阅读说明：本技术 一种聚芳硫醚原料的连续脱水预处理方法及系统 (Continuous dehydration pretreatment method and system for polyarylene sulfide raw material ) 是由 章驰 李吉辉 尹玉庆 郭彦超 于 2021-08-02 设计创作，主要内容包括：本发明特别涉及一种聚芳硫醚原料的连续脱水预处理方法及系统。该聚芳硫醚原料的连续脱水预处理方法及系统,将N个脱水反应釜和/或M个S级板式脱水塔串联形成脱水预处理系统；原料依次经过串联的脱水反应釜和/或S级板式脱水塔,蒸出的含水气相进入各脱水反应釜和/或板式脱水塔顶部的冷凝器,冷凝回收脱出的水份,将蒸出的有机溶剂重新回到脱水预处理系统中,不凝气则送到气相洗涤净化系统。该聚芳硫醚原料的连续脱水预处理方法及系统,原料脱水率完全可控、稳定,含硫单体分解率和脱出的冷凝水中溶剂浓度均较低,脱水物料组成稳定,有利于后续缩聚反应过程工艺控制的稳定性、可靠性；同时降低了原料的分解损耗,降低了成本,更加绿色环保。(The invention particularly relates to a continuous dehydration pretreatment method and a continuous dehydration pretreatment system for a polyarylene sulfide raw material. The method and the system for the continuous dehydration pretreatment of the polyarylene sulfide raw material are characterized in that N dehydration reaction kettles and/or M S-grade plate-type dehydration towers are connected in series to form a dehydration pretreatment system; the raw materials sequentially pass through dehydration reaction kettles and/or S-grade plate dehydration towers which are connected in series, the evaporated water-containing gas phase enters condensers at the tops of the dehydration reaction kettles and/or the plate dehydration towers, the evaporated water is condensed and recovered, the evaporated organic solvent returns to a dehydration pretreatment system again, and the non-condensable gas is sent to a gas phase washing and purifying system. According to the method and the system for the continuous dehydration pretreatment of the polyarylene sulfide raw material, the dehydration rate of the raw material is completely controllable and stable, the decomposition rate of the sulfur-containing monomer and the concentration of the solvent in the dehydrated condensed water are both low, and the composition of the dehydrated material is stable, so that the stability and the reliability of the process control in the subsequent polycondensation reaction process are facilitated; meanwhile, the decomposition loss of the raw materials is reduced, the cost is reduced, and the environment is protected.)

1. A method for continuous dehydration pretreatment of a polyarylene sulfide raw material is characterized by comprising the following steps: the method comprises the following steps:

firstly, connecting N dehydration reaction kettles and/or M S-stage plate-type dehydration towers in series to form a dehydration pretreatment system, wherein N, M and S are natural numbers, the sum of N and M is not less than 2, and S is not less than 2; a condenser is arranged at the top of each dehydration reaction kettle and/or S-grade plate-type dehydration tower, and the dehydration reaction kettles and/or S-grade plate-type dehydration towers which are connected in series in the dehydration pretreatment system realize material transfer through potential difference natural overflow or conveying pump conveying;

secondly, fully replacing air in the dehydration pretreatment system with nitrogen flow, metering raw materials by a metering pump, continuously adding the raw materials required by the synthesis of the polyarylene sulfide into a first-stage feed inlet of the dehydration system, and controlling the retention time T, the dehydration temperature T and the operation pressure P of the raw materials in the dehydration pretreatment system;

and thirdly, the raw materials sequentially pass through the dehydration reaction kettles and/or the S-grade plate dehydration towers which are connected in series, the water-containing gas phase evaporated by the dehydration reaction kettles and/or the S-grade plate dehydration towers which are connected in series enters a condenser at the top of each dehydration reaction kettle and/or plate dehydration tower, the evaporated water is condensed and recovered, the evaporated organic solvent is returned to the dehydration pretreatment system again, and the non-condensable gas is conveyed to a gas phase washing and purifying system.

2. The method for continuous dehydration pretreatment of polyarylene sulfide raw material according to claim 1, characterized in that: in the first step, each dehydration reaction kettle and/or S-grade plate-type dehydration tower is provided with a heat exchange jacket and/or an inner coil pipe, and steam or heat conducting oil is introduced into the heat exchange jacket and/or the inner coil pipe to control and adjust the dehydration temperature T.

3. The method for continuous dehydration pretreatment of polyarylene sulfide raw material according to claim 1, characterized in that: in the first step, a heat exchanger is arranged between each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series to exchange heat for materials so as to adjust the temperature of the materials entering the next-stage dehydration reaction kettle or S-grade plate-type dehydration tower.

