CN114950077B - Treatment process of styrene storage tank tail gas - Google Patents
Treatment process of styrene storage tank tail gas Download PDFInfo
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- CN114950077B CN114950077B CN202210591195.6A CN202210591195A CN114950077B CN 114950077 B CN114950077 B CN 114950077B CN 202210591195 A CN202210591195 A CN 202210591195A CN 114950077 B CN114950077 B CN 114950077B
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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
- B01D53/14—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
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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
- B01D53/14—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
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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
- B01D53/14—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
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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
- B01D53/14—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
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/005—Processes comprising at least two steps in series
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/04—Purification; Separation; Use of additives by distillation
- C07C7/05—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds
- C07C7/06—Purification; Separation; Use of additives by distillation with the aid of auxiliary compounds by azeotropic distillation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C7/00—Purification; Separation; Use of additives
- C07C7/11—Purification; Separation; Use of additives by absorption, i.e. purification or separation of gaseous hydrocarbons with the aid of liquids
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
- B01D2252/20—Organic absorbents
- B01D2252/202—Alcohols or their derivatives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
- B01D2252/50—Combinations of absorbents
- B01D2252/504—Mixtures of two or more absorbents
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
Abstract
The invention discloses a treatment process of styrene storage tank tail gas, which comprises the following steps: using crude phenethyl alcohol and desalted water as an absorbent, and carrying out absorption treatment on tail gas of a styrene storage tank in an absorption tower to obtain the treated tail gas, wherein the styrene content in the tail gas is not more than 100ppm; and (3) enabling a flow at the bottom of the absorption tower rich in styrene to enter a separation tower, separating styrene from an absorbent through the azeotropic effect of water and styrene, recycling crude phenethyl alcohol at the bottom of the tower to the absorption tower for recycling, standing and layering the azeotropic styrene and water at the top of the tower in a reflux tank, enabling an oil phase to enter a styrene refining system, and enabling a water phase to return to the absorption tower for feeding and supplementing water. The process method not only realizes recycling of the styrene in the tail gas of the styrene storage tank and reduces the unit consumption of products, but also solves the problem that the styrene in the tail gas pipeline is easy to generate polymerization blocking in the conventional treatment method, and improves the reliability of the process.
Description
Technical Field
The invention belongs to the field of organic chemical industry, and particularly relates to a treatment process of tail gas of a styrene storage tank.
Technical Field
Styrene is an important organic basic chemical raw material, is mainly used for producing synthetic resin, ion exchange resin, synthetic rubber and the like, and is also widely applied to industries such as pharmacy, pesticide, mineral separation and the like.
The current industrial styrene production method mainly comprises the following steps: and the propylene oxide co-oxidation co-production styrene process (PO/SM), ethylbenzene dehydrogenation process, pyrolysis gasoline extraction process and the like. As the main flow of styrene production process, the styrene product produced by ethylbenzene dehydrogenation process accounts for more than 75% of global industrial yield, and the main flow is that benzene and ethylene react to produce ethylbenzene, and then ethylbenzene is dehydrogenated to produce styrene. The process for extracting the pyrolysis gasoline is a method for separating the styrene from the produced pyrolysis gasoline by taking liquefied petroleum gas, naphtha and the like as main raw materials and adopting an extraction mode, and the process has the problems of poor stability of the S content of impurities in the obtained styrene product, high color number of the product and the like. The PO/SM process has been growing in recent years, and the demand for propylene oxide is vigorous due to the multiplication of the demand for downstream polyurethane, polyether and other products. As one of the propylene oxide production processes by the co-oxidation method, the PO/SM process has been developed for many years, and compared with the propylene oxide production process by the cumene co-oxidation method, the propylene oxide production process is mature and stable and has high reliability; meanwhile, compared with the traditional process for producing propylene oxide by using the chlorohydrin method, the PO/SM process has the advantages of less waste water amount and more environment friendliness. So the PO/SM technology with the two hot chemical raw materials of styrene and propylene oxide for high-efficiency and stable production is currently favored by various large chemical production companies.
