Separation system and separation method of methane chloride crude product

Abstract

The invention provides a separation system and a separation method of a methane chloride crude product. The separation system of the methane chloride crude product comprises a low-pressure dichloromethane tower, a high-pressure dichloromethane tower, a low-pressure trichloromethane tower, a high-pressure trichloromethane tower, a low-pressure dichloromethane reboiler, a low-pressure trichloromethane reboiler and a high-pressure trichloromethane reboiler, the low-pressure dichloromethane tower is provided with a methane chloride crude product inlet and a dichloromethane outlet, the high-pressure dichloromethane tower is provided with a dichloromethane outlet, the low-pressure trichloromethane tower is provided with a trichloromethane outlet, and the high-pressure trichloromethane tower is provided with a trichloromethane outlet; a dichloromethane outlet of the high-pressure dichloromethane tower is communicated with the high-pressure trichloromethane reboiler, a trichloromethane outlet of the high-pressure trichloromethane tower is communicated with the low-pressure dichloromethane reboiler, and a dichloromethane outlet of the low-pressure dichloromethane tower is communicated with the low-pressure trichloromethane reboiler.

Description

Technical Field

[0001] This invention relates to a separation system and method for crude methane chloride products, belonging to the field of chemical separation technology. Background Technology

[0002] Chlorinated methane (such as dichloromethane, trichloromethane, and carbon tetrachloride) is an important organic solvent and intermediate in chemical production, widely used in electronic cleaning, pharmaceutical synthesis, refrigerant manufacturing, and plastic foaming. In industrial production, chlorinated methane typically produces crude products through chlorination reactions, containing various chloride components. These crude products require distillation to obtain high-purity products to meet downstream application demands. Distillation is the core step in chlorinated methane production, consuming over 40% of the total energy. Traditional distillation processes employ a linear sequence operation, where the crude product sequentially enters a dichloromethane column and then a trichloromethane column for separation, ultimately yielding the target product. However, this process has significant drawbacks: the distillation columns must operate independently, the heat of vapor condensation at the top of the columns is not effectively recovered, and the reboiler relies on external steam heating, resulting in severe energy waste. Under the "dual carbon" goals and the trend towards green chemistry, how to achieve efficient energy integration and cascade utilization through equipment structure optimization and process reconfiguration has become a pressing technical challenge in the field of chlorinated methane refining. Summary of the Invention

[0003] This invention provides a separation system for crude methane chloride products, which is both energy-efficient and economical.

[0004] This invention provides a method for separating crude methane chloride products using the above-mentioned separation system, which is both energy-saving and economical.

[0005] This invention provides a separation system for crude methane chloride, comprising: a low-pressure dichloromethane tower, a high-pressure dichloromethane tower, a low-pressure trichloromethane tower, a high-pressure trichloromethane tower, a low-pressure dichloromethane reboiler, a low-pressure trichloromethane reboiler, and a high-pressure trichloromethane reboiler.

[0006] The low-pressure dichloromethane tower has a crude methane chloride inlet and a dichloromethane outlet; the high-pressure dichloromethane tower has a dichloromethane outlet; the low-pressure trichloromethane tower has a trichloromethane outlet; and the high-pressure trichloromethane tower has a trichloromethane outlet.

[0007] The dichloromethane outlet of the high-pressure dichloromethane tower is connected to the high-pressure trichloromethane reboiler, the trichloromethane outlet of the high-pressure trichloromethane tower is connected to the low-pressure dichloromethane reboiler, and the dichloromethane outlet of the low-pressure dichloromethane tower is connected to the low-pressure trichloromethane reboiler.

[0008] In the separation system described above, the operating pressure of the high-pressure dichloromethane tower is 0.4~1 MPaG; and / or,

[0009] The operating pressure of the low-pressure trichloromethane tower is -0.07 to -0.01 MPaG.

[0010] In the separation system described above, the high-pressure dichloromethane tower has a crude methane chloride product inlet, the bottom outlet of the low-pressure dichloromethane tower is connected to the feed inlet of the low-pressure trichloromethane tower, the bottom outlet of the high-pressure dichloromethane tower is connected to the feed inlet of the low-pressure trichloromethane tower, and the bottom outlet of the low-pressure trichloromethane tower is connected to the feed inlet of the high-pressure trichloromethane tower.

[0011] The separation system described above also includes a trichloride compressor and a trichloride cooler;

[0012] The chloroform outlet of the high-pressure chloroform tower is connected to the inlet of the chloroform compressor, the outlet of the chloroform compressor is connected to the inlet of the low-pressure dichloroform reboiler, the outlet of the low-pressure dichloroform reboiler is connected to the inlet of the chloroform cooler, and the outlet of the chloroform cooler is connected to the top inlet of the high-pressure chloroform tower.

[0013] The separation system described above also includes a dichloride cooler;

[0014] The dichloromethane outlet of the low-pressure dichloromethane tower is connected to the inlet of the dichloromethane cooler;

[0015] The outlet of the high-pressure trichlororeboiler is connected to the top inlet of the high-pressure dichloromethane tower, and the outlet of the high-pressure trichlororeboiler is connected to the outlet of the dichlorocooler.

[0016] In the separation system described above, the bottom outlet of the low-pressure dichloromethane tower is connected to the feed inlet of the high-pressure dichloromethane tower, the bottom outlet of the high-pressure dichloromethane tower is connected to the feed inlet of the low-pressure trichloromethane tower, the bottom outlet of the low-pressure trichloromethane tower is connected to the feed inlet of the high-pressure trichloromethane tower, the top of the low-pressure trichloromethane tower has a trichloromethane outlet, and the high-pressure trichloromethane tower has a trichloromethane outlet.

