A dry powder catalyst feeding device

Abstract

This utility model discloses a dry powder catalyst feeding device, which includes filling, metering, purging, injection, and control instrumentation modules. In the filling module, a filling tank and a feeding hopper are connected in series. In the metering module, a catalyst metering valve, paired with a specific volume metering cup, is positioned between the filling tank and the feeding hopper to achieve precise metering. The purging module utilizes a nitrogen buffer and a multi-way valve group to perform pressure replenishment and backflushing functions. The injection module employs a special reduced-diameter short-connection design to ensure high-speed injection of material into the reactor. The control instrumentation module monitors key node parameters in real time. This utility model achieves long-term stable and continuous addition of dry powder catalyst to a gas-phase fluidized bed, effectively solving the long-term pipe blockage problem of dry powder catalyst feeders in polyethylene plants, improving the stability and accuracy of catalyst feeding, ensuring stable reactor operation, and providing a reliable and efficient solution for related chemical production processes, significantly improving production efficiency and product quality.

Description

Technical Field

[0001] This utility model relates to the field of olefin polymerization, and specifically to a dry powder catalyst feeding device, particularly in the field of adding polyethylene dry powder catalyst to a gas-phase ethylene polymerization reactor in a gas-phase fluidized bed process. Background Technology

[0002] Gas-phase polyolefin (GPE) processes are a crucial component of GPE production. Currently, the main GPE processes in China include: UCC's Unipol gas-phase fluidized bed process, BP's Innovene gas-phase fluidized bed process, and Sinopec's GPE gas-phase fluidized bed process. In the production process, the catalyst is the core of the entire polymerization reaction. Processes such as UCC's Unipol and BP's Innovene require the addition of dry powder catalysts. To ensure long-term stable operation of the polymerization reaction, it is necessary to guarantee a stable and reliable dry powder catalyst feeding rate and prevent clogging of the injection pipe. Therefore, a dry powder catalyst feeding method has been developed. The dry powder catalyst is metered according to the catalyst requirements of the polymerization reactor through a dry powder catalyst feeding system and stably and continuously added to the gas-phase polymerization reactor via pipeline. The operating status of the feeder directly affects the reactor, and the catalyst feeding rate is a crucial parameter determining the polymerization yield.

[0003] Currently, UCC's Unipol gas-phase fluidized bed process, BP's Innovene gas-phase fluidized bed process, and Sinopec's GPE gas-phase fluidized bed process all have corresponding dry powder catalyst feeding systems. However, different problems exist in practical applications, preventing the feeding systems from operating stably for long periods, affecting the stability of the catalyst feeding rate, and consequently impacting the polymerization reaction. Common faults in UCC's Unipol gas-phase fluidized bed process's Mark V-type dry powder feeding system include: clogging of the injection tube and deformation of the injection tube. BP's Innovene gas-phase fluidized bed uses a decentralized feeding system, which suffers from a long process flow and the disadvantage of clogging in the discharge pipeline. The dry powder feeder manufactured by the 11th Research Institute of China Aerospace Science and Technology Corporation can be used in Sinopec's GPE gas-phase fluidized bed process, but it suffers from unstable feeding (forced feeding), inaccurate metering, and pipeline clogging.

[0004] Therefore, there is a need to develop a device / method that can achieve long-term, stable, continuous, and accurately metered addition of dry-powder polyethylene catalyst to a gas-phase fluidized bed reactor, while avoiding damage to the dry-powder polyolefin catalyst particles and protecting the catalyst morphology. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a dry powder catalyst feeding device.

[0006] This invention enables the long-term, stable, and continuous addition of dry powder polyethylene catalyst to a gas-phase fluidized bed reactor without clogging the feed pipeline.

[0007] The objective of this utility model can be achieved through the following technical solutions: One of the technical solutions of this utility model provides a dry powder catalyst feeding device for injecting dry powder catalyst into a reactor. The device includes a filling module, a metering module, and an injection module. The filling module is used to store and transport the dry powder catalyst, the metering module is used to accurately meter the material (the material referred to in this utility model is the catalyst), and the injection module delivers the material into the reactor. The metering module is located in the filling module, the outlet of the filling module is connected to the inlet of the injection module through a main pipeline, and the outlet of the injection module is connected to the inlet of the reactor.

