CN107602739A - The multi-stage polymeric process and device of a kind of propylene - Google Patents
The multi-stage polymeric process and device of a kind of propylene Download PDFInfo
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- CN107602739A CN107602739A CN201710968980.8A CN201710968980A CN107602739A CN 107602739 A CN107602739 A CN 107602739A CN 201710968980 A CN201710968980 A CN 201710968980A CN 107602739 A CN107602739 A CN 107602739A
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- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 title claims abstract description 176
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 title claims abstract description 176
- 238000000034 method Methods 0.000 title abstract description 7
- 239000007791 liquid phase Substances 0.000 claims abstract description 150
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 124
- 239000000463 material Substances 0.000 claims abstract description 103
- 229920000642 polymer Polymers 0.000 claims abstract description 67
- 238000006243 chemical reaction Methods 0.000 claims abstract description 64
- 238000012685 gas phase polymerization Methods 0.000 claims abstract description 44
- 239000000203 mixture Substances 0.000 claims abstract description 6
- 239000012071 phase Substances 0.000 claims description 117
- 239000007789 gas Substances 0.000 claims description 110
- 239000007788 liquid Substances 0.000 claims description 61
- 238000000926 separation method Methods 0.000 claims description 52
- 239000001257 hydrogen Substances 0.000 claims description 28
- 229910052739 hydrogen Inorganic materials 0.000 claims description 28
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 25
- 239000003054 catalyst Substances 0.000 claims description 25
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 10
- 239000005977 Ethylene Substances 0.000 claims description 10
- 238000002156 mixing Methods 0.000 claims description 10
- 238000007599 discharging Methods 0.000 claims description 8
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 claims description 5
- IAQRGUVFOMOMEM-UHFFFAOYSA-N butene Natural products CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 claims description 5
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 2
- 238000009833 condensation Methods 0.000 claims 1
- 230000005494 condensation Effects 0.000 claims 1
- 239000004743 Polypropylene Substances 0.000 abstract description 13
- 229920001155 polypropylene Polymers 0.000 abstract description 13
- 238000009826 distribution Methods 0.000 abstract description 12
- 239000002245 particle Substances 0.000 abstract description 7
- -1 polypropylene Polymers 0.000 abstract description 6
- 238000002360 preparation method Methods 0.000 abstract description 2
- 238000002844 melting Methods 0.000 abstract 2
- 230000008018 melting Effects 0.000 abstract 2
- 229920001577 copolymer Polymers 0.000 abstract 1
- 230000004069 differentiation Effects 0.000 abstract 1
- 230000035484 reaction time Effects 0.000 abstract 1
- 125000000383 tetramethylene group Chemical group [H]C([H])([*:1])C([H])([H])C([H])([H])C([H])([H])[*:2] 0.000 description 5
- 238000007334 copolymerization reaction Methods 0.000 description 4
- 239000000178 monomer Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 229920005629 polypropylene homopolymer Polymers 0.000 description 3
- 230000001502 supplementing effect Effects 0.000 description 3
- 238000010574 gas phase reaction Methods 0.000 description 2
- 239000012855 volatile organic compound Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000005416 organic matter Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 229920005606 polypropylene copolymer Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
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- Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
- Polymerisation Methods In General (AREA)
Abstract
The multi-stage polymeric process and device of a kind of propylene, first subregion carries out prepolymerization, then carries out liquid-phase polymerization, and liquid-phase polymerization sets two reaction zones, material composition and reaction system in two reaction zones is identical or different, then carries out gas phase polymerization and the 4th section of gas phase polymerization.The present invention is using prepolymerization in parallel and liquid-phase polymerization mode in parallel, differentiation control is carried out to reaction system, improve the reaction time, make polymer that there is broader molecular weight distribution, with higher molecular weight, relatively low melting means, further expand the melting means difference of each section of polymer, improve its processing characteristics and mechanical property, HOPP can be produced using the present invention, binary atactic copolymerized polypropene, ternary polymerized polypropylene or the impact copolymer polypropylene with high rubber content, the polymer particle diameter of preparation is evenly distributed, with low-volatile content of organics, wide molecular weight distribution and excellent mechanical property, processing characteristics.
Description
Technical Field
The invention belongs to the field of preparation of high polymer materials, and particularly relates to a multistage polymerization method and device for propylene.
Background
In the existing propylene polymerization process, each reactor is mainly operated in series or operated in a single reactor, only one catalyst system can be adopted, the monomer composition difference among the reactors is small, and the improvement of the mechanical property and the processability of a polymer is limited.
Disclosure of Invention
The invention aims to provide a multistage polymerization method and a multistage polymerization device for propylene, which adopt a parallel prepolymerization mode and a parallel liquid phase polymerization reaction mode to perform differential control on a reaction system, reduce the monomer content in a polymer, control the volatile organic compound content of the polymer, ensure that the polymer has uniform particle size distribution, excellent mechanical and processing properties such as high fluidity, wide molecular weight distribution, high crystallization and the like, and can produce homo-polypropylene, binary random co-polypropylene, ternary co-polypropylene or impact co-polypropylene with high rubber content.
