CN216856196U - Vacuum system for cracking dimethyl dichlorosilane hydrolysate and rectifying ring body - Google Patents

Abstract

The utility model discloses a dimethyl dichlorosilane hydrolysate cracking and loop body rectifying vacuum system which comprises an air inlet pipeline and a tail gas condensing tank connected with the air inlet pipeline, wherein a spiral condensing pipe is arranged inside the tail gas condensing tank, the bottom of the tail gas condensing tank is connected with a collecting tank through a liquid pipeline, the top of the tail gas condensing tank is connected with a washing tower through a first communication pipeline, a washing conveying pipeline is arranged on the washing tower, a circulating pipeline is arranged at the bottom of the washing tower, a circulating pump is arranged on the circulating pipeline, the outlet of the circulating pipeline is communicated with the washing conveying pipeline, a finished product pipeline is arranged on the circulating pipeline, the outlet of the finished product pipeline is connected with a product tank, a second communication pipeline is arranged at the top of the washing tower, and a buffer tank, a vacuum unit and an incineration device are sequentially arranged at the outlet of the second communication pipeline. The system has the advantages of reasonable system setting, low energy consumption, thorough rectification separation and stable system operation, and can bring good economic and social benefits to enterprises.

Description

Vacuum system for cracking dimethyl dichlorosilane hydrolysate and rectifying ring body

Technical Field

The utility model belongs to the technical field of organic silicon production processes, and particularly relates to a vacuum system for cracking a dimethyldichlorosilane hydrolysate and rectifying a ring body.

Background

The dimethyl dichlorosilane hydrolysate is cracked under the conditions of high vacuum and high temperature to produce dimethyl siloxane mixed cyclic body, the dimethyl siloxane mixed cyclic body comprises cyclic bodies such as hexamethylcyclotrisiloxane (D3 for short), octamethylcyclotetrasiloxane (D4 for short), decamethylcyclopentasiloxane (D5 for short) and dodecamethylcyclohexasiloxane (D6 for short), the dimethyl siloxane mixed cyclic body is rectified through the cyclic body, and D3, DMC (the main components are D4 and D5 and trace D3) and D5 are separated by vacuum rectification according to requirements, so that the dimethyl siloxane mixed cyclic body is reused. However, the high vacuum degree is required to be maintained in the cracking process of the dimethyl dichlorosilane hydrolysate and the ring body, and a special vacuum pumping system is required to be arranged in a matching way. Therefore, a large amount of low boiling point substances (mainly water, air, hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and the like) generated by cracking the dimethyl dichlorosilane hydrolysate need to be discharged to an external system after being collected by a matched vacuum unit, and the cracking system is kept to be always in a high vacuum environment, at present, because the normal pressure freezing point of the hexamethylcyclotrisiloxane (D3) in the low boiling point substances is only 64 ℃ and the normal pressure freezing point of the octamethylcyclotetrasiloxane (D4) is only 17.2 ℃, the low boiling point substances are easy to cause equipment and pipeline blockage under a vacuum environment with a lower temperature, cause equipment failure and system vacuum fluctuation, influence the stable start of the system and cause unstable separation quality, in the prior art, in order to ensure the stable operation of the vacuum system during cracking of the dimethyl dichlorosilane hydrolysate, generally, vacuum tail gas generated by cracking is condensed by a heat exchanger, and then materials brought out by condensation are recovered, so that on one hand, high-boiling-point materials such as octamethylcyclotetrasiloxane (D4 for short) and decamethylcyclopentasiloxane (D5 for short) can be recovered, and on the other hand, hexamethylcyclotrisiloxane (D3) is prevented from being condensed and solidified, and equipment and pipeline blockage is avoided. For example, the patent CN202110858553.0 proposes that gas generated in the cracking process of dimethyl dichlorosilane hydrolysate is subjected to heat exchange to 60-80 ℃ through a heat exchanger, then is separated through a suspension separating tank, then is subjected to primary vacuum pumping through a Roots vacuum unit, then is subjected to secondary vacuum pumping through the heat exchanger to control the gas temperature to 7-95 ℃, and finally is subjected to secondary vacuum pumping through the Roots vacuum unit, and the conditions of two groups of heat exchangers are adopted for control, so that the high vacuum of a cracking system can be maintained, and the condition that hexamethylcyclotrisiloxane (D3 for short) is not crystallized or the crystallization amount is small does not influence the operation of the vacuum unit is ensured. Although this system can solve the schizolysis evacuation tail gas blockage problem to a certain extent, still exist like six methyl cyclotrisiloxanes (be referred to for a short as D3), eight methyl cyclotetrasiloxane (be referred to for a short as D4) etc. valuable material carry-over volume along with the vacuum unit great, the separation thoroughly causes the extravagant condition of material, and adopt 2 level heat exchanger to condense, the heat transfer temperature control degree of difficulty is big, the energy consumption is big, not only can increase the cost of operation, and influenced by the temperature, the system very easily has the circumstances such as shutting down the thermoregulation, clearance pipeline. Therefore, it is objectively needed to develop a dimethyldichlorosilane hydrolysate cracking and ring body rectification vacuum system with reasonable system setup, low energy consumption, thorough rectification and separation and stable system operation.

