A system and method for improving the sealing water supply performance of a feed water pump group in a thermal power plant

Abstract

The present invention relates to the technical field of the sealing water system of the feed water pump group in a thermal power plant. More specifically, it relates to a system and method for improving the sealing water supply performance of the feed water pump group in a thermal power plant, including a condensate water pressure main pipe at the outlet of the condensate pump group, a condensate water polishing system, a shaft seal heater, a booster pump, a condensate water intake main pipe, as well as regulating valves, orifice plates and connecting pipes. There are 3 regulating pipelines arranged between the condensate water pressure main pipe and the orifice plate. The water supply end of the regulating pipeline is connected to the inlet end of the orifice plate and is connected to the feed water pump group through the orifice plate and a temperature regulating valve to continuously and stably supply the sealing water with stable flow and pressure to the feed water pump group. Its characteristic is that when the unit load of the thermal power plant changes and the water volume of miscellaneous water use changes, the condensate water pressure at the inlet end of the orifice plate is relatively high and stable, ensuring that the sealing water continuously and stably supplied to the feed water pump group.

Description

Technical Field

[0001] The present invention relates to the technical field of the sealing water system of the feed water pump group in a thermal power plant, and more specifically, to a system and method for improving the water supply performance of the sealing water of the feed water pump group in a thermal power plant. Background Art

[0002] The insufficient front-end pressure of the sealing water of the feed water pump group in a thermal power plant has become one of the important hidden dangers for the stable and efficient operation of the feed water pump group, and domestic power plants have gradually started to pay attention to this.

[0003] In large thermal power generating units, the high-pressure feed water pump group is known as the heart of the power plant and is an important auxiliary equipment of modern thermal power plants.

[0004] The sealing water system is an important system in the high-pressure feed water pump group. The wear caused by the high-speed rotor of the high-pressure feed water pump makes the seal of the high-pressure feed water pump prone to leakage events frequently. Seal failure will cause direct economic losses to the enterprise, and at the same time pose a threat to the personal safety of the staff. The unstable high-pressure water pump device always poses a hidden danger in the production of the enterprise, which is not conducive to the normal production of the enterprise. A good sealing water system can ensure the normal operation of the high-pressure water pump device and can improve work efficiency.

[0005] Hydraulic sealing is to introduce a certain amount of high-pressure water into the sealing cavity to play the roles of water sealing, cooling and flushing. It is a non-contact type fluid dynamic seal and is a new type of rotating shaft seal structure developed in recent years. The hydraulic sealing structure is simple, easy to maintain, has no wear during operation, has a low failure rate, and a long service life.

[0006] The sealing water usually comes from the outlet of the condensate pump or the auxiliary booster pump in the power plant. The supply pressure of the condensate pump is different from the internal pressure of the boiler feed water pump. Therefore, the regulation and control of the sealing water pressure and flow rate are the key factors for the good operation of the hydraulic sealing system.

[0007] With the increase in the capacity of thermal power generating units, the feed water pressure of the feed water pump group has increased significantly. As an important equipment in the production process of thermal power plants, the feed water pressure of ultra-supercritical thermal power generating units reaches more than 23 MPa, and that of ultra-supercritical thermal power generating units reaches more than 30 MPa, making the difficulty of hydraulic sealing increasingly large, and situations such as leakage of the sealing system occur from time to time, which has an adverse impact on the normal operation of thermal power generating units, such as a decrease in the operating efficiency of the feed water pump, a decrease in the feed water pressure, and even damage to the feed water pump group. Therefore, effectively controlling the hydraulic sealing system of the feed water pump group can not only improve production efficiency, but also be a prerequisite for ensuring the safe progress of the production process.

[0008] The sealing water of the feed water pump group in a thermal power plant usually comes from the condensate pump. During the power production process, the electrical load of the unit must match the power consumption load. When the electrical load of the unit is adjusted, the condensate flow rate and pressure will change significantly, which easily leads to unstable supply pressure and flow rate of the sealing water, making it difficult to ensure a continuous and stable supply of sufficient sealing water flow rate.

[0009] When a thermal power plant participates in peak shaving operation, in order to ensure the safety margin of the sealing water pressure of the feed water pump, the speed reduction of the inverter of the condensate pump motor is limited, and the throttling loss of the condensate system is large under low load of the unit, resulting in an increase in the power consumption rate of the condensate pump motor.

