Novel no-load running check valve and using method

Abstract

The invention discloses a novel no-load running check valve and a using method, belongs to the technical field of boiler feed pump self-circulation, and aims to solve the problems of a traditional no-load running check valve. The check valve comprises a first valve body which is in a four-way shape, a lower opening of the first valve body is a main path inlet, an upper opening of the first valve body is a main path outlet, a left opening of the first valve body is an inlet side bypass, a right opening of the first valve body is an outlet side bypass, a throttling sleeve is connected with the inlet side bypass in a sealed mode, and a main valve element rod and the throttling sleeve are matched with a plurality of sealing convex rings through a plurality of bypass sealing flanges. The main path valve clack assembly is in sliding fit with the throttling sleeve and is in sliding sealing with the main valve element rod, the crank seat is in sealing fit with the outlet side bypass, a plurality of crank bodies are hinged to the crank seat, the second spring pushes the main path valve clack assembly leftwards through the crank bodies, and the throttling assembly is arranged in the outlet side bypass. The use function of the valve is increased, and the bypass on the outlet side can be used as a preheating pipeline or a backflow pipeline.

Description

Technical Field

[0001] The present invention belongs to the technical field of self - circulation of boiler feed pumps, and particularly relates to a new type of air - discharge check valve and its usage method. Background Technique

[0002] The function of the feed pump of a thermal power unit is to send the water in the deaerator to the boiler. To ensure the safe and effective operation of the pump, the flow rate of the pump must be higher than a certain safety flow rate under any circumstances. This safety flow rate is the minimum flow rate of the centrifugal pump. This minimum flow rate value is obtained by the pump manufacturer through experiments and is generally 20% - 30% of the rated flow rate of the pump. When the flow rate of the pump is lower than the minimum flow rate, it will cause the pump temperature to rise, vibration to intensify, cavitation to occur, etc., thus causing damage to the pump components. Therefore, it is necessary to design a minimum flow rate protection for the pump. Currently, there are various forms of minimum flow rate protection. One of them is to design a self - circulation control protection system and set an air - discharge check valve at the pump outlet. This valve can automatically control the opening and closing of the main pipeline and the bypass circuit according to the change of the flow rate to ensure the normal operation of the pump.

[0003] Currently, the traditional air - discharge check valves mainly have two structural forms: sliding type and piston type.

[0004] 1. Piston - type structure, as Figure 19 shown. When the main - path valve flap opens, the valve flap drives the transmission push rod to contact the bypass valve - core rod, causing the valve - core rod to move to the right, thereby closing the bypass circuit. When the main - path valve flap closes, the valve flap drives the transmission push rod to separate from the bypass valve - core rod. Under the action of the piston, the valve - core rod automatically opens the bypass circuit.

[0005] This type of structure has the following deficiencies:

[0006] (1) The bypass circuit is automatically closed by a piston structure. The piston of the bypass valve - core rod and the piston chamber are sealed by multiple O - rings. A small hole is machined in the center of the bypass valve - core rod and connected to the bypass outlet to keep the pressure below the piston relatively low. If any one of the O - rings is damaged, or the small hole in the valve - core rod becomes blocked, it will cause the pressure difference above and below the piston to not be established, resulting in the bypass circuit being unable to close normally, with a high risk of bypass circuit leakage and poor performance stability.

[0007] (2) In the actual application process, the structural dimensions of the piston and the piston chamber are generally small, resulting in small O - ring sizes, which are difficult to install. At the same time, the O - ring itself is a vulnerable part and is extremely likely to be damaged during the installation process. Moreover, the O - rings used for the piston and the piston chamber are all dynamic seals, with a high wear intensity, which also greatly reduces the service life of the O - rings, ultimately resulting in the bypass circuit being unable to close normally.

[0008] (3) Difficult product maintenance. When a bypass loop leakage problem occurs in the product, due to the excessive number of factors causing the problem, it is impossible to accurately and quickly locate the cause of the problem. At the same time, the O-ring may also be damaged during the disassembly process, making it impossible to determine the root cause of the product leakage, which poses great difficulties for product maintenance.

[0009] 2. The sliding structure, as Figure 20 shown. When the main path valve flap opens, the valve flap drives the fork rod to swing clockwise, causing the bypass small valve flap to slide, thereby closing the bypass loop. When the main path valve flap closes, the valve flap drives the fork rod to swing counterclockwise, causing the bypass small valve flap to slide again, thereby automatically opening the bypass loop.

[0010] The following are the deficiencies of this type of structure:

[0011] (1) The switching between the main path and the bypass is completely achieved by the swing of the fork rod, which requires a high assembly accuracy and a high technical level of the assembly workers.

[0012] (2) During each opening and closing process, the small valve flap and the bypass valve seat generate sliding friction, which is extremely easy to scratch the sealing surface, affecting the sealing effect and causing leakage in the bypass loop. It is more likely that the small valve flap and the bypass valve seat are directly stuck, resulting in the inability to close the main path and the overall failure of the valve.

[0013] In summary, there is an urgent need for a new type of air exhaust check valve with stable bypass loop performance and convenient installation and maintenance to solve the above problems. Summary of the Invention

[0014] The purpose of the present invention is to provide a new type of air exhaust check valve and its usage method to solve the problems existing in the traditional air exhaust check valve. The technical solutions adopted by the present invention are as follows:

[0015] A new type of air exhaust check valve includes a first valve body, a valve rod assembly, a main path valve flap assembly, a crank assembly, a throttle assembly, and a back pressure adjustment assembly;

[0016] The first valve body is in a four-way shape. The lower opening of the first valve body is the main path inlet, the upper opening of the first valve body is the main path outlet, the left opening of the first valve body is the inlet side bypass, the right opening of the first valve body is the outlet side bypass. The main path inlet and the inlet side bypass are connected through the left valve cavity, the main path outlet and the outlet side bypass are connected through the right valve cavity, the left valve cavity and the right valve cavity are connected through the main path channel, and a first hard alloy sealing surface is built-up welded on the main path channel;

[0017] The valve stem assembly includes a main valve stem and a throttle sleeve. The left part of the throttle sleeve is sealingly connected to the right part of the inlet side bypass. The main valve stem is in sliding fit with the throttle sleeve. A number of sealing convex rings are arranged at intervals on the inner hole of the throttle sleeve, and a number of bypass sealing flanges are arranged at intervals on the outer circumference of the main valve stem. The number of bypass sealing flanges and the number of sealing convex rings are in one-to-one correspondence for abutting and sealing or separating. When the bypass sealing flange is separated from the corresponding sealing convex ring, an eddy current pressure reduction flow channel is formed between the main valve stem and the throttle sleeve. The left valve cavity is communicated with the left part of the inlet side bypass through the eddy current pressure reduction flow channel;

