Dividing wall column separation system for propane / isobutane mixed dehydrogenation unit

Abstract

The present application belongs to the field of petrochemical separation technology, and particularly relates to a partition wall column separation system for a propane / isobutane mixed dehydrogenation device. The partition wall column separation system for the propane / isobutane mixed dehydrogenation device comprises a partition wall column, a first overhead condenser, a first overhead reflux tank, a first overhead reflux pump, a second overhead condenser, a second overhead reflux tank, a second overhead reflux pump and a side line extraction pump; a partition plate is vertically arranged in the partition wall column, and the partition plate separates the upper part of the partition wall column into a light component removal zone and a propane / carbon four separation and extraction zone, and a lower section stripping zone is arranged below the partition plate. The present application removes water and light components such as ethane and ethylene in the reaction product of the propane / isobutane mixed dehydrogenation device, simultaneously realizes the separation of propylene propane and carbon four components, and obtains qualified materials meeting the requirements of downstream device equipment, with less equipment investment, compact equipment arrangement and saved land occupation.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical separation technology, specifically relating to a wall-mounted column separation system for a propane / isobutane mixed dehydrogenation unit. Background Technology

[0002] Propylene and isobutylene are both important chemical raw materials. Propylene is the second largest chemical raw material after ethylene, mainly used to produce dozens of chemical products such as polypropylene, ethylene oxide, acrylic acid, acrylonitrile, butanol, and octanol. Isobutylene is also an important chemical raw material, used to produce dozens of high-value-added chemical products such as butyl rubber, methyl tert-butyl ether, methyl methacrylate, polyisobutylene, and methacrylonitrile. Currently, industrial propylene and isobutylene mainly come from byproducts of catalytic cracking and steam cracking to produce ethylene, with limited capacity that cannot meet the growing market demand. Propane / isobutylane mixed alkane dehydrogenation units, using light olefins as the main product, can achieve simultaneous dehydrogenation of propane and isobutylene within a single unit, effectively filling the market gap for propylene and isobutylene. Statistics show that my country currently has nearly thirty propane dehydrogenation and mixed dehydrogenation units built or under construction, with a total capacity exceeding 30 million tons.

[0003] The reaction products of mixed dehydrogenation are compressed, resulting in a large liquid phase separation. Existing separation processes typically include a light component removal tower to remove water and light components. The material after water and light component removal is rich in C4 and C3 components. This material then enters a propane removal tower. Material from the ethane removal tower also enters the propane removal tower. In the propane removal tower, propylene, propane, and C4 components are separated. The propane and propylene feedstock is generally collected from the side stream of the propane removal tower and then enters the propylene distillation tower. This unit uses two distillation tower systems—the light component removal tower and the propane removal tower—resulting in large equipment investment, high energy consumption, and a large footprint. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides a wall-mounted column separation system for a propane / isobutane mixed dehydrogenation unit. This system removes water and light components such as ethane and ethylene from the reaction products of the propane / isobutane mixed dehydrogenation unit, while simultaneously separating propylene and propane from C4 components. This results in qualified materials that meet the requirements of downstream equipment. The system requires less investment, has a compact layout, and saves floor space.

[0005] The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to the present invention includes an indirect wall column, a first column top condenser, a first column top reflux tank, a first column top reflux pump, a second column top condenser, a second column top reflux tank, a second column top reflux pump, and a side stream extraction pump.

[0006] The partition wall column is vertically equipped with a partition plate, which divides the upper part of the partition wall column into a light component removal zone and a propane / C4 separation and extraction zone, with the lower section of the stripping zone below the partition plate.

[0007] The top of the light component removal zone is connected to the upper part of the second top reflux tank via the second top condenser. The upper part of the second top reflux tank is also equipped with a second top product pipeline. The lower part of the second top reflux tank is connected to the inlet of the second top reflux pump. The outlet of the second top reflux pump is connected to the second top reflux port of the light component removal zone via the second top reflux pipeline. The light component removal zone is connected to the liquid phase material discharge pipeline of the compression unit via the liquid phase material inlet, which is located below the second top reflux port.