However, in the process of producing and storing the styrene, if the styrene organic waste gas is improperly disposed and is easy to overflow and spread, the ecological environment and the health of personnel are damaged. The styrene tail gas produced by the related styrene chemical industry production enterprises is treated by adopting various different modes and processes. As CN105344224A discloses a method for treating waste gas containing styrene, which comprises the steps of carrying out an oxidation reaction on the waste gas containing styrene and an alkaline solution of potassium permanganate to consume and treat the styrene in the waste gas, wherein the method thoroughly removes the styrene, but a large amount of MnO is generated in the reaction process 2 And the like, and is difficult to treat. In addition, CN2012100287229 discloses a method for adsorbing styrene waste gas by modified sepiolite, which mainly adopts an adsorption mode to adsorb the waste gas containing styrene in an adsorption tower filled with modified sepiolite, and can carry out adsorption treatment on the high-content styrene tail gasThe method is effective in treatment, and the adsorbent can be regenerated and reused, but the regeneration flow of the adsorbent in the method is complex, the temperature of the adsorption exothermic process is high, and the high-content styrene has polymerization risk. In addition, CN109304084A discloses a method for recycling organic waste gas containing styrene in tank areas and loading materials, and the method combines absorption, adsorption and catalytic oxidation, has a good effect on treating styrene with the content of more than 30ppm in waste gas, but has the defects of complex whole treatment flow, high catalytic oxidation operation energy consumption and high maintenance cost.
Therefore, there is still a need to develop a treatment process suitable for the tail gas of a styrene storage tank, which solves the problems existing in the treatment methods of the prior art.
Disclosure of Invention
The invention aims to provide a treatment process for styrene storage tank tail gas, which is used for recycling styrene in the styrene storage tank tail gas, reducing unit consumption of products, solving the problem that styrene in a tail gas pipeline is easy to generate polymerization blockage in a conventional treatment method and improving process reliability.
In order to achieve the above object, the present invention adopts the following technical scheme:
a treatment process of styrene storage tank tail gas comprises the following steps:
1) Absorbing tail gas from a styrene storage tank in an absorption tower by using an absorbent, and obtaining treated tail gas at the top of the absorption tower, wherein the styrene content is not more than 100ppm;
2) And (3) enabling a flow rich in styrene in the tower bottom of the absorption tower to enter a separation tower, separating the styrene from the absorbent through azeotropic action of water and the styrene, recycling the flow in the tower bottom of the separation tower to the absorption tower to be used as the absorbent again, standing and layering materials obtained at the tower top of the separation tower, enabling the styrene to enter a refining system, and returning the water to the absorption tower to be used as absorbent water supplement.
In a specific embodiment, the styrene material in the styrene storage tank is derived from styrene co-produced in a process for producing propylene oxide by the ethylbenzene co-oxidation process.
In a specific embodiment, the absorbent in step 1) enters at the upper part of the absorption tower, and the styrene tail gas enters at the lower part of the absorption tower; and sending the treated tail gas obtained from the top of the absorption tower to a device incineration system.
In a specific embodiment, the absorbent is a mixed solution of crude phenethyl alcohol and desalted water which are intermediate products of the process for producing propylene oxide by an ethylbenzene co-oxidation method; preferably, the mixed solution contains phenethyl alcohol, acetophenone and desalted water; more preferably, the mass ratio of phenethyl alcohol, acetophenone and desalted water in the absorbent is 80-90: 7-14: 3 to 6, preferably 83 to 87:10 to 12:4 to 5.
In a specific embodiment, the styrene concentration in the tail gas entering the absorber is 100 to 15000ppm, preferably 500 to 10000ppm; after absorption treatment by the absorption tower, the styrene content in the discharged tail gas is not more than 50ppm.
In a specific embodiment, the bottom stream of the absorption tower is divided into two streams, one stream is returned to the middle part of the absorption tower as circulating absorption liquid, and the other stream enters the separation tower, and the mass ratio of the two streams is 1.0-3.0, preferably 1.5-2.5.
In a specific embodiment, the mass ratio of the absorbent entering from the top of the tower, the circulating absorption liquid in the tower and the styrene tail gas fed from the lower part of the tower is 5-10: 15-35: 20 to 55, preferably 6 to 8: 20-30: 30-40.
