WO2020024886A1 - Anti-corrosive process and device for methyl acetate hydrolysis and acetic acid refining in polyvinyl alcohol mother liquor recovery process - Google Patents

Abstract

Disclosed are an anti-corrosive process and a device, which relate to methyl acetate hydrolysis and acetic acid refining in a polyvinyl alcohol mother liquor recovery process. The anti-corrosive device includes a methyl acetate concentration device, a methyl acetate dealdehyding device, a methyl acetate hydrolysis device, a hydrolysis liquid separation device, an acetic acid refining device and an isopropyl acetate recovery device. The process of methyl acetate hydrolysis and acetic acid refining mainly comprises methyl acetate concentration, methyl acetate dealdehyding, methyl acetate hydrolysis, hydrolysis liquid separation, acetic acid refining and isopropyl acetate recovery. A mass transfer unit (i.e. a packing section) is arranged at the upper part of the side sampling port of a hydrolysis tower to improve the ability of removing halogen-containing impurities; broken resins entrained in a hydrolysis liquid are filtered by adding a precise filter, which prevents the broken resins bearing sulfonic groups from entering into an acetic acid refining system. The corrosion problem of the acetic acid refining device is fundamentally solved, the corrosion problem of the device in the acetic acid refining process is notably solved, and the service life of a key device is prolonged by 1 to 5 times.

Description

 Anti-corrosion process and device for the hydrolysis of methyl acetate and acetic acid refining during the recovery of polyvinyl alcohol mother liquor "Preservative process and device for methyl acetate hydrolysis and acetic acid purification in the process" has the priority of the earlier application. The entirety of the prior application is incorporated herein by reference. Technical field

 The invention belongs to the field of chemical industry, and particularly relates to a recovery device and process for a mother liquor recovery unit in the production process of polyvinyl alcohol, and in particular relates to an anticorrosion process and packing of methyl acetate hydrolysis and acetic acid purification in the recovery process of the polyvinyl alcohol mother liquor. Background

 Polyvinyl alcohol (PVA for short) is a white powder in appearance. It is a water-soluble polymer with properties between plastic and rubber. It is used in the textile industry, construction and decoration industry, chemical industry, agriculture, daily cosmetics and high-frequency beacon. Agents are widely used. PVA is the only vinyl polymer that can be used as a carbon source and energy source by bacteria. It is a biodegradable polymer material that can be produced on a large scale by non-petroleum routes. It is inexpensive and has excellent oil, solvent and gas barrier properties. It has unique advantages in food and pharmaceutical packaging.

 A large amount of alcoholysis mother liquor is produced in the process of polyvinyl acetate alcoholysis to produce polyvinyl alcohol, mainly composed of methanol, methyl acetate and sodium acetate. These are important chemical raw materials that should be recovered. Methyl acetate is actually produced from the raw materials acetic acid and methanol. Approximately 1.5 tons of methyl acetate are produced for each ton of polyvinyl alcohol produced. Although methyl acetate is also a chemical raw material, it has a small demand and is generally not sold as a by-product. It is necessary to hydrolyze methyl acetate to acetic acid and methanol, and use it for vinyl acetate synthesis and polymerization after separation and purification. In the industrial production process, under the action of strongly acidic cation exchange resin, methyl acetate undergoes a hydrolysis reaction as shown below to produce acetic acid and methanol:

CH3COOCH3 + H ₂ O === CH3OH + CH3COOH

 During the acetic acid refining process, high-temperature concentrated acetic acid containing impurities is often formed, which causes severe corrosion of equipment. The industry has tried to upgrade the equipment material from 316L stainless steel to deoxidized copper or even pure metal. Although it can slightly extend the service life, it cannot completely solve the corrosion problem, which has long plagued the development of the PVA industry.

Literature reports (Mao Yongsheng, Research on the Corrosion of Acetic Acid Concentration Tower, Master's Degree Thesis, 2000; Xu Zhiqiang, Research on the Etching Mechanism of Acetic Acid Tower in PVA Workshop and Protective Measures, Petrochemical Equipment Technology, 2008, 29 (5), 46) Production of Acetic Acid Refining Tower Strict The main cause of heavy corrosion is that the column feeds dilute acetic acid and other halide-containing impurities such as gas ions. Under its operating conditions, the corresponding hydrides obtained by combining halogen ions and hydrogen ions form the highest azeotrope with water. The boiling point is between the feed plate and the temperature of the flea, causing the halide argonide to accumulate in the tower. Accumulated dentin hydride has a significant effect on accelerating the corrosion of metallic materials under high-concentration acetic acid and higher temperature environments, which can cause corrosion cracking in a short period of time, greatly shortening the equipment life cycle. Ma Yuanzheng et al. (Ma Yuanzheng, Research on the Corrosion of Acetic Acid Concentration Tower in the Production of Polyvinyl Alcohol, Master's Degree Thesis, 2005) It is proposed to set a sideline extraction port in the gas ion accumulation zone in the acetic acid purification tower to extract gaseous acetic acid from the tower. , Thereby slowing the anti-corrosion strategy of gas ion accumulation. Although this method can alleviate the corrosion problem to a certain extent, a large amount of gas-containing waste acetic acid cannot be processed, and the problem has not been effectively solved.

 At present, although the material of the acetic acid refining equipment of some production facilities in the polyvinyl alcohol industry has been upgraded to titanium with strong corrosion resistance, the problem of acetic acid corrosion has not yet been solved. The development of a new process with enhanced anti-corrosion capabilities and the elimination of impurities that enhance the corrosiveness of acetic acid from the source are of great significance to the long-term safe production of polyvinyl alcohol plants, and have promotional value for similar types of plants in other industries. Summary of the invention

 The purpose of the present invention is to provide an anticorrosion device and process for the hydrolysis of methyl acetate and acetic acid purification during the recovery of PVA alcoholysis mother liquor. By reasonably setting the separation device and the process flow, the corrosive impurities that enhance vinegar can be eliminated from the source. Prevent corrosion of acetic acid refining equipment.

 The anticorrosion device for methyl acetate hydrolysis and acetic acid purification provided by the present invention includes a methyl acetate concentration device, an ethyl acetate dealdehyde dehydration device, an ethyl acetate hydrolysis device, a hydrolysate separation device, an acetic acid purification device, and an isopropyl acetate recovery device. The methyl acetate concentration device includes an extraction distillation column, the methyl acetate delighting device includes a deacetylation column, the methyl acetate hydrolysis device includes a hydrolysis column, and the hydrolysate separation device includes a hydrolysate separation A tower, wherein the acetic acid refining device includes an acetic acid refining tower, and the isopropyl acetate recovery container includes an isopropyl acetate recovery tower;

 The extractive distillation column, the deeezification column, the hydrolysis column, the hydrolysate separation column, the acetic acid refining column and the isopropyl acetate recovery column are connected in series according to the material flow direction. Preferably, the top of the extractive distillation column and the deethylation column The middle of the tower is connected, the tower kettle of the deacetylation tower is connected to the top of the hydrolysis tower, the tower flea of the hydrolysis tower is connected to the middle of the hydrolysis liquid separation tower, and the tower kettle of the hydrolysis liquid separation tower is purified with acetic acid The middle of the tower is connected, and the top of the acetic acid purification tower is connected to the top of the isopropyl acetate recovery tower.

 According to the device of the present invention, the methyl acetate concentration device further includes an extractive distillation column condenser, an extractive distillation column reflux tank, an extractive distillation column reflux pump, and an extractive distillation column reboiler;

The top of the extractive distillation column and the condenser of the extractive column tower, the reflux tank of the extractive column, and the reflux pump of the extractive column The secondary pump is connected to the exit of the reflux pump of the extractive distillation column and the top of the extractive distillation column, and a branch line connected to the deacetaldehyde column is provided on the connecting pipe;

 The extraction flea tower of the extraction hall tower is provided with an extraction tower reboiler;

 The flea of the extraction refinery tower is also connected to a methanol refining system;

 The methyl betrate concentration device further includes an extraction water inlet and a methyl acetate inlet. Preferably, the extraction water inlet is connected to the top of the extraction distillation column, and the methyl acetate inlet is in the middle of the extraction distillation column. connection.

