A system for treating acetic acid fermentation waste liquor and a method thereof

Abstract

The application provides an acetic acid fermentation waste liquid treatment system and method, and belongs to the field of fermentation waste liquid treatment. The system comprises: a vinyl acetate synthesis device for reacting fermentation waste liquid with calcium carbide, wherein the vinyl acetate synthesis device is communicated with a fermentation waste liquid pipeline and a calcium carbide pipeline; a separation and recovery device for separating and recovering the reaction product of fermentation waste liquid and calcium carbide, wherein the separation and recovery device is communicated with the vinyl acetate synthesis device; wherein the separation and recovery device comprises a rough separation device, a vinyl acetate refining device, an acetic acid refining device, a butenal recovery device, an acetaldehyde recovery device and a methyl acetate recovery device. Through the reaction of calcium carbide and acetic acid in the fermentation waste liquid, vinyl acetate with high added value is generated, waste acid liquid in the fermentation process is recovered, and various by-products produced by the calcium carbide acetylene method can be purified and separated, so that the purpose of maximizing resource utilization and minimizing energy consumption is achieved.

Description

Technical Field

[0001] This application relates to the field of fermentation waste liquid treatment technology, and in particular to a system and method for treating acetic acid-containing fermentation waste liquid. Background Technology

[0002] The production of ethanol from carbon monoxide is a relatively new technology in recent years. Currently, steel plant converter gas (whose main component is carbon monoxide) is used as raw material, and the carbon monoxide in the gas is converted into clean energy fuel ethanol through microbial fermentation. However, the fermentation process produces a large amount of acetic acid. Excessive acetic acid can cause the pH of the fermentation water environment to be too low, which is toxic to the fermentation bacteria. Therefore, the fermentation section needs to discharge acidic waste liquid in a timely manner.

[0003] However, the production of ethanol from carbon monoxide is a relatively new technology. The acetic acid produced during fermentation is difficult to control and its recycling is not cost-effective, requiring significant financial and material resources and is time-consuming and labor-intensive. Currently, the direct treatment method involves adding an alkaline solution (usually ammonia) for acid-base neutralization to meet environmental standards before discharge, resulting in a significant waste of resources. Therefore, there is an urgent need to develop a high-value method for recovering acetic acid from acetic acid-containing fermentation wastewater. Summary of the Invention

[0004] This application provides a system and method for treating acetic acid-containing fermentation waste liquid to solve the problem of waste acid resource waste in acetic acid-containing fermentation waste liquid in the prior art.

[0005] In a first aspect, this application provides a system for treating acetic acid-containing fermentation waste liquid, the system comprising:

[0006] A vinyl acetate synthesis unit is used for the reaction of fermentation waste liquid with calcium carbide. The vinyl acetate synthesis unit is connected to the fermentation waste liquid pipeline and the calcium carbide pipeline.

[0007] A separation and recovery device is used to separate and recover fermentation waste liquid and calcium carbide reaction products. The separation and recovery device is connected to the vinyl acetate synthesis device. The separation and recovery device includes a crude separation device, a vinyl acetate refining device, an acetic acid refining device, a butenal recovery device, an acetaldehyde recovery device, and a methyl acetate recovery device.

[0008] Optionally, the coarse separation device includes:

[0009] The first distillation column is used to separate acetaldehyde. The inlet of the first distillation column is connected to the outlet of the vinyl acetate synthesis unit. The first distillation column is provided with a first bottom outlet and a first top outlet.

[0010] The second distillation column is used for the preliminary separation of vinyl acetate. The inlet of the second distillation column is connected to the first bottom outlet. The second distillation column is provided with a second bottom outlet and a second top outlet.

[0011] Optionally, the vinyl acetate refining apparatus includes:

[0012] The third distillation column is used to purify vinyl acetate. The inlet of the third distillation column is connected to the second top outlet. The third distillation column is provided with a third bottom outlet, a third top outlet and a third side outlet.

[0013] The first storage tank is used to collect and store vinyl acetate, and the inlet of the first storage tank is connected to the outlet on the third side.

[0014] An oil-water separator is used to separate the oil and water phases of the liquid flowing out from the top of a third distillation column. The oil-water separator is connected to the top outlet of the third distillation column and has a water phase outlet and an oil phase outlet.

[0015] The fourth distillation column is used to further refine vinyl acetate. The fourth distillation column is connected to the aqueous phase outlet and has a fourth bottom outlet and a fourth top outlet. The fourth bottom outlet is connected to the inlet of the third distillation column, forming an internal circulation system with the third distillation column.

[0016] Optionally, the acetic acid refining apparatus includes:

[0017] The fifth distillation column is used to refine acetic acid. The inlet of the fifth distillation column is connected to the second bottom outlet. The fifth distillation column is provided with a fifth bottom outlet, a fifth top outlet and a fifth side outlet.

[0018] The second storage tank is used to collect and store acetic acid, and the inlet of the second storage tank is connected to the outlet on the fifth side.

[0019] The third storage tank is used to collect and store the heavy components of the bottom liquid of the fifth distillation column, and the inlet of the third storage tank is connected to the outlet of the fifth bottom column.

[0020] Optionally, the butenal recovery device includes:

[0021] The sixth distillation column is an azeotropic distillation column used to recover butenal. The inlet of the sixth distillation column is connected to the fifth top outlet. The sixth distillation column is provided with a sixth bottom outlet and a sixth top outlet.

[0022] The fourth storage tank is used to collect and store butenal, and the inlet of the fourth storage tank is connected to the outlet of the sixth top.