In a specific embodiment, the bottom stream of the separation tower is divided into two streams, one stream returns to the absorption tower to be used as an absorbent again, and the other stream is discharged to remove impurities; preferably, the mass ratio of the stream returned to the absorber to the effluent impurity-removed stream is from 50 to 300, preferably from 70 to 100.
In a specific embodiment, the absorber is a packed column, preferably in the form of at least any one of raschig rings, spiral rings, wire mesh, more preferably raschig rings; the number of the trays is 5 to 20, preferably 7 to 15; the pressure of the absorption tower is 3-10 KPaG, preferably 5-8 KPaG; the temperature at the top of the absorption column is 10 to 20 ℃, preferably 12 to 15 ℃.
In a specific embodiment, the separation column is a tray column having a tray number of 3 to 25, preferably 5 to 20; the operating pressure of the separation tower is 30-90 KPaA, preferably 50-80 KPaA; the reflux ratio is 1 to 10, preferably 3 to 7; the temperature of the tower kettle is 130-160 ℃, preferably 140-150 ℃.
Compared with the prior art, the treatment process for the tail gas of the styrene storage tank has the following advantages:
(1) The process method of the invention captures and recycles the styrene in the tail gas of the styrene storage tank in a mode of combining the absorption and separation processes, reduces the loss of the styrene product in the storage process, improves the comprehensive yield of the styrene of the production device, and reduces the unit consumption of the product.
(2) The styrene content in the tail gas obtained by the process method is low, the problem that the tail gas pipeline is blocked due to polymerization caused by the fact that the residual styrene content in the tail gas pipeline is too high in the conventional process method is solved, and the safety and reliability of the process flow for producing styrene are improved.
Drawings
FIG. 1 is a schematic diagram of an apparatus system for a styrene tank tail gas treatment process of the present invention.
Wherein 1 is a styrene storage tank, 2 an absorption tower, 3 a separation tower, 4a reflux tank, 5 a styrene-containing tail gas, 6 an absorption tower top exhaust gas, 7 an absorption tower bottom stream, 8 a circulating stream in the tower, 9 an externally discharged waste oil, 10 a water phase, 11 a styrene oil phase, 12 a separation tower bottom stream, 13 a fresh crude phenethyl alcohol pipeline and 14 a fresh desalting water pipeline.
Detailed Description
The following examples will further illustrate the method provided by the present invention for a better understanding of the technical solution of the present invention, but the present invention is not limited to the examples listed but should also include any other known modifications within the scope of the claims of the present invention.
As shown in fig. 1, a treatment process of styrene storage tank tail gas comprises the following steps:
1) Absorbing the tail gas 5 containing styrene from the styrene storage tank 1 in the absorption tower 2 by using an absorbent to obtain treated exhaust gas 6 at the top of the absorption tower, which meets the emission requirement;
2) The stream 7 at the bottom of the absorption tower enters the separation tower 3, styrene is separated from the absorbent through azeotropic action of water and styrene, the stream 12 at the bottom of the separation tower 3 is circulated to the absorption tower 2 to be used as the absorbent again, after materials in the reflux tank 4 at the top of the separation tower 3 are kept stand and layered, the styrene oil phase 11 enters the refining system, and the water phase 10 returns to the absorption tower to be used as absorbent water supplement.
The absorbent of the invention is the mixture of crude phenethyl alcohol which is a specific intermediate product in the process of producing propylene oxide by an ethylbenzene co-oxidation method and desalted water according to a certain proportion, and the composition of the crude phenethyl alcohol is as follows: the mass ratio of the phenethyl alcohol to the acetophenone to the desalted water in the absorbent is 80-90: 7-14: 3 to 6, preferably 83 to 87:10 to 12:4 to 5.
In a preferred embodiment, the absorbent enters at the upper part of the absorption tower 2, and the styrene tail gas 5 enters at the lower part of the absorption tower 2; the treated tail gas obtained from the top of the absorption tower 2, namely the exhaust gas 6 from the top of the absorption tower, is sent to a device incineration system. Wherein the styrene storage tank material is styrene prepared by co-production of epoxypropane by an ethylbenzene co-oxidation method, and the styrene content is 99.99%. The styrene tank tail gas, except for a small amount of styrene, is nitrogen purged air, wherein the styrene concentration is 100 to 15000ppm, including, for example, but not limited to, 200ppm, 500ppm, 1000ppm, 2000ppm, 3000ppm, 5000ppm, 6500ppm, 8000ppm, 10000ppm, 12000ppm, 14000ppm, preferably 500 to 10000ppm; after the absorption treatment by the absorption tower, the concentration of styrene in the discharged tail gas is preferably not more than 50ppm.
