External connection structure of boiler feed pump balance pipe

Abstract

The invention belongs to the technical field of centrifugal pumps, and provides a boiler feed pump balance pipe external connection structure which comprises a pump body, a balance pipe, a stop valve, a deaerator and a pressure gauge. A balance cavity used for balancing leakage pressure in the pump is formed in the pump body. The balance pipe is communicated with the balance cavity; the stop valve is connected to one end of the balance pipe away from the pump body; the deaerator is connected to the stop valve and can adjust the opening degree of a connecting channel between the deaerator and the balance pipe through the stop valve. The pressure gauge is arranged on the balance pipe and used for displaying the pressure value in the balance pipe.

Description

Technical Field

[0001] The present application belongs to the technical field of centrifugal pumps, and in particular, relates to an external connection structure for a balance pipe of a boiler feed water pump. Background Art

[0002] In the design of traditional boiler feed water pumps, a balance chamber is usually set on the pump cover at the non-drive end to accommodate the pumping medium (boiler water) leaking from the balance drum on the pump body. In order to reduce the pressure in the balance chamber, a balance pipe is usually connected between the balance chamber and the pump suction port to return the leaked liquid in the balance chamber to the pump suction port, so that the pressure of the balance chamber at the non-drive end is equal to the pressure of the pump suction port.

[0003] However, the boiler feed pump needs to operate at the minimum flow condition for a long time. At this time, the boiler water in the balance chamber is continuously heated up, causing its saturated vapor pressure to increase significantly. Once the saturated vapor pressure exceeds the pump suction pressure, and the traditional design is still used to directly connect the balance pipe to the pump suction, the pressure at the pump inlet will be lower than the saturated vapor pressure of the medium being returned, which will cause severe cavitation to the first-stage impeller and corresponding components. Cavitation not only causes cavitation erosion on the impeller surface and reduces the flow channel efficiency, but also induces pump vibration, noise and component damage, causing serious damage to the impeller and pump, and reducing the service life of the pump. Therefore, it is necessary to solve the above technical problems. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a boiler feed water pump balance pipe external connection structure to solve the technical problem of serious cavitation of the boiler feed water pump in the prior art.

[0005] In order to achieve the above-mentioned purpose, the technical solution adopted in this application is: to provide a boiler feed water pump balance pipe external connection structure, including: A pump body, forming a balancing chamber for balancing the leakage pressure inside the pump; A balance pipe, connected to the balance chamber; A stop valve connected to an end of the balance pipe away from the pump body; A deaerator, connected to the stop valve and capable of adjusting the opening of the connection passage between the deaerator and the balance pipe through the stop valve, so that the pressure in the balance chamber is greater than the suction port pressure of the boiler feed water pump when the boiler feed water pump is in the minimum flow condition. Assuming that the suction port pressure of the boiler feed water pump is P in the minimum flow condition, the pressure in the balance chamber is: P+ (0.15MPa-0.2MPa); A pressure gauge is arranged on the balance pipe and is used to display the pressure value in the balance pipe.

[0006] Optionally, the stop valve comprises a valve body, a valve stem movably mounted on the valve body, and a rotating disk connected to the valve stem, and further comprises a hollow screw movably sleeved on the valve stem, and a locking nut and a nut sleeve respectively threadedly connected to the hollow screw; The hollow screw is located between the turntable and the valve body and is used to abut against the turntable. The thread of the hollow screw used to connect the locking nut and the nut sleeve is coaxial with the valve stem. The nut sleeve is located between the locking nut and the valve body and is used to abut against the nut sleeve and the valve body respectively.

[0007] Optionally, an enlarged portion is formed at one end of the hollow screw near the rotating disk, and a radial dimension of the enlarged portion in the radial direction of the valve stem is larger than an outer diameter of a thread of the hollow screw.

[0008] Optionally, the locking nut and the nut sleeve do not exceed the enlarged portion in the radial direction of the valve stem.

[0009] Optionally, the boiler feed water pump balance pipe external connection structure further includes a branch pipe and a safety valve arranged on the branch pipe and used to control the opening and closing of the branch pipe; The branch pipe is communicated with the balance pipe, and the safety valve has a preset pressure threshold and can open the branch pipe when the pressure in the branch pipe reaches the pressure threshold.