[0023] Optionally, the acetaldehyde recovery device includes:

[0024] The seventh distillation column is used to recover acetaldehyde. The inlet of the seventh distillation column is connected to both the oil phase outlet and the first top outlet. The seventh distillation column is provided with a seventh bottom outlet, a seventh top outlet, and a seventh side outlet.

[0025] The fifth storage tank is used to collect and store acetaldehyde, and the inlet of the fifth storage tank is connected to the outlet of the seventh tank.

[0026] The sixth storage tank is used to collect and store vinyl acetate, and the inlet of the sixth storage tank is connected to the outlet of the seventh side.

[0027] Optionally, the methyl acetate recovery device includes:

[0028] The eighth distillation column is an intermittent operation used to recover methyl acetate. The inlet of the eighth distillation column is connected to the fourth top outlet. The eighth distillation column has an eighth bottom outlet and an eighth top outlet. The eighth bottom outlet is connected to a drainage ditch.

[0029] The seventh storage tank is used to collect and store methyl acetate, and the inlet of the seventh storage tank is connected to the outlet of the eighth storage tank.

[0030] Secondly, this application provides a method for treating acetic acid-containing fermentation waste liquid, wherein the method is applied to the system described in any embodiment of the first aspect, and the method includes:

[0031] The reaction product is obtained by reacting fermentation waste liquid with calcium carbide in a vinyl acetate synthesis unit;

[0032] The reaction products are passed into a separation and recovery device for separation and recovery.

[0033] Optionally, the separation and recovery of reaction products includes:

[0034] The reaction products were initially separated into acetaldehyde and vinyl acetate using a coarse separator.

[0035] The reaction products are purified and vinyl acetate is recovered using a vinyl acetate refining unit.

[0036] The reaction products are purified and acetic acid is recovered using an acetic acid purification unit;

[0037] The reaction products are separated and butenaldehyde is recovered using a butenaldehyde recovery device.

[0038] The reaction products are separated and acetaldehyde is recovered using an acetaldehyde recovery device;

[0039] The reaction products are separated and methyl acetate is recovered using a methyl acetate recovery device.

[0040] Optionally, the main product of the reaction is vinyl acetate, and the byproducts include acetylene, acetaldehyde, methyl acetate, methanol, water, butenal, and acetic acid; the fermentation waste liquid includes waste liquid generated from grain fermentation process and waste liquid generated from industrial tail gas fermentation process; the recovered vinyl acetate has a purity of 99.60%~99.99%.

[0041] The technical solutions provided in this application have the following advantages compared with the prior art:

[0042] This application provides a system for treating acetic acid-containing fermentation waste liquid. By reacting calcium carbide with acetic acid in the fermentation waste liquid, high-value-added vinyl acetate is generated. The waste acid liquid from the fermentation process is recovered, and various by-products produced by the calcium carbide acetylene method can be purified and separated, thereby maximizing resource utilization and minimizing energy consumption. Attached Figure Description

[0043] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of an acetic acid-containing fermentation waste liquid treatment system provided in an embodiment of this application;

[0046] Figure 2 A flowchart of a method for treating acetic acid-containing fermentation waste liquid provided in this application embodiment;

[0047] Figure label:

[0048] 1- Vinyl acetate synthesis apparatus;

[0049] 11-Fermentation waste liquid pipeline; 12-Calcium carbide pipeline connection;

[0050] 2-Separation and recovery device;

[0051] 21- Coarse separation device;

[0052] 211 - First distillation column; 212 - First bottom outlet; 213 - First top outlet; 214 - Second distillation column; 215 - Second bottom outlet; 216 - Second top outlet;

[0053] 22-vinyl acetate refining unit;

[0054] 2201 - Third distillation column; 2202 - Third bottom outlet; 2203 - Third top outlet; 2204 - Third side outlet; 2205 - First storage tank; 2206 - Oil-water separator; 2207 - Aqueous phase outlet; 2208 - Oil phase outlet; 2209 - Fourth distillation column; 2210 - Fourth bottom outlet; 2211 - Fourth top outlet;

[0055] 23-Acetic acid refining apparatus;

[0056] 231 - Fifth distillation column; 232 - Fifth bottom outlet; 233 - Fifth top outlet; 234 - Fifth side outlet; 235 - Second storage tank; 236 - Third storage tank;

[0057] 24-Butenal recovery unit;

[0058] 241 - Sixth distillation column; 242 - Sixth bottom outlet; 243 - Sixth top outlet; 244 - Fourth storage tank;

[0059] 25-acetaldehyde recovery device;

[0060] 251 - Seventh distillation column; 252 - Seventh bottom outlet; 253 - Seventh top outlet; 254 - Seventh side outlet; 255 - Fifth storage tank; 256 - Sixth storage tank;

[0061] 26-Methyl acetate recovery unit;

[0062] 261 - Eighth distillation column; 262 - Eighth bottom outlet, 263 - Eighth top outlet; 264 - Seventh storage tank. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0064] In this document, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing the present invention and its embodiments, and are not intended to limit the indicated devices, elements, or components to having a specific orientation, or to be constructed and operated in a specific orientation. Furthermore, some of the above terms may have other meanings besides indicating orientation or positional relationship; for example, the term "upper" may in some cases indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in the present invention according to the specific circumstances. In addition, the terms "installed," "set," "equipped with," "connected," and "linked" should be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral structure; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, elements, or components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0065] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0066] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0067] Figure 1 This is a schematic diagram of an acetic acid-containing fermentation waste liquid treatment system provided in an embodiment of this application;

[0068] Please see Figure 1 This application provides a system for treating acetic acid-containing fermentation waste liquid, the system comprising:

[0069] Vinyl acetate synthesis unit 1 is used for the reaction of fermentation waste liquid with calcium carbide. The vinyl acetate synthesis unit 1 is connected to fermentation waste liquid pipeline 11 and calcium carbide pipeline 12.

