CN115228118A

CN115228118A - Energy-saving method and device for rectifying crude monomer

Info

Publication number: CN115228118A
Application number: CN202210784569.6A
Authority: CN
Inventors: 李少平; 李书兵; 甘周清; 高英; 颜昌锐
Original assignee: Hubei Xingrui Silicon Material Co Ltd
Current assignee: Hubei Xingrui Silicon Material Co Ltd
Priority date: 2022-07-05
Filing date: 2022-07-05
Publication date: 2022-10-25

Abstract

The invention relates to a crude monomer rectifying device and a process, wherein a crude monomer enters a first rectifying tower, a high-boiling gas phase material removed from the top of the first rectifying tower firstly enters a reboiler at a fourth tower kettle of the rectifying tower as a heat source, the rest gas phase material enters a reboiler at a third tower kettle of the rectifying tower as a heat source, the rest gas phase material is condensed by the reboiler and then is fed into a second rectifying tower, and the crude high-boiling gas is extracted from the tower kettle; a methyl trichlorosilane product is extracted from the top of the rectifying tower III; all gas phase materials at the top of the tower enter a reboiler at the second tower kettle of the rectifying tower to be used as a heat source, and a part of gas phase materials after condensation by the reboiler is used as tower reflux to return to the top of the third tower of the rectifying tower; the tower bottom is taken as the feeding of a third rectifying tower and a fourth rectifying tower. According to the invention, the gas phase material at the top of the rectifying tower is preferentially used as a heat source of a reboiler at the four towers of the rectifying tower, the rest is used as a heat source of a reboiler at the three towers of the rectifying tower, and the gas phase material at the top of the rectifying tower is completely used as a heat source of a reboiler at the two towers of the rectifying tower, so that the steam consumption is reduced by at least 30% and the circulating water consumption is reduced by 30% in a same ratio.

Description

Energy-saving method and device for rectifying crude monomer

Technical Field

The invention relates to a crude monomer rectification energy-saving method, belonging to the technical field of organic silicon production.

Background

The methyl chlorosilane mixed monomer comprises dimethyl dichlorosilane (dimethyl for short), methyl trichlorosilane (methyl for short), trimethyl monochlorosilane (trimethyl for short), methyl dichlorosilane (methyl for short contains hydrogen), high boiling point substances and low boiling point substances. As is well known, the synthesis of methyl chlorosilane monomers at home and abroad generally adopts a direct method synthesis process, silicon powder and chloromethane are used as raw materials, a methyl chlorosilane mixed monomer is directly synthesized under the action of a copper catalyst system, the methyl chlorosilane mixed monomer is rectified and separated to obtain a main target product dimethyl, and byproducts, namely methyl, methyl contain hydrogen, trimethyl, high-boiling residues and low-boiling residues. Dimethyl is hydrolyzed and cracked to produce various organosilicon intermediates, namely oligomeric methyl siloxane or alkoxy silane, and the oligomeric methyl siloxane or alkoxy silane is further processed into various organosilicon downstream products.

The purity requirement of the raw material dimethyl is quite high when the silicone oil and the silicone rubber are prepared, and particularly the purity of the key raw material dimethyl is required to reach more than 99.95 percent when the high-temperature vulcanized silicone rubber is prepared. However, the crude monomer components are complex, the boiling point difference is small, and the purity of the dimethyl product obtained by rectification of domestic organic silicon manufacturers is not high and the energy consumption is large compared with the foreign advanced level, so that the market competitiveness of the product is low. The energy consumption for separating the methyl chlorosilane mixed monomer accounts for more than 80 percent of the whole organic silicon device, so that the related technical research on the separation and purification process of the methyl chlorosilane mixed monomer is necessary, and the energy consumption is reduced as much as possible under the condition of ensuring the product quality.

At present, the domestic technology mainly provides variable-pressure thermal coupling rectification of an upper tower and a lower tower, double-effect rectification thermal coupling of a binary tower in parallel connection, and variable-pressure thermal coupling rectification of the upper tower and the binary tower, the utilization rate of the thermal coupling is not high, the comprehensive consideration of the thermal coupling for a three-tower system of the upper tower, the lower tower and the binary tower is not involved, and the energy consumption is still high.

Disclosure of Invention

The invention provides a crude monomer rectification energy-saving method, which solves the problems of difficult extraction in the prior art and overcomes the problems of large steam and circulating water consumption and high energy consumption in monomer separation.

Description of technical terms used in the present invention:

coarse high-boiling residues: components with boiling point higher than 70.2 ℃ under normal pressure.

Low-boiling-point substances: a component having a boiling point of less than 40.4 ℃ at atmospheric pressure.

Crude monomer: the methyl chlorosilane mixed monomer comprises, by mass, 6% -9% of monomethyl trichlorosilane, 82% -87% of dimethyl dichlorosilane, 2.8% -3.7% of trimethyl monochlorosilane, 1.3% -2% of monomethyl dichlorosilane and 0.05% -1% of silicon tetrachloride, and also comprises other mixtures which are difficult to detect.

The technical scheme of the invention is as follows:

a crude monomer rectification energy-saving device is characterized in that a crude monomer feeding pipe is connected with a first rectification tower;

the top of the rectifying tower is respectively connected with a rectifying tower four-tower kettle reboiler arranged at the four bottoms of the rectifying tower and a rectifying tower three-tower kettle reboiler arranged at the three bottoms of the rectifying tower through a gas phase pipeline;

a rectifying tower three-tower kettle reboiler and a rectifying tower four-tower kettle reboiler are converged through a gas phase pipeline and then connected with a rectifying tower two;

the bottom of the second rectifying tower is respectively connected with a third rectifying tower and a fourth rectifying tower through liquid phase pipelines.

The gas phase pipelines of the rectifying tower three-tower kettle reboiler and the rectifying tower four-tower kettle reboiler are respectively provided with a rectifying tower three-coupling reflux pump and a rectifying tower four-coupling reflux pump before being converged.

The bottom of the second rectifying tower is also provided with a reboiler of the second rectifying tower kettle, and the top of the third rectifying tower is connected with the reboiler of the second rectifying tower kettle arranged at the bottom of the second rectifying tower through a gas phase pipeline.

One path of the reboiler at the second tower kettle of the rectifying tower is connected with the third rectifying tower through a reflux pump of the third rectifying tower, and the other path is connected with the first discharge pipe (namely a methyl trichlorosilane product discharge pipe).

The top of the second rectifying tower is connected with a second condenser of the rectifying tower, the second condenser of the rectifying tower is connected with a second reflux groove of the rectifying tower, the second reflux groove of the rectifying tower is connected with the second rectifying tower through one path of a second reflux pump of the rectifying tower, and the other path of the second reflux groove of the rectifying tower is connected with a third discharge pipe (namely a discharge pipe of a component with a boiling point lower than that of the methyltrichlorosilane).

And the bottom of the rectifying tower III is also provided with a rectifying tower III steam reboiler, and the bottom of the rectifying tower III is connected to a discharging pipe II (namely a dimethyl dichlorosilane discharging pipe).

The top of the rectifying tower IV is connected with a rectifying tower IV condenser, the rectifying tower IV condenser is connected with a rectifying tower IV reflux groove, the rectifying tower IV reflux groove is connected with the rectifying tower IV through a rectifying tower IV reflux pump, and one way is connected with a discharging pipe IV (namely a methyl trichlorosilane discharging pipe).

The four bottoms of the rectifying tower are connected to a fifth discharge pipe (namely a dimethyldichlorosilane discharge pipe).

The rectifying tower four-tower kettle reboiler is connected with the upper part of the rectifying tower I through a rectifying tower four-coupling reflux pump, and the rectifying tower three-tower kettle reboiler is also connected with the upper part of the rectifying tower I through a rectifying tower three-coupling reflux pump.

One bottom of the rectifying tower is connected to the coarse high-boiling-point substance discharging pipe.

The energy-saving process carried out by adopting the crude monomer rectification energy-saving device comprises the following steps:

(1) The method comprises the following steps of feeding organic silicon crude monomers into a first rectifying tower at a flow rate of 20-35t/h, feeding the organic silicon crude monomers into a first rectifying tower 1 at a flow rate of 20-35t/h, removing 35% -45% of high-boiling gas-phase materials from the top of the first rectifying tower, feeding the organic silicon crude monomers into a four-tower kettle reboiler of the rectifying tower as a heat source, feeding the rest gas-phase materials into a three-tower kettle reboiler of the rectifying tower as a heat source, condensing 10% -15% of the organic silicon crude monomers by the four-tower kettle reboiler of the rectifying tower and the three-tower kettle reboiler of the rectifying tower as a second rectifying tower feeding material, and extracting crude high-boiling materials from a tower kettle.

