Anti-coking device for large oil gas line of catalytic cracking reactor

Abstract

The utility model belongs to the technical field of large oil-gas line anti-coking devices, and particularly relates to a large oil-gas line anti-coking device of a catalytic cracking reactor. The anti-coking device for the large oil-gas line of the catalytic cracking reactor comprises an inner extending pipe, the inner extending pipe penetrates through the pipe wall of the large oil-gas line, the inner extending pipe is connected with an annular pipe through a flange fastener, the annular pipe is provided with a self-cleaning fan-shaped nozzle, and the annular pipe is fixedly connected to the inner wall of the large oil-gas line through a pipe frame; and outside the large oil-gas line pipeline, the inner extending pipe is connected with a steam pipeline through a steam inlet flange. According to the anti-coking device for the large oil-gas line of the catalytic cracking reactor, the self-cleaning fan-shaped nozzles are arranged, fan-shaped steam is sprayed out to form a protective layer on the inner wall of the large oil-gas line, the flow speed is increased, oil-gas staying is reduced, pressure division and coking prevention are achieved, meanwhile, the device can be arranged in a combined relay mode, and the device is suitable for key coking parts such as elbows and the like. And an anti-backflow check valve and a monitoring pressure gauge are arranged externally, so that the structure is reliable, and the anti-coking effect is good.

Description

Technical Field

[0001] This utility model belongs to the technical field of anti-coking devices for large oil and gas pipelines, specifically relating to an anti-coking device for a large oil and gas pipeline in a catalytic cracking reactor. Background Technology

[0002] Catalytic cracking is the most important method for converting heavy oil into lighter oil in my country. Coking in the reaction system during the operation of catalytic cracking units is a major factor affecting the long-term operation of production units. During unit shutdown and maintenance, it was found that the main oil and gas pipeline from the top outlet of the reactor to the inlet of the fractionation tower was severely coked, with a coking thickness of tens of millimeters. This was particularly noticeable at the bends of the main oil and gas pipeline and near the inlet of the fractionation tower. The presence of coke reduces the effective flow area of ​​the pipeline, increases the pressure drop of the catalytic cracking system, and reduces the pressure at the top of the fractionation tower, thus causing the inlet pressure of the gas compressor to be lower than the normal value. This not only increases energy consumption, but also makes it detrimental to the stable operation of the system if the gas compressor operates off-point for a long time. The main reasons for coking in large oil and gas pipelines are as follows: poor raw material properties, which easily lead to condensation reactions and the formation of coke at high temperatures; low oil and gas pipeline velocity, generally below 35 m / s, making it very easy for oil and gas to coke on the pipeline wall; large temperature drop in the oil and gas pipeline or local cold spots, causing the high-temperature oil and gas products to cool down during flow, and the high-boiling-point components to condense into droplets that adhere to the pipeline wall, easily undergoing condensation to form coke particles, which then further accumulate.

[0003] CN220246026U discloses an anti-coking and wall-cleaning structure for oil and gas pipelines, employing a non-contact magnetic drive wall-cleaning design. End caps are installed at both ends of the oil and gas pipeline, with an internal isolation tube running through it. A cleaning section consisting of a collar, a cleaning ring, and a first magnet is installed outside the isolation tube, while a second magnet is installed inside the isolation tube. The two are magnetically attracted, and an external driving device drives the second magnet to reciprocate within the isolation tube, thereby driving the cleaning section to move along the outer wall of the isolation tube. The cleaning ring adheres to the inner wall of the oil and gas pipeline to scrape away coking. This structure has minimal impact on the pipeline's internal space, ensuring adequate ventilation. Furthermore, the use of two connected magnets reduces the amount of internal structure required within the oil and gas pipeline, while maintaining a sealed section of the isolation tube within the pipeline. However, the magnetic attraction force is affected by distance and temperature; the magnetic force may weaken at high temperatures, leading to insufficient coking removal power, and the effect on coking at locations such as bends is limited.

