CN110981696A - Process and system for producing fuel ethanol by using double-coarse single-fine three-tower distillation low-concentration fermented mash - Google Patents
Process and system for producing fuel ethanol by using double-coarse single-fine three-tower distillation low-concentration fermented mash Download PDFInfo
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- C07—ORGANIC CHEMISTRY
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- C07C29/74—Separation; Purification; Use of additives, e.g. for stabilisation
- C07C29/76—Separation; Purification; Use of additives, e.g. for stabilisation by physical treatment
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- B01D3/14—Fractional distillation or use of a fractionation or rectification column
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C29/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
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Abstract
The invention discloses a process for producing fuel ethanol by using double-coarse single-fine three-tower distillation low-concentration fermented mash, which comprises the following steps: (1) preheating fermented mature mash with the concentration of below 8% (v/v) to 65 ℃ by a mash preheater, feeding at the top of a degassing section, enabling a part of degassed fermented mash to flow into a negative pressure mash tower, and preheating the rest by a feeding preheater of an atmospheric pressure mash tower and then entering the top of the atmospheric pressure mash tower; (2) the atmospheric beer still wine steam goes upward to enter a negative pressure beer still reboiler to heat the negative pressure beer still, and the condensed crude alcohol enters a crude wine tank; (3) preheating crude alcohol in a crude alcohol tank, and then feeding the preheated crude alcohol into the lower part of a rectifying tower, wherein alcohol steam with the concentration of over 95% (v/v) in the rectifying tower enters a membrane dehydration device for dehydration through an alcohol gas superheater; (4) and (3) feeding the fuel ethanol steam dehydrated by the membrane dehydration device into a normal pressure mash tower reboiler II to heat the normal pressure mash tower, and condensing and cooling to obtain a fuel ethanol finished product. Simple process equipment, low raw material cost, energy conservation, consumption reduction and emission reduction.
Description
Technical Field
The invention relates to the technical field of ethanol production, in particular to a process and a system for producing fuel ethanol by using double-coarse single-fine three-tower distillation low-concentration fermented mash.
Background
At present, domestic fuel ethanol raw materials mainly comprise corn or cassava, the alcohol concentration of fermented mash generally reaches more than 12%, particularly, the alcohol concentration of the fermented mash is up to 16% when thick mash fermentation is widely popularized in the corn alcohol industry in recent years, and the alcohol concentration of the fermented mash at abroad reaches more than 18%. The high-concentration fermented mash lays a solid foundation for energy conservation and consumption reduction of fuel ethanol production, so that the existing distillation process and distillation equipment are mainly used for producing the fuel ethanol from the high-concentration fermented mash.
At present, in order to realize energy conservation, consumption reduction and emission reduction, researches on the preparation of fuel ethanol by taking straws and tail gas of the steel industry as raw materials are vigorously carried out, and the cost of the raw materials can be greatly reduced by preparing the fuel ethanol by taking the straws and the tail gas of the steel industry as the raw materials. The alcohol concentration of the fermented mash for producing the fuel ethanol by taking the straws and the steel industrial waste gas as raw materials is lower, the alcohol concentration of the fermented mash is about 5 percent generally, a distillation process and a distillation device aiming at producing the fuel ethanol by taking the straws and the steel industrial tail gas as the raw materials do not exist at present, the distillation process and the distillation device are complex and have higher cost at present, the fuel ethanol is produced mainly aiming at the fermented mash with high concentration, and if the fuel ethanol is produced by applying the fermented mash with low concentration, the purposes of energy conservation and consumption reduction are not met. Therefore, a distillation process and a distillation device which have simple process and low cost and aim at producing fuel ethanol by taking straws and tail gas of the steel industry as raw materials are urgently needed.