[0018] The main path valve flap assembly includes a first main path valve flap, an annular pressing plate, a spring cover and a first spring. A stepped groove is formed on the left end face of the first main path valve flap. The stepped groove is in sliding fit with the outer circumference of the right part of the throttle sleeve. A main sealing flange is arranged at the right end of the outer circumference of the first main path valve flap. A second hard alloy sealing surface is built-up welded on the main sealing flange. The second hard alloy sealing surface abuts and seals or separates from the first hard alloy sealing surface. A sliding counterbore is formed on the right end face of the first main path valve flap. The annular pressing plate is coaxially fixed at the notch of the sliding counterbore. The spring cover is a cylindrical member with an open left end. A sliding flange is arranged at the left end of the spring cover. The axial thickness of the sliding flange is less than the depth of the sliding counterbore. The outer circumference of the sliding flange is in sliding fit with the side wall of the sliding counterbore. The inner circumference of the annular pressing plate is in sliding fit with the outer circumference of the spring cover. A limiting annular wall is arranged between the stepped groove and the sliding counterbore. The main valve stem is in sliding and sealing fit with the inner circumference of the limiting annular wall. A first spring is arranged in the spring cover. The first spring is sleeved on the main valve stem. The two ends of the first spring respectively abut against the limiting annular wall and the right end wall of the spring cover;

[0019] The crank assembly includes a crank seat. The crank seat is a pipe sleeve-shaped member. A number of connecting ears are arranged at the left end of the crank seat. One end of a number of crank bodies is respectively hinged to the number of connecting ears. The crank seat is in sealing fit with the outlet side bypass. The other ends of the number of crank bodies all abut against the right end wall of the spring cover;

[0020] The large diameter end of the bypass reducing flange is connected to the pipe body of the outlet side bypass. The bypass reducing flange is in sealing fit with the crank seat. The throttle assembly is arranged on the inner hole diameter of the bypass reducing flange;

[0021] The spring seat, the second spring and the throttle assembly abut against each other from left to right. The spring seat is bowl-shaped. The rim end of the spring seat faces left and abuts against the right side of the number of crank bodies. A connecting screw hole and a number of fourth flow holes are arranged at the bottom of the bowl of the spring seat. The main valve stem is in threaded fit with the connecting screw hole and is locked by a lock nut. The second spring is sleeved on the main valve stem. A third positioning hole is formed on the left end face of the first throttle ring. The main valve stem is in sliding fit with the third positioning hole;

[0022] The back pressure adjustment assembly is arranged at the left end of the diameter of the inlet side bypass.

[0023] Furthermore, the valve stem assembly further includes a locking sleeve. The inner hole of the throttle sleeve consists of a throttle hole, a balance hole, and a first positioning hole that are coaxially connected in sequence from left to right. A number of sealing convex rings are arranged at intervals on the side wall of the throttle hole. A number of first flow holes are arranged circumferentially on the side wall of the balance hole. The locking sleeve is fixed to the left end of the throttle sleeve, and the locking sleeve closes the left-end opening of the throttle sleeve. The locking sleeve is provided with a second positioning hole and a number of second flow holes. The main valve stem includes a second positioning section, a sealing section, a balance section, a first positioning section, a connecting section, and a third positioning section that are coaxially connected in sequence from left to right. A number of bypass sealing flanges are arranged at intervals on the sealing section. The second positioning section is in sliding fit with the second positioning hole. An annular cavity is formed between the outer circumference of the balance section and the side wall of the balance hole. The left part of the first positioning section is in sliding fit with the first positioning hole. The annular cavity is communicated with the left valve cavity through a number of first flow holes.

[0024] Furthermore, the stepped groove consists of a guiding groove, a flow-through groove, and a balance groove that are coaxially connected in sequence from left to right. The diameter of the guiding groove is smaller than the diameters of the flow-through groove and the balance groove. The side wall of the guiding groove is in sliding fit with the outer circumference of the throttle sleeve. The first positioning section is in sliding and sealing fit with the inner circumference of the limiting annular wall. A number of third flow holes are arranged circumferentially on the side wall of the flow-through groove. The left valve cavity is communicated with the balance groove through a number of third flow holes and the flow-through groove in sequence. The first spring is sleeved on the first positioning section.

[0025] Furthermore, a concave stop is provided on the right-end face of the pipe body of the outlet-side bypass. The concave stop is coaxial with the outlet-side bypass. A positioning flange is provided at the right end of the crank seat. The bypass reducing flange presses the positioning flange into the concave stop, and the positioning flange is in stop fit with the concave stop.

[0026] Furthermore, the throttle assembly includes a first throttle ring and a number of throttle orifice plates. The first throttle ring and the number of throttle orifice plates are arranged in sequence from left to right on the inner-hole diameter of the bypass reducing flange. Axial gaps are provided between the first throttle ring and the adjacent throttle orifice plate and between adjacent two throttle orifice plates. A number of fifth flow holes are provided on the first throttle ring.

[0027] Furthermore, a partition ring structure protruding leftward is provided at the edge of the throttle orifice plate. The throttle orifice plate abuts against the adjacent throttle orifice plate or throttle ring on the left through the partition ring structure.

[0028] Furthermore, the inner hole of the bypass reducing flange is a stepped hole. A first snap ring is provided in the inner hole of the bypass reducing flange. The first throttle ring and the number of throttle orifice plates are axially limited by the snap ring and the inner-hole step of the bypass reducing flange.

[0029] Further, the backpressure adjustment assembly includes a connection seat, a sealing plate, a third spring, and an adjustment cover. The connection seat is arranged at the left end of the through diameter of the inlet side bypass. The connection seat is a sleeve-shaped member and is provided with a right end wall. A sixth flow hole is opened on the right end wall of the connection seat. The inner circumference of the connection seat is threadedly connected to the outer circumference of the adjustment cover. A number of seventh flow holes are provided on the adjustment cover. The adjustment cover presses the sealing plate against the right end wall of the connection seat through the third spring to close the fifth flow hole. The inlet side bypass is a stepped hole and is provided with a second snap spring inside. The backpressure adjustment assembly is axially limited by the second snap spring and the inner hole step of the inlet side bypass.

[0030] The present invention also provides a usage method of a new type of air discharge check valve, which is realized based on the above new type of air discharge check valve. The deaerator is connected to the main path inlet through a first main pipeline, and a water pump is provided on the first main pipeline. The main path outlet is connected to the boiler through a second main pipeline, and a first shut-off valve is provided on the second main pipeline. The inlet side bypass is connected to the deaerator through a first bypass pipeline, and the outlet side bypass is connected to the boiler through a second bypass pipeline. A second shut-off valve is provided on the second bypass pipeline, and the second bypass pipeline is used as a preheating pipeline.

