CN112724300A - Condensation state production process of hexene copolymerized high density polyethylene drawing material - Google Patents
Condensation state production process of hexene copolymerized high density polyethylene drawing material Download PDFInfo
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Abstract
A condensation-state production process of a hexene copolymerized high-density polyethylene drawing material, belonging to the field of polyolefin production. The method is characterized in that: adopting a gas phase polyethylene process, and reacting under the action of a catalyst to generate polyethylene resin; the method specifically comprises the following steps: (1) switching products; (2) adjusting the reduction ratio; (2) reducing the addition of hexene to adjust the hexene concentration to 0.5-1.2% of the target concentration; (3) reducing the adding amount of hydrogen; (4) increasing the addition of fresh refrigerant; (5) extracting ethylene to 800-1000 kPa; (6) the height of the fluidized bed was adjusted to be set at 11.8 to 13 m. The invention realizes the hexene copolymerization high-density wire drawing material development of the gas-phase fluidized bed process device in a condensation state, eliminates the operation bottleneck of the device, solves the problems of difficult catalyst feeding, reaction temperature fluctuation, back flushing pipeline blockage, difficult granulation start and the like in the condensation state, and realizes the long-period operation of the device.
Description
Technical Field
A condensation-state production process of a hexene copolymerized high-density polyethylene drawing material, belonging to the field of polyolefin production.
Background
Most of domestic similar products are produced by a slurry process, the production difficulty of the products is high in a gas-phase fluidized bed process, and the production of high-density polyethylene wire drawing material products in a gas-phase process condensation state is not precedent in China.
With the continuous expansion of domestic polyethylene capacity, the general grades of DFDA7042 and the like produced by Linear Low Density Polyethylene (LLDPE) devices gradually lose market competitive advantages, the profit space is continuously reduced, and the adjustment and optimization of the device product structure are particularly urgent. The benefit of the high-density polyethylene wire-drawing material product is far higher than that of the general grade of linear polyethylene. In order to improve the product competitiveness, optimize the product structure and realize that the gas-phase fluidized bed device can adjust the product at any time according to the market demand. The condensed hexene copolymerized high-density polyethylene drawing material technology is developed on an LLDPE device and is industrially produced, and the production of full-density products of the device is imperative.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the condensation-state production process of the hexene copolymerized high-density polyethylene wiredrawing material overcomes the defects of the prior art, realizes that the hexene copolymerized high-density wiredrawing material is generated by a gas-phase fluidized bed process device in a condensation state, and eliminates the operation bottleneck of the device.
The technical scheme adopted by the invention for solving the technical problems is as follows: the condensation state production process of the hexene copolymerized high-density polyethylene drawing material is characterized by comprising the following steps of: introducing ethylene, hydrogen and a comonomer into a gas-phase fluidized bed reactor by adopting a gas-phase polyethylene process, and reacting under the action of a catalyst to generate polyethylene resin; the method specifically comprises the following steps:
(1) switching a production path from a medium-density product to a high-density product;
(2) the product load is controlled according to the design load of 80 percent;
(3) adjusting the reduction ratio, and stopping adding the diethyl aluminum monochloride;
(4) the reaction begins to switch, and the hexene concentration is adjusted to 0.5 to 1.2 percent by reducing the hexene addition;
(5) reducing the adding amount of hydrogen, and adjusting the concentration of the hydrogen to 7-9% of the target concentration;
(6) increasing the addition of fresh refrigerant, and adjusting the concentration of the refrigerant to 12-15% of the target concentration;
(7) extracting ethylene to 800-1000 kPa;
(8) the height of the fluidized bed was adjusted to be set at 11.8 to 13 m.
The production of the high-density product adopts hexene as a comonomer, improves the tensile strength and the fracture nominal strain performance of the product, solves the technical obstacle that the high-density polyethylene wiredrawing material is produced in a gas-phase fluidized bed process, successfully solves the technical obstacle that the high-density polyethylene wiredrawing material can only be produced in a slurry process and cannot be produced in the gas-phase fluidized bed process, and realizes the stable production of the polyethylene in a gas-phase fluidized bed in a condensation state. Aiming at the problem that the high-density product for the linear polyethylene device extrusion granulator is difficult to drive, the successful driving and the stable operation of the granulator set are realized by adopting measures of driving, filling and pulling the low-density product (preferably DFDA7042 powder), switching the high-density product for transition after the driving is stable and the like. The method realizes the hexene copolymerization high-density wire drawing material development of the gas-phase fluidized bed process device in a condensation state, eliminates the operation bottleneck of the device, solves the problems of difficult catalyst feeding, reaction temperature fluctuation, back flushing pipeline blockage, difficult granulation start and the like in the condensation state, and realizes the long-period operation of the device.
The melt index of the medium-density product is 4.0g/10min, and the density of the medium-density product is 0.940g/cm 3.