[0004] Therefore, it is necessary to further design the anti-coking device for large oil and gas pipelines, optimize the structure of the anti-coking device, and achieve the cleaning of key coking areas such as bends, so as to provide strong support for the long-term, safe and stable operation of catalytic cracking units. Utility Model Content

[0005] The purpose of this invention is to overcome the defects of the existing technology and provide a coking prevention device for the large oil and gas pipeline of a catalytic cracking reactor. By setting a self-cleaning fan-shaped nozzle on the annular structure, fan-shaped steam is sprayed out to form a protective layer on the inner wall of the large oil and gas pipeline, thereby increasing the flow rate, reducing oil and gas retention, and preventing coking by partial pressure. At the same time, the device can be arranged in combination and relay, and is suitable for key coking areas such as elbows. It is equipped with an anti-backflow check valve and a pressure monitoring gauge. The structure is reliable and the anti-coking effect is good.

[0006] The anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor described in this utility model consists of two parts: an inner part and an outer part of the large oil and gas pipeline. The two parts are connected by an inner extension pipe that penetrates the wall of the large oil and gas pipeline. Inside the large oil and gas pipeline, the inner extension pipe is connected to an annular pipe via flange fasteners. The annular pipe is equipped with self-cleaning fan-shaped nozzles and is fixedly connected to the inner wall of the large oil and gas pipeline by a pipe bracket. Outside the large oil and gas pipeline, the inner extension pipe is connected to a steam pipeline via a steam inlet flange. A pressure gauge is installed on the steam pipeline, and a check valve is installed upstream of the pressure gauge.

[0007] Preferably, the annular tube is composed of two semi-annular tubes, which are connected by a butt flange to realize the disassembly and assembly of the annular tube.

[0008] Preferably, each semi-annular pipe is uniformly provided with three self-cleaning fan-shaped nozzles, and the self-cleaning fan-shaped nozzles are connected to the semi-annular pipes by threaded connection. Furthermore, the nozzle opening of the self-cleaning fan-shaped nozzles is parallel to the axis of the main oil and gas pipeline and consistent with the material flow direction within the main oil and gas pipeline.

[0009] Preferably, the annular tube is evenly connected with three tube supports. Further, the tube supports are composed of fixed angle steel and U-bolts. One end of the fixed angle steel is connected to the inner wall of the large oil and gas pipeline, and the other end is connected to the U-bolt through the pre-set connection hole of the fixed angle steel. The U-bolt stably clamps and fixes the annular tube to the fixed angle steel.

[0010] Specifically, the anti-coking device for the large oil-gas pipeline of the catalytic cracking reactor is installed and operates as follows: The anti-coking device is made of 321H stainless steel. A DN40 inner extension pipe is installed through the pipe wall of the large oil-gas pipeline. The outer side of the inner extension pipe is connected to the steam pipeline, and the inner side is connected to the annular pipe via flange fasteners. The annular pipe is fixedly connected to the inner wall of the large oil-gas pipeline via a pipe rack. Self-cleaning fan-shaped nozzles are installed on the annular pipe. Steam from the steam pipeline enters the annular pipe through the inner extension pipe and is finally ejected through the self-cleaning fan-shaped nozzles. The nozzle openings of the self-cleaning fan-shaped nozzles are adjusted to be parallel to the axis of the large oil-gas pipeline, spraying a fan-shaped steam near the pipe wall. Six fan-shaped steam jets are sprayed through the six self-cleaning fan-shaped nozzles on the annular pipe, forming a rapidly flowing steam protective layer along the inner wall of the large oil-gas pipeline. This improves the oil-gas velocity at the inner wall of the large oil-gas pipeline and reduces the adhesion of oil and gas to the pipe wall. The short residence time and the steam's temperature further prevent material condensation and adhesion to the pipe wall, effectively avoiding the long-term accumulation and coking of oil droplets on the inner wall. For easy installation at bends, the annular pipe consists of two semi-annular pipes connected by a flange. The self-cleaning fan-shaped nozzle has a self-cleaning function during operation. The control valve core inside the nozzle controls the nozzle area. When foreign objects block the nozzle, the pressure inside the nozzle automatically increases, opening the built-in spring and increasing the nozzle diameter. After automatically expelling the foreign objects, the nozzle diameter automatically returns to normal spraying. A pressure gauge is installed on the steam pipeline to monitor the operation of the anti-coking device. If the pressure gauge reading exceeds the pressure of the main oil-gas line by a large margin, it indicates a blockage in the anti-coking device, requiring attention and measures to clear it. A check valve is installed upstream of the pressure gauge at each anti-coking device site to prevent oil and gas from flowing back into the steam network from the main oil-gas line.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: The anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor, by setting a self-cleaning fan-shaped nozzle on the annular pipe structure, sprays fan-shaped steam to form a protective layer on the inner wall of the large oil and gas pipeline, which increases the oil and gas flow rate, reduces oil and gas retention, and lowers the oil and gas partial pressure, further preventing material condensation and adhesion to the pipe wall, thus avoiding coking from the source. There is no need to stop production regularly to clean the coking, ensuring production efficiency. At the same time, this device has a detachable structure, is easy to install, and is suitable for key coking areas such as elbows. It is equipped with an external anti-backflow check valve and a monitoring pressure gauge, making it reliable in structure and effective in preventing coking. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the anti-coking device for the large oil and gas pipeline in the catalytic cracking reactor of this utility model.

