Liquid-phase monomer feeding mode and device in gas-phase fluidized bed process production

Abstract

The invention relates to the technical field of gas-phase fluidized bed process production, in particular to a liquid-phase monomer feeding mode and device in gas-phase fluidized bed process production, in the gas-phase fluidized bed process production, according to the requirements of products of different brands, the liquid-phase monomer feeding mode comprises a liquid-phase monomer single feeding mode and a liquid-phase monomer mixed feeding mode, the liquid-phase monomer single feeding mode comprises a liquid-phase monomer single feeding mode without addition of octylene and a liquid-phase monomer single feeding mode with addition of octylene, and the liquid-phase monomer mixed feeding mode comprises a liquid-phase monomer mixed feeding mode without addition of octylene and a liquid-phase monomer mixed feeding mode with addition of octylene. The feeding mode of the copolymerization liquid phase monomer can be switched between a single feeding mode and a mixed feeding mode, production stability is facilitated, more diversified production process modes can be provided, flexible adjustment of different product marks is adapted, high-performance polymer products are developed, and the production cost is reduced. The capacity of the reactor is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of gas-phase fluidized bed process technology, and specifically to a liquid-phase monomer feeding mode and apparatus in gas-phase fluidized bed process production. Background Technology

[0002] In existing gas-phase fluidized bed processes for producing polyethylene resin, the reaction occurs in a gas-solid phase. The copolymer liquid monomers and condensing medium are added as liquids to the fluidizing gas loop and enter the reactor through the bottom of the fluidized bed. Since the fluidizing gas serves as both the reaction medium and the heat exchange medium, it maintains the fluidization effect of the fluidized bed at a certain velocity. The solid catalyst is fluidized and distributed within the fluidized bed, reacting with the gaseous reaction medium and playing a role in mass and heat transfer. Because polymerization is an exothermic reaction, its exothermic rate is affected by the specific heat and flow rate of the fluidizing gas. The reaction temperature in the fluidized bed is typically between 85℃ and 105℃, while the fluidizing gas, after heat exchange, is generally around 40℃. This necessitates that the added liquid medium vaporize at the reaction temperature, rather than remaining in a liquid phase.

[0003] Deng Fangwen, Wang Huilun. Optimization of Start-up and Shutdown of Gas-Phase Fluidized Bed Polyethylene [J]. Guangdong Chemical Industry, 2013, 40(14): 199-201. This paper discusses the optimization of the start-up and shutdown process of gas-phase fluidized bed polyethylene, aiming to shorten start-up and shutdown time and improve economic efficiency. In the start-up process, the conditions for adding liquid monomers and reaction conditions are mentioned. However, the added liquid monomers are ethylene and butene, which are added to the fluidized gas loop in liquid form and enter the reactor through the bottom of the fluidized bed. Chinese patent document CN114195924B discloses a method for synthesizing polyethylene, comprising: (1) setting the system temperature 20%-30% lower than the reaction temperature before catalyst injection; (2) transporting the catalyst with nitrogen gas flow, with a catalyst feed rate of 0.5-2.0 g / h and a heating rate of 0.5-1.5℃ / h; (3) when the reactor inlet temperature reaches 90%-95% of the reaction temperature and the reactor bed pressure difference reaches: 0.1KPa-0.6KPa for the first stage, 0.4KPa-0.7KPa for the second stage, 0.8KPa-2.0KPa for the third stage, 1.0KPa-1.8KPa for the fourth stage, and 8.0KPa-12.4KPa for the fifth stage, setting the catalyst feed rate to 1.0-2.5 g / h and the heating rate to 1.0-5.0℃ / h; (4) after the catalyst activity reaches the design requirements and the polymerization system enters steady-state operation, the catalyst feed rate is related to the change in the Vicat softening point of the polymerization reaction product. However, this technical solution is based on the coordinated control of multiple process parameters, with the catalyst feed rate as the main control parameter. It controls the polymerization reaction of the device by setting the catalyst feed rate at different stages, and coordinates the regulation of process parameters such as reactor inlet temperature, reactor bed pressure difference, and changes in the softening point of the polymer reactants to ensure the stable release of the activity of the highly active catalyst system, effectively reducing the occurrence of explosive polymerization and agglomeration. It is not suitable for switching between the two feeding modes.