Disclosure of Invention

The utility model aims to provide a vacuum system for cracking the dimethyldichlorosilane hydrolysate and rectifying the ring body, which has the advantages of reasonable system arrangement, low energy consumption, thorough rectification separation and stable system operation.

The utility model aims to realize the purpose, which comprises an air inlet pipeline and a tail gas condensing tank connected with the air inlet pipeline, wherein a spiral condensing pipe is arranged inside the tail gas condensing tank, a liquid pipeline is arranged at the bottom of the tail gas condensing tank, the outlet of the liquid pipeline is connected with a collecting tank, a first communicating pipeline is arranged at the top of the tail gas condensing tank, the outlet of the first communicating pipeline is connected with a washing tower, a washing conveying pipeline is arranged on the washing tower above the first communicating pipeline, a first control valve is arranged on the washing conveying pipeline, a circulating pipeline is arranged at the bottom of the washing tower, a circulating pump is arranged on the circulating pipeline, the outlet of the circulating pipeline is communicated with the washing conveying pipeline between the first control valve and the washing tower, a finished product pipeline is arranged on the circulating pipeline between the circulating pump and the washing tower, a second control valve is arranged on the finished product pipeline, and the outlet of the finished product pipeline is connected with a product tank, the top of the washing tower is provided with a second communicating pipeline, and an outlet of the second communicating pipeline is sequentially provided with a buffer tank, a vacuum unit and an incineration device.

The system has the beneficial effects that firstly, the tail gas condensing tank is utilized to condense the dimethyl siloxane mixed ring body, and the heat exchange area of the spiral condensing pipe in the tail gas condensing tank is large, so that the temperature of a heat exchange medium in the spiral condensing pipe is easier to control when the heat exchange medium exchanges heat with the dimethyl siloxane mixed ring body and cools, the condensing effect is good, the structure not only can condense the dimethyl siloxane mixed ring body under a relatively stable temperature condition, but also can condense most of the ring body of the dimethyl siloxane mixed ring body and then recycle the condensed dimethyl siloxane mixed ring body, the blocking condition of the condensing pipe is avoided, the stable operation of the process system is effectively ensured, the consumption of heat energy can be effectively reduced, and the operation cost is further reduced; secondly, the system utilizes the washing tower to wash the dimethyl siloxane mixed ring body which is not completely condensed, the components in the dimethyl siloxane mixed ring body can be thoroughly separated, the arrangement of the washing tower can thoroughly avoid the condition that the ring body is brought out along with a vacuum unit to cause material waste, the recovery rate of the ring body is greatly improved, and meanwhile, the washed dimethyl siloxane mixed ring body can enter the washing tower to be recycled, so that the waste of washing liquid resources can be avoided.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic view of the structure of a washing column 6 in the present invention;

