CN112495071A - VC polymerization tail gas recovery system - Google Patents
VC polymerization tail gas recovery system Download PDFInfo
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- CN112495071A CN112495071A CN202011518765.6A CN202011518765A CN112495071A CN 112495071 A CN112495071 A CN 112495071A CN 202011518765 A CN202011518765 A CN 202011518765A CN 112495071 A CN112495071 A CN 112495071A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/56—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours with multiple filtering elements, characterised by their mutual disposition
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/66—Regeneration of the filtering material or filter elements inside the filter
- B01D46/69—Regeneration of the filtering material or filter elements inside the filter by means acting on the cake side without movement with respect to the filter elements, e.g. fixed nozzles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D46/00—Filters or filtering processes specially modified for separating dispersed particles from gases or vapours
- B01D46/66—Regeneration of the filtering material or filter elements inside the filter
- B01D46/70—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter
- B01D46/72—Regeneration of the filtering material or filter elements inside the filter by acting counter-currently on the filtering surface, e.g. by flushing on the non-cake side of the filter with backwash arms, shoes or nozzles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
- B01D5/0057—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes
- B01D5/0072—Condensation of vapours; Recovering volatile solvents by condensation in combination with other processes with filtration
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D5/00—Condensation of vapours; Recovering volatile solvents by condensation
- B01D5/0078—Condensation of vapours; Recovering volatile solvents by condensation characterised by auxiliary systems or arrangements
- B01D5/009—Collecting, removing and/or treatment of the condensate
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Abstract
The invention belongs to the fields of energy conservation, environmental protection, emission reduction and quality improvement of PVC powder, and particularly relates to a VC polymerization tail gas recovery system. The VC polymerization tail gas recovery system comprises a recovered gas buffer tank, two parallel recovery filters, a rotary blanking valve, at least one discharge centrifugal pump, at least one compressor, a desalted water pipeline, a stripping pipeline, an evaporative condenser, a monomer buffer tank, at least one delivery pump, at least one security tank, a regenerated gas heat exchanger and the like. The content of VC in the discharged noncondensable gas is lower than 8mg/m3Meets the 10mg/m specified in the discharge Standard of Industrial pollutants for caustic soda and polyvinyl chloride GB15581-20163(ii) a When the recycled VC is in the original polymerization system, all indexes of the PVC resin are superior to those of PVC produced by the original process, and the indexes of 'fish eyes' are reduced by 6-10/400 cm2(ii) a According to a 20 ten thousand ton PVC installation each yearExample calculation, ice machine load reduction was about 7.5 x 105Kcal/h, saving 858 tons of standard coal each year; therefore, the technology is advanced, reliable and safe in process, product quality and safety.
Description
Technical Field
The invention belongs to the fields of energy conservation, environmental protection, emission reduction and quality improvement of PVC powder, and particularly relates to a VC polymerization tail gas recovery system.
Background
The main methods for producing PVC by VC polymerization at present comprise a suspension polymerization method, an emulsion polymerization method and a bulk polymerization method, wherein the suspension polymerization method is mainly used and accounts for about 80 percent of the total yield of PVC. VC monomer is subjected to polymerization reaction under various auxiliaries, and when the monomer conversion rate reaches 80-90%, unreacted monomer needs to be recovered; secondly, in the suspension method and the emulsion method, the slurry stripping steam contains up to 15000ppmVC, VC in wastewater stripping steam and VC in overhaul replacement steam are required to be recovered; VC needs to be recovered in a degassing and homogenizing system in bulk polymerization; by taking a suspension polymerization method as an example for illustration, the recovered gas powder is not filtered in the prior art, is compressed by a water ring vacuum pump and then enters a two-section shell-and-tube heat exchanger for condensing VC, and finally enters a recovered monomer storage tank for standby; the vacuum water ring pump drains VC and powder, reclaim VC and take the powder; secondly, in a certain PVC production factory in China, tail gases of different polymerization methods enter the same storage device, so that the serious adhesion of the bulk production is caused; unqualified indexes such as product impurities and fish eyes are caused; secondly, the content of VC in the tail gas noncondensable gas recovered by the prior art is higher, and if VC is not completely recovered, resources are wasted, air pollution is caused, and human carcinogenesis is caused.