[0010] The beneficial effect of the boiler feed water pump balance pipe external connection structure provided in the present application is that: compared with the prior art, in the boiler feed water pump balance pipe external connection structure provided in the present application, the balance pipe connected to the balance chamber on the pump body is connected to the deaerator through a stop valve. Since the stop valve can adjust the opening of the connecting passage between the balance pipe and the deaerator, and since the pressure gauge arranged on the balance pipe can display the pressure value in the balance pipe, the operator can adjust the stop valve according to the pressure gauge and keep the pressure in the balance pipe and the balance chamber within the target range. In this way, the balance pipe in the present application no longer needs to be connected to the suction port of the pump body, thereby effectively solving the serious cavitation problem of traditional feed water pumps. At the same time, the leaked liquid is transported to the deaerator for reuse, which is far superior to the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0012] Figure 1 This is a schematic diagram of the connection principle of the external connection structure of the boiler feed water pump balance pipe in the embodiment of the present application; Figure 2 It is a partial structural cross-sectional view of the external connection structure of the balance pipe of the boiler feed water pump in the embodiment of the present application; Figure 3 It is a cross-sectional view of the overall structure of the stop valve in the embodiment of the present application.

[0013] Among them, the figure marks in the figure are: 100, pump body; 101, balance chamber; 200, balance pipe; 300, stop valve; 301, valve body; 302, valve stem; 303, turntable; 304, hollow screw; 305, locking nut; 306, nut sleeve; 307, expansion part; 400, deaerator; 500, pressure gauge; 600, branch pipe; 700, safety valve. DETAILED DESCRIPTION

[0014] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0015] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0016] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0017] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0018] Please also read Figures 1 to 3 Now, a boiler feed water pump balance pipe external connection structure provided in an embodiment of the present application is described. The boiler feed water pump balance pipe external connection structure includes a pump body 100, a balance pipe 200, a stop valve 300, a deaerator 400 and a pressure gauge 500. Among them: The pump body 100 forms a balancing chamber 101 for balancing the leakage pressure inside the pump; the balancing pipe 200 is connected to the balancing chamber 101; the stop valve 300 is connected to the end of the balancing pipe 200 away from the pump body 100; the deaerator 400 is connected to the stop valve 300 and can adjust the opening of the connecting passage between itself and the balancing pipe 200 through the stop valve 300, so that the pressure in the balancing chamber 101 of the boiler feed water pump is greater than the suction port pressure of the boiler feed water pump when the boiler feed water pump is in the minimum flow condition. Assuming that the suction port pressure of the boiler feed water pump is P under the minimum flow condition, the pressure in the balancing chamber 101 is: P+ (0.15MPa~0.2MPa); the pressure gauge 500 is set on the balancing pipe 200 and is used to display the pressure value in the balancing pipe 200.

[0019] According to the above structure provided in the present embodiment, in the external connection structure of the balance pipe of the boiler feed water pump provided in the present embodiment, the balance pipe 200 connected to the balance chamber 101 on the pump body 100 is connected to the deaerator 400 through the stop valve 300. Since the stop valve 300 can adjust the opening of the connection passage between the balance pipe 200 and the deaerator 400, and since the pressure gauge 500 arranged on the balance pipe 200 can display the pressure value in the balance pipe 200, the operator can adjust the stop valve 300 according to the pressure gauge 500 and keep the pressure in the balance pipe 200 and the balance chamber 101 within the target range. In this way, the balance pipe 200 in the present embodiment does not need to be directly connected to the suction port of the pump body 100, and the liquid in the balance chamber 101 can be smoothly drawn out and further processed by the deaerator 400 for reuse. While realizing the discharge and reuse of the liquid medium in the balance chamber 101, the serious cavitation problem of the traditional feed water pump is effectively solved. At the same time, the leaked liquid is transported to the deaerator 400 for reuse, which is far superior to the existing technology.

