80mw unit feed water pump mechanical seal cooler outlet pipe ball valve installation structure and method

Abstract

This invention discloses a structure and method for installing a ball valve on the outlet pipe of the mechanical seal cooler of an 80MW generator unit's feedwater pump. It belongs to the field of generator unit auxiliary equipment pipeline optimization technology. The installation structure includes a ball valve body installed on the outlet pipe downstream of the mechanical seal cooler's outlet, as well as supporting pipeline connection units, sealing protection units, and operation auxiliary units. The ball valve body enables rapid on / off control between the mechanical seal cooler and the downstream pipeline. The installation method includes preliminary preparation, pipeline positioning and cutting, ball valve installation, auxiliary component assembly, testing and debugging, and maintenance identification setting. This invention enables rapid isolation of the cooler, eliminates the need to shut down the system's main valves during maintenance, improves unit operational continuity, offers convenient operation, reliable sealing, and low modification costs, and is suitable for optimizing and upgrading the outlet pipe of the mechanical seal cooler in an 80MW generator unit's feedwater pump.

Description

Technical Field

[0001] This invention relates to the field of auxiliary equipment pipeline optimization technology for generator sets, and in particular to the structure and method for adding a ball valve to the outlet pipe of the mechanical seal cooler of the feedwater pump of an 80MW unit. Background Technology

[0002] The feedwater pump is the core power equipment of the steam-water circulation system in an 80MW subcritical generator set. The mechanical seal water cooler, as a key component of the feedwater pump, functions to reduce the temperature of the mechanical seal water through a cooling medium, ensuring the sealing performance and service life of the feedwater pump shaft seal. The outlet pipe of the mechanical seal water cooler must be kept continuously unobstructed and must have functions for rapid flow interruption and maintenance isolation to cope with scenarios such as cooler cleaning and fault repair.

[0003] In existing technology, the outlet water pipeline of the feedwater pump mechanical seal cooler in 80MW subcritical generator units lacks a dedicated shut-off valve and relies solely on the system's main valve for control. This approach has several drawbacks: First, maintenance of the cooler requires shutting down the system's main valve, leading to a complete shutdown of the feedwater pump and affecting the unit's operational continuity. A single maintenance operation can result in a power generation loss of tens of thousands of kilowatt-hours. Second, the main valve has a large diameter, is difficult to operate, and takes a long time to open and close, typically 30-60 minutes, extending the maintenance cycle. Third, the lack of a separate shut-off component prevents rapid isolation in case of cooler failure, easily leading to mechanical seal water leakage, abnormal temperature increases, and subsequent chain reactions such as feedwater pump shaft seal wear. Fourth, pipeline maintenance requires draining the entire branch medium, resulting in water and energy waste and increasing operational safety risks. Therefore, there is an urgent need to develop a suitable outlet water pipeline shut-off device installation scheme to address the aforementioned problems in the existing technology. Summary of the Invention

[0004] To address the technical problems of inconvenient maintenance, high operational risks, and energy waste caused by the lack of a dedicated shut-off valve in the outlet pipe of the feedwater pump mechanical seal cooler in existing 80MW subcritical units, this invention provides a structure and method for installing a ball valve on the outlet pipe of the feedwater pump mechanical seal cooler in 80MW units. By installing a dedicated ball valve at a specific location in the outlet pipe, the cooler can be quickly isolated, easily maintained, and the unit's continuous operation can be ensured, while reducing maintenance costs and safety risks.

[0005] The technical solution adopted in the present invention, namely the structure and method for installing the ball valve on the outlet pipe of the mechanical seal cooler of the feedwater pump of an 80MW unit, is as follows: The 80MW unit feedwater pump mechanical seal cooler outlet pipe ball valve installation structure includes a ball valve body installed on the outlet pipe downstream of the mechanical seal water cooler outlet, a pipe connection unit for achieving a stable connection between the ball valve body and the outlet pipe, a sealing protection unit for ensuring the sealing performance of the pipe connection, and an operation auxiliary unit for improving the ease of operation and protection performance of the ball valve; wherein, the diameter of the ball valve body is adapted to the diameter of the outlet pipe, and the ball valve body can realize the on / off control of the mechanical seal water cooler and the downstream pipe, so as to achieve separate isolation during the maintenance of the mechanical seal water cooler.

[0006] A further improvement to the technical solution of this invention is that: the ball valve body is a manually welded ball valve made of stainless steel, with a nominal diameter of DN20, a nominal pressure ≥1.6MPa, a PTFE soft seal structure for the sealing surface, a ball valve operation rotation angle of 90°, and an opening torque of... .

