CN102286544A - Method for cleanly producing starch-based fuel ethanol - Google Patents

Abstract

The invention relates to a clean production method of starch-based fuel ethanol, which includes the following steps: (1) liquefaction, (2) saccharification, (3) fermentation, (4) distillation and dehydration, and also includes comprehensive treatment of waste residues and recycling of by-products section. Among them, the liquefaction section adopts a low-pressure ejector continuous cooking process; the fermentation section adopts a semi-continuous fermentation system to keep the fermented mash in a flowing state and promote the uniform contact between yeast and mash; The combination tower with wine vapor heating on the top of the tower, the thermal coupling scheme of the crude distillation tower with wine vapor heating on the top of the combined tower, the obtained anhydrous ethanol is mixed to obtain denatured fuel ethanol, the quality meets the national standard GB18350-2001, and passed The waste residue comprehensive treatment and by-product recycling section recycles waste residue and useful substances in waste gas. In this method, the heat exchange network and water network of each production section are reasonably matched, and the goal of clean production with low material consumption and energy consumption and full resource utilization is realized.

Description

A kind of clean production method of starch-based fuel ethanol

technical field

The invention belongs to the field of biotechnology, and relates to a clean production method of starch-based fuel ethanol, in particular to a method for producing fuel ethanol by using starch-based raw materials such as corn, cassava, and sweet potato.

Background technique

The alcohol industry refers to the industry that uses cereals, potatoes, and molasses as raw materials to produce edible alcohol, industrial alcohol, and fuel ethanol through fermentation and distillation. It is an important basic raw material industry for the national economy. In recent decades, with the soaring price of oil and the rapid development of biotechnology, the use of biomass as raw material to produce fuel ethanol, which is used to replace vehicle fuel and reduce harmful substances in vehicle exhaust, has become more and more widely used.

In 2007, the total amount of wastewater discharged by my country's alcohol industry was about 400 million tons, and the annual discharge of COD was about 4 million tons, and BOD was about 2 million tons. It is one of the industries with high organic pollutant discharge. At the same time, the traditional fuel ethanol production method has problems such as low degree of automation, high material consumption and energy consumption, poor integration and optimization of the whole plant system, and there is still a big gap with the United States, Brazil and other fuel ethanol countries.

Contents of the invention

In order to solve the deficiencies in the above-mentioned prior art, the primary purpose of the present invention is to provide a clean production method for starch-based fuel ethanol, which is a method for producing fuel ethanol with starch-based raw materials such as corn, cassava, and sweet potato. The production method has the advantages of low material consumption and energy consumption, high degree of automation, and optimization of water and heat integration.

The object of the present invention is achieved through the following technical solutions: a clean production method of starch-based fuel ethanol, the main process flow of which is: starchy raw material→liquefaction→saccharification→fermentation→distillation→dehydration→fuel ethanol, as shown in the figure 1.

A clean production method of starch-based fuel ethanol, the production method is mainly realized through the following sections:

(1) Liquefaction: Mix and stir the starchy raw material with water and α-amylase evenly to obtain a slurry with a dry matter content of 20% to 34%, preheat it to 70-85°C and send it to the pre-liquefaction tank, and stir Evenly, at the same time, heat the slurry to 80-90°C, stir to make the insoluble substances in the mixed slurry reach a stable suspension state, and then carry out low-pressure steam jet liquefaction, the discharge temperature is 100-110°C, and then at 100-110°C Keep it for 1-2 hours for cooking and slaking, cool down the obtained matured mash to 65-80° C., and then perform flash cooling to obtain liquefied mash.

The starchy raw material is starch granules obtained by crushing one of corn, cassava and sweet potato with a starch content of 60% to 70% and a moisture content of 10% to 20% to an average particle size of 1 to 3 mm; The dosage of the above-mentioned α-amylase is calculated according to 1.5-2.0kg/t fuel ethanol product.

The operating pressure of the flash tank used for the flash cooling is -90 to -60kPa; the temperature of the flash steam obtained after flash evaporation is 50 to 70°C, and the flash steam is condensed and used as water for the liquefaction section.

The liquefaction section adopts a continuous cooking process of low-pressure steam injection followed by cooking, so that the mixed powder slurry is heated evenly, and the starch-based raw materials are thoroughly gelatinized. Compared with the high-temperature cooking process, the starch wine yield can be increased by 0.5%, and energy can be saved by 30%. The heat released from the temperature of the aged mash from 100-110°C to 65-80°C is used to heat the slurry before it is sent into the liquefaction tank, so as to realize full utilization of energy; the slurry is sent to the pre-liquefaction After tanking, the residence time in the tank is 20-50 minutes.

