Gas phase method production device and production method of polyolefin elastomer

Abstract

The invention relates to a gas phase method production device and a production method of a polyolefin elastomer, and belongs to the technical field of petrochemical engineering. The production device comprises a gas phase fluidized bed reactor, a cryogenic liquefier, a liquefied ethylene pump, an ethylene ejector and a circulating gas heat exchanger, wherein the cryogenic liquefier is connected with an ethylene pipeline of the cracking device and is used for liquefying ethylene prepared by the cracking device to form liquefied ethylene; the ethylene ejector is respectively connected with the liquefied ethylene pump and the fluidization loop of the gas-phase fluidized bed reactor, and is used for conveying liquefied ethylene to the fluidization loop of the gas-phase fluidized bed reactor in an ejection manner to participate in the polymerization reaction of the polyolefin elastomer. The reaction system in the production process of the polyolefin elastomer is cooled by utilizing the inherent gasification latent heat characteristic of the olefin raw material, and the temperature of the polymerization reaction is obviously reduced, so that the heat management optimization in the production process of the polyolefin elastomer is realized, the production load is improved, and the polyolefin elastomer with a lower melting point is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of petrochemical industry and relates to a gas phase production device and a production method of a polyolefin elastomer. Background Art

[0002] Polyolefin elastomer (POE for short) is a product formed by the copolymerization of ethylene and α-olefin (usually 1-butene, 1-hexene, 1-octene, etc.). Generally, the content of the comonomer exceeds 20%. Since the content of the comonomer is much higher than that of conventional polyolefin resins, the α-olefin greatly weakens the crystalline region of the carbon-carbon main chain, forming an amorphous structure similar to rubber elasticity. Therefore, the product has excellent optical properties, mechanical properties, and processing properties. The transmittance, elongation at break, and low-temperature brittleness of the product are better than those of general polyethylene and polypropylene.

[0003] As one of the main production methods of polyolefin elastomers (POE), the solution process has the characteristics of excellent product performance, wide product index range, and multiple molecular weight adjustment methods. Dow Chemical, Mitsui, and ExxonMobil all use this process to produce polyolefin elastomers. However, the solution process also has the disadvantages of difficulty in solvent recovery, high energy consumption, and large equipment investment.

[0004] At present, the gas phase method for producing polyethylene has been developed and used in the production process. The gas phase fluidized bed is a common polymerization reactor for producing polyethylene, which has the characteristics of short reaction process, simple reactor structure, good deashing and degassing effect, etc. However, the gas phase fluidized bed reactor is difficult to reconcile the contradiction between reaction temperature and polymer melting point. If the polymerization temperature is too high, the polymer powder will become sticky, and the block will affect the fluidization state; if the polymerization temperature is too low, the heat release of the polymerization reaction must be strictly controlled, which will affect the catalyst yield and have a negative impact on production cost control.

[0005] Patent CN 107531827 B discloses a method and system for olefin polymerization. The system includes flowing a catalyst through an injection nozzle and into a fluidized bed disposed in a reactor. The method includes flowing a material comprising one or more monomers, one or more inert fluids, or a combination thereof, through the injection nozzle and into the fluidized bed; the material may be at a temperature exceeding ambient temperature. The method also includes contacting one or more olefins with the catalyst in the fluidized bed under conditions sufficient to produce polyolefins.

[0006] Patent CN 105705532 B discloses a method for producing polyolefins, which comprises: contacting a reaction mixture with a reduced chromium oxide catalyst in a gas phase reactor to produce polyolefins, wherein the reaction mixture comprises monomers and comonomers; and changing the reaction temperature in the gas phase reactor by about 1°C or more, thereby changing the gas molar ratio of the comonomer to the monomer by about 2% or more and changing the comonomer content of the polyolefin of substantially constant density by about 2% or more.

[0007] Patent CN 103638877 B discloses a gas-phase fluidized bed reactor, including a gas collection section, a straight section and an expansion section, wherein the gas collection section and the straight section are separated by a gas distribution plate, a rotating shaft and a stirring blade are arranged in the straight section, and a baffle is also arranged in the straight section, wherein the baffle cooperates with the stirring blade to shear the material. The patent also discloses a gas-phase fluidized bed reactor with a stirring system, which can prevent the agglomeration of high-viscosity polymer particles and the adhesion of polymer particles to the inner wall of the reactor without adding auxiliary inert particles, and the gas-phase fluidized bed reactor can produce effective stirring and mixing effects and improve the fluidization stability of high-viscosity polymer particles.

[0008] Based on the production of polyethylene by the gas phase method, the gas phase production process of POE has gradually been developed. Patent CN108948248 B discloses a method for producing polyolefin elastomers by the gas phase method. In this method, the polymerization reaction of POE is carried out in a reactor with polyethylene particles as a seed bed. Specifically, a raw material mixture including ethylene, hydrogen and nitrogen is introduced into the reactor to make the polyethylene particles in the seed bed flow and reach a fluidized state, and then a catalyst is added to the reactor and atomized droplet-shaped comonomer is introduced to react. The comonomer is a long-chain olefin with a carbon number of 6 to 18, and the prepared polymer product has a density of 0.865 to 0.910 g / cm 3 , the long-chain olefin content is 6~40 wt%.