 According to the device of the present invention, the methyl acetate dealdehyde unit further includes a deacetaldehyde tower condenser, a deacetaldehyde tower reflux tank, a deacetylation tower reflux pump, a deacetylation tower reboiler, and a deacetylation tower kettle. Pump;

 The top of the deacetaldehyde column is sequentially connected with the deacetaldehyde column condenser, the deacetaldehyde column reflux tank, and the deacetaldehyde column reflux pump; the outlet of the deacetaldehyde column reflux pump is connected with the top of the deacetaldehyde column, And a branch line connected to the acetaldehyde refining system is provided on the connecting pipeline; the tower flea of the deacetaldehyde tower is provided with a deacetaldehyde tower reboiler;

 The deacetaldehyde tower flea is connected with the deacetaldehyde tower flea pump and the top of the hydrolysis tower sequentially.

 According to the device of the present invention, the methyl acid hydrolyzate device further includes a strongly acidic cation exchange resin bed, a hydrolysis tower condenser, a hydrolysis tower reflux tank, a hydrolysis tower reflux pump, a hydrolysis tower side pump, a hydrolysis tower reboiler, and hydrolysis. Outlet pump of the kettle and precision filter; the top of the hydrolysis tower is sequentially connected with the condenser of the hydrolysis tower, the reflux tank of the hydrolysis tower, and the reflux pump of the hydrolysis tower; the outlet of the reflux pump of the hydrolysis tower is connected with the top of the hydrolysis tower; the hydrolysis The column condenser is also connected to the middle of the deacetaldehyde column;

 The upper side line mining outlet of the hydrolysis tower is sequentially connected to the hydrolysis tower side mining pump, the strongly acidic cation exchange resin bed, and the precision filter, and the outlet of the precision filter is connected to the middle of the hydrolysis tower;

 Preferably, a packing section is provided in the hydrolysis tower, and the packing section is located above the upper side line mining outlet;

 Preferably, the packing section is equivalent to 5 to 10 theoretical plates;

 Wherein, at least one precision filter is provided, and the arrangement of the precision filters may be parallel or series; for example, a precision filter A and a precision filter B are arranged in parallel, and the precision filter A and the precision filter B are connected Several valves are installed on the pipeline;

 A tower water flea is provided with a hydrolysis tower reboiler;

 The water flea of the hydrolysis tower is connected with the water flea pump and the middle part of the hydrolysis liquid separation tower in sequence.

 Further, the methyl acetate hydrolysis device further includes a methyl acetate hydrolysis water inlet, which is arranged on a connecting pipeline between the deeezizer tower kettle and the top of the hydrolysis tower.

 According to the device of the present invention, the hydrolysate separation device further comprises a hydrolysate separation tower condenser, a hydrolysate separation tower reflux tank, a hydrolysate separation tower reflux pump, a hydrolysate separation tower reboiler, and a hydrolysate separation tower kettle pump;

The top of the hydrolysate separation tower is provided with two branches, branch one is connected to the middle of the extraction distillation column, and branch two is used for hydrolysis. The condenser of the liquid separation tower, the reflux tank of the hydrolysis liquid separation tower, and the reflux pump of the hydrolysis liquid separation tower are connected in sequence; the outlet of the reflux pump of the hydrolysis liquid separation tower is connected to the top of the hydrolysis liquid separation tower;

 The flea of the hydrolysate separation tower is provided with a hydrolysate separation tower reboiler;

 The tower kettle of the hydrolysate separation tower is sequentially connected with the pump of the hydrolysate separation tower and the middle of the acetic acid purification tower.

 According to the device of the present invention, the acid refining tower further includes a condenser of an acetic acid refining tower, a phase separator of the acetic acid refining tower, a reflux pump for the acetic acid refining tower, a reboiler for the acetic acid refining tower, a side pump for the acetic acid refining tower, and an acetic acid refining tower. Kettle out pump

 The top of the acid refining tower is sequentially connected with the condenser of the acetic acid refining tower and the phase separator of the acetic acid refining tower. The phase separator of the acetic acid refining tower is provided with an outlet one and an outlet two, and the outlet one and the acetic acid refining tower reflux pump. The top of the acetic acid refining tower is connected in sequence; the second outlet is connected to the isopropyl acetate recovery device;

 The lower side line outlet of the acetic acid refining tower is connected to an example acetic acid refining tower mining pump to produce acetic acid;

 The flea of the acetic acid refining tower is provided with a reboiler of the acetic acid refining tower;

 The flea in the acetic acid refining tower is connected with the acetic acid refining tower kettle pump to discharge the residue and tar.

 According to the device of the present invention, the isopropyl acetate recovery device further includes an isopropyl acetate recovery tower condenser, an isopropyl acetate recovery tower phase separator, an isopropyl acetate recovery tower distillation pump, and an isopropyl acetate water. Phase receiving tank, isopropyl acetate recovery tower feed pump, isopropyl acetate recovery tower reboiler, isopropyl acetate recovery tower kettle exit pump;

 The phase separator of the acetic acid refining tower is provided with an oil phase outlet and a water phase outlet;

 The outlet two of the phase separator of the acid refining tower is connected with the isopropyl acetate aqueous phase receiving tank, the isopropyl acetate recovery tower feed pump, and the top of the isopropyl acetate recovery tower in sequence;

 The top of the isopropyl acetate recovery tower is sequentially connected with the condenser of the isopropyl acetate recovery tower and the phase separator of the isopropyl acetate recovery tower; the oil phase outlet of the phase separator of the acetic acid purification tower and the isopropyl acetate The propyl recovery tower distillation pump and the acetic acid refining tower phase separator are connected sequentially; the water phase outlet of the acetic acid refining tower phase separator is connected to the isopropyl acetate water phase receiving tank;

 The flea of the isopropyl acetate recovery tower is provided with a reboiler of the isopropyl acetate recovery tower;

 The tower kettle of the isopropyl acetate recovery tower is connected to the flea pump of the isopropyl acetate recovery tower, and the water is sent out of the kettle. The present invention also provides the above-mentioned anticorrosion process of methyl acetate hydrolysis and acetic acid refining. The anticorrosion process is based on the above-mentioned anticorrosion device, and the process mainly includes methyl acetate concentration, methyl acetate dealdehyde, methyl acetate hydrolysis, hydrolysis solution separation, and Acetic acid purification and isopropyl acetate recovery.

 According to the process of the present invention, the methyl acetate concentration process unit includes the following operations:

 (1) Crude methyl acetate enters the extraction refinery tower for separation of ethyl acetate and methanol;

(2) Add extraction water to the top of the extraction tower, and the methyl acetate vapor volatilized from the top of the extraction tower is condensed, After collecting and pressurizing, a part of the methyl acetate was refluxed from the top of the extraction refinery tower, and the rest was sent to the deacetylation tower for feeding;

(3) extract the methanol aqueous solution produced by the distillation flea tower flea and send it to the methanol refining system for recovery;

 Preferably, the source of the above crude methyl acetate includes crude methyl acetate (concentration 60-75%, such as 75%) from a crude methyl acetate unit and a methyl acetate hydrolysis section to separate the gas phase at the top of the column from the hydrolysate. Distilled crude methyl acetate;

 Preferably, the temperature of the extraction water is 2 15X :, such as 4 ~ 10t :, for example, the temperature is 10 ° C;

 Wherein, the operating parameters of the extractive distillation column are: pressure 0.085 ~ 0.15Mpa, such as 0.1MPa; the temperature at the top of the column is 50-60 ° C, such as 551; the temperature of the tower flea is 75-85X :, such as 821C; tower Top reflux flow / Tower top output flow = 1.3 ~ 1.7, such as 1.4 ~ 1.6.

 Wherein, the above-mentioned process unit uses a method of extractive distillation with water to remove methanol from the alcoholysis solution, which destroys the azeotropic effect of methyl acetate and methanol and reduces the inhibitory effect of methanol on the subsequent hydrolysis of methyl acetate.