4. The method for continuous dehydration pretreatment of polyarylene sulfide raw material according to claim 2, characterized in that: in the first step, a set of condenser is shared by all the dehydration reaction kettles and/or S-grade plate-type dehydration towers which are connected in series in the dehydration pretreatment system, the temperature gradient of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, and all the dehydration reaction kettles and/or S-grade plate-type dehydration towers are dehydrated at different dehydration temperatures T respectively, but the operation pressures P are the same.

5. The method for continuous dehydration pretreatment of polyarylene sulfide raw material according to claim 2, characterized in that: in the first step, each serial dehydration reaction kettle and/or S-grade plate-type dehydration tower in the dehydration pretreatment system is respectively provided with a set of independent condenser so as to realize independent condensation and collection of vapor phase under the conditions of different dehydration temperatures T and operation pressures P; the non-condensable gas output by each condenser is combined and then enters a gas phase washing and purifying system.

6. The method for continuous dehydration pretreatment of polyarylene sulfide raw material according to claim 4 or 5, characterized in that: in the second step, the retention time T is 30-300 min, the dehydration temperature T is 80-220 ℃, and the operation pressure P is-0.085-0.15 MPa;

the temperature of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, the dehydration temperature T between each dehydration reaction kettle and/or S-grade plate dehydration tower realizes gradient temperature control, the dehydration temperature T of the dehydration reaction kettle or S-grade plate dehydration tower at the feed end is 80-120 ℃, and the dehydration temperature T of the dehydration reaction kettle or S-grade plate dehydration tower at the discharge end is 180-220 ℃;

the temperature gradient of each tower plate in the S-stage plate-type dehydration tower is controlled by the temperature gradient of a heating medium in the heat exchange jacket and/or the inner coil.

7. The method for continuous dehydration pretreatment of polyarylene sulfide raw material according to claim 6, characterized in that: and in the third step, the dehydration amount of the condenser and the refractive index of the dehydration liquid are monitored in real time, and the feeding speed, the dehydration temperature of the dehydration pretreatment system and the extraction speed of the dehydration liquid are controlled to ensure that the molar ratio of the total content of the sulfur source in the dehydration pretreatment system to the residual moisture in the dehydration pretreatment system is controlled to be 1: 1.0-1: 5.0.

8. A continuous dehydration pretreatment system of polyarylene sulfide raw material is characterized in that: the system comprises N dehydration reaction kettles and/or M S-stage plate-type dehydration towers which are connected in series, wherein N, M and S are natural numbers, the sum of N and M is not less than 2, and S is not less than 2; the dehydration reaction kettles and/or S-grade plate dehydration towers which are connected in series in the dehydration pretreatment system realize material transfer through potential difference natural overflow or conveying by a conveying pump; a condenser is arranged at the top of each dehydration reaction kettle and/or S-grade plate-type dehydration tower, the condenser is connected with a condensate water tank and a gas phase washing and purifying system, the condensate water tank is used for receiving and metering condensate water, non-condensable gas in the condenser is connected into the gas phase washing and purifying system, and the organic solvent after moisture removal returns to the dehydration pretreatment system;

each dehydration reaction kettle and/or S-grade plate-type dehydration tower is provided with a heat exchange jacket and/or an inner coil, and steam or heat conducting oil is introduced into the heat exchange jacket and/or the inner coil to control and adjust the dehydration temperature T, so that the control of the temperature gradient of the dehydration pretreatment system from the feed end to the discharge end is realized;

the dewatering pretreatment system is internally provided with a flowmeter quantum system, a temperature detection subsystem and a pressure detection subsystem, and is used for detecting the real-time flow, temperature and pressure of the material at each part;

each dehydration reaction kettle and/or S-grade plate-type dehydration tower connected in series in the dehydration pretreatment system shares a set of condenser, the temperature gradient of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, and each dehydration reaction kettle and/or S-grade plate-type dehydration tower is dehydrated at different dehydration temperature T, but the operation pressure P is the same;

or each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series in the dehydration pretreatment system are respectively provided with a set of independent condensers so as to realize the independent condensation and collection of vapor phases under the conditions of different dehydration temperatures T and operation pressures P; the non-condensable gas output by each condenser is combined and then enters a gas phase washing and purifying system.

9. The continuous dehydration pretreatment system for polyarylene sulfide raw material according to claim 8, characterized in that: and a heat exchanger is arranged between each dehydration reaction kettle and/or the S-grade plate-type dehydration tower which are connected in series to exchange heat for the material so as to adjust the temperature of the material entering the next-stage dehydration reaction kettle or the S-grade plate-type dehydration tower.

10. The continuous dehydration pretreatment system for polyarylene sulfide raw material according to claim 8, characterized in that: the feed inlet is connected with a nitrogen tank, and the discharge outlet is connected with a sampling device of a refractometer.

Technical Field

The invention relates to the technical field of polymer material synthesis industry, in particular to a continuous dehydration pretreatment method and a continuous dehydration pretreatment system for a polyarylene sulfide raw material.

