Raw material deoxidizing device for polyethylene production process

Abstract

The utility model relates to the technical field of polyethylene production process raw material refining, and discloses a polyethylene production process raw material deoxidizing device which comprises an ethylene heater, a heating section, an ethylene deaerator and a cooling section which are connected in sequence, the ethylene heater is a U-shaped pipe heater, the heating section is a steam jacketed pipe, the ethylene deaerator is a vertical fixed bed reactor, and the cooling section is a cooling water jacketed pipe. A first steam pipe is arranged on the side face of the U-shaped pipe heater, a first pressure transmitter and a first steam adjusting valve are arranged on the first steam pipe, a first condensate pipe is arranged at the bottom of the U-shaped pipe heater, and a condensate adjusting valve is arranged on the first condensate pipe; a first conveying pipeline is arranged on the U-shaped pipe heater, and a first temperature transmitter is arranged on the first conveying pipeline. The device can effectively control and eliminate the electrostatic problem caused by high oxygen content of raw materials, and ensures the long-period stable operation of a polyethylene device.

Description

Technical Field

[0001] This utility model relates to the field of raw material refining technology in polyethylene production, specifically to a deoxygenation device for raw materials in polyethylene production. Background Technology

[0002] Polyolefin materials are wear-resistant, possess excellent insulation properties, high transparency and air permeability, and good chemical corrosion resistance, resisting corrosion from acids, alkalis, salts, and other chemicals. They have good processing performance and can be processed into complex products such as tubes, sheets, films, and fibers through extrusion, blowing, and injection molding. Mass production is possible, with high efficiency, low cost, and significant economic benefits. They are also inexpensive, energy-saving, environmentally friendly, and recyclable.

[0003] The gas-phase fluidized bed polyethylene production process uses ethylene as raw material, butene-1 or hexene-1 as comonomers, hydrogen as a chain transfer agent, and isopentane as an inducing condenser to produce full-density polyethylene. The gas-phase fluidized bed polyethylene process is characterized by its simple flow, flexible production, economy, and safety. This process offers high production flexibility; a single process flow can produce a full range of products with high, medium, and low densities, providing significant operational flexibility and ensuring uniform product performance. The process is simple, operates under mild conditions, eliminates solvent recovery, and the fluidized bed reaction is self-limiting, thus minimizing potential safety hazards. Furthermore, it generates relatively small amounts of waste gas, wastewater, and solid waste, which are easily treated and meet various environmental regulations.

[0004] Gas-phase fluidized bed production technology has significant development potential and market prospects, low investment and operating costs, and is environmentally friendly; therefore, many plants in China adopt this technology. However, reactor agglomeration caused by static electricity frequently occurs during operation, forcing plant shutdowns. When static electricity is generated, adding trace amounts of water or alcohol to the reactor can neutralize the positive or negative static charge. However, when the net charge is excessive, adding water or alcohol cannot effectively control reactor agglomeration. The impurity content of the raw materials, especially the oxygen content, is the main cause of static electricity; therefore, eliminating the oxygen content in the raw materials is crucial. Currently, the deoxygenator system used in the raw material refining ethylene production plant cannot meet the reaction conditions of a highly efficient deoxygenation catalyst, resulting in poor deoxygenation performance. Utility Model Content

[0005] In view of the above-mentioned shortcomings in the prior art, the present invention provides a deoxygenation device for raw materials in polyethylene production process, which solves the problem of excessive impurity content in raw materials, especially high oxygen content, causing static electricity and thus reactor agglomeration.

[0006] To achieve the above-mentioned utility model objectives, the technical solution adopted by this utility model is as follows: a deoxygenation device for raw materials in polyethylene production process, comprising an ethylene heater, a heating section, an ethylene deoxygenator, a cooling section, and an ethylene CO removal device connected in sequence; the ethylene heater is a U-shaped tube heater, the heating section is a steam jacketed pipe, the ethylene deoxygenator is a vertical fixed bed reactor, and the cooling section is a cooling water jacketed pipe.

