Automatic mud switching system

Abstract

The application discloses a mud automatic switching system, which comprises a tank body, a metering bin, a sand setting bin, a degassing bin and a conveying bin are sequentially arranged in the tank body from one end to the other end, two vibrating screens are arranged side by side above the sand setting bin, the two vibrating screens are connected with a mud distributor, the mud distributor is connected with a mud return pipe, agitators are arranged in the degassing bin and the conveying bin, the degassing bin is communicated with the conveying bin through a balance pipeline, the degassing bin and the conveying bin are connected with a mud circulating mechanism, a plurality of make-up pumps are arranged below the vibrating screens, the plurality of make-up pumps are connected with the metering bin, and the metering bin, the sand setting bin, the degassing bin and the conveying bin are connected with a clean water pipeline through electric ball valve assemblies. The switching system solves the problem of long-distance conveying of mud and sand setting in the process of cluster well drilling.

Description

Technical Field

[0001] This invention belongs to the field of oil drilling and production equipment technology, and relates to an automatic mud transfer system. Background Technology

[0002] Cluster wells refer to drilling several or even hundreds of wells on a single well site or platform, with the wellheads less than a few meters apart and the bottoms of each well pointing in different directions. The widespread use of cluster wells is due to their ability to significantly reduce drilling costs compared to drilling a single directional well, while also meeting the overall development requirements of the oilfield. Unlike single directional wells, cluster well operations are characterized by their holistic and long-term nature.

[0003] Existing conventional mud transfer systems and solids control systems require 2-3 days to disassemble, relocate, and install the entire system during cluster well operations, resulting in a long operation cycle. In particular, sand settling is prone to occur during long-distance mud transportation. Summary of the Invention

[0004] The purpose of this invention is to provide an automatic mud transfer system, which solves the problem of long-distance mud and sand transport during cluster well drilling.

[0005] The technical solution adopted in this invention is an automatic mud transfer system, including a tank. Inside the tank, from one end to the other, are sequentially arranged a metering chamber, a settling chamber, a degassing chamber, and a transfer chamber. Two vibrating screens are arranged side-by-side above the settling chamber, both connected to a mud distributor. The mud distributor is connected to a mud return pipe. Agitators are installed in both the degassing chamber and the transfer chamber. The degassing chamber is connected to the transfer chamber via a balance pipeline. A mud circulation mechanism is connected to both the degassing chamber and the transfer chamber. Several replenishment pumps are installed below the vibrating screens, all connected to the metering chamber. The metering chamber, settling chamber, degassing chamber, and transfer chamber are each connected to a clean water pipeline via an electric ball valve assembly.

[0006] The invention is further characterized in that,

[0007] A degasser is installed between the degassing chamber and the transmission chamber. The degasser is connected to the degassing chamber and the transmission chamber through the degasser drain line, and the degasser is connected to the degasser exhaust line.

[0008] The bottom of the metering chamber, sedimentation chamber, degassing chamber, and transmission chamber are all connected to sand cleaning pipelines, and each sand cleaning pipeline is equipped with a sand cleaning valve.

[0009] The tank body is connected to one end of the floating platform on its side wall, and the other end of the floating platform is connected to the tank body side wall through the floating platform diagonal brace.

[0010] Each vibrating screen is equipped with a sand discharge plate at its discharge port. One end of the sand discharge plate is hinged to the side wall of the tank, and the other end of the sand discharge plate is equipped with a hook. The hook is connected to one end of a chain, and the other end of the chain is connected to the bottom of the floating platform.

[0011] Each vibrating screen is movably connected to a sand baffle on its side.

[0012] The mud circulation mechanism includes a transfer pump suction line A and a transfer pump suction line B. One end of the transfer pump suction line A is connected to the degassing chamber, and the other end of the transfer pump suction line A is connected to one end of the transfer pump discharge line A. The other end of the transfer pump discharge line A is connected to the degassing chamber. The transfer pump suction line A is equipped with butterfly valve B, butterfly valve C, transfer pump B, and butterfly valve D in sequence according to the liquid flow direction. A fourth butterfly valve is installed on the transfer pump discharge line A.

