A system and method for the separation of crude organosilicon monomers by six-tower heat integrated distillation

Abstract

The application discloses a system and method for separating crude organosilicon monomers by six-tower heat integration rectification, and is characterized by comprising a high-removing tower, a low-removing tower, a light separation tower, a hydrogen-containing tower, a trimethyl tower, a dimethyl tower, a separator and a mixer; the high-removing tower is connected with a preheater through a pipeline; a gas phase outlet at the top of the high-removing tower is connected with an inlet of the separator through a first heat exchanger; one outlet of the separator is connected with an inlet of the mixer through a second heat exchanger; another outlet of the separator is connected with the inlet of the mixer through a third heat exchanger; an outlet of the mixer is connected with the high-removing tower and the low-removing tower respectively; the low-removing tower is connected with the light separation tower; the low-removing tower is connected with the dimethyl tower through a preheater; a bottom product outlet of the dimethyl tower is connected with an auxiliary reboiler and the third heat exchanger respectively; the light separation tower is connected with the hydrogen-containing tower through the first heat exchanger; the hydrogen-containing tower is connected with the trimethyl tower through the second heat exchanger; and the method has the advantages of realizing high-purity separation of crude organosilicon monomers and greatly reducing energy consumption in production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical separation and purification, and in particular to a six-tower heat integrated distillation device and method for separating crude organosilicon monomers. BACKGROUND

[0002] Organosilicon is a new type of material with excellent performance and unique function. It can be used as a basic material and structural material in some large industries, and can also be added to other materials as a functional material to improve their process performance, thus gaining the reputation of "industrial MSG" and "catalyst for technological development".

[0003] Organosilicon monomers are essential for the preparation of organosilicon materials, and methyl chlorosilane, especially dimethyl dichlorosilane, is the most important and largest amount of organosilicon monomer. Regardless of the method used to produce methyl chlorosilane, it is a multi-component mixture, which has a series of problems such as multiple monomer components, small boiling point difference, and difficult separation and purification. In the production of organosilicon monomers, the distillation unit is a large consumer of steam. In industry, 7-10 distillation towers are generally used to separate and purify methyl chlorosilane. The first tower is generally a high-removal tower, and the order of the subsequent towers varies depending on the different separation sequences, including seven-tower process, cis-cutting process, trans-cutting process, and middle-cut process. When the same product purity requirement is reached, the yield of each main monomer in the above four processes is not much different, and the middle-cut process has the lowest energy consumption, while the cis-cutting separation process has the highest energy consumption. The product purity and yield of the seven-tower process are relatively low, and it is difficult to meet the industrial requirements. These separation sequences are mainly improvements on the seven-tower process. The seven-tower process mainly includes a high-removal tower, a low-removal tower, a light separation tower, a hydrogen-containing tower, a azeotropic tower, a trimethyl tower, and a dimethyl tower. Currently, the seven-tower process is modified to establish a six-tower separation process (traditional process). When separating monomethyl, dimethyl and other substances in the low-removal tower, monomethyl and dimethyl are as much as possible to enter the dimethyl tower, and then the qualified trimethyl product is collected at the bottom of the azeotropic tower. Although the six-tower process is simpler and more convenient than the seven-tower process, it still has the problem of high energy consumption. This is mainly because after the steam enters the reboiler of each tower for heat exchange, most of it becomes nearly saturated condensate at the same temperature and pressure through the drain valve, and part of it enters the recovery tank to become low-value steam, which cannot be utilized and increases the cost. Unstable conditions cause separation difficulties and other problems. Therefore, it is very important to find a process technology that can reduce investment costs and operating energy consumption. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a six-tower heat integrated distillation system and method for separating crude organosilicon monomers with high purity and significantly reducing energy consumption.