[0007] A further improvement of the technical solution of the present invention is that the ball valve body is installed on the water outlet pipe 150-300mm downstream of the outlet of the mechanical seal water cooler.

[0008] A further improvement of the technical solution of the present invention is that: the sealing and protection unit includes a metal spiral wound sealing gasket disposed between the pipe connection end faces, the sealing gasket adopts a composite structure of flexible graphite and 304 steel strip; the outer surface of the ball valve body and the pipe connection parts are coated with an anti-corrosion coating.

[0009] A further improvement of the technical solution of the present invention is that: the operation auxiliary unit includes an extension operating rod, a position indicator, and a protective cover; wherein, the extension operating rod is detachably connected to the handle of the ball valve body and has a length of 300-500mm; the position indicator is fixed to the side of the ball valve body and indicates the ball valve opening and closing status and the corresponding rotation direction; the protective cover is detachably installed on the outside of the ball valve body and the pipeline connection part and is made of transparent protective material.

[0010] A method for installing a ball valve on the outlet pipe of the feedwater pump mechanical seal cooler of an 80MW unit, characterized by the following steps for installing the aforementioned structure: S1. Preliminary preparation: Confirm that the generator set feedwater pump is shut down and the outlet water pipeline is depressurized, clean the pipeline connection end face and check the flange flatness, and select the matching ball valve body and supporting components. S2. Pipeline positioning and cutting: Mark and cut the pipeline at the preset position downstream of the outlet of the mechanical seal water cooler, and grind the cut to ensure that the mating surfaces are parallel. S3. Ball valve installation: The ball valve body is welded and fixed to the cut-off outlet pipes through the pipeline connection unit, and the connection is completed by diagonal and uniform fastening. S4. Auxiliary component assembly and testing: Complete the assembly of the operation auxiliary unit, start the mechanical seal water system to complete the pressure holding and switching performance tests, and finally set the operation and maintenance signs.

[0011] A further improvement of the above technical solution of the present invention is that: in step S2, the preset position is 150-300mm downstream of the outlet of the mechanical seal water cooler; in step S3, the connecting and tightening torque is controlled at... .

[0012] A further improvement of the above technical solution of the present invention is that: in step S4, the test pressure of the pressure holding test is 1.2 times the system working pressure, and the pressure holding time is 30 minutes; the main body switch response time of the ball valve is ≤10 seconds.

[0013] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows: This invention adds a dedicated ball valve body to the outlet pipe of the mechanical seal water cooler, enabling the cooler to be isolated quickly and independently. During maintenance, there is no need to shut down the main valve of the system, ensuring the normal operation of other equipment in the unit. A single maintenance can reduce downtime by 4-6 hours, improve the continuity of unit operation, and reduce power generation loss.

[0014] The ball valve body selected in this invention is easy to operate; it can be switched on and off by rotating it 90°. With the extension operating rod, it can be easily operated even in narrow spaces. The switching response time is ≤10 seconds, which improves the operating efficiency by more than 80% compared with traditional main valves, shortens the maintenance cycle, and reduces the labor intensity of operators.

[0015] This invention, through the combination of a sealing protection unit and a welded structure of a stainless steel ball valve, is suitable for the high-temperature and humid operating environment of generator sets, ensuring reliable sealing performance, avoiding the risk of mechanical seal water leakage, and reducing media waste during pipeline maintenance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure for adding a ball valve to the outlet pipe of the feedwater pump mechanical seal cooler of the 80MW unit according to the present invention.

[0017] In the attached diagram: 1. Mechanical seal water cooler; 2. Water outlet pipe; 3. Ball valve body. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings. In the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily obscuring the concept of this invention. Example 1

[0019] like Figure 1As shown, this embodiment provides a ball valve installation structure for the outlet pipe of the mechanical seal cooler of an 80MW unit feedwater pump, including a ball valve body 3, a pipeline connection unit, a sealing protection unit, and an operation auxiliary unit. The units work together to achieve rapid flow interruption and isolation and reliable sealing protection for the mechanical seal water cooler 1.

[0020] Specifically, the ball valve body 3 is installed on the outlet pipe 2 downstream of the outlet of the mechanical seal water cooler 1. The installation position is selected 200mm downstream of the outlet of the mechanical seal water cooler 1. This position avoids pipe bends and fixed supports, and is convenient for operators to stand and operate without interfering with the normal operation of the cooler. In this embodiment, the ball valve body 3 is a manual flange welded ball valve made of 316L stainless steel, with a nominal diameter of DN20, which is consistent with the diameter of the outlet pipe 2, and a nominal pressure of 2.0MPa, which meets the system working pressure requirements. The sealing surface adopts a PTFE soft seal structure to ensure zero leakage in the interrupted state. The opening torque of the ball valve is... The operating rotation angle is 90°, which allows for quick on / off operation.