[0017] The separation system described above further includes a dichloride compressor and a dichloride cooler;

[0018] The top outlet of the low-pressure dichloromethane tower is connected to the inlet of the dichloromethane compressor, the outlet of the dichloromethane compressor is connected to the inlet of the low-pressure trichloromethane reboiler, the outlet of the low-pressure trichloromethane reboiler is connected to the inlet of the dichloromethane cooler, and the outlet of the dichloromethane cooler is connected to the top inlet of the low-pressure dichloromethane tower.

[0019] In the separation system described above, the outlet of the high-pressure trichlororeboiler is connected to the top inlet of the high-pressure dichloromethane tower.

[0020] In the separation system described above, the outlet of the low-pressure dichloro reboiler is connected to the top inlet of the high-pressure trichloromethane tower.

[0021] The present invention also provides a method for separating crude methane chloride products, wherein the separation system described above is used.

[0022] This invention solves the problem of low energy utilization in traditional sequential distillation processes by constructing multi-stage pressure distillation columns (i.e., low-pressure dichloromethane column, high-pressure dichloromethane column, low-pressure trichloromethane column, and high-pressure trichloromethane column) and a cross-column thermal coupling network to achieve cross-column transfer and cascade utilization of top condensation heat. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the accompanying drawings used in the description of the embodiments of the present invention or related technologies are briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of a separation system for crude methane chloride products in the prior art;

[0025] Figure 2 This is a schematic diagram of a separation system for crude methane chloride products in some embodiments of the present invention;

[0026] Figure 3 This is a schematic diagram of a separation system for crude methane chloride products in some other embodiments of the present invention.

[0027] Explanation of reference numerals in the attached figures:

[0028] 1: Dichloromethane tower;

[0029] 2: Chloroform tower;

[0030] 3: Dichloromethane condenser;

[0031] 4: Trichloromethane condenser;

[0032] 5: Dichloromethane reboiler;

[0033] 6: Chloroform reboiler;

[0034] 11: Low-pressure dichloromethane tower;

[0035] 12: High-pressure dichloromethane tower;

[0036] 13: Low-pressure dichloride reboiler;

[0037] 14: Dichlorohydrin cooler;

[0038] 15: Trichloroisocyanuric acid cooler;

[0039] 16: Low-pressure trichlorocondenser;

[0040] 17: Trichloroethylene compressor;

[0041] 18: High-pressure trichloroisocyanuric acid reboiler;

[0042] 19: High-pressure dichloride reboiler;

[0043] 20: Low-pressure trichloroisocyanuric acid reboiler;

[0044] 21: Low-pressure chloroform tower;

[0045] 22: High-pressure chloroform tower;

[0046] 23: Dichlorocompressor. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] Figure 1 This is a schematic diagram of a separation system for crude methane chloride products in existing technology. Figure 1 As shown, existing crude methane chloride products generally employ a sequential distillation process. The core equipment of this separation system includes a dichloromethane column 1, a trichloromethane column 2, a dichloromethane reboiler 5, a dichloromethane condenser 3, a trichloromethane reboiler 6, and a trichloromethane condenser 4. Its basic principle is to achieve separation by controlling the temperature and pressure within the columns and utilizing the differences in boiling points of the different components. Specifically, the dichloromethane reboiler 5 provides heat to the dichloromethane column 1. In the dichloromethane column 1, the heat of vaporization is provided by heating the material at the bottom of the column, causing the low-boiling-point dichloromethane to be condensed from the top of the column and output through the dichloromethane condenser 3. Meanwhile, trichloromethane and carbon tetrachloride enter the trichloromethane column 2 for separation. The chloroform reboiler 6 provides energy for the separation of chloroform and carbon tetrachloride in the chloroform tower 2. The chloroform is condensed and output after passing through the chloroform condenser 4 at the top of the chloroform tower 2, while carbon tetrachloride and other heavy components are output through the bottom of the chloroform tower 2. This process has the following problems:

[0049] Low energy efficiency: Each distillation column operates independently, and the latent heat and sensible heat released when the steam at the top of the column is condensed are not recovered, requiring a large amount of cooling water; the reboiler in the column bottom relies on external steam for heating, resulting in high energy consumption.

[0050] Insufficient thermal coupling integration: Existing improvement schemes only achieve local heat recovery, such as using the top steam of dichloromethane tower 1 to heat trichloromethane reboiler 6, but fail to build a systematic thermal coupling network, resulting in a single energy transfer path and limited recovery efficiency.

[0051] This invention constructs a multi-stage pressure distillation column (low-pressure dichloromethane column, high-pressure dichloromethane column, low-pressure trichloromethane column, and high-pressure trichloromethane column) and a cross-column thermal coupling network to achieve cross-column transfer and cascade utilization of the top condensate heat, reducing external steam and cooling water consumption. This solves the problems of low energy utilization and insufficient thermal coupling integration in traditional processes. Furthermore, it reduces dependence on external steam and cooling systems, optimizes equipment configuration, and shortens the process flow, thereby reducing energy consumption and operation and maintenance costs.

[0052] Figure 2 This is a schematic diagram of a separation system for crude methane chloride products in some embodiments of the present invention; Figure 3 This is a schematic diagram of a separation system for crude methane chloride products in other embodiments of the present invention. For example... Figure 2 and Figure 3 As shown, the present invention provides a separation system for crude methane chloride products, comprising: a low-pressure dichloromethane tower 11, a high-pressure dichloromethane tower 12, a low-pressure trichloromethane tower 21, a high-pressure trichloromethane tower 22, a low-pressure dichloromethane reboiler 13, a low-pressure trichloromethane reboiler 20, and a high-pressure trichloromethane reboiler 18.

