阅读说明：本技术 催化剂循环脱水的氯甲烷合成工艺 (Methyl chloride synthesis process for cyclic dehydration of catalyst ) 是由 尚剑 曹锐建 李佳 陈维平 骆彩萍 于 2020-07-28 设计创作，主要内容包括：本发明公开了一种催化剂循环脱水的氯甲烷合成工艺。氯化氢与甲醇在氯甲烷反应器反应生成氯甲烷及水,催化剂与水从氯甲烷反应器底部排出进入催化剂脱水罐,经换热器加热后,水分气化离开系统,催化剂经催化剂循环泵返回至氯甲烷反应器。与现有工艺相比,本发明所述工艺通过催化剂脱水避免了氯甲烷合成中大量稀盐酸的产生,通过对催化剂溶液循环量及脱水率的调控,从而精确调节反应器内催化剂浓度。同时,催化剂与气相原料逆向流动提高了反应速率。(The invention discloses a chloromethane synthesis process for circularly dehydrating a catalyst. The hydrogen chloride and the methanol react in the methyl chloride reactor to generate methyl chloride and water, the catalyst and the water are discharged from the bottom of the methyl chloride reactor and enter a catalyst dehydration tank, after being heated by a heat exchanger, the water is gasified and leaves the system, and the catalyst returns to the methyl chloride reactor through a catalyst circulating pump. Compared with the prior art, the process avoids the generation of a large amount of dilute hydrochloric acid in methyl chloride synthesis through catalyst dehydration, and accurately adjusts the concentration of the catalyst in the reactor through regulating and controlling the circulation volume and the dehydration rate of the catalyst solution. Meanwhile, the catalyst and the gas phase raw material flow reversely, so that the reaction rate is improved.)

1. A chloromethane synthesis process for circularly dehydrating a catalyst is characterized by comprising the following steps:

(1) heating and mixing reaction raw materials of hydrogen chloride and methanol gas, then feeding the mixture into the bottom of a methyl chloride reactor, and uniformly distributing the mixture by a gas distributor and then flowing from bottom to top; feeding the concentrated catalyst solution into the top of a methyl chloride reactor, and enabling the concentrated catalyst solution to flow from top to bottom; gas-liquid two-phase flow is in reverse direction and fully contacted to react to generate methyl chloride and water;

(2) unreacted hydrogen chloride and a reaction product methyl chloride are discharged from the top of a methyl chloride reactor, and water generated by the reaction is discharged from the bottom of the methyl chloride reactor along with a catalyst solution and enters a catalyst dehydration tank, so that the hydrogen chloride and the water are discharged in a gas phase and a liquid phase respectively, and the generation of a large amount of dilute hydrochloric acid is fundamentally avoided;

(3) heating the dilute catalyst solution in a heat exchanger mode before or after entering a dehydration tank, wherein water is evaporated and discharged from the top, the dilute catalyst solution is changed into a concentrated catalyst solution, the concentration of the concentrated catalyst generated after dehydration is 60-98 wt%, and the temperature is 80-280 ℃;

(4) conveying the dehydrated catalyst solution to a methyl chloride reactor by a catalyst circulating pump, and reacting the catalyst with hydrogen chloride and methanol newly entering the methyl chloride reactor to complete the circulation of the catalyst; the concentration of the catalyst solution in the catalyst can be well controlled by regulating and controlling the dehydration temperature of the catalyst solution and the circulation volume of the catalyst solution, so that the reaction efficiency is accurately controlled.

2. A methyl chloride synthesis process for circularly dehydrating a catalyst is characterized by comprising the following steps:

(1) heating and mixing reaction raw materials of hydrogen chloride and methanol gas, then feeding the mixture into the bottom of a methyl chloride reactor, and uniformly distributing the mixture by a gas distributor and then flowing from bottom to top; feeding the concentrated catalyst solution into the top of a methyl chloride reactor, and enabling the concentrated catalyst solution to flow from top to bottom; gas-liquid two-phase flow is in reverse direction and fully contacted to react to generate methyl chloride and water;

(2) unreacted hydrogen chloride and a reaction product methyl chloride are discharged from the top of a methyl chloride reactor, and water generated by the reaction is discharged from the bottom of the methyl chloride reactor along with a catalyst solution and enters a heat exchanger, so that the hydrogen chloride and the water are discharged in a gas phase and a liquid phase respectively, and the generation of a large amount of dilute hydrochloric acid is fundamentally avoided;

(3) heating the dilute catalyst solution in a heat exchanger, wherein water is evaporated, discharging after separation, changing the dilute catalyst solution into a concentrated catalyst solution, and controlling the concentration of the concentrated catalyst generated after dehydration to be 60-98 wt% and the temperature to be 80-280 ℃;

(4) the dehydrated catalyst solution is sent to a methyl chloride reactor, and the catalyst reacts with hydrogen chloride and methanol which newly enter the methyl chloride reactor to complete the circulation of the catalyst; the concentration of the catalyst solution in the catalyst can be well controlled by regulating and controlling the dehydration temperature of the catalyst solution and the circulation volume of the catalyst solution, so that the reaction efficiency is accurately controlled.