 According to the process of the present invention, the methyl acetate dehydration process unit includes the following operations:

 (1) Methyl acetate enters the deacetaldehyde column for gas-liquid mass transfer;

 (2) After condensing, collecting, and increasing the pressure of the steam distilled from the top of the deeizez tower, a part of the deeziz flows back from the top of the deeze tower, and the rest is sent for purification;

 (3) The methyl acetate in the tower kettle is fed to the top of the hydrolysis tower after being pressurized;

 Preferably, the methyl acetate in step (1) includes a methyl acetate stream distilled from the top of the extraction tower and a gas-phase impurity stream from the hydrolysis column;

Wherein, the operating parameters of the deacetaldehyde tower are: pressure 0.085 ~ 0.15MPa, such as 0.1MPa; the temperature at the top of the tower is 45-55 ° C, such as 50t : _{; the} temperature of the tower flea is 50 ~ 60 ^* C, such as 55C ; Return flow / feed flow = 1.2 ~ 1.7, such as 1.3 ~ 1.6.

 The methyl acetate dehydration process unit is used to remove gas ions, fluoride ions, bromide ions, iodine ions, and ethylene impurities brought in by the extraction water from the system.

 According to the process of the present invention, the methyl acetate hydrolysis process unit includes the following operations:

 (1) Acetic acid from the deacetylation tower flea enters the hydrolysis tower, and the steam distilled from the top of the hydrolysis tower is condensed, collected, and pressurized, and then refluxed from the top of the hydrolysis tower. Uncondensed gas is used as a gas-phase impurity stream. Feed into deacetaldehyde tower feed;

 (2) The methyl acetate is extracted from the upper side line of the hydrolysis tower, mixed with methyl acetate hydrolyzed water after being pressurized, and sent to a strongly acidic cation exchange resin bed for hydrolysis reaction to generate acetic acid and methanol. The hydrolyzed solution is filtered to remove entrainment. After crushing the resin, return to the middle and lower part of the hydrolysis tower for separation;

 Preferably, the ethyl acetate extracted from the upper side line of the above-mentioned hydrolysis tower is treated by the packing section in the tower;

 Wherein, the operation parameters of the hydrolysis tower are: pressure 0.085 ~ 0.15MPa, such as O.IMPa; the temperature at the top of the tower is 55-65

V, for example, _60t:; bottoms temperature of 80 85C, e.g. _83t:; side draw back to the source temperature Flow rate / feed rate = 3.3 ~ 4.2, such as 3.5 ~ 4.0.

 Preferably, the above-mentioned filtration uses a precision filter, and the precision filter uses a needle punched blanket as a filtering medium, which can effectively filter the broken resin and prevent the broken resin from entering the acetic acid concentration system;

Wherein, the operating parameters of the strongly acidic cation exchange resin bed are: the feed temperature is 65 ~ 75 ^* C, for example, 70t :. Wherein, the operating conditions of the precision filter are: the pressure drop is less than O.IMPa, such as 0.01 ~ 0.09 MPa;

 The thickness of the filter medium is 20 ~ 30mm, and the pore size of the filter medium is less than lpm, such as 0.2 ~ 0.9um.

 (3) After the pressure of the hydrolysis solution of the hydrolytic tower flea is increased, it is sent to the hydrolysate separation tower for separation;

 Preferably, the hydrolysate is mainly composed of acetic acid, methanol, water and methyl acetate;

 Among them, the methyl acetate hydrolysis process unit described above, the methyl acetate stream that undergoes the hydrolysis reaction in the strongly acidic cation exchange resin bed is extracted from the upper side line of the hydrolysis tower, and the mass transfer unit pair between the side line extraction outlet and the top of the tower is used. The halogen impurities and acetaldehyde in the system are concentrated, and they are extracted in the gas phase to the methyl acetate de-brewing unit. The theoretical number of plates between the side extraction port and the top of the tower is 5-10.

 The precision filter uses a needle felt as a filter medium, and uses a liquid precise clarification filtration method to filter the hydrolysis reaction solution. The precision clarification and filtration filter medium has the characteristics of small capillary pore size, large porosity, and a thick layer of the filter medium. , Intercept solid particles in the internal pores of the filter medium layer.

 According to the process of the present invention, the hydrolysate separation process unit includes the following operations:

 (1) The hydrolysate flowing out from the reactor of the hydrolysis tower enters the hydrolysate separation tower for separation, and part of the vapor at the top of the column is blown into the extractive distillation column. ;

 (2) The dilute acetic acid of the hydrolysate separation tower Talea is sent to the acetic acid refining tower after being pressurized for dehydration purification.

Wherein, the operating parameters of the hydrolysate separation tower are: pressure 0.085 ~ 0.15MPa, for example O.IMPa; tower top temperature is 60 ~ 70 ^* C, for example 65 ° C _; tower kettle temperature is 110 ~ 115X :, for example 113t ：, Make-up flow / feed flow = 0.55 ~ 1.1, such as 0.6-1.0.

 According to the process of the present invention, the acetic acid refining process unit includes the following operations:

 (1) Dilute the acetic acid from Tata fleas from the hydrolysate to enter the acetic acid refining tower. The azeotrope of water and isopropyl acetate is distilled from the top of the tower. After condensation and phase separation, the upper layer of isopropyl acetate and the lower layer are obtained. Separation water (containing a small amount of isopropyl acetate); preferably, isopropyl acetate is used as an azeotrope in the acetic acid purification tower;

 (2) The isopropyl acetate phase in the upper layer is sent to the top of the acetic acid refining tower for reflux after being pressurized, and the separated water (containing a small amount of isopropyl acetate) in the lower layer is collected and sent to the isopropyl acetate recovery tower;

 (3) Acetic acid is extracted from the lower stern line of the acetic acid refining tower, and the residues and tar of tower flea are sent out of the system.

Wherein, the operating parameters of the acetic acid refining tower are: pressure 0.085 ~ 0.15MPa, for example, O.IMPa; the temperature at the top of the tower is 70-801 :, for example, 75 ° C; Talea temperature is 120125X :, for example, 124t : _; lower side line extraction temperature is 120125 ° C, for example, 123.8 "C _; reflux flow / feed flow = 3.74.2, such as 3.84.1

 According to the process of the present invention, the isopropyl acetate recovery process unit includes the following operations:

 (1) The separated water from the acetic acid refining process unit enters the top of the isopropyl acetate recovery tower, and the gas at the top of the tower is condensed and separated to obtain the water phase and the oil phase. The water phase is collected, and the water phase is returned to the isopropyl acetate recovery. At the top of the tower, the oil phase is returned to the acetic acid refining unit after being pressurized;

 (2) The flea drainage of the isopropyl acetate recovery tower is sent out to the system after being pressurized;

 Preferably, the isopropyl acetate recovery tower only includes a lifting section;

Wherein, the operating parameters of the isopropyl acetate recovery tower are: pressure 0.085 ~ 0.15MPa, for example, O.IMPa; tower top temperature is 90 ~ 100 ^* C, for example 96 ^* C _; tower temperature is 95 ~ 103X :, For example _100t:;

 Wherein, the operating temperature of the phase separation is 35 ~ 45C.

 The inventors of the present application have systematically studied the movement and distribution of halogen ions in the PVA alcoholysis mother liquor recovery system, and explored the accumulation mechanism of trace halogens in the system. Based on the above research, a method for removing trace halogen impurities from the system was developed, and a new separation process was constructed to achieve the removal of halogen impurities with lower energy and material consumption.

 The inventor of the present application unexpectedly discovered through systematic research on a methyl acetate hydrolysis and acetic acid refining device that broken strong acidic ion exchange resin particles and powders also existed in the acetic acid refining tower flea. Further analysis found that the broken resin was brought along with the hydrolysate after the methyl acetate hydrolysis catalyst was broken. This type of resin is a high molecular polymer with sulfonic acid group with a network-like three-dimensional structure. During use, it will be caused by mechanical external forces, repeated transformations, degradation of polymer molecules, and regeneration, backwash extrusion, etc. When the polymer chain constituting the resin is broken, the strength of the resin is easily weakened and broken. The crushed resin powder will enter the hydrolysis solution separation tower and the acetic acid purification tower together with the hydrolysis reaction solution, and the organic acid molecules will be decomposed at a higher temperature, which will cooperate with acetic acid to form a strong corrosion source of the equipment. This finding has not been reported in existing published literature. Further research found that the particle size of the crushed resin was extremely small and the medium was corrosive, making it difficult to remove it from the system. Based on this finding, the present application adds a precision filter at the exit of the cation exchange resin bed of the hydrolysis reactor to filter the crushed resin entrained by the hydrolysis solution, preventing the crushed resin with sulfonic acid group from entering the acetic acid refining system, avoiding the resin caused by the crushed resin. Equipment corrosion, effectively avoiding a source of corrosion. The beneficial effects of the present invention:

Based on the movement and distribution of gas ions, fluoride ions, bromide ions, read ions, and broken resins found in the inventors in the hydrolysis and purification system of methyl acetate, an efficient removal measure is established to effectively control high temperature concentrated acetic acid. Content of impurities. Specifically, in one aspect, the present invention enhances the removal capability of halogen-containing impurities by providing a mass transfer unit (ie, a filler section) at the upper part of the side of the hydrolysis tower, thereby removing gas ions, fluorine ions, The content of argonide formed by bromide ion, ion exchange and hydrogen is controlled below 10 ppm, which avoids the occurrence of local high concentration areas due to the formation of the highest azeotrope in the osmic acid refining tower; the original technology produced methyl acetate from the top of the hydrolysis tower The halide impurities enter the cation exchange resin bed of the hydrolysis reactor together with the reaction stream, and enter the acetic acid refining tower with the generated acetic acid, which accumulates continuously.

