阅读说明：本技术 除去二甲基二氯硅烷水解所得氯化氢中油相杂质的方法 (Method for removing oil phase impurities in hydrogen chloride obtained by hydrolyzing dimethyl dichlorosilane ) 是由 宋祥录 由成君 付春荣 郑士朋 于 2020-05-08 设计创作，主要内容包括：本发明提出了除去二甲基二氯硅烷水解所得氯化氢中油相杂质的方法,其特征在于,所述方法采用甲基硅油作为吸收剂在吸收塔中吸收氯化氢原料中的油相杂质,塔顶得到氯化氢产品,塔釜排出的塔釜料经过水洗、分离后,排出含氯化氢的水层,得到含甲基硅油和所述油相杂质的油层,所述油层经过脱低系统分离后,分别得到油相杂质和甲基硅油,甲基硅油回收并返回所述吸收塔。所述方法能够将氯化氢原料中的油相杂质的含量由300ppm下降至80ppm以下。(The invention provides a method for removing oil-phase impurities in hydrogen chloride obtained by hydrolysis of dimethyldichlorosilane, which is characterized in that methyl silicone oil is used as an absorbent to absorb oil-phase impurities in a hydrogen chloride raw material in an absorption tower, a hydrogen chloride product is obtained at the tower top, tower bottom materials discharged from a tower bottom are washed with water and separated, a water layer containing hydrogen chloride is discharged, an oil layer containing methyl silicone oil and the oil-phase impurities is obtained, the oil layer is separated by a low-removal system, the oil-phase impurities and the methyl silicone oil are respectively obtained, and the methyl silicone oil is recovered and returned to the absorption tower. The method can reduce the content of oil phase impurities in the hydrogen chloride raw material from 300ppm to below 80 ppm.)

1. A method for removing oil-phase impurities in hydrogen chloride obtained by hydrolyzing dimethyldichlorosilane is characterized in that methyl silicone oil is used as an absorbent to absorb oil-phase impurities in hydrogen chloride raw materials in an absorption tower, a hydrogen chloride product is obtained at the tower top, a tower bottom material discharged from a tower bottom is washed with water and separated, a water layer containing hydrogen chloride is discharged, an oil layer containing methyl silicone oil and the oil-phase impurities is obtained, the oil layer is separated by a low-removing system, the oil-phase impurities and the methyl silicone oil are respectively obtained, and the methyl silicone oil is recovered and returned to the absorption tower.

2. Method according to claim 1, characterized in that it comprises the following steps:

(1) the hydrogen chloride raw material enters an absorption tower from a tower kettle, and the absorbent methyl silicone oil enters the absorption tower from the tower top;

(2) the methyl silicone oil meets the hydrogen chloride raw material at the packing layer and absorbs oil phase impurities in the hydrogen chloride raw material, and pure hydrogen chloride gas is obtained at the tower top;

(3) the methyl silicone oil enters the liquid accumulation disc after passing through the filler layer, part of the methyl silicone oil is powered by an upper circulating pump outside the absorption tower, and after being cooled, the methyl silicone oil returns to the absorption tower from the top of the tower;

(4) part of the methyl silicone oil overflows from the liquid accumulation disc to the tower kettle to form tower kettle materials, the tower kettle materials are conveyed to a water washing system from an outlet of the tower kettle, and meanwhile, part of the tower kettle materials are subjected to bottom circulation through a bottom circulating pump;

(5) after a water washing agent is added into the tower kettle material, water is washed by a water washer and separated by a separator in sequence, a water layer is taken as waste water and discharged out of a water washing system, and an oil layer is conveyed to a low-level removing system;

(6) and the oil layer is separated from the oil phase impurities in a falling film evaporator of a low-boiling-point removal system according to the difference of boiling points, and after separation, the methyl silicone oil returns to the absorption tower.

3. The method according to claim 2, wherein in step (1), the hydrogen chloride raw material comprises hydrogen chloride, oil phase impurities and water, wherein the oil phase impurities comprise at least one of cyclic siloxane, linear siloxane, cyclic polysiloxane or linear polysiloxane; the feeding temperature of the hydrogen chloride raw material is-10-40 ℃, and the hydrogen chloride raw material contains oil phase impurities of 100-500 ppm;

the absorbent comprises accumulated liquid on a partial liquid accumulation disc which is circularly cooled by the upper circulating pump and methyl silicone oil recovered by the low-removing system, and the feeding temperature of the absorbent is-30-0 ℃.

4. The method of claim 2, wherein in step (2), the packing layers comprise at least one layer of structured packing and at least one layer of bulk packing, and the packing layers are layers of structured packing and layers of bulk packing in a staggered fit;

the height of the regular packing layer is 1500-4000mm, and the height of the bulk packing layer is 1000-4000 mm.

5. The method according to claim 2, wherein in the step (1), the hydrogen chloride raw material enters the absorption tower from a raw material inlet at the bottom of the tower and then enters a gas distribution pipe, the gas distribution pipe is spirally laid at the bottom of the tower, the upper surface of the gas distribution pipe is provided with gas distribution holes, and the diameter of the gas distribution holes is 2-3 cm.

6. The method according to claim 2, wherein in the step (2), the hydrogen chloride gas is discharged from the top of the tower after being subjected to a demister to remove entrained liquid, and the demister can remove methyl silicone oil entrained in the hydrogen chloride gas and oil phase impurities condensed from the upper part of the absorption tower when the hydrogen chloride gas is cooled.

