CN111036025A - Method and system for treating styrene pressure relief exhaust gas - Google Patents
Method and system for treating styrene pressure relief exhaust gas Download PDFInfo
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- CN111036025A CN111036025A CN201811185070.3A CN201811185070A CN111036025A CN 111036025 A CN111036025 A CN 111036025A CN 201811185070 A CN201811185070 A CN 201811185070A CN 111036025 A CN111036025 A CN 111036025A
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- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 title claims abstract description 282
- 238000000034 method Methods 0.000 title claims abstract description 43
- 239000007788 liquid Substances 0.000 claims abstract description 107
- 239000007789 gas Substances 0.000 claims description 130
- 238000000926 separation method Methods 0.000 claims description 28
- 238000007789 sealing Methods 0.000 claims description 23
- 239000003085 diluting agent Substances 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000009833 condensation Methods 0.000 claims description 15
- 230000005494 condensation Effects 0.000 claims description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 14
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical group CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 claims description 10
- 238000010926 purge Methods 0.000 claims description 10
- 239000011261 inert gas Substances 0.000 claims description 9
- 239000002826 coolant Substances 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 6
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 4
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 2
- -1 methylphenyl alcohol Chemical compound 0.000 claims description 2
- 238000004891 communication Methods 0.000 claims 3
- 238000011084 recovery Methods 0.000 abstract description 8
- 230000002159 abnormal effect Effects 0.000 abstract description 5
- 238000006116 polymerization reaction Methods 0.000 description 9
- 239000012071 phase Substances 0.000 description 8
- 239000000498 cooling water Substances 0.000 description 6
- 238000013461 design Methods 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 5
- 239000002912 waste gas Substances 0.000 description 5
- 238000004064 recycling Methods 0.000 description 4
- 239000000243 solution Substances 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 2
- 230000006837 decompression Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 125000003944 tolyl group Chemical group 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000010815 organic waste Substances 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 239000000057 synthetic resin Substances 0.000 description 1
- 229920003002 synthetic resin Polymers 0.000 description 1
- 239000005061 synthetic rubber Substances 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
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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
- B01D53/002—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
- B01D2257/00—Components to be removed
- B01D2257/70—Organic compounds not provided for in groups B01D2257/00 - B01D2257/602
- B01D2257/702—Hydrocarbons
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- Engineering & Computer Science (AREA)
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- Treating Waste Gases (AREA)
Abstract
The present disclosure relates to a method and system for treating styrene pressure relief vent gas. The method comprises the following steps: leading the styrene pressure-relief exhaust gas to flow into an exhaust pipe, and then condensing and separating liquid to obtain styrene condensate and tail gas with styrene removed; leading the tail gas without styrene to pass through a liquid seal device and then enter a tail gas treatment device; the styrene pressure relief exhaust gas is gas containing styrene and exhausted through a safety valve, the volume content of the styrene in the styrene pressure relief exhaust gas is 50-100%, and the pressure of the styrene pressure relief exhaust gas is 0.02-0.2 MPa. The method and the system can maintain the back pressure of the system in the styrene pressure relief exhaust gas treatment process, thereby realizing the high-efficiency recovery of the styrene gas discharged by the safety valve under abnormal working conditions, leading the recovered discharged tail gas to meet the requirements of a conventional tail gas treatment device, eliminating potential safety hazards, ensuring the safety of the device and solving the problem of the direction of the styrene gas discharged by the safety valve in the existing device or a newly-built device.
Description
Technical Field
The present disclosure relates to a method and system for treating styrene pressure relief vent gas.
Background
Styrene is an important monomer for industrial synthetic resins, ion exchange resins, synthetic rubbers, and the like. The toxicity of styrene is moderate, and the styrene can cause pollution to water, soil and atmosphere. According to the regulation of GB31571-2015 discharge Standard for pollutants in petrochemical industry, waste gas containing volatile organic compounds discharged by production equipment through a safety valve under abnormal working conditions is connected to an organic waste gas recovery or treatment device, and the discharge limit of styrene in the waste gas is regulated to be 50mg/m 3. Since 1/7/2015, new enterprises are required to implement the standard. Therefore, the styrene gas discharged from the safety valve should be connected to a waste gas recovery or treatment device.