Disclosure of Invention
In order to solve the defects of the prior art, the invention provides a VC polymerization tail gas recovery system. The system can be used for recovering high-quality VC from tail gas generated by suspension polymerization, bulk polymerization and emulsion polymerization, and the recovered VC can be mixed and stored without affecting the quality of PVC; the process adopts intermediate product gas as filter material cleaning and filter material conveying power, does not attract new back blowing gas, and takes VC gas phase conveying powder or centrifugal pump conveying slurry as power to prevent new impurities from appearing in recovered VC; finally, the VC in the VC polymerization tail gas is recovered to the maximum extent. The tail gas emission is reduced, the cold energy consumption of an ice machine is reduced, the VC polymerization production cost is reduced, and the PVC high yield and quality are improved.
The technical scheme provided by the invention is as follows:
the utility model provides a VC polymerization tail gas recovery system, includes recovery gas buffer tank, at least one recovery filter, rotatory unloading valve, at least one ejection of compact centrifugal pump, at least one compressor, desalination pipeline and strip pipeline, the recovery gas buffer tank has first air inlet, first gas outlet, first back flush mouth, first feed opening and first feed back mouth, the recovery filter has second air inlet, second gas outlet, second back flush mouth and second feed opening, each the compressor has third air inlet and third gas outlet, wherein:
the first air outlet is respectively communicated with the second air inlets, the second air outlets are respectively communicated with the third air inlets, the third air outlets are respectively communicated with the second back flushing ports and the first back flushing ports, the third air outlets are also sequentially communicated with an evaporative condenser and a monomer buffer tank, and the monomer buffer tank is respectively communicated with at least one conveying pump;
the desalination water pipeline is respectively communicated with the first back flushing port and each second back flushing port, the first discharging port is respectively communicated with each discharging centrifugal pump and the rotary discharging valve, each second discharging port is respectively communicated with the first returning port and the rotary discharging valve, and each discharging centrifugal pump and the rotary discharging valve are respectively communicated with the stripping pipeline.
Based on the technical scheme, the system can treat powder steam stripping gas and polymerization recovery gas of a bulk method and can also treat slurry steam stripping gas, wastewater steam stripping gas and polymerization recovery gas of a suspension method.
The pipeline of the third air outlet which is respectively communicated with the second back washing port and the first back washing port can be provided with a pulse electromagnetic valve.
Further:
the first discharging port is respectively communicated with each discharging centrifugal pump or the rotary discharging valve through a first three-way switching valve;
and each second feed opening is respectively communicated with the first return opening or the rotary feed valve through a second three-way switching valve.
Based on the technical scheme:
the system can process slurry stripping gas, waste water stripping gas and polymerization recovery gas of a suspension method;
the system can process powder stripping gas and polymerization recycle gas of a bulk method by switching the first three-way switching valve to the recycle gas buffer tank to be communicated with the rotary discharge valve and switching the second three-way switching valve to the recycle filter to be communicated with the rotary discharge valve.
Furthermore, the desalination water pipeline is sequentially communicated with a first switch valve and one end of a back washing pipeline, the third air outlet is sequentially communicated with a second switch valve and the other end of the back washing pipeline, and the back washing pipeline is respectively communicated with the first back washing port and each second back washing port.
Based on the technical scheme, the body method and the suspension method can share one section of backwashing pipeline. The first switch valve is opened and the second switch valve is closed, and the suspension method can be used. The first switch valve is closed and the second switch valve is opened, and the method can be used for the body method.
Further, the system still includes safety tank and regeneration gas heat exchanger, the high temperature gas outlet intercommunication of regeneration gas heat exchanger safety tank, evaporative condenser has fourth air inlet, fourth gas outlet, fourth inlet and fourth liquid outlet, the third gas outlet intercommunication the fourth air inlet, the fourth liquid outlet intercommunication the monomer buffer tank, desalination pipeline intercommunication the fourth inlet, the fourth gas outlet communicates respectively through third three-way switch valve the third air inlet with safety tank, safety tank rethread fourth switch valve communicates respectively third air inlet or atmospheric line.
Further, the monomer buffer tank is provided with an exhaust port which is communicated with the third air inlet. The communication pipeline can be provided with a one-way valve.
Based on the technical scheme, the system can further process the outlet gas of the evaporative condenser and the discharge of the monomer buffer tank.
Furthermore, the third air outlet is communicated with the third switch valve and the outlet of the rotary blanking valve in sequence. The communication pipeline can be provided with a one-way valve.
Based on above-mentioned technical scheme, can utilize the compressor to give vent to anger and promote rotatory unloading valve unloading.
Specifically, the recycle gas buffer tank includes the buffer tank body, the internal upper portion of buffer tank transversely is provided with the collection net, first air inlet first feed opening with first feed back mouth all is located the below of collection net, first gas outlet with first feed back mouth all is located the top of collection net.
Further, the buffer tank body is cylindrical, and the first air inlet is arranged along the tangential direction of the first air inlet.
