Double-coarse double-fine washing multi-tower differential pressure distillation system and method for preparing ethanol by using same

Abstract

The invention discloses a double-coarse double-fine washing multi-tower differential pressure distillation system and an ethanol preparation method thereof, and belongs to the technical field of rectification. The advanced four-effect distillation technology and the thermal coupling distillation technology are adopted, heat energy in the system is fully utilized, and steam consumption is reduced to the maximum extent through multi-stage preheating of materials and repeated utilization of heat. By arranging the protein separator, the protein contained in the mature mash is pretreated and separated before the mature mash enters the distillation system, so that the pipe blockage of the distillation tower is reduced. By optimizing the production process design, the production continuity and energy conservation are greatly improved, and the double harvest of economic benefit and low carbon consumption is realized.

Description

Technical Field

[0001] The invention relates to the technical field of distillation, and in particular to a double-crude double-fine water-washing multi-tower differential pressure distillation system and a method for preparing ethanol therefrom. Background Art

[0002] Ethanol (alcohol) is an important organic solvent, widely used in medicine, coatings, sanitary products, cosmetics, oils and fats, etc. Ethanol is also an important basic chemical raw material, which can be used to manufacture acetaldehyde, ethylenediene, ethylamine, ethyl acetate, acetic acid, ethyl chloride, etc., and derive many intermediates for products such as medicine, dyes, coatings, fragrances, synthetic rubber, detergents and pesticides.

[0003] Alcohol production mainly refers to the use of starchy materials such as wheat, rice, corn and cassava as raw materials, and alcohol products are made through processes such as crushing, liquefaction, saccharification, fermentation and alcohol separation. In the alcohol preparation industry, energy conservation and production continuity are two key research directions. In terms of energy-saving production of alcohol, the energy consumption cost of alcohol enterprises accounts for a high proportion of the product processing cost, and most of the energy is consumed in the process production stage. Energy consumption mainly includes steam, electricity, fresh water and compressed air, among which steam and electricity consumption account for the vast majority of energy consumption, which needs to be improved and reduced. Therefore, various manufacturers use process design and thermal coupling technology to strive to achieve the cascade application of energy. Although this method has produced certain effects, it is still necessary to continuously improve the production process and continue to reduce energy consumption. For the continuity of production, since the raw materials for alcohol production come from the fermentation of starchy materials, the mature mash produced after fermentation is distilled to obtain alcohol. In view of the fact that domestic alcohol production mostly adopts fermentation with residues, solid substances such as protein also enter the distillation system with the mature mash. These insoluble substances gather on the tower plate, causing the distillation tower to block. When this happens, the company can only stop the reaction and shut down for maintenance, which affects the continuity of production, increases product costs, and causes economic losses to the factory. The patent "CN112960853A A membrane treatment method for corn alcohol mash" uses membrane separation technology to treat and reuse corn alcohol mash. Although it achieves protein recovery, the object of treatment is the distilled corn alcohol mash, and it still cannot solve the tower blockage problem of the mature mash as the raw material. If the membrane separation step is pre-placed, the alcohol between the solid raw materials cannot be fully distilled due to the early separation of the solid and liquid raw materials, resulting in a decrease in raw material utilization and a reduction in alcohol product production. Therefore, how to save energy and improve the continuity of production in alcohol production has become an urgent need for manufacturers. Summary of the invention

[0004] In view of the above-mentioned prior art, the object of the present invention is to provide a double crude and double refined water washing multi-tower differential pressure distillation system and a method for producing ethanol therefrom.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] In a first aspect of the present invention, there is provided a method for preparing general-grade alcohol by double-crude and double-fine water-washing multi-tower differential pressure distillation, comprising the following steps:

