Energy-saving system for increasing temperature of extraction feeding unit of aromatic hydrocarbon device

Abstract

The utility model relates to an energy-saving system in production of an aromatic hydrocarbon device, in particular to an energy-saving system, method and system for increasing the temperature of an extraction feeding unit of the aromatic hydrocarbon device. Comprising a xylene reformate tower system, an extractive distillation unit system, an extractive distillation raw material tank system and a direct supply process connected between an outlet of the xylene reformate tower system and an inlet of the extractive distillation unit system, materials are mixed in an extractive distillation raw material tank system through a direct supply process to be supplied to an extractive distillation unit system, so that the feeding temperature of the extractive distillation unit is properly increased on the premise of ensuring safety and stability, the steam consumption of a steam reboiler of an extractive distillation tower can be effectively saved, and the energy consumption cost is saved; the circulating water consumption of the C6-C7 water cooler is saved, the energy consumption cost is saved, and the electric quantity consumption of the extraction raw material pump motor is saved; the purpose of recycling heat to the maximum extent is achieved, and waste of steam energy is greatly reduced.

Description

Technical Field

[0001] This utility model relates to an energy-saving system in the production of aromatics, specifically an energy-saving system and method for increasing the temperature of the extraction feed unit in an aromatics plant, belonging to the field of chemical energy-saving technology. Background Technology

[0002] The aromatics extraction distillation unit is a production unit within the aromatics plant. It is used to separate and cool the C6-C7 fractions generated from the upstream continuous reforming process to below 40°C via the xylene unit reforming oil separator before sending them to the extraction feed tank area (the internal floating roof tanks require a temperature below 40°C). The C6-C7 fractions are then further pumped to the extraction distillation unit for processing via intermediate feed pumps in the tank area.

[0003] Extractive distillation for aromatic hydrocarbon separation is a typical physical separation process. This process uses aqueous sulfolane as a solvent, primarily utilizing the principle that the solvent affects the relative volatility of different hydrocarbon components. Extractive distillation separates aromatics from non-aromatics. The resulting mixed aromatics are further separated in the aromatics distillation section to obtain benzene and toluene products, with non-aromatics as byproducts. During the design phase, concerns were raised about significant variations in the ratio of non-aromatics to aromatics in the C6-C7 fraction of the feed. Therefore, the C6-C7 fraction (80°C) of the reformate separator needed to be cooled before being sent to the extraction feed tank area. This resulted in a decrease in the extraction feed temperature to 40°C and heat loss. Summary of the Invention

[0004] In view of the above-mentioned technical problems, the purpose of this utility model is to provide an energy-saving system and method for increasing the temperature of the extraction feed unit of an aromatics plant. Under the premise of ensuring safety and stability, the feed temperature of the extraction distillation unit is appropriately increased to maximize the recovery and utilization of heat and greatly reduce the waste of steam energy.

[0005] To achieve the above objectives, the technical solution adopted by this utility model is: an energy-saving system for increasing the temperature of the extraction feed unit in an aromatics unit, comprising: a xylene reforming tower system, an extraction distillation unit system, an extraction distillation feed tank system, and a direct supply process connected between the outlet of the xylene reforming tower system and the inlet of the extraction distillation unit system; by mixing the feed with the extraction distillation feed tank system through the direct supply process, the feed temperature of the extraction distillation unit system is increased;

[0006] Furthermore, the xylene reforming tower system includes: a reforming tower, a reforming tower reflux tank, a reforming tower reflux pump, and C6~C7 water coolers; the top outlet pipeline of the reforming tower is connected to the reforming tower reflux tank, the outlet pipeline of the reforming tower reflux tank is connected to the inlet of the reforming tower reflux pump, the outlet of the reforming tower reflux pump is connected to the C6~C7 water coolers via a pipeline, and the outlet pipeline from the C6~C7 water coolers is connected to the extraction distillation feedstock tank system via a production-to-tank-area regulating valve;

[0007] Furthermore, the extraction and distillation feedstock system includes: an extraction feedstock tank, an extraction feedstock pump, an extraction tank area feed thermometer, and an extraction tank area feed regulating valve; the pipeline leading out of the extraction to the tank area regulating valve is connected to the extraction feedstock tank in the extraction and distillation feedstock system, and an electric valve and a gate valve are respectively installed near the bottom of the extraction feedstock tank between the extraction to the tank area regulating valve and the extraction feedstock tank; an extraction feedstock pipeline is connected from the bottom of the extraction feedstock tank to the extraction and distillation unit system; the extraction feedstock pipeline leads out from the bottom of the extraction feedstock tank and sequentially connects to the extraction feedstock pump, the extraction tank area feed thermometer, and the extraction tank area feed regulating valve;