The catalyst is a titanium slurry catalyst, the aluminum/titanium ratio can influence the molecular weight distribution of the product, and the molar ratio of aluminum to titanium in the catalyst is 50: 1.
The catalyst activity of the catalyst is 17000-23000 kg/kg.
The reaction pressure in the gas-phase fluidized bed is controlled to be 1.95-2.05MPa, and the ethylene partial pressure is more than or equal to 0.8 MPa.
The reaction temperature in the gas-phase fluidized bed is controlled to be 80-105 ℃.
The molar ratio of the hydrogen to the ethylene is (0.18-0.23) to 1; the hexene/ethylene molar ratio is (0.01-0.03) to 1.
The circulating gas in the gas-phase fluidized bed reactor comprises the following components: 38-43% of ethylene, 0.5-1.0% of hexene, 7.8-8.5% of hydrogen, 12-16% of isopentane and the balance of nitrogen.
In the reaction process of the gas-phase fluidized bed reactor, 5% of the cooler tube bundle is sealed, the quantity of the discharged back-blowing gas is improved by 7% compared with that before adjustment, the reaction inlet temperature of the gas-phase fluidized bed reactor is controlled to be lower than the dew point for operation by 5-10 ℃, and the fluctuation of the inlet temperature is controlled to be less than 2 ℃.
The reaction discharging balance pipeline is too low at the opening of the reactor, the balance pipeline is easy to store materials and generate caking, 5% of cooler tube bundles are sealed, the discharging back-blowing air quantity is increased by about 7%, and the caking of the discharging pipeline can be effectively reduced. Reaction temperature PID control parameters are optimized, the reaction inlet temperature is controlled to be lower than the dew point for operation by 5-10 ℃, and the inlet temperature fluctuation is controlled to be less than 2 ℃.
Compared with the prior art, the invention has the beneficial effects that:
the production of the high-density product adopts hexene as a comonomer, improves the tensile strength and the fracture nominal strain performance of the product, solves the technical obstacle that the high-density polyethylene wiredrawing material is produced in a gas-phase fluidized bed process, successfully solves the technical obstacle that the high-density polyethylene wiredrawing material can only be produced in a slurry process and cannot be produced in the gas-phase fluidized bed process, and realizes the stable production of the polyethylene in a gas-phase fluidized bed in a condensation state. Aiming at the problem that the high-density product for the linear polyethylene device extrusion granulator is difficult to drive, the successful driving and the stable operation of the granulator set are realized by adopting measures of driving, filling and pulling the low-density product (preferably DFDA7042 powder), switching the high-density product for transition after the driving is stable and the like. The method realizes the hexene copolymerization high-density wire drawing material development of the gas-phase fluidized bed process device in a condensation state, eliminates the operation bottleneck of the device, solves the problems of difficult catalyst feeding, reaction temperature fluctuation, back flushing pipeline blockage, difficult granulation start and the like in the condensation state, and realizes the long-period operation of the device.
Drawings
FIG. 1 is a schematic view of a gas-phase fluidized-bed reaction scheme.
Wherein, 1, a recovery system 2, a mixing unit 3, a butene and hexene conveying pipe.
Detailed Description
Fig. 1 shows a preferred embodiment of the present invention, which is further described below with reference to fig. 1.
Referring to figure 1: the condensation state production process of hexene copolymerized high density polyethylene drawing material adopts Unipol gas phase method polyethylene process, and ethylene, hydrogen and comonomer are introduced into a gas phase fluidized bed reactor and react under the action of catalyst to generate polyethylene resin; the method specifically comprises the following steps:
(1) switching a production path from a medium-density product to a high-density product; the production of the product is switched by adopting a low-density product (preferably DFDA7042 powder) to fill and draw the material during driving, and the medium-density product is switched to the high-density product; the melting index of the medium-density product is 4.0g/10min, and the density is 0.940g/cm 3;
(2) the product load is controlled according to the design load of 80 percent;
(3) adjusting the reduction ratio, and stopping adding the diethyl aluminum monochloride;
(4) the reaction begins to switch, and the hexene concentration is adjusted to 0.5 to 1.2 percent by reducing the hexene addition;
(5) reducing the adding amount of hydrogen, and adjusting the concentration of the hydrogen to 7-9% of the target concentration;
(6) increasing the addition of fresh refrigerant, and adjusting the concentration of the refrigerant to 12-15% of the target concentration;
(7) by means of reducing the discharging time, pulling the standby catalyst injection pipe and the like, the ethylene partial pressure is extracted to 800-1000 kPa;
(8) the height of the fluidized bed was adjusted to be set at 11.8 to 13 m.
