CN110252116B - Recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption - Google Patents

Recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption Download PDF

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CN110252116B
CN110252116B CN201910549911.2A CN201910549911A CN110252116B CN 110252116 B CN110252116 B CN 110252116B CN 201910549911 A CN201910549911 A CN 201910549911A CN 110252116 B CN110252116 B CN 110252116B
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styrene
washing
waste gas
adsorption
recovery process
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CN110252116A (en
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郭岩锋
孟宪谭
董凌云
菅秀君
王文彬
马瑞杰
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China Petroleum and Chemical Corp
Qilu Petrochemical Co of Sinopec
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Qilu Petrochemical Co of Sinopec
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    • 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
    • B01D53/02—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 adsorption, e.g. preparative gas chromatography
    • B01D53/04—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 adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • 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
    • B01D53/1425—Regeneration of liquid 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
    • B01D53/1487—Removing organic compounds
    • 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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/38—Removing components of undefined structure
    • B01D53/44—Organic components
    • 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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/72—Organic compounds not provided for in groups B01D53/48 - B01D53/70, e.g. hydrocarbons
    • 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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
    • B01D53/77—Liquid phase processes
    • B01D53/78—Liquid phase processes with gas-liquid contact
    • 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
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/96—Regeneration, reactivation or recycling of reactants

Abstract

The invention belongs to the technical field of industrial waste gas recovery, and particularly relates to a recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption. The recovery process for treating the styrene waste gas based on flash evaporation, washing and adsorption comprises mixing, flash evaporation, washing and adsorption, can treat the styrene waste gas generated in various places such as the tail gas of a styrene-butadiene device, wharf shipping, storage tank breathing and the like, recovers 85-95% of styrene in the waste gas through mixing and flash evaporation, recovers 4-15% of styrene in the waste gas through washing, then adsorbs an absorbent and the rest of styrene through adsorption, and controls the content of organic matters in the tail gas below a discharge standard so as to meet normal discharge. The recovery process can recycle the styrene in the waste gas to the maximum extent, changes waste into valuable, avoids the polymerization of the styrene in the adsorption process, and effectively ensures the stable operation of the device.

Description

Recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption
Technical Field
The invention belongs to the technical field of industrial waste gas recovery, and particularly relates to a recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption.
Background
Styrene, also known as vinyl benzene and styrene, is colorless to yellow transparent oily liquid, belongs to a secondary flammable liquid, and has the danger of combustion and explosion when steam meets high temperature or an oxidant. The most important use of styrene is as raw material of synthetic rubber and plastics, and the homopolymer of styrene, polystyrene, is one of five general thermoplastic synthetic resins, and is widely applied to the fields of injection molding, extrusion, foam products and the like; styrene can also generate copolymerization reaction with other monomers, and is used for manufacturing engineering plastics with multiple purposes, for example, a copolymer of styrene and butadiene is called styrene-butadiene rubber, the physical property, the processing property and the product use performance of the styrene-butadiene rubber are close to those of natural rubber, the styrene-butadiene rubber is the largest general synthetic rubber variety and is widely used in the fields of production of tires, adhesive tapes, rubber tubes, electric wires and cables, medical appliances, various rubber products and the like; in addition, styrene is also a raw material drug of the medicines of the pharmaceutical industry, such as the cough-suppressing and gastrodine, and has wide application in the field of medicines.
However, styrene is a typical malodorous pollutant, which not only seriously pollutes the environment and reduces the air quality, but also can enter human bodies through various ways such as respiratory tract, skin and gastrointestinal tract, etc., thus causing great harm to human health. In addition, styrene can also produce strong stimulation to eyes and upper respiratory tract, which causes people to feel uncomfortable, such as lacrimation, watery nasal discharge, cough, sneeze and the like, and even causes acute poisoning, and produces symptoms of dizziness, headache, hypodynamia and the like.