 On the other hand, in the present invention, a precision filter is added at the exit of the cation exchange resin bed of the hydrolysis reactor to filter the crushed resin entrained by the hydrolysis solution, preventing the crushed resin with sulfonic acid group from entering the acetic acid refining system.

 Through the above two measures, under the condition of low energy consumption, the effective removal of corrosive impurities of high-concentration acetic acid can be realized, and the problem of corrosion of acetic acid refining equipment can be fundamentally solved, thereby significantly solving the problem of corrosion of acetic acid refining equipment and extending the life of key equipment ~5 times. BRIEF DESCRIPTION OF THE DRAWINGS

 FIG. 1 is a schematic structural diagram of a device for methyl acetate hydrolysis and acetic acid purification described in Example 1 of the present invention; reference numerals: 01-extractive distillation column, 02-deacetaldehyde column, 03-hydrolysis column, 04-strong Acidic cation exchange resin bed, 05A- precision filter A, 05B- precision filter B, 06-hydrolysate separation tower, 07-gallic acid purification tower, 08-isopropyl acetate recovery tower, 09-extractive distillation column condensation Device, 10-extraction distillation column reflux tank, 11-extraction distillation column reflux pump, 12-extraction distillation column reboiler, 13-deacetaldehyde column condenser, 14-deacetaldehyde column reflux tank, 15- Deacetaldehyde column reflux pump, 16-deacetaldehyde column reboiler, 17-deacetaldehyde column boiler exit pump, 18-hydrolysis column condenser, 19-hydrolysis column reflux tank, 20-hydrolysis column reflux pump, 21- Hydrolysis tower side pump, 22-Hydrolysis tower reboiler, 23-Hydrolysis tower flea out pump, 24-Hydrolysate separation tower condenser, 25-Hydrolysate separation tower reflux tank, 26-Hydrolysate separation tower reflux pump, 27 -Hydrolysate separation tower reboiler, 28-Hydrolysate separation tower flea pump, 29-Acetic acid purification tower condenser, 30-acetic acid purification Phase separator, 31-acetic acid refining tower reflux pump, 32-acetic acid refining tower reboiler, 33-acetic acid refining tower example pump, 34-acetic acid refining tower flea pump, 35-isopropyl acetate recovery tower condenser, 36-Isopropyl acetate recovery tower phase separator, 37-Isopropyl acetate recovery tower outlet pump, 38-Isopropyl acetate water phase receiving tank, 39-Isopropyl acetate recovery tower feed pump, 40-Acetic acid Isopropyl ester recovery tower reboiler, 41-isopropyl acetate recovery tower flea pump. detailed description

The device structure and process of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explained the present invention, and should not be construed as limiting the protection scope of the present invention. Any technology implemented based on the foregoing content of the present invention is covered by the scope of the present invention. Unless otherwise stated, the raw materials and reagents used in the following examples are all commercially available products, or can be prepared by known methods.

 Example 1

 The anti-corrosion device with anti-corrosion function for methyl acetate hydrolysis and acetic acid purification as shown in FIG. 1 includes a methyl acetate concentration device, a methyl acetate dehydration device, a methyl acetate hydrolysis device, a hydrolysate separation device, an acetic acid purification device and Isopropyl acetate recovery unit;

 The methyl acetate concentration device includes the extraction refinement tower 01, the methyl acetate dehydration device includes the deacetylation tower 02, the ethyl acetate hydrolysis device includes the hydrolysis tower 03, the hydrolysate separation device includes the hydrolysate separation tower 06, and the acetic acid purification device includes Acetic acid purification tower 07, isopropyl acetate recovery unit includes isopropyl acetate recovery tower 08;

 Among them, the extraction refinement tower 01, the deacetylation tower 02, the hydrolysis tower 03, the hydrolysate separation tower 06, the acetic acid purification tower 07, and the isopropyl acetate recovery tower 08 are connected in series according to the material flow direction; the top of the extraction distillation tower 01 and the The middle of the deacetylation tower 02 is connected, the tower flea of the deacetaldehyde tower 02 is connected to the top of the hydrolysis tower 03, the tower flea of the hydrolysis tower 03 is connected to the middle of the hydrolysate separation tower 06, and the tower kettle of the hydrolysate separation tower 06 It is connected to the middle of the acetic acid purification tower 07, and the top of the acetic acid purification tower 07 is connected to the top of the isopropyl acetate recovery tower 08.

 Among them, the methyl acetate concentration device includes an extractive distillation tower 01, an extractive refinement tower condenser 09, an extractive refinement tower reflux tank 10, an extractive distillation tower reflux pump 11, an extractive refinery tower reboiler 12;

 The top of the extractive distillation column 01 is connected sequentially with the extractive distillation column condenser 09, the extractive distillation column reflux tank 10, and the extractive distillation column reflux pump 11; the outlet of the extractive distillation column reflux pump 11 and the extractive distillation column 01 is connected at the top, and a branch line connected to the deacetaldehyde column 02 is provided on the connecting pipe; the distillation kettle of the extraction distillation tower 01 is provided with an extraction distillation tower reboiler 12 as a heat source; Connect with methanol refining system;

 The methyl acetate concentration device further includes an extraction water inlet and an ethyl acetate inlet. The extraction water inlet is connected to the top of the extractive distillation column 01, and the methyl acetate inlet is connected to the middle of the extractive distillation column 01.

 The methyl acetate dealdehyde unit includes a deacetaldehyde tower 02, a deacetaldehyde tower condenser 13, a deacetaldehyde tower reflux tank 14, a deacetylation tower reflux pump 15, a deacetylation tower reboiler 16, and a deacetylation tower. The zita flea pump 17; the top of the deacetylation tower 02 is connected with the deacetaldehyde tower condenser 13, the deacetylation tower reflux tank 14, and the deacetylation tower return pump 15 in sequence; the exit of the deacetylation tower return pump 15 It is connected to the top of the deacetaldehyde tower 02, and a branch line connected to the acetaldehyde refining system is provided on the connecting pipeline;

 The tower flea of the debutter tower 02 is provided with a debaz tower reboiler 16, as a heat source;

The tower flea of the deacetylation tower 02 is connected to the top of the deacetylation tower kettle pump 17, and the top of the hydrolysis tower 03 in sequence. Among them, the methyl acetate hydrolysis unit includes a hydrolysis tower 03, a strongly acidic cation exchange resin bed 04, a hydrolysis tower condenser 18, a hydrolysis tower reflux tank 19, a hydrolysis tower reflux pump 20, a hydrolysis tower side pump 21, and a hydrolysis tower reboiler. 22. Hydrolysis tower kettle pump 23 and precision filter;

 The top of the hydrolysis tower 03 is connected with the condenser of the hydrolysis tower 18, the reflux tank of the hydrolysis tower 19, the reflux pump 20 of the hydrolysis tower is connected in sequence, and the outlet of the reflux pump 20 of the hydrolysis tower is connected with the top of the hydrolysis tower 03;

 The upper side line mining outlet of the hydrolysis column 03 is connected to the side tower mining pump 21. The strongly acidic cation exchange resin bed 04. The precision filter is connected in sequence, and the outlet of the precision filter is connected to the middle of the hydrolysis tower 03;

 A packing section is set in the hydrolysis tower 03, and the packing section is located above the upper side line mining outlet, and the packing section is equivalent to 5 to 10 theoretical plates;

 The precision filters include precision filters 05A and 05B in parallel, precision valves 05A and 05B. Several valves are installed on the connecting pipeline; normally, one is used and the other is reserved.