In order to achieve the purpose, the invention provides the following technical scheme:
a multistage polymerization process for propylene comprising the steps of:
1) prepolymerization reaction
Setting two liquid-phase prepolymerization reaction zones connected in parallel, mixing and stirring two paths of catalysts and liquid-phase propylene cooled to 5-10 ℃ in the two prepolymerization reaction zones respectively, and carrying out prepolymerization reaction at 22-28 ℃ and 3.0-3.5MPag for 12-17 min;
2) liquid phase polymerization
Two liquid phase reaction zones connected in parallel are arranged, and the reaction materials from the prepolymerization zone and the newly supplemented liquid phase propylene are respectively sent into the two reaction zones to respectively carry out liquid phase polymerization; the reaction temperature is 68-72 ℃, and the pressure is 2.8-3.4 MPag;
the polymerization heat gasifies liquid phase propylene in the reactors, gas phase propylene is discharged from the upper parts of the reactors of the two reaction areas, and the gas phase propylene returns to the corresponding reactors again after being condensed and separated, and the non-condensable gas after being separated is mixed with hydrogen and then returns to the corresponding reactors;
discharging a mixed material from the lower parts of the reactors of the two reaction zones, wherein the mass fraction of the polymer in the mixed material is 38-45%, and the liquid level in the reactors is controlled at 40-60%;
3) gas phase polymerization
The mixed material from the liquid phase reaction zone enters a gas phase polymerization reaction zone reactor to carry out gas phase polymerization reaction, the reaction temperature is 65-100 ℃, and the pressure is 2.4-2.8 MPag;
discharging gas-phase propylene containing polymers from the upper part of a gas-phase polymerization zone reactor, reducing gas-phase flow velocity through expansion and carrying out cyclone separation, after the polymers are separated out, condensing and separating the gas-phase propylene, removing polymerization reaction heat to obtain liquid-phase propylene, and feeding the liquid-phase propylene back to the reactor of the gas-phase polymerization zone, wherein the reaction temperature is controlled to be 65-100 ℃;
the non-condensable gas after the gas phase propylene is subjected to liquid separation is mixed with hydrogen and then returns to a reactor of the gas phase polymerization reaction zone; discharging a mixed material from the lower part of the reactor, wherein the mass fraction of the polymer in the mixed material is 75-85%, and the material level is controlled at 50-70%;
5) fourth stage polymerization
Feeding the mixed material discharged from the lower part of the reactor in the gas-phase polymerization reaction zone in the step 3) and the separated polymer into a reactor in a fourth gas-phase polymerization reaction zone for polymerization reaction at the temperature of 65-100 ℃ and the pressure of 2.2-2.6 MPag;
discharging gas-phase propylene containing polymers from the upper part of a reactor in a fourth gas-phase polymerization reaction zone, reducing the gas-phase flow rate through expansion and carrying out cyclone separation, after separating the polymers, condensing and separating the gas-phase propylene, removing the polymerization reaction heat, returning the obtained liquid-phase propylene to the reactor in the fourth gas-phase polymerization reaction zone, and controlling the reaction temperature to be 65-100 ℃;
and (3) mixing the non-condensable gas after the liquid separation of the gas-phase propylene with hydrogen, and then feeding the mixture back to a reactor in a fourth gas-phase polymerization reaction zone, wherein a mixed material is discharged from the lower part of the reactor, the mass fraction of the polymer in the mixed material is 75-85%, and the material level is controlled to be 50-70%.
Further, in step 1), the catalysts in the two prepolymerization zones are different.
Preferably, in step 2), the liquid level of each reactor of the two liquid-phase polymerization reaction zones is controlled between 48 and 56 percent.
Further, in the step 2), after the gas-phase propylene is condensed, the supplemented ethylene returns to the reactor along with the non-condensable gas and the hydrogen, and the supplemented butylene returns to the reactor along with the liquid-phase propylene.
In step 3) and/or step 4), the supplemented ethylene is returned to the reactor along with the non-condensable gas and the hydrogen after the gas-phase propylene is condensed, and the supplemented butylene or liquid-phase propylene is returned to the reactor along with the liquid-phase propylene.
