Method and system for improving linear low density film pellets

Abstract

The application provides a linear low-density film material crystal point improvement method and system, which comprises the following steps: during the switching from a high-density brand to a linear low-density brand, the hydrogen / ethylene molar ratio in a gas phase reactor is increased, and the hydrogen molar concentration is also increased; after the butene concentration in the gas phase reactor reaches a target value, the hydrogen and butene addition amounts are restored to normal film material production parameters; after the product is switched to transition material, the material level of a purification tank is adjusted multiple times; after the product is switched to transition material, a powder bin is switched to an empty powder bin; after the powder index in the purification tank enters the linear low-density film material normal product range, the powder bin is switched to another empty powder bin; the suction pressure of an extruder gear pump and the throttle valve opening degree are increased, and the filter screen is replaced. The application effectively reduces the crystal points generated in the film production process of linear low-density film material.

Description

Technical Field

[0001] This invention belongs to the field of linear low-density film material crystal point improvement technology. Specifically, it relates to a method and system for improving the crystal points of linear low-density film materials, and also relates to a corresponding computer terminal and computer-readable storage medium. Background Technology

[0002] Linear low-density polyethylene (LLDPE) is a non-toxic, tasteless, and odorless milky-white granule. Compared with low-density polyethylene (LDPE), it has a higher softening temperature and melting temperature, and has advantages such as high strength, good toughness, high rigidity, good heat resistance, and good cold resistance. It also has good resistance to environmental stress cracking, impact strength, and tear strength, and is resistant to acids, alkalis, and organic solvents. Therefore, it can be widely used in industrial, agricultural, medical, hygiene, and daily necessities fields.

[0003] However, linear low-density polyethylene often exhibits a high number of crystal points during film processing, which affects user processing requirements and downstream customer use. Summary of the Invention

[0004] To address the aforementioned shortcomings in the prior art, this invention provides a method and system for improving the crystal points of linear low-density film materials, and also provides a corresponding computer terminal and computer-readable storage medium.

[0005] According to one aspect of the present invention, a method for improving the crystal points of linear low-density film materials is provided, comprising:

[0006] During the transition from high-density grades to linear low-density grades, the hydrogen / ethylene molar ratio in the gas phase reactor is increased, and the hydrogen molar concentration is also increased. Once the butene concentration in the gas phase reactor reaches the target value, the amount of hydrogen and butene added is restored to the normal production parameters of the membrane material.

[0007] After the product is cut into transitional material, the material level in the purification tank is adjusted multiple times;

[0008] After the product is cut to the transition material, switch the powder silo to an empty powder silo; after the powder index in the purification tank enters the normal range of linear low density film material, switch the powder silo to another empty powder silo.

[0009] Increase the suction pressure of the extruder gear pump and the opening of the throttle valve, and replace the filter screen.

[0010] Preferably, during the switch from high-density grades to linear low-density grades, the hydrogen / ethylene molar ratio in the gas-phase reactor is increased, while the hydrogen molar concentration is also increased; after the butene concentration in the gas-phase reactor reaches the target value, the hydrogen and butene addition amounts are restored to the normal production parameters of the membrane material, including:

[0011] During the transition from high-density grades to linear low-density grades, the 1-butene / ethylene ratio in the gas phase reactor is increased, thereby increasing the hydrogen / ethylene molar ratio in the gas phase reactor.

[0012] Pre-set the time to reduce the amount of catalyst added, while increasing the hydrogen molar concentration in the gas phase reactor to keep the hydrogen / ethylene molar ratio in the gas phase reactor constant.

[0013] Once the butene concentration in the reactor reaches the target value, adjust the amount of hydrogen and butene added to restore the normal production parameters of the membrane material.

[0014] Preferably, increasing the 1-butene / ethylene ratio in the gas-phase reactor, thereby increasing the hydrogen / ethylene molar ratio in the gas-phase reactor, includes:

[0015] The initial value of 1-butene / ethylene is 21.5 kg / t, the adjustment range is 4 kg / t / 5 min, and the final value is 150-156 kg / t. The molar ratio of hydrogen to ethylene in the gas phase reactor is increased by 1-2 mol / kmol.

