Dry gas seal protection system and method for compressor of slurry bed residual oil hydrogenation device

Abstract

The invention relates to the technical field of mechanical structures, and particularly discloses a slurry bed residual oil hydrogenation device compressor dry gas seal protection system which comprises a centrifugal compressor, a primary sealing structure, a secondary sealing structure and an isolation gas structure, and the centrifugal compressor is provided with a process gas inlet pipeline and a process gas outlet pipeline. And the first-stage sealing structure, the second-stage sealing structure and the air isolation structure are respectively communicated with the centrifugal compressor. Process gas output by a process gas outlet pipeline or nitrogen conveyed by an air separation device is used as first-stage sealing gas, the flow of the first-stage sealing gas is guaranteed, separation of a dynamic ring and a static ring of a dry gas seal is achieved, and shortening of the service life or damage of the dry gas seal caused by friction of the dynamic ring and the static ring is reduced or avoided; switching of the process gas and the nitrogen serving as the first-stage sealing gas is achieved, frequent starting and stopping of a booster pump for the first-stage sealing gas are avoided, and the service life is effectively prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical engineering, and in particular to a dry gas seal protection system and method for a compressor of a slurry bed residue oil hydrogenation device. Background Art

[0002] In the slurry bed residue oil hydrogenation unit, the circulating hydrogen compressor is one of the key equipment. The reliability of its sealing system directly affects the safe and stable operation of the compressor. The dry gas seal is a non-contact mechanical seal that relies on gas film lubrication. When working, the sealing gas is introduced through the dynamic pressure groove opened on the sealing end face, so that the two sealing end faces are separated by a stable thin gas film and are in a non-contact operating state. The dry gas seal is a sealing form with a higher adoption rate in the shaft seal of centrifugal compressor units.

[0003] In the normal production of the hydrogenation device of the prior art, the process gas at the outlet of the compressor is used as the gas source of the primary sealing gas. However, during the operation of the fracturing device, when the centrifugal compressor is started, since the pressure of the process gas is equal to the pressure in the machine body, a gas phase circulation must be established when the system pressure is low, resulting in failure to form a good gas film between several gas seal dynamic and static rings during the startup process, and failure to protect the dry gas seal. Instead, the dry gas seal will be damaged. For this reason, it is often necessary to pressurize the process gas by a booster pump, resulting in an increase in production costs. Each startup of the booster pump will reduce its service life, affecting the stability and safety of the dry gas sealing system.

[0004] Therefore, it is necessary to propose a compressor dry gas seal protection system and method for a slurry bed residue oil hydrogenation unit to overcome the defects of the prior art. Summary of the invention

[0005] The purpose of the present invention is to solve the problems in the prior art and to provide a compressor dry gas seal protection system and method for a slurry bed residue oil hydrogenation unit.

[0006] The technical solution of the present invention is: A dry gas sealing protection system for a compressor of a slurry bed residue oil hydrogenation device comprises a centrifugal compressor, which is provided with a process gas inlet pipeline and a process gas outlet pipeline, and also comprises a primary sealing structure, a secondary sealing structure and an isolation gas structure. The primary sealing structure comprises a high-pressure nitrogen gas source pipeline, a process medium gas source pipeline and a primary sealing gas pipeline. The primary sealing gas pipeline is connected to the centrifugal compressor, the primary sealing gas pipeline is connected to the process gas outlet pipeline through the process medium gas source pipeline, the high-pressure nitrogen gas source pipeline is connected to the primary sealing gas pipeline, a primary gas liquid separation buffer tank, a primary gas booster pump, a dry gas sealing filter and a primary sealing gas heater are sequentially arranged on the primary sealing gas pipeline, the secondary sealing structure comprises a secondary and isolation gas source pipeline and a secondary sealing gas pipeline, the secondary and isolation gas source pipeline is connected to the centrifugal compressor through the secondary sealing gas pipeline, the isolation gas structure comprises an isolation gas pipeline, one end of the isolation gas pipeline is connected to the secondary and isolation gas source pipeline, and the other end of the isolation gas pipeline is connected to the centrifugal compressor.