[0053] The low-pressure dichloromethane tower 11 has a crude methane chloride inlet and a dichloromethane outlet, the high-pressure dichloromethane tower 12 has a dichloromethane outlet, the low-pressure trichloromethane tower 21 has a trichloromethane outlet, and the high-pressure trichloromethane tower 22 has a trichloromethane outlet.

[0054] The dichloromethane outlet of the high-pressure dichloromethane tower 12 is connected to the high-pressure trichloromethane reboiler 18, the trichloromethane outlet of the high-pressure trichloromethane tower 22 is connected to the low-pressure dichloromethane reboiler 13, and the dichloromethane outlet of the low-pressure dichloromethane tower 11 is connected to the low-pressure trichloromethane reboiler 20.

[0055] It is understandable that the pressure of the low-pressure dichloromethane tower 11 is lower than that of the high-pressure dichloromethane tower 12, and the pressure of the low-pressure trichloromethane tower 21 is lower than that of the high-pressure trichloromethane tower 22.

[0056] Specifically, the crude methane chloride product (mainly containing dichloromethane, trichloromethane, and carbon tetrachloride, at a temperature of 90~150°C) enters the low-pressure dichloromethane tower 11 through the crude methane chloride product inlet. In the low-pressure dichloromethane tower 11, the crude methane chloride product is initially separated, and the resulting dichloromethane rises and is output through the dichloromethane outlet of the low-pressure dichloromethane tower 11. It then enters the low-pressure trichloromethane reboiler 20 through the inlet, providing heat for the low-pressure trichloromethane reboiler 20.

[0057] The remaining raw materials enter the subsequent trichloromethane tower, where they are further separated to obtain dichloromethane in the high-pressure dichloromethane tower 12. The dichloromethane rises and exits through the dichloromethane outlet of the high-pressure dichloromethane tower 12, and enters the high-pressure trichloromethane reboiler 18 through the inlet of the high-pressure trichloromethane reboiler 18 to provide energy for the high-pressure trichloromethane reboiler 18 without the need for additional steam.

[0058] Chloroform is separated in low-pressure chloroform tower 21 and discharged through the chloroform outlet of low-pressure chloroform tower 21;

[0059] Chloroform and heavy components including carbon tetrachloride are separated in the high-pressure chloroform tower 22. The chloroform is output from the chloroform outlet of the high-pressure chloroform tower 22 and enters the low-pressure dichloroform reboiler 13 through the inlet of the low-pressure dichloroform reboiler 13 to provide energy for the low-pressure dichloroform reboiler 13. The carbon tetrachloride and other heavy components are output from the bottom of the high-pressure chloroform tower 22.

[0060] This invention utilizes distillation columns with different pressure levels, including a low-pressure dichloromethane column 11, a high-pressure dichloromethane column 12, a low-pressure trichloromethane column 21, and a high-pressure trichloromethane column 22. A highly flexible, multi-level thermally coupled network is constructed within the system. The gaseous dichloromethane from the top of the high-pressure dichloromethane column 12 serves as the heat source for the high-pressure trichloromethane reboiler 18, the gaseous trichloromethane from the top of the high-pressure trichloromethane column 22 serves as the heat source for the low-pressure dichloromethane reboiler 13, and the gaseous dichloromethane from the top of the low-pressure dichloromethane column 11 serves as the heat source for the low-pressure trichloromethane reboiler 20. This high degree of thermal integration improves upon the traditional "energy island" sequential distillation model, solving the problems of low energy utilization and insufficient thermal coupling integration in traditional processes. Furthermore, it reduces dependence on external steam and cooling systems, optimizes equipment configuration, and shortens the process flow, thereby reducing energy consumption and maintenance costs.

[0061] This invention allows for the selection of pressure and temperature for the low-pressure dichloromethane tower 11, high-pressure dichloromethane tower 12, low-pressure trichloromethane tower 21, and high-pressure trichloromethane tower according to actual needs, thereby further improving the separation efficiency of crude methane chloride products and maximizing energy savings. In some embodiments of this invention, the operating pressure of the high-pressure dichloromethane tower 12 is 0.4~1 MPaG; and / or,

[0062] When the operating pressure of the low-pressure trichloromethane tower 21 is -0.07 to -0.01 MPaG, the separation efficiency of the crude methane chloride product can be further improved, and energy savings can be maximized. It can be understood that the temperature of the high-pressure dichloromethane tower 12 can be selected based on its operating pressure, and the operating pressure of the low-pressure trichloromethane tower 21 can also be selected based on its operating pressure; furthermore, the operating pressures of the low-pressure dichloromethane tower 11 and the high-pressure trichloromethane tower 22 can be determined based on the operating pressures of the high-pressure dichloromethane tower 12 and the low-pressure trichloromethane tower 21.

[0063] like Figure 2 As shown, in some embodiments of the present invention, the high-pressure dichloromethane tower 12 has a crude methane chloride product inlet, the bottom outlet of the low-pressure dichloromethane tower 11 is connected to the feed inlet of the low-pressure trichloromethane tower 21, the bottom outlet of the high-pressure dichloromethane tower 12 is connected to the feed inlet of the low-pressure trichloromethane tower 21, and the bottom outlet of the low-pressure trichloromethane tower 21 is connected to the feed inlet of the high-pressure trichloromethane tower 22.

[0064] Specifically, the crude methane chloride product from the upstream reaction unit is divided into two streams: one enters a low-pressure dichloromethane tower 11, and the other enters a high-pressure dichloromethane tower 12. In the low-pressure dichloromethane tower 11, the crude methane chloride product undergoes distillation separation, with the lower-boiling-point dichloromethane distilled off from the top and output through the dichloromethane outlet of the low-pressure dichloromethane tower 11. In the high-pressure dichloromethane tower 12, the same separation process is carried out at a higher pressure, and the dichloromethane is output through the dichloromethane outlet of the high-pressure dichloromethane tower 12. The dichloromethane products from the low-pressure dichloromethane tower 11 and the high-pressure dichloromethane tower 12 are combined and sent to a dichloromethane product storage tank.