7. The method as claimed in claim 6, wherein a distributor is arranged below the demister, the distributor comprises a plurality of flow guide plates and distribution trays, one ends of the flow guide plates are arranged on the inner wall of the absorption tower, and form an angle of 10-70 degrees with the inner wall of the absorption tower; the distribution disc is arranged below the drainage plate, the upper surface of the distribution disc is provided with a plurality of sunken continuous or discontinuous diversion trenches, and the bottoms of the diversion trenches are provided with a plurality of through holes;

the distribution plate is provided with a plurality of air holes which penetrate through the upper surface and the lower surface of the distribution plate, and the air holes on the upper surface of the distribution plate are provided with air hole walls with the height of 1-3cm, so that the methyl silicone oil on the distribution plate cannot flow down through the air holes.

8. The method according to claim 2, wherein in the step (3), the flow rate of the methyl silicone oil circulated by the upper circulation pump is 1 to 10 t/h;

in the step (4), the liquid level of the tower kettle is maintained at 40-60% of the height of the tower kettle, and part of tower kettle materials exceeding the liquid level range are conveyed to a washing system from an outlet of the tower kettle.

9. The method as claimed in claim 2, wherein in the step (5), the water washing system comprises a feeder, a water washer and a separator which are sequentially connected through a pipeline, the tower bottoms are conveyed to the water washer through a bottom circulating pump outside the absorption tower, the feeder is used for adding the water washing agent into the water washer, and the mass ratio of the water washing agent to the tower bottoms entering the water washer is 1 (1-8);

stirring and mixing the tower bottom material and the water washing agent in a water washer, wherein the stirring speed is 60-150 revolutions per minute; then the tower bottoms and the rinsing agent enter a separator to be decanted, stand and layered, the lower layer is a water layer, the upper layer is an oil layer, the water layer comprises the rinsing agent and hydrogen chloride, the oil layer comprises methyl silicone oil and oil phase impurities, the water layer is used as a wastewater discharge rinsing system, and the oil layer is conveyed to a low-removal system to be separated.

10. The method according to claim 2, wherein in the step (6), the desuperheating system comprises a preheater, a first falling-film evaporator, a first vacuum separator, a second falling-film evaporator and a second vacuum separator which are connected in sequence;

the vacuum degree of the first vacuum separator is-0.09 to-0.095 MPa, and the vacuum degree of the second vacuum separator is-0.095 to-0.1 MPa;

the preheating temperature of the preheater is 140-150 ℃, the evaporation temperature of the first falling-film evaporator is 160-180 ℃, the heating temperature of the first vacuum separator is 180-190 ℃, the evaporation temperature of the second falling-film evaporator is 180-200 ℃, and the heating temperature of the second vacuum separator is 180-210 ℃.

Technical Field

The invention belongs to the technical field of organic silicon, and particularly relates to a method for removing oil phase impurities in hydrogen chloride obtained by hydrolyzing dimethyl dichlorosilane.

Background

The organic silicon compound is a chemical product or material with excellent performance, mainly comprises silicone oil, silicone resin, silicone rubber and the like, and is widely applied to the living fields of textiles, automobiles, buildings, electronics, cosmetics and the like and the special fields of national defense and the like. The organic silicon monomer is usually prepared by reacting silicon powder with methyl chloride, the product is mainly dimethyl dichlorosilane (hereinafter referred to as M2), M2 separated by rectification is further hydrolyzed to generate dimethyl siloxane hydrolysate and hydrogen chloride, and the hydrogen chloride returns to a methyl chloride synthesis device to react with methanol to produce the methyl chloride. However, the hydrogen chloride generated by hydrolysis of M2 contains some small molecular impurities, such as a short-chain body, a ring body, etc., and these impurities have important influence on the methyl chloride synthesis apparatus, which not only reduces the production efficiency of the reactor, causes the hydrochloric acid generated by methyl chloride to be seriously oiled and the COD to exceed the standard, but also these impurities are easy to adhere to the inner wall of the equipment or pipeline, and need to be shut down for cleaning.

The synthesis process and application of organosilicon product disclose a loop method constant boiling hydrochloric acid continuous hydrolysis M2 process, including a method for removing oil from concentrated hydrochloric acid after M2 hydrolysis: the M2 hydrolysate enters a delayer, concentrated hydrochloric acid at the lower layer is separated out, the concentrated hydrochloric acid is sent to a degumming tank, and the hydrolysate in the hydrochloric acid is further removed by settling; in addition, the concentrated acid hydrolysis process uses a method of combining cooling and a demister to remove hydrolysate in hydrogen chloride, and the method also has the defect that the hydrolysate in the hydrogen chloride is more remained.

Patent CN201380073230.4 proposes a method for removing siloxanes from a gas using lignite-lifted activated carbon, comprising flowing a siloxane-carrying gas stream through an adsorption medium to remove at least part of the siloxanes from the gas stream, wherein the adsorption medium comprises lignite-based activated carbon, and said lignite-based activated carbon can be regenerated. Patent US5,330,735 proposes a method for reducing the siloxane content by using polystyrene-based resin adsorption, and the polystyrene-based resin after adsorbing the siloxane can be washed, regenerated and recycled.

Patent CN201910980653.3 provides a method for removing siloxane from concentrated sulfuric acid containing siloxane, comprising: adding hydrogen peroxide into concentrated sulfuric acid containing siloxane to oxidize the siloxane into white carbon black, and filtering to remove the white carbon black. Extracting dilute hydrochloric acid containing siloxane by using concentrated sulfuric acid to separate out hydrogen chloride gas, transferring siloxane into sulfuric acid to obtain dilute sulfuric acid containing siloxane, and then carrying out vacuum concentration to obtain concentrated sulfuric acid containing siloxane.

