Production process and device of high-purity propylene acetate taking propylene as raw material

Abstract

The application relates to a propylene acetic ester production process and device with propylene as raw material, which comprises a synthesis system and a refining system, the synthesis system comprises a reaction process, a propylene circulation process, a decarburization process and a denitrogenation process; the refining system comprises a deacetic acid process, a propylene acetic ester refining process, a light component removal process and a dehydration process. The molar fraction of oxygen in the feed is greater than 8%, the conversion rate of acetic acid and propylene is improved, and the propylene acetic ester yield is increased; the propylene circulation process is arranged, the azeotropy of acetic acid and propylene acetic ester is utilized in a gas-liquid separation tower, and multi-stage circulation utilization of materials is realized; according to the boiling points and compositions of various products and azeotropes, a reasonable separation strategy is proposed, a suitable process flow is constructed, and high-purity propylene acetic ester products with a mass fraction of greater than or equal to 99.9% are obtained; heat is coupled between systems, steam generated by heat removal of the oxidation reactor is applied to a rectifying tower reboiler, the steam is then used in multi-stage, and the steam consumption is reduced to 68.51% of the original.

Description

Technical Field

[0001] This invention belongs to the field of chemical reaction and separation, and relates to the production process of propylene acetate, and particularly to a production process and apparatus for high-purity propylene acetate using propylene as raw material. Background Technology

[0002] Propylene acetate, also known as allyl acetate, has the molecular formula C5H8O2. It is an important organic compound whose main downstream products include allyl alcohol, 1,4-butanediol, epichlorohydrin, glycerol, and allyl ethers. It is widely used in the production of pharmaceuticals, agrochemicals, fragrances, surfactants, silicone coupling agents, resin modifiers, and crosslinking agents. 1,4-Butanediol has the molecular formula C4H... 10 O2 is a basic organic and fine chemical raw material, an important raw material for biodegradable plastics and spandex, and a raw material for γ-butyrolactone (GBL), carbon nanotubes (CNT), and N-methylpyrrolidone (NMP) in the lithium battery industry. It can also be used to produce vitamin B6, herbicides, cleaning agents, engineering plastics, insulating materials, pesticides, and crosslinking agents, and is widely used in pharmaceuticals, chemicals, machinery, and textiles. The propylene acetate process for producing 1,4-butanediol has good prospects for widespread application. The direct hydroformylation of propylene acetate avoids the involvement of allyl alcohol and promptly removes water generated during the propylene acetate production process, introducing water only in the final hydrolysis reaction, effectively reducing system energy consumption. However, the direct hydroformylation of propylene acetate requires a purity of ≥99% for the raw material propylene acetate.

[0003] Patent ZL201180044458.1 discloses a method for preparing propylene acetate, which involves using oxygen, acetic acid, and propylene as raw materials. This invention recovers unreacted acetic acid and propylene, as well as acetic acid generated during the hydrolysis of propylene acetate to allyl alcohol, and recycles them as raw materials for propylene acetate preparation. The molar fraction of oxygen in the feed is 6%. However, the process described in this invention does not address the issues of thermal coupling and the accumulation of inert gases nitrogen and carbon dioxide, which are crucial for reducing energy consumption and maintaining process stability. Furthermore, this invention does not purify propylene acetate, resulting in a crude product with a propylene acetate mass fraction of approximately 60-70%. Byproducts generated during the propylene acetate preparation process, such as acrolein, acrylic acid, and allyl acrylate, can lead to catalyst poisoning and deactivation.

[0004] Patent ZL201180011271.1 discloses a method for producing allyl alcohol, which involves reacting propylene, acetic acid, and oxygen to produce propylene acetate. This invention recycles unreacted propylene and acetic acid and incorporates a carbon dioxide removal device to remove carbon dioxide; the preferred molar fraction of oxygen in the feed is 2-6%. However, the described process lacks thermal coupling, removal of inert nitrogen gas, and purification of propylene acetate, resulting in a crude product with approximately 30% propylene acetate by mass. This crude product is then subjected to hydrolysis for the production of allyl alcohol. Byproducts generated during propylene acetate production, such as acrolein, acrylic acid, and allyl acrylate, can lead to catalyst poisoning and deactivation.

[0005] Patent ZL201310435112.5 discloses a method for producing propylene acetate. This method uses propylene, acetic acid, oxygen, and water as raw materials, reacting them with a Pd catalyst in a fixed-bed reactor to generate an effluent containing propylene acetate. The reactor includes at least two annular baffles and at least one inverted conical baffle plate. It offers advantages such as high fluid turbulence, small dead zones, high heat exchange efficiency, high catalyst utilization, and high conversion rate. This overcomes the shortcomings of previous technologies, such as uneven flow of the heat exchange medium between the shell and tube sides of large-diameter tubular fixed-bed reactors, which resulted in low heat exchange efficiency and uneven radial temperature distribution. However, the method described in this invention does not mention the complete propylene acetate production process, including material recycling, removal of inert components, thermal coupling, and purification of propylene acetate.

[0006] In summary, the current production process of propylene acetate mainly has the following problems: The low oxygen concentration in the reaction feedstock, with a molar fraction of only 6%, is unfavorable for the conversion of acetic acid and propylene, further leading to a low yield of propylene acetate. The accumulation of inert gas components, thermal coupling, and multi-stage material recycling were not considered, resulting in high material and energy consumption. The purification and refining of propylene acetate were not taken into account, resulting in a purity of <99%. Byproducts such as acrolein, acrylic acid, and allyl acrylate can poison and deactivate the catalyst, causing the catalyst selectivity to decrease from 91.0% to 82.6% over time. A high-purity propylene acetate production process applicable to the direct hydroformylation of propylene acetate urgently needs to be developed. Summary of the Invention

[0007] The purpose of this invention is to provide a high-purity propylene acetate production process. By setting up a synthesis system and a refining system, a high-purity propylene acetate production process using propylene as raw material is invented. The synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process, and a denitrification process; the refining system includes a deacetic acid removal process, a propylene acetate refining process, a light precipitate removal process, and a dehydration process, yielding a high-purity propylene acetate product with a mass fraction ≥99.9%, which is higher than the typical purity of 99% by mass.

[0008] To achieve the above-mentioned objectives, the technical solution of the present invention is as follows: A process for producing high-purity propylene acetate using propylene as raw material; comprising a synthesis system and a refining system, wherein the synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process and a denitrification process; and the refining system includes a deacetic acid removal process, a propylene acetate refining process, a light precipitate removal process and a dehydration process.

[0009] The process for producing high-purity propylene acetate using propylene as a raw material includes the following steps: (1) The raw materials propylene, acetic acid and oxygen are mixed and fed into the reaction process to carry out acetoxylation reaction to generate propylene acetate; the product obtained from the reaction process is separated by gas and liquid, and the liquid is sent into the purification system. After separation and purification, high-purity propylene acetate product is obtained, and the gas is propylene recycle gas. (2) Part of the propylene recycle gas is sent to the reaction process for recycling, and the other part is sent to the decarbonization process to remove CO2; the gas after CO2 removal is the decarbonized propylene recycle gas, part of which is sent to the reaction process for recycling, and the other part is sent to the denitrification process to remove N2; the gas after N2 removal is the denitrified propylene recycle gas, and all of it is sent to the reaction process for recycling. (3) The liquid material from the reaction process is fed into the deacetic acid removal process. The azeotrope formed by propionaldehyde, acrolein, propyl acetate, and propylene acetate and water is collected from the top of the distillation column in the deacetic acid removal process. The bottom of the distillation column is filled with a heavy component consisting of a small amount of water, acetic acid, allyl acrylate, acrylic acid, and allyl diacetate. The distillation column is side-collected to obtain a liquid material rich in propyl acetate. The gaseous material from the top of the distillation column in the deacetic acid removal process is condensed and sent to the phase separation unit, where it is divided into an aqueous phase and an oil phase. Part of the aqueous phase is refluxed to the deacetic acid removal process, and the other part is sent to the dehydration process. Part of the oil phase is refluxed to the deacetic acid removal process, and the other part is sent to the propylene acetate refining process. (4) In the refining process of propylene acetate, the distillation column for refining crude propylene acetate collects acrolein, propionaldehyde, and the azeotrope formed by propylene acetate and water as light components from the top of the column, and obtains a liquid material from the bottom of the column that is free of water and whose main components are propylene acetate and propyl acetate; the gaseous material from the top of the distillation column is condensed and sent to the phase separation unit, which separates it into an aqueous phase and an oil phase. All of the aqueous phase is sent to the dehydration process; part of the oil phase is refluxed and the other part is sent to the light component removal process; the liquid material from the bottom of the distillation column is sent to the distillation column for refining propylene acetate in the refining process of propylene acetate. (5) High-purity propylene acetate product is obtained from the top of the distillation column for refining propylene acetate, and liquid material with propylene acetate as the main component is obtained from the bottom of the column. It is recycled back to the deacetic acid removal process for further processing. (6) During the removal of light components, propionaldehyde, acrolein and a small amount of propyl acetate are collected from the top of the distillation column during the removal of light components. The bottom of the column contains a liquid material with water, propyl acetate and propylene acetate as the main components, which is recycled back to the propylene acetate refining process. The removal of light components removes propionaldehyde, acrolein and a small amount of propyl acetate, and recovers the remaining propylene acetate. (7) During the dehydration process, the azeotrope formed by water and propylene acetate is taken out as a light component from the top of the distillation column during the dehydration process and recycled back to the propylene acetate refining process for treatment; the bottom of the column obtains a liquid material with water as the main component, which is sent to wastewater treatment; the dehydration process removes water and recovers the remaining propylene acetate.

[0010] The apparatus for producing high-purity propylene acetate using propylene as raw material according to the present invention comprises the following main components: oxidation reactor R1, gas-liquid separation tower C1, water washing tower C2, absorption tower C3, desorption tower C4, circulating gas compressor K1, recovery gas compressor K2, first reaction gas cooler E1, second reaction gas cooler E2, circulating propylene preheater E3, third reaction gas cooler E4, recovery gas cooler E5, absorption tower condenser E6, rich liquid heater E7, desorption tower condenser E8, circulating gas-liquid separator V1, absorption tower gas-liquid separator V2, rich liquid flash evaporator V3, desorption tower gas-liquid separator V4, degassing tank V5, degassing tank gas-liquid separator V6, degassing tank tail gas-liquid separator V7, propylene feed mixer M1, acetic acid feed mixer M2, and oxygen mixer. The system includes: M3 (mixer), M4 (propylene circulating gas mixer), M5 (pressurized circulating gas mixer), M6 (denitrile propylene circulating gas mixer), M7 (lean liquor mixer), M8 (potassium carbonate solution mixer), M9 (degassing tank liquid phase circulating mixer), M10 (degassing tank feed mixer), F1 (first circulating gas splitter), F2 (second circulating gas splitter), and PK1 (membrane separator). The oxygen mixer M3 inlet is connected to the outlet of the circulating propylene preheater E3 and a fresh oxygen pipeline, and its outlet is connected to the inlet of the oxidation reactor R1. The outlet of the oxidation reactor R1 is connected to the inlet of the first reaction gas cooler E1. The outlet of the propylene feed mixer M1 is connected to the inlet of the second reaction gas cooler E2. The inlet of the acetic acid feed mixer M2 is connected to the outlet of the second reaction gas cooler E2. The system connects to the fresh acetic acid pipeline, with its outlet connected to the inlet of the first reaction gas cooler E1; the inlet of the circulating propylene preheater E3 connects to the outlet of the first reaction gas cooler E1; the outlet of the first reaction gas cooler E1 connects to the inlet of the second reaction gas cooler E2; the inlet of the third reaction gas cooler E4 connects to the outlet of the second reaction gas cooler E2, and its outlet connects to the inlet of the gas-liquid separator C1; the top outlet of the gas-liquid separator C1 connects to the inlet of the propylene circulating gas mixer M4, and the bottom outlet connects to the inlet of the degassing tank feed mixer M10; the outlet of the recovered gas cooler E5, the fresh acetic acid pipeline, and the process water pipeline connect to the inlet of the water washing tower C2; the top outlet of the water washing tower C2 connects to the inlet of the absorption tower C3, and the bottom outlet connects to the inlet of the degassing tank. The feed mixer M10 inlet is connected; the potassium carbonate solution mixer M8 outlet is connected to the absorber C3 inlet; the absorber C3 top outlet is connected to the absorber condenser E6 inlet, and the bottom outlet is connected to the rich liquid heater E7 inlet; the rich liquid flash tank V3 top outlet is connected to the degassing tank feed mixer M10 inlet, and the bottom outlet is connected to the desorption tower C4 inlet; the desorption tower C4 top outlet is connected to the desorption tower condenser E8 inlet, and the bottom outlet is connected to the lean liquid mixer M7 inlet; the degassing tank feed mixer M10 outlet and the degassing tank liquid phase circulation mixer M9 outlet are connected to the degassing tank V5 inlet; the degassing tank V5 top outlet is connected to the degassing tank condenser E9 inlet, and the bottom outlet is connected to the propylene acetate refining system.