FIG. 3 is a schematic top view of the shower 63;

1-gas inlet pipeline, 2-tail gas condensing tank, 21-spiral condensing pipe, 3-liquid pipeline, 4-collecting tank, 5-first communicating pipeline, 6-washing tower, 61-top outlet, 62-gas inlet, 63-spray pipe, 631-ring pipe, 632-liquid inlet main pipe, 633-distribution pipe, 64-gas distributor, 641-distribution cone, 642-gas distribution hole, 643-liquid baffle cone, 65-packing layer, 66-bottom outlet, 67-demister, 68-liquid level meter, 69-horizontal pipe, 610-washing pipe, 7-washing conveying pipeline, 8-circulating pump, 9-circulating pipeline, 10-finished product pipeline, 11-product tank, 12-second communicating pipeline, 13-buffer tank, 14-vacuum unit, 15-incineration device.

Detailed Description

The utility model is further described with reference to the accompanying drawings, but the utility model is not limited in any way, and any variations or modifications based on the teachings of the utility model are within the scope of the utility model.

As shown in fig. 1 to 3, the utility model comprises an air inlet pipeline 1 and a tail gas condensation tank 2 connected with the air inlet pipeline 1, wherein a spiral condensation pipe 21 is arranged inside the tail gas condensation tank 2, a liquid pipeline 3 is arranged at the bottom of the tail gas condensation tank 2, a collection tank 4 is connected to the outlet of the liquid pipeline 3, a first communication pipeline 5 is arranged at the top of the tail gas condensation tank 2, a washing tower 6 is connected to the outlet of the first communication pipeline 5, a washing conveying pipeline 7 is arranged on the washing tower 6 above the first communication pipeline 5, a first control valve is arranged on the washing conveying pipeline 7, a circulation pipeline 9 is arranged at the bottom of the washing tower 6, a circulation pump 8 is arranged on the circulation pipeline 9, the outlet of the circulation pipeline 9 is communicated with the washing conveying pipeline 7 between the first control valve and the washing tower 6, a finished product pipeline 10 is arranged on the circulation pipeline 9 between the circulation pump 8 and the washing tower 6, the finished product pipeline 10 is provided with a second control valve, the outlet of the finished product pipeline 10 is connected with a product tank 11, the top of the washing tower 6 is provided with a second communicating pipeline 12, and the outlet of the second communicating pipeline 12 is sequentially provided with a buffer tank 13, a vacuum unit 14 and an incineration device 15.

The process of cracking the dimethyl dichlorosilane hydrolysate and rectifying the ring body by adopting the system comprises the following steps:

condensation treatment: introducing dimethyl siloxane mixed ring bodies with the temperature of more than 110 ℃ generated in the cracking process of dimethyl dichlorosilane hydrolysate into a tail gas condensing tank 2 through an air inlet pipeline 1, wherein the dimethyl siloxane mixed ring bodies comprise hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane and dodecamethylcyclohexasiloxane, introducing a condensing medium into the tail gas condensing tank 2 through a spiral condensing pipe 21, the condensing medium is hot water, the inlet temperature of the condensing medium is controlled to be 70-90 ℃, condensing the dimethyl siloxane mixed ring bodies by using the condensing medium to form mixed ring body condensate and mixed ring body noncondensable gas, the outlet temperature of the mixed ring body condensate is 50-60 ℃, discharging the mixed ring body condensate formed by condensation from the bottom of the tail gas condensing tank 2, and introducing the mixed ring body condensate into a collecting tank 4 through a liquid pipeline 3, the non-condensable gas of the mixed ring body is discharged from the top of the tail gas condensation tank 2, the mass percentage contents of the hexamethylcyclotrisiloxane, the octamethylcyclotetrasiloxane and the decamethylcyclopentasiloxane in the non-condensable gas of the mixed ring body are respectively 0.03%, 85% and 14.97%, and the dimethyl siloxane mixed ring body is condensed by using a condensing medium, so that the temperature for heat exchange and cooling between the condensing medium and the dimethyl siloxane mixed ring body is easier to control, the condensing effect is better, the dimethyl siloxane mixed ring body can be condensed under a more stable temperature condition, the condition of blocking of a condensing pipe is avoided, the stable operation of a process system is effectively ensured, the consumption of heat energy can be effectively reduced, and the operation cost can be effectively reduced;