In a preferred embodiment, the absorber bottoms stream 7 is split into two streams, one of which is returned to the absorber as the mid-column recycle stream 8 and the other of which enters the separator 3. Specifically, the mass ratio of the two streams of the recycle stream returned to the absorber column to the stream entering the separator column is 1.0 to 3.0, including, for example, but not limited to, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, preferably 1.5 to 2.5.
Wherein, the mass ratio of the absorbent entering from the top of the tower to the circulating absorption liquid in the tower to the styrene tail gas fed into the lower part of the tower is 5-10: 15-35: 20 to 55, preferably 6 to 8: 20-30: 30-40. The absorption tower is a packed tower, and the number of the tower plates is 5-20, including, but not limited to, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, preferably 7-15; the absorber pressure is 3 to 10KPaG, including for example but not limited to 4KPaG, 5KPaG, 6KPaG, 7KPaG, 8KPaG, 9KPaG, preferably 5 to 8KPaG; the absorber tower top temperature is 10 to 20 ℃, including for example but not limited to 11 ℃, 12 ℃, 13 ℃, 14 ℃, 15 ℃, 16 ℃, 17 ℃, 18 ℃, 19 ℃, preferably 12 to 15 ℃.
Styrene and water are separated from the absorption liquid in a separation tower, and the styrene and the water are sent to the top of the tower in an azeotropic mode and condensed into a reflux tank at the top of the tower for phase separation; the oil phase rich in styrene enters a styrene refining system in a main device process, and the water phase returns to be used as absorbent replenishing water for reuse. In a preferred embodiment, the separator bottoms stream 12 is split into two streams, one stream being recycled to absorber 2 for reuse as absorbent and the other stream being discharged from waste oil 9. Wherein the mass ratio of the return to the absorber to the external displacement is 50 to 300, including for example but not limited to 60, 80, 100, 150, 200, 225, 250, 275, 290, 300, preferably 70 to 100.
Wherein the separation tower is a plate tower with the number of plates of 3-25, including, for example, but not limited to, 4, 6, 8, 10, 12, 14, 16, 18, 20, 23, preferably 5-20; the separation column operating pressure is 30 to 90KPaA, including for example, but not limited to, 35KPaA, 40KPaA, 45KPaA, 50KPaA, 55KPaA, 60KPaA, 65KPaA, 70KPaA, 75KPaA, 80KPaA, 85KPaA, preferably 50 to 80KPaA; the reflux ratio is 1 to 10, including for example but not limited to 2, 3, 4, 5, 6, 7, 8, 9, preferably 3 to 7; the temperature of the tower bottom is 130-160 ℃, including but not limited to 135 ℃, 140 ℃, 145 ℃, 150 ℃, 155 ℃, preferably 140-150 ℃, for example.
The absorber 2 is also provided with a make-up fresh raw phenethyl alcohol line 13, a make-up fresh desalinated water line 14 to make-up fresh raw phenethyl alcohol and desalinated water. The additional fresh raw phenethyl alcohol line 13, the additional fresh desalted water line 14 are preferably provided in combination with other circulation lines, for example, the line from the bottom of the separation column 3 to the absorption column 2.
The invention is further illustrated, but not limited, by the following more specific examples.
Example 1
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 7, the tower pressure is 5KPaG, and the tower top temperature is 12 ℃; the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is 87:10:3. the flow rate of the tail gas stream containing styrene is 1500m 3 The liquid/h enters from the lower part of the absorption tower, the feeding amount of the absorbent at the top of the tower is 450kg/h, the flow rate of the circulating absorption liquid in the tower kettle to the tower is 1350kg/h, and the flow rate of the absorption liquid in the tower kettle to the feeding flow rate of the separation tower is 540kg/h; fresh desalted water is fed in 10kg/h, and fresh crude phenethyl alcohol is fed in 20kg/h.