The invention makes the catalyst particles completely wrapped by a proper amount of polymer through prepolymerization, increases the contact resistance of propylene and the catalyst, is used for controlling the reaction speed of the catalyst in a liquid phase polymerization reactor, and can prevent the catalyst from producing a large amount of fine powder due to over violent reaction in the reactor. The second-stage polymerization reaction is liquid-phase polymerization reaction, and mixed materials are discharged from the lower parts of the reactors of the two reaction zones, wherein the mass fraction of polymers in the mixed materials is 38-45%; the liquid level of the liquid phase reactor must be controlled at 40-60%, the third stage polymerization reaction is a gas phase polymerization reaction, after the gas phase propylene containing the polymer is expanded to reduce the gas phase flow rate, the polymer with the particle size larger than 50 microns returns to the reactor, the polymer with the particle size smaller than 50 microns and the gas phase mixture are subjected to cyclone separation, after the polymer with the particle size smaller than 50 microns is separated, the gas phase is condensed and separated, and the polymer solid is prevented from blocking the condenser; the fourth stage polymerization is also gas phase polymerization, and may have hydrogen added based on the molecular weight and melt index of the polymer and ethylene or butene added into the liquid phase polymerization reactor for producing atactic polypropylene copolymer.
The present invention provides a multistage polymerization apparatus for propylene, comprising:
the prepolymerization reaction unit comprises two prepolymerization reactors which are arranged in parallel, and the prepolymerization reactors are provided with a material inlet and a material outlet;
the liquid phase polymerization reaction unit comprises two liquid phase polymerization reactors, two propylene condensers, two liquid separation tanks and two circulating air blowers, wherein the two liquid phase polymerization reactors, the two propylene condensers, the two liquid separation tanks and the two circulating air blowers are respectively and correspondingly arranged with the two prepolymerization reactors; wherein the liquid phase polymerization reactor is provided with a material inlet, a material outlet, a gas phase propylene outlet, a liquid phase propylene inlet and a gas phase propylene inlet; the liquid separation tank is provided with a material inlet, a liquid phase outlet and a gas phase outlet;
the material outlet of the prepolymerization reactor is connected with the material inlet of the liquid phase polymerization reactor, the gas phase propylene outlet of the liquid phase polymerization reactor is connected with the propylene condenser and then connected with the material inlet of the liquid separation tank, the liquid phase outlet of the liquid separation tank is connected with the liquid phase propylene inlet of the liquid phase polymerization reactor, and the gas phase outlet of the liquid separation tank is connected with the gas phase propylene inlet of the liquid phase polymerization reactor through a circulating gas fan;
the gas-phase polymerization reaction unit comprises a horizontal reactor, a cyclone separator, a condenser, a liquid separation tank, a propylene condensate pump and a circulating gas fan; wherein the horizontal reactor is provided with two material inlets, a gas phase outlet, a liquid phase propylene inlet, a gas phase propylene inlet and a mixed material outlet; the cyclone separator is provided with a gas phase inlet, a gas phase outlet and a polymer outlet; the liquid separation tank is provided with a material inlet, a liquid phase outlet and a gas phase outlet; wherein,
the material outlets of the two liquid-phase polymerization reactors are respectively connected to the two material inlets of the horizontal reactor, the gas-phase outlet of the horizontal reactor is connected to the gas-phase inlet of the cyclone separator, the gas-phase outlet of the cyclone separator is connected with the condenser and then connected to the material inlet of the liquid separating tank, the liquid-phase outlet of the liquid separating tank is connected to the liquid-phase propylene inlet of the horizontal reactor through a propylene condensate pump, and the gas-phase outlet of the liquid separating tank is connected to the gas-phase propylene inlet of the horizontal reactor through a circulating gas fan;
the fourth polymerization reaction unit comprises a horizontal reactor, a cyclone separator, a condenser, a liquid separation tank, a propylene condensate pump and a circulating gas fan; wherein the horizontal reactor is provided with a material inlet, a gas phase outlet, a liquid phase propylene inlet, a gas phase propylene inlet and a mixed material outlet; the cyclone separator is provided with a gas phase inlet, a gas phase outlet and a polymer outlet; the liquid separation tank is provided with a material inlet, a liquid phase outlet and a gas phase outlet;
the gas-phase polymerization unit cyclone separator comprises a gas-phase polymerization unit cyclone separator, a gas-phase reactor, a condenser, a unit liquid separation tank, a circulating gas fan, a gas-phase reactor material inlet, a gas-phase reactor material outlet.
Preferably, the prepolymerization unit further comprises a propylene cooler arranged corresponding to the prepolymerization reactor, and the propylene cooler is connected with the material inlet of the prepolymerization reactor.
Furthermore, in the liquid phase polymerization reaction unit, the gas phase polymerization reaction unit and the fourth polymerization reaction unit, a gas phase outlet pipeline of each liquid separation tank is also provided with a pipeline for supplementing ethylene.
Preferably, the liquid phase polymerization reaction unit is also provided with a pipeline for supplementing butylene on a liquid phase outlet pipeline of each liquid separation tank.
In the gas-phase polymerization reaction unit and the fourth polymerization reaction unit, a pipeline for supplementing butylene and/or liquid-phase propylene is further arranged on a liquid-phase outlet pipeline of each liquid separation tank.