[0013] Figure 2This is a cross-sectional view along line AA of the anti-coking device for the large oil and gas pipeline in the catalytic cracking reactor of this utility model.

[0014] Figure 3 This is a schematic diagram of the anti-coking device for the main oil and gas pipeline of the catalytic cracking reactor installed at the bend of the main oil and gas pipeline in this utility model.

[0015] In the diagram: 1. Steam inlet flange; 2. Inner extension pipe; 3. Flange fastener; 4. Semi-ring pipe; 5. Pipe rack; 501. Fixed angle steel; 502. U-bolt; 6. Butt flange; 7. Self-cleaning fan-shaped nozzle; 8. Main oil and gas line; 9. Pressure gauge; 10. Check valve; 11. Steam pipeline. Detailed Implementation

[0016] The present invention will be further described below with reference to the accompanying drawings.

[0017] like Figure 1-3 As shown, the anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor includes an inner extension pipe 2, an annular pipe, and a self-cleaning fan-shaped nozzle 7. The inner extension pipe 2 penetrates the wall of the large oil and gas pipeline 8 and is connected to the annular pipe inside the large oil and gas pipeline 8 by a flange fastener 3. The annular pipe is equipped with a self-cleaning fan-shaped nozzle 7 and is fixedly connected to the inner wall of the large oil and gas pipeline 8 by a pipe bracket 5. The inner extension pipe 2 is connected to a steam pipeline 11 outside the steam inlet flange 1. A pressure gauge 9 is installed on the steam pipeline 11, and a check valve 10 is installed upstream of the pressure gauge 9.

[0018] The annular tube is composed of two semi-annular tubes 4, which are connected by a butt flange 6. Three self-cleaning fan-shaped nozzles 7 are evenly arranged on the semi-annular tubes 4, and the self-cleaning fan-shaped nozzles 7 are connected to the semi-annular tubes 4 by threaded connection.

[0019] The annular pipe is evenly connected with three pipe supports 5. The pipe supports 5 are composed of fixed angle steel 501 and U-bolts 502. One end of the fixed angle steel 501 is connected to the inner wall of the large oil and gas line 8, and the other end is connected to the U-bolt 502 through the pre-set connection hole of the fixed angle steel 501. The U-bolt 502 stably clamps and fixes the annular pipe to the fixed angle steel 501.