[0031] The present invention also provides another usage method of a new type of air discharge check valve, which is realized based on the above new type of air discharge check valve. The deaerator is connected to the main path inlet through a first main pipeline, and a water pump is provided on the first main pipeline. The main path outlet is connected to the boiler through a second main pipeline, and a first shut-off valve is provided on the second main pipeline. The inlet side bypass is connected to the deaerator through a first bypass pipeline, and the outlet side bypass is connected to the deaerator through a second bypass pipeline. A second shut-off valve is provided on the second bypass pipeline, and the second bypass pipeline is used as a return pipeline.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. By designing the outlet side bypass, the new type of air discharge check valve of the present invention increases the usage functions of the valve. Compared with the traditional air discharge check valve, a new bypass pipeline is added, which can be used as a preheating pipeline or a return pipeline. Or, according to needs, the bypass flange can be replaced with a blind plate to make the valve function the same as that of the traditional air discharge check valve.

[0034] 2. The new type of air discharge check valve of the present invention realizes the opening and closing of the bypass circuit through the mechanical properties of the second spring, and the performance is more stable; the main path valve flap assembly is designed with a first spring, which overcomes the leakage of the inlet side bypass caused by working condition fluctuations and improves the sealing performance of the inlet side bypass.

[0035] 3. By designing the backpressure adjustment assembly, the new type of air discharge check valve of the present invention reduces the pressure difference at both ends of the valve stem assembly, reduces the occurrence of cavitation phenomenon, thus better protecting the valve stem assembly and improving the performance stability and service life of the inlet side bypass.

[0036] 4. The main function of the novel air discharge check valve of the present invention is realized by spring force, with lower requirements for machining accuracy and assembly, more stable performance. All internal parts are installed from one side. During maintenance, only the bypass reducing flange needs to be disassembled, and then all internal parts can be disassembled in sequence, which is convenient for installation and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a schematic structural diagram of the novel air discharge check valve of the present invention;

[0038] Figure 2 is a schematic structural diagram of the first valve body;

[0039] Figure 3 is a schematic structural diagram of the valve stem assembly;

[0040] Figure 4 is a schematic structural diagram of the throttle sleeve;

[0041] Figure 5 is a schematic structural diagram of the main spool stem;

[0042] Figure 6 is a schematic structural diagram of the locking sleeve;

[0043] Figure 7 is a schematic structural diagram of the main path valve flap assembly;

[0044] Figure 8 is a schematic structural diagram of the first main path valve flap;

[0045] Figure 9 is a schematic structural diagram of the spring cover;

[0046] Figure 10 is a schematic diagram of the cooperation between the crank assembly and the throttle assembly;

[0047] Figure 11 is a schematic structural diagram of the crank assembly;

[0048] Figure 12 is Figure 11 the left view of

[0049] Figure 13 is a schematic structural diagram of the spring seat;

[0050] Figure 14 is Figure 13 the view in the direction of K of

[0051] Figure 15 is a schematic diagram of the cooperation between the throttle assembly and the bypass reducing flange;

[0052] Figure 16 is a schematic diagram of the cooperation between the back pressure adjustment assembly and the first valve body;

[0053] Figure 17 It is a schematic connection diagram of the usage method of the novel air-discharging check valve of the present invention in Embodiment 2;

[0054] Figure 18 It is a schematic connection diagram of the usage method of the novel air-discharging check valve of the present invention in Embodiment 3;

[0055] Figure 19 It is a schematic structural diagram of a traditional piston-type air-discharging check valve;

[0056] Figure 20 It is a schematic structural diagram of a traditional sliding-type air-discharging check valve.

[0057] In the figure: 1. First valve body; 2. Valve rod assembly; 3. Main path valve flap assembly; 4. Back pressure adjustment assembly; 5. Crank assembly; 6. Throttle assembly; 7. Bypass reducing flange; 8. Main path inlet; 9. Main path outlet; 10. Inlet side bypass; 11. Outlet side bypass; 12. Left valve cavity; 13. Main path channel; 14. Right valve cavity; 15. First cemented carbide sealing surface; 16. Concave stop; 17. Locking sleeve; 18. Throttle sleeve; 19. Main valve spool rod; 20. Throttle hole; 21. Sealing convex ring; 22. First flow hole; 23. Balance hole; 24. First positioning hole; 25. Second positioning section; 26. Sealing section; 27. Bypass sealing flange; 28. Balance section; 29. First positioning section; 30. Connection section; 31. Third positioning section; 32. Second positioning hole; 33. Second flow hole; 34. First main path valve flap; 35. Annular pressing plate; 36. First spring; 37. Spring cover; 38. Guide groove; 39. Flow groove; 40. Balance groove; 41. Third flow hole; 42. Main sealing flange; 43. Second cemented carbide sealing surface; 44. Limit annular wall; 45. Sliding sink; 46. Sliding flange; 47. Fourth positioning hole; 48. Crank seat; 49. Spring seat; 50. Second spring; 51. Back nut; 52. Crank body; 53. Positioning flange; 54. Bowl bottom; 55. Connection screw hole; 56. Fourth flow hole; 57. Rim end; 58. First throttle ring; 59. Throttle orifice plate; 60. Fifth flow hole; 61. Third positioning hole; 62. Spacer ring structure; 63. First snap ring; 64. Connection seat; 65. Sealing plate; 66. Third spring; 67. Adjusting cover; 68. Sixth flow hole; 69. Second snap ring; 70. Second valve body; 71. Transmission ejector rod; 72. Second main path valve flap; 73. Piston chamber; 74. Piston; 75. Throttle cylinder; 76. Bypass valve spool rod; 77. Third valve body; 78. Third main path valve flap; 79. Fork rod; 80. Small valve flap; 81. Bypass valve seat; 82. Second throttle ring; 100. Air exhaust check valve; 200. Deaerator; 300. Boiler; 400. Water pump; 410. First main pipeline; 500. First shut-off valve; 510. Second main pipeline; 600. Second shut-off valve; 610. Second bypass pipeline; 710. First bypass pipeline. Detailed implementation manners

[0058] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be described below through specific embodiments shown in the drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0059] The connections mentioned in the present invention are divided into fixed connections and detachable connections. The fixed connections, i.e., non-detachable connections, include but are not limited to conventional fixed connection methods such as hemming connection, riveting connection, bonding connection, and welding connection, etc. The detachable connections include but are not limited to conventional disassembly methods such as bolt connection, snap connection, pin connection, and hinge connection, etc. When the specific connection method is not clearly defined, it is default that at least one connection method can be found among the existing connection methods to achieve this function, and those skilled in the art can choose according to their needs. For example: welding connection is selected for fixed connection, and bolt connection is selected for detachable connection.

[0060] The present invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are explanations of the present invention, and the present invention is not limited to the following embodiments.