Compared with the prior art, the invention has the following beneficial effects:
the invention adopts a multi-stage polymerization process and combines reactors for differential control, namely, a parallel liquid phase reactor and a serial gas phase reactor are adopted, two liquid phase reactors can use the same catalyst system and composition to produce a universal polymer with narrow molecular weight distribution, two different catalyst systems can be added into the two liquid phase reactors, and different polymerization monomer components are adopted in the liquid phase reactors to produce polymers with wide molecular weight distribution, high fluidity, high crystallization and the like. Meanwhile, the serially connected gas phase reactors can produce impact-resistant co-polypropylene with high rubber content, and by increasing the polymerization temperature, the monomer content in the polymer can be reduced, and the volatile organic compound content of the polymer can be controlled.
The invention can be used for producing homo-polypropylene, binary random copolymerization polypropylene, ternary copolymerization polypropylene or impact-resistant copolymerization polypropylene with high rubber content, and the prepared polymer has uniform particle size distribution, low volatile organic matter content, wide molecular weight distribution, excellent mechanical property and processing property.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
Detailed Description
The present invention is further illustrated by the following specific examples.
Example 1 referring to fig. 1, the multistage polymerization apparatus for propylene according to the present invention comprises:
the prepolymerization reaction unit 1 comprises two prepolymerization reactors 11 and 11' which are arranged in parallel, and propylene coolers 10 and 10' which are arranged corresponding to the prepolymerization reactors, wherein the prepolymerization reactors 11 and 11' are provided with material inlets and material outlets, and the propylene coolers 10 and 10' are connected with the material inlets of the prepolymerization reactors 11 and 11 ';
the liquid phase polymerization reaction unit 2 comprises two liquid phase polymerization reactors 21 and 21', two propylene condensers 22 and 22', two liquid separation tanks 23 and 23', and two circulating air blowers 24 and 24' which are respectively arranged corresponding to the two prepolymerization reactors 11 and 11 '; wherein, the liquid phase polymerization reactors 21, 21' are provided with a material inlet and outlet, a gas phase propylene outlet, a liquid phase propylene inlet and a gas phase propylene inlet; the liquid separating tanks 23 and 23' are provided with a material inlet, a liquid phase outlet and a gas phase outlet;
the material outlets of the prepolymerization reactors 11 and 11 'are connected with the material inlets of the liquid phase polymerization reactors 21 and 21', the gas phase propylene outlets of the liquid phase polymerization reactors 21 and 21 'are connected with the propylene condensers 22 and 22' and then connected with the material inlets of the liquid separation tanks 23 and 23', the liquid phase outlets of the liquid separation tanks 23 and 23' are connected with the liquid phase propylene inlets of the liquid phase polymerization reactors 21 and 21', and the gas phase outlets of the liquid separation tanks 23 and 23' are connected with the gas phase propylene inlets of the liquid phase polymerization reactors 21 and 21 'through the circulating gas fans 24 and 24';
the gas-phase polymerization reaction unit 3 comprises a horizontal reactor 31, a cyclone separator 32, a condenser 33, a liquid separating tank 34, a propylene condensate pump 35 and a circulating gas fan 36; wherein, the horizontal reactor 31 is provided with two material inlets, a gas phase outlet, a liquid phase propylene inlet, a gas phase propylene inlet and a mixed material outlet; the cyclone separator 32 is provided with a gas phase inlet, a gas phase outlet and a polymer outlet; the liquid separation tank 34 is provided with a material inlet, a liquid phase outlet and a gas phase outlet; wherein,
the material outlets of the two liquid-phase polymerization reactors 21 and 21' are respectively connected to two material inlets of the horizontal reactor 31, the gas-phase outlet of the horizontal reactor 31 is connected to the gas-phase inlet of the cyclone separator 32, the gas-phase outlet of the cyclone separator 32 is connected to the condenser 33 and then connected to the material inlet of the liquid separation tank 34, the liquid-phase outlet of the liquid separation tank 34 is connected to the liquid-phase propylene inlet of the horizontal reactor through the propylene condensate pump 35, and the gas-phase outlet of the liquid separation tank 34 is connected to the gas-phase propylene inlet of the horizontal reactor 31 through the circulating gas fan 36;
a fourth polymerization reaction unit 4 comprising a horizontal reactor 41, a cyclone 42, a condenser 43, a liquid separation tank 44, a propylene condensate pump 45, and a circulating gas blower 46; wherein, the horizontal reactor 41 is provided with a material inlet, a gas phase outlet, a liquid phase propylene inlet, a gas phase propylene inlet and a mixed material outlet; the cyclone 42 is provided with a gas phase inlet, a gas phase outlet and a polymer outlet; the liquid separation tank 44 is provided with a material inlet, a liquid phase outlet and a gas phase outlet;
the polymer outlet of the cyclone 32 of the gas-phase polymerization unit 3 and the material outlet of the horizontal reactor 31 thereof are connected to the material inlet of the horizontal reactor 41 of the fourth polymerization unit 4, in the fourth polymerization unit 4, the gas-phase outlet of the horizontal reactor 41 is connected to the gas-phase inlet of the cyclone 42, the gas phase outlet of the cyclone 42 is connected to the condenser 43 of the unit, and then to the feed inlet of the unit liquid separation tank 44, the liquid phase outlet of the unit liquid separation tank 44 is connected to the liquid phase propylene inlet of the unit horizontal reactor 41 via a propylene condensate pump 45, the gas phase outlet of the unit liquid separation tank 44 is connected to the gas phase propylene inlet of the unit horizontal reactor 41 through a circulating gas fan 46, and the mixed material outlet of the fourth polymerization reaction unit 4 and the polymer outlet of the cyclone separator 42 are converged and connected to a downstream gas-solid separation system.