[0065] The remaining product in the low-pressure dichloromethane tower 11 is discharged from the bottom outlet of the low-pressure dichloromethane tower 11 and enters the low-pressure trichloromethane tower 21 through the feed inlet. The remaining product in the high-pressure dichloromethane tower 12 is discharged from the bottom outlet of the high-pressure dichloromethane tower 12 and enters the low-pressure trichloromethane tower 21 through the feed inlet (in some embodiments, the bottom liquids of the low-pressure dichloromethane tower 11 and the high-pressure dichloromethane tower 12 merge after flowing out and enter the low-pressure trichloromethane tower 21). Preliminary separation of trichloromethane and carbon tetrachloride is carried out in the low-pressure trichloromethane tower 21, and a small amount of trichloromethane product is collected from the top of the tower and discharged through the trichloromethane outlet of the low-pressure trichloromethane tower 21.

[0066] The remaining chloroform and carbon tetrachloride flow out of the bottom of the low-pressure chloroform tower 21, are pressurized by a transfer pump, and enter the high-pressure chloroform tower 22. In the high-pressure chloroform tower 22, chloroform and carbon tetrachloride are separated to obtain chloroform and heavy components including carbon tetrachloride. The chloroform is output through the chloroform outlet of the high-pressure chloroform tower 22, while the carbon tetrachloride and other heavy components are output through the bottom of the high-pressure chloroform tower 22.

[0067] In this invention, the proportion of crude methane chloride entering the low-pressure dichloromethane tower 11 and the high-pressure dichloromethane tower 12 can be selected according to actual needs (based on reactant composition and energy consumption optimization targets). In some embodiments, the crude methane chloride entering the low-pressure dichloromethane tower 11 can be 0.3~0.7% of the total crude methane chloride. The adjustable material proportions entering the high-pressure dichloromethane tower 12 and the low-pressure dichloromethane tower 11 provide a flexible design that allows the system to adapt to different production loads and raw material changes, improving the flexibility and economy of the entire production unit and enhancing the operational flexibility of the process flow.

[0068] In some embodiments, the operating pressure of the low-pressure dichloromethane tower 11 can be 0.05~0.5 MPaG, the top temperature can be 50~80℃, and the bottom temperature can be 70~120℃; the operating pressure of the high-pressure dichloromethane tower 12 can be 0.4~1 MPaG, the top temperature can be 90~120℃, and the bottom temperature can be 130~150℃; the operating pressure of the low-pressure trichloromethane tower 21 can be -0.07~0.01 MPaG, the top temperature can be 40~60℃, and the bottom temperature can be 45~70℃; the operating pressure of the high-pressure trichloromethane tower 22 can be 0.01~0.15 MPaG, and the top temperature can be 50~90℃. In some embodiments, the trichloromethane produced by the low-pressure trichloromethane tower 21 can account for 0.2~0.5% of the total trichloromethane produced.

[0069] In some embodiments, a high-pressure dichloromethane reboiler 19 is also included, and the product output from the high-pressure dichloromethane tower 12 can provide energy for the high-pressure dichloromethane reboiler 19.

[0070] In some embodiments, a low-pressure trichloromethane condenser 16 is also included. Trichloromethane is output from the trichloromethane outlet of the low-pressure trichloromethane tower 21 and enters the low-pressure trichloromethane condenser 16 through the inlet. After being condensed in the low-pressure trichloromethane condenser 16, liquid trichloromethane is obtained. Part of the liquid trichloromethane enters the low-pressure trichloromethane tower 21 through the top inlet of the low-pressure trichloromethane tower 21 as reflux, and part of the liquid trichloromethane can be collected as a product.

[0071] In some embodiments of the present invention, the separation system further includes a trichloropolymer compressor 17 and a trichloropolymer cooler 15;

[0072] The chloroform outlet of the high-pressure chloroform tower 22 is connected to the inlet of the chloroform compressor 17, the outlet of the chloroform compressor 17 is connected to the inlet of the low-pressure dichloroform reboiler 13, the outlet of the low-pressure dichloroform reboiler 13 is connected to the inlet of the chloroform cooler 15, and the outlet of the chloroform cooler 15 is connected to the top inlet of the high-pressure chloroform tower 22.

[0073] Specifically, by installing a heat pump distillation system at the top of the high-pressure trichloromethane tower 22, a large amount of trichloromethane vapor produced at the top of the high-pressure trichloromethane tower 22 enters the trichloromethane compressor 17. The trichloromethane compressor 17 performs work on the trichloromethane, significantly increasing its pressure and temperature (for example, increasing the pressure from 0.01~0.15 MPaG to 0.1~0.5 MPaG and the temperature from 50~90℃ to 90~150℃) to obtain high-pressure, high-temperature vapor. This high-pressure, high-temperature vapor is output through the outlet of the trichloromethane compressor 17 and then passes through the inlet of the low-pressure dichloromethane reboiler 13. The vapor enters the low-pressure dichloromethane reboiler 13 to provide a heat source for the low-pressure dichloromethane tower 11. The trichloromethane vapor is condensed in the low-pressure dichloromethane reboiler 13 to form trichloromethane liquid. The obtained trichloromethane liquid is output through the outlet of the low-pressure dichloromethane reboiler 13 and enters the trichloromethane cooler 15 through the inlet of the trichloromethane tower. After being cooled in the trichloromethane cooler 15, it can be output through the outlet of the trichloromethane cooler 15 and enter the trichloromethane tower as reflux liquid through the top inlet of the high-pressure trichloromethane tower 22, or it can be output through the outlet of the trichloromethane cooler 15 for product storage.