[0009] However, a key technical problem faced by the gas phase production of POE is that due to its unique low melting point characteristics, POE materials require the polymerization reaction to be carried out under relatively low reaction temperature conditions, which places more stringent requirements on the external heat exchange system. Traditionally, gas phase polyethylene production units generally rely on circulating water systems to effectively remove heat, but this method has obvious limitations in its ability to remove heat when dealing with the large amount of polymerization heat generated during the POE production process. Since the reaction temperature in the POE production process is close to the circulating water temperature of the heat exchanger, the polymerization heat is difficult to remove, which not only restricts production load and production efficiency, but may also have an adverse effect on product quality stability.

[0010] Therefore, it is necessary to explore and develop new heat removal devices and technologies that are more efficient and adaptable to low-temperature polymerization environments, so as to achieve more precise and efficient temperature control, thereby ensuring the production efficiency and product quality of POE products. Summary of the invention

[0011] The present invention provides a gas phase production device and a production method for polyolefin elastomer, so as to improve the problem that the current gas phase production device has low heat removal capacity and low production load in POE production. The device of the present invention can effectively remove the heat of the polymerization reaction in the POE production process and reduce the production cost of POE.

[0012] In a first aspect, the present invention provides a gas phase production device for polyolefin elastomer, the production device comprising the following components: A gas-phase fluidized bed reactor, the gas-phase fluidized bed reactor comprising a polymerization reactor and a fluidizing loop (also referred to as a gas-phase fluidizing loop, a reaction fluidizing loop or a reaction loop), the polymerization reactor comprising a diameter section and an expansion section, the diameter section comprising a gas phase distribution plate located at the bottom of the diameter section; a circulating gas outlet is arranged at the top of the polymerization reactor, and a raw gas inlet and a circulating gas (or fluidizing gas) inlet are arranged at the bottom of the polymerization reactor; A cryogenic liquefier connected to the ethylene pipeline of the cracking unit is used to liquefy the ethylene (or refined ethylene) produced by the cracking unit to form liquefied ethylene (or low-temperature ethylene); a liquefied ethylene tank connected to the cryogenic liquefier and used to store liquefied ethylene (also referred to as low-temperature ethylene, low-temperature cold ethylene or low-temperature liquefied ethylene) cooled by the cryogenic liquefier; a liquefied ethylene pump connected to the liquefied ethylene tank and used to transport the liquefied ethylene stored in the liquefied ethylene tank to the reaction fluidization loop of the polymerization reactor; and an ethylene injector, connected to the liquefied ethylene pump and the fluidized loop of the gas-phase fluidized bed reactor, respectively, for injecting liquefied ethylene into the fluidized loop of the gas-phase fluidized bed reactor to participate in the polymerization reaction of the polyolefin elastomer; The circulating gas heat exchanger is located in the fluidizing loop and connected to the top and bottom of the polymerization reactor through pipelines (e.g., 24-inch pipelines) to exchange heat with the circulating gas in the fluidizing loop of the gas phase fluidized bed reactor and remove the reaction heat in the fluidizing loop.

[0013] As an optional embodiment, the cryogenic liquefier includes a compressor and a liquid nitrogen heat exchanger.

[0014] As an optional embodiment, the ethylene injector is installed in the pipeline of the fluidizing loop, the nozzle direction of the ethylene injector is the same as the direction of the circulating gas in the fluidizing loop, and the nozzle is set to a bell mouth of 15°~45°.

[0015] As an optional embodiment, the ethylene injector is installed at the outlet of the circulating gas heat exchanger and at a position more than 10 m away from the pipeline entering the polymerization reactor.

[0016] As an optional embodiment, the ethylene injector is located within 3 meters before and after the inlet of the fluidizing loop, and is located at a position where the inner diameter of the fluidizing pipeline of the fluidizing loop is 1.1 to 1.5 times the inner diameter of the fluidizing pipeline of other fluidizing loops.

[0017] In a second aspect, the present invention provides a gas phase production method of the polyolefin elastomer, wherein the production method uses the gas phase production device of the polyolefin elastomer to carry out a polymerization reaction in the presence of a metallocene catalyst, and the production method comprises the following steps: 1) The polymerization reaction relies on the seed bed to establish a gas phase state. The gas phase in the fluidized loop is compressed by a compressor and injected from the bottom of the polymerization reactor to make the powder in the polymerization reactor fluidized; 2) injecting the low-temperature liquefied ethylene treated by the cryogenic liquefier into the fluidized loop through an ethylene injector, the low-temperature liquefied ethylene exchanges heat with the circulating gas in the fluidized loop, and the gaseous condensing agent and comonomer in the circulating gas are liquefied to form a mixed liquid phase feedstock (for example, in the form of mixed liquid droplets) including the liquefied ethylene, the condensing agent and the comonomer; 3) introducing hydrogen (e.g., in gaseous form) into a fluidizing loop, mixing the liquid feedstock with hydrogen in the fluidizing loop to form a feedstock mixed gas that enters the polymerization reactor, and provides fluidization power to the powder in the polymerization reactor; 4) Injecting the metallocene catalyst into the polymerization reactor to initiate the polymerization reaction.

[0018] In the present invention, the gas phase production method of POE carries out polymerization reaction in the presence of a metallocene catalyst; the polymerization reaction relies on a seed bed to establish a gas phase state, and the circulating gas in the fluidized loop is compressed by a compressor and injected from the bottom of the polymerization reactor, so that the powder in the polymerization reactor is in a fluidized state. The metallocene catalyst is directly injected into the polymerization reactor. Since low-temperature liquefied ethylene is injected into the fluidized loop, it exchanges heat with the circulating gas in the fluidized loop to reduce the temperature of the circulating gas in the fluidized loop, so that the gaseous ethylene, pentane and comonomer in the fluidized loop are liquefied, and the liquefied ethylene, pentane and comonomer form a low-temperature raw material mixed gas with hydrogen and enter the polymerization reactor, providing fluidization power to the powder in the polymerization reactor, and exchanging heat with the reaction system in the polymerization reactor, thereby removing the reaction heat generated by the polymerization reaction.

