C4s refining unit

Abstract

The utility model relates to isobutane dehydrogenation feed technology field, concretely is C4 material refining device. C4 material refining device, including inlet and outlet heat exchanger A, inlet and outlet heat exchanger A is connected with hydrogenation reactor through feed heating furnace, hydrogenation reactor is connected with stable tower inlet and outlet heat exchanger through outlet buffer tank, stable tower inlet and outlet heat exchanger is connected with stable tower, and stable tower is connected with deisobutane column through connecting pipeline, and deisobutane column is connected with isomerization reactor through inlet and outlet heat exchanger B. The device is aimed at the isobutane dehydrogenation device C4 feed of rich normal butane, realizes the separation of normal butane and isobutane through deisobutane column, and normal butane can be side line and is extracted for other purposes, or is converted into isobutane through isomerization reaction and returns deisobutane column, improves the utilization efficiency of C4 material.

Description

Technical Field

[0001] This utility model relates to the field of isobutane dehydrogenation feed technology, specifically to a C4 material refining device. Background Technology

[0002] C4 feedstock mainly comes from associated gas from oil and gas fields, liquefied petroleum gas produced by refineries, and post-ether C4 from MTBE units. Its main components include butane and butene, and it is a key feedstock source for isobutane dehydrogenation units.

[0003] Currently, catalysts widely used in industrial isobutane dehydrogenation units, such as Pt-based noble metal catalysts (UOPOleflex process) and Cr-based catalysts (Lummus process), have strict limits on the content of impurities such as sulfur, nitrogen, oxygen, olefins, and halides in the feed. For example, the feed to the C4 unit of the UOPOleflex process requires an isobutane content of ≥96 mol% and a total olefin content of no more than 5000 wt-ppm, so the C4 feed must be purified.

[0004] Existing equipment presents several challenges in purifying C4 feed. Chinese Patent CA103773498A, published on November 28, 2013, discloses a high-temperature hydrogenation process for liquefied petroleum gas (LPG) feed, capable of handling LPG with specific impurity content ranges. After hydrogenation purification, it meets the requirements for isobutane dehydrogenation feed. However, this process uses alkaline washing to remove impurities such as H2S, NH3, and water from the light components after hydrogenation separation. The alkaline washing tower is used separately, resulting in high investment costs. Furthermore, for C4 feed rich in n-butane, there is a lack of effective methods for separating n-butane and isobutane and fully utilizing n-butane, leaving room for improvement in energy conservation and consumption reduction. Utility Model Content

[0005] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a C4 material refining device, which is designed for C4 feed to an isobutane dehydrogenation unit rich in n-butane. The device separates n-butane and isobutane through an isobutane removal tower. The n-butane can be extracted by side stream for other uses, or converted into isobutane through an isomerization reaction and then returned to the isobutane removal tower, thereby improving the utilization efficiency of C4 material.

[0006] This utility model is achieved using the following technical solution:

[0007] The C4 material refining device includes a feed heat exchanger A, which is connected to a hydrogenation reactor via a feed heater. The hydrogenation reactor is connected to a stabilizer tower feed heat exchanger via a discharge buffer tank. The stabilizer tower feed heat exchanger is connected to the stabilizer tower. The stabilizer tower is connected to a deisobutane tower via a connecting pipe. The deisobutane tower is connected to an isomerization reactor via a feed heat exchanger B.

[0008] The feed heat exchanger A is connected to a feed pipe. The hydrogenation reactor is connected to the discharge buffer tank through the feed heat exchanger A. A discharge cooler is provided between the feed heat exchanger A and the discharge buffer tank. The discharge buffer tank is connected to the circulating hydrogen compressor through the inlet buffer tank of the circulating hydrogen compressor. The circulating hydrogen compressor is connected to the feed pipe through the outlet buffer tank of the circulating hydrogen compressor.

[0009] The stabilizer is connected to the stabilizer reflux tank A via the stabilizer top condenser A, and the stabilizer reflux tank A is connected to the stabilizer via the stabilizer reflux pump A. The stabilizer reboiler A is connected to the bottom of the stabilizer.