[0004] Chinese patent document CN119186414A discloses an olefin polymerization apparatus and method for producing polyolefins. By flexibly combining fluidized bed reactors and degassing the polyethylene particles discharged from the reactors, it is possible to produce polyethylene or polyethylene block copolymer resin products with a wide molecular weight distribution / multi-peak structure. However, this technical solution involves adding a pipeline connecting the top of an intermediate tank to the reactor purge gas line to transport the polyethylene particles from the intermediate tank to the corresponding polymerization reactor, thereby stabilizing the polymerization environment within the reactor. While this transport process effectively removes gaseous components from the previous reactor, it does not allow for switching between two feeding modes.

[0005] It is evident that in existing production processes, when butene and hexene are used as comonomers in the liquid phase and isopentane is used as an inducing condenser, these reagents can all vaporize under reaction conditions and contact the solid bed in a gaseous phase. Since solid particles are the reaction medium and generate significant heat, they easily cause particle adhesion, leading to the accumulation of reaction heat and particle melting. Therefore, these reaction and addition conditions limit the types of comonomers that can be used in the liquid phase. Currently, with the continuous upgrading of new products, the use of C8 octene copolymerization has also entered practical production. Due to its high vaporization temperature, it remains in the liquid phase even at the reaction temperature. This causes C8 octene to adhere to the walls and result in extremely uneven distribution when added to the fluidized bed. Therefore, ensuring uniform dispersion of octene in the fluidized bed is a problem that urgently needs to be solved. Summary of the Invention

[0006] This invention provides a liquid-phase monomer feeding mode and device for gas-phase fluidized bed production, overcoming the shortcomings of the prior art. It can not only effectively solve the problem of uneven droplet dispersion causing changes in the fluidized bed state and resulting in explosive polymerization during the existing octene feeding process, but also provide more diversified production process methods and develop high-performance polymer products.

[0007] One of the technical solutions of the present invention is achieved through the following measures: a liquid phase monomer feeding mode in gas phase fluidized bed process production. In gas phase fluidized bed process production, according to the needs of different grades of products, the liquid phase monomer feeding mode includes a liquid phase monomer fluidized loop feeding mode and a liquid phase monomer reactor lower part feeding mode.

[0008] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions: The above-mentioned liquid phase monomer fluidized loop feeding modes include liquid phase monomer fluidized loop feeding modes without octene addition and liquid phase monomer fluidized loop feeding modes with octene addition. The lower feeding modes in the liquid phase monomer reactor include lower feeding modes in the liquid phase monomer reactor without octene addition and lower feeding modes in the liquid phase monomer reactor with octene addition. The above-mentioned liquid-phase monomer fluidized loop feed mode without octene addition is as follows: isopentane, butene, hexene and recovered condensate from the refining zone are transported to the liquid-phase feed pipeline through their respective feed pipelines, and then injected into the reactor through the fluidizing gas loop pipeline. Alternatively, butene, hexene, isopentane, and recovered condensate from the refining zone are transported to the mixer via their respective feed lines. The resulting mixture is then transported to the fluidizing gas loop via a bypass line and injected into the reactor.

[0009] The above-mentioned liquid-phase monomer fluidized loop feed mode with added octene is as follows: First, isopentane, butene, hexene and recovered condensate from the refining zone are transported to the liquid-phase feed line through their respective feed lines, and then injected into the reactor through the fluidizing gas loop line; then, octene is transported to the mixer through the octene feed line, and then transported to the liquid-phase feed line through the bypass line, and then injected into the reactor through the fluidizing gas loop line. Alternatively, butene, hexene, isopentane, recovered condensate, and octene from the refining zone are transported to the mixer via their respective feed lines. The resulting mixture is then transported to the liquid phase feed line via a bypass line and injected into the reactor via the fluidizing gas loop line.

[0010] The lower feed mode of the liquid phase monomer reactor without octene is as follows: butene, hexene, isopentane, and recovered condensate from the refining zone are transported to the liquid phase feed pipeline through their respective feed pipelines, and then transported to the mixed liquid feed pipeline through the bypass pipeline, and then injected into the reactor through the nozzles in the lower part of the reactor. Alternatively, isopentane, butene, hexene, and recovered condensate from the refining zone are transported to the mixer via their respective feed pipelines. The resulting mixture is then transported to the mixture feed pipeline and injected into the reactor through nozzles at the bottom of the reactor.

