External connection structure of boiler feed pump balance pipe

Abstract

The utility model 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] This application belongs to the field of centrifugal pump technology, and in particular relates to an external connection structure for a boiler feedwater pump balance pipe. Background Technology

[0002] In traditional boiler feed pump designs, a balancing chamber is typically installed on the pump cover at the non-drive end to contain the pumping medium (boiler water) leaking from the balancing drum on the pump body. To reduce the pressure within the balancing chamber, a balancing pipe is usually connected between the balancing chamber and the pump inlet to return the leaking liquid from the balancing chamber to the pump inlet, so that the pressure in the balancing chamber at the non-drive end is equal to the pressure at the pump inlet.

[0003] However, boiler feedwater pumps need to operate at minimum flow rate for extended periods. During this time, the boiler water in the balancing chamber experiences a significant increase in saturated vapor pressure due to continuous heating. If the saturated vapor pressure exceeds the pump inlet pressure, and the traditional design of directly connecting the balancing pipe to the pump inlet is still used, the pressure at the pump inlet will be lower than the saturated vapor pressure of the returned medium, leading to severe cavitation on the first-stage impeller and related components. Cavitation not only causes cavitation erosion on the impeller surface and reduces flow channel efficiency, but also induces pump vibration, noise, and component damage, severely damaging the impeller and pump and reducing its service life. Therefore, it is necessary to solve these technical problems. Summary of the Invention

[0004] The purpose of this application is to provide an external connection structure for the balance pipe of a boiler feedwater pump to solve the technical problem of severe cavitation in existing boiler feedwater pumps.

[0005] To achieve the above objectives, the technical solution adopted in this application is: to provide an external connection structure for a boiler feedwater pump balance pipe, comprising:

[0006] The pump body forms a balancing chamber to balance the leakage pressure inside the pump;

[0007] The balance tube is connected to the balance chamber;

[0008] A shut-off valve is connected to the end of the balance pipe furthest from the pump body;

[0009] A deaerator is connected to the shut-off valve and can adjust the opening of the connection passage between itself and the balance pipe through the shut-off valve so that the pressure in the balance chamber is greater than the inlet pressure of the boiler feedwater pump when the boiler feedwater pump is in minimum flow condition. Let the inlet pressure of the boiler feedwater pump in minimum flow condition be P, then the pressure in the balance chamber is: P + (0.15MPa ~ 0.2MPa).

[0010] A pressure gauge is installed on the balance tube and is used to display the pressure value inside the balance tube.

[0011] Optionally, the shut-off valve includes a valve body, a valve stem movably mounted on the valve body, and a turntable connected to the valve stem, and also includes a hollow screw movably fitted on the valve stem and a locking nut and a nut sleeve respectively threaded to the hollow screw;

[0012] 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 connecting 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.

[0013] Optionally, the hollow screw has an enlarged portion at one end near the turntable, and the radial dimension of the enlarged portion in the radial direction of the valve stem is greater than the outer diameter of the thread of the hollow screw.

[0014] Optionally, neither the locking nut nor the nut sleeved on the valve stem extends radially beyond the enlarged portion.

[0015] Optionally, the external connection structure of the boiler feed water pump balance pipe also includes a branch pipe and a safety valve disposed on the branch pipe for controlling the opening and closing of the branch pipe.

[0016] The branch pipe is connected to 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.

[0017] The beneficial effects of the external connection structure of the boiler feedwater pump balance pipe provided in this application are as follows: Compared with the prior art, in the external connection structure of the boiler feedwater pump balance pipe provided in this application, the balance pipe connected to the balance chamber on the pump body is connected to the deaerator through a shut-off valve. Since the shut-off valve can adjust the opening of the connection passage between the balance pipe and the deaerator, and since the pressure gauge installed on the balance pipe can display the pressure value in the balance pipe, the operator can adjust the shut-off 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 this application no longer needs to be connected to the suction port of the pump body, which can effectively solve the problem of severe cavitation of traditional feedwater pumps. At the same time, the leaked liquid is transported to the deaerator for reuse, which is far superior to the prior art. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram illustrating the connection principle of the external structure of the boiler feedwater pump balance pipe in the embodiments of this application;

[0020] Figure 2 This is a partial cross-sectional view of the external structure of the boiler feedwater pump balance pipe in an embodiment of this application;

[0021] Figure 3 This is a cross-sectional view of the overall structure of the shut-off valve in the embodiment of this application.