[0013] One end of the transfer pump suction line B is connected to the transfer chamber, and the other end of the transfer pump suction line B is connected to one end of the transfer pump discharge line B. The other end of the transfer pump discharge line B is connected to the transfer chamber. The transfer pump suction line B is equipped with butterfly valve J, butterfly valve I, transfer pump A and butterfly valve H in sequence according to the liquid flow direction. The first butterfly valve is installed on the transfer pump discharge line B.

[0014] The end of the transfer pump discharge line A away from the degassing chamber is connected to the end of the transfer pump discharge line B away from the transfer chamber via line D. A second butterfly valve and a third butterfly valve are installed on line D. A transfer line is connected to line D between the second butterfly valve and the third butterfly valve. A butterfly valve F is installed on the transfer line. The end of the transfer line away from butterfly valve F is connected to the flushing line via a ball valve. A butterfly valve E and a butterfly valve R are installed on the flushing line on both sides of the ball valve. The end of the flushing line near butterfly valve E is connected to the transfer pump suction line A. The flushing line between butterfly valve E and the ball valve is connected to the transfer pump suction line B via line C. A butterfly valve G is installed on line C.

[0015] The mud distributor is connected to the sedimentation chamber via pipeline B, and a butterfly valve T is connected to pipeline B; the mud distributor is connected to the metering chamber via pipeline A, and a butterfly valve S is connected to pipeline A.

[0016] The metering chamber is connected to a supply pipeline, and a butterfly valve Q is installed on the supply pipeline.

[0017] There are two supply pumps, namely supply pump A and supply pump B. Supply pump A is equipped with a butterfly valve L at its inlet and a butterfly valve K at its outlet. Supply pump B is equipped with a butterfly valve N at its inlet and a butterfly valve M at its outlet.

[0018] The beneficial effects of the present invention are as follows: The automatic mud transfer system of the present invention is suitable for cluster wells and has the functions of drilling fluid pretreatment, long-distance transmission of drilling fluid, remote valve control and integrated transportation. It can realize the screening, degassing, stirring, self-circulation and transmission of drilling fluid returned from the wellhead. Attached Figure Description

[0019] Figure 1 This is a front view of the automatic mud transfer system of the present invention;

[0020] Figure 2 This is a top view of the automatic mud transfer system of the present invention;

[0021] Figure 3 This is a side view of the automatic mud transfer system of the present invention;

[0022] Figure 4 This is a flowchart of the automatic mud transfer system of the present invention.

[0023] In the diagram, 1. Tank body, 2. Platform, 3. Railing, 4. Sand removal pipeline, 5. Ladder, 6. Mud distributor, 7. Sand baffle, 8. Sand discharge plate, 9. Mud return pipe, 10. Clean water pipeline, 11. Supply pipeline, 12. Supply pump A, 13. First butterfly valve, 14. Sand removal valve, 15. Deaerator discharge pipeline, 16. Deaerator exhaust pipeline, 17. Balancing pipeline, 18. Vibrating screen, 19. Agitator, 20. Deaerator, 21. Transfer pump A, 22. Transfer pump suction pipeline A, 23. Transfer pump discharge pipeline A, 24. Flushing pipeline, 25. Electric ball valve assembly, 26. Chain, 27. Platform diagonal brace, 28. Vibrating screen inlet pipe, 29. Butterfly valve A, 30. Butterfly... Valve B, 31. Butterfly Valve C, 32. Butterfly Valve D, 33. Butterfly Valve E, 34. Butterfly Valve F, 35. Butterfly Valve G, 36. Butterfly Valve H, 37. Butterfly Valve I, 38. Butterfly Valve J, 39. Butterfly Valve K, 40. Butterfly Valve L, 41. Butterfly Valve M, 42. Butterfly Valve N, 43. Butterfly Valve O, 44. Butterfly Valve P, 45. Butterfly Valve Q, 46. Butterfly Valve R, 47. Ball Valve, 48. Pipeline A, 49. Butterfly Valve S, 50. Pipeline B, 51. Butterfly Valve T, 52. Second Butterfly Valve, 53. Third Butterfly Valve, 54. Fourth Butterfly Valve, 55. Transfer Pump B, 56. Transfer Pump Suction Pipeline B, 57. Transfer Pump Discharge Pipeline B, 58. Transfer Pipeline, 59. Pipeline C, 60. Pipeline D, 61. Feed Pump B;