Disclosure of Invention
In view of the above-mentioned deficiencies of the prior art, it is an object of the present invention to provide a process and system for producing fuel ethanol using a double coarse single fine three-column distillation low concentration beer.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect of the invention, there is provided a process for producing fuel ethanol using a double coarse single fine three column distillation of low strength beer, the process comprising the steps of:
(1) fermented mature mash with the concentration of below 8% (v/v) is preheated to 45 ℃ by a mash primary preheater, preheated to 55 ℃ by a mash secondary preheater and preheated to 65 ℃ by a mash tertiary preheater and then fed into the top of a degassing section, carbon dioxide and part of low-boiling impurities in the mature mash are separated from the fermented mash under the action of negative pressure of the degassing section, the degassed fermented mash enters the bottom of the degassing section, part of the mash flows into a negative pressure mash tower through a gravity flow pipeline, and the rest of the fermented mash enters the top of an atmospheric pressure mash tower after being preheated by a feeding preheater of the atmospheric pressure mash tower;
(2) degassed mash entering from the top of the atmospheric pressure mash tower enters the tower, descends in the atmospheric pressure mash tower and is heated by steam rising from the bottom of the tower at the same time, and wine steam ascends to be separated from waste mash; discharging waste mash at the bottom of the normal pressure mash tower to a normal pressure mash tower feeding preheater, preheating degassed mash, and then feeding the preheated mash into a negative pressure mash tower kettle for flash evaporation; the atmospheric beer still wine steam goes upward to enter a negative pressure beer still reboiler to heat the negative pressure beer still, and the condensed crude alcohol enters a crude wine tank;
(3) preheating crude alcohol from a crude alcohol tank, then feeding the preheated crude alcohol into the lower part of a rectifying tower, gradually concentrating the alcohol after the preheated crude alcohol enters the rectifying tower until the alcohol concentration at the top of the rectifying tower reaches more than 95% (v/v), extracting alcohol vapor with the alcohol content of more than 95% (v/v) from a vapor phase at the top of the rectifying tower, feeding the alcohol vapor into a membrane dehydration device through an alcohol vapor superheater for dehydration, and condensing the rest alcohol vapor in a normal pressure mash tower reboiler I and then completely refluxing to the rectifying tower;
(4) and (3) feeding the fuel ethanol steam dehydrated by the membrane dehydration device into a normal pressure mash tower reboiler II to heat the normal pressure mash tower, condensing and cooling by a finished product cooler to obtain a finished product of the fuel ethanol.
Preferably, in the step (1), the heat is supplied to the primary mash preheater while the wine vapor at the top of the degassing section is condensed; the liquor steam at the top of the negative pressure mash tower is condensed and simultaneously supplies heat to the mash secondary preheater;
preferably, in the step (1), the wine tank at the bottom of the negative pressure mash tower enters the mash three-stage preheater for condensation and then enters the wine tank treatment system, and the wine tank at the bottom of the negative pressure mash tower supplies heat to the mash three-stage preheater while condensing.
Preferably, in the step (1), the miscellaneous coarse wine vapor at the top of the degassing section sequentially enters a mash primary preheater and a degassing section condenser set for condensation, and the condensate enters a coarse wine tank; the degassed mash is heated by steam rising from the bottom of the negative pressure mash tower while descending from the degassing section to the negative pressure mash tower, wine steam ascends to be separated from waste mash, and the waste mash is discharged from the bottom of the negative pressure mash tower and sent to a vinasse treatment system for treatment.
Preferably, in the step (1), after the negative pressure beer vapor rises, part of the negative pressure beer vapor enters the bottom of the degassing section, the rest of the crude beer vapor sequentially enters the beer liquid secondary preheater and the negative pressure beer tower condenser group for condensation, the condensate enters the crude beer tank, and the uncondensed impurity-containing gas is discharged through the distillation vacuum pump.
Preferably, in the step (1), 47% of mash flowing into the negative pressure mash tower from the flow pipeline and 53% of mash entering the top of the atmospheric mash tower after being preheated by the feeding preheater of the atmospheric mash tower are obtained.
Preferably, the heating mode of the negative pressure mash tower is as follows: the tower top steam of the atmospheric beer still heats the negative pressure beer still through a negative pressure beer still reboiler; the working pressure of the negative pressure mash tower is-0.07 MPa to-0.055 MPa, the bottom temperature of the negative pressure mash tower is 80 ℃, the top temperature of the negative pressure mash tower is 68 ℃, and the top temperature of the degassing section is 65 ℃.
Preferably, the atmospheric beer still works under normal pressure, and the heating mode of the atmospheric beer still is as follows: alcohol steam at the top of the rectifying tower is heated to the atmospheric beer still through an atmospheric beer still reboiler I; the fuel ethanol steam dehydrated by the membrane dehydration device is heated in the atmospheric beer still through an atmospheric beer still reboiler II; the bottom operating temperature of the atmospheric beer still was 105 deg.C and the top temperature was 99 deg.C.
Preferably, in the step (3), the crude alcohol is preheated by a primary crude alcohol preheater and a secondary crude alcohol preheater.
Preferably, in the step (3), the alcohol is gradually concentrated until the alcohol concentration at the top of the tower reaches more than 95% (v/v), middle-grade impurities (fusel oil) are retained on a plurality of layers of plates above a feeding plate, and the middle-grade impurities (fusel oil) are extracted, cooled and then enter a fusel oil separator to separate fusel oil;
preferably, in the step (3), the waste hot water at the bottom of the rectifying tower enters a primary crude alcohol preheater to preheat crude alcohol and then enters a sewage treatment system.