(2) And the gas phase at the top of the second rectifying tower is condensed by a second rectifying tower condenser and enters a second rectifying tower reflux groove, the material in the second rectifying tower reflux groove is conveyed by a second rectifying tower reflux pump to one part as tower reflux and returns to the top of the second rectifying tower, the other part is extracted to obtain the components with the boiling point below 66.4 ℃ at normal pressure and enters a subsequent rectifying tower for separation, and the extracted material in the second rectifying tower kettle is conveyed by a second rectifying tower kettle liquid pump to serve as the feed of a third rectifying tower and a fourth rectifying tower.

(3) And the gas phase material at the top of the rectifying tower III enters a reboiler at the bottom of the rectifying tower II to be used as a heat source, after being condensed by the reboiler at the bottom of the rectifying tower II, one part of the gas phase material is used as tower reflux and returns to the top of the rectifying tower III through a three-reflux pump of the rectifying tower III, the other part of the gas phase material is used as a methyl trichlorosilane product and is extracted from the bottom of the rectifying tower III, and a dimethyl dichlorosilane product is extracted from the bottom of the rectifying tower III.

(4) And condensing gas phase at the top of the four towers of the rectifying tower by a four-condenser of the rectifying tower to enter a four-reflux groove of the rectifying tower, conveying one part of the materials in the four-reflux groove of the rectifying tower by a four-reflux pump of the rectifying tower to return to the top of the four towers of the rectifying tower as tower reflux, extracting a trichlorosilane product from the other part of the materials, and extracting a dimethyldichlorosilane product from a tower kettle.

In the step (1), the crude organosilicon monomer is a mixture composed of methyl chlorosilane, and the main components and mass fractions of the crude organosilicon monomer are methyl trichlorosilane (6% -9%), dimethyl dichlorosilane (82% -87%), trimethyl monochlorosilane (2.8% -3.7%), methyl dichlorosilane (1.3% -2%), silicon tetrachloride (0.05% -1%), and the like; the organosilicon crude monomer enters a first rectifying tower at the flow rate of 20-35 t/h.

In the step (1), 85% -90% of heat sources in the four-tower kettle reboiler of the rectifying tower and the two reboilers of the three-tower kettle reboiler of the rectifying tower are condensed and respectively converged by a three-coupling reflux pump of the rectifying tower and a four-coupling reflux pump of the rectifying tower, and then return to the top of the rectifying tower as tower reflux.

In the step (1), the top temperature of the rectifying tower I is controlled to be 130-140 ℃, and the top pressure is controlled to be 0.40-0.55MPa; preferably, the top temperature of the rectifying tower is controlled at 135 ℃, and the top pressure is controlled at 0.45MPa. The operation parameters of the first rectifying tower need to be controlled within the above requirement range as the design requirement of the separation degree of the first rectifying tower and the production condition of the subsequent rectifying tower need to be met.

Preferably, in the step (1), the high-boiling gas phase material removed from the top of the rectifying tower 1 is fed into a four-tower reboiler 10 of the rectifying tower for use as a heat source by 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%, and after the heat source is supplemented, the residual gas phase material is fed into a three-tower reboiler 6 of the rectifying tower for use as a heat source.

After heat sources in the reboiler 10 at the four-tower kettle of the rectifying tower and the reboiler 6 at the three-tower kettle of the rectifying tower are condensed and converged by the three-coupling reflux pump 12 of the rectifying tower and the four-coupling reflux pump 16 of the rectifying tower respectively, 10%, 11%, 12%, 13%, 14% and 15% of the heat sources are used as the feeding material of the second rectifying tower 2, and the rest is used as the tower reflux and returns to the top of the first rectifying tower 1.

In the step (2), the temperature of the second tower kettle of the rectifying tower is controlled to be 84-95 ℃, the pressure of the second tower kettle of the rectifying tower is controlled to be 0.05-0.13MPa, and as a preferred scheme, the temperature of the second tower kettle of the rectifying tower is controlled to be 90 ℃, and the pressure of the second tower kettle of the rectifying tower is controlled to be 0.07MPa. And the operating parameters of the second rectifying tower need to be controlled within the above requirement range as the design requirement of the separation degree of the second rectifying tower and the production condition of the subsequent rectifying tower need to be met.

And (3) conveying more than or equal to 97 percent (usually 97-98 percent) of the material in the second reflux tank of the rectifying tower in the step (2) through a second reflux pump of the rectifying tower to return to the top of the second rectifying tower as tower reflux, and introducing the rest (usually 2-3 percent) of the extracted component with the boiling point below 66.4 ℃ at normal pressure into a subsequent rectifying tower for separation.

And (3) in the step (2), 60 to 70 percent of the distillation tower second kettle liquid is extracted and conveyed by a distillation tower second kettle liquid pump to be used as the third feed of the distillation tower, and the rest is used as the fourth feed of the distillation tower.

Preferably, the output from the second 2 tower bottom of the rectifying tower is first conveyed by 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69% and 70% through the second tower bottom liquid pump 14 of the rectifying tower to be used as the feed of the third 3 rectifying tower, and the rest of the feed of the third 3 rectifying tower is used as the feed of the fourth 4 rectifying tower.

And (4) returning 98.5-99% of the reflux of the rectifying tower serving as tower reflux to the top of the rectifying tower III by using a rectifying tower III reflux pump in the step (3), and extracting the rest serving as a methyltrichlorosilane product.

In the step (3), the temperature of the top of the rectifying tower III is controlled to be 105-115 ℃, and the pressure of the top of the rectifying tower is controlled to be 0.15-0.25MPa; preferably, the temperature of the three top of the rectifying tower is controlled at 107 ℃, and the pressure of the top of the rectifying tower is controlled at 0.2MPa. The operation parameters of the third rectifying tower need to be controlled within the above requirement range as the design requirement of the separation degree of the third rectifying tower and the production condition of the subsequent rectifying tower need to be met;

and (4) in the step (3), a third tower kettle of the rectifying tower adopts a third steam reboiler of a second reboiler rectifying tower as a supplementary heat source, and all gas phase materials at the top of the third tower of the rectifying tower enter a reboiler of a second tower kettle of the rectifying tower as a heat source.

And (4) conveying 98.5-99% of the material in the four reflux tanks of the rectifying tower in the step (4) through the four reflux pumps of the rectifying tower to return to the top of the four rectifying towers as tower reflux, and collecting a trichlorosilane product in the rest.

In the step (4), the temperature of the four tower kettles of the rectifying tower is controlled to be 85-95 ℃, and the pressure of the tower kettles is controlled to be 0.05-0.10MPa; as a preferred scheme, the temperature of the four-tower kettle of the rectifying tower is controlled at 90 ℃, and the pressure of the tower kettle is controlled at 0.07MPa. The operation parameters of the fourth rectifying tower need to be controlled within the above requirement range as the design requirement of the separation degree of the fourth rectifying tower and the production condition of the subsequent rectifying tower need to be met;

the gas phase temperature at the top of the first rectifying tower is higher than the tower kettle temperatures of the third rectifying tower and the fourth rectifying tower as the heat transfer basic conditions need to be met; in order to meet the most reasonable design conditions of the reboiler of the third rectifying tower and the fourth rectifying tower, the temperature of the gas phase at the top of the first rectifying tower is 15-60 ℃ higher than that of the kettle of the third rectifying tower and the kettle of the fourth rectifying tower.

And the gas phase temperature at the top of the third rectifying tower is higher than the temperature of the kettle of the second rectifying tower because heat transfer basic conditions are required to be met, and the gas phase temperature at the top of the third rectifying tower is 15-20 ℃ higher than the temperature of the kettle of the second rectifying tower in order to meet the most reasonable design conditions of a reboiler of the second rectifying tower.

The invention has simple process technology, strict control condition and good application prospect and application value, and compared with the prior art, the invention has the following good effects: in the conventional process, the reboilers of the rectifying tower I, the rectifying tower II, the rectifying tower III and the rectifying tower IV are heated by adopting steam, and the tower top is condensed by adopting circulating water.