[0007] The beneficial effects of this invention are as follows: This device addresses the static electricity generated in the reactor during the operation of a polyethylene plant by reducing the oxygen content of the raw material impurities, thus effectively solving the static electricity problem caused by high impurity content. Ethylene from the ethylene heat exchanger is heated in a U-tube heater, then further heated in a steam jacket, and finally fed into a vertical fixed-bed reactor. In the reactor, oxygen is removed from the ethylene. The deoxygenated ethylene then enters a cooling water jacket for cooling, and after cooling, it enters an ethylene deCO generator for further impurity removal and drying before participating in the polymerization reaction. This device effectively controls and eliminates static electricity problems caused by high oxygen content in the raw material, ensuring long-term stable operation of the polyethylene plant.

[0008] Furthermore, in the above-mentioned deoxygenation device for raw materials in polyethylene production process, a first steam pipe is provided on the side of the U-shaped tube heater, a first pressure transmitter and a first steam regulating valve are provided on the first steam pipe, a first condensate pipe is provided at the bottom of the U-shaped tube heater, and a condensate regulating valve is provided on the first condensate pipe; a first conveying pipeline is provided on the U-shaped tube heater, and a first temperature transmitter is provided on the first conveying pipeline.

[0009] The beneficial effects of adopting the above-mentioned further scheme are as follows: Steam from the public works is introduced into the first steam pipe, and the raw material ethylene for the ethylene heat exchanger is introduced into the U-tube heater. After heating, it is sent to the steam jacket pipe for further heating via the first delivery pipeline. The first steam pipe is equipped with a first pressure transmitter and a first steam regulating valve, allowing the operator to monitor and precisely adjust the pressure of the heating steam in real time. The pressure transmitter converts the pressure in the steam pipeline into an electrical signal, which is transmitted to the control system. The control system automatically adjusts the opening of the steam regulating valve according to the preset parameter range, thereby achieving precise control of the heating temperature. The first condensate pipe and condensate regulating valve effectively collect and discharge the steam condensate generated during the heating process, which is discharged via a floor drain. Timely discharge of condensate helps maintain the thermal efficiency of the heater, reduces energy loss, and improves the overall system energy efficiency. The first temperature transmitter installed on the first delivery pipeline is used to monitor the outlet temperature of the ethylene after passing through the U-tube heater in real time. Based on the information fed back by the temperature transmitter, the control system can automatically adjust the steam supply or take other measures to ensure that the temperature of the ethylene before entering the heating section is within the optimal range.

[0010] Furthermore, in the above-mentioned polyethylene production process raw material deoxygenation device, the steam jacket pipe and the U-tube heater are connected through a first conveying pipeline. A second steam pipe is installed on the steam jacket pipe, and a second steam regulating valve and a second pressure transmitter are installed on the second steam pipe. A second condensate pipe is installed at the bottom of the steam jacket pipe. The steam jacket pipe is connected to the vertical fixed bed reactor through a feed pipe, and a feed regulating valve and a feed gate valve are installed sequentially on the feed pipe.

[0011] The beneficial effects of adopting the above-mentioned further scheme are as follows: Since the reaction temperature of different deoxygenation catalysts and oxygen is different, the steam jacket pipe of the heating section is used to assist in heating the raw material ethylene to the predetermined temperature value. The heated ethylene then enters the vertical fixed bed reactor for deoxygenation.

[0012] Furthermore, in the above-mentioned polyethylene production process raw material deoxygenation device, a third pressure transmitter is installed at the end of the feed pipe near the vertical fixed bed reactor; a second temperature transmitter is installed on the side wall of the vertical fixed bed reactor; a second conveying pipeline is installed at the bottom of the vertical fixed bed reactor; the vertical fixed bed reactor is connected to the cooling water jacket pipe through the second conveying pipeline; and a discharge gate valve, a discharge regulating valve, and an online oxygen content analyzer are sequentially installed on the second conveying pipeline.