[0011] The lower feed mode of the liquid-phase monomer reactor with added octene is as follows: isopentane, butene, hexene, recovered condensate and octene from the refining zone are transported to the mixer through their respective feed pipelines. The resulting mixture is transported to the mixture feed pipeline and then injected into the reactor through the nozzle at the lower part of the reactor. Alternatively, butene, hexene, isopentane, and recovered condensate from the refining zone are first transported to the liquid phase feed line via their respective feed lines, and then to the mixed liquid feed line via the bypass line, and then injected into the reactor through the nozzles at the bottom of the reactor; then, octene is transported to the mixed liquid feed line via the mixer and injected into the reactor through the nozzles at the bottom of the reactor.

[0012] In the above-mentioned gas-phase fluidized bed process, the reaction temperature of the reactor is 85℃ to 105℃, and the reaction pressure of the reactor is 2000kPa to 2300kPa.

[0013] In the above-mentioned gas-phase fluidized bed process, in the single-feed mode and the mixed-feed mode of the liquid phase monomer, the flow rate of butene is 0 to 5000 kg / h, the flow rate of hexene is 0 to 3500 kg / h, the flow rate of isopentane is 0 to 2000 kg / h, the flow rate of the recovered condensate is 0 to 5000 kg / h, and the flow rate of octene is 0 to 3200 kg / h. Among them, the flow rate of octene adopts a separate flow control mode, or adopts a cascade control mode based on the flow ratio of octene to butene and hexene.

[0014] The second technical solution of the present invention is achieved through the following measures: an apparatus for implementing a liquid phase monomer feeding mode in a gas-phase fluidized bed process, comprising a reactor and a mixer, a nozzle is provided in the lower middle part of the reactor, a fluidizing gas circuit pipeline is fixedly connected to the bottom inlet of the reactor, a liquid phase feed pipeline is fixedly connected to the fluidizing gas circuit pipeline, a feed mixing pipeline is fixedly connected between the liquid phase feed pipeline and the first inlet of the mixer, an isopentane feed pipeline, a butene feed pipeline, a hexene feed pipeline and a recovered condensate feed pipeline are fixedly connected from top to bottom on the feed mixing pipeline, an octene feed pipeline is fixedly connected to the second inlet of the mixer, a mixed liquid feed pipeline is fixedly connected between the mixer outlet and the nozzle inlet, and a bypass pipeline is fixedly connected between the mixed liquid feed pipeline and the liquid phase feed pipeline.

[0015] The following are further optimizations and / or improvements to the second technical solution of the above invention: The nozzle inlet is also fixedly connected to a purging pipeline. A first valve is fixedly installed on the feed mixing pipeline between the recovered condensate feed pipeline and the mixer. A second valve is fixedly installed on the bypass pipeline. A third valve is fixedly installed on the liquid phase feed pipeline between the isopentane feed pipeline and the bypass pipeline. A fourth valve is fixedly installed on the mixed liquid feed pipeline between the bypass pipeline and the reactor.

[0016] This invention allows for switching between single-feed and mixed-feed modes for the feeding of copolymer liquid monomers, which not only facilitates production stability but also provides more diversified production processes, adapts to flexible adjustments for different product grades, develops high-performance polymer products, and effectively enhances reactor capacity. Attached Figure Description

[0017] Appendix Figure 1 This is a schematic diagram of the process flow of Embodiment 9 of the present invention.

[0018] Appendix Figure 1 The codes in the diagram are as follows: 1 for reactor, 2 for mixer, 3 for nozzle, 4 for fluidizing gas circuit line, 5 for liquid feed line, 6 for feed mixing line, 7 for butene feed line, 8 for hexene feed line, 9 for recovered condensate feed line, 10 for octene feed line, 11 for mixed liquid feed line, 12 for bypass line, 13 for first valve, 14 for second valve, 15 for third valve, 16 for purge line, 17 for fourth valve, and 18 for isopentane feed line. Detailed Implementation

[0019] The present invention is not limited to the following embodiments, and the specific implementation can be determined according to the technical solution of the present invention and the actual situation.

