Oil return and preheating safety treatment system for reducer pumps, and its oil return and preheating methods

Abstract

This invention relates to the field of petrochemicals and discloses a safe preheating system for the oil removal of a pressure reducing pump. The system includes a pressure reducing tower, a pressure reducing pump, a steam purging line, and a dedicated preheating line. A first valve is installed on the dedicated preheating line. A fifth valve, an eighth valve, and a ninth valve are respectively installed on the pressure reducing pump inlet line, sealing line, and vent line. A one-way valve, a seventh valve connected in parallel with the one-way valve, and a sixth valve located at the tail end are installed on the pressure reducing pump outlet line. The pressure reducing pump inlet line is connected to the outlet of the pressure reducing tower. The steam purging line is connected to the outlet line of the fifth valve. A fourth valve, a third valve, and a second valve are installed on the steam line. The two ends of the dedicated preheating line are respectively connected to the outlet line of the fourth valve and the pressure reducing tower. This safe preheating system for the pressure reducing pump reduces the steam purging time and steam consumption during the oil removal preheating process. The system allows for quantitative control of each stage of the process by monitoring changes in the pressure at the bottom of the pressure reducing tower, ensuring safe and controllable maintenance.

Description

Technical Field

[0001] This invention relates to the field of petrochemicals, specifically to a preheating and safety treatment system for oil removal from a bottom-reducing pump, as well as its oil removal and preheating methods. Background Technology

[0002] The operating temperature of the bottom residue oil in the atmospheric and vacuum distillation unit is 365℃. To facilitate the maintenance of the bottom residue pump, the process requires the oil from the pump to be returned and preheated. Currently, the conventional method used by various refineries is to return and preheat the oil via the heavy waste oil line. However, this traditional method has the following problems:

[0003] Before oil removal and preheating operations, the heavy oil line needs to be purged. The heavy oil system has a long process and a long steam penetration time, which will occupy the system's heavy oil system resources and increase steam consumption by 1.0 MPa. The steam consumption required for each pump maintenance is about 16 tons.

[0004] In addition, during the preheating operation, on the one hand, high-temperature residual oil (365℃) may enter the heavy waste oil tank and cause a sudden boiling accident; on the other hand, the preheating time of the heavy waste oil system cannot be controlled, and the preheating of the pump outlet may cause another operating bottom reducer pump to run dry. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of long processing time, high energy consumption, low safety, and unpredictable preheating time in the existing technology, and to provide a safe oil return preheating treatment system for a pressure reducing pump. This system reduces the steam purging time and steam consumption during the oil return preheating process of the pressure reducing pump. The system also allows for quantitative control of each process node by monitoring the pressure changes at the bottom of the pressure reducing tower, and ensures safe and controllable maintenance.

[0006] To achieve the above objectives, the present invention provides a preheating safety treatment system for the oil removal of a pressure reducing pump. This system includes: a pressure reducing tower, a pressure reducing pump, a steam purging line, and a dedicated preheating line. A first valve is installed on the dedicated preheating line. The pressure reducing pump is equipped with a pressure reducing pump inlet line, a pressure reducing pump outlet line, an oil sealing line, and a vent line. A fifth valve, an eighth valve, and a ninth valve are respectively installed on the pressure reducing pump inlet line, the oil sealing line, and the vent line. A one-way valve, a seventh valve connected in parallel with the one-way valve, and a sixth valve located at the tail end are installed on the pressure reducing pump outlet line. The pressure reducing pump inlet line is connected to the outlet of the pressure reducing tower. The steam purging line is connected to the outlet line of the fifth valve. A fourth valve, a third valve, and a second valve are sequentially installed on the steam purging line in a direction away from the pressure reducing pump inlet line. The two ends of the dedicated preheating line are respectively connected to the outlet line of the fourth valve and the pressure reducing tower.