[0061] Embodiment 1: As Figures 1 to 16 , Figure 19 , Figure 20 shown, a new type of air exhaust check valve includes a first valve body 1, a valve stem assembly 2, a main path valve flap assembly 3, a crank assembly 5, a throttle assembly 6, and a back pressure adjustment assembly 4;

[0062] The first valve body 1 is in a four-way shape. The lower opening of the first valve body 1 is the main path inlet 8, the upper opening of the first valve body 1 is the main path outlet 9, the left opening of the first valve body 1 is the inlet side bypass 10, and the right opening of the first valve body 1 is the outlet side bypass 11. The main path inlet 8 and the inlet side bypass 10 are connected through the left valve cavity 12, the main path outlet 9 and the outlet side bypass 11 are connected through the right valve cavity 14, and the left valve cavity 12 and the right valve cavity 14 are connected through the main path channel 13. A first hard alloy sealing surface 15 is surfacing welded on the main path channel 13;

[0063] The valve stem assembly 2 includes a main valve core rod 19 and a throttle sleeve 18. The left part of the throttle sleeve 18 is hermetically connected to the right part of the inlet side bypass 10, the right part of the throttle sleeve 18 extends into the left valve cavity 12, the main valve core rod 19 is slidably matched with the throttle sleeve 18. A plurality of sealing convex rings 21 are arranged at intervals on the inner hole of the throttle sleeve 18, and a plurality of bypass sealing flanges 27 are arranged at intervals on the outer circumference of the main valve core rod 19. The outer circumference of the bypass sealing flange 27 does not contact the side wall of the throttle hole 20, and the outer circumference of the sealing convex ring 21 does not contact the sealing section 26 either. However, a plurality of bypass sealing flanges 27 and a plurality of sealing convex rings 21 are in sealing contact or separation one by one. When the bypass sealing flange 27 is separated from the corresponding sealing convex ring 21, an eddy current pressure reduction flow channel is formed between the main valve core rod 19 and the throttle sleeve 18, and the left valve cavity 12 is communicated with the left part of the inlet side bypass 10 through the eddy current pressure reduction flow channel;

[0064] The main path valve flap assembly 3 includes a first main path valve flap 34, an annular pressing plate 35, a spring cover 37 and a first spring 36. The first main path valve flap 34 is sleeved on the main valve core rod 19. A stepped groove is provided on the left end face of the first main path valve flap 34, and the stepped groove is in sliding fit with the outer periphery of the right part of the throttle sleeve 18. A main sealing flange 42 is provided at the right outer end of the first main path valve flap 34, and a second hard alloy sealing surface 43 is surfacing welded on the main sealing flange 42. The second hard alloy sealing surface 43 abuts and seals or separates from the first hard alloy sealing surface 15. A sliding counterbore 45 is provided on the right end face of the first main path valve flap 34. The annular pressing plate 35 is coaxially fixed at the notch of the sliding counterbore 45. The spring cover 37 is a cylindrical member with an open left end. A sliding flange 46 is provided at the left end of the spring cover 37. The axial thickness of the sliding flange 46 is less than the depth of the sliding counterbore 45. The outer periphery of the sliding flange 46 is in sliding fit with the side wall of the sliding counterbore 45. The inner periphery of the annular pressing plate 35 is in sliding fit with the outer periphery of the spring cover 37. The bottom of the sliding counterbore 45 and the annular pressing plate 35 axially limit the sliding flange 46. A limiting annular wall 44 is provided between the stepped groove and the sliding counterbore 45. The limiting annular wall 44 is integrally formed with the first main path valve flap 34. A fourth positioning hole 47 is provided on the right end wall of the spring cover 37. The main valve core rod 19 passes through the inner periphery of the limiting annular wall 44 and the fourth positioning hole 47. The main valve core rod 19 is in sliding fit with the fourth positioning hole 47. The main valve core rod 19 is in sliding and sealing fit with the inner periphery of the limiting annular wall 44. The first spring 36 is provided inside the spring cover 37. The first spring 36 is sleeved on the main valve core rod 19. The two ends of the first spring 36 respectively abut against the limiting annular wall 44 and the right end wall of the spring cover 37;

[0065] The crank assembly 5 includes a crank seat 48. The crank seat 48 is a tubular sleeve-shaped member. A plurality of connecting ears are provided at the left end of the crank seat 48. One end of a plurality of crank bodies 52 is respectively hinged to the plurality of connecting ears. The main valve core rod 19 passes through the plurality of crank bodies 52. The crank seat 48 is in sealing fit with the outlet side bypass 11 through an O-ring. The other ends of the plurality of crank bodies 52 all abut against the right end wall of the spring cover 37;

[0066] The large-diameter end of the bypass reducing flange 7 is connected to the pipe body of the outlet side bypass 11. The bypass reducing flange 7 is in sealing fit with the crank seat 48 through an O-ring. The throttle assembly 6 is arranged on the inner hole diameter of the bypass reducing flange 7;

[0067] The spring seat 49, the second spring 50 and the throttling component 6 are abutted against each other in sequence from left to right. The spring seat 49 is bowl-shaped, the rim end 57 of the spring seat 49 faces left, the rim end 57 abuts against the right side of a plurality of crank bodies 52, a connecting screw hole 55 and a plurality of fourth flow holes 56 are provided on the bottom 54 of the bowl of the spring seat 49, the main valve spool rod 19 is in threaded fit with the connecting screw hole 55 and is locked by a lock nut 51. The second spring 50 is sleeved on the main valve spool rod 19. A third positioning hole 61 is formed on the left end face of the first throttling ring 58, and the main valve spool rod 19 is in sliding fit with the third positioning hole 61;

[0068] The back pressure adjustment component 4 is arranged at the left end of the diameter of the inlet side bypass 10.

[0069] At present, the traditional air discharge check valves mainly have two structural forms: the sliding air discharge check valve and the piston air discharge check valve.

[0070] 1. Piston air discharge check valve, as Figure 19 shown, includes a second valve body 70. The right opening of the second valve body 70 is the medium inlet channel, and the left opening of the second valve body 70 is the medium outlet channel. The medium inlet channel and the medium outlet channel of the piston air discharge check valve form a coaxial main flow channel. The second main valve flap 72 is slidably arranged in the main flow channel of the piston air discharge check valve and abuts against or separates from the valve seat arranged in the medium outlet channel of the second valve body 70. The upper side of the second valve body 70 is the bypass circuit. A throttling cylinder 75 and a bypass valve spool rod 76 which are matched with each other are arranged in the bypass circuit of the second valve body 70. A piston chamber 73 is arranged below the throttling cylinder 75. A piston 74 is in sliding fit with the piston chamber 73. The bypass valve spool rod 76 is connected with the piston 74. When the second main valve flap 72 is opened, the second main valve flap 72 drives the transmission ejector rod 71 to rotate clockwise. The transmission ejector rod 71 presses the bypass valve spool rod 76 to move upward through the piston 74, thereby closing the bypass circuit of the piston air discharge check valve. When the second main valve flap 72 is closed, the second main valve flap 72 drives the transmission ejector rod 71 to rotate counterclockwise. Under the action of the piston 74, the bypass valve spool rod 76 automatically opens the bypass circuit of the piston air discharge check valve.