[0070] Separation and recovery device 2 is used to separate and recover fermentation waste liquid and calcium carbide reaction products. The separation and recovery device 2 is connected to the vinyl acetate synthesis device 1. The separation and recovery device 2 includes a coarse separation device 21, a vinyl acetate refining device 22, an acetic acid refining device 23, a butenaldehyde recovery device 24, an acetaldehyde recovery device 25, and a methyl acetate recovery device 26.

[0071] During fermentation, the microbial cells produce a large amount of acetic acid, which not only affects cell activity but also requires a large amount of ammonia for neutralization and pH adjustment. This application provides a high-value recovery system for acetic acid from fermentation waste liquid containing acetic acid by selecting CaC2 (calcium carbide) as a separation reagent and designing a process for separating a mixed solution of vinyl acetate. The reaction principle in a low-concentration acetic acid solution is as follows:

[0072] Main reaction equation

[0073] (1) Preparation of acetylene gas from calcium carbide: CaC2 + 2H2O → C2H2↑ + Ca(OH)2

[0074] (2) Acetylene gas reacts with acetic acid vapor at a certain temperature with the action of zinc acetate-activated carbon catalyst to synthesize vinyl acetate. The reaction equation is: C2H2 + CH3COOH → CH3COOCH=CH2

[0075] Main side reaction equations

[0076] (1) Formation of acetaldehyde

[0077] Vinyl acetate hydrolysis: CH3COOCHCH2 + H2O → CH3CHO + CH3COOH

[0078] (2) Formation of crotonaldehyde (butenaldehyde)

[0079] a. Formation from acetaldehyde: 2CH3CHO→CH3CH=CHCHO+H2O

[0080] b. Reaction of acetylene and acetaldehyde: C2H2 + CH3CHO → CH3CH=CHCHO

[0081] To obtain higher value-added vinyl acetate, the main technologies currently used in industrial production of vinyl acetate are the acetylene gas-phase process and the ethylene gas-phase process. Ethylene is relatively cheaper than acetylene, therefore the ethylene process dominates globally. However, in regions with abundant and relatively inexpensive calcium carbide or natural gas resources, the acetylene gas-phase process still holds some competitiveness. After comprehensive comparison, the most economical and cost-effective calcium carbide-acetylene gas-phase process was selected to recover acetic acid and separate and purify vinyl acetate. This involves refining and separating the reaction products—acetylene, acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid—and recovering the products.

[0082] In some embodiments, the coarse separation device 21 includes:

[0083] The first distillation column 211 is used to separate acetaldehyde. The inlet of the first distillation column 211 is connected to the outlet of the vinyl acetate synthesis unit 1. The first distillation column 211 is provided with a first bottom outlet 212 and a first top outlet 213.

[0084] The second distillation column 214 is used for the preliminary separation of vinyl acetate. The inlet of the second distillation column 212 is connected to the first bottom outlet 213. The second distillation column 214 is provided with a second bottom outlet 215 and a second top outlet 216.

[0085] The first distillation column is mainly used to remove acetaldehyde. The effluent from the top of the column, after condensation (mainly vinyl acetate and acetaldehyde), is fed to the seventh distillation column, which uses one total condenser and one partial condenser. The bottom liquid (mainly vinyl acetate and acetic acid) is fed to the second distillation column. The top effluent from the first distillation column contains acetaldehyde ≥ 95%, and the bottom liquid contains vinyl acetate ≥ 90%.

[0086] The second distillation column is for preliminary separation. The distillate (vinyl acetate) is fed to the third distillation column, and the bottoms liquid (acetic acid) is fed to the fifth distillation column. The top liquid of the second distillation column contains ≥95% vinyl acetate, and the bottoms liquid contains ≥90% acetic acid.

[0087] In some embodiments, the vinyl acetate refining apparatus 22 includes:

[0088] The third distillation column 2201 is used to purify vinyl acetate. The inlet of the third distillation column 2201 is connected to the second top outlet 216. The third distillation column 2201 is provided with a third bottom outlet 2202, a third top outlet 2203 and a third side outlet 2204.

[0089] The first storage tank 2205 is used to collect and store vinyl acetate, and the inlet of the first storage tank 2205 is connected to the third side outlet 2204.

[0090] Oil-water separator 2206 is used to separate the oil and water phases of the liquid flowing out from the top of the third distillation column 2201. The oil-water separator 2206 is connected to the third top outlet 2203 and is provided with a water phase outlet 2207 and an oil phase outlet 2208.

[0091] The fourth distillation column 2209 is used to further refine vinyl acetate. The fourth distillation column 2209 is connected to the aqueous phase outlet 2207. The fourth distillation column 2209 is provided with a fourth bottom outlet 2210 and a fourth top outlet 2211. The fourth bottom outlet 2210 is connected to the inlet of the third distillation column 2201, forming an internal circulation system with the third distillation column 2201.

[0092] The third distillation column refines vinyl acetate, with the middle side stream collecting the refined vinyl acetate at the highest point of the component's vapor phase distribution within the column. The overhead liquid, after passing through a condenser and oil-water separator (vinyl acetate), is fed into the fourth distillation column, while the bottom liquid is used for TDA recycling. The overhead liquid from the third distillation column contains ≥92% methyl acetate, and the bottom liquid contains ≥92% vinyl acetate.