Styrene readily undergoes self-polymerization under high temperature conditions. According to the regulation requirement of clause 5.3.1 b in SH3009-2013 petrochemical engineering combustible gas discharge system design Specification, combustible gas which is easy to polymerize and has adverse effect on the passing capacity of a discharge system is not discharged into a whole plant combustible gas discharge system. The long-term small amount of polymerization of styrene has the hidden nature and is difficult to discover, and in case the improper operating mode appears, the relief valve discharges, and the torch system discharge capacity is not enough, and the consequence is difficult to estimate. Therefore, the styrene gas discharged from the safety valve in the device cannot directly enter a flare system of the whole plant.
At present, the styrene gas discharged by a safety valve is treated by an operating production device mostly by directly discharging to the atmosphere through a safety position, and does not directly enter a whole-plant combustible gas discharge system. The aim of the treatment method is mainly to avoid potential hazards caused by polymerization of styrene, and the basic principle is to preferentially ensure the safety of the device and meet the requirement of environmental protection as far as possible. But the treatment method does not meet the standard specification at present, and has huge potential safety hazard to the ecological environment.
The styrene gas discharge method for treating the discharge of the safety valve, which can ensure the safety of the device and meet the standard specification, has few reports in documents and patents. Many methods of treating styrene gas are poorly suited to treating styrene gas discharged from production facilities through safety valves during accident conditions. Under abnormal working conditions, the styrene gas discharged by the safety valve has a technical problem in the direction of the styrene gas.
Disclosure of Invention
It is an object of the present disclosure to provide a method and system for treating styrene pressure relief vent gas that is capable of recycling styrene from the exhaust gas discharged from a safety valve.
In order to achieve the above object, a first aspect of the present disclosure provides a method of treating styrene pressure relief vent gas, the method comprising: leading the styrene pressure-relief exhaust gas to flow into an exhaust pipe, and then condensing and separating liquid to obtain styrene condensate and tail gas with styrene removed; enabling the tail gas subjected to styrene removal to pass through a liquid seal device and then enter a tail gas treatment device; the styrene pressure relief exhaust gas is gas containing styrene and exhausted through a safety valve, the volume content of the styrene in the styrene pressure relief exhaust gas is 50-100%, and the pressure of the styrene pressure relief exhaust gas is 0.02-0.2 MPa.
Optionally, the method comprises: enabling the styrene pressure-relief exhaust gas to flow in the exhaust pipe under the blowing of nitrogen gas flow to enter a condensing device for condensation to obtain condensed materials, and then enabling all the condensed materials to enter a liquid separating device for liquid separation; the condensation temperature is 40-150 ℃.
Optionally, the method further comprises adding a diluent to the styrene condensate, wherein the weight ratio of the diluent to the styrene condensate is (0.05-0.5): 1, the diluent is ethylbenzene, water or methylphenyl alcohol, or a combination of two or three thereof.
Optionally, the volume content of styrene in the tail gas after styrene removal is less than 6%.
Optionally, a plurality of rupture discs are arranged in the discharge pipe, and the rupture discs are different in burst pressure and are arranged in parallel.
A second aspect of the present disclosure provides a system for treating styrene pressure relief vent gas using the method of the first aspect of the present disclosure, the system comprising; the discharge pipe, the condensing device, the liquid separating device, the liquid sealing device and the tail gas treatment device; the first end of the discharge pipe is used for being communicated with the safety valve, the second end of the discharge pipe is communicated with the inlet of the condensing device, the liquid outlet of the condensing device is communicated with the inlet of the liquid dividing device, and the gas outlet of the liquid dividing device is communicated with the inlet of the tail gas treatment device through the liquid sealing device.