 The tower flea of the hydrolysis tower 03 is provided with a hydrolysis tower reboiler 22 as a heat source;

 The tower kettle of the hydrolysis tower 03 is connected to the hydrolysis tower flea pump 23. The middle part of the hydrolysis liquid separation tower 06 is connected in sequence;

 The methyl acetate hydrolysis device further includes a methyl acetate hydrolysis water inlet, which is arranged on a connecting pipe at the top of the deacetylation tower 02 flea and the hydrolysis tower 03.

 The hydrolysate separation device includes a hydrolysate separation tower 06, a hydrolysate separation tower condenser 24, a hydrolysate separation tower reflux tank 25, a hydrolysate separation tower reflux pump 26, a hydrolysate separation tower reboiler 27, and a hydrolysate separation tower. Kettle out pump 28;

 The top of the hydrolysate separation tower 06 is provided with two branches. The first branch is connected to the middle of the extractive distillation column 01. The second branch is connected to the condenser 24 for the hydrolysate separation tower, the reflux tank 25 for the hydrolysate separation tower, and the hydrolysate separation. The column reflux pump 26 is sequentially connected; the outlet of the hydrolysis liquid separation column reflux pump 26 is connected to the top of the hydrolysis liquid separation column 26;

 The tower kettle of the hydrolysate separation tower 06 is provided with a hydrolysate separation tower reboiler 27 as a heat source;

 The tower kettle of the hydrolysate separation tower 06 and the hydrolysate separation tower flea pump 28. The middle part of the acetic acid purification tower 07 is sequentially connected.

 Among them, the acetic acid refining device includes acetic acid refining tower 07, acetic acid refining tower condenser 29, acetic acid refining tower phase separator 30, acetic acid refining tower reflux pump 31, acetic acid refining tower reboiler 32, acetic acid refining tower side pump 33, acetic acid Refining tower autopump 34; The top of acetic acid refining tower 07 is connected with condenser 29 and acetic acid refining tower phase separator 30 in sequence. The acetic acid refining tower phase separator 30 has outlet one and outlet two, and outlet one. Connect with the reflux pump 31 of acetic acid purification tower and the top of acetic acid purification tower 07 in sequence;

 The lower side line of the acetic acid purification tower 07 is connected to the side mining pump 33 of the acetic acid purification tower to produce acetic acid;

 The flea of the acetic acid refining tower 07 is provided with the acetic acid refining tower reboiler 32 as a heat source;

The flea in the acetic acid purification tower 07 is connected to the acetic acid purification tower kettle outlet pump 34 to discharge residues and tar. Isopropyl acetate recovery device includes isopropyl acetate recovery tower 08, isopropyl acetate recovery tower condenser 35, isopropyl acetate recovery tower phase separator 36, isopropyl acetate recovery tower pump 37, isopropyl acetate Ester water phase receiving tank 38, isopropyl acetate recovery tower feed pump 39, isopropyl acetate recovery tower reboiler 40, isopropyl acetate recovery tower flea pump 41;

 Isopropyl acetate recovery tower phase separator 36 is provided with oil phase outlet and water phase outlet;

 The outlet 2 of the acetic acid purification tower phase separator 30 is connected with the isopropyl acetate aqueous phase receiving tank 38, the isopropyl acetate recovery tower feed pump 39, and the isopropyl acetate recovery tower 08 are connected in series;

 The top of the isopropyl acetate recovery tower 08 is sequentially connected to the isopropyl acetate recovery tower condenser 35 and the isopropyl acetate recovery tower phase separator 36; the oil phase outlet of the isopropyl acetate recovery tower phase separator 36, The isopropyl acetate recovery tower distillation pump 37 and the acetic acid purification tower phase separator 30 are connected in sequence; the water phase outlet of the isopropyl acetate recovery tower phase separator 36 is connected to the isopropyl acetate water phase receiving tank 38;

 The flea of the isopropyl acetate recovery tower 08 is connected to the isopropyl acetate recovery tower kettle output pump 41, and the flea is discharged.

 The following is a detailed description of the process of hydrolysis of methyl acetate and the preservation of acetic acid in combination with Figure 1: Methyl acetate concentration process unit: 75% crude methyl acetate and hydrolysate separation tower 06 top gas phase from the previous section The distilled crude methyl acetate enters the extraction refinery column 01 for separation of methyl acetate and methanol. Cool to 10t: The extraction water is added from the top of the extractive distillation column 01 to destroy the azeotropic effect of methyl acetate and methanol and increase the relative volatility of methyl acetate and methanol. The steam at the top of the extractive distillation tower column 01 is condensed by the extractive distillation column condenser 09 and enters the extractive distillation column reflux tank 10, part of which is boosted by the extractive distillation column reflux pump 11 and returned to the extractive distillation column 01 for reflux, and the rest is sent to The deacetaldehyde column 02 is fed. The flea heat source is provided by the extraction refining tower 12 reboiler. The flea is a methanol aqueous solution and sent to a methanol refining system for refining and recovery.

 Methyl acetate dehydration process unit: Extracts the methyl acetate stream distilled from the top of refinery column 01 and the gas-phase impurity stream from hydrolysis column 03, and enters deacetylation column 02 for vapor-liquid mass transfer. After the deacetating tower condenser 13 condenses, it enters the deacetaldehyde tower reflux tank 14 and is boosted by the deacetaldehyde tower reflux pump 15 for a part of the reflux and the rest is sent to the acetaldehyde refining system for processing, so that gas ions, fluoride ions, Bromine ions, iodide ions, halogen impurities, and acetaldehyde impurities are removed from the system. The tower flea heat source of the deeze tower 02 is provided by the deeze tower reboiler 16, and the tower kettle is pumped by the liquid dee tower tower pump 17. Feed at the top of column 03.

Methyl acetate hydrolysis process unit: After the steam at the top of the hydrolysis tower 03 is partially condensed by the condenser 18 of the hydrolysis tower, the condensate completely enters the reflux tank 19 of the hydrolysis tower, and is returned to the hydrolysis tower 03 through the reflux pump 20 of the hydrolysis tower. The waste stream is fed to Deezita 02 to remove the acetaldehyde in the catalytic hydrolysis system and the gas ions, fluoride ions, bromide ions, and detoxification impurities brought by the extracted water. The material extracted from the upper side line of the hydrolysis tower 03 is pressurized by the side tower pump 21 and mixed with the hydrolyzed water of ethyl acetate, and then sent to the strongly acidic cation exchange resin bed 04 for hydrolysis reaction. A key technical measure equivalent to 8 theoretical plate high-efficiency packing sections is arranged above the side line mining outlet to realize effective removal of tooth impurities and aldehydes. Strongly acidic cations In the exchange resin bed 04, methyl gallate and water are partially hydrolyzed to form acetic acid and methanol under the catalysis of a cation exchange resin. The hydrolysate is filtered through a precision filter and returned to the middle and lower part of the hydrolysis tower 03 for separation. The precision filter uses a needle-punched blanket as a filter medium to effectively filter the crushed resin, thereby preventing the crushed resin from entering the acetic acid concentration system. The main composition of the hydrolysis reaction liquid in the 03-pot autoclave of the hydrolysis tower is acetic acid, methanol, water, and methyl acetate, which are sent to the hydrolysate separation tower 06 via the hydrolyzer-out pump 23 to be separated. The heat source of the hydrolysis column 03 column kettle is provided by the hydrolysis column reboiler 22.

 Hydrolysate separation process unit: The hydrolysate from the 03 column kettle of the hydrolysis tower is sent to the hydrolysate separation tower 06 via the hydrolysis tower kettle pump 23 to be separated. The vapor at the top of the tower is blown into the extraction refinery tower 01, and the rest is separated by the hydrolysate. The tower condenser 24 condenses and enters the hydrolysate separation tower reflux tank 25, and returns to the tower reflux through the hydrolysate separation tower reflux pump 26; the hydrolysate separation tower 06 tower flea dilute acetic acid is sent to the acetic acid purification tower via the hydrolysate separation tower flea pump 28 07 for dehydration purification. Hydrolysate separation tower 06 column kettle The heat source is provided by a re-boiler 27 of the hydrolysate separation tower.