[0022] The reference numerals in the figures are as follows: 100, pump body; 101, balance chamber; 200, balance pipe; 300, shut-off valve; 301, valve body; 302, valve stem; 303, turntable; 304, hollow screw; 305, lock nut; 306, nut sleeve; 307, expansion section; 400, deaerator; 500, pressure gauge; 600, branch pipe; 700, safety valve. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0024] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0025] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Please refer to the following: Figures 1 to 3The following describes an external structure for a boiler feedwater pump balancing pipe provided in an embodiment of this application. This external structure includes a pump body 100, a balancing pipe 200, a shut-off valve 300, a deaerator 400, and a pressure gauge 500. Wherein:

[0028] The pump body 100 forms a balancing chamber 101 for balancing internal leakage pressure; the balancing pipe 200 is connected to the balancing chamber 101; the shut-off 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 shut-off valve 300 and can adjust the opening of the connection passage between itself and the balancing pipe 200 through the shut-off valve 300 so that the pressure in the balancing chamber 101 is greater than the inlet pressure of the boiler feedwater pump when the boiler feedwater pump is in minimum flow condition. Let the inlet pressure of the boiler feedwater pump in minimum flow condition be P, then the pressure in the balancing chamber 101 is: P + (0.15MPa ~ 0.2MPa); the pressure gauge 500 is installed on the balancing pipe 200 and is used to display the pressure value in the balancing pipe 200.

[0029] According to the structure provided in this embodiment, in the external connection structure of the boiler feedwater pump balance pipe provided in this embodiment, the balance pipe 200 connected to the balance chamber 101 on the pump body 100 is connected to the deaerator 400 through the shut-off valve 300. Since the shut-off 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 installed on the balance pipe 200 can display the pressure value inside the balance pipe 200, the operator can adjust the shut-off 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 embodiment, the balance pipe 200 no longer needs 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, it effectively solves the serious cavitation problem of traditional feedwater pumps. At the same time, the leaked liquid is transported to the deaerator 400 for reuse, which is far superior to the existing technology.

[0030] In this embodiment, after the boiler feedwater pump is installed, the shut-off valve 300 is fully opened, and the boiler feedwater pump is operated at the minimum flow rate. Then, the opening of the shut-off valve 300 is gradually reduced, and the reading 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 boiler feedwater pump balance drum into the balance chamber 101 is high-pressure liquid, when the shut-off valve 300 is fully open, the balance pipe 200 is equivalent to completely depressurizing the balance chamber 101. At this time, the balance chamber 101... The pressure inside chamber 101 is the same as the pressure at the boiler feedwater pump inlet. By gradually reducing the opening of the regulating shut-off valve 300 to limit the liquid flow from the shut-off valve 300 to the deaerator 400, the actual pressure in the balance chamber 101 can be adjusted. This allows the pressure in the balance chamber 101 to be greater than the pressure at the boiler feedwater pump inlet, with the maximum pressure being between 0.15 MPa and 0.2 MPa. Typically, the middle value is used during adjustment, i.e., the maximum pressure is 0.175 MPa. This is significant because, on the one hand, it balances the pressure in the balance chamber... The pressure inside chamber 101 is maintained at a positive pressure 0.15MPa to 0.2MPa higher than the pressure at the boiler feed pump inlet. This creates a set basic pressure difference between the boiler feed pump outlet side and the balancing chamber 101. This helps reduce the leakage of liquid from the self-balancing drum under minimum flow conditions, ensuring the efficiency of the boiler feed pump at minimum flow. On the other hand, when the boiler feed pump operates under normal flow conditions and reaches maximum leakage, causing the pressure inside the balancing chamber 101 to rise, the increased pressure increases the flow rate of liquid through the shut-off valve 300. This allows the liquid in the balancing chamber 101 to flow out quickly to the deaerator 400. Thus, under normal flow conditions, the pressure inside the balancing chamber 101 can be maintained within the set optimal allowable range. This prevents excessive pressure increase on the mechanical seal of the boiler feed pump caused by the liquid in the balancing chamber 101, ensuring the reliability of the mechanical seal, extending its service life, and further improving the protection effect on the non-drive end bearing of the boiler feed pump. Consequently, the feed pump in this embodiment can operate in a better state. In addition, the liquid medium input into the deaerator 400 through the balance pipe 200 is processed together with unused water in the deaerator 400 series and returned to the target state of low saturated steam pressure before being resupplyed to the suction port of the pump body 100 from the output end of the deaerator 400, thus achieving reuse. In this embodiment, the external connection structure of the boiler feed water pump balance pipe can achieve the function of balance while avoiding severe cavitation. Here, the deaerator 400 is usually used as a boiler water treatment device to remove dissolved oxygen and other gases from the water before it is pressurized and pumped to the boiler by the boiler feed water pump. This is existing technology in boiler water supply systems and will not be described in detail here.

[0031] Understandably, the pressure at the boiler feed pump inlet can be observed by a pressure gauge located at the inlet.

[0032] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 3 The shut-off 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. It also includes a hollow screw 304 movably fitted on the valve stem 302, and a locking nut 305 and a nut sleeve 306 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. 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.