Optionally, an inert gas purging device is arranged in the discharge pipe, and the inert gas purging device is close to the first end of the discharge pipe; the inert gas purging device comprises a flow-limiting orifice plate or a self-operated regulating valve.
Optionally, the condensing device comprises a shell-and-tube condenser, a tube-side inlet of the shell-and-tube condenser is communicated with the second end of the discharge pipe, a tube-side outlet of the shell-and-tube condenser is communicated with an inlet of the liquid separating device, and a shell-side inlet of the shell-and-tube condenser is communicated with a cooling medium; and a non-condensable gas outlet of the condensing device is communicated with an inlet of the tail gas treatment device.
Optionally, the liquid seal device includes a liquid seal tank, the liquid seal tank is provided with an inlet pipe, one end of the inlet pipe is communicated with the gas outlet of the liquid separation device, the other end of the inlet pipe extends to the position below the liquid seal liquid level line, and the outlet of the liquid seal tank is communicated with the inlet of the tail gas treatment device.
Optionally, the liquid separating device comprises a liquid separating tank, and a cooling coil is arranged outside a tank body of the liquid separating tank; the liquid separation tank is also provided with a diluent pipeline communicated with the interior of the tank body.
Through the technical scheme, the method and the system can maintain the back pressure of the system in the styrene pressure relief exhaust gas treatment process by arranging the liquid seal device at the tail end of the treatment system, realize the high-efficiency recovery of the styrene gas discharged by the safety valve under the abnormal working condition, enable the recovered discharged tail gas to meet the requirements of a conventional tail gas treatment device, eliminate potential safety hazards, ensure the safety of the device and solve the problem of the destination of the styrene gas discharged by the safety valve in the existing device or a newly-built device.
Additional features and advantages of the disclosure will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:
FIG. 1 is a process flow diagram of a method of treating styrene blowdown vent gas of the present disclosure.
Description of the reference numerals
1 condenser 2 liquid separating tank
3 divide liquid jar 4 water seal jars of delivery pump
5 discharge pipe 6 low pressure torch
Detailed Description
The following detailed description of specific embodiments of the present disclosure is provided in connection with the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present disclosure, are given by way of illustration and explanation only, not limitation.
In the present disclosure, unless otherwise stated, the use of directional words such as "up" and "down" generally refers to the up and down of the device in normal use, and specifically refers to the orientation of the drawing in fig. 1. The "inner and outer" are with respect to the outline of the device itself.
A first aspect of the present disclosure provides a method of treating styrene pressure relief vent gas, the method comprising: leading the styrene pressure-relief exhaust gas to flow into an exhaust pipe, and then condensing and separating liquid to obtain styrene condensate and tail gas with styrene removed; leading the tail gas without styrene to pass through a liquid seal device and then enter a tail gas treatment device; the styrene pressure relief exhaust gas is gas containing styrene and exhausted through a safety valve, the volume content of the styrene in the styrene pressure relief exhaust gas is 50-100%, and the pressure of the styrene pressure relief exhaust gas is 0.02-0.2 MPa.
According to the method and the system, the liquid seal device is arranged at the tail end of the treatment system, so that the backpressure of the system in the treatment process of the styrene pressure relief exhaust gas can be maintained, the styrene gas discharged by the safety valve under the abnormal working condition is efficiently recovered, the recovered exhaust tail gas reaches the requirement of the inlet of the conventional tail gas treatment device, and the potential safety hazard is eliminated.
Safety valves are well known in the art in the sense of this disclosure, and the process of this disclosure can treat styrene blowdown vent gas exiting one or more safety valves. The plurality of safety valves may be respectively communicated to the exhaust pipes to respectively discharge the styrene pressure-relief exhaust gas discharged from the plurality of safety valves into the same exhaust pipe for processing, so as to control the back pressure of the system through the exhaust pipe.