[0093] The fourth distillation column is used to remove methyl acetate and further refine vinyl acetate. The bottom liquid (mainly vinyl acetate, recycled TDA) is fed to the third distillation column, and the overhead distillate (mainly methyl acetate) is fed to the eighth distillation column. The third and fourth distillation columns form an internal circulation system. The overhead liquid of the fourth distillation column contains ≥90% methyl acetate, and the bottom liquid contains ≥90% vinyl acetate.

[0094] In some embodiments, the acetic acid refining apparatus 23 includes:

[0095] The fifth distillation column 231 is used to refine acetic acid. The inlet of the fifth distillation column 231 is connected to the second bottom outlet 215. The fifth distillation column 231 is provided with a fifth bottom outlet 232, a fifth top outlet 233 and a fifth side outlet 234.

[0096] The second storage tank 235 is used to collect and store acetic acid, and the inlet of the second storage tank 235 is connected to the fifth side outlet 234;

[0097] The third storage tank 236 is used to collect and store the heavy components in the bottom liquid of the fifth distillation column 231. The inlet of the third storage tank 236 is connected to the outlet 232 of the fifth bottom column.

[0098] The fifth distillation column produces refined acetic acid, similar to the third distillation column. Refined acetic acid is collected via a side stream, and the top effluent (mainly acetic acid) is fed to the sixth distillation column. The bottom liquid is sent to the residue evaporator for recovery of heavy components. The top effluent from the fifth distillation column contains ≥90% butenal, and the bottom liquid contains ≥90% acetic acid.

[0099] In some embodiments, the butenal recovery device 24 includes:

[0100] The sixth distillation column 241 is an azeotropic distillation column used to recover butenal. The inlet of the sixth distillation column 241 is connected to the fifth top outlet 233. The sixth distillation column 241 is provided with a sixth bottom outlet 242 and a sixth top outlet 243.

[0101] The fourth storage tank 244 is used to collect and store butenaldehyde, and the inlet of the fourth storage tank 244 is connected to the sixth top outlet 243.

[0102] The sixth distillation column is an azeotropic distillation column. Process water is added from the top of the column, and butenal and acetic acid are collected from the top. The sixth distillation column (extraction): butenal ≥ 90%.

[0103] In some embodiments, the acetaldehyde recovery device 25 includes:

[0104] The seventh distillation column 251 is used to recover acetaldehyde. The inlet of the seventh distillation column 251 is simultaneously connected to the oil phase outlet 2208 and the first top outlet 213. The seventh distillation column 251 is provided with a seventh bottom outlet 252, a seventh top outlet 253 and a seventh side outlet 254.

[0105] The fifth storage tank 255 is used to collect and store acetaldehyde, and the inlet of the fifth storage tank 255 is connected to the seventh top outlet 253;

[0106] The sixth storage tank 256 is used to collect and store vinyl acetate, and the inlet of the sixth storage tank 256 is connected to the seventh side outlet 254.

[0107] The seventh distillation column separates acetaldehyde and vinyl acetate. It receives two feed streams: one from the upper oil phase of the oil-water separator in the third distillation column, and the other from the top distillate of the first distillation column. Acetaldehyde is collected from the top of the first column, and refined vinyl acetate is collected from the middle side stream. Seventh distillation column (extraction): Acetaldehyde ≥ 90%.

[0108] In some embodiments, the methyl acetate recovery device 26 includes:

[0109] The eighth distillation column 261 is an intermittent operation used to recover methyl acetate. The inlet of the eighth distillation column 261 is connected to the fourth top outlet 2211. The eighth distillation column 261 is provided with an eighth bottom outlet 262 and an eighth top outlet 263. The eighth bottom outlet 262 is connected to a trench.

[0110] The seventh storage tank 264 is used to collect and store methyl acetate, and the inlet of the seventh storage tank 264 is connected to the eighth top outlet 263.

[0111] The eighth distillation column operates intermittently, with feed coming from the overhead liquid of the fourth distillation column. Methyl acetate is collected from the top, and the bottom liquid is discharged into the drain. The overhead liquid of the eighth distillation column contains ≥90% methyl acetate, and the bottom liquid contains ≥90% H2O.

[0112] In some implementations, the number of trays, height of the column, spacing between trays, feed location, and feed temperature of the distillation column are all calculated rigorously to obtain the theoretically most energy-efficient and best-performing plate distillation column.

[0113] For example, the calculation steps are as follows: 1. Preliminary estimation: Use simplified calculation methods with clear partitioning whenever possible; however, based on the actual situation, all eight distillation columns are calculated using non-clear partitioning. 2. Select bubble point feed: Bubble point feed is unaffected by seasonal temperature variations that can cause column instability; ambient temperature feed may cause instability due to temperature changes. Bubble point feed ensures consistent gas-liquid load (liquid-to-gas ratio) between the rectifying and stripping sections, allowing for equal-diameter design (equal diameter for rectifying and stripping sections), which is easier to manufacture and design. Ambient temperature feed is more challenging. The bubble point and dew point temperatures can be obtained by processing the raw data. 3. The minimum theoretical plate number Nm can be obtained using the Finsker equation. 4. The minimum reflux ratio Rm can be obtained using the Entwood formula. 5. The theoretical plate number N can be calculated using the Gilliland equation. 6. The feed location is determined using the Finsker equation, which employs phase equilibrium equations, operating line equations, material balance equations, rectifying section equations, and stripping section equations. The feed location is where the ratio of the light to heavy critical components is minimized. 7. The actual number of trays can be derived from the overall column efficiency and the theoretical number of trays. Through rigorous chemical engineering calculations, the number of trays, column height, tray spacing, feed location, and feed temperature of the distillation column can be obtained.