Furthermore, a stirring device is arranged at the bottom of the buffer tank body.
Based on the technical scheme, the suspension method is facilitated to use.
Specifically, the recovery filter comprises a tank body, wherein a plurality of filter pipes with upper end openings and lower end closures are vertically arranged in the tank body, the upper end openings of the filter pipes penetrate through a fixed pattern plate and are fixedly connected with the fixed pattern plate, a back flushing pipe is fixedly arranged above the fixed pattern plate through a fixing frame, the back flushing pipe is provided with a plurality of nozzles, the nozzles are correspondingly arranged above the upper end openings of the filter pipes one by one, a second air inlet is communicated with the lower space of the tank body, a second air outlet is communicated with the upper space of the tank body, a second back flushing port is communicated with the back flushing pipe, and a second feed port is communicated with the bottom of the tank body.
Furthermore, the tank body is cylindrical, the filter pipes are arranged in a plurality of circles around the circumferential direction of the tank body, the radius of each circle of the filter pipes is gradually increased, and the filter pipes in the circles are uniformly arranged around the circumferential direction at intervals.
Based on the technical scheme, the back blowing and the suction can be efficiently carried out on each filter pipe.
Furthermore, the lower part of the tank body is in a half-gourd shape, and the diameter of the tank body is larger than that of the tank body.
Based on the technical scheme of the invention, the content of VC in discharged non-condensable gas is lower than 8mg/m3Meets the 10mg/m specified in the discharge Standard of Industrial pollutants for caustic soda and polyvinyl chloride GB15581-20163(ii) a The recycled VC is recycled in the original polymerization system under the same condition, and then the recycled VC is taken as an example of a suspension method, each index of the PVC resin is superior to that of the PVC produced by the original process, and the recycled VC has obvious advantages particularly on the index of 'fish eyes', and is reduced by 6-10/400 cm2(ii) a In an enterprise factory area simultaneously having a bulk polymerization method, an emulsion method and a suspension polymerization method, the recovered VC can be mixed and stored, so that the problem that the recovered VC is stuck to a kettle due to the recycling of emulsion polymerization gas through bulk polymerization is solved, and the one-time engineering investment for constructing a storage tank and a gas holder respectively due to the storage is reduced; secondly, the technology solves the potential safety hazard caused by the fact that VC enters a chilled water system due to the leakage of the heat exchanger tubes in the traditional technology; the technology economically calculates by taking 20 ten thousand tons of PVC device as an example, the load of the ice machine is reduced by about 7.5 x 105Kcal/h, saving 858 tons of standard coal each year; therefore, the technology is advanced, reliable and safe in process, product quality and safety.
Drawings
FIG. 1 is a system diagram of a VC polymerization tail gas recovery system provided by the present invention.
FIG. 2 is a schematic structural diagram of a VC polymerization tail gas recovery system provided by the present invention.
FIG. 3 is a schematic structural diagram of a recovery filter of the VC polymerization tail gas recovery system provided by the invention.
FIG. 4 is a top view AA of the recovery filter.
In fig. 1, 2, 3, and 4, the structures represented by the reference numerals are listed below:
1. the system comprises a recycle gas buffer tank, 2, a recycle filter, 3, a rotary blanking valve, 4, a discharge centrifugal pump, 5, a compressor, 6, a desalted water pipeline, 7, a stripping pipeline, 8, an evaporative condenser, 9, a monomer buffer tank, 10, a delivery pump, 11, a safety tank, 12, a regeneration gas heat exchanger, 13, a first three-way switching valve, 14, a second three-way switching valve, 15, a third three-way switching valve, 16, a fourth switching valve, 17, a first switching valve, 18, a second switching valve, 19 and a third switching valve.
Detailed Description
The principles and features of this invention are described below in conjunction with examples which are set forth to illustrate, but are not to be construed to limit the scope of the invention.
In a specific embodiment, as shown in fig. 1 and 2, the VC polymerization tail gas recovery system comprises a recovered gas buffer tank 1, two recovery filters 2 connected in parallel, a rotary blanking valve 3, at least one discharging centrifugal pump 4, at least one compressor 5, a desalted water pipeline 6, a stripping pipeline 7, an evaporative condenser 8, a monomer buffer tank 9, at least one transfer pump 10, at least one guard tank 11, and a regeneration gas heat exchanger 12.