3. The methyl chloride synthesis process with catalyst cycle dehydration according to claims 1 and 2, characterized in that: the water and the catalyst solution generated in the synthesis reaction are discharged from the bottom of the methyl chloride reactor, and the methyl chloride gas generated in the synthesis reaction and the unreacted hydrogen chloride gas are discharged from the top of the methyl chloride reactor.

4. The methyl chloride synthesis process with catalyst cycle dehydration according to claims 1 and 2, characterized in that: the catalyst, hydrogen chloride and methanol gas are contacted in a methyl chloride reactor to generate methyl chloride synthesis reaction, and methyl chloride gas and water are generated, wherein the reaction temperature is 80-250 ℃, and the reaction pressure is-0.1-3.0 MPaG.

5. The methyl chloride synthesis process with catalyst cycle dehydration according to claims 1 and 2, characterized in that: the heating heat exchanger is in the form of falling film type, rising film type, thermal siphon type, inner jacket, outer jacket, inserted heat exchange tube and catalyst dewatering tank combination.

Technical Field

The invention belongs to the field of methyl chloride synthesis, and particularly relates to a methyl chloride synthesis process for circularly dehydrating a catalyst.

Background

Methyl chloride is an important raw material for silicone, methyl cellulose and quaternary ammonium compound products. Currently, methyl chloride synthesis methods include a methane chlorination method and a methanol hydrogen oxidation method. The principle of the methanol hydrogen oxidation method is that methanol reacts with hydrogen chloride to produce methyl chloride and water, and the method has industrial feasibility. The methanol hydrogen oxidation method can be divided into a gas-liquid non-catalytic process, a gas-solid catalytic process and a gas-liquid catalytic process which is widely applied. The gas-liquid catalysis process has mild reaction condition and high selectivity. The reaction equation is as follows:

hydrogen chloride + methanol (methyl chloride + water)

Gas-liquid catalytic processes have three significant disadvantages in industrial production. Firstly, the reaction product water is separated from the reaction system along with the gas phase and condensed to form a large amount of low-concentration hydrochloric acid. The treatment process of the low-concentration hydrochloric acid is complex, and the investment and the energy consumption are high; secondly, the proportion of the catalyst and water in the catalyst aqueous solution is determined by the exhaust composition of the reactor, and the concentration of the catalyst and water cannot be independently regulated and controlled, so that the catalytic efficiency is influenced; thirdly, the catalyst solution is added into the reactor, gas-liquid contact is formed by bubbling of raw material gas, and the insufficient gas-liquid contact surface seriously restricts the production capacity and the industrialized scale of single equipment.

CN209010413U provides a methyl chloride synthesis process with two reaction kettles connected in series, wherein crude methyl chloride gas in a first reaction kettle is compressed by a compressor and sent to a second reaction kettle. The addition of a compressor increases the complexity of the system and the investment costs.

CN209555111U provides methyl chloride synthesis equipment without by-product hydrochloric acid. The problem that the wastewater in the pure water separator contains low-concentration hydrochloric acid cannot be avoided because the hydrochloric acid aqueous solution has an azeotropic phenomenon. The treatment of the salt-containing wastewater formed by the neutralization unit in the process is also a great problem in the chemical process.

Disclosure of Invention

The invention aims to provide a chloromethane synthesis process with catalyst cyclic dehydration, which fundamentally avoids the problems that a large amount of dilute hydrochloric acid is generated by mixing hydrogen chloride and water in chloromethane synthesis and the subsequent separation is difficult by a catalyst cyclic dehydration method.

The technical scheme of the invention is that the chloromethane synthesis process for circularly dehydrating the catalyst is characterized by comprising the following steps of:

1. heating and mixing reaction raw materials of hydrogen chloride and methanol gas, then feeding the mixture into the bottom of a methyl chloride reactor, and uniformly distributing the mixture by a gas distributor and then flowing from bottom to top; sending the concentrated catalyst solution into the top of a methyl chloride reactor, and distributing the concentrated catalyst solution by a liquid distributor to flow from top to bottom; the gas phase and the liquid phase flow reversely and fully contact with each other to react to generate methyl chloride and water. The reaction temperature is 80-280 ℃, and the reaction pressure is-0.1-3.0 MPaG.