(2) Saccharification: Use sulfuric acid to adjust the pH value of the liquefied mash in the saccharification tank to 4.0-4.5, and add α-1,4-glucose hydrolase while stirring. Afterwards, heat preservation at 50-70°C for 30-60 minutes for saccharification; the liquefied mash after saccharification is cooled to 28-32°C to obtain saccharified mash, which is sent to the fermentation section.

The cooling of the liquefied mash after saccharification uses a two-stage cooler, which is cooled step by step, and the cooler is one of a spiral plate cooler and a plate cooler.

(3) Fermentation: a semi-continuous fermentation process is adopted, and one distiller's mother tank and n fermentation tanks are used for joint fermentation. The fermentation process is as follows: firstly add mash, active dry yeast and urea into the distiller's mash tank, stir evenly, then proliferate and ferment, the obtained distiller's mash is mixed with the remaining mash into the 1# continuous fermentation tank, When it is full, it will flow into 2# continuous fermenter naturally. After 2# continuous fermenter is full, it will flow into 3# continuous fermenter naturally. After 3# continuous fermenter is full, it will flow into 4# intermittent fermenter from 3# continuous fermenter. After the 4# batch fermenter is full, the 3# continuous fermenter is diverted to the 5# batch fermenter, and the 5#~n# batch fermenter is filled one by one from the 3# continuous fermenter according to this step, and then batch fermentation is carried out , after the end of the fermentation, the fermented mature mash is obtained.

Said n=6～10, 1～3# is a continuous fermenter, wherein the mash fermentation time is 24～30h, temperature is 30～33 ℃, 4～n# tank is a batch fermenter, wherein the mash fermentation The time is 35-45 hours, and the temperature is 30-36°C.

The quality of the saccharification mash added in the wine mother tank is 30% to 40% of the total mass of the saccharification mash obtained in section (2); The quality of the product is calculated as 1-3kg/t fuel ethanol product; the temperature for multiplication and fermentation in the distiller's mother tank is 28-32°C, and the time is 10-12h.

The _CO2 produced from the fermentation process of the distiller's mother tank and fermenter in the fermentation section and the _CO2 discharged from the degassing section of the crude distillation tower in section (4) jointly enter the scrubber to recover carbon dioxide.

The fermentation section adopts a semi-continuous fermentation process, and the fermented mash is in a flowing state, which can promote the uniform contact between the yeast and the mash, facilitate the discharge and recovery of CO ₂ , enhance the fermentation activity of the yeast, and improve the utilization rate of starch. The continuous fermenter for semi-continuous fermentation usually washes and sterilizes the tank once every 10 to 15 days, which saves auxiliary fermentation time and improves the utilization rate of the equipment.

(4) Distillation and dehydration: After preheating the fermented mature mash, introduce it into the degassing section of the crude distillation tower for degassing, and the CO2 released will enter the condenser of the degassing section with the alcohol vapor to condense, and discharge CO2 and non-condensable gas; The mature mash is divided into two streams, one of which accounts for 30% to 60% of the total mass flow rate, and is introduced into the stripping section of the crude distillation tower for preliminary distillation to obtain alcohol vapor and waste mash at the bottom of the crude distillation tower, and the alcohol vapor passes through the degassing section After condensing in the condenser, crude wine is obtained, which is introduced into the crude alcohol tank, and the waste mash is discharged from the bottom of the crude distillation tower; another stream of degassed mature mash is drawn from the side line at the bottom of the degassing section, and is preheated by the waste mash at the bottom of the combined tower Afterwards, it is introduced into the combined tower for further distillation to obtain the alcohol vapor at the top of the tower and the waste mash at the bottom of the combined tower; a part of the alcohol vapor at the top of the tower is introduced into the forced circulation reboiler of the crude distillation tower to condense, and the latent heat of condensation is used to heat the crude distillation tower. The condensate is used as the top reflux of the tower; another part of the alcohol vapor is introduced into the molecular sieve dehydration unit to obtain light wine and absolute ethanol product steam with a concentration of 60% to 80% V/V, the light wine is introduced into the crude alcohol tank, and the absolute ethanol product steam is condensed Afterwards, a fuel ethanol product is obtained, and denatured fuel ethanol finished product is obtained after adding a denaturant to the product, and the product quality meets the national standard GB18350-2001; the waste mash is discharged from the bottom of the combined tower;

