阅读说明：本技术 混合原料发酵生产乙醇的方法和系统 (Method and system for producing ethanol by fermenting mixed raw materials ) 是由 卢久灵 邓衍宏 汪虎 耿玉友 于 2021-08-19 设计创作，主要内容包括：本发明涉及酒精发酵技术领域,具体涉及具体涉及混合原料发酵生产乙醇的方法和系统,所述方法包括：(1)将混合原料依次进行糊化液化反应、糖化反应、发酵,得到发酵醪液；(2)将所述发酵醪液进行脱气、脱醛,得到粗酒精；接着将所述粗酒精分为a股液和b股液；(3)将a股液进行初次精馏,得到初精馏汽和初精馏液；将b股液进行提馏,得到提馏汽和废液；(4)将所述初精馏汽和所述提馏汽混合进行蒸馏,得到蒸馏汽；(5)将所述蒸馏汽和所述初精馏液进行二次精馏,得到再精馏汽。本发明在利用现有的三塔精馏系统的基础上,有效解决发酵醪液堵塞醪塔以及组合塔现象,实现在工业上采用混合原料发酵制备酒精。(The invention relates to the technical field of alcohol fermentation, in particular to a method and a system for producing ethanol by fermenting mixed raw materials, wherein the method comprises the following steps: (1) sequentially carrying out gelatinization and liquefaction reaction, saccharification reaction and fermentation on the mixed raw materials to obtain fermented mash; (2) degassing and dealdehyding the fermented mash to obtain crude alcohol; then dividing the crude alcohol into a liquid and a liquid; (3) carrying out primary rectification on the a stock solution to obtain primary rectification steam and primary rectification solution; stripping the b-strand liquid to obtain stripping steam and waste liquid; (4) mixing the primary rectification steam and the stripping steam for distillation to obtain distillation steam; (5) and carrying out secondary rectification on the distillation steam and the primary rectification liquid to obtain re-rectification steam. The invention effectively solves the problems of blockage of the mash tower and combination tower of the fermented mash on the basis of utilizing the existing three-tower rectification system, and realizes the industrial preparation of alcohol by adopting mixed raw material fermentation.)

1. A method for producing ethanol by fermentation of a mixed feedstock, the method comprising:

(1) sequentially carrying out gelatinization and liquefaction reaction, saccharification reaction and fermentation on the mixed raw materials to obtain fermented mash;

(2) degassing and dealdehyding the fermented mash to obtain crude alcohol, low-boiling-point impurities and waste mash; then dividing the crude alcohol into a liquid and a liquid;

(3) carrying out primary rectification on the a stock solution to obtain primary rectification steam and primary rectification solution;

stripping the b-strand liquid to obtain stripping steam and waste liquid;

(4) mixing the primary rectification steam and the stripping steam for distillation to obtain distillation steam;

(5) performing secondary rectification on the distillation steam and the primary rectification liquid to obtain re-rectification steam;

wherein the weight ratio of rice to wheat in the mixed raw materials is 1: 0.8-1.

2. The method according to claim 1, wherein the volume content of the a-stream of liquid is 0-60% by volume based on the total amount of the crude alcohol; the volume content of the b strand of liquid is 40-100 volume%;

preferably, the mixed raw material further comprises at least one of corn, cassava, brown rice and sorghum.

3. The method of claim 1 or 2, wherein step (1) comprises: in the presence of xylanase and amylase, carrying out gelatinization liquefaction reaction on the mixed raw material to obtain liquefied mash; then adding saccharifying enzyme, acid protease and yeast seeds into the liquefied mash, and fermenting to obtain fermented mash;

preferably, the weight ratio of the xylanase to the amylase is 1-4: 28;

preferably, the conditions of the gelatinization liquefaction reaction at least satisfy: the temperature is 80-100 ℃, the time is 3-4h, and the pH is 5-6;

preferably, the conditions of the fermentation are at least: the temperature is 30-36 ℃, and the time is 50-60 h.

4. The method of claim 3, wherein step (1) further comprises: dividing the liquefied mash into c streams of liquor and d streams of liquor;

mixing the c-strand liquid with a first part of saccharifying enzyme to obtain a first mixed liquid;

mixing the d-strand solution with a second part of saccharifying enzyme to obtain a second mixed solution, and contacting the second mixed solution, acid protease and yeast seeds for a proliferation reaction to obtain a proliferation reaction solution;

mixing the first mixed solution and the proliferation reaction solution to obtain a third mixed solution, and then fermenting the third mixed solution to obtain fermented mash;

preferably, the weight content of the first part of saccharifying enzyme is 60-80 wt% based on the total amount of the first part of saccharifying enzyme and the second part of saccharifying enzyme; the weight content of the second part of saccharifying enzyme is 20-40 wt%;

the volume ratio of the c liquid to the d liquid is 1: 0.8-1.2.

5. A system for the fermentative production of ethanol from a mixed feedstock, said system comprising a fermentation system and a three-column distillation system, wherein said three-column distillation system comprises: the device comprises a mash tower (1), wherein the mash tower (1) sequentially comprises a crude distillation section (11), a degassing section (12) and a dealdehyding section (13) from bottom to top, and the top end of the degassing section (12) is provided with a feeding hole (10); used for degassing and dealdehyding the fermented mash to obtain crude alcohol, low-boiling-point impurities and waste mash; the crude alcohol is divided into a liquid and a liquid;

the combined tower (2) comprises a stripping section (21) and a distillation section (22) from bottom to top, and the stripping section (21) is communicated with the aldehyde removal section (13) and is used for stripping the b-strand liquid to obtain stripping steam and waste liquid;

the auxiliary tower (5) is communicated with the aldehyde removal section (13) and the distillation section (22) and is used for carrying out primary rectification on the a strand of liquid to obtain primary rectification steam and primary rectification liquid; distilling the mixture of the primary rectification steam and the stripping steam in the distillation section (22) to obtain distillation steam;

the rectifying tower (3) is communicated with the top end of the combined tower (2) and the bottom end of the auxiliary tower (5) and is used for carrying out secondary rectification on the primary distillation liquid and part of the distillation steam to obtain re-rectification steam;

and the dehydration unit (9) is respectively communicated with the top end of the combined tower (2) and the top end of the rectifying tower (3) and is used for dehydrating part of the re-rectifying steam and the rest of the distilled gas to obtain the absolute ethyl alcohol.

6. The system according to claim 5, wherein a bottom end of the crude distillation section (11) is provided with a first liquid outlet (112), a top end of the aldehyde removing section (13) is provided with a first gas outlet (133) for extracting the first part of low boiling impurities, and a bottom end of the aldehyde removing section (13) is provided with a second liquid outlet (132);

the second liquid outlet (132) is communicated with the auxiliary tower (5) and is used for introducing the a strand of liquid into the auxiliary tower (5) for primary rectification;

the second liquid outlet (132) is communicated with the top end of the stripping section (21) through a feed pump (19) and is used for feeding the b strands of liquid into the combined tower (2) for stripping.

7. The system according to claim 5 or 6, wherein the top of the degassing section (12) is provided with a second gas outlet (18) for leading a second portion of low boiling impurities out of the beer column (1);

preferably, the bottom of the beer column (1) is provided with a beer column reboiler (30).