Background

The polyarylene sulfide functional resin is a thermoplastic polymer functional material with wide application, has excellent chemical corrosion resistance, high temperature resistance, good electrical property, flame retardant property, high mechanical strength and dimensional stability, and compatibility and processability with other materials, and is widely applied to the industrial fields of electronic and electric appliances, aerospace, automobiles and transportation, military industry, precision instruments, pharmaceutical and chemical pipeline fittings and valves, 3D printing, new energy batteries, ecological environment restoration and the like.

In 1963, the person skilled in the art proposed a process for the reaction of sodium sulfide and p-dichlorobenzene in N-methylpyrrolidone (NMP) to give polyphenylene sulfide (PPS), and in 1973 the commercial production of polyarylene sulfides was first achieved. However, in the process of synthesizing polyarylene sulfide resin by the sodium sulfide route, the water content in the raw materials greatly affects the progress of polycondensation reaction, and affects the molecular weight and stability of the resin. Therefore, the crystal water of the crystallized sodium sulfide must be partially removed to meet the requirements of the polycondensation process.

The common dehydration method comprises dehydration outside a kettle and dehydration inside the kettle. Dehydrating outside the kettle, namely drying in vacuum to remove crystal water in advance, and adding sodium sulfide into the reaction system in an anhydrous form; the water in the kettle can be removed by adding crystallized sodium sulfide, distilling to remove water, or adding entrainer such as toluene, cyclohexanone, cyclohexane, etc. to form azeotropic mixture with water to remove water.

Because sodium sulfide can not be well dissolved in a solvent NMP of condensation reaction, the dehydration process is a solid-liquid heterogeneous process, the sodium sulfide dispersed in the system is decomposed by heating, the dehydration process is difficult, the dehydration rate and the decomposition rate of the sodium sulfide are difficult to stably control, so that the material ratio participating in the polycondensation reaction process is seriously influenced, the speed of the polycondensation reaction is influenced, and the polyarylene sulfide resin with low molecular weight is decomposed and colored by heating for a long time; affecting the yield and quality of the resin.

In order to solve the above problems, those skilled in the art have proposed the production of polyarylene sulfide using sodium hydrosulfide instead of sodium sulfide as a sulfur source, adding a sodium hydroxide solution to carry out neutralization reaction, and then dehydrating. The method is a gradual change process from homogeneous reaction to heterogeneous reaction, the system uniformity is high, and the dehydration rate is better controlled by heating temperature, a temperature rise process and dehydration time. However, the method is produced in an intermittent mode, sodium hydrosulfide and sodium hydroxide need to be fed once, the material quantity is large, and the method can only be operated manually. The stability of dehydration process receives stirring effect to be influenced very much, and the stirring is insufficient, and the inhomogeneous system that can mix acutely produces the bubble, and reaction thick liquids acutely bubble, bubble can wrap up in the reaction thick liquids and follow the dehydration and extract the export together and rush out fast, cause thick liquids loss and delivery port to block up.

Aiming at the problems, the invention provides a continuous dehydration pretreatment method and a continuous dehydration pretreatment system for polyarylene sulfide raw materials.

Disclosure of Invention

The invention provides a simple and efficient continuous dehydration pretreatment method and system for polyarylene sulfide raw materials in order to make up for the defects of the prior art.

The invention is realized by the following technical scheme:

a method for continuous dehydration pretreatment of a polyarylene sulfide raw material is characterized by comprising the following steps: the method comprises the following steps:

firstly, connecting N dehydration reaction kettles and/or M S-stage plate-type dehydration towers in series to form a dehydration pretreatment system, wherein N, M and S are natural numbers, the sum of N and M is not less than 2, and S is not less than 2; a condenser is arranged at the top of each dehydration reaction kettle and/or S-grade plate-type dehydration tower, and the dehydration reaction kettles and/or S-grade plate-type dehydration towers which are connected in series in the dehydration pretreatment system realize material transfer through potential difference natural overflow or conveying pump conveying;

secondly, fully replacing air in the dehydration pretreatment system with nitrogen flow, metering raw materials by a metering pump, continuously adding the raw materials required by the synthesis of the polyarylene sulfide into a first-stage feed inlet of the dehydration system, and controlling the retention time T, the dehydration temperature T and the operation pressure P of the raw materials in the dehydration pretreatment system;

and thirdly, the raw materials sequentially pass through the dehydration reaction kettles and/or the S-grade plate dehydration towers which are connected in series, the water-containing gas phase evaporated by the dehydration reaction kettles and/or the S-grade plate dehydration towers which are connected in series enters a condenser at the top of each dehydration reaction kettle and/or plate dehydration tower, the evaporated water is condensed and recovered, the evaporated organic solvent is returned to the dehydration pretreatment system again, and the non-condensable gas is conveyed to a gas phase washing and purifying system.

