Continuous Chemical Refinery

Continuous Chemical Refinery

The system is designed to fully refine, i.e. degum / neutralize, bleach, strip and deodorize seed oils. The Degumming / Neutralizing System are used as the first step in chemical refining referred to as Neutralizing. This step will generally produce oil with lower levels of residual phosphatides and less residual pigments and therefore require less bleaching earth in bleaching as well as help generate finished deodorized oil with a lighter color and longer shelf life. The process design is illustrated on the attached drawing. The Bleaching System is based on treatment with bleaching earth followed by filtration. The process design is illustrated on the attached drawing. The High Efficiency Deodorizing System can be used for deodorizing of neutralized oils as well as stripping and deodorizing of high FFA oils as part of physical refining. The process design is illustrated on the attached drawings.

Degumming , Neutralizing , dewaxing , Water Washing and Vacuum Drying System

The oil is delivered to the system by the Feed Pump. It is heated to 65 - 70 C in the Crude Oil Economizer by hot oil from down-stream bleaching/deodorizing operations or, when necessary, by steam in the Feed Heater mixed with pre calculated quantity of Phosphoric acid in an gum conditioning mixer and fed to mixer where the pre calculated quantity of water is added . Oil water mixture is fed to hydration tank to give sufficient residence time for gums to agglomerate on hydration. This oil is then pump to separator where the oil and hydrated gums are separated and pumped to storage or disposal or gum drying plant in case of soybean gums.

In case of water degumming process crude oil is heated to required temp in the plate heat exchanger ,mixed with pre calculated water through mixer and fed to the hydration tank for sufficient residence time for gums to agglomerate. Then it is pump to separator where oil and hydrated gums are separated.

Water degummed oil from separator is pumped to plate heat exchanger where oil is heated to neutralization temperature i.e. around 80 to 85 Deg C. The hot oil is fed to mixer with requisite quantity of phosphoric acid where oil and phosphoric acid is allowed a brief holding time and the precipitation and trace metals takes place.

Degummed oil is fed in to mixer where where it is mixed with calculated quantity of caustic soda solution of suitable strength .Free fatty acid to react with caustic soda to form soap . The reacted oil is sent to the Gum/Soap Separator . The precipitated impurities are removed from the oil as water based heavy phase referred to as soap stock. The gums/soap are collected in the Heavy Phase Receiver and sent to intermediate storage by the Heavy Phase Pump.

Dewaxing :-

After the neutralization the outlet oil Specification of separator is managed in such a way that it left with around 3000 to 3500 ppm as soap which acts as seed for the de-waxing . This oil is first cooled by cooling tower water up o 40 to 45 Deg C. Then this oil is cooled by outgoing de-waxed oil from the separator. This oil is then chilled to de-waxing temp and feed to Crystallizers. In the crystallizer proper residence time is given with maintaining the temperature of the oil , which results in formation of wax crystals and residence time will give proper growth to the crystals. In this a measured quantity of water is added so that the waxes from oil phase moves to water phase with soap stock.

This mixture is then feed to Centrifugal separator where waxes with soap is separated and oil is separated.

This oil is washed and vacuum dried.

Water Washing: The residual soap in the degummed & neutralized oil is reduced by water washing. In this case the oil from the separator is heated to about 95 C in the Washing Heater and then mixed with 10 - 15% soft water in the Wash Mixer. After a few minutes retention in the Wash Reactor the wet oil enters the Wash Water Separator. The washed oil, typically containing under 100 ppm soap and with a reduced level of phosphorus, is sent directly to bleaching as described above. The heavy phase soapy water is collected in the Recovered oil tank and drained to Effluent treatment.

Vacuum drying: Washed oil is fed continuously to the Vacuum dryer and sprayed through specially designed nozzles. The vacuum dryer is kept under a vacuum of 70 torr. The dried oil from the vacuum chamber is continuously pumped out by pump P105 to intermediate storage tank (not included).

The feed oil (acid conditioned, degummed / neutralized & washed) enters the Bleacher via a Bleaching heater where the oil is heated up to Bleaching temperature and discharged into the slurry mixer. A valve dosing system proportions bleaching earth. The earth is introduced under the oil spray in the mixing chamber for improved mixing so that earth does not enter the Bleaching Vacuum System. The earth adsorbs any residual gums and soap as well as trace metals, color bodies and other polar impurities. The Bleacher has multiple agitated compartments and operates under vacuum to ensure complete moisture and air removal. The dried oil and earth mixture is discharged by the Bleacher Discharge Pump to one of the Filters where the spent earth is removed. The filtered oil is collected in the Filtrate Receiver. The Bleached Oil Pump sends the oil to Deodorizing via one of the alternating Polish Filters.

Bleached oil is continuously pumped from the Feed Tank by the Deareator Feed Pump. The oil is pre-heated in the Deaerating Economizer by outgoing deodorized oil followed by the Deaerating Heater (if necessary) before entering the Deaerator. The vessel is under full vacuum, so that residual air is reduced to an absolute minimum. The Deaerator Discharge Pump sends the oil through a Heat Economizer where the temperature is increased by hot deodorized oil. The oil is heated to full processing temperature in the Vacuum Heater by thermal fluid from the Thermal Oil Heater. A portion of the free fatty acids in the oil will be flashed off as the oil temperature increases.

Stripping: The hot oil enters the Packed Column, which is filled with special structured packing so that the oil is distributed into a thin film and is evenly agitated by stripping steam flowing counter currently from the bottom of the column. As a result, free fatty acids and other remaining volatile impurities in the oil are evaporated and removed with the steam. The residence time in the column is only a few minutes. The bulk of the free fatty acids along with aldehydes, ketones etc. in the oil are quickly stripped off before any heat induced permanent damage has been done.

Deodorizing: The stripped oil from the column flows into the Deodorizer where it flows through the channels of a series of vertically stacked compartments (trays) while agitated by stripping steam. The prolonged thermal action breaks down carotene and other color bodies, resulting in a lighter oil color. Also, the amount of remaining free fatty acids in the oil is reduced to an absolute minimum. The stripping steam passes through the packed column and no separate steam is required in the stripping column. The maximum retention time in the Deodorizer is 70 minutes.