A method for processing alcohol-containing waste liquid by differential pressure distillation and heat coupling concentration

Abstract

The application provides a differential pressure distillation and heat coupling concentration aging method for treating alcohol-containing waste liquid, which comprises a differential pressure distillation method for treating alcohol-containing waste liquid raw materials and a heat coupling concentration aging method, and adopts an integrated device system comprising a crude distillation column, a dehydrocarbon column, a water washing column, a concentration column, a demethanol column and a recovery column. The alcohol-containing waste liquid raw materials are recycled and recovered in a high value mode, and high-quality products such as alcohol products and industrial alcohol, and derivative by-products such as distiller's yeast and biogas steam are prepared by a physical method. In addition, the process adopts one column for steam supply, is simple to operate in actual production, can save steam usage by more than 30%, and can reduce the amount of circulating water by more than 30%. Meanwhile, the differential pressure distillation and heat coupling are combined, the heat in the material conveying process in the differential pressure distillation is coupled to different links of the production system, the waste heat in the differential pressure distillation process is fully utilized, the energy consumption in the treatment process is reduced, and the purpose of truly realizing 'energy saving and cost reduction' is achieved.

Description

Technical Field

[0001] This invention belongs to the field of resource recovery and high-value purification and recycling of base wine aging and wine waste liquid, specifically involving a differential pressure distillation and thermal coupling concentration aging method for treating alcohol-containing waste liquid. Background Technology

[0002] Currently, the base liquor produced by sauce-flavored liquor enterprises generally has a high ethyl acetate content, requiring it to be stored for 3-5 years or more before blending. Furthermore, according to traditional production processes, after distillation, the yellow slurry from the fermentation pits and the water from the bottom of the distillation kettles are directly treated as wastewater and discharged after environmental protection facilities. Generally, the yellow slurry refers to the yellow seepage water from the mash in the fermentation pits of strong-flavored liquor. It contains 1-2% residual starch, 0.3-0.7% residual sugar, 4-5% (v / v) alcohol, as well as acetic acid, humic substances, and autolysates from yeast cells. The yellow slurry is quite acidic, with an acidity of around 5 degrees, and also contains some domesticated caproic acid bacteria and precursors to the aroma of baijiu. The current process of treating the yellow slurry and the water from the bottom of the distillation kettles as wastewater and discharging them after environmental treatment results in the waste of a large amount of recyclable low-alcohol liquor "grain," and the environmental treatment costs are extremely high, making it very difficult to meet emission standards.

[0003] The existing Chinese invention patent 200910194089.9 discloses a six-tower differential pressure distillation device and process for producing premium edible alcohol. The device uses a crude distillation tower, a water washing tower, a rectification tower, a methanol tower, a recovery tower, and a crude auxiliary tower to produce premium edible alcohol. It adds a crude auxiliary tower before the crude distillation tower in the traditional five-tower differential pressure distillation process to concentrate the liquor in the crude distillation tower and then reflux it to the crude distillation tower. The concentrated wastewater without alcohol is discharged to the outside. The raw material used by this system and process is mature mash. The purpose of the device and process is to produce premium edible alcohol. The treatment of yellow water and water at the bottom of the distillation kettle is not considered. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid.

[0005] This invention provides a differential pressure distillation and thermal coupling concentration aging method for treating alcohol-containing waste liquid, which is used to recover and purify base liquor and raw materials such as yellow water and bottom waste liquid containing alcohol in a resource-based manner. The method adopts an integrated device system including a crude distillation tower, a dehydrocarbonation tower, a water washing tower, a concentration tower, a methanol removal tower and a recovery tower.

[0006] The differential pressure distillation method includes the following steps: The raw liquor is preheated in a preheater and fed into the top of a crude distillation column. After being heated in the column, the liquid vapor rises and is discharged from the top, while the waste liquid is discharged from the bottom and transported to the wastewater treatment section. The liquid vapor is condensed and then sent to a dehydrocarbonation column for dehydrocarbonation to obtain a dehydrocarbonated liquid. This dehydrocarbonated liquid is then sent to a washing column for washing, and the alcohol content is controlled to 10%-15% V / V to obtain a diluted liquid. The diluted liquid is then subjected to water extraction and sent to a concentration column. An alcoholic liquid is taken from the Pasteurized zone at the top of the concentration column. This alcoholic liquid is sent to a methanol removal column to remove methanol, and the alcohol product is taken from the bottom of the methanol removal column. The fusel oil liquid taken from the concentration column is sent to a fusel oil separator for separation to obtain a diluted liquid. The diluted liquid is then sent to a recovery column for concentration and collection before being sent to a washing column.

[0007] The heat-coupled concentration and catalytic aging method includes the following steps: direct steam from a boiler or purchased steam is used to provide primary steam and heat the concentration tower via the reboiler; part of the feed vapor from the concentration tower is used to heat the water washing tower via the reboiler; part of the feed vapor is used to heat the methanol removal tower via the reboiler; steam discharged from the top of the water washing tower is used to heat the crude distillation tower via the first-stage reboiler; steam discharged from the top of the methanol removal tower is used to heat the crude distillation tower via the second-stage reboiler; feed vapor discharged from the top of the crude distillation tower is used to heat the waste liquid feedstock via the feed preheater; the recovery tower is heated by condensate flash steam and obtains direct steam from the concentration tower reboiler; the desalted feed vapor discharged from the top of the recovery tower is used to preheat the waste liquid feedstock via the feed preheater.

