CN115591258A - System and method for separating organic silicon crude monomer by six-tower heat integration rectification - Google Patents

System and method for separating organic silicon crude monomer by six-tower heat integration rectification Download PDF

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Publication number
CN115591258A
CN115591258A CN202210996344.7A CN202210996344A CN115591258A CN 115591258 A CN115591258 A CN 115591258A CN 202210996344 A CN202210996344 A CN 202210996344A CN 115591258 A CN115591258 A CN 115591258A
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tower
heat exchanger
boiling
heat
dimethyl
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李全
李鑫
刘新安
谷新春
李国华
李浩博
何欣蔚
吕龙辉
姜磊
刘福东
任倩茹
柴新刚
李国民
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SEDIN NINGBO ENGINEERING CO LTD
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SEDIN NINGBO ENGINEERING CO LTD
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/007—Energy recuperation; Heat pumps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/143—Fractional distillation or use of a fractionation or rectification column by two or more of a fractionation, separation or rectification step
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/14—Fractional distillation or use of a fractionation or rectification column
    • B01D3/32—Other features of fractionating columns ; Constructional details of fractionating columns not provided for in groups B01D3/16 - B01D3/30
    • B01D3/322—Reboiler specifications
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/08—Compounds containing halogen
    • C01B33/107—Halogenated silanes
    • C01B33/1071—Tetrachloride, trichlorosilane or silicochloroform, dichlorosilane, monochlorosilane or mixtures thereof
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/08—Compounds containing halogen
    • C01B33/107—Halogenated silanes
    • C01B33/10778—Purification
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/12—Organo silicon halides
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/20—Purification, separation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

Abstract

The invention discloses a system and a method for separating crude organic silicon monomers by six-tower heat integration rectification, which are characterized by comprising a high-removing tower, a low-removing tower, a light component tower, a hydrogen-containing tower, a trimethyl tower, a dimethyl tower, a separator and a mixer; the high-pressure removal tower is connected with a preheater through a pipeline, a gas phase outlet at the top of the high-pressure removal tower is connected with an inlet of a separator through a first heat exchanger, one outlet of the separator is connected with an inlet of a mixer through a second heat exchanger, the other outlet of the separator is connected with an inlet of the mixer through a third heat exchanger, outlets of the mixer are respectively connected with the high-pressure removal tower and a low-pressure removal tower, the low-pressure removal tower is connected with a light component tower, the low-pressure removal tower is connected with a second tower through the preheater, and a product outlet at the bottom of the second tower is respectively connected with an auxiliary reboiler and the third heat exchanger; the light component tower is connected with the hydrogen-containing tower through the first heat exchanger, and the hydrogen-containing tower is connected with the trimethyl tower through the second heat exchanger.

Description

System and method for separating organic silicon crude monomer by six-tower heat integration rectification
Technical Field
The invention belongs to the field of chemical separation and purification, and particularly relates to a device and a method for separating organic silicon crude monomers by six-tower heat integration rectification.
Background
Organosilicon is a novel material with excellent performance and unique function, can be used as a basic material and a structural material in some large industries, and can be used as a functional material to be added with other materials to improve the process performance, thereby gaining the reputation of industrial monosodium glutamate and a scientific and technological development catalyst.
