CN116078097A - Treatment process and device for acyloxysilane tail gas - Google Patents

Treatment process and device for acyloxysilane tail gas Download PDF

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Publication number
CN116078097A
CN116078097A CN202211682784.1A CN202211682784A CN116078097A CN 116078097 A CN116078097 A CN 116078097A CN 202211682784 A CN202211682784 A CN 202211682784A CN 116078097 A CN116078097 A CN 116078097A
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buffer tank
acetic acid
tail gas
tank
gas
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肖坤林
杨丞杰
李岩松
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HUBEI HUANYU CHEMICAL CO Ltd
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HUBEI HUANYU CHEMICAL CO Ltd
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
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    • B01D53/005—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
    • B01D3/10—Vacuum distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0033—Other features
    • B01D5/0036—Multiple-effect condensation; Fractional condensation
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
    • B01D5/006—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with evaporation or distillation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
    • B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
    • B01D5/009—Collecting, removing and/or treatment of the condensate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/002—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by condensation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1406—Multiple stage absorption
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1418—Recovery of products
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1493—Selection of liquid materials for use as absorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/18—Absorbing units; Liquid distributors therefor
    • B01D53/185—Liquid distributors
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/07—Purification ; Separation
    • C01B7/0706—Purification ; Separation of hydrogen chloride
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    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B7/00—Halogens; Halogen acids
    • C01B7/01—Chlorine; Hydrogen chloride
    • C01B7/07—Purification ; Separation
    • C01B7/0706—Purification ; Separation of hydrogen chloride
    • C01B7/0712—Purification ; Separation of hydrogen chloride by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C53/00—Saturated compounds having only one carboxyl group bound to an acyclic carbon atom or hydrogen
    • C07C53/08—Acetic acid
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07F—ACYCLIC, CARBOCYCLIC OR HETEROCYCLIC COMPOUNDS CONTAINING ELEMENTS OTHER THAN CARBON, HYDROGEN, HALOGEN, OXYGEN, NITROGEN, SULFUR, SELENIUM OR TELLURIUM
    • C07F7/00—Compounds containing elements of Groups 4 or 14 of the Periodic System
    • C07F7/02—Silicon compounds
    • C07F7/08—Compounds having one or more C—Si linkages
    • C07F7/20—Purification, separation

Abstract

The invention provides a process and a device for treating acyloxy silane tail gas. By the method provided by the invention, acetic acid and chlorosilane which are escaped from the fractionation refining stage in the production of acyloxy silane by an acetic acid method can be recovered, and the environmental protection and the economic performance of the whole set of device are improved. And the quality and the emission standard of hydrochloric acid recovered from the tail gas of hydrogen chloride are ensured. The device has the innovation points of simple structure, easy operation, no blockage of equipment pipelines, no gas leakage and the like.

Description

Treatment process and device for acyloxysilane tail gas
Technical Field
The field of organosilicon silane manufacture, in particular to a tail gas treatment process and a tail gas treatment device for acyloxy silane by an acetic acid method.
Technical Field
On an industrial scale, the production methods of acetoxysilane are classified into acetic acid method and acetic anhydride method. The material adopted for the acylation of chlorosilane is different, and the material belongs to the replacement of chlorine in chlorosilane by acyloxy groups. In either process, the byproduct chloride produced by the reaction is rapidly removed, so that the reaction is rapid and thorough, and the presence of chlorine causes the acyloxysilane to react toward the dimer (R n (R'COO) 3n SiOSi(R'COO) 3 R) conversion is unfavorable for quality improvement, and especially the byproduct hydrogen chloride of the acetic acid method has larger influence (EP 0845469). In this case, technological reforms such as bubbling nitrogen, increasing temperature, adding solvent (US 2566347) or catalyst, etc. are proposed, and devices such as film reaction (US 5387706), acetic acid zone heating (US 4332956) etc. are proposed on the equipment for upgrading.
The acetic anhydride method has higher acetic anhydride reaction activity (EP 0845469), and the byproduct acetyl chloride is taken as a multifunctional reaction medium and is a very good carrying agent, so that hydrogen chloride gas can be carried to be condensed and separated in a simple and efficient way; because of the lower boiling point, the material is used as a temperature control material, so that the thermal decomposition of acetoxysilane or chlorine-containing precursor thereof is effectively prevented; as a diluent, the hydrochloric acid concentration in the reaction mixture may also be kept at a low level. However, the disadvantage is that the economic efficiency of the byproduct acetyl chloride is mainly limited by the market price of the byproduct acetyl chloride.