[0114] In some implementations, the distillation unit includes crucial auxiliary equipment in addition to the column equipment, namely the condenser and reboiler. Performing a heat balance on the system allows for the determination of the heat load on these two devices, thereby calculating the consumption of the condensing and heating media, providing an important basis for selecting heat exchange equipment.

[0115] For example, the implementation steps are as follows: Taking the calculation and selection of the condenser for the first distillation column as an example; 1. Selection of fluid flow space; The top steam of the column is cooled with treated soft water. The cooling water flows through the tube side of the heat exchanger, and the distillate from column 1 flows through the shell side of the heat exchanger, which is beneficial for heat dissipation. 2. Finding and calculating the physical properties of the fluids; The outlet temperature of the cooling water is taken as 36℃, and the inlet temperature is taken as 30℃, and its qualitative temperature is (30+36) / 2=33℃. The inlet temperature of the substance being cooled is 60℃, and the outlet temperature is taken as 28℃, and its qualitative temperature is (60+28) / 2=44℃. Calculate the physical properties of the cooling water and the substance being cooled at this qualitative temperature. 3. Trial calculation and preliminary selection of the heat exchanger model; ① Calculate the heat load and cooling water consumption, ② Calculate the average temperature difference between the two fluids, ③ Calculate the heat exchange area. The heat exchanger selected after calculation can achieve the goal of energy saving. Furthermore, taking the calculation and selection of the reboiler for the first distillation column as an example: 1. Selection of fluid flow space: Saturated steam is selected to flow through the shell side of the heat exchanger, and the T0201 bottom liquid flows through the tube side. 2. Finding and calculating the physical properties of the fluids: The feed temperature of saturated steam is taken as 130℃, and the bottom liquid temperature as 111℃. 3. Trial calculation and preliminary selection of the heat exchanger model: ① Calculate the heat load and saturated steam consumption, ② Calculate the average temperature difference between the two fluids, ③ Calculate the heat exchange area. The reboiler selected through calculation can achieve the goal of energy saving.

[0116] In some implementations, the distillation column is a sieve tray column. To ensure that the selected equipment meets the optimal requirements of the production process technology, and is also highly efficient, a thorough study of the models, specifications, quantities, sources, and prices of the main and auxiliary equipment in the process flow must be conducted during equipment selection. These parameters must be compared to determine whether the equipment solution adequately meets the requirements of the building scale and the guarantee of product quality and production process requirements. The design and selection of equipment can reflect the advanced nature of the designed plant and the reliability of production. The product required in this case is refined vinyl acetate. The equipment model is selected based on the product quantity, material quantity, column diameter, column height, heat exchange area determined by process calculations, as well as the external conditions of process operation (temperature, pressure, vacuum, etc.) and the structural type and performance of the equipment. For example, 1. Find the surface tension of the liquid phase; find the surface tension of each component in the rectification section at the average rectification temperature, and use the formula to obtain the total surface tension; similarly, the total surface tension of the stripping section can be obtained. 2. Average density: Find the density of the rectification section at the average temperature of the rectification section, and combine it with the average density of the feed trays to obtain the average density of the rectification section at the rectification temperature; similarly, the average temperature of the stripping section can be obtained. 3. Gas-liquid load: The gas and liquid flow rates of the rectification and stripping sections. 4. Calculation of column diameter: ① Determination of the column diameter for the rectification section, ② Determination of the column diameter for the stripping section. Round the entire rectification column diameter according to the standard column diameter. 5. Number of manholes: Since the material does not require frequent cleaning, a manhole can be installed every 8-10 trays. 6. Top space HD: To facilitate the installation of manholes and minimize liquid entrainment, it is generally taken as 1.2 to 1.5 meters. 7. Manhole plate spacing HP: The height of the manhole center from the flat surface is generally 600-1250 mm. 8. Column height; top space (including manhole and end caps); bottom space (including one manhole); plate spacing HT; feed height HF; actual number of plates Np; one manhole is opened in the middle of the stripping section, number of manholes is n; plate spacing at the manhole is; skirt height, D is the column diameter; therefore, column height. After the distillation column equipment design, energy-saving, reliable, and efficient equipment can be obtained. Furthermore, the sieve plate distillation column is equipped with several layers of horizontal plates, with many small holes on the plates, shaped like a sieve; and is equipped with an overflow pipe or not. During operation, the liquid enters from the top of the column, descends through the overflow pipe (partially through the sieve holes) plate by plate, and accumulates a liquid layer on the plate. Gas (or vapor) enters from the bottom of the column, rises through the sieve holes, passes through the liquid layer, and bubbles out, so the two phases can fully contact and interact. The gas pressure drop is small, the liquid level difference on the plate is small; the plate efficiency is high. The thermosiphon reboiler is selected. The thermosiphon reboiler is actually a heat exchanger that heats the cold fluid by the thermal convection of the liquid.When the liquid in the reboiler is heated, it becomes a gas-liquid mixture with a lower density, flowing from the top into the bottom of the column. The liquid at the bottom of the column, being denser, automatically flows towards the reboiler. This creates a natural cycle: bottom of column – reboiler – top of column, continuously heating and vaporizing the liquid in the column. The amount of heat supplied in the reboiler is adjusted by changing the size of the heat exchange area. Increasing the condensate discharge increases the heat exchange area and heat supply, while decreasing the condensate discharge reduces the heat exchange area and heat supply. The condenser used is a shell-and-tube condenser, with the outer shell made of steel tubing at least 5mm thick, rust-proofed, and pressure-resistant up to 20 kg / cm². The heat exchange tubes are high-efficiency seamless copper tubes, pressure-resistant up to 10 kg / cm², with interchangeable end caps to change the direction of the water inlet. The water pipe flow has multiple loops, and the capacity of each condenser is matched with that of the compressor. The overall thermal conductivity should be within a tolerance of 0.00005 kcal / h·cm²℃. -1 Scaling factors should be minimized, condenser water pressure drop should not exceed 6.5 mAq, and straight-through water pipes should be easy to clean and maintain. An F-type centrifugal pump should be selected for the booster pump. F-type centrifugal pumps are used to transport corrosive liquids that do not contain solid particles, with a medium temperature of -20℃ to 105℃ and a pump inlet pressure not exceeding 6 kg / cm³. 2 This is to achieve the goals of thorough distillation and energy conservation.