[0013] The beneficial effects of adopting the above-mentioned further scheme are as follows: after the ethylene is heated, it enters the ethylene deoxygenator, where the oxygen in the ethylene reacts with the deoxygenation catalyst (Mn-based deoxygenator, Cu-based deoxygenator and Ni-based deoxygenator) to absorb the oxygen in the raw material. Since the subsequent reactor requires low-temperature operation, the deoxygenated ethylene raw material needs to be cooled through a pipeline with a cooling jacket, and the medium used is boundary circulating cooling water.

[0014] Furthermore, in the above-mentioned polyethylene production process raw material deoxygenation device, an outlet is provided on the cooling water jacket pipe, and the outlet is connected to the ethylene deCO tower.

[0015] The beneficial effects of adopting the above-mentioned further scheme are as follows: the ethylene deCO tower utilizes specific adsorbents or chemical reaction principles to effectively remove impurities such as CO from the product, thereby improving the purity of polyethylene products.

[0016] Furthermore, in the above-mentioned polyethylene production process raw material deoxygenation device, a steam jacket is installed on the first conveying pipeline.

[0017] Furthermore, in the above-mentioned polyethylene production process raw material deoxygenation device, a cooling water jacket is installed on the second conveying pipeline.

[0018] The beneficial effects of this invention are as follows: Ethylene feedstock from the ethylene heat exchanger enters the ethylene heater and is heated to a certain temperature. Because different deoxygenation catalysts react with oxygen at different temperatures, a heating stage is used to assist in heating the ethylene feedstock to the predetermined temperature. Staged heating is more efficient than one-step heating, hence the adoption of staged heating. The heated ethylene then enters the ethylene deaerator, where the oxygen in the ethylene reacts with the deoxygenation catalysts (Mn-based, Cu-based, and Ni-based deoxygenators), absorbing the oxygen from the feedstock. Since subsequent reactors require low-temperature operation, the deoxygenated ethylene feedstock is cooled through a pipeline with a cooling jacket before entering the ethylene CO2 removal unit. The oxygen-free ethylene feedstock participates in the polymerization reaction, preventing the generation of static electricity due to high oxygen content in the feedstock and avoiding unplanned plant shutdowns. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the deoxygenation device for raw materials in the polyethylene production process.

[0020] The components are as follows: 1. U-tube heater; 2. Steam jacket pipe; 3. Vertical fixed bed reactor; 4. Cooling water jacket pipe; 5. First steam pipe; 6. First pressure transmitter; 7. First steam regulating valve; 8. First condensate pipe; 9. Condensate regulating valve; 10. First conveying pipeline; 11. First temperature transmitter; 12. Second steam pipe; 13. Second pressure transmitter; 14. Second steam regulating valve; 15. Second condensate pipe; 16. Feed pipe; 17. Feed regulating valve; 18. Feed gate valve; 19. Third pressure transmitter; 20. Second temperature transmitter; 21. Second conveying pipeline; 22. Discharge gate valve; 23. Discharge regulating valve; 24. Online oxygen content analyzer; 25. Outlet. Detailed Implementation

[0021] The specific embodiments of this utility model are described below to enable those skilled in the art to understand this utility model. However, it should be understood that this utility model is not limited to the scope of the specific embodiments. For those skilled in the art, as long as various changes are within the spirit and scope of this utility model as defined and determined by the appended claims, these changes are obvious. All utility model creations utilizing the concept of this utility model are within the scope of protection.

[0022] like Figure 1 As shown, this embodiment provides a deoxygenation device for raw materials in polyethylene production, including an ethylene heater, a heating section, an ethylene deaerator, a cooling section, and an ethylene CO2 removal device connected in sequence; the ethylene heater is a U-tube heater 1, the heating section is a steam jacketed pipe 2, the ethylene deaerator is a vertical fixed bed reactor 3, and the cooling section is a cooling water jacketed pipe 4.

[0023] A first steam pipe 5 is provided on the side of the U-tube heater 1. A first pressure transmitter 6 and a first steam regulating valve 7 are provided on the first steam pipe 5. A first condensate pipe 8 is provided at the bottom of the U-tube heater 1. A condensate regulating valve 9 is provided on the first condensate pipe 8. A first conveying pipeline 10 is provided on the U-tube heater 1. A first temperature transmitter 11 and a steam jacket are provided on the first conveying pipeline 10.