[0024] 1-1. Metering chamber, 1-2. Sedimentation chamber, 1-3. Degassing chamber, 1-4. Transfer chamber. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0026] This invention provides an automatic mud transfer system, such as... Figure 1 , Figure 2 and Figure 3As shown, the system includes a rectangular tank 1 mounted on a bottom skid. Inside the tank 1, from one end to the other, are sequentially arranged a metering chamber 1-1, a settling chamber 1-2, a degassing chamber 1-3, and a transfer chamber 1-4. Each of these chambers has a ladder leading down and a door. A perforated signboard is installed on the tank 1, corresponding to the settling chamber 1-2, indicating the capacity, descent capacity per unit, and lowest position, facilitating observation of the settling volume. Two vibrating screens 18 are arranged side-by-side above the settling chamber 1-2, both connected by a vibrating screen inlet pipe. 28 is connected to the mud distributor 6. A butterfly valve A29 is installed on the inlet pipe 28 of the vibrating screen. The mud distributor 6 is connected to the mud return pipe 9. After the mud enters the mud distributor 6, it enters the two vibrating screens 18 for processing. Agitators 19 are installed in both the degassing chamber 1-3 and the transmission chamber 1-4. The degassing chamber 1-3 is connected to the transmission chamber 1-4 through the balance pipeline 17. A degasser 20 is installed between the degassing chamber 1-3 and the transmission chamber 1-4. The degasser 20 is connected to the degassing chamber 1-3 and the transmission chamber 1-4 through the degasser discharge pipeline 15. The degasser 20 is connected to the degasser exhaust pipeline 16. -3 and the transfer chamber 1-4 are connected to a mud circulation mechanism. Several feed pumps are installed below the vibrating screen 18, and all feed pumps are connected to the metering chamber 1-1. The metering chamber 1-1 is connected to the feed pipeline 11, and a butterfly valve Q45 is installed on the feed pipeline 11. The metering chamber 1-1, the sedimentation chamber 1-2, the degassing chamber 1-3, and the transfer chamber 1-4 are respectively connected to the clean water pipeline 10 through the electric ball valve assembly 25. One end of the floating platform 2 is connected to the side wall of the tank body 1, and the other end of the floating platform 2 is connected to the side wall of the tank body 1 through the floating platform diagonal brace 27. The end of the floating platform 2 away from the tank body 1 is equipped with a railing 3. The floating platform 2 and the tank body are hinged. The railing 3 and the platform 2 are hinged and can be folded, so they do not need to be disassembled during transportation in the oilfield. A ladder 5 is provided at one end of the platform 2 for going up and down. The tank surface of the tank body 1, the platform, and the steps of the ladder 5 are all made of steel grating, which has an anti-slip effect. Each vibrating screen 18 has a sand discharge plate 8 at its sand discharge port. One end of the sand discharge plate 8 is hinged to the side wall of the tank body 1, and the other end of the sand discharge plate 8 is provided with a hook. The hook is connected to one end of the chain 26, and the other end of the chain 26 is connected to the bottom of the platform 2. Each vibrating screen 18 has a sand baffle 7 movably connected to its side to prevent rock cuttings and waste slurry from splashing.

[0027] The mud distributor 6 is connected to the settling chamber 1-2 via pipeline B50, and a butterfly valve T51 is connected to pipeline B50. The mud distributor 6 is connected to the metering chamber 1-1 via pipeline A48, and a butterfly valve S49 is connected to pipeline A48. When the particle size of impurities in the drilling fluid meets the requirements, it can be directly discharged into the settling chamber 1-2 and the metering chamber 1-1.

[0028] The bottom of metering chamber 1-1, sedimentation chamber 1-2, degassing chamber 1-3 and transmission chamber 1-4 are all connected to sand cleaning pipelines 4. Each sand cleaning pipeline 4 is equipped with a sand cleaning valve 14 to facilitate sand cleaning and prevent sedimentation during long-distance transmission of mud.

[0029] like Figure 4 As shown, the mud circulation mechanism includes a transfer pump suction line A22 and a transfer pump suction line B56. One end of the transfer pump suction line A22 is connected to the degassing chamber 1-3, and the other end of the transfer pump suction line A22 is connected to one end of the transfer pump discharge line A23. The other end of the transfer pump discharge line A23 is connected to the degassing chamber 1-3. The transfer pump suction line A22 is equipped with butterfly valve B30, butterfly valve C31, transfer pump B55, and butterfly valve D32 in sequence according to the liquid flow direction. The transfer pump discharge line A23 is equipped with a fourth butterfly valve 54.