[0007] Preferably, a check valve, a regulating valve and a flow meter are also provided on the primary sealed air pipeline, and the check valve, the regulating valve and the flow meter are connected in series on the primary sealed air pipeline in sequence according to the air flow direction.

[0008] Preferably, a nitrogen booster pump, a high-pressure nitrogen buffer tank, a high-pressure nitrogen valve and a high-pressure nitrogen one-way valve are arranged in sequence on the high-pressure nitrogen gas source pipeline according to the gas flow direction. The number of high-pressure nitrogen valves is set to multiple, and multiple high-pressure nitrogen valves are connected in series on the high-pressure nitrogen gas source pipeline.

[0009] Preferably, a booster pump cross-line valve is also provided on the high-pressure nitrogen gas source pipeline, and the booster pump cross-line valve is connected in parallel with the nitrogen booster pump.

[0010] Preferably, a plurality of process gas sealing isolation valves and process gas sealing one-way valves are sequentially arranged on the process medium gas source pipeline according to the gas flow direction.

[0011] Preferably, an air separation device is also included, and the secondary and isolation gas source pipelines and the high-pressure nitrogen gas source pipeline are all connected to the air separation device.

[0012] A dry gas seal protection method for a compressor of a slurry bed residue oil hydrogenation unit is applied to the dry gas seal protection system for a compressor of a slurry bed residue oil hydrogenation unit described above, and the method comprises: The process gas output from the process gas outlet pipeline of the centrifugal compressor or the nitrogen delivered by the air separation unit is returned to the centrifugal compressor as the primary sealing gas, and the nitrogen delivered by the air separation unit is used as the secondary sealing gas and isolation gas.

[0013] Preferably, the selection principle of the primary sealing gas is determined by the starting pressure of the centrifugal compressor. When the starting pressure of the centrifugal compressor is close to or exceeds the pressure of the high-pressure nitrogen delivered after the air separation unit is pressurized, the high-pressure nitrogen is not used as the primary sealing gas source; when the centrifugal compressor starts normally or the pressure of the centrifugal compressor approaches the pressure of the high-pressure nitrogen source delivered after the air separation unit is pressurized as the system is pressurized, the primary sealing gas source should be switched from the high-pressure nitrogen to the process gas output from the process gas outlet pipeline.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. By connecting the process gas outlet pipeline and the high-pressure nitrogen gas source pipeline to the primary sealing gas pipeline, the process gas output from the process gas outlet pipeline or the nitrogen delivered by the air separation unit is used as the primary sealing gas. Before the centrifugal compressor is started to normal operation or shut down, the nitrogen provided by the air separation unit is used as the primary sealing gas to ensure the flow of the primary sealing gas, realize the separation of the dynamic and static rings of the dry gas seal, reduce or avoid the shortening or damage of the dry gas seal caused by the friction of the dynamic and static rings, and realize the switching of process gas and nitrogen as the primary sealing gas according to the body pressure of the centrifugal compressor, avoiding the frequent start and stop of the booster pump for the primary sealing gas, effectively extending the service life and reducing the use cost; 2. The liquid droplets in the process gas output from the process gas outlet pipeline are separated by the primary gas separation buffer tank, and then purified by the dry gas seal filter before entering the primary sealing end face of the dry gas seal protection system. The temperature of the primary sealing gas is automatically controlled by the primary sealing gas heater to prevent the light hydrocarbon components in the process gas from condensing into liquid and causing damage to the dry gas seal. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention.