The invention fully utilizes the components and characteristics of materials, adopts a triple-effect rectification process technology, splits a rectification tower III in the conventional process into a rectification tower III and a rectification tower IV, can apply the redundant heat of a rectification tower I to a rectification tower II through one-time splitting, and maximally utilizes the heat of a system.

Simultaneously, the first rectifying tower and the third rectifying tower are pressurized to increase the temperature of the first rectifying tower and the third rectifying tower; as heat transfer basic conditions need to be met, the temperature of the gas phase at the top of the first rectifying tower is higher than the temperatures of the tower kettles of the third rectifying tower and the fourth rectifying tower, and the temperature of the gas phase at the top of the third rectifying tower is higher than the temperature of the tower kettle of the second rectifying tower, so that the first rectifying tower and the third rectifying tower need to be pressurized, and the temperature of the top of the first rectifying tower and the temperature of the third rectifying tower are increased.

Because the third rectifying tower is provided with a steam reboiler as heat compensation of an external system, firstly, the gas phase material at the top of the first rectifying tower is preferentially used as a heat source of a thermally coupled reboiler at the four towers of the first rectifying tower, the rest is used as a heat source of the reboiler at the three towers of the third rectifying tower, and then, the gas phase material at the top of the third rectifying tower is completely used as a heat source of the reboiler at the two towers of the second rectifying tower, so that the latent heat of the gas phase steam material at the top of the first rectifying tower and the third rectifying tower is reasonably utilized, the system heat can be maximally utilized, the steam consumption of the second rectifying tower, the third rectifying tower and the fourth rectifying tower is reduced, the circulating water consumption of the first rectifying tower and the third rectifying tower is reduced, and the steam consumption is at least reduced by 30% and the circulating water consumption is reduced by 30% in the same ratio.

Drawings

FIG. 1 is a structural diagram of an energy-saving method for rectifying crude monomers, wherein 1 is a first rectifying tower; 2, a second rectifying tower; 3, a third rectifying tower; 4, a rectifying tower IV; 5, a reboiler of the rectifying tower; 6, a rectifying tower three-tower kettle reboiler; 7, a rectifying tower triple steam reboiler; 8, a reboiler at a second tower kettle of the rectifying tower; 9, a second condenser of the rectifying tower; 10, a rectifying tower four-tower kettle reboiler; 11, a rectifying tower four condenser; 12, a rectifying tower is coupled with a reflux pump; 13, a rectifying tower three reflux pumps; 14, a second kettle liquid pump of the rectifying tower; 15 a second reflux pump of the rectifying tower; 16, coupling a reflux pump with a rectifying tower IV; 17 a rectifying tower four reflux pump; 18, a second reflux groove of the rectifying tower; 19 a rectifying tower four reflux groove; 20 a crude monomer feed pipe; 21 a coarse high-boiling-point substance discharge pipe; 22, discharging a pipe I; 23 discharging a pipe II; 24, discharging a pipe III; 25, a fourth methyl trichlorosilane discharge pipe; and 26, discharging a pipe V.

FIG. 2 is a structural diagram of a crude monomer rectification method of a conventional process, wherein 1' a rectification tower I; 2' rectifying tower II; a 3' rectifying tower III; 4' rectifying tower-steam reboiler; a second steam reboiler of the 5' rectifying tower; 6' rectifying tower three-steam reboiler; 7' a rectifying tower-condenser; 8' a second condenser of the rectifying tower; 9' rectifying tower III condenser; 10' a reflux groove of the rectifying tower; 11' a second reflux groove of the rectifying tower; 12' rectifying tower three reflux tanks; 13' a reflux pump of the rectifying tower; 14' a second reflux pump of the rectifying tower; 15' rectifying tower three feed pumps; 16' rectifying tower three reflux pumps; 17' crude monomer feed line; 18' coarse high-boiling residue discharge pipe; 19' discharging pipe I; 20' discharging pipe II; 21' discharging pipe III; 22' dimethyl dichlorosilane discharging pipe; 23' a methyltrichlorosilane discharge tube.

Detailed Description

The present invention will be further described with reference to the accompanying drawings and examples, which are merely preferred embodiments of the invention, and are not intended to be exhaustive. Based on the embodiments in the implementation, other embodiments obtained by those skilled in the art without any creative efforts belong to the protection scope of the present invention.

Example 1

A crude monomer rectification energy-saving device is characterized in that a crude monomer feeding pipe is connected with a first rectification tower 1;

the top of the rectifying tower I1 is respectively connected with a rectifying tower four-tower kettle reboiler 10 arranged at the bottom of a rectifying tower four 4 and a rectifying tower three-tower kettle reboiler 6 arranged at the bottom of a rectifying tower three 3 through a gas phase pipeline;

a rectifying tower three-tower kettle reboiler 6 and a rectifying tower four-tower kettle reboiler 10 are converged through a gas phase pipeline and then connected with a rectifying tower two 2;

the bottom of the second rectifying tower 2 is respectively connected with a third rectifying tower 3 and a fourth rectifying tower 4 through liquid phase pipelines.

The gas phase pipelines of the rectifying tower three-tower kettle reboiler 6 and the rectifying tower four-tower kettle reboiler 10 are respectively provided with a rectifying tower three-coupling reflux pump 12 and a rectifying tower four-coupling reflux pump 16 before being converged.

The bottom of the second rectifying tower 2 is also provided with a second rectifying tower kettle reboiler 8, and the top of the third rectifying tower 3 is connected with the second rectifying tower kettle reboiler 8 arranged at the bottom of the second rectifying tower 2 through a gas phase pipeline.

And one path of the reboiler 8 at the second tower kettle of the rectifying tower is connected with the third rectifying tower 3 through a third reflux pump 13 of the rectifying tower, and the other path is connected with a first discharge pipe 22.

The top of the second rectifying tower 2 is connected with a second rectifying tower condenser 9, the second rectifying tower condenser 9 is connected with a second rectifying tower reflux groove 18, one path of the second rectifying tower reflux groove 18 is connected with the second rectifying tower 2 through a second rectifying tower reflux pump 15, and the other path of the second rectifying tower reflux groove 18 is connected with a third discharge pipe 24.

The bottom of the rectifying tower III 3 is also provided with a rectifying tower III steam reboiler 7, and the bottom of the rectifying tower III 3 is connected to the discharging pipe II 23.

The top of the rectifying tower IV 4 is connected with a rectifying tower IV condenser 11, the rectifying tower IV condenser 11 is connected with a rectifying tower IV reflux groove 19, the rectifying tower IV reflux groove 19 is connected with the rectifying tower IV 4 through one path of a rectifying tower IV reflux pump 17, and the other path is connected with a discharge pipe IV 25.

The bottom of the rectifying tower four 4 is connected to a discharge pipe five 26.

The rectifying tower four-tower kettle reboiler 10 is connected with the upper part of the rectifying tower I1 through a rectifying tower four-coupling reflux pump 16, and the rectifying tower three-tower kettle reboiler 6 is further connected with the upper part of the rectifying tower I1 through a rectifying tower three-coupling reflux pump 12.

The bottom of the rectifying tower I1 is connected to a crude high-boiling residue discharge pipe 21.

Example 2

The equipment connecting structure of the conventional process is as follows:

the lower part of the first rectifying tower 1 'is provided with a first rectifying tower steam reboiler 4', the top of the first rectifying tower 1 'is connected with a first rectifying tower condenser 7', the top of the first rectifying tower condenser 7 'is connected with a first rectifying tower reflux groove 10' through a gas phase pipeline, the first rectifying tower reflux groove 10 'is connected with a rectifying tower reflux pump 13', one path of the rectifying tower reflux pump 13 'is connected to the upper part of the first rectifying tower 1', the other path of the rectifying tower reflux pump is connected with a second rectifying tower 2 'through a first discharging pipe 19', and the first rectifying tower 1 'kettle is connected with a coarse high-boiling substance discharging pipe 18';

the lower part of the second rectifying tower 2 'is provided with a second rectifying tower steam reboiler 5', the top of the second rectifying tower 2 'is connected with a second rectifying tower condenser 8', the top of the first rectifying tower condenser 8 'is connected with a second rectifying tower reflux groove 11' through a gas phase pipeline, the second rectifying tower reflux groove 11 'is connected with a second rectifying tower reflux pump 14', one path of the second rectifying tower reflux pump 14 'is connected to the upper part of the second rectifying tower 2', and the other path of the second rectifying tower reflux pump 14 'is connected to a third discharging pipe 21';

the bottom of the second rectifying tower is connected with the middle of a third rectifying tower 3 'through a second discharging pipe 20', the lower part of the third rectifying tower 3 'is provided with a third rectifying tower steam reboiler 6', the top of the third rectifying tower 3 'is connected with a third rectifying tower condenser 9' through a gas phase pipeline, the third rectifying tower condenser 9 'is connected with a third rectifying tower reflux groove 12', one path of the third rectifying tower reflux groove 12 'is connected to the upper part of the third rectifying tower 3' through a third rectifying tower reflux pump 16', one path of the third rectifying tower reflux groove is connected to a methyltrichlorosilane discharging pipe 23', and the bottom of the third rectifying tower 3 'is connected to a dimethyldichlorosilane discharging pipe 22'.

