Light component recovery system in catalytic cracking device

Abstract

The utility model belongs to the technical field of catalytic cracking devices, and particularly relates to a light component recovery system in a catalytic cracking device. The light component recovery system in the catalytic cracking device comprises an inlet oil-gas separator, the inlet oil-gas separator is connected with an aerostatic press, the aerostatic press is connected with an outlet oil-gas separator through an air cooling device and a water cooling device in sequence, the top of the outlet oil-gas separator is connected with an inlet in the lower portion of an absorption tower, and the top of the absorption tower is connected with an inlet in the lower portion of the absorption tower. Non-condensable steam at the top of the absorption tower is connected with the re-absorption tower through a pipeline, the bottom of the outlet oil-gas separator is connected with the desorption tower, and the bottom of the desorption tower is connected with the stabilization tower. The light component recovery system in the catalytic cracking device is provided, and the reasonable design of the system ensures that the normal operation of the device is not influenced after an external light component medium is introduced into the catalytic cracking device, the surplus capacity of the device can be fully utilized, the problem of waste caused by pressure relief of a high value-added medium to a torch system is avoided, and the processing benefit of the device is increased.

Description

Technical Field

[0001] This utility model belongs to the technical field of catalytic cracking equipment, specifically relating to a light component recovery system in a catalytic cracking equipment. Background Technology

[0002] In the petrochemical industry, gasoline hydrotreating units, alkylation units, and gas separation units are crucial production units. Gasoline hydrotreating units effectively reduce the sulfur content and other impurities in gasoline through hydrogenation, meeting increasingly stringent environmental standards and technical requirements, thereby improving gasoline quality. Alkylation units primarily convert C4 light hydrocarbons into high-octane gasoline components, such as isoalkanes, playing an indispensable role in improving gasoline quality and increasing its octane rating. Gas separation units, also known as liquefied petroleum gas (LPG) gas separation units, are mainly used to separate propane, propylene, and C4 components from liquefied petroleum gas (LPG).

[0003] However, during the production process of these units, some depressurized gas is inevitably generated, and this depressurized gas contains a large amount of liquefied petroleum gas (LPG) components. For example, the acid gas from the gasoline hydrotreating unit, the hydrogen-rich fuel gas from the alkylation unit, and the C2 non-condensable gas from the gas separation unit all contain significant amounts of LPG components. Currently, there are two common methods for handling this depressurized gas: one is to directly depressurize it and burn it through a flare system; the other is to recover this gas phase through a combined unit. However, the first method leads to the loss of high-value-added products, resulting in resource waste; while the second method achieves recovery to some extent, combined unit recovery also suffers from high costs and limited recovery efficiency, failing to fully realize efficient resource utilization and maximize economic benefits.

[0004] CN218710198U discloses a gasoline hydrogenation exhaust gas treatment device, which includes a gasoline hydrogenation fractionation tower, a reflux tank at the top of the fractionation tower, and a coking unit. The coking unit includes an oil-gas separator, a cooling liquid separator, an absorption tower, a re-absorption tower, and a dry gas desulfurization tower connected in sequence by pipelines. The absorption tower can absorb most of the C3 and above hydrocarbon components in the exhaust gas with a high absorption rate. The purified dry gas at the end of the device can be used as a raw material for a hydrogen production unit, which greatly reduces the waste of hydrocarbon and hydrogen resources and has broad market application prospects. However, this device is only for exhaust gas from gasoline hydrogenation units and cannot treat mixed exhaust gas from multiple units. It mainly focuses on hydrocarbons and hydrogen, and other high-value-added light components are not fully utilized, which limits the space for improving the overall resource utilization efficiency and economic benefits.

[0005] In conclusion, it is of great significance to find ways to more effectively recover light components such as liquefied gas generated by production equipment, reduce the loss of high value-added products, and improve resource utilization efficiency and economic benefits. Utility Model Content

[0006] The purpose of this invention is to overcome the defects of the existing technology and provide a light component recovery system in a catalytic cracking unit. The rational design of this system ensures that the introduction of external light component media into the catalytic cracking unit will not affect the normal operation of the unit, and can make full use of the unit's surplus capacity. It avoids the problem of waste caused by the depressurization of high value-added media to the flare system, and increases the processing efficiency of the unit.