[0117] In some implementations, the distillation process will also include design specifications for non-process components to ensure the design is feasible and that the process is safe and environmentally friendly.

[0118] For example, 1. Ensure safe production; provide the characteristics of the corresponding components and the selection principles for their safety countermeasures, and provide corresponding safety countermeasures and risk control. 2. Design reasonable and feasible public works; mainly including electrical facilities, water and steam facilities, oxygen supply, air and auxiliary gas facilities, and waste treatment facilities. Finally, the invention patent was simulated using the chemical production simulation software ASPEN. The simulation results are logical, and the design is efficient, energy-saving, and reasonable. The described method for treating and recovering acetic acid-containing fermentation waste liquid is a completely feasible method that achieves the goal of turning waste into treasure, with significant economic benefits and production efficiency. It can solve the problems of difficult pH control and waste acid resources during fermentation.

[0119] Figure 2 This is a flowchart of a method for treating acetic acid-containing fermentation waste liquid, provided as an embodiment of this application.

[0120] Please see Figure 2 This application provides a method for treating acetic acid-containing fermentation waste liquid, the method comprising:

[0121] S1. The reaction product is obtained by reacting fermentation waste liquid with calcium carbide in vinyl acetate synthesis unit 1.

[0122] In some embodiments, the main product of the reaction is vinyl acetate, and the byproducts include acetylene, acetaldehyde, methyl acetate, methanol, water, butenal, and acetic acid; the fermentation waste liquid includes waste liquid generated from grain fermentation processes and waste liquid generated from industrial tail gas fermentation processes.

[0123] S2. The reaction products are passed into the separation and recovery device 2 for separation and recovery of the reaction products.

[0124] In some embodiments, the separation and recovery of reaction products includes:

[0125] S21. The reaction products are initially separated into acetaldehyde and vinyl acetate by a coarse separator 21.

[0126] S22. The reaction product is purified and vinyl acetate is recovered by passing it through vinyl acetate refining unit 22.

[0127] In some embodiments, the recovered vinyl acetate has a purity of 99.60% to 99.99%.

[0128] For example, the purity of the recovered vinyl acetate can be 99.60%, 99.65%, 99.70%, 99.75%, 99.80%, 99.85%, 99.90%, 99.95%, 99.99%, etc.

[0129] S23. The reaction product is purified and acetic acid is recovered by acetic acid purification unit 23;

[0130] S24. The reaction product is separated and butenaldehyde is recovered by butenaldehyde recovery device 24;

[0131] S25. Separate and recover acetaldehyde from the reaction products using acetaldehyde recovery device 25;

[0132] S26. The reaction product is separated and methyl acetate is recovered by the methyl acetate recovery device 26.

[0133] Grain fermentation for ethanol, grain fermentation for other products, and industrial waste gas fermentation, especially the bio-fermentation of carbon monoxide to ethanol, easily generate large amounts of waste acid (acetic acid). This not only affects the activity of the microorganisms but also requires a large amount of ammonia water for neutralization and pH adjustment. By reacting calcium carbide with acetic acid in the fermentation waste liquid, high-value-added vinyl acetate is produced. The waste acid liquid from the fermentation process is recovered, and various by-products produced by the calcium carbide-acetylene method can be purified and separated, maximizing resource utilization and minimizing energy consumption. The acetylene method for synthesizing vinyl acetate has a stable source of raw materials, a mature and reliable process, and economical production costs. It has advantages over the domestic and international ethylene method markets in terms of raw material supply environment, product price, and domestic catalyst efficiency. Calcium carbide is relatively inexpensive in Southwest China; therefore, the calcium carbide-acetylene method is adopted. To further obtain vinyl acetate, high-value-added vinyl acetate is separated by distillation.

[0134] The present application is further illustrated below with reference to exemplary embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to industry standards. If there is no corresponding industry standard, then common international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0135] Example 1

[0136] This embodiment describes a method for treating and recovering high-value acetic acid-containing fermentation waste liquid. The recovery process utilizes the calcium carbide-acetylene method, while the separation process is distillation. Eight distillation columns are selected, all of which are sieve tray columns. The sieve tray spacing, installation height, and number of trays are determined by chemical engineering calculations. The bottom liquid of column 1 enters the second distillation column via a reboiler and a booster pump. The distillate from the top of the first distillation column enters the feed inlet of the seventh distillation column via a condenser and a booster pump. Acetaldehyde and vinyl acetate enter the seventh distillation column, primarily to obtain the byproduct acetaldehyde and the refined vinyl acetate. Sequential separation and purification are performed to achieve the goal of recovering fermentation waste acid using the calcium carbide-acetylene method and then obtaining high-concentration vinyl acetate through distillation separation.