The preparation of organosilicon materials is not independent of organosilicon monomers, and methylchlorosilanes, especially dimethyldichlorosilane, are the most important and most used organosilicon monomers. No matter which method is adopted to produce the methyl chlorosilane, the methyl chlorosilane is a multi-component mixture, and a series of problems of more monomer components, small boiling point difference, difficult separation and purification and the like exist. In the production of the organic silicon monomer, a rectification unit is a large steam consumption household. The industrial separation and purification of methyl chlorosilane generally adopts 7 to 10 rectifying towers, wherein the 1 st tower is generally a high-removing tower, and the sequence of the later towers is different according to different separation sequences, and comprises a seven-tower process, a cis-cutting process, a trans-cutting process, a middle-cutting process and the like. When the same product purity requirement is met, the yield of each main monomer in the 4 processes is not greatly different, wherein the energy consumption of the middle cutting process is the lowest, and the energy consumption of the cis cutting separation process is the highest. The product purity and yield of the 7-tower process are low, and the industrial requirement is difficult to reach. These several separation sequences are mainly improvements made on the 7-column process. The 7-tower process mainly comprises a high-removing tower, a low-removing tower, a light component tower, a hydrogen-containing tower, an azeotropic tower, a trimethyl tower and a dimethyl tower. At present, a 6-tower separation process (traditional process) is established by changing a 7-tower process, and mainly when first methanol, second methanol and other substances are separated in a low-boiling tower, the first methanol and the second methanol are all introduced into a second methanol tower as far as possible, and qualified trimethyl product is extracted from the bottom of an azeotropic tower. Although the 6-tower process is simpler and more convenient than the 7-tower process, the problem of high energy consumption still exists, mainly because the steam enters the reboiler of each tower for heat exchange, and then most of the steam becomes nearly saturated same-temperature and same-pressure condensed water through the drain valve, and part of the steam enters the recovery tank for flash evaporation to become exhaust steam with lower utilization value, and the part of the steam cannot be utilized and needs to be condensed for recovery, so that the cost is increased, and the problem of difficult separation and the like are caused due to instability. It is therefore important to find a process technology that reduces the investment costs and the operating energy consumption even more.
Disclosure of Invention
The invention aims to solve the technical problem of providing a system and a method for separating crude organosilicon monomers by six-tower heat integration rectification, which realize high-purity separation of crude organosilicon monomers and greatly reduce production energy consumption.
The technical scheme adopted by the invention for solving the technical problems is as follows: a system for separating crude organic silicon monomers by six-tower heat integration rectification comprises a high-removing tower, a low-removing tower, a light component tower, a hydrogen-containing tower, a trimethyl tower, a dimethyl tower, a separator and a mixer; the middle raw material inlet of the high-pressure component removing tower is connected with a preheater through a pipeline, the top gas phase outlet of the high-pressure component removing tower is connected with the inlet of the separator through a first heat exchanger, one outlet of the separator is connected with the inlet of the mixer through a second heat exchanger, the other outlet of the separator is connected with the inlet of the mixer through a third heat exchanger, the outlet of the mixer is respectively connected with the top reflux port of the high-pressure component removing tower and the middle material inlet of the low-pressure component removing tower, the top material outlet of the low-pressure component removing tower is connected with the middle material inlet of the light component removing tower, the bottom material outlet of the low-pressure component removing tower is connected with the middle material inlet of the second tower through the preheater, and the bottom product outlet of the second tower is respectively connected with an auxiliary reboiler and the third heat exchanger; the tower bottom material outlet of the light component tower is connected with the middle material inlet of the hydrogen-containing tower through the first heat exchanger, and the tower bottom material outlet of the hydrogen-containing tower is connected with the middle material inlet of the trimethyl tower through the second heat exchanger.
Further, the tower top product outlets of the low-boiling point removal tower, the light component tower, the hydrogen-containing tower, the trimethyl tower and the dimethyl tower are respectively provided with a condenser.
Furthermore, reboiler are respectively arranged at the product outlets at the bottom of the high-removing tower, the low-removing tower and the trimethyl tower.
