An energy-saving inlet temperature control system for the C2 hydrogenation reactor in an ethylene plant.
By coordinating the temperature control loop and the selective controller, the inlet temperature control of the C2 hydrogenation reactor was optimized using the waste heat from the cracked gas, thus solving the problem of energy loss in the ethylene plant and reducing energy consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- CNOOC & SHELL PETROCHEMICAL CO LTD
- Filing Date
- 2025-09-28
- Publication Date
- 2026-07-03
AI Technical Summary
In existing ethylene plants, there is energy loss in controlling the inlet temperature of the C2 hydrogenation reactor, especially after the arsenic removal protective bed reactor is shut down, leading to increased energy consumption.
A temperature control system including a first, second, and third temperature control loop and a selector controller was designed. By coordinating and adjusting the loops, the waste heat of the cracked gas is utilized to reduce heat exchange in the cooler, optimize the inlet temperature control of the C2 hydrogenation reactor, and reduce the consumption of low-pressure steam.
Under full load operation, the consumption of low-pressure steam was reduced, saving energy consumption per unit of ethylene product and minimizing energy consumption for inlet temperature regulation of the C2 hydrogenation reactor.
Smart Images
Figure CN224457277U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of temperature control technology for ethylene plants, specifically an energy-saving inlet temperature control system for the C2 hydrogenation reactor in an ethylene plant. Background Technology
[0002] The inlet of the C2 hydrogenation reactor in a certain ethylene plant is designed with an arsenic removal protective bed reactor. The 80°C pyrolysis gas from the pyrolysis gas compressor outlet needs to be cooled to 40°C by a circulating water heat exchanger before entering the arsenic removal protective bed reactor for adsorption reaction. For the C2 hydrogenation reactor downstream of the arsenic removal protective bed reactor, since the reaction initiation temperature needs to reach at least 65°C, the cooled pyrolysis gas needs to be reheated to the preset temperature using steam, resulting in a certain energy loss. This situation becomes more prominent after the arsenic removal protective bed reactor is shut down. Utility Model Content
[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide an energy-saving inlet temperature control system for the C2 hydrogenation reactor of an ethylene plant that can reduce energy consumption.
[0004] This utility model is achieved through the following technical solution: an energy-saving inlet temperature control system for a C2 hydrogenation reactor in an ethylene plant, comprising an arsenic removal protective bed reactor, a C2 hydrogenation reactor, a cooler, a heater, a first temperature control loop, a second temperature control loop, and a third temperature control loop. The inlet of the cooler is connected to a cracked gas compressor via a process pipeline. The outlet of the cooler is connected to the inlet of the arsenic removal protective bed reactor via a first pipeline. The outlet of the arsenic removal protective bed reactor is connected to the inlet of the C2 hydrogenation reactor via a second pipeline. The outlet of the arsenic removal protective bed reactor is connected to the inlet of the heater via a third pipeline. The outlet of the heater is connected to the inlet of the C2 hydrogenation reactor via a fourth pipeline. The first temperature control loop is used to regulate the inlet temperature of the C2 hydrogenation reactor. The second temperature control loop is used to regulate the outlet temperature of the cooler. The third temperature control loop is used to increase the temperature of the cracked gas and regulate the inlet temperature of the C2 hydrogenation reactor when the arsenic removal protective bed reactor is in a shutdown state.
[0005] Furthermore: the first pipeline branches into a fifth pipeline, which is connected to the second pipeline and the third pipeline respectively. A first shut-off valve is installed on the fifth pipeline, and the outlet of the arsenic removal protective bed reactor is connected to the fifth pipeline through a second shut-off valve.
[0006] Further: The first temperature control circuit includes a first temperature control regulating valve, a second temperature control regulating valve, and a first temperature controller. The first temperature control regulating valve is disposed on the third pipeline, the second temperature control regulating valve is disposed on the second pipeline, and the first temperature controller is disposed on the fourth pipeline.