8. The system of claim 7, further comprising a heat exchange system in communication with the feed inlet (10), a beer feed pump, the first outlet (133), the second outlet (18), and a beer reflux drum (17), respectively, for heat exchanging the beer with the low boiling impurities;

preferably, the heat exchange system comprises a first heat exchanger (15) and a second heat exchanger (16), the second heat exchanger (16) being in communication with the first gas outlet (133) and the beer feed pump for heat exchanging the beer with the first portion of low boiling impurities to obtain a first preheated beer and a first condensate;

the first heat exchanger (15) is communicated with the second gas outlet (18) and an outlet of the second heat exchanger (16) and is used for exchanging heat between the first preheated mash and the second part of low-boiling-point impurities to obtain a second preheated mash and a second condensate;

the beer column reflux drum (17) is in communication with the first heat exchanger (15) and/or the second heat exchanger (16) for collecting the first condensate and/or the second condensate.

9. The system according to any one of claims 5 to 8, wherein the top of the crude distillation section (11) is provided with a third gas outlet (111), and the bottom end of the aldehyde removal section (13) is provided with a first gas inlet (131) communicated with the third gas outlet (111);

preferably, the bottom of the degassing section (12) is in communication with the top end of the crude fraction (11) via a gravity pipe (14) for cyclically introducing into the crude fraction (11) for crude rectification a degassed mash obtained by degassing the fermentation mash through the degassing section (12).

10. The system according to any one of claims 5 to 8, wherein the top of the stripping section (21) is provided with a first liquid inlet (211), the bottom of the distillation section (22) is provided with a second gas inlet (221), and the top of the distillation section (22) is provided with a fifth gas outlet (222); the first liquid inlet (211) is communicated with the second liquid outlet (132),

preferably, the top end of the auxiliary column (5) is communicated with the second gas inlet (221) for introducing the primary rectification steam into the distillation section (22) for distillation;

preferably, the system further comprises a second preheater (25) which is respectively communicated with the second liquid outlet (132), the bottom end of the stripping section (21) and the first liquid inlet (211) and is used for exchanging heat between the b-strand liquid and the waste liquid and introducing the b-strand liquid obtained by heat exchange into the stripping section (21) for stripping.

11. The system of claim 10, wherein the beer column reboiler (30) is in communication with the fifth gas outlet (222) for condensing a remaining portion of the distillation vapor to produce a third condensate;

preferably, the system further comprises a combined column reflux tank (26), a fifth liquid inlet (223) is arranged at the upper end of the distillation section (22), and the combined column reflux tank (26) is communicated with the mash column reboiler (30) and the fifth liquid inlet (223) and is used for introducing the third condensate into the rectifying column (3) for secondary rectification;

preferably, the combined column reflux drum (26) is in communication with the fifth liquid inlet (223) via a combined column reflux pump (27) for recycling a portion of the third condensate into the combined column (2).

12. A system according to any one of claims 5 to 11, wherein the combined column reflux drum (26) communicates with the top end of the rectification column (3) for introducing part of the third condensate into the rectification column (3) for rectification;

a sixth air outlet (64) is formed in the top end of the rectifying tower (3), and the sixth air outlet (64) is communicated with a dehydration unit and is used for dehydrating the re-rectified steam to obtain absolute ethyl alcohol;

the system also comprises a rectifying tower reflux tank (65), wherein the rectifying tower reflux tank (65) is respectively communicated with the top of the rectifying tower (3) and the combined tower reflux tank (26) and is used for introducing part of the third condensate into the rectifying tower (3) for secondary rectification;

preferably, a second liquid inlet (61) is arranged in the middle of the rectifying tower (3), and the second liquid inlet (61) is communicated with the bottom end of the auxiliary tower (5) and is used for introducing the primary rectifying liquid into the rectifying tower (3) for rectification;

preferably, the system further comprises a rectifying tower preheater (62), wherein the rectifying tower preheater (62) is communicated with the auxiliary tower (5) and the rectifying tower (3) and is used for introducing the preheated primary rectifying liquid into the rectifying tower (3) for secondary rectification.

13. The system of claim 12, further comprising a combined column reboiler (31), wherein the combined column reboiler (31) is in communication with the sixth gas outlet (64) and the fine column reflux drum (65) and is configured to condense part of the re-rectification gas taken out from the sixth gas outlet (64) to obtain a fourth condensate, and to introduce the fourth condensate into the rectification column (3) by circulating through the fine column reflux drum (65);

preferably, the bottom of the auxiliary tower (5) is provided with an auxiliary tower reboiler (33);

preferably, the bottom of the rectifying tower (3) is provided with a rectifying tower reboiler (32).

Technical Field

The invention relates to the technical field of alcoholic fermentation, in particular to a method and a system for producing ethanol by fermenting mixed raw materials.

Background

Biofuel ethanol is ethanol that can be used as fuel by using renewable biomass as a raw material, and a typical biological energy source is a strategic emerging industry of China that is concerned with agriculture, energy, environment and regional economy. At present, the raw material for alcohol fermentation is mainly corn, but the production cost of ethanol is increasing with the increase of the price of corn, so that the production of ethanol by using mixed raw materials of rice, wheat and the like instead of corn is one of important ways for reducing the cost of fuel ethanol.

However, because the protein in rice and wheat is high, a large amount of foam is generated in the liquefaction and fermentation processes, and the viscosity of fermented liquor is high, so that the fermented liquor is easy to scale on a pipeline and block the pipeline and a tower plate in the subsequent distillation process, the distillation process cannot be continuously and stably performed, frequent stopping, overhauling and cleaning are needed, and safety risks exist during the operation; in addition, the by-product DDGS obtained by fermenting and producing rice and wheat has dark color, and the economic benefit of the by-product is reduced. The fuel ethanol produced by fermenting wheat has the problems, and the fuel ethanol produced by fermenting rice and wheat serving as raw materials is difficult to popularize due to the reasons.

In the prior art, the problem that a large amount of foam is generated in the processes of liquefaction and fermentation of rice is solved by mixing corn and rice for fermentation, but in the actual production, the problems of foaming, high mash viscosity and tower kettle scaling still exist by adopting the method, and in addition, the raw materials are fermented in a raw material fermentation mode, so that acidic substances are easily generated in the fermentation process, and the incomplete liquefaction is caused.

Disclosure of Invention

The invention aims to solve the problems of distillation system scaling and pipeline blockage caused by foaming and high mash viscosity of a mixed raw material containing rice and wheat in the fermentation process in the prior art, and provides a method for producing ethanol by fermenting the mixed raw material.

The inventor of the invention finds that rice or wheat is easy to foam in the fermentation process, and the obtained fermented mash has high viscosity, so that the fermented mash is easy to block a mash tower, a combined tower and pipelines thereof in the subsequent rectification process, the rectification effect is poor, and a distillation system can be stopped in serious cases; in addition, due to the vegetable proteins contained in the wheat fermentation liquor, during distillation, the vegetable proteins can be attached to the inner walls of the tower kettle and the pipeline, so that the inner walls of the tower kettle and the pipeline are scaled, the system is blocked, and the shutdown and maintenance are required frequently. However, when rice and wheat are mixed and fermented simultaneously, plant proteins in the wheat can be attached to the surface of the rice hulls and continuously wash the tower kettle and the pipeline along with the flowing of materials, so that the scale formation of the tower kettle and the pipeline is avoided.