In the first step, each dehydration reaction kettle and/or S-grade plate-type dehydration tower is provided with a heat exchange jacket and/or an inner coil pipe, and steam or heat conducting oil is introduced into the heat exchange jacket and/or the inner coil pipe to control and adjust the dehydration temperature T.

In the first step, a heat exchanger is arranged between each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series to exchange heat for materials so as to adjust the temperature of the materials entering the next-stage dehydration reaction kettle or S-grade plate-type dehydration tower.

In the first step, a set of condenser is shared by all the dehydration reaction kettles and/or S-grade plate-type dehydration towers which are connected in series in the dehydration pretreatment system, the temperature gradient of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, and all the dehydration reaction kettles and/or S-grade plate-type dehydration towers are dehydrated at different dehydration temperatures T respectively, but the operation pressures P are the same.

In the first step, each serial dehydration reaction kettle and/or S-grade plate-type dehydration tower in the dehydration pretreatment system is respectively provided with a set of independent condenser so as to realize independent condensation and collection of vapor phase under the conditions of different dehydration temperatures T and operation pressures P; the non-condensable gas output by each condenser is combined and then enters a gas phase washing and purifying system.

In the second step, the retention time T is 30-300 min, the dehydration temperature T is 80-220 ℃, and the operation pressure P is-0.085-0.15 MPa;

the temperature of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, the dehydration temperature T between each dehydration reaction kettle and/or S-grade plate dehydration tower realizes gradient temperature control, the dehydration temperature T of the dehydration reaction kettle or S-grade plate dehydration tower at the feed end is 80-120 ℃, and the dehydration temperature T of the dehydration reaction kettle or S-grade plate dehydration tower at the discharge end is 180-220 ℃;

the temperature gradient of each tower plate in the S-stage plate-type dehydration tower is controlled by the temperature gradient of a heating medium in the heat exchange jacket and/or the inner coil.

And in the third step, the dehydration amount of the condenser and the refractive index of the dehydration liquid are monitored in real time, and the feeding speed, the dehydration temperature of the dehydration pretreatment system and the extraction speed of the dehydration liquid are controlled to ensure that the molar ratio of the total content of the sulfur source in the dehydration pretreatment system to the residual moisture in the dehydration pretreatment system is controlled to be 1: 1.0-1: 5.0.

A continuous dehydration pretreatment system of polyarylene sulfide raw material is characterized in that: the system comprises N dehydration reaction kettles and/or M S-stage plate-type dehydration towers which are connected in series, wherein N, M and S are natural numbers, the sum of N and M is not less than 2, and S is not less than 2; the dehydration reaction kettles and/or S-grade plate dehydration towers which are connected in series in the dehydration pretreatment system realize material transfer through potential difference natural overflow or conveying by a conveying pump; a condenser is arranged at the top of each dehydration reaction kettle and/or S-grade plate-type dehydration tower, the condenser is connected with a condensate water tank and a gas phase washing and purifying system, the condensate water tank is used for receiving and metering condensate water, non-condensable gas in the condenser is connected into the gas phase washing and purifying system, and the organic solvent after moisture removal returns to the dehydration pretreatment system;

each dehydration reaction kettle and/or S-grade plate-type dehydration tower is provided with a heat exchange jacket and/or an inner coil, and steam or heat conducting oil is introduced into the heat exchange jacket and/or the inner coil to control and adjust the dehydration temperature T, so that the control of the temperature gradient of the dehydration pretreatment system from the feed end to the discharge end is realized;

the dewatering pretreatment system is internally provided with a flowmeter quantum system, a temperature detection subsystem and a pressure detection subsystem, and is used for detecting the real-time flow, temperature and pressure of the material at each part;

each dehydration reaction kettle and/or S-grade plate-type dehydration tower connected in series in the dehydration pretreatment system shares a set of condenser, the temperature gradient of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, and each dehydration reaction kettle and/or S-grade plate-type dehydration tower is dehydrated at different dehydration temperature T, but the operation pressure P is the same;

or each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series in the dehydration pretreatment system are respectively provided with a set of independent condensers so as to realize the independent condensation and collection of vapor phases under the conditions of different dehydration temperatures T and operation pressures P; the non-condensable gas output by each condenser is combined and then enters a gas phase washing and purifying system.

In the dehydration pretreatment system, a heat exchanger is arranged between each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series to exchange heat for materials so as to adjust the temperature of the materials entering the next-stage dehydration reaction kettle or S-grade plate-type dehydration tower.

The feed inlet of the dehydration pretreatment system is connected with a nitrogen tank, and the discharge outlet is connected with a sampling device of a refractometer.