Preferably, the rectifying tower works under positive pressure, the working pressure of the rectifying tower is 0.3MPa, and the heating mode of the rectifying tower is as follows: fresh steam is used for heating the rectifying tower through a rectifying tower reboiler, the operation temperature of the bottom of the rectifying tower is 146 ℃, and the top temperature of the rectifying tower is 118 ℃.
In a second aspect of the invention, a double-coarse single-fine three-tower system adopted by the process is provided, which comprises a mash preheater, a degassing section, a negative pressure mash tower, an atmospheric mash tower and a rectifying tower; the mash preheater comprises a mash primary preheater, a mash secondary preheater and a mash tertiary preheater which are sequentially connected in series, and the outlet end of the mash tertiary preheater is connected with the inlet end of the degassing section through a pipeline;
the outlet end of the degassing section is connected with the negative pressure beer still through a pipeline, the outlet end of the degassing section is connected with the top of the normal pressure beer still after being fed into the preheater through the pipeline and the normal pressure beer still, and the outlet end of the normal pressure beer still is connected with the coarse wine tank after passing through the negative pressure beer still reboiler through the pipeline; the outlet end of the bottom of the atmospheric pressure mash tower is connected with the bottom of the negative pressure mash tower after being fed into the preheater of the atmospheric pressure mash tower through a pipeline;
the outlet end of the crude wine tank is connected with the rectifying tower after passing through the crude alcohol preheater through a pipeline; the rectifying tower and an atmospheric beer still reboiler I form a closed loop through a pipeline; the outlet end of the rectifying tower is connected with a membrane dehydration device through a heat exchanger by a pipeline, the outlet end of the membrane dehydration device is connected with a finished product cooler by a pipeline constant pressure beer still reboiler II, and the constant pressure beer still reboiler II forms a closed loop with the constant pressure beer still by a pipeline; the outlet end of the membrane dehydration device is also connected with a waterless vacuum pump through a desorption condenser group by a pipeline, and the outlet end of the desorption condenser group is connected with the crude wine tank by a pipeline.
Preferably, the outlet end of the degassing section is sequentially connected with the mash primary preheater and the degassing section condenser set through pipelines, the outlet end of the degassing section condenser set is respectively connected with the coarse wine tank and the distillation vacuum pump through pipelines, the outlet end of the negative pressure mash tower is sequentially connected with the mash secondary preheater and the negative pressure mash tower condenser set through pipelines, and the outlet end of the negative pressure mash tower condenser set is respectively connected with the coarse wine tank and the distillation vacuum pump through pipelines; the negative pressure beer tower reboiler forms a closed loop with the negative pressure beer tower through a pipeline; the outlet end of the negative pressure mash tower is sequentially connected with the mash three-stage preheater and the vinasse treatment system through pipelines.
Preferably, the crude alcohol preheater comprises a first-stage crude alcohol preheater and a second-stage crude alcohol preheater which are sequentially connected in series;
preferably, the outlet end of the rectifying tower is connected with the fusel oil separator through a pipeline, and is also connected with a sewage treatment system through a primary crude alcohol preheater through a pipeline;
preferably, the rectifying tower and a rectifying tower reboiler form a closed loop through a pipeline, and the outlet end of the rectifying tower reboiler is connected with the boiler after sequentially passing through a condensation water tank and a secondary crude alcohol preheater through pipelines;
preferably, the membrane dehydration device comprises a plurality of shell-and-tube membrane structures connected in series, each shell-and-tube membrane structure comprises a shell and an inner tube positioned inside the shell, and the inner tube comprises a ceramic tube and a molecular sieve membrane covering the outer surface of the ceramic tube; the space between the outer shell and the inner tube is a shell pass, and the space inside the inner tube is a tube pass. And (2) pumping negative pressure on the tube pass, introducing alcohol steam into the shell pass, wherein after the alcohol steam passes through the membrane dehydration device, the moisture in the finished product can reach below 0.5%, most of the moisture and a small amount of ethanol permeate the inner tube, and the water enters the desorption condenser through the tube pass to be condensed and then enters the distillation section for recovery.