[0019] As an optional embodiment, the comonomer includes an α-olefin having 4 to 18 carbon atoms.

[0020] As an optional embodiment, the amount of comonomer added is 20~400 kg / t.

[0021] As an optional embodiment, the temperature of the liquefied ethylene (or low-temperature ethylene) when injected into the reaction loop is -50~-90°C.

[0022] As an optional embodiment, the mass fraction of the seed bed in the fluidized powder in the polymerization reactor is 20% to 45%.

[0023] As an optional embodiment, the ethylene content in the liquefied ethylene is 98.3 wt%~99.98 wt%, and the acetylene content is not higher than 1 wt%.

[0024] As an optional implementation, the partial pressure of ethylene in the raw mixed gas is 550-950 kPa, and the partial pressure ratio of hydrogen to ethylene is 0.0001-0.004:1.

[0025] As an optional embodiment, the metallocene catalyst includes a mono-titanium metallocene catalyst.

[0026] As an optional embodiment, during the polymerization reaction, the polymerization temperature is 30-90° C. and the pressure is 1400-2600 kPa.

[0027] As an optional embodiment, the temperature of the lower part of the distribution plate of the polymerization reactor is 5-25°C.

[0028] In the present invention, the temperature of the upper part of the distribution plate of the polymerization reactor reflects the temperature of the polymerization reaction; the difference between the temperature of the lower part of the distribution plate and the uppermost end of the polymerization reactor can reflect the heat release of the polymerization reaction. The condensing agent (including pentane) enters from the bottom and has a condensing effect, so the temperature at the bottom of the distribution plate can monitor the phase state of the condensing agent. When different catalysts are used, the temperature at which the olefin polymerization reaction is initiated is different.

[0029] In the present invention, the above technical features can be freely combined to form a new technical solution without conflicting with each other.

[0030] Compared with the prior art, the technical solution of the present invention has the following beneficial technical effects: (1) The gas phase production method of POE provided by the present invention utilizes the inherent latent heat of vaporization of polymer raw materials and designs a high-efficiency temperature control method to significantly reduce the temperature inside the polymerization reactor, thereby realizing the thermal management optimization of the POE (polyolefin elastomer) production process, which not only greatly improves the production load capacity of POE, but also creates conditions for the preparation of POE with a lower melting point; (2) The gas phase production device of POE provided by the present invention has a more efficient and advanced heat removal system. The heat removal technology in the production method is more efficient and can quickly and accurately remove the heat generated during the polymerization reaction, ensuring that the entire production process is in the optimal temperature range. It can not only effectively improve the production efficiency of POE products and achieve capacity improvement, but also ensure product quality under strict temperature control conditions; (3) The present invention utilizes the inherent vaporization heat absorption property of the polymer raw materials to effectively enhance the efficiency of heat removal during the polymerization reaction. The production device does not require large-scale transformation of the existing polymerization reactor, while ensuring production cost control and achieving an increase in the yield of POE products. After the polymerization reaction heat in the polymerization reactor is effectively removed, POE products with lower melting points can also be produced. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The figure is a schematic structural diagram of a gas phase production device for polyolefin elastomer according to the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0033] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0035] Some embodiments of the present invention provide a gas phase production device for polyolefin elastomer, such as Figure 1 As shown, it includes the following parts: A gas phase fluidized bed reactor, the gas phase fluidized bed reactor comprising a polymerization reactor and a fluidizing loop, the polymerization reactor comprising a diameter section and an expansion section, the diameter section comprising a gas phase distribution plate located at the bottom of the diameter section; a circulating gas outlet is arranged at the top of the polymerization bed reactor, and a raw gas inlet and a circulating gas inlet are arranged at the bottom of the polymerization reactor; A cryogenic liquefier connected to the ethylene pipeline of the cracking unit is used to liquefy the ethylene (or refined ethylene) produced by the cracking unit to form liquefied ethylene (or low-temperature ethylene); a liquefied ethylene tank connected to the cryogenic liquefier and used to store liquefied ethylene (i.e., low-temperature ethylene or low-temperature cold ethylene) cooled by the cryogenic liquefier; a liquefied ethylene pump connected to the liquefied ethylene tank and used to transport the liquefied ethylene stored in the liquefied ethylene tank to the reaction fluidization loop of the polymerization reactor; and an ethylene injector, connected to the liquefied ethylene pump and the fluidized loop of the gas-phase fluidized bed reactor, respectively, for injecting liquefied ethylene into the fluidized loop of the gas-phase fluidized bed reactor to participate in the polymerization reaction of the polyolefin elastomer; The circulating gas heat exchanger is located in the fluidizing loop and connected to the top and bottom of the polymerization reactor through pipelines (e.g., 24-inch pipelines) to exchange heat with the circulating gas in the fluidizing loop of the gas phase fluidized bed reactor and remove the reaction heat in the fluidizing loop.

[0036] In the present invention, the ethylene ejector can fully disperse the liquefied ethylene to prevent the large amount of concentrated liquefied ethylene from eroding the pipeline of the fluidizing loop. The fluidizing loop is a loop of fluidizing gas that is formed by the fluidizing gas coming out of the top of the polymerization reactor and returning to the bottom of the reactor after heat exchange, compression, separation and other steps.