[0021] The pipeline connection unit includes a PN1.6MPa flange connection assembly that matches the ball valve body 3. The flange is welded and fixed to the cut end of the outlet pipeline 2. The ball valve body 3 is stably connected to the outlet pipelines 2 on both sides through the flange to ensure the coaxiality of the pipeline and avoid the risk of leakage caused by misalignment.

[0022] The sealing protection unit includes a sealing gasket disposed between the flange connection end faces. In this embodiment, the sealing gasket is a 4mm thick flexible stone and 304 steel strip metal spiral wound gasket. Flange sealant is evenly applied to both sides of the gasket to further enhance the sealing effect. At the same time, the outer surface of the ball valve body 3 and the flange connection part are sprayed with an epoxy anti-corrosion coating, which can resist the corrosion of the humid and dusty environment of the generator room and extend the service life of the equipment.

[0023] The operation assistance unit includes an extension operating lever, a position indicator, and a protective cover. The extension operating lever is a 400mm long stainless steel rod that is detachably connected to the handle of the ball valve body 3 via threads, adapting to the operational needs of confined spaces in machine rooms and reducing operational difficulty. The position indicator is made of acrylic material and is bolted to the pipeline next to the ball valve body 3, clearly marked with "Open (rotate 90° clockwise)" and "Close (rotate 90° counterclockwise)" to clearly indicate the ball valve's on / off status and operating direction, avoiding misoperation. The protective cover is made of transparent PC material and is detachably fixed to the flange connection with clips, completely covering the ball valve body 3 and the flange connection area. This prevents damage to the ball valve caused by foreign object collisions and dust corrosion, while not obstructing observation of the ball valve's on / off status. Example 2

[0024] This embodiment provides a method for installing a ball valve on the outlet pipe of the mechanical seal cooler of an 80MW unit feedwater pump. The method employs the aforementioned installation structure and specifically includes the following steps: 1. Preliminary preparation: Confirm that the feedwater pump of the 80MW subcritical generator set is in a stopped state, and that the outlet water pipe 2 of the mechanical seal water cooler 1 has been depressurized and the medium has been drained; clean the impurities and rust on the end face of the pipe to be connected, and use a dial indicator to check the flatness of the original pipe flange, controlling the flatness deviation to ≤0.2mm; select the matching ball valve body 3, sealing gasket and other supporting components according to the parameters of the outlet water pipe 2.

[0025] 2. Pipeline positioning and cutting: Make a cutting mark 200mm downstream of the outlet of the mechanical seal water cooler 1. Use a plasma cutting device to cut the outlet pipe 2 vertically along the mark. After cutting, use an angle grinder to grind the cut to remove burrs and oxide layer, ensuring that the cut end face is smooth and perpendicular to the pipeline axis, and ensuring that the ball valve mating surface is parallel.

[0026] 3. Ball Valve Installation: Weld the matching flanges to the two cut-off ends of the outlet pipe 2 respectively. After welding, clean the weld slag and check the flatness of the flange end faces. Place the sealing gasket between the two flanges, place the ball valve body 3 between the two flanges, and tighten with bolts, controlling the tightening torque to within [value missing]. The bolts are tightened in three stages using a diagonal, uniform tightening method to ensure that the flange connection is free from skewing and that the force is evenly distributed.

[0027] 4. Auxiliary component assembly: Connect and fix the extension operating rod to the ball valve handle with threads to ensure a firm and secure connection; fix the position indicator to the pipeline next to the ball valve with pipe clamps to ensure the markings are clearly visible; fix the transparent protective cover to the flange with clips to completely cover the ball valve body and connection parts.

[0028] 5. Testing and Debugging: Slowly open the inlet valve of the mechanical seal water system to pressurize the pipeline to the system working pressure, and then gradually increase the pressure to 1.2 times the working pressure. Hold the pressure for 30 minutes. During this period, use soapy water to test the flange connection and ball valve sealing surface to confirm that there is no leakage. Operate the ball valve to perform multiple opening and closing tests to confirm that the ball valve opens flexibly without jamming and that the flow interruption is reliable. Record that the opening and closing response time is ≤10 seconds, which meets the design requirements.

[0029] In the above embodiments, a structure and method for installing a ball valve on the outlet pipe of the mechanical seal cooler of the feedwater pump of an 80MW unit are provided. After the ball valve is installed, the mechanical seal cooler can be quickly isolated during maintenance without shutting down the feedwater pump system and the main system valve, thus completely solving the problem of needing to shut down the entire unit for traditional pipeline maintenance. The ball valve is easy to operate and has reliable sealing, which greatly improves the efficiency of equipment operation and maintenance and operational safety. At the same time, the installation structure is simple, does not require large-scale modification of the original pipeline, has a short construction period, and low maintenance costs.