The process for producing the homo-polypropylene with wide molecular weight distribution and high crystallization comprises the following steps:
1. and (3) prepolymerization:
normal temperature liquid phase propylene (25 ℃, 3.5-4.5MPag) is cooled to 5-10 ℃ by propylene coolers 10, 10', and respectively enters prepolymerization reactors 11, 11', and prepolymerization is respectively carried out in the prepolymerization reactors 11, 11', wherein a catalyst system A capable of improving the molecular weight distribution of a polymer is added into the prepolymerization reactor 11, a catalyst system B capable of improving the crystallinity of the polymer is added into the prepolymerization reactor 11', and the catalysts are common catalysts in propylene polymerization.
The residence time of the catalyst in each prepolymerization reactor is 12-17min, the prepolymerization reactor adopts full-kettle operation, the catalyst and propylene are uniformly mixed through a stirrer, the reaction temperature is 22-28 ℃, and the pressure is 3.0-3.5 MPag.
2. Liquid phase polymerization:
the catalyst A, B passed through the prepolymerization reactor and unreacted propylene were fed into the liquid phase polymerization reactors 21 and 21', respectively, together with the newly fed liquid phase propylene.
The liquid phase polymerization reactors 21, 21' are operated at an operating temperature of 68-72 ℃ and an operating pressure of 2.8-3.4 MPag. The gas phase propylene at the top of the kettle is condensed by the propylene condensers 22 and 22', the polymerization reaction heat is removed, the condensed liquid phase propylene returns to the liquid phase polymerization reactors 21 and 21', and part of uncondensed noncondensable gas and hydrogen are returned to the liquid phase polymerization reactors 21 and 21' together by the circulating gas fan.
The liquid level of the liquid phase polymerization reactors 21 and 21' is controlled at 40-60%, and the liquid level is controlled through a kettle bottom discharge line. The feed leaving the liquid phase polymerization reactor 21, 21' contains 38-45% by weight of polymer, the remainder being propylene, hydrogen.
The liquid phase polymerization reactors 21, 21' employ vertical stirrers to ensure uniform mixing of the polymer and propylene.
Wherein the concentration of hydrogen in the gas phase of the liquid phase polymerization reactor 21 is 2 to 8 times the concentration of hydrogen in the gas phase of the liquid phase polymerization reactor 21'.
3. Gas-phase polymerization:
the material discharged from the liquid phase polymerization reactors 21, 21' enters the horizontal reactor 31 in the gas phase reaction zone, the operation temperature is 65-95 ℃, and the operation pressure is 2.4-2.8 MPag.
The gas-phase propylene at the top of the kettle enters a propylene condenser 33 after small-particle-size polymers are removed by a cyclone separator 32, the heat of polymerization reaction is removed, part of the condensed liquid-phase propylene and the supplemented liquid-phase propylene return to the horizontal reactor 31 through a propylene condensate pump 35, and part of uncondensed non-condensable gas and hydrogen enter the bottom of the horizontal reactor 31 through a circulating gas fan 36.
The material level in the horizontal reactor 31 is controlled to be 50-70%, and the material level is controlled through a material outlet line at the bottom of the kettle. The feed leaving the horizontal reactor 31 contains 75-85% wt of polymer, the remainder being propylene, hydrogen.
The horizontal reactor 31 is a horizontal stirred reactor with an expansion section to ensure uniform mixing of the polymer and propylene.
4. Fourth stage polymerization:
the material discharged from the horizontal reactor 31 in the gas phase polymerization stage enters the horizontal reactor 41 in the fourth polymerization reaction zone, the operation temperature is 65-95 ℃, and the operation pressure is 2.2-2.6 MPag.
The gas phase propylene at the top of the reactor enters a propylene condenser 43 after small-particle-size polymers are removed by a cyclone separator 42, the heat of polymerization reaction is removed, part of the condensed liquid phase propylene and the supplemented liquid phase propylene return to the horizontal reactor 41 through a propylene condensate pump 45, and part of uncondensed non-condensable gas and hydrogen enter the bottom of the horizontal reactor 41 through a circulating gas fan 46.
The material level of the horizontal reactor 41 is controlled to be 50-70%, and the material level is controlled through a material outlet line at the bottom of the kettle. The feed leaving the horizontal reactor 41 contains 75-85% wt of polymer, the remainder being propylene, hydrogen. The material leaving the horizontal reactor 41 completes the polymerization reaction and enters a gas-solid separation system.