A method for separating crude organosilicon monomers by utilizing six-tower heat-integrated rectification of the system comprises the following steps
(1) Preheating an organosilicon crude monomer mixture by a preheater, feeding the organosilicon crude monomer mixture into a high-boiling-point removal tower, treating the organosilicon crude monomer mixture by the high-boiling-point removal tower, dividing steam at the top of the high-boiling-point removal tower into two streams by a separator after the steam exchanges heat with a first heat exchanger through a pipeline, exchanging heat with a second heat exchanger by one stream, exchanging heat with a third heat exchanger by the other stream, mixing the two streams by a mixer after the two streams exchange heat, refluxing a part of the mixture to the high-boiling-point removal tower, extracting a part of the mixture to enter a low-boiling-point removal tower, and extracting a high-boiling-point substance at the bottom of the high-boiling-point removal tower;
(2) Feeding a mixture with a boiling point lower than that of the monomethyl trichlorosilane extracted from the top of the low-boiling component removing tower into a light component removing tower, extracting a mixture of the monomethyl trichlorosilane and the dimethyl dichlorosilane from the bottom of the low-boiling component removing tower, preheating the feed by a preheater, and feeding the preheated feed into a dimethyl tower;
(3) Extracting low-boiling-point substances with the boiling point lower than that of the monomethyldichlorosilane from the top of the light component tower, and sending a tower bottom into a hydrogen-containing tower after heat exchange is carried out between the tower bottom and steam at the top of the high-component tower through a first heat exchanger;
(4) The product of the monomethyldichlorosilane is extracted from the top of the hydrogen-containing tower, the bottom material flows through a second heat exchanger to exchange heat with a material flow separated by a separator, and the extracted mixture of trimethylchlorosilane and silicon tetrachloride is sent into a trimethyl tower;
(5) An azeotrope of trimethylchlorosilane and silicon tetrachloride is extracted from the top of a trimethyl tower, and a product of trimethylchlorosilane is extracted from the bottom of the trimethyl tower;
(6) And (3) extracting a product namely the monomethyl trichlorosilane from the top of the dimethyl tower, dividing the material flow at the bottom of the dimethyl tower into two streams, heating one stream by an auxiliary reboiler and then returning the heated stream to the dimethyl tower, exchanging heat between the other stream separated by the separator and the one stream by a third heat exchanger and then returning the heated stream to the dimethyl tower, and extracting a product namely the dimethyldichlorosilane from the bottom of the dimethyl tower.
Further, the operating pressure of the high-pressure removal tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 30-40; the operating pressure of the low-boiling component removing tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 50-60; the operating pressure of the light component tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 30-40; the operating pressure of the hydrogen-containing tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 1-10; the operating pressure of the trimethyl tower is 100-300 kpa, the number of theoretical plates is 20-50, and the reflux ratio is 90-100; the operating pressure of the dimethyl tower is 100-300 kpa, the number of theoretical plates is 200-300, and the reflux ratio is 70-80.
Compared with the prior art, the invention has the advantages that:
(1) The invention has the beneficial effect that the high-efficiency separation of the organosilicon crude monomer mixture is realized by adopting a six-tower rectification separation method.
(2) The invention utilizes the high heat of the tower top steam of a high-removing tower in the production and separation of crude organosilicon monomers to recycle the waste heat, and particularly, the invention adopts the tower top material flow of the high-removing tower to supply heat to a reboiler of a light-weight separation tower firstly, one part of the tower top material flow passes through a separator to supply heat to the reboiler of a hydrogen-containing tower, and the other part of the tower top material flow supplies heat to a reboiler of a dimethyl tower, thereby reducing the energy consumption of the heating steam of the reboiler and the cost of circulating water of a condenser.
(3) The invention realizes the coupling design, adopts the tower top steam of the high-pressure removal tower as the heat source of the light component tower and the hydrogen-containing tower, realizes the complete heat integration, heats the dimethyl tower by the residual heat, obviously reduces the energy consumption, reduces two reboilers and one condenser, saves the equipment cost, and has simple process and high product purity.
In conclusion, the invention provides a method for separating crude organosilicon monomers by six-tower heat-integration rectification, which can realize high-purity effective separation of mono-methyl trichlorosilane, dimethyl dichlorosilane, trimethyl chlorosilane and mono-methyl dichlorosilane and greatly reduce the separation energy consumption by utilizing six towers for rectification separation, wherein the mass fraction of the mono-methyl trichlorosilane, the mass fraction of the dimethyl dichlorosilane, the mass fraction of the trimethyl chlorosilane and the mass fraction of the mono-methyl dichlorosilane are respectively more than 99.5%, more than 99.99%, more than 99.5% and more than 99.5% after the separation by using the system and the method.
Drawings
FIG. 1 is a schematic connection diagram of a six-tower heat-integrated distillation device for separating crude organosilicon monomers; each is labeled as follows: 1-a high-removing tower; 2-a depower; 3-light fraction tower; 4-a hydrogen-containing column; 5-trimethyl tower; 6-dimethyl tower; 7-a separator; 8-a mixer; 9-a preheater; 10-a first heat exchanger; 11-a second heat exchanger; 12-a third heat exchanger; 13-an auxiliary reboiler; 14-a condenser; 15-reboiler.