Example 3

The energy-saving process for rectifying the crude monomer by using the embodiment 1 is as follows:

the organosilicon crude monomer is a mixture composed of methyl chlorosilane, and comprises the main components and mass fractions of (6% -9%) methyl trichlorosilane, (82% -87%) dimethyl dichlorosilane, (2.8% -3.7%) trimethyl monochlorosilane, (1.3% -2%) methyl dichlorosilane and (0.05% -1%) silicon tetrachloride.

(1) The method comprises the following steps of (1) enabling an organic silicon crude monomer to enter a rectifying tower I1 at a flow rate of 25.5t/h, enabling a high-boiling gas-phase material removed from the top of the rectifying tower I1 to firstly enter a rectifying tower IV reboiler 10 as a heat source of a rectifying tower IV with a volume fraction of 35% as a priority, enabling a remaining 65% of gas-phase material to enter a rectifying tower IV reboiler 6 as a heat source, condensing by the reboiler, converging the 85% of gas-phase material with the volume fraction through a rectifying tower III-coupled reflux pump 14 and a rectifying tower IV-coupled reflux pump 16 respectively, enabling the 85% of gas-phase material with the volume fraction to return to the top of the rectifying tower I1 as tower reflux, enabling the 15% of gas-phase material with the volume fraction to be fed into a rectifying tower II 2, and extracting crude high-boiling 21 from a tower kettle; the temperature of the top of the rectifying tower 1 is controlled at 135 ℃, and the pressure of the top of the rectifying tower is controlled at 0.45MPa.

(2) Condensing gas phase at the top of the fourth 4 tower top of the rectifying tower by a fourth condenser 11 of the rectifying tower to enter a fourth reflux groove 19 of the rectifying tower, conveying 99 percent of material in the fourth reflux groove 19 of the rectifying tower by a fourth reflux pump 17 of the rectifying tower to return to the top of the fourth 4 tower as tower reflux, extracting a trichlorosilane product 25 with 1 percent volume fraction, and extracting a dimethyldichlorosilane product 26 at the tower bottom; the temperature of the four 4 tower kettles of the rectifying tower is controlled at 90 ℃, and the pressure of the tower kettles is controlled at 0.07MPa.

(3) A third 3 tower kettle of the rectifying tower adopts a third steam reboiler 7 of a second reboiler rectifying tower as a supplementary heat source, all gas phase materials at the tower top enter a second tower kettle reboiler 8 of the rectifying tower as a heat source, after the gas phase materials are condensed by a second tower kettle thermal coupling reboiler 8 of the rectifying tower, 99% volume fraction materials are returned to the top of the third 3 tower of the rectifying tower as tower reflux through a third reflux pump 13 of the rectifying tower, 1% volume fraction materials are extracted as a methyltrichlorosilane product 22, and a dimethyldichlorosilane product 23 is extracted at the tower bottom; the top temperature of the third rectifying tower 3 is controlled at 107 ℃, the top pressure is controlled at 0.2MPa, and if the top temperature of the third rectifying tower 3 can be controlled at 107 ℃ and the top pressure is controlled at 0.2MPa as the heat source of the third rectifying tower in the steps, a second reboiler, a third steam reboiler 7 of the rectifying tower is not needed as a supplementary heat source.

(4) The gas phase at the top of the second rectifying tower 2 is condensed by a second rectifying tower condenser 9 and enters a second rectifying tower reflux groove 18, the material in the second rectifying tower reflux groove 18 is conveyed by a second rectifying tower reflux pump 15 to be 98% volume fraction material as tower reflux and returns to the top of the second rectifying tower 2, the other part of the extracted component 24 with the boiling point lower than that of the methyl trichlorosilane enters a subsequent rectifying tower for separation, the material extracted from the second rectifying tower 2 tower kettle is conveyed by a second rectifying tower kettle liquid pump 14 to be a third rectifying tower 3, and the rest 40% volume fraction material is obtained to be fed as a fourth rectifying tower 4; the temperature of the second 2 tower bottom of the rectifying tower is controlled at 90 ℃, and the pressure of the tower bottom is controlled at 0.07MPa.

To this process condition of this application, the volume of this application to the trend selection and trend of each gaseous phase material has carried out the condition of refining to condenser and reboiler load influence, and the volume of walking of discovery gaseous phase is huge to the influence that realizes the energy-conserving effect of rectification process, specifically as follows:

note: the percentages are volume fractions.

The energy-saving process (conventional process) for rectifying the crude monomer carried out in example 2 is as follows:

feeding organosilicon crude monomers into a first rectifying tower 1' at a flow rate of 25.5t/h, condensing high-boiling gas-phase materials removed from the top of the first rectifying tower 1' through a first rectifying tower condenser 7' and feeding the high-boiling gas-phase materials into a reflux groove 10' of the rectifying tower, conveying the materials in the reflux groove 10' of the rectifying tower through a reflux pump 13' of the rectifying tower to be 85 volume percent as tower reflux and returning the materials to the top of the first rectifying tower 1', feeding 15 volume percent of gas-phase materials as a second rectifying tower 2', and extracting crude high-boiling 18' from a tower kettle; the top temperature of the first 1' of the rectifying tower is controlled at 135 ℃, and the top pressure is controlled at 0.45MPa.

The gas phase material at the top of the second rectifying tower 2' is condensed by a second rectifying tower condenser 8' and enters a second rectifying tower reflux groove 11', the material in the second rectifying tower reflux groove 11' is conveyed by a second rectifying tower reflux pump 14' to form 98% volume fraction material which is returned to the top of the second rectifying tower 2' as tower reflux, the other part of the material is extracted to form a component 21' with a boiling point lower than that of the methyl trichlorosilane and enters a subsequent rectifying tower for separation, and the material extracted from the bottom of the tower is conveyed by a third rectifying tower feed pump 15' to form third rectifying tower 3' feed; the temperature of the second 2' tower kettle of the rectifying tower is controlled at 90 ℃, and the pressure of the tower kettle is controlled at 0.07MPa.

The gas phase material at the top of the rectifying tower III 3 'is condensed by a rectifying tower III condenser 9' and enters a rectifying tower III reflux groove 12', the material in the rectifying tower III reflux groove 12' is conveyed by a rectifying tower III reflux pump 16 'to be taken as the material with 99% volume fraction to return to the top of the rectifying tower III 3' as the tower reflux, the material with 1% volume fraction, namely a trichlorosilane product 23', and a dimethyldichlorosilane product 22' is extracted at the bottom of the rectifying tower; the tower top temperature of the third 3' of the rectifying tower is controlled at 107 ℃, and the tower top pressure is controlled at 0.2MPa.

Under the condition of the same treatment capacity and product quality, the energy consumption comparison data of the conventional process and the system of the invention are as follows:

the purity of the obtained product, namely the methyl trichlorosilane, can reach 99.7 percent or more under the process conditions of the conventional technical means, and the purity of the dimethyl dichlorosilane can reach 99.98 percent or more.

The steps and the process conditions are the same as those of the embodiment 1, the top of the rectifying tower I1 is controlled to remove less than 35 percent or more than 45 percent of high-boiling gas-phase materials, the high-boiling gas-phase materials are firstly fed into a reboiler 10 at the four-tower kettle of the rectifying tower to be used as a heat source, and the system cannot normally operate because the high-boiling gas-phase materials are less than 35 percent or more than 45 percent and the heat received by the reboiler 10 is too low or too high.