[0020] The present invention will be further described below with reference to embodiments: Example 1: In the production of this gas-phase fluidized bed process, according to the needs of different grades of products, the liquid phase monomer feeding mode includes the liquid phase monomer fluidized loop feeding mode and the liquid phase monomer reactor bottom feeding mode.

[0021] Example 2: As an optimization of the above examples, the liquid phase monomer fluidized loop feeding mode includes a liquid phase monomer fluidized loop feeding mode without octene and a liquid phase monomer fluidized loop feeding mode with octene. The lower part feeding mode of the liquid phase monomer reactor includes a lower part feeding mode of the liquid phase monomer reactor without octene and a lower part feeding mode of the liquid phase monomer reactor with octene.

[0022] Example 3: As shown in the attached document Figure 1 As shown, as an optimization of the above embodiment, the liquid phase monomer fluidized loop feed mode without octene addition is as follows: isopentane, butene, hexene and recycled condensate from the refining zone are transported to the liquid phase feed line 5 through their respective feed lines, and then injected into the reactor 1 through the fluidized gas loop line 4. Alternatively, butene, hexene, isopentane, and recovered condensate from the refining zone are transported to mixer 2 via their respective feed pipelines. The resulting mixture is then transported to fluidizing gas loop pipeline 4 via bypass pipeline 2 and injected into reactor 1.

[0023] Example 4: As shown in the appendix Figure 1 As shown, as an optimization of the above embodiment, the liquid-phase monomer fluidized loop feed mode with added octene is as follows: First, isopentane, butene, hexene and recovered condensate from the refining zone are transported to the liquid-phase feed line 5 through their respective feed lines, and then injected into reactor 1 through the fluidizing gas loop line 4; then, octene is transported to mixer 1 through octene feed line 10, and then transported to liquid-phase feed line 5 through bypass line 12, and then injected into reactor 1 through the fluidizing gas loop line 4; Alternatively, butene, hexene, isopentane, recovered condensate, and octene from the refining zone are transported to mixer 1 via their respective feed lines. The resulting mixture is then transported to liquid phase feed line 5 via bypass line 12, and then injected into reactor 1 via fluidizing gas loop line 4.

[0024] Example 5: As shown in the attached document Figure 1 As shown, as an optimization of the above embodiment, the lower feeding mode of the liquid phase monomer reactor without octene addition is as follows: butene, hexene, isopentane and recovered condensate from the refining zone are transported to the liquid phase feed line 5 through their respective feed lines, and then transported to the mixed liquid feed line 11 through the bypass line 12, and then injected into the reactor 1 through the nozzle 3 in the lower part of the reactor 1. Alternatively, isopentane, butene, hexene, and recovered condensate from the refining zone are transported to mixer 1 via their respective feed pipelines. The resulting mixture is then transported to the mixture feed pipeline 11 and injected into reactor 1 through nozzle 3 at the lower part of reactor 1.

[0025] Example 6: As attached Figure 1 As shown, as an optimization of the above embodiment, the lower feeding mode of the liquid-phase monomer reactor with added octene is as follows: isopentane, butene, hexene, recovered condensate and octene from the refining zone are transported to the mixer 1 through their respective feed pipelines. The resulting mixture is transported to the mixture feed pipeline 11 and then injected into the reactor 1 through the nozzle 3 at the lower part of the reactor 1. Alternatively, butene, hexene, isopentane, and recovered condensate from the refining zone are first transported to the liquid phase feed line 5 via their respective feed lines, and then transported to the mixed liquid feed line 11 via the bypass line 12, and then injected into reactor 1 through the nozzle 3 at the lower part of reactor 1; then, octene is transported to the mixed liquid feed line 11 via the mixer 2, and then injected into reactor 1 through the nozzle 3 at the lower part of reactor 1.

[0026] Example 7: As attached Figure 1 As shown, as an optimization of the above embodiment, in the gas-phase fluidized bed process, the reaction temperature of reactor 1 is 85°C to 105°C, and the reaction pressure of reactor 1 is 2000 kPa to 2300 kPa.

[0027] In this invention, the reaction conditions can be adjusted within an appropriate range according to the different catalyst systems and production grades, wherein the reaction temperature of reactor 1 is between 85°C and 105°C, and the reaction pressure of reactor 1 is between 2000 kPa and 2300 kPa.