[0016] Preferably, the step of reducing the amount of catalyst added by setting a pre-set time includes:

[0017] Set the time in advance to 25-45 minutes and reduce the speed to 0.5-0.6 kg / h.

[0018] Preferably, the multiple adjustments of the material level in the purification tank include:

[0019] After the product is cut into the transition material, the material level in the purification tank is adjusted by lowering and raising it multiple times. The material level is lowered to the low level alarm at least twice, and the last adjustment is made within a set time after the linear low-density film material is cut in.

[0020] Preferably, after the product is cut to the transition material, the powder silo is switched to an empty powder silo; after the powder index in the purification tank enters the range of the linear low-density film material, the powder silo is switched to another empty powder silo, including:

[0021] Three powder silos are set up. After the product from the gas phase reactor passes through the purification tank, the powder is output to the first powder silo. After the product is cut to the transition material, the powder conveyed from the purification tank is switched to the empty second powder silo, and the transition material powder is output to the second powder silo. After the powder index enters the normal range of linear low density film material, the powder silo is switched to another empty third powder silo, and the normal powder is output to the third powder silo. After the last batch of pipeline material or inspection product is delivered, the powder silos and the blending silos maintain the pneumatic conveying for the set time to achieve the purpose of completely emptying the remaining material in the silos.

[0022] Preferably, the set time for maintaining the airflow is 30 minutes to 1 hour.

[0023] Preferably, increasing the suction pressure of the extruder gear pump and the opening of the throttle valve, and replacing the filter screen, includes:

[0024] The suction pressure of the extruder gear pump should be controlled between 0.20 and 0.45 MPa.

[0025] Adjust the throttle valve opening to 20-28°;

[0026] Replace the filter with a 60-mesh or 80-mesh filter.

[0027] According to another aspect of the present invention, a system for improving the crystal points of linear low-density film materials is provided, comprising:

[0028] The grade switching process parameter optimization module is used to increase the hydrogen / ethylene molar ratio in the gas phase reactor and increase the hydrogen molar concentration during the switch from high-density grade to linear low-density grade. After the butene concentration in the gas phase reactor reaches the target value, the amount of hydrogen and butene added is restored to the normal production parameters of the membrane material.

[0029] The purification tank level adjustment module is used to adjust the level of the purification tank multiple times after the product is cut into transition material.

[0030] The powder silo switching module is used to switch the powder silo to an empty powder silo after the product has been cut to the transition material; after the powder index in the purification tank enters the normal range of linear low density film material, the powder silo is switched to another empty powder silo.

[0031] The extruder operating parameter optimization module is used to improve the suction pressure of the extruder gear pump and the opening of the throttle valve, and to replace the filter screen.

[0032] According to a third aspect of the present invention, a computer terminal is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it can be used to perform the method described in any one of the above inventions, or to run the system described in the above inventions.

[0033] According to a fourth aspect of the present invention, a computer-readable storage medium is provided having a computer program stored thereon, characterized in that, when executed by a processor, the computer program can be used to perform the method described in any one of the above-described inventions, or to run the system described in the above-described inventions.

[0034] By adopting the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0035] The method and system for improving the crystal point of linear low-density film material provided by the present invention can reduce the crystal point of linear low-density film material without modifying the existing equipment or changing the process flow. This can be achieved by overshooting parameters during switching, adjusting the product screen material level, optimizing the switching method of the transition product powder hopper, and adjusting the extruder parameters.

[0036] The present invention provides a method and system for improving the crystal points of linear low-density film materials, which effectively reduces the transition material generated during the switching of pipeline materials to linear low-density film materials.

[0037] The present invention provides a method and system for improving crystal points in linear low-density film materials, which effectively reduces the number of crystal points generated during the film-making process of linear low-density film materials. Attached Figure Description

[0038] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0039] Figure 1 This is a flowchart illustrating the process of a method for improving the crystal points of linear low-density film materials in a preferred embodiment of the present invention.

[0040] Figure 2 This is a schematic diagram of the structure of a linear low-density film material crystal point improvement system in a preferred embodiment of the present invention.