As can be seen from the comparison of the data, the process and the system have the advantages that under the condition of the same treatment capacity and product quality, the heat consumption is only 64.49 percent of that of the conventional process, the load of a condenser is 61.84 percent of that of the conventional process, and the consumption of energy and circulating water is greatly reduced.

Example 4

the method comprises the following steps of (1) enabling an organic silicon crude monomer to enter a first rectifying tower 1' at a flow rate of 25.5t/h, enabling a high-boiling gas-phase material removed from the top of the first rectifying tower 1' to enter a reflux groove 10' of the rectifying tower through a first rectifying tower condenser 7', enabling a material in the reflux groove 10' of the rectifying tower to be conveyed by a reflux pump 13' of the rectifying tower in 88 volume percent to return to the top of the first rectifying tower 1' as tower reflux, enabling a gas-phase material in 12 volume percent to be fed as a second rectifying tower 2', and extracting crude high-boiling 18' from a tower kettle; the top temperature of the first 1' of the rectifying tower is controlled at 132 ℃, and the top pressure is controlled at 0.42MPa.

The gas phase material at the top of the second 2' rectifying tower is condensed by a second condenser 8' of the rectifying tower and enters a second reflux groove 11' of the rectifying tower, the material in the second reflux groove 11' of the rectifying tower is conveyed by a second reflux pump 14' of the rectifying tower to be 99% volume fraction material as tower reflux and returns to the top of the second 2' rectifying tower, the other part of the material, 1%, of which the component 21' with the boiling point lower than that of the methyltrichlorosilane is extracted, enters a subsequent rectifying tower for separation, and the material extracted at the bottom of the tower is conveyed by a third feed pump 15' of the rectifying tower to be fed as a third 3' of the rectifying tower; the temperature of the second 2' tower kettle of the rectifying tower is controlled at 90 ℃, and the pressure of the tower kettle is controlled at 0.08MPa.

The gas phase material at the top of the rectifying tower III 3 'is condensed by a rectifying tower III condenser 9' and enters a rectifying tower III reflux groove 12', the material in the rectifying tower III reflux groove 12' is conveyed by a rectifying tower III reflux pump 16 'to be taken as the material with 98.5% volume fraction to return to the top of the rectifying tower III 3' as tower reflux, and the material with 1.5% volume fraction, namely a trichlorosilane product 23', and a dimethyldichlorosilane product 22' is extracted at the bottom of the rectifying tower; the tower top temperature of the third 3' of the rectifying tower is controlled at 109 ℃, and the tower top pressure is controlled at 0.21MPa.

(1) The method comprises the following steps of (1) enabling an organic silicon crude monomer to enter a rectifying tower I1 at a flow rate of 25.5t/h, enabling a high-boiling gas-phase material removed from the top of the rectifying tower I1 to firstly enter a rectifying tower IV reboiler 10 as a heat source of a rectifying tower IV with a volume fraction of 42%, enabling the remaining 58% of the gas-phase material to enter a rectifying tower III reboiler 6 as a heat source, condensing the gas-phase material by the reboiler, converging the gas-phase material by a rectifying tower III-coupled reflux pump 14 and a rectifying tower IV-coupled reflux pump 16 respectively, enabling the gas-phase material with a volume fraction of 88% to return to the top of the rectifying tower I1 as tower reflux, enabling the gas-phase material with a volume fraction of 12% to be fed into a rectifying tower II 2, and enabling the tower kettle to obtain crude high-boiling 21; the top temperature of the rectifying tower 1 is controlled at 132 ℃, and the top pressure is controlled at 0.42MPa.

(2) Condensing gas phase at the top of the fourth 4 tower top of the rectifying tower by a fourth condenser 11 of the rectifying tower to enter a fourth reflux groove 19 of the rectifying tower, conveying 99 percent of material in the fourth reflux groove 19 of the rectifying tower by a fourth reflux pump 17 of the rectifying tower to return to the top of the fourth 4 tower as tower reflux, extracting a trichlorosilane product 25 with 1 percent volume fraction, and extracting a dimethyldichlorosilane product 26 at the tower bottom; the temperature of the four 4 tower bottom of the rectifying tower is controlled at 92 ℃, and the pressure of the tower bottom is controlled at 0.09MPa.

(3) A third 3 tower kettle of the rectifying tower adopts a third steam reboiler 7 of a second reboiler rectifying tower as a supplementary heat source, all gas phase materials at the tower top enter a second tower kettle reboiler 8 of the rectifying tower as a heat source, after the gas phase materials are condensed by the second tower kettle thermal coupling reboiler 8 of the rectifying tower, 98.5% volume fraction materials are extracted by a third reflux pump 13 of the rectifying tower and return to the tower top of the third 3 tower as tower reflux, 1.5% volume fraction monomethyl trichlorosilane product 22 is extracted at the other part, and a dimethyl dichlorosilane product 23 is extracted at the tower bottom; the top temperature of the third rectifying tower 3 is controlled at 109 ℃, the top pressure is controlled at 0.21MPa, and if the top temperature of the third rectifying tower 3 can be controlled at 107 ℃ and the top pressure is controlled at 0.2MPa as the heat source of the third rectifying tower in the steps, a second reboiler, a third steam reboiler 7 of the rectifying tower is not needed as a supplementary heat source.

(4) The gas phase at the top of the second rectifying tower 2 is condensed by a second rectifying tower condenser 9 and enters a second rectifying tower reflux groove 18, the material in the second rectifying tower reflux groove 18 is conveyed by a second rectifying tower reflux pump 15 to be 99% in volume fraction as tower reflux and returns to the top of the second rectifying tower 2, the other part is extracted to be 1%, namely, the component 24 with low boiling point of the methyl trichlorosilane enters a subsequent rectifying tower for separation, the material extracted from the second rectifying tower 2 is conveyed by a second rectifying tower kettle liquid pump 14 to be used as a third rectifying tower 3, and the material obtained from the rest 32% in volume fraction is used as the feed of a fourth rectifying tower 4; the temperature of the second 2 tower bottom of the rectifying tower is controlled at 90 ℃, and the pressure of the tower bottom is controlled at 0.08MPa.

In another experimental process of the present application, the gas-phase material in step (1) does not preferentially enter the rectifying tower four, but first enters the rectifying tower three, for example, 42% of the gas-phase material in volume fraction enters the rectifying tower three-tower kettle reboiler 6 as a heat source, and then 58% of the gas-phase material in volume fraction enters the rectifying tower four-tower kettle reboiler 10 as a heat source of the rectifying tower four. Other process conditions are the same as above, and this example is 4-1.

In another experimental process of the present application, in the step (1), the gas-phase material does not preferentially enter the rectifying tower four, but first enters the rectifying tower three, for example, 60% of the gas-phase material with volume fraction enters the rectifying tower three-tower kettle reboiler 6 as a heat source, and then 40% of the gas-phase material with volume fraction enters the rectifying tower four-tower kettle reboiler 10 as a heat source of the rectifying tower four. Other process conditions are the same as above, and this example is 4-2.

it can be seen from the comparison of the above data that, by adopting the process and the system of the present invention, under the condition of the same treatment capacity and product quality, the heat consumption is only 66.90% of the conventional process, the condenser load is 66.64% of the conventional process, the energy consumption and the consumption of circulating water are greatly reduced, compared with example 4, the sequence of the gas-phase material of the rectifying tower to the rectifying tower three-reboiler 6 and the rectifying tower four-reboiler 10 is changed in example 4-1 and 4-2, and the result is: the start-up sequence of the rectifying tower is changed.

Example 5

The crude organosilicon monomer is a mixture consisting of methyl chlorosilane, and comprises the main components and the mass fractions of monomethyl trichlorosilane (6-9%), dimethyl dichlorosilane (82-87%), trimethyl monochlorosilane (2.8-3.7%), methyl dichlorosilane (1.3-2%) and silicon tetrachloride (0.05-1%).

The energy-saving process for rectifying the crude monomer (conventional process) carried out in example 2 is as follows:

the method comprises the following steps of (1) enabling an organic silicon crude monomer to enter a rectifying tower I1 at a flow rate of 30.5t/h, enabling a high-boiling gas-phase material removed from the top of the rectifying tower I1 to enter a reflux tank 10 of the rectifying tower through a condenser 7 of the rectifying tower I1, enabling the material in the reflux tank 10 of the rectifying tower I1 to be conveyed by a reflux pump 13 of the rectifying tower I1 to be 87% in volume fraction to return to the top of the rectifying tower I1 as tower reflux, enabling the extracted 13% in volume fraction to serve as a feed of a rectifying tower II 2, and extracting crude high-boiling 18 from a tower kettle; the temperature of the top of the rectifying tower 1 is controlled at 138 ℃, and the pressure of the top of the rectifying tower is controlled at 0.48MPa.