[0008] The top of the propane / C4 separation and extraction zone is connected to the upper part of the first top reflux tank via the first top condenser. The upper part of the first top reflux tank is also equipped with the first top product pipeline. The lower part of the first top reflux tank is connected to the inlet of the first top reflux pump. The outlet of the first top reflux pump is connected to the first top reflux port of the propane / C4 separation and extraction zone via the first top reflux pipeline. Below the first top reflux port is a liquid collection tank for the extraction zone. The liquid collection tank for the extraction zone is connected to the side line discharge pipeline. The side line discharge pipeline is equipped with a side line extraction pump. The propane / C4 separation and extraction zone is connected to the de-ethane tower material product outlet pipeline via the de-ethane material inlet. The de-ethane material inlet is located below the side line discharge pipeline.

[0009] Preferably, the bottom of the partition wall tower is provided with a bottom discharge pipeline, and the bottom discharge pipeline is provided with a bottom discharge pump and a bottom discharge regulating circuit to extract components such as C4 from the bottom of the tower.

[0010] Preferably, the bottom of the partition wall column is equipped with a bottom reboiler, which uses low-pressure steam (0.35 MPaG) as the heating source for the bottom reboiler; a steam feed regulating valve is installed on the steam inlet pipeline of the bottom reboiler; a bottom temperature sensor and a bottom level gauge are installed at the bottom of the column; the steam feed regulating valve and the bottom temperature sensor form a cascade control, and the steam feed rate of the reboiler is controlled by the bottom temperature; the bottom discharge regulating loop and the bottom level gauge form a cascade control.

[0011] Preferably, the bottom reboiler is a vertical thermosiphon reboiler.

[0012] Preferably, a first tower top discharge pressure control valve is installed on the first tower top outlet pipeline, and a second tower top discharge pressure control valve is installed on the second tower top outlet pipeline.

[0013] Preferably, the first top reflux pipeline is equipped with a first top flow regulation loop, and the first top reflux tank is equipped with a first reflux tank level gauge, the first reflux tank level gauge and the first top flow regulation loop forming a cascade control; the second top reflux pipeline is equipped with a second top flow regulation loop, and the second top reflux tank is equipped with a second reflux tank level gauge, the second reflux tank level gauge and the second top flow regulation loop forming a cascade control.

[0014] Preferably, the side discharge pipeline is equipped with a side discharge flow rate regulating loop, and the liquid collection tank in the extraction area is equipped with a liquid collection tank level gauge. The liquid collection tank level gauge and the side discharge flow rate regulating loop constitute a cascade control.

[0015] Preferably, the light component removal zone and the propane / C4 separation and extraction zone are respectively provided with packing sections, and the packing sections are filled with high-efficiency structured packing.

[0016] Preferably, the light component removal zone is provided with a first packing section, a second packing section and a third packing section from top to bottom, and a liquid material inlet is provided between the first packing section and the second packing section; the propane / C4 separation and extraction zone is provided with a fourth packing section, a fifth packing section and a sixth packing section from top to bottom, and an extraction zone collection tank and an extraction zone redistributor are provided between the fourth packing section and the fifth packing section, and an ethane-removed material inlet is provided between the fifth packing section and the sixth packing section.

[0017] Preferably, a guide plate is provided at the top of the lower stripping zone.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. This invention replaces the dual-tower separation system consisting of a light component removal tower and a propane removal tower with a wall-mounted tower separation system. It realizes the functions of two or more towers in one shell, which can obtain side-stream products with higher purity and save one tower and one reboiler, thereby reducing equipment investment.

[0020] 2. The indirect wall column of this invention is a thermally coupled distillation system, which can reduce energy consumption to a certain extent; the equipment layout is more compact, which can significantly save floor space.

[0021] 3. This invention removes water and light components such as ethane and ethylene from the reaction products of the propane / isobutane mixed dehydrogenation unit, while simultaneously separating propylene and propane from C4 components, and obtaining qualified materials that meet the requirements of downstream equipment. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the present invention (where A represents the liquid phase material separated from the compression unit, B represents the material from the de-ethane tower, C represents the non-condensable gas separated from the light component removal zone, D represents the non-condensable gas separated from the propane / C4 separation and extraction zone, E represents the extracted mixed propane and propylene material, F represents the C4 component in the tower bottom, G represents 0.35MPaG low-pressure steam, and H represents circulating cooling water).