[0005] The technical scheme adopted by the present application to solve the above technical problems is as follows: a six-tower heat integrated rectification system for separating crude organosilicon monomers, comprising a high-removing tower, a low-removing tower, a light separation tower, a hydrogen-containing tower, a trimethyl tower, a dimethyl tower, a separator and a mixer; a preheater is connected to the middle raw material inlet of the high-removing tower through a pipeline; the gas phase outlet at the top of the high-removing tower is connected to the inlet of the separator through a first heat exchanger; one outlet of the separator is connected to the inlet of the mixer through a second heat exchanger; another outlet of the separator is connected to the inlet of the mixer through a third heat exchanger; the outlet of the mixer is connected to the reflux inlet of the high-removing tower and the middle material inlet of the low-removing tower respectively; the material outlet at the top of the low-removing tower is connected to the middle material inlet of the light separation tower; the material outlet at the bottom of the low-removing tower is connected to the middle material inlet of the dimethyl tower through the preheater; the product outlet at the bottom of the dimethyl tower is connected to an auxiliary reboiler and the third heat exchanger respectively; the material outlet at the bottom of the light separation tower is connected to the middle material inlet of the hydrogen-containing tower through the first heat exchanger; the material outlet at the bottom of the hydrogen-containing tower is connected to the middle material inlet of the trimethyl tower through the second heat exchanger.

[0006] Further, a condenser is arranged at the product outlet at the top of the low-removing tower, the light separation tower, the hydrogen-containing tower, the trimethyl tower and the dimethyl tower respectively.

[0007] Further, a reboiler is arranged at the product outlet at the bottom of the high-removing tower, the low-removing tower and the trimethyl tower respectively.

[0008] A method for separating crude organosilicon monomers by using the above six-tower heat integrated rectification system, comprising the following steps

[0009] (1) The crude organosilicon monomer mixture is preheated by a preheater and then enters the high-removing tower; after being treated by the high-removing tower, the steam at the top of the high-removing tower is exchanged with the first heat exchanger through a pipeline, and then is separated into two streams by the separator; one stream is exchanged with the second heat exchanger, and the other stream is exchanged with the third heat exchanger; after being exchanged, the two streams are mixed by the mixer, and then part of the mixture is returned to the high-removing tower, and the other part is taken out and enters the low-removing tower; the high-boiling substances at the bottom of the high-removing tower are taken out;

[0010] (2) The mixture with a boiling point lower than monomethyltrichlorosilane taken out from the top of the low-removing tower is sent to the light separation tower; the mixture of monomethyltrichlorosilane and dimethyldichlorosilane taken out from the bottom of the low-removing tower is preheated by a preheater and then enters the dimethyl tower;

[0011] (3) The low-boiling substances with a boiling point lower than monomethyldichlorosilane taken out from the top of the light separation tower are sent to the hydrogen-containing tower after being exchanged with the steam at the top of the high-removing tower by the first heat exchanger;

[0012] (4) The methyl dichlorosilane containing hydrogen column top product is taken out, the column bottom stream is heated with one stream separated by the separator through the second heat exchanger, and the mixture of the trimethyl monochlorosilane and silicon tetrachloride taken out is sent into the trimethyl column;

[0013] (5) The trimethyl monochlorosilane and silicon tetrachloride azeotrope of the trimethyl column top is taken out, and the trimethyl monochlorosilane product is taken out from the bottom;

[0014] (6) The dimethyl dichlorosilane product is taken out from the dimethyl column top, and the column bottom stream is divided into two streams, one of which is heated by the auxiliary reboiler and then returned to the dimethyl column, and the other of which is heated with another stream separated by the separator through the third heat exchanger and then returned to the dimethyl column, and the dimethyl dichlorosilane product is taken out from the bottom of the dimethyl column.

[0015] Further, the operating pressure of the high-removing column is 100-300 kpa, the theoretical plate number is 40-60, and the reflux ratio is 30-40; the operating pressure of the low-removing column is 100-300 kpa, the theoretical plate number is 40-60, and the reflux ratio is 50-60; the operating pressure of the light separation column is 100-300 kpa, the theoretical plate number is 40-60, and the reflux ratio is 30-40; the operating pressure of the hydrogen-containing column is 100-300 kpa, the theoretical plate number is 40-60, and the reflux ratio is 1-10; the operating pressure of the trimethyl column is 100-300 kpa, the theoretical plate number is 20-50, and the reflux ratio is 90-100; and the operating pressure of the dimethyl column is 100-300 kpa, the theoretical plate number is 200-300, and the reflux ratio is 70-80.

[0016] Compared with the prior art, the advantages of the present application are that:

[0017] (1) The present application has the beneficial effect of realizing efficient separation of the crude organosilicon monomer mixture by adopting a six-column rectification separation method.