Gas-phase materials at the top of the second rectifying tower 2 enter a second rectifying tower 2 reflux groove 11 after being condensed by a second rectifying tower 2 condenser 8, the materials in the second rectifying tower 2 reflux groove 11 are conveyed by a second rectifying tower 2 reflux pump 14 to serve as materials with 98% volume fraction to return to the top of the second rectifying tower 2 as tower reflux, the other part of the materials is extracted to form a component 21 with a boiling point lower than that of the methyl trichlorosilane and enters a subsequent rectifying tower for separation, and the materials extracted from the bottom of the tower are conveyed by a third rectifying tower feed pump 15 to serve as feed of a third rectifying tower 3; the temperature of the second 2 tower bottom of the rectification tower is controlled at 93 ℃, and the pressure of the tower bottom is controlled at 0.09MPa.

Condensing the gas-phase material at the top of the third 3 rectifying tower into a third 3 rectifying tank 12 of the rectifying tower through a third 3 rectifying condenser 9, conveying 99% volume fraction material in the third 3 rectifying tank 12 of the rectifying tower as tower reflux by a third 3 rectifying pump 16 of the rectifying tower to return to the top of the third 3 rectifying tower, extracting a trichlorosilane product 23 from the other part, and extracting a dimethyldichlorosilane product 22 from the tower kettle; the top temperature of the third rectifying tower 3 is controlled at 112 ℃, and the top pressure is controlled at 0.23MPa.

(1) The method comprises the following steps of (1) enabling an organic silicon crude monomer to enter a rectifying tower I1 at a flow rate of 30.5t/h, enabling a gas phase material with a volume fraction of 44% preferentially removed from a high-boiling gas phase material at the tower top of the rectifying tower I1 to enter a rectifying tower IV reboiler 10 to serve as a heat source, enabling a remaining gas phase material with a volume fraction of 56% to enter a rectifying tower IV reboiler 6 to serve as a heat source, condensing the condensed gas phase materials by the reboiler, converging the condensed gas phase materials respectively through a rectifying tower III-coupled reflux pump 14 and a rectifying tower IV-coupled reflux pump 16, enabling the 87% gas phase material with the volume fraction to serve as tower reflux to return to the tower top of the rectifying tower I1, enabling the 13% gas phase material with the volume fraction to serve as a rectifying tower II 2 to be fed, and enabling the tower kettle to obtain crude high-boiling 21; the temperature of the top of the rectifying tower 1 is controlled at 138 ℃, and the pressure of the top of the rectifying tower is controlled at 0.48MPa.

(2) Condensing gas phase at the top of the fourth 4 tower top of the rectifying tower by a fourth condenser 11 of the rectifying tower to enter a fourth reflux groove 19 of the rectifying tower, conveying 99 percent of material in the fourth reflux groove 19 of the rectifying tower by a fourth reflux pump 17 of the rectifying tower to return to the top of the fourth 4 tower as tower reflux, producing 25 mass percent of a trichlorosilane product with 1 percent volume fraction, and producing 26 mass percent of dimethyldichlorosilane at the bottom of the tower; the temperature of the four 4 tower bottom of the rectifying tower is controlled at 94 ℃, and the pressure of the tower bottom is controlled at 0.09MPa.

(3) A third 3 tower kettle of the rectifying tower adopts a third steam reboiler 7 of a second reboiler rectifying tower as a supplementary heat source, all gas phase materials at the tower top enter a second tower kettle reboiler 8 of the rectifying tower as a heat source, after the gas phase materials are condensed by a second tower kettle thermal coupling reboiler 8 of the rectifying tower, 99% volume fraction materials are returned to the top of the third 3 tower of the rectifying tower as tower reflux through a third reflux pump 13 of the rectifying tower, 1% volume fraction monomethyl trichlorosilane product 22 is extracted, and a dimethyl dichlorosilane product 23 is extracted at the tower bottom; the top temperature of the third rectifying tower 3 is controlled to be 112 ℃, the top pressure is controlled to be 0.23MPa, and if the top temperature of the third rectifying tower 3 can be controlled to be 107 ℃ and the top pressure is controlled to be 0.2MPa as the heat source of the third rectifying tower in the steps, a second reboiler, a third steam reboiler 7 of the rectifying tower is not needed to be used as a supplementary heat source.

The gas phase at the top of the second rectifying tower 2 is condensed by a second rectifying tower condenser 9 and enters a second rectifying tower reflux groove 18, the material in the second rectifying tower reflux groove 18 is conveyed by a second rectifying tower reflux pump 15 to be 98% volume fraction material as tower reflux and returns to the top of the second rectifying tower 2, the other part of the extracted component 24 with the boiling point lower than that of the methyl trichlorosilane enters a subsequent rectifying tower for separation, the extracted material at the bottom of the second rectifying tower 2 is conveyed by a second rectifying tower bottom liquid pump 14 to be used as a third rectifying tower 3, and the rest 33% volume fraction material is obtained to be used as a fourth rectifying tower 4 feed; the temperature of the second 2 tower bottom of the rectification tower is controlled at 93 ℃, and the pressure of the tower bottom is controlled at 0.09MPa.

In another experimental process of the present application, in step (3), a third 3 tower bottom of the rectifying tower adopts a third steam reboiler 7 of the rectifying tower as a supplementary heat source, and only 90% of the gas phase material at the top of the third 3 tower bottom of the rectifying tower enters a second tower bottom reboiler 8 of the rectifying tower as a heat source. Other process conditions are the same as above, and the present example is 5-1.

as can be seen from the comparison of the data, by adopting the process and the system, under the condition of the same treatment capacity and product quality, the heat consumption is only 65.68 percent of that of the conventional process, the load of the condenser is 63.90 percent of that of the conventional process, and the consumption of energy and circulating water is greatly reduced.

Example 6

(1) The method comprises the following steps of (1) enabling an organic silicon crude monomer to enter a rectifying tower I1 at a flow rate of 25.5t/h, removing high-boiling gas-phase materials at the top of the rectifying tower I1, preferably enabling 35% of the gas-phase materials with volume fraction to enter a rectifying tower IV reboiler 10 as a heat source of a rectifying tower IV, enabling the remaining 65% of the gas-phase materials with volume fraction to enter a rectifying tower III reboiler 6 as a heat source, condensing by the reboiler, converging 85% of the gas-phase materials with volume fraction serving as tower reflux and returning to the top of the rectifying tower I1 through a rectifying tower III-coupled reflux pump 14 and a rectifying tower IV-coupled reflux pump 16, feeding 15% of the gas-phase materials with volume fraction serving as a rectifying tower II 2, and extracting crude high-boiling 21 from the tower kettle; the top temperature of the rectifying tower 1 is controlled at 125 ℃, and the top pressure is controlled at 0.38MPa.

(3) The third 3 tower bottom of the rectifying tower adopts a second reboiler, a rectifying tower triple steam reboiler 7 as a supplementary heat source, all gas phase materials at the tower top enter a second tower bottom reboiler 8 of the rectifying tower as a heat source, after the gas phase materials are condensed by the second tower bottom thermal coupling reboiler 8 of the rectifying tower, 99% volume fraction materials are returned to the third 3 tower top of the rectifying tower as tower reflux through a third reflux pump 13 of the rectifying tower, 1% volume fraction materials are extracted as a methyltrichlorosilane product 22, and a dimethyldichlorosilane product 23 is extracted at the tower bottom; the temperature at the top of the third rectifying tower 3 is controlled at 107 ℃, the pressure at the top of the third rectifying tower is controlled at 0.2MPa, and if the temperature at the top of the third rectifying tower 3 can be controlled at 120 ℃ and the pressure at the top of the third rectifying tower is controlled at 0.28MPa as the heat source of the third rectifying tower in the steps, a third steam reboiler 7 of a second reboiler rectifying tower is not needed as a supplementary heat source.

