CN115612168B - Secondary recycling method of polymerization kettle for polyvinyl chloride production - Google Patents
Secondary recycling method of polymerization kettle for polyvinyl chloride production Download PDFInfo
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- CN115612168B CN115612168B CN202211037383.0A CN202211037383A CN115612168B CN 115612168 B CN115612168 B CN 115612168B CN 202211037383 A CN202211037383 A CN 202211037383A CN 115612168 B CN115612168 B CN 115612168B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/02—Recovery or working-up of waste materials of solvents, plasticisers or unreacted monomers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2327/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers
- C08J2327/02—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment
- C08J2327/04—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
- C08J2327/06—Homopolymers or copolymers of vinyl chloride
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Abstract
The secondary recovery method of the polymerization kettle for producing the polyvinyl chloride is characterized by comprising the following steps of: s1, opening a secondary recovery valve of the polymerization kettle, and starting a secondary recovery vacuumizing system. S2, opening a secondary recovery steam valve of the polymerization kettle, and introducing steam into the kettle. S3, continuously vacuumizing. S4, starting a mother liquor pump, and opening a mother liquor valve of the polymerization kettle. S5, starting a vacuumizing system of the polymerization kettle. S6, opening a secondary recovery steam valve. S7, opening a nitrogen charging valve at the top of the polymerization kettle. And S8, continuously pumping negative pressure after nitrogen introduction is completed. S9, opening a nitrogen filling valve at the top of the polymerization kettle, and introducing nitrogen into the polymerization kettle to break vacuum. The secondary recycling method of the polymerization kettle for producing polyvinyl chloride can quickly and thoroughly recycle the polymerization kettle, can avoid the problems of long recycling time and incomplete recycling, not only can ensure the physical health of people, but also can reduce potential safety hazards.
Description
Technical Field
The invention relates to polyvinyl chloride production equipment, in particular to a secondary recovery method of a polymerization kettle for polyvinyl chloride production.
Background
In the process of producing polyvinyl chloride by a suspension method, a polymerization kettle is a main production device, and the polymerization kettle is required to be opened for inspection and cleaning after a certain batch of polymerization kettle is operated. At the present stage, the conversion rate of the vinyl chloride polymerization reaction is about 80% -85%, and unreacted monomers are recovered to a compression recovery system through a kettle top recovery pipeline for condensation recycling when the polymerization kettle is discharged, and the process is called primary recovery. However, a large amount of vinyl chloride remains in the polymerization vessel after one recovery. Vinyl chloride is a combustible explosive material and has certain toxicity, so that the secondary recovery of the polymerization kettle is needed before a worker opens the polymerization kettle in order to prevent the damage of the gas in the kettle to the human health and the potential safety hazard caused by the explosion gas formed by mixing the vinyl chloride and air. At present, the existing secondary recovery method generally comprises the steps of introducing steam into a polymerization kettle and vacuumizing at the same time, and the conventional method has the defects of long time consumption and incomplete replacement. Therefore, a person skilled in the art provides a secondary recycling method of a polymerization kettle for producing polyvinyl chloride to solve the technical problems.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a secondary recycling method of a polymerization kettle for polyvinyl chloride production, which can quickly and thoroughly recycle the polymerization kettle, can avoid the problems of long recycling time and incomplete recycling, not only can ensure the physical health of people, but also can reduce the potential safety hazard.
The invention relates to a secondary recycling method of a polymerization kettle for polyvinyl chloride production, which is characterized by comprising the following steps:
s1, opening a secondary recovery valve of the polymerization kettle, starting a secondary recovery vacuumizing system, operating a secondary recovery vacuum pump and vacuumizing the polymerization kettle.
S2, when the pressure of the polymerization kettle is reduced to minus 0.04MPa, opening a secondary recovery steam valve of the polymerization kettle, introducing steam into the kettle, and closing the valve after a few minutes.
And S3, continuously vacuumizing until the pressure of the kettle is reduced to minus 0.08MPa, closing a secondary recovery valve of the polymerization kettle, and stopping the secondary recovery vacuumizing system.
S4, starting a mother liquor pump, opening a mother liquor valve of the polymerization kettle, pumping mother liquor into the polymerization kettle, closing the mother liquor valve after a few minutes, stopping the mother liquor pump, and finishing water pumping.