According to the present disclosure, the safety valve trips to vent the styrene pressure relief vent in the event of an overpressure in the device, and no gas is vented from the safety valve during normal operation of the device. In one embodiment of the present disclosure, to maintain the pressure of the vent pipe system, nitrogen may be purged in the vent pipe to maintain the pressure, and in the case of normal operation of the production plant, nitrogen may be continuously purged in the vent pipe to maintain the pressure of the tail gas treatment plant.
In an embodiment of this disclosure, in order to maintain the exhaust pipe pressure, can make styrene pressure release exhaust flow and get into condensing equipment and condense in the exhaust pipe under nitrogen gas air current sweeps, nitrogen gas sweeps still is favorable to the interior styrene exhaust of exhaust pipe to get into condensing equipment simultaneously, obtains the material after the condensation, is convenient for separate styrene condensate, prevents that styrene from remaining in the exhaust pipe, then makes the whole partial liquid devices that get into of material after the condensation divide the liquid. The means for condensing and separating the liquid may be conventional in the art, for example the condensing means may comprise a condenser, such as a shell and tube condenser; the liquid separation device may comprise a liquid separation tank.
Further, the circulating cooling water can be used as a cooling medium of the shell-and-tube condenser, and preferably, the circulating cooling water can be secondary circulating cooling water of other cooling water heat exchangers in the device, so that additional circulating water consumption is avoided, and the energy consumption of the system is reduced.
Further, in order to ensure that the styrene is fully condensed and prevent the content of the styrene in the tail gas from exceeding the standard, preferably, the design capacity of the condenser can be that the styrene gas phase in the discharged waste gas is fully condensed or mostly condensed, and preferably, the styrene gas phase is fully condensed; further preferably, the condensation temperature may be 40 to 150 ℃, more preferably 60 to 100 ℃.
In an embodiment of the present disclosure, a cooling coil may be disposed outside the liquid separation tank to control the temperature rise caused by self-polymerization of styrene in the liquid separation tank.
In order to prevent the self-polymerization runaway of the styrene condensate, the method can further comprise adding a diluent into the styrene condensate, and for example, a diluent pipeline can be arranged outside the liquid separation tank.
The dosage of the diluent can be changed in a large range, and preferably, the weight ratio of the diluent to the styrene condensate can be (0.05-0.5): 1, more preferably (0.1 to 0.2): the diluent may be a conventional diluent which does not react with styrene and is easily separated in the recovery process, preferably ethylbenzene, water or methyl phenyl alcohol, or a combination of two or three thereof, such as an ethylbenzene/methyl phenyl alcohol solution. Within the above preferred range of the type and amount of the diluent, the diluent can function to lower the temperature of the styrene condensate, dilute the styrene condensate and absorb free radicals, thereby preventing the styrene in the condensate from self-polymerization due to excessive concentration or temperature. The styrene condensate in the separating tank can be sent out of the device for recycling.
According to this disclosure, the tail gas of desorption styrene passes through liquid encapsulation back and can keep the discharge pipe system internal pressure at row tail gas processing apparatus, prevents to discharge the operating mode that negative pressure appears in the condensation process, prevents for example the back-off of torch gas in the tail gas device simultaneously.
Further, in the embodiment of liquid separation using a liquid separation device such as a liquid separation tank, a separate liquid sealing device such as a water sealing tank may be provided at the gas phase outlet of the liquid separation tank, and the pressure in the discharge pipe system is maintained by controlling the water sealing height of the water sealing tank, which may be of a type conventional in the art.
The styrene content in the styrene pressure relief exhaust gas treated by the method is greatly reduced, and the styrene pressure relief exhaust gas can be discharged into a conventional tail gas treatment device, and is discharged and treated by the conventional tail gas treatment device without arranging an independent treatment device; for example, the tail gas treatment device can be a low-pressure torch, and the exhaust gas treated by the tail gas treatment device can reach the qualified emission of the national standard.
According to the present disclosure, after condensation and liquid separation treatment, the styrene content in the tail gas from which styrene is removed is low, which can meet the requirements of conventional tail gas treatment devices, and the volume content of styrene in the tail gas from which styrene is removed is, for example, less than 6%, and further can be 1-5%.