[0011] The apparatus for producing high-purity propylene acetate using propylene as raw material according to the present invention includes a refining system comprising: a deacetic acid tower C5, a crude propylene acetate tower C6, a refined propylene acetate tower C7, a light propylene oxide removal tower C8, a dehydration tower C9, a deacetic acid tower condenser E11, a deacetic acid tower condensate cooler E12, a crude propylene acetate tower condenser E13, a crude propylene acetate tower condensate cooler E14, a refined propylene acetate tower condenser E15, a refined propylene acetate tower condensate cooler E16, a light propylene oxide removal tower condenser E17, a light propylene oxide removal tower tail gas condenser E18, a light propylene oxide removal tower condensate cooler E19, a deacetic acid tower gas-liquid separator V8, a deacetic acid tower distillate phase separation tank V9, and a crude propylene acetate... The following components are listed: Acrylic ester tower gas-liquid separator V10, crude propylene acetate tower distillate phase separator V11, refined propylene acetate tower gas-liquid separator V12, light propylene acetate removal tower gas-liquid separator V13 and light propylene acetate removal tower tail gas-liquid separator V14, acetic acid removal tower oil phase reflux pump P1, acetic acid removal tower aqueous phase reflux pump P2, crude propylene acetate tower reflux pump P3, refined propylene acetate tower outlet pump P4, light propylene acetate removal tower outlet pump P5, dehydration tower feed pump P6, acetic acid removal tower aqueous phase reflux distributor F3, acetic acid removal tower oil phase reflux distributor F4, crude propylene acetate tower reflux distributor F5, refined propylene acetate tower outlet distributor F6, light propylene acetate removal tower outlet distributor F7, and crude propylene acetate tower overhead gas-phase mixer. M11, M12 (light emission tower), M13 (feed mixer for dehydration tower); the inlet of C5 (acetic acid removal tower) is connected to the propylene acetate synthesis system, the outlet of F3 (aqueous phase reflux distributor for acetic acid removal tower), the outlet of F4 (oil phase reflux distributor for acetic acid removal tower), and the bottom outlet of C7 (refined propylene acetate tower); the top outlet is connected to the inlet of E11 (condenser for acetic acid removal tower); the inlet of C6 (crude propylene acetate tower) is connected to the outlet of F4 (oil phase reflux distributor for acetic acid removal tower), the outlet of F5 (reflux distributor for crude propylene acetate tower), and the bottom outlet of C8 (light emission tower); the top outlet is connected to the inlet of M11 (top gas phase mixer for crude propylene acetate tower), and the bottom outlet is connected to the inlet of C7 (refined propylene acetate tower); refined propylene acetate... The top outlet of the propylene ester tower C7 is connected to the inlet of the condenser E15 of the refined propylene acetate tower; the outlet of the product distributor F6 of the refined propylene acetate tower is connected to the inlet of the refined propylene acetate tower C7 and the propylene acetate product pipeline; the inlet of the light propylene oxide removal tower C8 is connected to the outlet of the reflux distributor F5 of the crude propylene acetate tower, and its top outlet is connected to the inlet of the condenser E17 of the light propylene oxide removal tower; the inlet of the product distributor F7 of the light propylene oxide removal tower is connected to the outlet of the product pump P5 of the light propylene oxide removal tower, and its outlet is connected to the inlet of the light propylene oxide removal tower C8 and the product pipeline; the inlet of the dehydration tower C9 is connected to the outlet of the feed pump P6 of the dehydration tower, its top outlet is connected to the inlet of the gas phase mixer M11 at the top of the crude propylene acetate tower, and its bottom outlet is connected to the wastewater treatment device.

[0012] The operating pressure of gas-liquid separator C1 is 0.85-1.05 MPaA, the operating pressure of water washing tower C2 is 1.05-1.25 MPaA, the operating pressure of absorption tower C3 is 0.90-1.10 MPaA, the operating pressure of desorption tower C4 is 0.04-0.24 MPaA, and the operating pressure of degassing tank V5 is 0.05-0.15 MPaA; the washing acetic acid flow rate of gas-liquid separator C1 is 9500-10500 kg·h. -1 The acetic acid flow rate for washing in water washing tower C2 is 2000-3000 kg·h. -1 The water flow rate is 200-300 kg·h -1 .

[0013] The operating pressure of the acetic acid removal tower C5 is 0.05-0.15 MPaA, the operating pressure of the crude propylene acetate tower C6 is 0.05-0.15 MPaA, the operating pressure of the refined propylene acetate tower C7 is 0.05-0.15 MPaA, the operating pressure of the light propylene acetate removal tower C8 is 0.05-0.15 MPaA, and the operating pressure of the dehydration tower C9 is 0.05-0.15 MPaA.

[0014] The specific explanation is as follows: This invention proposes a process for producing high-purity propylene acetate using propylene as raw material, which includes a synthesis system and a refining system. The synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process, and a denitrification process. The refining system consists of a deacetic acid removal process, a propylene acetate refining process, a light precipitate removal process, and a dehydration process.

[0015] (1) The synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process and a denitrification process; the raw materials propylene, acetic acid and oxygen are mixed and fed into the reaction process to carry out an acetoxylation reaction to produce propylene acetate; the molar fraction of oxygen in the feed is greater than 8%, which improves the conversion rate of acetic acid and propylene, thereby increasing the yield of propylene acetate; the product obtained from the reaction process is separated into gas and liquid, and the liquid is sent to the purification system. After separation and purification, high-purity propylene acetate product is obtained, and the gas is propylene recycling gas; (2) Part of the propylene circulating gas is fed into the reaction process for recycling, and the other part is fed into the decarbonization process to remove CO2; the gas after CO2 removal is the decarbonized propylene circulating gas, part of which is fed into the reaction process for recycling, and the other part is fed into the denitrification process to remove N2; the gas after N2 removal is the denitrified propylene circulating gas, and all of it is fed into the reaction process for recycling; the propylene circulating gas is sent back to the reaction process, realizing multi-stage recycling of materials; the carbon dioxide and nitrogen in the propylene circulating gas are removed to prevent the accumulation of inert gases; By applying the steam generated during the heat transfer process to the steam pipeline network, and then through the multi-stage utilization of low-pressure steam, thermal coupling between systems is achieved, and steam consumption is reduced to 68.51% of the original amount, thereby reducing the material and energy consumption of the system. (3) Based on the boiling point and composition of each product and azeotrope, a reasonable separation strategy was proposed for the refining system. The refining system was specifically divided into the deacetic acid process, the propylene acetate refining process, the light ions removal process and the dehydration process. Furthermore, a suitable process flow was constructed to separate propylene acetate from by-products such as acrolein, acrylic acid and allyl acrylate, thereby avoiding catalyst poisoning and deactivation caused by by-products. Specifically: the liquid phase material from the reaction process is fed into the deacetic acid removal process, where the azeotrope formed by propionaldehyde, acrolein, propyl acetate, and propylene acetate and water is collected from the top of the distillation column in the deacetic acid removal process; the bottom of the distillation column yields a heavy component consisting of a small amount of water, acetic acid, allyl acrylate, acrylic acid, and allyl diacetate; the distillation column is side-collected to obtain a liquid phase material rich in propyl acetate; the gaseous material from the top of the distillation column in the deacetic acid removal process is condensed and sent to the phase separation unit, where it is separated into an aqueous phase and an oil phase. Part of the aqueous phase is refluxed back to the deacetic acid removal process, and the other part is sent to the dehydration process; part of the oil phase is refluxed back to the deacetic acid removal process, and the other part is sent to the propylene acetate refining process; (4) In the refining process of propylene acetate, the distillation column for refining crude propylene acetate collects acrolein, propionaldehyde, and the azeotrope formed by propylene acetate and water as light components from the top of the column, while the bottom of the column yields a liquid material that is free of water and whose main components are propylene acetate and propyl acetate. The gaseous material from the top of the distillation column is condensed and sent to the phase separation unit, where it is separated into an aqueous phase and an oil phase. All of the aqueous phase is sent to the dehydration process, and part of the oil phase is refluxed, while the other part is sent to the light component removal process. The liquid material from the bottom of the distillation column is sent to the distillation column for refining propylene acetate in the refining process of propylene acetate. This process achieves the separation of propylene acetate from acrolein, propionaldehyde, and water, producing refined propylene acetate. (5) High-purity propylene acetate product is obtained from the top of the distillation column for refining propylene acetate, and liquid material with propylene acetate as the main component is obtained from the bottom of the column. This material is recycled back to the deacetic acid removal process for further treatment. This process achieves further separation and purification of propylene acetate to produce high-purity propylene acetate product; (6) During the removal of light components, propionaldehyde, acrolein, and a small amount of propyl acetate are collected from the top of the distillation column. The bottom of the column yields a liquid material mainly composed of water, propyl acetate, and propylene acetate, which is recycled back to the propylene acetate refining process. The removal of light components removes propionaldehyde, acrolein, and a small amount of propyl acetate, and recovers the remaining propylene acetate. (7) During the dehydration process, the azeotrope formed by water and propylene acetate is collected as a light component from the top of the distillation column during the dehydration process and recycled back to the propylene acetate refining process for further treatment; the bottom of the column yields a liquid material with water as the main component, which is sent to wastewater treatment. The dehydration process removes water and recovers the remaining propylene acetate.

[0016] In the above technical solution, the synthesis system mainly includes an oxidation reactor R1, a gas-liquid separation tower C1, a water washing tower C2, an absorption tower C3, a desorption tower C4, a circulating gas compressor K1, a recovery gas compressor K2, a first reaction gas cooler E1, a second reaction gas cooler E2, a circulating propylene preheater E3, a third reaction gas cooler E4, a recovery gas cooler E5, an absorption tower condenser E6, a rich liquid heater E7, a desorption tower condenser E8, a circulating gas-liquid separator V1, an absorption tower gas-liquid separator V2, a rich liquid flash evaporator V3, a desorption tower gas-liquid separator V4, a degassing tank V5, a degassing tank gas-liquid separator V6, and a degassing tank. The system comprises the following components: tail gas-liquid separator V7, propylene feed mixer M1, acetic acid feed mixer M2, oxygen mixer M3, propylene circulating gas mixer M4, pressurized circulating gas mixer M5, denitrified propylene circulating gas mixer M6, lean liquor mixer M7, potassium carbonate solution mixer M8, degassing tank liquid phase circulating mixer M9, degassing tank feed mixer M10, first circulating gas splitter F1, second circulating gas splitter F2, and membrane separator PK1. The connections between the equipment in the synthesis system are as follows: the inlet of oxygen mixer M3 is connected to the outlet of circulating propylene preheater E3 and the fresh oxygen pipeline, and the outlet is connected to the inlet of oxidation reactor R1. The outlet of oxidation reactor R1 is connected to the inlet of the first reaction gas cooler E1. The outlet of propylene feed mixer M1 is connected to the inlet of the second reaction gas cooler E2. The inlet of acetic acid feed mixer M2 is connected to the outlet of the second reaction gas cooler E2 and the fresh acetic acid pipeline, and the outlet is connected to the inlet of the first reaction gas cooler E1. The inlet of the circulating propylene preheater E3 is connected to the outlet of the first reactant gas cooler E1. The outlet of the first reactant gas cooler E1 is connected to the inlet of the second reactant gas cooler E2. The inlet of the third reactant gas cooler E4 is connected to the outlet of the second reactant gas cooler E2, and its outlet is connected to the inlet of the gas-liquid separator C1. The top outlet of the gas-liquid separator C1 is connected to the inlet of the propylene circulating gas mixer M4, and its bottom outlet is connected to the inlet of the degassing tank feed mixer M10. The outlet of the recovered gas cooler E5, the fresh acetic acid pipeline, and the process water pipeline are connected to the inlet of the water scrubbing tower C2. The top outlet of the water scrubbing tower C2 is connected to the inlet of the absorption tower C3, and its bottom outlet is connected to the inlet of the degassing tank feed mixer M10. The outlet of the potassium carbonate solution mixer M8 is connected to the inlet of the absorption tower C3. The top outlet of the absorption tower C3 is connected to the inlet of the absorption tower condenser E6, and its bottom outlet is connected to the inlet of the rich liquid heater E7. The top outlet of the rich liquid flash evaporator V3 is connected to the inlet of the degassing tank feed mixer M10, and the bottom outlet is connected to the inlet of the desorption tower C4. The top outlet of the desorption tower C4 is connected to the inlet of the desorption tower condenser E8, and the bottom outlet is connected to the inlet of the lean liquid mixer M7. The outlet of the degassing tank feed mixer M10 and the outlet of the degassing tank liquid phase circulation mixer M9 are connected to the inlet of the degassing tank V5. The top outlet of the degassing tank V5 is connected to the inlet of the degassing tank condenser E9, and the bottom outlet is connected to the propylene acetate refining system.

