Five-column Differential Pressure Distillation
Process flow description of five-column differential pressure distillation
The differential pressure of the process unit is: differential pressure of rectifying column T0403, dilution column and de-methanol column T0404; differential pressure of dilution column T0402, de-methanol column T0404 and mash column T0401. The impurity column T0405 uses the steam condensate water and the secondary steam from the waste hot water at the bottom of the rectifying column and a small amount of new steam for heating.
a、Fermentation mash from the fermentation section is preheated to about 80 ℃ through the primary preheater E0403 (Fermentation mash is preheated by the crude alcohol vapor condensed at the top of the mash column), secondary preheater E0404 (Fermentation mash is double preheated by the alcohol vapor from the top of the recovery column) and preheater E0405 (Fermentation mash is third-time preheated by the steam condensate water), and enters into the mash column on the 24th tray. The fermentation mash is heated by the steam from the bottom of the column while downward in the mash column T0401. The alcohol vapor is upward and separated from the waste mash. The waste mash is discharged at the bottom of the column. The alcohol content of the waste mash must not exceed 0.05% and it is sent to the DDGS section; the column top is controlled at 60 ~ 65 ° C to evaporate the crude alcohol with a concentration of about 50% (w / w). After being condensated by the primary condenser (primary preheater of mash) on the top of the column and the bank of condensers, it is collected into the crude alcohol tank V0405. Part of the crude alcohol is refluxed, part is pre-heated to the dilution column. Part of the crude alcohol with more impurities is extracted from the mash column condenser III for discharging into the miscellaneous wine tank. The non-condensable gas enters into the vacuum buffer tank for vapor-liquid separation and is discharged into the atmosphere through a water ring vacuum pump.
The sealed water used by the water ring vacuum pump is recycled while a small amount of primary water is added, and the overflow water containing alcohol is returned to the fermentation section.
The heating mode of the mash column: mash column is heated by the vapor at the top of the de-methanol column through mash column reboiler AE0401, and mash column is heated by the alcohol vapor at the top of the dilution column through mash column reboiler BE0402. The reboiler uses a circulating pump for circulation. Mash column works under the negative pressure.
b、The dilution column works under the micro-negative pressure. The crude alcohol from the crude alcohol tank is preheated in two stages by the final alcohol and waste hot water at the bottom of the de-methanol column. Then it enters into the dilution column T0102 from the 30th tray in the middle and upper part of the dilution column, and sufficient heat transfer and mass transfer are carried out with the rectified waste hot water and process hot water coming from the top of the dilution column. Keep the alcohol concentration at the bottom of the column at 10 ~ 15% (w / w). At a lower alcohol concentration, n-propanol, fusel oil and most esters have larger volatility coefficients, which move to the top of the column and accumulate there. The alcohol vapor at the top of the column is condensed by reboiler E0402, part is refluxed, part is sent to the miscellaneous wine tank. The non-condensed alcohol vapor enters into the auxiliary condenser of the dilution column for continuous condensation. The non-condensing vapor enters into the vacuum system, part of the initial distillate is extracted from the auxiliary condenser to the miscellaneous wine tank. After cleaning, the lighter pure alcohol is drawn from the bottom of the column and sent to the rectifying column T0103. The dilution column is indirectly heated by the alcohol vapor at the top of the rectifying column through the dilution column reboiler E0410.
c、The light alcohol from the dilution column T0402 is preheated by the high-temperature waste hot water at the bottom of the rectifying column and enters into the 16th tray of the rectifying column. While parallel to the gradual concentration, first-level impurities such as methanol and aldehydes rise to the top of the column with the alcohol vapor, and part of impurities (such as oil) is retained on the trays on the upper layers of the feed plate, whereby produced into the miscellaneous wine, and extracted to the miscellaneous wine tank V0408; there are some high-grade oil accumulation around 40th tray, and they are also extracted and sent to the miscellaneous wine tank. About 10 trays below the reflux at the top of the column are high-concentration alcohols with a concentration of 96% (v / v) or higher as semi-finished products to the de-methanol column T0104. The alcohol vapor at the top of the rectifying column is condensed by the dilution column reboiler and the demethanolizer reboiler and be refluxed, and the uncondensed alcohol vapor is sent to the 60th tray of the impurities column. Light alcohol of dilution column is preheated by the column kettle waste hot water, the waste hot water enters into the hot water tank for flash evaporation. The flash steam is used as part of the heat source of the recovery column, part of the hot water is used to dilute the crude alcohol at the top of the dilution column, and the other part is used to preheat the crude alcohol and then goes to the front stage for mixing. The heating mode of rectifying column is for indirect heating with fresh steam through the rectification reboiler. After flash evaporation of the steam condensate water, it is pumped by the condensate pump to the three-stage preheater E0405 and miscellaneous wine preheater E0421 and returned to the boiler room for reuse. The flash steam is used as part of the heat source of the recovery column.
d、The de-methanol column T0104 works under the positive pressure. The high-concentration semi-finished alcohol from the rectifying column with a concentration of 96% (v / v) or above enter into the 30th tray in the middle and upper part of the de-methanol column. It is indirectly heated by the alcohol vapor at the top of the rectifying column for secondary distillation. In the de-methanol column, methanol, aldehydes and acids in the alcohol move toward the top of the column and are accumulated there, and the alcohol vapor at the top of the column is condensed through the reboiler E0401 and be refluxed. The non-condensed alcohol vapor enters into the auxiliary condenser of the de-methanol column for continuous condensation. A part of the initial distillate is extracted from the auxiliary condenser and the alcohol enters into the aldehyde wine tank as industrial alcohol, and the finished product is extracted from the bottom of the column to produce edible premium alcohol. After concentrating crude alcohol, light alcohol and other impurity wines in the miscellaneous wine tank, they are directly sent to the recovery system for processing, and there is a recovery column T0405, to improve the yield of the high-grade edible alcohol.
e、The recovery column works under the normal pressure, and it is directly heated by using the flash steam of rectifying column reboiler steam condensate water, the hot water tank waste hot water flash steam and some new steam. Impurity alcohol in the miscellaneous wine tank is preheated by the miscellaneous wine preheater, it enters into the 18th tray in the middle and lower part of the recovery column. The alcohol vapor on the top of the column is condensed by the secondary preheater and the condenser of the recovery column, and part of the initial distillate is extracted as industrial alcohol to enter into the aldehyde wine column. The rest is returned to the column; the miscellaneous wine is collected from the lower trays of the reflux layer and returned to the 36th tray of the dilution column for re-extraction and distillation. The oil-rich wine is collected from the upper trays of the feed plate and be cooled to enter into the fusel oil separator for separating fusel oil. The oil separator separates the fusel oil, and the waste water from the column kettle goes to the hot water tank for flash evaporation. The rich oil wine is fully mixed with the process water in the fusel oil separator and be layered. The upper layer of fusel oil goes to the fusel oil tank, and the lower layer of light alcohol flows into the fermentation section or miscellaneous wine tank.
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