Detailed Description
The invention is described in further detail below with reference to the accompanying examples.
Detailed description of the preferred embodiment
A system for separating crude organic silicon monomers by six-tower heat integration rectification is shown in figure 1 and comprises a high-removing tower 1, a low-removing tower 2, a light component tower 3, a hydrogen-containing tower 4, a trimethyl tower 5, a dimethyl tower 6, a separator 7 and a mixer 8;
the middle raw material inlet of the high-boiling component removing tower 1 is connected with a preheater 9 through a pipeline, the top gas phase outlet of the high-boiling component removing tower 1 is connected with the inlet of a separator 7 through a first heat exchanger 10, one outlet of the separator 7 is connected with the inlet of a mixer 8 through a second heat exchanger 11, the other 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 respectively connected with the top reflux port of the high-boiling component removing tower 1 and the middle material inlet of the low-boiling component removing tower 2, the top material outlet of the low-boiling component removing tower 2 is connected with the middle material inlet of the light component removing tower 3, the bottom material outlet of the low-boiling component removing tower 2 is connected with the middle material inlet of the second boiling component removing tower 6 through the preheater 9, and the bottom product outlet of the second boiling component removing tower 6 is respectively connected with an auxiliary reboiler 13 and the third heat exchanger 12; the material outlet at the bottom of the light component tower 3 is connected with the material inlet at the middle part of the hydrogen-containing tower 4 through a first heat exchanger 10, and the material outlet at the bottom of the hydrogen-containing tower 4 is connected with the material inlet at the middle part of the trimethyl tower 5 through a second heat exchanger 11.
In this embodiment, condensers 14 are provided at the top product outlets of the dephlegmator 2, the fractionator 3, the hydrogenerator 4, the trimethanizer 5 and the dimethy tower 6, respectively. Reboiler 15 is respectively arranged at the product outlets at the bottoms of the high-removing tower 1, the low-removing tower 2 and the trimethyl tower 5. The material flow at the top of the high-pressure-removing tower 1 is sequentially connected with a first heat exchanger 10, a separator 7, a second heat exchanger 11 and a third heat exchanger 12 through pipelines in a gas phase mode to supply heat to a light-weight-separating tower 3, a hydrogen-containing tower 4 and a reboiler 15 of a dimethyl tower 6, the material flow after heat exchange flows back to the top of the high-pressure-removing tower 1 through a mixer 8 through a pipeline, the material flow at the bottom of the low-pressure-removing tower 2 is connected with the heat exchanger through a pipeline in a liquid phase mode to preheat feeding materials, and the material flow after heat exchange enters the dimethyl tower 6 through a pipeline to realize complete heat integration.
Detailed description of the invention
A method for separating crude organosilicon monomers by utilizing six-tower heat integration rectification of the system of the embodiment I comprises the following steps
(1) Preheating an organosilicon crude monomer mixture by a preheater 9, feeding the organosilicon crude monomer mixture into a high-boiling-point removal tower 1, treating the organosilicon crude monomer mixture by the high-boiling-point removal tower 1, then, after heat exchange between steam at the top of the high-boiling-point removal tower 1 and a first heat exchanger 10 through a pipeline, dividing the steam into two streams by a separator 7, exchanging heat between one stream and a second heat exchanger 11, exchanging heat between the other stream and a third heat exchanger 12, mixing the two streams by a mixer 8 after heat exchange, then refluxing a part of the mixed streams to the high-boiling-point removal tower 1, extracting a part of the mixed streams to enter a low-boiling-point removal tower 2, and extracting a high-boiling-point substance at the bottom of the high-boiling-point removal tower 1;
(2) The mixture with the boiling point lower than that of the monomethyl trichlorosilane extracted from the top of the low-boiling component removing tower 2 is sent into a light component tower 3, the mixture of the monomethyl trichlorosilane and the dimethyl dichlorosilane extracted from the bottom of the low-boiling component removing tower 2 is preheated by a preheater 9 and then enters a dimethyl tower 6;