The catalyst is a titanium slurry catalyst, the aluminum/titanium ratio can influence the molecular weight distribution of the product, and the molar ratio of aluminum to titanium in the catalyst is 50: 1. The catalyst activity of the catalyst is 17000-23000 kg/kg. The reaction pressure in the gas-phase fluidized bed is controlled to be 1.95-2.05MPa, and the ethylene partial pressure is more than or equal to 0.8 MPa. The reaction temperature in the gas-phase fluidized bed is controlled to be 80-105 ℃.
The molar ratio of hydrogen to ethylene is (0.18-0.23) to 1; the hexene/ethylene molar ratio is (0.01-0.03) to 1. Cycle gas composition in gas phase fluidized bed reactor: 38-43% of ethylene, 0.5-1.0% of hexene, 7.8-8.5% of hydrogen, 12-16% of isopentane and the balance of nitrogen.
The copolymerized high-density monofilament polyethylene resin produced by the invention comprises the following components: the density is 0.948-0.954g/cm3Preferably 0.950 to 0.952g/cm3The melt mass flow rate is from 0.7 to 1.3g/10min (measured at 190 ℃ C. under 2.16 Kg), preferably from 0.9 to 1.1g/10 min. The monofilament lipid comonomer is hexene. Photovoltaic bucket resin: the weight average molecular weight is 11-13 ten thousand, and the number average molecular weight is 2.0-3.0 ten thousand; the ratio of Mw/Mn is preferably 3.7 to 5.5.
The invention mainly solves the bottleneck of producing the hexene copolymerized high-density polyethylene product in a condensation state by a gas-phase fluidized bed process, and realizes stable production. The product has high tensile strength and impact strength, good nominal strain at break, and high knot breaking strength and single wire breaking strength meeting the first-grade index requirements of the industry.
The invention is implemented in a linear low-density polyethylene device, realizes the production of full-density polyethylene in a condensation state, and realizes the high-end and customized transformation of the device towards products. The product produced by the invention has good tensile strength and nominal strain performance at break, and is widely applied to the fields of rope nets, fishing nets and the like.
The materials enter a gas-phase fluidized bed reactor C-4001 through a feeding system to carry out polymerization reaction, and the produced powder products are subjected to hydrocarbon substance removal through a degassing bin C-5009 and enter an extrusion granulator set for granulation and molding. In the reaction process of the gas-phase fluidized bed reactor, 5% of the cooler tube bundle is sealed, the quantity of the discharged back-blowing gas is improved by 7% compared with that before adjustment, the reaction inlet temperature of the gas-phase fluidized bed reactor is controlled to be lower than the dew point for operation by 5-10 ℃, and the fluctuation of the inlet temperature is controlled to be less than 2 ℃.
Table 1 example data
The production of the high-density product adopts hexene as a comonomer, improves the tensile strength and the fracture nominal strain performance of the product, solves the technical obstacle of the production of the high-density polyethylene wiredrawing material in a gas-phase fluidized bed process, and realizes the stable production in a condensation state of the gas-phase fluidized bed polyethylene process.
The invention develops a 'undisturbed switching of comonomer' process, solves the temperature fluctuation in the comonomer switching process: when the comonomer of the original linear polyethylene device is switched from butene to hexene, the butene in the comonomer feeding buffer system needs to be emptied, and the hexene is added, so that the reaction temperature is easy to fluctuate during operation, and material loss is caused at the same time. The flow optimization among the devices is implemented, a high-density polyethylene device is newly added to convey a hexene pipeline to a linear device, the high-density device conveys hexene, the linear device carries out charging control, the rapid adjustment and conversion of the reaction environment are realized, and a disturbance-free switching technology of butene and hexene is obtained, so that the temperature fluctuation during comonomer switching is solved, and the loss of comonomer discharge is reduced.
The invention develops a slurry catalyst feeding technology and carries out screening and optimization of the catalyst, namely, a catalyst feeding system is modified, the heat tracing temperature of the system is controlled to be 40-60 ℃, and a nitrogen injection port is adjusted to the tail end of the feeding system, so that the stable feeding of the slurry catalyst is realized all day long; the optimization of the on-line reduction scheme is carried out to realize stable operation of the slurry catalyst under the full density grade.
The invention develops a reaction control technology of a condensed high-density polyethylene wire drawing material and a circulating gas re-splitting technology: (1) the activity of the slurry catalyst is controlled to be 17000-23000 kg/kg, preferably 21000 kg/kg. (2) The recycling gas comprises 38-43% of ethylene, 0.5-1.0% of hexene, 7.8-8.5% of hydrogen, 12-16% of isopentane and the balance of nitrogen. (3) The reaction discharging balance pipeline is too low at the opening of the reactor, the balance pipeline is easy to store materials and generate caking, 5% of cooler tube bundles are sealed, the discharging back-blowing air quantity is increased by about 7%, and the caking of the discharging pipeline can be effectively reduced. (4) Reaction temperature PID control parameters are optimized, the reaction inlet temperature is controlled to be lower than the dew point for operation by 5-10 ℃, and the inlet temperature fluctuation is controlled to be less than 2 ℃.