The horizontal reactor 41 is a horizontal stirred reactor containing an expansion section to ensure uniform mixing of the polymer and propylene.
Example 2 the procedure for producing broad molecular weight distribution, high crystalline impact co-polypropylene is as follows:
normal temperature liquid phase propylene (25 ℃, 3.5-4.5MPag) is cooled to 5-10 ℃ by propylene coolers 10, 10', and respectively enters prepolymerization reactors 11, 11', and prepolymerization is respectively carried out in the prepolymerization reactors 11, 11', wherein a catalyst system A capable of improving the molecular weight distribution of a polymer is added into the prepolymerization reactor 11, a catalyst system B capable of improving the crystallinity of the polymer is added into the prepolymerization reactor 11', and the catalysts are common catalysts in propylene polymerization.
The residence time of the catalyst in each prepolymerization reactor is 12-17min, the prepolymerization reactor adopts full-kettle operation, the catalyst and propylene are uniformly mixed through a stirrer, the reaction temperature is 22-28 ℃, and the pressure is 3.0-3.5 MPag.
2. Liquid phase polymerization:
the catalyst A, B passed through the prepolymerization reactor and unreacted propylene were fed into the liquid phase polymerization reactors 21 and 21', respectively, together with the newly fed liquid phase propylene.
The liquid phase polymerization reactors 21, 21' are operated at an operating temperature of 68-72 ℃ and an operating pressure of 2.8-3.4 MPag. The gas phase propylene at the top of the kettle is condensed by the propylene condensers 22 and 22', the polymerization reaction heat is removed, the condensed liquid phase propylene returns to the liquid phase polymerization reactors 21 and 21', and part of uncondensed noncondensable gas and hydrogen are returned to the liquid phase polymerization reactors 21 and 21' together by the circulating gas fan.
The liquid level of the liquid phase polymerization reactors 21 and 21' is controlled at 40-60%, and the liquid level is controlled through a kettle bottom discharge line. The feed leaving the liquid phase polymerization reactor 21, 21' contains 38-45% by weight of polymer, the remainder being propylene, hydrogen.
The liquid phase polymerization reactors 21, 21' employ vertical stirrers to ensure uniform mixing of the polymer and propylene.
Wherein the concentration of hydrogen in the gas phase of the liquid phase polymerization reactor 21 is 2 to 8 times the concentration of hydrogen in the gas phase of the liquid phase polymerization reactor 21'.
3. Gas-phase polymerization:
the material discharged from the liquid phase polymerization reactors 21, 21' enters the horizontal reactor 31 in the gas phase reaction zone, the operation temperature is 65-95 ℃, and the operation pressure is 2.4-2.8 MPag.
The gas-phase propylene containing polymers at the top of the kettle enters a propylene condenser 33 after the polymers are removed by a cyclone separator 32, the heat of polymerization reaction is removed, the partially condensed liquid-phase propylene and the supplemented liquid-phase propylene return to the horizontal reactor 31 through a propylene condensate pump 35, and the partially uncondensed non-condensable gas and hydrogen enter the bottom of the horizontal reactor 31 through a circulating gas fan 36.
The material level in the horizontal reactor 31 is controlled to be 50-70%, and the material level is controlled through a material outlet line at the bottom of the kettle. The feed leaving the horizontal reactor 31 contains 75-85% wt of polymer, the remainder being propylene, hydrogen.
The horizontal reactor 31 is a horizontal stirred reactor with an expansion section to ensure uniform mixing of the polymer and propylene.
4. Fourth stage polymerization:
the material discharged from the horizontal reactor 31 in the gas phase polymerization stage enters the horizontal reactor 41 in the fourth polymerization reaction zone, the operation temperature is 65-95 ℃, and the operation pressure is 2.2-2.6 MPag.
The gas phase propylene containing the polymer at the top of the kettle enters a propylene condenser 43 after the polymer is removed by a cyclone separator 42, the heat of polymerization reaction is removed, part of the condensed liquid phase propylene and the supplemented liquid phase propylene return to the horizontal reactor 41 through a propylene condensate pump 45, and part of the uncondensed non-condensable gas enters the bottom of the horizontal reactor 41 through a circulating gas fan 46 together with newly added hydrogen and ethylene.
The material level of the horizontal reactor 41 is controlled to be 50-70%, and the material level is controlled through a material outlet line at the bottom of the kettle. The feed leaving the horizontal reactor 41 contains 75-85% wt of polymer, the remainder being propylene, hydrogen. The material leaving the horizontal reactor 41 completes the polymerization reaction and enters a gas-solid separation system.
The horizontal reactor 41 is a horizontal stirred reactor containing an expansion section to ensure uniform mixing of the polymer and propylene.
