A fuel ethanol distillation method and device using secondary steam from a superheated steam fluidized bed dryer as part of the heat source

Abstract

The invention discloses a fuel ethanol distillation method and device using secondary steam of a superheated steam fluidized bed dryer as a partial heat source, and the device comprises a negative pressure mash tower I, a negative pressure mash tower II, a low-pressure fine tower, a high-pressure fine tower, a molecular sieve adsorber group and a superheated steam fluidized bed dryer. The fermented mature mash enters the degassing section, a part of the fermented mash with gas removed enters the negative pressure mash tower I, and the other part enters the negative pressure mash tower II, and is heated by steam to obtain crude alcohol. The crude alcohol enters the low-pressure fine tower for further distillation after acid removal and dealdehyde removal in the acid removal section, and the light alcohol at the bottom of the tower and the alcohol after distillation enter the middle and lower part and the top of the high-pressure fine tower respectively. After distillation and concentration in the high-pressure fine tower, the light alcohol enters the molecular sieve attachment group together with the concentrated alcohol sent into the low-pressure fine tower for dehydration to obtain fuel ethanol. The negative pressure mash tower II in the device of the invention directly uses the secondary steam of the superheated steam fluidized bed dryer as a heat source, thereby saving steam consumption.

Description

Technical Field

[0001] The invention relates to the technical field of alcohol production technology, and in particular to a fuel ethanol distillation method and device using secondary steam from a superheated steam fluidized bed dryer as a partial heat source. Background Art

[0002] At present, domestic fuel ethanol production is mainly based on three-tower three-effect distillation + molecular sieve dehydration process. This process was first introduced by Jilin Fuel Alcohol Co., Ltd. from Austria's Vogelbusch Company with an annual production capacity of 300,000 tons of fuel ethanol. The construction was officially started in 2001 and put into production in 2003. After that, domestic alcohol equipment manufacturers digested and absorbed this process and gradually realized localization. The main disadvantages of this equipment are high combined tower operating temperature (up to about 120°C), easy coking and carbonization of materials, poor feed color, and easy clogging of equipment. In the next few years, new devices will generally not adopt this process, and existing devices will also be upgraded and transformed.

[0003] The four-tower four-effect distillation + molecular sieve dehydration process device developed by the applicant has been successfully used in the production of fuel ethanol. This process device reduces the operating temperature of the mash tower from the original 120°C to about 108°C, the material is not easy to coke and carbonize, the equipment is not easy to clog, and the feed color is greatly improved (see patent application number 201810719237.3). However, compared with the negative pressure operation of the mash tower, the feed quality and color of this process device are still inferior.

[0004] With the promotion of concentrated mash fermentation, multi-effect evaporation and MVR evaporation technology, the low-pressure secondary steam generated in the drying section is still in large surplus after being used for the evaporation of the clear liquid. However, this surplus steam contains a large amount of air, has low grade and low temperature (generally around 80°C), and cannot provide heat for the distillation section. It can only be discharged, causing heat waste and environmental pollution.

[0005] The superheated steam fluidized bed dryer is a device that uses superheated steam to dry distiller's grains. For its structure, please refer to the "Superheated Steam Fluidized Bed Drying Device" (Xiao Zhifeng et al.) published in "Drying Technology and Equipment" Vol. 3, No. 3, 2005. Compared with the tube-type dryer, the superheated steam fluidized bed drying technology does not contain air in the secondary steam generated after drying the feed (the secondary steam generated by the tube-type dryer contains more than 30% air, and the secondary steam utilization rate is low). The secondary steam has a high quality, the steam temperature can reach about 100°C, and the utilization rate is high. After being used in multiple-effect evaporation, the number of multiple-effect evaporation effects can be increased by at least one effect, so that more secondary steam can be used in the distillation section. This part of secondary steam can account for more than 40% of the steam consumption in the distillation section.

[0006] Therefore, it is necessary to develop a new type of fuel ethanol distillation system that can make full use of the secondary steam in the drying section, improve energy utilization, and reduce steam consumption in the distillation section; while utilizing the secondary steam, it can also reduce the operational stability of the negative pressure mash tower, making the protein in the wine lees less likely to denature, the material will not coke and carbonize, and the feed color will be good. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a fuel ethanol distillation method and device using secondary steam from a superheated steam fluidized bed dryer as a partial heat source. The operating temperature of the bottoms of the two negative pressure mash towers is about 80°C, the Maillard reaction is not easy to occur, the protein in the lees is not easy to denature, the material will not coke and carbonize, the feed color is good, the equipment will not coke and clog, and there is no need to stop the machine for cleaning.