[0016] Among them, 1. Centrifugal compressor; 2. Process gas inlet pipeline; 3. Process gas outlet pipeline; 4. High-pressure nitrogen gas source pipeline; 401. Nitrogen booster pump; 402. High-pressure nitrogen buffer tank; 403. High-pressure nitrogen valve; 404. High-pressure nitrogen check valve; 405. Booster pump cross-line valve; 5. Process medium gas source pipeline; 501. Process gas sealing isolation valve; 502. Process gas sealing check valve; 6. Primary sealing gas pipeline; 601. Primary gas gas liquid separation buffer tank; 602. Primary gas booster pump; 603. Dry gas sealing filter; 604. Primary sealing gas heater; 605. Check valve; 606. Regulating valve; 607. Flow meter; 7. Secondary and isolation gas source pipelines; 8. Secondary sealing gas pipeline; 9. Isolation gas pipeline; 10. Air separation unit. DETAILED DESCRIPTION

[0017] In order to make the technical means, technical features, invention objectives and technical effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific illustrations.

[0018] like Figure 1 As shown, a dry gas seal protection system for a compressor of a slurry bed residue oil hydrogenation unit is applied to a centrifugal compressor 1, and includes a primary seal structure, a secondary seal structure, an isolation gas structure and an air separation unit 10. The primary seal structure, the secondary seal structure and the isolation gas structure are respectively connected to the centrifugal compressor 1. The primary seal structure provides primary seal gas for the centrifugal compressor 1 to prevent the unclean gas inside the centrifugal compressor 1 from polluting the primary seal end face. The secondary seal structure provides secondary seal gas for the centrifugal compressor 1 to prevent a small amount of gas leaking from the primary seal end face from entering the secondary seal end face, thereby ensuring the safety and reliability of the secondary seal. The primary sealing structure and the secondary sealing structure are also connected to the air separation device 10, and the air separation device 10 provides nitrogen for the primary sealing structure and the secondary sealing structure. The isolation gas structure is used to prevent lubricating oil from entering the dry gas sealing system and contaminating the sealing surface. The centrifugal compressor 1 used in the present invention is a high-pressure centrifugal compressor 1, and its outlet pressure is greater than 9.8MPa. A process gas inlet pipeline 2 and a process gas outlet pipeline 3 are respectively installed at the inlet and outlet ends of the centrifugal compressor 1. The process gas inlet pipeline 2 is used to provide the centrifugal compressor 1 with a medium process gas that drives its operation, and the process gas is discharged through the process gas outlet pipeline 3 for recycling.

[0019] like Figure 1 As shown, the primary sealing structure uses process gas or high-pressure nitrogen as the primary sealing gas source. Specifically, the primary sealing structure includes a high-pressure nitrogen gas source pipeline 4, a process medium gas source pipeline 5 and a primary sealing gas pipeline 6. The outlet end of the primary sealing gas pipeline 6 is connected to the primary sealing end face of the centrifugal compressor 1, and the inlet end of the primary sealing gas pipeline 6 is connected to the process gas outlet pipeline 3 through the process medium gas source pipeline 5. At the same time, the outlet end of the high-pressure nitrogen gas source pipeline 4 is also connected to the inlet end of the primary sealing gas pipeline 6. The process medium gas source pipeline 5 provides process gas as the primary sealing gas to the centrifugal compressor 1 through the primary sealing gas pipeline 6, and the high-pressure nitrogen gas source pipeline 4 provides high-pressure nitrogen as the primary sealing gas to the centrifugal compressor 1 through the primary sealing gas pipeline 6. The selection of process gas and high-pressure nitrogen is switched according to the starting pressure of the centrifugal compressor 1.