In one embodiment, the average particle size of the PVC particles is 160 μm, and the distribution is 3-63 μm to 1%, 88-74 μm to 4%, 97-88 μm to 1%, 105-97 μm to 9%, 125-; secondly, bottom stirring is arranged in a recycle gas buffer tank, and the slurry is condensed to prevent sedimentation due to partial steam feeding of the stripping steam of the slurry; (the body method does not need to be provided with bottom stirring, flushing water and a discharge pump, the discharge mode is changed into a rotary discharge valve, product gas is fed to a body degassing system by using a compressor to recover powder, and the intermittent operation) the pressure grade of a recovered gas buffer tank is set to be 2.5MPa, the buffer tank body and a trapping net are made of 316L, and a safety valve, a liquid level meter and liquid level remote transmission can be arranged on the top of the tank; the discharge centrifugal pump adopts an open impeller centrifugal pump, is operated intermittently, prevents the discharge pump from being damaged by plastifying matters, and is made of 316 basically.
In one embodiment, the first discharging port is respectively communicated with each discharging centrifugal pump 4 or the rotary discharging valve 3 through a first three-way switching valve 13; and each second feed opening is respectively communicated with the first return opening or the rotary feed valve 3 through a second three-way switching valve 14. Based on the technical scheme: the first three-way switching valve 13 is switched to the recovered gas buffer tank to be communicated with the discharge centrifugal pump, the second three-way switching valve 14 is switched to the recovered filter to be communicated with the recovered gas buffer tank, and the system can treat slurry stripping gas, waste water stripping gas and polymerization recovered gas of a suspension method; the system can process the powder stripping gas and the polymerization recycle gas of the bulk method by switching the first three-way switching valve 13 to the recycle gas buffer tank to be communicated with the outlet rotary blanking valve and switching the second three-way switching valve 14 to be communicated with the recycle filter to be communicated with the rotary blanking valve.
In one implementation, the recovery filter is two parallel filters, the appearance of the recovery filter is in a gourd shape, and a filter structure is mainly formed by an annular back-blowing back-washing internal part (each spray head is over against a filter element, so that back-blowing or back-washing can be better performed, wherein a body is not provided with washing water), a filter element with the filtering precision of 3 mu m, a tangent air inlet, a safety valve and a material level meter, and is shown in figure 3;
the recovery filter can be provided with a pressure detection instrument, a switch valve and an electromagnetic pulse valve at an inlet and an outlet; the pressure difference at the inlet and the outlet is more than 200Pa, and the filter can be switched to another recovery filter to clean the filter screen at present;
the filter element is formed by winding an inner steel framework, an outer steel framework and a plurality of filter materials in the middle in a multi-layer mode, the end covers are made of stainless steel, the end parts of the filter element are prevented from being damaged by sealing pieces, steel supporting pieces are arranged on the inner side and the outer side, the filter element can be protected from being damaged under the condition of bidirectional airflow, the filtering efficiency is 99.99%, and the solid content of tail gas is lower than or equal to 0.5mg/m3For example, a stainless steel sintered felt filter element may be used. Secondly, the fine filtering system realizes the cleaning without opening the cover all the year round,the filter screen is not replaced in 3 years;
all the metal surfaces of the equipment which are contacted with the medium are subjected to electrolytic polishing treatment (including end socket girth welds and manhole covers), so that the roughness Ra of the inner surface of the filter is less than or equal to 0.05 mu m, and the roughness Ra of the surface of the internal parts is less than or equal to 0.1 mu m; polishing the inner wall of a powder blanking pipeline, wherein the included angle between the installation angle and the ground is not less than 60 degrees;
in one implementation, the rotary blanking valve is mainly used for uniformly blanking the powder in the filter to an air conveying system (the suspension method or the emulsion method is not provided with the rotary blanking valve and the air conveying system and is used for blanking to a recycling gas buffer tank).
In one implementation, two compressors are connected in parallel, a screw compressor is selected, so that higher compression ratio is convenient to provide, the outlet pressure of the compressor is not lower than 0.6MPa (G), and the pressure can liquefy vinyl chloride and separate the vinyl chloride from non-condensable gas when the outlet temperature of an evaporative condenser reaches 28 ℃.
In one embodiment, the evaporative condenser 8, the U-shaped blanking pipe, the body buffer tank 9, the delivery pump 10, the guard tank 11 and the regeneration gas heat exchanger 12 form an evaporative condensing system. The evaporative condenser 8 adopts the prior art and comprises a variable frequency motor, a tower body, a cooling coil, a circulating water pump, a water collecting tank, a noncondensable gas on-line analyzer, a pressure and temperature detecting instrument, a switch valve and the like.