[0041] Figure 3 This is a schematic diagram of the working structure of the polyethylene device product purification tank V406 in a preferred embodiment of the present invention.

[0042] Figure 4 This is a schematic diagram of the working structure of the polyethylene plant powder silo system in a preferred embodiment of the present invention. Detailed Implementation

[0043] The embodiments of the present invention are described in detail below: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention.

[0044] A preferred embodiment of the present invention provides a method for improving the crystal point of linear low-density film material. The method reduces the crystal point of linear low-density film material by overshooting parameters during switching, adjusting the material level in the product purification tank, optimizing the switching mode of the transition product powder silo, and adjusting the extruder parameters.

[0045] Specifically, such as Figure 1 As shown, the method for improving the crystal points of linear low-density film provided in this embodiment includes:

[0046] S1, During the transition from high-density grade to linear low-density grade, increase the hydrogen / ethylene molar ratio in the gas phase reactor and simultaneously increase the hydrogen molar concentration; Once the butene concentration in the gas phase reactor reaches the target value, restore the hydrogen and butene addition amounts to the normal production parameters of the membrane material.

[0047] S2, after the product is cut into the transition material, the material level in the purification tank is adjusted multiple times;

[0048] S3, after the product is cut to the transition material, switch the powder silo to an empty powder silo; after the powder index in the purification tank enters the normal range of linear low density film material, switch the powder silo to another empty powder silo again;

[0049] S4, increase the suction pressure of the extruder gear pump and the opening of the throttle valve, and replace the filter screen.

[0050] In some preferred embodiments, during the transition from high-density grade to linear low-density grade in S1, the hydrogen / ethylene molar ratio in the gas-phase reactor is increased, and the hydrogen molar concentration is simultaneously increased. After the butene concentration in the gas-phase reactor reaches the target value, the hydrogen and butene addition amounts are restored to the normal production parameters of the membrane material. This may further include the following operations:

[0051] S11, during the transition from high-density grades to linear low-density grades, increases the 1-butene / ethylene ratio in the gas phase reactor, thereby increasing the hydrogen / ethylene molar ratio in the gas phase reactor.

[0052] S12, the amount of catalyst added is reduced by setting the time in advance, while increasing the molar concentration of hydrogen in the gas phase reactor and keeping the molar ratio of hydrogen to ethylene in the gas phase reactor constant.

[0053] S13. After the butene concentration in the reactor reaches the target value, adjust the amount of hydrogen and butene added to restore the normal production parameters of the membrane material.

[0054] In some preferred embodiments, S11 above, which increases the 1-butene / ethylene ratio in the gas-phase reactor and thereby increases the hydrogen / ethylene molar ratio in the gas-phase reactor, may further include the following operations:

[0055] The initial value of 1-butene / ethylene is 21.5 kg / t, the adjustment range is 4 kg / t / 5 min, and the final value is 150-156 kg / t. The molar ratio of hydrogen to ethylene in the gas phase reactor is increased by 1-2 mol / kmol.

[0056] In some preferred embodiments, the above-mentioned step S12, which involves reducing the amount of catalyst added by setting a time in advance, may further include the following operation:

[0057] The time is set in advance to 25-45 minutes, preferably 30 minutes, and the reduction rate is 0.5-0.6 kg / h.

[0058] S1 above describes the process of optimizing the switching parameters for different grades. During the switch from a high-density grade to a linear low-density grade, the 1-butene / ethylene ratio in the gas-phase reactor is increased. The initial 1-butene / ethylene ratio is approximately 21.5 kg / t, adjusted by 4 kg / t / 5 min, and finally adjusted to 152 kg / t (150–156 kg / t). The hydrogen / ethylene molar ratio in the gas-phase reactor is appropriately increased by 1–2 mol / kmol. Once the butene concentration in the reactor reaches the target value, the parameters are adjusted back to the normal production parameters for the membrane material. By reducing the catalyst addition by approximately 0.5–0.6 kg / h about 30 min in advance, the ethylene consumption rate in the reactor is slowed down, and the ethylene molar concentration in the reactor is stabilized at a higher level, resulting in a higher ethylene content in the reactor. Since the hydrogen / ethylene molar ratio in the reactor needs to remain constant, the hydrogen molar concentration in the reactor will increase accordingly. By over-adjusting the hydrogen supply, the product index is ensured to reach the target level quickly, reducing the transition time during the grade switch and minimizing the generation of low melt index powder during the switch. Once the chromatographic values ​​reach the production parameters for linear low-density membrane materials, restore the hydrogen and butene feedstocks to the production parameters.