2. Due to the water absorption of the concentrated catalyst solution and the same ion effect of chloride ions, unreacted hydrogen chloride and a reaction product methyl chloride are discharged from the top of the reactor, and water generated by the reaction is discharged from the bottom of the reactor along with the catalyst solution and enters a catalyst dehydration tank. Thus, the hydrogen chloride and the water are discharged in a gas phase and a liquid phase respectively, and the generation of a large amount of dilute hydrochloric acid is fundamentally avoided.

3. The dilute catalyst solution is heated before entering the dehydration tank or after entering the de-cargo tank, wherein the water evaporates and is discharged from the top, the dilute catalyst solution becoming a concentrated catalyst solution. The bubble point of the catalyst solution is greatly increased after the concentration of the catalyst solution is increased, so the advantages of heating before entering the tank are that the heat transfer temperature difference is large, the energy can be effectively utilized, and the solution is not back-mixed. The advantage of heating in the form of a heat exchanger after entering the tank is that the material circulates in the heat exchanger in a large amount, the single gasification rate is small, the heat transfer coefficient is large, the dehydration speed is easy to control, and the heat exchanger is not easy to scale. The viscosity of the catalyst solution rises along with the rise of the concentration, and the catalyst solution is easy to crystallize or scale, so that the falling film type, the rising film type and the thermal siphon type are better in applicability compared with a jacket heating mode. In the invention, an appropriate scheme is selected according to the conditions of production scale, industry and the like. The concentration of the concentrated catalyst generated after dehydration is 60-98 wt%, and the temperature is 80-280 ℃.

4. The dehydrated catalyst solution is conveyed to a methyl chloride reactor by a catalyst circulating pump, and the catalyst reacts with hydrogen chloride and methanol which newly enter the reactor to complete the circulation of the catalyst. The concentration of the catalyst solution in the catalyst can be well controlled by regulating and controlling the dehydration temperature of the catalyst solution and the circulation volume of the catalyst solution, so that the reaction efficiency is accurately controlled.

A methyl chloride synthesis process for circularly dehydrating a catalyst is characterized by comprising the following steps:

(1) heating and mixing reaction raw materials of hydrogen chloride and methanol gas, then feeding the mixture into the bottom of a methyl chloride reactor, and uniformly distributing the mixture by a gas distributor and then flowing from bottom to top; feeding the concentrated catalyst solution into the top of a methyl chloride reactor, and enabling the concentrated catalyst solution to flow from top to bottom; gas-liquid two-phase flow is in reverse direction and fully contacted to react to generate methyl chloride and water;

(2) unreacted hydrogen chloride and a reaction product methyl chloride are discharged from the top of a methyl chloride reactor, and water generated by the reaction is discharged from the bottom of the methyl chloride reactor along with a catalyst solution and enters a heat exchanger, so that the hydrogen chloride and the water are discharged in a gas phase and a liquid phase respectively, and the generation of a large amount of dilute hydrochloric acid is fundamentally avoided;

(3) heating the dilute catalyst solution in a heat exchanger, wherein water is evaporated, discharging after separation, changing the dilute catalyst solution into a concentrated catalyst solution, and controlling the concentration of the concentrated catalyst generated after dehydration to be 60-98 wt% and the temperature to be 80-280 ℃;

(4) the dehydrated catalyst solution is sent to a methyl chloride reactor, and the catalyst reacts with hydrogen chloride and methanol which newly enter the methyl chloride reactor to complete the circulation of the catalyst; the concentration of the catalyst solution in the catalyst can be well controlled by regulating and controlling the dehydration temperature of the catalyst solution and the circulation volume of the catalyst solution, so that the reaction efficiency is accurately controlled.

According to the invention, the concentration of the catalyst in the reactor is accurately regulated and controlled through the circulation quantity of the catalyst aqueous solution and the dehydration temperature of the catalyst aqueous solution, so that the reaction efficiency and the reaction controllability are improved. Meanwhile, the invention solves the problems of insufficient contact between the catalyst and the reaction raw materials and large-scale synthesis of the chloromethane in a mode of reverse contact reaction with upward gas phase and downward liquid phase.

Drawings

FIG. 1 is a diagram of a synthesis process of methyl chloride by cyclic dehydration of a catalyst.

FIG. 2 is a second diagram of a process for synthesizing methyl chloride by circularly dehydrating a catalyst.

FIG. 3 is a diagram of a process for the synthesis of methyl chloride by cyclic dehydration of a catalyst using a climbing-film heat exchanger.