And is also affected by acetyl chloride, wherein the content of acid chloride ions is high. For example, the mass fraction is 4.1×10 -6 230kg of methyltriacetoxysilane and 0.266kg of acetic acid solution of 8% sodium acetate, stirring at 90 ℃ for one hour, and filtering to remove NaCl to obtain a mass fraction less than 1.0X10 -7 Methyl triacetoxy silane of (a). This process involves the formation of considerable amounts of NaCl salts, which must be removed from the reaction mixture by cumbersome filtration and washing.
Acetic acid has lower reactivity in the acetic acid process. R is R n Si 4-n ＋（4-n）AcOH→R n Si(AOc) （4-n）3 +nHCl. To facilitate the yield of the target product, it is generally necessary to increase the reaction temperature and increase the reaction AcOH: r is R n Si 4-n Proportioning. This results in the formation of dimers. The byproduct HCl needs to be removed from the system in time. US4329484 suggests that acid chloride with acetic acid usage above 50% can be reduced to 1ppm; the mixture ratio of AcOH to chlorosilane is greatly improved, the reaction is promoted thoroughly, meanwhile, HCl is diluted, and side reactions are reduced. However, compared with the yield of chlorosilane of not less than 97% by the acetic anhydride method, the yield of chlorosilane is difficult to reach more than 90% by the acetic anhydride method even if the reaction ratio and the reaction temperature are greatly improved. The resulting mixture of acetic acid/acetoxysilane/hydrogen chloride/methyltrichlorosilane must be separated by distillation under reduced pressure. Such separation devices are extremely expensive and, due to the high freezing point of acetic acid, require a complex condensing system, often prone to failure.
The byproduct of the acetic acid method is hydrochloric acid solution or is prepared into hydrochloride, but because the reaction yield is lower, the hydrogen chloride tail gas carries a large amount of chlorosilane and even acetic acid to enter a tail gas treatment system, so that the system is blocked, acid gas overflows, and the production environment is bad.
CN110252091B is a step absorption process for treating chloromethyl silane tail gas, which is mainly a venturi scrubber using water as a medium, and meanwhile, potassium hydroxide neutralizes and hydrolyzes hydrogen chloride gas, so that chlorosilane is not well utilized, and meanwhile, the generated methyl potassium silicate is not well digested; and a reaction rectifying device for treating the tail gas containing chlorosilane by a CN206783568U alcoholysis method. The silicate is prepared by alcoholysis by utilizing the tail gas of polysilicon, but the tail gas generated in the production of silicate is not utilized enough, the device is expensive and the energy consumption is high.
Disclosure of Invention
The invention provides a process and a device for treating acyloxy silane tail gas. By the method provided by the invention, acetic acid and chlorosilane which are escaped from the fractionation refining stage in the production of acyloxy silane by an acetic acid method can be recovered, and the environmental protection and the economic performance of the whole set of device are improved. And the quality and the emission standard of hydrochloric acid recovered from the tail gas of hydrogen chloride are ensured. The device has the innovation points of simple structure, easy operation, no blockage of equipment pipelines, no gas leakage and the like.
An acyloxy silane tail gas treatment device, wherein a tail gas pipe is connected with a decompression distillation tank;
the decompression distillation tank is connected with the graphite heat exchanger; a nitrogen inlet pipe is arranged on the graphite heat exchanger;
the graphite heat exchanger is connected with an acetic acid injection vacuum system through a Venturi injection pump I;
the acetic acid injection vacuum system is connected with the first-stage buffer tank through a second Venturi injection pump;
the first-stage buffer tank is connected with the second-stage buffer tank through a Venturi jet pump III;
the second-stage buffer tank is connected with the third-stage buffer tank through a Venturi jet pump IV;
the third-stage buffer tank is connected with the fourth-stage buffer tank; the fourth-stage buffer tank is connected to the hydrochloric acid absorption storage tank.
And a first cold water heat exchanger is arranged on the graphite heat exchanger.
The acetic acid injection vacuum system is connected with the Venturi injection pump I through the acetic acid circulating pump I to form a circulating loop;
the acetic acid injection vacuum system is connected with a cold water heat exchanger II through an acetic acid circulating pump II, and the cold water heat exchanger II is connected with the acetic acid injection vacuum system to form a circulating loop.
The first-stage buffer tank is connected with the third cold water heat exchanger through the third acetic acid circulating pump and then is connected with the first-stage buffer tank to form a circulating loop; and the cold water heat exchanger III is respectively connected with the tail liquid collecting pipe and the Venturi jet pump II through pipelines.