[0007] The light component recovery system in the catalytic cracking unit of this utility model includes an inlet oil-gas separator. The outlet of the inlet oil-gas separator is connected to a gas compressor, which is connected to the outlet oil-gas separator in sequence through an air-cooling device and a water-cooling device. The top of the outlet oil-gas separator is connected to the lower inlet of the absorption tower, and the non-condensable vapor at the top of the absorption tower is connected to the reabsorption tower through a pipeline. The bottom of the outlet oil-gas separator is provided with a pipeline connected to the desorption tower, and the bottom outlet of the desorption tower is provided with a pipeline connected to the inlet of the stabilization tower. The bottom of the stabilization tower is provided with a pipeline connected to a cooling device, which is connected to the gasoline refining unit through a pipeline. The inlet oil-gas separator is provided with a feed inlet, which is connected to an oil-gas pipeline and a pressure relief gas pipeline.

[0008] Preferably, the bottom of the oil-gas separator is provided with an acidic water outlet for discharging acidic wastewater generated after cooling.

[0009] Preferably, in the imported oil-gas separator, the feed inlet pipeline extends into the interior of the imported oil-gas separator and is lower than the liquid level inside the imported oil-gas separator, further reducing the amount of liquid carried by the gas phase. A dehydration bag is provided at the bottom of the imported oil-gas separator, and the acidic water accumulated in the dehydration bag is sent out through the pipeline.

[0010] Preferably, a mesh demister is provided on the inner side wall corresponding to the discharge port of the inlet oil-gas separator. The mesh demister is composed of a foam net and a grid. The foam net is pressed and fixed to the upper part of the grid. The side and bottom surfaces of the mesh demister can be used to separate the oil phase and the gas phase.

[0011] Preferably, the absorption tower is provided with crude gasoline inlets at both the upper and lower parts, which are connected to crude gasoline pipeline I and crude gasoline pipeline II respectively, and a pipeline for return to the water cooling device is provided at the bottom of the absorption tower.

[0012] Preferably, the upper part of the reabsorption tower is connected to the lean absorber oil pipeline, and the bottom is provided with a pipeline connected to the downstream heat exchange device.

[0013] Preferably, the top of the desorption tower is provided with a pipeline for reflux to the air cooling device.

[0014] Preferably, the top of the stabilization tower is provided with a pipeline connected to the top reflux tank, and a cooling device is provided on the pipeline. The top reflux tank is provided with a pipeline connected to the liquefied gas pipeline network. An acidic water outlet is provided on one side of the bottom of the top reflux tank. A reflux pipeline is provided on the other side of the bottom of the top reflux tank. The reflux pipeline is divided into two paths, one of which returns to the stabilization tower and the other is connected to the desulfurization device.

[0015] Preferably, the cooling device is equipped with a stable gasoline pipeline, which delivers stable gasoline to the top of the absorption tower.

[0016] Specifically, the pressure relief pipeline consists of four gas pipelines connected in parallel, with the gas sources for each pipeline being: acid gas from the gasoline hydrogenation unit, sulfur-containing light hydrocarbons from the diesel mild cracking unit, hydrogen-rich fuel gas from the alkylation unit, and C2 noncondensable gas from the gas separation unit.