In one embodiment of the present disclosure, in order to protect the equipment, a rupture disk may be provided in the discharge pipe, and preferably, a plurality of rupture disks, preferably having different burst pressures and being arranged in parallel, may be provided in the discharge pipe. In this embodiment, if the back path of the discharge system deviates from the design, such as the system flux cannot reach the design value due to blockage, or the system discharge amount exceeds the design value, the back pressure of the system will increase, i.e. the pressure in the discharge pipe increases, while the constant pressure of the safety valve of the styrene system is generally low, and the back pressure increases to a certain extent, which will affect the discharge amount of the safety valve and further affect the upstream equipment protected by the safety valve.
A second aspect of the present disclosure provides a system for treating styrene pressure relief vent gas using the method of the first aspect of the present disclosure, the system comprising; the device comprises a discharge pipe, a condensing device, a liquid separating device, a liquid sealing device and a tail gas treatment device; the first end of the discharge pipe is used for being communicated with the safety valve, the second end of the discharge pipe is communicated with the inlet of the condensing device, the liquid outlet of the condensing device is communicated with the inlet of the liquid separating device, and the gas outlet of the liquid separating device is communicated with the inlet of the tail gas treatment device through the liquid sealing device.
In one embodiment of the present disclosure, in order to maintain the system pressure, an inert gas purging device may be provided within the discharge pipe, preferably near the first end of the discharge pipe, i.e., near the end of the safety valve; the inert gas purge means may be of a type conventional in the art and preferably includes a restricted orifice or self-operated regulator valve to control the flow and pressure of the inert gas.
In a specific embodiment of the present disclosure, in order to improve the condensation effect of the styrene pressure-relief exhaust gas and reduce the content of styrene in the exhaust tail gas, the condensing device may include a shell-and-tube condenser, a tube-side inlet of the shell-and-tube condenser may be communicated with the second end of the exhaust pipe, a tube-side outlet may be communicated with an inlet of the liquid separating device, and a shell-side inlet of the shell-and-tube condenser may be communicated with the cooling medium; the non-condensable gas outlet of the condensing device can be communicated with the inlet of the tail gas treatment device. The condenser is designed to fully condense or largely condense the styrene gas phase in the exhaust gas, preferably the styrene gas phase.
According to the present disclosure, the liquid sealing device may be of a conventional kind in the art for preventing gas from flowing backwards when negative pressure occurs during the discharge condensation process, and the liquid sealing device may include, for example, a liquid sealing tank, in one embodiment of the present disclosure, the liquid sealing tank may be provided with an inlet pipe, one end of the inlet pipe may be communicated with the gas outlet of the liquid separating device, and the other end may extend to below a liquid sealing liquid level line of the liquid sealing device and maintain a certain liquid sealing height to maintain the pressure in the discharge pipe system, and the system back pressure in the discharge pipe may be adjusted by adjusting the liquid sealing height; furthermore, the vertical section of the inlet pipe above the liquid seal liquid level can also have a certain height so as to maintain a certain safe height and prevent the liquid seal suck-back phenomenon caused by the negative pressure generated by excessive condensation; the gas outlet of the liquid seal tank can be communicated with the inlet of the tail gas treatment device.
Further, the liquid separating device can comprise a liquid separating tank, and in order to prevent the temperature rise of styrene polymerization in the liquid separating tank, a cooling coil can be arranged outside the tank body of the liquid separating tank.
Furthermore, in order to dilute and cool the styrene condensate and prevent self-polymerization, the liquid separating tank can be further provided with a diluent pipeline communicated with the interior of the liquid separating tank body, so that the diluent is fed into the liquid separating tank to dilute and cool the styrene condensate.
The present disclosure is illustrated below by examples, but the present disclosure is not limited thereto.