(3) Extracting low-boiling-point substances with the boiling point lower than that of the monomethyldichlorosilane from the top of the light component tower 3, and sending tower bottoms to a hydrogen-containing tower 4 after heat exchange is carried out between the tower bottoms and steam at the top of the high-boiling-point removal tower 1 through a first heat exchanger 10;
(4) The product of the monomethyl dichlorosilane is extracted from the top of the hydrogen-containing tower 4, the bottom of the tower flows through a second heat exchanger 11 to exchange heat with a material flow separated by a separator 7, and the extracted mixture of trimethyl monochlorosilane and silicon tetrachloride is sent to a trimethyl tower 5;
(5) An azeotrope of trimethylchlorosilane and silicon tetrachloride is extracted from the top of a trimethyl tower 5, and a product of the trimethylchlorosilane is extracted from the bottom of the trimethyl tower;
(6) The product monomethyl trichlorosilane is extracted from the top of the dimethyl tower 6, the material flow at the bottom of the dimethyl tower is divided into two flows, one flow is heated by an auxiliary reboiler 13 and then returns to the dimethyl tower 6, the other flow is subjected to heat exchange by a third heat exchanger 12 and the other flow separated by a separator 7 and then returns to the dimethyl tower 6, and the product dimethyl dichlorosilane is extracted from the bottom of the dimethyl tower 6.
The operating pressure of the high-altitude removing tower 1 is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 30-40; the operation pressure of the low-boiling component removing tower 2 is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 50-60; the operating pressure of the light component tower 3 is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 30-40; the operation pressure of the hydrogen-containing tower 4 is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 1-10; the operating pressure of the trimethyl tower 5 is 100-300 kpa, the number of theoretical plates is 20-50, and the reflux ratio is 90-100; the operating pressure of the dimethyl tower 6 is 100-300 kpa, the number of theoretical plates is 200-300, and the reflux ratio is 70-80.
Example 1
The feeding temperature is 25 ℃, the feeding flow is 28582 kg/h, the pressure is 1 atm (absolute pressure), the feeding contains 8 percent of methyl trichlorosilane, 80 percent of dimethyl dichlorosilane, 2.8 percent of trimethyl monochlorosilane, 3.2 percent of methyl dichlorosilane and other substances, the material flow at the top of the high-removal tower 1 is respectively connected with a first heat exchanger 10, a second heat exchanger 11 and a third heat exchanger 12 through pipelines in a gas phase mode, heat is supplied to a light-weight separation tower 3, a hydrogen-containing tower 4 and a dimethyl tower 6 reboiler 15, the material flow after heat exchange flows back to the top of the high-removal tower 1 through the pipelines, the material flow at the bottom of the low-removal tower 2 is connected with the heat exchangers through the pipelines in a liquid phase mode, and the feeding is preheated; the operating pressure of the high-boiling component removing tower 1 is 150 kpa, the number of theoretical plates is 75, and the reflux ratio is 2; the operating pressure of the lower removing tower 2 is 200 kpa, the number of theoretical plates is 215, and the reflux ratio is 51; the operating pressure of the light ends column 3 is 220 kpa, the theoretical plate number is 120, and the reflux ratio is 38; the operating pressure of the hydrogenous tower 4 is 150 kpa, the number of theoretical plates is 100, and the reflux ratio is 5; the operating pressure of the trimethyl tower 5 is 150 kpa, the theoretical plate number is 70, and the reflux ratio is 100; the operating pressure of the dimethyl tower 6 is 100 kpa, the theoretical plate number is 450, and the reflux ratio is 75; the mass fraction of the separated methyl trichlorosilane is 99.9 percent, and the recovery rate is 99.04 percent; the mass fraction of the separated dimethyldichlorosilane is 99.99 percent, and the recovery rate is 99.24 percent; the mass fraction of the separated trimethylchlorosilane is 99.8 percent, and the recovery rate is 84.4 percent; the mass fraction of the separated monomethyl dichlorosilane is 99.9%, the recovery rate is 98.9%, and the whole process can save energy by 55.3% compared with the traditional process.
