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[mals]

Hi,

We split non edible vegetable oil at 235 deg C and 32bar pressure, its a batch process. The process is;
1. Pressurize the Oil in autoclave to 32bar using open steam. Duration is 1hr 30 min
2. Vent the vapours from autoclave till the Pr. goes down to 30bar
3. Re-pressurize autoclave till 32 bar and charge demineralised water into autoclave to wash away the Glycerine. Wash water qty is decided on the Free Fatty Acid present in the oil. Also note that the pressure in autoclave will be maintained 32 bar during washing process. Duration is 40 min
4. Oil is settled for 10 min and batch is dropped. Glycerine sweet water and crude fatty are collected in separate tanks

My query is, why is the venting operation required and why cant we start washing operation at 20 bar or any other pressure below 32 bar? Actually I tried washing at 24 bar, but the degree of split was low.

Can i get my doubts cleared??????
Please help.

Mallik