[0017] In the above technical solution, during the reaction process, fresh propylene FD1 is mixed with circulating gas from the circulating gas compressor K1; the mixed gas passes through the second reaction gas cooler E2 and exchanges heat with the reaction gas from the first reaction gas cooler E1; then it is mixed with fresh acetic acid FD2; the mixture of acetic acid and propylene passes through the first reaction gas cooler E1 and exchanges heat with the reaction gas from the oxidation reactor R1, then is heated by the circulating propylene preheater E3, and then mixed with fresh oxygen FD3 by the oxygen mixer M3 to obtain a mixed gaseous material of propylene, acetic acid and oxygen, which is sent to the oxidation reactor R1 for acetylation. Acetyl acetate is produced by the acetylation reaction. The reaction gas obtained from the outlet of the oxidation reactor R1 is cooled by the first reaction gas cooler E1, the second reaction gas cooler E2, and the third reaction gas cooler E4 before being sent to the gas-liquid separation tower C1. The oxidation reactor R1 is a heat-transfer fixed-bed reactor. The reactor tube side is filled with Pd-based catalyst with active components distributed in an eggshell pattern and undergoes an acetylation reaction. The reactor shell side uses pressurized water circulation to remove the heat of reaction in a timely manner. The reactor inlet material contains carbon dioxide and nitrogen, with a carbon dioxide concentration of 20-28 mol% and a nitrogen concentration of 2-8 mol%.

[0018] The above technical solution incorporates a propylene recycling process, enabling multi-stage material recycling. During the propylene recycling process, the reactor outlet stream is cooled by the first reaction gas cooler E1, the second reaction gas cooler E2, and the third reaction gas cooler E4 before being fed into the bottom of the gas-liquid separator C1. The top stream of the gas-liquid separator C1, being propylene recycling gas, is sent to the recycling gas-liquid separator V1, while the bottom stream is sent to the degassing tank V5. The degassing tank V5 receives the liquid phase material from the recycling gas-liquid separator V1, the bottom liquid from the gas-liquid separator C1, the bottom liquid from the water washing tower C2, and the gas phase material from the rich liquid flash evaporator V3. Through reduced pressure flash evaporation, the propylene, oxygen, and carbon dioxide gases in the mixture are separated from the top... The liquid phase material, mainly composed of propylene acetate, acetic acid, and water, is collected from the bottom and sent to the propylene acetate refining system to obtain high-purity propylene acetate product. The gaseous material from the top of the degassing tank V5 is condensed by the degassing tank condenser E9 and then enters the degassing tank gas-liquid separator V6. The gaseous material in the degassing tank gas-liquid separator V6 is cooled by the degassing tank tail gas condenser E10 and then sent to the degassing tank tail gas-liquid separator V7. The gaseous stream in V7 is sent to the subsequent water washing tower C2, and the liquid phase material is mixed with the liquid phase material in V6 and then recycled back to the degassing tank V5.

[0019] The above technical solution includes a decarbonization process to remove carbon dioxide from the propylene circulating gas and prevent the accumulation of inert gases. During the decarbonization process, the middle section of the water washing tower C2 uses fresh acetic acid FD5 for washing to remove propylene acetate from the recovered gas; the top of the water washing tower C2 uses water FD6 for washing to remove the recovered gas and the acetic acid introduced by the fresh acetic acid FD5; the gaseous material from the circulating gas-liquid separator V1 is pressurized by the circulating gas compressor K1, and a portion of the circulating gas is sent to the decarbonization process; the gaseous material from the degassing tank V5 is the recovered gas, which is pressurized by the recovered gas compressor K2, mixed with the circulating gas, and then sent to the decarbonization process. Water washing tower C2 recovers propylene acetate and acetic acid, and the recovered gas from the top of water washing tower C2 is sent to absorber C3. The main components of the bottom stream of water washing tower C2 are acetic acid and propylene acetate, which are sent to degassing tank V5. Carbon dioxide is removed using the hot potassium carbonate method. The material from the top of water washing tower C2 enters absorber C3 from the bottom, where it comes into full countercurrent contact with the potassium carbonate solution flowing down from top to bottom. The material from the top of absorber C3 is condensed in absorber condenser E6 and then enters the absorber for gas-liquid separation. The gaseous material obtained at the top of tank V2 is partially mixed with the propylene circulating gas from the top of gas-liquid separator C1 as decarbonized propylene circulating gas, and then sent to circulating gas-liquid separator V1 to achieve the recycling of propylene and oxygen. The bottom liquid of absorber C3 is a rich liquid after carbon dioxide absorption. After depressurization, it is heated by rich liquid heater E7 and sent to rich liquid flash tank V3 to remove most of the propylene dissolved in the rich liquid, and then sent to degasser V5. The liquid phase material in rich liquid flash tank V3 is sent to the top of desorption tower C4 for carbon dioxide desorption. The material at the top of desorption tower C4 is condensed by desorption tower condenser E8 and then sent to desorption tower gas-liquid separator V4 to obtain gas with carbon dioxide as the main component. This gas is discharged from the system to avoid carbon dioxide accumulation. The liquid phase material in desorption tower gas-liquid separator V4 is mixed with the lean liquid at the bottom of desorption tower C4 and the liquid phase material in absorber gas-liquid separator V4, and then mixed with additional potassium carbonate solution to obtain lean liquid, which is recycled back to the top of absorber C3.

[0020] The above technical solution includes a denitrification process to remove nitrogen from the propylene circulating gas and prevent the accumulation of inert gases. During the denitrification process, a portion of the gaseous material from the gas-liquid separator V2 in the absorber is sent to the membrane separator PK1 to remove nitrogen, thus solving the problem of nitrogen accumulation during propylene acetate production. The material with nitrogen as the main component is treated as tail gas and then discharged. The material with propylene as the main component is used as the denitrified propylene circulating gas, which is mixed with the gas stream from the degassing tank tail gas-liquid separator V7, and then pressurized by the recovery gas compressor K2 before being recycled to the decarbonization process.

[0021] In the above technical solution, a refining system is set up based on the boiling points and compositions of each product and azeotrope, and a reasonable separation strategy is proposed. The refining system mainly includes: acetic acid removal tower C5, crude propylene acetate tower C6, refined propylene acetate tower C7, light ester removal tower C8, dehydration tower C9, acetic acid removal tower condenser E11, acetic acid removal tower condensate cooler E12, crude propylene acetate tower condenser E13, crude propylene acetate tower condensate cooler E14, refined propylene acetate tower condenser E15, refined propylene acetate tower condensate cooler E16, light ester removal tower condenser E17, light ester removal tower tail gas condenser E18, light ester removal tower condensate cooler E19, and acetic acid removal tower... V8, V9, V10, V11, V12, V13, V14, V14, V15, P16, P17, P18, P19, P20, P30, P30, P40, P50, P50, P60, P60, P70, P80, P90, P10, P11, P20, P30, P30, P40, P50, P50, P60, P60, P70, P80, P90, P10, P11, P20, P30, P30, P40, P50, P50, P60, P60, P70, P80, P90, P10, P11, P12, P20, P30, P30, P40, P50, P50, P60, P60, P70, P10, P11, P12, P13, P140, P150, P160, P170, P180, P180, P19 ... The system comprises the following components: aqueous phase reflux distributor F3, oil phase reflux distributor F4, crude propylene acetate tower reflux distributor F5, refined propylene acetate tower outlet distributor F6, light ester removal tower outlet distributor F7, crude propylene acetate tower overhead gas phase mixer M11, light ester removal tower outlet mixer M12, and dehydration tower feed mixer M13. The refining system consists of an acetic acid removal process, a propylene acetate refining process, a light ester removal process, and a dehydration process. The acetic acid removal process mainly includes the acetic acid removal tower and its auxiliary equipment, and the propylene acetate... The refining process mainly includes a crude propylene acetate tower and a refined propylene acetate tower and their auxiliary equipment. The light-weight component removal process mainly includes a light-weight component removal tower and its auxiliary equipment. The dehydration process mainly includes a dehydration tower and its auxiliary equipment. The connections between the equipment in the refining system are as follows: the inlet of the deacetic acid tower C5 is connected to the propylene acetate synthesis system, the outlet of the aqueous phase reflux distributor F3 of the deacetic acid tower, the outlet of the oil phase reflux distributor F4 of the deacetic acid tower, and the bottom outlet of the refined propylene acetate tower C7. The top outlet of the deacetic acid tower is connected to the inlet of the condenser E11 of the deacetic acid tower. The inlet of the crude propylene acetate tower C6 is connected to the outlet of the oil phase reflux distributor F4 of the deacetic acid tower, the outlet of the reflux distributor F5 of the crude propylene acetate tower, and the bottom outlet of the light-weight component removal tower C8. The top outlet of the crude propylene acetate tower is connected to the inlet of the gas phase mixer M11 at the top of the crude propylene acetate tower. The bottom outlet of the crude propylene acetate tower C7 is connected to the inlet of the condenser E15 of the refined propylene acetate tower. The outlet of the refined propylene acetate tower's outlet distributor F6 is connected to the inlet of the refined propylene acetate tower C7 and the propylene acetate outlet pipeline. The inlet of the light propylene acetate removal tower C8 is connected to the outlet of the crude propylene acetate tower's reflux distributor F5, and the tower's top outlet is connected to the inlet of the light propylene acetate removal tower condenser E17. The inlet of the light propylene acetate removal tower's outlet distributor F7 is connected to the outlet of the light propylene acetate removal tower's outlet pump P5, and the outlet is connected to the inlet of the light propylene acetate removal tower C8 and the outlet pipeline.The inlet of the dehydration tower C9 is connected to the outlet of the dehydration tower feed pump P6, the top outlet of the tower is connected to the inlet of the gas phase mixer M11 at the top of the crude propylene acetate tower, and the bottom outlet of the tower is connected to the wastewater treatment device.

[0022] In the above technical solution, during the acetic acid removal process, the liquid phase material from the bottom of the degassing tank V5 and the liquid phase material from the bottom of the refined propylene acetate tower C7 are fed into the acetic acid removal tower C5 together; the gas phase material at the top of the tower is a light component composed of propionaldehyde, acrolein, propylene acetate and water azeotrope, and propyl acetate and water azeotrope. After being condensed by the acetic acid removal tower condenser E11, it enters the acetic acid removal tower gas-liquid separator V8; the liquid phase material in the acetic acid removal tower gas-liquid separator V8 is cooled by the acetic acid removal tower condensate cooler E12 and then sent to the acetic acid removal tower distillation phase separation tank V9 for phase separation. Part of the aqueous phase material is returned to the acetic acid removal tower C5, and the other part is sent to the dehydration tower C9; part of the oil phase material is returned to the acetic acid removal tower C5, and the other part is sent to the crude propylene acetate tower C6.

[0023] In the above technical solution, during the refining process of propylene acetate, the liquid phase material from the top oil phase of the deacetic acid removal tower C5 and the liquid phase material from the bottom of the light phase removal tower C8 are fed together into the crude propylene acetate tower C6. The gaseous material at the top of the tower is a light component composed of azeotropes of propionaldehyde and water, acrolein and water, propylene acetate and water, and propylene acetate and water. After mixing with the gaseous material from the top of the dehydration tower C9, it is sent to the crude propylene acetate tower condenser E13 for condensation, and then enters the crude propylene acetate tower gas-liquid separator V10. The liquid phase material in the crude propylene acetate tower gas-liquid separator V10 is cooled by the crude propylene acetate tower condensate cooler E14 and then sent to the crude propylene acetate tower distillation phase separation tank V11 for phase separation. The aqueous phase material is mixed with the aqueous phase product from the top of the deacetic acid removal tower C5 and then sent to the dehydration tower C9 for processing. Part of the oil phase material is recycled back to the crude propylene acetate tower. The remaining portion is sent to the esterification tower C6, and another portion is sent to the light component removal tower C8. The heavy component, composed of propylene acetate and propyl acetate, obtained from the bottom of the crude propylene acetate tower C6 after the removal of propionaldehyde, acrolein, and water, is sent to the refined propylene acetate tower C7 for further processing. The liquid phase from the bottom of the crude propylene acetate tower C6 is sent to the refined propylene acetate tower C7. The gaseous material at the top of the tower is high-purity propylene acetate product, which is cooled by the condenser E15 of the refined propylene acetate tower before entering the gas-liquid separator V12. The liquid phase in the gas-liquid separator V12 is cooled by the condensate cooler E16 of the refined propylene acetate tower, and part of it is refluxed to the top of the refined propylene acetate tower C7, while the rest is collected to obtain high-purity propylene acetate product with a mass fraction ≥99.9%. The heavy component, mainly composed of propylene acetate and propyl acetate, obtained from the bottom of the tower is sent to the deacetic acid removal tower C5 along with the feed from C5 for recycling.