[0074] Carbon tetrachloride and other heavy components are collected from the bottom of the high-pressure trichloromethane tower 22. The high-pressure trichloromethane reboiler 18 in the bottom of the tower is heated by the gaseous liquid at the top of the high-pressure dichloromethane tower 12, without the need for additional steam.

[0075] In some embodiments of the present invention, a dichloride cooler 14 is also included;

[0076] The dichloromethane outlet of the low-pressure dichloromethane tower 11 is connected to the inlet of the dichloromethane cooler 14;

[0077] The outlet of the high-pressure trichlororeboiler 18 is connected to the top inlet of the high-pressure dichloromethane tower 12, and the outlet of the high-pressure trichlororeboiler 18 is connected to the outlet of the dichlorocooler 14.

[0078] Specifically, dichloromethane is output from the dichloromethane outlet of the low-pressure dichloromethane tower 11 and enters the dichloromethane cooler 14 through the inlet of the dichloromethane cooler 14. After being cooled by the dichloromethane cooler 14, it is stored as a product.

[0079] After dichloromethane is heated and formed into a liquid phase by the high-pressure trichloromethane reboiler 18, it is output from the outlet of the high-pressure trichloromethane reboiler 18 and enters the high-pressure dichloromethane tower 12 through the top inlet of the tower as reflux liquid. After dichloromethane is heated and formed into a liquid phase by the high-pressure trichloromethane reboiler 18, it is output from the outlet of the high-pressure trichloromethane reboiler 18 and enters the dichloromethane cooler 14 through the inlet of the dichloromethane cooler 14. After being cooled by the dichloromethane cooler 14, it is stored as a product.

[0080] like Figure 2 In the separation system shown, a three-level thermally coupled network is constructed.

[0081] The first-stage thermal coupling integrates the dichloromethane cooler 14 at the top of the low-pressure dichloromethane tower 11 with the low-pressure trichloromethane reboiler 20. The sensible heat and a large amount of latent heat released when the steam at the top of the low-pressure dichloromethane tower 11 condenses are directly used to heat the low-pressure trichloromethane reboiler 20 at the bottom of the low-pressure trichloromethane tower 21, realizing direct energy transfer across towers.

[0082] The second stage of thermal coupling involves integrating the condenser at the top of the high-pressure dichloromethane column 12 with the high-pressure trichloromethane reboiler 18 at the bottom of the high-pressure trichloromethane column 22. Similarly, the condensation heat of the vapor at the top of the high-pressure dichloromethane column 12 is used to drive the high-pressure trichloromethane reboiler 18 at the bottom of the high-pressure trichloromethane column 22.

[0083] The third-stage thermal coupling uses a trichloromethane compressor 17 to "upgrade" the heat of the overhead vapor from the high-pressure trichloromethane tower 22, which is then used to supply the low-pressure dichloromethane reboiler 13 of the low-pressure dichloromethane tower 11. This not only recovers heat but also achieves efficient reverse energy utilization from the back end of the process to the front end. This invention uses the heat from the top of the trichloromethane tower to drive the front-end separation, rather than the trichloromethane tower itself, thus maximizing heat utilization.

[0084] The separation system of this invention systematically solves the fundamental defects of traditional processes, such as wasted condensation heat at the top of the distillation column and huge external energy consumption. By setting and matching pressure levels, a temperature difference that can be used for heat transfer is created, so that the latent heat of condensation at the top of each column, which originally needed to be dissipated by cooling water, is precisely used to drive the reboiling process of other columns, realizing the internal circulation and cascade utilization of process heat. At the same time, the introduction of heat pump technology "upgrades" the heat energy at the top of the downstream distillation column and feeds it back to the upstream distillation column for use, forming a cross-series reverse energy utilization, which greatly reduces or even eliminates the dependence on external fresh steam and cooling water in some links. Moreover, the flow ratio of the streams entering and leaving distillation columns of different pressure levels is adjustable, which can cope with the working conditions of various raw material compositions, thereby reducing the overall energy consumption by about 66%, transforming a high-energy-consumption, high-emission linear process into a low-energy-consumption, high-efficiency, and highly flexible thermal integrated system.

[0085] like Figure 3As shown, in some embodiments of the present invention, the bottom outlet of the low-pressure dichloromethane tower 11 is connected to the feed inlet of the high-pressure dichloromethane tower 12, the bottom outlet of the high-pressure dichloromethane tower 12 is connected to the feed inlet of the low-pressure trichloromethane tower 21, the bottom outlet of the trichloromethane tower is connected to the feed inlet of the high-pressure trichloromethane tower 22, the top of the low-pressure trichloromethane tower 21 has a trichloromethane outlet, and the high-pressure trichloromethane tower 22 has a trichloromethane outlet.

[0086] Specifically, the crude methane chloride product is separated into dichloromethane and a first residue product in a low-pressure dichloromethane column 11. The first residue product is output from the bottom outlet of the low-pressure dichloromethane column 11 and enters the high-pressure dichloromethane column 12 through the feed inlet. Dichloromethane is separated in the high-pressure dichloromethane column 12 to obtain a second residue product. The second residue product is output from the bottom outlet of the high-pressure dichloromethane column 12 and enters the low-pressure trichloromethane column 21 through the feed inlet. Trichloromethane is separated in methane tower 1 to obtain a third residual product. The trichloromethane is output through the trichloromethane outlet of low-pressure trichloromethane tower 21, and the third residual product is output through the bottom outlet of low-pressure trichloromethane tower 21. It enters high-pressure trichloromethane tower 22 through the feed inlet. In high-pressure trichloromethane tower 22, trichloromethane and heavy components including carbon tetrachloride are separated. The trichloromethane is output through the trichloromethane outlet of high-pressure trichloromethane tower 22, and carbon tetrachloride and other heavy components are output through the bottom outlet of high-pressure trichloromethane tower 22.