In order to achieve the above object, a first aspect of the present invention provides a method for producing ethanol by fermentation of a mixed feedstock, the method comprising:

(1) sequentially carrying out gelatinization and liquefaction reaction, saccharification reaction and fermentation on the mixed raw materials to obtain fermented mash;

(2) degassing and dealdehyding the fermented mash to obtain crude alcohol, low-boiling-point impurities and waste mash; then dividing the crude alcohol into a liquid and a liquid;

(3) carrying out primary rectification on the a stock solution to obtain primary rectification steam and primary rectification solution;

stripping the b-strand liquid to obtain stripping steam and waste liquid;

(4) mixing the primary rectification steam and the stripping steam for distillation to obtain distillation steam;

(5) performing secondary rectification on the distillation steam and the primary rectification liquid to obtain re-rectification steam;

wherein the weight ratio of rice to wheat in the mixed raw materials is 1: 0.8-1.

In a second aspect, the present invention provides a system for producing ethanol by fermentation of a mixed feedstock, the system comprising a fermentation system and a three-column distillation system, the three-column distillation system comprising: the mash tower sequentially comprises a coarse distillation section, a degassing section and a dealdehyding section from bottom to top, and the top end of the degassing section is provided with a feeding hole; used for degassing and dealdehyding the fermented mash to obtain crude alcohol, low-boiling-point impurities and waste mash; the crude alcohol is divided into a liquid and a liquid;

the combined tower comprises a stripping section and a distillation section from bottom to top, and the stripping section is communicated with the aldehyde removal section and is used for stripping the b-strand liquid to obtain stripping steam and waste liquid;

the auxiliary tower is communicated with the aldehyde removal section and the distillation section and is used for carrying out primary rectification on the a stock solution to obtain primary rectification steam and primary rectification solution; distilling the mixture of the primary rectification steam and the stripping steam in the distillation section to obtain distillation steam;

the rectifying tower is communicated with the top end of the combined tower and the bottom end of the auxiliary tower and is used for carrying out secondary rectification on the distillation steam and the primary distillation liquid to obtain re-rectification steam;

and the dehydration unit is respectively communicated with the top end of the combined tower and the top end of the rectifying tower and is used for dehydrating the re-rectifying steam and the residual part of the distilled gas to obtain the anhydrous ethanol.

Through the technical scheme, the plant protein in the wheat is attached to the surface of the rice hull by mixing various raw materials such as rice, wheat and the like for fermentation, and the tower kettle and the pipeline are continuously washed, so that the scale formation of the tower kettle and the pipeline can be effectively avoided;

according to the characteristics of the fermented mash obtained by fermenting the mixed raw materials, the crude alcohol obtained by degassing and dealdehyding the fermented mash through the mash tower is directly introduced into the combined tower or the rectifying tower for rectification, and the degassed mash is not extracted from the mash tower, so that the degassed mash is not introduced into the combined tower, the phenomenon that the fermented mash blocks the mash tower and the combined tower can be effectively solved on the basis of utilizing the conventional three-tower distillation system, and the industrial production of alcohol prepared by fermenting the mixed raw materials is realized.

Drawings

FIG. 1 is a schematic diagram of a system for the fermentative production of ethanol from mixed feedstocks, according to an embodiment of the present invention;

FIG. 2 is a schematic structural view of a beer column according to an embodiment of the present invention;

FIG. 3 is a schematic structural view of a modular tower according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of a rectification column according to an embodiment of the present invention;

FIG. 5 is a photograph showing fouling of the distillation system in comparative example 3.

Description of the reference numerals

1. A mash tower 10, a feed inlet 11 and a crude distillation section

111. Third gas outlet 112, first liquid outlet 12 and degassing section

13. A formaldehyde removing section 131, a first gas inlet 132 and a second liquid outlet

14. Free flow pipe 15, first heat exchanger 16, second heat exchanger

17. A mash tower reflux tank 18, a second air outlet 2 and a combined tower

21. A stripping section 211, a first liquid inlet 22 and a distillation section

221. Second air inlet 222, fifth air outlet 25 and second preheater

26. Combination tower reflux tank 27, combination tower reflux pump 3 and rectifying tower

30. Mash tower reboiler 31, combined tower reboiler 32 and auxiliary tower reboiler

33. Auxiliary tower reboiler 4, steam main pipe 223 and fifth liquid inlet

5. Auxiliary tower 50, first preheater 51 and fourth air outlet

52. A third liquid outlet 60, a rectifying tower feed pump 61 and a second liquid inlet

62. Rectifying tower preheater 63, fusel oil extraction outlet 65 and auxiliary tower reboiler

67. Reflux pump 133 of rectifying tower, first air outlet 64 and sixth air outlet

212. A fourth liquid outlet 19, a feeding pump 8 and a third preheater

9. Dewatering unit

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

In the present invention, the use of directional terms such as "upper, lower, left, right" generally means upper, lower, left, right as viewed with reference to the accompanying drawings, unless otherwise specified; "inner and outer" generally refer to the inner and outer relative to the profile of the components themselves; "distal and proximal" generally refer to distance relative to the contour of the components themselves.

As previously mentioned, a first aspect of the present invention provides a process for the fermentative production of ethanol from a mixed feedstock, said process comprising:

(1) sequentially carrying out gelatinization and liquefaction reaction, saccharification reaction and fermentation on the mixed raw materials to obtain fermented mash;

(2) degassing and dealdehyding the fermented mash to obtain crude alcohol, low-boiling-point impurities and waste mash; then dividing the crude alcohol into a liquid and a liquid;

(3) carrying out primary rectification on the a stock solution to obtain primary rectification steam and primary rectification solution;

stripping the b-strand liquid to obtain stripping steam and waste liquid;

(4) mixing the primary rectification steam and the stripping steam for distillation to obtain distillation steam;

(5) and carrying out secondary rectification on the distillation steam and the primary rectification liquid to obtain re-rectification steam.

According to the present invention, the mixed raw material preferably further comprises other starchy mixed raw material, and the starchy mixed raw material may be of a type known to those skilled in the art, and may be at least one of corn, sorghum, brown rice, cassava, and the like. The content of each raw material can be adjusted according to the supply condition of the raw materials in the actual production.

According to the invention, by adjusting the contents of rice and wheat in the mixed raw materials and adjusting the fermentation process and the distillation process, the problems of scale formation and pipeline blockage in the distillation process of fermented mash obtained by fermenting the conventional rice and wheat mixed raw materials are solved, the ethanol is produced by fermenting various mixed raw materials, and the source range of the mixed raw materials is improved. According to the invention, the ratio of rice and wheat needs to be controlled within a certain range, when the wheat content is too high, the vegetable protein in the wheat can not be completely adsorbed by rice hulls, the mash still contains free vegetable protein, and the vegetable protein can be attached to the inner walls of a tower kettle and a pipeline to cause system scaling, and under the optimal condition, the weight ratio of the rice to the wheat in the mixed raw material is 1: 0.8-1.

According to the invention, in order to improve the yield of ethanol, the content of the a strand liquid is preferably 0-60% by volume based on the total amount of the crude alcohol; the volume content of the b strand of liquid is 40-100 volume percent. Through dividing into two strands with crude alcohol, can realize the heat and match, improve the utilization ratio of energy, and conveniently control the liquid level of combination tower.