[0010] The stabilizer is connected to the isobutane removal tower via a stabilizer inlet and outlet heat exchanger. A connecting pipe is provided between the stabilizer inlet and outlet heat exchanger and the isobutane removal tower, and a dehydrogenation device pipe is connected to the connecting pipe.

[0011] The isobutane removal tower is connected to the inlet buffer tank of the heat pump compressor via a pipeline. The inlet buffer tank of the heat pump compressor is connected to the reboiler of the isobutane removal tower via the heat pump compressor. The reboiler of the isobutane removal tower is connected to the inlet buffer tank of the heat pump compressor via the outlet cooler of the heat pump compressor. The inlet buffer tank of the heat pump compressor is connected to the isobutane removal tower via the reflux pump of the isobutane removal tower. A product delivery pump is connected to the inlet buffer tank of the heat pump compressor. The heat pump compressor is connected to the outlet cooler of the heat pump compressor via a pipeline.

[0012] The feed heat exchanger B is connected to the heterogeneous stabilizer via a pipeline. The heterogeneous stabilizer is connected to the stabilizer reflux tank B via the stabilizer top condenser B. The stabilizer reflux tank B is connected to the heterogeneous stabilizer via the stabilizer reflux pump B. A stabilizer reboiler B is connected below the heterogeneous stabilizer. The heterogeneous stabilizer is connected to the connecting pipeline via the stabilizer bottom cooler. The bottom of the isomerization reactor is connected to the feed heat exchanger B via a pipeline. The bottom of the isobutane removal tower is connected to the C5+ heavy component cooler via a C5+ heavy component external pump.

[0013] The working principle of this utility model is as follows:

[0014] After C4 material is mixed with circulating hydrogen, it is heated to the reaction temperature in the feed heater after heat exchange in the feed heat exchanger, and then enters the hydrogenation reactor for reaction. The reaction temperature in the hydrogenation reactor is 270~350℃, the reaction pressure is 1.8~3.0MPaG, and the hydrogen-to-hydrogen ratio is 60~150.

[0015] The reaction products undergo heat exchange with the feed in the inlet and outlet heat exchangers, and after cooling in the cooler, they enter the outlet buffer tank. In the outlet buffer tank, hydrogen and liquid products are separated. The gaseous component at the top of the tank is mainly hydrogen, which is compressed by the circulating hydrogen compressor and returned to the reactor inlet, while fresh hydrogen is added at the compressor inlet. The liquid component at the bottom of the outlet buffer tank is sent to the stabilizer after heat exchange with the stabilizer tower inlet and outlet heat exchangers. In the stabilizer tower, the liquid product undergoes flash evaporation and distillation. The light components, carrying impurities such as H2S, HCl, and NH3 produced after purification, are discharged from the top of the tower. After condensation and gas-liquid separation, they are discharged from the top of the reflux tank. The bottom of the stabilizer tower yields purified C4 material. Stabilizer tower top operating temperature: 80~100℃, operating pressure: 1.5~2.2MPaG; stabilizer tower bottom operating temperature: 90~120℃, operating pressure: 1.8~2.5MPaG.

[0016] If the purified C4 material has a low n-butane content, it can be directly used as feed for the isobutane dehydrogenation unit after heat exchange. If the n-butane content is relatively high, n-butane and isobutane are separated by a deisobutane tower (DIB tower) after hydrorefining. The n-butane can be drawn off via a side stream and sent to a storage tank or downstream unit, or partially or completely converted to isobutane through a n-butane isomerization reaction and returned to the deisobutane tower. When using the isomerization process, the impurity requirements of the purified material must meet the requirements for dehydrogenation feed as well as the requirements for the isomerization catalyst. The specific process is as follows:

[0017] After refining, C4 material enters the isobutane removal tower, which employs heat pump energy-saving technology. The isobutane at the top of the tower enters the inlet buffer tank of the heat pump compressor. After compression by the heat pump compressor, a portion provides heat to the reboiler at the bottom of the isobutane removal tower, and the remaining portion, after cooling, returns to the inlet buffer tank. Liquid isobutane is discharged from the bottom of the inlet buffer tank; a portion is returned to the top of the isobutane removal tower via a reflux pump as reflux, and the remaining portion is pumped to the downstream isobutane dehydrogenation unit or storage tank via a product delivery pump. The bottom of the isobutane removal tower mainly contains C5+ heavy components; a portion is returned to the isobutane removal tower via the bottom reboiler, and the remaining portion is extracted, cooled, and sent to the outside. The top operating temperature of the isobutane removal tower is 35~45℃, and the operating pressure is 0.35~0.6MPaG. The bottom operating temperature of the isobutane removal tower is 45~70℃, and the operating pressure is 0.45~0.75MPaG.

[0018] The n-butane entering the isomerization unit is first mixed with hydrogen, and after heat exchange between the feed and discharge, it enters the isomerization reactor. Inside the reactor, n-butane is converted to isobutane under the action of a catalyst. The reaction temperature in the isomerization reactor is 130~220℃, and the reaction pressure is 2.9~3.5 MPaG.

[0019] After heat exchange with the feed, the reacted material enters the isomerization stabilizer. The top material, after condensation, enters the stabilizer reflux tank B. The top gas phase is dry isomerized gas, while the bottom liquid phase is pressurized by the stabilizer reflux pump B and returned to the stabilizer as reflux. The bottom material is sent to the isobutane removal tower after passing through a cooling zone. The isomerization stabilizer top operating temperature is 80~100℃, operating pressure is 1.9~2.2 MPaG; the isomerization stabilizer bottom operating temperature is 100~120℃, operating pressure is 2.0~2.3 MPaG. The n-butane delivery rate and isomerization ratio can be flexibly selected according to the needs of downstream units.

[0020] The composition of the light components discharged from the top of reflux tank A of the hydrorefining stabilizer is closely related to the light components in the feedstock, mainly consisting of hydrogen, methane, ethane, propane, and small amounts of one or more of n-butane and isobutane. The light components from reflux tank A and the dry gas from the top of reflux tank B of the isobutane stabilizer can be sent separately or combined to the regeneration gas alkaline scrubbing tower of the isobutane dehydrogenation unit's outlet dryer. After removing impurities such as H2S, HCl, and NH3 from the gas, it is sent together with the dry gas from the dehydrogenation unit to the dry gas compression and PSA unit or used as fuel gas for the unit.

[0021] Compared with the prior art, the beneficial effects of this utility model are:

[0022] (1) The alkaline washing tower for removing impurities such as H2S and NH3 from the light components after hydrogenation separation in this device is shared with the regeneration gas of the product gas dryer of the dehydrogenation unit or the isomerized dry gas of the isomerization unit. Compared with the existing technology, which sets up an alkaline washing tower separately, the equipment investment is effectively reduced.

[0023] (2) For the C4 feed of the isobutane dehydrogenation unit rich in n-butane, an innovative solution of isobutane removal tower + n-butane isomerization is proposed. The separation of n-butane and isobutane is achieved by the isobutane removal tower. The n-butane can be extracted by side stream for other uses, or converted into isobutane by isomerization reaction and then returned to the isobutane removal tower, thereby improving the utilization efficiency of C4 material.

[0024] (3) On the one hand, the deisobutane tower adopts heat pump energy-saving technology, which optimizes the energy utilization in the distillation process and reduces energy consumption. On the other hand, the feed heat exchangers (No. 1 and No. 30) of the hydrogenation reactor and the isomerization reactor are selected as high-efficiency coiled tube heat exchangers, which fully recover the heat generated by hydrogenation and isomerization reactions, further improve the energy utilization rate, and achieve the goal of energy saving and consumption reduction. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the C4 material refining device of this utility model;