[0059] In some preferred embodiments, the above-mentioned S2, which involves repeatedly adjusting the material level in the purification tank, may further include the following operations:

[0060] After the product is cut into the transition material, the material level in the purification tank is adjusted by lowering and raising it multiple times. The adjustment involves lowering the material level to the low-level alarm at least twice, with the final adjustment occurring within a set time after the linear low-density film material is cut in. More preferably, this set time can be 6 hours.

[0061] S2 above describes the process of adjusting the product purification tank level during the switching period. After the product transition material is cut off, the purification tank level is lowered and raised multiple times. By manually intervening in the discharge of the purification tank, the residual powder of the high-density product in the purification tank can be emptied as quickly as possible, and the high-density product in the purification tank can be replaced with linear low-density film material as soon as possible. This reduces the mixing of low-index pipeline material with high-index material, thereby reducing crystal points. This step generally lowers the purification tank level 2-3 times, with the last time being performed as soon as possible after the linear low-density film material is cut in. By lowering the purification tank level control, combined with increasing the opening of the rotary valve at the bottom of the purification tank, the rotation speed of the rotary valve is increased, thereby increasing the amount of powder conveyed in the purification tank to achieve the required level. Similarly, by increasing the purification tank level control, the opening of the rotary valve at the bottom of the purification tank is lowered, thereby reducing the rotation speed of the rotary valve and reducing the amount of powder conveyed in the purification tank, thus raising the purification tank level to the target level.

[0062] In some preferred embodiments, S3 above, after the product is cut to the transition material, switches the powder silo to an empty powder silo; after the powder index in the purification tank enters the normal range of linear low-density film material, switches the powder silo to another empty powder silo again, and may further include the following operations:

[0063] Three powder silos are set up. After the gas phase reactor product passes through the purification tank, the powder is output to the first powder silo. After the product is cut to the transition material, the powder conveyed by the purification tank is switched to the empty second powder silo, and the transition material powder is output to the second powder silo. After the powder index enters the normal range of linear low density film material, the powder silo is switched to another empty third powder silo, and the normal powder is output to the third powder silo. After the last batch of pipeline material or inspection product is delivered, the powder silos and the blending silos maintain the pneumatic conveying for the set time to achieve the purpose of completely emptying the remaining material in the silos.

[0064] In some preferred embodiments, the above-mentioned air-blowing setting time can be 30 minutes to 1 hour.

[0065] S3 above describes the process of optimizing the switching method for the transitional product powder silo. To avoid mixing of different grades of powder, the advantages of three powder silos can be utilized to separate different grades of powder. After the product is cut to the transitional material, the powder silo is switched to an empty one. Once the powder index in the purification tank enters the range of the linear low-density membrane material, the powder silo is switched to another empty one. After the last batch of high-density product or inspection-ready product is delivered to the powder silo and the mixing silo, and after the pipeline powder and transitional powder are emptied, feeding continues for 1 hour to completely empty the remaining material in the silos. By optimizing silo management, mixing of different grades of powder can be effectively avoided, reducing the possibility of crystal point formation in the membrane material.

[0066] In some preferred embodiments, S4 above, which involves increasing the suction pressure of the extruder gear pump and the opening of the throttle valve, and replacing the filter screen, may further include the following operations:

[0067] S41, control the suction pressure of the extruder gear pump between 0.20 and 0.45 MPa;

[0068] S42, adjust the throttle valve opening to 20-28°, preferably 25°;

[0069] S43, replace the filter with a 60-mesh or 80-mesh filter.