[0008] Furthermore, the filling module includes a filling tank and a feeding hopper; the metering module includes a catalyst metering valve and a feeding valve assembly; the injection module feeds the dry catalyst powder into the reactor at high speed, and the outlet of the injection module is sealed to the reactor inlet. The filling tank is positioned above the feeding hopper, the catalyst metering valve is located on the pipeline between the filling tank and the feeding hopper, and the feeding hopper is connected to the injection module via a main pipeline.

[0009] Furthermore, the filling tank has a conical structure, preferably a cone or pyramid, wider at the top and narrower at the bottom, with the upper port serving as the material inlet and the lower port as the discharge outlet. A guide pipe is provided at the center of the top of the filling tank, and the lower port is connected to the upper port of the feeding hopper via a pipeline. The functions of the guide pipe are: 1) to pour out the material in the tank; 2) to guide the flow of powder and granular materials.

[0010] Furthermore, the feeding hopper has a conical structure, preferably a cone or pyramid, with the upper end serving as the catalyst inlet and the lower end as the catalyst outlet. The catalyst inlet has two downward-sloping oblique holes; these holes connect to the first and second nitrogen inlets. The feeding hopper utilizes gravity to allow the material to slide down naturally, reducing accumulation and blockage. The conical inner wall guides the material to fall evenly, making it suitable for conveying bulk materials such as granules and powders. The feeding speed can be easily controlled by adjusting the cone angle and taper.

[0011] Furthermore, the catalyst inlet is designed as DN50 (indicating a nominal diameter of 50 mm for the hopper inlet), with a flange connection, while the catalyst outlet is designed as DN15, also with a flange connection. Two φ5 downward-sloping 45° holes are designed on the catalyst inlet flange to facilitate the replenishment of pressure into the hopper by external nitrogen gas. Simultaneously, these holes can backflush the metering valve core to prevent dry powder from adhering to it and affecting metering and feeding.

[0012] Furthermore, the first and second nitrogen inlets of the feeding hopper are DN15, and the outlet is φ5 (i.e., the aforementioned oblique hole), which is connected to high-pressure nitrogen. When the high-pressure nitrogen is replenished, it can purge the metering valve core (metering cup) to prevent the catalyst from adhering to the metering cup and affecting the feeding of the metering cup.

[0013] Furthermore, the catalyst metering valve is installed on the pipeline between the filling tank and the feeding hopper. The feeding port on the catalyst metering valve is adapted to a metering cup. The rotating shaft (or valve cover, valve) of the catalyst metering valve is driven by a servo motor to rotate at a certain angle to achieve material discharge. For example, when the discharge command is triggered, the servo motor immediately enters the working state, and its output shaft is flexibly connected to the rotating shaft of the catalyst metering valve through a coupling, stably transmitting torque to the transmission structure inside the valve body. After the discharge is completed, the servo motor drives the catalyst metering valve to reset in the reverse direction. Even further, the feeding port on the catalyst metering valve can be adapted to a 10-120mL PTFE or metal metering cup. PTFE is corrosion-resistant and non-stick, while metal is high-temperature resistant and has high strength.

[0014] Furthermore, the feeding valve assembly includes a nitrogen pressure replenishment valve, a catalyst injection valve, a shut-off valve, a needle valve, and a start / stop valve; used to control the start and stop of nitrogen backflushing pressure replenishment and material injection; the nitrogen pressure replenishment valve is used to control nitrogen backflushing and pressure replenishment, the needle valve assists in pressure replenishment control, and the catalyst injection valve, shut-off valve, and start / stop valve are used to control the start and stop of injection; the shut-off valve, catalyst injection valve, and start / stop valve are installed on the main pipeline, and the nitrogen pressure replenishment valve and needle valve are installed on the pipeline of the purging module.