The invention has the beneficial effects that: according to the method and the system for the continuous dehydration pretreatment of the polyarylene sulfide raw material, the dehydration rate of the raw material is completely controllable and stable, the decomposition rate of the sulfur-containing monomer and the concentration of the solvent in the dehydrated condensed water are both low, and the composition of the dehydrated material is stable, so that the stability and the reliability of the process control in the subsequent polycondensation reaction process are facilitated; meanwhile, the decomposition loss of the raw materials is reduced, the cost is reduced, and the environment is protected.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic view of a continuous dehydration pretreatment system for polyarylene sulfide raw materials consisting of 4 dehydration reaction kettles according to the present invention.

FIG. 2 is a schematic diagram of the S-stage plate-type dehydration tower of the present invention.

FIG. 3 is a schematic view of a continuous dehydration pretreatment system for polyarylene sulfide raw material composed of a dehydration reactor and an S-stage plate-type dehydration tower according to the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the embodiment of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The continuous dehydration pretreatment method of the polyarylene sulfide raw material comprises the following steps:

firstly, connecting N dehydration reaction kettles and/or M S-stage plate-type dehydration towers in series to form a dehydration pretreatment system, wherein N, M and S are natural numbers, the sum of N and M is not less than 2, and S is not less than 2; a condenser is arranged at the top of each dehydration reaction kettle and/or S-grade plate-type dehydration tower, and the dehydration reaction kettles and/or S-grade plate-type dehydration towers which are connected in series in the dehydration pretreatment system realize material transfer through potential difference natural overflow or conveying pump conveying;

secondly, fully replacing air in the dehydration pretreatment system with nitrogen flow, metering raw materials by a metering pump, continuously adding the raw materials required by the synthesis of the polyarylene sulfide into a first-stage feed inlet of the dehydration system, and controlling the retention time T, the dehydration temperature T and the operation pressure P of the raw materials in the dehydration pretreatment system;

raw materials for synthesizing the polyarylene sulfide comprise a sulfur source compound, alkali liquor, a catalyst, an auxiliary agent and a solvent, wherein the sulfur source compound is sodium sulfide, sodium sulfide containing crystal water, sodium hydrosulfide crystal, a sodium hydrosulfide aqueous solution, lithium hydrosulfide, a lithium hydrosulfide aqueous solution, lithium sulfide and other compounds in aqueous solution, and the mass fraction of the sulfur source compound is 10-60%; the alkali liquor is an aqueous solution of an alkaline substance (sodium hydroxide or lithium hydroxide) and has a mass fraction of 20-60%; the molar ratio of the sulfur source compound to the alkaline substance is 1:1 to 1: 1.2.

and thirdly, the raw materials sequentially pass through the dehydration reaction kettles and/or the S-grade plate dehydration towers which are connected in series, the water-containing gas phase evaporated by the dehydration reaction kettles and/or the S-grade plate dehydration towers which are connected in series enters a condenser at the top of each dehydration reaction kettle and/or plate dehydration tower, the evaporated water is condensed and recovered, the evaporated organic solvent is returned to the dehydration pretreatment system again, and the non-condensable gas is conveyed to a gas phase washing and purifying system.

In the first step, each dehydration reaction kettle and/or S-grade plate-type dehydration tower is provided with a heat exchange jacket and/or an inner coil pipe, and steam or heat conducting oil is introduced into the heat exchange jacket and/or the inner coil pipe to control and adjust the dehydration temperature T.

In the first step, a heat exchanger is arranged between each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series to exchange heat for materials so as to adjust the temperature of the materials entering the next-stage dehydration reaction kettle or S-grade plate-type dehydration tower.

In the first step, a set of condenser is shared by all the dehydration reaction kettles and/or S-grade plate-type dehydration towers which are connected in series in the dehydration pretreatment system, the temperature gradient of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, and all the dehydration reaction kettles and/or S-grade plate-type dehydration towers are dehydrated at different dehydration temperatures T respectively, but the operation pressures P are the same.

The gas phase condensate evaporated from the dehydration reaction kettle at the low temperature section (80-180 ℃) has high moisture content and low organic solvent content; the water content of the gas phase condensate evaporated from the high-temperature section dehydration reaction kettle (180-220 ℃) is low, and the solvent content is high; in the first step, each serial dehydration reaction kettle and/or S-grade plate-type dehydration tower in the dehydration pretreatment system can also be respectively provided with a set of independent condenser so as to realize independent condensation and collection of vapor phase under the conditions of different dehydration temperatures T and operation pressures P; the non-condensable gas output by each condenser is combined and then enters a gas phase washing and purifying system.