After passing through a preheater 9, the feeding temperature is increased to 53 ℃, and the temperature of the bottom stream of the lower tower 2 is reduced to 55 ℃; after heat exchange is carried out by a first heat exchanger 10, the temperature of the bottom material flow of the light component tower 3 after vaporization is 74.9 ℃, and the temperature of the top material flow of the condensed high-removing tower 1 is 81.1 ℃; after heat exchange is carried out by a second heat exchanger 11, the temperature of the bottom material flow of the hydrogen-containing tower 4 after vaporization is 70.5 ℃, and the temperature of the top material flow of the condensed high-removing tower 1 is 78.7 ℃; after heat exchange by the third heat exchanger 12, the temperature of the bottom stream of the vaporized dimethyl tower 6 is 69.7 ℃, and the temperature of the top stream of the completely condensed height removing tower 1 is 78.7 ℃.
Example 2
The feeding temperature is 25 ℃, the feeding flow is 28582 kg/h, the pressure is 1 atm (absolute pressure), the feeding contains materials such as 8% of methyl trichlorosilane, 80% of dimethyl dichlorosilane, 2.8% of trimethyl monochlorosilane and 3.2% of methyl dichlorosilane (mass fraction), the material flow at the top of the high-removal tower 1 is respectively connected with a first heat exchanger 10, a second heat exchanger 11 and a third heat exchanger 12 through pipelines in a gas phase manner, heat is supplied to a light-weight separation tower 3, a hydrogen-containing tower 4 and a dimethyl tower 6 reboiler 15, the material flow flows back to the top of the high-removal tower 1 through the pipelines after heat exchange, the material flow at the bottom of the low-removal tower 2 is connected with the heat exchanger through the pipelines in a liquid phase manner, and the feeding is preheated; the operation pressure of the high-boiling component removing tower 1 is 150 kpa, the number of theoretical plates is 80, and the reflux ratio is 5; the operation pressure of the low-boiling component removing tower 2 is 200 kpa, the number of theoretical plates is 220, and the reflux ratio is 55; the operating pressure of the light component tower 3 is 220 kpa, the number of theoretical plates is 130, and the reflux ratio is 38; the operating pressure of the hydrogenous tower 4 is 150 kpa, the number of theoretical plates is 110, and the reflux ratio is 6; the operating pressure of the trimethyl tower 5 is 150 kpa, the theoretical plate number is 80, and the reflux ratio is 95; the operating pressure of the dimethyl tower 6 is 100 kpa, the number of theoretical plates is 480, and the reflux ratio is 78; the mass fraction of the separated monomethyltrichlorosilane is 99.92 percent, and the recovery rate is 99.21 percent; the mass fraction of the separated dimethyldichlorosilane is 99.99 percent, and the recovery rate is 99.31 percent; the mass fraction of the separated trimethylchlorosilane is 99.9 percent, and the recovery rate is 85.5 percent; the mass fraction of the separated monomethyl dichlorosilane is 99.9%, the recovery rate is 99.1%, and the whole process can save 52.1% of energy compared with the traditional process.
After passing through a preheater 9, the feeding temperature is raised to 51 ℃, and the temperature of the bottom stream of the lower tower 2 is reduced to 54 ℃; after heat exchange is carried out by the first heat exchanger 10, the temperature of the bottom material flow of the vaporized light component tower 3 is 73.8 ℃, and the temperature of the top material flow of the condensed high-removing tower 1 is 79.6 ℃; after heat exchange is carried out by a second heat exchanger 11, the temperature of the bottom material flow of the hydrogen-containing tower 4 after vaporization is 70.5 ℃, and the temperature of the top material flow of the condensed high-removing tower 1 is 78.7 ℃; after heat exchange by the third heat exchanger 12, the temperature of the bottom stream of the vaporized dimethyl tower 6 is 69.9 ℃, and the temperature of the top stream of the completely condensed height removing tower 1 is 78.7 ℃.
