Chloromethane mixed gas multi-stage treatment device

Abstract

The utility model provides a multi-stage treatment device for chloromethane mixed gas. The multi-stage treatment device comprises a first-stage condenser, a second-stage condenser, a third-stage condenser and a rectifying tower which are communicated in sequence, the top of the rectifying tower is provided with a gas-phase outlet for discharging hydrogen chloride gas, and the bottom of the rectifying tower is provided with a liquid-phase outlet for discharging methane chloride liquid. The device has the beneficial effects that uncondensed HCl gas in the mixed gas is discharged from the top of the separation tank, and is conveyed to a hydrochlorination reaction system after being converged with HCl at the top of the rectifying tower. Through cyclic utilization of HCl, the utilization rate of the chlorine element is increased to 95% or above from 60% of a traditional process, meanwhile, the cost of hydrochloric acid neutralization treatment is reduced, and hydrogen chloride is prevented from circularly entering a reactor.

Description

Technical Field

[0001] This utility model relates to the field of pressure testing equipment technology, specifically to a multi-stage treatment device for chloromethane mixed gas. Background Technology

[0002] Chlorinated methanes are an important class of organic chemicals, mainly including chloromethane (CH3Cl), dichloromethane (CH2Cl2), chloroform (CHCl3), and carbon tetrachloride (CCl4). They are widely used in solvents, refrigerants, foaming agents, pharmaceuticals, and pesticides.

[0003] The common process for producing methane chloride is the direct chlorination process, also known as the thermal chlorination process. The principle is based on the free radical substitution reaction between methane and chlorine under high temperature or light conditions, producing products with different degrees of chlorination. In existing methane chlorination processes, the mixed gas exiting the reactor contains approximately 38% hydrogen chloride. This hydrogen chloride, as a reaction product of the thermal chlorination reaction, returns to the reactor, inhibiting the reaction. Simultaneously, this portion of hydrogen chloride circulates as an inert gas into the condenser, lowering the partial pressure and condensation temperature of the organic matter. This reduces the heat exchanger's temperature difference, making condensation of the organic matter more difficult and requiring a larger heat exchange area for the same condensation load. Furthermore, this circulating hydrogen chloride into the reactor reduces the reaction intensity per unit cross-sectional area, lowering the reactor temperature and impacting the reactor's production capacity. Utility Model Content

[0004] The purpose of this invention is to solve the problem of hydrogen chloride recycling into the reactor in the prior art;

[0005] A multi-stage treatment device for chloromethane mixture is provided, comprising a primary condenser, a secondary condenser, a tertiary condenser and a distillation column connected in sequence. The cooling medium of the primary condenser is cooling water, the cooling medium of the secondary condenser is circulating water in the reactor, and the cooling medium of the tertiary condenser is Freon.

[0006] The first-stage condenser is equipped with a chloromethane mixed gas inlet pipe. A first-stage separator for collecting liquid trichloromethane is installed between the first-stage and second-stage condensers. A second-stage separator for collecting liquid dichloromethane is installed between the second-stage and third-stage condensers. A third-stage separator for collecting liquid monochloromethane is installed between the third-stage condenser and the distillation column.

[0007] The distillation column has a gas outlet at the top to discharge hydrogen chloride gas, and a liquid outlet at the bottom to discharge chloromethane liquid.

[0008] As a preferred embodiment, the three-stage separator is equipped with an exhaust pipe at the top to discharge hydrogen chloride gas, and a drain pipe at the bottom to connect to the feed trough, which is connected to the feed pipe of the distillation column. The drain pipe is equipped with a feed pump for the distillation column.

[0009] As a preferred embodiment, the liquid phase outlet pipe of the distillation column is connected to a secondary condenser, with chloromethane liquid used as the cooling medium for the secondary condenser, and a bottom delivery pump is installed on the liquid phase outlet pipe of the distillation column.

[0010] As a preferred embodiment, the distillation column is equipped with a reboiler.

[0011] As a preferred option, the distillation column uses DN25 Pall ring random packing.

[0012] As a preferred embodiment, the gas phase outlet of the distillation column is connected to a hydrochlorination system.

[0013] The beneficial effects of this utility model are as follows:

[0014] 1. This utility model utilizes a stepped condensation design to precisely match the boiling points of different chloromethanes, achieving step-by-step separation of the mixed gas. Through boiling point descending condensation, the traditional "full-component liquefaction-re-distillation" mode of a single condenser is optimized into "step-by-step separation," allowing the distillation column to process only a small amount of residual components, reducing energy consumption by more than 40%, and increasing product purity to over 99.5%.

[0015] 2. In this invention, the monochloromethane liquid (temperature approximately -15°C) at the bottom of the distillation column is directly introduced into the secondary condenser via a bottom pump, replacing part of the cooling water as the cooling medium. The low-temperature characteristics of monochloromethane enhance the refrigeration efficiency of the secondary condenser. Simultaneously, it absorbs heat and vaporizes, returning to the distillation column for re-separation, forming a closed-loop cold energy utilization, reducing external refrigeration energy consumption by more than 30%.

[0016] 3. This invention discharges uncondensed HCl gas from the mixed gas at the top of the separator, where it merges with HCl from the top of the distillation column and is then transported to the hydrochlorination reaction system. Through the recycling of HCl, the utilization rate of chlorine is increased from 60% in the traditional process to over 95%, while simultaneously reducing the cost of hydrochloric acid neutralization and preventing hydrogen chloride from circulating into the reactor. Attached Figure Description

[0017] To make the content of this utility model easier to understand, the present utility model will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0018] Figure 1 This is a schematic diagram of the structure of this utility model.