[0070] S4 above describes the process of optimizing extruder operating parameters. By increasing the extruder gear pump suction pressure and throttle valve opening, the extruder mixing effect is improved, causing the residual low melt index portion in the linear low-density film to melt or degrade, thus reducing the formation of crystal points during the blown film process. Changing the screen directly removes the residual low melt index polyethylene from the filter screen, effectively reducing the residence time of the low melt index powder in the system. By increasing the extruder gear pump suction pressure to within the range of 0.25–0.35 MPa and adjusting the throttle valve opening to 25°, the extruder mixing effect is improved, causing the residual low melt index portion in the linear low-density film to melt or degrade, thus reducing the formation of crystal points during the blown film process. Frequent screen changes, especially using screens with higher mesh sizes such as 60 or 80 mesh, directly remove the residual low melt index polyethylene from the filter screen, effectively reducing the residence time of the low melt index powder in the system.

[0071] Based on the same inventive concept, an embodiment of the present invention also provides a system for improving the crystal points of linear low-density film materials.

[0072] Specifically, such as Figure 2 As shown, the system for improving the crystal points of linear low-density film materials provided in this embodiment may include the following modules:

[0073] The grade switching process parameter optimization module is used to increase the hydrogen / catalyst molar ratio in the gas phase reactor during the switching from high-density grade to linear low-density grade. After the catalyst concentration in the gas phase reactor reaches the target value, the catalyst addition amount is adjusted to restore the normal production parameters of the membrane material.

[0074] The purification tank level adjustment module is used to adjust the level of the purification tank multiple times after the product is cut into transition material.

[0075] The powder silo switching module is used to switch the powder silo to an empty powder silo after the product has been cut to the transition material; after the powder index in the purification tank enters the normal range of linear low density film material, the powder silo is switched to another empty powder silo.

[0076] The extruder operating parameter optimization module is used to improve the suction pressure of the extruder gear pump and the opening of the throttle valve, and to replace the filter screen.

[0077] It should be noted that the steps in the method provided by the present invention can be implemented using corresponding modules, devices, units, etc. in the system. Those skilled in the art can refer to the technical solution of the method to realize the composition of the system. That is, the embodiments in the method can be understood as preferred examples for building the system, and will not be elaborated here.

[0078] The technical solution provided by the above embodiments of the present invention will be further described in detail below with reference to a specific application example.

[0079] During the switchover from pipeline feed to linear low-density membrane feed, the hydrogen / ethylene molar ratio in gas-phase reactor R401 is appropriately increased by 1-2 mol / kmol. Once the butene concentration in the reactor reaches the target value, the parameters are adjusted back to the normal production parameters for the membrane feed. The purpose of hydrogen overshoot is to reduce the amount of low-index products generated in the gas-phase reactor during the switchover process and to reduce the mixing of low-index pipeline feed products with high-index linear low-density membrane feed products.

[0080] like Figure 3 The diagram shows the working structure of the V406 product purification tank in Shanghai Petrochemical's No. 4 polyethylene unit. The polymerized product from the loop reactor and gas-phase reactor is sent to the purification tank, where it is cleaned with hot nitrogen and steam to reduce the hydrocarbon content in the polymer and deactivate residual catalyst. The cleaned polymer is then conveyed via a pneumatic conveying system to the powder silo in the granular area. After the product transition material is removed, the tank level is lowered and raised to quickly evacuate any remaining pipeline material from V406, reducing the amount of residual pipeline material and replacing it with linear low-density film material as soon as possible, thus minimizing the mixing of low-index pipeline material with high-index product.

[0081] like Figure 4 The diagram shows the working structure of the powder silo system in Shanghai Petrochemical's No. 4 polyethylene unit. Powder from the gas-phase reactor area is delivered to the powder silo, and the powder from the silo is fed into the extruder feed conveyor via a powder feed flow meter. The No. 4 polyethylene unit is designed with three powder silos: T702A / B / C. After the product reaches the transition material stage, the powder silo is switched to an empty silo. Once the CV406 powder index enters the range of the linear low-density film material, the powder silo is switched to another empty silo. After the last batch of pipeline material or inspection-ready products is delivered to the powder silo and blending silo, pneumatic conveying is maintained for 1 hour to completely empty the remaining material in the silos.