Example 3
The feeding temperature is 25 ℃, the feeding flow is 28582 kg/h, the pressure is 1 atm (absolute pressure), the feeding contains materials such as 8% of methyl trichlorosilane, 80% of dimethyl dichlorosilane, 2.8% of trimethyl monochlorosilane and 3.2% of methyl dichlorosilane (mass fraction), the material flow at the top of the high-removal tower 1 is respectively connected with a first heat exchanger 10, a second heat exchanger 11 and a third heat exchanger 12 through pipelines in a gas phase manner, heat is supplied to a light-weight separation tower 3, a hydrogen-containing tower 4 and a dimethyl tower 6 reboiler 15, the material flow flows back to the top of the high-removal tower 1 through the pipelines after heat exchange, the material flow at the bottom of the low-removal tower 2 is connected with the heat exchanger through the pipelines in a liquid phase manner, and the feeding is preheated; the operation pressure of the high-boiling component removing tower 1 is 150 kpa, the theoretical plate number is 50, and the reflux ratio is 7; the operation pressure of the lower removing tower 2 is 200 kpa, the number of theoretical plates is 200, and the reflux ratio is 50; the operating pressure of the light ends column 3 is 220 kpa, the theoretical plate number is 130, and the reflux ratio is 40; the operating pressure of the hydrogenous tower 4 is 150 kpa, the number of theoretical plates is 100, and the reflux ratio is 7; the operating pressure of the trimethyl tower 5 is 150 kpa, the theoretical plate number is 70, and the reflux ratio is 90; the operating pressure of the dimethyl tower 6 is 100 kpa, the number of theoretical plates is 430, and the reflux ratio is 70; the mass fraction of the separated monomethyltrichlorosilane is 99.75 percent, and the recovery rate is 98.1 percent; the mass fraction of the separated dimethyldichlorosilane is 99.99 percent, and the recovery rate is 99.22 percent; the mass fraction of the separated trimethylchlorosilane is 99.78 percent, and the recovery rate is 89.5 percent; the mass fraction of the separated monomethyldichlorosilane is 99.92%, the recovery rate is 98.5%, and the whole process can save energy by 55.1% compared with the traditional process.
After passing through a preheater 9, the feeding temperature is increased to 53 ℃, and the temperature of the bottom material flow of the lower tower 2 is reduced to 57 ℃; after heat exchange is carried out by a first heat exchanger 10, the temperature of the bottom material flow of the light component tower 3 after vaporization is 75.2 ℃, and the temperature of the top material flow of the condensation high-removal tower 1 is 82.4 ℃; after heat exchange is carried out by a second heat exchanger 11, the temperature of the bottom material flow of the vaporized hydrogen-containing tower 4 is 71.5 ℃, and the temperature of the top material flow of the condensed height removing tower 1 is 78.7 ℃; after heat exchange is carried out by the third heat exchanger 12, the temperature of the bottom material flow of the dimethyl tower 6 after vaporization is 68.8 ℃, and the temperature of the top material flow of the high-altitude separation tower 1 after complete condensation is 78.7 ℃.
The above description is not intended to limit the invention, nor is the invention limited to the examples set forth above. Those skilled in the art should also realize that changes, modifications, additions and substitutions can be made without departing from the true spirit and scope of the invention.

Claims (5)

1. A system for separating crude organosilicon monomers by six-tower heat integration rectification is characterized in that: comprises a high-removing tower, a low-removing tower, a light-ends tower, a hydrogen-containing tower, a trimethyl tower, a dimethyl tower, a separator and a mixer; the middle raw material inlet of the high-pressure component removing tower is connected with a preheater through a pipeline, the top gas phase outlet of the high-pressure component removing tower is connected with the inlet of the separator through a first heat exchanger, one outlet of the separator is connected with the inlet of the mixer through a second heat exchanger, the other outlet of the separator is connected with the inlet of the mixer through a third heat exchanger, the outlet of the mixer is respectively connected with the top reflux port of the high-pressure component removing tower and the middle material inlet of the low-pressure component removing tower, the top material outlet of the low-pressure component removing tower is connected with the middle material inlet of the light component removing tower, the bottom material outlet of the low-pressure component removing tower is connected with the middle material inlet of the second tower through the preheater, and the bottom product outlet of the second tower is respectively connected with an auxiliary reboiler and the third heat exchanger; the tower bottom material outlet of the light component tower is connected with the middle material inlet of the hydrogen-containing tower through the first heat exchanger, and the tower bottom material outlet of the hydrogen-containing tower is connected with the middle material inlet of the trimethyl tower through the second heat exchanger.