Patent CN200610001362.8 discloses a method for reducing the siloxane content in hydrochloric acid obtained by hydrolysis of M2 by adopting a stirring mode, wherein hydrolysate and by-product hydrochloric acid are stirred to accelerate condensation of a short-chain body in the hydrolysate, the solubility in acid water is reduced after the chain of the short-chain body is lengthened, and then the short-chain body in the hydrochloric acid is separated out and dissolved in the hydrolysate to reduce the siloxane content in acid water.

At present, the method for removing oil-phase hydrolysate from M2 hydrolysis acid generally has the problems of low removal efficiency, high content of residual hydrolysate or influence on the subsequent production of organic silicon products.

Disclosure of Invention

In order to solve the problems, the invention provides a method for removing oil-phase impurities in hydrogen chloride obtained by hydrolyzing dimethyldichlorosilane, which adopts methyl silicone oil as an absorbent to absorb the oil-phase impurities in a hydrogen chloride raw material in an absorption tower, a hydrogen chloride product is obtained at the tower top, a tower bottom material discharged from a tower bottom is washed with water and separated, a water layer containing hydrogen chloride is discharged, an oil layer containing methyl silicone oil and the oil-phase impurities is obtained, the oil layer is separated by a low-removing system, the oil-phase impurities and the methyl silicone oil are respectively obtained, and the methyl silicone oil is recovered and returned to the absorption tower.

Preferably, the method for removing oil phase impurities in hydrogen chloride obtained by hydrolysis of dimethyldichlorosilane comprises the following steps:

(1) the hydrogen chloride raw material enters an absorption tower from a tower kettle, and the absorbent methyl silicone oil enters the absorption tower from the tower top;

(2) the methyl silicone oil meets the hydrogen chloride raw material at the packing layer and absorbs oil phase impurities in the hydrogen chloride raw material, and pure hydrogen chloride gas is obtained at the tower top;

(3) the methyl silicone oil enters the liquid accumulation disc after passing through the filler layer, part of the methyl silicone oil is powered by an upper circulating pump outside the absorption tower, and after being cooled, the methyl silicone oil returns to the absorption tower from the top of the tower;

(4) part of the methyl silicone oil overflows from the liquid accumulation disc to the tower kettle to form tower kettle materials, the tower kettle materials are conveyed to a water washing system from an outlet of the tower kettle, and meanwhile, part of the tower kettle materials are subjected to bottom circulation through a bottom circulating pump;

(5) after a water washing agent is added into the tower kettle material, water is washed by a water washer and separated by a separator in sequence, a water layer is taken as waste water and discharged out of a water washing system, and an oil layer is conveyed to a low-level removing system;

(6) and the oil layer is separated from the oil phase impurities in a falling film evaporator of a low-boiling-point removal system according to the difference of boiling points, and after separation, the methyl silicone oil returns to the absorption tower.

In the step (1), the hydrogen chloride raw material comprises hydrogen chloride, oil phase impurities and water, wherein the oil phase impurities comprise at least one of cyclic siloxane, linear siloxane, cyclic polysiloxane or linear polysiloxane.

The feeding temperature of the hydrogen chloride raw material is-10-40 ℃, and the hydrogen chloride raw material contains oil phase impurities of 100-500 ppm.

In the step (1), the absorbent comprises accumulated liquid on a partial liquid accumulation disc which is circularly cooled by the upper circulating pump and methyl silicone oil recovered by the low-removing system, and the feeding temperature of the absorbent is-30-0 ℃. Optionally, the absorbent may also include additional fresh methyl silicone oil as needed for the process to run.

In the step (2), the packing layers comprise at least one layer of structured packing layer and at least one layer of bulk packing layer, namely the packing layers are in a mode that the structured packing layers and the bulk packing layers are in staggered fit.

The height of the regular packing layer is 1500-4000mm, and the height of the bulk packing layer is 1000-4000 mm.

In the step (1), the hydrogen chloride raw material enters the absorption tower from a tower kettle raw material inlet and then enters a gas distribution pipe, the gas distribution pipe is spirally laid at the tower kettle and is immersed below the liquid level of the tower kettle, a plurality of gas distribution holes are formed in the upper surface of the gas distribution pipe, and the diameter of each gas distribution hole is 2-3 cm.

Preferably, the gas distribution pipe can further comprise a plurality of branches, and the branches are arranged between the structured packing layer and the bulk packing layer.

Preferably, in the step (2), the hydrogen chloride gas is discharged from a product outlet at the top of the tower after entrained liquid is removed by a demister, and the demister can remove methyl silicone oil entrained in the hydrogen chloride gas and oil phase impurities condensed from the upper part of the absorption tower when the hydrogen chloride gas is cooled.

Preferably, a distributor is arranged below the demister, the distributor comprises a plurality of flow guide plates and distribution discs, and one end of each flow guide plate is arranged on the inner wall of the absorption tower and forms an angle of 10-70 degrees with the inner wall of the absorption tower.

The distribution plate is arranged below the drainage plate, the upper surface of the distribution plate is provided with a plurality of sunken continuous or discontinuous diversion trenches, and the bottoms of the diversion trenches are provided with a plurality of through holes.

Preferably, the distribution disc is provided with a plurality of air holes for allowing relatively pure hydrogen chloride gas to pass through the distribution disc and reducing pressure drop in the absorption tower, the air holes are staggered with the bottom end of the drainage plate, so that falling methyl silicone oil is prevented from falling into the air holes, the air holes penetrate through the upper surface and the lower surface of the distribution disc, and the air holes in the upper surface of the distribution disc are provided with air hole walls with the height of 1-3cm, so that the methyl silicone oil on the distribution disc cannot flow down through the air holes.