[0008] Furthermore, a gate valve and an electric valve are also provided on the extraction feed pipeline at the bottom of the extraction raw material tank;

[0009] Furthermore, the extraction distillation unit system includes: an extraction distillation column and an extraction distillation column steam reboiler; the extraction feed pipeline of the extraction distillation feed tank system is connected to the side wall of the extraction distillation column, and the extraction distillation column steam reboiler is connected to the extraction distillation column via a pipeline.

[0010] Furthermore, the direct supply process includes: a direct supply cross-line, one end of which is connected to the outlet of the reforming tower reflux pump, and the other end is connected to the extraction feed pipeline located at the feed position of the extraction distillation unit system; the direct supply cross-line is equipped with a direct supply flow meter, a direct supply regulating valve, a control valve and a check valve in sequence according to the feed direction;

[0011] Furthermore, the control valve and check valve are located on the direct supply cross line near the feed line to prevent material from flowing back from the direct supply cross line.

[0012] Furthermore, a mixing supply temperature gauge is installed in the area of ​​the extraction supply pipeline behind the intersection of the direct supply cross-line and the extraction supply pipeline to measure the temperature of the mixed materials.

[0013] Furthermore, the medium in the reforming oil tower reflux tank that exits from the reforming oil tower reflux pump has a temperature of 80°C and a pressure of 0.75 MPa.

[0014] In the energy-saving system described above, the reforming tower is composed of C6-C7 fractions. The medium in the reforming tower is cooled to 80°C and then collected by the reforming tower reflux pump. The reflux pump outlet splits into two branches: one is pressurized and sent back to the reforming tower via a reflux line for mass and heat transfer; the other is cooled by a C6-C7 water cooler and then mixed in the extraction feed tank. The C6-C7 fractions are then pressurized by the extraction feed pump and sent to the extraction distillation tower for product separation. Simultaneously, a direct supply line is established before the two branches at the outlet of the reforming tower reflux pump. The medium is mixed with the medium flowing from the extraction feed pump in the original extraction feed tank and fed to the extraction distillation unit system, thereby increasing the feed temperature of the extraction distillation unit system to a maximum of 80°C. This effectively saves steam consumption in the extraction distillation tower reboiler, reducing energy costs; saves circulating water consumption in the C6-C7 water cooler, reducing energy costs; and saves electricity consumption in the extraction feed pump motor.

[0015] The energy-saving method for the energy-saving system using the above structure includes the following operation process:

[0016] 1. The medium flows from the reforming oil tower reflux tank through the reforming oil tower reflux pump. The direct supply flow meter and direct supply cross-line are put into operation. The direct supply regulating valve is opened to increase the flow rate at a rate of 2t / h.

[0017] 2. Close the extraction to tank area regulating valve at a rate of 2t / h, and close the C6~C7 fraction to extraction feed tank at a rate of 2t / h; simultaneously close the extraction feed pump outlet at a rate of 2t / h, i.e., reduce the flow rate of the extraction tank area feed regulating valve; the flow rate of the extraction to tank area regulating valve 5 is synchronized with and the same as the flow rate of the extraction tank area feed regulating valve and the flow rate of the direct feed regulating valve 11.

[0018] 3. As the flow rate of the hot C6~C7 fraction at 80℃ in the direct supply process gradually increases and the flow rate of the cold C6~C7 fraction at 40℃ from the extraction raw material pump gradually decreases, the temperature of the mixed material, as measured by the mixing feed temperature gauge, gradually increases. At this point, the temperature starts to rise slowly from 40℃.

[0019] 4. Continue to increase the flow rate of the direct supply regulating valve, so that the flow rate of the direct supply regulating valve 11 reaches the maximum design flow rate of 115t / h for the extraction unit; and simultaneously close the regulating valve from the extraction to the tank area; and simultaneously close the regulating valve of the extraction tank area and stop the extraction raw material pump.