2. The system for separating the crude organosilicon monomer by six-tower heat integrated distillation according to claim 1, wherein: the top product outlets of the low-component removing tower, the light-component separating tower, the hydrogen-containing tower, the trimethyl tower and the dimethyl tower are respectively provided with a condenser.
3. The system for separating the crude organosilicon monomer by the six-tower heat-integrated distillation according to claim 1, wherein: and reboiler are respectively arranged at the product outlets at the bottoms of the high-removing tower, the low-removing tower and the trimethyl tower.
4. A method for separating crude organosilicon monomers by using six-tower heat-integrated rectification of the system of any one of claims 1-3, characterized by comprising the following steps
(1) Preheating an organosilicon crude monomer mixture by a preheater, feeding the organosilicon crude monomer mixture into a high-boiling-point removal tower, treating the organosilicon crude monomer mixture by the high-boiling-point removal tower, dividing steam at the top of the high-boiling-point removal tower into two streams by a separator after the steam exchanges heat with a first heat exchanger through a pipeline, exchanging heat with a second heat exchanger by one stream, exchanging heat with a third heat exchanger by the other stream, mixing the two streams by a mixer after the two streams exchange heat, refluxing a part of the mixture to the high-boiling-point removal tower, extracting a part of the mixture to enter a low-boiling-point removal tower, and extracting a high-boiling-point substance at the bottom of the high-boiling-point removal tower;
(2) Feeding a mixture with a boiling point lower than that of the monomethyl trichlorosilane extracted from the top of the low-boiling component removing tower into a light component tower, extracting a mixture of the monomethyl trichlorosilane and the dimethyl dichlorosilane from the bottom of the low-boiling component removing tower, preheating the feed by a preheater, and feeding the preheated feed into a dimethyl tower;
(3) Extracting low-boiling-point substances with the boiling point lower than that of the monomethyldichlorosilane from the top of the light component tower, and sending tower bottoms into a hydrogen-containing tower after heat exchange is carried out between the tower bottoms and the steam at the top of the high-removal tower through a first heat exchanger;
(4) The product of the monomethyl dichlorosilane is extracted from the top of the hydrogen-containing tower, the bottom of the tower flows through a second heat exchanger to exchange heat with a material flow separated by a separator, and the extracted mixture of trimethyl monochlorosilane and silicon tetrachloride is fed into a trimethyl tower;
(5) An azeotrope of trimethylchlorosilane and silicon tetrachloride is extracted from the top of a trimethyl tower, and a product of trimethylchlorosilane is extracted from the bottom of the trimethyl tower;
(6) And (3) separating the product monomethyl trichlorosilane from the top of the dimethyl tower, dividing the material flow at the bottom of the dimethyl tower into two flows, heating one flow by an auxiliary reboiler and returning the other flow to the dimethyl tower, exchanging heat between the other flow separated by a separator and the third heat exchanger and returning the other flow to the dimethyl tower, and collecting the product dimethyl dichlorosilane from the bottom of the dimethyl tower.
5. The method for separating the crude organosilicon monomer by the six-tower heat-integrated rectification as claimed in claim 4, wherein: the operating pressure of the high-pressure removal tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 30-40; the operating pressure of the low-boiling component removing tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 50-60; the operating pressure of the light component tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 30-40; the operating pressure of the hydrogen-containing tower is 100-300 kpa, the number of theoretical plates is 40-60, and the reflux ratio is 1-10; the operating pressure of the trimethyl tower is 100-300 kpa, the number of theoretical plates is 20-50, and the reflux ratio is 90-100; the operating pressure of the dimethyl tower is 100-300 kpa, the number of theoretical plates is 200-300, and the reflux ratio is 70-80.
CN202210996344.7A 2022-08-19 2022-08-19 System and method for separating organic silicon crude monomer by six-tower heat integration rectification Pending CN115591258A (en)

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