Mecpro has invested for years in research and development for improving the technology used in Solvent Extraction Plants. The total work done in this area is very vast and covers all areas from raw material Preparation to bagging of deoiled meal. All equipment are of superior construction to reduce utility consumption and downtime. The large number of innovations make Mecpro’s Solvent Extraction Plant your best choice. These reduce your operating cost, increase the efficiency of your plant and are environment friendly features.

Out of these the most important ones are being described here. They include

Vent-air purification system

The vent air purification system allows hexane to be recovered in the solvent extraction plant instead of letting it escape to the atmosphere.  This innovation results in a hexane loss of below 1 kg per metric ton of feed material processed, which is an achievement unparalleled by other method.

Process description

To create vacuum in the toaster, conveying equipment, extractor and other equipment except in the distillation section, we use ejector or fans at the final vent at a pressure of about 0.5 kg per cm2. By adopting the new system this pressure can be increased upto 7 kg per cm2 without any additional loss to the atmosphere. As a result all the equipment will be under an adequate vacuum because desolventisation efficiency can be improved. Thus, solvent losses will be at the minimum. We have observed that during continuous operation out of the total hexane losses 35% are through vent air, 40% through desolventising toaster, 5% through oil, and 20% through leakages. By adopting the new system all these losses except through oil can be reduced by upto 90%.

In our new system, the vent air is taken back into the vent air purification system instead of discharging to atmosphere, where the air is dissolved in the water by high pressure mixing method. Hexane is arrested by water, which is then taken into the water separator and hexane is recovered for re-use. The final traces of hexane and air that escape from the purification system are taken to the extractor where the hexane is absorbed by the raw material and the air is discharged.

With the adoption of the vent air purification system, there is no need of a refrigeration unit in the project to condense the hexane.

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Low temperature miscella separation (Patented)

This is a process of separating hexane from the miscella at a low temperature. It is achieved by means of azeotropic distillation using a reflux column. A reflux column is designed to perform the most efficient distillation of hexane from the miscella so that the maximum possible amount of hexane is recovered at a lower temperature. The process has been perfected in a series of laboratory trials and actual implementation in India and abroad.

Process description

After conducting a detailed study of the conventional process of hexane separation and the excessive losses of hexane, deterioration of oil and development of non-hydratable phosphatides therein, we have developed a new process named azeotropic distillation. It refers to a process in which a component (known as the solvent or entrainer) is added at the top of the column to form a homogeneous complex known as an azeotrope, which is removed as distillate itself. The other component free from the solvent is collected at the bottom of the column. In this case, the process is quite different from the normal stripping distillation because the solvent that appears as distillate can be separated at a lower temperature and refluxed at the top of the column for augmentation of the process.

In isothermal distillation, no physical or chemical changes take place to any of the components present. The complex formed in the vapour filter is fed to the reflux column where the hexane separation takes place isothermally at 65oC, the vapourising temperature of hexane. 

By means of the reflux column, miscella separation at 65o C for non-frothing oil and 75oC to 85oC in frothing oil like soybean and mustard is achieved. Plants not using the reflux column separate the miscella at an elevated temperature of 120oC with sparged steam, due to which oxidation of oil and degradation occur.  Also steam sparged at this elevated temperature in the stripper increases non-hydratable phosphatides which increases the refining loss. At a lower temperature with a reflex column water degumming is possible provided harvesting and storage of the seed was proper.

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Special filtration system (Patented)

The special filtration system uses special filter media to reduce the level of impurities and volatiles to below 0.1% as against anything up to 2% in the conventional filters. This helps in avoiding degradation of the oil and improving distillation. This will not only reduce the capital investment but also reduce the operating cost and maintenance cost to make it more economical.

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Waste Water Recycling System (Patented)

Most of the Solvent Extraction Plants use water ring vacuum pump to create vacuum in the process.  The pump installed requires 20 Ltr/min, water and it is heated in the waste water boiler from 30oC to 95oC prior to discharge to the waste pit. In this process delta 65oC has to be raised. So the total water coming out from the vacuum pump is more than 30,000 ltr. So the total heat consumed is 30,000 x 65 =18,72,000 K. Cal besides the same quantity of water is discharged as an effluent which has to be handled for the disposal. By developing this recirculating system one can save this heat energy handling problem of effluent from the project. So in the new method the water that comes out from the vacuum pump to the water separator, will be recycled to the vacuum pump after cooling. Therefore, there shall be no loss of heat energy or production of effluent.

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Desolventization (Patented)

The recent innovation and research in the desolventization of hexane from defatted meal reduces the steam consumption and temperature by adopting a blower to accelerate the hexane separation.  The control system is so simplified that there will not be any error in the desolventization, which makes lower hexane ppm in the discharged defatted meal and no deterioration of product in desolventization.

Generally 125 kg of steam is consumed in the desolventizing toaster per metric ton processed.  Out of this, 75% of the steam consumption is sparged steam to strip out the hexane from defatted meal.  With the adoption of blower 40% of the sparged steam is reduced in the desolventization process.  In recent research a 150 ton plant could run with 20 amps load, so the desolventizing toaster can give a quality product with lower utility consumption.

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