[0008] Preferably, the raw material preheater includes a primary preheater and a secondary preheater. After the feed liquid vapor is discharged from the top of the crude distillation column, it passes through the primary preheater to heat the waste liquid raw material. The light feed liquid vapor discharged from the top of the recovery column passes through the secondary preheater to preheat the waste liquid raw material. After being heated by the primary and secondary preheaters, the liquor raw material is fed from the top of the crude distillation column. While descending in the crude distillation column, it is heated by the bottom steam, forming feed liquid vapor that rises in the crude distillation column and separates from the waste liquid raw material. The rising feed liquid vapor enters the primary preheater, where it partially condenses while heating the primary preheater. The uncondensed feed liquid vapor enters the condenser for condensation.

[0009] Preferably, the wastewater discharged from the concentration tower passes through a desalination liquid preheater to heat the desalination liquid obtained from the water washing tower, and then enters a wastewater flash tank for impurity removal. Part of the resulting flash steam is sent to the water washing tower for water washing, and the other part is used to heat the dehydrocarbonized feed liquid before being discharged.

[0010] Preferably, the dehydrogenated feed liquid enters from the middle of the water washing tower and exchanges heat and mass with the flash steam of the wastewater from the concentration tower entering from the top of the water washing tower, so that the alcohol content of the dilute feed liquid at the bottom of the water washing tower is controlled at 10%-15% V / V, and the dilute feed liquid after water washing is extracted from the bottom of the tower.

[0011] Preferably, the diluted liquid drawn from the washing tower enters the feed plate at the bottom of the concentration tower. The first-stage impurities rise to the top of the tower with the alcohol vapor, and some impurities remain in the plate layer near the feed plate. The impurity liquid is drawn out from this plate layer and stored in the impurity liquid tank. The retained impurity liquid is drawn out in the middle of the concentration tower and transported to the washing tower.

[0012] Preferably, a concentrated liquid with an alcohol content of 96% V / V or higher is extracted from the top of the concentration tower as a semi-finished product. Multiple sampling points are set up on the concentration tower, and the sensory characteristics and composition of the liquid taken from each sampling point are tested. Based on the test results of the sampling points, the finished product is collected from the sampling points. The steam at the top of the tower is condensed and then completely refluxed after passing through the reboiler of the water washing tower, the reboiler of the methanol removal tower, and the reboiler of the crude distillation tower. The waste hot water from the bottom of the tower is used to preheat the dilute liquid coming out of the water washing tower before it enters from the top of the water washing tower.

[0013] Preferably, the impurity liquid and the dilute liquid after treatment by the fusel oil separator are transported to the recovery tower. The steam at the top of the recovery tower is condensed by the secondary preheater and then the industrial alcohol is extracted, and the remainder is returned to the recovery tower. The impurity liquid is extracted from the plate below the reflux layer and enters the water washing tower. The tail-stage impurity liquid is extracted from the plate above the feed layer and enters the fusel oil separator. The wastewater in the bottom of the recovery tower is heated and the impurity liquid extracted from the recovery tower is discharged.

[0014] Preferably, the methanol removal tower is a positive pressure distillation tower. The semi-finished product from the concentration tower enters from the middle of the methanol removal tower. The steam at the top of the concentration tower indirectly heats the methanol removal tower, causing the concentrated liquid in the methanol removal tower to be distilled a second time, and the finished alcohol product with an alcohol content of 96% V / V or higher is collected from the bottom area of ​​the methanol removal tower.

[0015] Preferably, the high-concentration organic waste liquid discharged from the bottom of the crude distillation tower is subjected to solid-liquid separation to obtain waste residue and clear liquid. The waste residue is processed into brewing yeast after being processed by an integrated regeneration device, and the clear liquid is transported to the sewage treatment plant and treated by combined fermentation to generate biogas steam, which is used to provide steam energy for the reboiler of the concentration tower. This forms a large-scale closed-loop "dual-carbon" path with zero discharge, zero pollution and near-zero energy consumption of high-concentration organic waste liquid.

[0016] Preferably, the processing parameters of each tower in the apparatus system used in the process of the present invention are as follows:

[0017] Crude distillation column: The vacuum pressure inside the column is -63kPa to -68kPa, the final cooling temperature is 35℃ to 40℃, and the alcohol concentration of the crude distillation product is 65% to 85% V / V.

[0018] Dehydrocarbon removal tower: The vacuum pressure inside the tower is -63kPa to -68kPa, and the final cooling temperature is 45℃-50℃;

[0019] Water washing tower: final cooling temperature is 68℃-75℃, bottom alcohol content is 10%-15% V / V, top alcohol content is 35%-45% V / V, and reflux ratio is 0.15-0.25.

