CN118788247B - Polyethylene preparation system - Google Patents
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- CN118788247B CN118788247B CN202411270752.XA CN202411270752A CN118788247B CN 118788247 B CN118788247 B CN 118788247B CN 202411270752 A CN202411270752 A CN 202411270752A CN 118788247 B CN118788247 B CN 118788247B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F10/00—Homopolymers and copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
- C08F10/02—Ethene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D11/00—Solvent extraction
- B01D11/04—Solvent extraction of solutions which are liquid
- B01D11/0488—Flow sheets
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/009—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping in combination with chemical reactions
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D3/00—Distillation or related exchange processes in which liquids are contacted with gaseous media, e.g. stripping
- B01D3/14—Fractional distillation or use of a fractionation or rectification column
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/001—Controlling catalytic processes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
- B01J8/08—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles
- B01J8/10—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes with moving particles moved by stirrers or by rotary drums or rotary receptacles or endless belts
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Abstract
本发明涉及聚乙烯制备技术领域，尤其涉及一种聚乙烯制备系统，包括：聚合模块，用以将乙烯聚合以输出成品聚乙烯；检测模块，其与所述聚合模块相连，用以对聚乙烯的制备过程的加工参数进行检测；控制模块，其分别与所述聚合模块和检测模块相连，用以根据反应器中温度的波动幅度的方差判定聚乙烯制备的稳定性是否符合要求，在不符合要求时调节反应器中搅拌轴的电机转速或根据蒸馏塔的进料管道内部的平均压力调节聚乙烯混合物的进料速度，以及，根据所述蒸馏塔的进料管道内部的平均压力和成品聚乙烯中催化剂的含量调节反应器中搅拌桨的竖直高。本发明提高了聚乙烯制备的稳定性。
The present invention relates to the technical field of polyethylene preparation, and in particular to a polyethylene preparation system, comprising: a polymerization module for polymerizing ethylene to output finished polyethylene; a detection module connected to the polymerization module for detecting processing parameters of the polyethylene preparation process; a control module connected to the polymerization module and the detection module respectively for determining whether the stability of polyethylene preparation meets the requirements according to the variance of the temperature fluctuation amplitude in the reactor, and adjusting the motor speed of the stirring shaft in the reactor or adjusting the feeding speed of the polyethylene mixture according to the average pressure inside the feeding pipeline of the distillation tower when it does not meet the requirements, and adjusting the vertical height of the stirring paddle in the reactor according to the average pressure inside the feeding pipeline of the distillation tower and the content of the catalyst in the finished polyethylene. The present invention improves the stability of polyethylene preparation.
Description
Technical Field
The invention relates to the technical field of polyethylene preparation, in particular to a polyethylene preparation system.
Background
Polyethylene (Polyethylene) is a common polymer in the prior art and is widely used in the production of plastic articles. The preparation of polyethylene is generally achieved by polymerizing Ethylene monomer (Ethylene), which is mainly two of high pressure tube process and kettle process. Therefore, it is important to control the production process of polyethylene, and a production system of polyethylene is required to improve the quality and stability of the production of polyethylene.
The Chinese patent application publication No. CN117304599A discloses a high-density polyethylene material for a nuclear power system pipeline and a preparation method thereof, and the method comprises the following steps of S1, mixing nano ZnO, modified magnesium hydroxide, modified basalt fiber, aragonite type calcium carbonate whisker, an antioxidant, a heat-resistant agent, a radiation-resistant agent and HDPE according to a specific weight ratio, pretreating by a high-speed stirrer to ensure uniform dispersion, stirring for about 30 minutes, S2, putting the pretreated mixture into a double-screw extruder for heating and melting treatment, heating the mixture to 180-200 ℃ and continuously stirring for about 2 hours in the melting process, S3, extruding and molding by using a single-screw extruder at an extruding speed of 5-10 mm/S and an extruding pressure of 10-20 MPa, S4, cooling and solidifying the extruded or injection molded product for about 2 hours, and then performing a post-treatment process to obtain the high-density polyethylene material pipeline. Therefore, the high-density polyethylene material for the nuclear power system pipeline and the preparation method thereof have the problems that the heating temperature cannot reach the preset temperature due to the aging of the heating element of the heating device in the reactor, and further, the ethylene and the catalyst cannot be uniformly mixed, so that the stability of polyethylene preparation is reduced.