[0037] The present invention adopts a cryogenic liquefier (or freezing station) to cryogenically cool the boundary ethylene (or refined ethylene), and adds the ethylene in the form of liquid phase to the gas phase fluidized bed reactor, and absorbs a large amount of reaction heat by utilizing the latent heat of vaporization, and quickly removes the reaction heat generated by the polymerization reaction in the gas phase fluidized bed reactor, thereby improving the production efficiency of POE. Here, the boundary ethylene refers to ethylene obtained by a device other than a polyethylene production device, for example, obtained by a cracking device.

[0038] As an optional embodiment, the cryogenic liquefier includes a compressor and a liquid nitrogen heat exchanger.

[0039] As an optional embodiment, the ethylene injector is installed in the pipeline of the fluidizing loop, the nozzle direction of the ethylene injector is in the same direction as the direction of the circulating gas in the fluidizing loop, and the nozzle is set to a bell mouth of 15°~45° (for example, 20°, 25°, 30°, 35° or 40°).

[0040] As an optional embodiment, the ethylene injector is installed at the outlet of the circulating gas heat exchanger and at a position more than 10 m away from the pipeline entering the polymerization reactor.

[0041] As an optional embodiment, the ethylene injector is located within 3 meters before and after the inlet of the fluidizing loop, and is located at a position where the inner diameter of the fluidizing pipeline of the fluidizing loop is 1.1 to 1.5 times the inner diameter of the fluidizing pipeline of other fluidizing loops.

[0042] In a second aspect, the present invention provides a gas phase production method of the polyolefin elastomer, wherein the production method uses the gas phase production device of the polyolefin elastomer to carry out a polymerization reaction in the presence of a metallocene catalyst, and the production method comprises the following steps: 1) The polymerization reaction relies on the seed bed to establish a gas phase state. The gas phase in the fluidized loop is compressed by a compressor and injected from the bottom of the polymerization reactor to make the powder in the polymerization reactor fluidized; 2) injecting the low-temperature liquefied ethylene treated by the cryogenic liquefier into the fluidized loop through an ethylene injector, the low-temperature liquefied ethylene exchanges heat with the circulating gas in the fluidized loop, and the gaseous condensing agent and comonomer in the circulating gas are liquefied to form a mixed liquid phase feedstock (for example, in the form of mixed liquid droplets) including the liquefied ethylene, the condensing agent and the comonomer; 3) introducing hydrogen (e.g., in gaseous form) into a fluidizing loop, mixing the liquid feedstock with hydrogen in the fluidizing loop to form a feedstock mixed gas that enters the polymerization reactor, and provides fluidization power to the powder in the polymerization reactor; 4) Injecting the metallocene catalyst into the polymerization reactor to initiate the polymerization reaction.

[0043] In the present invention, the gas phase production method of POE carries out polymerization reaction in the presence of a metallocene catalyst; the polymerization reaction relies on a seed bed to establish a gas phase state, and the circulating gas in the fluidized loop is compressed by a compressor and injected from the bottom of the polymerization reactor, so that the powder in the polymerization reactor is in a fluidized state. The metallocene catalyst is directly injected into the polymerization reactor. Since low-temperature liquefied ethylene is injected into the fluidized loop, it exchanges heat with the circulating gas in the fluidized loop to reduce the temperature of the circulating gas in the fluidized loop, so that the gaseous ethylene, pentane and comonomer in the fluidized loop are liquefied, and the liquefied ethylene, pentane and comonomer form a low-temperature raw material mixed gas with hydrogen and enter the polymerization reactor, providing fluidization power to the powder in the polymerization reactor, and exchanging heat with the reaction system in the polymerization reactor, thereby removing the reaction heat generated by the polymerization reaction.

[0044] In some embodiments, the condensing agent comprises pentane.

[0045] In some embodiments, the comonomer includes an α-olefin having 4 to 18 carbon atoms (eg, 5, 6, 8, 10, 12, 15, or 17).

[0046] In some embodiments, the amount of comonomer added is 20 to 400 kg / t (e.g., 50 kg / t, 100 kg / t, 150 kg / t, 200 kg / t, 250 kg / t, 300 kg / t, or 350 kg / t).

[0047] In some embodiments, the temperature of the liquefied ethylene (or low-temperature ethylene) when injected into the reaction loop is -50 to -90°C (eg, -60°C, -70°C, -80°C or -85°C).

[0048] In some embodiments, the mass fraction of the seed bed in the fluidized powder in the polymerization reactor is 20% to 45% (eg, 25%, 30%, 35%, 40% or 42%).

[0049] In some embodiments, the ethylene content in the liquefied ethylene is 98.3 wt% to 99.98 wt%, and the acetylene content is not higher than 1 wt%.

[0050] In some embodiments, the partial pressure of ethylene in the raw mixed gas is 550-950 kPa (e.g., 600 kPa, 650 kPa, 700 kPa, 750 kPa, 800 kPa, 850 kPa or 900 kPa), and the partial pressure ratio of hydrogen to ethylene is 0.0001-0.004:1.

[0051] In some embodiments, the metallocene catalyst comprises a mono-titanium-metallocene catalyst.

[0052] In some embodiments, during the polymerization reaction, the polymerization temperature is 30-90°C (eg, 40°C, 50°C, 60°C, 70°C, or 80°C), and the pressure is 1400-2600 kPa (eg, 1500 kPa, 1800 kPa, 2000 kPa, 2200 kPa, or 2400 kPa).

[0053] In some embodiments, the temperature of the lower portion of the distribution plate of the polymerization reactor (ie, gas phase fluidized bed reactor) is 5 to 25° C. (eg, 10° C., 15° C., or 20° C.).