[0008] The present invention is achieved through the following technical solutions:

[0009] In a first aspect of the present invention, there is provided a fuel ethanol distillation device using secondary steam from a superheated steam fluidized bed dryer as a partial heat source, comprising a high-pressure refinement tower, the bottom of the high-pressure refinement tower being connected to a high-pressure refinement tower reboiler, the top of the high-pressure refinement tower being connected to the bottom of a low-pressure refinement tower via a low-pressure refinement tower reboiler; the top of the low-pressure refinement tower being connected to the bottom of a negative pressure mash tower I via a negative pressure mash tower I reboiler A; the bottom of a negative pressure mash tower II being connected to a negative pressure mash tower II reboiler, and the negative pressure mash tower II reboiler being connected to a superheated steam fluidized bed dryer;

[0010] A degassing section is provided above the negative pressure mash tower I; the top of the degassing section is connected to the mash preheater, the lower part of the degassing section is connected to the upper part of the negative pressure mash tower I through a pipeline, and the lower part of the degassing section is also connected to the upper part of the negative pressure mash tower II through a pipeline; an acid discharge section is provided above the negative pressure mash tower II, and the acid discharge section is connected to the low-pressure fine tower through a pipeline; the bottom of the low-pressure fine tower is connected to the lower part of the high-pressure fine tower; the top of the high-pressure fine tower is connected to the molecular sieve adsorber group through a superheater; the molecular sieve adsorber group is connected to the finished product cooler through the reboiler B of the negative pressure mash tower I; the reboiler B of the negative pressure mash tower I is connected to the bottom of the negative pressure mash tower I.

[0011] Preferably, the mash preheater includes a first-stage mash preheater; the first-stage mash preheater is connected to a second-stage mash preheater; the second-stage mash preheater is connected to a third-stage mash preheater; and the third-stage mash preheater is connected to the top of the degassing section.

[0012] More preferably, the molecular sieve adsorber group is connected to the finished product cooler in sequence through the negative pressure mash tower I reboiler B and the mash three-stage preheater; the top of the degassing section is connected to the mash two-stage preheater, and the mash two-stage preheater is connected to the degassing section condenser; the acid discharge section is connected to the mash first-stage preheater, and the mash first-stage preheater is connected to the acid discharge section condenser.

[0013] More preferably, one end of the degassing section condenser and one end of the acid discharge section condenser are both connected to the distillation vacuum pump, and the other ends are both connected to the acid discharge section reflux tank; the acid discharge section reflux tank is connected to the upper part of the acid discharge section.

[0014] Preferably, the acid discharge section is connected to the low-pressure finishing tower via a crude alcohol tank and a crude alcohol preheater in sequence.

[0015] More preferably, the molecular sieve adsorber group is connected to the crude alcohol tank via an analytical condenser; the analytical condenser is also connected to a waterless vacuum pump; and the bottom of the high-pressure fine tower is connected to a crude alcohol preheater.

[0016] Preferably, the bottom of the low-pressure refinement tower is connected to the lower part of the high-pressure refinement tower through a high-pressure refinement tower feed preheater; and the high-pressure refinement tower reboiler is connected to the high-pressure refinement tower feed preheater.

[0017] Preferably, the superheated steam fluidized bed dryer is connected to the fan and the superheater in sequence to form a closed loop; the superheated steam fluidized bed dryer is also connected to the wine lees separation system and the clear liquid multiple-effect evaporation system respectively; the wine lees separation system is connected to the clear liquid multiple-effect evaporation system; the bottoms of the negative pressure mash tower I and the negative pressure mash tower II are both connected to the wine lees separation system through pipelines.

[0018] A second aspect of the present invention provides a fuel ethanol distillation method using secondary steam from a superheated steam fluidized bed dryer as a partial heat source, comprising the following steps:

[0019] (1) The fermented mature mash is preheated to about 42° C. in a first-stage mash preheater, to about 55° C. in a second-stage mash preheater, and to about 58° C. in a third-stage mash preheater, and then fed to the top of the degassing section. The carbon dioxide and some low-boiling impurities in the mature mash are separated from the fermented mash under the action of the crude alcohol vapor rising from the negative pressure mash tower I. The impure crude alcohol vapor enters the second-stage mash preheater and the degassing section condenser for condensation, and the uncondensed impure crude alcohol vapor is discharged through a distillation vacuum pump; the condensate enters the reflux tank of the acid discharge section, and the fermented mash with gas removed enters the bottom of the degassing section, and 60-70% of it flows by gravity into the negative pressure mash tower I, and the obtained lees is discharged from the bottom of the negative pressure mash tower I;

[0020] Heating method of negative pressure mash tower I: the top steam of low pressure refinement tower passes through reboiler A of negative pressure mash tower I to heat negative pressure mash tower I; the dehydrated anhydrous alcohol steam passes through reboiler B of negative pressure mash tower I to heat negative pressure mash tower I;

[0021] (2) Another 30-40% of the fermented mash from which gas has been removed flows by gravity into the negative pressure mash tower II, and is heated by the steam rising from the bottom of the tower while descending in the negative pressure mash tower II. The evaporated wine vapor ascends and is separated from the remaining waste mash, and the waste mash is discharged at the bottom of the tower; the wine vapor in the negative pressure mash tower II ascends and enters the bottom of the acid discharge section, and most of the volatile acids and aldehydes in the crude alcohol are discharged through the acid discharge section. The wine vapor rising from the acid discharge section enters the first-level mash preheater and the acid discharge section condenser in turn for condensation, and the uncondensed wine vapor is discharged through a distillation vacuum pump, and the condensate enters the acid discharge section reflux tank and is sent to the top of the acid discharge section. The crude alcohol at the bottom of the acid discharge section flows by gravity into the crude alcohol tank;