 Acetic acid refining process unit: Acetic acid refining tower 07 uses isopropyl acetate as an azeotrope, and uses the azeotropic action of isopropyl acetate and water to distill the azeotrope of water and isopropyl acetate from the top of the tower. The gas phase mixture at the top of the column is condensed and cooled in the acetic acid purification tower condenser 29 and enters the acetic acid purification tower phase separator 30 for phase separation. The upper isopropyl acetate phase is sent to the top of the acetic acid refining tower 07 through the acetic acid refining tower reflux pump 31 for reflux; the separated water (containing a small amount of isopropyl acetate) in the lower part of the acetic acid refining tower phase separator 30 is accepted in the isopropyl acetate aqueous phase After the collection in the tank 38, the isopropyl acetate recovery tower 08 was fed and the isopropyl acetate therein was recovered. The acetic acid refining tower 07 extracts the finished acetic acid from the lower stern line through the side extraction pump 33 of the acetic acid refining tower, and the tower flea liquid is the residue and the tar is sent out from the system by the acetic acid refining tower kettle pump 34. The flea heat source of the acetic acid purification tower 07 is provided by the acetic acid purification tower reboiler 32.

 Isopropyl acetate recovery process unit: The separated water from the acetic acid purification tower phase separator 30 is sent to the isopropyl acetate recovery tower 08 through the isopropyl acetate water phase receiving tank 38 and the isopropyl acetate recovery tower feed pump 39 The top feed is used to recover the isopropyl acetate dissolved in the separation water. The tower only has a lift section. After the top gas is condensed by the isopropyl acetate recovery tower condenser 35, the condensate enters the isopropyl acetate recovery tower phase separator. 36 phases, the water phase sends isopropyl gallate to the water phase receiving tank 38, and the oil phase is sent from the isopropyl acetate recovery tower pump 37 to the acetic acid purification tower phase separator 30 for the oil phase side feed. The heat source of the boiler in the isopropyl acetate recovery tower 08 is provided by the isopropyl acetate recovery tower reboiler 40, and the flea drainage is sent out of the system by the isopropyl acetate recovery tower flea output pump 41. Example 2

 Preservative process of methyl acetate hydrolysis and acetic acid refining. The process mainly includes continuous operation of methyl acetate concentration, methyl acetate dealdehyde, hydrolysis of ethyl acetate, separation of hydrolysate, purification of acetic acid and recovery of isopropyl acetate.

 The methyl acetate concentration process unit includes the following operations:

(1) 75% crude methyl acetate and methyl acetate from the methyl acetate crude sub-unit hydrolysing section, the crude methyl acetate distilled from the gas phase of the top of the hydrolysate separation tower enters the extraction refinery tower, and methyl acetate and Separation of methanol; (2) Add 1 ° C of extraction water to the top of the extraction refinery tower. After condensing, collecting, and pressurizing the methyl acetate vapor volatilized from the extraction refinery tower tower, a part of the methyl acetate is extracted from the extraction distillation tower. Top reflux, the rest is sent to the deeziz tower feed; reflux flow / tower top production flow = 1.4;

 (3) Extract the methanol aqueous solution produced by the distillation flea tower flea and send it to the methanol refining system for recovery.

 The methyl acetate dehydration process unit includes the following operations:

 (1) Methyl acetate (the methyl acetate stream distilled from the top of the extractive distillation column and the gas-phase exhaust stream from the hydrolysis column) enter the deacetaldehyde column for vapor-liquid mass transfer;

 (2) After condensing, collecting, and pressurizing the steam distilled from the top of the deacetylation column, a part of the ethyl chloride is refluxed from the top of the deacetylation column, and the rest of the acetaldehyde is sent for purification; reflux flow / feed flow = 1.3;

 (3) Methyl acetate of Talea is fed to the top of the hydrolysis tower after being pressurized.

 The methyl acetate hydrolysis process unit includes the following operations:

 (1) Acetic acid from the deacetylation tower flea enters the hydrolysis tower, and the steam distilled from the top of the hydrolysis tower is condensed, collected, and pressurized, and then refluxed from the top of the hydrolysis tower. Uncondensed gas is used as a gas-phase impurity stream. Feed into the deacetaldehyde tower feed; reflux flow / feed flow = 3.4;

 (2) After treatment in the column packing section (packing section is equivalent to 8 theoretical plates), methyl acetate is extracted from the upper side line of the hydrolysis tower, mixed with methyl acetate hydrolyzed water after being pressurized, and sent into strong acidity. The cation exchange resin bed (feed temperature 65 ~ 75 V) is subjected to hydrolysis reaction to generate acetic acid and methanol. After the hydrolyzed solution is filtered to remove the broken resin entrained therein, it is returned to the middle and lower part of the hydrolysis tower for separation;

 Among them, the filtration uses a precision filter with a needle punched blanket as the filter medium, the thickness of the filter medium is 30mm, the pore diameter of the filter medium is less than 1pm, and the pressure drop is less than O.IMPa;

 (3) The hydrolysate (mainly composed of acetic acid, methanol, water and methyl acetate) of the hydrolysing tower flea is sent to the hydrolysate separation tower for separation after being pressurized.

 The hydrolysate separation process unit includes the following operations:

 (1) The hydrolysate flowing out of the hydrolysis tower and flea enters the hydrolysate separation tower for separation, and part of the vapor at the top of the tower is blown into the extractive distillation column, and the rest is condensed, collected, and pressurized, and then refluxed from the top of the hydrolysate separation tower. , Supplementary return flow / feed flow = 0.6;

 (2) The dilute acetic acid of the hydrolysate separation tower Talea is sent to the acetic acid refining tower after being pressurized for dehydration purification.

The acetic acid refining process unit includes the following operations: (1) Dilute acetic acid from tower flea from the hydrolysate is separated into the acetic acid purification tower. Isopropyl acetate is used as an azeotrope in the tower. The azeotrope of water and isopropyl acetate is distilled from the top of the tower. After the phases, isopropyl acetate in the upper house and separated water in the lower layer (containing a small amount of isopropyl acetate) were obtained;

 (2) The isopropyl acetate phase in the upper layer is sent to the top of the acetic acid refining tower for reflux after being pressurized. The separated water (containing a small amount of isopropyl acetate) in the lower layer is collected and sent to the isopropyl acetate recovery tower. Material flow = 3.8;

 (3) Acetic acid is extracted from the lower side line of the acetic acid purification tower, and the residue and tar from the tower kettle are sent out of the system.

 The isopropyl acetate recovery process unit includes the following operations:

 (1) The separated water from the acetic acid refining process unit enters the top of the isopropyl acetate recovery tower (the recovery tower only has a lift section). The gas at the top of the tower is condensed and 45X: the phases are separated to obtain the water phase and the oil phase, and the water is collected. Phase, the water phase is returned to the top of the isopropyl acetate recovery tower, and the oil phase is returned to the acetic acid refining unit after being pressurized;

 (2) The flea water from the isopropyl acetate recovery tower is sent out of the system after being pressurized.

 The process provided by this embodiment realizes the effective removal of the corrosive impurities of high-concentration acetic acid under the condition of low energy consumption, significantly alleviates the problem of equipment corrosion in the acetic acid refining process, and extends the life of key equipment by 4 to 5 times. Comparative Example 1

 The process of this comparative example is similar to that of Example 2, the difference is that

 (1) The process parameters are slightly different (see Table 1);

 (2) The packing section in the hydrolysis column is equivalent to 3 theoretical plates;

 (3) No precision filter is provided.