[0020] like Figure 1As shown, a nitrogen booster pump 401, a high-pressure nitrogen buffer tank 402, a high-pressure nitrogen valve 403 and a high-pressure nitrogen check valve 404 are sequentially installed on the high-pressure nitrogen gas source pipeline 4 according to the flow direction of the gas. The number of high-pressure nitrogen valves 403 is multiple, and the multiple high-pressure nitrogen valves 403 are connected in series on the high-pressure nitrogen gas source pipeline 4 between the high-pressure nitrogen buffer tank 402 and the high-pressure nitrogen check valve 404. By adopting multiple high-pressure nitrogen valves 403, the tightness of the valve is protected, and the maintenance and repair of the pipeline are convenient to ensure safety and stability. The opening and closing of the high-pressure nitrogen valve 403 realizes the communication between the high-pressure nitrogen gas source pipeline 4 and the primary sealing gas pipeline 6. A booster pump cross-line valve 405 is also installed on the high-pressure nitrogen gas source pipeline 4. During installation, both ends of the booster pump cross-line valve 405 are connected in parallel to both ends of the nitrogen booster pump 401. According to the specific usage scenario, the nitrogen booster pump 401 or the booster pump cross-line valve 405 can be opened. The inlet end of the high-pressure nitrogen gas source pipeline 4 is connected to the air separation unit 10. The nitrogen provided by the air separation unit 10 can enter the high-pressure nitrogen buffer tank 402 for storage through the nitrogen booster pump 401 or the booster pump cross-line valve 405. A pressure gauge can be installed on the high-pressure nitrogen buffer tank 402 to facilitate the observation of the nitrogen pressure in the high-pressure nitrogen buffer tank 402.

[0021] like Figure 1 As shown, a process gas sealing isolation valve 501 and a process gas sealing non-return valve 502 are connected in sequence on the process medium gas source pipeline 5 according to the gas flow direction. There are multiple process gas sealing isolation valves 501, and multiple process gas sealing isolation valves 501 are connected in sequence to protect the tightness and ensure the safety and stability of use. During operation, the process medium gas source pipeline 5 and the primary sealing gas pipeline 6 are opened and closed by opening and closing the process gas sealing isolation valve 501.

[0022] like Figure 1 As shown, a primary gas liquid separation buffer tank 601, a primary gas booster pump 602, a dry gas sealing filter 603 and a primary sealing gas heater 604 are sequentially connected to the primary sealing gas pipeline 6 according to the gas flow direction. When the process gas is used as the primary sealing gas, since the process gas contains light hydrocarbon droplets, the light hydrocarbon droplets in the process gas are separated by the primary gas liquid separation buffer tank 601 and then purified by the dry gas sealing filter 603. After purification, the light hydrocarbon droplets enter the primary sealing end face of the dry gas seal. The temperature of the primary sealing gas is automatically controlled by the primary sealing gas heater 604 to prevent the light hydrocarbon components in the process gas from condensing into liquid and causing damage to the dry gas seal. A check valve 605, a regulating valve 606 and a flow meter 607 are also installed on the primary sealed gas pipeline 6. The check valve 605, the regulating valve 606 and the flow meter 607 are connected in series on the primary sealed gas pipeline 6 in sequence according to the direction of the airflow. The flow rate is regulated by the regulating valve 606, and the gas flow rate is measured by the flow meter 607, so as to facilitate the control adjustment.

[0023] like Figure 1 As shown, the secondary sealing structure includes a secondary and isolation gas source pipeline 7 and a secondary sealing gas pipeline 8, the isolation gas structure includes an isolation gas pipeline 9, the outlet end of the secondary and isolation gas source pipeline 7 is connected to the centrifugal compressor 1 through the secondary sealing gas pipeline 8, the inlet end of the secondary and isolation gas source pipeline 7 is connected to the air separation device 10, and nitrogen is provided as the secondary sealing gas for the secondary sealing end face, the inlet end of the isolation gas pipeline 9 is connected to the outlet end of the secondary and isolation gas source pipeline 7, and the outlet end of the isolation gas pipeline 9 is connected to the centrifugal compressor 1, and the low-pressure nitrogen provided by the air separation device 10 is used as the isolation gas.