In the step (3), the flow rate of the methyl silicone oil circulated by the upper circulating pump is 1-10 t/h;

in the step (4), the liquid level of the tower kettle is maintained at 40-60% of the height of the tower kettle, part of tower kettle materials exceeding the liquid level range are conveyed to a washing system from an outlet of the tower kettle, and part of tower kettle materials enter the tower kettle through a bottom circulating pump in a circulating reflux mode when the liquid level range is not exceeded.

In step (5), the washing system includes charging means, rinsing ware and the separator that connects gradually through the pipeline, the tower cauldron material by outside bottom circulating pump of absorption tower carries to the rinsing ware, and the charging means adds the washing agent to the rinsing ware, the washing agent is water, and tower cauldron material and washing agent intensive mixing in the rinsing ware, then decantation layering of stewing in tower cauldron material and washing agent entering separator, the lower floor is the water layer, and the upper strata is the oil layer, the water layer includes washing agent and hydrogen chloride, the oil layer includes methyl silicone oil and oil phase impurity, and the water layer is as waste water discharge washing system, and the oil layer is carried to low system of eluting and is further separated.

The mass ratio of the water washing agent to tower bottom materials entering the water washer is 1 (1-8).

The stirring speed of the water scrubber is 60-150 revolutions per minute.

In the step (6), the low-boiling-point removing system comprises a preheater, a first falling-film evaporator, a first vacuum separator, a second falling-film evaporator and a second vacuum separator which are sequentially connected, and after the tower bottom material is subjected to water phase separation in the water washing system, the separation of the methyl silicone oil and the oil phase impurities is carried out.

The vacuum degree of the first vacuum separator is-0.09 to-0.095 MPa, and the vacuum degree of the second vacuum separator is-0.095 to-0.1 MPa.

Preferably, the preheating temperature of the preheater is 140-.

The method for removing the oil phase impurities in the hydrogen chloride obtained by hydrolyzing the dimethyldichlorosilane has the following beneficial effects:

(1) the content of oil phase impurities in the hydrogen chloride raw material is reduced to below 80ppm from 100-500 ppm;

(2) when the obtained hydrogen chloride product is used for a methyl chloride reactor, the pollution to the reactor is slowed down, and the activity of the catalyst is maintained, so that the one-way conversion rate and the yield of methanol are improved, the sewage production is further reduced, wherein the one-way conversion rate of the methanol is improved from 96.1% to 98.2%, the yield is improved by about 3%, and the sewage discharge amount is reduced by 2.3%;

(3) the operation period of the water scrubber cooler in the methyl chloride device is increased, and the operation period of the methyl chloride device is doubled.

Drawings

FIG. 1 is a process diagram of an absorption tower and a water wash system.

FIG. 2 is a schematic view of a distribution plate.

FIG. 3 is a process diagram of a lowering system.

In the figure, 1-absorption tower, 101-product outlet, 102-absorbent inlet, 103-raw material inlet, 104-tower bottom material outlet, 105-tower bottom material inlet, 106-absorbent outlet, 2-packing layer, 201-first structured packing layer, 202-first bulk packing layer, 203-second structured packing layer, 204-second bulk packing layer, 3-gas distribution pipe, 4-demister, 5-distributor, 501-flow guide plate, 502-distribution plate, 503-flow guide groove, 504-through hole, 505-gas hole, 6-liquid collection plate, 7-upper circulating pump, 8-cooler, 9-liquid level sensor, 10-outlet control valve, 11-bottom circulating pump, 12-water washing system, 1201-feeder, 1202-water scrubber, 1203-separator, 13-desuperheater system, 1301-preheater, 1302-first falling-film evaporator, 1303-first vacuum separator, 1304-second falling-film evaporator, 1305-second vacuum separator.

Detailed Description

The present invention is described below based on embodiments, and it will be understood by those of ordinary skill in the art that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.

Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".

The invention provides a method for removing oil phase impurities in hydrogen chloride obtained by hydrolyzing dimethyldichlorosilane, aiming at the problems that the removal efficiency is low, the content of residual hydrolysate is high, or the subsequent production of organic silicon products is influenced in a method for removing the oil phase impurities in the hydrogen chloride obtained by hydrolyzing dimethyldichlorosilane, wherein methyl silicone oil is used as an absorbent to absorb the oil phase impurities in a hydrogen chloride raw material in an absorption tower 1, a hydrogen chloride product is obtained at the tower top, a mixture discharged from the tower bottom is washed by water and separated, a water layer containing hydrogen chloride is discharged to obtain an oil layer containing methyl silicone oil and the oil phase impurities, the oil layer is separated by a low removal system to respectively obtain the oil phase impurities and the methyl silicone oil, and the methyl silicone oil is recovered and returned to the absorption tower 1.