[0015] Furthermore, the injection module consists of a sleeve, an injection tube connecting flange, an injection end flange, a three-way ball valve, a packing pipe flange, and a guide connecting flange; the injection module is arranged in the following order along the flow direction: guide connecting flange → packing pipe flange → three-way ball valve → injection end flange → injection tube connecting flange → sleeve; each component is connected by threaded connection; the guide connecting flange is connected to the start / stop valve, and the sleeve is connected to the reactor.

[0016] Furthermore, the device also includes a purging module for providing high-pressure nitrogen to the device. The purging module includes a nitrogen buffer, an auxiliary pressure-replenishing pipeline, a pressure-replenishing backflush pipeline, and an ethylene purging pipeline. The pressure-replenishing backflush pipeline is connected to the first and second nitrogen inlets of the feeding hopper. A nitrogen pressure-replenishing valve is installed on the pressure-replenishing backflush pipeline. The auxiliary pressure-replenishing pipeline is connected to the main pipeline via a needle valve, with the connection point located at the rear end of the catalyst injection valve and the front end of the start / stop valve. The ethylene purging pipeline is connected to the third outlet of the three-way ball valve of the injection module. Nitrogen entering from the first and second nitrogen inlets simultaneously passes through the backflush valve assembly and connects to the inclined hole of the feeding hopper inlet flange, with the inclined hole outlet directly facing the valve core of the metering valve. Furthermore, the nitrogen buffer has a size of DN50~DN100, with inlet and outlet dimensions of DN15, used to stabilize nitrogen pressure and ensure stable airflow during backflush and pressure replenishment processes.

[0017] Furthermore, the injection module has a 1 / 2" flange at the inlet and a 1 / 4" diameter at the outlet, with a 33.5mm short-circuit length and a 5° angle with the horizontal plane. This is to ensure that the catalyst can be injected into the reactor at a sufficient velocity. The inner wall is polished to prevent the catalyst from adhering to the pipe wall. The three-way valve bypass port is connected to the ethylene purge gas pipeline.

[0018] Furthermore, the device also includes a control instrument module, which is used to monitor and regulate the operation of the device; the control instrument module includes a pressure transmitter, a pressure indicator, a flow meter, and a differential pressure transmitter.

[0019] The pressure transmitter is installed on the pressure replenishment and backflush pipeline and is used in conjunction with the pressure indicating instrument; the upper pressure port of the differential pressure transmitter is connected to the first or second nitrogen inlet, and the lower pressure port is connected to the horizontal section of the main pipeline. Valves are installed at both the upper and lower pressure ports; the flow meter is installed on the auxiliary pressure replenishment pipeline to monitor the flow rate of the purging nitrogen and can track the flow rate to determine whether the catalyst injection pipeline is unobstructed.

[0020] Furthermore, the inner walls of the filling tank and the feeding hopper are polished and made of 304 stainless steel; all valves are high-pressure ball valves, and the pipelines are seamless steel pipes.

[0021] Preferably, all valves are PN5.0, 316L high-pressure ball valves, the pipeline is Φ18×3mm seamless steel pipe, the joints are sealed with metal spiral wound gaskets, and the pressure resistance is ≥3.8MPa(G).

[0022] The second technical solution of this utility model provides a method for using the above-mentioned device, including the following steps: (1) Material filling: The dry powder catalyst enters the metering cup of the metering valve from the filling tank and is quantitatively filled by gravity and the guide tube; the metering valve rotates 180° to pour the material into the feeding hopper, and then resets to wait for the next pouring; Before filling, select a metering cup with the appropriate capacity (10-120mL) according to the amount of catalyst used and install it at the feed port of the catalyst metering valve; use a polytetrafluoroethylene cup for corrosive catalysts and a metal cup for high-temperature conditions. (2) Nitrogen pretreatment: Open the backflush valve group, and high-pressure nitrogen is used to purge the inner wall of the metering cup through the first nitrogen inlet or the second nitrogen inlet; after the metering valve discharges the material, open the nitrogen pressure replenishment valve to pressurize the feeding hopper to the set pressure, and then close the pressure replenishment valve. At the same time, the high-pressure nitrogen pressurizes the pipeline to spray the catalyst; during the catalyst transportation, the pipeline is designed to keep the purging nitrogen in the open state to ensure that there is always nitrogen purging injection module in the pipeline; The set pressure is as follows: the high-pressure nitrogen pressure must be 0.7 MPa greater than the reactor pressure; to ensure that the catalyst is completely blown into the catalyst outlet and to avoid pipeline blockage; (3) Injection: Open the catalyst injection valve, mix the material with nitrogen and inject it into the reactor at high speed through the injection module. After injection for 5-15 seconds, close the injection valve. The mass percentage of the catalyst to nitrogen is 0.30%~0.40%.