[0007] After the raw fermented mash is separated from the protein in the protein separator, it is preheated by the preheater and enters the degassing tank. A part of the degassed mash enters the upper part of the atmospheric crude tower, and the crude alcohol vapor at the top of the atmospheric crude tower enters the negative pressure crude tower through the negative pressure crude tower reboiler; the other part flows into the negative pressure crude tower, merges with the crude alcohol vapor from the atmospheric crude tower and enters the dealdehyde tank; the crude wine condensed in the dealdehyde tank enters the crude wine tank of the negative pressure crude tower, and then the crude wine enters the water washing tower. The light wine at the bottom of the water washing tower is preheated and enters the second refinement tower, and the upper part of the second refinement tower produces general-grade alcohol; the light wine at the bottom of the second refinement tower enters the first refinement tower, and the general-grade alcohol is produced at the upper part of the first refinement tower, and then flows out after merging with the general-grade alcohol produced at the upper part of the second refinement tower;

[0008] The primary steam heats the first refined tower through the first refined tower reboiler, and the top material of the first refined tower is connected to the top of the second refined tower reboiler and the top of the atmospheric pressure crude tower reboiler through pipelines respectively. The second refined tower reboiler provides heat for the second refined tower, and the atmospheric pressure crude tower reboiler provides heat for the atmospheric pressure crude tower; the top material of the second refined tower is connected to the water washing tower reboiler through a pipeline, and the water washing tower reboiler provides heat for the water washing tower; the top material of the water washing tower and the top material of the atmospheric pressure crude tower are both connected to the negative pressure crude tower reboiler through pipelines, and the negative pressure crude tower reboiler provides heat for the negative pressure crude tower.

[0009] Furthermore, the bottom temperature of the atmospheric pressure crude tower is 100-110°C, and the top temperature is 90-100°C; the bottom temperature of the negative pressure crude tower is 70-90°C, and the top temperature is 60-70°C; the bottom temperature of the water washing tower is 90-100°C, and the top temperature is 80-100°C; the bottom temperature of the second fine tower is 110-120°C, and the top temperature is 90-110°C; the bottom temperature of the first fine tower is 140-160°C, and the top temperature is 110-130°C.

[0010] In a second aspect of the present invention, a double crude and double refined water-wash multi-tower differential pressure distillation system is provided, comprising a normal pressure crude tower, a negative pressure crude tower, a water-wash tower, a second refined tower and a first refined tower;

[0011] The top of the atmospheric pressure crude tower is connected to the negative pressure crude tower reboiler, the upper part is connected to the degassing tank, the lower part is connected to the atmospheric pressure crude tower reboiler, and the bottom part is connected to the negative pressure crude tower;

[0012] The upper part of the negative pressure crude tower is connected to the aldehyde removal tank and the degassing tank, the lower part is connected to the reflux tank and the negative pressure crude tower reboiler, and a wastewater outlet is set at the bottom;

[0013] The top of the water scrubber is connected to the negative pressure crude tower reboiler, the bottom is connected to the water scrubber reboiler, and the bottom is connected to the bottom of the second refinement tower and the first refinement tower respectively;

[0014] The top of the second refining tower is connected to the reboiler of the water washing tower, and a crude alcohol outlet pipe is arranged on the upper part and connected to the crude alcohol outlet pipe of the first refining tower;

[0015] The top of the first refinement tower is connected to the reboiler of the second refinement tower, the lower part is connected to the reboiler of the first refinement tower, and the bottom is connected to the reboiler of the negative pressure crude tower;

[0016] The reboiler of the atmospheric pressure crude tower is provided with a wastewater outlet;

[0017] A reboiler of a fine tower is provided with a wastewater outlet;

[0018] The preheater is connected to the degassing tank and the protein skimmer through a pipeline;

[0019] The aldehyde removal tank is connected to the reflux tank.