[0024] When the centrifugal compressor 1 is started, since the process gas pressure is equal to the pressure in the machine body, there is no flow on the primary sealing end face, and the function of protecting the dry gas seal cannot be achieved. At this time, the nitrogen provided by the air separation unit 10 is introduced as the primary sealing gas, and the nitrogen passes through the nitrogen booster pump 401 or the booster pump cross-line valve 405 to reach the high-pressure nitrogen buffer tank 402, and passes through the high-pressure nitrogen valve 403 and the high-pressure nitrogen check valve 404 in turn, and then enters the dry gas sealing system through the primary sealing gas pipeline 6. At this time, the process gas sealing isolation valve 501 is in a closed state. When the speed of the centrifugal compressor 1 is normal, the process gas sealing isolation valve 501 is opened, the high-pressure nitrogen valve 403 is closed, and the process gas is introduced as the primary sealing gas. In this way, the primary sealing gas flow of the dry gas sealing system can be continuously guaranteed, and the purpose of protecting the dry gas sealing system can be achieved without starting the primary gas booster pump 602, and the service life of the primary gas booster pump 602 is extended. When nitrogen is used as the primary sealing gas, there are the following scenarios: 1) When the starting pressure of the centrifugal compressor 1 is lower than the nitrogen source pressure, open the booster pump cross-line valve 405 to introduce nitrogen into the dry gas sealing system; 2) When the starting pressure of the centrifugal compressor 1 is higher than the nitrogen gas source pressure, close the booster pump cross-line valve 405, open the nitrogen booster pump 401, and boost the nitrogen gas source pressure. While boosting, check the pressure of the high-pressure nitrogen buffer tank 402. When the pressure is higher than the machine body pressure, it can be used normally as in scenario 1); 3) Before the centrifugal compressor 1 stops normally and starts to slow down, the process gas and nitrogen are switched as the primary sealing gas. When switching, whether to start the nitrogen booster pump 401 is selected according to the body pressure.

[0025] A dry gas seal protection method for a compressor of a slurry bed residue oil hydrogenation unit is applied to the dry gas seal protection system for a compressor of a slurry bed residue oil hydrogenation unit described above, and the method comprises: The process gas output from the process gas outlet pipeline 3 of the centrifugal compressor 1 or the nitrogen delivered by the air separation unit 10 is returned to the centrifugal compressor 1 as the primary sealing gas, and the nitrogen delivered by the air separation unit 10 is used as the secondary sealing gas and the isolation gas. The selection principle of the primary sealing gas is determined by the starting pressure of the centrifugal compressor 1. When the starting pressure of the centrifugal compressor 1 is close to or exceeds the pressure of the high-pressure nitrogen delivered by the air separation unit 10 after pressurization, the high-pressure nitrogen is not used as the primary sealing gas source; when the centrifugal compressor 1 is started normally or the pressure of the centrifugal compressor 1 is close to the pressure of the high-pressure nitrogen source delivered by the air separation unit 10 after pressurization as the system is boosted, the primary sealing gas source is switched from the high-pressure nitrogen to the process gas output from the process gas outlet pipeline 3.

[0026] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of implementation of the present invention. That is, all equivalent changes and modifications made according to the content of the patent application scope of the present invention should belong to the technical scope of the present invention.

Claims

1. A dry gas seal protection system for a compressor of a slurry bed residue oil hydrogenation unit, comprising a centrifugal compressor (1), wherein the centrifugal compressor (1) is provided with a process gas inlet pipeline (2) and a process gas outlet pipeline (3), characterized in that: The invention also comprises a primary sealing structure, a secondary sealing structure and an isolation gas structure, wherein the primary sealing structure comprises a high-pressure nitrogen gas source pipeline (4), a process medium gas source pipeline (5) and a primary sealing gas pipeline (6), wherein the primary sealing gas pipeline (6) is connected to the centrifugal compressor (1), the primary sealing gas pipeline (6) is connected to the process gas outlet pipeline (3) through the process medium gas source pipeline (5), the high-pressure nitrogen gas source pipeline (4) is connected to the primary sealing gas pipeline (6), and the primary gas liquid separation buffer tank ( 601), a primary air booster pump (602), a dry air sealing filter (603) and a primary sealing air heater (604), the secondary sealing structure comprising a secondary and isolation air source pipeline (7) and a secondary sealing air pipeline (8), the secondary and isolation air source pipeline (7) being connected to the centrifugal compressor (1) via the secondary sealing air pipeline (8), the isolation air structure comprising an isolation air pipeline (9), one end of the isolation air pipeline (9) being connected to the secondary and isolation air source pipeline (7), and the other end of the isolation air pipeline (9) being connected to the centrifugal compressor (1).