[0010] The sealing water of the feed water pump group usually shares the condensate intake header with various water uses such as the desuperheating water of the condenser. When the water consumption of various water uses such as the desuperheating water of the condenser changes significantly, the pressure of the condensate intake header will also fluctuate greatly, which in turn causes the pressure and flow rate of the sealing water of the feed water pump group to fluctuate greatly, having an adverse impact on the operation of the feed water pump group and even making it difficult to operate normally. Summary of the Invention

[0011] In view of this, the purpose of the present invention is to propose a system and method for improving the sealing water supply performance of the feed water pump group in a thermal power plant, which can maintain the sealing water supply pressure and continuously and stably supply sufficient sealing water flow rate when the unit load and the condensate system change, so that the entire feed water pump group operates with better stability and higher efficiency.

[0012] To achieve the above object, the technical solution adopted by the present invention is: a system for improving the sealing water supply performance of the feed water pump group in a thermal power plant, including a condensate pressure header at the outlet of the condensate pump group, a condensate polishing system, a shaft seal heater, a booster pump, a condensate intake header, and regulating valves, orifice plates, and connecting pipes. There are 3 regulating pipelines arranged between the condensate pressure header and the orifice plate. The water supply end of the regulating pipeline is connected to the inlet end of the orifice plate, and after passing through the orifice plate and a temperature regulating valve, it is connected to the feed water pump group to supply sealing water to the feed water pump group. Let the condensate from the condensate pressure header pass through 3 regulating pipelines respectively, be connected to the inlet end of the orifice plate, and after passing through the orifice plate and a temperature regulating valve, supply sealing water to the feed water pump group.

[0013] Preferably, the first regulating pipeline is successively connected with a condensate intake header and a first gate valve between the condensate polishing system and the shaft seal heater, and the water supply end of the first gate valve is connected to the inlet end of the orifice plate.

[0014] Preferably, the second regulating pipeline is successively connected with a condensate intake header, a second gate valve, a booster pump, and a third gate valve between the condensate polishing system and the shaft seal heater, and the water supply end of the third gate valve is connected to the inlet end of the orifice plate.

[0015] Preferably, a flow regulating branch pipe is provided on the outlet pipe of the booster pump, and the flow regulating branch pipe is connected to the inlet pipe of the booster pump through a flow regulating valve.

[0016] Preferably, the third regulating pipeline is provided with a stop valve and a check valve between the condensate pressure header and the condensate polishing system, and the water supply end of the check valve is connected to the inlet end of the orifice plate.

[0017] Preferably, a boiler feedwater desuperheating water intake point, a condenser desuperheating water intake point, and other water intake points are arranged on the condensate intake header.

[0018] A method for improving the sealing water supply performance of the feed pump group in a thermal power plant. The condensate from the condensate pressure header respectively passes through three regulating pipelines connected to the inlet end of the orifice plate, and after passing through the orifice plate and the temperature regulating valve, the output supply pressure and flow rate of the sealing water are adjusted according to the changes in the unit load of the thermal power plant and the changes in the water volume of other water uses, and a stable flow and stable pressure sealing water is continuously supplied to the feed pump group.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: By setting three regulating pipelines that can make rapid adjustments according to different change situations, the present invention effectively solves the problems of reduced condensate pressure and insufficient flow rate in the condensate water sealing system of the feed pump group when the unit load of the thermal power plant changes and the water volume of miscellaneous condensate water changes, improves the condensate pressure of the sealing water system, and ensures the supply flow rate of the sealing water. When the unit load of the thermal power plant changes, the condensate system parameters change, and the water volume of miscellaneous water uses changes, the condensate pressure at the inlet end of the orifice plate is kept high and stable, ensuring the continuous and stable supply of sealing water to the feed pump group. The design structure of the present invention is reasonable, convenient for adjustment and control, has strong adaptability, is easy to maintain, has no wear during operation, has a low failure rate, and has a long service life, effectively ensuring the long-term normal operation of the feed pump group. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of a system for improving the sealing water supply performance of the feed pump group in a thermal power plant

[0021] The illustration marks are explained as follows: 1 - condensate pressure header, 2 - condensate polishing system, 3 - gland heater, 4 - stop valve, 5 - check valve, 6 - third valve gate, 7 - booster pump, 8 - second valve gate, 9 - first gate valve, 10 - orifice plate, 11 - temperature regulating valve, 12 - feed pump group, 13 - low-pressure heater group, 14 - boiler feedwater desuperheating water intake point, 15 - condenser desuperheating water intake point, 16 - other water intake points, 17 - condensate intake header, 18 - flow regulating valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] The present invention will be further described below in conjunction with specific embodiments. Among them, the attached drawings are only for illustrative purposes, showing only schematic diagrams, not physical diagrams, and should not be construed as a limitation to this patent; in order to better illustrate the embodiments of the present invention, some components in the attached drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the attached drawings may be omitted.