In the second step, the retention time T is 30-300 min, the dehydration temperature T is 80-220 ℃, and the operation pressure P is-0.085-0.15 MPa;

the temperature of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, the dehydration temperature T between each dehydration reaction kettle and/or S-grade plate dehydration tower realizes gradient temperature control, the dehydration temperature T of the dehydration reaction kettle or S-grade plate dehydration tower at the feed end is 80-120 ℃, and the dehydration temperature T of the dehydration reaction kettle or S-grade plate dehydration tower at the discharge end is 180-220 ℃;

FIG. 2 is a schematic structural view of a plate-type dehydration column. The plate type dehydration tower reactor is internally provided with devices such as tower plates, downcomers, overflow weirs, gas distributors and the like, each tower plate is provided with a temperature detector, the outer part of the plate type dehydration tower reactor is provided with a heat exchange jacket, and the jacket is provided with a heating medium inlet and a heating medium outlet.

The temperature gradient of each tower plate in the S-stage plate-type dehydration tower is controlled by the temperature gradient of a heating medium in the heat exchange jacket and/or the inner coil. The temperature of the S-grade plate-type dehydration tower is ensured to be 190-220 ℃, and the temperature of the first plate is 80-120 ℃. Gradient temperature rise is realized for each tower plate in the middle.

When a continuous dehydration pretreatment process of a multi-stage series orifice plate dehydration tower is adopted, materials can enter from the bottom of the orifice plate dehydration tower and exit from the side line at the upper part of the orifice plate dehydration tower; or can enter from the upper side line of the tower and discharge from the bottom of the tower; the flow transfer of the materials among the towers can adopt potential difference natural overflow or conveying pump conveying; the evaporated water-containing gas phase is discharged from the top of the dehydrating tower and enters a tower top condenser to be condensed and recovered with the evaporated water and the solvent.

And in the third step, the dehydration amount of the condenser and the refractive index of the dehydration liquid are monitored in real time, and the feeding speed, the dehydration temperature of the dehydration pretreatment system and the extraction speed of the dehydration liquid are controlled to ensure that the molar ratio of the total content of the sulfur source in the dehydration pretreatment system to the residual moisture in the dehydration pretreatment system is controlled to be 1: 1.0-1: 5.0.

The continuous dehydration pretreatment system for the polyarylene sulfide raw material comprises N dehydration reaction kettles and/or M S-grade plate-type dehydration towers which are mutually connected in series, wherein N, M and S are natural numbers, the sum of N and M is not less than 2, and S is not less than 2; the dehydration reaction kettles and/or S-grade plate dehydration towers which are connected in series in the dehydration pretreatment system realize material transfer through potential difference natural overflow or conveying by a conveying pump; a condenser is arranged at the top of each dehydration reaction kettle and/or S-grade plate-type dehydration tower, the condenser is connected with a condensate water tank and a gas phase washing and purifying system, the condensate water tank is used for receiving and metering condensate water, non-condensable gas in the condenser is connected into the gas phase washing and purifying system, and the organic solvent after moisture removal returns to the dehydration pretreatment system;

each dehydration reaction kettle and/or S-grade plate-type dehydration tower is provided with a heat exchange jacket and/or an inner coil, and steam or heat conducting oil is introduced into the heat exchange jacket and/or the inner coil to control and adjust the dehydration temperature T, so that the control of the temperature gradient of the dehydration pretreatment system from the feed end to the discharge end is realized;

the dewatering pretreatment system is internally provided with a flowmeter quantum system, a temperature detection subsystem and a pressure detection subsystem, and is used for detecting the real-time flow, temperature and pressure of the material at each part;

each dehydration reaction kettle and/or S-grade plate-type dehydration tower connected in series in the dehydration pretreatment system shares a set of condenser, the temperature gradient of the dehydration pretreatment system is gradually increased from the feed end to the discharge end, and each dehydration reaction kettle and/or S-grade plate-type dehydration tower is dehydrated at different dehydration temperature T, but the operation pressure P is the same;

or each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series in the dehydration pretreatment system are respectively provided with a set of independent condensers so as to realize the independent condensation and collection of vapor phases under the conditions of different dehydration temperatures T and operation pressures P; the non-condensable gas output by each condenser is combined and then enters a gas phase washing and purifying system.

In the dehydration pretreatment system, a heat exchanger is arranged between each dehydration reaction kettle and/or S-grade plate-type dehydration tower which are connected in series to exchange heat for materials so as to adjust the temperature of the materials entering the next-stage dehydration reaction kettle or S-grade plate-type dehydration tower.

The feed inlet of the dehydration pretreatment system is connected with a nitrogen tank, and the discharge outlet is connected with a sampling device of a refractometer.

A continuous dehydration pretreatment system for polyarylene sulfide raw material comprising 4 dehydration reaction vessels in FIG. 1 will be described as an example. In this example, the number N of dehydration reactors connected in series was 4, the first reactor was maintained at 120 ℃ and the second reactor was maintained at 145 ℃. The water-containing gas phase of the first kettle and the second kettle directly enters a water treatment system after being condensed. The third vessel was maintained at 170 ℃ and the fourth vessel at 200 ℃. Evaporated gas phases of the third kettle and the fourth kettle are condensed and then enter a solvent recovery system.