[0071] This kind of structure has the following deficiencies:

[0072] a. The bypass circuit is automatically closed by adopting the piston 74 structure. The bypass valve spool rod 76, the piston 74 and the piston chamber 73 are sealed by a plurality of O-rings. The bypass valve spool rod 76 is processed with a through hole along the axis. The two ends of the bypass circuit of the piston air discharge check valve are connected through the through hole to keep the pressure below the piston 74 relatively low. If any one of the O-rings of the bypass valve spool rod 76, the piston 74 and the piston chamber 73 is damaged, or the through hole is blocked, it will cause no pressure difference to be established between the upper and lower parts of the piston 74, resulting in the bypass circuit of the piston air discharge check valve unable to be normally closed, with a large risk of bypass circuit leakage and poor performance stability.

[0073] b. During the actual operation process, the structural dimensions of the piston 74 and the piston chamber 73 are generally small, resulting in a small size of the O-ring for sealing. It is difficult to install, and at the same time, the O-ring itself is a vulnerable part and is extremely likely to be damaged during the installation process. Moreover, the O-rings used for the piston 74 and the piston chamber 73 are both dynamic seals, with a large wear intensity, which also greatly reduces the service life of the O-ring, ultimately resulting in the inability of the bypass circuit to be normally closed.

[0074] c. Product maintenance is difficult. When there is a leak in the bypass circuit of the piston type air discharge check valve, due to too many factors causing the leak, it is impossible to accurately and quickly locate the cause of the leak. At the same time, the O-ring may also be damaged during the disassembly process, making it impossible to determine the root cause of the product leak, which poses great difficulties for product maintenance.

[0075] 2. The sliding type air discharge check valve is as Figure 20 shown. It includes a third valve body 77. The right opening of the third valve body 77 is the medium inlet channel, and the left opening of the third valve body 77 is the medium outlet channel. The medium inlet channel and the medium outlet channel of the sliding type air discharge check valve form a coaxial main flow channel. The third main valve flap 78 is slidably arranged in the main flow channel of the sliding type air discharge check valve and abuts and seals or separates from the valve seat arranged in the medium outlet channel of the third valve body 77. The upper side of the third valve body 77 is the bypass circuit. When the third main valve flap 78 is opened, the third main valve flap 78 drives the fork rod 79 to swing clockwise, causing the bypass small valve flap 80 to slide upward, thereby closing the bypass circuit of the sliding type air discharge check valve. When the third main valve flap 78 is closed, the valve flap drives the fork rod 79 to swing counterclockwise, causing the small valve flap 80 to slide downward, thereby automatically opening the bypass circuit of the sliding type air discharge check valve.

[0076] This type of structure has the following deficiencies:

[0077] a. The switching between the main flow channel and the bypass circuit of the sliding type air discharge check valve is completely achieved by the swing of the fork rod 79, which requires a relatively high assembly accuracy and a relatively high technical level of the assembly workers.

[0078] b. During each opening and closing process, the small valve flap 80 and the bypass valve seat 81 both generate sliding friction, which is extremely likely to scratch the sealing surface, affecting the sealing effect, resulting in leakage of the bypass circuit of the sliding type air discharge check valve, and it is more likely that the small valve flap 80 and the bypass valve seat 81 get stuck, resulting in the inability to close the main flow channel of the sliding type air discharge check valve and the overall failure of the valve.

[0079] The novel air-discharging check valve 100 of the present invention has a double bypass structure. The main valve flap assembly 3 is provided with a first spring 36 and a spring cover 37. The first spring 36 can be compressed within a certain range. At the initial stage of valve opening, the spring force of the first spring 36 is greater than the elastic force transmitted by the second spring 50 through a plurality of crank bodies 52. Under the action of the medium force, the second spring 50 is first compressed. Since the sliding stroke of the main valve flap assembly 3 is much larger than the sliding stroke of the main valve core rod 19, when the main valve flap assembly 3 slides to the main passage 13, the inlet side bypass 10 is completely closed, as Figure 1 shown in the state. After the second spring 50 cannot be compressed further due to the limit, at this time, the main valve flap assembly 3 has not reached the fully open position and will continue to compress the first spring 36 until it is opened to the full stroke. When the working condition changes and the main passage needs to be closed, the first spring 36 rebounds first. After the first spring 36 rebounds in place, the second spring 50 continues to rebound. A plurality of crank bodies 52 push the main valve flap assembly 3 to slide leftward, so that the second hard alloy sealing surface 43 abuts against the first hard alloy sealing surface 15 for sealing. The spring seat 49 drives the main valve core rod 19 to slide leftward, and a plurality of bypass sealing flanges 27 are separated from a plurality of sealing convex rings 21 one by one, and the inlet side bypass 10 is opened.

[0080] When the main valve flap assembly 3 is in the fully open position, in the case of fluctuations in the operating conditions, the first spring 36 rebounds first, the second spring 50 remains stationary, and the inlet side bypass 10 remains closed, overcoming the leakage of the inlet side bypass caused by the fluctuations in the working conditions and improving the sealing performance of the inlet side bypass.

[0081] The valve rod assembly 2 further includes a locking sleeve 17. The inner hole of the throttle sleeve 18 is composed of a throttle hole 20, a balance hole 23 and a first positioning hole 24 that are coaxially connected in sequence from left to right. A plurality of sealing convex rings 21 are arranged at intervals on the side wall of the throttle hole 20. A plurality of first flow holes 22 are arranged circumferentially on the side wall of the balance hole 23. The locking sleeve 17 is fixed to the left end of the throttle sleeve 18. The locking sleeve 17 closes the left end opening of the throttle sleeve 18. The locking sleeve 17 is provided with a second positioning hole 32 and a plurality of second flow holes 33. The main valve core rod 19 includes a second positioning section 25, a sealing section 26, a balance section 28, a first positioning section 29, a connecting section 30 and a third positioning section 31 that are coaxially connected in sequence from left to right. A plurality of bypass sealing flanges 27 are arranged at intervals on the sealing section 26. The second positioning section 25 is in sliding fit with the second positioning hole 32. An annular cavity is formed between the outer periphery of the balance section 28 and the side wall of the balance hole 23. The left part of the first positioning section 29 is in sliding fit with the first positioning hole 24. The annular cavity is communicated with the left valve cavity 12 through a plurality of first flow holes 22.

[0082] The stepped groove is composed of a guiding groove 38, a flow-through groove 39, and a balancing groove 40 that are coaxially connected in sequence from left to right. The diameter of the guiding groove 38 is smaller than those of the flow-through groove 39 and the balancing groove 40. The side wall of the guiding groove 38 is in sliding fit with the right outer part of the outer circumference of the throttle sleeve 18. The first positioning section 29 is in sliding and sealing fit with the inner circumference of the limiting annular wall 44. There are gaps between the side walls of the flow-through groove 39 and the balancing groove 40 and the outer circumference of the first positioning section 29. A number of third flow-through holes 41 are circumferentially arranged on the side wall of the flow-through groove 39. The left valve cavity 12 is communicated with the balancing groove 40 through a number of third flow-through holes 41 and the flow-through groove 39 in sequence to keep the pressure in the balancing groove 40 consistent with that in the left valve cavity 12. The right part of the first positioning section 29 passes through the inner circumference of the limiting annular wall 44 and the fourth positioning hole 47. The first positioning section 29 is in sliding fit with the fourth positioning hole 47. The first spring 36 is sleeved on the first positioning section 29.