FIG. 4 is a diagram of a process for the synthesis of methyl chloride by cyclic dehydration of a catalyst using a falling film heat exchanger.

Wherein: a chloromethane reactor (R-1), a catalyst dehydration tank (V-1), a heat exchanger (E-1), a climbing film heat exchanger (E-2), a falling film heat exchanger (E-3), a catalyst circulating pump (P-1), a catalyst solution dehydration circulating pump (P-2)

Detailed Description

The process operating characteristics to which the present invention relates are further explained below.

As shown in fig. 1, the process of the present invention is as follows:

1. the reaction raw materials of hydrogen chloride and methanol gas are heated and mixed, then are sent to the bottom of a chloromethane reactor (R-1), and flow from bottom to top after being uniformly distributed by a gas distributor; sending the concentrated catalyst solution into the top of a methyl chloride reactor (R-1), and distributing the concentrated catalyst solution by a liquid distributor to flow from top to bottom; the gas phase and the liquid phase flow reversely and fully contact with each other to react to generate methyl chloride and water. The reaction temperature is 80-250 ℃, and the reaction pressure is-0.1-3.0 MPaG.

2. Due to the water absorption of the concentrated catalyst solution and the co-ion effect of chloride ions, unreacted hydrogen chloride and the reaction product methyl chloride are discharged from the top of the methyl chloride reactor (R-1), and water generated by the reaction is discharged from the bottom of the methyl chloride reactor (R-1) along with the catalyst solution and enters a catalyst dehydration tank (V-1). Thus, the hydrogen chloride and the water are discharged in a gas phase and a liquid phase respectively, and the generation of a large amount of dilute hydrochloric acid is fundamentally avoided.

3. The dilute catalyst solution is heated before entering the catalyst dehydration tank (V-1) or after entering the de-cargo tank, wherein the water is evaporated and discharged from the top, the dilute catalyst solution becomes a concentrated catalyst solution. The bubble point of the catalyst solution is greatly increased after the concentration of the catalyst solution is increased, so the advantages of heating before entering the tank are that the heat transfer temperature difference is large, the energy can be effectively utilized, and the solution is not back-mixed. The advantage of heating in the form of the heat exchanger (E-1) after entering the tank is that the material circulates in the heat exchanger in a large amount, the single gasification rate is small, the heat transfer coefficient is large, the dehydration speed is easy to control, and the heat exchanger is not easy to scale. The viscosity of the catalyst solution rises along with the rise of the concentration, and the catalyst solution is easy to crystallize or scale, so that the falling film type, the rising film type and the thermal siphon type are better in applicability compared with a jacket heating mode. In the invention, an appropriate scheme is selected according to the conditions of production scale, industry and the like. The concentration of the concentrated catalyst generated after dehydration is 60-98 wt%, and the temperature is 90-280 ℃.

4. The dehydrated catalyst solution is conveyed to a methyl chloride reactor (R-1) by a catalyst circulating pump (P-1), and the catalyst reacts with hydrogen chloride and methanol which newly enter the reactor to complete the circulation of the catalyst. The concentration of the catalyst solution in the catalyst can be well controlled by regulating and controlling the dehydration temperature of the catalyst solution and the circulation volume of the catalyst solution, so that the reaction efficiency is accurately controlled.

As shown in fig. 2, the process of the present invention can also be used in the following manner:

(1) heating and mixing reaction raw materials of hydrogen chloride and methanol gas, then feeding the mixture into the bottom of a methyl chloride reactor, and uniformly distributing the mixture by a gas distributor and then flowing from bottom to top; sending the concentrated catalyst solution into the top of a methyl chloride reactor, and distributing the concentrated catalyst solution by a liquid distributor to flow from top to bottom; gas-liquid two-phase flow is in reverse direction and fully contacted to react to generate methyl chloride and water;

(2) unreacted hydrogen chloride and a reaction product methyl chloride are discharged from the top of a methyl chloride reactor, and water generated by the reaction is discharged from the bottom of the methyl chloride reactor along with a catalyst solution and enters a heat exchanger, so that the hydrogen chloride and the water are discharged in a gas phase and a liquid phase respectively, and the generation of a large amount of dilute hydrochloric acid is fundamentally avoided;

(3) heating the dilute catalyst solution in a heat exchanger, wherein water is evaporated, discharging after separation, changing the dilute catalyst solution into a concentrated catalyst solution, and controlling the concentration of the concentrated catalyst generated after dehydration to be 70-98 wt% and the temperature to be 90-280 ℃;

(4) the dehydrated catalyst solution is sent to a methyl chloride reactor, and the catalyst reacts with hydrogen chloride and methanol which newly enter the methyl chloride reactor to complete the circulation of the catalyst; the concentration of the catalyst solution in the catalyst can be well controlled by regulating and controlling the dehydration temperature of the catalyst solution and the circulation volume of the catalyst solution, so that the reaction efficiency is accurately controlled.