Disclosure of Invention
Therefore, the invention provides a polyethylene preparation system, which is used for solving the problem that the heating temperature cannot reach the preset temperature due to the aging of a heating element of a heating device in a reactor in the prior art, so that ethylene and a catalyst cannot be uniformly mixed, and the stability of polyethylene preparation is reduced.
In order to achieve the above object, the invention provides a polyethylene preparation system, comprising a polymerization module, a forming unit, a detection module, a control module and a stirring module, wherein the polymerization module is used for polymerizing ethylene to output finished polyethylene, the reaction module comprises a reaction unit used for carrying out mixed reaction on the ethylene and a catalyst to output a polyethylene mixture, the forming unit is connected with the reaction unit and used for carrying out distillation separation on the polyethylene mixture to output polyethylene fractionation and byproducts, the extraction unit is connected with the distillation unit and used for extracting the polyethylene fractionation to output polyethylene extraction and impurities, the forming unit is used for carrying out processing forming on the polyethylene extraction to output finished polyethylene, the reaction unit comprises a reactor used for providing a reaction place, the distillation unit comprises a distillation tower connected with the reactor and used for carrying out separation on the polyethylene mixture, the forming unit comprises an extruder connected with the distillation tower and used for carrying out extrusion forming on the polyethylene extraction, the detection module is connected with the distillation unit and used for detecting processing parameters of a preparation process of the polyethylene, the control module is respectively connected with the polymerization module and the detection module and used for carrying out the detection of the polyethylene fractionation, the detection module is used for judging whether the average temperature of the polyethylene in the reactor meets the stirring tower is required by the stirring speed of the polyethylene in the reactor, and the reactor is required to be stirred or the stirring tower is not stirred, and the average or the stirring speed of the finished polyethylene is required to be stirred or the stirring tower is required to be regulated according to the average or the average pressure in the stirring speed is in the reactor is required to the stirring tower is in the reactor is required, and the stirring is required to be stirred.
Further, the detection module includes:
A temperature sensor connected to the reactor for detecting a temperature in the reactor;
A pressure sensor connected to the feed pipe for detecting the pressure inside the feed pipe;
and the X-ray fluorescence spectrometer is arranged at the output end of the extruder and used for detecting the content of the catalyst in the finished polyethylene.
Further, the processing parameters include the temperature in the reactor, the pressure inside the feed conduit, and the catalyst content in the finished polyethylene.
Further, the control module obtains the temperature of the reactor in a plurality of heating periods, calculates the variance of the fluctuation range of the temperature in the reactor, and judges that the stability of the polyethylene preparation does not meet the requirement if the variance of the fluctuation range of the temperature in the reactor is larger than a preset first variance;
And when the variance of the fluctuation amplitude of the temperature in the reactor is larger than the preset first variance and smaller than or equal to the preset second variance, the control module preliminarily judges that the separation effectiveness of the polyethylene mixture is not in accordance with the requirement, and secondarily judges whether the separation effectiveness of the polyethylene mixture is in accordance with the requirement according to the average pressure in the feeding pipeline.
Further, the control module increases the motor speed of the stirring shaft when the variance of the fluctuation amplitude of the temperature in the reactor is greater than the preset second variance;
The increasing amplitude of the motor rotation speed of the stirring shaft is determined by the difference value between the variance of the fluctuation amplitude of the temperature in the reactor and the preset second variance.
Further, the control module obtains the pressure inside the feeding pipeline of the distillation tower in a plurality of conveying periods, calculates the average pressure inside the feeding pipeline, and secondarily judges that the separation effectiveness of the polyethylene mixture is not in accordance with the requirement if the average pressure inside the feeding pipeline is larger than the preset first pressure.
Further, the control module preliminarily judges that the effectiveness of extraction is not satisfactory when the average pressure inside the feeding pipeline is larger than a preset second pressure, and judges secondarily whether the effectiveness of extraction is satisfactory according to the content of the catalyst in the finished polyethylene.