[0022] Heating method of negative pressure mash tower II: secondary steam from superheated steam fluidized bed dryer heats negative pressure mash tower II through negative pressure mash tower II reboiler;

[0023] (3) The crude alcohol from the crude alcohol tank is preheated in the crude alcohol preheater and enters the lower part of the low-pressure polishing tower. After entering the tower, part of the alcohol evaporates and undergoes vapor-liquid mass transfer exchange with the reflux liquid at the top of the tower, gradually concentrating until the alcohol vapor at the top of the tower has an alcohol content of more than 95% (v / v). It enters the reboiler A of the negative pressure mash tower I to heat the negative pressure mash tower I, condenses, and then refluxes to the low-pressure polishing tower. The alcohol is then extracted from the low-pressure polishing tower and sent to the top of the high-pressure polishing tower;

[0024] Heating method of low-pressure refinement tower: Alcohol vapor from the top of high-pressure refinement tower heats the low-pressure refinement tower through the reboiler of low-pressure refinement tower;

[0025] (4) The light alcohol at the bottom of the low-pressure refinement tower is preheated in the high-pressure refinement tower feed preheater and then enters the middle of the high-pressure refinement tower. After entering the tower, the alcohol is gradually concentrated until the alcohol content at the top of the tower reaches more than 95% (v / v). The alcohol vapor with an alcohol content of more than 95% (v / v) is extracted from the vapor phase at the top of the high-pressure refinement tower and enters the molecular sieve adsorber group for dehydration. The remaining alcohol vapor in the high-pressure refinement tower is condensed in the low-pressure refinement tower reboiler and then refluxed to the high-pressure refinement tower; the waste hot water in the high-pressure refinement tower is discharged and enters the crude alcohol preheater to preheat the crude alcohol preheater;

[0026] Heating method of high-pressure refinement tower: fresh steam from the boiler room heats the high-pressure refinement tower through the high-pressure refinement tower reboiler;

[0027] (5) The alcohol vapor with an alcohol content of more than 95% (v / v) from the top of the high-pressure fine tower is superheated to 150°C in the superheater and then enters the molecular sieve adsorber group for dehydration. The anhydrous ethanol vapor produced after dehydration enters the negative pressure mash tower I reboiler B for heating. The alcohol vapor is condensed to become anhydrous ethanol, and then preheats the fermented mash through the mash three-stage preheater, and finally cools to room temperature through the finished product cooler; the light wine produced by negative pressure analysis in the analysis condenser enters the crude wine tank;

[0028] (6) The lees at the bottom of negative pressure mash tower I and negative pressure mash tower II are separated by the lees separation system to obtain clear liquid and wet lees. The clear liquid enters the clear liquid multi-effect evaporation system for concentration and evaporation, and the wet lees enter the superheated steam fluidized bed dryer for drying. The secondary steam is extracted by the fan, and then superheated in the superheater and enters the superheated steam fluidized bed dryer for circulation. The superheated steam absorbs the moisture in the lees and becomes saturated steam, thereby drying the lees. Part of the secondary steam generated by the superheated steam fluidized bed dryer is used as the heat source of the clear liquid multi-effect evaporation system, and part of it is used as the heat source of the negative pressure mash tower II. The concentrated slurry generated by the clear liquid multi-effect evaporation system enters the superheated steam fluidized bed dryer and is dried together with the wet lees to obtain DDGS feed.

[0029] Preferably, the mature mash is preheated once while the wine vapor is condensing at the top of the acid discharge section; the mature mash is preheated twice while the wine vapor is condensing at the top of the degassing section; and the mature mash is preheated thrice by the liquid fuel ethanol condensed after dehydration and heating in the negative pressure mash tower.

[0030] Preferably, the bottom operating temperature of negative pressure mash tower I is 80°C, the top temperature is 65°C, and the top temperature of the degassing section is 62°C; the bottom operating temperature of negative pressure mash tower II is 80°C, the top temperature is 65°C, and the top temperature of the acid discharge section is 52°C; the working pressure of the low-pressure rectification tower is 0.1MPa, the bottom operating temperature of the low-pressure rectification tower is 105°C, and the top temperature is 95°C; the working pressure of the high-pressure rectification tower is 0.35MPa, the bottom operating temperature of the high-pressure rectification tower is 150°C, and the top temperature is 120°C. The temperature of the secondary steam generated by the superheated steam fluidized bed is 100°C.

[0031] The beneficial effects of the present invention are:

[0032] (1) The device of the present invention is provided with two negative pressure mash towers, negative pressure mash tower I / II. Negative pressure mash tower I, low pressure fine tower, high pressure fine tower and molecular dehydration system form a three-effect distillation and dehydration system. Negative pressure mash tower II uses the secondary steam of the fluidized bed dryer as an independent heat source, thereby avoiding the influence of fluctuations and fault maintenance of the superheated steam fluidized bed dryer on the distillation.