The crude alcohol in the crude alcohol tank is preheated and introduced into a rectification tower for concentration and separation to obtain alcohol containing fusel oil, alcohol vapor at the top of the tower and residual water at the bottom of the tower respectively; the alcohol containing fusel oil is obtained from the After the top of the material layer is drawn out, it is cooled, then diluted with water and washed, and the lower layer removed after stratification is diluted and washed light wine with fusel oil, which enters the crude alcohol tank; the alcohol vapor at the top of the tower is introduced into the forced circulation reboiler of the combined tower to condense , the latent heat of condensation is used to heat the combined tower, and 40% to 70% of the mass flow rate of the condensate is returned to the top tray of the rectifying tower, and the rest of the condensed liquid is introduced into the combined tower for re-distillation; out from the bottom of the tower.

The fermented mature mash that enters the degassing section of the crude distillation tower is preheated by using the alcohol steam of the crude distillation tower, the waste mash at the bottom of the crude distillation tower, and the absolute ethanol product steam from the molecular sieve dehydration unit; After the fresh steam is fed into the bottom reboiler for heat supply, the condensed water obtained by the condensation of steam and the residual water at the bottom of the rectification tower are used for secondary preheating of the crude alcohol, part of which is returned to the boiler as reused water, and the other part is passed through Alcohol used to dilute fusel oils after cooling.

This section adopts a multi-effect thermal coupling rectification process. The thermal coupling scheme is: fresh steam heating rectification tower, rectification tower top alcohol steam heating combined tower, combined tower top alcohol steam heating crude distillation tower. Therefore, the utilization efficiency of heat energy is improved, and the consumption of circulating water is reduced, so as to achieve the effect of saving energy and reducing consumption.

As a kind of preferred scheme, the operating pressure of each distillation column, the tower top temperature are respectively:

The operating pressure at the top of the crude distillation tower is -70~-30kPa, and the temperature at the top of the tower is 55~75°C;

The operating pressure at the top of the combined tower is 0-100kPa, and the temperature at the top of the tower is 78-102°C;

The operating pressure at the top of the rectification tower is 300-520kPa, and the temperature at the top of the tower is 110-135°C.

The molecular sieve dehydration unit is composed of a molecular sieve adsorption tower and an analysis tower; the operating pressure of the molecular sieve adsorption tower is 0-150kPa; the operating pressure of the molecular sieve analysis tower is -80-0kPa.

The method for producing starch-based fuel ethanol of the present invention also includes a waste residue comprehensive treatment section and a by-product recycling section. Among them, the waste grains treatment is to separate the solids and liquids from the waste mash, and then treat the solids and liquids separately to convert them into feed, organic fertilizer or other by-products. Wastewater is discharged according to relevant national standards or directly used to irrigate farmland.

For example, if corn is used as raw material to produce alcohol, the waste residue treatment process is shown in Figure 4, which mainly consists of solid-liquid separation, evaporation concentration, drying, fan transportation, powder storage, packaging and other processes. The facilities and equipment mainly include: pumps, storage tanks , centrifuges, evaporation and concentration devices, dryers, fans, powder bins, packaging machines, finished product storage warehouses. The specific treatment steps are as follows: the first step is to recycle DDS in the wastewater to reduce the pollutants entering the environmental protection treatment system, including pressure filtration treatment of the waste liquid discharged from alcohol production, part of the clear liquid is reused, and part of it is sent to the evaporation concentration system to produce thick slurry , mix the thick slurry and filter residue, dry, granulate, and cool in a tube bundle dryer to obtain DDGS (fully dried distiller's grains); the second step of reclaimed water reuse: treat the secondary condensed water produced by the concentration of the clear liquid, and the treated reclaimed distiller's grains Water is used as water in the liquefaction section to realize the recycling of production water in the whole plant. After passing through the MVR mechanical steam recompression device, the waste heat gas from the evaporating and concentrating device has an improved grade and is used as a supplementary heat source for the evaporating and concentrating device itself, which can reduce 81% of the standard coal consumption in the waste residue treatment section.

If dried cassava is used as raw material to produce ethanol, the waste liquid treatment process mainly consists of separation, anaerobic digestion, aerobic biochemical treatment and other processes. Its facilities and equipment mainly include: storage tanks (pools), coolers, separators, biogas fermentation tanks (pools), pumps, biogas, aerobic and other effective treatment equipment. Wastewater is discharged according to relevant national standards or directly used to irrigate farmland.