S5, starting a vacuumizing system of the polymerization kettle, opening a vacuumizing valve of the polymerization kettle, operating a vacuumizing pump and vacuumizing the polymerization kettle.
S6, when the pressure of the polymerization kettle is reduced to minus 0.04MPa, opening a valve for secondary recovery steam, introducing steam into the polymerization kettle, and closing the valve after tens of seconds.
And S7, when the pressure of the polymerization kettle is reduced to-0.08 MPa, opening a nitrogen filling valve at the top of the polymerization kettle, introducing nitrogen into the polymerization kettle, and closing the valve after a few minutes.
And S8, after nitrogen introduction is completed, continuously pumping negative pressure until the pressure of the kettle is reduced to minus 0.08MPa, closing a vacuumizing valve of the polymerization kettle, and stopping a vacuumizing system of the polymerization kettle.
S9, opening a nitrogen filling valve at the top of the polymerization kettle, introducing nitrogen into the polymerization kettle to break vacuum, closing the nitrogen filling valve at the top of the polymerization kettle when the pressure of the kettle rises to 0.00-0.01MPa, and opening a vent valve of the polymerization kettle to finish the secondary recovery operation of the polymerization kettle.
The invention has the beneficial effects that: the secondary recovery method can rapidly and thoroughly carry out secondary recovery on the polymerization kettle, avoids the problem of long recovery time consumption, simultaneously also avoids the problem of environmental pollution caused by incomplete recovery, not only ensures the physical health of people, but also reduces potential safety hazards.
Drawings
Fig. 1 is a schematic structural view of an embodiment of the present invention.
1-a polymerization kettle 2-a secondary recovery valve 3-a secondary recovery vacuum pump 4-a secondary recovery steam valve 5-a mother liquor water pump 6-a mother liquor water valve 7-a vacuumizing valve 8-a vacuumizing pump 9-a nitrogen filling valve.
Detailed Description
Referring now to the drawings, the following is described, in connection with specific embodiments: the invention relates to a secondary recovery method of a polymerization kettle for polyvinyl chloride production, which comprises the following steps:
s1, opening a secondary recovery valve 2 of the polymerization kettle 1, starting a secondary recovery vacuumizing system, operating a secondary recovery vacuum pump 3 and vacuumizing the polymerization kettle 1.
S2, when the pressure of the polymerization kettle 1 is reduced to minus 0.04MPa, opening a secondary recovery steam valve 4 of the polymerization kettle 1, and introducing steam into the kettle for 2-5 minutes. In practical operation, according to the state equation pv=nrt of ideal gas, it can be known that when the pressure in the polymerization kettle is reduced from 0.01MPa to about-0.04 MPa under the condition of unchanged temperature and volume, the amount of substances in the gas is reduced by about 45%, and it can be approximately considered that half of vinyl chloride gas in the kettle is pumped out of the polymerization kettle by the secondary recovery vacuum pump. And the steam is introduced for 2-5 minutes to raise the temperature of the polymerization kettle from about 30 ℃ to 60-65 ℃, and the temperature is doubled under the condition of unchanged volume and pressure, so that the amount of residual gas substances in the polymerization kettle can be reduced by half again, and the amount of chloroethylene substances in the polymerization kettle is reduced to 1/4 of that of the original chloroethylene substances.
And S3, continuously vacuumizing until the pressure of the kettle is reduced to minus 0.08MPa, closing the secondary recovery valve 2 of the polymerization kettle 1, and stopping the secondary recovery vacuumizing system. In practice, when the pressure of the polymerizer is reduced from-0.04 MPa to-0.08 MPa, the amount of gaseous substances in the polymerizer is reduced by about 50%, and by this step, the amount of vinyl chloride substances in the polymerizer can be reduced to the initial 1/8.
S4, starting a mother liquor water pump 5, opening a mother liquor water valve 6 of the polymerization kettle 1, pumping mother liquor water into the polymerization kettle 1, closing the mother liquor water valve 6 after 7.5-8 minutes, stopping the mother liquor water pump 5, and finishing water pumping. At this time, the liquid level in the polymerization kettle 1 should be near the interface of the upper end socket of the polymerization kettle 1 and the cylinder. In actual operation, the time for beating the mother liquor is controlled to be 7.5-8 minutes, and the volume of the mother liquor which is pumped into the polymerization kettle is about 80-85 m, so that the volume of a gas phase space in the polymerization kettle can be reduced to about 25m, and the pressure of the polymerization kettle is close to normal pressure.