Further, the control module increases the feeding speed of the polyethylene mixture when the average pressure inside the feeding pipeline is greater than the preset first pressure and less than or equal to the preset second pressure;
Wherein the increasing amplitude of the feeding speed of the polyethylene mixture is determined by the difference between the average pressure inside the feeding pipe and the preset first pressure.
Further, when the content of the catalyst in the finished polyethylene is larger than the preset content, the control module secondarily judges that the effectiveness of extraction is not in accordance with the requirement, and the vertical height of the stirring paddle is increased.
Further, the increase of the vertical height of the stirring paddle is determined by the difference between the catalyst content in the finished polyethylene and the preset content.
Compared with the prior art, the system has the beneficial effects that the polymerization module, the detection module and the control module are arranged, the motor rotating speed of the stirring shaft in the reactor is regulated according to the variance of the fluctuation range of the temperature in the reactor, the heating element of the heating device in the reactor is aged, so that the heating temperature cannot reach the preset temperature, the ethylene and the catalyst cannot be uniformly mixed, the mixing speed of the ethylene and the catalyst is accelerated by increasing the motor rotating speed of the stirring shaft, the non-uniformity is reduced, the feeding speed of the polyethylene mixture is regulated according to the average pressure in the feeding pipeline of the distillation tower, part of sediment in the feeding pipeline is accumulated on the inner wall of the pipeline, part of pipeline is blocked for a long time, the feeding flow rate in the distillation tower is unstable, the fractionation effect is influenced, the influence of blocking is reduced, the flow stability is improved, the vertical height of the stirring paddles in the reactor is regulated according to the content of the catalyst in the finished polyethylene, the stirring paddles is required to be stirred in the reaction process, the particle size of the catalyst is reduced, the particles can be completely removed from the bottom of the catalyst, the catalyst is difficult to be completely removed, and the particles in the process of collision and the catalyst is more difficult to be completely removed from the bottom of the catalyst is reduced.
Further, the system adjusts the motor rotation speed of the stirring shaft in the reactor by setting the preset first variance and the preset second variance, and the heating temperature cannot reach the preset temperature due to the aging of the heating element of the heating device in the reactor, so that the ethylene and the catalyst cannot be uniformly mixed, the mixing speed of the ethylene and the catalyst is increased by increasing the motor rotation speed of the stirring shaft, the non-uniformity is reduced, and the stability of the polyethylene preparation is further improved.
Furthermore, the system adjusts the feeding speed of the polyethylene mixture by setting the preset first pressure and the preset second pressure, and part of sediments in the feeding pipeline are accumulated on the inner wall of the pipeline, so that part of pipelines are blocked for a long time, the feeding flow in the distillation tower is unstable, the fractionation effect is affected, the feeding speed of the polyethylene mixture is increased, the polyethylene mixture is helped to be pushed to pass through the pipeline, the blocking effect is lightened, the flow stability is improved, and the stability of polyethylene preparation is further improved.
Furthermore, the system adjusts the vertical height of the stirring paddle in the reactor by setting the preset content, and because the stirring device is required to stir during the reaction process, part of catalyst particles collide, so that the particle size becomes smaller, the catalyst is difficult to completely remove during the extraction process, and the stirring paddle is farther away from the bottom of the reactor by increasing the vertical height of the stirring paddle, so that the probability of particle collision is reduced, the abrasion and the possibility of diminishing the catalyst particles are reduced, and the stability of polyethylene preparation is further improved.
Drawings
FIG. 1 is a schematic diagram showing the overall structure of a polyethylene production system according to an embodiment of the present invention;
FIG. 2 is a block diagram showing the overall structure of a polyethylene production system according to an embodiment of the present invention;
FIG. 3 is a logic flow diagram of a polyethylene production system according to an embodiment of the present invention;
FIG. 4 is a block diagram showing a specific structure of a polymerization module of the polyethylene production system according to the embodiment of the present invention;
The reference numerals are as follows, 1-reactor, 2-stirring shaft, 3-stirring paddle, 4-electric telescopic rod, 5-temperature sensor, 6-conveying pump, 7-feeding pipeline, 8-pressure sensor, 9-distillation tower, 10-first conveying pipeline, 11-extractor, 12-second conveying pipeline, 13-extruder, 14-X-ray fluorescence spectrometer.