The second-stage buffer tank is connected with the cold water heat exchanger IV through the acetic acid circulating pump IV and then is connected with the second-stage buffer tank to form a circulating loop; and the cold water heat exchanger four is respectively connected with the tail liquid collecting pipe and the Venturi jet pump three through pipelines.
The third-stage buffer tank is connected with the cold water heat exchanger five through the acetic acid circulating pump five and then is connected with the third-stage buffer tank to form a circulating loop; the cold water heat exchanger five is respectively connected with the tail liquid collecting pipe and the Venturi jet pump four;
the fourth-stage buffer tank is connected with a tail liquid collecting pipe through a sixth acetic acid circulating pump.
The method for treating the acyloxy silane tail gas adopts the device and comprises the following steps:
(1) The acyloxysilane tail gas enters a decompression distillation tank, the separated tail gas enters a venturi jet pump I after heat exchange, enters an acetic acid jet vacuum system after being cooled by the venturi jet pump I, and takes acetic acid as jet fluid to cool and then brings non-condensable gas into a first-stage buffer tank by a venturi jet pump II;
(2) Collecting and settling condensate in the first-stage buffer tank, collecting the condensate at the bottom, and introducing non-condensable gas into the second-stage buffer tank through the third Venturi jet pump;
(3) Collecting and settling condensate at the bottom of the secondary buffer tank, and introducing non-condensable gas into the tertiary buffer tank through a Venturi jet pump IV;
(4) Collecting and settling condensate in the third-stage buffer tank, collecting the condensate at the bottom, and taking non-condensable gas into the fourth-stage buffer tank through a pipeline;
(5) And collecting and settling condensate at the bottom of the four-stage buffer tank, and enabling tail gas to enter a hydrochloric acid absorption system.
The acetic acid vacuum spraying system of the invention is used for mass transfer and heat transfer. Mass transfer refers to bringing the non-condensable gas into the next section and heat transfer refers to cooling.
The tail gas of the acyloxysilane in the step (1) comprises a mixture formed by acetic acid, acetoxysilane, hydrogen chloride and methyltrichlorosilane;
the flow rate of the tail gas of the acyloxy silane is 100-1000Nm 3 /h; the temperature in the reduced pressure distillation tank is 75-125 ℃, and the vacuum degree is-0.095 MPa to-0.01 MPa; the temperature of the outer circulation of the Venturi jet pump is controlled to be 0-20 ℃.
The venturi jet pump is a vacuum device, and glacial acetic acid is adopted as jet fluid. Avoiding the massive generation of methyl silicic acid which is usually caused by the hydrolysis of chlorosilane by taking water as a medium and the blockage of a pipeline.
The cooled glacial acetic acid is used as a vacuum fluid and a refrigerant of tail gas, and is rapidly mixed with the tail gas in a venturi throat and is efficiently cooled.
The fluid of the jet pump device is totally closed in a moisture-proof way, and the temperature of acetic acid is controlled to be 0-20 ℃ by adopting external circulation cooling.
The mixture of acetic acid/acetoxy silane/hydrogen chloride/methyltrichlorosilane generated in the production process of acyloxy silane is decompressed, distilled and separated, and a vacuum device is cooled by a buffer tank to primarily condense and remove part of acetic acid, and non-condensable gas enters a Venturi jet pump. The venturi jet pump is isolated from the atmosphere and is totally closed, and the outlet of the venturi jet pump is connected with the buffer tank.
The relative pressure in the first-stage buffer tank in the step (2) is 100-300pa, and the constant temperature of the glacial acetic acid in the tank is 0-20 ℃;
the relative pressure in the second-level buffer tank in the step (3) is 300-500pa, and the constant temperature of the glacial acetic acid in the memory is 0-20 ℃;
the relative pressure in the three-stage buffer tank in the step (4) is 500-800pa, and the constant temperature of the glacial acetic acid in the tank is 0-20 ℃;
the relative pressure in the four-stage buffer tank in the step (5) is 800-1000pa.
Above 20 ℃, efficiency decreases and can result in bulky devices.
The non-condensable gas enters a first-stage buffer tank, a second-stage buffer tank, a third-stage buffer tank and a fourth-stage buffer tank, and the total volume fraction is controlled to be 30-70%.
The condensed liquid in the steps (2), (3), (4) and (5) is acetic acid and chlorosilane, and the acetic acid and the chlorosilane are transferred into a tail liquid collecting tank.