[0024] In the above technical solution, during the removal of light esters, the oil phase product from the top of the crude propylene acetate tower C6 is sent to the light ester removal tower C8; the gaseous product at the top of the tower is enriched with propionaldehyde and acrolein, and after being cooled by the light ester removal tower condenser E17, it enters the light ester removal tower gas-liquid separator V13; the gaseous product in the light ester removal tower gas-liquid separator V13 is cooled by the light ester removal tower tail gas condenser E18, and then enters the light ester removal tower tail gas-liquid separator V14, where the gaseous product is sent to the tail gas treatment. The liquid phase material is refluxed and collected as condensate; the liquid phase material in the gas-liquid separator V13 of the light-light removal tower is cooled by the condensate cooler E19 of the light-light removal tower, and then mixed with the liquid phase material in the tail gas-liquid separator V14 of the light-light removal tower. Part of the mixture is refluxed to the top of the light-light removal tower C8, and the other part is collected; the bottom of the light-light removal tower C8 receives a heavy component composed of water, propylene acetate and propyl acetate, which has been depropanol and acrolein removed, and is sent to the crude propylene acetate tower C6 for recycling.

[0025] In the above technical solution, during the dehydration process, the aqueous phase material from the top of the deacetic acid tower C5 and the aqueous phase material from the top of the crude propylene acetate tower C6 are mixed and then sent to the top of the dehydration tower C9; the gaseous material at the top of the tower is an azeotrope of water and propylene acetate and an azeotrope of water and propyl acetate, which is mixed with the material from the top of the crude propylene acetate tower C6 and then sent to the condenser E13 of the crude propylene acetate tower; the liquid phase material with water as the main component obtained from the bottom of the dehydration tower C9 is sent to the wastewater treatment plant.

[0026] In the above technical solution, the steam generated by the heat transfer of the oxidation reactor is applied to the reboilers of desorption tower C4, deacetic acid tower C5, crude propylene acetate tower C6, and refined propylene acetate tower C7; then, through multi-stage utilization of low-pressure steam, the steam condensate obtained from the reboilers of desorption tower C4, deacetic acid tower C5, crude propylene acetate tower C6, and refined propylene acetate tower C7 is flash-evaporated, and the resulting low-pressure steam is further applied to the reboilers of light oil removal tower C8 and dehydration tower C9.

[0027] The advantages and beneficial effects of this invention are as follows: (1) The present invention relates to a process for producing high-purity propylene acetate from propylene feedstock. Its advantages are that the molar fraction of oxygen in the feedstock is greater than 8%, which improves the conversion rate of acetic acid and propylene, thereby increasing the yield of propylene acetate and reducing material and energy consumption; carbon dioxide and nitrogen are used as stabilizers to dilute propylene, narrowing the explosion limit and ensuring the continuous and safe operation of the reaction process. (2) The present invention relates to a process for producing high-purity propylene acetate using propylene as raw material. Its advantage is that a propylene recycling process is set up. In the gas-liquid separation tower, the azeotropic reaction of acetic acid and propylene acetate is used to completely separate propylene acetate from gases such as propylene and oxygen. The gas is returned to the reaction process as propylene recycling gas, realizing multi-stage recycling of materials. (3) The present invention relates to a process for producing high-purity propylene acetate from propylene raw material, which has the advantage of setting up a decarbonization process and a denitrification process to remove carbon dioxide and nitrogen from the propylene circulating gas and prevent the accumulation of inert gases. (4) The present invention relates to a process for producing high-purity propylene acetate from propylene raw material. Its advantage is that, based on the boiling point and composition of each product and azeotrope, a reasonable separation strategy is proposed, a suitable process flow is constructed, and a high-purity propylene acetate product with a mass fraction ≥99.9% is obtained. (5) The present invention relates to a process for producing high-purity propylene acetate from propylene feedstock. Its advantage is that it achieves inter-system thermal coupling, applies the steam generated by the heat transfer of the oxidation reactor to the reboiler of the distillation column, and reduces the steam consumption to 68.51% of the original through multi-stage utilization of low-pressure steam. Attached Figure Description

[0028] Figure 1 A simplified flow chart of the synthesis system for producing high-purity propylene acetate from propylene raw material according to the present invention.

[0029] Figure 2 : A schematic diagram of the synthesis system of the high-purity propylene acetate production apparatus using propylene as raw material according to the present invention.

[0030] Figure 3 A simplified flow chart of the refining system for producing high-purity propylene acetate from propylene raw materials according to the present invention.

[0031] Figure 4 : Schematic diagram of the refining system of the high-purity propylene acetate production apparatus using propylene as raw material according to the present invention.

[0032] The components include: oxidation reactor R1, gas-liquid separation tower C1, water washing tower C2, absorption tower C3, desorption tower C4, circulating gas compressor K1, recovery gas compressor K2, first reactant gas cooler E1, second reactant gas cooler E2, circulating propylene preheater E3, third reactant gas cooler E4, recovery gas cooler E5, absorption tower condenser E6, rich liquid heater E7, desorption tower condenser E8, circulating gas-liquid separator V1, absorption tower gas-liquid separator V2, rich liquid flash evaporator V3, desorption tower gas-liquid separator V4, degassing tank V5, and degassing tank gas-liquid separator V6. Tail gas gas-liquid separator V7, propylene feed mixer M1, acetic acid feed mixer M2, oxygen mixer M3, propylene circulating gas mixer M4, pressurized circulating gas mixer M5, denitrified propylene circulating gas mixer M6, lean liquor mixer M7, potassium carbonate solution mixer M8, degassing tank liquid phase circulating mixer M9, degassing tank feed mixer M10, first circulating gas splitter F1, second circulating gas splitter F2, membrane separation unit PK1, acetic acid removal tower C5, crude propylene acetate tower C6, refined propylene acetate tower C7, light ester removal tower C8, dehydration tower C9, acetic acid removal tower condenser E1 1. Acetic acid removal tower condensate cooler E12, crude propylene acetate tower condensate cooler E13, crude propylene acetate tower condensate cooler E14, refined propylene acetate tower condensate cooler, refined propylene acetate tower condensate cooler E16, light propylene acetate removal tower condenser E17, light propylene acetate removal tower tail gas cooler E18, light propylene acetate removal tower condensate cooler E19, acetic acid removal tower gas-liquid separator V8, acetic acid removal tower distillate phase separation tank V9, crude propylene acetate tower gas-liquid separator V10, crude propylene acetate tower distillate phase separation tank V11, refined propylene acetate tower gas-liquid separator V12, light propylene acetate removal tower gas-liquid separator V13, and light propylene acetate removal tower tail gas... The names and numbers of the following components are shown in the figure: liquid separator V14, oil phase reflux pump P1 for the acetic acid removal tower, aqueous phase reflux pump P2 for the acetic acid removal tower, reflux pump P3 for the crude propylene acetate tower, outlet pump P4 for the refined propylene acetate tower, outlet pump P5 for the light propylene acetate removal tower, feed pump P6 for the dehydration tower, aqueous phase reflux distributor F3 for the acetic acid removal tower, oil phase reflux distributor F4 for the acetic acid removal tower, reflux distributor F5 for the crude propylene acetate tower, outlet distributor F6 for the refined propylene acetate tower, outlet distributor F7 for the light propylene acetate removal tower, gas phase mixer M11 at the top of the crude propylene acetate tower, outlet mixer M12 for the light propylene acetate removal tower, and feed mixer M13 for the dehydration tower. Detailed Implementation

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be construed as limiting the scope of protection of the present invention.

[0034] This invention provides a process for producing high-purity propylene acetate from propylene feedstock, comprising a synthesis system and a refining system. The synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process, and a denitrification process. The refining system consists of an acetic acid removal process, a propylene acetate refining process, a light precipitate removal process, and a dehydration process. The technical solutions include the following: (1) The synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process and a denitrification process; the raw materials propylene, acetic acid and oxygen are mixed and fed into the reaction process to carry out an acetoxylation reaction to produce propylene acetate; the molar fraction of oxygen in the feed is greater than 8%, which improves the conversion rate of acetic acid and propylene, and thus increases the yield of propylene acetate; the product obtained from the reaction process is separated into gas and liquid, and the liquid is sent to the purification system, and after separation and purification, high-purity propylene acetate product is obtained, and the gas is propylene recycling gas; (2) Part of the propylene circulating gas is sent to the reaction process for recycling, and the other part is sent to the decarbonization process to remove CO2; the gas after CO2 removal is the decarbonized propylene circulating gas, part of which is sent to the reaction process for recycling, and the other part is sent to the denitrification process to remove N2; the gas after N2 removal is the denitrified propylene circulating gas, and all of it is sent to the reaction process for recycling; the propylene circulating gas is sent back to the reaction process, realizing multi-stage recycling of materials; the carbon dioxide and nitrogen in the propylene circulating gas are removed to prevent the accumulation of volatile gases; By applying the steam generated during the heat transfer process to the steam pipeline network, and then through the multi-stage utilization of low-pressure steam, thermal coupling between systems is achieved, and steam consumption is reduced to 68.51% of the original amount, thereby reducing the material and energy consumption of the system. (3) Based on the boiling point and composition of each product and azeotrope, a reasonable separation strategy was proposed for the refining system. The refining system was specifically divided into the deacetic acid process, the propylene acetate refining process, the light ions removal process and the dehydration process. Furthermore, a suitable process flow was constructed to separate propylene acetate from by-products such as acrolein, acrylic acid and allyl acrylate, thereby avoiding catalyst poisoning and deactivation caused by by-products. Specifically: the liquid phase material from the reaction process is fed into the acetic acid removal process, where the azeotrope formed by propionaldehyde, acrolein, propyl acetate, and propylene acetate and water is collected from the top of the acetic acid removal tower; the bottom of the acetic acid removal tower yields a heavy component consisting of a small amount of water, acetic acid, allyl acrylate, acrylic acid, and allyl diacetate; the acetic acid removal tower side-collects a liquid phase material rich in propyl acetate; the gaseous material from the top of the acetic acid removal tower is condensed and sent to a phase separator, where it is separated into an aqueous phase and an oil phase. Part of the aqueous phase is refluxed back into the acetic acid removal tower, and the other part is sent to the dehydration process; part of the oil phase is refluxed back into the acetic acid removal tower, and the other part is sent to the propylene acetate refining process; (4) In the refining process of propylene acetate, the crude propylene acetate tower collects acrolein, propionaldehyde, and the azeotrope formed by propylene acetate and water as light components from the top of the tower, and obtains a liquid material from the bottom of the tower that is free of water and whose main components are propylene acetate and propyl acetate; the gaseous material from the top of the crude propylene acetate tower is condensed and sent to the phase separator, where it is separated into an aqueous phase and an oil phase. All of the aqueous phase is sent to the dehydration process; part of the oil phase is refluxed, and the other part is sent to the light component removal process; the liquid material from the bottom of the crude propylene acetate tower is sent to the refined propylene acetate tower in the refining process of propylene acetate. This process achieves the separation of propylene acetate from acrolein, propionaldehyde, and water, producing refined propylene acetate; (5) High-purity propylene acetate product is obtained from the top of the propylene acetate tower, and liquid material with propylene acetate as the main component is obtained from the bottom of the tower, which is recycled back to the deacetic acid tower for further treatment. This process achieves further separation and purification of propylene acetate to produce high-purity propylene acetate product; (6) During the removal of light components, propionaldehyde, acrolein, and a small amount of propyl acetate are collected from the top of the removal tower. The bottom of the tower yields a liquid material mainly composed of water, propyl acetate, and propylene acetate, which is recycled back to the propylene acetate refining process. The removal of light components removes propionaldehyde, acrolein, and a small amount of propyl acetate, and recovers the remaining propylene acetate. (7) In the dehydration process, the azeotrope formed by water and propylene acetate is collected as a light component from the top of the dehydration tower and recycled back to the propylene acetate refining process; the bottom of the tower yields a liquid material with water as the main component, which is sent to wastewater treatment. The dehydration process removes water and recovers the remaining propylene acetate.