The by-product recycling section includes liquid carbon dioxide recovery, biogas purification and precision separation of fusel oil, as shown in Figure 1. Its main purpose is to increase the added value of by-products, realize the maximization of resource utilization and economic benefits of the whole plant.

Description of drawings

Figure 1 is a general flow chart of the production of starch-based fuel ethanol.

Figure 2 is a flowchart of the liquefaction, saccharification and fermentation sections.

Figure 3 is a flow chart of the distillation and dehydration section.

Figure 4 is a flow chart of the waste residue comprehensive treatment section for producing fuel ethanol from cornstarch.

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

The process of producing fuel ethanol from corn starch is as follows:

37.7t/h corn (starch content is 65%, moisture content is 14%) is crushed to an average particle size of 2mm and sent to the pre-liquefaction tank, adding 84.6t/h mixing water, α-amylase 22kg/h, Obtain a slurry with a dry matter mass content of 26.5%. In order to mix the slurry evenly, the tank is equipped with an agitator, and the slurry is preheated to 78°C and then sent to a pre-liquefaction tank. In the pre-liquefaction tank, the above-mentioned slurry Heated by direct steam to 86°C, the stirrer drives the insoluble material into a stable suspension. When operating at full load, the residence time of slurry in the tank is 40min.

Then the slurry is pumped to the jet liquefier, and the outlet temperature of the steam jet is controlled to be 105° C. to obtain heated mash. The heated mash is sent to the cooking column and kept at 105°C for 1.5h for cooking and slaking. The matured mash is pumped to the slurry preheater. After preheating the slurry that has not entered the liquefaction tank, the temperature drops to 70°C and then enters the flash tank. The pressure of the flash tank is -75kPa. The temperature of the liquefied mash after flashing was 65°C. The generated flash steam is condensed and used as water for the liquefaction stage. The liquefied mash after flash cooling flows into the mash tank by gravity.

Use sulfuric acid to adjust the pH value to 4.2 in the saccharification tank (equipped with agitator), then add α-1,4-glucose hydrolase 43kg/h, keep warm at 65°C for 45min, and the mash after saccharification is pumped through two stages The plate cooler is cooled step by step until it is cooled to 31°C, and the obtained saccharification mash is sent to the fermentation section.

The fermentation section adopts a semi-continuous fermentation process, using 1 distiller's mother tank and 10 fermentation tanks for joint fermentation. When starting to put into production, after cleaning and sterilizing the distiller's mother tank, add mash which accounts for 35% of the total mash mass, the mass of active dry yeast added is calculated as 0.15kg/t fuel ethanol product, and the mass of urea added is calculated as 2kg/t fuel ethanol product After mixing evenly, carry out the dominant proliferation and fermentation of yeast, the temperature is 30°C, and the time is 12h; the obtained wine mash is mixed with the remaining saccharified mash and the mash flows into the 1# continuous fermentation tank, and after filling up, it naturally flows into the 2# Continuous fermentation tank, after 2# continuous fermentation tank is filled up, it will naturally flow into 3# continuous fermentation tank, after 3# continuous fermentation tank is filled up, it will flow into 4# intermittent fermentation tank from 3# continuous fermentation tank, and 4# batch fermentation tank will be filled up Finally, the 3# continuous fermenter is diverted to the 5# intermittent fermenter, and the 5#～10# intermittent fermenter is filled up one by one from the 3# continuous fermenter according to this step. The first three tanks kept the continuous main fermentation state, the fermentation time was 26h, and the temperature was 32°C. The fermentation time of 4#～10# batch fermentation tanks is 40h and the temperature is 35℃. After the fermentation is over, the fermented mash obtained is sent to the distillation and dehydration section, and the tank body is washed and sterilized before repeating the above operations.