[0020] 5. Finally, the C6~C7 fractions are transported by the reforming oil tower reflux pump and directly fed to the extraction distillation tower via the direct feed flow meter, direct feed cross-line, and direct feed regulating valve. The mixed feed temperature gauge shows that it reaches 80℃. The increase in feed temperature and the shortening of the direct feed process stabilize the feed pressure of the extraction distillation tower at 0.5Mpa and 80℃.

[0021] Finally, the tank area regulating valve is closed, the C6-C7 water cooler is shut down, the extraction feed pump is stopped, and the extraction tank area feeding regulating valve 9 is closed.

[0022] In the above process, the final feed pressure of the extraction distillation column in step 5 is 0.5 MPa because the extraction distillation column has a large volume and low pressure, which forms a state equilibrium in the system, and the pressure naturally decreases to 0.5 MPa.

[0023] The above operating method can effectively save steam consumption in the steam reboiler of the extraction distillation tower, thus saving energy costs; save circulating water consumption in the C6-C7 water cooler, thus saving energy costs; and save electricity consumption in the extraction raw material pump motor.

[0024] The beneficial effects of this utility model are:

[0025] By appropriately increasing the feed temperature of the extraction distillation unit while ensuring safety and stability, and by mixing the feed with the raw material tank system in the direct supply process, the feed temperature of the extraction distillation unit system can be increased. This can effectively save on the steam consumption of the steam reboiler in the extraction distillation tower, thus saving on energy costs; save on the circulating water consumption of the C6-C7 water cooler, thus saving on energy costs; and save on the electricity consumption of the extraction raw material pump motor. This achieves the goal of maximizing heat recovery and utilization, and greatly reduces the waste of steam energy. Attached Figure Description

[0026] Figure 1 This utility model discloses an energy-saving system flow chart for increasing the temperature of the extraction feed unit in an aromatics plant.

[0027] In the diagram, 1. Reformer, 2. Reformer reflux tank, 3. Reformer reflux pump, 4. C6-C7 water cooler, 5. Control valve from production to tank area, 6. Extraction feed tank, 7. Extraction feed pump, 8. Extraction tank area feed thermometer, 9. Extraction tank area feed control valve, 101. Direct supply line, 10. Direct supply flow meter, 11. Direct supply control valve, 12. Mixed feed temperature gauge, 13. Extraction distillation column, 14. Extraction distillation column steam reboiler, 15. Reflux line, 16. Gate valve, 17. Electric valve, 18. Control valve, 19. Check valve. Detailed Implementation

[0028] To make the above-mentioned objects, features, and advantages of this utility model more apparent and understandable, the specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a full understanding of this utility model. However, this utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this utility model. Therefore, this utility model is not limited to the specific embodiments disclosed below.

[0029] Example 1

[0030] like Figure 1 An energy-saving system for increasing the temperature of an aromatics unit extraction feed unit is shown, comprising: a xylene reforming tower system, an extraction distillation unit system, an extraction distillation feed tank system, and a direct supply process connecting the outlet of the xylene reforming tower system and the inlet of the extraction distillation unit system; the feed is supplied to the extraction distillation unit system by mixing with the feed in the extraction distillation feed tank system through the direct supply process, thereby increasing the feed temperature of the extraction distillation unit system.

[0031] Furthermore, the xylene reforming tower system includes: a reforming tower 1, a reforming tower reflux tank 2, a reforming tower reflux pump 3, and a C6~C7 water cooler 4; the top outlet pipeline of the reforming tower 1 is connected to the reforming tower reflux tank 2, the outlet pipeline of the reforming tower reflux tank 2 is connected to the inlet of the reforming tower reflux pump 3, the outlet of the reforming tower reflux pump 3 is connected to the C6~C7 water cooler 4 through a pipeline, and the outlet pipeline from the C6~C7 water cooler 4 is connected to the extraction distillation feedstock tank system through the extraction to tank area regulating valve 5;

[0032] Furthermore, the extraction and distillation feedstock system includes: an extraction feedstock tank 6, an extraction feedstock pump 7, an extraction tank area feed thermometer 8, and an extraction tank area feed regulating valve 9; the pipeline leading out of the extraction to tank area regulating valve 5 is connected to the extraction feedstock tank 6 in the extraction and distillation feedstock system, and an electric valve 17 and a gate valve 18 are respectively installed near the bottom of the extraction feedstock tank 6 between the extraction to tank area regulating valve 5 and the extraction feedstock tank 6; an extraction feedstock pipeline is connected from the bottom of the extraction feedstock tank 6 to the extraction and distillation unit system; the extraction feedstock pipeline leads out from the bottom of the extraction feedstock tank 6 and is sequentially connected to the extraction feedstock pump 7, the extraction tank area feed thermometer 8, and the extraction tank area feed regulating valve 9;