S5, starting a vacuumizing system of the polymerization kettle 1, opening a vacuumizing valve 7 of the polymerization kettle 1, operating a vacuumizing pump 8 and vacuumizing the polymerization kettle 1.
S6, when the pressure of the polymerization kettle 1 is reduced to minus 0.04MPa, opening a secondary recovery steam valve 2, and introducing steam into the polymerization kettle 1 for 30 seconds. By this step operation, the pot temperature can be maintained at 60 to 65℃and the pot pressure can be reduced to about-0.04 MPa, so that the vinyl chloride content in the polymerization pot can be reduced to the initial 1/16.
And S7, when the pressure of the polymerization kettle 1 is reduced to minus 0.08MPa, opening a nitrogen charging valve 9 at the top of the polymerization kettle 1, and introducing nitrogen into the polymerization kettle 1 for 1-2 minutes. In practice, the pressure in the polymerizer was reduced from-0.04 MPa to-0.08 MPa, and the amount of gaseous substances in the polymerizer was reduced by about 50%, so that the amount of vinyl chloride substances in the polymerizer was reduced to the original 1/32. The nitrogen flow rate is regulated to control the nitrogen introducing time of the polymerization kettle, the nitrogen is filled while the operation of the vacuumizing system is maintained, the nitrogen introducing time is flexibly regulated according to the working capacity of the vacuum pump and the nitrogen flow rate, the polymerization kettle is always kept in a negative pressure state, the pressure of the polymerization kettle is kept at a slight negative pressure (-0.00 to-0.01 MPa) after the nitrogen filling is finished, the nitrogen amount is slightly larger than the volume of a gas phase space in the polymerization kettle, and the vinyl chloride gas in the gas phase space is replaced by the nitrogen.
And S8, after nitrogen introduction is completed, continuously pumping negative pressure until the pressure of the kettle is reduced to minus 0.08MPa, closing the vacuumizing valve 7 of the polymerization kettle 1, and stopping the vacuumizing system of the polymerization kettle 1. The pressure of the polymerization kettle is reduced to minus 0.08Mpa from slight negative pressure by vacuumizing, so that the amount of vinyl chloride gas in the polymerization kettle can be further reduced to 1/4 of the vinyl chloride content in the polymerization kettle after nitrogen introduction is finished.
S9, opening a nitrogen filling valve 9 at the top of the polymerization kettle 1, introducing nitrogen into the polymerization kettle 1 to break vacuum, closing the nitrogen filling valve 9 at the top of the polymerization kettle 1 when the kettle pressure rises to 0.00-0.01MPa, and opening a vent valve of the polymerization kettle 1 to finish the secondary recovery operation of the polymerization kettle. In actual operation, the pressure of the kettle is controlled to be 0.00-0.01Mpa, so that the pressure of the polymerization kettle is slightly positive, and then a vent valve and a manhole cover of the polymerization kettle are opened, so that the condition that the manhole is difficult to open due to the pressure of the kettle in the polymerization kettle can be avoided.
While the fundamental and principal features of the invention and advantages of the invention have been shown and described, it will be apparent to those skilled in the art that the invention is not limited to the details of the foregoing exemplary embodiments, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present disclosure describes embodiments, not every embodiment is provided with a separate embodiment, and that this description is provided for clarity only, and that the disclosure is not limited to the embodiments described in detail below, and that the embodiments described in the examples may be combined as appropriate to form other embodiments that will be apparent to those skilled in the art.