The invention has the beneficial effects that:
1. the process takes the straws and the tail gas of the steel industry as the raw materials to prepare the fuel ethanol, has simple process equipment and low cost of the raw materials, and can achieve the purposes of energy conservation, consumption reduction and emission reduction;
2. the process is suitable for fermented mash which takes straws and steel industrial tail gas as raw materials and has the fermentation concentration of below 8% (v/v), and the concentration of the produced fuel ethanol is above 95% (v/v) by controlling the trend of mash and steam and controlling the temperature and the pressure of a negative pressure mash tower, a normal pressure mash tower and a rectifying tower;
3. the distillation section of the process device adopts a double-coarse tower and single-fine tower triple-effect distillation process, one tower enters steam, and three towers work, so that the consumption in the distillation process is reduced to the maximum extent;
4. compared with the traditional fuel ethanol distillation process, the temperature of the distiller's grains at the bottom of the coarse distillation tower (normal pressure beer still) is reduced from 120 ℃ to 105 ℃, and the coking of materials is avoided after the temperature is reduced, so that the equipment blockage is avoided, the shutdown and the cleaning are not needed, and the working efficiency is improved.
5. The steam consumption of the whole process is not more than 1.0 ton per ton of fuel ethanol; the membrane dehydration is a continuous process, the working pressure is stable, no influence is caused to distillation, after the alcohol vapor is subjected to membrane dehydration, the moisture content in a finished product can reach below 0.5 percent, most of the moisture and a small amount of ethanol permeate through a membrane tube, and the alcohol vapor enters a desorption condenser set through a pipeline to be condensed and then enters a distillation working section for recovery; the light wine produced by membrane dehydration is less, the alcohol amount required to be distilled and recovered is not more than 1% of the product amount, and the steam consumption can be reduced; the fuel ethanol steam after membrane dehydration can be returned to the distillation section to be continuously used as a heat source of the distillation tower, thereby further reducing the steam consumption.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic cross-sectional structural view of a shell-and-tube membrane structure of the present invention;
in the figure: 1. a degassing section, 2, a negative pressure mash tower, 3, an atmospheric mash tower, 4, a rectifying tower, 5, a mash primary preheater, 6, a mash secondary preheater, 7, a mash tertiary preheater, 8, a degassing section condenser group, 9, a crude alcohol tank, 10, a distillation vacuum pump, 11, a negative pressure mash tower condenser group, 12, an atmospheric mash tower feeding preheater, 13, a negative pressure mash tower reboiler, 14, a vinasse treatment system, 15, a primary crude alcohol preheater, 16, a secondary crude alcohol preheater, 17, a fusel oil separator, 18, a water-free vacuum pump, 19, a sewage treatment system, 20, an atmospheric mash tower reboiler I, 21, a fine tower reboiler, 22, a condensation water tank, 23, a boiler room, 24, a wine gas superheater, 25, a membrane dehydration device, 26, an atmospheric pressure tower II, 27, a finished product cooler, 28, a desorption condenser group, 251, a shell, 252, and a ceramic pipe, 253. 254, shell pass, 255 and tube pass.
Detailed Description
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
In order to make the technical solutions of the present application more clearly understood by those skilled in the art, the technical solutions of the present application will be described in detail below with reference to specific embodiments.
The system for producing fuel ethanol by distilling low-concentration fermented mash by using double-coarse single-fine three-tower distillation comprises a mash preheater, a degassing section 1, a negative pressure mash tower 2, a normal pressure mash tower 3 and a rectifying tower 4. The mash preheater comprises a mash primary preheater 5, a mash secondary preheater 6 and a mash tertiary preheater 7 which are sequentially connected in series. The outlet end of the mash tertiary preheater 7 is connected with the inlet end of the degassing section 1 through a pipeline, and fermented mature mash enters the degassing section 1 after being preheated by the mash primary preheater 5, the mash secondary preheater 6 and the mash tertiary preheater 7 in sequence. The outlet end of the degassing section 1 is sequentially connected with a mash primary preheater 5 and a degassing section condenser group 8 through pipelines, the outlet end of the degassing section condenser group 8 is respectively connected with a coarse wine tank 9 and a distillation vacuum pump 10 through pipelines, the outlet end of the negative pressure mash tower 2 is sequentially connected with a mash secondary preheater 6 and a negative pressure mash tower condenser group 11 through pipelines, and the outlet end of the negative pressure mash tower condenser group 11 is respectively connected with the coarse wine tank 9 and the distillation vacuum pump 10 through pipelines.