The limit of the styrene emission in the waste gas is 50mg/m specified in GB-1571 petrochemical industry pollutant emission Standard newly issued by the state 3 . At present, the effective treatment of domestic styrene waste gas is mostly in the laboratory research stage, the effective treatment methods are few in reports, and because the methods have certain application range and limitation, the method is difficult to comprehensively develop the treatment of the styrene waste gas generated by styrene in loading, shipping and storage tank breathing of refining enterprises.
At present, the treatment methods of the styrene waste gas mainly comprise a condensation method and an adsorption method: the condensation method can directly recover liquid styrene, but the condensation method reaches the environmental protection standard and needs to be reduced to a very low temperature, so that the energy consumption is high, the device configuration is complex and the maintenance is difficult; however, most of the styrene waste gas treated by the adsorption method adopts an activated carbon adsorbent, but in view of the problems of easy polymerization, polymerization heat effect and large adsorption heat effect of styrene, the activated carbon is easy to deactivate and regenerate after long-term use of activated carbon adsorption, and a fire risk is caused.
Chinese patent CN204543913U discloses a styrene recovery system, which liquefies tail gas by setting a condenser to facilitate separation of styrene, and the liquefied tail gas is collected in a degassing collecting tank, and then is introduced into an oil-water separator after being collected to a certain amount, so as to realize separation of styrene and water and purification of styrene. However, the styrene treatment system has a very limited application range and a complicated process.
For another example, chinese patent CN102527185A discloses a method for adsorbing styrene waste gas by using modified sepiolite, which can adsorb foul waste gas containing styrene at 0-80 ℃ by using modified sepiolite in an adsorption tower, the modified sepiolite after adsorption saturation can desorb styrene in situ at 150-350 ℃, high concentration styrene is condensed and recovered, and the sepiolite is recycled after regeneration. However, the preparation of the modified sepiolite is complex, the desorption temperature is high, and certain potential safety hazards exist.
For another example, patent CN105344224A discloses a styrene waste gas treatment method, in which styrene waste gas is used to make countercurrent contact with an alkaline solution of potassium permanganate, during the contact process, the styrene and the alkaline solution of potassium permanganate undergo an oxidation reaction, and after the reaction is completed, the waste gas which has consumed styrene is discharged into the atmosphere. The process can realize the removal of styrene in the waste gas, but MnO generated after the reduction of the alkaline solution of potassium permanganate 2 And the like do not have a good treatment process.
Therefore, the development of a safe and stable styrene recovery process with high recovery efficiency is an urgent problem in the field of styrene production, and has great industrial and environmental significance.
Disclosure of Invention
Therefore, the technical problem to be solved by the present invention is to provide a recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption, so as to solve the problem of environmental pollution caused by difficult recovery of styrene waste gas in the prior art.
In order to solve the technical problem, the recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption comprises the following steps:
(1) Fully mixing the styrene waste gas with an absorbent, and carrying out flash evaporation separation on the mixed material to obtain a gas-phase material and a liquid-phase material;
(2) Mixing the obtained gas-phase material with a washing liquid for washing, and further recovering styrene and an organic solvent in tail gas; recovering the obtained liquid-phase material;
(3) Adsorbing the washed gas material to further remove organic matters in the tail gas, and discharging the adsorbed tail gas;
(4) And (4) carrying out material separation treatment on the washing liquid after washing treatment, and respectively recovering the separated oil phase material and the washing liquid.
Specifically, in the step (1), the absorbent includes at least one of dimethylformamide, benzene, toluene, ethylbenzene, dimethylacetamide, o-xylene, p-xylene, m-xylene, dimethyl sulfoxide, ethylene glycol, pyrolysis gasoline or depentanized oil. More preferably o-xylene, ethylbenzene, p-xylene, m-xylene, pyrolysis gasoline, depentanizer oil, or a mixture of the five, wherein the content of o-xylene, p-xylene and m-xylene is 0-100% respectively, and the content of pyrolysis gasoline and depentanizer oil is 0-40%.