As shown in fig. 3, the process of the present invention can also be used as follows:

1. hydrogen chloride gas was fed from the outside at a rate of 15312kg/h and methanol from the outside at a rate of 12807kg/h to a gas distributor at the bottom of the methyl chloride reactor (R-1).

2. The dehydrated catalyst is sent to the top of a methyl chloride reactor (R-1) and then sequentially falls into 8 layers of gas-liquid reaction disks after passing through a trough-disk type liquid distributor.

3. Methanol and hydrogen chloride continuously flow upwards in a methyl chloride reactor (R-1) and continuously react to generate methyl chloride and water. When the gas phase reaches the top of the methyl chloride reactor (R-1), the methanol is almost completely reacted, the hydrogen chloride gas is slightly remained, and the concentration of the methyl chloride reaches the highest. The catalyst flows from top to bottom, continuously catalyzes the reaction and absorbs the water of the reaction product to reach the bottom of the chloromethane reactor (R-1).

4. The dilute catalyst solution automatically flows into a catalyst dehydration tank (V-1) and is sent to a rising film heat exchanger (E-2) by a catalyst solution dehydration circulating pump (P-2). The catalyst solution flows from bottom to top in the climbing film heat exchanger (E-2), is continuously gasified after being heated by steam, and finally circularly enters the catalyst dehydration tank (V-1) for gas-liquid separation. The gas phase mainly composed of water is discharged from the top of the catalyst dehydration tank (V-1), the concentrated catalyst is discharged from the bottom of the dehydration tank (V-1), and part of the catalyst exists in a crystallized form.

5. The catalyst circulating pump (P-1) conveys the concentrated catalyst water solution to the methyl chloride reactor (R-1) to complete the circulating dehydration process of the catalyst.

Compared with the traditional process, the synthesis of the methyl chloride is realized by adopting the methyl chloride synthesis process with the catalyst circularly dehydrated, and the yield of the dilute hydrochloric acid is reduced by 96.95 percent. The concentration of the catalyst in the methyl chloride reactor and the gas-liquid contact strength are improved, the reaction efficiency and controllability are improved, and the reaction efficiency of unit volume is improved by 31.52%.

As shown in fig. 4, the process of the present invention can also be used as follows:

1. hydrogen chloride gas was fed from the outside at a rate of 1167kg/h and methanol from the outside at a rate of 896kg/h to a gas distributor at the bottom of the methyl chloride reactor (R-1).

2. The dehydrated catalyst is sent to the top of a methyl chloride reactor (R-1) and sequentially falls into 5 layers of gas-liquid reaction disks after passing through a perforated disk type liquid distributor.

3. Methanol and hydrogen chloride continuously flow upwards in a methyl chloride reactor (R-1) and continuously react to generate methyl chloride and water. When the gas phase reaches the top of the methyl chloride reactor (R-1), the methanol is almost completely reacted, the hydrogen chloride gas is slightly remained, and the concentration of the methyl chloride reaches the highest. The catalyst flows from top to bottom, continuously catalyzes the reaction and absorbs the water of the reaction product to reach the bottom of the chloromethane reactor (R-1).

4. The dilute catalyst solution automatically flows into a catalyst dehydration tank (V-1) and is sent to a falling film heat exchanger (E-3) by a catalyst solution dehydration circulating pump (P-2). The dilute catalyst solution flows from top to bottom in the falling film heat exchanger (E-3), is continuously gasified after being heated by steam, and finally circularly enters the catalyst dehydration tank (V-1) for gas-liquid separation. The gas phase mainly composed of water is discharged from the top of the catalyst dehydration tank (V-1), the concentrated catalyst is discharged from the bottom of the catalyst dehydration tank (V-1), and at this time, part of the catalyst exists in a crystallized form.

5. The catalyst circulating pump (P-1) conveys the concentrated catalyst solution to the methyl chloride reactor (R-1) to complete the circulating dehydration process of the catalyst.

Compared with the prior art, the methyl chloride synthesis process adopting the catalyst for cyclic dehydration realizes the synthesis of methyl chloride, and the yield of dilute hydrochloric acid is reduced by 93.27%. The concentration of the catalyst in the methyl chloride reactor and the gas-liquid contact strength are improved, the reaction efficiency and controllability are improved, and the reaction efficiency of unit volume is improved by 22.72 percent.