The fermented mature mash (112t/h, 14% V/V, 32°C) is preheated in the degassing section of the crude distillation tower after being preheated in three stages by the alcohol steam of the crude distillation tower, the anhydrous ethanol product steam, and the waste mash at the bottom of the crude distillation tower. Degassing, the released CO2 enters the condenser of the degassing section with the alcohol vapor to condense, and discharges CO2 and non-condensable gas; the mature mash after degassing is divided into two strands, and one strand enters the stripping section of the crude distillation tower for preliminary distillation to obtain alcohol vapor After being condensed by the condenser in the degassing section, the crude wine is obtained and enters the crude alcohol tank. The obtained waste mash is discharged from the bottom of the crude distillation tower to the waste grain treatment section; Extracted, the flow rate is 67.2t/h, after being preheated by the waste mash in the combined column, it enters the combined column for re-distillation, and part of the alcohol vapor (95.8% V/V) obtained at the top of the column enters the forced circulation reboiler of the crude distillation column The latent heat of condensation is used to heat the crude distillation tower, and the condensate is used as a reflux at the top of the tower, and the waste mash is discharged from the bottom of the combined tower to the waste residue treatment section; the other part of the alcohol vapor is sent to the molecular sieve dehydration unit to obtain a concentration of (70 %V/V) of light wine and dehydrated ethanol product steam, light wine enters the crude alcohol tank, and the dehydrated ethanol product steam is condensed to obtain fuel ethanol product; the mass flow rate is 12.6t/h, and the product mass fraction is 99.2%, containing The water content is less than 0.5%, the acid content is 46ppm, which meets the national standard GB18350-2001, and the steam consumption in the distillation and dehydration section is 1.42t/t fuel ethanol.

The rectification tower operates under positive pressure conditions (520kPa), and the bottom reboiler of the rectification tower is fed with fresh steam for heating. The condensed water is preheated to 132°C in two stages, and then enters the rectification tower to concentrate and separate the crude wine to obtain alcohol containing fusel oil, alcohol vapor at the top of the tower and residual water at the bottom of the tower; the obtained alcohol containing fusel oil It is drawn from the top of the feed layer and then cooled, then diluted and washed with water, and the lower layer removed after layering is fusel oil diluted and washed light wine, which enters the crude alcohol tank; the obtained overhead alcohol vapor is introduced into the forced circulation reboiler of the combined tower The latent heat of condensation is used to heat the combined tower, and the condensate with a flow rate of 10.5t/h is refluxed to the top tray of the rectifying tower, and the rest is extracted into the combined tower for re-distillation, and residual water is drawn from the bottom of the rectifying tower.

The waste mash discharged from the bottom of the crude distillation tower and combined tower is filtered through a plate-and-frame filter press, 30% of the separated clear liquid is reused as water for the liquefaction section, and 70% is sent to the evaporation and concentration system to produce thick slurry. It is mixed with the filter residue from the filter press, dried, granulated and cooled by a tube bundle dryer to obtain DDGS feed with a moisture content of less than 11.5%. After passing through the MVR mechanical vapor recompression device, the waste heat gas from the outlet of the tube bundle dryer is improved in grade and used as a supplementary heat source for the evaporation and concentration device. The secondary condensed water produced by the concentration of clear liquid is used for sewage treatment, and the treated reclaimed water is used as water for the liquefaction section to realize the recycling of production water in the whole plant. The treatment section is shown in Figure 4. The total steam consumption of the whole plant is 3.45t/t of fuel ethanol (including waste residue comprehensive treatment section).

Example 2

The process of producing fuel ethanol with dried cassava as raw material is as follows:

20t/h dried cassava chips (68% starch content, 12% water mass content) were crushed to an average particle size of 3mm and sent to the pre-liquefaction tank, 40t/h mixing water was added, and α-amylase 12.5 kg/h to obtain a slurry with a dry matter content of 29.3%. In order to mix the slurry evenly, the tank is equipped with an agitator, and the slurry is heated to 75°C and then sent to the pre-liquefaction tank. In the pre-liquefaction tank, The above slurry is heated to 84°C by direct steam, and the stirrer promotes the insoluble matter to reach a stable suspension state. When operating at full load, the residence time of slurry in the tank is 30 minutes.

Then the slurry is pumped to the jet liquefier, and the outlet temperature of the steam jet is controlled to be 106° C. to obtain heated mash. The heated mash is sent to the cooking column and kept at 106°C for 2 hours for cooking and slaking. The matured mash is pumped to the slurry preheater. After preheating the slurry that has not entered the liquefaction tank, the temperature drops to 68°C and then enters the flash tank. The pressure of the flash tank is -80kPa. The temperature of the liquefied mash after flashing was 60°C. The generated flash steam is condensed and used as water for the liquefaction stage. The liquefied mash after flash cooling flows into the mash tank by gravity.