[0023] In the diagram: 1. Indirect-flow column; 2. First column top condenser; 3. First column top reflux tank; 4. First column top reflux pump; 5. Second column top condenser; 6. Second column top reflux tank; 7. Second column top reflux pump; 8. Side-stream extraction pump; 9. Baffle; 10. Light component removal zone; 101. First packing section; 102. Second packing section; 103. Third packing section; 11. Propane / C4 separation and extraction zone; 111. Fourth packing section; 112. Fifth packing section; 113. Sixth packing section; 12. Lower stripping zone; 13. Second column top product line; 14. Second column top reflux line; 15. Second column top reflux port; 16. Liquid phase material inlet; 17. Liquid phase material outlet line; 18. First column top product line; 19. 20. First top reflux pipeline; 21. Extraction zone collection tank; 22. Side discharge pipeline; 23. Material inlet after ethane removal; 24. Material collection pipeline from the ethane removal tower; 25. Bottom discharge pipeline; 26. Bottom discharge pump; 27. Bottom discharge regulating loop; 28. Bottom reboiler; 29. ​​Steam feed regulating valve; 30. Bottom temperature sensor; 31. Bottom level gauge; 32. First top discharge pressure control valve; 33. Second top discharge pressure control valve; 34. First top flow regulating loop; 35. First reflux tank level gauge; 36. Second top flow regulating loop; 37. Second reflux tank level gauge; 38. Side discharge flow regulating loop; 39. Collection tank level gauge; 40. Baffle plate. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings and embodiments.

[0025] It should be noted that relational terms such as "first" and "second" in this text are only used to distinguish one entity or operation from another for ease of expression, and do not represent a sequential relationship.

[0026] like Figure 1 As shown, the indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit of the present invention includes an indirect wall column 1, a first column top condenser 2, a first column top reflux tank 3, a first column top reflux pump 4, a second column top condenser 5, a second column top reflux tank 6, a second column top reflux pump 7, and a side stream extraction pump 8.

[0027] The partition plate 9 is vertically installed inside the partition wall column 1. The partition plate 9 divides the upper part of the partition wall column 1 into a light component removal zone 10 and a propane / C4 separation and extraction zone 11. Below the partition plate 9 is the lower section stripping zone 12.

[0028] The top of the light component removal zone 10 is connected to the upper part of the second top reflux tank 6 via the second top condenser 5. The upper part of the second top reflux tank 6 is also equipped with a second top outflow pipeline 13. The lower part of the second top reflux tank 6 is connected to the inlet of the second top reflux pump 7. The outlet of the second top reflux pump 7 is connected to the second top reflux port 15 of the light component removal zone 10 via the second top reflux pipeline 14. The light component removal zone 10 is connected to the liquid phase material discharge pipeline 17 of the compression unit via the liquid phase material inlet 16. The liquid phase material inlet 16 is located below the second top reflux port 15.

[0029] The top of the propane / C4 separation and extraction zone 11 is connected to the upper part of the first top reflux tank 3 via the first top condenser 2. The upper part of the first top reflux tank 3 is also equipped with a first top product pipeline 18. The lower part of the first top reflux tank 3 is connected to the inlet of the first top reflux pump 4. The outlet of the first top reflux pump 4 is connected to the first top reflux port 20 of the propane / C4 separation and extraction zone 11 via the first top reflux pipeline 19. Below the first top reflux port 20 is an extraction zone collection tank 21, which is connected to a side-line discharge pipeline 22. A side-line extraction pump 8 is installed on the side-line discharge pipeline 22. The propane / C4 separation and extraction zone 11 is connected to the de-ethane tower product product collection pipeline 24 via the de-ethane dematerial inlet 23, which is located below the side-line discharge pipeline 22. The first top condenser 2 and the second top condenser 5 are respectively supplied with cooling capacity by circulating cooling water H.

[0030] The bottom of the partition tower 1 is provided with a bottom discharge pipeline 25, and the bottom discharge pipeline 25 is provided with a bottom discharge pump 26 and a bottom discharge regulating circuit 27.