[0030] One end of the transfer pump suction line B56 is connected to the transfer chamber 1-4, and the other end of the transfer pump suction line B56 is connected to one end of the transfer pump discharge line B57. The other end of the transfer pump discharge line B57 is connected to the transfer chamber 1-4. The transfer pump suction line B56 is equipped with butterfly valve J38, butterfly valve I37, transfer pump A21 and butterfly valve H36 in sequence according to the liquid flow direction. The transfer pump discharge line B57 is equipped with the first butterfly valve 13.

[0031] The end of the transfer pump discharge pipeline A23 away from the degassing chamber 1-3 is connected to the end of the transfer pump discharge pipeline B57 away from the transfer chamber 1-4 via pipeline D60. A second butterfly valve 52 and a third butterfly valve 53 are installed on pipeline D60. A transfer pipeline 58 is connected to pipeline D60 between the second butterfly valve 52 and the third butterfly valve 53. A butterfly valve F34 is installed on transfer pipeline 58. The end of transfer pipeline 58 away from butterfly valve F34 is connected to flushing pipeline 24 via ball valve 47. A butterfly valve E33 and a butterfly valve R46 are installed on both sides of ball valve 47 on flushing pipeline 24. The end of flushing pipeline 24 near butterfly valve E33 is connected to transfer pump suction pipeline A22. A pipeline C59 is connected to transfer pump suction pipeline B56 between butterfly valve E33 and ball valve 47 on flushing pipeline 24. A butterfly valve G35 is installed on pipeline C59.

[0032] There are two supply pumps, namely supply pump A12 and supply pump B61. Supply pump A12 is equipped with a butterfly valve L40 at its inlet and a butterfly valve K39 at its outlet. Supply pump B61 is equipped with a butterfly valve N42 at its inlet and a butterfly valve M41 at its outlet. Supply pumps A12 and B61 are mounted on the bottom skid and arranged side by side. Supply pumps A12 and B61 are connected to the wellhead bell mouth and mud distributor 6 respectively through supply pipeline 11. A butterfly valve O43 is installed near the wellhead bell mouth of supply pipeline 11, and a butterfly valve P44 is installed near the mud distributor 6 on supply pipeline 11.

[0033] All butterfly valves and ball valves involved in this invention are equipped with electric actuators. These electric actuators can open, close, or regulate the valves, enabling remote control, centralized control, and automatic control of the valves, improving the degree of automation, reducing worker labor efficiency, and providing functions such as liquid level monitoring and automatic mud transfer.

[0034] The working process of the automatic mud transfer system of the present invention is as follows: the drilling fluid returning from the wellhead enters the mud distributor 6 through the mud return pipe 9. The mud distributor 6 evenly distributes the drilling fluid to two vibrating screens 18. The vibrating screens 18 are equipped with sand baffles 7 to prevent rock cuttings and waste mud from splashing. A sand discharge plate 8 is installed at the sand discharge port to discharge large solid particles. The mud after being processed by the vibrating screens 18 enters the settling chamber 1-2. The mud with lower density in the settling chamber 1-2 overflows into the degassing chamber 1-3, and then enters the transfer chamber 1-4 through the balance pipeline 17. The degassing chamber 1-3 and the... Two agitators 19 on the transfer chamber 1-4 prevent the mud from solidifying. The deaerator 20 between the deaerator chamber 1-3 and the transfer chamber 1-4 removes harmful gases from the mud through the deaerator exhaust pipe 16. The mud in the deaerator chamber 1-3 and the transfer chamber 1-4 can be self-circulated between the two transfer pumps 21 to further enhance the pretreatment of the mud and prevent sand settling. Finally, the two transfer pumps 21 transport the mud to the original solids control system. The transfer system of this invention adopts a dual-pump, dual-process transfer function to ensure the safety of drilling operations.

[0035] When hoisting drill strings, annularity in the wellbore causes a shortage of drilling mud. The driller starts feed pumps A12 and B61, which draw in drilling mud from metering chamber 1-1. The mud in metering chamber 1-1 can be replenished through feed line 11 by opening butterfly valve Q45. The mud is then drawn back in by feed pumps A12 and B61, enters the wellhead bell mouth through feed line 11, and finally enters the wellbore. Drilling mud causing annularity during drill string lowering overflows through the wellhead bell mouth, then flows through mud return pipe 9 into mud distributor 6, and then into metering chamber 1-1 or sand settling chamber 1-2. The driller can monitor the level in metering chamber 1-1 to check for any abnormalities and take appropriate action.