Specifically, in the step (1), the mass-to-volume ratio of the absorbent to the styrene tail gas is 0.033 to 0.4kg/cum, the temperature in the mixing step is controlled to be 30 to 90 ℃, and the pressure is controlled to be 0 to 10atm. More preferably, the mass-to-volume ratio of the absorbent to the styrene tail gas is 0.17-0.3 kg/cum, the temperature of the mixing step is controlled to be 30-50 ℃, and the pressure is controlled to be 3-6 atm.
The mixing step is carried out in a mixer, which can be a static mixer, a venturi mixer, a line mixer and a mixing tank, and preferably a venturi mixer and a line mixer.
When the Venturi mixer is selected, the ratio range of the diameter of the throat pipe section to the diameter of the inlet and the outlet is selected to be 0-1, the ratio range of the length range of the contracted section to the length of the inlet and the outlet is selected to be 0-1, and the ratio range of the length range of the expanded section to the length of the inlet and the outlet is selected to be 0-1. More preferably, the preferred range of the ratio of the diameter of the throat pipe section of the Venturi mixer to the diameter of the inlet and the outlet is 0.1-0.4, the preferred range of the ratio of the length of the contracted section to the length of the inlet and the outlet is 0.2-0.4, and the preferred range of the length of the expanded section to the length of the inlet and the outlet is 0.3-0.7.
When a line mixer is selected, the line mixer has a diameter in the range of 0 to 0.9m and a ratio of length to diameter in the range of 0 to 20, more preferably a line mixer has a diameter in the range of 0.3 to 0.6m and a ratio of length to diameter in the range of 7 to 14.
Specifically, in the step (1), the temperature in the flashing step is-30 to 90 ℃, and the pressure in the flashing step is 0 to 10atm. More preferably, the temperature of the flash step is 20 to 40 ℃ and the pressure is 3 to 7atm.
Specifically, in the step (2), the washing liquid is water, and the mass-to-volume ratio of the washing liquid to the styrene-containing gas phase material is 0.04-0.7 kg/cum. More preferably, the mass-to-volume ratio of the washing liquid to the styrene tail gas is 0.15-0.4 kg/cum.
Specifically, in the step (2), the temperature of the washing step is 0-90 ℃, and the pressure is 0-10 atm. More preferably, the temperature of the washing step is 20 to 40 ℃ and the pressure is 3 to 6atm.
Specifically, in the step (2), part of the obtained liquid-phase materials are recycled as the absorbent, and the rest of the liquid-phase materials are recycled.
Specifically, in the step (2), the washing step is carried out in a washing column, and the number of the plates of the washing column is controlled to be 2 to 22, and preferably 5 to 14. The washing column may be a packed column or a tray column.
Specifically, in the step (3), an adsorbent is used for removing the organic solvent in the gas-phase material in the adsorption step; the adsorbent comprises activated carbon, an X-type molecular sieve, a 5A-type molecular sieve or diatomite. Most preferred are activated carbon and type X molecular sieves.
Specifically, in the step (3), the temperature in the adsorption step is 0-90 ℃, the pressure is 0-6 atm, and the adsorption space velocity is 0-8 h -1 . Preferably, the adsorption temperature is controlled to be 30-60 ℃, the pressure is 1-3 atm, and the adsorption space velocity is 1-4 h 1 。
Specifically, the step (4) further comprises the step of recycling the oil-phase material as an absorbent; and recycling the washing solution.
The recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption comprises mixing, flash evaporation, washing and adsorption, can treat styrene-containing waste gas generated in various places such as tail gas of a styrene-butadiene device, wharf shipping, storage tank breathing and the like, recovers 85-95% of styrene in the waste gas through mixing and flash evaporation, recovers 4-15% of styrene in the waste gas through washing, then adsorbs an absorbent and the rest of styrene through adsorption, and controls the content of organic waste gas in the tail gas below a discharge standard so as to meet normal discharge. The recovery process can recycle the styrene in the waste gas to the maximum extent, changes waste into valuable, avoids the polymerization of the styrene in the adsorption process, and effectively ensures the stable operation of the device.