[0035] In this specific embodiment, the synthesis system mainly includes an oxidation reactor R1, a gas-liquid separation tower C1, a water washing tower C2, an absorption tower C3, a desorption tower C4, a circulating gas compressor K1, a recovery gas compressor K2, a first reaction gas cooler E1, a second reaction gas cooler E2, a circulating propylene preheater E3, a third reaction gas cooler E4, a recovery gas cooler E5, an absorption tower condenser E6, a rich liquid heater E7, a desorption tower condenser E8, a circulating gas-liquid separator V1, an absorption tower gas-liquid separator V2, a rich liquid flash evaporator V3, a desorption tower gas-liquid separator V4, a degassing tank V5, and a degassing tank gas-liquid separator V6. The system comprises the following components: degassing tank tail gas-liquid separator V7, propylene feed mixer M1, acetic acid feed mixer M2, oxygen mixer M3, propylene circulating gas mixer M4, pressurized circulating gas mixer M5, denitrified propylene circulating gas mixer M6, lean liquor mixer M7, potassium carbonate solution mixer M8, degassing tank liquid phase circulating mixer M9, degassing tank feed mixer M10, first circulating gas splitter F1, second circulating gas splitter F2, and membrane separator PK1. The connections between the equipment in the synthesis system are as follows: the inlet of oxygen mixer M3 is connected to the outlet of circulating propylene preheater E3 and the fresh oxygen pipeline, and the outlet is connected to the inlet of oxidation reactor R1. The outlet of oxidation reactor R1 is connected to the inlet of the first reaction gas cooler E1. The outlet of propylene feed mixer M1 is connected to the inlet of the second reaction gas cooler E2. The inlet of acetic acid feed mixer M2 is connected to the outlet of the second reaction gas cooler E2 and the fresh acetic acid pipeline, and the outlet is connected to the inlet of the first reaction gas cooler E1. The inlet of the circulating propylene preheater E3 is connected to the outlet of the first reactant gas cooler E1. The outlet of the first reactant gas cooler E1 is connected to the inlet of the second reactant gas cooler E2. The inlet of the third reactant gas cooler E4 is connected to the outlet of the second reactant gas cooler E2, and its outlet is connected to the inlet of the gas-liquid separator C1. The top outlet of the gas-liquid separator C1 is connected to the inlet of the propylene circulating gas mixer M4, and its bottom outlet is connected to the inlet of the degassing tank feed mixer M10. The outlet of the recovered gas cooler E5, the fresh acetic acid pipeline, and the process water pipeline are connected to the inlet of the water scrubbing tower C2. The top outlet of the water scrubbing tower C2 is connected to the inlet of the absorption tower C3, and its bottom outlet is connected to the inlet of the degassing tank feed mixer M10. The outlet of the potassium carbonate solution mixer M8 is connected to the inlet of the absorption tower C3. The top outlet of the absorption tower C3 is connected to the inlet of the absorption tower condenser E6, and its bottom outlet is connected to the inlet of the rich liquid heater E7. The top outlet of the rich liquid flash evaporator V3 is connected to the inlet of the degassing tank feed mixer M10, and the bottom outlet is connected to the inlet of the desorption tower C4. The top outlet of the desorption tower C4 is connected to the inlet of the desorption tower condenser E8, and the bottom outlet is connected to the inlet of the lean liquid mixer M7. The outlet of the degassing tank feed mixer M10 and the outlet of the degassing tank liquid phase circulation mixer M9 are connected to the inlet of the degassing tank V5. The top outlet of the degassing tank V5 is connected to the inlet of the degassing tank condenser E9, and the bottom outlet is connected to the propylene acetate refining system.

[0036] In this specific embodiment, during the reaction process, fresh propylene FD1 is mixed with circulating gas from the circulating gas compressor K1; the mixed gas passes through the second reaction gas cooler E2, where it exchanges heat with the reaction gas from the first reaction gas cooler E1; then it is mixed with fresh acetic acid FD2; the mixture of acetic acid and propylene passes through the first reaction gas cooler E1, where it exchanges heat with the reaction gas from the oxidation reactor R1, then is heated by the circulating propylene preheater E3, and then mixed with fresh oxygen FD3 by the oxygen mixer M3 to obtain a mixed gaseous material of propylene, acetic acid, and oxygen, which is then fed into the oxidation reactor R1 for further processing. The acetoxylation reaction produces propylene acetate. The reaction gas obtained from the outlet of the oxidation reactor R1 is cooled by the first reaction gas cooler E1, the second reaction gas cooler E2, and the third reaction gas cooler E4 before being sent to the gas-liquid separation tower C1. The oxidation reactor R1 is a heat-transfer fixed-bed reactor. The reactor tube side is filled with Pd-based catalyst with active components distributed in an eggshell pattern and undergoes the acetoxylation reaction. The reactor shell side uses pressurized water circulation to remove the heat of reaction in a timely manner. The reactor inlet material contains carbon dioxide and nitrogen, with a carbon dioxide concentration of 20-28 mol% and a nitrogen concentration of 2-8 mol%.

[0037] In this specific embodiment, a propylene recycling process is incorporated to achieve multi-stage material recycling. During the propylene recycling process, the reactor outlet stream is cooled by the first reaction gas cooler E1, the second reaction gas cooler E2, and the third reaction gas cooler E4 before being fed into the bottom of the gas-liquid separator C1. The top stream of the gas-liquid separator C1, being propylene recycling gas, is sent to the recycling gas-liquid separator V1, while the bottom stream is sent to the degassing tank V5. The degassing tank V5 receives the liquid phase material from the recycling gas-liquid separator V1, the bottom liquid from the gas-liquid separator C1, the bottom liquid from the water washing tower C2, and the gas phase material from the rich liquid flash evaporator V3. Through reduced pressure flash evaporation, the propylene, oxygen, and carbon dioxide gases in the mixture are separated from the top... The liquid phase material, mainly composed of propylene acetate, acetic acid, and water, is collected from the bottom and sent to the propylene acetate refining system to obtain high-purity propylene acetate product. The gaseous material from the top of the degassing tank V5 is condensed by the degassing tank condenser E9 and then enters the degassing tank gas-liquid separator V6. The gaseous material in the degassing tank gas-liquid separator V6 is cooled by the degassing tank tail gas condenser E10 and then sent to the degassing tank tail gas-liquid separator V7. The gaseous stream in V7 is sent to the subsequent water washing tower C2, and the liquid phase material is mixed with the liquid phase material in V6 and then recycled back to the degassing tank V5.

[0038] In this specific embodiment, a decarbonization process is incorporated to remove carbon dioxide from the propylene circulating gas and prevent the accumulation of inert gases. During the decarbonization process, the middle section of the water washing tower C2 is washed with fresh acetic acid FD5 to remove propylene acetate from the recovered gas; the top of the water washing tower C2 is washed with water FD6 to remove the recovered gas and the acetic acid introduced by the fresh acetic acid FD5; the gaseous material from the circulating gas-liquid separator V1 is pressurized by the circulating gas compressor K1, and a portion of the circulating gas is sent to the decarbonization process; the gaseous material from the degassing tank V5 is the recovered gas, which is pressurized by the recovered gas compressor K2, mixed with the circulating gas, and then sent to the decarbonization process. Water washing tower C2 recovers propylene acetate and acetic acid, and the recovered gas from the top of water washing tower C2 is sent to absorber C3. The main components of the bottom stream of water washing tower C2 are acetic acid and propylene acetate, which are sent to degassing tank V5. Carbon dioxide is removed using the hot potassium carbonate method. The material from the top of water washing tower C2 enters absorber C3 from the bottom, where it comes into full countercurrent contact with the potassium carbonate solution flowing down from top to bottom. The material from the top of absorber C3 is condensed in absorber condenser E6 and then enters the absorber for gas-liquid separation. The gaseous material obtained at the top of tank V2 is partially mixed with the propylene circulating gas from the top of gas-liquid separator C1 as decarbonized propylene circulating gas, and then sent to circulating gas-liquid separator V1 to achieve the recycling of propylene and oxygen. The bottom liquid of absorber C3 is a rich liquid after carbon dioxide absorption. After depressurization, it is heated by rich liquid heater E7 and sent to rich liquid flash tank V3 to remove most of the propylene dissolved in the rich liquid, and then sent to degasser V5. The liquid phase material in rich liquid flash tank V3 is sent to the top of desorption tower C4 for carbon dioxide desorption. The material at the top of desorption tower C4 is condensed by desorption tower condenser E8 and then sent to desorption tower gas-liquid separator V4 to obtain gas with carbon dioxide as the main component. This gas is discharged from the system to avoid carbon dioxide accumulation. The liquid phase material in desorption tower gas-liquid separator V4 is mixed with the lean liquid at the bottom of desorption tower C4 and the liquid phase material in absorber gas-liquid separator V4, and then mixed with additional potassium carbonate solution to obtain lean liquid, which is recycled back to the top of absorber C3.

[0039] In this specific embodiment, a denitrification process is incorporated to remove nitrogen from the propylene circulating gas, preventing the accumulation of inert gases. During the denitrification process, a portion of the gaseous material from the gas-liquid separator V2 in the absorber is sent to the membrane separator PK1 to remove nitrogen, thus solving the problem of nitrogen accumulation during propylene acetate production. The material with nitrogen as its main component is treated as tail gas and then discharged. The material with propylene as its main component is used as the denitrified propylene circulating gas, which is mixed with the gas stream from the degassing tank tail gas-liquid separator V7, and then pressurized by the recovery gas compressor K2 before being recycled to the decarbonization process.

[0040] In this specific embodiment, a refining system is established based on the boiling points and compositions of each product and azeotrope, and a reasonable separation strategy is proposed. The refining system mainly includes an acetic acid removal tower C5, a crude propylene acetate tower C6, a refined propylene acetate tower C7, a light propylene acetate removal tower C8, a dehydration tower C9, an acetic acid removal tower condenser E11, an acetic acid removal tower condensate cooler E12, a crude propylene acetate tower condenser E13, a crude propylene acetate tower condensate cooler E14, a refined propylene acetate tower condenser E15, a refined propylene acetate tower condensate cooler E16, a light propylene acetate removal tower condenser E17, a light propylene acetate removal tower tail gas condenser E18, a light propylene acetate removal tower condensate cooler E19, and an acetic acid removal tower... V8, V9, V10, V11, V12, V13, V14, V14, V15, P16, P17, P18, P19, P20, P30, P30, P40, P50, P50, P60, P60, P70, P80, P90, P10, P11, P20, P30, P30, P40, P50, P50, P60, P60, P70, P80, P90, P10, P11, P20, P30, P30, P40, P50, P50, P60, P60, P70, P80, P90, P10, P11, P12, P20, P30, P30, P40, P50, P50, P60, P60, P70, P10, P11, P12, P13, P140, P150, P160, P170, P180, P180, P19 ... The system comprises the following components: aqueous phase reflux distributor F3, oil phase reflux distributor F4, crude propylene acetate tower reflux distributor F5, refined propylene acetate tower outlet distributor F6, light ester removal tower outlet distributor F7, crude propylene acetate tower overhead gas phase mixer M11, light ester removal tower outlet mixer M12, and dehydration tower feed mixer M13. The refining system consists of an acetic acid removal process, a propylene acetate refining process, a light ester removal process, and a dehydration process. The acetic acid removal process mainly includes the acetic acid removal tower and its auxiliary equipment, and the propylene acetate... The refining process mainly includes a crude propylene acetate tower and a refined propylene acetate tower and their auxiliary equipment. The light-weight component removal process mainly includes a light-weight component removal tower and its auxiliary equipment. The dehydration process mainly includes a dehydration tower and its auxiliary equipment. The connections between the equipment in the refining system are as follows: the inlet of the deacetic acid tower C5 is connected to the propylene acetate synthesis system, the outlet of the aqueous phase reflux distributor F3 of the deacetic acid tower, the outlet of the oil phase reflux distributor F4 of the deacetic acid tower, and the bottom outlet of the refined propylene acetate tower C7. The top outlet of the deacetic acid tower is connected to the inlet of the condenser E11 of the deacetic acid tower. The inlet of the crude propylene acetate tower C6 is connected to the outlet of the oil phase reflux distributor F4 of the deacetic acid tower, the outlet of the reflux distributor F5 of the crude propylene acetate tower, and the bottom outlet of the light-weight component removal tower C8. The top outlet of the crude propylene acetate tower is connected to the inlet of the gas phase mixer M11 at the top of the crude propylene acetate tower. The bottom outlet of the crude propylene acetate tower C7 is connected to the inlet of the condenser E15 of the refined propylene acetate tower. The outlet of the refined propylene acetate tower's outlet distributor F6 is connected to the inlet of the refined propylene acetate tower C7 and the propylene acetate outlet pipeline. The inlet of the light propylene acetate removal tower C8 is connected to the outlet of the crude propylene acetate tower's reflux distributor F5, and the tower's top outlet is connected to the inlet of the light propylene acetate removal tower condenser E17. The inlet of the light propylene acetate removal tower's outlet distributor F7 is connected to the outlet of the light propylene acetate removal tower's outlet pump P5, and the outlet is connected to the inlet of the light propylene acetate removal tower C8 and the outlet pipeline.The inlet of the dehydration tower C9 is connected to the outlet of the dehydration tower feed pump P6, the top outlet of the tower is connected to the inlet of the gas phase mixer M11 at the top of the crude propylene acetate tower, and the bottom outlet of the tower is connected to the wastewater treatment device.