washing treatment: introducing mixed ring noncondensable gas discharged from the top of a tail gas condensation tank 2 into the lower part of a washing tower 6 through a first communication pipeline 5, introducing washing liquid from the upper part of the washing tower 6 through a washing conveying pipeline 7, wherein the washing liquid is a mixture consisting of hexamethylcyclotrisiloxane or hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane and decamethylcyclopentasiloxane, washing the mixed ring noncondensable gas in the gas inlet washing tower 6 by using the washing liquid, and respectively obtaining clean tail gas and ring washing water after the countercurrent mass transfer and heat transfer of the mixed ring noncondensable gas and the washing liquid, wherein the washing is carried out by using the principle that similar phases are dissolved and difficult to solidify after mutual dissolution, and the washing liquid is used for fully washing the mixed ring noncondensable gas, so that the components in the mixed ring noncondensable gas can be thoroughly separated, and the condition that the ring is brought out along with a vacuum unit 14 to cause material waste is thoroughly avoided, the recovery rate of the loop body is greatly improved, the obtained loop body washing water is discharged from the bottom of the washing tower 6, a part of the discharged loop body washing water is conveyed into the washing tower 6 through the circulating pump 8 and the circulating pipeline 9 for recycling, and the circulating amount of the loop body washing water conveyed into the washing tower 6 through the circulating pump 8 and the circulating pipeline 9 is controlled to be 1-10 m³And h, the other part is conveyed into a product groove 11 through a finished product pipeline 10, the obtained clean tail gas is discharged from the top of the washing tower 6 and conveyed into a buffer tank 13 through a second communication pipeline 12, the clean tail gas is vacuumized by a vacuum unit 14 and then conveyed into an incineration device 15 for incineration treatment, the incompletely condensed dimethyl siloxane mixed ring body is washed by the washing tower 6, the components in the dimethyl siloxane mixed ring body can be thoroughly separated, the condition that the ring body is brought out along with the vacuum unit 14 to cause material waste can be thoroughly avoided by the arrangement of the washing tower 6, the recovery rate of the ring body is greatly improved, and meanwhile, the washed dimethyl siloxane mixed ring body can enter the washing tower 6 for recycling, so that the waste of washing liquid resources can be avoided.

In order to avoid the condition that condensation temperature fluctuates due to heat loss in the condensation process of the dimethyl siloxane mixed ring body of the tail gas condensation tank 2, the outer side of the tail gas condensation tank 2 is provided with a heat preservation layer, and the heat preservation layer can be made of mineral wool, rock wool, glass wool, aluminum silicate wool, asbestos and the like used in the prior art.