[0020] Concentration tower: The pressure inside the tower is 230-240 kPa, the reflux ratio of the product to the reflux is 1:(5-7), the pH of the liquid in the concentration tower is controlled at 7-9, and the pH concentration of the concentration tower is adjusted by adding alkaline substances.

[0021] Methanol removal tower: final cooling temperature is 65℃-75℃, and the reflux ratio inside the tower is 1:(1.5~2.5);

[0022] Recovery tower: final cooling temperature is 65℃-75℃; alcohol concentration of the top product is ≥95% V / V, and the product accounts for 5%-10% of the total recovery tower volume.

[0023] This invention provides a differential pressure distillation and thermally coupled concentration and aging method for treating alcohol-containing waste liquid. This method focuses on the resource recovery and purification of alcohol-containing waste liquid raw materials, enabling their recycling and high-value, zero-carbon reuse. High-purity alcohol and industrial alcohol are produced through physical methods, along with byproducts such as yeast starter and biogas steam. This significantly improves the valuable recovery of waste throughout the entire life cycle of biological raw materials, realizing a closed-loop system concept of turning waste into treasure from the source of waste to the final disposal. Furthermore, the system's concentration tower uses a single-tower steam supply, simplifying operation and saving over 30% of steam usage in actual production. Simultaneously, reduced steam consumption also decreases recycled water usage by over 30%. The combined differential pressure distillation and thermal coupling utilizes the heat generated during material transport in differential pressure distillation to different stages of the production system, fully leveraging the waste heat from the distillation process to reduce energy consumption in treating alcohol-containing waste liquid, truly achieving the goal of "energy saving and cost reduction." Attached Figure Description

[0024] The above and other objects, features, and advantages of the invention will become clearer through a more detailed description of the preferred embodiments illustrated in the accompanying drawings. The same reference numerals denote the same parts throughout the drawings, and the drawings are not intentionally drawn to scale with actual dimensions; the focus is on illustrating the gist of the invention.

[0025] Figure 1 This is a schematic flowchart of a differential pressure distillation and thermally coupled concentration accelerator method for treating alcohol-containing waste liquid, provided in an embodiment of the present invention.

[0026] Figure 2This is a schematic diagram of a process for accelerating aging provided in another embodiment of the present invention. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0028] Please refer to Figure 1 ,in Figure 1 The solid line represents the material flow direction, and the dashed line represents the energy flow direction. The differential pressure distillation and thermally coupled concentration aging method for treating alcohol-containing waste liquid provided in this embodiment of the invention is used for the resource recovery and high-value purification of base liquor and alcohol-containing yellow water and bottom waste liquid raw materials. It includes a differential pressure distillation method and a thermally coupled concentration method for treating alcohol-containing waste liquid raw materials, employing an integrated device system including a crude distillation tower, a water washing tower, a dehydrocarbonization tower, a concentration tower, a methanol removal tower, and a recovery tower.

[0029] The differential pressure distillation method for treating alcohol-containing waste liquid feedstock includes the following steps: The alcohol-containing waste liquid feedstock is preheated in a feed preheater and then fed into the top of a crude distillation column. The feed preheater includes a primary preheater and a secondary preheater. After being heated in the crude distillation column, the feed liquid vapor rises and is discharged from the top of the column, while the waste liquid is discharged from the bottom of the crude distillation column and transported to the wastewater treatment section. The feed liquid vapor is condensed and then transported to a dehydrocarbonation column for dehydrocarbonation to obtain a dehydrocarbonated feed liquid. The dehydrocarbonated feed liquid is then transported to a water washing column for washing, and the alcohol content is controlled to 10%-15% V / V to obtain a diluted feed liquid. The alcohol content refers to the alcohol concentration, specifically the volume concentration. After water extraction, the diluted feed liquid is transported to a concentration column. Here, "diluted" refers to the alcohol concentration of the diluted feed liquid output at this stage being lower than that of the finished product. Alcohol feed is taken from the pasteurized zone at the top of the concentration tower. The alcohol concentration of the feed can be determined according to the product requirements, preferably with an alcohol content of 96% V / V or higher. The alcohol feed is then sent to a methanol removal tower to remove methanol. After methanol removal, the alcohol product is taken from the bottom of the methanol removal tower. The alcohol content of the alcohol product taken from the bottom of the methanol removal tower can also be determined according to the requirements, preferably with an alcohol content of 96% V / V or higher. The fusel oil feed taken from the concentration tower is sent to a fusel oil separator for separation to obtain a dilute feed. The dilute feed is sent to a recovery tower for concentration and then collected and sent to a water washing tower.