[0041] In this specific embodiment, during the acetic acid removal process, the liquid phase material from the bottom of the degassing tank V5 and the liquid phase material from the bottom of the refined propylene acetate tower C7 are fed into the acetic acid removal tower C5 together. The gaseous material at the top of the tower is a light component composed of propionaldehyde, acrolein, an azeotrope of propylene acetate and water, and an azeotrope of propyl acetate and water. After being condensed by the acetic acid removal tower condenser E11, it enters the acetic acid removal tower gas-liquid separator V8. The liquid phase material in the acetic acid removal tower gas-liquid separator V8 is cooled by the acetic acid removal tower condensate cooler E12 and then sent to the acetic acid removal tower distillation phase separation tank V9 for phase separation. Part of the aqueous phase material is returned to the acetic acid removal tower C5, and the other part is sent to the dehydration tower C9. Part of the oil phase material is returned to the acetic acid removal tower C5, and the other part is sent to the crude propylene acetate tower C6.

[0042] In this specific embodiment, during the refining process of propylene acetate, the liquid phase material from the top oil phase of the deacetic acid removal tower C5 and the liquid phase material from the bottom of the light phase removal tower C8 are fed together into the crude propylene acetate tower C6. The gaseous material at the top of the tower is a light component composed of azeotropes of propionaldehyde and water, acrolein and water, propylene acetate and water, and propylene acetate and water. After mixing with the gaseous material from the top of the dehydration tower C9, it is sent to the crude propylene acetate tower condenser E13 for condensation, and then enters the crude propylene acetate tower gas-liquid separator V10. The liquid phase material in the crude propylene acetate tower gas-liquid separator V10 is cooled by the crude propylene acetate tower condensate cooler E14 and then sent to the crude propylene acetate tower distillation phase separation tank V11 for phase separation. The aqueous phase material is mixed with the aqueous phase product from the top of the deacetic acid removal tower C5 and then sent to the dehydration tower C9 for processing. Part of the oil phase material is recycled back to the crude propylene acetate tower. The remaining portion of the product from the propylene acetate column C6 is sent to the light ester removal column C8. The heavy component, consisting of propylene acetate and propyl acetate, obtained from the bottom of the crude propylene acetate column C6 after the removal of propionaldehyde, acrolein, and water, is sent to the refined propylene acetate column C7 for further processing. The liquid phase from the bottom of the crude propylene acetate column C6 is sent to the refined propylene acetate column C7. The gaseous material at the top of the column, being high-purity propylene acetate, is cooled by the condenser E15 before entering the gas-liquid separator V12. The liquid phase in the gas-liquid separator V12 is cooled by the condensate cooler E16 and partially refluxed to the top of the refined propylene acetate column C7, while the remaining portion is collected to obtain high-purity propylene acetate with a mass fraction ≥99.9%. The heavy component, mainly composed of propylene acetate and propyl acetate, obtained from the bottom of the column is sent to the deacetic acid removal column C5 along with the feed from C5 for recycling.

[0043] In this specific embodiment, during the removal of light esters, the oil phase product from the top of the crude propylene acetate tower C6 is fed into the light ester removal tower C8; the gaseous product at the top of the tower is enriched with propionaldehyde and acrolein, and after being cooled by the light ester removal tower condenser E17, it enters the light ester removal tower gas-liquid separator V13; the gaseous product in the light ester removal tower gas-liquid separator V13 is cooled by the light ester removal tower tail gas condenser E18, and then enters the light ester removal tower tail gas-liquid separator V14, where the gaseous product is sent to the tail gas... In the gas treatment process, the liquid phase material is refluxed and collected as condensate. After being cooled by the condensate cooler E19 in the gas-liquid separator of the light-light removal tower, the liquid phase material in the gas-liquid separator V14 of the light-light removal tower tail gas is mixed with the liquid phase material in the gas-liquid separator V14 of the light-light removal tower. Part of the mixture is refluxed to the top of the light-light removal tower C8, and the other part is collected. The bottom of the light-light removal tower C8 yields a heavy component composed of water, propylene acetate, and propyl acetate, which has been depropanol and acrolein removed. This component is then sent to the crude propylene acetate tower C6 for recycling.

[0044] In this specific embodiment, during the dehydration process, the aqueous phase material from the top of the deacetic acid tower C5 and the aqueous phase material from the top of the crude propylene acetate tower C6 are mixed and then fed to the top of the dehydration tower C9. The gaseous material at the top of the tower is an azeotrope of water and propylene acetate and an azeotrope of water and propyl acetate. After being mixed with the material from the top of the crude propylene acetate tower C6, it is sent to the condenser E13 of the crude propylene acetate tower. The liquid phase material with water as the main component obtained from the bottom of the dehydration tower C9 is sent to the wastewater treatment plant.

[0045] In this specific embodiment, the steam generated by the heat transfer from the oxidation reactor is applied to the reboilers of desorption tower C4, deacetic acid tower C5, crude propylene acetate tower C6, and refined propylene acetate tower C7. Then, through multi-stage utilization of low-pressure steam, the steam condensate obtained from the reboilers of desorption tower C4, deacetic acid tower C5, crude propylene acetate tower C6, and refined propylene acetate tower C7 is flash-evaporated, and the resulting low-pressure steam is further applied to the reboilers of light propylene removal tower C8 and dehydration tower C9.

[0046] In this specific embodiment, the operating pressure of gas-liquid separation tower C1 is 0.85-1.05 MPaA, the operating pressure of water washing tower C2 is 1.05-1.25 MPaA, the operating pressure of absorption tower C3 is 0.90-1.10 MPaA, the operating pressure of desorption tower C4 is 0.04-0.24 MPaA, and the operating pressure of degassing tank V5 is 0.05-0.15 MPaA; the washing acetic acid flow rate of gas-liquid separation tower C1 is 9500-10500 kg·h. -1 The acetic acid flow rate for washing in water washing tower C2 is 2000-3000 kg·h. -1 The water flow rate is 200-300 kg·h -1The operating pressure of the acetic acid removal tower C5 is 0.05-0.15 MPaA, the operating pressure of the crude propylene acetate tower C6 is 0.05-0.15 MPaA, the operating pressure of the refined propylene acetate tower C7 is 0.05-0.15 MPaA, the operating pressure of the light propylene acetate removal tower C8 is 0.05-0.15 MPaA, and the operating pressure of the dehydration tower C9 is 0.05-0.15 MPaA.

[0047] The following specific examples illustrate the implementation process of the method in this application.

[0048] Example 1: like Figure 1 As shown, the raw materials propylene, acetic acid and oxygen are mixed and fed into the reaction process to carry out the acetoxylation reaction to produce propylene acetate; the product obtained from the reaction process is separated into gas and liquid, and the liquid is sent to the purification system. After separation and purification, high-purity propylene acetate product is obtained, and the gas is propylene recycle gas.

[0049] Part of the propylene recycle gas is fed into the reaction process for recycling, and the other part is fed into the decarbonization process to remove CO2. The gas after CO2 removal is called decarbonized propylene recycle gas, part of which is fed into the reaction process for recycling, and the other part is fed into the denitrification process to remove N2. The gas after N2 removal is called denitrified propylene recycle gas, and all of it is fed into the reaction process for recycling.

[0050] like Figure 3 As shown, the liquid material from the reaction process is fed into the deacetic acid tower in the deacetic acid removal process. The azeotrope formed by propionaldehyde, acrolein, propyl acetate, and propylene acetate and water is collected from the top of the tower. The bottom of the tower yields a heavy component consisting of a small amount of water, acetic acid, allyl acrylate, acrylic acid, and allyl diacetate. The deacetic acid tower performs side sampling to obtain a liquid material rich in propyl acetate. The gaseous material at the top of the deacetic acid tower is condensed and sent to a phase separator to separate into an aqueous phase and an oil phase. Part of the aqueous phase is refluxed back to the deacetic acid tower, and the other part is sent to the dehydration tower. Part of the oil phase is refluxed back to the deacetic acid tower, and the other part is sent to the crude propylene acetate tower.

[0051] In the refining process of propylene acetate, the crude propylene acetate tower collects acrolein, propionaldehyde, and the azeotrope formed by propylene acetate and water as light components from the top of the tower, while the bottom of the tower yields a liquid material that is anhydrous and whose main components are propylene acetate and propyl acetate. The gaseous material from the top of the crude propylene acetate tower is condensed and sent to a phase separator to separate into an aqueous phase and an oil phase. All of the aqueous phase is sent to a dehydration tower, part of the oil phase is refluxed, and the other part is sent to a light component removal tower. The liquid material from the bottom of the crude propylene acetate tower is sent to the refined propylene acetate tower.

[0052] High-purity propylene acetate product is obtained from the top of the propylene acetate refining tower during the propylene acetate refining process, while the bottom of the tower yields a liquid material whose main component is propylene acetate, which is then recycled back to the deacetic acid desulfurization tower for further treatment.

[0053] In the process of removing light components, the light component removal tower collects light components such as propionaldehyde, acrolein and a small amount of propyl acetate from the top of the tower, and obtains a liquid material with water, propyl acetate and propylene acetate as the main components in the bottom of the tower, which is recycled back to the crude propylene acetate tower for further processing.

[0054] In the dehydration process, the dehydration tower collects the azeotrope formed by water and propylene acetate as a light component from the top of the tower and recycles it back to the crude propylene acetate tower for further treatment; the bottom of the tower yields a liquid material with water as the main component, which is then sent to wastewater treatment.

[0055] like Figure 2 As shown, the synthesis system includes an oxidation reactor R1, a gas-liquid separation tower C1, a water washing tower C2, an absorption tower C3, a desorption tower C4, a circulating gas compressor K1, a recovery gas compressor K2, a first reaction gas cooler E1, a second reaction gas cooler E2, a circulating propylene preheater E3, a third reaction gas cooler E4, a recovery gas cooler E5, an absorption tower condenser E6, a rich liquid heater E7, a desorption tower condenser E8, a circulating gas-liquid separator V1, an absorption tower gas-liquid separator V2, a rich liquid flash evaporator V3, a desorption tower gas-liquid separator V4, a degassing tank V5, a degassing tank gas-liquid separator V6, a degassing tank tail gas-liquid separator V7, an oxygen mixer M3, and a membrane separation unit PK1.

[0056] In the reaction process, fresh propylene FD1 is mixed with circulating gas from circulating gas compressor K1; the mixed gas passes through the second reaction gas cooler E2 and exchanges heat with the reaction gas from the first reaction gas cooler E1; then it is mixed with fresh acetic acid FD2; the mixture of acetic acid and propylene passes through the first reaction gas cooler E1 and exchanges heat with the reaction gas from oxidation reactor R1, then is heated by circulating propylene preheater E3, and then mixed with fresh oxygen FD3 by oxygen mixer M3 to obtain a mixed gaseous material of propylene, acetic acid and oxygen, which is sent to oxidation reactor R1 for acetoxylation reaction to produce propylene acetate; the reaction gas obtained from the outlet of oxidation reactor R1 is cooled by the first reaction gas cooler E1, the second reaction gas cooler E2 and the third reaction gas cooler E4, and then sent to gas-liquid separation tower C1.

[0057] The oxidation reactor is a heat-transfer fixed-bed reactor. The reactor tube side is filled with Pd-based catalyst with active components distributed in an eggshell pattern and undergoes an acetoxylation reaction. The reactor shell side uses pressurized water circulation to remove the heat of reaction in a timely manner. The reactor inlet material contains carbon dioxide and nitrogen, with a carbon dioxide concentration of 20 mol% and a nitrogen concentration of 8 mol%.