In one embodiment, the evaporative condenser cooling coil adopts a dry air cooling section and a mixed air cooling section to mix and cool materials, the dry cooling section adopts an aluminum alloy finned tube, the wet section adopts a two-phase steel tube, and the dry and wet sections are hot dipped after being made into an integral coil; the condensation effect is achieved by using air under the condition of water-free operation in winter (0 ℃);
in one embodiment, the fans and the water pump are matched with motors which are explosion-proof motors, are arranged outdoors, are protected at the IP55 level and are protected at the dIII BT4 level, and meet the power supply requirement of an AC power supply of 380V/50 Hz. The fan blade is made of aluminum alloy, and the transmission form adopts a direct connection type (high transmission efficiency, energy conservation and maintenance-free property).
In one embodiment, the security tank is filled with a high-efficiency porous adsorption material, and the materials are filled at intervals in layers to ensure that tail gas uniformly passes through the adsorption material in the security tank; after VC in tail gas exceeds standard, the first stepVC is adsorbed at a time, and the VC content in the evacuated non-condensable gas is always ensured to be lower than 8mg/m3(ii) a The vent line of the safety tank can be conventionally installed on-line analytical instrument, and the VC content is equal to 8mg/m3The security jar is switched to another one, and the security jar with saturated adsorption is regenerated at the same time, and the regenerated gas adopts hot nitrogen with the temperature of not less than 0.5MPa (G)80-105 ℃ (the body method adopts 60-80 ℃).
As shown in figure 2, the compressor 5 can be connected in parallel by two compressor machines, the discharge centrifugal pump 4 can be connected in parallel by two sub-pumps, the security tank 11 can be connected in parallel by two sub-tanks, and the delivery pump 10 can be connected in parallel by two sub-pumps.
In one embodiment, as shown in fig. 1, 2, 3 and 4, the recycle gas buffer tank 1 has a first gas inlet, a first gas outlet, a first back flush port, a first feed port and a first return port, the recycle filter 2 has a second gas inlet, a second gas outlet, a second back flush port and a second feed port, each compressor 5 has a third gas inlet and a third gas outlet, and the evaporative condenser 8 has a fourth gas inlet, a fourth gas outlet, a fourth liquid inlet and a fourth liquid outlet.
The first air outlet is respectively communicated with the second air inlets, the second air outlets are respectively communicated with the third air inlets, the third air outlets are respectively communicated with the second back flushing ports and the first back flushing ports and are sequentially communicated with the evaporative condenser 8 and the monomer buffer tank 9, and the monomer buffer tank 9 is respectively communicated with at least one conveying pump 10.
The desalination water pipeline 6 is respectively communicated with the first back flushing port and each second back flushing port, the first discharging port is respectively communicated with each discharging centrifugal pump 4 and the rotary blanking valve 3, each second discharging port is respectively communicated with the first returning port and the rotary blanking valve 3, and each discharging centrifugal pump 4 and the rotary blanking valve 3 are respectively communicated with the stripping pipeline 7. Based on the system, the system can treat powder steam stripping gas and polymerization recovery gas of a bulk method, and can also treat slurry steam stripping gas, wastewater steam stripping gas and polymerization recovery gas of a suspension method.
The first discharging port is respectively communicated with each discharging centrifugal pump 4 or the rotary discharging valve 3 through a first three-way switching valve 13. And each second feed opening is respectively communicated with the first return opening or the rotary feed valve 3 through a second three-way switching valve 14. Based on this, switch first three-way diverter valve 13 to the recovery gas buffer tank and communicate the ejection of compact centrifugal pump to switch second three-way diverter valve 14 to the recovery filter and communicate the recovery gas buffer tank, the system can handle the thick liquids stripping gas of suspension method, waste water stripping gas and polymerization recovery gas. The system can process the powder stripping gas and the polymerization recycle gas of the bulk method by switching the first three-way switching valve 13 to the recycle gas buffer tank to be communicated with the outlet rotary blanking valve and switching the second three-way switching valve 14 to be communicated with the recycle filter to be communicated with the rotary blanking valve.
The desalination water pipeline 6 is sequentially communicated with a first switch valve 17 and one end of a back washing pipeline, and the third air outlet is sequentially communicated with a second switch valve 18 and the other end of the back washing pipeline. Based on the above, the body method and the suspension method can share a section of back washing pipeline. The first switch valve is opened and the second switch valve is closed, and the suspension method can be used. The first switch valve is closed and the second switch valve is opened, and the method can be used for the body method.
The high-temperature gas outlet of the regenerated gas heat exchanger 12 is communicated with the safety tank 11, the third gas outlet is communicated with the fourth gas inlet, the fourth liquid outlet is communicated with the monomer buffer tank 9, the desalted water pipeline 6 is communicated with the fourth liquid inlet, the fourth gas outlet is communicated with the third gas inlet and the safety tank 11 through a third three-way switching valve 15, and the safety tank 11 is communicated with the third gas inlet or an emptying pipeline through a fourth switching valve 16. The two desalination water pipelines 6 are the same pipeline.