[0020] In this embodiment, after the boiler feed water pump is installed, the stop valve 300 is fully opened, and the boiler feed water pump is operated at the minimum flow rate, and then the opening of the stop valve 300 is gradually reduced, and the indication of the pressure gauge 500 is observed. Since the value displayed on the pressure gauge 500 is the pressure in the balance chamber 101, and since the liquid leaking from the balance drum of the boiler feed water pump into the balance chamber 101 is a high-pressure liquid, when the stop valve 300 is fully opened, the balance pipe 200 is equivalent to completely relieving the pressure of the balance chamber 101. At this time, the balance chamber 101 is The pressure in the balance chamber 101 is the same as the pressure at the inlet of the boiler feed water pump. When the opening of the stop valve 300 is gradually reduced to limit the liquid flow out of the stop valve 300 to the deaerator 400, the actual pressure in the balance chamber 101 can be adjusted, so that the pressure value in the balance chamber 101 is greater than the pressure at the inlet of the boiler feed water pump, and the greater value is between 0.15MPa and 0.2MPa. The median value is usually taken during adjustment, that is, the greater value is 0.175MPa. Its significance is that: on the one hand, the balance chamber The pressure value in 101 is maintained at a positive pressure of 0.15MPa to 0.2MPa greater than the pressure at the suction port of the boiler feed pump, so that there is a set basic pressure difference between the discharge side of the boiler feed pump and the balancing chamber 101, which is beneficial to reduce the liquid flow rate of the self-balancing drum leakage under the minimum flow condition to ensure the efficiency of the boiler feed pump under the minimum flow condition. On the other hand, when the boiler feed pump is operating under normal flow conditions and reaches the maximum leakage amount to increase the pressure in the balancing chamber 101, the increased pressure can increase the flow rate of the liquid through the stop valve 300, so that the liquid in the balancing chamber 101 can quickly flow out to the deaerator 400. In this way, the pressure in the balancing chamber 101 under normal flow conditions can be maintained within the set optimal allowable value range, avoiding excessive pressure increase on the mechanical seal of the boiler feed pump caused by the liquid in the balancing chamber 101, thereby ensuring the reliability of the mechanical seal, extending the service life of the mechanical seal, and further improving the protection effect on the non-drive end bearing of the boiler feed pump, so that the feed pump in this embodiment can be in a better operating state. In addition, the liquid medium input into the deaerator 400 through the balance pipe 200 is processed by the deaerator 400 series together with the unused water in the deaerator 400 and returned to the target state of low saturated vapor pressure. Then, it is re-supplied to the suction port of the pump body 100 from the output end of the deaerator 400 to achieve reuse. In this way, the external connection structure of the balance pipe of the boiler feed water pump in this embodiment can achieve the balancing function while avoiding the occurrence of serious cavitation. Here, the deaerator 400 is usually used as a processing equipment for the boiler water source, which is used to remove dissolved oxygen and other gases in the water and then pressurize it to the boiler through the boiler feed water pump. It is a prior art in the boiler water supply system and will not be elaborated here.

[0021] It can be understood that the pressure at the suction inlet of the boiler feed water pump can be observed by a pressure gauge arranged at the suction inlet.

[0022] In another embodiment of the present application, please refer to Figures 1 to 3 The stop valve 300 includes a valve body 301, a valve stem 302 movably mounted on the valve body 301, and a turntable 303 connected to the valve stem 302, and also includes a hollow screw 304 movably sleeved on the valve stem 302, and a locking nut 305 and a nut sleeve 306 respectively threadedly connected to the hollow screw 304; the hollow screw 304 is located between the turntable 303 and the valve body 301 and is used to abut against the turntable 303, the thread of the hollow screw 304 used to connect the locking nut 305 and the nut sleeve 306 is coaxial with the valve stem 302, and the nut sleeve 306 is located between the locking nut 305 and the valve body 301 and is used to abut against the nut sleeve 306 and the valve body 301 respectively.

[0023] According to the above structure provided in this embodiment, the valve stem 302 can flexibly adjust the opening of the connection passage between the balance pipe 200 and the deaerator 400 by moving along its own axial direction relative to the valve body 301. Since the set connection opening between the balance pipe 200 and the deaerator 400 needs to be maintained so that the pressure in the balance chamber 101 is 0.15MPa to 0.2MPa higher than the suction port pressure of the boiler feed water pump when the boiler feed water pump is at the minimum flow condition, the hollow screw 304 movably mounted on the valve stem 302 can limit the movement range of the valve stem 302 by abutting against the rotary disk 303 on the valve stem 302. It can be understood that when the nut sleeve 306 sandwiched between the locking nut 305 and the valve body 301 rotates relative to the hollow screw 304, the hollow screw 304 can be driven away from or close to the turntable 303 along the axial direction of the valve stem 302, and the locking nut 305 threadedly connected to the hollow screw 304 can limit the movement of the hollow screw 304 by pressing the nut sleeve 306 against the valve body 301. In this way, when the locking nut 305 is locked, the movement range of the valve stem 302 can be effectively limited, so that the minimum opening that meets the target can be formed between the balance pipe 200 and the deaerator 400. In this way, the external connection structure of the balance pipe of the boiler feed water pump in this embodiment can effectively prevent the occurrence of the situation where the stop valve 300 is closed due to misoperation by the on-site personnel, thereby better solving the problem of serious cavitation of the traditional feed water pump.

[0024] In another embodiment of the present application, please refer to Figures 1 to 3The hollow screw 304 forms an enlarged portion 307 at one end close to the rotary disk 303, and the radial dimension of the enlarged portion 307 in the radial direction of the valve stem 302 is larger than the thread outer diameter of the hollow screw 304. According to the above structure provided in this embodiment, the hollow screw 304 provided with the enlarged portion 307 can, on the one hand, make it easier for operators to operate the hollow screw 304 to rotate relative to the nut sleeve 306, and on the other hand, can also form a stable abutting relationship between the hollow screw 304 and the rotary disk 303, so that the boiler feed water pump balance pipe external connection structure in this embodiment can also better solve the problem of severe cavitation of the traditional feed water pump.