[0137] For example, calcium carbide reacts with water to produce acetylene, which then reacts with acetic acid to produce the main product, vinyl acetate. During the main reaction, other side reactions also occur, with the main post-reaction components being acetylene, acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid. The first distillation column is mainly used to remove acetaldehyde. The effluent from the first column, after condensation (mainly vinyl acetate and acetaldehyde), is fed to the seventh distillation column, which uses one total condenser and one partial condenser. The bottom liquid (mainly vinyl acetate and acetic acid) is fed to the second distillation column. The second distillation column performs preliminary separation; the distillate (vinyl acetate) is fed to the third distillation column, and the bottom liquid (acetic acid) is fed to the fifth distillation column. The seventh distillation column separates acetaldehyde and vinyl acetate. It has two feed streams: one from the upper layer of the oil-water separator in the third distillation column, and the other from the raffinate phase in the first distillation column. Acetaldehyde is collected from the top of the column, and refined vinyl acetate is collected from the middle. The third distillation column refines vinyl acetate, with the middle side stream collecting refined vinyl acetate at the highest point of the component's vapor phase distribution within the column. The overhead stream (vinyl acetate) is fed to the fourth distillation column after passing through a condenser and oil-water separator, while the bottom liquid is used for TDA recycling. The fourth distillation column further refines vinyl acetate by removing methyl acetate. The bottom liquid (mainly vinyl acetate, used for TDA recycling) is fed to the third distillation column, while the overhead distillate (mainly methyl acetate) is fed to the eighth distillation column. The third and fourth distillation columns form an internal circulation system. The fifth distillation column refines acetic acid, similar to the third column, collecting refined acetic acid midway through. The overhead stream (mainly acetic acid) is fed to the sixth distillation column, while the bottom liquid is sent to the residue evaporator for recovery of heavy components. The sixth distillation column is an azeotropic distillation column, with process water added from the top, and butenal and acetic acid collected simultaneously from the top. The eighth distillation column operates intermittently, with feed coming from the top runoff of the fourth distillation column. Methyl acetate is collected from the top, while the bottom liquid is discharged into the drain. This achieves complete component separation, yielding high-concentration vinyl acetate.

[0138] Example 2

[0139] This embodiment further illustrates the technology. The number of distillation columns is determined based on the main components and their characteristics after the reaction. It mainly includes: 1. A coarse fractionation system; 2. A vinyl acetate refining system; 3. An acetic acid refining system; 4. An acetaldehyde recovery system; 5. A methyl acetate recovery system; 6. A butenal recovery system; and 7. A methyl acetate recovery system. This system is used to distill a multi-component solution containing vinyl acetate to extract and refine vinyl acetate.

[0140] For example, in a vinyl acetate synthesis unit, fermentation waste liquid is reacted with calcium carbide to obtain reaction products. Before entering the first distillation column, all components are determined to be acetylene, acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid. The distribution of components at the top and bottom of the column is determined, with acetaldehyde identified as the light key component, requiring a distillate concentration of 95%, and vinyl acetate as the heavy key component, requiring a bottom concentration of 90%. The feed to the second distillation column is the distillate from the first distillation column, initially separated, consisting of acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid; the light and heavy key components are selected as vinyl acetate and acetic acid, respectively. Based on the separation in the second distillation column, we understand that vinyl acetate mainly enters the third distillation column from the top for purification. The bottom liquid of the second distillation column mainly goes to the fifth distillation column for acetic acid purification. The feed components for the third distillation column are acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid. Methyl acetate is selected as the light key component and vinyl acetate as the heavy key component for the third distillation column. The liquid flowing from the top of the third distillation column, after passing through an oil-water separator, is sent to the fourth distillation column for feeding. The components of the fourth distillation column are methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid. Methyl acetate is selected as the light key component and vinyl acetate as the heavy key component for the fourth distillation column. The liquid flowing out from the top of the fourth distillation column, mainly containing methyl acetate, enters the eighth distillation column for separation. The feed components of the eighth distillation column are methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid. Here, methyl acetate is selected as the light key component and vinyl acetate is selected as the heavy key component, in accordance with the design requirements. The bottom liquid from the second distillation column, mainly composed of acetic acid, consists of acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid. It then reaches the fifth distillation column for separation. The fifth distillation column selects butenal as the light key component and acetic acid as the heavy key component. The sixth distillation column is mainly a recovery column for the fifth distillation column, primarily recovering low-concentration products. Its feed components are acetaldehyde, methyl acetate, methanol, vinyl acetate, water, butenal, and acetic acid; similarly, the sixth distillation column selects butenal as the light key component and vinyl acetate as the heavy key component. The seventh distillation column is the distillate from the first distillation column, mainly containing acetaldehyde and vinyl acetate, with all components being acetylene, acetaldehyde, methyl acetate, methanol, vinyl acetate, water, and butenal. The purpose of the seventh distillation column is primarily to obtain the product acetaldehyde; its light key component is acetaldehyde, and its heavy key component is vinyl acetate. Preliminary estimates suggest that high-concentration main products and by-products can be separated in each column design.