[0033] Furthermore, a gate valve 16 and an electric valve 17 are also provided on the extraction feed pipeline at the bottom of the extraction raw material tank 6;

[0034] Furthermore, the extraction distillation unit system includes: an extraction distillation column 13 and an extraction distillation column steam reboiler 14; the extraction feed pipeline of the extraction distillation feed tank system is connected to the side wall of the extraction distillation column 13, and the extraction distillation column steam reboiler 14 is connected to the extraction distillation column 13 via a pipeline.

[0035] Furthermore, the direct supply process includes: a direct supply line 101, one end of which is connected to the outlet of the reforming tower reflux pump 3, and the other end is connected to the extraction feed pipeline located at the feed position of the extraction distillation unit system; the direct supply line 101 is equipped with a direct supply flow meter 10, a direct supply regulating valve 11, a control valve 18, and a check valve 19 in sequence according to the feed direction;

[0036] Furthermore, the control valve 18 and the check valve 19 are located on the direct supply cross line 101 near the feed line to prevent material from flowing back from the direct supply cross line 101.

[0037] Furthermore, a mixing supply temperature gauge 12 is provided in the area of ​​the extraction supply pipeline at the rear of the intersection of the direct supply cross line 101 and the extraction supply pipeline, for measuring the temperature of the mixed materials.

[0038] Furthermore, the medium exiting the reforming oil tower reflux tank 2 from the reforming oil tower reflux pump 3 has a temperature of 80°C and a pressure of 0.75 MPa.

[0039] In the energy-saving system described above, reforming tower 1 is divided into C6-C7 fractions. The medium in reforming tower 1 is cooled to 80°C and then collected by reforming tower reflux pump 3. The medium is then split into two branches at the outlet of reforming tower reflux pump 3. One branch is pressurized and sent back to reforming tower 1 through reflux line 15 for reflux mass transfer and heat transfer. The other branch is cooled by C6-C7 water cooler 4 and then enters extraction feed tank 6 for mixing. The C6-C7 fractions are then pressurized by extraction feed pump 7 and sent to extraction distillation tower 13 to separate the product. At the same time, the medium is mixed with the medium flowing out of extraction feed pump 7 from the original extraction feed tank 6 through direct supply line 101 before the two branches at the outlet of reforming tower reflux pump 3, and then fed to the extraction distillation unit system, thereby increasing the feed temperature of the extraction distillation unit system to a maximum of 80°C.

[0040] Example 2

[0041] Based on the structure of the energy-saving system in Embodiment 1 above, the energy-saving method for increasing the temperature of the aromatics extraction feed unit includes the following operation process:

[0042] 1. The medium flows from the reforming oil tower reflux tank 2 through the reforming oil tower reflux pump 3, the direct supply flow meter 10 and the direct supply cross line 101 are put into operation, and the direct supply regulating valve 11 is opened to increase the flow rate at a speed of 2t / h;

[0043] 2. Close the collection-to-tank-area regulating valve 5 at a rate of 2t / h, and close the flow rate of C6~C7 fraction to extraction feed tank 6 at a rate of 2t / h; simultaneously close the outlet of extraction feed pump 7 at a rate of 2t / h, that is, reduce the flow rate of extraction tank area feed regulating valve 9; the flow rate reduced by collection-to-tank-area regulating valve 5, the flow rate reduced by extraction tank area feed regulating valve 9, and the flow rate increased by direct feed regulating valve 11 are synchronized and the same, which can ensure the balance of flow rate;

[0044] 3. As the flow rate of the hot C6~C7 fraction at 80℃ in the direct supply process gradually increases and the flow rate of the cold C6~C7 fraction at 40℃ from the extraction raw material pump 7 gradually decreases, the mixed material, after being measured by the mixing feed temperature gauge 12, shows a gradual increase in temperature. At this point, the temperature starts to rise slowly from 40℃.

[0045] 4. Continue to increase the flow rate of the direct supply regulating valve 11 until it reaches the maximum design flow rate of 115t / h for the extraction unit; and simultaneously close the extraction to tank area regulating valve 5; simultaneously close the extraction tank area regulating valve 9 and stop the extraction raw material pump 7.