(4) The gas phase at the top of the second rectifying tower 2 is condensed by a second rectifying tower condenser 9 and enters a second rectifying tower reflux groove 18, the material in the second rectifying tower reflux groove 18 is conveyed by a second rectifying tower reflux pump 15 to be 98% volume fraction material as tower reflux and returns to the top of the second rectifying tower 2, the other part of the extracted component 24 with the boiling point lower than that of the methyl trichlorosilane enters a subsequent rectifying tower for separation, the material extracted by the second rectifying tower 2 is conveyed by a second rectifying tower kettle liquid pump 14 to be used as a third rectifying tower 3, and the rest 40% volume fraction material is obtained to be used as a fourth rectifying tower 4 for feeding; the temperature of the second 2 tower bottom of the rectifying tower is controlled at 90 ℃, and the pressure of the tower bottom is controlled at 0.07MPa.

Because the pressure at the top of the first rectifying tower 1 is controlled to be below 0.4MPa, the temperature at the top of the first rectifying tower 1 is correspondingly reduced to be below 125 ℃; controlling the temperature at the top of the third rectifying tower to be more than 0.25MPa, and correspondingly increasing the temperature at the top of the third rectifying tower to be more than 120 ℃; the conditions do not satisfy that the temperature of the gas phase at the top of the first rectifying tower 1 is 15-60 ℃ higher than the temperature of the kettle of the third rectifying tower, so that the reboiler 5 of the first rectifying tower 1 cannot effectively provide heat for the reboiler 6 of the third rectifying tower, and the system cannot normally operate.

Example 7

(3) The third 3 tower bottom of the rectifying tower adopts a second reboiler, a rectifying tower triple steam reboiler 7 as a supplementary heat source, all gas phase materials at the tower top enter a second tower bottom reboiler 8 of the rectifying tower as a heat source, after the gas phase materials are condensed by the second tower bottom thermal coupling reboiler 8 of the rectifying tower, 99% volume fraction materials are returned to the third 3 tower top of the rectifying tower as tower reflux through a third reflux pump 13 of the rectifying tower, 1% volume fraction materials are extracted as a methyltrichlorosilane product 22, and a dimethyldichlorosilane product 23 is extracted at the tower bottom; the top temperature of the third rectifying tower 3 is controlled at 105 ℃, the top pressure is controlled at 0.18MPa, and if the top temperature of the third rectifying tower 3 can be controlled at 107 ℃ and the top pressure is controlled at 0.2MPa as the heat source of the third rectifying tower in the steps, a second reboiler, a third steam reboiler 7 of the rectifying tower is not needed as a supplementary heat source.

(4) The gas phase at the top of the second rectifying tower 2 is condensed by a second rectifying tower condenser 9 and enters a second rectifying tower reflux groove 18, the material in the second rectifying tower reflux groove 18 is conveyed by a second rectifying tower reflux pump 15 to be 98% volume fraction material as tower reflux and returns to the top of the second rectifying tower 2, the other part of the extracted component 24 with the boiling point lower than that of the methyl trichlorosilane enters a subsequent rectifying tower for separation, the material extracted by the second rectifying tower 2 is conveyed by a second rectifying tower kettle liquid pump 14 to be used as a third rectifying tower 3, and the rest 40% volume fraction material is obtained to be used as a fourth rectifying tower 4 for feeding; the temperature of the second 2 tower bottom of the rectifying tower is controlled at 95 ℃, and the pressure of the tower bottom is controlled at 0.08MPa. Because the temperature of the third rectifying tower is only 10 ℃ higher than that of the second rectifying tower, the temperature difference between the third rectifying tower and the second rectifying tower is small, the second rectifying tower cannot reach the working reflux ratio, the product is unstable, and the system cannot normally operate.

The steps and the process conditions are the same as those of the example 7, the temperature of the top of the rectifying tower III 3 is controlled at 115 ℃, and the pressure of the top of the rectifying tower III is controlled at 0.25MPa. The temperature of the second 2 rectifying tower kettle is controlled at 84 ℃, and the pressure of the tower kettle is controlled at 0.05MPa. Because the temperature of the third rectifying tower is higher than that of the second rectifying tower by 31 ℃, the temperature difference between the third rectifying tower and the second rectifying tower is large, the heat received by the second rectifying tower is too much, the working reflux ratio cannot be reached, the product is unstable, and the system cannot normally operate.

Claims

1. A crude monomer rectification energy-saving device is characterized in that a crude monomer feeding pipe is connected with a first rectifying tower (1);

the top of the rectifying tower I (1) is respectively connected with a rectifying tower four-tower kettle reboiler (10) arranged at the bottom of the rectifying tower four (4) and a rectifying tower three-tower kettle reboiler (6) arranged at the bottom of the rectifying tower three (3) through a gas phase pipeline;

a rectifying tower three-tower kettle reboiler (6) and a rectifying tower four-tower kettle reboiler (10) are converged through a gas phase pipeline and then are connected with a rectifying tower two (2);

the bottom of the second rectifying tower (2) is respectively connected with a third rectifying tower (3) and a fourth rectifying tower (4) through liquid phase pipelines.

2. The energy-saving device for crude monomer rectification according to claim 1, wherein the gas phase pipelines of the rectifying tower three-tower kettle reboiler (6) and the rectifying tower four-tower kettle reboiler (10) are respectively provided with a rectifying tower three-coupling reflux pump (12) and a rectifying tower four-coupling reflux pump (16) before being merged.

3. The energy-saving device for crude monomer rectification according to claim 2, wherein a reboiler (8) of the second rectifying tower kettle is arranged at the bottom of the second rectifying tower (2), and the top of the third rectifying tower (3) is connected with the reboiler (8) of the second rectifying tower kettle arranged at the bottom of the second rectifying tower (2) through a gas phase pipeline.

4. The energy-saving crude monomer rectification device according to claim 3, wherein the reboiler (8) in the second kettle of the rectification column is connected to the third rectification column (3) through the third reflux pump (13) of the rectification column, and one way is connected to the first discharge pipe (22).

5. The energy-saving crude monomer rectification device according to claim 4, wherein the top of the second rectification column (2) is connected with a second rectification column condenser (9), the second rectification column condenser (9) is connected with a second rectification column reflux tank (18), one path of the second rectification column reflux tank (18) is connected with the second rectification column (2) through a second rectification column reflux pump (15), and the other path is connected with a third discharge pipe (24).

6. The energy-saving device for crude monomer rectification according to claim 4, wherein a rectifying tower triple steam reboiler (7) is further arranged at the bottom of the rectifying tower III (3), and the bottom of the rectifying tower III (3) is connected to the discharging pipe II (23).

7. The energy-saving crude monomer rectification device according to claim 1, wherein the top of the rectifying tower four (4) is connected with a rectifying tower four condenser (11), the rectifying tower four condenser (11) is connected with a rectifying tower four reflux groove (19), one path of the rectifying tower four reflux groove (19) is connected with the rectifying tower four (4) through a rectifying tower four reflux pump (17), and the other path is connected with a discharge pipe four (25).

8. Crude monomer rectification energy saving device according to claim 7, characterized in that the rectification column four (4) is connected at the bottom to the discharge pipe five (26).

9. The energy-saving crude monomer rectification device according to claim 8, wherein the rectifying tower four-tower kettle reboiler (10) is connected with the upper part of the rectifying tower I (1) through the rectifying tower four-coupling reflux pump (16), and the rectifying tower three-tower kettle reboiler (6) is further connected with the upper part of the rectifying tower I (1) through the rectifying tower three-coupling reflux pump (12).

10. The energy-saving device for crude monomer rectification according to claim 9, characterized in that the bottom of the rectification column one (1) is connected to the crude high-boiling residue discharge pipe (21).

11. A crude monomer rectification energy-saving process is characterized by comprising the following steps:

(1) Feeding organosilicon crude monomer into a first rectifying tower 1, wherein gas-phase materials subjected to high boiling removal at the top of the first rectifying tower 1 are firstly fed into a fourth-tower kettle reboiler 10 of the rectifying tower as a heat source, and then fed into a third-tower kettle reboiler 6 of the rectifying tower as a heat source;

(2) Materials in two reboilers, namely a rectifying tower four-tower kettle reboiler 10 and a rectifying tower three-tower kettle reboiler 6 are condensed and converged to be used as a rectifying tower two 2 for feeding;

(3) And the material extracted from the second 2 tower bottom of the rectifying tower is conveyed by a second liquid pump 14 of the rectifying tower to be fed as a third 3 rectifying tower and a fourth 4 rectifying tower.