In some preferred embodiments of the present invention, the step (1) further comprises: in the presence of xylanase and amylase, carrying out gelatinization liquefaction reaction on the mixed raw material to obtain liquefied mash; and then adding saccharifying enzyme, acid protease and yeast seeds into the liquefied mash, and fermenting to obtain fermented mash.

In the present invention, in order to reduce the viscosity of the liquefied mash and to increase the efficiency of gelatinisation liquefaction and the alcohol content of the fermented mash, it is preferred that the ratio of the xylanase to the amylase is 1-4: 28; further preferably, the total amount of xylanase and amylase added is 0.1-0.3 kg/ton based on the total amount of the raw materials mixed.

In the present invention, the amount of the acidic protease added is 0.05 to 0.15 kg/ton based on the total amount of the raw materials to be mixed.

According to the invention, the mixed raw material is gelatinized and liquefied by adopting a clinker fermentation mode, and further preferably, the conditions of the gelatinization and liquefaction reaction at least meet the following conditions: the temperature is 80-100 deg.C, the time is 3-4h, and the pH is 5-6. Under the preferable conditions, the liquefaction efficiency can be improved, and the content of alcohol in the fermented mash can be improved.

According to the invention, it is preferred that the conditions of the fermentation at least satisfy: the temperature is 30-36 ℃, and the time is 50-60 h.

According to the invention, in the early stage of fermentation, if the concentration of reducing sugar in the system is too high, the activity and growth rate of yeast seeds are inhibited, so that the growth rate of yeast is reduced, the death rate is increased, the cell resistance is reduced, and the alcohol content of fermented liquor is reduced. In some preferred embodiments of the present invention, the activity of yeast seeds is ensured, thereby increasing the alcohol content in the fermentation mash, and the step (1) further comprises: dividing the liquefied mash into c streams of liquor and d streams of liquor;

mixing the c-strand liquid with a first part of saccharifying enzyme to obtain a first mixed liquid;

mixing the d-strand solution with a second part of saccharifying enzyme to obtain a second mixed solution, and contacting the second mixed solution, acid protease and yeast seeds for a proliferation reaction to obtain a proliferation reaction solution;

and mixing the first mixed solution and the proliferation reaction solution to obtain a third mixed solution, and then fermenting the third mixed solution to obtain fermented mash.

According to the invention, part of saccharifying enzyme is added into the d liquid, so that the d liquid simultaneously carries out saccharification reaction on the liquefied mash and proliferation of yeast seeds, and the generation rate of reducing sugar in the saccharification reaction is equivalent to the consumption rate of the reducing sugar in the proliferation process of the yeast seeds, so that the concentration of the reducing sugar in the reaction liquid is lower, the activity of the yeast seeds is ensured, and the alcohol content in the fermented mash is improved.

According to the present invention, preferably, since the second mixed solution simultaneously performs the saccharification reaction and the propagation reaction, a low content of the saccharifying enzyme in the second mixed solution results in a low amount of reducing sugar produced by the saccharification reaction and fails to satisfy the requirement for propagation of the yeast seeds, while a high content of the saccharifying enzyme results in an excessively high concentration of the reducing sugar produced and inhibits propagation of the yeast seeds, wherein the weight content of the first saccharifying enzyme is 60 to 80 wt% based on the total amount of the first saccharifying enzyme and the second saccharifying enzyme; the weight content of the second part of saccharifying enzyme is 20-40 wt%.

According to the invention, in order to further improve the promotion of fermentation and the alcohol content of the fermented mash, the volume ratio of the c liquid to the d liquid is preferably 1: 0.8 to 1.2, for example, 0.8: 1. 1: 1. 1.2: 1 or any value in the range of any two of the above values, most preferably 1: 1.

in the invention, in order to improve the utilization rate of energy and reduce the energy consumption of production, under the preferable conditions, the method further comprises the following steps: and exchanging heat between the low-boiling-point impurities and the fermented mash.

According to the present invention, preferably, the method further comprises: and the b-stock solution and the waste liquid are subjected to heat exchange, so that the utilization rate of system energy can be further improved under the preferable condition.

According to the invention, the waste mash can be directly fed into a DDGS production device to produce DDGS, and the produced DDGS has lighter color.

In the invention, the redistilled steam is also dehydrated to obtain absolute ethyl alcohol (more than 99.5 volume percent), and the dehydration can be molecular sieve dehydration.

Aiming at the characteristics that mash obtained by fermenting mixed raw materials contains a large amount of foam, the mash has high viscosity and is easy to block pipelines and scale, the method not only improves the scale formation of the pipelines and tower plates by adjusting the types of the mixed raw materials, but also improves the pipeline blockage and reduces the cleaning frequency of the system by changing the structure of a distillation system.

In a second aspect, the present invention provides a system for producing ethanol by fermentation of a mixed feedstock, the system comprising a fermentation system and a three-column distillation system, the three-column distillation system comprising: the device comprises a mash tower 1, wherein the mash tower 1 sequentially comprises a rough distillation section 11, a degassing section 12 and a dealdehyding section 13 from bottom to top, and the top end of the degassing section 12 is provided with a feeding hole 10; used for degassing and dealdehyding the fermented mash to obtain crude alcohol, low-boiling-point impurities and waste mash; the crude alcohol is divided into a liquid and a liquid;

the combined tower 2 comprises a stripping section 21 and a distillation section 22 from bottom to top, and the stripping section 21 is communicated with the aldehyde removal section 13 and is used for stripping the b-strand liquid to obtain stripping steam and waste liquid;

the auxiliary tower 5 is communicated with the aldehyde removal section 13 and the distillation section 22 and is used for carrying out primary rectification on the a stock solution to obtain primary rectification steam and primary rectification solution; distilling the mixture of the primary rectification steam and the stripping steam in the distillation section 22 to obtain distillation steam;

the rectifying tower 3 is communicated with the top end of the combined tower 2 and the bottom end of the auxiliary tower 5 and is used for carrying out secondary rectification on the primary distillation liquid and part of the distillation steam to obtain re-rectification steam;

and the dehydration unit 9 is respectively communicated with the top end of the combined tower 2 and the top end of the rectifying tower 3 and is used for dehydrating part of the re-rectified steam and the rest of the distilled gas to obtain the absolute ethyl alcohol.

According to the invention, the system further comprises a steam main 4 for supplying heat to the system, the steam main 4 being in communication with the bottoms of the beer column 1, the combination column 2, the rectification column 3 and the auxiliary column 5, respectively, for supplying heat to the beer column 1, the combination column 2, the rectification column 3 and the auxiliary column 5, respectively.

In the invention, fermentation mash enters a mash tower 1 from a degassing section 12 of the mash tower 1, firstly, degassing is carried out in the degassing section 12 to obtain degassed mash, the degassed mash continues to flow upwards, and dealdehydization is carried out in a dealdehydizing section 13 to obtain crude alcohol and waste mash; the crude alcohol is extracted from a second liquid outlet 132 and then is divided into a liquid a and a liquid b, wherein the liquid a is firstly subjected to primary rectification in an auxiliary tower 5 to obtain primary rectification steam and primary rectification liquid, and the primary rectification steam enters a distillation section 22 of a combined tower 2; b, directly introducing the liquid into a stripping section 21 of the combined tower 2 for stripping to obtain stripping steam and waste liquid; wherein the stripping steam continuously flows upwards to enter a distillation section 22, and is mixed with the primary rectification steam and then distilled in the distillation section 22 to obtain distillation steam, the distillation steam flows out from the top end of the combined tower and is divided into two strands, one strand enters a rectification tower 3 to be continuously rectified secondarily, and the re-rectification steam is obtained at the top of the rectification tower 3; the other strand and the re-rectification steam respectively enter a dehydration unit 9 for dehydration treatment to obtain ethanol steam, and the ethanol steam is cooled to obtain absolute ethanol (more than 99.5 vol%); the waste mash is extracted from the bottom of the mash tower 1 and directly enters a DDGS production device to produce DDGS.