[0083] A concave stop 16 is provided on the right end face of the pipe body of the outlet side bypass 11. The concave stop 16 is coaxial with the outlet side bypass 11. A positioning flange 53 is provided at the right end of the crank seat 48. The bypass reducing flange 7 presses the positioning flange 53 into the concave stop 16, and the positioning flange 53 is in stop fit with the concave stop 16.

[0084] The throttling assembly 6 includes a first throttling ring 58 and a number of throttling orifice plates 59. The first throttling ring 58 and the number of throttling orifice plates 59 are arranged in sequence from left to right on the inner hole diameter of the bypass reducing flange 7. Axial gaps are provided between the first throttling ring 58 and the adjacent throttling orifice plate 59 and between two adjacent throttling orifice plates 59. A number of fifth flow-through holes 60 are provided on the first throttling ring 58.

[0085] A separating ring structure 62 that protrudes leftward is provided at the edge of the throttling orifice plate 59. The throttling orifice plate 59 abuts against the adjacent throttling orifice plate 59 or throttling ring on the left through the separating ring structure 62, so that a gap is formed between two adjacent throttling orifice plates 59, and a gap is also formed between the throttling ring and the adjacent throttling orifice plate 59, facilitating the medium to pass through the throttling holes 20 on the throttling ring and the number of throttling orifice plates 59 in sequence.

[0086] The inner hole of the bypass reducing flange 7 is a stepped hole. A first snap ring 63 is provided in the inner hole of the bypass reducing flange 7. The first throttling ring 58 and the number of throttling orifice plates 59 are axially limited by the snap ring and the inner hole step of the bypass reducing flange 7.

[0087] The backpressure adjustment assembly 4 includes a connecting seat 64, a sealing plate 65, a third spring 66, and an adjustment cover 67. The connecting seat 64 is arranged at the left end of the through diameter of the inlet side bypass 10. The connecting seat 64 is a sleeve-shaped member. The connecting seat 64 is provided with a right end wall. A sixth flow hole 68 is formed in the right end wall of the connecting seat 64. The inner circumference of the connecting seat 64 is threadedly connected to the outer circumference of the adjustment cover 67. The adjustment cover 67 is provided with a plurality of seventh flow holes. The adjustment cover 67 presses the sealing plate 65 against the right end wall of the connecting seat 64 through the third spring 66 to close the fifth flow hole 60. The inlet side bypass 10 is a stepped hole. A second snap ring 69 is arranged in the inlet side bypass 10. The backpressure adjustment assembly 4 is axially limited by the second snap ring 69 and the inner hole step of the inlet side bypass 10.

[0088] The connecting seat 64 and the adjustment cover 67 are threadedly connected. The adjustment cover 67 compresses the third spring 66. Under the spring force of the third spring 66, the sealing plate 65 can close the fifth flow hole 60. By adjusting the relative position of the connecting seat 64 and the adjustment cover 67, the minimum pressure required to open the sealing plate 65 can be controlled, and a pressure chamber is formed in front of the sealing plate 65, thereby reducing the pressure difference between the two ends of the valve stem assembly 2 and reducing the occurrence of cavitation phenomenon, so as to better protect the valve stem assembly 2 and improve the service life of the valve.

[0089] By designing the outlet side bypass 11, the novel air exhaust check valve of the present invention increases the use functions of the valve. Compared with the traditional air exhaust check valve, a new bypass pipeline is added, which can be used as a preheating pipeline or a reflux pipeline. Also, according to needs, the bypass flange can be replaced with a blind plate to make the valve function the same as that of the traditional air exhaust check valve.

[0090] The novel air exhaust check valve of the present invention realizes the opening and closing of the bypass circuit through the mechanical properties of the second spring 50, and the performance is more stable; the main valve flap assembly 3 is designed with a first spring 36, which overcomes the leakage of the inlet side bypass caused by working condition fluctuations and improves the sealing performance of the inlet side bypass.

[0091] By designing the backpressure adjustment assembly 4, the novel air exhaust check valve of the present invention reduces the pressure difference between the two ends of the valve stem assembly 2 and reduces the occurrence of cavitation phenomenon, so as to better protect the valve stem assembly 2 and improve the performance stability and service life of the inlet side bypass 10.

[0092] The main function of the novel air exhaust check valve of the present invention is realized through spring force, and the requirements for processing accuracy and assembly are relatively low, and the performance is more stable. All internal parts are installed from one side. During the maintenance process, only the bypass reducing flange 7 needs to be disassembled, and then all internal parts can be disassembled in sequence, which is convenient for installation and maintenance.

[0093] Example 2: As Figures 1 to 17As shown in the figure, a method for using a new type of air exhaust check valve is realized by relying on the new type of air exhaust check valve described in Embodiment 1. The new type of air exhaust check valve is the air exhaust check valve 100. The deaerator 200 is connected to the main path inlet 8 through the first main pipeline 410. A water pump 400 is provided on the first main pipeline 410. The main path outlet 9 is connected to the boiler 300 through the second main pipeline 510. A first shut-off valve 500 is provided on the second main pipeline 510. The inlet side bypass 10 is connected to the deaerator 200 through the first bypass pipeline 710. The outlet side bypass 11 is connected to the boiler 300 through the second bypass pipeline 610. A second shut-off valve 600 is provided on the second bypass pipeline 610. The second bypass pipeline 610 is used as a preheating pipeline.

[0094] During the start-up stage of the system, first close the first shut-off valve 500 and open the second shut-off valve 600. At this time, after the main path valve flap assembly 3 is opened, the medium enters the boiler 300 from the outlet side bypass 11, and passes through the throttling assembly 6 for multi-stage pressure reduction, which can control the medium to enter the boiler 300 with a smaller pressure and flow rate, playing a preheating role, ensuring the normal operation of the boiler 300 and extending the service life of the boiler.

[0095] When the conditions for normal start-up of operation are reached, open the first shut-off valve 500 and close the second shut-off valve 600. At this time, after the main path valve flap assembly 3 is opened, the medium enters the boiler 300 from the second main pipeline 510 with normal operating condition parameters.

[0096] When the unit is operating at full load, under the action of the medium force, overcoming the spring force of the second spring 50, the main path valve flap assembly 3 slides to the right to open, driving several crank bodies 52 to rotate. The several crank bodies 52 push the spring seat 49 to the right. Since the spring seat 49 is connected to the main valve core rod 19, the main valve core rod 19 is driven to slide to the right. At this time, several bypass sealing flanges 27 are in one-to-one contact and sealing with several sealing rings 21, the inlet side bypass 10 is closed, and the medium enters the boiler 300 from the second main pipeline 510 or the second bypass pipeline 610.