The theoretical plate number of the separation tower is 5, the tower pressure is 50KPaG, the reflux ratio is 3, and the temperature of the tower kettle is 145 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 420kg/h, and the amount of the discharged waste oil is 5kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to be 12.5kg/h, and the oil phase of the oil-water separation tank at the top of the tower goes to the flow rate of the SM refining system of 170.05kg/h.
TABLE 1 organic content in each of the gas and liquid phase streams
According to the data in Table 1, after the treatment by the process, the styrene content in the exhaust gas is 4ppm, the styrene removal rate is 99.95%, and the total organic matter content in the exhaust gas is 12ppm, thereby meeting the environmental protection design requirement; in addition, the recovery rate of styrene recovered by the separation column was 99.76%.
Example 2
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 15, the tower pressure is 8KPaG, and the tower top temperature is 15 ℃; the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is 83:12:5. the flow rate of the tail gas stream containing styrene is 1500m 3 The liquid/h enters from the lower part of the absorption tower, the feeding amount of the top absorbent is 450kg/h, the flow rate of the circulating absorption liquid in the tower kettle to the tower is 1080kg/h, and the flow rate of the absorption liquid in the tower kettle to the feeding flow rate of the separation tower is 540kg/h; fresh desalted water is fed in 10kg/h, and fresh crude phenethyl alcohol is fed in 20kg/h.
The theoretical plate number of the separation tower is 20, the tower pressure is 80KPaG, the reflux ratio is 7, and the temperature of the tower kettle is 150 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 600kg/h, and the amount of the discharged waste oil is 6kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of 11.3kg/h of the feed line of the absorbent, and the flow rate of the oil phase of the oil-water separation tank at the top of the tower to the SM refining system of the main device is 101.8kg/h.
TABLE 2 organic content in each of the gas and liquid phase streams
According to the data in Table 2, after the treatment by the process, the styrene content in the exhaust gas is 13ppm, the styrene removal rate is 98.34%, and the total organic matter content in the exhaust gas is 22ppm, thereby meeting the environmental protection design requirement; in addition, the recovery rate of styrene recovered by the separation column was 98.11%.
Example 3
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 5, the tower pressure is 3KPaG, and the tower top temperature is 10 ℃; the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is 80:14:6. the flow rate of the tail gas stream containing styrene is 1500m 3 The absorption liquid/h enters from the lower part of the absorption tower, the feeding amount of the top absorbent is 450kg/h, the flow rate of the circulating absorption liquid flow from the tower bottom to the tower is 1200kg/h, and the flow rate of the absorption liquid from the tower bottom to the feeding flow rate of the separation tower is 900kg/h; fresh desalted water feeding amount of 10kg/h and fresh coarseThe feeding amount of the phenethyl alcohol is 20kg/h.
The theoretical plate number of the separation tower is 3, the tower pressure is 30KPaG, the reflux ratio is 1, and the temperature of the tower kettle is 130 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 500kg/h, and the amount of the discharged waste oil is 10kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to be 10.5kg/h, and the flow rate of the oil phase of the oil-water separation tank at the top of the tower to the SM refining system of the main device to be 100.5kg/h.
TABLE 3 organic content in each of the gas and liquid phase streams
According to the data in Table 3, after the treatment by the process, the styrene content in the exhaust gas is 15ppm, the styrene removal rate is 98.95%, and the total organic matter content in the exhaust gas is 22ppm, thereby meeting the environmental protection design requirement; further, the recovery rate of styrene recovered by the separation column was 98.70%.
Example 4
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 19, the tower pressure is 9KPaG, and the tower top temperature is 14 ℃; the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is 89:7:4. the flow rate of the tail gas stream containing styrene is 1500m 3 The absorption liquid/h enters from the lower part of the absorption tower, the feeding amount of the top absorbent is 450kg/h, the flow rate of the circulating absorption liquid flow from the tower bottom to the tower is 1400kg/h, and the flow rate of the absorption liquid from the tower bottom to the feeding flow rate of the separation tower is 675kg/h; fresh desalted water is fed in 10kg/h, and fresh crude phenethyl alcohol is fed in 20kg/h.