Detailed Description
The invention will be further described with reference to examples for the purpose of making the objects and advantages of the invention more apparent, it being understood that the specific examples described herein are given by way of illustration only and are not intended to be limiting.
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention.
It should be noted that, in the description of the present invention, terms such as "upper," "lower," "left," "right," "inner," "outer," and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the apparatus or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
In addition, it should be noted that, in the description of the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, integrally connected, mechanically connected, electrically connected, directly connected, indirectly connected through an intermediate medium, or in communication between two elements. The specific meaning of the above terms in the present invention can be understood by those skilled in the art according to the specific circumstances.
Referring to fig. 1, fig. 2, fig. 3, and fig. 4, an overall schematic diagram, an overall block diagram, a logic flow diagram, and a specific block diagram of an aggregation module of a polyethylene preparation system according to an embodiment of the invention are shown. The invention relates to a polyethylene preparation system, which comprises:
A polymerization module for polymerizing ethylene to output a finished polyethylene, comprising a reaction unit for carrying out a mixing reaction on the ethylene and a catalyst to output a polyethylene mixture, a distillation unit connected with the reaction unit for carrying out distillation separation on the polyethylene mixture to output a polyethylene fraction and byproducts, an extraction unit connected with the distillation unit for extracting the polyethylene fraction to output a polyethylene extract and impurities, and a molding unit for processing and molding the polyethylene extract to output a finished polyethylene;
Wherein the reaction unit comprises a reactor for providing a reaction site, the distillation unit comprises a distillation tower connected with the reactor for separating the polyethylene mixture, and the forming unit comprises an extruder connected with the distillation tower for extruding and forming the polyethylene extract;
the detection module is connected with the polymerization module and used for detecting processing parameters in the preparation process of the polyethylene;
And the control module is respectively connected with the polymerization module and the detection module, and is used for judging whether the stability of the polyethylene preparation meets the requirement according to the variance of the fluctuation range of the temperature in the reactor, adjusting the motor rotation speed of a stirring shaft in the reactor or adjusting the feeding speed of the polyethylene mixture according to the average pressure in the feeding pipeline of the distillation tower when the stability of the polyethylene preparation does not meet the requirement, and adjusting the vertical height of a stirring paddle in the reactor according to the average pressure in the feeding pipeline of the distillation tower and the content of the catalyst in the finished polyethylene.
Specifically, the reaction unit further comprises an electric telescopic rod connected with the stirring shaft and used for adjusting the vertical height of the stirring paddle.
In particular, the distillation unit further comprises a transfer pump connected to the feed line for adjusting the feed rate of the polyethylene mixture.
Specifically, the extraction unit includes:
A first conveying pipeline arranged at the output end of the distillation tower and used for conveying polyethylene fractions;
An extractor is connected to the first transfer line for extracting the polyethylene fraction.
In particular, the forming unit further comprises a second conveying pipe arranged at the output end of the extractor for conveying the polyethylene extract.
In particular, the catalyst includes Ziegler-Natta catalysts, chromium catalysts, phillips catalysts.
Specifically, the polyethylene mixture comprises polyethylene polymer, catalyst, ethylene.
Specifically, the polyethylene fraction is high purity polyethylene.
Specifically, the byproducts include catalyst residues, unreacted ethylene, impurities.
Specifically, the polyethylene extract is high purity polyethylene.
Specifically, the impurities include catalyst residues, unreacted ethylene, moisture.
Specifically, the reactor includes a loop reactor and a gas phase reactor.
Specifically, the vertical height of the stirring paddle is the distance between the stirring paddle and the bottom of the reactor.
The method comprises the steps of dividing the finished polyethylene at equal intervals, cutting the finished polyethylene into a plurality of equal-size cut pieces according to dividing lines, detecting each cut piece by using an X-ray fluorescence spectrometer, and finally adding the content of the catalyst in the plurality of cut pieces to obtain the content of the catalyst in the finished polyethylene.