[0033] (2) The operating temperature at the bottom of the two negative pressure mash towers I / II of the present invention is about 80°C, the Maillard reaction is not easy to occur, the protein in the lees is not easy to denature, the material will not coke and carbonize, the feed color is good, the equipment will not coke and clog, and there is no need to stop the machine for cleaning.

[0034] (3) The present invention adopts a three-effect thermal coupling distillation process, with one tower supplying heat and three towers working. The alcohol vapor at the top of the high-pressure refinement tower serves as the heat source for the low-pressure refinement tower, and the alcohol vapor at the top of the low-pressure refinement tower serves as the heat source for the negative pressure mash tower I. The alcohol vapor is extracted from the vapor phase at the top of the high-pressure refinement tower and enters the molecular sieve adsorber group for adsorption and dehydration. The dehydrated anhydrous ethanol vapor also serves as the heat source for the negative pressure mash tower I.

[0035] (4) The present invention can effectively reduce the acidity of the finished fuel ethanol by arranging a degassing section and an aldehyde removal section on the top of the two negative pressure mash towers I / II, respectively, and extracting alcohol from the side line of the low-pressure fine tower, so as to stabilize the pH value of the finished product to 7-8 and improve the product quality.

[0036] (5) The molecular sieve adsorber group used in the present invention adopts a three-column adsorption and dehydration process, which can analyze a small amount of light wine. The vapor pressure of anhydrous ethanol after adsorption and dehydration is stable, and the heat can be reused.

[0037] (6) The drying section of the present invention adopts a superheated steam fluidized bed dryer, and the secondary steam generated does not contain air and has a high steam quality. Compared with the secondary steam generated by a shell-and-tube dryer (containing more than 30% air), the evaporation effect can be increased by at least one effect, and more secondary steam is surplus and can be used in the distillation system.

[0038] (7) The method of the present invention consumes no more than 1.0 ton of steam for each ton of fuel ethanol produced. Compared with the traditional "three-tower three-effect distillation process device" and "double-crude double-fine four-tower four-effect distillation process technology and device for producing fuel ethanol", it saves more than 20% of steam and 20% of water. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0040] Figure 1 The present invention is a process flow chart for the distillation of fuel ethanol using secondary steam from a superheated steam fluidized bed dryer as part of the heat source.

[0041] In the figure: 1. Negative pressure mash tower I, 2. Negative pressure mash tower II, 3. Low-pressure fine tower, 4. High-pressure fine tower, 5. Molecular sieve adsorber group, 6. Mash first-stage preheater, 7. Mash second-stage preheater, 8. Mash third-stage preheater, 9. Negative pressure mash tower I reboiler A, 10. Negative pressure mash tower I reboiler B, 11. Negative pressure mash tower II reboiler, 12. Crude wine tank, 13. Crude alcohol preheater, 14. Low-pressure fine tower reboiler, 15. High-pressure fine tower reboiler, 16. High-pressure fine tower feed preheater, 17. Superheater, 18. Desorption condenser, 19. Waterless vacuum pump, 20. Finished product cooler, 21. Degassing section condenser, 22. Acid discharge section condenser, 23. Distillation vacuum pump, 24. Acid discharge section reflux tank, 25. Degassing section, 26. Acid discharge section, 27. Superheated steam fluidized bed dryer, 28. Fan, 29. Superheater, 30. Wine lees separation system, 31. Clear liquid multi-effect evaporation system. DETAILED DESCRIPTION

[0042] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0043] In the description of the present invention, it should be noted that the directions or positional relationships indicated by the terms "upper", "lower", "inner", "outer", etc. are generally expressed directions or positional relationships, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0044] As described in the background technology, the existing ethanol distillation equipment mainly has the disadvantages of high combined tower operating temperature (up to about 120°C), easy coking and carbonization of materials, poor feed color, and easy clogging of equipment. Even if a negative pressure mash tower is used in the patent with application number 201810719237.3 (double crude double refined four-tower four-effect energy-saving distillation system for producing fuel ethanol and its use method), the operating temperature of subsequent sections such as normal pressure mash tower and medium pressure refined tower is still too high. Although the color of the feed has been greatly improved, it needs to be further improved. At the same time, the low-pressure secondary steam generated in the drying section has not been effectively utilized. How to make the ethanol distillation device effectively utilize the low-pressure secondary steam generated in the drying section, while solving the problems of poor feed color, Maillard reaction, protein in lees, coking and carbonization of materials, coking and clogging of equipment, and need to stop for cleaning. Based on this, the present invention provides a fuel ethanol distillation method and device using the secondary steam of a superheated steam fluidized bed dryer as a partial heat source.