The invention develops a granulation technology of a high-density polyethylene wiredrawing material: aiming at the problem that the high-density product for the linear polyethylene device extrusion granulator is difficult to drive, the successful driving and the stable operation of the granulator set are realized by adopting measures of driving, filling and pulling the low-density product (preferably DFDA7042 powder), switching the high-density product for transition after the driving is stable and the like.
The invention realizes the hexene copolymerization high-density wire drawing material under the condensation state of a gas-phase fluidized bed process device. The invention eliminates the operation bottleneck of the device, solves the problems of difficult catalyst feeding, reaction temperature fluctuation, back flushing pipeline blockage, difficult granulation start and the like in a condensation state, and realizes long-period operation of the device.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (9)
1. The condensation state production process of the hexene copolymerized high-density polyethylene drawing material is characterized by comprising the following steps of: introducing ethylene, hydrogen and a comonomer into a gas-phase fluidized bed reactor by adopting a gas-phase polyethylene process, and reacting under the action of a catalyst to generate polyethylene resin; the polymerization production specifically comprises the following steps:
(1) switching a production path from a medium-density product to a high-density product;
(2) the product load is controlled according to the design load of 80 percent;
(3) adjusting the reduction ratio, and stopping adding the diethyl aluminum monochloride;
(4) the reaction begins to switch, and the hexene concentration is adjusted to 0.5 to 1.2 percent by reducing the hexene addition;
(5) reducing the adding amount of hydrogen, and adjusting the concentration of the hydrogen to 7-9% of the target concentration;
(6) increasing the addition of fresh refrigerant, and adjusting the concentration of the refrigerant to 12-15% of the target concentration;
(7) extracting ethylene to 800-1000 kPa;
(8) the height of the fluidized bed was adjusted to be set at 11.8 to 13 m.
2. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: the melt index of the medium-density product is 4.0g/10min, and the density of the medium-density product is 0.940g/cm 3.
3. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: the catalyst is a titanium slurry catalyst, and the molar ratio of aluminum to titanium in the catalyst is 50: 1.
4. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 3, characterized in that: the catalyst activity of the catalyst is 17000-23000 kg/kg.
5. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: the reaction pressure in the gas-phase fluidized bed is controlled to be 1.95-2.05MPa, and the ethylene partial pressure is more than or equal to 0.8 MPa.
6. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: the reaction temperature in the gas-phase fluidized bed is controlled to be 80-105 ℃.
7. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: the molar ratio of the hydrogen to the ethylene is (0.18-0.23) to 1; the hexene/ethylene molar ratio is (0.01-0.03) to 1.
8. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: the circulating gas in the gas-phase fluidized bed reactor comprises the following components: 38-43% of ethylene, 0.5-1.0% of hexene, 7.8-8.5% of hydrogen, 12-16% of isopentane and the balance of nitrogen.
9. The condensation state production process of the hexene copolymerized high density polyethylene drawing material according to claim 1, characterized in that: in the reaction process of the gas-phase fluidized bed reactor, 5% of the cooler tube bundle is sealed, the quantity of the discharged back-blowing gas is improved by 7% compared with that before adjustment, the reaction inlet temperature of the gas-phase fluidized bed reactor is controlled to be lower than the dew point for operation by 5-10 ℃, and the fluctuation of the inlet temperature is controlled to be less than 2 ℃.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113480683A (en) * | 2021-06-04 | 2021-10-08 | 中国神华煤制油化工有限公司 | Polymerization switching process for producing polyethylene |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105254782A (en) * | 2015-10-14 | 2016-01-20 | 中国石油化工股份有限公司 | Gas-phase fluidized bed polyethylene condensation state technology for non-disturbance starting and quitting of induced condensing operation |
| CN109627368A (en) * | 2017-10-09 | 2019-04-16 | 中国石油化工股份有限公司 | A kind of production technology of polyethylene wire drawing material product |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105254782A (en) * | 2015-10-14 | 2016-01-20 | 中国石油化工股份有限公司 | Gas-phase fluidized bed polyethylene condensation state technology for non-disturbance starting and quitting of induced condensing operation |
| CN109627368A (en) * | 2017-10-09 | 2019-04-16 | 中国石油化工股份有限公司 | A kind of production technology of polyethylene wire drawing material product |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113480683A (en) * | 2021-06-04 | 2021-10-08 | 中国神华煤制油化工有限公司 | Polymerization switching process for producing polyethylene |
| CN113480683B (en) * | 2021-06-04 | 2022-12-27 | 中国神华煤制油化工有限公司 | Polymerization switching process for producing polyethylene |
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