Drawings
In order that the manner in which the disclosure of the present invention is attained and can be more readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings, wherein,
FIG. 1 is a schematic flow diagram of an apparatus for the recovery process of the present invention;
in the figures, the reference numbers are given by: 1-mixer, 2-flash tank, 3-washing tower, 4-adsorption reactor, 5-oil-water separator, 6-styrene waste gas, 7-absorbent, 8-gas phase material, 9-liquid phase material, 10-washing liquid, 11-oil phase, 12-water phase and 13-tail gas.
Detailed Description
As shown in a schematic process unit diagram shown in FIG. 1, the device for realizing the recovery process comprises a mixer 1, a flash tank 2, a washing tower 3, an adsorption reactor 4 and an oil-water separator 5 which are communicated in sequence.
According to the recovery scheme in the following embodiment of the invention, when the styrene waste gas is recovered, the styrene waste gas 6 and the selected absorbent 7 are fully mixed in the mixer 1, and the mixed material enters the flash tank 2 for flash evaporation treatment; after the materials are subjected to flash separation, a gas phase material 8 positioned at the top of the flash tank 2 enters a washing tower 3 for washing, a part of liquid phase in a separated liquid phase material 9 returns to the mixer 1 to be reused as an absorbent, and the rest of liquid phase is recycled as a high-value product; the gas-phase material 8 enters the washing tower 3 from the tower bottom, is in countercurrent contact with washing liquid 10 (water) on the tower top on a tower tray, styrene and an organic solvent in tail gas are recovered through washing, the gas-phase material on the tower top of the washing tower 3 enters the adsorption reactor 4, and organic matters in the tail gas are removed through an adsorbent so as to ensure that the tail gas 13 is discharged after reaching the standard; the liquid phase material (mainly mixture of water, styrene and absorbent) at the bottom of the washing tower 3 enters the oil-water separator 5, after standing and layering, the oil phase 11 at the upper part returns to the mixer 1 to be reused as absorbent, and the water phase 12 at the lower part returns to the top of the washing tower 3 to be reused as washing liquid.
Example 1
In this example, the styrene waste gas is four 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 The styrene content was 6000ppm, the remainder being air.
The recycling process described in this example employs an apparatus such as that shown in FIG. 1 for recycling.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, o-xylene is used as an absorbent, the temperature of the mixer is controlled to be 32 ℃, and the flow rate of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
In the adsorption reactor 4, active carbon is used as an adsorbent, and the gas phase airspeed is controlled to be 2h -1 。
In this example, the content changes of styrene and absorbent in the gas-phase material and the liquid-phase material related to each apparatus part after the above recovery process are shown in table 1.
Table 1 example 1 content of organics in gas and liquid phases
Figure BDA0002105112520000061
Figure BDA0002105112520000071
As can be seen from the data in Table 1 above, the styrene content in the treated tail gas is reduced from 6000ppm to 35ppm, the recovery rate of styrene is 99.42%, at this time, the content of o-xylene is 430ppm, and the benefit brought by raw material absorption is calculated to be about 7666 yuan; after all the adsorption treatment, the total content of the styrene and the o-xylene in the tail gas is only 23ppm, and the emission standard is met.
Comparative example 1
In this comparative example, the styrene off-gas was measured at four times of 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, wherein the styrene content is 6000ppm, and the balance is air.
The recycling process of this comparative example was conducted using an apparatus such as that shown in FIG. 1.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 1m, the length of the mixer is 10m, o-xylene is used as an absorbent, the temperature of the mixer is controlled to be 32 ℃, and the flow rate of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is washed by a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
In the adsorption reactor 4, active carbon is used as an adsorbent, and the airspeed of a gas phase is controlled to be 2h -1 。
In this comparative example, the changes in the contents of styrene and the absorbent in the gas-phase material and the liquid-phase material in each apparatus part after the above-mentioned recovery process are shown in Table 2.