[0033] According to the 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 relative to the valve body 301 along its own axial direction. Since the balance pipe 200 and the deaerator 400 also need to maintain a set connection opening so that the pressure in the balance chamber 101 is 0.15MPa to 0.2MPa higher than the suction pressure of the boiler feedwater pump when the boiler feedwater pump is in 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 turntable 303 on the valve stem 302. It is understandable that when the nut sleeve 306, sandwiched between the locking nut 305 and the valve body 301, rotates relative to the hollow screw 304, it can drive the hollow screw 304 away from or towards the turntable 303 along the axial direction of the valve stem 302. The locking nut 305, threaded onto the hollow screw 304, can further restrict the movement of the hollow screw 304 by pressing the nut sleeve 306 against the valve body 301. Thus, when the locking nut 305 is tightened, the movement range of the valve stem 302 is effectively limited, thereby allowing the balance pipe 200 and the deaerator 400 to form the minimum opening that meets the target. In this embodiment, the external connection structure of the boiler feedwater pump balance pipe can effectively prevent on-site personnel from accidentally closing the shut-off valve 300, thus better solving the problem of severe cavitation in traditional feedwater pumps.

[0034] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 3The hollow screw 304 has an enlarged portion 307 at one end near the turntable 303. 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. According to the structure provided in this embodiment, the hollow screw 304 with the enlarged portion 307 can make it easier for the operator to rotate the hollow screw 304 relative to the nut sleeve 306. On the other hand, it can also form a stable abutment relationship between the hollow screw 304 and the turntable 303. This also allows the external connection structure of the boiler feedwater pump balance pipe in this embodiment to better solve the problem of severe cavitation in traditional feedwater pumps.

[0035] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 3 The locking nut 305 and the nut sleeve 306 do not extend beyond the expansion portion 307 in the radial direction of the valve stem 302. According to the structure provided in this embodiment, the locking nut 305 and the nut sleeve 306, which do not extend beyond the expansion portion 307 in the radial direction of the valve stem 302, can effectively prevent human error. This also allows the external connection structure of the boiler feedwater pump balance pipe in this embodiment to better solve the problem of severe cavitation in traditional feedwater pumps.

[0036] In another embodiment of this application, please refer to [the relevant document / reference]. Figures 1 to 3 The external structure of the boiler feedwater pump balancing pipe also includes a branch pipe 600 and a safety valve 700 installed on the branch pipe 600 to control its opening and closing. The branch pipe 600 is connected to the balancing pipe 200, and the safety valve 700 has a preset pressure threshold and can open the branch pipe 600 when the pressure inside the branch pipe 600 reaches the pressure threshold. According to the structure provided in this embodiment, when the internal pressure of the balancing pipe 200 is too high, the safety valve 700 installed on the branch pipe 600 connected to the balancing pipe 200 can open to relieve pressure on the balancing pipe 200. This also ensures the reliable and continuous operation of the boiler feedwater pump in this embodiment when the balancing chamber 101 is overpressurized due to various accident conditions. It should be noted that the end of the branch pipe 600 away from the balancing pipe 200 can be connected to a target location as needed. For example, in specific implementation, the end of the branch pipe 600 away from the balancing pipe 200 is connected to the flare port usually installed on a traditional boiler feedwater pump, which will not be elaborated further here.

[0037] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. An external connection structure for a boiler feedwater pump balance pipe, characterized in that, include: The pump body (100) forms a balancing chamber (101) for balancing the leakage pressure inside the pump. A balance tube (200) is connected to the balance chamber (101); A shut-off valve (300) is connected to the end of the balance pipe (200) away from the pump body (100); A deaerator (400) is connected to the shut-off valve (300) and can adjust the opening of the connection passage between itself and the balance pipe (200) through the shut-off valve (300) so that the pressure in the balance chamber (101) is greater than the inlet pressure of the boiler feed pump when the boiler feed pump is in the minimum flow condition. Let the inlet pressure of the boiler feed pump in the minimum flow condition be P, then the pressure in the balance chamber (101) is: P + (0.15MPa ~ 0.2MPa). A pressure gauge (500) is installed on the balance tube (200) and is used to display the pressure value inside the balance tube (200).

2. The external connection structure of the boiler feedwater pump balance pipe as described in claim 1, characterized in that: The shut-off 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). It also includes a hollow screw (304) movably fitted on the valve stem (302) and a locking nut (305) and a nut sleeve (306) respectively threaded 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 hollow screw (304) is used to connect the locking nut (305) and the nut sleeve (306) with the thread 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 external connection structure of the boiler feedwater pump balance pipe as described in claim 2, characterized in that: The hollow screw (304) has an enlarged portion (307) at one end near the turntable (303), and the radial dimension of the enlarged portion (307) in the radial direction of the valve stem (302) is greater than the outer diameter of the thread of the hollow screw (304).

4. The external connection structure of the boiler feedwater pump balance pipe as described in 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 external connection structure of the boiler feedwater pump balance pipe as described in claim 1, characterized in that: The external structure of the boiler feed water pump balance pipe also includes a branch pipe (600) and a safety valve (700) installed 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.

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