[0141] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A system for treating acetic acid-containing fermentation wastewater, characterized in that, The system includes: A vinyl acetate synthesis device (1) is used for the reaction of fermentation waste liquid with calcium carbide. The vinyl acetate synthesis device (1) is connected to the fermentation waste liquid pipeline (11) and the calcium carbide pipeline (12). A separation and recovery device (2) is used to separate and recover fermentation waste liquid and calcium carbide reaction products. The separation and recovery device (2) is connected to the vinyl acetate synthesis device (1). The separation and recovery device (2) includes a coarse separation device (21), a vinyl acetate refining device (22), an acetic acid refining device (23), a butenaldehyde recovery device (24), an acetaldehyde recovery device (25), and a methyl acetate recovery device (26). The coarse separation device (21) includes: The first distillation column (211) is used to separate acetaldehyde. The inlet of the first distillation column (211) is connected to the outlet of the vinyl acetate synthesis device (1). The first distillation column (211) is provided with a first bottom outlet (212) and a first top outlet (213). The second distillation column (214) is used for the preliminary separation of vinyl acetate. The inlet of the second distillation column (214) is connected to the first bottom outlet (212). The second distillation column (214) is provided with a second bottom outlet (215) and a second top outlet (216). The vinyl acetate refining apparatus (22) includes: The third distillation column (2201) is used to purify vinyl acetate. The inlet of the third distillation column (2201) is connected to the second top outlet (216). The third distillation column (2201) is provided with a third bottom outlet (2202), a third top outlet (2203) and a third side outlet (2204). The first storage tank (2205) is used to collect and store vinyl acetate, and the inlet of the first storage tank (2205) is connected to the third side outlet (2204); An oil-water separator (2206) is used to separate the oil and water phases of the liquid flowing out from the top of the third distillation column (2201). The oil-water separator (2206) is connected to the third top outlet (2203). The oil-water separator (2206) is provided with a water phase outlet (2207) and an oil phase outlet (2208). The fourth distillation column (2209) is used to further purify vinyl acetate. The fourth distillation column (2209) is connected to the aqueous phase outlet (2207). The fourth distillation column (2209) is provided with a fourth bottom outlet (2210) and a fourth top outlet (2211). The fourth bottom outlet (2210) is connected to the inlet of the third distillation column (2201) and forms an internal circulation system with the third distillation column (2201).

2. The system according to claim 1, characterized in that, The acetic acid refining apparatus (23) includes: The fifth distillation column (231) is used to refine acetic acid. The inlet of the fifth distillation column (231) is connected to the second bottom outlet (215). The fifth distillation column (231) is provided with a fifth bottom outlet (232), a fifth top outlet (233) and a fifth side outlet (234). The second storage tank (235) is used to collect and store acetic acid, and the inlet of the second storage tank (235) is connected to the fifth side outlet (234); The third storage tank (236) is used to collect and store the heavy components of the bottom liquid of the fifth distillation column (231), and the inlet of the third storage tank (236) is connected to the outlet (232) of the fifth bottom column.

3. The system according to claim 2, characterized in that, The butenaldehyde recovery device (24) includes: The sixth distillation column (241) is an azeotropic distillation column used to recover butenaldehyde. The inlet of the sixth distillation column (241) is connected to the fifth top outlet (233). The sixth distillation column (241) is provided with a sixth bottom outlet (242) and a sixth top outlet (243). The fourth storage tank (244) is used to collect and store butenaldehyde, and the inlet of the fourth storage tank (244) is connected to the sixth top outlet (243).

4. The system according to claim 3, characterized in that, The acetaldehyde recovery device (25) includes: The seventh distillation column (251) is used to recover acetaldehyde. The inlet of the seventh distillation column (251) is connected to both the oil phase outlet (2208) and the first top outlet (213). The seventh distillation column (251) is provided with a seventh bottom outlet (252), a seventh top outlet (253) and a seventh side outlet (254). The fifth storage tank (255) is used to collect and store acetaldehyde, and the inlet of the fifth storage tank (255) is connected to the seventh top outlet (253); The sixth storage tank (256) is used to collect and store vinyl acetate, and the inlet of the sixth storage tank (256) is connected to the seventh side outlet (254).

5. The system according to claim 4, characterized in that, The methyl acetate recovery device (26) includes: The eighth distillation column (261) is operated intermittently for the recovery of methyl acetate. The inlet of the eighth distillation column (261) is connected to the fourth top outlet (2211). The eighth distillation column (261) is provided with an eighth bottom outlet (262) and an eighth top outlet (263). The eighth bottom outlet (262) is connected to a trench. The seventh storage tank (264) is used to collect and store methyl acetate, and the inlet of the seventh storage tank (264) is connected to the eighth top outlet (263).

6. A method for treating acetic acid-containing fermentation waste liquid, characterized in that, The method is applied to the system according to any one of claims 1-5, and the method includes: The fermentation waste liquid and calcium carbide are fed into the vinyl acetate synthesis device (1) to react and obtain the reaction product; The reaction products are passed into the separation and recovery device (2) for separation and recovery of the reaction products.

7. The method according to claim 6, characterized in that, The separation and recovery reaction products include: The reaction products were initially separated into acetaldehyde and vinyl acetate using a coarse separation device (21); The reaction products are purified and vinyl acetate is recovered using a vinyl acetate refining unit (22); The reaction product is purified and acetic acid is recovered using an acetic acid purification unit (23); The reaction products are separated and the butenaldehyde is recovered by the butenaldehyde recovery device (24); The reaction products are separated and acetaldehyde is recovered by an acetaldehyde recovery device (25); The reaction products are separated and methyl acetate is recovered by a methyl acetate recovery device (26).

8. The method according to claim 7, characterized in that, The main product of the reaction is vinyl acetate, and the byproducts include acetylene, acetaldehyde, methyl acetate, methanol, water, butenal, and acetic acid; the fermentation waste liquid includes waste liquid generated from grain fermentation process and waste liquid generated from industrial tail gas fermentation process; the recovered vinyl acetate purity is 99.60%~99.99%.

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