Three-column Differential Pressure Distillation
Process description of three-column differential pressure distillation
The differential pressure of the process unit is: the differential pressure between rectifying column T502 and beer stripping column (mash column) T501, aldehyde column is for atmospheric distillation.
1、The fermentation mash from fermentation section is preheated to 70 ℃ through primary preheater E502 (Fermentation mash is preheated by crude alcohol vaporcondensed at the top of the mash column), secondary preheater E507 (Fermentation mash is double preheated by waste distillers in mash column), and feed into the mash column at the 24th tray. Mature mash is heated by the bottom steam when downward in the mash column T501, alcohol vapor is upward and separated from the waste mash. Waste mash is discharged at the bottom of the column, and the alcohol content of waste mash is no more than 0.05% and transported to the environmental protection section. Upward crude alcohol is for defoaming (low concentration alcohol) by 25th, 26th defoaming plates and enters into 1 # preheater, part of the alcohol vapor is condensed, uncooled alcohol vapor continues to be condensed by a set of condenser. The condensate liquid is heated indirectly by steam condensate water and residual distilling water (waste water at the bottom of the column) of rectifying column and enters into the aldehyde column T503. Part of the crude alcohol is reflux (the purpose is for defoaming the crude alcohol gas), while some non-condensing gas is discharged into the atmosphere through the vacuum pump.
Heating mode of mash column: the alcohol vapor at the top of the rectifying column heats the mash column through the reboiler E501, The reboiler uses a circulating pump for circulation. The mash column works under the negative pressure, the negative pressure is produced by the connection of the vacuum pump through the bank of condensers.
2、Aldehyde column works under the atmospheric pressure. Condensate liquid (crude alcohol) from mash column is indirectly heated by the steam condensate water, enters into the aldehyde column at the 16th tray. The head impurities such as aldehydes and esters move upward to the top of the column. After condensation, most of the alcohol vapor at the top of the column will reflux, and a small part is extracted as industrial alcohol. Low boiling point gases such as aldehydes and esters and non-condensable gas are discharged into the atmosphere through the auxiliary condenser. After separation, the light alcohol at the bottom of the column is relatively pure, and enters into the rectifying column after being preheated by the residual distillation water (waste water at the bottom of the column).
Heating mode of aldehyde column: is directly heated by the fresh steam and the flash steam.
3、Light alcohol from aldehyde column T503 is indirectly heated by the residual distilling water of rectifying column, enters into the rectifying column at the 18th tray. While the light alcohol is gradually concentrated, head impurities such as methanol and aldehyde are upward with alcohol vapor to the top of the column, part of impurities (such as oil) is retained on the upper layers of the feed plate whereby as fusel oil produced into the fusel oil separator for oil and alcohol separation. Fusel oil enters into fusel oil storage tank V509, and light alcohol enters into light alcohol tank and is pumped to the fermentation mash tank. The head impurities can be removed by extracted part of the reflux as industrial alcohol. The alcohol with a concentration of 95-96% (v/v) in the 6-8 trays below the reflux mouth of the column top is extracted as the finished product, and after cooling, the high concentration alcohol enters into the finished product alcohol tank.
Heating mode of rectifying column is heated indirectly by fresh steam through the rectifying column reboiler, and the condensate water is flash steamed and sent to the crude alcohol preheater by the condensate pump for exchanging heat with the crude alcohol and then return to the boiler room for reuse. The flash steam is used as part of the heat source of the beer stripping column.
|Column plate||Distillation column manufacture|
|Two-columns distillation||Three-columns distillation|
|Five-columns distillation||Several-columns distillation|