[0058] In the propylene circulation process, the reactor outlet stream is cooled by the first reaction gas cooler E1, the second reaction gas cooler E2, and the third reaction gas cooler E4 before being sent to the bottom of the gas-liquid separator C1. The top stream of the gas-liquid separator C1, which is the propylene circulating gas, is sent to the circulating gas-liquid separator V1, while the bottom stream is sent to the degassing tank V5. The degassing tank V5 receives the liquid material from the circulating gas-liquid separator V1, the bottom liquid from the gas-liquid separator C1, the bottom liquid from the water washing tower C2, and the gaseous material from the rich liquid flash evaporator V3. Through reduced pressure flash evaporation, the propylene, oxygen, carbon dioxide, and other gases in the mixture are extracted from the top and sent to the decarbonization degassing tank. The process includes denitrification; the liquid phase material, mainly composed of propylene acetate, acetic acid, and water, is collected from the bottom and sent to the propylene acetate refining system to obtain high-purity propylene acetate product; the gaseous material from the top of degassing tank V5 is condensed by degassing tank condenser E9 and then enters degassing tank gas-liquid separator V6; the gaseous material in degassing tank gas-liquid separator V6 is cooled by degassing tank tail gas condenser E10 and then sent to degassing tank tail gas-liquid separator V7; the gaseous stream in V7 is sent to the subsequent water washing tower C2, and the liquid phase material is mixed with the liquid phase material in V6 and then recycled back to degassing tank V5; the operating pressure of gas-liquid separator C1 is 0.85 MPaA, and the operating pressure of degassing tank V5 is 0.05 MPaA.

[0059] In the decarbonization process, the middle section of the water washing tower C2 uses fresh acetic acid FD5 for washing to remove propylene acetate from the recovered gas; the top of the water washing tower C2 uses water FD6 for washing to remove the recovered gas and the acetic acid introduced by the fresh acetic acid FD5; the gaseous material from the circulating gas-liquid separator V1 is pressurized by the circulating gas compressor K1, and part of the circulating gas is sent to the decarbonization process; the gaseous material from the degassing tank V5 is the recovered gas, which is pressurized by the recovered gas compressor K2, mixed with the circulating gas, and then sent to the water... Washing tower C2 recovers propylene acetate and acetic acid, and the recovered gas from the top of washing tower C2 is sent to absorption tower C3. The main components of the bottom stream of washing tower C2 are acetic acid and propylene acetate, which are sent to degassing tank V5. Carbon dioxide is removed using the hot potassium carbonate method. The material from the top of washing tower C2 enters absorption tower C3 from the bottom, where it comes into full countercurrent contact with the potassium carbonate solution flowing down from the top. The material from the top of absorption tower C3 is condensed in absorption tower condenser E6 and then enters absorption tower gas-liquid separator V2. The resulting gaseous material is partially mixed with the propylene circulating gas from the top of gas-liquid separator C1 as decarbonized propylene circulating gas, and then sent to circulating gas-liquid separator V1 to achieve the recycling of propylene and oxygen. The bottom liquid of absorber C3, which is the rich liquid after carbon dioxide absorption, is depressurized and then heated by rich liquid heater E7 before being sent to rich liquid flash tank V3 to remove most of the propylene dissolved in the rich liquid, and then sent to degassing tank V5. The liquid phase material in rich liquid flash tank V3 is sent to the top of desorption tower C4 for further processing. Carbon dioxide desorption: The material at the top of desorption tower C4 is condensed in desorption tower condenser E8 and then sent to desorption tower gas-liquid separator V4 to obtain gas with carbon dioxide as the main component. This gas is then discharged from the system to prevent carbon dioxide accumulation. The liquid phase material in desorption tower gas-liquid separator V4 is mixed with the lean liquid from the bottom of desorption tower C4 and the liquid phase material from the absorption tower gas-liquid separator. This mixture is then mixed with additional potassium carbonate solution to obtain a lean liquid, which is recycled back to the top of absorption tower C3. The operating pressure of water washing tower C2 is 1.05 MPaA, the operating pressure of absorption tower C3 is 0.90 MPaA, and the operating pressure of desorption tower C4 is 0.04 MPaA. The washing acetic acid flow rate of gas-liquid separator C1 is 9500 kg·h. -1 The acetic acid flow rate for washing in water washing tower C2 is 2000 kg·h. -1 The water flow rate is 200 kg·h -1 .

[0060] In the denitrification process, part of the gas in the gas phase material of the gas-liquid separator V2 of the absorber is sent to the membrane separation unit PK1 to remove nitrogen and solve the problem of nitrogen accumulation in the production of propylene acetate. The material with nitrogen as the main component is discharged after tail gas treatment, and the material with propylene as the main component is used as denitrification propylene circulating gas. After mixing with the gas phase stream from the tail gas gas-liquid separator V7 of the degassing tank, it is pressurized by the recovery gas compressor K2 and sent to the decarbonization process in a cycle.

[0061] like Figure 4 As shown, the refining system includes an acetic acid removal tower C5, a crude propylene acetate tower C6, a refined propylene acetate tower C7, a light propylene acetate removal tower C8, a dehydration tower C9, an acetic acid removal tower condenser E11, an acetic acid removal tower condensate cooler E12, a crude propylene acetate tower condenser E13, a crude propylene acetate tower condensate cooler E14, a refined propylene acetate tower condenser E15, a refined propylene acetate tower condensate cooler E16, a light propylene acetate removal tower condenser E17, a light propylene acetate removal tower tail gas condenser E18, a light propylene acetate removal tower condensate cooler E19, an acetic acid removal tower gas-liquid separator V8, an acetic acid removal tower distillate phase separation tank V9, a crude propylene acetate tower gas-liquid separator V10, a crude propylene acetate tower distillate phase separation tank V11, a refined propylene acetate tower gas-liquid separator V12, a light propylene acetate removal tower gas-liquid separator V13, and a light propylene acetate removal tower tail gas-liquid separator V14.

[0062] The liquid phase material from the bottom of the degassing tank V5 and the liquid phase material from the bottom of the refined propylene acetate tower C7 are fed into the deacetic acid tower C5. The gaseous material at the top of the tower, consisting of a light component composed of propionaldehyde, acrolein, an azeotrope of propylene acetate and water, and an azeotrope of propyl acetate and water, is condensed in the deacetic acid tower condenser E11 and then enters the deacetic acid tower gas-liquid separator V8. The liquid phase material in the deacetic acid tower gas-liquid separator V8 is cooled by the deacetic acid tower condensate cooler E12 and then sent to the deacetic acid tower distillate phase separation tank V9 for phase separation. Part of the aqueous phase material is refluxed back to the deacetic acid tower C5, and the other part is sent to the dehydration tower C9. Part of the oil phase material is refluxed back to the deacetic acid tower C5, and the other part is sent to the crude propylene acetate tower C6. The operating pressure of the deacetic acid tower C5 is 0.05 MPaA.

[0063] The liquid phase material from the top of the acetic acid removal tower C5 and the liquid phase material from the bottom of the light propylene acetate removal tower C8 are fed together into the crude propylene acetate tower C6. The gaseous material from the top of the tower, consisting of a light component composed of azeotropes of propionaldehyde and water, acrolein and water, propyl acetate and water, and propylene acetate and water, is mixed with the gaseous material from the top of the dehydration tower C9 and then sent to the crude propylene acetate tower condenser E13 for condensation before entering the crude propylene acetate tower gas-liquid separator V10. The crude propylene acetate tower gas-liquid separator V10... The liquid phase material in column 0 is cooled by the crude propylene acetate column condensate cooler E14 and then sent to the crude propylene acetate column distillation phase separation tank V11 for phase separation. The aqueous phase material is mixed with the aqueous phase product from the top of the deacetic acid removal column C5 and then sent to the dehydration column C9 for processing. Part of the oil phase material is refluxed to the crude propylene acetate column C6, and the other part is sent to the light phase removal column C8. After the propionaldehyde, acrolein, and water are removed from the bottom of the crude propylene acetate column C6, the heavy component composed of propylene acetate and propyl acetate is sent to the refined propylene acetate column C7 for processing. The operating pressure of the crude propylene acetate column C6 is 0.05 MPaA.

[0064] The liquid material from the bottom of the crude propylene acetate tower (C6) is fed into the refined propylene acetate tower (C7). The gaseous material at the top of the tower, which is high-purity propylene acetate, is cooled by the condenser (E15) before entering the gas-liquid separator (V12). The liquid material in the gas-liquid separator (V12) is cooled by the condensate cooler (E16) and partially refluxed to the top of the refined propylene acetate tower (C7), while the remaining portion is collected to obtain high-purity propylene acetate with a mass fraction of 99.91%. The bottom of the tower contains a heavy component consisting mainly of propylene acetate and propyl acetate, which is fed into the deacetic acid tower (C5) along with the feed from C5 for recycling. The operating pressure of the refined propylene acetate tower (C7) is 0.05 MPaA.

[0065] The process involves sending the oil phase from the top of the crude propylene acetate tower C6 to the light-duty removal tower C8. The gaseous material at the top of the tower, enriched with propionaldehyde and acrolein, is cooled by the light-duty removal tower condenser E17 before entering the light-duty removal tower gas-liquid separator V13. The gaseous material in the gas-liquid separator V13 is cooled by the light-duty removal tower tail gas condenser E18 before entering the light-duty removal tower tail gas-liquid separator V14. The gaseous material is sent for tail gas treatment, while the liquid material is refluxed and collected as condensate. The liquid material in the light-duty removal tower gas-liquid separator V13 is cooled by the light-duty removal tower condensate cooler E19, then mixed with the liquid material in the light-duty removal tower tail gas-liquid separator V14. Part of the mixture is refluxed back to the top of the light-duty removal tower C8, and the other part is collected. The bottom of the light-duty removal tower C8 yields a heavy component composed of water, propylene acetate, and propyl acetate, after the removal of propionaldehyde and acrolein, which is then recycled back to the crude propylene acetate tower C6. The operating pressure of the light removal tower C8 is 0.05 MPaA.

[0066] The aqueous phase material from the top of the deacetic acid removal tower C5 and the aqueous phase material from the top of the crude propylene acetate tower C6 are mixed and then fed to the top of the dehydration tower C9. The gaseous phase material at the top of the towers consists of an azeotrope of water and propylene acetate, and an azeotrope of water and propyl acetate. This mixture is then sent to the condenser E13 of the crude propylene acetate tower after being mixed with the material from the top of the crude propylene acetate tower C6. The liquid phase material obtained from the bottom of the dehydration tower C9, whose main component is water, is sent to wastewater treatment. The operating pressure of the dehydration tower C9 is 0.05 MPaA.

[0067] Specifically, the steam generated by the heat transfer from the oxidation reactor is applied to the reboilers of desorption tower C4, deacetic acid tower C5, crude propylene acetate tower C6, and refined propylene acetate tower C7. Then, through multi-stage utilization of low-pressure steam, the steam condensate obtained from the reboilers of desorption tower C4, deacetic acid tower C5, crude propylene acetate tower C6, and refined propylene acetate tower C7 is flash-evaporated, and the resulting low-pressure steam is further applied to the reboilers of light propylene removal tower C8 and dehydration tower C9.

[0068] Example 2: The processes and apparatus used are the same as in Example 1, so the details will not be repeated. The differences are explained below: Synthesis System: The reactor inlet feed contains carbon dioxide and nitrogen, with a carbon dioxide concentration of 24 mol% and a nitrogen concentration of 5 mol%. The operating pressure of gas-liquid separator C1 is 0.95 MPaA, and the operating pressure of degassing tank V5 is 0.10 MPaA. The operating pressures of water washing tower C2, absorption tower C3, and desorption tower C4 are 1.00 MPaA and 0.14 MPaA, respectively. The acetic acid flow rate for washing in gas-liquid separator C1 is 10000 kg·h. -1 The acetic acid flow rate for washing in water washing tower C2 is 2500 kg·h. -1 The water flow rate is 250 kg·h -1 .

[0069] Refining System: The operating pressure of the acetic acid removal tower C5 is 0.10 MPaA, the operating pressure of the crude propylene acetate tower C6 is 0.10 MPaA, the operating pressure of the refined propylene acetate tower C7 is 0.10 MPaA, the operating pressure of the light propylene acetate removal tower C8 is 0.10 MPaA, and the operating pressure of the dehydration tower C9 is 0.10 MPaA, thus obtaining a high-purity propylene acetate product with a mass fraction of 99.94%.

[0070] Example 3: The processes and apparatus used are the same as in Example 1, so the details will not be repeated. The differences are explained below: Synthesis System: The reactor inlet feed contains carbon dioxide and nitrogen, with a carbon dioxide concentration of 28 mol% and a nitrogen concentration of 2 mol%. The operating pressure of gas-liquid separator C1 is 1.05 MPaA, and the operating pressure of degassing tank V5 is 0.15 MPaA. The operating pressures of water washing tower C2, absorption tower C3, and desorption tower C4 are 1.10 MPaA and 0.24 MPaA, respectively. The acetic acid flow rate for washing in gas-liquid separator C1 is 10500 kg·h. -1 The acetic acid flow rate for washing in water washing tower C2 is 3000 kg·h. -1 The water flow rate is 300 kg·h -1 .