In the technical scheme of the invention, tail gas from the mixture of acetic acid/acetoxysilane/hydrogen chloride/methyltrichlorosilane of acyloxysilane, which is separated by reduced pressure distillation, is conveyed into a primary buffer tank by negative pressure after passing through a Venturi jet pump unit, and is primarily condensed in the primary buffer tank to obtain most of acetic acid and chlorosilane. Acetic acid and chlorosilane after constant temperature condensation can be transferred into a tail liquid collecting tank to be used as production raw materials of the next batch.
The non-condensable tail gases from the primary buffer tank are very little acetic acid and chlorosilane, and most of the non-condensable tail gases are hydrogen chloride gas. The acetic acid and chlorosilane are mostly liquefied by heat exchange with the environment, and the liquefied mixture is incorporated into a primary buffer tank mixture for production for later use. The residual air is brought into the three-stage buffer tank by negative pressure.
And collecting the liquid drops collected by sedimentation through three-four-stage buffering and condensation, and merging the liquid drops into a secondary condensate storage tank, and merging the cooling liquid of each stage of buffer tank into a tail liquid collecting tank for standby. The purified hydrogen chloride tail gas enters a hydrochloric acid absorption system.
The technical scheme of the invention has the following beneficial effects:
unlike traditional venturi pump with water as jet, the jet of the present invention is glacial acetic acid. Mainly because of the characteristics of glacial acetic acid that saturated vapor pressure is lower than water and specific gravity is higher than water. This is one of the major innovations of the present invention. Avoiding the use of expensive and complex vacuum pumps; in particular to solve the problems of blockage and acid gas leakage caused by chlorosilane hydrolysis due to water as a fluid and difficult treatment.
Unlike acetic acid which normally has a freezing point of 16.6 ℃ in the standard state (293 k, latm), the present invention is surprising in that the freezing point of acetic acid can be lowered below 0 ℃ because the presence of hydrogen chloride and chlorosilane breaks the intermolecular hydrogen bonding of pure acetic acid, i.e. glacial acetic acid. The hydrogen bond of glacial acetic acid is destroyed by hydrogen chloride gas, and the operation is performed below the freezing point of glacial acetic acid, which breaks through the industry consensus. Acetic acid is a second major innovation of the present invention as a refrigerant.
With respect to venturi jet pumps using acetic acid as a jet body, the jet pump is generally only mass transfer, that is, the negative pressure generated by the high-speed liquid flow is used as power to drive the gas to flow to a low-pressure area. The method adopts cooled acetic acid superfluid, and simultaneously carries out mass transfer and high-efficiency gas-liquid mixing at a venturi throat to cool non-condensable gas. The invention is to cool the non-condensable gas step by step, promote the liquefaction of the non-condensable gas, and reduce the content of the condensable substances in the gas entering the next stage at the temperature.
The venturi device is adopted to directly mix gas and liquid, so that the heat transfer and mass transfer efficiency is high, and the venturi device is a great innovation of the invention.
Solves the production bottleneck of acetic acid method, recovers raw materials to the maximum extent, reduces the production cost, and has no other byproducts. Meanwhile, the quality of the hydrochloric acid is improved, and the application field of the hydrochloric acid is expanded.
By controlling the micro negative pressure operation of each buffer tank, the static balance of liquid drop cooling condensation and sedimentation microcirculation is realized. Disorder caused by high-speed air flow is avoided.
The whole set of device has simple structure, economy and reliable operation. The whole system runs under micro negative pressure, and is safe and free of leakage.
Drawings
Fig. 1 shows a device for treating acyloxysilane tail gas, a tail gas pipe 1, a nitrogen inlet pipe 2, a graphite heat exchanger T1, a decompression distillation tank R1, a venturi jet pump M1, a tail liquid collecting pipe V1, an acetic acid jet vacuum system V2, a primary buffer tank V3, a secondary buffer tank V4, a tertiary buffer tank V5, a quaternary buffer tank V6, a first acetic acid circulating pump P1, a second acetic acid circulating pump P2, a third acetic acid circulating pump P3, a fourth acetic acid circulating pump P4, a fifth acetic acid circulating pump P5, a sixth acetic acid circulating pump P6, a first cold water heat exchanger E1, a second cold water heat exchanger E2, a third cold water heat exchanger E3, a fourth cold water heat exchanger E4 and a fifth cold water heat exchanger E5.
Detailed Description
The technical and equipment features to which the present invention relates are further described below with reference to the accompanying drawings.