[0007] Further: The second temperature control circuit includes a third temperature control regulating valve, a fourth temperature control regulating valve, and a second temperature controller. The third temperature control regulating valve is disposed on the process pipeline, the fourth temperature control regulating valve is connected between the process pipeline and the first pipeline, and the second temperature controller is disposed on the first pipeline. The second temperature controller is signal-connected to the third temperature control regulating valve and the fourth temperature control regulating valve respectively.
[0008] Furthermore, the third temperature control loop includes a selection controller, which is signal-connected to the first temperature controller, the second temperature controller, the first temperature control valve, and the second temperature control valve.
[0009] Furthermore, a third shut-off valve is installed on the first pipeline, and the third shut-off valve is located behind the second temperature controller.
[0010] Furthermore, the heater is provided with a low-pressure steam inlet and a low-pressure condensate outlet.
[0011] Furthermore, the cooler is provided with a circulating cooling water inlet and a circulating cooling water outlet.
[0012] Compared with the prior art, the present invention has the following beneficial effects:
[0013] This invention, through the coordinated operation of the first, second, and third temperature control loops, allows the cracked gas to bypass the cooler and maximize the use of the residual heat from the compressor outlet, minimizing heat loss through circulating water, when the selector controller determines the reactor is in a shutdown state based on the valve status of the arsenic removal protective bed reactor. This reduces the low-pressure steam consumption by 6 tons / hour while meeting the inlet temperature regulation requirements of the C2 hydrogenation reactor. Under full-load operation, the saved steam is equivalent to reducing the unit ethylene energy consumption by 3 kg of standard oil per ton of ethylene product, thus minimizing the energy consumption for inlet temperature regulation of the C2 hydrogenation reactor. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the structure of this utility model.
[0015] Explanation of reference numerals in the attached diagram: 1-Arsenic removal protective bed reactor, 2-C2 hydrogenation reactor, 3-Cooler, 4-Heater, 5-First temperature control loop, 6-Second temperature control loop, 7-Third temperature control loop, 8-Process pipeline, 9-First pipeline, 10-Second pipeline, 11-Third pipeline, 12-Fourth pipeline, 13-Fifth pipeline, 14-First shut-off valve, 15-Second shut-off valve, 16-First temperature control regulating valve, 17-Second temperature control regulating valve, 18-First temperature controller, 19-Third temperature control regulating valve, 20-Fourth temperature control regulating valve, 21-Second temperature controller, 22-Selector controller, 23-Third shut-off valve, 24-Low-pressure steam inlet, 25-Low-pressure condensate outlet, 26-Circulating cooling water inlet, 27-Circulating cooling water outlet. Detailed Implementation
[0016] Figure 1 This utility model provides a schematic diagram of an embodiment of an energy-saving ethylene plant C2 hydrogenation reactor inlet temperature control system, including an arsenic removal protective bed reactor 1, a C2 hydrogenation reactor 2, a cooler 3, a heater 4, a first temperature control loop 5, a second temperature control loop 6, and a third temperature control loop 7. The inlet of the cooler 3 is connected to the cracked gas compressor via a process pipeline 8. The outlet of the cooler 3 is connected to the inlet of the arsenic removal protective bed reactor 1 via a first pipeline 9. The outlet of the arsenic removal protective bed reactor 1 is connected to the inlet of the C2 hydrogenation reactor 2 via a second pipeline 10. The outlet of the arsenic removal protective bed reactor 1 is connected to the inlet of the heater 4 via a third pipeline 11. The outlet of the heater 4 is connected to the inlet of the C2 hydrogenation reactor 2 via a fourth pipeline 12. The first temperature control loop 5 is used to regulate the inlet temperature of the C2 hydrogenation reactor 2. The second temperature control loop 6 is used to regulate the outlet temperature of the cooler 3. The third temperature control loop 7 is used to increase the temperature of the cracked gas and regulate the inlet temperature of the C2 hydrogenation reactor 2 when the arsenic removal protective bed reactor 1 is in a shutdown state.