[0007] Preferably, a pump auxiliary line is provided between the inlet line of the fifth valve and the outlet line of the sixth valve, a first auxiliary line valve is provided on the pump auxiliary line, a first steam auxiliary line is provided between the outlet line of the auxiliary line valve and the outlet line of the second valve, and a second auxiliary line valve is provided on the first steam auxiliary line.

[0008] Preferably, a second steam bypass line is provided between the inlet line of the third valve and the outlet line of the fifth valve, and a third bypass line valve is provided on the second steam bypass line.

[0009] Preferably, the pressure reducing tower is provided with an ultra-cooled oil line, and a tenth valve is provided on the ultra-cooled oil line, with the outlet line of the first valve connected to the outlet line of the tenth valve.

[0010] Preferably, the ultracooled oil line is made of Cr5Mo and has a design pressure of not less than 0.68 MPa.

[0011] Preferably, a filter is provided on the outlet line of the fifth valve.

[0012] Preferably, the preheating line is made of 0Cr18Ni10Ti and has a design pressure of not less than 2.475 MPa, and the inlet line of the reducing pump is made of 0Cr18Ni10Ti and has a design pressure of not less than 0.185 MPa.

[0013] A second aspect of the present invention provides a method for removing oil from a bottom-reducing pump, the method using the aforementioned oil removal preheating safety treatment system, comprising the following steps:

[0014] A1) Open the first valve, the second valve, and the third valve, and close the remaining valves. Use the preheating line to draw steam to purge the pressure reducing tower. When the pressure indicator at the bottom of the pressure reducing tower changes, close the second valve, the third valve, and the seventh valve. The purging process is then complete.

[0015] A2) Open the fourth valve, change the preheating line process, and then open the eighth valve to inject sealing oil into the reducing pump. The sealing oil is sent to the pressure reducing tower through the preheating line to replace and cool the reducing pump. When the surface temperature of the reducing pump cylinder is below 90°C, the oil cooling of the reducing pump ends.

[0016] A3) Close the fifth and fourth valves, open the ninth valve, and depressurize the bottom reducer pump cylinder to 0 MPa before handing it over for maintenance;

[0017] A4) Repeat step A1) purge and connect the preheating line.

[0018] Preferably, the steam in the steam purging line has a pressure of not less than 1.0 MPa.

[0019] A third aspect of the present invention discloses a method for preheating a bottom-reducing pump, which is performed after steps A1)-A4) are completed, and includes the following steps:

[0020] B1) Repeat step A1) purge and connect the preheating line;

[0021] B2) Open the fourth valve to change the preheating line process, and then open the sixth and seventh valves. The high-temperature residual oil is replaced and preheated by the preheating line to the pressure reducing tower.

[0022] B3) When the pressure indicator at the bottom of the pressure reducing tower is at the normal indication value, close the fourth valve and stop preheating to the pressure reducing tower via the preheating line.

[0023] B4) After closing the sixth valve, open the fifth valve, and then slowly open the sixth valve to the half-open state, and then preheat through the sixth valve at the outlet of the reducer pump;

[0024] B5) After preheating is complete, repeat step A1) to purge and connect the preheating line.

[0025] Through the above technical solution, the oil return preheating safety treatment system of the pressure reducing pump reduces the steam flow purging time and steam consumption during the oil return preheating process. The treatment of each node can be quantitatively controlled by the pressure change indicator at the bottom of the pressure reducing tower, and the maintenance process is safe and controllable. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of a preferred embodiment of the oil return preheating safety treatment system for a bottom reducer pump.