Example 1
An acyloxysilane tail gas treatment device, wherein a tail gas pipe 1 is connected with a decompression distillation tank R1;
the decompression distillation tank R1 is connected with a graphite heat exchanger T1; a nitrogen inlet pipe 2 is arranged on the graphite heat exchanger;
the graphite heat exchanger T1 is connected with the acetic acid injection vacuum system V2 through a Venturi injection pump M1;
the acetic acid injection vacuum system V2 is connected with the first-stage buffer tank V3 through a venturi injection pump II M2;
the first-stage buffer tank V3 is connected with the second-stage buffer tank V4 through a Venturi jet pump III M3;
the second-stage buffer tank V4 is connected with the third-stage buffer tank V5 through a Venturi jet pump four M4;
the third-stage buffer tank V5 is connected with the fourth-stage buffer tank V6; the fourth-stage buffer tank V6 is connected to a hydrochloric acid absorption tank.
And a first cold water heat exchanger is arranged on the graphite heat exchanger.
The acetic acid injection vacuum system V2 is connected with the Venturi injection pump M1 through the acetic acid circulating pump P1 to form a circulating loop;
the acetic acid injection vacuum system V2 is connected with the cold water heat exchanger II E2 through the acetic acid circulating pump II P2, and the cold water heat exchanger II E2 is connected with the acetic acid injection vacuum system V2 to form a circulating loop.
The first-stage buffer tank V3 is connected with the cold water heat exchanger three E3 through the acetic acid circulating pump three P3 and then is connected with the first-stage buffer tank V3 to form a circulating loop; and the cold water heat exchanger III E3 is respectively connected with the tail liquid collecting pipe V1 and the venturi jet pump II M2 through pipelines.
The second-stage buffer tank V4 is connected with the cold water heat exchanger four E4 through the acetic acid circulating pump four P4 and then is connected with the second-stage buffer tank V4 to form a circulating loop; and the cold water heat exchanger four E4 is respectively connected with the tail liquid collecting pipe V1 and the venturi jet pump three M3 through pipelines.
The three-stage buffer tank V5 is connected with the cold water heat exchanger five E5 through the acetic acid circulating pump five P5 and then is connected with the three-stage buffer tank V5 to form a circulating loop; the cold water heat exchanger five E5 is respectively connected with the tail liquid collecting pipe V1 and the venturi jet pump four M4;
the fourth-stage buffer tank V6 is connected with the tail liquid collecting pipe V1 through an acetic acid circulating pump six P6.
The first-stage buffer tank V3, the second-stage buffer tank V4 are made of glass fiber reinforced plastic or polypropylene, the third-stage buffer tank V5 and the fourth-stage buffer tank V6 are made of steel lining glass fiber reinforced plastic or tetrafluoro. The tanks are connected in a flange structure. The first 3 stages of buffer tanks are all provided with acetic acid for internal circulation cooling, and the temperature is controlled to be 0 to 20 ℃.
Example 2
The methyltriacetoxysilane production at a certain plant is batch. Dry nitrogen replaces the reactor and all the pipelines, condensers and other accessory equipment. According to 1600kg of glacial acetic acid (AcOH), monomethyl trichlorosilane (MeSi) is added dropwise 3 ) 400kg, at 70℃for 1 hour. The vacuum reduced pressure distillation time is 3 hours, and the temperature is 70-115 ℃. 500kg of methyl triacetoxy silane finished product is obtained, and 1150kg of acetic acid is recovered by condensation. Acetic acid yield 91%, and monomethyl trichlorosilane 85%. The three sets of equipment are operated simultaneously, and the production amount is 9 tons of methyltriacetoxy silane in the whole day. The tail gas is sucked into a hydrolysis tank through a Venturi jet pump, the scum is manually fished out after the chlorosilane is hydrolyzed, the tail gas is subjected to solid waste treatment after standing and dehydration, and hydrochloric acid and acetic acid are neutralized by limestone untilAfter the pH is neutral, the COD content is 6000PPM, the salt content is 5 percent, and the mixture is discharged after dilution.
The scheme of the patent is adopted for the following transformation.
400kg of monomethyl trichlorosilane is added dropwise according to 1600kg of glacial acetic acid (AcOH), and reflux reaction is carried out for 1 hour at 65-75 ℃. Vacuum distillation is carried out for 3 hours at 75-115 ℃. 440kg of methyl triacetoxy silane finished product is obtained, and 1200kg of acetic acid is recovered by preliminary condensation. The flow rate of the tail gas is 100 to 1000Nm 3 /h。
The tail gas is a mixture of acetic acid/acetoxy silane/hydrogen chloride/methyl trichlorosilane, and the mixture enters a reduced pressure distillation tank. The total amount of the acetic acid is that the gas escape speed is controlled by adjusting the sizes of an oil inlet valve and a vacuum gas outlet valve of the distillation pot. The temperature of the distillation pot is 75-125 ℃, and the vacuum degree is controlled to be-0.095 Mp to-0.01 Mp.