[0054] In the present invention, the polymerization reactor adopts a conventional gas-phase fluidized bed reactor in the art. The present invention does not improve the internal structure of the gas-phase fluidized bed reactor. Therefore, the structure of the gas-phase fluidized bed reactor is not described in detail here, and only the relevant components involved in the present invention are described.

[0055] Example 1 A gas phase production device for polyolefin elastomer, such as Figure 1 As shown, it includes a gas-phase fluidized bed reactor, a cryogenic liquefier, a liquefied ethylene tank, a liquefied ethylene pump, an ethylene ejector and a circulating gas heat exchanger, which are specifically introduced as follows.

[0056] The gas phase fluidized bed reactor comprises a polymerization reactor and a fluidizing loop; wherein the polymerization reactor comprises a diameter section and an expansion section, a gas phase distribution plate is arranged at the bottom of the diameter section, and is 0.6 to 1 m (e.g., 0.8 m) away from the bottom end of the polymerization reactor, and the powder is in a fluidized state on the gas phase distribution plate and circulates in the expansion section; a circulating gas outlet is arranged at the top of the polymerization reactor, and a raw gas inlet and a circulating gas inlet are arranged at the bottom.

[0057] The cryogenic liquefier is connected to the ethylene pipeline of the cracking unit, and comprises a compressor and a liquid nitrogen heat exchanger, and is used for cryogenically liquefying the refined ethylene prepared by the cracking unit to form liquefied ethylene.

[0058] The liquefied ethylene tank is connected to the cryogenic liquefier and is used to store the liquefied ethylene (ie, low-temperature ethylene or low-temperature cold ethylene) cooled by the cryogenic liquefier.

[0059] The liquefied ethylene pump is connected to the liquefied ethylene tank and is used to transport the liquefied ethylene stored in the liquefied ethylene tank to the reaction fluidization loop of the polymerization reactor.

[0060] The ethylene injector is connected to the liquefied ethylene pump and the polymerization reactor respectively, and is installed in the pipeline of the fluidized loop, at the outlet of the circulating gas heat exchanger and at a position more than 10 m away from the pipeline entering the polymerization reactor. In addition, the ethylene injector is located within 3 meters before and after the inlet of the fluidized loop, and the inner diameter of the fluidized pipeline of the fluidized loop is 1.1 to 1.5 times the inner diameter of the fluidized pipeline of other fluidized loops. The nozzle direction of the ethylene injector is the same as the flow direction of the circulating gas in the fluidized loop, and the nozzle is set to a bell mouth of 15° to 45°; the ethylene injector is used to inject liquefied ethylene to the gas phase fluidized loop of the polymerization reactor to participate in the polymerization reaction of the polyolefin elastomer.

[0061] The circulating gas heat exchanger is located in the fluidized loop, and is connected to the top and bottom of the polymerization reactor through pipelines. It is used to exchange heat with the circulating gas in the fluidized loop of the polymerization reactor and remove the reaction heat in the fluidized loop.

[0062] In the present invention, the ethylene ejector can fully disperse the liquefied ethylene to prevent the large amount of concentrated liquefied ethylene from eroding the pipeline of the fluidizing loop. The fluidizing loop is a loop of fluidizing gas that is formed by the fluidizing gas coming out of the top of the reactor and returning to the bottom of the reactor after heat exchange, compression, separation and other steps.

[0063] The present invention adopts a cryogenic liquefier (or freezing station) to cryogenically cool the refined ethylene, and adds the ethylene in the form of liquid into the gas phase fluidized bed reactor, utilizing the latent heat of vaporization to absorb a large amount of reaction heat, thereby improving the POE production efficiency.

[0064] Example 2 This embodiment provides a gas phase production device for polyolefin elastomer, which is different from the embodiment 1 in that: The ethylene injector is installed in the fluidizing loop pipeline, and at the outlet of the circulating gas heat exchanger, 12 m away from the pipeline entering the reactor; in addition, the ethylene injector is located 3 m away from the inlet of the fluidizing loop, and at a position where the inner diameter of the fluidizing pipeline is 1.4 times the inner diameter of other fluidizing loop pipelines; the nozzle direction of the ethylene injector is in the same direction as the airflow direction of the circulating gas in the fluidizing loop, and the nozzle is set to a 40° bell mouth.

[0065] Example 3 This embodiment provides a gas phase production device for polyolefin elastomer, which is different from the embodiment 1 in that: The ethylene injector is installed in the fluidizing loop pipeline, and at the outlet of the circulating gas heat exchanger, 11 m away from the pipeline entering the reactor; in addition, the ethylene injector is located 3 meters away from the inlet of the fluidizing loop, and at a position where the inner diameter of the fluidizing pipeline is 1.2 times the inner diameter of other fluidizing loop pipelines; the nozzle direction of the ethylene injector is in the same direction as the airflow direction of the circulating gas in the fluidizing loop, and the nozzle is set to a 40° bell mouth.

[0066] Example 4 This embodiment provides a gas phase production device for polyolefin elastomer, which is different from the embodiment 1 in that: The ethylene injector is installed in the fluidized loop pipeline, and at the outlet of the circulating gas heat exchanger, 12 m away from the reactor pipeline; in addition, the ethylene injector is located 3 m away from the inlet of the fluidized loop, and at a position where the inner diameter of the fluidized pipeline is 1.1 times the inner diameter of other fluidized loop pipelines. The nozzle direction of the ethylene injector is in the same direction as the flow direction of the circulating gas in the fluidized loop, and the nozzle is set to a 20° bell mouth.