[0017] The light component recovery system in the catalytic cracking unit operates as follows: Depressurized exhaust gas from upstream units and oil / gas from the fractionation tower are transported via depressurized gas pipelines and oil / gas pipelines. These two pipelines are connected in parallel and enter the inlet oil / gas separator for separation. In the inlet oil / gas separator, the liquid phase is crude gasoline, and the gas phase consists of liquefied petroleum gas (LPG), C2, and other components. Simultaneously, acidic water is generated in the dehydration tank and is discharged via pipeline. The gas phase components pass through a mesh demister at the top of the inlet oil / gas separator and into a compressor for compression. The compressed gas phase is further cooled by air and water cooling devices before entering the outlet oil / gas separator for further separation. The separated gas phase, containing LPG, C2, and other components, enters an absorption tower for absorption. To further absorb the effective components, crude gasoline and stabilized gasoline are introduced into the absorption tower to ensure absorption. The absorption process is as follows: the heavy components are returned to the water-cooling unit for further separation, while the unabsorbed gas phase enters the reabsorption tower. Lean absorbent oil is introduced into the reabsorption tower for further gas phase absorption until almost no usable components remain. The resulting gas is then discharged from the top of the tower to the desulfurization unit for desulfurization. The absorbent oil produced at the bottom of the reabsorption tower is transported to the downstream heat exchange unit, cooled, and recycled. The gasoline and other fractions separated by the outlet oil-gas separator are transported in two routes to different trays of the desorption tower to achieve better desorption. The gas phase produced after desorption is recycled to the air-cooling unit, and the oil fraction produced at the bottom of the tower is cooled and transported to the stabilization tower. A top reflux tank is installed at the top of the stabilization tower to transport the generated liquefied gas to the liquefied gas pipeline network. The gasoline produced at the bottom of the stabilization tower is cooled and transported to the gasoline refining unit. At the same time, the gasoline produced in the stabilization tower is also transported to the absorption tower through the stabilized gasoline pipeline to ensure the stable operation of the entire unit.

[0018] The beneficial effects of this utility model are as follows: By rationally designing the light component absorption process, it is ensured that the introduction of external light component media into the catalytic cracking unit will not affect the normal operation of the unit, making full use of the unit's surplus capacity, avoiding the waste caused by high-value-added media being depressurized to the flare system, and increasing the unit's processing efficiency; at the same time, the oil-gas separator device has been rationally designed to further reduce the amount of liquid carried in the gas phase, ensuring the quality of the gas phase entering the gas compressor and reducing the risk of equipment damage and failure. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the light component recovery system in the catalytic cracking unit of this utility model;

[0020] Figure 2 This is a schematic diagram of the imported oil-gas separator described in this utility model;

[0021] Figure 3 This is a schematic diagram of the structure of the mesh demister in the imported oil-gas separator described in this utility model.

[0022] In the diagram: 1. Inlet oil-gas separator; 101. Feed inlet; 102. Discharge outlet; 103. Dehydration bag; 104. Mesh demister; 1041. Grille; 1042. Foam net; 2. Air compressor; 3. Outlet oil-gas separator; 4. Absorption tower; 5. Reabsorption tower; 6. Desorption tower; 7. Stabilizer tower; 8. Top reflux tank; 9. Oil-gas pipeline; 10. Pressure relief pipeline; 11. Air cooling unit; 12. Water cooling unit; 13. No. I crude gasoline pipeline; 14. Stabilized gasoline pipeline; 15. No. II crude gasoline pipeline; 16. Downstream heat exchange unit; 17. Lean absorbent oil pipeline; 18. Gasoline refining unit; 19. Desulfurization unit; 20. Liquefied gas pipeline network; 21. Cooling unit. Detailed Implementation

[0023] The technical solution proposed by this utility model will be further explained below with reference to the accompanying drawings.

[0024] like Figures 1-3As shown, the light component recovery system in the catalytic cracking unit includes an inlet oil-gas separator 1, a gas compressor 2, and an outlet oil-gas separator 3. The inlet oil-gas separator 1 is provided with a feed inlet 101 and a discharge outlet 102. The feed inlet 101 is connected to a pressure relief gas pipeline 10, and the discharge outlet 102 is connected to the gas compressor 2. The gas compressor 2 is connected to the outlet oil-gas separator 3 in sequence through an air-cooling device 11 and a water-cooling device 12. The top of the outlet oil-gas separator 3 is connected to the lower inlet of the absorption tower 4, and the non-condensable vapor at the top of the absorption tower 4 is connected to the reabsorption tower 5 through a pipeline. The bottom of the outlet oil-gas separator 3 is provided with a pipeline connected to the desorption tower 6, and the bottom outlet of the desorption tower 6 is provided with a pipeline connected to the inlet of the stabilization tower 7. The bottom of the stabilization tower 7 is provided with a pipeline connected to a cooling device 21, and the cooling device 21 is connected to the gasoline refining unit 18 through a pipeline.