[0027] Explanation of reference numerals in the attached figures

[0028] 1-First valve; 2-Second valve; 3-Third valve; 4-Fourth valve; 5-Fifth valve; 6-Sixth valve; 7-Seventh valve; 8-Eighth valve; 9-Ninth valve; 10-Tenth valve; 11-Extreme cold oil line; 12-Preheating dedicated line; 13-Reducing pressure pump inlet line; 14-Steam purging line; 15-Pump auxiliary line; 16-Reducing pressure pump outlet line; 17-Check valve; 18-Sealing oil line; 19-Reducing pressure pump; 20-Filter; 21-Tower bottom root valve; 22-Second auxiliary line valve; 23-First auxiliary line valve; 24-First steam auxiliary line; 25-Second steam auxiliary line; 26-Third auxiliary line valve; 27-Vent line; 28-Pressure reducing tower. Detailed Implementation

[0029] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0030] In this invention, unless otherwise stated, directional terms such as "up, down, left, right, front, back, inside, outside" in the terminology only represent the orientation of the term in its normal use or are common terms understood by those skilled in the art, and should not be regarded as a limitation on the term.

[0031] See Figure 1 The illustrated oil removal preheating safety treatment system for the pressure reducing pump includes: a pressure reducing tower 28, a pressure reducing pump 19, a steam purging line 14, and a preheating dedicated line 12. A first valve 1 is installed on the preheating dedicated line 12. The pressure reducing pump 19 is equipped with a pressure reducing pump inlet line 13, a pressure reducing pump outlet line 16, an oil sealing line 18, and a vent line 27. A fifth valve 5, an eighth valve 8, and a ninth valve 9 are respectively installed on the pressure reducing pump inlet line 13, the oil sealing line 18, and the vent line 27. The pressure reducing pump outlet line 16... The system is equipped with a one-way valve 17, a seventh valve 7 connected in parallel with the one-way valve 17, and a sixth valve 6 located at the tail end; the inlet line 13 of the pressure reducing pump is connected to the outlet of the pressure reducing tower 28, the steam purging line 14 is connected to the outlet line of the fifth valve 5, and the steam purging line 14 is sequentially equipped with a fourth valve 4, a third valve 3, and a second valve 2 in a direction away from the inlet line 13 of the pressure reducing pump; the two ends of the preheating line 12 are respectively connected to the outlet line of the fourth valve 4 and the pressure reducing tower 28.

[0032] Through the implementation of the above technical solution, the oil return preheating safety treatment system of the pressure reducing pump 19 reduces the steam flow purging time and steam consumption during oil return preheating. The processing of each node can be quantitatively controlled by monitoring the pressure changes at the bottom of the pressure reducing tower 28, ensuring safe and controllable maintenance. Specifically, by adding a dedicated preheating line 12 to the pressure reducing tower 28 after the fifth valve 5 in the inlet pipeline of the pressure reducing pump 19, both oil return and preheating of the pressure reducing pump 19 can be operated via this dedicated line, effectively shortening the steam flow time. Simultaneously, the preheating status can be judged by monitoring the pressure changes at the bottom of the pressure reducing tower 28 during preheating via the dedicated preheating line 12, avoiding the risk of pump cavitation during preheating at the pump outlet. In this invention, the flow direction of the one-way valve 17 is towards the sixth valve 6.

[0033] In this embodiment, in order to further provide a safety treatment system for oil return preheating of the bottom reducer pump, a pump auxiliary line 15 is provided between the inlet line of the fifth valve 5 and the outlet line of the sixth valve 6. A first auxiliary line valve 23 is provided on the pump auxiliary line 15. A first steam auxiliary line 24 is provided between the outlet line of the auxiliary line valve and the outlet line of the second valve 2. A second auxiliary line valve 22 is provided on the first steam auxiliary line 24.

[0034] In this embodiment, in order to further provide a safety treatment system for oil return preheating of the bottom reducer pump, a second steam auxiliary line 25 is provided between the inlet line of the third valve 3 and the outlet line of the fifth valve 5, and a third auxiliary line valve 26 is provided on the second steam auxiliary line 25.

[0035] In this embodiment, an ultracooled oil line 11 is provided on the pressure reducing tower 28, and a tenth valve 10 is provided on the ultracooled oil line 11. The outlet line of the first valve 1 is connected to the outlet line of the tenth valve 10. With this arrangement, the preheating line 12 and the ultracooled oil line 11 share a common pipeline, and the high-temperature residual oil for sealing or preheating is finally sent into the pressure reducing tower 28 through the root of the ultracooled oil line 11.