According to the invention, hydrogen is added according to the requirements of polymer molecular weight and melt index, and ethylene or butylene is also added into the fourth stage gas phase polymerization reactor when random copolymerization polypropylene is produced; in the production of impact co-polypropylene, the fourth stage gas phase polymerization reactor requires the addition of ethylene.
Claims (12)
1. A multistage polymerization process for propylene comprising the steps of:
1) prepolymerization reaction
Setting two liquid-phase prepolymerization reaction zones connected in parallel, mixing and stirring two paths of catalysts and liquid-phase propylene cooled to 5-10 ℃ in the two prepolymerization reaction zones respectively, and carrying out prepolymerization reaction at 22-28 ℃ and 3.0-3.5MPag for 12-17 min;
2) liquid phase polymerization
Two liquid phase reaction zones connected in parallel are arranged, the reaction materials from the prepolymerization zone and the newly supplemented liquid phase propylene are respectively sent into the two liquid phase reaction zones for liquid phase polymerization reaction, the reaction temperature is 68-72 ℃, and the pressure is 2.8-3.4 MPag;
the polymerization heat gasifies the liquid-phase propylene in the reactor, the gas-phase propylene is discharged from the upper part of the reactor of the two liquid-phase reaction areas, and the gas-phase propylene returns to the corresponding reactor again after being condensed and separated, and the non-condensable gas after being separated is mixed with the hydrogen and then returns to the corresponding reactor;
discharging a mixed material from the lower part of the reactor of the two liquid-phase reaction zones, wherein the mass fraction of the polymer in the mixed material is 38-45%, and the liquid level in the reactor is controlled at 40-60%;
3) gas phase polymerization
The mixed material from the liquid phase reaction zone enters a gas phase polymerization reaction zone reactor to carry out gas phase polymerization reaction, the reaction temperature is 65-100 ℃, and the pressure is 2.4-2.8 MPag;
discharging gas-phase propylene containing polymers from the upper part of a gas-phase polymerization zone reactor, reducing gas-phase flow velocity through expansion and carrying out cyclone separation, after the polymers are separated out, condensing and separating the gas-phase propylene, removing polymerization reaction heat to obtain liquid-phase propylene, and feeding the liquid-phase propylene back to the reactor of the gas-phase polymerization zone, wherein the reaction temperature is controlled to be 65-100 ℃;
the non-condensable gas after the gas phase propylene is subjected to liquid separation is mixed with hydrogen and then returns to a reactor of the gas phase polymerization reaction zone; discharging a mixed material from the lower part of the reactor, wherein the mass fraction of the polymer in the mixed material is 75-85%, and the material level is controlled at 50-70%;
4) fourth stage polymerization
Feeding the mixed material discharged from the lower part of the reactor in the gas-phase polymerization reaction zone in the step 3) and the separated polymer into a reactor in a fourth gas-phase polymerization reaction zone for polymerization reaction at the temperature of 65-100 ℃ and the pressure of 2.2-2.6 MPag;
discharging gas-phase propylene containing polymers from the upper part of a reactor in a fourth gas-phase polymerization reaction zone, reducing the gas-phase flow rate through expansion and carrying out cyclone separation, after separating the polymers, condensing and separating the gas-phase propylene, removing the polymerization reaction heat, returning the obtained liquid-phase propylene to the reactor in the fourth gas-phase polymerization reaction zone, and controlling the reaction temperature to be 65-100 ℃;
and (3) mixing the non-condensable gas after the liquid separation of the gas-phase propylene with hydrogen, and then feeding the mixture back to a reactor in a fourth gas-phase polymerization reaction zone, wherein a mixed material is discharged from the lower part of the reactor, the mass fraction of the polymer in the mixed material is 75-85%, and the material level is controlled to be 50-70%.
2. The multistage polymerization process of propylene according to claim 1, wherein in step 1), the catalysts in the two prepolymerization zones are different.
3. The multistage polymerization process for propylene according to claim 1, wherein the liquid level in each of the reactors in the two reaction zones in step 2) is controlled to 48 to 56%.
4. The multistage polymerization process for propylene according to claim 1, wherein in the step 2), after the gas phase propylene is condensed, the supplemented ethylene is returned to the liquid phase reactor together with the noncondensable gas and hydrogen.
5. The multistage polymerization process of propylene according to claim 1 or 4, wherein in the step 2), after the gas phase propylene is condensed, the make-up butene is returned to the liquid phase reactor together with the liquid phase propylene.
6. The multistage polymerization process for propylene according to claim 1, wherein in step 3) and/or 4), after the condensation of the propylene in the gas phase, the ethylene is fed back to the reactor together with the non-condensable gas and hydrogen.
7. The multistage polymerization process of propylene according to claim 1 or 6, wherein in step 3) and/or step 4), additional butene or liquid-phase propylene is returned to the reactor with the liquid-phase propylene.