[0020] Furthermore, the bottom temperature of the atmospheric pressure crude tower is 100-110°C, and the top temperature is 90-100°C; the bottom temperature of the negative pressure crude tower is 70-90°C, and the top temperature is 60-70°C; the bottom temperature of the water washing tower is 90-100°C, and the top temperature is 80-100°C; the bottom temperature of the second fine tower is 110-120°C, and the top temperature is 90-110°C; the bottom temperature of the first fine tower is 140-160°C, and the top temperature is 110-130°C.

[0021] Beneficial effects of the present invention:

[0022] The device of the present invention realizes pretreatment of mature mash and reduces pipe blockage of the distillation tower by arranging a protein separator; reduces steam consumption by optimizing pipeline design; and achieves great improvements in production continuity and energy saving.

[0023] The present invention adopts advanced four-effect distillation technology and thermal coupling distillation process, fully utilizes the thermal energy in the system, and uses the heat for multiple times through multi-stage preheating of materials, thereby reducing steam consumption to the maximum extent. Specifically, the system of the present invention is equipped with double crude towers (normal pressure crude tower and negative pressure crude tower), double refined towers (one refined tower and two refined towers) and water washing tower, realizing "one tower steam inlet, five towers working". The primary steam heats the first refined tower through the reboiler of the first refined tower, part of the alcohol vapor at the top of the first refined tower heats the second refined tower through the reboiler of the second refined tower, the wine vapor at the top of the second refined tower heats the water washing tower through the reboiler of the water washing tower, and the wine vapor at the top of the water washing tower heats the negative pressure crude tower through the reboiler of the negative pressure crude tower, forming a four-effect distillation. The residual heat at the top of the first refined tower provides heat to the normal pressure crude tower through the normal pressure crude tower reboiler, and the alcohol vapor at the top of the normal pressure crude tower provides heat to the negative pressure crude tower through the negative pressure crude tower reboiler, and the three towers form a three-effect distillation. The steam consumption of one ton of general-grade alcohol is reduced from 1.4t / t steam to 0.6t / t steam.

[0024] The present invention provides a protein separator to pre-treat and separate the protein contained in the mature mash before it enters the distillation system. Due to the price changes of starch (sugar) raw materials required for alcohol production, alcohol production companies gradually adopt diversified raw materials, and corn, cassava, aged wheat and rice have become optional raw materials for alcohol production. When the system of the present invention performs protein removal operation on the mature mash, it does not use a membrane separator, but instead provides a protein separator to effectively reduce the protein content in the mature mash, avoiding the aggregation of protein at high temperature to form mist entrainment, and then the flow stream carries the aggregated deteriorated protein to the tower plate, causing the distillation tower to block. Before the protein separator is provided, when rice and wheat are used as raw materials, due to the blockage of the lower part of the distillation tower, the distillation system needs to be shut down every 15 days or so, and it takes about 2 days to clean the tower scale. After installing the protein skimmer, the continuous production time can be extended to 90-120 days, and the annual maintenance time is reduced from about 42 days to about 7 days, a decrease of 83.3%; the production time is increased from about 323 days to 358 days, an increase of 10.8%; overall, continuous production and increased benefits are achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of a double crude and double refined water washing multi-tower differential pressure distillation system;

[0026] In the figure: 1. Normal pressure crude tower; 2. Negative pressure crude tower; 3. Water washing tower; 4. Second refinement tower; 5. First refinement tower; 6. Reboiler of normal pressure crude tower; 7. Reboiler of negative pressure crude tower; 8. Reboiler of water washing tower; 9. Reboiler of second refinement tower; 10. Reboiler of first refinement tower; 11. Preheater; 12. Degassing tank; 14. Crude wine tank of negative pressure crude tower; 15. Formaldehyde removal section; 16. Protein separator. DETAILED DESCRIPTION

[0027] 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.

[0028] 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 embodiments.

[0029] The experimental materials used in the examples of the present invention but not specifically described are all conventional experimental materials in the art and can be purchased through commercial channels.