The monomer surge tank 9 has a gas exhaust port communicating with the third gas inlet port. The communication pipeline can be provided with a one-way valve. Based on this, the system can further process the outlet gas of the evaporative condenser and the discharge of the monomer buffer tank.
And the third air outlet is communicated with the third switch valve 19 and the outlet of the rotary blanking valve 3 in sequence. The communication pipeline can be provided with a one-way valve. Based on the method, the discharging of the rotary discharging valve can be promoted by utilizing the air outlet of the compressor.
The recycling gas buffer tank 1 comprises a buffer tank body, a collecting net is transversely arranged on the upper portion in the buffer tank body, the first gas inlet is formed in the first feed opening and the first return opening, the first gas outlet is formed in the lower portion of the collecting net, and the first return opening is formed in the upper portion of the collecting net. The buffer tank body is cylindrical, and the first air inlet is arranged along the tangential direction of the first air inlet. And a stirring device is arranged at the bottom of the buffer tank body. Based on the method, the suspension method is facilitated.
The recovery filter 2 comprises a tank body 21, a plurality of filter pipes 22 with upper end openings and lower ends closed are vertically arranged in the tank body 21, a fixed pattern plate penetrates through the upper end openings of the filter pipes 22 and is fixedly connected with the filter pipes, a back flushing pipe 24 is fixedly arranged above the fixed pattern plate through a fixing frame 23, the back flushing pipe 24 is provided with a plurality of nozzles 25, the nozzles 25 are correspondingly arranged above the upper end openings of the filter pipes 22 one by one, a second air inlet is communicated with the lower space of the tank body 21, a second air outlet is communicated with the upper space of the tank body 21, a second back flushing port is communicated with the back flushing pipe 24, and a second blanking port is communicated with the bottom of the tank body 21. The tank body 21 is cylindrical, the filter pipes 22 are arranged around the circumferential direction to form a plurality of annular rings with gradually increasing radiuses, and the filter pipes 22 in each ring are uniformly arranged around the circumferential direction. The lower part of the tank body 21 is in a half-gourd shape, and the diameter of the tank body is larger than that of the tank body 21. Based on the technical scheme, the back blowing and the suction can be efficiently carried out on each filter pipe 22.
To ensure the capacity of the polymerization process, the VC polymerization tail gas recovery system was designed to recover vinyl chloride gas as polymerization tail gas at 15% of the polymerization feed rate, which corresponds to the high peak recovery from the lowest conversion of one pot with the stripper operating at maximum flow. It is assumed that the gas entering the vinyl chloride compressor contains 1% by volume of inert gas, and that these inert gases have the properties of air.
VC-containing tail gas from a polymerization kettle, a discharge tank system, a stripping tower, a vacuum pump and a wastewater stripping tower system (or a bulk degassing system and a homogenizing system) enters a recycle gas buffer tank 1 (the type can be selected from V300) according to a tangent form, so that the retention time of the gas is ensured to be more than 2 seconds, and most of gas-carried powder is separated again; the suspension method can carry a small amount of water vapor to enter, the water vapor is settled again, the slurry is not hardened by stirring the bottom of the recycle gas buffer tank 1, the discharge of the bottom of the buffer tank is carried out in time by setting the material level condition of a liquid level meter, and the material is sent to a stripping tower by a discharge centrifugal pump (the model can be selected from P300A/B); a pressure detection instrument can be arranged at an inlet and an outlet of the recovery buffer tank, the tail gas pressure difference is automatically calculated, when the pressure difference is larger than 200Pa, washing water is started to wash the powder of the trapping net, the material is discharged in time according to the material level condition, the washing time is not more than 5min, the washing water pressure is not lower than 0.6MPa (G), and the washing water passes through a nozzle which is arranged at the top of the buffer tank and can be 360 degrees to wash the filter net; (if the tail gas is the body method, a water washing process is not adopted, the outlet gas of a compressor is adopted to carry out back flushing on a system, and aggregate is conveyed to a degassing tank by an air conveying system);
the tail gas after primary filtration is discharged from the top of the recycle gas buffer tank 1, and then passes through a filter element with the filtering precision of 3 mu m continuously through a recycle filter 2, the filtering efficiency is 99.99 percent, and the solid content of the tail gas is lower than or equal to 0.5mg/m3(ii) a The outlet and the inlet of the fine filter can be provided with a pressure detection instrument, the pressure difference is calculated, and when the pressure difference is larger than 150Pa, the pressure difference is switched to another one to flush the current one. Cleaning a high-precision filter element by flushing water and back flushing gas in a pulse mode, wherein the back flushing time and the back flushing time are not more than 5min, the pressure of the flushing water and the back flushing gas is controlled at 0.3MPa (G) -0.5MPa (G), discharging the materials into a recovery filter 2 in time according to the material level condition, and sending the slurry to steam stripping according to the material level of a buffer tank; (if the tail gas is the body method, a water washing process is not adopted, a back-blowing system is adopted by the back end gas of a compressor, and aggregate is sent to a degassing tank by an air conveying system);
the tail gas passing through the recovery filter 2 enters a screw compressor, the outlet pressure of the compressor is not lower than 0.6MPa (G), the temperature is not higher than 40 ℃, the compressor is complete equipment, and heat exchange is contained in a compression boundary region; a part of the compressed gas is sent to an evaporative condenser 8 for liquefaction; one part of gas is used as the back flushing gas of the filter screens of the recovery filter 2 and the recovery gas buffer tank 1, the operation is carried out intermittently (if the tail gas is produced by a body method, the blanking of the recovery filter 2 enters an air supply system through a rotary blanking valve 3, an air supply source comes from the outlet of a compressor, and the operation is continuous operation.