Preferably, the method for removing oil phase impurities in hydrogen chloride hydrolyzed by dimethyldichlorosilane comprises the following steps:

(1) the hydrogen chloride raw material enters the absorption tower 1 from the tower bottom, and the absorbent methyl silicone oil enters the absorption tower 1 from the tower top;

(2) the methyl silicone oil meets the hydrogen chloride raw material at the packing layer 2 and absorbs oil phase impurities in the hydrogen chloride raw material, and pure hydrogen chloride gas is obtained at the tower top;

(3) the methyl silicone oil enters a liquid accumulation disc 6 after passing through a filler layer 2, part of the methyl silicone oil is powered by an upper circulating pump 7 outside the absorption tower 1, and the methyl silicone oil returns to the absorption tower 1 from the top of the tower after being cooled;

(4) part of the methyl silicone oil overflows from the liquid accumulation disc 6 to the tower kettle to become tower kettle material, and the tower kettle material is conveyed to a water washing system 12 from the outlet of the tower kettle, and meanwhile, part of the tower kettle material is subjected to bottom circulation through a bottom circulating pump 11;

(5) after a water washing agent is added into the tower kettle material, the tower kettle material is sequentially washed by a water washer 1202 and separated by a separator 1203, a water layer is taken as wastewater and discharged out of the water washing system 12, and an oil layer is conveyed to a low-level removing system 13;

(6) and the oil layer is separated from the oil phase impurities in a falling film evaporator of the low-boiling-point removing system 13 according to the difference of boiling points, and after separation, the methyl silicone oil returns to the absorption tower 1.

In the step (1), the hydrogen chloride raw material comprises hydrogen chloride, oil phase impurities and water, wherein the oil phase impurities comprise at least one of cyclic siloxane, linear siloxane, cyclic polysiloxane or linear polysiloxane.

In the step (1), the absorbent comprises accumulated liquid on the partial liquid accumulation disc 6 which is circularly cooled by the upper circulating pump 7 and methyl silicone oil recovered by the low-removing system 13, and the absorbent can also comprise supplemented fresh methyl silicone oil according to the operation requirement of the process.

The top of the absorption tower 1 is provided with a product outlet 101 and an absorbent inlet 102, the product outlet 101 is used for discharging the treated pure hydrogen chloride gas, and the absorbent enters the absorption tower 1 through the absorbent inlet 102.

The tower kettle of the absorption tower 1 is provided with a raw material inlet 103, a tower kettle material outlet 104 and a tower kettle material inlet 105, wherein the raw material inlet 103 is used for inputting a hydrogen chloride raw material, and the tower kettle material outlet 104 is used for outputting tower kettle materials which overflow from the effusion disc 6 to the tower kettle and contain methyl silicone oil and oil phase impurities.

And an absorbent outlet 106 is arranged in the middle of the absorption tower 1 and used for outputting the methyl silicone oil to the upper circulating pump 7 to promote the circulation of the absorbent in the absorption tower 1.

In the step (2), the packing layer 2 comprises at least one layer of structured packing layer and at least one layer of bulk packing layer, that is, the packing layer 2 is a mode of alternately matching the structured packing layer and the bulk packing layer, preferably, the packing layer 2 comprises, from bottom to top, a first structured packing layer 201, a first bulk packing layer 202, a second structured packing layer 203, a second bulk packing layer 204, so that the hydrogen chloride gas fed from the tower bottom enters the first bulk packing layer 202 after being rectified by the first structured packing layer 201 and absorbed and exchanged with the methyl silicone oil, the oil phase impurities are fully absorbed by fully contacting with the absorbent, but the viscosity of the methyl silicone oil is slightly higher, the flow in the bulk packing layer for a long time can cause the phenomenon of splitting or gathering, the mass transfer efficiency is reduced, and the flow condition of the hydrogen chloride gas and the methyl silicone oil is improved through the rectification action of the second structured packing layer 203. The invention adopts the staggered arrangement form of the regular packing layers and the bulk packing layers, exerts the advantages of different packing layers, overcomes the flow problem caused by higher viscosity of the absorbent and improves the mass transfer efficiency.

The filler of the bulk filler layer is selected from at least one of cascade ring filler, pall ring filler, intalox saddle filler or conjugated ring filler.

The structured packing layer is preferably a structured packing layer having inclined rectangular flow channels, and the inventors have unexpectedly found that the structured packing layer has the best rectification effect on hydrogen chloride gas and methyl silicone oil.

In the step (1), the hydrogen chloride raw material enters the absorption tower 1 from a raw material inlet 103 of the tower kettle and then enters the gas distribution pipe 3, the gas distribution pipe 3 is spirally laid at the tower kettle and is immersed below the liquid level of the tower kettle, the upper surface of the gas distribution pipe 3 is provided with a plurality of gas distribution holes, the diameters of the gas distribution holes are 2-3cm, the gas distribution pipe 3 improves the feeding condition of the hydrogen chloride raw material and simultaneously considers the problem of the residue of oil phase impurities contained in the gas distribution pipe 3, therefore, the diameters of the gas distribution holes are increased, the pressure drop is reduced, and the residue of the oil phase impurities is greatly reduced.

Preferably, the gas distribution pipe 3 may further include a plurality of branches, and the branches are disposed between the structured packing layer and the bulk packing layer.

The design scheme that the gas distribution pipe 3 is matched with the regular packing layer and the bulk packing layer is adopted, so that the method is particularly suitable for the technical characteristics that the methyl silicone oil is used as an absorbent, and meanwhile, the hydrogen chloride raw material contains oil phase impurities, and has great positive effects on improving the flowing condition of the methyl silicone oil, the feeding state of the hydrogen chloride raw material and the contact absorption condition of the methyl silicone oil and the hydrogen chloride gas, thereby improving the mass transfer efficiency.

Preferably, in the step (2), the hydrogen chloride gas is discharged from the product outlet 101 at the top of the tower after being subjected to liquid entrainment removal through the demister 4, and the demister 4 can remove the methyl silicone oil entrained in the hydrogen chloride gas and the oil phase impurities condensed from the upper part of the absorption tower 1 when the hydrogen chloride gas is cooled.

Preferably, the demister 4 is at a distance of 60-80cm from the product outlet 101.