[0023] In the attached drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", etc. indicating the orientation or positional relationship based on the orientation or positional relationship shown in the attached drawings, it is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the attached drawings are only for illustrative purposes and should not be construed as a limitation to this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.

[0024] In order for the review committee to have a further understanding of the purpose, features and functions of the present invention, the present invention will be further described below in conjunction with specific embodiments and the attached drawings:

[0025] Please refer to Figure 1 As shown, it is a schematic diagram of the system structure of the present invention. The present invention is a system for improving the sealing water supply performance of the feed pump group in a thermal power plant, including a condensate pressure main pipe 1 at the outlet of the condensate pump group, a condensate polishing system 2, a gland heater 3, a booster pump 7, a condensate intake main pipe 17, as well as regulating valves, an orifice plate 10 and connecting pipes. There are 3 regulating pipelines arranged between the condensate pressure main pipe and the orifice plate. The water supply end of the regulating pipeline is connected to the inlet end of the orifice plate 10, and after passing through the orifice plate 10 and a temperature regulating valve 11, it is connected to the feed pump group to supply sealing water to the feed pump group.

[0026] Preferably, the first regulating pipeline is sequentially connected with a condensate intake main pipe 17 and a first gate valve 9 between the condensate polishing system 2 and the gland heater 3, and the water supply end of the first gate valve 9 is connected to the inlet end of the orifice plate 10.

[0027] Preferably, the second regulating pipeline is sequentially connected with a condensate intake main pipe 17, a second gate valve 8, a booster pump 7 and a third gate valve 6 between the condensate polishing system 2 and the gland heater 3, and the water supply end of the third gate valve 6 is connected to the inlet end of the orifice plate 10.

[0028] Preferably, a flow regulation branch pipeline is provided on the outlet pipeline of the booster pump 7, and the flow regulation branch pipeline is connected to the inlet pipeline of the booster pump 7 through a flow regulating valve 18.

[0029] Preferably, the third regulating pipeline is provided with a stop valve 4 and a check valve 5 between the condensate pressure header 1 and the condensate polishing system 2, and the water supply end of the check valve 5 is connected to the inlet end of the orifice plate 10.

[0030] Preferably, a boiler feedwater desuperheating water intake point 14, a condenser desuperheating water intake point 15, and other water intake points 16 are arranged on the condensate intake header 17.

[0031] A method for improving the sealing water supply performance of the feed pump group in a thermal power plant. The condensate from the condensate pressure header is respectively passed through 3 regulating pipelines connected to the inlet end of the orifice plate, and after passing through the orifice plate and the temperature regulating valve, the output supply pressure and flow rate of the sealing water are adjusted according to the changes in the unit load of the thermal power plant and the changes in the water volume of other uses, and a stable flow and stable pressure sealing water is continuously and stably supplied to the feed pump group.

[0032] The following non-limiting examples are used to illustrate the present invention patent:

[0033] A system and method for improving the sealing water supply performance of the feed pump group in a thermal power plant according to the present invention, as Figure 1 shown, the condensate from the condensate pressure header 1 enters the condensate polishing system 2, and then passes through the gland steam heater 3 and serves as the main condensate to the low-pressure heater group 13, which is the working medium of the power plant steam power cycle. Between the condensate polishing system 2 and the gland steam heater 3, a condensate intake header 17 is led out. Then, several branches are led out from the condensate intake header 17, and the branches include but are not limited to water-using equipment such as the sealing water supply for the feed pump group 12, the boiler feedwater desuperheating water intake point 14, the condenser desuperheating water intake point 15, and other water intake points 16.

[0034] When the unit load and the pressure of the condensate intake header 17 are relatively high, through the first regulating pipeline, the condensate from the condensate pressure header 1 is passed through the condensate intake header 17 and the first gate valve 9 after passing through the condensate polishing system 2 and before the gland steam heater 3. The water supply end of the first gate valve 9 is connected to the inlet end of the orifice plate 10, and the output supply pressure of the sealing water is adjusted through the orifice plate 10 and the temperature regulating valve 11, keeping the condensate pressure at the inlet end of the orifice plate relatively high and stable, and ensuring continuous and stable supply of sealing water to the feed pump group 12.