[0067] Example 5 A gas phase production method for polyolefin elastomer, using the gas phase production device for polyolefin elastomer in Example 2, and carrying out polymerization reaction in the presence of a single titanocene metallocene catalyst, the production method comprises the following steps.

[0068] Step S1: A gas phase state is established by relying on a seed bed. The gas phase in the fluidized loop is compressed by a compressor and then injected from the bottom of the polymerization reactor to fluidize the powder in the polymerization reactor. The mass fraction of the seed bed in the fluidized powder in the polymerization reactor is 45%.

[0069] Step S2: liquefied ethylene treated by a cryogenic liquefier is continuously injected into a fluidized loop by an ethylene injector, the low-temperature liquefied ethylene is heat exchanged with the circulating gas in the fluidized loop, and the gaseous condensing agent (for example, pentane) and comonomer in the circulating gas are liquefied to form a mixed liquid phase raw material including liquefied ethylene, condensing agent and comonomer; wherein the temperature of the liquefied ethylene when injected into the fluidized loop is -77°C, and the comonomer is an α-olefin with 8 carbon atoms, namely 1-octene; the ethylene content in the liquefied ethylene is 99.98%, and the acetylene content is 0.01%.

[0070] Step S3: hydrogen (for example, in gaseous form) is introduced into the fluidized loop, and the liquid phase raw material and hydrogen are mixed in the fluidized loop to form a raw material mixed gas, which enters the polymerization reactor, provides fluidization power to the powder in the polymerization reactor, and exchanges heat with the polymerization reaction system at the same time. The partial pressure of ethylene in the raw material mixed gas is 940 kPa, the partial pressure ratio of hydrogen to ethylene is 0.003:1, and the amount of comonomer added is 45 kg / t.

[0071] Step S4: injecting a metallocene catalyst into a polymerization reactor to initiate a polymerization reaction; during the polymerization reaction, unreacted ethylene and comonomers, as well as gaseous condensing agents and circulating gases flow out from the top of the polymerization reactor into the fluidized loop. Since liquefied ethylene is continuously injected into the fluidized loop, it exchanges heat with the circulating gas, ethylene, comonomers and condensing agents in the fluidized loop, and then is injected into the polymerization reactor from the bottom of the polymerization reactor, providing fluidization power to the powder in the polymerization reactor, participating in the polymerization reaction and exchanging heat with the polymerization reaction system, removing the polymerization reaction heat, lowering the polymerization reaction temperature, and ensuring the normal operation of the polymerization reaction. Among them, the polymerization reaction temperature is 36°C, the pressure is 2400 kPa, and the temperature of the lower part of the distribution plate of the fluidized bed reactor is 18°C; after the reaction stays for 7 hours, the prepared polyolefin elastomer powder is extracted from the gas phase fluidized reactor.

[0072] Example 6 A gas phase production method for polyolefin elastomer, using the gas phase production device for polyolefin elastomer in Example 3, and carrying out polymerization reaction in the presence of a single titanocene metallocene catalyst, the production method comprises the following steps.

[0073] Step S1: A gas phase state is established by relying on a seed bed. The gas phase in the fluidized loop is compressed by a compressor and then injected from the bottom of the polymerization reactor to fluidize the powder in the polymerization reactor. The mass fraction of the seed bed in the fluidized powder in the polymerization reactor is 35%.

[0074] Step S2: liquefied ethylene treated by a cryogenic liquefier is continuously injected into a fluidized loop by an ethylene injector, the low-temperature liquefied ethylene is heat exchanged with the circulating gas in the fluidized loop, and the gaseous condensing agent (for example, pentane) and comonomer in the circulating gas are liquefied to form a mixed liquid phase raw material including liquefied ethylene, condensing agent and comonomer; wherein the temperature of the liquefied ethylene when injected into the fluidized loop is -60°C, and the comonomer is an α-olefin with a carbon number of 6; the ethylene content in the liquefied ethylene is 99.91%, and the acetylene content is 0.03%.

[0075] Step S3: hydrogen (for example, in gaseous form) is introduced into the fluidized loop, and the liquid phase raw material and hydrogen are mixed in the fluidized loop to form a raw material mixed gas, which enters the polymerization reactor, provides fluidization power to the powder in the polymerization reactor, and exchanges heat with the polymerization reaction system at the same time. The partial pressure of ethylene in the raw material mixed gas is 790 kPa, the partial pressure ratio of hydrogen to ethylene is 0.0025:1, and the amount of comonomer added is 110 kg / t.

[0076] Step S4: injecting a metallocene catalyst into a polymerization reactor to initiate a polymerization reaction; during the polymerization reaction, unreacted ethylene and comonomers, as well as gaseous condensing agents and circulating gas flow out from the top of the polymerization reactor into the fluidized loop. Since liquefied ethylene is continuously injected into the fluidized loop, it exchanges heat with the circulating gas, ethylene, comonomers and condensing agents in the fluidized loop, and then is injected into the polymerization reactor from the bottom of the polymerization reactor, providing fluidization power to the powder in the polymerization reactor, participating in the polymerization reaction and exchanging heat with the polymerization reaction system, removing the polymerization reaction heat, lowering the polymerization reaction temperature, and ensuring the normal operation of the polymerization reaction. Among them, the polymerization reaction temperature is 42°C and the pressure is 2050 kPa; the temperature under the distribution plate of the fluidized bed reactor is 20°C; after the reaction stays for 7 hours, the prepared polyolefin elastomer powder is extracted from the gas phase fluidized reactor.