[0017] The first pipeline 9 branches off into the fifth pipeline 13, which is connected to the second pipeline 10 and the third pipeline 11. The fifth pipeline 13 is equipped with a first shut-off valve 14, and the outlet of the arsenic removal protective bed reactor 1 is connected to the fifth pipeline 13 through a second shut-off valve 15.
[0018] The first temperature control circuit 5 includes a first temperature control regulating valve 16, a second temperature control regulating valve 17, and a first temperature controller 18. The first temperature control regulating valve 16 is installed on the third pipeline 11, the second temperature control regulating valve 17 is installed on the second pipeline 10, and the first temperature controller 18 is installed on the fourth pipeline 12.
[0019] The second temperature control circuit 6 includes a third temperature control valve 19, a fourth temperature control valve 20, and a second temperature controller 21. The third temperature control valve 19 is installed on the process pipeline 8, the fourth temperature control valve 20 is connected between the process pipeline 8 and the first pipeline 9, and the second temperature controller 21 is installed on the first pipeline 9. The second temperature controller 21 is connected to the third temperature control valve 19 and the fourth temperature control valve 20 by signal.
[0020] The third temperature control loop 7 includes a selection controller 22, which is connected to the first temperature controller 18, the second temperature controller 21, the first temperature control valve 16, and the second temperature control valve 17.
[0021] A third shut-off valve 23 is installed on the first pipeline 9, and the third shut-off valve 23 is located behind the second temperature controller 21.
[0022] The heater 4 is provided with a low-pressure steam inlet 24 and a low-pressure condensate outlet 25.
[0023] The cooler 3 is provided with a circulating cooling water inlet 26 and a circulating cooling water outlet 27.
[0024] The selector controller 22 has a judgment function. When the first shut-off valve 14 is closed and the second shut-off valve 15 and the third shut-off valve 23 are open, it is determined that the arsenic removal protective bed reactor 1 is in operation. The first temperature control loop 5 at the inlet of the C2 hydrogenation reactor 2 normally selects the heater 4 to participate in temperature control through the selector controller 22.
[0025] When the first shut-off valve 14 is open and the second shut-off valve 15 and the third shut-off valve 23 are closed, it is determined that the arsenic removal protective bed reactor 1 is in a shutdown state. At this time, the selector controller 22 will automatically select the second temperature control loop 6 to adjust the inlet temperature of the C2 hydrogenation reactor 2, and the heater 4 will be shut down.
[0026] Specifically, when the arsenic removal protective bed reactor 1 is in operation, the first shut-off valve 14 is closed, the second temperature control valve 17 and the fourth temperature control valve 20 are both partially closed, and at the same time, the first temperature control valve 16, the third temperature control valve 19, the second shut-off valve 15 and the third shut-off valve 23 are all open. The temperature of the fluid flowing out of the heater 4 outlet is detected by the first temperature controller 18, and a control command is sent to the first temperature control valve 16 according to the detected fluid temperature to control the opening degree of the first temperature control valve 16, thereby controlling the flow rate of the fluid entering the heater 4 and the flow rate of the fluid entering the C2 hydrogenation reactor 2, thereby regulating the inlet temperature of the C2 hydrogenation reactor 2.
[0027] When the arsenic removal protective bed reactor 1 is in a shutdown state, the third temperature control valve 19, the second shut-off valve 15, and the third shut-off valve 23 are in a closed state, while the first shut-off valve 14 is in a closed state. The selector controller 22 prioritizes controlling the temperature of the cracked gas through the second temperature controller 21 and controls the opening of the fourth temperature control valve 20. This allows the heated cracked gas to enter the heater 4 sequentially through the first pipeline 9, the fifth pipeline 13, and the third pipeline 11 for heating, and finally enter the C2 hydrogenation reactor 2 through the fourth pipeline 12. This eliminates the need for the cracked gas to pass through the cooler 3 for heat exchange, reducing temperature loss and thus increasing the temperature of the fluid entering the heater 4. This minimizes the energy consumption for regulating the inlet temperature of the C2 hydrogenation reactor 2.