[0036] Transfer pump A21 draws in drilling fluid from transfer chambers 1-4 via transfer pump suction line B56, and discharges it into the original solids control system via transfer line 58. Transfer pump B55 draws in drilling fluid from sand settling chambers 1-3 via transfer pump suction line A22, and discharges it into the original solids control system via transfer line 58. Simultaneously, transfer pump A21 discharges drilling fluid into transfer chambers 1-4 via transfer pump discharge line B57, and transfer pump B55 discharges drilling fluid via transfer pump discharge line A23. Drilling fluid is transported to sedimentation chamber 1-3. To prevent sedimentation caused by long-distance transmission of drilling fluid, the first butterfly valve 13, the second butterfly valve 52, the third butterfly valve 53, the fourth butterfly valve 54, and the butterfly valve R46 are closed. The electric ball valve assembly 25 and the ball valve 47 are opened. Clean water is introduced into metering chamber 1-1, sedimentation chamber 1-2, degassing chamber 1-3, and transmission chamber 1-4 through clean water pipeline 10. Clean water is drawn in by transmission pumps A21 and B55 and backflushed through flushing pipeline 24 to backflush transmission pipeline 58.

[0037] The transportation status of the automatic mud transfer system of this invention is as follows: The automatic mud transfer system of this invention has a skid-mounted structure, which can be transported as a whole. In cluster well operations, when the wellhead position changes, the transport skid moves the tank 1 to the same vertical direction as the corresponding wellhead position and connects the pipeline between the tank 1 and the vibrating screen 18. The tank 1 is kept at the same horizontal position as the original solids control system and at the same vertical direction as the corresponding wellhead position. During this process, the original solids control system does not need to be moved. Only the automatic mud transfer system needs to be moved and the pipeline between the automatic mud transfer system and the original solids control system needs to be connected. The relocation and disassembly time between wells can be completed within 1 hour, realizing integrated transportation, reducing non-drilling operation time, shortening the drilling cycle, and improving overall drilling efficiency. At the same time, it also solves the problem of mud sedimentation during long-distance transportation, as well as the overflow and suction problems caused by different mud discharge volumes in different drilling operations. In addition, the platform 2 and the railing 3 are designed to be flip-up and foldable, which can realize integrated transportation during long-distance relocation.

[0038] Conventional solids control systems require 2-3 days to disassemble, relocate, and install in cluster well operations. However, the system of this invention eliminates the need to move the original solids control system in cluster well operations. Only the automatic mud transfer system needs to be moved, and the pipeline connecting the automatic mud transfer system and the original solids control system needs to be connected. The relocation and disassembly between wells can be completed within hours, achieving integrated transportation, reducing non-drilling operation time, shortening the drilling cycle, and improving overall drilling efficiency.