[0028] Example 8: As an optimization of the above examples, in the gas-phase fluidized bed process, in the single-feed mode and the mixed-feed mode of the liquid phase monomer, the flow rate of butene is 0 to 5000 kg / h, the flow rate of hexene is 0 to 3500 kg / h, the flow rate of isopentane is 0 to 2000 kg / h, the flow rate of the recovered condensate is 0 to 5000 kg / h, and the flow rate of octene is 0 to 3200 kg / h. The flow rate of octene is controlled by a separate flow rate control mode or by a cascade control mode using the flow rate ratio of octene to butene and hexene.

[0029] Example 9: As Figure 1As shown, the apparatus for liquid-phase monomer feeding mode in the gas-phase fluidized bed process includes a reactor 1 and a mixer 2. A nozzle 3 is installed in the lower middle part of the reactor 1. A fluidizing gas circuit pipeline 4 is fixedly connected to the bottom inlet of the reactor 1. A liquid-phase feed pipeline 5 is fixedly connected to the fluidizing gas circuit pipeline 4. A feed mixing pipeline 6 is fixedly connected between the liquid-phase feed pipeline 5 and the first inlet of the mixer 2. An isopentane feed pipeline 18, a butene feed pipeline 7, a hexene feed pipeline 8, and a recovered condensate feed pipeline 9 are fixedly connected to the feed mixing pipeline 6 from top to bottom. An octene feed pipeline 10 is fixedly connected to the second inlet of the mixer 2. A mixed liquid feed pipeline 11 is fixedly connected between the outlet of the mixer 2 and the inlet of the nozzle 3. A bypass pipeline 12 is fixedly connected between the mixed liquid feed pipeline 11 and the liquid-phase feed pipeline 5.

[0030] Example 10: As attached Figure 1 As shown, as an optimization of the above embodiment, the nozzle 3 inlet is also fixedly connected to a purge line 16, a first valve 13 is fixedly installed on the feed mixing line 6 between the recovered condensate feed line 9 and the mixer 2, a second valve 14 is fixedly installed on the bypass line 12, a third valve 15 is fixedly installed on the liquid phase feed line 5 between the isopentane feed line 18 and the bypass line 12, and a fourth valve 17 is fixedly installed on the mixed liquid feed line 11 between the bypass line 12 and the reactor 1.

[0031] Depending on the needs, the pipelines and equipment of the device for switching between single-feed and mixed-feed modes of liquid phase monomer in the fluidized bed process can also be equipped with conventional valves, thermometers, and pressure gauges known in the art, as required by production needs.

[0032] In this invention, as needed, nozzle 3 is directly inserted into reactor 1 via a flange connection through an opening in reactor 1. A 2-inch 300-pound flange is used, and nozzle 3 is designed with a sealing assembly to prevent leakage of the medium from reactor 1. During liquid medium injection, a certain pressure differential is used to ensure atomization, ranging from 0.7 MPa to 1.2 MPa, with a minimum requirement of 0.6 MPa, and generally around 0.9 MPa. A purge line 16 is fixedly connected to the nozzle 3 interface. The purge gas is high-pressure refined nitrogen or ethylene. When liquid injection stops at nozzle 3, the purge gas is used to ensure that the pressure inside reactor 1 does not backflow and carry out powder that clogs nozzle 3. When nozzle 3 needs cleaning to remove blockages, purge gas can also be used for cleaning.

[0033] As needed, two nozzles 3 can be set. Different injection pipelines with different diameters can be designed according to different flow rates. For example, one nozzle 3 with a flow rate of 5t / h can be selected with a diameter of DN25, 1" and another nozzle 3 with a flow rate of 15t / h can be selected with a diameter of DN40, 1½". They can be set in the middle and lower part of reactor 1, respectively.

[0034] Example 11: As Figure 1 As shown, the operation process of this gas-phase fluidized bed process in the single-feed mode of liquid monomer without octene addition is as follows: Close the first valve 13, the second valve 14 and the fourth valve 17, and open the third valve 15. Butene, hexene, recovered condensate and isopentane from the refining zone are respectively fed into the liquid phase feed line 5 via the butene feed line 7, the hexene feed line 8, the recovered condensate feed line 9 and the isopentane feed line 18, and then transported to the fluidizing gas loop line 4 before being injected into the reactor 1.