[0028] The above detailed description is a specific description of a feasible embodiment of the present utility model. This embodiment is not intended to limit the patent scope of the present utility model. All equivalent implementations or modifications that do not depart from the present utility model should be included in the patent scope of this case.
Claims
1. An energy efficient ethylene plant carbon dioxide hydrogenation reactor inlet temperature control system characterized by: The reactor includes an arsenic removal protective bed reactor, a C2 hydrogenation reactor, a cooler, a heater, a first temperature control loop, a second temperature control loop, and a third temperature control loop. The inlet of the cooler is connected to the cracked gas compressor via a process pipeline. The outlet of the cooler is connected to the inlet of the arsenic removal protective bed reactor via the first pipeline. The outlet of the arsenic removal protective bed reactor is connected to the inlet of the C2 hydrogenation reactor via the second pipeline. The outlet of the arsenic removal protective bed reactor is connected to the inlet of the heater via the third pipeline. The outlet of the heater is connected to the inlet of the C2 hydrogenation reactor via a fourth pipeline. The first temperature control loop is used to regulate the inlet temperature of the C2 hydrogenation reactor. The second temperature control loop is used to regulate the outlet temperature of the cooler. The third temperature control loop is used to increase the temperature of the cracked gas and regulate the inlet temperature of the C2 hydrogenation reactor when the arsenic removal protective bed reactor is in a shutdown state.
2. An energy efficient ethylene plant carbon dioxide hydrogenator inlet temperature control system as in claim 1 wherein: A fifth pipeline branches off from the first pipeline, and the fifth pipeline is connected to the second pipeline and the third pipeline respectively. A first shut-off valve is installed on the fifth pipeline, and the outlet of the arsenic removal protective bed reactor is connected to the fifth pipeline through a second shut-off valve.
3. The energy efficient ethylene plant carbon dioxide hydrogenator inlet temperature control system of claim 2 wherein: The first temperature control circuit includes a first temperature control regulating valve, a second temperature control regulating valve, and a first temperature controller. The first temperature control regulating valve is disposed on the third pipeline, the second temperature control regulating valve is disposed on the second pipeline, and the first temperature controller is disposed on the fourth pipeline.
4. The energy-saving inlet temperature control system for the C2 hydrogenation reactor of an ethylene plant according to claim 3, characterized in that: The second temperature control circuit includes a third temperature control valve, a fourth temperature control valve, and a second temperature controller. The third temperature control valve is installed on the process pipeline, the fourth temperature control valve is connected between the process pipeline and the first pipeline, and the second temperature controller is installed on the first pipeline. The second temperature controller is signal-connected to the third temperature control valve and the fourth temperature control valve, respectively.
5. An energy efficient ethylene plant carbon dioxide hydrogenator inlet temperature control system as in claim 4 wherein: The third temperature control loop includes a selection controller, which is signal-connected to the first temperature controller, the second temperature controller, the first temperature control valve, and the second temperature control valve.
6. An energy efficient ethylene plant carbon dioxide hydrogenator inlet temperature control system as in claim 5 wherein: A third shut-off valve is installed on the first pipeline, and the third shut-off valve is located behind the second temperature controller.
7. An energy efficient ethylene plant carbon dioxide hydrogenator inlet temperature control system as in claim 6 wherein: The heater is equipped with a low-pressure steam inlet and a low-pressure condensate outlet.
8. The energy efficient ethylene plant carbon dioxide hydrogenator inlet temperature control system of claim 6 wherein: The cooler is provided with a circulating cooling water inlet and a circulating cooling water outlet.