According to the invention, crude alcohol obtained by degassing and dealdehyding fermented mash obtained by fermenting mixed raw materials is divided into two streams (a stream and b stream) and then is partially introduced into the combined tower 2 for stripping and distillation, and partially introduced into the rectifying tower 3 for rectification, degassed mash is not extracted from the mash tower 1, and the combined tower 2 does not need to distill the degassed mash, so that the fermented mash of the mixed raw materials can be distilled on the basis of utilizing the existing three-tower distillation system, the combined tower 2 cannot be blocked, the cleaning frequency is obviously reduced, the long-term stable operation of the distillation system is ensured, the economic loss caused by normally-open cleaning can be avoided, the production cost of anhydrous ethanol is reduced, and the industrial production of preparing the anhydrous ethanol from the mixed raw materials, particularly from hydrous rice and/or wheat raw materials is realized; meanwhile, heat matching can be realized, the utilization rate of energy is improved, and the liquid level of the combined tower is conveniently controlled.

In some preferred embodiments of the present invention, the beer column 1 comprises, from bottom to top, a crude distillation section 11, a degassing section 12 and a dealdehyding section 13, wherein the bottom end of the crude distillation section 11 is provided with a first liquid outlet 112 for extracting the waste beer; the top end of the aldehyde removing section 13 is provided with a first air outlet 133 for extracting a first part of low-boiling-point impurities; the bottom end of the aldehyde removing section 13 is provided with a second liquid outlet 132 for extracting the crude alcohol; wherein the second liquid outlet 132 is communicated with the auxiliary tower 5 and is used for introducing the a strand of liquid into the auxiliary tower 5 for primary rectification; the second liquid outlet 132 is communicated with the top end of the stripping section 21, and is used for introducing the b strands of liquid into the combined tower 1 for stripping.

According to the present invention, it is preferred that the top of the degassing section 12 is provided with a second gas outlet 18 for leading a second portion of the low boiling impurities out of the beer column 1, in order to increase the energy utilization in the system and reduce the energy consumption for production.

According to the present invention, preferably, in order to increase the utilization rate of energy in the system, the system further comprises a heat exchange system, which is respectively communicated with the feed inlet 10, the fermented mash feed pump, the first outlet 133, the second outlet 18 and the mash tower reflux tank 17, for exchanging heat between the fermented mash and the low-boiling impurities. Further preferably, the heat exchange system comprises a first heat exchanger 15 and a second heat exchanger 16, wherein a tube-side inlet of the second heat exchanger 16 is connected with a fermented mash feed pump, and a shell-side of the second heat exchanger 16 is respectively connected with the first gas outlet 133 and an inlet of the mash tower reflux tank 17, and is used for exchanging heat between the fermented mash and a first part of low-boiling-point impurities extracted from the first gas outlet 133 to obtain a first preheated mash and a first condensate; the tube side of the first heat exchanger 15 is connected with the material inlet 10 and the tube side outlet of the second heat exchanger 16, the shell side of the first heat exchanger 15 is respectively connected with the second gas outlet 18 and the inlet of the mash tower reflux tank 17, and the first heat exchanger 15 is used for exchanging heat between the first preheated mash and a second part of low-boiling-point impurities collected from the second gas outlet 18 to obtain a second preheated mash and a second condensate, wherein the first heat exchanger 15 is communicated with the feed inlet 10 and is used for introducing the second preheated mash into the mash tower 1 through the feed inlet 10; the beer column reflux drum 17 is used to collect the first condensate and/or the second condensate.

In some preferred embodiments of the present invention, the top of the crude distillation section 11 is provided with a third gas outlet 111, and the bottom end of the aldehyde removing section 13 is provided with a first gas inlet 131 communicated with the second gas outlet 111.

According to the invention, the bottom of the degassing section 12 is communicated with the top end of the crude distillation section 11 through a gravity flow pipe 14 under the preferred conditions, and the degassed mash obtained by degassing the fermented mash through the degassing section 12 is circularly introduced into the crude distillation section 11 for crude distillation, so that the degassing efficiency of the fermented mash can be improved, the yield of crude alcohol can be improved, and the impurity content in the crude alcohol can be reduced under the preferred conditions.

According to the present invention, preferably, the bottom of the beer column 1 is provided with a beer column reboiler 30 for providing heat to the beer column 1.

In some preferred embodiments of the present invention, the top of the stripping section 21 is provided with a first liquid inlet 211, the bottom of the distillation section 22 is provided with a second gas inlet 221, and the top of the distillation section 22 is provided with a fifth gas outlet 222; the first liquid inlet 211 is communicated with the second liquid outlet 132, and is used for introducing the b strands of liquid into the stripping section 21 for stripping to obtain stripping vapor and waste liquid.

In some preferred embodiments of the present invention, a fourth gas outlet 51 is disposed at the top end of the auxiliary column 5, a third liquid outlet 52 is disposed at the bottom end of the auxiliary column 5, and the fourth gas outlet 51 is communicated with the second gas inlet 221, and is used for introducing a primary distillation vapor obtained by primary distillation of the a liquid into the distillation section 22 for distillation.

According to the present invention, preferably, the bottom of the auxiliary column 5 is further provided with an auxiliary column reboiler 33 for heating the auxiliary column 5.

According to the present invention, preferably, the system further comprises a first preheater 50, wherein the first preheater 50 is connected to the second liquid outlet 32 and the inlet of the auxiliary column 5, and is used for introducing the a liquid into the auxiliary column 5 for primary rectification after preheating the a liquid.

In the present invention, the waste liquid is composed of hot water, in some preferred embodiments of the present invention, in order to improve the energy utilization rate of the system and realize the reuse of the waste water, under preferred conditions, the system further includes a second preheater 25, a tube pass inlet of the second preheater 25 is communicated with the feed pump 19, a tube pass outlet of the second preheater 25 is communicated with the first liquid inlet 211, a shell pass of the second preheater 25 is communicated with the fourth liquid outlet 212, and is configured to exchange heat between the b-strand liquid and the waste liquid, and introduce the b-strand liquid obtained by heat exchange into the stripping section 21 from the first liquid inlet 211 for stripping; the low temperature waste liquid obtained by heat exchange is circularly led into a water tank of a reboiler 30 of the mash tower for recycling.

Further preferably, the fifth gas outlet 222 is communicated with the reboiler 30, the distillation vapor extracted from the fifth gas outlet 22 is divided into two streams, one stream enters the reboiler 30 to heat the beer column 1, and the distillation vapor is condensed to obtain a third condensate; one stream enters the dehydration unit 9 for dehydration.