[0018] (2) The present application utilizes the high heat of the high-removing column top steam in the production and separation of the crude organosilicon monomer to realize waste heat recovery and utilization, specifically, the high-removing column top stream is used to first heat the light separation column reboiler, one stream is used to heat the hydrogen-containing column reboiler through the separator, and the other stream is used to heat the dimethyl column reboiler, thereby reducing the heating steam energy consumption of the reboiler and the circulating water cost of the condenser. In general, the high-removing column top steam is used as a heat source to realize energy consumption reduction, and the raw material preheating of the low-removing column bottom stream reduces energy consumption loss.

[0019] (3) The application realizes coupling design, adopts the overhead steam of the high-removing column as the heat source of the light separation column and the hydrogen-containing column, realizes complete heat integration, the remaining heat heats the dimethyl column, the energy consumption is significantly reduced, the application reduces two reboilers and a condenser, saves equipment cost, and the process is simple, and the product purity is high.

[0020] To sum up, the application provides a six-column heat integration rectification method for separating crude organosilicon monomers, which realizes high-purity effective separation of methyltrichlorosilane, dimethyldichlorosilane, trimethylmonochlorosilane and monomethyldichlorosilane, and a significant reduction in separation energy consumption, and the mass fraction of methyltrichlorosilane separated by the system and method is greater than 99.5%, the mass fraction of dimethyldichlorosilane is greater than 99.99%, the mass fraction of trimethylmonochlorosilane is greater than 99.5%, and the mass fraction of monomethyldichlorosilane is greater than 99.5%. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The application is a six-column heat integration rectification device for separating crude organosilicon monomers, and the connection relationship is shown in the figure, and the annotations are as follows: 1-high-removing column; 2-low-removing column; 3-light separation column; 4-hydrogen-containing column; 5-trimethyl column; 6-dimethyl column; 7-separator; 8-mixer; 9-preheater; 10-first heat exchanger; 11-second heat exchanger; 12-third heat exchanger; 13-assisted reboiler; 14-condenser; 15-reboiler. DETAILED DESCRIPTION

[0022] The application will be further described in detail in combination with the embodiments of the drawings. Specific embodiment one

[0024] A six-column heat integration rectification system for separating crude organosilicon monomers, as shown in the figure, includes a high-removing column 1, a low-removing column 2, a light separation column 3, a hydrogen-containing column 4, a trimethyl column 5, a dimethyl column 6, a separator 7 and a mixer 8. Figure 1

[0025] ​The middle raw material inlet of the high-removing column 1 is connected with a preheater 9 through a pipeline, the overhead gas phase outlet of the high-removing column 1 is connected with the inlet of the separator 7 through a first heat exchanger 10, one outlet of the separator 7 is connected with the inlet of the mixer 8 through a second heat exchanger 11, another outlet of the separator 7 is connected with the inlet of the mixer 8 through a third heat exchanger 12, the outlet of the mixer 8 is connected with the overhead reflux inlet of the high-removing column 1 and the middle material inlet of the low-removing column 2 respectively, the overhead material outlet of the low-removing column 2 is connected with the middle material inlet of the light separation column 3, the bottom material outlet of the low-removing column 2 is connected with the middle material inlet of the dimethyl column 6 through the preheater 9, the bottom product outlet of the dimethyl column 6 is connected with the auxiliary reboiler 13 and the third heat exchanger 12 respectively; the bottom material outlet of the light separation column 3 is connected with the middle material inlet of the hydrogen-containing column 4 through the first heat exchanger 10, the bottom material outlet of the hydrogen-containing column 4 is connected with the middle material inlet of the trimethyl column 5 through the second heat exchanger 11.

[0026] In this specific embodiment, the condensers 14 are respectively arranged at the overhead product outlets of the low-removing column 2, the light separation column 3, the hydrogen-containing column 4, the trimethyl column 5 and the dimethyl column 6. The reboilers 15 are respectively arranged at the bottom product outlets of the high-removing column 1, the low-removing column 2 and the trimethyl column 5. The overhead stream of the high-removing column 1 is connected with the first heat exchanger 10, the separator 7, the second heat exchanger 11 and the third heat exchanger 12 in sequence through pipelines in the form of gas phase, to provide heat for the light separation column 3, the hydrogen-containing column 4 and the dimethyl column 6 reboiler 15, and the stream after heat exchange flows back to the overhead of the high-removing column 1 through the mixer 8. The bottom stream of the low-removing column 2 is connected with the heat exchanger through a pipeline in the form of liquid phase to preheat the feed, and the stream after heat exchange enters the dimethyl column 6 through a pipeline, to realize complete heat integration. Specific embodiment two