[0025] In another embodiment of the present application, please refer to Figures 1 to 3 , the locking nut 305 and the nut sleeve 306 do not exceed the expanded portion 307 in the radial direction of the valve stem 302. According to the above structure provided in this embodiment, the locking nut 305 and the nut sleeve 306 that do not exceed the expanded portion 307 in the radial direction of the valve stem 302 can effectively avoid human misoperation, so that the boiler feed water pump balance pipe external connection structure in this embodiment can also better solve the serious cavitation problem of the traditional feed water pump.

[0026] In another embodiment of the present application, please refer to Figures 1 to 3 The external connection structure of the balance pipe of the boiler feed water pump also includes a branch pipe 600 and a safety valve 700 arranged on the branch pipe 600 and used to control the opening and closing of the branch pipe 600; the branch pipe 600 is connected to the balance pipe 200, and the safety valve 700 has a preset pressure threshold and can open the branch pipe 600 when the pressure in the branch pipe 600 reaches the pressure threshold. According to the above structure provided in this embodiment, when the internal pressure of the balance pipe 200 is too large, the branch pipe 600 connected to the balance pipe 200 can open the safety valve 700 arranged thereon to relieve the pressure of the balance pipe 200, so that the boiler feed water pump in this embodiment can also fully guarantee the reliable and continuous operation of the boiler feed water pump when the balance chamber 101 is over-pressurized due to various accident conditions. It should be noted that the end of the branch pipe 600 away from the balance pipe 200 can be connected to the target position according to actual needs. For example, in the specific implementation process, the end of the branch pipe 600 away from the balance pipe 200 is connected to the flare port usually arranged on the traditional boiler feed water pump, which will not be repeated here.

[0027] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A boiler feed water pump balance pipe external connection structure, characterized in that: include: A pump body (100) forms a balancing chamber (101) for balancing leakage pressure inside the pump; A balancing pipe (200) communicates with the balancing chamber (101); A stop valve (300) connected to an end of the balance pipe (200) away from the pump body (100); a deaerator (400) connected to the stop valve (300) and capable of adjusting the opening of the connection passage between the deaerator and the balance pipe (200) through the stop valve (300), so that the pressure in the balance chamber (101) is greater than the suction port pressure of the boiler feed water pump when the boiler feed water pump is in the minimum flow condition. Assuming that the suction port pressure of the boiler feed water pump is P in the minimum flow condition, the pressure in the balance chamber (101) is: P+(0.15MPa-0.2MPa); A pressure gauge (500) is arranged on the balancing pipe (200) and is used to display the pressure value in the balancing pipe (200).

2. The boiler feed water pump balance pipe external connection structure according to claim 1, characterized in that: The stop valve (300) comprises a valve body (301), a valve stem (302) movably mounted on the valve body (301), and a rotating disk (303) connected to the valve stem (302), and also comprises a hollow screw (304) movably sleeved on the valve stem (302), and a locking nut (305) and a nut sleeve (306) respectively threadedly connected to the hollow screw (304); The hollow screw (304) is located between the rotating disk (303) and the valve body (301) and is used to abut against the rotating disk (303). The thread of the hollow screw (304) used to connect the locking nut (305) and the nut sleeve (306) is coaxial with the valve stem (302). The nut sleeve (306) is located between the locking nut (305) and the valve body (301) and is used to abut against the nut sleeve (306) and the valve body (301), respectively.

3. The boiler feed water pump balance pipe external connection structure according to claim 2, characterized in that: The hollow screw (304) forms an enlarged portion (307) at one end close to the rotating disk (303), and the radial dimension of the enlarged portion (307) in the radial direction of the valve stem (302) is larger than the outer diameter of the thread of the hollow screw (304).

4. The boiler feed water pump balance pipe external connection structure according to claim 3, characterized in that: The locking nut (305) and the nut sleeve (306) do not extend beyond the enlarged portion (307) in the radial direction of the valve stem (302).

5. The boiler feed water pump balance pipe external connection structure according to claim 1, characterized in that: The boiler feed water pump balance pipe external connection structure further includes a branch pipe (600) and a safety valve (700) arranged on the branch pipe (600) and used to control the opening and closing of the branch pipe (600); The branch pipe (600) is in communication with the balance pipe (200), and the safety valve (700) has a preset pressure threshold and is capable of opening the branch pipe (600) when the pressure in the branch pipe (600) reaches the pressure threshold.

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