The condensate of the distillation tank enters a tail liquid collecting tank, primary tail gas enters a primary buffer tank through a venturi jet pump, and the primary tail gas mainly comprises the following components in volume: 50% of hydrogen chloride, 17% of monomethyl trichlorosilane, 16% of acetic acid steam and 17% of nitrogen.
The primary tail gas is cooled by a Venturi jet pump and is brought into a primary buffer tank, the relative pressure of the primary buffer tank is 100-300Pa, the constant temperature of glacial acetic acid stored in the primary buffer tank is 0-20 ℃, the primary buffer tank stays and gathers and settles for 15min, condensate gathers at the bottom, and non-condensable gas enters a secondary buffer tank. The non-condensable gas is secondary tail gas, and the main volume components of the secondary tail gas are as follows: 61% of hydrogen chloride, 4% of monomethyl trichlorosilane, 2% of acetic acid steam and 33% of nitrogen.
Cooling the secondary tail gas by a Venturi jet pump and taking the cooled secondary tail gas into a secondary buffer tank, wherein the relative pressure of the secondary buffer tank is 300-500pa, and the constant temperature of the glacial acetic acid stored in the secondary buffer tank is 0-20 ℃; and staying and converging and settling for 15min, converging condensate at the bottom, and feeding non-condensable gas into a three-stage buffer tank. The non-condensable gas is three-stage tail gas, and the main volume components of the three-stage tail gas are as follows: 73% of hydrogen chloride, 3% of monomethyl trichlorosilane, 1% of acetic acid steam and 21% of nitrogen.
The tertiary tail gas is cooled by a Venturi jet pump and is brought into a tertiary buffer tank, the relative pressure of the tertiary buffer tank is 500-800pa, and the constant temperature of glacial acetic acid stored in the tertiary buffer tank is 0-20 ℃; and staying and collecting and settling for 15min, collecting condensate at the bottom, and introducing non-condensable gas into a four-stage buffer tank. The non-condensable gas is three-stage tail gas, and the main volume components of the three-stage tail gas are as follows: 75% of hydrogen chloride, 0.7% of monomethyl trichlorosilane, 0.3% of acetic acid steam and 24% of nitrogen.
The tail gas of the fourth stage is cooled by a Venturi jet pump and is brought into a buffer tank of the fourth stage, and the relative pressure of the fourth stage is 800-1000pa; and staying and collecting and settling for 15min, collecting condensate at the bottom, and introducing non-condensable gas into a four-stage buffer tank. The non-condensable gas is four-stage tail gas, and the main volume components of the three-stage tail gas are as follows: 75% of hydrogen chloride, 0.1% of monomethyl trichlorosilane, 0.1% of acetic acid steam and 23.8% of nitrogen. And the fourth-stage tail gas enters a hydrochloric acid absorption system.
Through the above cyclic operation, the statistical result shows that the yield of the monomethyl trichlorosilane reaches 98 percent, and the recovery rate of the acetic acid reaches 99.5 percent.
Example 3
The methyltriacetoxysilane production at a certain plant is batch. Dry nitrogen replaces the reactor and all the pipelines, condensers and other accessory equipment. According to 1600kg of glacial acetic acid (AcOH), monoethyl trichlorosilane (MeSi) was added dropwise 3 ) 435kg, at 70℃for 1 hour. Vacuum distillation is carried out for 3 hours at 70-120 ℃. 530kg of ethyl triacetoxy silane finished product is obtained, and 1150kg of acetic acid is recovered by condensation. Acetic acid yield 92%, methyl trichlorosilane 88%. The tail gas is sucked into a hydrolysis tank through a Venturi jet pump, the scum is manually fished out after the chlorosilane is hydrolyzed, the scum is subjected to standing and dehydration and is treated as solid waste, hydrochloric acid and acetic acid are neutralized by limestone until ph is neutral, the Cod content is 6000PPM, the salt content is 5%, and the scum is discharged after dilution.
The scheme of the patent is adopted for the following transformation.
According to 1600kg of glacial acetic acid (AcOH), 435kg of monoethyl trichlorosilane is added dropwise and the mixture is reacted at 70 ℃ under reflux for 1 hour. Vacuum distillation is carried out for 3 hours at 70-120 ℃. The flow rate of the tail gas is 100 to 1000Nm 3 /h。
The tail gas is a mixture of acetic acid/acetoxy silane/hydrogen chloride/ethyl trichlorosilane, and the mixture enters a reduced pressure distillation tank.