According to the present invention, it is preferable that the system further comprises a combined column reflux drum 26, the upper end of the distillation section 22 is provided with a fifth liquid inlet 223, the inlet of the combined column reflux drum 26 is communicated with the beer column reboiler 30, and the third condensate is passed through the combined column reflux drum 26; an outlet of the combined tower reflux tank 26 is respectively communicated with the fifth liquid inlet 223, the dehydration unit 9 and the top end of the rectifying tower 3; the third condensate which flows out from the reflux tank 26 of the combined tower is divided into three streams, one stream enters the rectifying tower 3 for secondary rectification, and the other stream is circularly introduced into the combined tower 2 for distillation; the other strand enters a dewatering unit 9 for dewatering treatment. More preferably, the liquid outlet of the combined column reflux drum 26 is in communication with the combined column 2 via a combined column reflux pump 27.

According to the present invention, preferably, the bottom of the combined column 2 is provided with a beer column reboiler 31 for providing heat for the combined column 2; the mash tower reboiler 31 is communicated with the top end of the rectifying tower 3 and is used for introducing the re-rectifying steam into the rectifying tower 3 for heat exchange. Under the above preferable conditions, the utilization rate of energy can be improved.

In some preferred embodiments of the present invention, a sixth gas outlet 64 is disposed at the top end of the rectifying tower 3 for extracting the re-rectified steam; the sixth gas outlet 64 is in communication with the dewatering unit 9 and the beer column reboiler 31, respectively; the rectification tower is used for dividing the re-rectification steam into two parts, and part of the re-rectification steam is introduced into the rectification tower 3 for heat exchange; the rest re-rectification steam enters a dehydration unit 9 for dehydration treatment.

According to the present invention, under a preferable condition, the system further comprises a rectifying tower preheater 62, wherein the rectifying tower preheater 62 is communicated with the third liquid outlet 52 at the bottom end of the auxiliary tower 5 and the second liquid inlet 61, and is used for introducing the preheated primary rectifying liquid into the rectifying tower 3 for secondary rectification.

According to the invention, under the preferable conditions, the system further comprises a rectifying tower reflux tank 65, wherein the rectifying tower reflux tank 65 is respectively communicated with the top of the rectifying tower 3 and the combined tower reflux tank 26 and is used for pumping the third condensate into the rectifying tower 3 through a rectifying tower reflux pump 67 for secondary rectification.

According to the present invention, preferably, a rectifying tower reboiler 32 is disposed at the bottom of the rectifying tower 3, the rectifying tower reboiler 32 is communicated with the steam main 4, and the steam passing through the steam main 4 is introduced into the rectifying tower reboiler 32 to indirectly heat the rectifying tower 3.

According to the invention, under a preferable condition, the system further comprises a combined tower reboiler 31, the combined tower reboiler 31 is communicated with the sixth gas outlet 64 and the rectifying tower reflux tank 65, and is used for condensing part of re-rectification gas extracted from the sixth gas outlet 64 and exchanging heat with the combined tower reboiler 31 to obtain fourth condensate, and the fourth condensate is circularly introduced into the rectifying tower 3 through the rectifying tower reflux tank 65 for rectification. Under the above preferred conditions, the efficiency of energy utilization can be improved

In the invention, the alcohol vapor obtained by dehydration in the dehydration unit 9 still contains high heat, and in order to realize comprehensive utilization of energy, under the preferable conditions, the dehydration unit 9 is communicated with the auxiliary tower reboiler 33 and used for supplying heat to the auxiliary tower reboiler 33; the absolute ethanol from the auxiliary column reboiler 33 is communicated with the third preheater 8 for heating the second preheated mash to obtain a third preheated mash.

In the present invention, the type of the dehydration unit may be known to those skilled in the art, and may be, for example, a molecular sieve.

In some preferred embodiments of the invention, the bottoms of the mash tower 1, the combination tower 2, the auxiliary tower 5 and the rectification tower 3 are respectively provided with a liquid level controller and an alarm, the liquid level controller is electrically connected with the alarm, and the alarm can receive signals of the liquid level controller and send an alarm. Through the liquid level controller can maintain the invariable liquid level at the bottom of the tower, when the liquid level at the bottom of the tower surpassed and predetermine the liquid level, the alarm can accept the signal of liquid level controller and send out the police dispatch newspaper, be convenient for in time discover and handle unusual problem, liquid level controller and alarm are the well-known product among the prior art.

The system for producing ethanol by fermenting mixed raw materials, provided by the invention, is used for distilling fermented mash obtained by gelatinizing, liquefying, saccharifying and fermenting the mixed raw materials, and comprises a mash tower 1, a combined tower 2 and a rectifying tower 3, wherein the mash tower 1, the combined tower 2 and the rectifying tower 3 are respectively connected with a steam main pipe 4 and a reboiler for providing heat required by distillation, fermented mash is gradually distilled through the mash tower 1, the combined tower 2 and the rectifying tower 3, and the mash tower 1 is used for removing aldehyde from the fermented mash entering the towers to obtain crude alcohol; the combined tower 2 is used for carrying out positive pressure rough distillation on the crude alcohol entering the tower to obtain alcohol steam with the alcohol content of more than 95%; the rectifying tower 3 is used for extracting and rectifying fusel from crude alcohol entering the rectifying tower, and dehydrating the crude alcohol through a molecular sieve dehydration layer to obtain absolute ethyl alcohol with the alcohol content of more than 99.5 percent; the system can effectively avoid the fermented mash from blocking the tower plates and pipelines in the system, and ensures the long-term stable operation of the system.

FIG. 1 is a schematic diagram of a system for producing ethanol by fermenting a rice-containing mixed feedstock, according to an embodiment of the present invention; FIG. 2 is a schematic structural view of a beer column according to an embodiment of the present invention; FIG. 3 is a schematic structural view of a modular tower according to an embodiment of the present invention; fig. 4 is a schematic structural view of a rectifying tower according to an embodiment of the present invention, as shown in fig. 1 to 4, and in a preferred embodiment of the present invention, the method for producing ethanol by fermenting mixed raw materials comprises:

(1) in the presence of xylanase and amylase, carrying out gelatinization liquefaction reaction on a mixed raw material (the weight ratio of rice to wheat in the mixed raw material is 1: 0.8-1) at the temperature of 80-100 ℃ and the pH value of 5-6 for 3-4h to obtain liquefied mash; wherein the weight ratio of the xylanase to the amylase is 1-4: 28;

dividing the liquefied mash into c streams of liquor and d streams of liquor;

mixing the c-strand liquid with 60-80 wt% of saccharifying enzyme to obtain a first mixed liquid;

mixing the d-strand liquid with the residual 20-40 wt% of saccharifying enzyme to obtain a second mixed liquid, contacting the second mixed liquid with acid protease and yeast seeds, and carrying out proliferation reaction at the temperature of 29 ℃ and the pH of 3.5 to obtain a proliferation reaction liquid;

injecting the first mixed solution into the proliferation reaction solution to obtain a third mixed solution, and then fermenting the third mixed solution for 60 hours at the temperature of 32 ℃ to obtain fermented mash;