Compressed tail gas enters an evaporative condenser 8, a fan of the evaporative condenser 8 is in variable frequency setting, so that the VC temperature is always ensured to be lower than 28 ℃, a tail gas pressure regulating valve is arranged, regulation is carried out according to the inlet pressure of the evaporative condenser, and the internal pressure of a heat exchange coil of the evaporative condenser is kept to be not lower than 0.6MPa (G), so that the liquefaction effect is ensured; the noncondensable gas outlet can be provided with an online VC content monitor meter and a three-way programmable valve switch, and the VC content is higher than 8mg/m3The tail gas is not discharged to the security tank, returns to the inlet of the compressor and is compressed and condensed newly;
the evaporative condensate enters the monomer buffer tank 9 through the U-shaped pipe, the U-shaped pipe ensures that tail gas does not enter the monomer buffer tank 9, the monomer quality in the tank is controlled within 1 ton, and the monomer is buffered on site and is not stored, so that a major hazard source is not formed; the monomer buffer tank 9 can be provided with a liquid level meter and an outlet regulating valve for ensuring that the liquid level of the monomer buffer tank 9 keeps a certain range; the monomer buffer tank 9 can be provided with safety accessories such as a safety valve, a field pressure gauge and the like, then the gas phase in the monomer buffer tank 9 is communicated with the inlet of the compressor, and the gas-phase chloroethylene is recovered in time, so that the safe operation of the buffer tank is ensured;
VC content is less than 8mg/m3The tail gas enters the security tank and is discharged outside 11, the security tank 11 can be provided with an online VC content monitoring instrument, and the VC content is higher than 8mg/m3The security tank is switched to another one; the security tank with saturated adsorption is regenerated by hot nitrogen, and the regenerated tail gas is sent to an inlet of a compressor 5 to recover VC in the regenerated gas; therefore, one security tank is always in a standby state, and the exhaust is discharged in a qualified mode and VC in the exhaust is recovered to the maximum extent.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. A VC polymerization tail gas recovery system which is characterized in that: including recovery gas buffer tank (1), at least one recovery filter (2), rotatory unloading valve (3), at least one ejection of compact centrifugal pump (4), at least one compressor (5), desalination water pipeline (6) and strip pipeline (7), recovery gas buffer tank (1) has first air inlet, first gas outlet, first back flush mouth, first feed opening and first feed back mouth, recovery filter (2) has second air inlet, second gas outlet, second back flush mouth and second feed back mouth, each compressor (5) has third air inlet and third gas outlet, wherein:
the first air outlet is respectively communicated with the second air inlets, the second air outlets are respectively communicated with the third air inlets, the third air outlets are respectively communicated with the second back flushing ports and the first back flushing ports, the third air outlets are also sequentially communicated with an evaporative condenser (8) and a monomer buffer tank (9), and the monomer buffer tank (9) is respectively communicated with at least one conveying pump (10);
the desalination water pipeline (6) is respectively communicated with the first back flushing port and each second back flushing port, the first discharging port is respectively communicated with each discharging centrifugal pump (4) and the rotary blanking valve (3), each second discharging port is respectively communicated with the first return port and the rotary blanking valve (3), and each discharging centrifugal pump (4) and the rotary blanking valve (3) are respectively communicated with the stripping pipeline (7).