[0077] Example 7 A gas phase production method for polyolefin elastomer, using the gas phase production device for polyolefin elastomer in Example 4, to carry out polymerization reaction in the presence of a single titanocene metallocene catalyst, the production method comprising the following steps.

[0078] Step S1: A gas phase state is established by relying on a seed bed. The gas phase in the fluidized loop is compressed by a compressor and then injected from the bottom of the polymerization reactor to fluidize the powder in the polymerization reactor. The mass fraction of the seed bed in the fluidized powder in the polymerization reactor is 27%.

[0079] Step S2: liquefied ethylene treated by a cryogenic liquefier is continuously injected into a fluidized loop by an ethylene injector, the low-temperature liquefied ethylene is heat exchanged with the circulating gas in the fluidized loop, and the gaseous condensing agent (for example, pentane) and comonomer in the circulating gas are liquefied to form a mixed liquid phase raw material including liquefied ethylene, condensing agent and comonomer; wherein the temperature of the liquefied ethylene when injected into the fluidized loop is -57°C, and the comonomer is an α-olefin with 4 carbon atoms; the ethylene content in the liquefied ethylene is 98.9%, and the acetylene content is 0.05%.

[0080] Step S3: hydrogen (for example, in gaseous form) is introduced into the fluidized loop, and the liquid phase raw material and hydrogen are mixed in the fluidized loop to form a raw material mixed gas, which enters the polymerization reactor, provides fluidization power to the powder in the polymerization reactor, and exchanges heat with the polymerization reaction system at the same time. The partial pressure of ethylene in the raw material mixed gas is 660 kPa, the partial pressure ratio of hydrogen to ethylene is 0.0015:1, and the amount of comonomer added is 180 kg / t.

[0081] Step S4: injecting a metallocene catalyst into a polymerization reactor to initiate a polymerization reaction; during the polymerization reaction, unreacted ethylene and comonomers, as well as gaseous condensing agents and circulating gas flow out from the top of the polymerization reactor into the fluidized loop. Since liquefied ethylene is continuously injected into the fluidized loop, it exchanges heat with the circulating gas, ethylene, comonomers and condensing agents in the fluidized loop, and then is injected into the polymerization reactor from the bottom of the polymerization reactor, providing fluidization power to the powder in the polymerization reactor, participating in the polymerization reaction and exchanging heat with the polymerization reaction system, removing the polymerization reaction heat, lowering the polymerization reaction temperature, and ensuring the normal operation of the polymerization reaction. Among them, the polymerization reaction temperature is 50°C and the pressure is 1880 kPa; the temperature under the distribution plate of the fluidized bed reactor is 24°C; after the reaction stays for 7 hours, the prepared polyolefin elastomer powder is extracted from the gas phase fluidized reactor.

[0082] Comparative Example 1 A gas phase production method for polyolefin elastomer, which differs from Example 5 in that: Ethylene was fed in gaseous state through an ethylene injector and injected into the fluidizing loop, with an inlet temperature of 75°C; the ethylene injector was installed in the fluidizing loop pipeline, in the same direction as the fluidizing gas flow, and the nozzle was set to a 40° bell mouth. The temperature of the polymerization reactor was 50°C, the pressure was 2400 kPa, and the temperature under the distribution plate was 42°C.

[0083] Comparative Example 2 A gas phase production method for polyolefin elastomer, which differs from Example 6 in that: Ethylene is not cryogenically liquefied, but fed in gaseous state through an ethylene injector and injected into the fluidizing loop with an inlet temperature of 78°C. The ethylene injector is installed in the fluidizing loop pipeline in the same direction as the fluidizing gas flow, and the nozzle is set to a 40° bell mouth. The polymerization reactor temperature is about 59°C and the pressure is 2400 kPa. The temperature under the distribution plate is about 47°C.

[0084] Comparative Example 3 A gas phase production method for polyolefin elastomer, which differs from Example 7 in that: Ethylene is fed in gaseous state through an ethylene injector and injected into the fluidized loop, with an inlet temperature of 80°C; the ethylene injector is installed in the center of the fluidized loop pipeline, in the same direction as the fluidized gas flow, and the nozzle is set to a 20° bell mouth. The polymerization reactor temperature is about 62.5°C and the pressure is 2400 kPa; the temperature under the distribution plate of the gas phase fluidized bed reactor is maintained at about 51°C; The production loads of the gas phase production methods of polyolefin elastomers provided by Examples 5 to 7 and Comparative Examples 1 to 3 and the lowest melting points of the prepared POE are shown in Table 1.

[0085] Table 1:

[0086] As can be seen from Table 1, the gas phase production apparatus for polyolefin elastomer provided in Examples 2 to 4 of the present invention and the gas phase production method for polyolefin elastomer provided in Examples 5-7 can increase the production load of POE, and the melting point of the produced POE is significantly reduced.

[0087] Table 2 shows the performance comparison between the polyolefin elastomer POE prepared by the preparation method of the present invention and conventional PE (LLDPE).

[0088] Table 2:

[0089] It can be seen from Table 2 that, compared with conventional PE, the polyolefin elastomer gas phase production device and method of the present invention can produce POE with higher melt index, lower density, excellent tensile properties and strong toughness.

[0090] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0091] In the present invention, in the absence of any contrary description, the directional words used, such as "upper" and "lower", are specifically the directions of the drawings in the accompanying drawings. In addition, in the description of the specification of the present invention, the terms "including", "comprising", etc. refer to "including but not limited to". In this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of the associated objects, indicating that three relationships may exist, for example, A and / or B, which can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A, B can be singular or plural. In this article, "at least one" refers to one or more, and "plural" refers to two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of singular or plural items.