[0036] In this embodiment, to further provide an ultra-cooled oil line 11 for better coordination with the preheating line 12, the ultra-cooled oil line 11 is made of Cr5Mo and has a design pressure of not less than 0.68 MPa. For example, in one embodiment, the ultra-cooled oil line 11 is made of Cr5Mo, has a design pressure of 0.68 MPa, and a design pipe diameter of DN100.

[0037] In this embodiment, a filter 20 is provided on the outlet line of the fifth valve 5. By providing the filter 20, less residual oil impurities enter the reducer pump 19.

[0038] In this embodiment, to further provide a preheating dedicated line 12 and a pressure reducing pump inlet line 13, the preheating dedicated line 12 is made of 0Cr18Ni10Ti and has a design pressure of not less than 2.475 MPa, and the pressure reducing pump inlet line 13 is made of 0Cr18Ni10Ti and has a design pressure of not less than 0.185 MPa. For example, in one embodiment, the preheating dedicated line 12 is made of 0Cr18Ni10Ti, has a design pressure of 2.475 MPa, and a design pipe diameter of DN40. The pressure reducing pump inlet line 13 is made of 0Cr18Ni10Ti, has a design pressure of 0.185 MPa, and a design pipe diameter of DN500.

[0039] A second aspect of the present invention provides a method for removing oil from a bottom-reducing pump, the method using the aforementioned oil removal preheating safety treatment system, comprising the following steps:

[0040] A1) Open the first valve 1, the second valve 2, the third valve 3 and the seventh valve, and close the remaining valves. Use the preheating line 12 to purge the pressure reducing tower 28 until the pressure indicator at the bottom of the pressure reducing tower 28 changes. Then close the second valve 2 and the third valve 3 to end the purging process.

[0041] A2) Open the fourth valve 4, change the flow of the preheating line 12, and then open the eighth valve 8 to inject sealing oil into the reducing pump 19. The sealing oil is then sent to the pressure reducing tower 28 via the preheating line 12 to replace and cool the reducing pump 19. When the surface temperature of the pump cylinder of the reducing pump 19 is below 90°C, the oil cooling of the reducing pump 19 is completed.

[0042] A3) Close the fifth valve 5 and the fourth valve 4, open the ninth valve 9, and depressurize the cylinder of the bottom reducer pump 19 to 0 MPa before handing it over for maintenance;

[0043] A4) Repeat step A1) purge and connect the preheating line 12.

[0044] Through the implementation of the above technical solution, the oil removal process of the pressure reducing pump 19 is completed in the preheating line 12. Steam enters the pressure reducing tower 28 through the preheating line 12 for purging and connection. Since the normal remote pressure value at the bottom of the pressure reducing tower 28 is -97 kPa, the pressure will suddenly drop to -91 kPa after the steam purging and connection. When the pressure suddenly changes, it can be known that the purging and connection has been completed. At this time, the connection purging is over. After the connection purging is completed, the process of the preheating line 12 is switched on, and the pressure reducing pump 19 is cooled by sealing oil. The sealing oil enters the pressure reducing tower 28 through the preheating line 12. When the surface temperature of the pump cylinder of the pressure reducing pump 19 drops below 90°C, the oil removal and cooling of the pressure reducing pump 19 is completed. Then, the fifth valve 5 and the fourth valve 4 are closed, and the ninth valve 9 is opened to depressurize the pump cylinder of the pressure reducing pump 19 to 0 MPa before it is handed over for maintenance. After the maintenance is completed, the preheating line 12 is purged and connected again for the next use.

[0045] In this embodiment, the steam in the steam purging line 14 is at a pressure of not less than 1.0 MPa. For example, in one specific embodiment, the steam in the steam purging line 14 is at a pressure of 1.0 MPa.