[0023] (4) Purge standby: When injection stops, open the three-way valve of the injection module to introduce ethylene purging gas to purge the module; when the device is in standby mode, the metering valve waits for the next material discharge and the process is executed in cycles.

[0024] During the above process, pressure transmitters and differential pressure transmitters are used to monitor the system pressure and the pressure difference between the feeding hopper and the pipeline in real time. The feeding amount of the metering valve is determined by the pressure difference data to ensure feeding accuracy.

[0025] Compared with the prior art, the present invention has at least the following improvements and beneficial effects: This invention overcomes the shortcomings of existing feeder technology, enabling the long-term, stable, and continuous addition of dry powder polyethylene catalyst to the gas-phase fluidized bed. It effectively solves the long-term pipe blockage problem of the dry powder catalyst feeder in polyethylene plants, ensuring the stable operation of the reactor.

[0026] (1) By combining the design of the conical feeding hopper and the nitrogen backflushing system, the dual effects of gravity feeding and high-pressure nitrogen purging are utilized to effectively solve the problem of dry powder catalyst adhesion and accumulation in the metering cup and pipeline, and achieve long-term continuous operation.

[0027] (2) An innovative feeding valve group pressure control mechanism (high-pressure nitrogen pressure is 0.7MPa greater than the reactor pressure) ensures that the catalyst is completely delivered to the reactor. An independent auxiliary pressure replenishment pipeline is designed to continuously purge the catalyst feed pipeline and injection module (5) with nitrogen purging gas to avoid the poor feeding caused by pipeline residue and ensure the stability of the polymerization reaction in the reactor.

[0028] (3) The multi-size measuring cup (10-120mL) and dual material (PTFE / metal) design not only meet the needs of the whole scenario from laboratory pilot to industrial production, but also adapt to different catalyst systems through the corrosion resistance and high temperature resistance of the material, reducing downtime maintenance due to equipment compatibility.

[0029] (4) The inner diameter of the injection pipe is increased and the length is shortened to reduce the risk of pipe blockage.

[0030] (5) The differential pressure transmitter monitors the feed rate and pipeline status in real time. Combined with the reduced diameter acceleration design of the injection module, the catalyst injection speed reaches 15-20m / s, and the dispersion uniformity in the reactor is improved by 30%, thus achieving stable operation of the device and optimization of product quality. Attached Figure Description

[0031] Figure 1 This is a simplified flow chart of a dry powder catalyst feeding device provided by this utility model; Figure 2 This is a schematic diagram of the feeding hopper; Figure 3 This is a schematic diagram of the injection module structure; Figure label: 1 filling tank, 11 flow guide pipes; 2. Feed hopper; 21. Catalyst inlet; 22. First nitrogen inlet; 23. Second nitrogen inlet; 24. Catalyst outlet; 3. Catalyst metering valve; 4. Feed valve assembly; 41. Nitrogen pressure replenishment valve; 42. Injection valve; 43. Shut-off valve; 44. Needle valve; 5. Injection module; 501 sleeve, 502 injection tube connection flange, 503 injection end flange, 504 three-way ball valve, 505 packing pipe flange, 506 guide connection flange. 61 Pressure transmitter, 62 Pressure indicating instrument, 63 Differential pressure transmitter; 61-63 belong to the 6 control instrument module; 7. Nitrogen buffer. Detailed Implementation

[0032] To enable those skilled in the art to better understand the technical solution of this utility model, the present utility model will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand this utility model, but do not limit this utility model in any way. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of this utility model. These all fall within the protection scope of this utility model.

[0033] Unless otherwise specified, all raw materials used in this invention are not subject to any particular restriction on their source; they may be purchased from the market or prepared using conventional methods known to those skilled in the art.