[0092] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A gas phase production device for polyolefin elastomer, characterized in that: The production device comprises the following components: A gas phase fluidized bed reactor, the gas phase fluidized bed reactor comprising a polymerization reactor and a fluidizing loop, the polymerization reactor comprising a diameter section and an expansion section, the diameter section comprising a gas phase distribution plate located at the bottom of the diameter section; a circulating gas outlet is arranged at the top of the polymerization reactor, and a raw gas inlet and a circulating gas inlet are arranged at the bottom of the polymerization reactor; A cryogenic liquefier connected to the ethylene pipeline of the cracking unit and used to liquefy the ethylene produced by the cracking unit to form liquefied ethylene; a liquefied ethylene tank connected to the cryogenic liquefier and used to store liquefied ethylene cooled by the cryogenic liquefier; a liquefied ethylene pump connected to the liquefied ethylene tank and used to transport the liquefied ethylene stored in the liquefied ethylene tank to the reaction fluidization loop of the polymerization reactor; an ethylene injector, connected to the liquefied ethylene pump and the fluidizing loop of the gas-phase fluidized bed reactor, respectively, for injecting liquefied ethylene into the fluidizing loop of the gas-phase fluidized bed reactor to participate in the polymerization reaction of the polyolefin elastomer; and The circulating gas heat exchanger is located in the fluidized loop and connected to the top and bottom of the polymerization reactor through pipelines. It is used to exchange heat with the circulating gas in the fluidized loop of the gas phase fluidized bed reactor and remove the reaction heat in the fluidized loop.

2. The gas phase production device for polyolefin elastomer according to claim 1, characterized in that: The cryogenic liquefier comprises a compressor and a liquid nitrogen heat exchanger.

3. The gas phase production device for polyolefin elastomer according to claim 1, characterized in that: The ethylene injector is installed in the pipeline of the fluidized loop. The nozzle direction of the ethylene injector is the same as the direction of the circulating gas in the fluidized loop. The nozzle is set to a bell mouth of 15° to 45°.

4. The gas phase production device for polyolefin elastomer according to claim 3, characterized in that: The ethylene injector is installed at the outlet of the circulating gas heat exchanger and at a position more than 10 m away from the pipeline entering the polymerization reactor.

5. The gas phase production device for polyolefin elastomer according to claim 4, characterized in that: The ethylene injector is located within 3 meters before and after the inlet of the fluidizing loop, and is located at a position where the inner diameter of the fluidizing pipeline of the fluidizing loop is 1.1 to 1.5 times the inner diameter of the fluidizing pipeline of other fluidizing loops.

6. A gas phase production method for polyolefin elastomer, characterized in that: The production method uses a gas phase production device for polyolefin elastomer according to any one of claims 1 to 5 to carry out a polymerization reaction in the presence of a metallocene catalyst, and the production method comprises the following steps: 1) The polymerization reaction relies on the seed bed to establish a gas phase state. The gas phase in the fluidized loop is compressed by a compressor and injected from the bottom of the polymerization reactor to make the powder in the polymerization reactor fluidized; 2) injecting the low-temperature liquefied ethylene treated by the cryogenic liquefier into the fluidized loop through the ethylene injector, the low-temperature liquefied ethylene exchanges heat with the circulating gas in the fluidized loop, and the gaseous condensing agent and comonomer in the circulating gas are liquefied to form a mixed liquid phase raw material including liquefied ethylene, condensing agent and comonomer; 3) hydrogen is introduced into the fluidizing loop, where the liquid raw material is mixed with hydrogen to form a raw material mixed gas which enters the polymerization reactor, providing fluidizing power to the powder in the polymerization reactor; 4) Injecting the metallocene catalyst into the polymerization reactor to initiate the polymerization reaction.

7. The gas phase production method of polyolefin elastomer according to claim 6, characterized in that: The comonomer includes an α-olefin having 4 to 18 carbon atoms.

8. The gas phase production method of polyolefin elastomer according to claim 7, characterized in that: The amount of comonomer added is 20~400 kg / t.

9. The gas phase production method of polyolefin elastomer according to claim 6, characterized in that: The temperature of liquefied ethylene when injected into the reaction loop is -50~-90℃.

10. The gas phase production method of polyolefin elastomer according to claim 6, characterized in that: The mass fraction of the seed bed in the fluidized powder in the polymerization reactor is 20% to 45%.

11. The gas phase production method of polyolefin elastomer according to claim 6, characterized in that: The ethylene content in the liquefied ethylene is 98.3 wt%~99.98 wt%, and the acetylene content is not higher than 1wt%.

12. The gas phase production method of polyolefin elastomer according to claim 6, characterized in that: The partial pressure of ethylene in the raw mixed gas is 550~950 kPa, and the partial pressure ratio of hydrogen to ethylene is 0.0001~0.004:

1.

13. The gas phase production method of polyolefin elastomer according to claim 6, characterized in that: The metallocene catalyst includes a mono-titanium-metallocene catalyst.

14. The gas phase production method of a polyolefin elastomer according to any one of claims 6 to 13, characterized in that: During the polymerization reaction, the polymerization temperature is 30~90°C and the pressure is 1400~2600 kPa.

15. The gas phase production method of polyolefin elastomer according to claim 14, characterized in that: The temperature of the lower part of the distribution plate of the polymerization reactor is 5~25℃.

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