Use sulfuric acid to adjust the pH value to 4.5 in the saccharification tank (equipped with agitator), then add α-1,4-glucose hydrolase 25kg/h, keep warm at 60°C for 50min, and the mash after saccharification is pumped through two stages The plate cooler is cooled step by step until it is cooled to 29°C, and the obtained mash is sent to the fermentation section.

The fermentation section adopts a semi-continuous fermentation process, using 1 distiller's mother tank and 6 fermentation tanks for joint fermentation. At the beginning of production, after cleaning and sterilizing the distiller's mother tank, add mash which accounts for 32% of the total mash mass, the mass of active dry yeast added is calculated as 0.1kg/t fuel ethanol product, and the mass of urea added is calculated as 3kg/t fuel ethanol product , after mixing evenly, carry out the dominant proliferation and fermentation of yeast, the temperature is 28 ° C, and the time is 10 hours; the obtained wine mash and the remaining saccharification mash are mixed and the mash flows into the 1# continuous fermentation tank. After filling up, it naturally flows into the 2# Continuous fermentation tank, after 2# continuous fermentation tank is filled up, it will naturally flow into 3# continuous fermentation tank, after 3# continuous fermentation tank is filled up, it will flow into 4# intermittent fermentation tank from 3# continuous fermentation tank, and 4# batch fermentation tank will be filled up After that, the 3# continuous fermenter is diverted to the 5# batch fermenter. After the 5# batch fermenter is full, the 3# continuous fermenter is diverted to the 6# intermittent fermenter. The first three tanks were kept in the state of continuous main fermentation, the fermentation time was 28h, and the temperature was 33°C. The fermentation time of 4#~6# batch fermentation tanks is 38 hours and the temperature is 34°C. After the fermentation is completed, the fermented mash obtained is sent to the distillation and dehydration section, and the tank body is washed and sterilized before repeating the above operations.

The fermented mature mash (66.3t/h, 13.0% V/V, 33°C) enters the degassing section of the crude distillation tower after being preheated in three stages by the alcohol steam of the crude distillation tower, the steam of anhydrous ethanol product, and the waste mash at the bottom of the crude distillation tower Degassing, the released CO2 enters the condenser of the degassing section with the alcohol steam to condense, and discharges CO2 and non-condensable gas; the mature mash after degassing is divided into two shares, and one enters the stripping section of the crude distillation tower for preliminary distillation to obtain alcohol The steam is condensed by the condenser in the degassing section to obtain crude wine, which enters the crude alcohol tank, and the obtained waste mash is discharged from the bottom of the crude distillation tower to the waste grain treatment section; another stream of degassed mature mash is discharged from the bottom of the degassing section The side line is drawn out, the flow rate is 32t/h, and after being preheated by the waste mash in the combined column, it enters the combined column for re-distillation, and part of the alcohol vapor (96.0% V/V) obtained at the top of the column enters the forced circulation reboiler of the crude distillation column The latent heat of condensation is used to heat the crude distillation tower, and the condensate is used as a reflux at the top of the tower, and the waste mash obtained is discharged from the bottom of the combined tower to the waste residue treatment section; the other part of the alcohol vapor is sent to the molecular sieve dehydration unit to obtain a concentration of (65 %V/V) of light wine and absolute ethanol product steam, light wine enters the crude alcohol tank, and the fuel ethanol product is obtained after the absolute ethanol product steam is condensed; the mass flow rate is 6.95t/h, and the product mass fraction is 99.4%. The water content is less than 0.3%, the acid content is 39ppm, and meets the national standard GB18350-2001 for denatured fuel ethanol. The steam consumption in the distillation and dehydration section is 1.45t/t fuel ethanol.

The rectification tower operates under positive pressure conditions (480kPa), and the reboiler at the bottom of the rectification tower is fed with fresh steam for heating. The condensed water is preheated to 132°C in two stages, and then enters the rectification tower to concentrate and separate the crude wine to obtain alcohol containing fusel oil, alcohol vapor at the top of the tower and residual water at the bottom of the tower; the obtained alcohol containing fusel oil It is drawn from the top of the feed layer and then cooled, then diluted and washed with water, and the lower layer removed after layering is fusel oil diluted and washed light wine, which enters the crude alcohol tank; the obtained overhead alcohol vapor is introduced into the forced circulation reboiler of the combined tower The latent heat of condensation is used to heat the combined tower, and the condensate with a flow rate of 10.5t/h is refluxed to the top tray of the rectifying tower, and the rest is extracted into the combined tower for re-distillation, and residual water is drawn from the bottom of the rectifying tower.