The continuous dehydration pretreatment system for the polyarylene sulfide raw material can be carried out in a mode that a dehydration reaction kettle and a plate type dehydration tower are connected in series; firstly, one or more stirring dehydration reaction kettles are connected in series, and then 1 or more perforated plate dehydration towers are connected in series; or 1 or more perforated plate dehydration towers can be connected in series, and then 1 or more stirring dehydration reaction kettles can be connected in series. Whether the multistage kettles are connected in series, the multistage pore plate dehydration towers are connected in series, or the dehydration reaction kettle and the dehydration tower are combined and connected in series, the material temperature in the front-stage dehydration device is relatively low, and the dehydration temperature of the rear-end material is relatively high; the gas phase of each dehydration device can be independently prepared into a gas phase condenser, and can also share one set of gas phase condenser to recover the evaporated water phase and the solvent.

FIG. 3 shows a dehydration system formed by connecting a dehydration reactor and a plate-type dehydration tower in series. In this example, the number of dehydration reaction tanks is N1, and the number of plate dehydration columns is M1. Wherein the temperature of the dehydration reaction kettle is maintained at 140 ℃, the temperature of the plate type dehydration tower is between 150 ℃ and 220 ℃ according to the number of the tower plates, the temperature is flexibly adjusted to realize gradient temperature rise from the tower top to the tower bottom, and if the temperature of the first plate at the tower top is 150 ℃, the temperature of the tower kettle is 220 ℃. The water-containing gas phase of the dehydration reaction kettle directly enters a water treatment system after being condensed, and the evaporated gas phase of the plate-type dehydration tower enters a solvent recovery system after being condensed.

Example 1:

the method comprises the steps of taking sodium hydrosulfide aqueous solution (mass fraction is 45.44%) and sodium hydroxide solution (mass fraction is 50%) as raw materials, adding a catalyst, an auxiliary agent and a solvent, and carrying out dehydration pretreatment on the polyarylene sulfide raw material in 5 dehydration reaction kettles which are mutually connected in series. The air in the system is fully replaced by nitrogen flow, and then the raw materials are metered by a metering pump, and the materials are continuously conveyed into dehydration reaction kettles which are connected in series. The feed rate of the aqueous sodium hydrosulfide solution was 123.4kg/h, the feed rate of the sodium hydroxide solution was 80kg/h, the feed rate of the compounded solvent was 370kg/h, the feed rate of the catalyst was 29.7kg/h, and the feed rate of the auxiliary agent was 16.4 kg/h. Maintaining the temperature of the first dehydration reaction kettle at 80 ℃, and controlling the retention time to be 40 min; the temperature of the second dehydration reaction kettle is 120 ℃, the retention time is controlled to be 40min, the temperature of the third dehydration reaction kettle is 145 ℃, and the retention time is 45 min; the temperature of the fourth dehydration reaction kettle is 170 ℃, and the retention time is 40 min; the temperature of the last stage dehydration reaction kettle is 200 ℃, and the retention time is 60 min. The materials among the dehydration reaction kettles are conveyed by a potential difference natural overflow method to realize the transfer of the materials. The withdrawal rate of the system after dehydration was 511.5 kg/h. The water-containing gas phase evaporated from each dehydration reaction kettle respectively enters a kettle top condenser for collection and separation, and the separated solvent reflows again and enters the reaction system.

Collecting the collected water after the condensation and separation of the water-containing gas phase at the top of the kettle, weighing, measuring the content of the residual solvent in the water through the refractive index, and detecting the sulfur content in the water. And (4) introducing the non-condensable gas condensed at the top of the kettle into a washing and purifying system, and detecting the sulfur content of the non-condensable gas. And recording the sum of the total sulfur content in the dehydrated water and the sulfur content in the non-condensable gas as the total sulfur decomposition amount in the dehydration pretreatment process. The total sulfur decomposition rate was calculated.

The final calculation result is: the dehydration rate is 73.1 percent, the total sulfur decomposition rate is 1.4 percent, and the solvent content in the water collected after the condensation and separation of the water-containing gas phase at the top of the kettle is 0.91 per thousand.