[0030] Example

[0031] Figure 1Schematic diagram of a double crude double polish water-washing multi-tower differential pressure distillation system of the present invention, which comprises a normal pressure crude tower 1, a negative pressure crude tower 2, a water-washing tower 3, a second polishing tower 4 and a first polishing tower 5;

[0032] The top of the atmospheric crude tower 1 is connected to the negative pressure crude tower reboiler 7, the upper part is connected to the degassing tank 12, the lower part is connected to the atmospheric crude tower reboiler 6, and the bottom is connected to the negative pressure crude tower 2; the upper part of the negative pressure crude tower 2 is connected to the aldehyde removal tank 14 and the degassing tank 12, the lower part is connected to the reflux tank 15 and the negative pressure crude tower reboiler 7, and a wastewater outlet is arranged at the bottom; the top of the water washing tower 3 is connected to the negative pressure crude tower reboiler 7, the lower part is connected to the water washing tower reboiler 8, and the bottom is respectively connected to the bottom of the second refinement tower 4 and the first refinement tower 5; the second refinement tower 4 The top is connected to the water washing tower reboiler 8, the upper part is provided with a crude alcohol outlet pipe and is connected to the crude alcohol outlet pipeline of the first refinement tower 5; the top of the first refinement tower 5 is connected to the second refinement tower reboiler 9, the lower part is connected to the first refinement tower reboiler 10, and the bottom is connected to the negative pressure crude tower reboiler 7; the atmospheric pressure crude tower reboiler 6 is provided with a wastewater outlet; the first refinement tower reboiler 10 is provided with a wastewater outlet; the preheater 11 is connected to the degassing tank 12 and the protein separator 16 through a pipeline; the dealdehyde tank 14 is connected to the reflux tank 15.

[0033] When used, the following production process is adopted:

[0034] After the raw fermented mash is separated from the protein in the protein separator 16, it is preheated by the preheater 11 and enters the degassing tank 12. A part of the degassed mash enters the upper part of the atmospheric crude tower 1, and the crude alcohol vapor at the top of the atmospheric crude tower 1 enters the negative pressure crude tower 2 through the negative pressure crude tower reboiler 7; the other part flows into the negative pressure crude tower 2, merges with the crude alcohol vapor from the atmospheric crude tower 1, and enters the dealdehyde tank 15; the crude wine condensed in the dealdehyde tank 15 enters the negative pressure crude tower crude wine tank 14, and then the crude wine enters the water washing tower 3, and the light wine at the bottom of the water washing tower 3 is preheated and enters the second refining tower 4, and the upper part of the second refining tower 4 produces general alcohol; the light wine at the bottom of the second refining tower 4 enters the first refining tower 5, and the general alcohol is produced at the upper part of the first refining tower 5, and then flows out after merging with the general alcohol produced at the upper part of the second refining tower 4;

[0035] The primary steam heats the first refined tower 5 through the first refined tower reboiler 10, and the top material of the first refined tower 5 is connected to the top of the second refined tower reboiler 9 and the top of the atmospheric pressure crude tower reboiler 6 through pipelines respectively, the second refined tower reboiler 9 provides heat for the second refined tower 4, and the atmospheric pressure crude tower reboiler 6 provides heat for the atmospheric pressure crude tower 1; the top material of the second refined tower 4 is connected to the water washing tower reboiler 8 through a pipeline, and the water washing tower reboiler 8 provides heat for the water washing tower 3; the top material of the water washing tower 3 and the top material of the atmospheric pressure crude tower 1 are both connected to the negative pressure crude tower reboiler 7 through pipelines, and the negative pressure crude tower reboiler 7 provides heat for the negative pressure crude tower 2.

[0036] The bottom temperature of atmospheric pressure crude tower 1 is 107°C, and the top temperature is 97°C; the bottom temperature of negative pressure crude tower 2 is 80°C, and the top temperature is 65°C; the bottom temperature of water washing tower 3 is 94°C, and the top temperature is 91°C; the bottom temperature of second fine tower 4 is 114°C, and the top temperature is 100°C; the bottom temperature of first fine tower 5 is 149°C, and the top temperature is 120°C.