[0045] A fuel ethanol distillation device using secondary steam from a superheated steam fluidized bed dryer as a partial heat source comprises a high-pressure refinement tower 4, the bottom of which is connected to a high-pressure refinement tower reboiler 15, the top of which is connected to the bottom of a low-pressure refinement tower 3 via a low-pressure refinement tower reboiler 14; the top of the low-pressure refinement tower 3 is connected to the bottom of a negative pressure mash tower I 1 via a negative pressure mash tower I reboiler A 9; the bottom of a negative pressure mash tower II 2 is connected to a negative pressure mash tower II reboiler 11, and the negative pressure mash tower II reboiler 11 is connected to a superheated steam fluidized bed dryer 27;

[0046] A degassing section 25 is provided above the negative pressure mash tower I1; the top of the degassing section 25 is connected to the mash preheater, the lower part of the degassing section 25 is connected to the upper part of the negative pressure mash tower I1 through a pipeline, and the lower part of the degassing section 25 is also connected to the upper part of the negative pressure mash tower II2 through a pipeline; an acid discharge section 26 is provided above the negative pressure mash tower II2, and the acid discharge section 26 is connected to the low-pressure fine tower 3 through a pipeline; the bottom of the low-pressure fine tower 3 is connected to the lower part of the high-pressure fine tower 4; the top of the high-pressure fine tower 4 is connected to the molecular sieve adsorber group 5 through the superheater 17; the molecular sieve adsorber group 5 is connected to the finished product cooler 20 through the negative pressure mash tower I reboiler B10; the negative pressure mash tower I reboiler B10 is connected to the bottom of the negative pressure mash tower I1.

[0047] The mash preheater includes a first-stage mash preheater 6 ; the first-stage mash preheater 6 is connected to a second-stage mash preheater 7 ; the second-stage mash preheater 7 is connected to a third-stage mash preheater 8 ; the third-stage mash preheater 8 is connected to the top of the degassing section 25 .

[0048] The molecular sieve adsorber group 5 is connected to the finished product cooler 20 in sequence through the negative pressure mash tower I reboiler B10 and the mash three-stage preheater 8; the top of the degassing section 25 is connected to the mash two-stage preheater 7, and the mash two-stage preheater 7 is connected to the degassing section condenser 21; the acid discharge section 26 is connected to the mash one-stage preheater 6, and the mash one-stage preheater 6 is connected to the acid discharge section condenser 22. One end of the degassing section condenser 21 and one end of the acid discharge section condenser 22 are both connected to the distillation vacuum pump 23, and the other end is connected to the acid discharge section reflux tank 24; the acid discharge section reflux tank 24 is connected to the upper part of the acid discharge section 26. The acid discharge section 26 is connected to the low-pressure fine tower 3 in sequence through the crude wine tank 12 and the crude alcohol preheater 13. The molecular sieve adsorber group 5 is connected to the crude wine tank 12 through the analytical condenser 18; the analytical condenser 18 is also connected to the waterless vacuum pump 19; the bottom of the high-pressure fine tower 4 is connected to the crude alcohol preheater 13. The bottom of the low-pressure fine tower 3 is connected to the lower part of the high-pressure fine tower 4 through the high-pressure fine tower 4 feed preheater; the high-pressure fine tower reboiler 15 is connected to the high-pressure fine tower feed preheater 16. The superheated steam fluidized bed dryer 27 is connected to the fan 28 and the superheater 29 in sequence to form a closed loop; the superheated steam fluidized bed dryer 27 is also connected to the lees separation system 30 and the clear liquid multi-effect evaporation system 31 respectively; the lees separation system 30 is connected to the clear liquid multi-effect evaporation system 31; the bottoms of the negative pressure mash tower Ⅰ1 and the negative pressure mash tower Ⅱ2 are both connected to the lees separation system 30 through pipelines.

[0049] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific examples. If the specific experimental conditions are not specified in the examples, they are usually in accordance with conventional conditions or the conditions recommended by the reagent company; the reagents, consumables, etc. used in the following examples, unless otherwise specified, can be obtained through commercial channels.

[0050] Example

[0051] 1. The fermented mature mash is preheated to 42°C by the first-level mash preheater 6 (the mature mash is preheated once while the wine vapor is condensed at the top of the acid discharge section 26), preheated to 55°C by the second-level mash preheater 7 (the mature mash is preheated twice while the wine vapor is condensed at the top of the degassing section 25), and preheated to 58°C by the third-level mash preheater 8 (the liquid fuel ethanol condensed after dehydration and heating of the negative pressure mash tower Ⅰ1 is preheated three times for the mature mash), and then fed to the top of the degassing section 25 at the top of the negative pressure mash tower Ⅰ1. After entering the tower, the carbon dioxide and some low-boiling impurities in the mature mash are separated from the fermented mash under the action of the crude alcohol vapor rising from the negative pressure mash tower Ⅰ1, and the impure crude wine vapor enters the second-level mash preheater 7 and the degassing section condenser 21 for condensation, and the uncondensed impurity gas is discharged through the distillation vacuum pump 23. The condensate enters the reflux tank 24 of the acid discharge section, and the fermented mash with gas removed enters the bottom of the degassing section 25. Part of the mash (70%) flows by gravity into the negative pressure mash tower Ⅰ1, and the lees are discharged at the bottom of the negative pressure mash tower Ⅰ1 and sent to the lees treatment section. The rest (30%) flows by gravity into the negative pressure mash tower Ⅱ2.