(2a) the fermented mash exchanges heat through a second heat exchanger 16 and a first heat exchanger 15 in sequence to obtain a second preheated mash; introducing the second preheated mash into a degassing section 12 of the mash tower 1 from a feed inlet 10, and after entering the tower, separating carbon dioxide, volatile acids and low-boiling impurities in the fermented mash from the fermented mash under the action of negative pressure to form steam (first part of low-boiling impurities) and degassed mash (degassed fermented mash);

the degassed mash comprises gaseous degassed mash and liquid degassed mash, wherein the gaseous degassed mash continuously flows upwards to enter a dealdehyding section 13 for dealdehyding treatment to obtain dealdehydized crude alcohol and a second part of low-boiling-point impurities; wherein, the dealdehydized crude alcohol is discharged from the second liquid outlet 132; the liquid degassed mash flows into the crude distillation section 11 through the gravity flow pipe 14 and descends, and is heated by steam rising from the bottom of the tower at the same time, ascending wine vapor and descending alcohol-free waste mash are obtained, the wine vapor continues to ascend and sequentially enters the degassing section 12 and the dealdehyding section 13, and the waste mash is discharged from the first liquid outlet 112 and directly enters the DDGS processing device to produce DDGS;

a first part of low boiling point impurities rises in the degassing section 12 and is discharged from a first gas outlet 133, flows through a first heat exchanger 15 to heat fermented mash, is condensed into a first condensate liquid and flows into a mash tower reflux tank 17;

a second part of low-boiling impurities are discharged from the first gas outlet 133, flow through the second heat exchanger 16 to heat the fermented mash, and are condensed into a second condensate to flow into the mash tower reflux tank 17;

wherein the temperature of the crude distillation section is 82-86 ℃, and the pressure is-50 to-40 kPa; the temperature of the degassing section is 60-65 ℃, and the pressure is-65 to-70 kPa; the temperature of the aldehyde removing section is 55-60 ℃, and the pressure is-65 to-70 kPa;

(2b) dividing the crude alcohol into a liquid and a liquid, wherein the volume content of the liquid is 60% of the total volume of the crude alcohol; the volume content of the b strand of liquid is 40 volume percent;

(2c) preheating the a stock of liquid by a first preheater 50, and then feeding the preheated a stock of liquid into an auxiliary tower 5 for primary rectification to obtain primary rectification steam and primary rectification liquid, wherein the primary rectification steam is discharged out of the auxiliary tower 5 through a fourth gas outlet 51 and enters a distillation section 22 of the combined tower 2 from a second gas inlet 221 for distillation; wherein the temperature of the combination tower 5 is 118-123 ℃, and the pressure is 98-103 kPa;

(2d) stripping the b-strand liquid to obtain stripping steam and waste liquid;

b, preheating the liquid by a second preheater 25, feeding the liquid into a stripping section 21 of the combined tower 2 from a first liquid inlet 211 for stripping, descending the liquid in the combined tower 2, heating the liquid by ascending steam, separating the liquid to form ascending wine vapor and descending alcohol-free waste liquid, continuously ascending the wine vapor to enter a distillation section 21, mixing the wine vapor with the primary distillation vapor for distillation and concentration, and obtaining distillation vapor (the alcohol concentration reaches more than 95%) at the top of the combined tower 2; the distillation steam is discharged out of the combined tower from a fifth gas outlet 222, enters a mash tower reboiler 30 to heat the mash tower 1, is condensed to form a third condensate, then flows into a combined tower reflux tank 26, flows out of the combined tower reflux tank 26, is divided into two parts, one part is circularly pumped into the combined tower for distillation through a combined tower reflux pump 27, and the other part enters a rectifying tower 3 for rectification.

The alcohol-free waste liquid is discharged from the combination column 2 through a fourth liquid outlet 212 and enters the shell side of the second preheater 25.

Wherein the temperature of the distillation section 22 is 90-95 ℃ and the pressure is 78-81 kPa; the temperature of the stripping section 21 is 105-109 ℃, and the pressure is 85-90 kPa;

(2f) preheating 62 the primary rectification liquid from the bottom of the combined tower 5 by a rectification tower preheater, and then feeding the preheated primary rectification liquid into the rectification tower 3 from a second liquid inlet 61 for rectification; while gradually concentrating, low boiling point impurities such as methanol rise along with the alcohol vapor and flow out from the fusel oil extraction port 63; the alcohol continuously goes upward and is extracted through a sixth air outlet 64, and then is divided into two strands, and one strand enters a dehydration unit for dehydration to obtain absolute ethyl alcohol with the concentration of more than 99.5 volume percent; the other part of the condensed liquid enters a rectifying tower reflux tank 65 after being condensed by a combined tower reboiler 31, and then is circularly added into the rectifying tower 3 for secondary rectification under the action of a rectifying tower reflux pump 67;

wherein the temperature of the rectifying tower 3 is 150 ℃ and 158 ℃, and the pressure is 410 ℃ and 420 kPa.

The present invention will be described in detail below with reference to examples.

Amylase is a commercially available product of bioengineering, ltd, jenenaceae (china); the glucoamylase is a product sold by Shandong Kete enzyme preparation Co., Ltd, and the dosage of glucoamylase and raw material powder is 540 g/ton; the yeast seeds are super high-activity dry yeast for brewing wine, and are a commercial product of Angel yeast GmbH; the xylanase is a commercial product of Shandong Kete enzyme preparation GmbH; the acid protease is a commercially available product of Shandong Kete enzyme preparation Co.

The following examples are all carried out in the systems shown in figures 1 to 4.

Example 1

(1) Mixing and grinding mixed raw materials into powder to obtain raw material powder, wherein the mixed raw materials comprise 40 wt% of rice, 35 wt% of wheat, 20 wt% of corn and 5 wt% of brown rice;

mixing 1 ton of raw material powder with water to form slurry, adding 0.021kg of xylanase and 0.15kg of amylase into the slurry, and then carrying out gelatinization and liquefaction reaction for 3 hours under the conditions that the temperature is 85 ℃ and the pH value is 5.5 to obtain liquefied mash; dividing the liquefied mash into c liquid and d liquid, wherein the flow ratio of the c liquid to the d liquid is 1: 1;

mixing the c-strand liquid with 75 wt% of saccharifying enzyme to obtain a first mixed liquid;

mixing the d-strand liquid with the residual 25 wt% of saccharifying enzyme to obtain a second mixed liquid, introducing the second mixed liquid into a seed tank, and carrying out proliferation reaction under the action of 0.085kg of acid protease and yeast seeds to obtain a proliferation reaction liquid, wherein the proliferation reaction conditions are as follows: the temperature is 29 ℃, and the pH is 3.5;

injecting the first mixed solution into the proliferation reaction solution to obtain a third mixed solution, and then fermenting the third mixed solution for 60 hours at the temperature of 32 ℃ to obtain fermented mash;

(2a) the fermented mash passes through a second heat exchanger 16, a first heat exchanger 15 and a third heat exchanger 8 in sequence to exchange heat, and second preheated mash is obtained; introducing the second preheated mash into a degassing section 12 of the mash tower 1 from a feeding hole 10, and separating low-boiling-point impurities such as carbon dioxide, volatile acids and the like in the fermented mash after entering the tower from the fermented mash under the action of negative pressure to form a first part of low-boiling-point impurities and degassed mash; the de-aerated mash comprises gaseous de-aerated mash and liquid de-aerated mash;

the gaseous degassed mash continuously goes upward to enter a dealdehyding section 13 for dealdehyding treatment to obtain dealdehydized crude alcohol and a second part of low-boiling-point impurities; the dealdehydized crude alcohol is discharged from the second liquid outlet 132; the liquid degassed mash flows into the crude distillation section 11 through the gravity flow pipe 14 and descends, and is heated by the steam ascending at the bottom of the tower, so that ascending wine steam and descending waste mash without alcohol are obtained, and the wine steam continues to ascend; discharging the waste mash from a first liquid outlet 112, and directly feeding the waste mash into a DDGS processing device to produce DDGS;

a first part of low-boiling impurities rise in the degassing section 12 and are discharged from a first gas outlet 133, and then flow through a second heat exchanger 16 to exchange heat with the fermented mash to form a first condensate which flows into a mash tower reflux tank 17;

a second part of low-boiling-point impurities are discharged from a second gas outlet 18, flow through the first heat exchanger 15 and the first preheated mash, are heated and then are condensed into a second condensate liquid, and flow into the mash tower reflux tank 17;

wherein the bottom temperature of the crude distillation section is 84.18 ℃, and the bottom pressure is-45.96 KPa; the temperature of the degassing section is 64.89 ℃, and the pressure is-67.52 KPa; the temperature of the aldehyde removal section is 58.37 ℃, and the pressure is-68.53 KPa;