[0030] The heat-coupled concentration and catalytic aging method includes the following steps: Direct steam generated from the boiler or purchased externally is used to provide primary steam and heat to the concentration tower via the reboiler. Direct steam is water vapor generated by directly heating water. Part of the feed liquid vapor from the concentration tower is used to heat the water washing tower via the reboiler, and part of the feed liquid vapor is used to heat the methanol removal tower via the reboiler. Steam discharged from the top of the water washing tower is used to heat the crude distillation tower via the secondary reboiler, and steam discharged from the top of the methanol removal tower is used to heat the crude distillation tower via the primary reboiler. Feed liquid vapor discharged from the top of the crude distillation tower is used to heat the waste liquid feedstock via the feed preheater. The recovery tower is heated by condensate flash steam and direct steam is obtained from boiler steam. Only a small amount of direct steam is needed. The desalted feed liquid vapor discharged from the top of the recovery tower is used to preheat the waste liquid feedstock via the feed preheater.

[0031] The alcohol-containing waste liquid feedstock enters the degassing section of the crude distillation tower after being preheated twice. The flash vapor is condensed and impurities are removed before entering the crude distillation temporary storage tank. The devastated waste liquid feedstock enters the crude distillation tower. The liquid vapor from the crude distillation tower is condensed by the waste liquid feedstock and circulating water before entering the crude distillation temporary storage tank. The liquid in the crude distillation temporary storage tank is pumped to the dehydrocarbonization tower by the liquid pump.

[0032] In this invention, the main functions of each column are as follows: the crude distillation column is mainly used to remove impurities such as acids, some esters, and fusel oils, while concentrating the waste liquid to an alcohol content of approximately 40% V / V; the water washing column washes the approximately 40% V / V feed liquid down to approximately 10% V / V. The reflux from the water washing column enriches high concentrations of methanol, fusel oils, total esters, and total aldehydes, turning a deep yellow-green color. This utilizes the principle that flavor substances are more volatile at low concentrations to remove various impurities, resulting in a significant reduction in impurity content in the diluted feed liquid after washing. The concentration column produces fusel oils and total esters as byproducts, and the content of fusel oils and total esters in the standard-grade product produced by the concentration column is significantly reduced. This means that the concentration column removes most of the fusel oils and total esters while concentrating the alcohol content of the diluted feed liquid, bringing the semi-finished product to a standard-grade alcohol level. The reflux enrichment of methanol, total aldehydes, and total esters in the methanol removal column indicates that, in addition to removing methanol, the methanol removal column further removes total aldehydes and total esters, processing the standard-grade product prepared by the concentration column into a higher grade. The liquid coming out of the recovery tower is rich in fusel oil and has a high total ester content. In other words, the recovery tower mainly removes fusel oil and some total esters, thus improving the recovery rate.

[0033] In addition, the inner walls of the crude distillation column, water washing column, dehydrocarbonization column, concentration column, methanol removal column, and recovery column in the embodiments of the present invention are made of copper. During differential pressure distillation, the copper material of the inner wall of the column will absorb some impurities, so that the recovery rate of the differential pressure distillation method in the embodiments of the present invention can reach more than 85%.

[0034] In this invention, the feed preheater includes a primary preheater and a secondary preheater. Feed vapor discharged from the top of the crude distillation column passes through the primary preheater to heat the waste feed. Dilute feed vapor discharged from the top of the recovery column passes through the secondary preheater to preheat the waste feed. The alcoholic beverage feed, after being heated by the primary and secondary preheaters, is fed from the top of the crude distillation column. The waste feed, while descending in the crude distillation column, is heated by the bottom steam, forming feed vapor that rises and separates from the waste feed. The rising feed vapor enters the primary preheater, where it partially condenses while heating the primary preheater. The uncondensed feed vapor enters the condenser for further condensation. The condensate is indirectly heated by the residual distillate from the concentration column and fed to the washing tower. However, some non-condensable gases are still sent to the washing tower for washing before being released into the atmosphere.

[0035] The wastewater discharged from the concentration tower passes through the desalination liquid preheater, which heats the desalination liquid obtained from the water washing tower. Then, it enters the wastewater flash tank for impurity removal. Part of the resulting flash steam is sent to the water washing tower for water washing, and the other part is used to heat the dehydrocarbonized liquid before being discharged.

[0036] The dehydrogenated feed liquid enters from the middle of the washing tower, where it exchanges heat and mass with the flash vapor from the concentration tower wastewater entering from the top of the washing tower. This maintains the alcohol content of the dilute feed liquid at the bottom of the washing tower at 10%-15% V / V. The washed dilute feed liquid is then drawn off from the bottom of the tower. At lower alcohol concentrations, n-propanol, fusel oil, and some esters have higher volatility coefficients and tend to move and accumulate at the top of the tower. The vapor at the top of the tower is partially refluxed after being condensed in the reboiler of the crude distillation tower, and partially sent to the fusel oil separator for oil separation.

[0037] In this embodiment, the dilute liquid drawn from the washing tower enters the feed plate at the bottom of the concentration tower. Primary impurities rise to the top of the tower with the alcohol vapor, while some impurities remain in the plates above the feed plate. The impurities are then drawn from these plates and stored in a impurity tank. The retained impurities are drawn from the middle of the concentration tower and transported to the washing tower. Taking an 80-layer concentration tower as an example, the dilute liquid from the washing tower enters at the 16th plate of the concentration tower. As it gradually concentrates, primary impurities such as methanol and aldehydes rise to the top of the tower with the vapor. Near the 40th plate, some higher-grade oils accumulate; this portion is then collected and transported to the washing tower. Primary impurities are removed by taking out a portion of the reflux liquid for industrial alcohol production.