The treatment of waste mash discharged from the distillation dehydration system is mainly composed of separation, anaerobic digestion, aerobic biochemical treatment and other processes. Its facilities and equipment mainly include: storage tanks (pools), coolers, separators, biogas fermentation tanks (pools), pumps, biogas, aerobic and other effective treatment equipment. After the waste grains are treated by the above treatment process, the biogas generated is used for combustion to generate electricity, and the remaining waste water (COD value 197mg/L) is discharged according to relevant national standards. The total steam consumption of the main plant is 2.51t/t fuel ethanol.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the spirit, scope and content of the present invention.

Claims (10)

1. the clean preparation method of a starch base alcohol fuel is characterized in that comprising following workshop section:

(1) liquefaction: with starchy material and water and α-Dian Fenmei mixing and stirring, obtain dry biomass content and be 20%～34% powder slurry, send into pre-liquefied pot after being preheated to 70～85 ℃, stir, then the powder slurry is heated to 80～90 ℃, carry out low-pressure steam injection liquefaction again, drop temperature is 100～110 ℃, keep 1～2h to carry out the boiling slaking at 100～110 ℃ then, carry out flash cooling after the mash after the gained slaking is cooled to 65～80 ℃, obtain liquefied fermented glutinous rice;

(2) saccharification: the pH value of regulating liquefied fermented glutinous rice with sulfuric acid is 4.0～4.5, adds α-1 in the time of stirring, and 4-glucose hydrolysis enzyme, its consumption add back insulation 30～60min under 50～70 ℃ and carry out saccharification by 3.2～4.0kg/t process of alcohol products; Mash after the saccharification is cooled to 28～32 ℃ and obtains converted mash;

(3) fermentation: 30%～40% and active dry yeast and the urea of gained converted mash total mass in the workshop section (2) are added in the distiller's yeast jar, breed after stirring and ferment, the mixed mash of yeast wash that obtains and remaining converted mash flows into the 1# jar that continuously ferments, after filling it up with, naturally flow into the 2# jar that continuously ferments, 2# continuously ferments after jar fills it up with, naturally the inflow 3# jar that continuously ferments; 3# continuously ferment the jar fill it up with after, flow into 4# batch fermentation jar, after 4# batch fermentation jar is filled it up with, then change and flow to 5# batch fermentation jar by the 3# jar that continuously ferments, fill it up with the laggard fermentation of having a rest of 5#～n# batch fermentation jar, wherein n=6～10 by this step one by one in the ranks by the 3# jar that continuously ferments; After the fermentation ends, obtain the fermenting-ripening wine with dregs;

(4) distillation and dehydration: outgas the CO that deviates from introducing the topping still degassing stages after the preheating of fermenting-ripening wine with dregs ₂Enter with alcohol steam and to take off vapour section condenser condenses, discharge CO ₂And noncondensable gas; Ripe wine with dregs after the degassing is divided into two strands, one accounts for 30%～60% of total mass flow rate, introduce the topping still stripping section and carry out predistillation, obtain useless wine with dregs at the bottom of alcohol steam and the topping still tower, described alcohol steam obtains thick wine after taking off vapour section condenser condenses, introduce the crude alcohol jar, described useless wine with dregs is discharged by the topping still bottom; Ripe wine with dregs after another burst degassing is introduced combined column and is distilled once more from the side line extraction of degassing stages bottom after useless wine with dregs preheating at the bottom of the combination Tata, useless wine with dregs at the bottom of obtaining the cat head alcohol steam and making up Tata; Condensation in the forced circulating reboiler of described cat head alcohol steam part introducing topping still, condensation latent heat is used to heat topping still, and phlegma is as trim the top of column; Another part alcohol steam is introduced the molecular sieve dehydration unit, obtains light wine and dehydrated alcohol finished product steam that concentration is 60%～80%V/V, and light wine is introduced the crude alcohol jar, promptly obtains process of alcohol products behind the dehydrated alcohol finished product vapor condensation; Described useless wine with dregs is discharged by the combined column bottom;

Concentrate and separate introducing rectifying tower after the thick wine preheating in the crude alcohol jar, obtain containing the surplus water that heats up in a steamer at the bottom of alcohol, cat head alcohol steam and the tower of potato spirit respectively; After drawing from charging layer top, cools off by the described alcohol that contains potato spirit, dilute with water washing then, and the lower floor that shifts out after the layering is a potato spirit dilution washing light wine, enters the crude alcohol jar; Condensation in the forced circulating reboiler of described cat head alcohol steam introducing combined column, the latent heat of condensation is used for heating combined column, and 40%～70% of phlegma mass rate is back to rectifying tower top layer column plate, and all the other phlegmas are introduced combined column and are distilled once more; The surplus water that heats up in a steamer is drawn at the bottom of by the rectifying Tata at the bottom of the described tower.