[0097] When the unit is operating at low load, the medium force decreases. Under the action of the spring force of the second spring 50, the main valve core rod 19 slides to the left. At this time, the inlet side bypass 10 is opened; the main valve core rod 19 drives the spring seat 49 to move to the left, and the spring seat 49 drives the crank body 52 to rotate, closing the main path valve flap assembly 3. The medium only returns to the deaerator 200 after multi-stage pressure reduction through the eddy current pressure reduction flow channel.

[0098] Embodiment 3: As Figures 1 to 16 、 Figure 18As shown in the figure, a method for using a new type of air discharge check valve is realized based on the new type of air discharge check valve described in Embodiment 1. The new type of air discharge check valve is the air discharge check valve 100. The deaerator 200 is connected to the main path inlet 8 through the first main pipeline 410. A water pump 400 is provided on the first main pipeline 410. The main path outlet 9 is connected to the boiler 300 through the second main pipeline 510. A first shut-off valve 500 is provided on the second main pipeline 510. The inlet side bypass 10 is connected to the deaerator 200 through the first bypass pipeline 710. The outlet side bypass 11 is connected to the deaerator 200 through the second bypass pipeline 610. A second shut-off valve 600 is provided on the second bypass pipeline 610. The second bypass pipeline 610 is used as a return pipeline.

[0099] During normal system operation, the first shut-off valve 500 is opened and the second shut-off valve 600 is closed. At this time, after the main path valve flap assembly 3 is opened, the medium enters the boiler 300 from the second main pipeline 510 under normal operating condition parameters.

[0100] When an emergency condition occurs and the parameters of the water pump 400 cannot be quickly reduced to the preset parameters, the inlet side bypass 10 cannot be opened at this time. The first shut-off valve 500 can be closed and the second shut-off valve 600 can be opened to allow the medium to flow back to the deaerator 200 after being multi-stage decompressed by the throttling assembly 6 from the outlet side bypass 11.

[0101] When the unit is operating at full load, under the action of the medium force, overcoming the spring force of the second spring 50, the main path valve flap assembly 3 slides to the right to open, driving several crank bodies 52 to rotate. Several crank bodies 52 push the spring seat 49 to the right. Since the spring seat 49 is connected to the main valve core rod 19, the main valve core rod 19 is driven to slide to the right. At this time, several bypass sealing flanges 27 are in one-to-one correspondence with several sealing rings 21 to seal. The inlet side bypass 10 is closed, and the medium enters the boiler 300 from the second main pipeline 510 or the second bypass pipeline 610. Under emergency conditions, the medium flows back from the second bypass pipeline 610 to the deaerator 200.

[0102] When the unit is operating at low load, the medium force decreases. Under the action of the spring force of the second spring 50, the main valve core rod 19 slides to the left. At this time, the inlet side bypass 10 is opened; the main valve core rod 19 drives the spring seat 19 to move to the left, and the spring seat 49 drives the crank body 52 to rotate to close the main path valve flap assembly 3. The medium only flows back to the deaerator 200 after being multi-stage decompressed through the eddy current pressure reduction flow channel.

[0103] The above embodiments are only illustrative descriptions of the present invention and do not limit its protection scope. Those skilled in the art can also make partial changes to it as long as they do not exceed the spirit of the present invention, and they are all within the protection scope of the present invention.

Claims

1. A new type of air exhaust check valve, characterized in that: It comprises a first valve body (1), a valve stem assembly (2), a main valve disc assembly (3), a crank assembly (5), a throttling assembly (6) and a back pressure adjustment assembly (4); The first valve body (1) is in a four-way shape, the lower opening of the first valve body (1) is a main road inlet (8), the upper opening of the first valve body (1) is a main road outlet (9), the left opening of the first valve body (1) is an inlet side bypass (10), and the right opening of the first valve body (1) is an outlet side bypass (11). The main road inlet (8) and the inlet side bypass (10) are connected through a left valve chamber (12), the main road outlet (9) and the outlet side bypass (11) are connected through a right valve chamber (14), the left valve chamber (12) and the right valve chamber (14) are connected through a main road channel (13), and a first hard alloy sealing surface (15) is welded on the main road channel (13); The valve stem assembly (2) comprises a main valve core rod (19) and a throttling sleeve (18). The left part of the throttling sleeve (18) is sealed and connected to the right part of the inlet side bypass (10). The main valve core rod (19) and the throttling sleeve (18) are slidably matched. A plurality of sealing convex rings (21) are arranged at intervals on the inner hole of the throttling sleeve (18). A plurality of bypass sealing flanges (27) are arranged at intervals on the outer periphery of the main valve core rod (19). The plurality of bypass sealing flanges (27) and the plurality of sealing convex rings (21) are correspondingly abutted and sealed or separated. When the bypass sealing flanges (27) are separated from the corresponding sealing convex rings (21), a vortex pressure reduction flow channel is formed between the main valve core rod (19) and the throttling sleeve (18). The left valve chamber (12) is connected to the left part of the inlet side bypass (10) through the vortex pressure reduction flow channel. The main path valve flap assembly (3) includes a first main path valve flap (34), an annular pressing plate (35), a spring cover (37) and a first spring (36). A stepped groove is provided on the left end face of the first main path valve flap (34), and the stepped groove is in sliding fit with the outer periphery of the right part of the throttle sleeve (18). A main sealing flange (42) is provided at the right outer periphery of the first main path valve flap (34), and a second cemented carbide sealing surface (43) is surfacing welded on the main sealing flange (42). The second cemented carbide sealing surface (43) abuts and seals or separates from the first cemented carbide sealing surface (15). A sliding counterbore (45) is provided on the right end face of the first main path valve flap (34). The annular pressing plate (35) is coaxially fixed at the notch of the sliding counterbore (45). The spring cover (37) is a cylindrical member with an open left end. A sliding flange (46) is provided at the left end of the spring cover (37). The axial thickness of the sliding flange (46) is less than the depth of the sliding counterbore (45). The outer periphery of the sliding flange (46) is in sliding fit with the side wall of the sliding counterbore (45). The inner periphery of the annular pressing plate (35) is in sliding fit with the outer periphery of the spring cover (37). A limiting annular wall (44) is provided between the stepped groove and the sliding counterbore (45). The main valve core rod (19) is in sliding and sealing fit with the inner periphery of the limiting annular wall (44). The first spring (36) is provided inside the spring cover (37). The first spring (36) is sleeved on the main valve core rod (19). The two ends of the first spring (36) respectively abut against the limiting annular wall (44) and the right end wall of the spring cover (37); The crank assembly (5) includes a crank seat (48). The crank seat (48) is a tubular sleeve-shaped member. A plurality of connecting ears are provided at the left end of the crank seat (48). One end of a plurality of crank bodies (52) is respectively hinged to the plurality of connecting ears. The crank seat (48) is in sealing fit with the outlet side bypass (11). The other ends of the plurality of crank bodies (52) all abut against the right end wall of the spring cover (37); The large diameter end of the bypass reducing flange (7) is connected to the pipe body of the outlet side bypass (11). The bypass reducing flange (7) is in sealing fit with the crank seat (48). The throttle assembly (6) is arranged on the inner hole diameter of the bypass reducing flange (7); The spring seat (49), the second spring (50) and the throttle assembly (6) abut against each other from left to right. The spring seat (49) is bowl-shaped. The rim end (57) of the spring seat (49) faces left and abuts against the right side of the plurality of crank bodies (52). A connecting screw hole (55) and a plurality of fourth flow holes (56) are provided on the bottom (54) of the bowl of the spring seat (49). The main valve core rod (19) is in threaded fit with the connecting screw hole (55) and is locked by a lock nut (51). The second spring (50) is sleeved on the main valve core rod (19). A third positioning hole (61) is provided on the left end face of the first throttle ring (58). The main valve core rod (19) is in sliding fit with the third positioning hole (61); The back pressure adjusting assembly (4) is arranged at the left end of the diameter of the inlet side bypass (10).