[0025] The feed inlet 101 of the imported oil-gas separator 1 is connected to the oil-gas pipeline 9. The pipeline at the feed inlet 101 extends into the interior of the imported oil-gas separator 1 and is lower than the liquid level inside the imported oil-gas separator 1. A dehydration bag 103 is provided at the bottom of the imported oil-gas separator 1. The acidic water accumulated in the dehydration bag 103 is sent out through the pipeline.

[0026] On the inner side wall corresponding to the discharge port 102 of the imported oil-gas separator 1, a mesh demister 104 is provided. The mesh demister 104 is composed of a foam net 1042 and a grid 1041. The foam net 1042 is pressed and fixed to the upper part of the grid 1041. The side and bottom surfaces of the mesh demister 104 can be used to separate the oil phase and the gas phase.

[0027] The absorption tower 4 is equipped with crude gasoline inlets at both the upper and lower parts of the tower body, which are connected to crude gasoline pipeline 13 (No. I) and crude gasoline pipeline 15 (No. II) respectively. A pipeline for return flow to water cooling device 12 is provided at the bottom of the absorption tower 4.

[0028] The upper part of the reabsorption tower 5 is connected to the lean absorption oil pipeline 17, and the bottom is provided with a pipeline connected to the downstream heat exchange device 16.

[0029] The top of the desorption tower 6 is equipped with a pipeline for reflux to the air cooling device 11.

[0030] The top of the stabilizer tower 7 is equipped with a pipeline connected to the top reflux tank 8, and a cooling device 21 is installed on the pipeline. The top reflux tank 8 is equipped with a pipeline connected to the liquefied gas pipeline network 20. An acidic water outlet is provided on one side of the bottom of the top reflux tank 8. A reflux pipeline is provided on the other side of the bottom of the top reflux tank 8. The reflux pipeline is divided into two paths, one of which returns to the stabilizer tower 7 and the other is connected to the desulfurization device 19.

[0031] The cooling device 21 is equipped with a stable gasoline pipeline 14, which delivers stable gasoline to the top of the absorption tower 4.

[0032] The light component recovery system in the catalytic cracking unit operates as follows: Depressurized exhaust gas from upstream units and oil / gas from the fractionation tower are transported via depressurized gas pipeline 10 and oil / gas pipeline 9. These two pipelines are connected in parallel and enter the inlet oil / gas separator 1 through inlet 101 for separation. In the inlet oil / gas separator 1, the liquid phase is crude gasoline, and the gas phase consists of liquefied petroleum gas, C2, and other components. Simultaneously, acidic water is generated in the dehydration chamber 103, which is then discharged via pipeline. The gas phase components pass through the inlet oil / gas separator... The mesh demister 104 at the top of separator 1 and the discharge port 102 enter the air compressor 2 for compression. The compressed gas phase is further cooled by the air cooling device 11 and the water cooling device 12, and then enters the outlet oil-gas separator 3 for further separation. The separated gas phase containing liquefied gas, C2 and other components enters the absorption tower 4 for absorption. In order to further absorb the effective components, crude gasoline transported by crude gasoline pipeline I 13 and crude gasoline pipeline II 15, as well as stabilized gasoline transported by stabilized gasoline pipeline 14, need to be introduced into the absorption tower 4. The gasoline is kept constant to ensure absorption efficiency. The absorbed heavy components are returned to the water-cooling unit 12 for further separation. The unabsorbed gas phase enters the reabsorption tower 5. Lean absorption oil, supplied by the lean absorption oil pipeline 17, is introduced into the reabsorption tower 5 for further gas phase absorption until almost no usable components remain. The resulting gas is discharged from the top of the tower to the desulfurization unit 19 for desulfurization. The absorption oil produced at the bottom of the reabsorption tower 5 is transported to the downstream heat exchange unit 16 for cooling and recycling. The gasoline fractions separated by the outlet oil-gas separator 3 are transported in two routes to different trays of the desorption tower 6 to achieve better desorption. The gas phase produced after desorption is recycled to the air-cooling unit 11. The oil fraction produced at the bottom of the tower is cooled and transported to the stabilization tower 7. The top of the stabilization tower 7 is equipped with a top reflux tank 8 to transport the generated liquefied gas to the liquefied gas pipeline network 20. The gasoline produced at the bottom of the stabilization tower 7 is cooled by the cooling unit 21 and then transported to the gasoline refining unit 18. At the same time, the gasoline produced by the stabilization tower 7 is also transported to the absorption tower 4 through the stabilized gasoline pipeline 14 to ensure the stable operation of the entire unit.