In the implementation, the system adjusts the motor rotation speed of a stirring shaft in the reactor according to the variance of the fluctuation range of the temperature in the reactor by arranging the polymerization module, the detection module and the control module, the heating temperature cannot reach the preset temperature due to the aging of a heating element of a heating device in the reactor, so that the ethylene and the catalyst cannot be uniformly mixed, the mixing speed of the ethylene and the catalyst is accelerated by increasing the motor rotation speed of the stirring shaft, the non-uniformity is reduced, the feeding speed of the polyethylene mixture is adjusted according to the average pressure in a feeding pipeline of the distillation tower, partial precipitates in the feeding pipeline are accumulated on the inner wall of the pipeline, partial pipelines are blocked for a long time, the feeding flow in the distillation tower is unstable, thereby influence fractionation effect, through the pay-off speed that increases the polyethylene mixture, help promoting the polyethylene mixture and pass through the pipeline, alleviate the influence of jam, improve flow stability, according to the content of catalyst in the finished product polyethylene to the vertical height of stirring rake in the reactor is adjusted, because need stir with agitating unit in the reaction process, make partial catalyst granule bump, lead to the particle diameter to diminish, thereby lead to being difficult to get rid of the catalyst completely in the extraction process, through increasing the vertical height of stirring rake, make the stirring rake more distant from the reactor bottom, reduce the chance of granule collision, thereby reduce the wearing and tearing of catalyst granule and the possibility that diminish, polyethylene preparation's stability has been improved.
Specifically, the detection module includes:
A temperature sensor connected to the reactor for detecting a temperature in the reactor;
A pressure sensor connected to the feed pipe for detecting the pressure inside the feed pipe;
and the X-ray fluorescence spectrometer is arranged at the output end of the extruder and used for detecting the content of the catalyst in the finished polyethylene.
In particular, the processing parameters include the temperature in the reactor, the pressure inside the feed conduit and the catalyst content in the finished polyethylene.
Specifically, the control module acquires the temperature of the reactor in a plurality of heating periods, calculates the variance of the fluctuation range of the temperature in the reactor, and judges that the stability of the polyethylene preparation does not meet the requirement if the variance of the fluctuation range of the temperature in the reactor is larger than a preset first variance;
And when the variance of the fluctuation amplitude of the temperature in the reactor is larger than the preset first variance and smaller than or equal to the preset second variance, the control module preliminarily judges that the separation effectiveness of the polyethylene mixture is not in accordance with the requirement, and secondarily judges whether the separation effectiveness of the polyethylene mixture is in accordance with the requirement according to the average pressure in the feeding pipeline.
It can be understood that three intervals corresponding to the preset first variance and the preset second variance correspond to three conditions respectively, wherein the first interval is Q < Q1 and corresponds to the condition that the stability of polyethylene preparation meets the requirement, the second interval is Q1< Q2 and corresponds to the condition that partial sediments in a feeding pipeline are accumulated on the inner wall of the pipeline, partial pipeline blockage is caused for a long time, the feeding flow in a distillation tower is unstable, the fractionation effect is influenced, the third interval is Q > Q2 and corresponds to the condition that a heating element of a heating device in a reactor is aged, the heating temperature cannot reach the preset temperature, and thus ethylene and a catalyst cannot be uniformly mixed. In practice, Q1 is typically selected in the range of [3 ℃ 2,5℃2 ], and Q2 is typically selected in the range of [5 ℃ 2,7℃2 ].
Preferably, the preferred embodiment of the preset first variance Q1 is 4 ℃ 2 and the preferred embodiment of the preset second variance Q2 is 6 ℃ 2.
Specifically, the variance of the fluctuation amplitude of the temperature in the reactor is denoted as Q.
In implementation, the system judges the stability of the preparation of the polyethylene by setting the preset first variance and the preset second variance, reduces the influence of the reduction of the precision of the preparation of the polyethylene caused by inaccurate judgment of the stability of the preparation of the polyethylene, and further improves the stability of the preparation of the polyethylene.
Specifically, the control module increases the motor speed of the stirring shaft when the variance of the fluctuation amplitude of the temperature in the reactor is greater than the preset second variance;
The increasing amplitude of the motor rotation speed of the stirring shaft is determined by the difference value between the variance of the fluctuation amplitude of the temperature in the reactor and the preset second variance.