[0031] The bottom of the partition wall column 1 is equipped with a bottom reboiler 28, which uses 0.35MPaG low-pressure steam G as the heating source for the bottom reboiler; a steam feed regulating valve 29 is installed on the steam inlet pipeline of the bottom reboiler 28, and a bottom temperature sensor 30 and a bottom level gauge 31 are installed at the bottom of the column. The steam feed regulating valve 29 and the bottom temperature sensor 30 form a cascade control; the bottom discharge regulating loop 27 and the bottom level gauge 31 form a cascade control.

[0032] The bottom reboiler 28 is a vertical thermosiphon reboiler.

[0033] The first tower top extraction pipeline 18 is equipped with a first tower top discharge pressure control valve 32, and the second tower top extraction pipeline 13 is equipped with a second tower top discharge pressure control valve 33.

[0034] The first top reflux line 19 is equipped with a first top flow regulation loop 34, and the first top reflux tank 3 is equipped with a first reflux tank level gauge 35. The first reflux tank level gauge 35 and the first top flow regulation loop 34 form a cascade control. The second top reflux line 14 is equipped with a second top flow regulation loop 36, and the second top reflux tank 6 is equipped with a second reflux tank level gauge 37. The second reflux tank level gauge 37 and the second top flow regulation loop 36 form a cascade control.

[0035] The side discharge pipeline 22 is equipped with a side discharge flow rate regulating circuit 38, and the liquid collection tank 21 in the extraction area is equipped with a liquid collection tank level gauge 39. The liquid collection tank level gauge 39 and the side discharge flow rate regulating circuit 38 constitute a cascade control.

[0036] The light component removal zone 10 and the propane / C4 separation and extraction zone 11 are respectively equipped with packing sections, which are filled with high-efficiency structured packing.

[0037] The light component removal zone 10 is provided with a first packing section 101, a second packing section 102 and a third packing section 103 from top to bottom. A liquid material inlet 16 is provided between the first packing section 101 and the second packing section 102. The liquid material separated by the compression unit enters the lower part of the first packing section 101. The height of the first packing section 101 is set to 2m, and the height of the second packing section 102 and the third packing section 103 is set to 3m, with a total packing height of 8m.

[0038] The propane / C4 separation and extraction zone 11 is provided with a fourth packing section 111, a fifth packing section 112, and a sixth packing section 113 from top to bottom. An extraction zone collection tank 21 and an extraction zone redistributor are provided between the fourth packing section 111 and the fifth packing section 112. Mixed propane and propylene are extracted from the side stream of the extraction zone collection tank 21. The material from the upstream unit de-ethane tower enters the lower part of the fourth packing section 111. An ethane-de-ethane material inlet 23 is provided between the fifth packing section 112 and the sixth packing section 113. The height of the fourth packing section 111 and the fifth packing section 112 is set to 2m, and the height of the sixth packing section 113 is set to 4m, for a total packing height of 8m.

[0039] A guide plate 40 is provided on the upper part of the lower stripping zone 12.

[0040] The lower stripping zone 12 adopts a plate column with a theoretical number of 40 plates.

[0041] Working process: Liquid material A separated from the compression unit and material B from the upstream ethane stripper enter the lower part of the first packing section 101 of the light component removal zone 10 and the lower part of the fifth packing section 112 of the propane / C4 separation and extraction zone 11 of the indirect wall column 1, respectively. Two gaseous streams are distilled from the top of the indirect wall column 1: one is non-condensable gas C separated from the light component removal zone 10, and the other is non-condensable gas D separated from the propane / C4 separation and extraction zone 11. Mixed propane and propylene material E is distilled from the side stream of the indirect wall column 1, and C4 component F is collected from the bottom of the indirect wall column 1.