[0046] A third aspect of the present invention discloses a method for preheating a bottom-reducing pump, which is performed after steps A1)-A4) are completed, and includes the following steps:

[0047] B1) Repeat step A1) purge and connect the preheating line 12;

[0048] B2) Open the fourth valve 4, change the flow of the preheating line 12, and then open the sixth valve 6 and the seventh valve 7. The high-temperature residual oil is replaced and preheated by the preheating line 12 to the pressure reducing tower 28.

[0049] B3) When the remote pressure indicator at the bottom of the pressure reducing tower 28 is at the normal indication value, close the fourth valve 4 and stop preheating to the pressure reducing tower 28 via the preheating line 12.

[0050] B4) After closing the sixth valve 6, open the fifth valve 5, and then slowly open the sixth valve 6 to the half-closed state, and then preheat through the sixth valve 6 at the outlet of the bottom reducer pump 19;

[0051] B5) After preheating is complete, repeat step A1) to purge and connect the preheating line 12.

[0052] Through the implementation of the above technical solution, the purging and connection method of the preheating line 12 is the same as in step A1). After purging and connection, the flow of the preheating line 12 is changed, and then the sixth valve 6 and the seventh valve 7 are opened. The high-temperature residual oil is preheated and heated by the preheating line 12 to the pressure reducing tower 28. When the pressure indication at the bottom of the pressure reducing tower 28 does not change significantly, that is, when the indication is -97 kPa, the preheating to the pressure reducing tower 28 via the preheating line 12 is stopped, and the preheating is changed to the sixth valve 6 at the outlet of the pressure reducing pump 19. During the preheating process via the sixth valve 6 at the outlet of the pressure reducing pump 19, the sixth valve 6 needs to be opened slowly to a half-closed state so that the high-temperature residual oil flows in slowly, avoiding excessive impact due to excessive pressure difference. After two rounds of preheating, the preheating line 12 is purged and connected again for future use.

[0053] During the oil return process of the pressure reducing pump 19 and the preheating process of the pressure reducing pump, the bottom root valve 21 located at the bottom of the pressure reducing tower should always be kept open, or at least the bottom root valve 21 should be opened in step B4) of the pressure reducing pump preheating process.

[0054] After the above technical transformation, the steam purging time was shortened from 4 hours to 1 hour, and the steam consumption was reduced from 16 tons to 4 tons. The changes in pressure at each node can be quantitatively controlled by the pressure indicator at the bottom of the pressure reducing tower 28. After the transformation was put into use, the pressure reducing pump 19 underwent 30 maintenance operations without any abnormalities in pumping air. The maintenance process was safe and controllable.

[0055] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0056] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0057] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for removing oil from a bottom-reducing pump, characterized in that, The oil return method of the pressure reducing pump uses an oil return preheating safety treatment system, which includes: pressure reducing tower (28), pressure reducing pump (19), steam purging line (14) and preheating line (12), and the preheating line (12) is equipped with a first valve (1). The bottom reducing pump (19) is provided with a bottom reducing pump inlet line (13), a bottom reducing pump outlet line (16), an oil sealing line (18) and a vent line (27). The bottom reducing pump inlet line (13), the oil sealing line (18) and the vent line (27) are respectively provided with a fifth valve (5), an eighth valve (8) and a ninth valve (9). The bottom reducing pump outlet line (16) is provided with a one-way valve (17), a seventh valve (7) connected in parallel with the one-way valve (17) and a sixth valve (6) located at the tail end. The inlet line (13) of the pressure reducing pump is connected to the outlet of the pressure reducing tower (28), the steam purging line (14) is connected to the outlet line of the fifth valve (5), and the steam purging line (14) is sequentially provided with a fourth valve (4), a third valve (3) and a second valve (2) in the direction away from the inlet line (13) of the pressure reducing pump. The two ends of the preheating line (12) are respectively connected to the outlet line of the fourth valve (4) and the pressure reducing tower (28). The oil return method of the bottom-reducing pump includes the following steps: A1) Open the first valve (1), the second valve (2), the third valve (3) and the seventh valve, and close the remaining valves. Use the preheating line (12) to purge the pressure reducing tower (28) until the pressure indicator at the bottom of the pressure reducing tower (28) changes. Then close the second valve (2) and the third valve (3) to complete the purging process. A2) Open the fourth valve (4), change the flow of the preheating line (12), and then open the eighth valve (8) to inject sealing oil into the reducing pump (19). The sealing oil will go through the preheating line (12) to the pressure reducing tower (28) to replace and cool the reducing pump (19). When the surface temperature of the reducing pump (19) cylinder is lower than 90°C, the oil removal and cooling of the reducing pump (19) will end. A3) Close the fifth valve (5) and the fourth valve (4), open the ninth valve (9), and depressurize the cylinder of the bottom reducer pump (19) to 0 MPa before handing it over for maintenance; A4) Repeat step A1) purge and connect the preheating line (12).