8. A multistage polymerization apparatus for propylene, comprising:
the prepolymerization reaction unit comprises two prepolymerization reactors which are arranged in parallel, and the prepolymerization reactors are provided with a material inlet and a material outlet;
the liquid phase polymerization reaction unit comprises two liquid phase polymerization reactors, two propylene condensers, two liquid separation tanks and two circulating air blowers, wherein the two liquid phase polymerization reactors, the two propylene condensers, the two liquid separation tanks and the two circulating air blowers are respectively and correspondingly arranged with the two prepolymerization reactors; wherein the liquid phase polymerization reactor is provided with a material inlet, a material outlet, a gas phase propylene outlet, a liquid phase propylene inlet and a gas phase propylene inlet; the liquid separation tank is provided with a material inlet, a liquid phase outlet and a gas phase outlet;
the material outlet of the prepolymerization reactor is connected with the material inlet of the liquid phase polymerization reactor, the gas phase propylene outlet of the liquid phase polymerization reactor is connected with the propylene condenser and then connected with the material inlet of the liquid separation tank, the liquid phase outlet of the liquid separation tank is connected with the liquid phase propylene inlet of the liquid phase polymerization reactor, and the gas phase outlet of the liquid separation tank is connected with the gas phase propylene inlet of the liquid phase polymerization reactor through a circulating gas fan;
the gas-phase polymerization reaction unit comprises a horizontal reactor, a cyclone separator, a condenser, a liquid separation tank, a propylene condensate pump and a circulating gas fan; wherein the horizontal reactor is provided with two material inlets, a gas phase outlet, a liquid phase propylene inlet, a gas phase propylene inlet and a mixed material outlet; the cyclone separator is provided with a gas phase inlet, a gas phase outlet and a polymer outlet; the liquid separation tank is provided with a material inlet, a liquid phase outlet and a gas phase outlet; wherein,
the material outlets of the two liquid-phase polymerization reactors are respectively connected to the two material inlets of the horizontal reactor, the gas-phase outlet of the horizontal reactor is connected to the gas-phase inlet of the cyclone separator, the gas-phase outlet of the cyclone separator is connected with the condenser and then connected to the material inlet of the liquid separating tank, the liquid-phase outlet of the liquid separating tank is connected to the liquid-phase propylene inlet of the horizontal reactor through a propylene condensate pump, and the gas-phase outlet of the liquid separating tank is connected to the gas-phase propylene inlet of the horizontal reactor through a circulating gas fan;
the fourth polymerization reaction unit comprises a horizontal reactor, a cyclone separator, a condenser, a liquid separation tank, a propylene condensate pump and a circulating gas fan; wherein the horizontal reactor is provided with a material inlet, a gas phase outlet, a liquid phase propylene inlet, a gas phase propylene inlet and a mixed material outlet; the cyclone separator is provided with a gas phase inlet, a gas phase outlet and a polymer outlet; the liquid separation tank is provided with a material inlet, a liquid phase outlet and a gas phase outlet;
the gas-phase polymerization unit cyclone separator comprises a gas-phase polymerization unit cyclone separator, a gas-phase reactor, a condenser, a unit liquid separation tank, a circulating gas fan, a gas-phase reactor material inlet, a gas-phase reactor material outlet.
9. The multistage polymerization device for propylene according to claim 8, wherein the prepolymerization unit further comprises a propylene cooler disposed corresponding to the prepolymerization reactor, and the propylene cooler is connected to the material inlet of the prepolymerization reactor.
10. The multistage polymerization apparatus for propylene according to claim 8, wherein a gas-phase outlet line of each of the liquid-phase polymerization reaction unit, the gas-phase polymerization reaction unit and the fourth polymerization reaction unit is further provided with a line for replenishing ethylene.
11. The multistage polymerization apparatus for propylene according to claim 8 or 10, wherein a line for replenishing butene is further provided in a liquid phase outlet line of each liquid separation tank of the liquid phase polymerization reaction unit.
12. The multistage polymerization apparatus for propylene according to claim 10 or 11, wherein a line for replenishing butene and/or liquid-phase propylene is further provided in the liquid-phase outlet line of each of the liquid separation tanks in the gas-phase polymerization unit and the fourth polymerization unit.
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| CN108586644A (en) * | 2018-06-13 | 2018-09-28 | 浙江卫星能源有限公司 | A kind of multi-stage polymeric process and device of propylene |
| CN108794669A (en) * | 2018-06-13 | 2018-11-13 | 浙江卫星能源有限公司 | A kind of multi-stage polymeric process and device of propylene |
| CN108976329A (en) * | 2018-06-13 | 2018-12-11 | 浙江卫星能源有限公司 | A kind of multi-stage polymeric process and device of propylene |
| CN111116785A (en) * | 2019-12-27 | 2020-05-08 | 浙江卫星能源有限公司 | Propylene polymerization method and apparatus |
| CN111892673A (en) * | 2020-06-17 | 2020-11-06 | 南京延长反应技术研究院有限公司 | Micro-interface enhanced reaction system and method for preparing polypropylene |
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