2. The dry gas seal protection system for compressor of slurry bed residue oil hydrogenation unit according to claim 1, characterized in that: The primary sealed air pipeline (6) is also provided with a check valve (605), a regulating valve (606) and a flow meter (607); the check valve (605), the regulating valve (606) and the flow meter (607) are sequentially connected in series on the primary sealed air pipeline (6) according to the direction of air flow.

3. The dry gas seal protection system for compressor of slurry bed residue oil hydrogenation unit according to claim 1, characterized in that: The high-pressure nitrogen gas source pipeline (4) is provided with a nitrogen booster pump (401), a high-pressure nitrogen buffer tank (402), a high-pressure nitrogen valve (403) and a high-pressure nitrogen check valve (404) in sequence according to the gas flow direction. The number of the high-pressure nitrogen valves (403) is set to be multiple, and the multiple high-pressure nitrogen valves (403) are connected in series to the high-pressure nitrogen gas source pipeline (4).

4. The dry gas seal protection system for compressor of slurry bed residue oil hydrogenation unit according to claim 3 is characterized in that: The high-pressure nitrogen gas source pipeline (4) is also provided with a booster pump cross-line valve (405), and the booster pump cross-line valve (405) is connected in parallel with the nitrogen booster pump (401).

5. The dry gas seal protection system for compressor of slurry bed residue oil hydrogenation unit according to claim 1, characterized in that: A plurality of process gas sealing isolation valves (501) and process gas sealing non-return valves (502) are arranged in sequence on the process medium gas source pipeline (5) according to the gas flow direction.

6. The dry gas seal protection system for compressor of slurry bed residue oil hydrogenation unit according to claim 1, characterized in that: It also includes an air separation device (10), and the secondary and isolation gas source pipelines (7) and the high-pressure nitrogen gas source pipeline (4) are both connected to the air separation device (10).

7. A method for protecting dry gas seal of a compressor of a slurry bed residue oil hydrogenation unit, applied to a dry gas seal protection system of a compressor of a slurry bed residue oil hydrogenation unit as claimed in claims 1 to 6, characterized in that: The method comprises: The process gas output from the process gas outlet pipeline (3) of the centrifugal compressor (1) or the nitrogen delivered by the air separation unit (10) is returned to the centrifugal compressor (1) as primary sealing gas, and the nitrogen delivered by the air separation unit (10) is used as secondary sealing gas and isolation gas.

8. The method for protecting dry gas seal of a compressor of a slurry bed residue oil hydrogenation unit according to claim 7, characterized in that: The principle of selecting the primary sealing gas is determined by the starting pressure of the centrifugal compressor (1). When the starting pressure of the centrifugal compressor (1) approaches or exceeds the pressure of the high-pressure nitrogen gas delivered by the air separation unit (10) after being pressurized, the high-pressure nitrogen gas is not used as the primary sealing gas source. When the centrifugal compressor (1) starts normally or the pressure of the centrifugal compressor (1) approaches the pressure of the high-pressure nitrogen gas source delivered by the air separation unit (10) after being pressurized as the system is pressurized, the primary sealing gas source is switched from the high-pressure nitrogen gas to the process gas outputted from the process gas outlet pipeline (3).

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