Examples
The styrene pressure relief exhaust gas in this example is a styrene gas material discharged by a plurality of safety valves of an upstream production device, wherein the volume content of styrene is 99%, and the pressure is 0.05 MPa. The safety valve discharges and is connected with the device and the method for treating the styrene decompression exhaust gas disclosed by the invention. The capacity design of the device and the method for treating the styrene decompression exhaust gas is carried out by taking a safety valve with the maximum styrene emission as a reference. The safety valve having the maximum styrene emission is named safety valve a.
As shown in fig. 1, the system includes a condenser 1, a separatory tank 2, a separatory tank transfer pump 3, and a water-sealed tank 4. The safety valve A jumps under the accident condition, discharged styrene gas enters the condenser 1 from the discharge pipe 5, and exchanges heat with a cooling medium of the condenser 1, and the styrene gas is liquefied and then enters the liquid separation tank 2. The styrene condensate in the liquid separation tank 2 is sent out by a liquid separation tank conveying pump 3 for recycling. The tail gas in the liquid separation tank 2 is discharged to a low-pressure torch 6 through a water seal tank 4.
The first end of the above-mentioned discharge pipe 5 (the end near the safety valve) is provided with a continuous nitrogen purge to maintain the system pressure. The flow and pressure of the nitrogen are controlled by a flow-limiting orifice plate. With the production plant operating normally, a nitrogen purge is continued to maintain the pressure of the styrene flare waste gas discharge recovery system.
Two stages of rupture discs are arranged in parallel before the safety valve of the discharge pipe 5 enters the mouth of the condenser 1. The setting of the burst pressure of the first-stage rupture disk is determined by the constant pressure of the safety valve A and the back pressure of the low-pressure torch outside the safety valve A. The burst pressure of the second-stage rupture disk is not more than 5% of that of the first stage.
The condenser 1 is a shell-and-tube condenser, styrene gas is arranged on the tube side, cooling medium is arranged on the shell side, the cooling medium adopts secondary circulating cooling water of other cooling water heat exchangers in the device, the condensation temperature is 70 ℃, and the styrene gas phase is fully condensed. And calculating the styrene equilibrium temperature under the pressure condition according to the discharge pressure of the safety valve A. The condenser 1 is designed to condense the styrene gas phase in the exhaust gas completely, again depending on the equilibrium temperature.
The styrene is liquefied and then enters the liquid separation tank 2. A cooling coil is arranged outside the liquid separation tank 2, and an ethylbenzene solution is injected into the liquid separation tank 2 to dilute the styrene in the tank, so that temperature runaway of the styrene is prevented. The liquid-phase styrene in the liquid separation tank 2 is sent out by a liquid separation tank delivery pump 3 for recycling. And a circulating cooling line returning to the liquid separation tank 2 is arranged at the outlet of the liquid separation tank conveying pump 3.
And the gas phase tail gas in the liquid separation tank 2 is discharged to an outdoor low-pressure flare header pipe through a water seal tank 4. The water seal tank 4 is provided with an industrial water injection pipeline, and the water seal height of 500mm is maintained. While the vertical section of the inlet line of the water-sealed tank 4 is 5 m. At the discharge initial stage of the safety valve, a certain emptying amount is needed to break the water seal, and the water seal enters the low-pressure torch system through the water seal tank 4 so as to discharge non-condensable gas to maintain the lower back pressure of the system. The tail gas discharged by the safety valve after condensation is sent into a low-pressure torch 6, and the non-condensable gas in the system is also sent into the low-pressure torch 6.
The volume content of styrene in the tail gas entering the low-pressure flare system for removing styrene is 3 percent.
The method and the system disclosed by the invention adopt a condensation method to carry out the liquefaction recovery treatment on the styrene pressure relief discharge gas, the tail gas after the recovery treatment is discharged to the low-pressure flare header pipe, and meanwhile, a plurality of reliable safety means are adopted to control the styrene polymerization and maintain the back pressure of the system, so that the normal operation of the flare system is ensured. The invention not only meets the requirement of environmental protection, but also ensures the safety of the device, and solves the problem of the direction of the styrene gas discharged by pressure relief in the existing device or a newly-built device.