The theoretical plate number of the separation tower is 3, the tower pressure is 30KPaG, the reflux ratio is 1, and the temperature of the tower kettle is 130 ℃; the flow rate of the flow returning to the absorption tower of the separation tower kettle is 270kg/h, and the amount of the discharged waste oil is 3kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to 11.1kg/h, and the flow rate of the oil phase of the oil-water separation tank at the top of the tower to the SM refining system to 101.7kg/h.
TABLE 4 organic content in each of the gas and liquid phase streams
According to the data in Table 4, after the treatment by the process, the styrene content in the exhaust gas is 17ppm, the styrene removal rate is 99.05%, and the total organic matter content in the exhaust gas is 24ppm, thereby meeting the environmental protection design requirement; in addition, the recovery rate of styrene recovered by the separation column was 99.00%.
Comparative example 1
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 7, the tower pressure is 5KPaG, and the tower top temperature is 12 ℃; the absorbent is diethylbenzene. The flow rate of the tail gas stream containing styrene is 1500m 3 The liquid/h enters from the lower part of the absorption tower, the feeding amount of the absorbent at the top of the tower is 450kg/h, the flow rate of the circulating absorption liquid in the tower kettle to the tower is 1350kg/h, and the flow rate of the absorption liquid in the tower kettle to the feeding flow rate of the separation tower is 540kg/h; fresh desalted water is fed in 10kg/h, and fresh crude phenethyl alcohol is fed in 20kg/h.
The theoretical plate number of the separation tower is 5, the tower pressure is 50KPaG, the reflux ratio is 3, and the temperature of the tower kettle is 145 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 420kg/h, and the amount of the discharged waste oil is 5kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to be 6.6kg/h, and the flow rate of the oil phase of the oil-water separation tank at the top of the tower to the SM refining system of the main device to be 65.7kg/h.
TABLE 5 organic content in each of the gas and liquid phase streams
According to the data in Table 5, diethylbenzene is adopted as an absorbent to be implemented under the same condition, the styrene content in the exhaust gas is 254ppm, the styrene removal rate is only 88.34 percent, and the total organic matter content in the exhaust gas is 332ppm, so that the environmental protection design requirement is not satisfied; further, the recovery rate of styrene recovered by the separation column was 88.11%.
Comparative example 2
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 7, the tower pressure is 5KPaG, and the tower top temperature is 12 ℃; the absorbent is glycol. The flow rate of the tail gas stream containing styrene is 1500m 3 The liquid/h enters from the lower part of the absorption tower, the feeding amount of the absorbent at the top of the tower is 450kg/h, the flow rate of the circulating absorption liquid in the tower kettle to the tower is 1350kg/h, and the flow rate of the absorption liquid in the tower kettle to the feeding flow rate of the separation tower is 540kg/h; fresh desalted water is fed in 10kg/h, and fresh crude phenethyl alcohol is fed in 20kg/h.
The theoretical plate number of the separation tower is 5, the tower pressure is 50KPaG, the reflux ratio is 3, and the temperature of the tower kettle is 145 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 420kg/h, and the amount of the discharged waste oil is 5kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to be 2.3kg/h, and the oil phase of the oil-water separation tank at the top of the tower enters the SM refining system to be 71.8kg/h.
TABLE 6 organic content in each of the gas and liquid phase streams
According to the data in Table 6, the implementation is carried out under the same conditions by adopting ethylene glycol as an absorbent, the styrene content in the exhaust gas is 110ppm, the styrene removal rate is only 90.58%, and the total organic matter content in the exhaust gas is 245ppm, so that the environmental protection design requirement is not satisfied; in addition, the recovery rate of styrene recovered by the separation column was 89.14%.
Comparative example 3
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
Theoretical plate number of absorption tower 7, tower pressure 5KPaG, tower top temperature 12 ℃; the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is 75:22:3. the flow rate of the tail gas stream containing styrene is 1500m 3 The liquid/h enters from the lower part of the absorption tower, the feeding amount of the absorbent at the top of the tower is 450kg/h, the flow rate of the circulating absorption liquid in the tower kettle to the tower is 1350kg/h, and the flow rate of the absorption liquid in the tower kettle to the feeding flow rate of the separation tower is 540kg/h; fresh desalted water is fed in 10kg/h, and fresh crude phenethyl alcohol is fed in 20kg/h.