[0037] The device of the present invention realizes pretreatment of mature mash and reduces pipe blockage of the distillation tower by arranging a protein separator; reduces steam consumption by optimizing pipeline design; and achieves great improvements in production continuity and energy saving.

[0038] In terms of energy saving, the present invention adopts advanced four-effect distillation technology and thermal coupling distillation process, fully utilizes the thermal energy in the system, and reduces steam consumption to the maximum extent through multi-stage preheating of materials and multiple utilization of heat. Specifically, the system of the present invention is equipped with a double crude tower atmospheric crude tower and a negative pressure crude tower, a double refined tower, a second refined tower and a water washing tower, so as to realize "one tower steam inlet, five towers working". The primary steam heats the first refined tower through the first refined tower reboiler, part of the alcohol vapor at the top of the first refined tower heats the second refined tower through the second refined tower reboiler, the wine vapor at the top of the second refined tower heats the water washing tower through the water washing tower reboiler, and the wine vapor at the top of the water washing tower heats the negative pressure crude tower through the negative pressure crude tower reboiler, forming a four-effect distillation. The residual heat at the top of the first refined tower provides heat to the atmospheric crude tower through the atmospheric crude tower reboiler, and the alcohol vapor at the top of the atmospheric crude tower provides heat to the negative pressure crude tower through the negative pressure crude tower reboiler, and the three towers form a three-effect distillation. The steam consumption of one ton of general-grade alcohol is reduced from 1.4t / t steam to 0.6t / t steam.

[0039] In terms of production continuity, the present invention pre-treats and separates the protein contained in the mature mash before it enters the distillation system by setting a protein separator. Due to the price changes of starch sugar raw materials required for alcohol production, alcohol production companies gradually adopt diversified raw materials, and corn, cassava, aged wheat and rice have become optional raw materials for alcohol production. When the system of the present invention performs protein removal operation on the mature mash, it does not use a membrane separator, but sets a protein separator to effectively reduce the protein content in the mature mash, avoiding the aggregation of protein at high temperature to form mist entrainment, and then the flow stream carries the aggregated deteriorated protein to the tower plate, causing the distillation tower to block. Before the protein separator is set, when rice and wheat are used as raw materials, due to the blockage of the lower part of the distillation tower, the distillation system needs to be shut down every 15 days or so, and it takes about 2 days to clean the tower scale. After installing the protein skimmer, the continuous production time can be extended to 90-120 days, and the annual maintenance time is reduced from about 42 days to about 7 days, a decrease of 83.3%; the production time is increased from about 323 days to 358 days, an increase of 10.8%; overall, continuous production and increased benefits are achieved.

[0040] 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 method for preparing general-grade alcohol by double-crude and double-fine water-washing multi-tower differential pressure distillation, characterized in that: The steps include: After the raw fermented mash is separated from the protein in the protein separator (16), it is preheated by the preheater (11) and enters the degassing tank (12). A portion of the degassed mash enters the upper part of the atmospheric crude tower (1). The crude alcohol vapor at the top of the atmospheric crude tower (1) enters the negative pressure crude tower (2) through the negative pressure crude tower reboiler (7); the other portion flows into the negative pressure crude tower (2), merges with the crude alcohol vapor from the atmospheric crude tower (1), and enters the dealdehyde tank (15); the crude wine condensed in the dealdehyde tank (15) enters the negative pressure crude tower crude wine tank (14), and then enters the water washing tower (3). The light wine at the bottom of the water washing tower (3) is preheated and enters the second refining tower (4), and the upper part of the second refining tower (4) produces general-grade alcohol; the light wine at the bottom of the second refining tower (4) enters the first refining tower (5), and the upper part of the first refining tower (5) produces general-grade alcohol, which merges with the general-grade alcohol produced at the upper part of the second refining tower (4) and flows out; The primary steam heats the first refined tower (5) through the first refined tower reboiler (10), and the top material of the first refined tower (5) is connected to the top of the second refined tower reboiler (9) and the top of the atmospheric pressure crude tower reboiler (6) through pipelines respectively. The second refined tower reboiler (9) provides heat for the second refined tower (4), and the atmospheric pressure crude tower reboiler (6) provides heat for the atmospheric pressure crude tower (1); the top material of the second refined tower (4) is connected to the water washing tower reboiler (8) through a pipeline, and the water washing tower reboiler (8) provides heat for the water washing tower (3); the top material of the water washing tower (3) and the top material of the atmospheric pressure crude tower (1) are both connected to the negative pressure crude tower reboiler (7) through pipelines, and the negative pressure crude tower reboiler (7) provides heat for the negative pressure crude tower (2).