Claims

1. A wall-mounted column separation system for a propane / isobutane mixed dehydrogenation unit, characterized in that, It includes a partition wall tower (1), a first top condenser (2), a first top reflux tank (3), a first top reflux pump (4), a second top condenser (5), a second top reflux tank (6), a second top reflux pump (7), and a side-stream extraction pump (8). The partition wall column (1) is vertically equipped with a partition (9). The partition (9) divides the upper part of the partition wall column (1) into a light component removal zone (10) and a propane / C4 separation and extraction zone (11). Below the partition (9) is the lower section stripping zone (12). The top of the light component removal zone (10) is connected to the upper part of the second top reflux tank (6) through the second top condenser (5). The upper part of the second top reflux tank (6) is also provided with a second top outflow pipeline (13). The lower part of the second top reflux tank (6) is connected to the inlet of the second top reflux pump (7). The outlet of the second top reflux pump (7) is connected to the second top reflux port (15) of the light component removal zone (10) through the second top reflux pipeline (14). The light component removal zone (10) is connected to the liquid phase material discharge pipeline (17) of the compression unit through the liquid phase material inlet (16). The liquid phase material inlet (16) is located below the second top reflux port (15). The top of the propane / C4 separation and extraction zone (11) is connected to the upper part of the first top reflux tank (3) via the first top condenser (2). The upper part of the first top reflux tank (3) is also equipped with the first top product pipeline (18). The lower part of the first top reflux tank (3) is connected to the inlet of the first top reflux pump (4). The outlet of the first top reflux pump (4) is connected to the first top reflux of the propane / C4 separation and extraction zone (11) via the first top reflux pipeline (19). The first tower top reflux port (20) is provided with a liquid collection tank (21) for the extraction zone below the reflux port (20). The liquid collection tank (21) for the extraction zone is connected to the side discharge pipeline (22). The side discharge pipeline (22) is provided with a side extraction pump (8). The propane / C4 separation and extraction zone (11) is connected to the deethane tower material collection pipeline (24) through the deethane dematerial inlet (23). The deethane dematerial inlet (23) is located below the side discharge pipeline (22). The bottom of the indirect wall tower (1) is equipped with a reboiler (28).

2. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 1, characterized in that, The bottom of the partition tower (1) is provided with a bottom discharge pipeline (25), and the bottom discharge pipeline (25) is provided with a bottom discharge pump (26) and a bottom discharge regulating circuit (27).

3. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 1, characterized in that, A steam feed regulating valve (29) is provided on the steam inlet pipeline of the reboiler at the bottom of the tower (28). A bottom temperature sensor (30) and a bottom level gauge (31) are provided at the bottom of the tower. The steam feed regulating valve (29) and the bottom temperature sensor (30) form a cascade control. The bottom discharge regulating loop (27) and the bottom level gauge (31) form a cascade control.

4. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 3, characterized in that, The bottom reboiler (28) is a vertical thermosiphon reboiler.

5. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 1, characterized in that, The first tower top outlet pipeline (18) is equipped with a first tower top outlet pressure control valve (32), and the second tower top outlet pipeline (13) is equipped with a second tower top outlet pressure control valve (33).

6. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 1, characterized in that, The first top reflux line (19) is equipped with a first top flow regulation loop (34), and the first top reflux tank (3) is equipped with a first reflux tank level gauge (35). The first reflux tank level gauge (35) and the first top flow regulation loop (34) constitute a cascade control. The second top reflux line (14) is equipped with a second top flow regulation loop (36), and the second top reflux tank (6) is equipped with a second reflux tank level gauge (37). The second reflux tank level gauge (37) and the second top flow regulation loop (36) constitute a cascade control.

7. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 1, characterized in that, A side discharge flow rate regulating circuit (38) is provided on the side discharge pipeline (22), and a liquid level gauge (39) is provided in the liquid collection tank (21) of the extraction area. The liquid level gauge (39) and the side discharge flow rate regulating circuit (38) constitute a cascade control.

8. The indirect wall column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 1, characterized in that, The light component removal zone (10) and the propane / C4 separation and extraction zone (11) are respectively equipped with packing sections, which are filled with high-efficiency structured packing.

9. The wall-mounted column separation system for a propane / isobutane mixed dehydrogenation unit according to claim 8, characterized in that, The light component removal zone (10) is provided with a first packing section (101), a second packing section (102) and a third packing section (103) from top to bottom. A liquid material inlet (16) is provided between the first packing section (101) and the second packing section (102). The propane / C4 separation and extraction zone (11) is provided with a fourth packing section (111), a fifth packing section (112) and a sixth packing section (113) from top to bottom. An extraction zone collection tank (21) and an extraction zone redistributor are provided between the fourth packing section (111) and the fifth packing section (112). An ethane-free material inlet (23) is provided between the fifth packing section (112) and the sixth packing section (113).

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