[0082] Powders, additives, carbon black masterbatch, and other materials from the extruder feed conveyor are fed into the extruder. These materials are melted, homogenized, and granulated in the extruder to form particles of a specific shape. By increasing the suction pressure of the extruder gear pump and the opening of the throttle valve, the mixing effect of the extruder is improved, causing the low-index components remaining in the linear low-density film material to melt or degrade, reducing the formation of crystal points during the film-making process.

[0083] An embodiment of the present invention also provides a computer terminal, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, it can be used to execute any of the methods in the above embodiments of the present invention, or to run any of the systems in the above embodiments of the present invention.

[0084] Optionally, the memory is used to store programs; the memory may include volatile memory, such as random-access memory (RAM), such as static random-access memory (SRAM), double data rate synchronous dynamic random-access memory (DDR SDRAM), etc.; the memory may also include non-volatile memory, such as flash memory. The memory is used to store computer programs (such as application programs, functional modules, etc. that implement the above methods), computer instructions, etc., and the aforementioned computer programs, computer instructions, etc., can be partitioned and stored in one or more memories. Furthermore, the aforementioned computer programs, computer instructions, data, etc., can be accessed by the processor.

[0085] The aforementioned computer programs, computer instructions, etc., can be stored in partitions within one or more memory locations. Furthermore, the aforementioned computer programs, computer instructions, data, etc., can be accessed by a processor.

[0086] A processor is used to execute computer programs stored in memory to implement the various steps of the methods or various modules of the systems involved in the above embodiments. For details, please refer to the relevant descriptions in the preceding method and system embodiments.

[0087] The processor and memory can be separate structures or integrated structures. When the processor and memory are separate structures, they can be coupled together via a bus.

[0088] An embodiment of the present invention also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, can be used to perform the method of any of the above embodiments of the present invention, or to run the system of any of the above embodiments of the present invention.

[0089] Computer-readable media include computer storage media and communication media, wherein communication media include any medium that facilitates the transfer of computer programs from one place to another. Storage media can be any available medium accessible to a general-purpose or special-purpose computer. An exemplary storage medium is coupled to a processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and storage medium can reside in an ASIC. Alternatively, the ASIC can reside in a user device. Of course, the processor and storage medium can also exist as discrete components in a communication device.

[0090] The method and system for improving the crystal point of linear low-density film material provided in the above embodiments of the present invention can reduce the crystal point of linear low-density film material without modifying the existing equipment or changing the process flow. This is achieved by over-adjusting parameters during switching, adjusting the product sieve material level, optimizing the switching method of the transition product powder hopper, and adjusting the extruder parameters. This effectively reduces the transition material generated during the switching from pipeline material to linear low-density film material and effectively reduces the crystal point generated during the film-making process of linear low-density film material.

[0091] The method and system for improving the crystal points of linear low-density film provided in the above embodiments of the present invention can be applied to the "BORSTAR" bimodal polyethylene process.

[0092] Any matters not covered in the above embodiments of the present invention are well-known in the art.

[0093] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for improving the crystal points of linear low-density film materials, characterized in that, include: During the transition from high-density grades to linear low-density grades, the hydrogen / ethylene molar ratio in the gas phase reactor is increased, and the hydrogen molar concentration is also increased. Once the butene concentration in the gas phase reactor reaches the target value, the amount of hydrogen and butene added is restored to the normal production parameters of the membrane material. After the product is cut into transitional material, the material level in the purification tank is adjusted multiple times; After the product is cut to the transition material, switch the powder silo to an empty powder silo; after the powder index in the purification tank enters the normal range of linear low density film material, switch the powder silo to another empty powder silo. Increase the suction pressure of the extruder gear pump and the opening of the throttle valve, and replace the filter screen.