[0028] A method for separating crude organosilicon monomer by using the six-column heat integrated distillation system of the above specific embodiment one, comprising the following steps

[0029] (1) The crude organosilicon monomer mixture is preheated by the preheater 9 and then enters the high-removing column 1. After being treated by the high-removing column 1, the overhead steam of the high-removing column 1 is heat-exchanged with the first heat exchanger 10 through a pipeline, and then divided into two streams by the separator 7, one of which is heat-exchanged with the second heat exchanger 11, and the other of which is heat-exchanged with the third heat exchanger 12. The two streams are mixed by the mixer 8 after heat exchange, and then part of them flows back to the high-removing column 1, and the other part of them is taken out and enters the low-removing column 2. The high-boiling substances are taken out from the bottom of the high-removing column 1.

[0030] (2) The mixture with a boiling point lower than monomethyl trichlorosilane taken out from the top of the low-removing column 2 is sent into the light separation column 3, and the mixture of monomethyl trichlorosilane and dimethyl dichlorosilane taken out from the bottom of the low-removing column 2 is preheated by the preheater 9 and then enters the dimethyl column 6.

[0031] (3) The low-boiling material with a boiling point lower than monomethyldichlorosilane is taken out from the top of the light fractionating tower 3, and the bottom stream is sent into the hydrogen-containing tower 4 after heat exchange with the overhead steam of the high-removing tower 1 through the first heat exchanger 10;

[0032] (4) The product monomethyldichlorosilane is taken out from the top of the hydrogen-containing tower 4, and the bottom stream is sent into the trimethyl tower 5 after heat exchange with one of the streams separated by the separator 7 through the second heat exchanger 11, and the mixture of trimethylmonochlorosilane and silicon tetrachloride is taken out;

[0033] (5) The azeotrope of trimethylmonochlorosilane and silicon tetrachloride is taken out from the top of the trimethyl tower 5, and the product trimethylmonochlorosilane is taken out from the bottom;

[0034] (6) The product monomethyltrichlorosilane is taken out from the top of the dimethyl tower 6, and the bottom stream is divided into two streams, one of which is returned to the dimethyl tower 6 after heating by the auxiliary reboiler 13, and the other of which is returned to the dimethyl tower 6 after heat exchange with the other stream separated by the separator 7 through the third heat exchanger 12, and the product dimethyldichlorosilane is taken out from the bottom of the dimethyl tower 6.

[0035] The operating pressure of the high-removing tower 1 is 100-300 kPa, the theoretical plate number is 40-60, and the reflux ratio is 30-40; the operating pressure of the low-removing tower 2 is 100-300 kPa, the theoretical plate number is 40-60, and the reflux ratio is 50-60; the operating pressure of the light fractionating tower 3 is 100-300 kPa, the theoretical plate number is 40-60, and the reflux ratio is 30-40; the operating pressure of the hydrogen-containing tower 4 is 100-300 kPa, the theoretical plate number is 40-60, and the reflux ratio is 1-10; the operating pressure of the trimethyl tower 5 is 100-300 kPa, the theoretical plate number is 20-50, and the reflux ratio is 90-100; and the operating pressure of the dimethyl tower 6 is 100-300 kPa, the theoretical plate number is 200-300, and the reflux ratio is 70-80.