The theoretical plate number of the separation tower is 5, the tower pressure is 50KPaG, the reflux ratio is 3, and the temperature of the tower kettle is 145 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 420kg/h, and the amount of the discharged waste oil is 5kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to be 9.3kg/h, and the flow rate of the oil phase of the oil-water separation tank at the top of the tower to the SM refining system of the main device to be 99.5kg/h.
TABLE 7 organic content in each of the gas and liquid phase streams
According to the data in Table 7, compared with example 1, comparative example 3 uses the same amount of absorbent, control parameters of absorption tower and separation tower, etc., and the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is from 87:10:3 to 75:22:3 with the reduction of the phenethyl alcohol content in the absorbent, the styrene content in the exhaust gas is increased to 1591ppm, the styrene removal rate is reduced to 80.11 percent, the total organic matter content in the exhaust gas is 1602ppm, and the recovery rate of the styrene recovered by the separation tower is reduced to 86.68 percent.
Comparative example 4
Taking a device for co-producing styrene by using a Wanhua ethylbenzene co-oxidation method as an example, two styrene product storage tanks, a crude styrene storage tank, the pressure of 2KPaG, the styrene content in the top tail gas of 0.8% and the rest of air after nitrogen purging are shared.
The theoretical plate number of the absorption tower is 7, the tower pressure is 5KPaG, and the tower top temperature is 12 ℃; the mass ratio of phenethyl alcohol, acetophenone and water in the absorbent is 87:10:3. the flow rate of the tail gas stream containing styrene is 1500m 3 The mixture/h enters from the lower part of the absorption tower, the feeding amount of the top absorbent is 100kg/h, and the circulating absorption liquid flow in the tower kettle to the towerFlow 1350kg/h, and flow 360kg/h from the absorption liquid at the tower bottom to the feeding flow of the separation tower; fresh desalted water 7kg/h and fresh crude phenethyl alcohol 13kg/h.
The theoretical plate number of the separation tower is 5, the tower pressure is 50KPaG, the reflux ratio is 3, and the temperature of the tower kettle is 145 ℃; the flow rate of the flow returned from the separation tower to the absorption tower is 420kg/h, and the amount of the discharged waste oil is 3kg/h; the water phase of the oil-water separation tank at the top of the tower returns to the flow rate of the flow of the feeding pipe line of the absorbent to 6.5kg/h, and the oil phase of the oil-water separation tank at the top of the tower enters the SM refining system to flow rate of 82kg/h.
TABLE 8 organic content in each of the gas and liquid phase streams
According to the data in Table 8, comparative example 4 was compared with example 1, and the recovery rate of styrene recovered by the separation column was reduced to 81.47% by using the same absorbent ratio, control parameters of the absorption column and the separation column, etc., and the absorbent amount was reduced from 450kg/h to 100kg/h, the styrene content in the exhaust gas was increased to 2221ppm, the styrene removal rate was reduced to 72.23%, and the total organic matter content in the exhaust gas was 2241 ppm.
While the present invention has been described in detail through the foregoing description of the preferred embodiment, it should be understood that the foregoing description is not to be considered as limiting the invention. Those skilled in the art will appreciate that certain modifications and adaptations of the invention are possible and can be made under the teaching of the present specification. Such modifications and adaptations are intended to be within the scope of the present invention as defined in the appended claims.
Claims (18)
1. The treatment process of the styrene storage tank tail gas is characterized by comprising the following steps of:
1) Absorbing tail gas from a styrene storage tank in an absorption tower by using an absorbent, and obtaining treated tail gas at the top of the absorption tower, wherein the styrene content is not more than 100ppm;
2) The method comprises the steps that a flow rich in styrene at the bottom of an absorption tower enters a separation tower, styrene is separated from an absorbent through azeotropic action of water and the styrene, the flow at the bottom of the separation tower is circulated to the absorption tower to be used as the absorbent again, after materials obtained at the top of the separation tower are kept stand and layered, the styrene enters a refining system, and water returns to the absorption tower to be used as absorbent water supplement;
the absorbent is a mixed solution of crude phenethyl alcohol which is an intermediate product of a propylene oxide production process by an ethylbenzene co-oxidation method and desalted water; the mixed solution contains phenethyl alcohol, acetophenone and desalted water, and the mass ratio of the phenethyl alcohol to the acetophenone to the desalted water in the absorbent is 80-90: 7-14: 3-6.