[0026] In the diagram: 1. Feed / Discharge heat exchanger A; 2. Feed heater; 3. Hydrogenation reactor; 4. Discharge cooler; 5. Discharge buffer tank; 6. Circulating hydrogen compressor inlet buffer tank; 7. Circulating hydrogen compressor; 8. Circulating hydrogen compressor outlet buffer tank; 9. Stabilizer feed / discharge heat exchanger; 10. Stabilizer; 11. Stabilizer top condenser A; 12. Stabilizer reflux tank A; 13. Stabilizer reflux pump A; 14. Stabilizer reboiler A; 15. Isobutane removal tower; 16. Heat pump compressor inlet buffer tank; 17. Heat pump compressor; 18. Heat pump compressor... 19. Pump compressor outlet cooler; 20. Isobutane removal tower reflux pump; 21. Product delivery pump; 22. Isobutane removal tower reboiler; 23. C5+ heavy component delivery pump; 24. C5+ heavy component cooler; 25. Feed and discharge heat exchanger B; 26. Isomerization reactor; 27. Isomerization stabilizer; 28. Stabilizer top condenser B; 29. ​​Stabilizer reflux tank B; 30. Stabilizer bottom cooler; 31. Stabilizer reboiler B; 32. Feed pipeline; 33. Pipeline to dehydrogenation unit; 34. Connecting pipeline. Detailed Implementation

[0027] To make the objectives and technical solutions of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings.

[0028] Example 1

[0029] like Figure 1As shown, the C4 material refining unit includes a feed heat exchanger A1, which is connected to a hydrogenation reactor 3 via a feed heater 2. The hydrogenation reactor 3 is connected to a stabilizer tower feed heat exchanger 9 via a discharge buffer tank 5. The stabilizer tower feed heat exchanger 9 is connected to a stabilizer tower 10. The stabilizer tower 10 is connected to a deisobutane tower 15 via a connecting pipe 34. The deisobutane tower 15 is connected to an isomerization reactor 25 via a feed heat exchanger B24. The hydrogenation reactor 3 has a reaction temperature of 300℃, a reaction pressure of 2 MPaG, and a hydrogen-to-hydrogen ratio of 100. The stabilizer tower 10 has an operating temperature of 90℃ at the top and an operating pressure of 1.8 MPaG at the bottom. The stabilizer tower 10 has an operating temperature of 110℃ and an operating pressure of 2.2 MPaG at the bottom. A feed pipe 32 is connected to the feed heat exchanger A1. The hydrogenation reactor 3 is connected to the discharge buffer tank 5 through the feed heat exchanger A1. A discharge cooler 4 is installed between the feed heat exchanger A1 and the discharge buffer tank 5. The discharge buffer tank 5 is connected to the circulating hydrogen compressor 7 through the circulating hydrogen compressor inlet buffer tank 6. The circulating hydrogen compressor 7 is connected to the feed pipe 32 through the circulating hydrogen compressor outlet buffer tank 8. The stabilizer tower 10 is connected to the stabilizer tower reflux tank A12 above the stabilizer tower condenser A11. The stabilizer tower reflux tank A12 is connected to the stabilizer tower 10 through the stabilizer tower reflux pump A13. A stabilizer tower reboiler A14 is connected below the stabilizer tower 10. The stabilizer tower 10 is connected to the isobutane removal tower 15 through the stabilizer tower feed heat exchanger 9. A connecting pipe 34 is provided between the stabilizer tower feed heat exchanger 9 and the isobutane removal tower 15. A pipe 33 for the dehydrogenation unit is connected to the connecting pipe 34. The top of the deisobutane tower 15 is connected to the inlet buffer tank 16 of the heat pump compressor via a pipeline. The inlet buffer tank 16 of the heat pump compressor is connected to the reboiler 21 of the deisobutane tower via the heat pump compressor 17. The reboiler 21 of the deisobutane tower is connected to the inlet buffer tank 16 of the heat pump compressor via the outlet cooler 18 of the heat pump compressor. The inlet buffer tank 16 of the heat pump compressor is connected to the deisobutane tower 15 via the reflux pump 19 of the deisobutane tower. A product delivery pump 20 is connected to the inlet buffer tank 16 of the heat pump compressor. The heat pump compressor 17 is connected to the outlet cooler 18 of the heat pump compressor via a pipeline. The feed heat exchanger B24 is connected to the isomerization stabilizer 26 via a pipeline. The isomerization stabilizer 26 is connected to the stabilizer reflux tank B28 via the stabilizer top condenser B27. The stabilizer reflux tank B28 is connected to the isomerization stabilizer 26 via the stabilizer reflux pump B29. The stabilizer reboiler B31 is connected below the isomerization stabilizer 26. The isomerization stabilizer 26 is connected to the connecting pipeline 34 via the stabilizer bottom cooler 30. The bottom of the isomerization reactor 25 is connected to the feed heat exchanger B24 via a pipeline. The bottom of the deisobutane tower 15 is connected to the C5+ heavy component cooler 23 via the C5+ heavy component external pump 22.