The preferred embodiments of the present disclosure are described in detail with reference to the accompanying drawings, however, the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present disclosure within the technical idea of the present disclosure, and these simple modifications all belong to the protection scope of the present disclosure.
It should be noted that the various features described in the above embodiments may be combined in any suitable manner without departing from the scope of the invention. In order to avoid unnecessary repetition, various possible combinations will not be separately described in this disclosure.
In addition, any combination of various embodiments of the present disclosure may be made, and the same should be considered as the disclosure of the present disclosure, as long as it does not depart from the spirit of the present disclosure.
Claims (10)
1. A method of treating styrene blowdown offgas, the method comprising: leading the styrene pressure-relief exhaust gas to flow into an exhaust pipe, and then condensing and separating liquid to obtain styrene condensate and tail gas with styrene removed; enabling the tail gas subjected to styrene removal to pass through a liquid seal device and then enter a tail gas treatment device;
the styrene pressure relief exhaust gas is gas containing styrene and exhausted through a safety valve, the volume content of the styrene in the styrene pressure relief exhaust gas is 50-100%, and the pressure of the styrene pressure relief exhaust gas is 0.02-0.2 MPa.
2. The method of claim 1, wherein the method comprises: enabling the styrene pressure-relief exhaust gas to flow in the exhaust pipe under the blowing of nitrogen gas flow to enter a condensing device for condensation to obtain condensed materials, and then enabling all the condensed materials to enter a liquid separating device for liquid separation; the condensation temperature is 40-150 ℃.
3. The method according to claim 1, further comprising adding a diluent to the styrene condensate in a weight ratio of (0.05-0.5): 1, the diluent is ethylbenzene, water or methylphenyl alcohol, or a combination of two or three thereof.
4. The process of claim 1, wherein the styrene-depleted tail gas has a styrene content of less than 6% by volume.
5. The method of claim 1, wherein a plurality of rupture discs are disposed within the discharge tube, the rupture discs having different burst pressures and being arranged in parallel.
6. A system for treating styrene blowdown exhaust gas using the method of any one of claims 1 to 5, the system comprising; the discharge pipe, the condensing device, the liquid separating device, the liquid sealing device and the tail gas treatment device;
the first end of the discharge pipe is used for being communicated with the safety valve, the second end of the discharge pipe is communicated with the inlet of the condensing device, the liquid outlet of the condensing device is communicated with the inlet of the liquid dividing device, and the gas outlet of the liquid dividing device is communicated with the inlet of the tail gas treatment device through the liquid sealing device.
7. The system of claim 6, wherein an inert gas purge is disposed within the discharge tube, the inert gas purge being proximate the first end of the discharge tube; the inert gas purging device comprises a flow-limiting orifice plate or a self-operated regulating valve.
8. The system of claim 6, wherein the condensing device comprises a shell-and-tube condenser, a tube-side inlet of the shell-and-tube condenser is in communication with the second end of the discharge tube, a tube-side outlet is in communication with an inlet of the liquid separation device, and a shell-side inlet of the shell-and-tube condenser is in communication with a cooling medium; and a non-condensable gas outlet of the condensing device is communicated with an inlet of the tail gas treatment device.
9. The system according to claim 6, wherein the liquid sealing device comprises a liquid sealing tank, the liquid sealing tank is provided with an inlet pipe, one end of the inlet pipe is communicated with the gas outlet of the liquid separating device, the other end of the inlet pipe extends to the position below a liquid sealing liquid level line, and the outlet of the liquid sealing tank is communicated with the inlet of the tail gas treatment device.
10. The system according to claim 6, wherein the liquid separating device comprises a liquid separating tank, and a cooling coil is arranged outside a tank body of the liquid separating tank;
the liquid separation tank is also provided with a diluent pipeline communicated with the interior of the tank body.
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