[0035] Example 12: As Figure 1 As shown, in this gas-phase fluidized bed process, octene is added, and the octene is transported to the fluidized gas loop line 4 via the bypass line 12 and then injected into the reactor 1 in a single-feed liquid phase monomer mode. The operation process is as follows: First, close the first valve 13 and the fourth valve, and open the second valve 14 and the third valve 15. Butene, hexene, isopentane and recovered condensate from the refining zone are respectively transported to the liquid phase feed line 5 via the butene feed line 7, the hexene feed line 8, the isopentane feed line 18 and the recovered condensate feed line 9, and then injected into the reactor 1 via the fluidizing gas loop line 4. Then, octene is transported to the mixer 2 via the octene feed line 10 for mixing, and then transported to the fluidizing gas loop line 4 via the bypass line 12 before being injected into the reactor 1.

[0036] Example 13: As Figure 1 As shown, in this gas-phase fluidized bed process, octene is added, and the octene is injected into reactor 1 through nozzle 3 in a single-feed liquid phase monomer mode. The operation process is as follows: First, close the first valve 13 and the second valve 14, and open the third valve 15 and the fourth valve. Butene, hexene, isopentane and recovered condensate from the refining zone are respectively transported to the fluidizing gas loop line 4 via the butene feed line 7, the hexene feed line 8, the liquid phase feed line 5 and the recovered condensate feed line 9 and then injected into the reactor 1. Then, octene is transported to the mixer 2 via the octene feed line 10 and mixed, and then injected into the reactor 1 via the nozzle 3 at the bottom of the reactor 1.

[0037] Example 14: As Figure 1As shown, in this gas-phase fluidized bed process, no octene is added, and the mixture is transported to the fluidized gas loop line 4 via the bypass line 12 and then injected into the reactor 1 in a liquid-phase monomer mixing feed mode. The operation process is as follows: Close the third valve 15 and the fourth valve 17, and open the first valve 13 and the second valve 14. Butene, hexene, isopentane and recovered condensate from the refining zone are transported to the mixer 2 through their respective feed pipelines and mixed. The resulting mixture is then transported to the fluidizing gas loop pipeline 4 through the bypass pipeline 12 and injected into the reactor 1.

[0038] Example 15: As Figure 1 As shown, in this gas-phase fluidized bed process, no octene is added, and the mixture is injected into reactor 1 through nozzle 3 in a liquid-phase monomer mixing feed mode. The operation process is as follows: Close the second valve 14 and the third valve 15, and open the first valve 13 and the fourth valve 17. Butene, hexene, isopentane and recovered condensate from the refining zone are transported to the mixer 2 through their respective feed pipelines and mixed. The resulting mixture is then transported to the nozzle 3 through the mixture feed pipeline 11 and injected into the reactor 1.

[0039] Example 16: As Figure 1 As shown, in this gas-phase fluidized bed process, octene is added, and the mixture is transported through bypass line 12 to fluidized gas loop line 4 and then injected into reactor 1. The operation process of the liquid-phase monomer mixing feed mode is as follows: Close the third valve 15 and the fourth valve 17, open the first valve 13 and the second valve 14, and the butene, hexene, isopentane, recovered condensate and octene from the refining zone are transported to the mixer 2 through their respective feed lines and mixed. The resulting mixture is transported to the fluidizing gas loop line 4 through the bypass line 12 and then injected into the reactor 1.

[0040] Example 17: As Figure 1 As shown, in this gas-phase fluidized bed process, octene is added, and the mixture is injected into reactor 1 through nozzle 3 in a liquid-phase monomer mixing feed mode. The operation process is as follows: Close the second valve 14 and the third valve 15, and open the first valve 13 and the fourth valve 17. Butene, hexene, isopentane, recovered condensate and octene from the refining zone are transported to the mixer 2 through their respective feed lines and mixed. The resulting mixture is then transported to the nozzle 3 through the mixture feed line 11 and injected into the reactor 1. Polyethylene resin is a widely used chemical product, and the main performance tests for production control include: Density, 910 kg / m³ 3 Up to 965kg / m 3 This is a specific manifestation of material stiffness; Melt index, the mass of polyethylene resin passing through a standard capillary in 10 minutes under specified temperature and pressure (unit: g / 10min), ranging from 0.1 g / 10min to 50 g / 10min, reflects flowability and processing performance; the higher the value, the better the flowability. Tensile yield stress, ranging from 8 MPa to 35 MPa, is the ability of a material to yield to tensile deformation. Tensile strength, ranging from 12 MPa to 40 MPa, reflects the ultimate strength of a material; Tensile modulus, ranging from 100 MPa to 1600 MPa, is a rigid indicator that measures the ability of polyethylene resin to resist elastic tensile deformation. Impact strength, in the range of greater than 5 kJ / m 2 This reflects the high impact strength, making it suitable for low-temperature or impact load scenarios.