 The operating conditions of the main equipment in Example 2 and Comparative Example 1 are shown in Table 1. Table 1. Main equipment operating conditions

It can be known from Example 2 and Comparative Example 1: Strict control of the number of theoretical plates and operation parameters of the packing section of the hydrolysis column can enhance the removal ability of halogen impurities and aldehydes. Specifically, when F, When the CT and acetaldehyde concentrations were 134 ppm, 281 ppm, and 150 ppm, respectively, the F— and C1— concentrations in the hydrolyzed tower fleas in Example 2 were 7 ppm and 2 ppm, respectively. 1 ppm. In contrast, the concentration of F \ Cl— in the hydrolyzed tower fleas in Comparative Example 1 was 30 ppm and 20 ppm, respectively, and the concentration of ethyl acetate in the side of the hydrolyzed tower was 10 ppm. The setting of a precision filter can effectively filter the crushed resin entrained by the hydrolysate, thereby preventing the crushed resin from entering the acetic acid concentration system and causing equipment corrosion. Specifically, the resin content in the feed of the precision filter in Example 2 is 1000 ppm. The resin content in the output of the precision filter was reduced to 1 ppm, and the resin concentration in the hydrolyzed tower flea output was correspondingly 1 ppm; while in Comparative Example 1, because the precision filter was not provided, the resin concentration in the hydrolyzed tower flea material was 1000 ppm _» Comparative Example 1 The concentrations of F, Cl— and resin in the hydrolysate were significantly higher than those in Example 2, which illustrates that the technical measures of the present invention have achieved good beneficial effects. The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

Rights request

1. An anticorrosive device for methyl acetate hydrolysis and acetic acid purification during the recovery of polyvinyl alcohol mother liquor, characterized in that the anticorrosive device includes a methyl acetate concentration device, a methyl acetate dealdehyde device, a methyl acetate hydrolysis device, and a hydrolysate Separation device, acetic acid purification device and isopropyl acetate recovery device;

 The ethyl acetate concentration device includes an extraction refinery tower, the methyl acetate dealdehyde device includes a deacetylation tower, the methyl acetate hydrolysis device includes a hydrolysis tower, and the hydrolysate separation device includes a hydrolysate separation tower The acetic acid refining device includes an acetic acid refining tower, and the isopropyl acetate recovery device includes an isopropyl acetate recovery tower;

 Preferably, the extraction refinery tower, the deezization tower, the hydrolysis tower, the hydrolysate separation tower, the acetic acid purification tower and the isopropyl acetate recovery tower are connected in series according to the material flow direction.

2. The anticorrosive device according to claim 1, wherein the top of the extractive distillation column is connected to the middle of the deeziz tower, and the tower kettle of the deeze tower is connected to the top of the hydrolysis tower The tower flea of the hydrolysis tower is connected to the middle of the hydrolysate separation tower, the tower kettle of the hydrolysate separation tower is connected to the middle of the acetic acid purification tower, and the top of the acid purification tower is connected to the isopropyl acetate recovery tower. Top connection

 Wherein, the methyl methyl acid concentration device further includes an extractive distillation column condenser, an extractive distillation column reflux tank, an extractive distillation saturation column reflux pump, and an extractive refinement column reboiler;

 Preferably, the top of the extractive distillation column may be sequentially connected to the extractive distillation column condenser, the extractive distillation column reflux tank, and the extractive distillation column reflux pump; the outlet of the extractive distillation column reflux pump may be connected to the extractive distillation column; The top of the distillation column is connected, and a branch line connected to the deacetaldehyde tower is set on the connecting pipe;

 Preferably, the flea of the extractive distillation tower may be provided with an extractive refiner tower reboiler;

 Preferably, the tower kettle of the extractive distillation column may also be connected to a methanol refining system;

 Preferably, the methyl acetate concentration device may further include an extraction water inlet and a methyl acetate inlet. Preferably, the extraction water inlet is connected to the top of an extraction distillation column, and the methyl acetate inlet is connected to the extraction distillation. The middle of the tower is connected.

The anticorrosive device according to claim 1 or 2, wherein the methyl acetate dehydration device further comprises a deacetaldehyde tower condenser, a deacetaldehyde tower reflux tank, a deacetaldehyde tower reflux pump, Deacetaldehyde tower reboiler, deacetaldehyde tower flea pump; the top of the deacetaldehyde tower can be connected to the deacetaldehyde tower condenser, deacetaldehyde tower reflux tank, and deacetaldehyde tower reflux pump in sequence The outlet of the deacetylation reflux pump can be connected to the top of the deacetaldehyde column, and a branch line connected to the deacetylation refining system is provided on the connecting pipeline; The deacetaldehyde tower flea may be provided with a deacetaldehyde tower reboiler;

 The dezitzing flea can be connected in series with the dezitzing flea pump and the top of the hydrolysis tower.

4. The anticorrosive device according to any one of claims 1 to 3, wherein the methyl acetate hydrolysis device further comprises a strongly acidic cation exchange resin bed, a hydrolysis tower condenser, a hydrolysis tower reflux tank, and a hydrolysis tower reflux Pumps, side pumps for hydrolysis towers, reboilers for hydrolysis towers, kettle exit pumps for hydrolysis towers and precision filters;

 Preferably, the top of the hydrolysis tower may be sequentially connected with the hydrolysis tower condenser, the hydrolysis tower reflux tank, and the hydrolysis tower reflux pump; the outlet of the hydrolysis tower reflux pump may be connected with the top of the hydrolysis tower; the hydrolysis tower condenser is also Can be connected to the middle of Deezita;

 Preferably, the upper side line mining outlet of the hydrolysis tower may be sequentially connected with the hydrolysis tower side mining pump, the strong acid cation exchange resin bed, and the precision filter, and the outlet of the precision filter is connected with the middle of the hydrolysis tower;

 Preferably, a packing section may be set in the hydrolysis column, and the packing section is located above the upper side line mining outlet; preferably, the packing section is equivalent to 5 to 10 theoretical tray plates;

 Preferably, the tower kettle of the hydrolysis tower may be provided with a hydrolysis tower reboiler;

 Preferably, the flea of the hydrolysis tower may be sequentially connected with the pump of the hydrolysis flea and the middle of the hydrolysate separation tower; preferably, the methyl acetate hydrolysis device may further include an ethyl acetate hydrolysis water inlet, which is provided at Dezitzata fleas are connected to the top of the hydrolysis tower.

The anticorrosive device according to any one of claims 1 to 4, wherein the hydrolysate separation device further comprises a hydrolysate separation tower condenser, a hydrolysate separation tower reflux tank, a hydrolysate separation tower reflux pump, Hydrolysate separation tower reboiler, hydrolysate separation tower flea pump;

 Preferably, two branches can be set on the top of the hydrolysate separation tower. Branch 1 is connected to the middle of the extraction distillation column, and branch 2 is connected to the condenser of the hydrolysate separation tower, the reflux tank of the hydrolysate separation tower, and hydrolysis. The reflux pump of the liquid separation tower is connected sequentially; the outlet of the reflux pump of the hydrolysis liquid separation tower is connected to the top of the hydrolysis liquid separation tower;

 Preferably, the flea of the hydrolysate separation tower may be provided with a reboiler of the hydrolysate separation tower;

Preferably, the flea in the hydrolysate separation tower can be connected in series with the pump in the hydrolysate separation tower and the middle of the acetic acid purification tower.

6. The anticorrosive device according to any one of claims 1 to 5, wherein the acetic acid refining tower further comprises an acetic acid refining tower condenser, an acetic acid refining tower phase separator, an acetic acid refining tower reflux pump, and an acetic acid refining tower. Reboiler, side extraction pump for acetic acid purification tower, and outlet pump for acetic acid purification tower;

 Preferably, the top of the acetic acid refining tower may be sequentially connected with the condenser of the acetic acid refining tower and the phase separator of the acetic acid refining tower, and the phase separator of the acid refining tower may be provided with outlet one and outlet two, and outlet one and The reflux pump of the acetic acid refining tower and the top of the acetic acid refining tower are connected in sequence;

 Preferably, the outlet of the lower side line of the acetic acid refining tower may be connected to the side pump of the acetic acid refining tower to produce acetic acid; preferably, the tower kettle of the acetic acid refining tower may be provided with an acetic acid refining tower reboiler;

 Preferably, the flea of the acetic acid refining tower may be connected to an acetic acid refining tower flea pump to discharge residues and tars; preferably, the isopropyl acetate recovery device further includes an isopropyl gallate recovery tower condenser, acetic acid Isopropyl ester recovery tower phase separator, isopropyl acetate recovery tower building pump, isopropyl acetate water phase receiving tank, isopropyl acetate recovery tower feed pump, isopropyl acetate recovery tower reboiler, isopropyl acetate Propyl ester recovery tower flea pump;

 Preferably, the phase separator of the acetic acid purification tower may be provided with an oil phase outlet and a water phase outlet;

 Preferably, the outlet two of the phase separator of the acetic acid refining tower may be sequentially connected to the top of the isopropyl acetate water phase receiving tank, the isopropyl acetate recovery tower feed pump, and the isopropyl acetate recovery tower;

 Preferably, the top of the isopropyl acetate recovery tower may be sequentially connected to the condenser of the isopropyl acetate recovery tower and the phase separator of the isopropyl acetate recovery tower; the oil phase outlet of the phase separator of the acetic acid purification tower The pump of the isopropyl acetate recovery tower and the phase separator of the acetic acid purification tower are connected in sequence; the water phase outlet of the phase separator of the acetic acid purification tower can be connected to the water phase receiving tank of isopropyl acetate;

 Preferably, the flea of the isopropyl acetate recovery tower may be provided with a reboiler of the isopropyl acetate recovery tower;

 Preferably, the flea of the isopropyl acetate recovery tower may be connected to an isopropyl acetate recovery tower flea pump to send water out of the kettle.