[0087] In some embodiments, a high-pressure dichloro reboiler 19 is also included, and the first residual product can provide energy for the high-pressure dichloro reboiler 19.

[0088] In some embodiments, a low-pressure trichloromethane condenser 16 is also included. Trichloromethane is output from the trichloromethane outlet of the low-pressure trichloromethane tower 21 and enters the low-pressure trichloromethane condenser 16 through the inlet. After being condensed by the low-pressure trichloromethane condenser 16, liquid trichloromethane is obtained. Part of the liquid trichloromethane enters the low-pressure trichloromethane tower 21 through the top inlet of the low-pressure trichloromethane tower 21 as reflux, and part of the liquid trichloromethane can be collected as a product.

[0089] In some embodiments of the present invention, the separation system further includes a dichloride compressor 23 and a dichloride cooler 14;

[0090] The top outlet of the low-pressure dichloromethane tower 11 is connected to the inlet of the dichloromethane compressor 23, the outlet of the dichloromethane compressor 23 is connected to the inlet of the low-pressure trichloromethane reboiler 20, the outlet of the low-pressure trichloromethane reboiler 20 is connected to the inlet of the dichloromethane cooler 14, and the outlet of the dichloromethane cooler 14 is connected to the top inlet of the low-pressure dichloromethane tower 11.

[0091] Specifically, the crude product of methane chloride from the methane chlorination reaction unit enters the low-pressure dichloromethane tower 11. The dichloromethane produced by the low-pressure dichloromethane tower is output from the top outlet of the tower and enters the dichloromethane compressor 23 through the inlet of the dichloromethane compressor 23. After being pressurized by the dichloromethane compressor 23, it is output from the outlet of the dichloromethane compressor 23 and enters the low-pressure trichloromethane reboiler 20 through the inlet of the low-pressure trichloromethane reboiler 20, providing a heat source for the low-pressure trichloromethane tower 21.

[0092] The low-pressure trichloromethane tower 21 uses heat to form liquid dichloromethane, which is output through the outlet of the low-pressure trichloromethane reboiler 20 and enters the dichloromethane cooler 14 for further cooling through the inlet of the dichloromethane cooler 14. The resulting liquid dichloromethane can be returned to the low-pressure dichloromethane tower 11 through the top inlet of the low-pressure dichloromethane tower 11 as reflux liquid. The resulting liquid dichloromethane can be collected as a product.

[0093] Furthermore, the outlet of the high-pressure trichlororeboiler 18 is connected to the top inlet of the high-pressure dichloromethane tower 12.

[0094] Dichloromethane is heated in a high-pressure trichloromethane reboiler 18 to form liquid dichloromethane. The liquid dichloromethane can be output from the outlet of the high-pressure trichloromethane reboiler 18 and enter the high-pressure dichloromethane tower 12 through the top inlet of the tower as reflux liquid. The liquid dichloromethane can also be output from the outlet of the high-pressure trichloromethane reboiler 18 and mixed with the dichloromethane output from the dichloromethane cooler 14 before being collected as the product.

[0095] Furthermore, the outlet of the low-pressure dichloro reboiler 13 is connected to the top inlet of the high-pressure trichloromethane tower 22.

[0096] After being heated by the low-pressure dichloromethane reboiler 13, trichloromethane is converted into liquid trichloromethane. The liquid trichloromethane can be output from the outlet of the low-pressure dichloromethane reboiler 13 and enter the high-pressure trichloromethane tower 22 through the top inlet of the high-pressure trichloromethane tower 22 as reflux liquid. The liquid trichloromethane can also be output from the outlet of the low-pressure dichloromethane reboiler 13 and mixed with the trichloromethane output from the low-pressure trichloromethane condenser 16, and then collected as the product.

[0097] The present invention also provides a method for separating crude methane chloride products, using the separation system described above.

[0098] This invention separates crude methane chloride products using the aforementioned separation system. The overhead vapor from high-pressure dichloromethane column 12 serves as the heat source for high-pressure trichloromethane reboiler 18, the overhead vapor from high-pressure trichloromethane column 22 serves as the heat source for low-pressure dichloromethane reboiler 13, and the overhead vapor from low-pressure dichloromethane column 11 serves as the heat source for low-pressure trichloromethane reboiler 20, achieving a high degree of thermal integration. Compared to existing sequential distillation separation methods, this method consumes less energy, reducing steam consumption by approximately 72%, circulating water consumption by approximately 69%, and overall energy consumption by approximately 66%, demonstrating significant energy-saving effects.

[0099] The technical solution of the present invention will be further described below with reference to specific embodiments.

[0100] Example 1

[0101] The use of this embodiment Figure 2 The crude methane chloride product separation system shown separates crude methane chloride products.

[0102] The separation system includes: a low-pressure dichloromethane tower 11, a high-pressure dichloromethane tower 12, a low-pressure trichloromethane tower 21, a high-pressure trichloromethane tower 22, a low-pressure dichloromethane reboiler 13, a high-pressure dichloromethane reboiler 19, a low-pressure trichloromethane condenser 16, a low-pressure trichloromethane reboiler 20, a trichloromethane compressor 17, a high-pressure trichloromethane reboiler 18, a dichloromethane cooler 14, and a trichloromethane cooler 15;

[0103] First, the crude methane chloride product from the methane chlorination reaction unit is split into two independent streams with a mass flow ratio of 1:1. The first stream is introduced into a low-pressure dichloromethane column 11, operating at a pressure maintained at 0.15 MPaG, for distillation. The vapor output from the top of the low-pressure dichloromethane column 11 is divided into two streams: one enters a low-pressure trichloromethane reboiler 20, providing a heat source for the low-pressure trichloromethane column 21; the other is cooled by a dichloromethane cooler 14 and discharged as product. The bottom of the low-pressure dichloromethane column 11, in the low-pressure dichloromethane reboiler 13, is heated by the high-temperature vapor from the trichloromethane compressor 17 at the top of the high-pressure trichloromethane column 22, requiring no additional steam heating. The bottom product is then combined with the high-pressure dichloromethane column 12 and enters the low-pressure trichloromethane column 21.