[0036] Example 1

[0037] The feed temperature is 25℃, the feed flow rate is 28582 kg / h, the pressure is 1 atm (absolute pressure), the feed contains 8% methyltrichlorosilane, 80% dimethyldichlorosilane, 2.8% trimethylmonochlorosilane and 3.2% monomethyldichlorosilane (mass fraction), the overhead stream of the de-elevating column 1 is connected to the first heat exchanger 10, the second heat exchanger 11 and the third heat exchanger 12 in the form of a gas phase, and supplies heat to the reboiler 15 of the light separation column 3, the hydrogen-containing column 4 and the dimethyl column 6, and after heat exchange, the stream flows back to the overhead of the de-elevating column 1 through a pipeline; the bottom stream of the de-elevating column 1 is connected to the heat exchanger in the form of a liquid phase, and preheats the feed; the operating pressure of the de-elevating column 1 is 150 kpa, the theoretical plate number is 75, and the reflux ratio is 2; the operating pressure of the de-elevating column 2 is 200 kpa, the theoretical plate number is 215, and the reflux ratio is 51; the operating pressure of the light separation column 3 is 220 kpa, the theoretical plate number is 120, and the reflux ratio is 38; the operating pressure of the hydrogen-containing column 4 is 150 kpa, the theoretical plate number is 100, and the reflux ratio is 5; the operating pressure of the trimethyl column 5 is 150 kpa, the theoretical plate number is 70, and the reflux ratio is 100; the operating pressure of the dimethyl column 6 is 100 kpa, the theoretical plate number is 450, and the reflux ratio is 75; after separation, the mass fraction of methyltrichlorosilane is 99.9%, and the recovery rate is 99.04%; after separation, the mass fraction of dimethyldichlorosilane is 99.99%, and the recovery rate is 99.24%; after separation, the mass fraction of trimethylmonochlorosilane is 99.8%, and the recovery rate is 84.4%; after separation, the mass fraction of monomethyldichlorosilane is 99.9%, and the recovery rate is 98.9%; compared with the traditional process, the entire process saves energy by 55.3%.

[0038] After the preheater 9, the feed temperature rises to 53℃, and the temperature of the bottom stream of the de-elevating column 2 drops to 55℃; after heat exchange in the first heat exchanger 10, the temperature of the vaporized bottom stream of the light separation column 3 is 74.9℃, and the temperature of the condensed overhead stream of the de-elevating column 1 is 81.1℃; after heat exchange in the second heat exchanger 11, the temperature of the vaporized bottom stream of the hydrogen-containing column 4 is 70.5℃, and the temperature of the condensed overhead stream of the de-elevating column 1 is 78.7℃; after heat exchange in the third heat exchanger 12, the temperature of the vaporized bottom stream of the dimethyl column 6 is 69.7℃, and the temperature of the completely condensed overhead stream of the de-elevating column 1 is 78.7℃.

[0039] Example 2

[0040] The feed temperature is 25℃, the feed flow rate is 28582 kg / h, the pressure is 1 atm (absolute pressure), the feed contains 8% methyltrichlorosilane, 80% dimethyldichlorosilane, 2.8% trimethylmonochlorosilane and 3.2% monomethyldichlorosilane (mass fraction), the overhead stream of the de-elevating column 1 is connected to the first heat exchanger 10, the second heat exchanger 11 and the third heat exchanger 12 in the form of gas phase, providing heat for the reboiler 15 of the light separation column 3, the hydrogen-containing column 4 and the dimethyl column 6, and the stream after heat exchange flows back to the overhead of the de-elevating column 1 through the pipeline; the bottom stream of the de-elevating column 1 is connected to the heat exchanger in the form of liquid phase, providing preheating for the feed; the operating pressure of the de-elevating column 1 is 150 kpa, the theoretical plate number is 80, and the reflux ratio is 5; the operating pressure of the de-elevating column 2 is 200 kpa, the theoretical plate number is 220, and the reflux ratio is 55; the operating pressure of the light separation column 3 is 220 kpa, the theoretical plate number is 130, and the reflux ratio is 38; the operating pressure of the hydrogen-containing column 4 is 150 kpa, the theoretical plate number is 110, and the reflux ratio is 6; the operating pressure of the trimethyl column 5 is 150 kpa, the theoretical plate number is 80, and the reflux ratio is 95; the operating pressure of the dimethyl column 6 is 100 kpa, the theoretical plate number is 480, and the reflux ratio is 78; the mass fraction of the separated methyltrichlorosilane is 99.92%, and the recovery rate is 99.21%; the mass fraction of the separated dimethyldichlorosilane is 99.99%, and the recovery rate is 99.31%; the mass fraction of the separated trimethylmonochlorosilane is 99.9%, and the recovery rate is 85.5%; the mass fraction of the separated monomethyldichlorosilane is 99.9%, and the recovery rate is 99.1%; compared with the traditional process, the whole process saves energy by 52.1%.