TABLE 2 content of organic substances in gas and liquid phases
Figure BDA0002105112520000072
Figure BDA0002105112520000081
As can be seen from the data in Table 2 above, compared with the embodiment of example 1, when the diameter of the line mixer is increased to 1m under the condition that the rest of the process conditions are unchanged, the mixing effect is deteriorated, the content of the styrene in the gas phase at the top of the flash tank is increased from 320ppm to 1250ppm, the content of the styrene in the corresponding gas phase at the top of the washing tower is increased from 35ppm to 450ppm, and the content of the styrene in the tail gas is far higher than the content of the styrene in the emission standard and cannot be directly discharged.
Example 2
In this example, the styrene waste gas is four 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, styrene content 2000ppm, remainder air.
The recycling process described in this example uses an apparatus such as that shown in FIG. 1 for recycling.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, o-xylene is used as an absorbent, the temperature of the mixer is 32 ℃, and the flow rate of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
In the adsorption reactor 4, active carbon is used as an adsorbent, and the gas phase airspeed is controlled to be 2h -1 。
In this example, the content changes of styrene and absorbent in the gas-phase material and the liquid-phase material related to each apparatus part after the above recovery process are shown in table 3.
TABLE 3 content of organic substances in gas and liquid phases
Figure BDA0002105112520000082
Figure BDA0002105112520000091
As can be seen from the data in Table 3, the styrene content in the treated tail gas is reduced from 2000ppm to 1ppm, the recovery rate of styrene is 99.95%, at this time, the content of o-xylene is 320ppm, and the benefit brought by the raw material absorption is about 7015 yuan; after all the adsorption treatment, the total content of styrene and o-xylene in the tail gas is 12ppm, which meets the emission standard.
Comparative example 2 to 1
In this comparative example, the styrene off-gas was measured at four times of 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, styrene content 2000ppm, remainder air.
The recycling process described in this comparative example was carried out using an apparatus such as that shown in FIG. 1.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, o-xylene is used as an absorbent, the temperature of the mixer is 32 ℃, and the flow of the absorbent in the mixer is controlled to be 400kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
The adsorption reactor 4 takes activated carbon as an adsorbent, and controls the gas phase airspeed to be 2h -1 。
In this comparative example, the changes in the styrene and absorbent contents in the gas-phase material and the liquid-phase material in each apparatus part after the above-mentioned recovery process are shown in Table 4.
TABLE 4 content of organic substances in gas and liquid phases
Figure BDA0002105112520000092
Figure BDA0002105112520000101
As can be seen from the data in Table 4, compared with the scheme of example 2, under the condition that the rest of the process conditions are not changed, the flow rate of the absorbent in the mixer is reduced from 800kg/h to 400kg/h, the mixing effect is deteriorated, the content of the styrene in the gas phase at the top of the flash tank is increased from 85ppm to 435ppm, the content of the styrene in the corresponding gas phase at the top of the washing tower is increased from 1ppm to 225ppm, and the content of the styrene in the tail gas is 79ppm, which exceeds the content of the styrene in the emission standard, so that the direct emission cannot be realized.
Comparative examples 2 to 2
In this comparative example, the styrene off-gas was measured at four times of 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, styrene content 2000ppm, remainder air.
The recycling process of this comparative example was conducted using an apparatus such as that shown in FIG. 1.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, benzene is used as an absorbent, the temperature of the mixer is 32 ℃, and the flow of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
The adsorption reactor 4 takes activated carbon as an adsorbent, and controls the gas phase airspeed to be 2h -1 。
In this comparative example, the changes in the contents of styrene and the absorbent in the gas-phase material and the liquid-phase material in each apparatus part after the above-mentioned recovery process are shown in Table 5.
TABLE 5 content of organic substances in gas and liquid phases
Figure BDA0002105112520000102
Figure BDA0002105112520000111
As can be seen from the data in Table 5, compared with the scheme of example 2, under the condition that the rest process conditions are not changed, the benzene-substituted ortho-xylene is used as the absorbent, the mixing effect and the absorption effect are basically not changed, the content of the styrene in the gas phase at the top of the flash tank is reduced from 85ppm to 74ppm, and the content of the styrene in the gas phase at the top of the washing tower is not changed. However, the benzene content in the gas phase is obviously increased, the benzene content in the gas phase at the top of the flash tank is increased from 10000ppm to 110000ppm, the benzene content in the gas phase at the top of the washing tower is increased from 203ppm to 10230ppm, the benzene content in the gas phase at the outlet of the adsorption reactor is increased from 12ppm to 2345ppm, the discharge standard cannot be met, and the process is not economical.