[0104] Simultaneously, the second stream of crude product feed enters the high-pressure dichloromethane column 12, maintained at 0.7 MPaG, for separation. The vapor phase at the top of the high-pressure dichloromethane column 12 enters the high-pressure trichloromethane reboiler 18, providing a heat source for the high-pressure trichloromethane column 22, eliminating the need for additional circulating water condensation. The condensed dichloromethane splits into two streams: one flows back to the top of the high-pressure dichloromethane column 12, and the other is discharged as product. The material collected from the bottom of the high-pressure dichloromethane column 12 merges with the material from the bottom of the low-pressure dichloromethane column 11 and enters the low-pressure trichloromethane column 21.

[0105] In the low-pressure trichloromethane column 21 (operating pressure -0.04 MPaG), preliminary separation of trichloromethane and carbon tetrachloride is performed. A small amount of trichloromethane is collected from the top of the column. The low-pressure trichloromethane reboiler 20 at the bottom of the column is heated by the high-temperature gas phase from the top of the low-pressure dichloromethane column 11, requiring no additional steam. The trichloromethane and carbon tetrachloride collected from the bottom of the column enter the high-pressure trichloromethane column 22 for further separation. In the high-pressure trichloromethane column 22 (operating pressure 0.01 MPaG), the trichloromethane gas phase discharge from the top of the column first enters the trichloromethane compressor 17, which increases the pressure of the gas phase stream to 0.2 MPaG. Then, this high-temperature, high-pressure trichloromethane gas phase material enters the low-pressure dichloromethane reboiler 13 for power. The condensed trichloromethane liquid enters the trichloromethane cooler 15 for further cooling and is then divided into two streams: one stream is returned to the top of the high-pressure trichloromethane column 22 as reflux, and the other stream is sent out as product. Carbon tetrachloride and other heavy components are collected from the bottom of the high-pressure trichloromethane tower 22. The high-pressure trichloromethane reboiler 18 in the bottom of the tower is heated by the gaseous liquid at the top of the high-pressure dichloromethane tower 12, without the need for additional steam.

[0106] Table 1 shows the usage Figure 1 The separation system shown, as well as the energy consumption and product purity of the crude methane chloride product separated in this embodiment, are illustrated.

[0107] Table 1

[0108]

[0109] As can be seen from Table 1, Figure 1 The separation system shown consumes approximately 6 tons / h of low-pressure saturated steam and approximately 650 tons / h of circulating water when separating the crude methane chloride product of this embodiment. In this embodiment, however, the system uses… Figure 2 The separation system shown separates crude methane chloride product, consuming approximately 1.65 tons / h of low-pressure saturated steam and approximately 200 tons / h of circulating water. The separation method in this embodiment can reduce steam consumption by approximately 72.5%, circulating water consumption by approximately 69%, and overall energy consumption by approximately 66%.

[0110] Example 2

[0111] The use of this embodiment Figure 3 The crude methane chloride product separation system shown separates crude methane chloride products.

[0112] The separation system includes a low-pressure dichloromethane tower 11, a high-pressure dichloromethane tower 12, a low-pressure trichloromethane tower 21, a high-pressure trichloromethane tower 22, a low-pressure dichloromethane reboiler 13, a high-pressure dichloromethane reboiler 19, a low-pressure trichloromethane condenser 16, a low-pressure trichloromethane reboiler 20, a dichloromethane compressor 23, a high-pressure trichloromethane reboiler 18, and a dichloromethane cooler 14;

[0113] The top gas phase of the high-pressure dichloromethane tower 12 serves as the heat source for the high-pressure trichloromethane reboiler 18 of the high-pressure trichloromethane tower, the top gas phase of the high-pressure trichloromethane tower 22 serves as the heat source for the low-pressure dichloromethane reboiler 13 of the low-pressure dichloromethane tower 11, and the top gas phase of the low-pressure dichloromethane tower 11 serves as the bottom heat source for the low-pressure trichloromethane tower 21.

[0114] First, the crude product from the methane chlorination reaction unit enters the low-pressure dichloromethane column 11 (operating pressure 0.05 MPaG). The overhead vapor from the dichloromethane column first enters the dichloromethane compressor 23, is pressurized to 0.15 MPaG, and then enters the low-pressure trichloromethane reboiler 20 to provide a heat source for the low-pressure trichloromethane column 21. After further cooling in the dichloromethane cooler 14, it is divided into two streams: one returns to the top of the column, and the other is collected as product. The low-pressure dichloromethane reboiler 13 at the bottom of the low-pressure dichloromethane column 11 is heated by the overhead vapor from the high-pressure trichloromethane column 22. The bottom liquid from the low-pressure dichloromethane column 11 enters the high-pressure dichloromethane column 12 for further separation.

[0115] In the high-pressure dichloromethane tower 12 (pressure 0.7 MPaG), the gaseous discharge from the top of the tower first enters the high-pressure trichloromethane reboiler 18 to provide a heat source for the high-pressure trichloromethane tower 22. After cooling, it is divided into two streams. One stream returns to the top of the tower, and the other stream, as dichloromethane product, merges with the dichloromethane collected from the low-pressure dichloromethane tower 11 and is then sent outside the boundary.