2. The method for removing oil from a bottom-reducing pump according to claim 1, characterized in that, The steam purging line (14) contains steam with a pressure of not less than 1.0 MPa.

3. The method for removing oil from a bottom-reducing pump according to claim 1, characterized in that, A pump sub-line (15) is provided between the inlet line of the fifth valve (5) and the outlet line of the sixth valve (6). A first sub-line valve (23) is provided on the pump sub-line (15). A first steam sub-line (24) is provided between the outlet line of the sub-line valve and the outlet line of the second valve (2). A second sub-line valve (22) is provided on the first steam sub-line (24).

4. The method for removing oil from a bottom-reducing pump according to claim 1, characterized in that, A second steam sub-line (25) is provided between the inlet line of the third valve (3) and the outlet line of the fifth valve (5), and a third sub-line valve (26) is provided on the second steam sub-line (25).

5. The method for removing oil from a bottom-reducing pump according to claim 1, characterized in that, The pressure reducing tower (28) is equipped with an ultra-cooled oil line (11), and the ultra-cooled oil line (11) is equipped with a tenth valve (10). The outlet line of the first valve (1) is connected to the outlet line of the tenth valve (10).

6. The method for removing oil from a bottom-reducing pump according to claim 5, characterized in that, The material of the ultra-cooled oil line (11) is Cr5Mo, and the design pressure is not less than 0.68 MPa.

7. The method for removing oil from a bottom-reducing pump according to claim 1, characterized in that, A filter (20) is installed on the outlet line of the fifth valve (5).

8. The method for removing oil from a bottom-reducing pump according to claim 1, characterized in that, The preheating line (12) is made of oCr18Ni10Ti and has a design pressure of not less than 2.475 MPa. The inlet line (13) of the reducing pump is made of oCr18Ni10Ti and has a design pressure of not less than 0.185 MPa.

9. A method for preheating a pressure reducing pump, characterized in that, The preheating method for the reduced pressure pump is performed after steps A1)-A4) of any one of claims 1 to 8 are completed, and includes the following steps: B1) Repeat step A1) purge and connect the preheating line (12); B2) Open the fourth valve (4), change the flow of the preheating line (12), and then open the sixth valve (6) and the seventh valve (7). The high-temperature residue oil is replaced and preheated by the preheating line (12) to the pressure reducing tower (28). B3) When the pressure indicator at the bottom of the pressure reducing tower (28) is at the normal indication value, close the fourth valve (4) and stop preheating to the pressure reducing tower (28) via the preheating line (12); B4) After closing the sixth valve (6), open the fifth valve (5), and then slowly open the sixth valve (6) to the half-locked state, and then preheat through the sixth valve (6) at the outlet of the bottom reducer pump (19); B5) After preheating is completed, repeat step A1) to purge and connect the preheating line (12).

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