[0030] The above-mentioned C4 material refining device includes the following steps during operation:

[0031] (1) C4 material is mixed with circulating hydrogen and after heat exchange in feed heat exchanger A1, it is heated to 270-350℃ in feed heater 2 and enters hydrogenation reactor 3 for reaction. The reaction pressure is 1.8-3.0 MPaG and the hydrogen-to-hydrogen ratio is 60-150. (2) The reaction product is cooled by feed heat exchanger A1 and discharge cooler 4 and then enters discharge buffer tank 5 to achieve gas-liquid separation. The gas phase hydrogen is compressed by circulating hydrogen compressor inlet buffer tank 6, circulating hydrogen compressor 7 and circulating hydrogen compressor outlet buffer tank 8 and then returned to the reactor inlet. The liquid phase is sent to stabilizer tower 10 through stabilizer tower feed heat exchanger 9. Inside the stabilizer tower 10, the light components carrying impurities are condensed by the stabilizer tower top condenser A11, and after gas-liquid separation in the stabilizer tower reflux tank A12, they are discharged from the top of the tank. The bottom of the stabilizer tower 10 yields refined C4 material. The temperature at the top of the stabilizer tower 10 is 80-100℃ and 1.5-2.2MPaG, and the temperature at the bottom of the tower is 90-120℃ and 1.8-2.5MPaG. (3) If the n-butane content of the refined C4 material is low, it can be directly used as feed for the dehydrogenation unit; if the content is high, it enters the isobutane removal tower 15. The isobutane removal tower 15 uses heat pump technology. The isobutane at the top of the tower enters the heat pump compressor inlet buffer tank 16. After being compressed by the heat pump compressor 17, part of it provides a heat source for the reboiler 21 of the isobutane removal tower. Then, it and another part are cooled by the heat pump compressor outlet cooler 18 and returned to the heat pump compressor inlet buffer tank 16. The liquid isobutane is sent out from the bottom of the heat pump compressor inlet buffer tank 16. Part of it is sent back to the top of the isobutane removal tower 15 as reflux by the isobutane removal tower reflux pump 19, and part of it is sent to the downstream isobutane dehydrogenation unit or storage tank by the product delivery pump 20. The bottom of the isobutane removal tower 15 mainly consists of C5+ heavy components. Part of it is returned to the isobutane removal tower 15 via the reboiler 21, and the rest is cooled by the C5+ heavy component external pump 22 and the C5+ heavy component cooler 23 before being sent to the outside. The top temperature of the isobutane removal tower 15 is 35-45℃ and the pressure is 0.35-0.6MPaG, while the bottom temperature is 45-70℃ and the pressure is 0.45-0.75MPaG. (4) n-Butane can also be isomerized. After mixing with hydrogen, it is heated by the feed heat exchanger B24 and then enters the isomerization reactor 25. The reaction occurs in the isomerization reactor 25 at a temperature of 130-220℃ and a pressure of 2.9-3.5MPaG. After the reaction, the material is heated by the feed heat exchanger B24 and then enters the isomerization stabilizer 26. The material at the top of the isomerization stabilizer 26 is condensed by the stabilizer top condenser B27 and then enters the stabilizer reflux tank B28. The gas phase at the top of the tank is isomerized dry gas, and the liquid phase at the bottom of the tank is pressurized by the stabilizer reflux pump B29 and returned to the isomerization stabilizer 26 as reflux. The material at the bottom of the tower is cooled by the stabilizer bottom cooler 30 and then sent to the isobutane removal tower 15. The isomerization stabilizer 26 has a top temperature of 80-100℃ and a pressure of 1.9-2.2 MPaG, and a bottom temperature of 100-120℃ and a pressure of 2.0-2.3 MPaG. The amount of n-butane supplied and the isomerization ratio can be adjusted as needed.(5) The light components discharged from the reflux tank A12 of the hydrorefining stabilizer and the reflux tank B28 of the heterogeneous stabilizer, after being washed with alkali to remove impurities, can be used for dry gas compression, PSA unit or as fuel gas.