[0038] A concentrated liquid with an alcohol content of 96% V / V or higher is extracted from the top of the concentration tower as a semi-finished product. Multiple sampling points are set up on the concentration tower, and the sensory characteristics and composition of the liquid sample taken from each sampling point are tested. Based on the test results of the sampling points, the finished product is collected from the sampling points. In a further preferred embodiment, multiple sampling points are set up in each of the crude distillation tower, dehydrocarbonization tower, water washing tower, concentration tower, methanol removal tower, and recovery tower. The samples collected from each sampling point in each tower are tested, and the sampling points whose test results meet the index requirements can be used as the collection points of the finished product. In the brewing industry, especially in the baijiu (Chinese liquor) brewing industry, alcoholic waste liquid mainly refers to the yellow water and water left over from the distillation kettle after brewing baijiu. In the baijiu industry, sensory characteristics are tested for the finished product because baijiu contains various flavor compounds that give it its aroma and other sensory characteristics. In the preferred embodiment, sampling points are set up at each tower to select the feed liquid with better sensory characteristics—that is, the feed liquid that retains more flavor compounds—and collect it as the finished product for subsequent blending of high-alcohol products to form blended liquor. The steam at the top of the tower is condensed and completely refluxed after passing through the reboiler of the water washing tower, the reboiler of the methanol removal tower, and the reboiler of the crude distillation tower. The waste hot water from the tower bottom preheats the diluted feed liquid from the water washing tower before it enters from the top of the water washing tower.

[0039] The diluted liquid after processing by the impurity liquid and fusel oil separator is sent to the recovery tower. The steam at the top of the recovery tower is condensed by the secondary preheater and then the industrial alcohol is extracted, while the remainder is returned to the recovery tower. The impurity liquid is extracted from the plate below the reflux layer and enters the water washing tower. The tail-stage impurity liquid is extracted from the plate above the feed layer and enters the fusel oil separator. The wastewater in the bottom of the recovery tower is heated and the impurity liquid extracted from the recovery tower is discharged.

[0040] The methanol stripping tower is a positive pressure distillation unit, generally operating under slightly positive pressure. Its heat source comes from the steam in the concentration tower. Increasing the reflux ratio in the methanol stripping tower can meet the requirements for methanol separation. The concentrated liquid from the concentration tower enters from the middle of the methanol stripping tower. The steam at the top of the concentration tower indirectly heats the methanol stripping tower, causing the concentrated liquid in the methanol stripping tower to undergo secondary distillation. The finished alcohol product with an alcohol content of 96% V / V or higher is collected from the bottom area of ​​the methanol stripping tower.

[0041] In this embodiment, the waste liquid discharged from the bottom of the crude distillation column is subjected to solid-liquid separation to obtain waste residue and clarified liquid. The waste residue can be processed to obtain yeast starter, and the clarified liquid is transported to a wastewater treatment plant for treatment and then used to provide steam for the reboiler of the concentration tower. Specifically, the waste residue is processed into yeast starter after being processed by an integrated regeneration device, and the clarified liquid is transported to a wastewater treatment plant for combined fermentation gasification to generate biogas steam, which is used to provide steam energy for the reboiler of the concentration tower. This forms a large-scale closed-loop "dual-carbon" pathway with zero discharge, zero pollution, and near-zero energy consumption of high-concentration organic waste liquid.

[0042] In this embodiment, the processing parameters of each tower in the apparatus system used in the process of the present invention are as follows:

[0043] Crude distillation column: The vacuum pressure inside the column is -63kPa to -68kPa. Excessive vacuum pressure will draw impurities from the bottom of the column into the column, affecting the feed quality. Insufficient vacuum will raise the column temperature and disrupt the heat balance. Appropriately reducing the vacuum level and minimizing the distillation of impurities from the bottom is recommended. The final cooling temperature is 35℃-40℃. Increasing the temperature is beneficial for impurity removal, but excessively high temperatures will cause alcohol loss due to vacuum issues. The alcohol concentration of the crude distillate is 65%-85% V / V. Increasing the concentration in the crude distillation column is beneficial for impurity removal, but excessive reflux will result in alcohol loss due to insufficient column capacity.

[0044] Dehydrocarbon removal tower: The vacuum pressure inside the tower is -63kPa to -68kPa, and the final cooling temperature is 45℃ to 50℃; the effects of the vacuum pressure and final cooling temperature in the dehydrocarbon removal tower are the same as those in the crude distillation tower.

[0045] Water washing tower: The final cooling temperature is 68℃-75℃, the alcohol content at the bottom of the tower is 10%-15% V / V, and the alcohol content at the top of the tower is 35%-45% V / V. Increasing the water washing volume is beneficial for removing impurities. The reflux ratio inside the tower is 0.15-0.25. Only a sample needs to be collected at the final cooling stage. The more impurities removed by the final cooling stage, the better the product quality.