12. The energy-saving process for rectifying the crude monomers according to claim 11, wherein the crude organosilicon monomer in the step (1) is a mixture of methyl chlorosilane, and the main components and the mass fractions of the mixture are 6% -9% of monomethyl trichlorosilane, 82% -87% of dimethyl dichlorosilane, 2.8% -3.7% of trimethyl monochlorosilane, 1.3% -2% of monomethyl dichlorosilane and 0.05% -1% of silicon tetrachloride; the organosilicon crude monomer enters a rectifying tower I1 at the flow rate of 20-35 t/h.

13. The energy-saving process for rectifying the crude monomer as claimed in claim 12, wherein in the step (1), the temperature of the top of the rectifying tower is controlled to be 130-140 ℃, and the pressure of the top of the rectifying tower is controlled to be 0.40-0.55MPa; preferably, the top temperature of the first rectifying tower 1 is controlled at 135 ℃, and the top pressure is controlled at 0.45MPa.

14. The energy-saving process for rectifying the crude monomer as claimed in claim 13, wherein in step (1), 35-45% of high-boiling gas phase materials removed from the top of the first rectifying tower 1 enter a four-tower kettle reboiler 10 of the rectifying tower as a heat source, and the rest gas phase materials enter a three-tower kettle reboiler 6 of the rectifying tower as a heat source.

15. The energy-saving process for rectifying the crude monomer according to claim 14, wherein in the step (1), the high-boiling gas phase material removed from the top of the first rectifying tower 1 is fed into the reboiler 10 of the fourth rectifying tower kettle for use as a heat source by 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44% or 45%, and after the heat source is supplemented, the rest gas phase material is fed into the reboiler 6 of the third rectifying tower for use as a heat source.

16. The energy-saving crude monomer rectification process according to claim 11, wherein the gas phase at the top of the fourth 4 tower top of the rectification tower is condensed by the fourth condenser 11 of the rectification tower and enters the fourth reflux tank 19 of the rectification tower, a part of the material in the fourth reflux tank 19 of the rectification tower is conveyed by the fourth reflux pump 17 of the rectification tower to return to the top of the fourth 4 tower as tower reflux, the other part of the material is used for producing a trichlorosilane product 25, and the fourth 4 tower bottom of the rectification tower is used for producing a dimethyldichlorosilane product 26.

17. The energy-saving process for rectifying the crude monomer according to claim 16, wherein the temperature of the four-tower kettle of the rectifying tower is controlled to be 85-95 ℃, and the pressure of the tower kettle is controlled to be 0.05-0.10MPa; as a preferable scheme, the temperature of the four 4 tower kettles of the rectifying tower is controlled at 90 ℃, and the pressure of the tower kettles is controlled at 0.07MPa.

18. The energy-saving process for rectifying the crude monomer according to claim 17, wherein 98.5% -99% of the material in the rectifying tower four-reflux tank 19 is conveyed by the rectifying tower four-reflux pump 17 to return to the top of the rectifying tower four 4 as tower reflux, and a methyltrichlorosilane product 25 is produced in the rest.

19. The energy-saving process for rectifying crude monomers according to claim 22, wherein the gas phase material at the top of the rectifying tower three 3 enters the reboiler 8 at the bottom of the rectifying tower two, and is used as a heat source, after being condensed by the reboiler 8 at the bottom of the rectifying tower two, a part of the gas phase material is used as tower reflux and returns to the top of the rectifying tower three 3 through the three reflux pumps 13 of the rectifying tower, the other part of the gas phase material is used as a methyltrichlorosilane product 22, and a dimethyldichlorosilane product 23 is extracted at the bottom of the rectifying tower three 3.

20. The energy-saving process for rectifying the crude monomer as claimed in claim 23, wherein a reboiler 7 for triple vapor in the rectifying tower is used as a supplementary heat source in the third 3 tower bottom of the rectifying tower, and all gas phase materials at the top of the rectifying tower 3 enter a reboiler 8 for the second tower bottom of the rectifying tower as a heat source.

21. The energy-saving crude monomer rectification process according to claim 23, wherein the temperature at the top of the three rectifying towers is controlled to be 105-115 ℃, and the pressure at the top of the three rectifying towers is controlled to be 0.15-0.25MPa; preferably, the top temperature of the third 3 rectifying tower is controlled at 107 ℃, and the top pressure is controlled at 0.2MPa.

22. The energy-saving process for rectifying crude monomers as claimed in claim 23, wherein 98.5% -99% of reflux of the rectifying tower III reflux pump 13 is returned to the top of the rectifying tower III 3 as tower reflux, and the rest is extracted as the methyltrichlorosilane product 22.

23. The energy-saving process for rectifying the crude monomer according to claim 15, wherein in the step (2), after condensation of heat sources in the four-tower kettle reboiler 10 of the rectifying tower and the three-tower kettle reboiler 6 of the rectifying tower, the heat sources are converged by the three-coupling reflux pump 12 of the rectifying tower and the four-coupling reflux pump 16 of the rectifying tower respectively, 10% -15% of the heat sources are used as feed of the second rectifying tower 2, and 85% -90% of the heat sources are used as reflux of the first rectifying tower 1.

24. The energy-saving process for rectifying the crude monomer according to claim 16, wherein in the step (2), after heat sources in the reboiler 10 at the four towers of the rectifying tower and the reboiler 6 at the three towers of the rectifying tower are condensed and converged by the reflux pump 12 at the three towers of the rectifying tower and the reflux pump 16 at the four towers of the rectifying tower respectively, 10%, 11%, 12%, 13%, 14% and 15% of the condensed heat sources are used as feed materials for the second rectifying tower 2, and the rest of the condensed heat sources are used as tower reflux and returned to the top of the first rectifying tower 1.

25. The energy-saving process for rectifying the crude monomer according to claim 17, wherein in the step (2), the temperature of the second tower kettle of the rectifying tower is controlled to be 84-95 ℃, and the pressure of the second tower kettle of the rectifying tower is controlled to be 0.05-0.13MPa, and as a preferable scheme, the temperature of the second tower kettle of the rectifying tower 2 is controlled to be 90 ℃, and the pressure of the second tower kettle of the rectifying tower is controlled to be 0.07MPa.

26. The energy-saving process for rectifying the crude monomer according to claim 18, wherein in the step (2), the gas phase at the top of the second rectifying tower 2 is condensed by the second rectifying tower condenser 9 and enters the second rectifying tower reflux tank 18, the material in the second rectifying tower reflux tank 18 is conveyed by the second rectifying tower reflux pump 15 to one part to be used as tower reflux and return to the top of the second rectifying tower 2, and the low-boiling-point substances are extracted from the other part.

27. The energy-saving process for rectifying the crude monomer as claimed in claim 19, wherein in the step (2), more than or equal to 97% of the material in the second reflux tank 18 of the rectifying tower is conveyed by the second reflux pump 15 of the rectifying tower to return to the top of the second rectifying tower 2 as tower reflux, and the rest of the component 24 with the boiling point below 66.4 ℃ under the extraction normal pressure enters a subsequent rectifying tower for separation.

28. The energy-saving process for rectifying the crude monomer according to claim 11, wherein in the step (3), 60 to 70 percent of the distillate from the second 2 tower bottom of the rectifying tower is conveyed by a second tower bottom liquid pump 14 of the rectifying tower to be used as the feed of a third 3 rectifying tower, and the rest is used as the feed of a fourth 4 rectifying tower.

29. The energy-saving process for rectifying crude monomers according to claim 21, wherein in the step (3), 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70% of the distillate from the second 2-stage distillation column is first fed by the second-stage distillation column liquid pump 14 to serve as the feed for the third 3-stage distillation column, and the remainder after the third 3-stage distillation column is fed is used as the feed for the fourth 4-stage distillation column.

30. The energy-saving process for rectifying the crude monomer according to claim 11, wherein the temperature of the gas phase at the top of the rectifying tower I1 is 15-60 ℃ higher than the temperature of the bottoms of the rectifying tower III and the rectifying tower IV, and crude high boiling 21 is extracted from the bottom of the rectifying tower I1.

31. The energy-saving process for rectifying the crude monomer according to claim 30, wherein the temperature of the gas phase at the top of the third rectifying tower 3 is 15-20 ℃ higher than the temperature of the bottom of the second rectifying tower 2.

32. The energy-saving process for rectifying crude monomers according to any one of claims 11 to 31, characterized in that it adopts a process implemented by the device according to any one of claims 1 to 10.