[0034] In the description of this utility model, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0035] Example 1: A dry powder catalyst feeding device This embodiment provides a dry powder catalyst feeding device for injecting dry powder catalyst into a reactor, such as... Figures 1-3 As shown. This device includes: a filling module, a metering module, an injection module 5, a purging module, and a control instrument module 6.

[0036] The filling module includes a filling tank 1 and a feeding hopper 2. The metering module is responsible for accurately controlling the amount of dry powder fed, and includes a catalyst metering valve 3 and a feeding valve group 4. The injection module 5 is used to connect the feeding device to the reactor. The purging module is used to prevent powder from adhering to pipelines and components and to avoid blockage, and includes a nitrogen buffer 7, an auxiliary pressure replenishment pipeline, a pressure replenishment backflush pipeline, and an ethylene purging pipeline. The control instrument module is used to monitor and control the feeding process, and includes a pressure transmitter 61, a pressure indicator 62, and a differential pressure transmitter 63. The connection relationship is as follows: the metering module is set in the filling module, the outlet of the filling module is connected to the inlet of the injection module 5 through a main pipeline, and the outlet of the injection module 5 is connected to the inlet of the reactor. The purging module and the control instrument module 6 are set between the filling module, the metering module, and the injection module 5.

[0037] like Figure 3As shown, the injection module 5 delivers dry powder into the reactor at high speed. It consists of a sleeve 501 (inlet 1 / 2" and outlet 1 / 4" with a reduced diameter short section length of 33.5mm and an angle of 5° with the horizontal plane), an injection tube connecting flange 502, an injection end flange 503, a three-way ball valve 504, a packing pipe flange 505, and a guide connecting flange 506, with a polished inner wall. The injection module 5 is arranged in the following order along the flow direction: guide connecting flange 506 → packing pipe flange 505 → three-way ball valve 504 → injection end flange 503 → injection tube connecting flange 502 → sleeve 501. The guide flange 506 and the packing nozzle flange 505 are bolted together with a threaded connection. The packing nozzle flange 505 and the injection end flange 503 are also bolted together with a threaded connection. A three-way ball valve 504 is installed between the packing nozzle flange 505 and the injection end flange 503. The injection end flange 503 and the reactor nozzle flange are bolted together with a threaded connection. The injection pipe connection flange 502 is installed between the injection end flange 503 and the reactor nozzle flange. The injection pipe connection flange 502 and the sleeve 501 are bolted together with a threaded connection. The function of the injection pipe connection flange 502 is to fix the sleeve 501, ensuring that the sleeve is fixed and does not rotate. O-rings (such as O-ring rubber rings) and gaskets (such as graphite gaskets) are also provided between the various components for functions such as fixing, sealing, and buffering.

[0038] The filling tank 1 is a conical or pyramidal structure, wider at the top and narrower at the bottom, with a polished inner wall. A guide pipe 11 is inserted into the center of the top and extends to the bottom outlet. The upper port is the material inlet, and the lower port is the outlet. The filling tank 1 is made of 304 stainless steel, and the cone angle is preferably 60°. The guide pipe 11 assists in material feeding and balances the pressure inside the tank.

[0039] The feeding hopper 2 is a conical or pyramidal structure with a preferred cone angle of 45°. It is wider at the top and narrower at the bottom, with a polished inner wall. The upper end is the catalyst inlet 21, and the lower end is the catalyst outlet 24. The catalyst inlet 21 is a DN50 flange, and the catalyst outlet 24 is a DN15 flange. The catalyst inlet 21 flange has two φ5mm, downward-facing oblique holes at 45° for nitrogen backflushing. The left and right sides are respectively connected to the first nitrogen inlet 22 and the second nitrogen inlet 23 for pressure replenishment.

[0040] The catalyst metering valve 3 is installed below the filling tank 1 and above the catalyst inlet 21. The catalyst metering valve 3 is compatible with a 10-120mL metering cup, which is made of polytetrafluoroethylene or metal. The material is poured out and reset through rotation. The catalyst metering valve 3 is driven to rotate by a servo motor, with a pouring angle of 180° to ensure complete material discharge.