[0030] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the concept and scope of the present invention. Various modifications and improvements made to the technical solutions of the present invention by those skilled in the art without departing from the inventive concept should fall within the protection scope of the present invention. All technical contents for which protection is sought in this invention are fully described in the claims.

Claims

The structure for adding a ball valve to the outlet pipe of the feedwater pump mechanical seal cooler of a 1.80MW unit is characterized by: The device includes a ball valve body (3) installed on the downstream outlet pipe (2) of the mechanical seal water cooler (1), a pipe connection unit for achieving a stable connection between the ball valve body (3) and the outlet pipe (2), a sealing protection unit for ensuring the sealing performance of the pipe connection, and an operation auxiliary unit for improving the ease of operation and protection performance of the ball valve; wherein, the diameter of the ball valve body (3) is adapted to the diameter of the outlet pipe (2), and the ball valve body (3) can realize the on / off control of the mechanical seal water cooler (1) and the downstream pipe, so as to achieve separate isolation when the mechanical seal water cooler (1) is under maintenance.

2. The structure for adding a ball valve to the outlet pipe of the feedwater pump mechanical seal cooler of an 80MW unit according to claim 1, characterized in that: The ball valve body (3) is a manually welded ball valve made of stainless steel, with a nominal diameter of DN20, a nominal pressure ≥1.6MPa, and a PTFE soft seal structure for the sealing surface. The ball valve operates with a rotation angle of 90° and an opening torque of [missing information]. .

3. The structure for adding a ball valve to the outlet pipe of the feedwater pump mechanical seal cooler of an 80MW unit according to claim 1, characterized in that: The ball valve body (3) is installed on the outlet pipe (2) 150-300mm downstream of the outlet of the mechanical seal water cooler (1).

4. The structure for adding a ball valve to the outlet pipe of the feedwater pump mechanical seal cooler of an 80MW unit according to claim 1, characterized in that: The sealing and protection unit includes a metal spiral wound sealing gasket disposed between the pipe connection end faces. The sealing gasket adopts a composite structure of flexible graphite and 304 steel strip. The outer surface of the ball valve body (3) and the pipe connection parts are coated with an anti-corrosion coating.

5. The structure for adding a ball valve to the outlet pipe of the feedwater pump mechanical seal cooler of an 80MW unit according to claim 1, characterized in that: The operation assistance unit includes an extension operating rod, a position indicator, and a protective cover; wherein, the extension operating rod is detachably connected to the handle of the ball valve body (3) and has a length of 300-500mm; the position indicator is fixed to the side of the ball valve body (3) and indicates the ball valve opening and closing status and the corresponding rotation direction; the protective cover is detachably installed on the outside of the ball valve body (3) and the pipeline connection part and is made of transparent protective material. A method for installing a ball valve on the outlet pipe of the mechanical seal cooler of a 6.80MW unit feedwater pump, characterized in that... For mounting the structure according to any one of claims 1-5, the following steps are included: S1. Preliminary preparation: Confirm that the generator set water pump is shut down and the outlet pipeline (2) is depressurized. Clean the pipeline connection end face and check the flange flatness. Select the matching ball valve body (3) and matching parts. S2. Pipeline positioning and cutting: Mark and cut the pipeline at the preset position downstream of the outlet of the mechanical seal water cooler (1), and grind the cut to ensure that the mating surfaces are parallel. S3. Ball valve installation: The ball valve body (3) is welded and fixed between the cut-off water outlet pipe (2) through the pipeline connection unit, and the connection is completed by diagonal uniform fastening. S4. Auxiliary component assembly and testing: Complete the assembly of the operation auxiliary unit, start the mechanical seal water system to complete the pressure holding and switching performance tests, and finally set the operation and maintenance signs.

7. The method for installing a ball valve on the outlet pipe of the mechanical seal cooler of the feedwater pump of an 80MW unit according to claim 6, characterized in that: In step S2, the preset position is 150-300mm downstream of the outlet of the mechanical seal water cooler (1); in step S3, the connecting tightening torque is controlled at... .

8. The method for installing a ball valve on the outlet pipe of the mechanical seal cooler of the feedwater pump of an 80MW unit according to claim 6, characterized in that: In step S4, the test pressure for the pressure holding test is 1.2 times the system working pressure, and the pressure holding time is 30 minutes; the main body switch response time of the ball valve is ≤10 seconds.

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