[0041] After the preheater 9, the feed temperature rises to 51℃, and the temperature of the bottom stream of the de-elevating column 2 drops to 54℃; after the first heat exchanger 10, the temperature of the vaporized bottom stream of the light separation column 3 is 73.8℃, and the temperature of the condensed overhead stream of the de-elevating column 1 is 79.6℃; after the second heat exchanger 11, the temperature of the vaporized bottom stream of the hydrogen-containing column 4 is 70.5℃, and the temperature of the condensed overhead stream of the de-elevating column 1 is 78.7℃; after the third heat exchanger 12, the temperature of the vaporized bottom stream of the dimethyl column 6 is 69.9℃, and the temperature of the completely condensed overhead stream of the de-elevating column 1 is 78.7℃.

[0042] Example 3

[0043] The feed temperature is 25℃, the feed flow rate is 28582 kg / h, the pressure is 1 atm (absolute pressure), the feed contains 8% methyltrichlorosilane, 80% dimethyldichlorosilane, 2.8% trimethylmonochlorosilane and 3.2% monomethyldichlorosilane (mass fraction), the overhead stream of the high-removing column 1 is connected with the first heat exchanger 10, the second heat exchanger 11 and the third heat exchanger 12 in the form of gas phase, and supplies heat to the reboiler 15 of the light separation column 3, the hydrogen-containing column 4 and the dimethyl column 6, and the stream after heat exchange flows back to the overhead of the high-removing column 1 through the pipeline; the bottom stream of the low-removing column 2 is connected with the heat exchanger in the form of liquid phase, and preheats the feed; the operating pressure of the high-removing column 1 is 150 kpa, the theoretical plate number is 50, and the reflux ratio is 7; the operating pressure of the low-removing column 2 is 200 kpa, the theoretical plate number is 200, and the reflux ratio is 50; the operating pressure of the light separation column 3 is 220 kpa, the theoretical plate number is 130, and the reflux ratio is 40; the operating pressure of the hydrogen-containing column 4 is 150 kpa, the theoretical plate number is 100, and the reflux ratio is 7; the operating pressure of the trimethyl column 5 is 150 kpa, the theoretical plate number is 70, and the reflux ratio is 90; the operating pressure of the dimethyl column 6 is 100 kpa, the theoretical plate number is 430, and the reflux ratio is 70; the mass fraction of the separated methyltrichlorosilane is 99.75%, and the recovery rate is 98.1%; the mass fraction of the separated dimethyldichlorosilane is 99.99%, and the recovery rate is 99.22%; the mass fraction of the separated trimethylmonochlorosilane is 99.78%, and the recovery rate is 89.5%; the mass fraction of the separated monomethyldichlorosilane is 99.92%, and the recovery rate is 98.5%; compared with the traditional process, the whole process saves energy by 55.1%.

[0044] After the preheater 9, the feed temperature is increased to 53℃, and the bottom stream temperature of the low-removing column 2 is decreased to 57℃; after the first heat exchanger 10, the vaporized bottom stream temperature of the light separation column 3 is 75.2℃, and the condensed overhead stream temperature of the high-removing column 1 is 82.4℃; after the second heat exchanger 11, the vaporized bottom stream temperature of the hydrogen-containing column 4 is 71.5℃, and the condensed overhead stream temperature of the high-removing column 1 is 78.7℃; after the third heat exchanger 12, the vaporized bottom stream temperature of the dimethyl column 6 is 68.8℃, and the completely condensed overhead stream temperature of the high-removing column 1 is 78.7℃.

[0045] The above description is not a limitation of the present application, and the present application is not limited to the above examples. Changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present application shall also fall within the protection scope of the present application.