Preferably, a distributor 5 is arranged below the demister 4, and the demister 4 can alleviate the phenomenon to a certain extent because the absorbent tends to flow in a strand and along the inner wall of the absorption tower 1 after flowing down from the top of the tower, however, the absorbent used in the invention is methyl silicone oil, which has a viscosity greater than that of water, so that the phenomenon of the absorbent collecting and flowing is more serious, which seriously affects the sufficient contact of the absorbent and the hydrogen chloride raw material, especially the uniform flow in the filler layer 2 and the contact with the raw material, and reduces the absorption effect.

The distributor 5 designed by the invention can uniformly redistribute the methyl silicone oil fluid entering from the top of the tower, namely, the methyl silicone oil fluid uniformly falls on the cross section of the absorption tower 1, and the absorbent is prevented from flowing on the inner wall of the absorption tower 1. The distributor 5 comprises a plurality of flow guide plates 501 and distribution discs 502, one end of each flow guide plate 501 is arranged on the inner wall of the absorption tower 1 and forms a certain angle with the inner wall of the absorption tower 1, the length and the angle of each flow guide plate 501 can be changed according to the tower entering temperature and the flow of methyl silicone oil, preferably, the length of each flow guide plate 501 is 10-90cm, and the angle formed by each flow guide plate 501 and the inner wall of the absorption tower 1 is 10-70 degrees.

The distribution plate 502 is arranged below the flow guide plate 501, the upper surface of the distribution plate 502 is provided with a plurality of concave continuous or discontinuous flow guide grooves 503, the bottoms of the flow guide grooves 503 are provided with a plurality of through holes 504, preferably, the flow guide grooves 503 and the through holes 504 are uniformly distributed on the distribution plate 502, so that methyl silicone oil falling or naturally flowing down along the flow guide plate 501 is guided to different positions of the distribution plate 502 through the flow guide grooves 503 on the distribution plate 502, and continuously falls down to the filler layer 2 from the through holes 504.

Preferably, a plurality of air holes 505 are formed in the distribution plate 502, and are used for allowing relatively pure hydrogen chloride gas to pass through the distribution plate 502, so as to reduce pressure drop in the absorption tower 1, the positions of the air holes 505 and the bottom end of the flow guide plate 501 are staggered, so that falling methyl silicone oil is prevented from falling into the air holes 505, the air holes 505 penetrate through the upper surface and the lower surface of the distribution plate 502, and the air holes 505 in the upper surface of the distribution plate 502 have air hole walls with the height of 1-3cm, so that the methyl silicone oil on the distribution plate 502 cannot flow down through the air holes 505.

In one embodiment of the invention, the lengths of the drainage plates 501 are 40cm, 60cm and 80cm respectively, the angles between the drainage plates 501 and the inner wall of the absorption tower 1 are the same and are 45 degrees, the drainage plates 501 with the same length are arranged in a circle at the same height of the inner wall of the absorption tower 1, 4-8 drainage plates with the same length are arranged in a circle, that is, the drainage plates with the lengths of 40cm, 60cm and 80cm are arranged in three circles from top to bottom on the inner wall of the absorption tower 1, and the height interval between every two circles is 5-20 cm.

In another embodiment of the present invention, the lengths of the drainage plates 501 are 40cm, 60cm and 80cm, the drainage plates with different lengths are arranged in a circle at the same height of the inner wall of the absorption tower 1, and 4 to 8 drainage plates with different lengths are arranged in a circle, that is, the drainage plates with different lengths can be matched with each other at the same height of the inner wall of the absorption tower 1, the angle of each drainage plate 501 can be different, so that the design of the drainage plates 501 can be that 1 to 5 circles are arranged on the inner wall of the absorption tower 1, and the height interval between every two circles is 5 to 20 cm. Those skilled in the art can also use other designs of the flow guide plate 501 with different lengths, angles and heights under the guidance of the above embodiments, and these designs are all within the scope of the present invention.

In the step (3), after the methyl silicone oil passes through the packing layer 2 and fully absorbs the oil phase impurities in the raw materials, the methyl silicone oil continuously flows downwards and enters the liquid accumulating disc 6, at this time, the methyl silicone oil is contacted with the hydrogen chloride raw material for heat exchange, the temperature of the methyl silicone oil rises, part of the methyl silicone oil on the liquid accumulating disc 6 is output to the absorption tower 1 from the absorbent outlet 106, and under the action of the upper circulating pump 7, the methyl silicone oil is cooled by the cooler 8 and then returns to the absorption tower 1 from the absorbent inlet 102 at the top of the tower; meanwhile, fresh methyl silicone oil or methyl silicone oil recovered from the lowering system is merged into a methyl silicone oil pipeline before the upper circulating pump 7, mixed with methyl silicone oil output from the absorbent outlet 106, powered by the upper circulating pump 7, and enters the cooler 8 for cooling.

In the step (4), the liquid accumulation disc 6 is provided with an overflow pipe, and part of the methyl silicone oil which absorbs the oil phase impurities flows down to the tower kettle from the overflow pipe to form tower kettle materials, wherein the tower kettle materials comprise the methyl silicone oil, the oil phase impurities and a small amount of hydrogen chloride.

Preferably, the tower kettle is provided with a liquid level sensor 9, the tower kettle material outlet 104 is provided with an outlet control valve 10, the liquid level sensor 9 controls the outlet control valve 10, the tower kettle discharge is controlled, and the tower kettle liquid level is ensured to be appropriate. The tower kettle material passes through a bottom circulating pump 11 outside the absorption tower 1, a part of the tower kettle material enters the water washing system 12, and the other part of the tower kettle material returns to the absorption tower 1 through a tower kettle material inlet 105 to maintain the liquid level of the tower kettle.