Example 2:

sodium sulfide nonahydrate and sodium hydroxide solution (50%) are used as raw materials, a catalyst, an auxiliary agent and a solvent are added, the dehydration pretreatment of polyarylene sulfide raw materials is carried out in a dehydration device formed by connecting a dehydration reaction kettle and a plate type dehydration tower in series, the number of plates of the plate type dehydration tower is S & lt3 & gt, the materials are fed from the upper side line of the plate type dehydration tower, and the materials are discharged from the bottom of the tower. The air in the system is fully replaced by nitrogen flow, and then the raw materials are metered by a metering pump and continuously conveyed into a dehydration reaction kettle. The feed rate of sodium sulfide nonahydrate was 240kg/h, the feed rate of sodium hydroxide solution was 4kg/h, the feed rate of the compounding solvent was 370kg/h, the feed rate of the catalyst was 29.7kg/h, and the feed rate of the auxiliary was 16.4 kg/h. Maintaining the temperature of the first dehydration reaction kettle at 120 ℃, and controlling the retention time to be 40 min; the temperature of the first tower plate at the top of the plate type dehydration tower is 140 ℃; the temperature of the second tower plate is 160 ℃; the temperature of the third tower plate is 180 ℃, and the temperature of the tower kettle is controlled to be 200 ℃. The materials between the dehydration reaction kettle and the plate-type dehydration tower are conveyed by a potential difference natural overflow method to realize the transfer of the materials. The withdrawal rate of the system after dehydration was 511.5 kg/h. The water-containing gas phase evaporated from the top of the dehydration reaction kettle and the plate-type dehydration tower respectively enters a kettle top and a tower top condenser for collection and separation, and the separated solvent reflows again and enters a reaction system.

Collecting the collected water after condensation and separation of the water-containing gas phase at the top of the kettle and the tower, weighing, measuring the content of the residual solvent in the water through the refractive index, and detecting the sulfur content in the water. And (4) introducing the non-condensable gas condensed at the top of the kettle and the top of the tower into a washing and purifying system, and detecting the sulfur content of the non-condensable gas. And recording the sum of the total sulfur content in the dehydrated water and the sulfur content in the non-condensable gas as the total sulfur decomposition amount in the dehydration pretreatment process. The total sulfur decomposition rate was calculated.

The final calculation result is: the dehydration rate is 76.6 percent, the total sulfur decomposition rate is 0.7 percent, and the content of the solvent in the water collected after the condensation and separation of the water-containing gas phase at the top of the tower and the top of the kettle is 0.77 per mill.

Example 3:

the method comprises the steps of taking a sodium hydrosulfide aqueous solution (mass fraction is 42.23%) and a sodium hydroxide solution (mass fraction is 50%) as raw materials, adding a catalyst, an auxiliary agent and a solvent, and carrying out dehydration pretreatment on the polyarylene sulfide raw material in a series of plate-type dehydration towers, wherein the number of the plates of the plate-type dehydration towers is S-5. The air in the system is fully replaced by nitrogen flow, and then the raw materials are metered by a metering pump and continuously conveyed into the plate type dehydration tower. The feed rate of the aqueous sodium hydrosulfide solution was 398.1kg/h, the feed rate of the sodium hydroxide solution was 240kg/h, the feed rate of the compounded solvent was 1110kg/h, the feed rate of the catalyst was 89.1kg/h, and the feed rate of the auxiliary agent was 49.2 kg/h. The temperature of a first tower plate of the plate type dehydration tower is 100 ℃; the temperature of the second tower plate is 120 ℃; the temperature of the third tower plate is 140 ℃, and the temperature of the fourth tower plate is 160 ℃; the temperature of the fifth tower plate is 180 ℃; the temperature of the tower bottom is controlled to be 200 ℃. The withdrawal rate of the dehydrated system was 1565.4 kg/h. And (3) allowing the water-containing gas phase evaporated from the top of the plate-type dehydrating tower to enter a kettle top condenser for collection and separation, and refluxing the separated solvent again to enter a reaction system.

Collecting the water collected after the condensation and separation of the water-containing gas phase at the tower top, weighing, measuring the content of the residual solvent in the water through the refractive index, and detecting the sulfur content in the water. And (4) the non-condensable gas condensed at the tower top enters a washing and purifying system, and the sulfur content of the non-condensable gas is detected. And recording the sum of the total sulfur content in the dehydrated water and the sulfur content in the non-condensable gas as the total sulfur decomposition amount in the dehydration pretreatment process. The total sulfur decomposition rate was calculated.

The final calculation result is: the dehydration rate is 75.3 percent, the total sulfur decomposition rate is 1.1 percent, and the content of the solvent in the water collected after the condensation and separation of the gas phase containing water at the top of the tower is 0.83 per thousand.

The continuous dehydration pretreatment method of the polyarylene sulfide raw material has the advantages that the dehydration rate of the raw material is completely controllable and stable, the decomposition rate of the sulfur-containing monomer is very low (less than 3%), the concentration of the solvent in the dehydrated condensed water is lower (less than 1 per thousand), and the composition of the dehydrated material is stable, thereby being beneficial to the stability and reliability of the process control in the subsequent polycondensation reaction process; meanwhile, the decomposition loss of the raw materials is reduced, the cost is reduced, and the whole process is more environment-friendly.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.