2. The VC polymerization tail gas recovery system according to claim 1, wherein:
the first discharging port is communicated with each discharging centrifugal pump (4) or the rotary discharging valve (3) through a first three-way switching valve (13);
and each second feed opening is respectively communicated with the first return opening or the rotary feed valve (3) through a second three-way switching valve (14).
3. The VC polymerization tail gas recovery system according to claim 1, wherein: the desalination water pipeline (6) is sequentially communicated with a first switch valve (17) and one end of a back washing pipeline, the third air outlet is sequentially communicated with a second switch valve (18) and the other end of the back washing pipeline, and the back washing pipeline is respectively communicated with the first back washing port and each second back washing port.
4. The VC polymerization tail gas recovery system according to claim 1, wherein: the system still includes security personnel jar (11) and regeneration gas heat exchanger (12), the high temperature gas outlet intercommunication of regeneration gas heat exchanger (12) security personnel jar (11), evaporative condenser (8) have fourth air inlet, fourth gas outlet, fourth inlet and fourth liquid outlet, the third gas outlet intercommunication the fourth air inlet, fourth liquid outlet intercommunication monomer buffer tank (9), desalination pipeline (6) intercommunication the fourth inlet, the fourth gas outlet communicates respectively through third three-way switch valve (15) the third air inlet with security personnel jar (11), security personnel jar (11) rethread fourth switch valve (16) communicate respectively third air inlet or blow-down pipeline.
5. The VC polymerization tail gas recovery system of claim 4, wherein:
the monomer buffer tank (9) is provided with an exhaust port which is communicated with the third air inlet;
and the third air outlet is communicated with the third switch valve (19) and the outlet of the rotary blanking valve (3) in sequence.
6. A VC polymerization tail gas recovery system according to any one of claims 1 to 5, characterized in that: the recycling gas buffer tank (1) comprises a buffer tank body, a collecting net is transversely arranged on the upper portion in the buffer tank body, the first gas inlet is formed in the first feed opening, the first return opening is formed in the lower portion of the collecting net, and the first gas outlet is formed in the upper portion of the collecting net.
7. The VC polymerization tail gas recovery system according to claim 6, wherein:
the buffer tank body is cylindrical, and the first air inlet is arranged along the tangential direction of the first air inlet;
and a stirring device is arranged at the bottom of the buffer tank body.
8. A VC polymerization tail gas recovery system according to any one of claims 1 to 5, characterized in that: the recovery filter (2) comprises a tank body (21), wherein a plurality of filter pipes (22) with upper end openings and lower end closures are vertically arranged in the tank body (21), a fixed pattern plate penetrates through the upper end openings of the filter pipes (22) and is fixedly connected with the filter pipes, annular back-flushing pipes (24) are fixedly arranged above the fixed pattern plate through fixing frames (23), the back-flushing pipes (24) are provided with a plurality of nozzles (25), the nozzles (25) are correspondingly arranged above the upper end openings of the filter pipes (22), a second air inlet is communicated with the lower space of the tank body (21), a second air outlet is communicated with the upper space of the tank body (21), a second back-flushing port is communicated with the back-flushing pipes (24), and a second feed port is communicated with the bottom of the tank body (21).
9. The VC polymerization tail gas recovery system according to claim 8, wherein: the tank body (21) is cylindrical, the filter pipes (22) are arranged in a plurality of circles around the circumferential direction of the tank body to form a circular ring shape with gradually increased radius, and the filter pipes (22) in each circle are uniformly arranged at intervals around the circumferential direction.
10. The VC polymerization tail gas recovery system according to claim 8, wherein: the lower part of the tank body (21) is arc-shaped and protrudes outwards to form a semi-gourd shape, and the diameter of the protruding part is larger than that of the tank body (21).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011518765.6A CN112495071A (en) | 2020-12-21 | 2020-12-21 | VC polymerization tail gas recovery system |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011518765.6A CN112495071A (en) | 2020-12-21 | 2020-12-21 | VC polymerization tail gas recovery system |
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| CN112495071A true CN112495071A (en) | 2021-03-16 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113058342A (en) * | 2021-04-13 | 2021-07-02 | 西安航空制动科技有限公司 | CVD furnace filter equipment convenient to online real-time clearance |
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2020
- 2020-12-21 CN CN202011518765.6A patent/CN112495071A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113058342A (en) * | 2021-04-13 | 2021-07-02 | 西安航空制动科技有限公司 | CVD furnace filter equipment convenient to online real-time clearance |
| CN113058342B (en) * | 2021-04-13 | 2022-10-28 | 西安航空制动科技有限公司 | CVD furnace filter equipment convenient to online real-time clearance |
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