The outlet end of the degassing section 1 is connected with the negative pressure beer still 2 through a pipeline, the outlet end of the degassing section 1 is connected with the top of the normal pressure beer still 3 after passing through a normal pressure beer still feeding preheater 12 through a pipeline, and the outlet end of the normal pressure beer still 3 is connected with the coarse wine tank 9 after passing through a negative pressure beer still reboiler 13 through a pipeline. The negative pressure beer still reboiler 13 forms a closed loop with the negative pressure beer still 2 through a pipeline, and the outlet end of the negative pressure beer still 2 is sequentially connected with the beer liquid three-stage preheater 7 and the vinasse treatment system 14 through pipelines. The outlet end of the tower bottom of the atmospheric beer still 3 is connected with the tower bottom of the negative pressure beer still 2 after passing through a pipeline and a feeding preheater 12 of the atmospheric beer still.
The outlet end of the coarse wine tank 9 is connected with the rectifying tower 4 after passing through a coarse alcohol preheater through a pipeline, and the coarse alcohol preheater comprises a first-stage coarse alcohol preheater 15 and a second-stage coarse alcohol preheater 16 which are sequentially connected in series.
The outlet end of the rectifying tower 4 is connected with a fusel oil separator 17 through a pipeline, and the outlet end of the rectifying tower 4 is also connected with a sewage treatment system 19 through a first-stage crude alcohol preheater 15 through a pipeline.
Rectifying column 4 forms closed circuit through pipeline and ordinary pressure beer wine tower reboiler I20, ordinary pressure beer wine tower reboiler I20 still forms closed circuit through pipeline and ordinary pressure beer wine tower 3, and rectifying column 4 forms closed circuit through pipeline and rectifying column reboiler 21, and the exit end of rectifying column reboiler 21 is connected with boiler room 23 through the pipeline behind condensation water tank 22, the thick alcohol preheater 16 of second grade in proper order.
The outlet end of the rectifying tower 4 is connected with a membrane dewatering device 25 through a heat device 24 by a pipeline, the outlet end of the membrane dewatering device 25 is connected with a finished product cooler 27 through a pipeline constant pressure beer still reboiler II 26, and the constant pressure beer still reboiler II 26 forms a closed loop with the constant pressure beer still 3 by a pipeline. The outlet end of the membrane dehydration device 25 is also connected with the anhydrous vacuum pump 18 through a desorption condenser group 28 by a pipeline, and the outlet end of the desorption condenser group 28 is connected with the crude wine tank 9 by a pipeline.
The membrane dewatering device 25 comprises a plurality of shell-and-tube membrane structures connected in series, as shown in fig. 2, each of which comprises a housing 251 and an inner tube located inside the housing 251, the inner tube comprising a ceramic tube 252 and a molecular sieve membrane 253 covering the outer surface of the ceramic tube 252. The space between the outer shell 251 and the inner tube is a shell pass 254, the inner space of the inner tube is a tube pass 255, negative pressure is pumped in the tube pass 255, alcohol steam is introduced into the shell pass 254, after the alcohol steam passes through the membrane dehydration device 25, the moisture in the finished product can reach below 0.5%, most of the moisture and a small amount of ethanol penetrate through the inner tube, and the water enters the desorption condenser group 28 through the tube pass 255 to be condensed and then enters the distillation section for recovery.
The heating mode of each tower of the invention is as follows:
the rectifying tower 4 adopts raw steam to indirectly heat through a rectifying tower reboiler 21;
a part of the wine vapor at the top of the rectifying tower 4 is supplied to the atmospheric beer still 3 through an atmospheric beer still reboiler I20;
the other part of the wine vapor at the top of the rectifying tower 4 is superheated by a heater 24 and then is subjected to a membrane removal dehydration device 25, and the dehydrated fuel ethanol vapor is supplied to the atmospheric beer still 3 through an atmospheric beer still reboiler II 26;
the wine steam at the top of the atmospheric beer still 3 is supplied to the negative pressure beer still 2 through the negative pressure beer still reboiler 13.