2. The novel air exhaust check valve according to claim 1, characterized in that: The valve stem assembly (2) further includes a locking sleeve (17). The inner hole of the throttle sleeve (18) consists of a throttle hole (20), a balance hole (23), and a first positioning hole (24) that are coaxially connected in sequence from left to right. A number of sealing convex rings (21) are arranged at intervals on the side wall of the throttle hole (20). A number of first flow holes (22) are arranged circumferentially on the side wall of the balance hole (23). The locking sleeve (17) is fixed to the left end of the throttle sleeve (18). The locking sleeve (17) closes the left end opening of the throttle sleeve (18). The locking sleeve (17) is provided with a second positioning hole (32) and a number of second flow holes (33). The main valve stem (19) includes a second positioning section (25), a sealing section (26), a balance section (28), a first positioning section (29), a connecting section (30), and a third positioning section (31) that are coaxially connected in sequence from left to right. A number of bypass sealing flanges (27) are arranged at intervals on the sealing section (26). The second positioning section (25) is in sliding fit with the second positioning hole (32). An annular cavity is formed between the outer circumference of the balance section (28) and the side wall of the balance hole (23). The left part of the first positioning section (29) is in sliding fit with the first positioning hole (24). The annular cavity communicates with the left valve cavity (12) through a number of first flow holes (22).

3. A novel air discharge check valve according to claim 2, characterized in that: The stepped groove is composed of a guide groove (38), a flow groove (39), and a balance groove (40) that are coaxially connected in sequence from left to right. The diameter of the guide groove (38) is smaller than the diameters of the flow groove (39) and the balance groove (40). The side wall of the guide groove (38) is in sliding fit with the outer circumference of the throttle sleeve (18). The first positioning section (29) is in sliding and sealing fit with the inner circumference of the limiting annular wall (44). A number of third flow holes (41) are arranged circumferentially on the side wall of the flow groove (39). The left valve cavity (12) communicates with the balance groove (40) through a number of third flow holes (41) and the flow groove (39) in sequence. The first spring (36) is sleeved on the first positioning section (29).

4. A novel air exhaust check valve according to claim 1, characterized in that: A concave stop (16) is provided on the right end face of the pipe body of the outlet side bypass (11). The concave stop (16) is coaxial with the outlet side bypass (11). A positioning flange (53) is provided at the right end of the crank seat (48). The bypass reducing flange (7) presses the positioning flange (53) into the concave stop (16). The positioning flange (53) is in stop fit with the concave stop (16).

5. A novel air discharge check valve according to claim 1, characterized in that: The throttle assembly (6) includes a first throttle ring (58) and a number of throttle orifice plates (59). The first throttle ring (58) and the number of throttle orifice plates (59) are arranged in sequence on the inner hole diameter of the bypass reducing flange (7) from left to right. An axial gap is provided between the first throttle ring (58) and the adjacent throttle orifice plate (59) and between adjacent two throttle orifice plates (59). A number of fifth flow holes (60) are provided on the first throttle ring (58).

6. The novel air exhaust check valve according to claim 5, characterized in that: The edge of the throttle orifice plate (59) is provided with a separating ring structure (62) that protrudes leftward. The throttle orifice plate (59) abuts against the adjacent throttle orifice plate (59) or throttle ring on the left through the separating ring structure (62).

7. A novel air discharge check valve according to claim 6, characterized in that: The inner hole of the bypass reducing flange (7) is a stepped hole. A first snap ring (63) is provided in the inner hole of the bypass reducing flange (7). The first throttle ring (58) and several throttle orifice plates (59) are axially limited by the snap ring and the inner hole step of the bypass reducing flange (7).

8. A novel air exhausting check valve according to any one of claims 1-7, characterized in that: The back pressure adjustment assembly (4) includes a connection seat (64), a sealing plate (65), a third spring (66) and an adjustment cover (67). The connection seat (64) is arranged at the left end of the through diameter of the inlet side bypass (10). The connection seat (64) is a sleeve-shaped member. The connection seat (64) is provided with a right end wall. A sixth flow hole (68) is opened on the right end wall of the connection seat (64). The inner circumference of the connection seat (64) is threadedly connected with the outer circumference of the adjustment cover (67). The adjustment cover (67) is provided with several seventh flow holes. The adjustment cover (67) presses the sealing plate (65) against the right end wall of the connection seat (64) through the third spring (66) to close the fifth flow hole (60). The inlet side bypass (10) is a stepped hole. A second snap ring (69) is provided in the inlet side bypass (10). The back pressure adjustment assembly (4) is axially limited by the second snap ring (69) and the inner hole step of the inlet side bypass (10).

9. A method of using a new type of air discharge check valve, which is realized by relying on the new type of air discharge check valve described in any one of claims 1-8, and is characterized in that: The deaerator (200) is connected to the main path inlet (8) through the first main pipeline (410). A water pump (400) is provided on the first main pipeline (410). The main path outlet (9) is connected to the boiler (300) through the second main pipeline (510). A first shut-off valve (500) is provided on the second main pipeline (510). The inlet side bypass (10) is connected to the deaerator (200) through the first bypass pipeline (710). The outlet side bypass (11) is connected to the boiler (300) through the second bypass pipeline (610). A second shut-off valve (600) is provided on the second bypass pipeline (610). The second bypass pipeline (610) is used as a preheating pipeline.

10. A method of using a new type of air discharge check valve, which is realized based on the new type of air discharge check valve described in any one of claims 1-8, and is characterized in that: The deaerator (200) is connected to the main path inlet (8) through the first main pipeline (410). A water pump (400) is provided on the first main pipeline (410). The main path outlet (9) is connected to the deaerator (200) through the second main pipeline (510). A first shut-off valve (500) is provided on the second main pipeline (510). The inlet side bypass (10) is connected to the deaerator (200) through the first bypass pipeline (710). The outlet side bypass (11) is connected to the deaerator (200) through the second bypass pipeline (610). A second shut-off valve (600) is provided on the second bypass pipeline (610). The second bypass pipeline (610) is used as a return pipeline.

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