2. The method for improving the crystal points of linear low-density film materials according to claim 1, characterized in that, During the transition from high-density grades to linear low-density grades, the hydrogen / ethylene molar ratio in the gas-phase reactor is increased, while the hydrogen molar concentration is also increased. Once the butene concentration in the gas-phase reactor reaches the target value, the hydrogen and butene addition amounts are restored to the normal production parameters for the membrane material, including: During the transition from high-density grades to linear low-density grades, the 1-butene / ethylene ratio in the gas phase reactor is increased, thereby increasing the hydrogen / ethylene molar ratio in the gas phase reactor. Pre-set the time to reduce the amount of catalyst added, while increasing the hydrogen molar concentration in the gas phase reactor to keep the hydrogen / ethylene molar ratio in the gas phase reactor constant. Once the butene concentration in the reactor reaches the target value, adjust the amount of hydrogen and butene added to restore the normal production parameters of the membrane material.

3. The method for improving the crystal points of linear low-density film materials according to claim 2, characterized in that, The increase in the 1-butene / ethylene ratio in the gas-phase reactor, thereby increasing the hydrogen / ethylene molar ratio in the gas-phase reactor, includes: The initial value of 1-butene / ethylene is 21.5 kg / t, the adjustment range is 4 kg / t / 5 min, and the final value is 150-156 kg / t. The molar ratio of hydrogen to ethylene in the gas phase reactor is increased by 1-2 mol / kmol. The method of reducing the amount of catalyst added by setting a pre-defined time includes: Set the time in advance to 25-45 minutes and reduce the speed to 0.5-0.6 kg / h.

4. The method for improving the crystal points of linear low-density film materials according to claim 1, characterized in that, The repeated adjustments to the material level in the purification tank include: After the product is cut into the transition material, the material level in the purification tank is adjusted by lowering and raising it multiple times. The material level is lowered to the low level alarm at least twice, and the last adjustment is made within a set time after the linear low-density film material is cut in.

5. The method for improving the crystal points of linear low-density film materials according to claim 1, characterized in that, After the product is cut to the transition material, the powder silo is switched to an empty powder silo; after the powder index in the purification tank enters the range of the linear low-density film material, the powder silo is switched to another empty powder silo, including: Three powder silos are set up. After the gas phase reactor product passes through the purification tank, the powder is output to the first powder silo. After the product is cut to the transition material, the powder conveyed by the purification tank is switched to the empty second powder silo, and the transition material powder is output to the second powder silo. After the powder index enters the normal range of linear low density film material, the powder silo is switched to another empty third powder silo, and the normal powder is output to the third powder silo. After the last batch of pipeline material or inspection product is delivered, the powder silos and the blending silos maintain the pneumatic conveying for the set time to achieve the purpose of completely emptying the remaining material in the silos.

6. The method for improving the crystal points of linear low-density film materials according to claim 5, characterized in that, The set time for maintaining airflow is 30 minutes to 1 hour.

7. The method for improving the crystal points of linear low-density film materials according to claim 1, characterized in that, The steps of increasing the suction pressure of the extruder gear pump and the opening of the throttle valve, and replacing the filter screen, include: The suction pressure of the extruder gear pump should be controlled between 0.20 and 0.45 MPa. Adjust the throttle valve opening to 20-28°; Replace the filter with a 60-mesh or 80-mesh filter.

8. A system for improving the crystal points of linear low-density film materials, characterized in that, include: The grade switching process parameter optimization module is used to increase the hydrogen / ethylene molar ratio in the gas phase reactor and increase the hydrogen molar concentration during the switch from high-density grade to linear low-density grade. After the butene concentration in the gas phase reactor reaches the target value, the amount of hydrogen and butene added is restored to the normal production parameters of the membrane material. The purification tank level adjustment module is used to adjust the level of the purification tank multiple times after the product is cut into transition material. The powder silo switching module is used to switch the powder silo to an empty powder silo after the product has been cut to the transition material; after the powder index in the purification tank enters the normal range of linear low density film material, the powder silo is switched to another empty powder silo. The extruder operating parameter optimization module is used to improve the suction pressure of the extruder gear pump and the opening of the throttle valve, and to replace the filter screen.

9. A computer terminal, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it can be used to perform the method of any one of claims 1-7, or to run the system of claim 8.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When executed by a processor, the computer program can be used to perform the method of any one of claims 1-7, or to run the system of claim 8.

Images