[0024] The steam jacket pipe 2 is connected to the U-tube heater 1 through the first conveying pipeline 10. A second steam pipe 12 is installed on the steam jacket pipe 2. A second steam regulating valve 14 and a second pressure transmitter 13 are installed on the second steam pipe 12. A second condensate pipe 15 is installed at the bottom of the steam jacket pipe 2. The steam jacket pipe 2 is connected to the vertical fixed bed reactor 3 through the feed pipe 16. A feed regulating valve 17 and a feed gate valve 18 are installed on the feed pipe 16 in sequence.

[0025] A third pressure transmitter 19 is installed at one end of the feed pipe 16 near the vertical fixed-bed reactor 3; a second temperature transmitter 20 is installed on the side wall of the vertical fixed-bed reactor 3; a second conveying pipeline 21 is installed at the bottom of the vertical fixed-bed reactor 3; the vertical fixed-bed reactor 3 is connected to the cooling water jacket pipe 4 through the second conveying pipeline 21; a discharge gate valve 22, a discharge regulating valve 23, and an online oxygen content analyzer 24 are sequentially installed on the second conveying pipeline 21; a cooling water jacket is installed on the second conveying pipeline 21; an outlet 25 is installed on the cooling water jacket pipe 4, and the outlet 25 is connected to the ethylene deCO tower.

[0026] This raw material deoxygenation device is used to effectively remove impurities from the ethylene raw material, ensuring stable operation of the polyethylene plant. In this mode, the ethylene raw material enters the ethylene heater and is heated to a certain temperature. Based on the reaction temperature, a heating section is used to further heat the ethylene raw material to a predetermined temperature. After heating, the ethylene enters the ethylene deoxygenator, where oxygen reacts with the deoxygenation catalyst to remove oxygen from the raw material. The deoxygenated ethylene is then cooled via a pipeline with a cooling jacket before entering the ethylene CO2 removal unit. The deoxygenation process is controlled by an online oxygen content analyzer 24 to ensure effective deoxygenation.

[0027] The specific operating procedure for this device is as follows:

[0028] Commissioning of the raw material deoxygenation unit: All instruments and equipment of the raw material deoxygenation unit are operating. Common media such as steam and cooling water are in operation. All equipment and pipelines have been purged with nitrogen and replaced with ethylene gas to maintain pressure. The ethylene deoxygenator has been loaded with deoxygenation catalyst. Open the feed gate valve 18 to connect the ethylene heater and the ethylene deoxygenator. Open the discharge gate valve 22 to connect the ethylene deoxygenator and the ethylene CO2 removal unit. Adjust other parameters to normal values.

[0029] Ethylene Heating Control: The raw ethylene flows from the ethylene heat exchanger to the ethylene heater at a pressure of approximately 3.1 MPaG. Steam is drawn into the shell side of the ethylene heater, and the steam pressure entering the heater is set by a temperature controller. The steam flow to the ethylene heater is controlled by the display value of the first pressure transmitter 6 and the opening degree of the first steam regulating valve 7 to ensure stable temperature and pressure in the ethylene heater. The steam jacket is activated by the value of the first temperature transmitter 11. The temperature of the ethylene heated by the ethylene heater does not exceed 130°C. Based on the type of deoxygenation catalyst and the oxygen content of the raw material, the steam flow to the jacket is controlled by the display value of the second pressure transmitter 13 and the second steam regulating valve 14, allowing for staged heating of the raw material temperature to not exceed 160°C. The temperature is displayed by the second temperature transmitter 20. In case of a fault, the feed is switched to the discharge unit.