[0046] 5. Finally, the C6~C7 fractions are transported by the reforming oil tower reflux pump 3 and directly fed to the extraction distillation tower 13 via the direct feed flow meter 10, the direct feed cross-line 101, and the direct feed regulating valve 11. The mixed feed temperature gauge 12 shows that it reaches 80℃. The increase in feed temperature and the shortening of the direct feed process make the feed pressure of the extraction distillation tower 13 stable at 0.5Mpa and 80℃.

[0047] Finally, the tank area regulating valve 5 is closed, the C6-C7 water cooler 4 is shut down, the extraction feed pump 7 is stopped, and the extraction tank area feeding regulating valve 9 is closed.

[0048] The maximum flow rate of the extraction unit in step 4 above is determined based on the process design scale of the extraction unit. In this embodiment, the maximum flow rate of the extraction unit is 115 t / h.

[0049] In the description of this utility model, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0051] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0052] In this utility model, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0053] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0054] The above-listed embodiments are merely preferred embodiments of this utility model. Obviously, this utility model is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this utility model should be considered within the protection scope of this utility model.

Claims

1. An energy-saving system for increasing the temperature of the extraction feed unit in an aromatics plant, characterized in that, include: The xylene reforming tower system, the extraction distillation unit system, the extraction distillation feed tank system, and the direct supply process connecting the outlet of the xylene reforming tower system and the inlet of the extraction distillation unit system; the feed to the extraction distillation unit system is increased by mixing the feed from the extraction distillation feed tank system with the feed from the direct supply process.

2. The energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 1, characterized in that: The xylene reforming tower system includes: a reforming tower, a reforming tower reflux tank, a reforming tower reflux pump, and C6-C7 water coolers; the top outlet pipeline of the reforming tower is connected to the reforming tower reflux tank, the outlet pipeline of the reforming tower reflux tank is connected to the inlet of the reforming tower reflux pump, the outlet of the reforming tower reflux pump is connected to the C6-C7 water coolers via a pipeline, and the outlet pipeline from the C6-C7 water coolers is connected to the extraction distillation feedstock tank system via a production-to-tank-area regulating valve.

3. The energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 2, characterized in that: The extraction and distillation feedstock system includes: an extraction feedstock tank, an extraction feedstock pump, an extraction tank area feed thermometer, and an extraction tank area feed regulating valve; the pipeline leading out of the extraction to the tank area regulating valve is connected to the extraction feedstock tank in the extraction and distillation feedstock system, and an electric valve and a gate valve are respectively installed near the bottom of the extraction feedstock tank between the extraction to the tank area regulating valve and the extraction feedstock tank; an extraction feedstock pipeline is connected from the bottom of the extraction feedstock tank to the extraction and distillation unit system; the extraction feedstock pipeline leads out from the bottom of the extraction feedstock tank and is sequentially connected to the extraction feedstock pump, the extraction tank area feed thermometer, and the extraction tank area feed regulating valve.

4. The energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 3, characterized in that: The extraction distillation unit system includes: an extraction distillation column and an extraction distillation column steam reboiler; the extraction feed pipeline of the extraction distillation feed tank system is connected to the side wall of the extraction distillation column, and the extraction distillation column steam reboiler is connected to the extraction distillation column via a pipeline.

5. An energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 4, characterized in that: The direct supply process includes: a direct supply cross-line, one end of which is connected to the outlet of the reforming tower reflux pump, and the other end is connected to the extraction feed pipeline located at the feed position of the extraction distillation unit system; the direct supply cross-line is equipped with a direct supply flow meter, a direct supply regulating valve and control valve and a check valve in sequence according to the feed direction.

6. The energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 5, characterized in that: The control valve and check valve are located on the direct supply cross line near the pumping supply pipeline.

7. An energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 5, characterized in that: A mixing temperature gauge is installed in the area of ​​the extraction feed pipeline behind the intersection of the direct supply cross-line and the extraction feed pipeline.

8. An energy-saving system for increasing the temperature of the extraction feed unit of an aromatics plant according to claim 2, characterized in that: The medium in the reforming oil tower reflux tank is pumped out from the reforming oil tower reflux pump at a temperature of 80°C and a pressure of 0.75 MPa.

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