[0041] The feeding valve assembly 4 includes a nitrogen pressure replenishment valve 41, a catalyst injection valve 42, a shut-off valve 43, a needle valve 44, and a start / stop valve 45, used to control the start and stop of nitrogen backflushing pressure replenishment and material injection. Both the nitrogen pressure replenishment valve 41 and the catalyst injection valve 42 are equipped with drive devices, commonly pneumatic, electric, or hydraulic actuators, used to automatically control the valve opening degree (e.g., receiving signals from the control system and adjusting the valve opening / closing degree). The shut-off valve 43, catalyst injection valve 42, and start / stop valve 45 are located on the main pipeline. A shut-off valve 43 with a pressure measuring point is installed at the front end of the catalyst injection valve 42 to monitor the upstream pressure, determine the upstream pressure status (e.g., material pressure), and cut off the fluid (nitrogen, catalyst, etc.) when closed, isolating the upstream pipeline. At the rear end of the catalyst injection valve 42, near the inlet of the injection module 5, a start / stop valve 45 is installed. This valve isolates the filling module and the reactor; it is normally open during normal operation of the device. An auxiliary pressure-replenishing pipeline is connected to the main pipeline at the rear end of the catalyst injection valve 42 and the front end of the start-stop valve 45. A needle valve 44 is installed at the connection point, and its opening degree can be adjusted more precisely.

[0042] The nitrogen buffer 7 is DN100 in size, with both inlet and outlet being DN15. It stabilizes nitrogen pressure and provides a stable gas source for pressure replenishment and backflushing. It connects to the pressure replenishment and backflushing pipeline and the auxiliary pressure replenishment pipeline. The pressure replenishment and backflushing pipeline is connected to the first nitrogen inlet 22 and the second nitrogen inlet 23 of the feeding hopper 2, and is connected to the valve core of the high-pressure nitrogen purging metering valve. The auxiliary pressure replenishment pipeline is connected to the main pipeline through a needle valve 44 to replenish pressure. The ethylene purging pipeline is connected to the three-way ball valve 504 of the injection module 5 and is used to purge residual material in the injection module 5 when the machine is stopped. A flow meter is installed on the auxiliary pressure replenishment pipeline to monitor the nitrogen delivery flow rate.

[0043] The pressure transmitter 61 is used to monitor the system pressure and is installed on the connecting pipeline between the nitrogen pressure replenishing valve 41 and the feeding hopper 2. The pressure transmitter 61 works in conjunction with the pressure indicating instrument 62 to achieve real-time monitoring of the device pressure, ensuring that the pressure remains stable within the set range during the feeding process (e.g., pressurized to 3.0 MPa, 0.7 MPa higher than the reactor pressure, etc.), thus ensuring the stable delivery of the dry powder catalyst. The upper pressure port of the differential pressure transmitter 63 is connected to the first nitrogen inlet 22 or the second nitrogen inlet 23, and the lower pressure port is connected to the horizontal section of the main pipeline. The feed amount of the metering valve is determined by the pressure difference. Valves are provided on both the upper and lower pressure ports of the differential pressure transmitter 63.

[0044] Example 2: Method of using the device This embodiment provides a method for using the device described in Embodiment 1, in the following sequence: metering valve 3 discharges material → metering valve 3 resets → nitrogen pressure valve 41 pressurizes → nitrogen pressure valve 41 closes → catalyst injection valve 42 injects → catalyst injection valve 42 closes → metering valve 3 discharges material (returning to the first step and repeating the cycle). Specifically, as follows: (1) Material filling: The dry powder catalyst enters the metering cup of the metering valve 3 from the filling tank 1, and is quantitatively filled by gravity and the guide tube; the metering valve 3 is rotated 180° to pour the material into the feeding hopper 2, which has a volume of 360 cm³. 3 , with a measuring cup 120 cm 3 The 1:3 design ensures smooth material conveying. Metering valve 3 resets, awaiting the next discharge. Dry powder catalyst is fed into the main pipeline through metering valve 3. The main pipeline adopts a DN15*PN5.0 design to ensure that the catalyst does not clog after entering the main pipeline. The feeding hopper 2 adopts a unique design, firstly ensuring that the catalyst can smoothly enter the main pipeline, and secondly, allowing for periodic purging of the metering cup of metering valve 3 to prevent residual catalyst from adhering inside the metering cup.