The process method for producing the fuel ethanol by using the double-coarse single-fine three-tower distillation low-concentration fermented mash comprises the following steps:
(1) fermented mature mash with the concentration of below 8% (v/v) is sequentially preheated to about 45 ℃ by a mash primary preheater 5, preheated to about 55 ℃ by a mash secondary preheater 6 and preheated to about 65 ℃ by a mash tertiary preheater 7, then fed into the top of a degassing section 1, carbon dioxide and part of low-boiling impurities in the mature mash are separated from the fermented mash under the action of negative pressure of the degassing section 1, impurity-containing crude wine vapor at the top of the degassing section 1 sequentially enters the mash primary preheater 5 and a degassing section condenser group 8 for condensation, condensate enters a crude wine tank 9, and heat is supplied to the mash primary preheater 5 while wine vapor at the top of the degassing section 1 is condensed; after the fermented mash without gas enters the bottom of the degassing section 1, part of mash (about 47%) flows into the negative pressure mash tower 2 through a gravity flow pipeline, and the rest (about 53%) enters the top of the normal pressure mash tower 3 after being preheated by the normal pressure mash tower feeding preheater 12;
the degassed mash descends from the degassing section 1 to the negative pressure mash tower 2 and is heated by steam ascending from the bottom of the negative pressure mash tower 2, and wine steam ascends to be separated from waste mash; the waste mash is discharged from the bottom of the negative pressure mash tower 2 and sent to a vinasse treatment system 14 for treatment; after the wine vapor of the negative pressure mash tower 2 rises, part of the wine vapor enters the bottom of the degassing section 1, the rest of the crude wine vapor enters the mash secondary preheater 6 and the negative pressure mash tower condenser set 11 in sequence for condensation, the condensate enters the crude wine tank 9, the uncondensed impurity-containing gas is discharged through the distillation vacuum pump 10, and the wine vapor at the top of the negative pressure mash tower 2 is condensed and simultaneously supplies heat to the mash secondary preheater 6; the wine tank at the bottom of the negative pressure mash tower 2 enters the mash tertiary preheater 7 for condensation and then enters the wine tank treatment system, and the wine tank at the bottom of the negative pressure mash tower 2 supplies heat to the mash tertiary preheater 7 while condensing.
The heating mode of the negative pressure mash tower 2 is as follows: the steam at the top of the atmospheric beer still 3 heats the negative pressure beer still 2 through a negative pressure beer still reboiler 13; the working pressure of the negative pressure mash tower 2 is-0.07 MPa to-0.055 MPa, the bottom temperature of the negative pressure mash tower 2 is 80 ℃, the top temperature is 68 ℃, and the top temperature of the degassing section 1 is 65 ℃.
(2) Degassed mash entering from the top of the atmospheric pressure mash tower enters the tower, descends in the atmospheric pressure mash tower 3 and is heated by steam rising from the bottom of the tower at the same time, and wine steam ascends to be separated from waste mash; the waste mash is discharged to a feed preheater 12 of the normal pressure mash tower at the bottom of the normal pressure mash tower 3, and the preheated and degassed mash enters a tower kettle of the negative pressure mash tower 2 for flash evaporation; the wine steam in the normal pressure beer still 3 goes upwards to enter a negative pressure beer still reboiler 13 to heat the negative pressure beer still 2, and the condensed crude alcohol enters a crude wine tank 9.
The atmospheric beer still 3 is operated under normal pressure, and the heating mode of the atmospheric beer still 3 is as follows: alcohol steam at the top of the rectifying tower 4 heats the atmospheric beer still 3 through an atmospheric beer still reboiler I20; the fuel ethanol vapor from membrane dehydration unit 25 after dehydration is passed through atmospheric beer column reboiler II 26 to heat atmospheric beer column 3. The bottom operating temperature of the atmospheric beer still 3 is 105 ℃ and the top temperature is 99 ℃.
(3) Crude alcohol from a crude alcohol tank 9 enters the lower part of a rectifying tower 4 after being preheated by a primary crude alcohol preheater 15 and a secondary crude alcohol preheater 16, the alcohol is gradually concentrated after entering the rectifying tower 4 until the alcohol concentration at the top of the tower reaches more than 95% (v/v), middle-grade impurities (fusel oil) are retained on a plurality of layers of plates above a feeding plate, and the middle-grade impurities (fusel oil) are extracted and cooled and then enter a fusel oil separator 17 to separate fusel oil. Alcohol vapor with alcohol degree of more than 95% (v/v) extracted from the vapor phase at the top of the rectifying tower 4 enters a membrane dehydration device 25 through an alcohol gas superheater 24 for dehydration, and the rest alcohol vapor is condensed by an atmospheric beer reboiler I20 and then completely reflows to the rectifying tower 4. The waste hot water in the tower bottom of the rectifying tower 4 enters a primary crude alcohol preheater 15 to preheat crude alcohol and then enters a sewage treatment system 19.
The rectifying tower 4 works under positive pressure, the working pressure is 0.3MPa, and the heating mode of the rectifying tower 4 is as follows: the fresh steam heats the rectifying tower 4 through a rectifying tower reboiler 21, the operation temperature of the bottom of the rectifying tower 4 is 146 ℃, and the top temperature is 118 ℃.