[0071] Refining System: The operating pressure of the acetic acid removal tower C5 is 0.15 MPaA, the operating pressure of the crude propylene acetate tower C6 is 0.15 MPaA, the operating pressure of the refined propylene acetate tower C7 is 0.15 MPaA, the operating pressure of the light propylene acetate removal tower C8 is 0.15 MPaA, and the operating pressure of the dehydration tower C9 is 0.15 MPaA, thus obtaining a high-purity propylene acetate product with a mass fraction of 99.92%.

[0072] The technical solutions disclosed and proposed in this invention can be implemented by those skilled in the art by appropriately modifying the conditions and routes, etc. Although the methods and preparation techniques of this invention have been described through preferred embodiments, those skilled in the art can obviously modify or recombine the methods and technical routes described herein without departing from the content, spirit, and scope of this invention to achieve the final preparation technique. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included within the spirit, scope, and content of this invention.

Claims

1. A process for producing high-purity propylene acetate using propylene as a raw material; characterized in that, It includes a synthesis system and a refining system. The synthesis system consists of a reaction process, a propylene recycling process, a decarbonization process, and a denitrification process. The refining system includes a deacetic acid removal process, a propylene acetate refining process, a light precipitate removal process, and a dehydration process.

2. The production process of high-purity propylene acetate using propylene as raw material as described in claim 1; characterized in that, The specific process includes the following steps: (1) The raw materials propylene, acetic acid and oxygen are mixed and fed into the reaction process to carry out acetoxylation reaction to generate propylene acetate; the product obtained from the reaction process is separated by gas and liquid, and the liquid is sent into the purification system. After separation and purification, high-purity propylene acetate product is obtained, and the gas is propylene recycle gas. (2) Part of the propylene recycle gas is sent to the reaction process for recycling, and the other part is sent to the decarbonization process to remove CO2; the gas after CO2 removal is the decarbonized propylene recycle gas, part of which is sent to the reaction process for recycling, and the other part is sent to the denitrification process to remove N2; the gas after N2 removal is the denitrified propylene recycle gas, and all of it is sent to the reaction process for recycling. (3) The liquid material from the reaction process is fed into the deacetic acid removal process. The azeotrope formed by propionaldehyde, acrolein, propyl acetate, and propylene acetate and water is collected from the top of the distillation column in the deacetic acid removal process. The bottom of the distillation column is filled with a heavy component consisting of a small amount of water, acetic acid, allyl acrylate, acrylic acid, and allyl diacetate. The distillation column is side-collected to obtain a liquid material rich in propyl acetate. The gaseous material from the top of the distillation column in the deacetic acid removal process is condensed and sent to the phase separation unit, where it is divided into an aqueous phase and an oil phase. Part of the aqueous phase is refluxed to the deacetic acid removal process, and the other part is sent to the dehydration process. Part of the oil phase is refluxed to the deacetic acid removal process, and the other part is sent to the propylene acetate refining process. (4) In the refining process of propylene acetate, the distillation column for refining crude propylene acetate collects acrolein, propionaldehyde, and the azeotrope formed by propylene acetate and water as light components from the top of the column, and obtains a liquid material from the bottom of the column that is free of water and whose main components are propylene acetate and propyl acetate; the gaseous material from the top of the distillation column is condensed and sent to the phase separation unit, which separates it into an aqueous phase and an oil phase. All of the aqueous phase is sent to the dehydration process; part of the oil phase is refluxed and the other part is sent to the light component removal process; the liquid material from the bottom of the distillation column is sent to the distillation column for refining propylene acetate in the refining process of propylene acetate. (5) High-purity propylene acetate product is obtained from the top of the distillation column for refining propylene acetate, and liquid material with propylene acetate as the main component is obtained from the bottom of the column. It is recycled back to the deacetic acid removal process for further processing. (6) During the removal of light components, propionaldehyde, acrolein and a small amount of propyl acetate are collected from the top of the distillation column during the removal of light components. The bottom of the column contains a liquid material with water, propyl acetate and propylene acetate as the main components, which is recycled back to the propylene acetate refining process. The removal of light components removes propionaldehyde, acrolein and a small amount of propyl acetate, and recovers the remaining propylene acetate. (7) During the dehydration process, the azeotrope formed by water and propylene acetate is taken out as a light component from the top of the distillation column during the dehydration process and recycled back to the propylene acetate refining process for treatment; the bottom of the column obtains a liquid material with water as the main component, which is sent to wastewater treatment; the dehydration process removes water and recovers the remaining propylene acetate.

3. An apparatus for implementing the high-purity propylene acetate production process using propylene as raw material as described in claim 1 or 2, characterized in that, The synthesis system mainly includes an oxidation reactor R1, a gas-liquid separator C1, a water washing tower C2, an absorption tower C3, a desorption tower C4, a circulating gas compressor K1, a recovery gas compressor K2, a first reactant gas cooler E1, a second reactant gas cooler E2, a circulating propylene preheater E3, a third reactant gas cooler E4, a recovery gas cooler E5, an absorption tower condenser E6, a rich liquid heater E7, a desorption tower condenser E8, a circulating gas-liquid separator V1, an absorption tower gas-liquid separator V2, a rich liquid flash evaporator V3, a desorption tower gas-liquid separator V4, a degassing tank V5, a degassing tank gas-liquid separator V6, a degassing tank tail gas-liquid separator V7, a propylene feed mixer M1, an acetic acid feed mixer M2, and an oxygen mixer. The system includes: M3 (mixer), M4 (propylene circulating gas mixer), M5 (pressurized circulating gas mixer), M6 (denitrile propylene circulating gas mixer), M7 (lean liquor mixer), M8 (potassium carbonate solution mixer), M9 (degassing tank liquid phase circulating mixer), M10 (degassing tank feed mixer), F1 (first circulating gas splitter), F2 (second circulating gas splitter), and PK1 (membrane separator). The oxygen mixer M3 inlet is connected to the outlet of the circulating propylene preheater E3 and a fresh oxygen pipeline, and its outlet is connected to the inlet of the oxidation reactor R1. The outlet of the oxidation reactor R1 is connected to the inlet of the first reaction gas cooler E1. The outlet of the propylene feed mixer M1 is connected to the inlet of the second reaction gas cooler E2. The inlet of the acetic acid feed mixer M2 is connected to the outlet of the second reaction gas cooler E2. The system connects to the fresh acetic acid pipeline, with its outlet connected to the inlet of the first reaction gas cooler E1; the inlet of the circulating propylene preheater E3 connects to the outlet of the first reaction gas cooler E1; the outlet of the first reaction gas cooler E1 connects to the inlet of the second reaction gas cooler E2; the inlet of the third reaction gas cooler E4 connects to the outlet of the second reaction gas cooler E2, and its outlet connects to the inlet of the gas-liquid separator C1; the top outlet of the gas-liquid separator C1 connects to the inlet of the propylene circulating gas mixer M4, and the bottom outlet connects to the inlet of the degassing tank feed mixer M10; the outlet of the recovered gas cooler E5, the fresh acetic acid pipeline, and the process water pipeline connect to the inlet of the water washing tower C2; the top outlet of the water washing tower C2 connects to the inlet of the absorption tower C3, and the bottom outlet connects to the inlet of the degassing tank. The feed mixer M10 inlet is connected; the potassium carbonate solution mixer M8 outlet is connected to the absorber C3 inlet; the absorber C3 top outlet is connected to the absorber condenser E6 inlet, and the bottom outlet is connected to the rich liquid heater E7 inlet; the rich liquid flash tank V3 top outlet is connected to the degassing tank feed mixer M10 inlet, and the bottom outlet is connected to the desorption tower C4 inlet; the desorption tower C4 top outlet is connected to the desorption tower condenser E8 inlet, and the bottom outlet is connected to the lean liquid mixer M7 inlet; the degassing tank feed mixer M10 outlet and the degassing tank liquid phase circulation mixer M9 outlet are connected to the degassing tank V5 inlet; the degassing tank V5 top outlet is connected to the degassing tank condenser E9 inlet, and the bottom outlet is connected to the propylene acetate refining system.

4. An apparatus for implementing the high-purity propylene acetate production process using propylene as a raw material as described in claim 1 or 2, characterized in that, The refining system mainly includes: acetic acid removal tower C5, crude propylene acetate tower C6, refined propylene acetate tower C7, light propylene acetate removal tower C8, dehydration tower C9, acetic acid removal tower condenser E11, acetic acid removal tower condensate cooler E12, crude propylene acetate tower condenser E13, crude propylene acetate tower condensate cooler E14, refined propylene acetate tower condenser E15, refined propylene acetate tower condensate cooler E16, light propylene acetate removal tower condenser E17, light propylene acetate removal tower tail gas condenser E18, light propylene acetate removal tower condensate cooler E19, acetic acid removal tower gas-liquid separator V8, acetic acid removal tower distillate phase separation tank V9, crude propylene acetate tower gas-liquid separator V10, and crude propylene acetate tower... Distillation phase separation tank V11, refined propylene acetate tower gas-liquid separator V12, light propylene acetate removal tower gas-liquid separator V13 and light propylene acetate removal tower tail gas-liquid separator V14, acetic acid removal tower oil phase reflux pump P1, acetic acid removal tower aqueous phase reflux pump P2, crude propylene acetate tower reflux pump P3, refined propylene acetate tower outlet pump P4, light propylene acetate removal tower outlet pump P5, dehydration tower feed pump P6, acetic acid removal tower aqueous phase reflux distributor F3, acetic acid removal tower oil phase reflux distributor F4, crude propylene acetate tower reflux distributor F5, refined propylene acetate tower outlet distributor F6, light propylene acetate removal tower outlet distributor F7, crude propylene acetate tower top gas phase mixer M11, light propylene acetate removal tower outlet mixer M 12. Dehydration tower feed mixer M13; The inlet of the deacetic acid tower C5 is connected to the propylene acetate synthesis system, the outlet of the deacetic acid tower aqueous phase reflux distributor F3, the outlet of the deacetic acid tower oil phase reflux distributor F4, and the bottom outlet of the refined propylene acetate tower C7; the top outlet of the tower is connected to the inlet of the deacetic acid tower condenser E11; The inlet of the crude propylene acetate tower C6 is connected to the outlet of the deacetic acid tower oil phase reflux distributor F4, the outlet of the crude propylene acetate tower reflux distributor F5, and the bottom outlet of the light propylene acetate tower C8; the top outlet of the tower is connected to the inlet of the crude propylene acetate tower top gas phase mixer M11; the bottom outlet of the tower is connected to the inlet of the refined propylene acetate tower C7; the refined propylene acetate tower C7... The top outlet is connected to the E15 inlet of the condenser of the refined propylene acetate tower; the F6 outlet of the refined propylene acetate tower's outlet distributor is connected to the C7 inlet of the refined propylene acetate tower and the propylene acetate outlet pipeline; the C8 inlet of the light propylene acetate removal tower is connected to the F5 outlet of the reflux distributor of the crude propylene acetate tower, and the top outlet of the tower is connected to the E17 inlet of the condenser of the light propylene acetate removal tower; the F7 inlet of the light propylene acetate removal tower's outlet distributor is connected to the P5 outlet of the light propylene acetate removal tower's outlet pump, and the outlet of the outlet is connected to the C8 inlet of the light propylene acetate removal tower and the outlet pipeline; the C9 inlet of the dehydration tower is connected to the P6 outlet of the dehydration tower's feed pump, and the top outlet of the tower is connected to the M11 inlet of the crude propylene acetate tower's top gas phase mixer; the bottom outlet of the tower is connected to the wastewater treatment device.

5. The apparatus for producing high-purity propylene acetate using propylene as raw material according to claim 3, characterized in that, The operating pressure of gas-liquid separator C1 is 0.85-1.05 MPaA, the operating pressure of water washing tower C2 is 1.05-1.25 MPaA, the operating pressure of absorption tower C3 is 0.90-1.10 MPaA, the operating pressure of desorption tower C4 is 0.04-0.24 MPaA, and the operating pressure of degassing tank V5 is 0.05-0.15 MPaA; the washing acetic acid flow rate of gas-liquid separator C1 is 9500-10500 kg·h. -1 The acetic acid flow rate for washing in water washing tower C2 is 2000-3000 kg·h. -1 The water flow rate is 200-300 kg·h -1 .

6. The apparatus for producing high-purity propylene acetate using propylene as raw material according to claim 4, characterized in that, The operating pressure of the acetic acid removal tower C5 is 0.05-0.15 MPaA, the operating pressure of the crude propylene acetate tower C6 is 0.05-0.15 MPaA, the operating pressure of the refined propylene acetate tower C7 is 0.05-0.15 MPaA, the operating pressure of the light propylene acetate removal tower C8 is 0.05-0.15 MPaA, and the operating pressure of the dehydration tower C9 is 0.05-0.15 MPaA.

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