7. An anticorrosive process of methyl acetate hydrolysis and acetic acid purification, characterized in that the process uses the anticorrosive device according to any one of claims 1 to 6, wherein the anticorrosive process mainly includes methyl acetate concentration, methyl acetate dealdehyde, Hydrolysis of methyl acetate, separation of hydrolysate, purification of acetic acid and recovery of isopropyl acetate.

8. The anticorrosive process according to claim 7, wherein the methyl acetate concentration process unit comprises the following operations:

(1) Crude methyl acetate enters the extraction refinery tower to separate methyl acetate from methanol; (2) Add extraction water to the top of the extractive distillation column. After methyl acetate vapor volatilized from the top of the extractive distillation column is condensed, collected, and pressurized, a part of the methyl acetate is refluxed from the top of the extractive saturated column, and the rest Feed into Deezita feed;

 (3) extract the methanol aqueous solution produced by the flea from the distillation column and send it to the methanol refining system for recovery;

 Preferably, the source of the above crude methyl acetate includes crude methyl acetate from a crude methyl acetate unit and crude methyl acetate distilled from the top of a hydrolysate separation column in a methyl acetate hydrolyzing section;

 Preferably, the temperature of the extraction water is 2 ~ 15 ° C;

 Preferably, the operating parameters of the extractive distillation column are: a pressure of 0.085 to 0.15 MPa, a temperature at the top of the column of 50 to 601C, a temperature of the tower flea of 75 to 851 :, the reflux flow at the top of the column / the output flow at the top of the column = 1.3 to 1.7;

 The methyl acetate decoupling process unit includes the following operations:

 (1) Methyl acetate enters the deacetaldehyde tower for vapor-liquid chip transfer;

 (2) After the steam distilled from the top of the deacetylation tower is condensed, collected, and pressurized, a part of the ethyl acetate is refluxed from the top of the deethylation brewing tower, and the rest is sent for purification;

 (3) The methyl acetate in the tower kettle is fed to the top of the hydrolysis tower after being pressurized;

 Preferably, the methyl acetate in step (1) includes a methyl acetate stream distilled from the top of the extraction tower and a gas-phase impurity stream from the hydrolysis column;

 Preferably, the operating parameters of the deacetaldehyde column are: a pressure of 0.085 to 0.15 MPa, a tower top temperature of 45 to 55 ° C, a tower kettle temperature of 50 to 60 t :, reflux flow / feed flow = 1.2 to 1.7.

The anticorrosive process according to claim 7 or 8, wherein the methyl acetate hydrolysis process unit comprises the following operations:

 (1) Methyl acetate flowing from Dezitzata flea enters the hydrolysis tower, and the steam distilled from the top of the hydrolysis tower is condensed, collected, and pressurized, and then refluxed from the top of the hydrolysis tower. Uncondensed gas is used as a gas phase impurity stream. The stock is fed into the deacetaldehyde tower feed;

 (2) The methyl acetate is extracted from the upper side line of the hydrolysis tower, mixed with methyl acetate hydrolyzed water after being pressurized, and sent to a strongly acidic cation exchange resin bed for hydrolysis reaction to generate acetic acid and methanol. The hydrolyzed solution is filtered to remove entrainment. After crushing the resin, return to the middle and lower part of the hydrolysis tower for separation;

 Preferably, the methyl acetate extracted from the upper side line of the above hydrolysis column is treated by a packing section in the tower, and the packing section is equivalent to 5 to 10 theoretical plates;

Preferably, the operating parameters of the hydrolysis tower are: pressure 0.085 ~ 0.15MPa, tower top temperature is 55-65V, tower kettle temperature is 80 ~ 85T :, side line extraction temperature 60 ~ 65 "C, reflux flow rate / inlet Material flow = 3.3 ~ 4.2; Preferably, the above-mentioned filtration uses a precision filter, the precision filter uses a needle felt as a filter medium, the thickness of the filter medium is 20 ~ 30mm, and the pore diameter of the filter medium is less than lpm;

 Preferably, the operating conditions of the precision filter are: the pressure drop is less than O.IMPa;

 Preferably, the operating parameters of the strongly acidic cation exchange resin bed are: a feed temperature of 65 to 75C, such as 70C;

(3) After the pressure of the hydrolysis solution of the hydrolytic tower flea is increased, it is sent to the hydrolysate separation tower for separation;

 Wherein, the hydrolysis liquid separation process unit includes the following operations:

 (1) The hydrolysate flowing out of the hydrolysis tower and flea enters the hydrolysate separation tower for separation, and part of the vapor at the top of the tower is blown into the extractive distillation column, and the rest is condensed, collected, and pressurized, and then refluxed from the top of the hydrolysate separation tower. ;

 (2) The dilute acetic acid of the hydrolysate separation Tata flea is sent to the acetic acid refining tower after being pressurized for dehydration refining;

 Preferably, the operating parameters of the hydrolysate separation tower are: pressure 0.085 ~ 0.15MPa, tower top temperature is 60 ~ 70 ° C, tower flea temperature is 110 ~ 1151C, and supplementary return flow / feed flow = 0.55 ~ 1.1.

The anticorrosive process according to any one of claims 7 to 9, wherein the acetic acid refining process unit comprises the following operations:

 (1) Dilute the acetic acid from Tata fleas from the hydrolysate to enter the acetic acid refining tower. Distillate the azeotrope of water and isopropyl acetate from the top of the tower. After condensation and phase separation, the upper isopropyl acetate and lower layer are obtained Separation water (containing a small amount of isopropyl acetate); preferably, isopropyl acetate is used as an azeotrope in the acetic acid purification tower;

 (2) The isopropyl acetate phase in the upper layer is sent to the top of the acetic acid refining tower for reflux after being pressurized, and the separated water (containing a small amount of isopropyl acetate) in the lower layer is collected and sent to the isopropyl acetate recovery tower;

 (3) Acetic acid is extracted from the lower side line of the acetic acid refining tower, and the residues and tar of the fleas are sent out of the system;

 Preferably, the operating parameters of the acetic acid refining tower are: pressure 0.085 ~ 0.15MPa, tower top temperature 70 ~ 801C, tower flea temperature 120 ~ 125X :, lower side line extraction temperature 120 ~ 125X :, reflux flow / inlet Material flow = 3.7 ~ 4.2;

 Wherein, the isopropyl acetate recovery process unit includes the following operations:

 (1) The separated water from the acetic acid refining process unit enters the top of the isopropyl acetate recovery tower, and the gas at the top of the tower is condensed and separated to obtain the water phase and the oil phase. The water phase is collected, and the water phase is returned to the isopropyl acetate recovery. At the top of the tower, the oil phase is returned to the acetic acid refining unit after being pressurized;

 (2) The water from the tower kettle of the isopropyl acetate recovery tower is sent out to the system after being pressurized;

 Preferably, the operating parameters of the isopropyl acetate recovery tower are: a pressure of 0.085 to 0.15 MPa, a tower top temperature of 90-100 ° C, and a tower flea temperature of 95 to 1031 C; preferably, the phase-separated operating temperature 35 ~ 45T :.