(4) Alcohol steam with the concentration of more than 95% (v/v) from the top of the rectifying tower 4 is superheated by a heater 24 and then enters a membrane dehydration device 25 for dehydration, the dehydrated fuel ethanol steam enters an atmospheric beer tower reboiler II 26 to heat the atmospheric beer tower 3, and the condensed fuel ethanol steam is cooled by a finished product cooler 27 to obtain a fuel ethanol finished product.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. The process for producing the fuel ethanol by using the double-coarse single-fine three-tower distillation low-concentration fermented mash is characterized by comprising the following steps of:
(1) fermented mature mash with the concentration of below 8% (v/v) is sequentially preheated to 45 ℃ by a mash primary preheater (5), preheated to 55 ℃ by a mash secondary preheater (6), preheated to 65 ℃ by a mash tertiary preheater (7) and then fed to the top of a degassing section (1), carbon dioxide and part of low-boiling impurities in the mature mash are separated from the fermented mash under the negative pressure action of the degassing section (1), the degassed fermented mash enters the bottom of the degassing section (1), part of the mash flows into a negative pressure mash tower (2) through a gravity flow pipeline, and the rest of the fermented mash enters the top of an atmospheric pressure mash tower (3) after being preheated by a normal pressure mash tower feeding preheater (12);
(2) degassed mash entering from the top of the atmospheric pressure mash tower enters the tower, descends in the atmospheric pressure mash tower (3) and is heated by steam rising from the bottom of the tower at the same time, and wine steam ascends to be separated from waste mash; the waste mash is discharged to a feed preheater (12) of the normal pressure mash tower at the bottom of the normal pressure mash tower (3), and the preheated and degassed mash enters a tower kettle of the negative pressure mash tower (2) for flash evaporation; the wine steam in the normal pressure beer still (3) goes upwards to enter a negative pressure beer still reboiler (13) to heat the negative pressure beer still (2), and the condensed crude alcohol enters a crude wine tank (9);
(3) preheating crude alcohol from a crude alcohol tank (9), then feeding the preheated crude alcohol into the lower part of a rectifying tower (4), feeding the preheated crude alcohol into the rectifying tower (4), then gradually concentrating the alcohol until the alcohol concentration at the top of the rectifying tower reaches more than 95% (v/v), extracting alcohol steam with the alcohol content of more than 95% (v/v) from the vapor phase at the top of the rectifying tower (4), feeding the alcohol steam into a membrane dehydration device (25) through an alcohol gas superheater (24) for dehydration, and condensing the rest alcohol steam through an atmospheric mash tower reboiler I (20) and then completely refluxing to the rectifying tower (4);
(4) the fuel ethanol steam dehydrated by the membrane dehydration device (25) enters an atmospheric beer still reboiler II (26) to heat the atmospheric beer still (3), and is cooled by a finished product cooler (27) after being condensed to obtain a finished product of the fuel ethanol.
2. The process according to claim 1, characterized in that: in the step (1), the miscellaneous coarse wine vapor at the top of the degassing section (1) sequentially enters a mash primary preheater (5) and a degassing section condenser group (8) for condensation, and the condensate enters a coarse wine tank (9); the degassed mash descends from the degassing section (1) to the negative pressure mash tower (2) and is heated by steam ascending at the bottom of the negative pressure mash tower (2), wine steam ascends to be separated from waste mash, the waste mash is discharged at the bottom of the negative pressure mash tower (2) and is sent to a vinasse treatment system (14) for treatment.
3. The process according to claim 1, characterized in that: in the step (1), after the wine vapor of the negative pressure mash tower (2) rises, part of the wine vapor enters the bottom of the degassing section (1), the rest of the crude wine vapor enters a mash secondary preheater (6) and a negative pressure mash tower condenser group (11) in sequence for condensation, the condensate enters a crude wine tank (9), and the uncondensed impurity-containing gas is discharged through a distillation vacuum pump (10).
4. The process according to claim 1, characterized in that: in the step (1), 47% of mash flowing into the negative pressure mash tower (2) from the flow pipeline, and 53% of mash entering the top of the normal pressure mash tower (3) after being preheated by the normal pressure mash tower feeding preheater (12).
5. The process according to claim 1, characterized in that: the heating mode of the negative pressure mash tower (2) is as follows: the tower top steam of the atmospheric beer still (3) heats the negative pressure beer still (2) through a negative pressure beer still reboiler (13); the working pressure of the negative pressure beer still (2) is-0.07 MPa to-0.055 MPa, the bottom temperature of the negative pressure beer still (2) is 80 ℃, the top temperature is 68 ℃, and the top temperature of the degassing section (1) is 65 ℃.