Preferably, a viscometer is arranged on a circulating pipeline where the bottom circulating pump 11 is located, the viscosity of the tower bottom material is monitored in real time, and when the viscosity is higher, the absorbent can be supplemented properly.

In step (5), washing system 12 includes charging means 1201, water scrubber 1202 and the separator 1203 that connects gradually through the pipeline, the tower bottom material is carried to water scrubber 1202 by the outside bottom circulating pump 11 of absorption tower 1, and charging means 1201 adds the washing agent to the water scrubber in, the washing agent is water, and tower bottom material and washing agent intensive mixing in water scrubber 1202, then decant the layering of standing in tower bottom material and washing agent entering separator 1203, the lower floor is the water layer, and the upper strata is the oil reservoir, the water layer includes washing agent and hydrogen chloride, the oil reservoir includes methyl silicone oil and oil phase impurity, and the water layer is water discharge washing system 12 as waste water, and the oil reservoir is carried to low system 13 of eluting and is further separated.

In the step (6), the low-boiling removal system 13 includes a preheater 1301, a first falling-film evaporator 1302, a first vacuum separator 1303, a second falling-film evaporator 1304 and a second vacuum separator 1305 which are connected in sequence, and after the tower bottoms are subjected to water phase separation in the water washing system 12, the separation of the methyl silicone oil and the oil phase impurities is performed. According to the invention, the difference of the boiling points of the two is utilized, the low-boiling-point removing system 13 and the method are selected, and a falling film evaporator is selected to treat the material aiming at the characteristic that the methyl silicone oil and the oil phase impurities have certain viscosity. In order to reduce the content of oil phase impurities in methyl silicone oil after separation, the invention uses a two-stage falling-film evaporator, after the material passes through the first falling-film evaporator 1302, most of the oil phase impurities are separated in a first vacuum separator 1303, purer methyl silicone oil enters a second falling-film evaporator 1304 to be continuously evaporated and separated, finally, trace oil phase impurities are removed in a second vacuum separator 1305, the obtained methyl silicone oil is used as an absorbent to return to the absorption tower 1 for reuse, and preferably, oil phase impurity steam and secondary steam obtained from the first vacuum separator 1303 and the second vacuum separator 1305 are used as heat sources to return to the preheater for reuse.

The process flow comprises the following steps:

(1) hydrogen chloride raw material with the temperature of minus 5 ℃ enters the absorption tower 1 from the tower bottom, the hydrogen chloride raw material contains 300ppm of oil phase impurities, and absorbent methyl silicone oil with the temperature of minus 20 ℃ enters the absorption tower 1 from the tower top;

(2) the methyl silicone oil meets the hydrogen chloride raw material at the packing layer 2 and absorbs oil phase impurities in the hydrogen chloride raw material, and pure hydrogen chloride gas is obtained at the tower top;

wherein the packing layer 2 comprises, from bottom to top, a first structured packing layer 201 (height of 2400mm), a first bulk packing layer 202 (height of 1800mm), a second structured packing layer 203 (height of 2400mm), a second bulk packing layer 204 (height of 1800 mm);

(3) methyl silicone oil enters a liquid accumulation disc 6 after passing through a filler layer 2, the methyl silicone oil is powered by an upper circulating pump 7 of the absorption tower 1, the flow rate is 8t/h, and the methyl silicone oil returns to the absorption tower 1 from the top of the tower after being cooled;

(4) the other part of the methyl silicone oil overflows from the effusion disc 6 to the tower kettle to become tower kettle material, and is conveyed to the water washing system 12 from the outlet of the tower kettle;

the liquid level of the tower kettle is maintained at 50% of the height of the tower kettle, part of tower kettle materials exceeding the liquid level range are conveyed to a washing system from an outlet of the tower kettle, and part of tower kettle materials enter the tower kettle through a bottom circulating pump 11 in a circulating reflux mode when the liquid level range is not reached;

(5) adding a water washing agent into the tower bottom material, wherein the mass ratio of the water washing agent to the tower bottom material entering the water washer is 1:2, the tower bottom material and the water washing agent are sequentially washed by the water washer 1202 and separated by the separator 1203, a water layer is discharged out of the water washing system as wastewater, and an oil layer is conveyed to the low-level removing system 13;

the stirring speed of the water scrubber is 120 revolutions per minute;

(6) separating the methyl silicone oil from the oil phase impurities in the oil layer in the step (5) in a low-boiling system 13 according to the difference of boiling points, and returning the methyl silicone oil to the absorption tower 1 after separation;

wherein the vacuum degree of the first vacuum separator 1303 is-0.09 MPa, and the vacuum degree of the second vacuum separator 1305 is-0.095 MPa; the preheating temperature of the preheater 1301 is 140 ℃, the evaporation temperature of the first falling-film evaporator 1302 is 180 ℃, the heating temperature of the first vacuum separator 1303 is 180 ℃, the evaporation temperature of the second falling-film evaporator 1304 is 200 ℃, and the heating temperature of the second vacuum separator 1305 is 210 ℃.

The content of oil phase impurities in the hydrogen chloride raw material is reduced from 300ppm to 60ppm after treatment.

Example 2

The structure of the apparatus of this example is the same as that of example 1.