Example 3
In this example, the styrene waste gas is in the range of four to 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, styrene content 3000ppm, remainder air.
The recycling process described in this example employs an apparatus such as that shown in FIG. 1 for recycling.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, o-xylene is used as an absorbent, the temperature of the mixer is 32 ℃, and the flow of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
The adsorption reactor 4 takes activated carbon as an adsorbent, and controls the gas phase airspeed to be 2h -1 。
In this example, the content changes of styrene and absorbent in the gas-phase material and the liquid-phase material related to each apparatus part after the above recovery process are shown in table 6.
TABLE 6 content of organic substances in gas and liquid phases
Figure BDA0002105112520000121
As can be seen from the data in Table 6, after the treatment, the styrene content in the tail gas is reduced from 3000ppm to 12ppm, the recovery rate of the styrene is 99.6%, at this time, the content of the o-xylene is 324ppm, and the benefit brought by the raw material absorption is about 7397 yuan; after all the adsorption treatments, the content of the styrene and the o-xylene in the tail gas is 15ppm, which meets the emission standard.
Comparative example 3-1
In this comparative example, the styrene off-gas was used at a rate of four 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, styrene content 3000ppm, remainder air.
The recycling process of this comparative example was conducted using an apparatus such as that shown in FIG. 1.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, o-xylene is used as an absorbent, the temperature of the mixer is 32 ℃, and the flow rate of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow of water in the absorption tower is controlled to be 400kg/h.
The adsorption reactor takes activated carbon as an adsorbent, and controls the gas phase airspeed to be 2h -1 。
In this comparative example, the changes in the contents of styrene and the absorbent in the gas-phase material and the liquid-phase material in each apparatus part after the above-mentioned recovery process are shown in Table 7.
TABLE 7 content of organics in gas and liquid phases
Figure BDA0002105112520000122
Figure BDA0002105112520000131
As can be seen from the data in Table 7, after the treatment according to the comparative example, the styrene content in the tail gas was reduced from 3000ppm to 38ppm, the recovery rate of styrene was 98.7%, and the ortho-xylene content was 724ppm, and the benefit from the raw material absorption was about 6391 yuan. In the embodiment, the content of the styrene and the content of the o-xylene in the gas phase at the top of the washing tower are obviously increased due to the reduction of the water consumption, so that the content of the styrene and the ethylbenzene in the tail gas exceeds the standard and cannot meet the emission standard.
Comparative examples 3 to 2
In this comparative example, the styrene off-gas was measured at four times of 5000m 3 The styrene storage tanks are all internal floating roof tanks, and the flow of the tail gas discharged through the breathing holes is 3000m 3 H, styrene content 3000ppm, remainder air.
The recycling process described in this comparative example was carried out using an apparatus such as that shown in FIG. 1.
In the mixer 1, a pipeline mixer is adopted, the diameter of the pipeline mixer is controlled to be 0.4m, the length of the mixer is 4m, o-xylene is used as an absorbent, the temperature of the mixer is 32 ℃, and the flow of the absorbent in the mixer is controlled to be 800kg/h.
In the flash tank 2, the temperature is controlled to be 30 ℃ and the pressure is controlled to be 3.9atm. The gas phase at the top of the flash tank 2 is subjected to a washing tower 3, 90% of the liquid phase at the bottom of the flash tank 2 returns to the mixer 1 to be used as an absorbent, and the other 10% is recycled.
The washing tower 3 is a packed tower, the number of theoretical plates is 8, the temperature at the top of the tower is 30 ℃, and the flow rate of water in the absorption tower is controlled to be 800kg/h.