Claims

1. A light ends recovery system in a catalytic cracking unit, characterized by, The device comprises an import oil-gas separator (1), an air compressor (2), and an export oil-gas separator (3). The import oil-gas separator (1) is provided with a feeding port (101) and a discharging port (102). The feeding port (101) is connected with a pressure relief gas pipeline (10), and the discharging port (102) is connected with the air compressor (2). The air compressor (2) is connected with the export oil-gas separator (3) through an air cooling device (11) and a water cooling device (12) in sequence. The top of the export oil-gas separator (3) is connected with a lower inlet of an absorption tower (4). The top of the absorption tower (4) is connected with a reabsorption tower (5) through a pipeline. The bottom of the export oil-gas separator (3) is provided with a pipeline connected with a desorption tower (6). The bottom outlet of the desorption tower (6) is provided with a pipeline connected with an inlet of a stabilizing tower (7). The bottom of the stabilizing tower (7) is provided with a pipeline connected with a cooling device (21). The cooling device (21) is connected with a gasoline refining device (18) through a pipeline.

2. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, The feeding port (101) of the import oil-gas separator (1) is connected with an oil-gas pipeline (9). The pipeline at the feeding port (101) extends into the import oil-gas separator (1) and is lower than the liquid level in the import oil-gas separator (1). The bottom of the import oil-gas separator (1) is provided with a dehydration bag (103). Acidic water accumulated in the dehydration bag (103) is discharged through a pipeline.

3. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, A mesh demister (104) is arranged on the corresponding inner side wall of the discharging port (102) of the import oil-gas separator (1). The mesh demister (104) is composed of a foamed mesh (1042) and a grid (1041). The foamed mesh (1042) is tightly fixed on the upper part of the grid (1041). The side surface and the bottom surface of the mesh demister (104) can be used for separating oil phase and gas phase.

4. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, The upper part and the lower part of the tower body of the absorption tower (4) are provided with crude gasoline inlets, which are connected with a No. I crude gasoline pipeline (13) and a No. II crude gasoline pipeline (15), respectively. The bottom of the absorption tower (4) is provided with a pipeline returning to the water cooling device (12).

5. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, The upper part of the tower body of the reabsorption tower (5) is connected with a lean absorption oil pipeline (17), and the bottom is provided with a pipeline connected with a downstream heat exchange device (16).

6. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, The top of the desorption tower (6) is provided with a pipeline returning to the air cooling device (11).

7. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, The top of the stabilizing tower (7) is provided with a pipeline connected with a tower top reflux tank (8). The pipeline is provided with a cooling device (21). The tower top reflux tank (8) is provided with a pipeline connected with a liquefied gas pipeline network (20). One side of the bottom of the tower top reflux tank (8) is provided with an acidic water discharge port. The other side of the bottom of the tower top reflux tank (8) is provided with a reflux pipeline, which is divided into two paths. One path returns to the stabilizing tower (7), and the other path is connected with a desulfurization device (19).

8. The light ends recovery system in a catalytic cracking unit of claim 1, wherein, The cooling device (21) is provided with a stable gasoline pipeline (14), which transports stable gasoline to the top of the absorption tower (4).

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