[0052] Heating method of negative pressure mash tower Ⅰ1: the top steam of low pressure fine tower 3 heats negative pressure mash tower Ⅰ1 through negative pressure mash tower Ⅰ reboiler A 9; the dehydrated anhydrous alcohol vapor heats negative pressure mash tower Ⅰ1 through negative pressure mash tower Ⅰ reboiler B10. The bottom operating temperature of negative pressure mash tower Ⅰ1 is 80℃, the top temperature is 65℃, and the top temperature of degassing section 25 is 62℃.

[0053] 2. Part of the deaerated mash from the bottom of the degassing section 25 flows by gravity into the negative pressure mash tower Ⅱ2. After entering the tower, it is heated by the steam rising from the bottom of the tower while descending in the negative pressure mash tower Ⅱ2, and the wine vapor goes up and separates from the waste mash. The waste mash is discharged at the bottom of the negative pressure mash tower Ⅱ2 and sent to the lees treatment section together with the lees at the bottom of the negative pressure mash tower Ⅰ1; the wine vapor from the negative pressure mash tower Ⅱ2 goes up and enters the bottom of the acid discharge section 26, and most of the volatile acids and aldehydes in the crude alcohol are discharged through the acid discharge section 26. The rising wine vapor from the acid discharge section 26 enters the mash primary preheater 6 and the acid discharge section condenser 22 for condensation, and the uncondensed impurity gas is discharged through the distillation vacuum pump 23. The condensed condensate enters the acid discharge section reflux tank 24, and then is pumped into the top of the acid discharge section 26. The crude alcohol at the bottom of the acid discharge section 26 flows by gravity into the crude wine tank 12.

[0054] Heating method of negative pressure mash tower Ⅱ 2: secondary steam from the superheated steam fluidized bed dryer enters the negative pressure mash tower Ⅱ reboiler 11 through the secondary steam inlet 27 to heat negative pressure mash tower Ⅱ 2; the bottom operating temperature of negative pressure mash tower Ⅱ 2 is 80°C, the top temperature is 65°C, and the top temperature of the acid discharge section 26 is 52°C.

[0055] 3. The crude alcohol from the crude wine tank 12 is preheated by the crude alcohol preheater 13 (heat exchange with the waste hot water at the bottom of the high-pressure fine tower 4) and enters the lower part of the low-pressure fine tower 3. After entering the tower, part of the alcohol evaporates and undergoes vapor-liquid mass transfer exchange with the reflux liquid at the top of the tower, gradually concentrating until the alcohol vapor with an alcohol content of more than 95% (v / v) at the top of the tower enters the negative pressure mash tower I reboiler A 9 to heat the negative pressure mash tower I1, and is pumped into the low-pressure fine tower 3 after condensation. Alcohol is extracted from the side line of the tower plate 10-15 layers below the reflux port of the low-pressure fine tower 3 and pumped into the top of the high-pressure fine tower 4.

[0056] The low-pressure refinement tower 3 works under a slight positive pressure, and its working pressure is about 0.1MPa. The heating method of the low-pressure refinement tower 3 is as follows: the alcohol vapor at the top of the high-pressure refinement tower 4 heats the low-pressure refinement tower 3 through the low-pressure refinement tower reboiler 14. The operating temperature of the bottom of the low-pressure refinement tower 3 is 105℃, and the top temperature is 95℃.

[0057] 4. The light alcohol from the bottom of the low-pressure fine tower 3 is pumped into the high-pressure fine tower feed preheater 16 for preheating (heat exchange with steam condensate water) and then enters the middle of the high-pressure fine tower 4. After entering the tower, the alcohol is gradually concentrated, and the alcohol concentration at the top of the tower can reach more than 95% (v / v). The intermediate impurities (fusel oils) are retained on the plates above the feed plate, and the fusel oil is produced. The alcohol vapor with an alcohol content of more than 95% (v / v) produced by the vapor phase at the top of the high-pressure fine tower 4 enters the molecular sieve adsorber group 5 for dehydration, and the remaining alcohol vapor is condensed by the low-pressure fine tower reboiler 14 and then pumped back to the high-pressure fine tower 4. The waste water in the kettle of the high-pressure fine tower 4 preheats the crude alcohol and then goes to the sewage treatment section.

[0058] The high-pressure distillation tower 4 works under positive pressure, and its working pressure is 0.35MPa. The heating method of the high-pressure rectification tower 4 is that the fresh steam from the boiler room heats the high-pressure rectification tower 4 through the high-pressure rectification tower reboiler 15. The operating temperature of the bottom of the high-pressure rectification tower 4 is 150℃, and the top temperature is 120℃.

[0059] 5. The alcohol vapor with a concentration of more than 95% (v / v) from the top of the high-pressure fine tower 4 is superheated to 150°C by the superheater 17 and then enters the molecular sieve adsorber group 5 for dehydration. The anhydrous ethanol vapor produced after dehydration enters the negative pressure mash tower I reboiler B10 to heat the negative pressure mash tower I1. The condensed anhydrous ethanol is pumped into the mash three-stage preheater 8 to preheat the fermented mash, and then cooled to room temperature by the finished product cooler 20. The light wine produced by negative pressure analysis in the analysis condenser 18 enters the crude wine tank 12.