The total amount of the acetic acid is that the gas escape speed is controlled by adjusting the sizes of an oil inlet valve and a vacuum gas outlet valve of the distillation pot. The temperature of the distillation pot is 75-120 ℃. The vacuum was controlled to-0.095 Mp to-0.01 Mp.
The condensate of the distillation tank enters a tail liquid collecting tank, primary tail gas enters a primary buffer tank through a venturi jet pump, and the primary tail gas mainly comprises the following components in volume: 51% of hydrogen chloride, 15% of monoethyl trichlorosilane, 17% of acetic acid steam and 17% of nitrogen. It is desirable to include the volume of gas that enters the buffer tank.
The primary tail gas is cooled by a Venturi jet pump and is brought into a primary buffer tank, the relative pressure of the primary buffer tank is 100-300Pa, the constant temperature of glacial acetic acid stored in the primary buffer tank is 0-20 ℃, the primary buffer tank stays and gathers and settles for 15min, condensate gathers at the bottom, and non-condensable gas enters a secondary buffer tank. The non-condensable gas is secondary tail gas, and the main volume components of the secondary tail gas are as follows: 63% of hydrogen chloride, 3% of monoethyl trichlorosilane, 2% of acetic acid steam and 34% of nitrogen.
Cooling the secondary tail gas by a Venturi jet pump and taking the cooled secondary tail gas into a secondary buffer tank, wherein the relative pressure of the secondary buffer tank is 300-500pa, and the constant temperature of the glacial acetic acid stored in the secondary buffer tank is 0-20 ℃; and staying and converging and settling for 15min, converging condensate at the bottom, and feeding non-condensable gas into a three-stage buffer tank. The non-condensable gas is three-stage tail gas, and the main volume components of the three-stage tail gas are as follows: 74% of hydrogen chloride, 1% of monoethyl trichlorosilane, 1% of acetic acid steam and 24% of nitrogen.
The tertiary tail gas is cooled by a Venturi jet pump and is brought into a tertiary buffer tank, the relative pressure of the tertiary buffer tank is 500-800pa, and the constant temperature of glacial acetic acid stored in the tertiary buffer tank is 0-20 ℃; and staying and collecting and settling for 15min, collecting condensate at the bottom, and introducing non-condensable gas into a four-stage buffer tank. The non-condensable gas is three-stage tail gas, and the main volume components of the three-stage tail gas are as follows: 75% of hydrogen chloride, 0.5% of monoethyl trichlorosilane, 0.5% of acetic acid steam and 24% of nitrogen.
The tail gas of the fourth stage is cooled by a Venturi jet pump and is brought into a buffer tank of the fourth stage, and the relative pressure of the fourth stage is 800-1000pa; and staying and collecting and settling for 15min, collecting condensate at the bottom, and introducing non-condensable gas into a four-stage buffer tank. The non-condensable gas is four-stage tail gas, and the main volume components of the three-stage tail gas are as follows: 75% of hydrogen chloride, 0.1% of monoethyl trichlorosilane, 0.1% of acetic acid steam and 24.8% of nitrogen. And the fourth-stage tail gas enters a hydrochloric acid absorption system.
Through the above cyclic operation, the statistical result shows that the yield of the monoethyl trichlorosilane reaches 99 percent, and the recovery rate of the acetic acid reaches 99.5 percent.

Claims (10)

1. The device for treating the acyloxysilane tail gas is characterized in that a tail gas pipe (1) is connected with a decompression distillation tank (R1);
the decompression distillation tank (R1) is connected with a graphite heat exchanger (T1);
the graphite heat exchanger (T1) is connected with the acetic acid injection vacuum system (V2) through the Venturi injection pump I (M1);
the acetic acid injection vacuum system (V2) is connected with the first-stage buffer tank (V3) through the Venturi injection pump II (M2);
the first-stage buffer tank (V3) is connected with the second-stage buffer tank (V4) through a Venturi jet pump III (M3);
the second-stage buffer tank (V4) is connected with the third-stage buffer tank (V5) through a Venturi jet pump IV (M4);
the third-level buffer tank (V5) is connected with the fourth-level buffer tank (V6); the fourth-stage buffer tank (V6) is connected to the hydrochloric acid absorption tank.