2. The method for preparing general-grade alcohol by double-crude and double-fine water washing five-tower four-effect differential pressure distillation according to claim 1, characterized in that: The bottom temperature of the atmospheric pressure crude tower (1) is 100-110°C, and the top temperature is 90-100°C; the bottom temperature of the negative pressure crude tower (2) is 70-90°C, and the top temperature is 60-70°C; the bottom temperature of the water washing tower (3) is 90-100°C, and the top temperature is 80-100°C; the bottom temperature of the second refinement tower (4) is 110-120°C, and the top temperature is 90-110°C; the bottom temperature of the first refinement tower (5) is 140-160°C, and the top temperature is 110-130°C.

3. Double crude and double refined water washing multi-tower differential pressure distillation system, characterized in that: It comprises a normal pressure crude tower (1), a negative pressure crude tower (2), a water washing tower (3), a second refining tower (4) and a first refining tower (5); The top of the atmospheric pressure crude tower (1) is connected to the negative pressure crude tower reboiler (7), the upper part is connected to the degassing tank (12), the lower part is connected to the atmospheric pressure crude tower reboiler (6), and the bottom is connected to the negative pressure crude tower (2); The upper part of the negative pressure crude tower (2) is connected to the aldehyde removal tank (14) and the degassing tank (12), the lower part is connected to the reflux tank (15) and the negative pressure crude tower reboiler (7), and a wastewater outlet is arranged at the bottom; The top of the water washing tower (3) is connected to the negative pressure crude tower reboiler (7), the bottom is connected to the water washing tower reboiler (8), and the bottom is respectively connected to the bottom of the second refinement tower (4) and the bottom of the first refinement tower (5); The top of the second refining tower (4) is connected to the water washing tower reboiler (8), and a crude alcohol outlet pipe is arranged on the upper part and connected to the crude alcohol outlet pipeline of the first refining tower (5); The top of the first refinement tower (5) is connected to the second refinement tower reboiler (9), the lower part is connected to the first refinement tower reboiler (10), and the bottom is connected to the negative pressure crude tower reboiler (7); The atmospheric pressure crude tower reboiler (6) is provided with a wastewater outlet; A reboiler (10) of a fine tower is provided with a wastewater outlet; The preheater (11) is connected to the degassing tank (12) and the protein separator (16) through a pipeline; The aldehyde removal tank (14) is connected to the reflux tank (15).

4. The double crude and double refined water washing multi-tower differential pressure distillation system according to claim 3, characterized in that: The bottom temperature of the atmospheric pressure crude tower (1) is 100-110°C, and the top temperature is 90-100°C; the bottom temperature of the negative pressure crude tower (2) is 70-90°C, and the top temperature is 60-70°C; the bottom temperature of the water washing tower (3) is 90-100°C, and the top temperature is 80-100°C; the bottom temperature of the second refinement tower (4) is 110-120°C, and the top temperature is 90-110°C; the bottom temperature of the first refinement tower (5) is 140-160°C, and the top temperature is 110-130°C.

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