[0041] Depending on their different physical properties, polyethylene resin is used in different fields. The selection of liquid-phase monomer octene and the feeding mode are aimed at improving some of its properties to enhance user experience and develop new functions for polyethylene resin.

[0042] Example 18: Taking a polyethylene unit in a petrochemical plant as an example, it adopts the liquid-phase monomer mixed feed mode (with octene added) described in Example 17 to produce a certain grade of product. The reaction conditions are as follows: reactor 1 pressure is 2100 kPa, reaction temperature is 85℃, ethylene (gas phase) molar concentration is 67%, hydrogen to ethylene molar ratio is 0.025:1, hexene to ethylene (gas phase) flow ratio is 0.018:1, and octene to ethylene (gas phase) flow ratio is 0.0013:1. During production, the reaction in reactor 1 is stable, the electrostatic oscillation amplitude is reduced by 3%, and the reaction activity increases from 5100 kg / kg to 5400 kg / kg, an increase of 5.8%, indicating good reaction activity. The powder density is controlled from 927 kg / m³. 3 The melt flow index remained constant at 1.3 g / 10 min. The powder density showed a high responsiveness to the addition of octene, indicating a good overall reaction with no abnormal phenomena such as clumping or increased static electricity. This suggests that the dispersion and vaporization of octene were within safe limits. Performance analysis of the obtained product showed improved appearance compared to the original product (under the same grade) using only hexene copolymerization.

[0043] The tensile yield stress increased from 12.5 MPa to 14.5 MPa, an increase of 16%; the tensile strength increased from 26 MPa to 31.5 MPa, an increase of 21%; the tensile modulus increased from 380 MPa to 450 MPa, an increase of 18%; and the impact strength increased from 57 kJ / m². 2 Increased to 68kJ / m 2Impact strength increased by 19%.

[0044] Therefore, it can be seen that by arbitrarily switching the liquid phase monomer feeding mode in the gas phase fluidized bed process of the present invention, the performance parameters of the resin have been improved, indicating that the addition of the new medium octene has a certain degree of competitiveness in improving the resin performance.

[0045] In summary, this invention allows for switching between single-feed and mixed-feed modes for the feeding of copolymer liquid monomers, which not only facilitates production stability but also provides more diversified production processes, adapts to flexible adjustments for different product grades, and enables the development of high-performance polymer products, effectively enhancing the capacity of reactor 1.

[0046] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A liquid-phase monomer feeding mode in a gas-phase fluidized bed process, characterized in that... In gas-phase fluidized bed production, depending on the requirements of different product grades, the liquid-phase monomer feeding modes include liquid-phase monomer fluidized loop feeding mode and liquid-phase monomer reactor bottom feeding mode.

2. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 1, characterized in that... The liquid phase monomer fluidized loop feeding modes include liquid phase monomer fluidized loop feeding modes without octene addition and liquid phase monomer fluidized loop feeding modes with octene addition. The lower feed modes in the liquid phase monomer reactor include lower feed modes in the liquid phase monomer reactor without octene addition and lower feed modes in the liquid phase monomer reactor with octene addition.

3. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 2, characterized in that... The octene-free liquid-phase monomer fluidized loop feed mode is as follows: isopentane, butene, hexene and recovered condensate from the refining zone are transported to the liquid-phase feed pipeline through their respective feed pipelines, and then injected into the reactor through the fluidizing gas loop pipeline. Alternatively, butene, hexene, isopentane, and recovered condensate from the refining zone are transported to the mixer via their respective feed lines. The resulting mixture is then transported to the fluidizing gas loop via a bypass line and injected into the reactor.

4. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 2 or 3, characterized in that... The liquid-phase monomer fluidized loop feed mode with octene is as follows: First, isopentane, butene, hexene and recovered condensate from the refining zone are transported to the liquid-phase feed line through their respective feed lines, and then injected into the reactor through the fluidizing gas loop line; then, octene is transported to the mixer through the octene feed line, and then transported to the liquid-phase feed line through the bypass line, and then injected into the reactor through the fluidizing gas loop line. Alternatively, butene, hexene, isopentane, recovered condensate, and octene from the refining zone are transported to the mixer via their respective feed lines. The resulting mixture is then transported to the liquid phase feed line via a bypass line and injected into the reactor via the fluidizing gas loop line.

5. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 4, characterized in that... The lower feed mode of the liquid phase monomer reactor without octene addition is as follows: butene, hexene, isopentane and recovered condensate from the refining zone are transported to the liquid phase feed pipeline through their respective feed pipelines, and then transported to the mixed liquid feed pipeline through the bypass pipeline, and then injected into the reactor through the nozzles in the lower part of the reactor. Alternatively, isopentane, butene, hexene, and recovered condensate from the refining zone are transported to the mixer via their respective feed pipelines. The resulting mixture is then transported to the mixture feed pipeline and injected into the reactor through nozzles at the bottom of the reactor.

6. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 5, characterized in that... The lower feed mode of the liquid-phase monomer reactor with added octene is as follows: isopentane, butene, hexene, recovered condensate and octene from the refining zone are transported to the mixer through their respective feed pipelines. The resulting mixture is transported to the mixture feed pipeline and then injected into the reactor through the nozzle at the lower part of the reactor. Alternatively, butene, hexene, isopentane, and recovered condensate from the refining zone are first transported to the liquid phase feed pipeline via their respective feed pipelines, and then transported to the mixed liquid feed pipeline via the bypass pipeline, and then injected into the reactor through the nozzle at the bottom of the reactor. Then, octene is conveyed through a mixer to the mixed liquid feed line and injected into the reactor through a nozzle in the lower part of the reactor.

7. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 6, characterized in that... In gas-phase fluidized bed production, the reactor reaction temperature is 85℃ to 105℃, and the reactor reaction pressure is 2000kPa to 2300kPa.

8. The liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claim 7, characterized in that... In gas-phase fluidized bed production, in both single-feed and mixed-feed modes of the liquid phase monomer, the flow rate of butene is 0 to 5000 kg / h, the flow rate of hexene is 0 to 3500 kg / h, the flow rate of isopentane is 0 to 2000 kg / h, the flow rate of the recovered condensate is 0 to 5000 kg / h, and the flow rate of octene is 0 to 3200 kg / h. Among these, the flow rate of octene is controlled separately or in a cascade control mode using the flow ratio of octene to butene and hexene.

9. An apparatus for implementing the liquid-phase monomer feeding mode in the gas-phase fluidized bed process according to claims 1 to 8, characterized in that... The reactor includes a reactor and a mixer. A nozzle is installed in the lower middle part of the reactor. A fluidizing gas circuit line is fixedly connected to the bottom inlet of the reactor. A liquid feed line is fixedly connected to the fluidizing gas circuit line. A feed mixing line is fixedly connected between the liquid feed line and the first inlet of the mixer. From top to bottom, the feed mixing line is fixedly connected to the isopentane feed line, the butene feed line, the hexene feed line, and the recovered condensate feed line. An octene feed line is fixedly connected to the second inlet of the mixer. A mixed liquid feed line is fixedly connected between the mixer outlet and the nozzle inlet. A bypass line is fixedly connected between the mixed liquid feed line and the liquid feed line.

10. The apparatus according to claim 9, characterized in that... The nozzle inlet is also fixedly connected to a purging pipeline. A first valve is fixedly installed on the feed mixing pipeline between the recovered condensate feed pipeline and the mixer. A second valve is fixedly installed on the bypass pipeline. A third valve is fixedly installed on the liquid phase feed pipeline between the isopentane feed pipeline and the bypass pipeline. A fourth valve is fixedly installed on the mixed liquid feed pipeline between the bypass pipeline and the reactor.

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