Further, the washing tower 6 comprises an upper sealing head, a cylinder, a lower sealing head and a skirt which are sequentially arranged from top to bottom, the top of the upper sealing head is provided with a top outlet 61 communicated with a second communication pipeline 12, the lower part of the cylinder is provided with an air inlet 62 communicated with a first communication pipeline 5, the upper part in the cylinder is provided with a spray pipe 63 communicated with a washing conveying pipeline 7, a gas distributor 64 and a packing layer 65 are arranged in the cylinder between the air inlet 62 and the spray pipe 63 from bottom to top, the gas distributor 64 has a uniform distribution effect on the ring body noncondensable gas entering the washing tower 6, the packing layer 65 has an effect of increasing the contact area of the ring body noncondensable gas and the washing liquid so as to ensure the smooth mass transfer and heat transfer of the ring body noncondensable gas and the washing liquid, the gas distributor 64 comprises a distribution cone 641 with a conical structure, and a plurality of layers of gas distribution holes 642 are uniformly distributed and processed on the circumference of the distribution cone 641, a liquid blocking cone 643 is vertically arranged on the outer wall of the distribution cone 641 at the lower side of each layer of gas distribution holes 642, the liquid blocking cone 643 is of a structure with a large upper end and a small lower end, and a bottom outlet 66 communicated with a circulation pipeline 9 is arranged at the bottom of the lower seal head. The distribution awl 641 is the ascending toper of closed angle, compares with planar gas distribution board, has increased the surface area, can reduce the resistance, increases the gas-liquid contact effect to still be equipped with on the distribution awl 641 and keep off liquid awl 643, keep off liquid awl 643 can block the washing liquid, prevents that the washing liquid from flowing to barrel inner wall department, in order to guarantee that washing liquid and ring body noncondensable gas fully contact.

Preferably, the shower 63 includes the ring pipe 631 and the feed liquor is responsible for 632, ring pipe 631 is installed in the barrel, feed liquor is responsible for 632 horizontal installation between ring pipe 631, the upper portion center department that feed liquor was responsible for 632 communicates with washing pipeline 7 through central return bend, many distribution pipes 633 with the ring pipe 631 intercommunication are installed perpendicularly to feed liquor is responsible for 632 both sides, ring pipe 631, distribution pipe 633 and feed liquor are responsible for the bottom of 632 and all the equipartition and are provided with a plurality of mouths that spray, can let like this enter into the washing liquid evenly distributed in the scrubbing tower 6, let the washing liquid in packing layer 65 abundant with the contact of the noncondensable gas of ring body, further improvement washing separation's effect. A demister 67 is arranged in the cylinder above the spray pipe 63, the demister 67 can remove washing liquid moisture carried in the clean tail gas, and the demister 67 is one of a tubular demister, a flat demister and a ridge demister.

For the effect of further improvement ring body rectification separation, be provided with level gauge 68 on the barrel of air inlet 62 below, level gauge 68 is used for monitoring the liquid level height of barrel lower part washing liquid, be provided with the horizontal pipe 69 with the air inlet 62 intercommunication in the barrel, the horizontal pipe 69 other end is sealed through the shrouding, the equidistant vertical many washtubs 610 that are provided with in bottom of horizontal pipe 69, the lower extreme of washtub 610 extends to the below of level gauge 68, and the ring body noncondensable gas that enters into in the horizontal pipe 69 from air inlet 62 enters into each washtub 610 earlier to the direct washing liquid contact with the barrel bottom of flowing downwards, the mode that utilizes gas-liquid direct contact can improve the effect of rectification separation.

In order to prolong the service time of the packing layer 65, the packing material of the packing layer 65 is preferably ceramic or PTFE.

Preferably, the circulating pump 8 is a canned motor pump, and the canned motor pump is mainly selected to convey petrochemical liquids which are inflammable, explosive and highly toxic, so that the safety and reliability of the operation of the petrochemical device are improved.

Preferably, in order to ensure the stability and durability of the system operation, the vacuum unit 14 is one of a screw vacuum unit, a roots vacuum unit or a combination of the two.

Claims (8)

1. A vacuum system for cracking and ring rectification of dimethyl dichlorosilane hydrolysate is characterized by comprising an air inlet pipeline (1) and a tail gas condensation tank (2) connected with the air inlet pipeline (1), wherein a spiral condensation pipe (21) is arranged inside the tail gas condensation tank (2), a liquid pipeline (3) is arranged at the bottom of the tail gas condensation tank (2), an outlet of the liquid pipeline (3) is connected with a collection tank (4), a first communication pipeline (5) is arranged at the top of the tail gas condensation tank (2), an outlet of the first communication pipeline (5) is connected with a washing tower (6), a washing conveying pipeline (7) is arranged on the washing tower (6) above the first communication pipeline (5), a first control valve is arranged on the washing conveying pipeline (7), and a circulating pipeline (9) is arranged at the bottom of the washing tower (6), be provided with circulating pump (8) on circulating line (9), washing pipeline (7) intercommunication between the export of circulating line (9) and first control valve and scrubbing tower (6) is provided with finished product pipeline (10) on circulating line (9) between circulating pump (8) and scrubbing tower (6), be provided with the second control valve on finished product pipeline (10), the exit linkage of finished product pipeline (10) has product jar (11), the top of scrubbing tower (6) is provided with second intercommunication pipeline (12), the export of second intercommunication pipeline (12) has set gradually buffer tank (13), vacuum unit (14) and burns device (15).