[0030] Ethylene Deoxygenation Control: The ethylene deaerator uses a deoxidizing agent to react with oxygen to remove oxygen from the raw material propylene. The heated ethylene feedstock is controlled by the display value of the third pressure transmitter 19 and the feed regulating valve 17. The opening of the feed gate valve 18 is adjusted to control the ethylene feed. The pressure of the ethylene deaerator is controlled at approximately 3.1 MPaG, and the material residence time is controlled by the reaction load. After oxygen removal, the feedstock is discharged through the discharge gate valve 22 and cooled before being sent to the ethylene CO2 remover. Because the CO2 remover requires low-temperature operation, cooling is necessary; the feedstock is cooled to approximately 90°C by jacket cooling water. The ethylene deoxygenation effect is verified by the oxygen concentration indicator, and the temperature of the ethylene deaerator is adjusted based on the indicated value.

[0031] All components in this utility model are commercially available products. For example, the first pressure transmitter 6, the second pressure transmitter 13, and the third pressure transmitter 19 are model YTF-100H; the first steam regulating valve 7 and the second steam regulating valve 14 are model PS50-36H; the first temperature transmitter 11 and the second temperature transmitter 20 are model pt100; the condensate regulating valve 9 is an LDZJHP pneumatic diaphragm single-seat regulating valve; the feed regulating valve 17 and the discharge regulating valve 23 are LDZJHM pneumatic diaphragm sleeve regulating valves; the feed gate valve 18 and the discharge gate valve 22 are model Z41W-16P; the oxygen content concentration analyzer is model ZY500-D; the ethylene heater is a double-tube sheet-BEU type U-tube heat exchanger; and the ethylene deaerator is a vertical fixed bed reactor 3.

Claims

1. A deoxygenation device for raw materials in a polyethylene production process, characterized in that, It includes an ethylene heater, a heating section, an ethylene deaerator, a cooling section, and an ethylene CO2 removal unit connected in sequence; the ethylene heater is a U-tube heater (1), the heating section is a steam jacketed pipe (2), the ethylene deaerator is a vertical fixed bed reactor (3), and the cooling section is a cooling water jacketed pipe (4).

2. The deoxygenation device for raw materials in polyethylene production process according to claim 1, characterized in that, The U-tube heater (1) has a first steam pipe (5) on its side, a first pressure transmitter (6) and a first steam regulating valve (7) on the first steam pipe (5), a first condensate pipe (8) on its bottom, and a condensate regulating valve (9) on the first condensate pipe (8); a first conveying pipeline (10) is provided on the U-tube heater (1), and a first temperature transmitter (11) is provided on the first conveying pipeline (10).

3. The deoxygenation device for raw materials in polyethylene production process according to claim 2, characterized in that, The steam jacket pipe (2) is connected to the U-tube heater (1) through the first conveying pipeline (10). A second steam pipe (12) is provided on the steam jacket pipe (2). A second steam regulating valve (14) and a second pressure transmitter (13) are provided on the second steam pipe (12). A second condensate pipe (15) is provided at the bottom of the steam jacket pipe (2). The steam jacket pipe (2) is connected to the vertical fixed bed reactor (3) through the feed pipe (16). A feed regulating valve (17) and a feed gate valve (18) are provided on the feed pipe (16) in sequence.

4. The deoxygenation device for raw materials in polyethylene production process according to claim 3, characterized in that, A third pressure transmitter (19) is installed at one end of the feed pipe (16) near the vertical fixed bed reactor (3); a second temperature transmitter (20) is installed on the side wall of the vertical fixed bed reactor (3); a second conveying pipeline (21) is installed at the bottom of the vertical fixed bed reactor (3); the vertical fixed bed reactor (3) is connected to the cooling water jacket pipe (4) through the second conveying pipeline (21); a discharge gate valve (22), a discharge regulating valve (23), and an online oxygen content analyzer (24) are installed sequentially on the second conveying pipeline (21).

5. The deoxygenation device for raw materials in polyethylene production process according to claim 1, characterized in that, The cooling water jacket pipe (4) is provided with an outlet (25), which is connected to the ethylene deCO tower.

6. The deoxygenation device for raw materials in polyethylene production process according to claim 2, characterized in that, A steam jacket is provided on the first delivery pipeline (10).

7. The deoxygenation device for raw materials in polyethylene production process according to claim 4, characterized in that, A cooling water jacket is provided on the second delivery pipeline (21).

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