6. The process according to claim 1, characterized in that: the normal pressure beer well tower (3) works under normal pressure, and the heating mode of the normal pressure beer well tower (3) is as follows: alcohol steam at the top of the rectifying tower (4) heats the atmospheric beer still (3) through an atmospheric beer still reboiler I (20); the fuel ethanol steam dehydrated from the membrane dehydration device (25) heats the atmospheric beer tower (3) through an atmospheric beer tower reboiler II (26); the operation temperature of the bottom of the atmospheric beer still (3) is 105 ℃, and the top temperature is 99 ℃.
7. The process according to claim 1, characterized in that: the rectifying tower (4) works under positive pressure, the working pressure of the rectifying tower is 0.3MPa, and the heating mode of the rectifying tower (4) is as follows: the fresh steam heats the rectifying tower (4) through a rectifying tower reboiler (21), the operation temperature of the bottom of the rectifying tower (4) is 146 ℃, and the top temperature is 118 ℃.
8. The double coarse single fine three-tower system adopted by the process of any one of claims 1 to 7, which is characterized in that: comprises a mash preheater, a degassing section (1), a negative pressure mash tower (2), a normal pressure mash tower (3) and a rectifying tower (4); the mash preheater comprises a mash primary preheater (5), a mash secondary preheater (6) and a mash tertiary preheater (7) which are sequentially connected in series, and the outlet end of the mash tertiary preheater (7) is connected with the inlet end of the degassing section (1) through a pipeline;
the outlet end of the degassing section (1) is connected with the negative pressure beer still (2) through a pipeline, the outlet end of the degassing section (1) is connected with the top of the normal pressure beer still (3) after passing through a normal pressure beer still feeding preheater (12) through a pipeline, and the outlet end of the normal pressure beer still (3) is connected with the coarse wine tank (9) after passing through a negative pressure beer still reboiler (13) through a pipeline; the outlet end of the bottom of the atmospheric pressure mash tower (3) is connected with the tower kettle of the negative pressure mash tower (2) after passing through a feed preheater (12) of the atmospheric pressure mash tower through a pipeline;
the outlet end of the crude wine tank (9) is connected with the rectifying tower (4) after passing through a crude alcohol preheater through a pipeline; the rectifying tower (4) and an atmospheric beer still reboiler I (20) form a closed loop through a pipeline, and the atmospheric beer still reboiler I (20) and the atmospheric beer still (3) form a closed loop through a pipeline; the outlet end of the rectifying tower (4) is connected with a membrane dehydration device (25) through a heat device (24) by a pipeline, the outlet end of the membrane dehydration device (25) is connected with a finished product cooler (27) through a normal pressure beer still reboiler II (26) by a pipeline, and the normal pressure beer still reboiler II (26) forms a closed loop with the normal pressure beer still (3) by a pipeline; the outlet end of the membrane dehydration device (25) is also connected with a waterless vacuum pump (18) through a desorption condenser group (28) by a pipeline, and the outlet end of the desorption condenser group (28) is connected with the crude wine tank (9) by a pipeline.
9. The double roughing single finishing three column system of claim 8 wherein: the outlet end of the degassing section (1) is sequentially connected with a mash primary preheater (5) and a degassing section condenser set (8) through pipelines, the outlet end of the degassing section condenser set (8) is respectively connected with a coarse wine tank (9) and a distillation vacuum pump (10) through pipelines, the outlet end of the negative pressure mash tower (2) is sequentially connected with a mash secondary preheater (6) and a negative pressure mash tower condenser set (11) through pipelines, and the outlet end of the negative pressure mash tower condenser set (11) is respectively connected with the coarse wine tank (9) and the distillation vacuum pump (10) through pipelines; the negative pressure beer still reboiler (13) forms a closed loop with the negative pressure beer still (2) through a pipeline; the outlet end of the negative pressure mash tower (2) is sequentially connected with a mash three-stage preheater (7) and a vinasse treatment system (14) through pipelines.
10. The double roughing single finishing three column system of claim 8 wherein: the membrane dehydration device (25) comprises a plurality of shell-and-tube membrane structures connected in series, each shell-and-tube membrane structure comprises a shell (251) and an inner tube positioned inside the shell (251), the inner tube comprises a ceramic tube (252) and a molecular sieve membrane (253) coated on the outer surface of the ceramic tube (252); the space between the outer shell (251) and the inner tube is a shell pass (254), and the inner space of the inner tube is a tube pass (255).
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