Claims

1. An automatic mud transfer system, characterized in that, The system includes a tank (1), which contains, from one end to the other, a metering chamber (1-1), a sedimentation chamber (1-2), a degassing chamber (1-3), and a transfer chamber (1-4). Two vibrating screens (18) are arranged side-by-side above the sedimentation chamber (1-2), both connected to a mud distributor (6). The mud distributor (6) is connected to a mud return pipe (9). Agitators (19) are installed in both the degassing chamber (1-3) and the transfer chamber (1-4). The degassing chamber (1-3) is connected to the transfer chamber (1-4) via a balance pipeline (17). A mud circulation mechanism is connected to both the degassing chamber (1-3) and the transfer chamber (1-4). Several feed pumps are located below the vibrating screens (18), and these feed pumps are all connected to the metering chamber (1-1). The metering chamber (1-1), sedimentation chamber (1-2), degassing chamber (1-3) and transmission chamber (1-4) are respectively connected to the clean water pipeline (10) through an electric ball valve assembly (25); The mud circulation mechanism includes a transfer pump suction line A (22) and a transfer pump suction line B (56). One end of the transfer pump suction line A (22) is connected to the degassing chamber (1-3), and the other end of the transfer pump suction line A (22) is connected to one end of the transfer pump discharge line A (23). The other end of the transfer pump discharge line A (23) is connected to the degassing chamber (1-3). The transfer pump suction line A (22) is provided with butterfly valve B (30), butterfly valve C (31), transfer pump B (55), and butterfly valve D (32) in sequence according to the direction of liquid flow. The transfer pump discharge line A (23) is provided with a fourth butterfly valve (54). One end of the transfer pump suction line B (56) is connected to the transfer chamber (1-4), and the other end of the transfer pump suction line B (56) is connected to one end of the transfer pump discharge line B (57). The other end of the transfer pump discharge line B (57) is connected to the transfer chamber (1-4). The transfer pump suction line B (56) is provided with butterfly valve J (38), butterfly valve I (37), transfer pump A (21), and butterfly valve H (36) in sequence according to the liquid flow direction. The transfer pump discharge line B (57) is provided with a first butterfly valve (13). The end of the discharge pipeline A (23) of the transfer pump away from the degassing chamber (1-3) is connected to the end of the discharge pipeline B (57) of the transfer pump away from the transfer chamber (1-4) via pipeline D (60), and a second butterfly valve (52) and a third butterfly valve (53) are provided on pipeline D (60). A transfer pipeline (58) is connected on pipeline D (60) between the second butterfly valve (52) and the third butterfly valve (53). A butterfly valve F (34) is provided on the transfer pipeline (58). The transfer pipeline (58) is away from the butterfly valve F (34). One end is connected to the flushing pipeline (24) via a ball valve (47). A butterfly valve E (33) and a butterfly valve R (46) are respectively installed on the flushing pipeline (24) and on both sides of the ball valve (47). The end of the flushing pipeline (24) near the butterfly valve E (33) is connected to the transfer pump suction pipeline A (22). The flushing pipeline (24) between the butterfly valve E (33) and the ball valve (47) is connected to the transfer pump suction pipeline B (56) via pipeline C (59). A butterfly valve G (35) is installed on pipeline C (59).

2. The automatic mud transfer system according to claim 1, characterized in that, A degasser (20) is provided between the degassing chamber (1-3) and the transmission chamber (1-4). The degasser (20) is connected to the degassing chamber (1-3) and the transmission chamber (1-4) through the degasser drain line (15). The degasser (20) is connected to the degasser exhaust line (16).

3. The automatic mud transfer system according to claim 1, characterized in that, The bottom of the metering chamber (1-1), sedimentation chamber (1-2), degassing chamber (1-3) and transmission chamber (1-4) are all connected to sand cleaning pipelines (4), and each sand cleaning pipeline (4) is equipped with a sand cleaning valve (14).

4. The automatic mud transfer system according to claim 1, characterized in that, The side wall of the tank (1) is connected to one end of the floating platform (2), and the other end of the floating platform (2) is connected to the side wall of the tank (1) through the floating platform diagonal brace (27).

5. The automatic mud transfer system according to claim 4, characterized in that, Each of the vibrating screens (18) is provided with a sand discharge plate (8) at its sand discharge port. One end of the sand discharge plate (8) is hinged to the side wall of the tank body (1), and the other end of the sand discharge plate (8) is provided with a hook. The hook is connected to one end of a chain (26), and the other end of the chain (26) is connected to the bottom of the floating platform (2).

6. The automatic mud transfer system according to claim 1, characterized in that, Each of the vibrating screens (18) is movably connected to a sand baffle (7) on its side.

7. The automatic mud transfer system according to claim 1, characterized in that, The mud distributor (6) is connected to the sedimentation chamber (1-2) via pipeline B (50), and a butterfly valve T (51) is connected to pipeline B (50); the mud distributor (6) is connected to the metering chamber (1-1) via pipeline A (48), and a butterfly valve S (49) is connected to pipeline A (48).

8. The automatic mud transfer system according to claim 1, characterized in that, The metering chamber (1-1) is connected to a supply pipeline (11), and a butterfly valve Q (45) is installed on the supply pipeline (11).

9. The automatic mud transfer system according to claim 1, characterized in that, The number of supply pumps is 2, including supply pump A (12) and supply pump B (61). Supply pump A (12) is equipped with a butterfly valve L (40) at its inlet end and a butterfly valve K (39) at its outlet end. Supply pump B (61) is equipped with a butterfly valve N (42) at its inlet end and a butterfly valve M (41) at its outlet end.

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