[0019] The numbers in the attached diagram are:

[0020] 1. Primary condenser; 2. Secondary condenser; 3. Tertiary condenser; 4. Primary separator; 5. Secondary separator; 6. Tertiary separator; 7. Heat exchanger feed trough; 8. Distillation column; 9. Reboiler; 10. Distillation column bottom transfer pump; 11. Distillation column feed pump. Detailed Implementation

[0021] To illustrate the features of this utility model, the following description, in conjunction with the accompanying drawings and embodiments, will further explain this utility model.

[0022] Example:

[0023] Please see Figure 1 This utility model provides a multi-stage treatment device for chloromethane mixed gas, including a first-stage condenser 1, a second-stage condenser 2, a third-stage condenser 3 and a distillation column 8 connected in sequence. The cooling medium of the first-stage condenser 1 is cooling water, the cooling medium of the second-stage condenser 2 is circulating water in the reactor liquid, and the cooling medium of the third-stage condenser 3 is Freon.

[0024] The first-stage condenser 1 is equipped with a chloromethane mixed gas inlet pipe. A first-stage separator 4 for collecting liquid trichloromethane is installed between the first-stage condenser 1 and the second-stage condenser 2. A second-stage separator 5 for collecting liquid dichloromethane is installed between the second-stage condenser 2 and the third-stage condenser 3. A third-stage separator 6 for collecting liquid monochloromethane is installed between the third-stage condenser 3 and the distillation column 8.

[0025] The top of the distillation column 8 is equipped with a gas phase outlet to discharge hydrogen chloride gas, and the bottom of the distillation column 8 is equipped with a liquid phase outlet to discharge chloromethane liquid.

[0026] Preferably, in this embodiment, the three-stage separator 6 is provided with an exhaust pipe at the top to discharge hydrogen chloride gas, and a drain pipe at the bottom to connect to the feed trough 7. The feed trough 7 is connected to the feed pipe of the distillation column 8, and the drain pipe is equipped with a distillation column feed pump 11.

[0027] Preferably, in this embodiment, the liquid phase outlet pipe of the distillation column 8 is connected to the secondary condenser 2, and chloromethane liquid is used as the cooling medium of the secondary condenser 2. The liquid phase outlet pipe of the distillation column 8 is equipped with a distillation column bottom transfer pump 10.

[0028] Preferably, the distillation column 8 in this embodiment is equipped with a reboiler 9.

[0029] Preferably, the distillation column 8 described in this embodiment uses DN25 Pall ring random packing.

[0030] Preferably, the gas phase outlet of the distillation column 8 in this embodiment is connected to a hydrogen chlorination system.

[0031] The above embodiments and accompanying drawings are only used to illustrate the technical solutions of this utility model and are not intended to limit this utility model. This utility model has been described in detail with reference to preferred embodiments. Those skilled in the art should understand that any changes, modifications, additions, or substitutions made by those skilled in the art within the scope of this utility model do not depart from the spirit of this utility model and should also fall within the protection scope of the claims of this utility model. Other related technical structures not disclosed in detail in this utility model are existing technologies in the art.

Claims

1. A multi-stage treatment device for a chloromethane mixture, characterized in that: It includes a first-stage condenser (1), a second-stage condenser (2), a third-stage condenser (3) and a distillation column (8) connected in sequence. The cooling medium of the first-stage condenser (1) is cooling water, the cooling medium of the second-stage condenser (2) is circulating water from the bottom liquid, and the cooling medium of the third-stage condenser (3) is Freon. The first-stage condenser (1) is equipped with a chloromethane mixed gas inlet pipe. A first-stage separator (4) for collecting liquid trichloromethane is set between the first-stage condenser (1) and the second-stage condenser (2). A second-stage separator (5) for collecting liquid dichloromethane is set between the second-stage condenser (2) and the third-stage condenser (3). A third-stage separator (6) for collecting liquid monochloromethane is set between the third-stage condenser (3) and the distillation column (8). The distillation column (8) is equipped with a gas phase outlet at the top to discharge hydrogen chloride gas, and a liquid phase outlet at the bottom to discharge chloromethane liquid.

2. The multi-stage treatment device for chloromethane mixture according to claim 1, characterized in that: The three-stage separation tank (6) is equipped with an exhaust pipe at the top to discharge hydrogen chloride gas, and a drain pipe at the bottom to connect to the feed tank (7). The feed tank (7) is connected to the feed pipe of the distillation column (8), and the drain pipe is equipped with a distillation column feed pump (11).

3. The multi-stage treatment device for chloromethane mixed gas according to claim 1, characterized in that: The liquid phase outlet pipe of the distillation column (8) is connected to the secondary condenser (2), and chloromethane liquid is used as the cold medium of the secondary condenser (2). The bottom delivery pump (10) of the distillation column (8) is installed on the liquid phase outlet pipe of the distillation column (8).

4. The multi-stage treatment device for chloromethane mixture according to claim 1, characterized in that: The distillation column (8) is equipped with a reboiler (9).

5. The multi-stage treatment device for chloromethane mixture according to claim 4, characterized in that: The distillation column (8) uses DN25 Pall ring random packing.

6. The multi-stage treatment device for chloromethane mixture according to claim 1, characterized in that: The gas phase outlet of the distillation column (8) is connected to the hydrogen chlorination system.

Images