Specifically, the calculation formula of the motor rotation speed of the stirring shaft after the increase is:
wherein V' is the motor speed of the stirring shaft after increasing, V is the current motor speed of the stirring shaft, A is the minimum unit variance for adjusting the motor speed of the stirring shaft, and V is the motor speed of the stirring shaft when the variance of the fluctuation range of the temperature in the reactor is the minimum unit variance.
In practice, the value of a is typically 7 ℃ 2～9℃2, preferably, a preferred embodiment of a is 8 ℃ 2.
In practice, the value of v may be selected in the range of [900r/min,1100r/min ], preferably, when the motor speed of the stirring shaft is less than 1000r/min, it may be the case that the ethylene and the catalyst cannot be uniformly mixed, so that the preferred embodiment of v is 1000r/min.
For example, loop polyethylene is prepared using a polyethylene preparation system, wherein v=900 r/min, q=10 ℃, 2, calculated as V'=1400r/min。
In implementation, the system adjusts the motor rotation speed of the stirring shaft in the reactor by setting the preset first variance and the preset second variance, and the heating temperature cannot reach the preset temperature due to the aging of the heating element of the heating device in the reactor, so that the ethylene and the catalyst cannot be uniformly mixed, the mixing speed of the ethylene and the catalyst is increased by increasing the motor rotation speed of the stirring shaft, the non-uniformity is reduced, and the stability of the polyethylene preparation is further improved.
Specifically, the control module obtains the pressure inside a feeding pipeline of the distillation tower in a plurality of conveying periods, calculates the average pressure inside the feeding pipeline, and secondarily judges that the separation effectiveness of the polyethylene mixture is not in accordance with the requirement if the average pressure inside the feeding pipeline is larger than the preset first pressure.
Specifically, the control module preliminarily judges that the effectiveness of extraction is not in accordance with the requirement when the average pressure in the feeding pipeline is larger than the preset second pressure, and secondarily judges whether the effectiveness of extraction is in accordance with the requirement according to the content of the catalyst in the finished polyethylene.
It can be understood that three intervals corresponding to the preset first pressure P1 and the preset second pressure P2 correspond to three conditions respectively, wherein the first interval is P1 or less and corresponds to the condition that the separation effectiveness of the polyethylene mixture meets the requirement, the second interval is P1 or less and corresponds to the condition that partial sediments in a feeding pipeline are accumulated on the inner wall of the pipeline, partial pipeline is blocked for a long time and the feeding flow in a distillation tower is unstable, so that the fractionation effect is influenced, and the third interval is P > P2 and corresponds to the condition that stirring is needed by a stirring device in the reaction process, so that partial catalyst particles collide, the particle size is reduced, and the catalyst is difficult to completely remove in the extraction process. In practice, P1 is generally selected in the range of [25KPa,35KPa ], and P2 is generally selected in the range of [35KPa,45KPa ].
Preferably, the preferred embodiment of the preset first pressure P1 is 30KPa and the preferred embodiment of the preset second pressure P2 is 40KPa.
Specifically, the average pressure inside the feed conduit is noted as P.
In implementation, the system of the invention carries out secondary judgment on the separation effectiveness of the polyethylene mixture by setting the preset first pressure and the preset second pressure, thereby reducing the influence of the reduction of the stability of the polyethylene preparation caused by inaccurate secondary judgment on the separation effectiveness of the polyethylene mixture and further improving the stability of the polyethylene preparation.
Specifically, the control module increases the feeding speed of the polyethylene mixture when the average pressure inside the feeding pipeline is greater than the preset first pressure and less than or equal to the preset second pressure;
Wherein the increasing amplitude of the feeding speed of the polyethylene mixture is determined by the difference between the average pressure inside the feeding pipe and the preset first pressure.
Specifically, the calculation formula of the feeding speed of the increased polyethylene mixture is:
Wherein H' is the feeding speed of the increased polyethylene mixture, H is the current feeding speed of the polyethylene mixture, B is the minimum unit pressure for adjusting the feeding speed of the polyethylene mixture, and H is the feeding speed of the polyethylene mixture when the average pressure inside the feeding pipeline is the minimum unit pressure.