[0035] When the unit load changes and the pressure of the condensate extraction header 17 is relatively low, the first gate valve 9 is closed. Through the second regulating pipeline, the condensate from the condensate pressure header 1 is introduced from the condensate extraction header 17 after passing through the condensate polishing system 2 and before the shaft seal heater 3, and is adjusted and transported as sealing water via the second gate valve 8, the booster pump 7, and the third gate valve 6. The water supply end of the third gate valve 6 is connected to the inlet end of the orifice plate 10. A part of the sealing water pressurized by the booster pump 7 continuously and stably outputs sealing water to the feed pump set 12 via the orifice plate 10 and the temperature regulating valve 11.

[0036] Preferably, a flow regulating branch pipeline is provided on the outlet pipeline of the booster pump 7. The flow regulating branch pipeline is connected to the inlet pipeline of the booster pump 7 via a flow regulating valve 18. Another part of the sealing water passes through the flow regulating valve 18, converges with the condensate from the condensate extraction header 17, and enters the inlet end of the booster pump 7.

[0037] Adjust the opening degree of the flow regulating valve 18 to control the pressure at the inlet end of the orifice plate 10 and the flow rate of the sealing water 12. When the pressure before the flow regulating valve 18 exceeds or is lower than the set value of the flow regulating valve 18, the flow regulating valve 18 automatically adjusts the size of the water flow passing through.

[0038] When the booster pump 7 and the flow regulating valve 18 need to be overhauled, the second gate valve 8 and the third gate valve 6 are closed, so that the booster pump 7 and the flow regulating valve 18 are cut off and isolated, which is convenient for overhaul and maintenance operations. When using other regulating pipelines, the second regulating pipeline is closed.

[0039] When the unit load changes and the pressure of the condensate extraction header 17 is relatively low, and the booster pump 7 is out of service or under overhaul, the condensate from the condensate pressure header 1 is transported through the stop valve 4 and the check valve 5, reaches the inlet end of the orifice plate 10, and adjusts the output supply pressure of the sealing water through the orifice plate 10 and the temperature regulating valve 11, keeping the condensate pressure at the inlet end of the orifice plate relatively high and stable, ensuring continuous and stable supply of sealing water to the feed pump set 12. The check valve 5 is provided to prevent the sealing water output from the second regulating pipeline from flowing back through the third regulating pipeline and causing a problem of reduced output sealing water pressure loss.

[0040] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A system for improving the sealing water supply performance of a feed water pump group in a thermal power plant, comprising a condensate water pressure main pipe at the outlet of the condensate pump group, a condensate water polishing system, a gland heater, a booster pump, a condensate water intake main pipe, and regulating valves, orifice plates, and connecting pipes, characterized in that, The regulating valve includes a first gate valve, a second gate valve, a third gate valve, a stop valve, a check valve, a temperature regulating valve, and a flow regulating valve. There are 3 regulating pipelines arranged between the condensate pressure header and the orifice plate. The water supply end of the regulating pipeline is connected to the inlet end of the orifice plate, and after passing through the orifice plate and the temperature regulating valve, it is connected to the seal water system of the feed pump group to supply seal water to the feed pump group. The first regulating pipeline is successively connected with a condensate water intake header and a first gate valve between the condensate polishing system and the gland heater. The water supply end of the first gate valve is connected to the inlet end of the orifice plate. The second regulating pipeline is successively connected with a condensate water intake header, a second gate valve, a booster pump, and a third gate valve between the condensate polishing system and the gland heater. The water supply end of the third gate valve is connected to the inlet end of the orifice plate. A flow regulating branch pipeline is provided on the outlet pipeline of the booster pump, and the flow regulating branch pipeline is connected to the inlet pipeline of the booster pump through a flow regulating valve. The third regulating pipeline is provided with a stop valve and a check valve between the condensate pressure header and the condensate polishing system. The water supply end of the check valve is connected to the inlet end of the orifice plate. The condensate water intake header is arranged with a boiler steam supply desuperheating water intake point, a condenser desuperheating water intake point, and other water intake points.

2. A method for improving the sealing water supply performance of the feed pump group in a thermal power plant, which uses the system for improving the sealing water supply performance of the feed pump group in a thermal power plant as described in claim 1, characterized in that, The method is that the condensate water from the condensate pressure header respectively passes through 3 regulating pipelines connected to the inlet end of the orifice plate, and after passing through the orifice plate and the temperature regulating valve, adjusts the output supply pressure and flow of the seal water according to the changes in the unit load of the thermal power plant and the changes in the water volume of other water uses, and continuously and stably supplies the seal water with stable flow and pressure to the feed pump group.

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