The process flow comprises the following steps:

(1) hydrogen chloride raw material with the temperature of minus 10 ℃ enters the absorption tower 1 from the tower bottom, the hydrogen chloride raw material contains 500ppm of oil phase impurities, and absorbent methyl silicone oil with the temperature of minus 30 ℃ enters the absorption tower 1 from the tower top;

(2) the methyl silicone oil meets the hydrogen chloride raw material at the packing layer 2 and absorbs oil phase impurities in the hydrogen chloride raw material, and pure hydrogen chloride gas is obtained at the tower top;

wherein the packing layer 2 comprises, from bottom to top, a first structured packing layer 201 (height 1500mm), a first bulk packing layer 202 (height 4000mm), a second structured packing layer 203 (height 4000mm), a second bulk packing layer 204 (height 1000 mm);

(3) methyl silicone oil enters a liquid accumulation disc 6 after passing through a filler layer 2, the methyl silicone oil is powered by an upper circulating pump 7 of the absorption tower 1, the flow rate is 1t/h, and the methyl silicone oil returns to the absorption tower 1 from the top of the tower after being cooled;

(4) the other part of the methyl silicone oil overflows from the effusion disc 6 to the tower kettle to become tower kettle material, and is conveyed to the water washing system 12 from the outlet of the tower kettle;

the liquid level of the tower kettle is maintained at 40% of the height of the tower kettle, part of tower kettle materials exceeding the liquid level range are conveyed to a washing system from an outlet of the tower kettle, and part of tower kettle materials enter the tower kettle through a bottom circulating pump 11 in a circulating reflux mode when the liquid level range is not reached;

(5) adding a water washing agent into the tower bottom material, wherein the mass ratio of the water washing agent to the tower bottom material entering the water washer is 1:1, the tower bottom material and the water washing agent are sequentially washed by the water washer 1202 and separated by the separator 1203, a water layer is discharged out of the water washing system as wastewater, and an oil layer is conveyed to the low-level removing system 13;

the stirring speed of the water scrubber is 150 revolutions per minute;

(6) separating the methyl silicone oil from the oil phase impurities in the oil layer in the step (5) in a low-boiling system 13 according to the difference of boiling points, and returning the methyl silicone oil to the absorption tower 1 after separation;

wherein the vacuum degree of the first vacuum separator 1303 is-0.095 MPa, and the vacuum degree of the second vacuum separator 1305 is-0.1 MPa; the preheating temperature of the preheater 1301 is 150 ℃, the evaporation temperature of the first falling-film evaporator 1302 is 160 ℃, the heating temperature of the first vacuum separator 1303 is 190 ℃, the evaporation temperature of the second falling-film evaporator 1304 is 180 ℃, and the heating temperature of the second vacuum separator 1305 is 180 ℃.

The content of oil phase impurities in the hydrogen chloride raw material is reduced from 500ppm to 80ppm after treatment.

Example 3

The structure of the apparatus of this example is the same as that of example 1.

The process flow comprises the following steps:

(1) hydrogen chloride raw material with the temperature of 40 ℃ enters the absorption tower 1 from the tower bottom, the hydrogen chloride raw material contains 100ppm of oil phase impurities, and absorbent methyl silicone oil with the temperature of 0 ℃ enters the absorption tower 1 from the tower top;

(2) the methyl silicone oil meets the hydrogen chloride raw material at the packing layer 2 and absorbs oil phase impurities in the hydrogen chloride raw material, and pure hydrogen chloride gas is obtained at the tower top;

wherein the packing layer 2 comprises, from bottom to top, a first structured packing layer 201 (height 3000mm), a first bulk packing layer 202 (height 2500mm), a second structured packing layer 203 (height 2000mm), a second bulk packing layer 204 (height 3500 mm);

(3) methyl silicone oil enters a liquid accumulation disc 6 after passing through a filler layer 2, the methyl silicone oil is powered by an upper circulating pump 7 of the absorption tower 1, the flow rate is 10t/h, and the methyl silicone oil returns to the absorption tower 1 from the top of the tower after being cooled;

(4) the other part of the methyl silicone oil overflows from the effusion disc 6 to the tower kettle to become tower kettle material, and is conveyed to the water washing system 12 from the outlet of the tower kettle;

the liquid level of the tower kettle is maintained at 60% of the height of the tower kettle, partial tower kettle materials exceeding the liquid level range are conveyed to a washing system from an outlet of the tower kettle, and partial tower kettle materials enter the tower kettle through a bottom circulating pump 11 in a circulating reflux mode when the liquid level range is not reached;

(5) adding a water washing agent into the tower bottom material, wherein the mass ratio of the water washing agent to the tower bottom material entering the water washer is 1:8, the tower bottom material and the water washing agent are sequentially washed by the water washer 1202 and separated by the separator 1203, a water layer is discharged out of the water washing system as wastewater, and an oil layer is conveyed to the low-level removing system 13;

the stirring speed of the water scrubber is 60 revolutions per minute;

(6) separating the methyl silicone oil from the oil phase impurities in the oil layer in the step (5) in a low-boiling system 13 according to the difference of boiling points, and returning the methyl silicone oil to the absorption tower 1 after separation;

wherein the vacuum degree of the first vacuum separator 1303 is-0.095 MPa, and the vacuum degree of the second vacuum separator 1305 is-0.1 MPa; the preheating temperature of the preheater 1301 is 140 ℃, the evaporation temperature of the first falling-film evaporator 1302 is 170 ℃, the heating temperature of the first vacuum separator 1303 is 180 ℃, the evaporation temperature of the second falling-film evaporator 1304 is 190 ℃, and the heating temperature of the second vacuum separator 1305 is 200 ℃.

The content of oil phase impurities in the hydrogen chloride raw material is reduced from 100ppm to 50ppm after treatment.

Those skilled in the art will readily appreciate that the above-described preferred embodiments may be freely combined, superimposed, without conflict.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.