Claims (5)
1. The secondary recovery method of the polymerization kettle for producing the polyvinyl chloride is characterized by comprising the following steps of:
s1, opening a secondary recovery valve of the polymerization kettle, starting a secondary recovery vacuumizing system, operating a secondary recovery vacuum pump and vacuumizing the polymerization kettle;
s2, when the pressure of the polymerization kettle is reduced to minus 0.04MPa, opening a secondary recovery steam valve of the polymerization kettle, introducing steam into the kettle, and closing the valve after a few minutes;
s3, continuously vacuumizing until the pressure of the kettle is reduced to minus 0.08MPa, closing a secondary recovery valve of the polymerization kettle, and stopping the secondary recovery vacuumizing system;
s4, starting a mother liquor pump, opening a mother liquor valve of the polymerization kettle, pumping mother liquor into the polymerization kettle, closing the mother liquor valve after a few minutes, stopping the mother liquor pump, and finishing water pumping;
s5, starting a vacuumizing system of the polymerization kettle, opening a vacuumizing valve of the polymerization kettle, operating a vacuumizing pump and vacuumizing the polymerization kettle;
s6, when the pressure of the polymerization kettle is reduced to-0.04 MPa, opening a valve for secondary recovery steam, introducing steam into the polymerization kettle, and closing the valve after tens of seconds;
s7, when the pressure of the polymerization kettle is reduced to-0.08 MPa, opening a nitrogen filling valve at the top of the polymerization kettle, introducing nitrogen into the polymerization kettle, and closing the valve after a few minutes;
s8, after nitrogen introduction is completed, continuously pumping negative pressure until the pressure of the kettle is reduced to minus 0.08MPa, closing a vacuumizing valve of the polymerization kettle, and stopping a vacuumizing system of the polymerization kettle;
s9, opening a nitrogen filling valve at the top of the polymerization kettle, introducing nitrogen into the polymerization kettle to break vacuum, closing the nitrogen filling valve at the top of the polymerization kettle when the pressure of the kettle rises to 0.00-0.01MPa, and opening a vent valve of the polymerization kettle to finish the secondary recovery operation of the polymerization kettle.
2. The secondary recycling method of a polymerization kettle for producing polyvinyl chloride according to claim 1, wherein the method comprises the following steps: in S2, the steam is introduced for 2-5 minutes.
3. The secondary recycling method of a polymerization kettle for producing polyvinyl chloride according to claim 1, wherein the method comprises the following steps: and S4, closing a mother liquor valve after 7.5-8 minutes, wherein the liquid level in the kettle of the polymerization kettle is near the interface of the upper end socket of the polymerization kettle and the barrel.
4. The secondary recycling method of a polymerization kettle for producing polyvinyl chloride according to claim 1, wherein the method comprises the following steps: in S6, the steam-on time is 30 seconds.
5. The secondary recycling method of a polymerization kettle for producing polyvinyl chloride according to claim 1, wherein the method comprises the following steps: in S7, the nitrogen gas is introduced for 1-2 minutes.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202211037383.0A CN115612168B (en) | 2022-08-29 | 2022-08-29 | Secondary recycling method of polymerization kettle for polyvinyl chloride production |
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| CN202211037383.0A CN115612168B (en) | 2022-08-29 | 2022-08-29 | Secondary recycling method of polymerization kettle for polyvinyl chloride production |
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| CN115612168B true CN115612168B (en) | 2023-06-06 |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4086414A (en) * | 1974-08-19 | 1978-04-25 | Ethyl Corporation | Steam stripping polyvinyl chloride resins |
| US4367331A (en) * | 1978-07-27 | 1983-01-04 | Wacker-Chemie Gmbh | Method of degassing of aqueous PVC dispersions |
| CN206751716U (en) * | 2017-05-04 | 2017-12-15 | 宜宾天原集团股份有限公司 | The purifying processing device of polyvinyl chloride synthesis low pressure recovery monomer |
| CN112275244A (en) * | 2020-11-27 | 2021-01-29 | 昊华宇航化工有限责任公司 | Device and method for replacing vinyl chloride polymerization kettle |
-
2022
- 2022-08-29 CN CN202211037383.0A patent/CN115612168B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4086414A (en) * | 1974-08-19 | 1978-04-25 | Ethyl Corporation | Steam stripping polyvinyl chloride resins |
| US4367331A (en) * | 1978-07-27 | 1983-01-04 | Wacker-Chemie Gmbh | Method of degassing of aqueous PVC dispersions |
| CN206751716U (en) * | 2017-05-04 | 2017-12-15 | 宜宾天原集团股份有限公司 | The purifying processing device of polyvinyl chloride synthesis low pressure recovery monomer |
| CN112275244A (en) * | 2020-11-27 | 2021-01-29 | 昊华宇航化工有限责任公司 | Device and method for replacing vinyl chloride polymerization kettle |
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| CN115612168A (en) | 2023-01-17 |
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