Claims

1. A system for separating crude organosilicon monomers by six-tower integrated thermal distillation, characterized in that: The system includes a high-efficiency removal tower, a low-efficiency removal tower, a light separation tower, a hydrogen-containing tower, a methyl methacrylate (MMA) tower, a dimethyl methacrylate (DMMA) tower, a separator, and a mixer. The high-efficiency removal tower has a preheater connected to its central feed inlet via a pipeline. The gas phase outlet at the top of the high-efficiency removal tower is connected to the inlet of the separator via a first heat exchanger. One outlet of the separator is connected to the inlet of the mixer via a second heat exchanger, and the other outlet of the separator is connected to the inlet of the mixer via a third heat exchanger. The outlet of the mixer is connected to the reflux port at the top of the high-efficiency removal tower and the central outlet of the low-efficiency removal tower. The material inlet of the first heat exchanger is connected to the middle material inlet of the second heat exchanger. The material outlet of the first heat exchanger is connected to the middle material inlet of the third heat exchanger. The material outlet of the second heat exchanger is connected to the auxiliary reboiler and the third heat exchanger. The material outlet of the bottom material of the first heat exchanger is connected to the middle material inlet of the hydrogen-containing tower. The material outlet of the bottom material of the hydrogen-containing tower is connected to the middle material inlet of the third heat exchanger. Includes the following steps (1) The mixture of crude organosilicon monomers is preheated by a preheater and then enters the de-boiling tower. After being processed by the de-boiling tower, the steam at the top of the de-boiling tower exchanges heat with the first heat exchanger through a pipeline. Then, it is separated into two streams by a separator. One stream exchanges heat with the second heat exchanger and the other stream exchanges heat with the third heat exchanger. After the two streams exchange heat, they are mixed by a mixer. Then, part of the stream is returned to the de-boiling tower and part is collected and enters the de-boiling tower. High-boiling substances are collected from the bottom of the de-boiling tower. (2) The mixture with a boiling point lower than monomethyltrichlorosilane collected from the top of the de-lowering tower is fed into the light separation tower. The mixture of monomethyltrichlorosilane and dimethyldichlorosilane collected from the bottom of the de-lowering tower is preheated by the preheater and then fed into the dimethyl tower. (3) The top of the light separation tower is taken out as a low-boiling substance with a boiling point lower than that of monomethyldichlorosilane, and the bottom stream is sent to the hydrogen-containing tower after exchanging heat with the top steam of the de-heating tower through the first heat exchanger. (4) The product monomethyldichlorosilane is collected from the top of the hydrogen-containing tower. The bottom stream is exchanged with a stream separated by the separator in the second heat exchanger. The mixture of collected trimethyldichlorosilane and silicon tetrachloride is then sent to the trimethyldichlorosilane tower. (5) The azeotrope of trimethylchlorosilane and silicon tetrachloride is collected from the top of the three-methyl tower, and the product trimethylchlorosilane is collected from the bottom of the tower. (6) The product monomethyltrichlorosilane is collected from the top of the dimethyl dichlorosilane tower, and the bottom stream is divided into two streams. One stream is heated by the auxiliary reboiler and returned to the dimethyl dichlorosilane tower. The other stream is heated by the third heat exchanger and returned to the dimethyl dichlorosilane tower after exchanging heat with the other stream separated by the separator. The product dimethyldichlorosilane is collected from the bottom of the dimethyl dichlorosilane tower. The operating pressure of the high-pressure removal tower is 100-300 kPa, the theoretical number of trays is 40-60, and the reflux ratio is 30-40; the operating pressure of the low-pressure removal tower is 100-300 kPa, the theoretical number of trays is 40-60, and the reflux ratio is 50-60; the operating pressure of the light fractionation tower is 100-300 kPa, the theoretical number of trays is 40-60, and the reflux ratio is 30-40; the operating pressure of the hydrogen-containing tower is 100-300 kPa, the theoretical number of trays is 40-60, and the reflux ratio is 1-10; the operating pressure of the methyl methacrylate (MDMA) tower is 100-300 kPa, the theoretical number of trays is 20-50, and the reflux ratio is 90-100; the operating pressure of the dimethyl methacrylate (DMMA) tower is 100-300 kPa, the theoretical number of trays is 200-300, and the reflux ratio is 70-80.

2. The system for separating crude organosilicon monomers by six-tower integrated thermal distillation according to claim 1, characterized in that: Condensers are respectively installed at the product outlets of the top of the aforementioned de-oxidation tower, light fractionation tower, hydrogen-containing tower, methyl methacrylate tower, and dimethyl methacrylate tower.

3. The system for separating crude organosilicon monomers by six-tower thermal integrated distillation according to claim 1, characterized in that: Each of the high-density stripping tower, the low-density stripping tower, and the ternary ammonium chloride tower is equipped with a reboiler at the bottom product outlet.

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