[0045] (2) Nitrogen pretreatment: Open the backflush valve group (nitrogen pressure replenishment valve 41 and valves on the pipeline connected to the first nitrogen inlet 22 or the second nitrogen inlet 23), and blow high-pressure nitrogen through the φ5mm inclined hole (45° downward) of the inlet flange of the feeding hopper 2 to purge the inner wall of the metering cup to prevent catalyst adhesion; pressurize the main pipeline with high-pressure nitrogen, and then inject the catalyst into the reactor; pour the material with the metering valve 3, open the nitrogen pressure replenishment valve 41 to pressurize the feeding hopper 2, and close the nitrogen pressure replenishment valve 41 after pressing to the set pressure.

[0046] (3) Injection: Open the catalyst injection valve 42. After the catalyst material is mixed with nitrogen, it is injected into the reactor at high speed through the injection module 5. After 5-15 seconds of injection, close the catalyst injection valve 42.

[0047] (4) Purge standby: When injection stops, open the three-way ball valve 504 to introduce ethylene purging gas to purge the module and avoid catalyst residue blockage; during the standby period of the unit, the metering valve 3 waits for the next discharge command and cyclically executes the feeding process.

[0048] In this embodiment, the sum of the volumes of the catalyst feeding hopper 2 and the catalyst delivery pipeline is: 360 + 3.14 * 0.007852 * 3 = 940 cm³ 3 The catalyst injection pressure is 30 kg / cm². 2 The pressure in the reactor is 23 kg / cm². 2Pipe friction (S): [S = (10.3n^2) / (d^5.33)], where n is the roughness of the pipe wall and d is the pipe diameter in meters. Calculate the flow rate (Q): [Q = [H / (SL)]^(0.5)], where H is the head difference between the two ends of the pipe in meters; L is the pipe length in meters. Therefore, the flow velocity V = 4Q / (3.14D) 2 The inlet pipe diameter of catalyst injection module 5 is 1 / 2”, the outlet pipe diameter is 1 / 4”, the length of the shorted section is 33.5mm, and the angle with the horizontal plane is 5°, the purpose of which is to improve the injection rate of catalyst and nitrogen.

[0049] Example 3 In this embodiment, the device used in the injection system has a sleeve inlet size of 3 / 16.

[0050] Compared with Example 3, Example 1 increased the size of the catalyst injection tube and shortened the size of the injection module 5, resulting in the following technical effects: the injection tube does not clog, ensuring stable catalyst feeding; the increased diameter of the injection tube disperses the catalyst, allowing it to enter the reactor in a dispersed state without local hot spots; and it reduces the maintenance frequency of the catalyst injection system, lowering the risk of catalyst leakage into the environment and reducing maintenance costs.

[0051] The above description of the embodiments is provided to enable those skilled in the art to understand and use the utility model. It will be apparent to those skilled in the art that various modifications can be easily made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present utility model is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present utility model without departing from its scope should be within the protection scope of the present utility model.

Claims

1. A dry powder catalyst feeding device for injecting dry powder catalyst into a reactor, characterized in that, It includes a filling module, a metering module and an injection module (5). The filling module is used to store and transport dry powder catalyst, the metering module is used to accurately meter the material, and the injection module (5) delivers the material into the reactor. The metering module is set in the filling module, and the outlet of the filling module is connected to the inlet of the injection module (5) through the main pipeline. The outlet of the injection module (5) is connected to the inlet of the reactor. The filling module includes a filling tank (1) and a feeding hopper (2); the metering module includes a catalyst metering valve (3) and a feeding valve group (4); the injection module (5) feeds dry powder catalyst powder into the reactor at high speed, and the outlet of the injection module (5) is sealed to the reactor inlet. The filling tank (1) is located above the feeding hopper (2), and the catalyst metering valve (3) is located on the pipeline between the filling tank (1) and the feeding hopper (2). The feeding hopper (2) is connected to the injection module (5) through the main pipeline.