[0046] Concentrator: The pressure inside the tower is 230-240 kPa. The reflux ratio of the collected product to the reflux is 1:(5-7). Increasing the reflux ratio can improve product quality. The pH of the feed liquid in the concentration tower is controlled between 7 and 9. The pH concentration of the concentration tower is adjusted by adding alkaline substances, such as sodium hydroxide solution (3%-5% concentration). Adding alkali can increase the oxidation time. The alkaline substances will react with sulfides to form complexes, which are then discharged as waste, improving the taste. However, excessive alkali and esters will cause saponification, preventing the foaming tower from operating.

[0047] Methanol removal tower: The final cooling temperature is 65℃-75℃, and the reflux ratio inside the tower is 1:(1.5~2.5). Only the final cooling needs to produce some residue. The more impurities removed by the final cooling, the better the product quality.

[0048] Recovery tower: The final cooling temperature is 65℃-75℃; the alcohol content of the product collected at the top of the tower is ≥95% V / V, and the product accounts for 5%-10% of the total recovery tower volume. Returning the product to the crude distillation temporary storage tank and then back into the crude distillation tower for rectification and impurity removal is better than returning it to the next tower, the water washing tower. Using all industrial alcohol for product removal is optimal, but an increase in industrial alcohol will lead to a decrease in the recovery rate.

[0049] The waste liquid raw material contains lactic acid, which can cause the product to become acidic and fail to meet factory or industry standards. Therefore, lactic acid needs to be removed during waste liquid treatment. Lactic acid has a boiling point of around 120°C. In this embodiment, by controlling the final cooling temperatures of the crude distillation column, dehydrocarbonization column, water washing column, concentration column, methanol removal column, and recovery column, especially for the crude distillation column, a lower temperature is used to ensure that the lactic acid never reaches its boiling point during the waste liquid treatment process. This means that the lactic acid remains in a liquid solution throughout the process and is ultimately discharged from the crude distillation column along with the waste liquid, preventing it from entering the subsequent distillation system. Lowering the temperature of each column, while still meeting the requirements for differential pressure distillation of the alcohol-containing waste liquid, helps remove lactic acid and other high-boiling-point impurities, thereby improving the product grade.

[0050] This invention provides a differential pressure distillation and thermally coupled concentration and aging method for treating alcohol-containing waste liquid. This method focuses on the resource recovery and purification of alcohol-containing waste liquid raw materials, enabling their recycling and high-value, zero-carbon recovery. High-purity alcohol and industrial alcohol are produced through physical methods, along with byproducts such as yeast starter and biogas steam. This significantly improves the valuable recovery of waste throughout the entire life cycle of biological raw materials, realizing a closed-loop system concept of turning waste into treasure from the source of waste to the final disposal. Furthermore, the system's concentration tower uses a single-tower steam supply, simplifying operation and saving over 30% of steam usage in actual production. Simultaneously, the reduced steam consumption also reduces circulating water usage by over 30%. The combined differential pressure distillation and thermal coupling utilizes the heat generated during material transport in differential pressure distillation to different stages of the production system, fully leveraging the waste heat from the distillation process to reduce energy consumption in treating alcohol-containing waste liquid, truly achieving the goal of "energy saving and cost reduction."

[0051] The apparatus system utilized in this invention can also be used in the base liquor aging process, specifically a single-tower purification and aging process. The raw liquor is directly fed into a concentration tower, which is indirectly heated by boiler steam. After concentrating and purifying the raw liquor, different sections of the tower yield ethyl acetate liquor, ethyl hexanoate-containing liquor, 65%–70% baijiu (Chinese white liquor), and low-boiling-point liquor containing acetaldehyde and methanol. The ethyl hexanoate-containing liquor and ethyl acetate liquor can be blended with 65%–70% baijiu in different proportions to obtain a 65%–70% finished baijiu blend. The 65%–70% baijiu directly obtained from the concentration tower represents the completed aging process. By accelerating the aging of base liquor, the circulation time of products in the liquor industry can be expedited.

[0052] To verify the differential pressure distillation and thermally coupled concentration-accelerating method for treating alcohol-containing waste liquid provided by this invention, a technical modification scheme for a 6-tower system distillation tower was carried out on a 6-tower system of a winery in Sichuan. The modification was carried out according to the scheme and parameters provided by this invention, and actual production verification was conducted. In this production verification, 30 tons of tailings (alcohol content of 13%-18% V / V) from another winery were used as raw materials.

[0053] Table 1. Parameters of raw materials used in the verification.

[0054] Alcohol content (% Vol) 16.6 Acetaldehyde (mg / L) 179.1 Methanol (mg / L) 82.2 n-Propanol (mg / L) 143.7 Ethyl acetate (mg / L) 320.5 sec-Butanol (mg / L) 24.7 Isobutanol (mg / L) 53.5 Acetaldehyde (mg / L) - n-Butanol (mg / L) 2452.5 Isoamyl alcohol (mg / L) 166.8 Ethyl butyrate (mg / L) - Ethyl lactate (mg / L) 1715.7 Ethyl hexanoate (mg / L) - Total impurities (mg / L) 5138.6

[0055] Verification method steps:

[0056] 1. Pump 30 tons of tailings raw material into a 10 cubic meter mash tank, feeding material while pumping. The experimental distillery's feed rate is 40 cubic meters. 3 / h, the 30 tons of raw materials for the experiment can be completely fed in 1 hour. Due to the multi-tower structure, the material enters each tower at different times. In order to ensure that the sample is generated from the raw materials for the experiment, all the material is fed in at once, and the feeding time is 1 hour.

