption in acid recovery section. And also the unit felt there is a scope for energy conservation in chilling section of vanaspati.To reduce/eliminate the excess consumption the unit as a first step focussed on these areas for CP study.

· Energy consumption in whole plant


4. CP OPPORTUNITIES THAT REDUCED ENVRIONMENTAL LOAD AND ACCRUED ECONOMIC BENEFITS:

The assessment study evaluated causes for higher caustic consumption of caustic and evaluated options for reducing/controlling caustic use and the associated benefits arising there of. The implementation results were briefly described below.

1. The causes of excess caustic use is found to be due to having no controls to measure caustic dosage and not measuring caustic concentration. Using dip check for caustic consumption in storage tank and dosing caustic by metering pump and manual checking of caustic strength measures were implemented. The benefits resulting there of are:
Investment needed = Rs 15,000
Reduction in caustic consumption = 80 T/annum (flakes)
Savings in Caustic consumption =Rs12.12
lakhs/annum Reduction in acid consumption = 98 T/annum
Savings due to reduced acid consumption = Rs 5 lakhs/annum

2. Regularise the suppliers of raw oil. This ensured the quality of the raw material and the industry stopped using Rice-bran oil which produces large quantities of waste in form of soap-stock and wash-water

3. Ensuring seperation of soap stock and wash water with little or no free oil from oil by operating the centrifuge at optimum* RPM and regular maintenance of centrifuge yielded following results

Oil saved =50000 liter
Savings in oil = Rs 15 lakhs/annum
Reduction in COD =60 Tons /annum
Savings due to reduction in treatment cost = Rs 6,00,000/ annum

*Optimum RPM for each type of oil should be established

4. Thermostat set point in Ammonia compressor changed from (-)15oC to (-)2oC. Hence electrical consumption in compressor reduced.
This reduces the Green House Gas CO2 (gas) emission from the power plant.

5. The pouches of vanaspati used to be chilled in chilling room after completing the packing in cardboard cartons. Presently, the pouches are chilled before packing in cartons using plastic trays. This reduces the energy required for chilling & reduced wastage in handling losses. This reduces the
Green House Gas CO2 (gas) emission from the power plant

i) Above solution also saves cartons, which were damaged earlier due to spillage of vanaspati. This reduces the solid waste generated in form of cartons.

ii) The oil spillage, which was earlier not possible to collect, are also collected due to above option and reprocessed. This reduces the solid waste generation

iii) Filter cloth is washed using dilute caustic solution and acid oil is recovered. This improves the washing efficiency of filter cloth

iv) Insulation of all naked & damaged steam pipeline is being done. This will reduce the heat losses to the surroundings and enhance steam saving. This increases the fuel economy thus conserving the fuel for future generation

v) In the batch operation of neutralisation, the separation valve size is reduced from 2" to 1 ½" This allows better control for separation of oil from soap stock and reduces the oil loss into the soap stock.

This option was implemented with an initial investment of about Rs. 1.5lakhs and the savings accrued by this option is about Rs. 5 lakhs/annum.

5. POLLUTION STATUS BEFORE AND AFTER CP IMPLEMENTATION:

The overall comparative results achieved due to this study are given in the following table.
S.No Parameter Before CP(per annum) After CP(per annum) % change
1. Caustic consumption 918 T 840 -8.8
2. COD load 300 240 20
3. WasteWater treatment cost Rs 30 Lakh Rs 25 lakh -17

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