2. The apparatus according to claim 1, characterized in that, The filling tank (1) has a conical structure, wider at the top and narrower at the bottom, with a guide pipe (11) at the top center and the lower port connected to the upper port of the feeding hopper (2) via a pipeline.

3. The apparatus according to claim 2, characterized in that, The feeding hopper (2) has a conical structure, with the upper port being the catalyst inlet (21) and the lower port being the catalyst outlet (24). The catalyst inlet (21) has two downward-sloping oblique holes; the oblique holes are connected to the first nitrogen inlet (22) and the second nitrogen inlet (23).

4. The apparatus according to claim 3, characterized in that, The feed port on the catalyst metering valve (3) is adapted to the metering cup, and the catalyst metering valve (3) is driven to rotate by a servo motor to realize the pouring of materials.

5. The apparatus according to claim 4, characterized in that, The feeding valve assembly (4) includes a nitrogen pressure replenishment valve (41), a catalyst injection valve (42), a shut-off valve (43), a needle valve (44), and a start-stop valve (45); used to control the start and stop of nitrogen backflushing, pressure replenishment, and injection; the nitrogen pressure replenishment valve (41) is used to control nitrogen backflushing and pressure replenishment, the needle valve (44) assists in pressure replenishment control, and the catalyst injection valve (42), shut-off valve (43), and start-stop valve (45) are used to control the start and stop of injection.

6. The apparatus according to claim 5, characterized in that, The shut-off valve (43), catalyst injection valve (42) and start / stop valve (45) are installed on the main pipeline, and the nitrogen pressure replenishment valve (41) and needle valve (44) are installed on the pipeline of the purging module.

7. The apparatus according to claim 5, characterized in that, The injection module (5) consists of a sleeve (501), an injection tube connecting flange (502), an injection end flange (503), a three-way ball valve (504), a packing pipe flange (505), and a guide connecting flange (506). The injection module (5) is arranged in the following order along the material flow direction: guide connecting flange (506), packing pipe flange (505), three-way ball valve (504), injection end flange (503), injection tube connecting flange (502), and sleeve (501). Each component is connected by a threaded connection. The guide connecting flange (506) is connected to the start / stop valve (45), and the sleeve (501) is connected to the reactor.

8. The apparatus according to claim 7, characterized in that, The device also includes a purging module for providing high-pressure nitrogen to the device; the purging module includes a nitrogen buffer (7), an auxiliary pressure replenishment pipeline, a pressure replenishment backflush pipeline and an ethylene purging pipeline; The pressure replenishing backflush pipeline is connected to the first nitrogen inlet (22) and the second nitrogen inlet (23) of the feeding hopper (2); a nitrogen pressure replenishing valve (41) is provided on the pressure replenishing backflush pipeline; The auxiliary pressure replenishment pipeline is connected to the main pipeline through a needle valve (44), and the connection position is at the rear end of the catalyst injection valve (42) and the front end of the start / stop valve (45); The ethylene purging pipeline is connected to the third outlet of the three-way ball valve (504) of the injection module (5).

9. The apparatus according to claim 8, characterized in that, The device also includes a control instrument module (6), which is used to monitor and regulate the operation of the device. The control instrument module (6) includes a pressure transmitter (61), a pressure indicator (62), a differential pressure transmitter (63), and a flow meter. The pressure transmitter (61) is installed on the pressure replenishment and backflush pipeline, and the pressure transmitter (61) is used in conjunction with the pressure indicator (62). The upper pressure port of the differential pressure transmitter (63) is connected to the first nitrogen inlet (22) or the second nitrogen inlet (23), and the lower pressure port is connected to the horizontal section of the main pipeline. Valves are installed at both the upper and lower pressure ports. The flow meter is installed on the auxiliary pressure replenishment pipeline to monitor the flow rate of the purging nitrogen. It can follow the flow rate to determine whether the catalyst injection pipeline is unobstructed.

10. The apparatus according to claim 9, characterized in that, The inner walls of the filling tank (1), the feeding hopper (2) and the injection module (5) are all polished and made of stainless steel.

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