[0020] The anti-coking device for the large oil-gas pipeline of the catalytic cracking reactor operates as follows: The device is made of 321H stainless steel. A DN40 inner extension pipe 2 is installed through the pipe wall of the large oil-gas pipeline 8. The outer side of the inner extension pipe 2 is connected to the steam pipeline 11, and the inner side of the inner extension pipe 2 is connected to an annular pipe via flange fasteners 3. The annular pipe is fixedly connected to the inner wall of the large oil-gas pipeline 8 via a pipe bracket 5. Self-cleaning fan-shaped nozzles 7 are installed on the annular pipe. Steam from the steam pipeline 11 enters the annular pipe through the inner extension pipe 2 and is finally ejected through the self-cleaning fan-shaped nozzles 7. The nozzle openings of the self-cleaning fan-shaped nozzles 7 are adjusted to be parallel to the axis of the large oil-gas pipeline 8, spraying a fan-shaped steam near the pipe wall of the large oil-gas pipeline 8. Six fan-shaped steam jets are sprayed through the six self-cleaning fan-shaped nozzles 7 on the annular pipe, forming a rapidly flowing steam protective layer along the inner wall of the large oil-gas pipeline 8. This improves the oil-gas velocity at the inner wall of the large oil-gas pipeline 8 and reduces the oil-gas velocity near the pipe wall. The residence time, and the steam's temperature, further prevent material condensation and adhesion to the pipe wall, effectively avoiding the long-term accumulation and coking of oil droplets on the inner wall. For easy installation at bends, the annular pipe consists of two semi-annular pipes 4 connected by a connecting flange 6. The self-cleaning fan-shaped nozzle 7 has a self-cleaning function during operation. The control valve core inside the self-cleaning fan-shaped nozzle 7 controls the nozzle area. When foreign objects block the nozzle, the pressure inside the nozzle automatically increases, opening the built-in spring and increasing the nozzle diameter. After automatically discharging the foreign objects, the nozzle diameter automatically returns to normal spraying. Simultaneously, a pressure gauge 9 is installed on the steam pipeline 11 to monitor the operating status of the anti-coking device. If the pressure gauge 9 indicates a pressure exceeding the pressure of the main oil-gas line 8 by a large margin, it indicates a blockage in the anti-coking device, requiring attention and measures to clear it. A check valve 10 is installed upstream of the pressure gauge 9 at each anti-coking device site to prevent oil and gas from flowing back into the steam pipeline network from the main oil-gas line 8. Figure 3 As shown, when this device is applied to the large oil and gas pipeline, anti-coking devices are installed upstream and downstream of the bend to ensure the continuity of materials and steam within the large oil and gas pipeline 8.

Claims

1. A coking prevention device for a large oil and gas pipeline in a catalytic cracking reactor, comprising an inner extension pipe (2), an annular pipe, and a self-cleaning fan-shaped nozzle (7), characterized in that, The inner extension pipe (2) penetrates the wall of the main oil and gas line (8). The inner extension pipe (2) is connected to the annular pipe inside the main oil and gas line (8) through a flange fastener (3). The annular pipe is equipped with a self-cleaning fan-shaped nozzle (7). The annular pipe is fixedly connected to the inner wall of the main oil and gas line (8) through a pipe rack (5). The outer side of the inner extension pipe (2) is connected to the steam pipeline (11) through a steam inlet flange (1).

2. The anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor according to claim 1, characterized in that, The annular pipe is composed of two semi-annular pipes (4), which are connected by a butt flange (6). Three pipe supports (5) are evenly connected around the annular pipe.

3. The anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor according to claim 2, characterized in that, Three self-cleaning fan-shaped nozzles (7) are evenly arranged on the semi-annular tube (4), and the self-cleaning fan-shaped nozzles (7) are connected to the semi-annular tube (4) by a threaded connection.

4. The anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor according to claim 2, characterized in that, The pipe rack (5) consists of a fixed angle steel (501) and a U-bolt (502). One end of the fixed angle steel (501) is connected to the inner wall of the large oil and gas line (8), and the other end is connected to the U-bolt (502) through the pre-set connection hole of the fixed angle steel (501). The U-bolt (502) stably clamps and fixes the annular pipe to the fixed angle steel (501).

5. The anti-coking device for the large oil and gas pipeline of the catalytic cracking reactor according to claim 1, characterized in that, A pressure gauge (9) is installed on the steam pipeline (11), and a check valve (10) is installed upstream of the pressure gauge (9).

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