(2b) dividing the crude alcohol into a liquid and a liquid, wherein the volume content of the liquid is 60% of the total volume of the crude alcohol; the volume content of the b strand of liquid is 40 volume percent;

preheating the a stock of liquid by a first preheater 50, and then feeding the preheated a stock of liquid into an auxiliary tower 5 for primary rectification to obtain primary rectification steam and primary rectification liquid, wherein the primary rectification steam is discharged out of the auxiliary tower 5 through a fourth gas outlet 51 and enters a distillation section 22 of the combined tower 2 from a second gas inlet 221 for distillation; wherein the bottom temperature of the combined tower 5 is 120.4 ℃, and the pressure is 100.27 kPa;

(2d) stripping the b-strand liquid to obtain stripping steam and waste liquid;

b, preheating the liquid by a second preheater 25, feeding the liquid into a stripping section 21 of the combined tower 2 from a first liquid inlet 211 for stripping, descending the liquid in the combined tower 2, heating the liquid by ascending steam, separating the liquid to form ascending wine vapor and descending alcohol-free waste liquid, continuously ascending the wine vapor to enter a distillation section 21, mixing the wine vapor with the primary rectification vapor for distillation and concentration, and obtaining distillation vapor at the top of the combined tower 2; the distilled steam is discharged out of the combined tower from a fifth gas outlet 222 and then is divided into two parts, one part enters a dehydration unit 9 for dehydration, and the other part is condensed by a beer tower reboiler 30 to form a third condensate and flows into a combined tower reflux tank 26; the third condensate is divided into three strands after flowing out of the combined tower reflux tank 26, one strand is circularly pumped into the combined tower for distillation through a combined tower reflux pump 27, and the other strand enters the rectifying tower 3 for rectification; one stream enters the dehydration unit 9 for dehydration.

The alcohol-free waste liquid is discharged out of the combined tower 2 through a fourth liquid outlet 212, and enters a shell pass of the second preheater 25 to exchange heat with b streams of liquid, and the obtained low-temperature waste liquid enters a water tank of a mash tower reboiler 30 to serve as make-up water;

wherein the temperature of the distillation section 22 is 93.88 ℃ and the pressure is 79.43 kPa; the temperature of the stripping section 21 is 107.61 ℃, and the pressure is 87.36 kPa;

(2f) preheating 62 the primary rectification liquid from the bottom of the combined tower 5 by a rectification tower preheater, and then feeding the preheated primary rectification liquid into the rectification tower 3 from a second liquid inlet 61 for rectification to obtain second rectification steam; while the second rectification steam is gradually concentrated, low-boiling-point impurities such as methanol and the like rise along with the alcohol steam and flow out from the fusel oil extraction outlet 63; the second rectification steam continuously goes upward and is extracted through a sixth air outlet 64 and then is divided into two streams, and one stream enters a dehydration unit 9 for dehydration to obtain absolute ethyl alcohol with the concentration of more than 99.5 volume percent; the other part of the condensed liquid enters a rectifying tower reflux tank 65 after being condensed by a combined tower reboiler 31, and then is circularly added into the rectifying tower 3 for secondary rectification under the action of a rectifying tower reflux pump 67;

wherein the bottom temperature of the rectifying tower 3 is 152.24 ℃, and the bottom pressure is 415.07 kPa.

The distillation steam and the second rectification steam enter an auxiliary tower reboiler 33 after passing through a dehydration unit 9 to obtain ethanol steam, heat is supplied to the auxiliary tower reboiler 33, and liquid absolute ethanol is obtained; the liquid absolute ethyl alcohol and the second preheated mash enter an alcohol storage tank after heat exchange through a third heat exchanger 8;

the experimental results of this example are shown in table 1.

Example 2

The procedure of example 1 was followed except that 0.03kg of xylanase was used based on the total amount of the raw materials mixed; the dosage of amylase is 0.15 kg; the mass ratio of the xylanase to the amylase is 1: 5.

example 3

The procedure of example 1 was followed except that 0.015kg of xylanase was used, based on the total amount of the raw materials mixed; the dosage of amylase is 0.15 kg; the mass ratio of the xylanase to the amylase is 1: 10.

example 4

The process of example 1 was followed except that the conditions for liquefaction by gelatinization were: the temperature was 60 ℃.

Example 5

The process of example 1 was followed except that the saccharifying enzyme was directly added to the liquefied mash in one portion to carry out the saccharification reaction.

Example 6

The method of example 1 was followed except that the mixed raw materials included 55 wt% of rice and 45 wt% of wheat.

Example 7

The method of example 1 was followed except that the mixed raw materials included 30 wt% of rice, 25 wt% of wheat, 30 wt% of corn and 15 wt% of cassava.

Example 8

The process of example 1 was followed except that the mixed raw material comprised 10 wt% of rice, 9 wt% of wheat, 50 wt% of corn and 31 wt% of sorghum.

Comparative example 1

The method of example 1 was followed except that the mixed raw material contained 50 wt% of rice, 25 wt% of wheat, 20 wt% of corn and 5 wt% of brown rice.

Comparative example 2

The method of example 1 was followed except that the mixed raw material contained 30 wt% of rice, 35 wt% of wheat, 30 wt% of corn and 5 wt% of brown rice.

TABLE 1

TABLE 1 continuation

In table 1, saccharifying enzyme means the amount of saccharifying enzyme added to the first mixed solution, saccharifying enzyme means the amount of saccharifying enzyme added to the second mixed solution, and alcohol content means the volume percentage of alcohol in the fermented mash.

Comparative example 3

The fermented mash of example 1 was distilled using a three-column distillation system disclosed in CN111841053A, and the experimental results are shown in table 2;

as shown in fig. 5, the fouling of the system was severe after long-term distillation using the three-column distillation system of this comparative example, wherein 5(a) is the fouling of the injector pin; 5(b) is the scaling condition of the coordinating pipe of the jet machine; and 5(c) is the fouling of the liquefaction conduit.

TABLE 2

It can be seen from table 2 that the alcohol content of the fermented mash can be significantly increased by using the fermentation method and distillation method of the present invention, the viscosity of the fermented mash can be reduced by using a specific ratio of rice and wheat for fermentation, and the fouling and clogging of the mash tower and the rectification tower can be alleviated. In addition, since the cleaning frequency in comparative examples 1 to 3 is high, frequent shutdown for maintenance is required, which results in disqualification of ethanol produced during startup and shutdown, generation of a large amount of wastewater, etc., and increases production costs.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.