2. The device for treating an acyloxysilane tail gas according to claim 1, wherein the acetic acid injection vacuum system (V2) is connected with the venturi injection pump (M1) through the acetic acid circulation pump (P1) to form a circulation loop;
the acetic acid injection vacuum system (V2) is connected with the cold water heat exchanger II (E2) through the acetic acid circulating pump II (P2), and the cold water heat exchanger II (E2) is connected with the acetic acid injection vacuum system (V2) to form a circulating loop.
3. The device for treating the tail gas of the acyloxysilane according to claim 1, wherein the primary buffer tank (V3) is connected with the cold water heat exchanger III (E3) through the acetic acid circulating pump III (P3) and then is connected with the primary buffer tank (V3) to form a circulating loop; and the cold water heat exchanger III (E3) is respectively connected with the tail liquid collecting pipe V1 and the Venturi jet pump II (M2) through pipelines.
4. The device for treating the tail gas of the acyloxysilane according to claim 1, wherein the secondary buffer tank (V4) is connected with the cold water heat exchanger four (E4) through the acetic acid circulating pump four (P4) and then is connected with the secondary buffer tank (V4) to form a circulating loop; and the cold water heat exchanger IV (E4) is respectively connected with the tail liquid collecting pipe V1 and the Venturi jet pump III (M3) through pipelines.
5. The device for treating the tail gas of the acyloxysilane according to claim 1, wherein the tertiary buffer tank (V5) is connected with the cold water heat exchanger five (E5) through the acetic acid circulating pump five (P5) and then is connected with the tertiary buffer tank (V5) to form a circulating loop; the cold water heat exchanger five (E5) is respectively connected with the tail liquid collecting pipe (V1) and the Venturi jet pump four (M4);
the fourth-stage buffer tank (V6) is connected with a tail liquid collecting pipe (V1) through an acetic acid circulating pump six (P6).
6. A method for treating acyloxysilane off-gas using the apparatus of any one of claims 1 to 5, comprising the steps of:
(1) The acyloxysilane tail gas enters a decompression distillation tank, the separated tail gas enters a venturi jet pump I after heat exchange, enters an acetic acid jet vacuum system after being cooled by the venturi jet pump I, and takes acetic acid as jet fluid to cool and then brings non-condensable gas into a first-stage buffer tank by a venturi jet pump II;
(2) Collecting and settling condensate in the first-stage buffer tank, collecting the condensate at the bottom, and introducing non-condensable gas into the second-stage buffer tank through the third Venturi jet pump;
(3) Collecting and settling condensate at the bottom of the secondary buffer tank, and introducing non-condensable gas into the tertiary buffer tank through a Venturi jet pump IV;
(4) Collecting and settling condensate in the third-stage buffer tank, collecting the condensate at the bottom, and taking non-condensable gas into the fourth-stage buffer tank through a pipeline;
(5) And collecting and settling condensate at the bottom of the four-stage buffer tank, and enabling tail gas to enter a hydrochloric acid absorption system.
7. The method for treating an acyloxysilane off-gas according to claim 6, wherein the acyloxysilane off-gas in step (1) comprises a mixture of acetic acid, acetoxysilane, hydrogen chloride, methyltrichlorosilane;
the flow rate of the tail gas of the acyloxy silane is 100-1000Nm 3 /h; the temperature in the reduced pressure distillation tank is 75-125 ℃, and the vacuum degree is-0.095 MPa to-0.01 MPa; the temperature of the outer circulation of the Venturi jet pump is controlled to be 0-20 ℃.
8. The method for treating an acyloxysilane off-gas according to claim 6, wherein,
the relative pressure in the first-stage buffer tank in the step (2) is 100-300pa, and the constant temperature of the glacial acetic acid in the tank is 0-20 ℃;
the relative pressure in the second-level buffer tank in the step (3) is 300-500pa, and the constant temperature of the glacial acetic acid in the memory is 0-20 ℃;
the relative pressure in the three-stage buffer tank in the step (4) is 500-800pa, and the constant temperature of the glacial acetic acid in the tank is 0-20 ℃;
the relative pressure in the four-stage buffer tank in the step (5) is 800-1000pa.
9. The method for treating an acyloxysilane off-gas according to claim 6, wherein the total volume fraction is controlled to be 30-70% when the noncondensable gas enters the primary buffer tank, the secondary buffer tank, the tertiary buffer tank and the quaternary buffer tank.
10. The method for treating tail gas of acyloxysilane according to claim 6, wherein the condensed liquid in the steps (2), (3), (4) and (5) is acetic acid and chlorosilane, and the condensed liquid is transferred into a tail liquid collecting tank.
CN202211682784.1A 2022-12-27 2022-12-27 Treatment process and device for acyloxysilane tail gas Pending CN116078097A (en)

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