The adsorption reactor 4 takes active carbon as an adsorbent,controlling the gas phase space velocity to be 5h -1 。
In this comparative example, the changes in the contents of styrene and the absorbent in the gas-phase material and the liquid-phase material in each apparatus part after the above-mentioned recovery process are shown in Table 8.
TABLE 8 content of organics in gas and liquid phases
Figure BDA0002105112520000141
As can be seen from the data in Table 8, after the treatment of the comparative example, the styrene content in the tail gas is reduced from 3000ppm to 12ppm, the recovery rate of styrene is 99.6%, and the content of o-xylene is 724ppm, and the benefit brought by the absorption of the raw material is about 7397 yuan. In the comparative example, the space velocity of the adsorption reactor is controlled to be from 2h -1 Increased to 5h -1 The content of styrene and o-xylene in the gas phase at the outlet of the adsorption reactor is obviously increased, so that the content of styrene and ethylbenzene in the tail gas exceeds the standard and cannot meet the emission standard.
It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. This need not be, nor should it be exhaustive of all embodiments. And obvious variations or modifications therefrom are within the scope of the invention.

Claims (9)

1. A recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption is characterized by comprising the following steps:
(1) Fully mixing the styrene waste gas with an absorbent, and carrying out flash evaporation separation on the mixed material to obtain a gas-phase material and a liquid-phase material;
the absorbent comprises at least one of dimethylformamide, benzene, toluene, ethylbenzene, dimethylacetamide, o-xylene, p-xylene, m-xylene, dimethyl sulfoxide, ethylene glycol, pyrolysis gasoline or depentanized oil;
(2) Mixing the obtained gas-phase material with a washing liquid for washing, and further recovering styrene and an organic solvent in the styrene waste gas; recovering the obtained liquid-phase material;
the washing liquid is water;
(3) Adsorbing the washed gas material, further removing organic matters in the styrene waste gas, and discharging the adsorbed tail gas;
(4) And (4) carrying out material separation treatment on the washing liquid after washing treatment, and respectively recovering the separated oil-phase material and the washing liquid.
2. The recovery process for treating styrene waste gas based on flash washing adsorption according to claim 1, wherein in the step (1), the mass-to-volume ratio of the absorbent to the styrene waste gas is 0.033 to 0.4kg/cum, the temperature in the mixing step is controlled to be 30 to 90 ℃, and the pressure is controlled to be 0 to 10atm.
3. The recovery process for treating styrene waste gas based on flash scrubbing adsorption according to claim 2, wherein in the step (1), the temperature of the flash step is 30-90 ℃ and the pressure is 0-10 atm.
4. The recovery process for treating styrene waste gas based on flash washing adsorption according to claim 3, wherein in the step (2), the mass-to-volume ratio of the washing liquid to the gas phase material containing styrene is 0.04-0.7 kg/cum; the temperature of the washing step is 0-90 ℃, and the pressure is 0-10 atm.
5. The recovery process of treating styrene waste gas based on flash washing adsorption according to claim 4, wherein in the step (2), part of the liquid phase materials are recovered and used as absorbent for recycling, and the rest of the liquid phase materials are recovered and used.
6. The recovery process for treating styrene waste gas based on flash scrubbing adsorption according to claim 5, wherein in the step (2), the washing step is carried out in a washing tower, and the number of the tower plates of the washing tower is controlled to be 2-22.
7. The recovery process for treating styrene waste gas based on flash evaporation, washing and adsorption as claimed in claim 6, wherein in the step (3), an adsorbent is used for removing the organic solvent in the gas phase material in the adsorption step; the adsorbent comprises activated carbon, an X-type molecular sieve, a 5A-type molecular sieve or diatomite.
8. The recovery process of treating styrene waste gas based on flash washing adsorption as claimed in claim 7, wherein in the step (3), the temperature of the adsorption step is 0-90 ℃, the pressure is 0-6 atm, and the adsorption space velocity is 0-8 h -1 。
9. The recovery process for treating styrene waste gas based on flash washing adsorption according to any one of claims 1 to 8, characterized in that, in the step (4), the process further comprises the step of recycling the oil phase material as an absorbent; and recycling the washing solution.
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