[0060] 6. The lees at the bottom of negative pressure mash tower Ⅰ1 and negative pressure mash tower Ⅱ2 are separated by lees separation system 30 to obtain clear liquid and wet lees. The clear liquid enters the clear liquid multi-effect evaporation system 31 for concentration and evaporation, and the wet lees enters the superheated steam fluidized bed dryer 27 for drying. The secondary steam is extracted by the fan 28, and then enters the superheated steam fluidized bed dryer 27 for circulation after being superheated by the heater 29. The superheated steam absorbs the moisture in the lees and becomes saturated steam, thereby drying the lees. A part of the secondary steam generated by the superheated steam fluidized bed dryer 27 is used as the heat source of the clear liquid multi-effect evaporation system 31, and a part of it enters the reboiler 11 of the negative pressure mash tower Ⅱ as the heat source of the negative pressure mash tower Ⅱ2. The concentrated slurry generated by the clear liquid multi-effect evaporation system 31 enters the superheated steam fluidized bed dryer 27 and is dried together with the wet lees to obtain DDGS feed.

[0061] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A fuel ethanol distillation device using secondary steam from a superheated steam fluidized bed dryer as part of the heat source, characterized in that: The fuel ethanol distillation device comprises a high-pressure refinement tower, the bottom of which is connected to a high-pressure refinement tower reboiler, and the top of which is connected to the bottom of a low-pressure refinement tower via a low-pressure refinement tower reboiler; the top of the low-pressure refinement tower is connected to the bottom of a negative pressure mash tower I via a negative pressure mash tower I reboiler A; the bottom of the negative pressure mash tower II is connected to a negative pressure mash tower II reboiler, and the negative pressure mash tower II reboiler is connected to a superheated steam fluidized bed dryer; A degassing section is provided above the negative pressure mash tower I; the top of the degassing section is connected to a mash preheater, the lower part of the degassing section is connected to the upper part of the negative pressure mash tower I through a pipeline, and the lower part of the degassing section is also connected to the upper part of the negative pressure mash tower II through a pipeline; an acid discharge section is provided above the negative pressure mash tower II; the top of the high pressure fine tower is connected to a molecular sieve adsorber group through a superheater; the reboiler B of the negative pressure mash tower I is connected to the bottom of the negative pressure mash tower I; The mash preheater comprises a first-stage mash preheater; the first-stage mash preheater is connected to a second-stage mash preheater; the second-stage mash preheater is connected to a third-stage mash preheater; the third-stage mash preheater is connected to the top of the degassing section; The molecular sieve adsorber group is connected to the finished product cooler in sequence through the negative pressure mash tower I reboiler B and the mash three-stage preheater; the top of the degassing section is connected to the mash two-stage preheater, and the mash two-stage preheater is connected to the degassing section condenser; the top of the acid discharge section is connected to the mash first-stage preheater, and the mash first-stage preheater is connected to the acid discharge section condenser; One end of the degassing section condenser and one end of the acid discharge section condenser are connected to the distillation vacuum pump, and the other end of the degassing section condenser and the other end of the acid discharge section condenser are connected to the acid discharge section reflux tank; the acid discharge section reflux tank is connected to the upper part of the acid discharge section; The acid discharge section is connected to the low-pressure fine tower through the crude wine tank and the crude alcohol preheater in sequence; the molecular sieve adsorber group is connected to the crude wine tank through the analytical condenser; the analytical condenser is also connected to the waterless vacuum pump; the bottom of the high-pressure fine tower is connected to the crude alcohol preheater; The bottom of the low-pressure refinement tower is connected to the lower part of the high-pressure refinement tower through the high-pressure refinement tower feed preheater; the high-pressure refinement tower reboiler is connected to the high-pressure refinement tower feed preheater; The superheated steam fluidized bed dryer is connected to the fan and the superheater in sequence to form a closed loop; the superheated steam fluidized bed dryer is also connected to the wine lees separation system and the clear liquid multi-effect evaporation system respectively; the wine lees separation system is connected to the clear liquid multi-effect evaporation system; the bottoms of the negative pressure mash tower I and the negative pressure mash tower II are connected to the wine lees separation system through pipelines.