Claims

1. A C4 material refining apparatus, characterized in that, It includes a feed heat exchanger A (1), which is connected to the hydrogenation reactor (3) via a feed heater (2). The hydrogenation reactor (3) is connected to the stabilizer tower feed heat exchanger (9) via a discharge buffer tank (5). The stabilizer tower feed heat exchanger (9) is connected to the stabilizer tower (10). The stabilizer tower (10) is connected to the deisobutane tower (15) via a connecting pipe (34). The deisobutane tower (15) is connected to the isomerization reactor (25) via a feed heat exchanger B (24).

2. The C4 material refining apparatus according to claim 1, characterized in that, The feed heat exchanger A (1) is connected to a feed pipe (32). The hydrogenation reactor (3) is connected to the discharge buffer tank (5) through the feed heat exchanger A (1). A discharge cooler (4) is provided between the feed heat exchanger A (1) and the discharge buffer tank (5). The discharge buffer tank (5) is connected to the circulating hydrogen compressor (7) through the circulating hydrogen compressor inlet buffer tank (6). The circulating hydrogen compressor (7) is connected to the feed pipe (32) through the circulating hydrogen compressor outlet buffer tank (8).

3. The C4 material refining apparatus according to claim 1, characterized in that, The stabilizer tower (10) is connected to the stabilizer tower reflux tank A (12) above the stabilizer tower top condenser A (11), the stabilizer tower reflux tank A (12) is connected to the stabilizer tower (10) through the stabilizer tower reflux pump A (13), and the stabilizer tower reboiler A (14) is connected below the stabilizer tower (10).

4. The C4 material refining apparatus according to claim 1, characterized in that, The stabilizer tower (10) is connected to the deisobutane tower (15) through the stabilizer tower feed heat exchanger (9). A connecting pipe (34) is provided between the stabilizer tower feed heat exchanger (9) and the deisobutane tower (15), and a dehydrogenation device pipe (33) is connected to the connecting pipe (34).

5. The C4 material refining apparatus according to claim 1, characterized in that, The isobutane removal tower (15) is connected to the heat pump compressor inlet buffer tank (16) via a pipe. The heat pump compressor inlet buffer tank (16) is connected to the isobutane removal tower reboiler (21) via the heat pump compressor (17). The isobutane removal tower reboiler (21) is connected to the heat pump compressor inlet buffer tank (16) via the heat pump compressor outlet cooler (18). The heat pump compressor inlet buffer tank (16) is connected to the isobutane removal tower (15) via the isobutane removal tower reflux pump (19). A product delivery pump (20) is connected to the heat pump compressor inlet buffer tank (16). The heat pump compressor (17) is connected to the heat pump compressor outlet cooler (18) via a pipe.

6. The C4 material refining apparatus according to claim 1, characterized in that, The feed heat exchanger B (24) is connected to the heterogeneous stabilizer (26) via a pipeline. The heterogeneous stabilizer (26) is connected to the stabilizer reflux tank B (28) via the stabilizer top condenser B (27). The stabilizer reflux tank B (28) is connected to the heterogeneous stabilizer (26) via the stabilizer reflux pump B (29). The stabilizer reboiler B (31) is connected below the heterogeneous stabilizer (26). The heterogeneous stabilizer (26) is connected to the connecting pipeline (34) via the stabilizer bottom cooler (30). The bottom of the isomerization reactor (25) is connected to the feed heat exchanger B (24) via a pipeline. The bottom of the deisobutane tower (15) is connected to the C5+ heavy component cooler (23) via the C5+ heavy component external pump (22).

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