[0057] 2. Confirm the arrival time and residence time of materials in each tower, calculate the sampling time point, and take samples in 4 batches, for a total of 30 samples. The sample volume of each sample is 500ml, and the time covers the entire residence time in the tower. See Table 2 for the process sampling list.

[0058] Table 2 Process Sampling List

[0059]

[0060] 3. Sensory and physicochemical tests were performed on the sampled products, and comparisons were made according to the Chinese standard for edible alcohol products (GB10343-2008). Specific sample test data are as follows:

[0061] Table 3 Sampling and testing results of each intermediate tower

[0062]

[0063]

[0064] The recovery rate of tail wine is calculated by calculating the quality of the product obtained after raw material processing.

[0065] Table 4 Recovery Rate

[0066]

[0067] Furthermore, the finished products from the four samplings were compared according to the national standard (GB10343-2008) to obtain the following data:

[0068] Table 5 Product Testing Results

[0069]

[0070]

[0071] *: This requirement applies to alcohol made from cassava; there is no such requirement for alcohol made from other raw materials.

[0072] As shown in Table 5, the physicochemical testing indicators are as follows: oxidation time (only one group did not reach the premium grade), total aldehydes, methanol, and total acids are all at the excellent grade, failing to meet the premium grade standard. All other indicators meet the premium grade standard. The oxidation time can be reduced by adding alkali during the process. In this experiment, the winery's equipment was not equipped with an alkali addition device, but the 6-tower system of this invention will have a pre-installed alkali addition device; therefore, the oxidation time can also reach the premium grade.

[0073] Sensory indicators: In terms of aroma, it has no plastic smell like distillation tower products, but has the aroma of ethanol and no off-odors. In terms of taste, it is pure and sweet on the palate. The sensory quality can reach the level of superior grade alcohol.

[0074] The above experimental data shows that by recycling the tailings of the wine at the distillery according to the process of this invention, all samples reached the superior grade. After overall calculation, the recovery rate of the superior grade products reached 96%, and the overall recovery rate reached 98%. Furthermore, the distillery configuration used in this experiment was a technical modification of existing equipment, not a completely new facility built according to the process of this invention. Therefore, some indicators of the recovered products only reached the superior grade, while the remaining indicators reached the premium grade. Based on this experiment, if a new equipment system is built according to the process of this invention, it is entirely possible to process wine raw materials containing organic impurities into premium grade products.

[0075] The above are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid, used to recover and purify base liquor, alcohol-containing yellow liquid, and bottom waste liquid raw materials, characterized in that... An integrated system including a crude distillation tower, a hydrocarbon removal tower, a water washing tower, a concentration tower, a methanol removal tower, and a recovery tower is adopted; The differential pressure distillation method includes the following steps: The feedstock is preheated in a feed preheater and then fed into the top of a crude distillation column. After being heated in the column, the feed vapor rises and is discharged from the top, while the waste liquid is discharged from the bottom and transported to the wastewater treatment section. The feed vapor is condensed and then sent to a dehydrocarbonation column for dehydrocarbonation to obtain a dehydrocarbonated feed liquid. This dehydrocarbonated feed liquid is then sent to a washing column for washing, and the alcohol content is controlled to 10%-15% V / V to obtain a dilute feed liquid. The dilute feed liquid is then subjected to water extraction and sent to a concentration column. Alcohol feed liquid is taken from the Pasteurized zone at the top of the concentration column. This alcohol feed liquid is then sent to a methanol removal column to remove methanol, and the alcohol product is taken from the bottom of the methanol removal column. The fusel oil feed liquid taken from the concentration column is sent to a fusel oil separator for separation to obtain a dilute feed liquid. This dilute feed liquid is then sent to a recovery column for concentration and collection before being sent to a washing column. The heat-coupled concentration and catalytic aging method includes the following steps: Direct steam is used to provide primary steam and heat to the concentration tower via the reboiler; part of the feed vapor from the concentration tower is used to heat the water washing tower via the reboiler; part of the feed vapor is used to heat the methanol removal tower via the reboiler; steam discharged from the top of the water washing tower is used to heat the crude distillation tower via the secondary reboiler; steam discharged from the top of the methanol removal tower is used to heat the crude distillation tower via the primary reboiler; feed vapor discharged from the top of the crude distillation tower is used to heat the waste liquid feedstock via a feed preheater; the recovery tower is heated by condensate flash steam and direct steam is obtained from boiler steam; the desalinated feed vapor discharged from the top of the recovery tower is used to preheat the waste liquid feedstock via a feed preheater; the processing parameters of each tower are as follows: Crude distillation column: The vacuum pressure inside the column is -63kPa to -68kPa, the final cooling temperature is 35℃ to 40℃, and the alcohol concentration of the crude distillation product is 65% to 85% V / V. Dehydrocarbon removal tower: The vacuum pressure inside the tower is -63kPa to -68kPa, and the final cooling temperature is 45℃ to 50℃; Water washing tower: final cooling temperature is 68℃-75℃, bottom alcohol content is 10%-15% V / V, top alcohol content is 35%-45% V / V, and reflux ratio is 0.15~0.