2. A method for preparing fuel ethanol using the fuel ethanol distillation apparatus according to claim 1, characterized in that: The following steps are involved: (1) The fermented mature mash is preheated to 42°C in the first-stage mash preheater, 55°C in the second-stage mash preheater, and 58°C in the third-stage mash preheater, and then fed to the top of the degassing section. The carbon dioxide and some low-boiling impurities in the mature mash are separated from the fermented mash under the action of the crude alcohol vapor rising from the negative pressure mash tower I. The impure crude alcohol vapor enters the second-stage mash preheater and the degassing section condenser for condensation, and the uncondensed impure crude alcohol vapor is discharged through the distillation vacuum pump; the condensate enters the reflux tank of the acid discharge section, and the fermented mash with gas removed enters the bottom of the degassing section, and 60-70% of it flows into the negative pressure mash tower I by gravity, and the obtained lees are discharged at the bottom of the negative pressure mash tower I; Heating method of negative pressure mash tower I: the top steam of low pressure refinement tower passes through reboiler A of negative pressure mash tower I to heat negative pressure mash tower I; the dehydrated anhydrous alcohol steam passes through reboiler B of negative pressure mash tower I to heat negative pressure mash tower I; The mature mash is preheated once while the wine vapor is condensed at the top of the acid discharge section; the mature mash is preheated twice while the wine vapor is condensed at the top of the degassing section; the liquid fuel ethanol condensed after dehydration and heating of the negative pressure mash tower I is preheated three times for the mature mash; the operating temperature of the bottom of the negative pressure mash tower I is 80℃, the top temperature is 65℃, and the top temperature of the degassing section is 62℃; (2) The other 30-40% of the fermented mash that has been degassed flows by gravity into the negative pressure mash tower II. While descending in the negative pressure mash tower II, it is heated by the steam rising from the bottom of the tower. The evaporated wine vapor rises and separates from the remaining waste mash, and the waste mash is discharged at the bottom of the tower. The wine vapor in the negative pressure mash tower II rises and enters the bottom of the acid discharge section, and most of the volatile acids and aldehydes in the crude alcohol are discharged through the acid discharge section. The wine vapor rising from the acid discharge section enters the mash primary preheater and the acid discharge section condenser in turn for condensation. The uncondensed wine vapor is discharged through the distillation vacuum pump, and the condensate enters the acid discharge section reflux tank and is sent to the top of the acid discharge section. The crude alcohol at the bottom of the acid discharge section flows by gravity into the crude alcohol tank. Heating method of negative pressure mash tower II: secondary steam from fluidized bed dryer heats negative pressure mash tower II through negative pressure mash tower II reboiler; the bottom operating temperature of negative pressure mash tower II is 80℃, the top temperature is 65℃, and the top temperature of acid discharge section is 52℃; (3) The crude alcohol from the crude alcohol tank is preheated in the crude alcohol preheater and then enters the lower part of the low-pressure polishing tower. After entering the tower, part of the alcohol evaporates and then undergoes vapor-liquid mass transfer exchange with the reflux liquid at the top of the tower, gradually concentrating until the alcohol vapor at the top of the tower reaches an alcohol content of more than 95% (v / v). It enters the reboiler A of the negative pressure mash tower I to heat the negative pressure mash tower I, condenses, and then refluxes to the low-pressure polishing tower. The alcohol extracted from the low-pressure polishing tower is then sent to the top of the high-pressure polishing tower. Heating method of low-pressure tower: alcohol vapor at the top of high-pressure tower heats low-pressure tower through low-pressure tower reboiler; working pressure of low-pressure tower is 0.1MPa, operating temperature at the bottom of low-pressure tower is 105℃, and top temperature is 95℃; (4) The light alcohol at the bottom of the low-pressure refinement tower is preheated in the high-pressure refinement tower feed preheater and then enters the middle and lower part of the high-pressure refinement tower. After entering the tower, the alcohol is gradually concentrated until the alcohol content at the top of the tower reaches more than 95% (v / v). The alcohol vapor with an alcohol content of more than 95% (v / v) is extracted from the vapor phase at the top of the high-pressure refinement tower and enters the molecular sieve adsorber group for dehydration. The remaining alcohol vapor in the high-pressure refinement tower is condensed in the low-pressure refinement tower reboiler and then refluxed to the high-pressure refinement tower; the waste hot water in the high-pressure refinement tower is discharged and enters the crude alcohol preheater to preheat the crude alcohol preheater; Heating method of high-pressure rectification tower: fresh steam from the boiler room heats the high-pressure rectification tower through the high-pressure rectification tower reboiler; the working pressure at the top of the high-pressure rectification tower is 0.35MPa, the operating temperature at the bottom of the high-pressure rectification tower is 150℃, and the top temperature is 120℃; (5) The alcohol vapor with an alcohol content of more than 95% (v / v) from the top of the high-pressure fine tower is superheated to 150°C in the superheater and then enters the molecular sieve adsorber group for dehydration. The anhydrous ethanol vapor produced after dehydration enters the negative pressure mash tower I reboiler B for heating. The alcohol vapor is condensed to become anhydrous ethanol, and then preheats the fermented mash in the mash three-stage preheater, and finally cools to room temperature in the finished product cooler; the light wine produced by negative pressure analysis in the analysis condenser enters the crude wine tank; (6) The lees at the bottom of negative pressure mash tower I and negative pressure mash tower II are separated by the lees separation system to obtain clear liquid and wet lees. The clear liquid enters the clear liquid multi-effect evaporation system for concentrated evaporation, and the wet lees enter the superheated steam fluidized bed dryer for drying. The secondary steam is extracted by the fan, and then superheated in the superheater and enters the superheated steam fluidized bed dryer for circulation. The superheated steam absorbs the moisture in the lees and becomes saturated steam, thereby drying the lees. The concentrated slurry produced by the clear liquid multi-effect evaporation system enters the superheated steam fluidized bed dryer and is dried together with the wet lees to obtain DDGS feed.

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