2. the clean preparation method of a kind of starch base alcohol fuel according to claim 1, it is characterized in that: starchy material is for being 60%～70% with starch content in the described workshop section (1), and the moisture mass content is that a kind of median size that is crushed in 10%～20% corn, cassava and the Ipomoea batatas is the starch granules that 1～3mm obtains; The consumption of described α-Dian Fenmei is by 1.5～2.0kg/t process of alcohol products.

3. the clean preparation method of a kind of starch base alcohol fuel according to claim 1 is characterized in that: after the powder slurry was sent into pre-liquefied pot in the described workshop section (1), the residence time in jar was 20～50min; Mash after the described slaking is used for the powder slurry of sending into before the liquefied pot is heated from 100～110 ℃ of heats that are cooled to 65～80 ℃ of releases; The pressure of the flash tank that described flash cooling is used is-90～-60kPa, the flash steam temperature that obtains after the flash distillation is 50～70 ℃, after the flash steam condensation as liquefaction workshop section water.

4. the clean preparation method of a kind of starch base alcohol fuel according to claim 1, it is characterized in that: two-stage cooler is used in the cooling of the liquefaction mash in the described workshop section (2) after the saccharification, cool off step by step, water cooler is a kind of in spiral plate type and the plate cooler.

5. the clean preparation method of a kind of starch base alcohol fuel according to claim 1, it is characterized in that: the quality that adds active dry yeast in the described workshop section (3) in the distiller's yeast jar is by 0.1～0.15kg/t process of alcohol products, and the quality that adds urea is by 1～3kg/t process of alcohol products; The temperature of breeding in the distiller's yeast jar and fermenting is 28～32 ℃, and the time is 10～12h.

6. the clean preparation method of a kind of starch base alcohol fuel according to claim 1, it is characterized in that: 1-3# is the jar that continuously ferments in the described workshop section (3), the fermentation time of mash is 24～30h in jar, temperature is 30～33 ℃, 4-n# is the batch fermentation jar, the fermentation time of mash is 35～45h in jar, and temperature is 30～36 ℃.

7. the clean preparation method of a kind of starch base alcohol fuel according to claim 1 is characterized in that: the CO that produces during the fermentation from distiller's yeast jar and all fermentor tanks in the described workshop section (3) ₂And the CO that discharges from the topping still degassing stages in the workshop section (4) ₂Enter washing tower jointly and carry out the recovery of carbonic acid gas.

8. the clean preparation method of a kind of starch base alcohol fuel according to claim 1, it is characterized in that: in the described workshop section (4), the described fermenting-ripening wine with dregs that enters the topping still degassing stages is to utilize useless wine with dregs at the bottom of topping still alcohol steam, the topping still tower and carry out preheating from the dehydrated alcohol finished product steam of molecular sieve dehydration unit; Described rectifying tower feeds live steam by tower bottom reboiler and carries out heat supply, the vapour that the vapor generation condensation obtains after the heat supply coagulate at the bottom of water and the rectifying Tata surplus heat up in a steamer water thick wine carried out preheating after, a part is returned boiler as reuse water, and another part is used to dilute the alcohol that contains potato spirit after cooling.

9. the clean preparation method of a kind of starch base alcohol fuel according to claim 1 is characterized in that: working pressure, the tower top temperature of each distillation tower are respectively in the described workshop section (4):

Topping still cat head operation presses to-70～-30kPa, 55～75 ℃ of tower top temperatures;

Combined column cat head working pressure is 0～100kPa, 78～102 ℃ of tower top temperatures;

Rectifying tower cat head working pressure is 300～520kPa, 110～135 ℃ of tower top temperatures.

10. the clean preparation method of a kind of starch base alcohol fuel according to claim 1 is characterized in that: the molecular sieve dehydration unit in the described workshop section (4) is made up of adsorbing tower with molecular sieve and Analytic Tower; Described adsorbing tower with molecular sieve working pressure is 0～150kPa, and molecular sieve Analytic Tower working pressure is-80～0kPa.

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