25. Concentration tower: The pressure inside the tower is 230-240 kPa, the reflux ratio of the product to the reflux is 1:(5~7), the pH of the liquid in the concentration tower is controlled at 7~9, and the pH concentration of the concentration tower is adjusted by adding alkaline substances. Methanol removal tower: final cooling temperature is 65℃-75℃, and the reflux ratio inside the tower is 1:(1.5~2.5). Recovery tower: final cooling temperature is 65℃-75℃; alcohol concentration of the effluent at the top of the tower is ≥95% V / V, and the effluent accounts for 5%-10% of the total volume of the recovery tower.

2. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 1, characterized in that, The feed preheater includes a primary preheater and a secondary preheater. The feed liquid vapor discharged from the top of the crude distillation column passes through the primary preheater to heat the waste liquid feedstock. The desalinated feed liquid vapor discharged from the top of the recovery column passes through the secondary preheater to preheat the waste liquid feedstock. After being heated by the primary and secondary preheaters, the waste liquid feedstock is fed from the top of the crude distillation column. As it descends in the crude distillation column, it is heated by the bottom steam, forming feed liquid vapor that rises in the crude distillation column and separates from the waste liquid feedstock. The rising feed liquid vapor enters the primary preheater, where it partially condenses while heating the primary preheater. The uncondensed feed liquid vapor enters the condenser for condensation.

3. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 1, characterized in that, The wastewater discharged from the concentration tower passes through the desalination liquid preheater, which heats the desalination liquid obtained from the water washing tower. Then, it enters the wastewater flash tank for impurity removal. Part of the resulting flash steam is sent to the water washing tower for water washing, and the other part is used to heat the dehydrocarbonized liquid before being discharged.

4. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 3, characterized in that, After dehydrogenation, the dehydrogenated feed liquid enters from the middle of the water washing tower and undergoes heat and mass transfer with the flash steam of the wastewater from the concentration tower entering from the top of the water washing tower. This controls the alcohol content of the dilute feed liquid at the bottom of the water washing tower to be 10%-15% V / V. The dilute feed liquid after water washing is then drawn out from the bottom of the tower.

5. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 1, characterized in that, The diluted liquid drawn from the washing tower enters the feed plate at the bottom of the concentration tower. The first-stage impurities rise to the top of the tower with the alcohol vapor. Some impurities remain in the plate layer near the feed plate. The impurities are drawn out from this plate layer and stored in the impurity tank. The retained impurities are drawn out in the middle of the concentration tower and transported to the washing tower.

6. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 5, characterized in that, The liquid with an alcohol content of 96% V / V or higher is extracted from the top of the concentration tower as a semi-finished product. Multiple sampling points are set up on the concentration tower, and the sensory characteristics and composition of the liquid are tested at each sampling point. Based on the test results of the sampling points, the finished product is collected from the sampling points. The steam at the top of the tower is condensed and then completely refluxed after passing through the reboiler of the water washing tower, the reboiler of the methanol removal tower, and the reboiler of the crude distillation tower. The waste hot water from the bottom of the tower is used to preheat the dilute liquid coming out of the water washing tower before it enters from the top of the water washing tower.

7. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 5, characterized in that, The diluted liquid after processing by the impurity liquid and fusel oil separator is sent to the recovery tower. The steam at the top of the recovery tower is condensed by the preheater and then extracted to remove industrial alcohol, while the remainder is returned to the recovery tower. The impurity liquid is extracted from the plate below the reflux layer and enters the water washing tower. The tail-stage impurity liquid is extracted from the plate above the feed layer and enters the fusel oil separator. The wastewater in the bottom of the recovery tower is heated and discharged after removing the impurity liquid extracted from the recovery tower.

8. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 1, characterized in that, The methanol stripping tower is a positive pressure distillation tower. The semi-finished product from the concentration tower enters from the middle of the methanol stripping tower. The steam at the top of the concentration tower indirectly heats the methanol stripping tower, causing the liquid in the methanol stripping tower to be distilled a second time. The finished alcohol product with an alcohol content of 96% V / V or higher is collected from the bottom area of ​​the methanol stripping tower.

9. The differential pressure distillation and thermally coupled concentration method for treating alcohol-containing waste liquid as described in claim 1, characterized in that, The waste liquid discharged from the bottom of the crude distillation column is separated into solid and liquid residue to obtain waste residue and clear liquid. After treatment, the waste residue is used to obtain brewing yeast, and the clear liquid is sent to the sewage treatment plant for treatment and then used to provide steam for the reboiler of the concentration column.

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