2. The process for treating tail gas of a styrene storage tank according to claim 1, wherein the styrene material in the styrene storage tank is styrene co-produced from a process for producing propylene oxide by an ethylbenzene co-oxidation method.
3. The process for treating the tail gas of the styrene storage tank according to claim 1, wherein the absorbent in the step 1) enters at the upper part of the absorption tower, and the styrene tail gas enters at the lower part of the absorption tower; and sending the treated tail gas obtained from the top of the absorption tower to a device incineration system.
4. The process for treating the tail gas of the styrene storage tank according to claim 1, wherein the mass ratio of phenethyl alcohol, acetophenone and desalted water in the absorbent is 83-87: 10-12: 4-5.
5. The process for treating tail gas of a styrene storage tank according to claim 1, wherein the concentration of styrene in the tail gas entering the absorption tower is 100-15000 ppm; after absorption treatment by the absorption tower, the concentration of styrene in the discharged tail gas is not more than 50ppm.
6. The process for treating tail gas from a styrene storage tank as defined in claim 5, wherein the concentration of styrene in the tail gas fed into the absorption column is 500 to 10000ppm.
7. A process for treating a styrene storage tank tail gas according to claim 3, wherein the flow at the bottom of the absorption tower is divided into two flows, one flow is returned to the middle part of the absorption tower as circulating absorption liquid, and the other flow enters the separation tower, and the mass ratio of the two flows is 1.0-3.0.
8. The process for treating tail gas of a styrene storage tank according to claim 7, wherein the mass ratio of the two strands is 1.5-2.5.
9. The process for treating tail gas of a styrene storage tank according to claim 7, wherein the mass ratio of the absorbent entering from the top of the tower to the circulating absorption liquid in the tower to the styrene tail gas fed from the lower part of the tower is 5-10: 15-35: 20-55.
10. The process for treating tail gas of a styrene storage tank according to claim 9, wherein the mass ratio of the absorbent entering from the top of the tower to the circulating absorption liquid in the tower to the styrene tail gas fed from the lower part of the tower is 6-8: 20-30: 30-40.
11. The process for treating tail gas of a styrene storage tank according to claim 1, wherein the flow of the bottom of the separation tower is divided into two parts, one part returns to the absorption tower to be used as an absorbent again, and the other part is discharged to remove impurities.
12. The process for treating a styrene tank offgas according to claim 11, characterized in that the mass ratio of the stream returned to the absorption tower to the stream from which impurities are removed by the external discharge is 50 to 300.
13. The process for treating a styrene tank offgas according to claim 11, characterized in that the mass ratio of the stream returned to the absorption tower to the stream from which impurities are removed by the external discharge is 70 to 100.
14. The process for treating tail gas of a styrene storage tank according to claim 1, wherein the absorption tower is a packed tower with a tray number of 5-20, the pressure of the absorption tower is 3-10 KPaG, and the temperature of the top of the absorption tower is 10-20 ℃.
15. The process for treating styrene storage tank tail gas according to claim 14, wherein the filler is at least one of raschig ring type, spiral ring type and wire mesh type; the number of the tower plates is 7-15; the pressure of the absorption tower is 5-8 KPaG; the temperature of the top of the absorption tower is 12-15 ℃.
16. The process for treating styrene storage tank tail gas according to claim 15, wherein the filler type is raschig ring type.
17. The process for treating tail gas of a styrene storage tank according to claim 1, wherein the separation tower is a plate tower with the number of plates being 3-25; the operating pressure of the separation tower is 30-90 KPaA; the reflux ratio is 1-10; the temperature of the tower kettle is 130-160 ℃.
18. The process for treating tail gas of a styrene storage tank according to claim 17, wherein the number of plates is 5 to 20; the operating pressure of the separation tower is 50-80 KPaA; the reflux ratio is 3-7; the temperature of the tower kettle is 140-150 ℃.
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