In practice, the value of B is generally 45 KPa-55 KPa, preferably, the preferred embodiment of B is 50KPa.
In practice, the value of h may be chosen in the range of [15kg/h,25kg/h ], preferably when the feeding rate of the polyethylene mixture is less than 20kg/h, an unstable feeding flow may be caused, so that a preferred embodiment of h is 20kg/h.
For example, loop polyethylene is prepared using a polyethylene preparation system, wherein h=17 kg/H, p=45 KPa, calculated as H' ==23kg/h。
In implementation, the system adjusts the feeding speed of the polyethylene mixture by setting the preset first pressure and the preset second pressure, and part of sediments in the feeding pipeline are accumulated on the inner wall of the pipeline, so that part of pipelines are blocked for a long time, and the feeding flow in the distillation tower is unstable, thereby influencing the fractionation effect.
Specifically, when the content of the catalyst in the finished polyethylene is larger than the preset content, the control module secondarily judges that the effectiveness of extraction is not in accordance with the requirement, and increases the vertical height of the stirring paddle.
It can be understood that the two intervals corresponding to the preset content Y0 correspond to two cases respectively, wherein the first interval is Y < Y0 and corresponds to the condition that the effectiveness of extraction meets the requirement, and the second interval is Y > Y0 and corresponds to the condition that stirring is needed by a stirring device in the reaction process, so that part of catalyst particles collide, the particle size is reduced, and the catalyst is difficult to completely remove in the extraction process. In practice, Y0 is generally selected in the range of [4ppm,6ppm ].
Preferably, the preferred embodiment of the preset content Y0 is 5ppm.
Specifically, the catalyst content in the final polyethylene is designated as Y.
In implementation, the system of the invention carries out secondary judgment on the effectiveness of extraction by setting the preset content, reduces the influence of the reduction of the stability of the preparation of polyethylene caused by inaccurate secondary judgment on the effectiveness of extraction, and further improves the stability of the preparation of polyethylene.
Specifically, the increase in the vertical height of the stirring paddles is determined by the difference between the catalyst content in the finished polyethylene and the preset content.
Specifically, the calculation formula of the vertical height of the increased stirring paddle is:
Wherein L' is the vertical height of the stirring paddle after the increase, L is the current vertical height of the stirring paddle, C is the minimum unit content for adjusting the vertical height of the stirring paddle, and L is the vertical height of the stirring paddle when the content of the catalyst in the finished polyethylene is the minimum unit content.
In practice, the value of C is generally 5ppm to 7ppm, preferably, the preferred embodiment of C is 6ppm.
In practice, the value of l may be selected in the range of [0.2m,0.4m ], preferably when the vertical height of the stirring paddle is less than 0.3m, a situation may be caused in which the particle diameter of a part of the catalyst particles becomes smaller, so that the preferred embodiment of l is 0.3m.
For example, loop polyethylene is prepared using a polyethylene preparation system, wherein l=0.2 m, y=8 ppm, calculated as L' ==0.35。
In the implementation, the system adjusts the vertical height of the stirring paddle in the reactor by setting the preset content, and because the stirring device is required to stir during the reaction process, part of catalyst particles collide, so that the particle size becomes smaller, the catalyst is difficult to completely remove during the extraction process, and the vertical height of the stirring paddle is increased, so that the stirring paddle is farther away from the bottom of the reactor, the probability of particle collision is reduced, the abrasion and the possibility of the catalyst particles are reduced, and the stability of polyethylene preparation is further improved.
Thus far, the technical solution of the present invention has been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present invention, and such modifications and substitutions will be within the scope of the present invention.
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| CN106029712A (en) * | 2014-02-11 | 2016-10-12 | 尤尼威蒂恩技术有限责任公司 | Method of producing polyethylene and polyethylene thereof |
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| CN114524703A (en) * | 2020-11-23 | 2022-05-24 | 中国化学工程第十六建设有限公司 | Device and process for preparing polyethylene by catalytic cracking of coal-to-olefin |
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| CN106029712A (en) * | 2014-02-11 | 2016-10-12 | 尤尼威蒂恩技术有限责任公司 | Method of producing polyethylene and polyethylene thereof |
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