[0116] The feed liquid from the bottom of the high-pressure dichloromethane tower 12 enters the low-pressure trichloromethane tower 21 (pressure -0.04 MPaG). A portion of trichloromethane is collected from the top of the low-pressure trichloromethane tower 21, and the heat source for the low-pressure trichloromethane reboiler 20 is provided by the top gas phase of the low-pressure dichloromethane tower 11. The material from the bottom of the low-pressure trichloromethane tower 21 enters the high-pressure trichloromethane tower 22.

[0117] In the high-pressure trichloromethane tower 22 (pressure 0.1 MPaG), the vaporous discharge from the top of the tower first enters the low-pressure dichloromethane reboiler 13. After cooling, it splits into two streams: one returns to the top of the tower, and the other, as the product, merges with the product from the low-pressure trichloromethane tower 21 and is then sent outside the boundary. The high-pressure trichloromethane reboiler 18 is heated by the vaporous discharge from the top of the high-pressure dichloromethane tower 12. The carbon tetrachloride and other heavy components collected from the bottom of the high-pressure trichloromethane tower 22 are sent outside the boundary.

[0118] Figure 1 The separation system shown consumes approximately 7.6 tons / h of low-pressure saturated steam and approximately 815 tons / h of circulating water when separating the crude methane chloride product of this embodiment. In this embodiment, however, the system uses… Figure 3The separation system shown separates crude methane chloride product, consuming approximately 2.1 tons / h of low-pressure saturated steam and approximately 240 tons / h of circulating water. The separation method in this embodiment can reduce steam consumption by approximately 72.4%, circulating water consumption by approximately 70%, and overall energy consumption by approximately 66.1%.

[0119] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A separation system of a crude methane chloride product, characterized by, Comprising: a low-pressure dichloromethane column, a high-pressure dichloromethane column, a low-pressure trichloromethane column, a high-pressure trichloromethane column, a low-pressure dichloro reboiler, a low-pressure trichloro reboiler, a high-pressure trichloro reboiler; the low-pressure dichloromethane column has a crude methylene chloride product inlet and a dichloromethane outlet, the high-pressure dichloromethane column has a dichloromethane outlet, the low-pressure trichloromethane column has a trichloromethane outlet, and the high-pressure trichloromethane column has a trichloromethane outlet; the dichloromethane outlet of the high-pressure dichloromethane column is in communication with the high-pressure trichloro reboiler, the trichloromethane outlet of the high-pressure trichloromethane column is in communication with the low-pressure dichloro reboiler, and the dichloromethane outlet of the low-pressure dichloromethane column is in communication with the low-pressure trichloro reboiler.

2. The separation system of claim 1, wherein, the operating pressure of the high-pressure dichloromethane column is 0.4-1 MPaG; and / or, the operating pressure of the low-pressure trichloromethane column is -0.07--0.01 MPaG.

3. The separation system according to claim 1 or 2, characterized in that the low-pressure dichloromethane column has a crude methylene chloride product inlet, the column bottom outlet of the low-pressure dichloromethane column is in communication with the raw material inlet of the low-pressure trichloromethane column, the column bottom outlet of the high-pressure dichloromethane column is in communication with the raw material inlet of the low-pressure trichloromethane column, and the column bottom outlet of the low-pressure trichloromethane column is in communication with the raw material inlet of the high-pressure trichloromethane column.

4. The separation system of claim 3, wherein, Further comprising a trichloro compressor and a trichloro cooler; the trichloromethane outlet of the high-pressure trichloromethane column is in communication with the inlet of the trichloro compressor, the outlet of the trichloro compressor is in communication with the inlet of the low-pressure dichloro reboiler, the outlet of the low-pressure dichloro reboiler is in communication with the inlet of the trichloro cooler, and the outlet of the trichloro cooler is in communication with the top inlet of the high-pressure trichloromethane column.

5. The separation system of claim 4, wherein, Further comprising a dichloro cooler; the dichloromethane outlet of the low-pressure dichloromethane column is in communication with the inlet of the dichloro cooler; the outlet of the high-pressure trichloro reboiler is in communication with the top inlet of the high-pressure dichloromethane column, and the outlet of the high-pressure trichloro reboiler is in communication with the outlet of the dichloro cooler.

6. The separation system of claim 1 or 2, wherein, the column bottom outlet of the low-pressure dichloromethane column is in communication with the raw material inlet of the high-pressure dichloromethane column, the column bottom outlet of the high-pressure dichloromethane column is in communication with the raw material inlet of the low-pressure trichloromethane column, the column bottom outlet of the low-pressure trichloromethane column is in communication with the raw material inlet of the high-pressure trichloromethane column, the top of the low-pressure trichloromethane column has a trichloromethane outlet, and the high-pressure trichloromethane column has a trichloromethane outlet.

7. The separation system of claim 6, wherein, Further comprising a dichloro compressor and a dichloro cooler; the top outlet of the low-pressure dichloromethane column is in communication with the inlet of the dichloro compressor, the outlet of the dichloro compressor is in communication with the inlet of the low-pressure trichloro reboiler, the outlet of the low-pressure trichloro reboiler is in communication with the inlet of the dichloro cooler, and the outlet of the dichloro cooler is in communication with the top inlet of the low-pressure dichloromethane column.

8. The separation system of claim 7, wherein, the outlet of the high-pressure trichloro reboiler is in communication with the top inlet of the high-pressure dichloromethane column.

9. A separation system according to claim 7 or 8, characterised in that, the outlet of the low-pressure dichloro reboiler is in communication with the top inlet of the high-pressure trichloromethane column.

10. A process for the separation of a crude methane chloride product, characterized in that, using the separation system of any one of claims 1-9.

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