2. The vacuum system for cracking dimethyldichlorosilane hydrolysate and rectifying rings as claimed in claim 1, wherein the scrubber tower (6) comprises an upper head, a cylinder, a lower head and a skirt which are sequentially arranged from top to bottom, the top of the upper head is provided with a top outlet (61) communicated with a second communication pipeline (12), the lower part of the cylinder is provided with an air inlet (62) communicated with the first communication pipeline (5), the upper part in the cylinder is provided with a spray pipe (63) communicated with the scrubbing and conveying pipeline (7), a gas distributor (64) and a packing layer (65) are arranged in the cylinder between the air inlet (62) and the spray pipe (63) from bottom to top, the gas distributor (64) comprises a distribution cone (641) with a conical structure, and a plurality of layers of gas distribution holes (642) are uniformly processed on the circumference of the distribution cone (641), liquid blocking cones (643) are vertically arranged on the outer walls of the distribution cones (641) on the lower sides of the gas distribution holes (642), the liquid blocking cones (643) are of structures with large upper ends and small lower ends, and bottom outlets (66) communicated with the circulating pipelines (9) are formed in the bottoms of the lower seal heads.

3. The vacuum system for cracking dimethyldichlorosilane hydrolysate and rectifying ring body according to claim 2, wherein the spray pipe (63) comprises a circular pipe (631) and a main liquid inlet pipe (632), the circular pipe (631) is installed in the cylinder, the main liquid inlet pipe (632) is horizontally installed between the circular pipes (631), the center of the upper part of the main liquid inlet pipe (632) is communicated with the washing conveying pipeline (7) through a central bent pipe, a plurality of distribution pipes (633) communicated with the circular pipe (631) are vertically installed on two sides of the main liquid inlet pipe (632), and a plurality of spray ports are uniformly distributed at the bottoms of the circular pipe (631), the distribution pipes (633) and the main liquid inlet pipe (632).

4. The vacuum system for cracking and rectifying the dimethyldichlorosilane hydrolysate as claimed in claim 3, wherein a demister (67) is arranged in the cylinder above the spray pipe (63), and the demister (67) is one of a tubular demister, a flat demister and a ridge demister.

5. The vacuum system for cracking of dimethyldichlorosilane hydrolysate and rectifying of ring body according to claim 3, characterized in that a liquid level meter (68) is arranged on the cylinder body below the air inlet (62), a horizontal pipe (69) communicated with the air inlet (62) is arranged in the cylinder body, the other end of the horizontal pipe (69) is sealed by a sealing plate, a plurality of washing pipes (610) are vertically arranged at the bottom of the horizontal pipe (69) at equal intervals, and the lower ends of the washing pipes (610) extend to the lower part of the liquid level meter (68).

6. The vacuum system for cracking dimethyldichlorosilane hydrolysate and rectifying rings as claimed in claim 2, wherein the packing material of the packing layer (65) is ceramic or PTFE.

7. The vacuum system for cracking dimethyldichlorosilane hydrolysate and rectifying ring body according to claim 1, wherein the circulating pump (8) is a canned motor pump.

8. The vacuum system for cracking dimethyldichlorosilane hydrolysate and rectifying annulus as claimed in claim 1, wherein the vacuum unit (14) is one or two of a screw vacuum unit, a Roots vacuum unit.

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