A feed water recirculation valve protection system

Abstract

The water supply recirculation valve protection system provided by the present invention includes an electric stop valve, a pressure reducing assembly, a water supply recirculation valve, a manual stop valve, a controller, and a pressure measuring device arranged on the deaerator water tank for measuring the water tank pressure value, which are sequentially arranged on the water supply recirculation pipeline. The electric stop valve is located on the side of the water supply recirculation pipeline close to the water supply pump. By arranging the pressure reducing assembly, the pressure reducing assembly can be used to reduce the valve front pressure of the water supply recirculation valve, thereby reducing the degree of scouring, extending the service life, reducing the frequency of inspection and maintenance, ensuring tightness, and reducing leakage. By making the pressure reducing assembly include an adjustable pressure reducing valve, the controller is electrically connected to the adjustable pressure reducing valve and the pressure measuring device, and the pressure reducing ratio of the adjustable pressure reducing valve can be controlled in real time according to the water tank pressure value, thereby ensuring the power of the recirculating water while minimizing the pressure difference before and after the water supply recirculation valve, thereby significantly improving the economy and safety of the unit during operation.

Description

Technical Field

[0001] The invention belongs to the technical field of boiler feed water, and in particular relates to a feed water recirculation valve protection system. Background Art

[0002] At present, the feed water pumps used in thermal power plants are all high-temperature and high-pressure multi-stage centrifugal pumps. In order to ensure the normal start and stop of the feed water pump, a recirculation pipeline is designed. The pipeline is generally drawn from the outlet of the feed water pump and returns to the deaerator after passing through the feed water recirculation valve. The main functions of this pipeline are: (1) before the feed water pump is started, the pump is primed by connecting the recirculation pipeline; (2) when the demand drops sharply, the flow is diverted by connecting the recirculation pipeline, and the flow of the feed water pump is gradually reduced to avoid damage to the feed water pump due to sudden flow changes.

[0003] Since the water pressure on the feedwater pump side is high and the water pressure on the deaerator side is low, the pressure difference on both sides of the feedwater recirculation valve is very large. When matched with a supercritical (or ultra-supercritical) unit, the pressure difference can reach more than 25MPa. Affected by the unit load and power grid fluctuations, the start and stop and flow adjustment of the feedwater pump are very frequent, resulting in frequent on and off of the recirculation pipeline. The feedwater recirculation valve is frequently and strongly eroded, and is prone to leakage due to valve core wear. The cost of inspection and maintenance is high. When a large leak occurs, it is necessary to temporarily shut down for replacement. In addition, the leakage will also increase the power (steam) consumption of the feedwater pump and increase the coal consumption of the unit. For a 600MW-class unit, for every 10% leakage of feedwater flow from the feedwater recirculation valve, the unit coal consumption increases by about 0.6g / (kW•h), seriously affecting the economy and safety of the unit during operation. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a water recirculation valve protection system that can reduce the degree of scouring, extend the service life, reduce the frequency of inspection and maintenance, ensure tightness, and reduce leakage. The system can significantly improve the economy and safety of the unit during operation.

[0005] To achieve the above-mentioned object, the technical solution provided by the present invention is a water recirculation valve protection system, comprising an electric stop valve, a water recirculation valve, and a manual stop valve sequentially arranged on a water recirculation pipeline, wherein the electric stop valve is located on a side of the water recirculation pipeline close to the water pump;

[0006] The water supply recirculation valve protection system also includes a pressure reducing component, a pressure measuring device, and a controller. The pressure reducing component is arranged on the water supply recirculation pipeline. The pressure reducing component is located between the electric stop valve and the water supply recirculation valve. The pressure reducing component includes an adjustable pressure reducing valve. The pressure measuring device is arranged on the water tank of the deaerator. The pressure measuring device is used to detect the pressure value of the water tank. The controller is electrically connected to the adjustable pressure reducing valve and the pressure measuring device. The controller controls the pressure reduction ratio of the adjustable pressure reducing valve according to the pressure value.

[0007] Preferably, the pressure reducing assembly further comprises a proportional pressure reducing valve arranged between the electric stop valve and the adjustable pressure reducing valve, and the pressure reducing ratio of the proportional pressure reducing valve is 3:1.

[0008] Preferably, the pressure measuring device includes a plurality of pressure sensors arranged in the water tank, and the pressure value is an average value of detection values of all the pressure sensors.

[0009] Further preferably, the pressure sensor is arranged close to the connection port between the water tank and the water supply recirculation pipeline.

[0010] Further preferably, all the pressure sensors are distributed in a ring array along the axis of the connecting port.

[0011] Preferably, the water supply recirculation valve protection system further comprises a desuperheater arranged on the water supply recirculation pipeline, the desuperheater being arranged between the electric stop valve and the pressure reducing assembly, and the desuperheater being used to control the temperature of the recirculating water passing through the desuperheater.

[0012] More preferably, the temperature is controlled between 85°C and 100°C.

[0013] Further preferably, the desuperheater is a hybrid desuperheater or a surface desuperheater. When the desuperheater is a hybrid desuperheater, the cooling water mixed into the recirculating water along the desuperheater can also improve the flow rate of the water feed recirculation pipeline.

[0014] Further preferably, the water inlet of the desuperheater is connected to the water outlet of the condensate pump through a cooling water pipe.

[0015] Further preferably, the cooling water pipe is provided with an electric valve for controlling the cooling water flow rate, the water recirculation pipeline is provided with a temperature sensor for detecting the recirculating water temperature, and the temperature sensor is located between the desuperheater and the pressure reducing assembly.

[0016] Further preferably, the controller is electrically connected to the electric valve and the temperature sensor, and controls the opening of the electric valve according to the temperature value measured by the temperature sensor.

[0017] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0018] The water supply recirculation valve protection system provided by the present invention includes an electric stop valve, a pressure reducing assembly, a water supply recirculation valve, a manual stop valve, a controller, and a pressure measuring device arranged on the deaerator water tank for measuring the water tank pressure value, which are sequentially arranged on the water supply recirculation pipeline. The electric stop valve is located on the side of the water supply recirculation pipeline close to the water supply pump. By arranging the pressure reducing assembly, the pressure reducing assembly can be used to reduce the valve front pressure of the water supply recirculation valve, thereby reducing the degree of scouring, extending the service life, reducing the frequency of inspection and maintenance, ensuring tightness, and reducing leakage. By making the pressure reducing assembly include an adjustable pressure reducing valve, the controller is electrically connected to the adjustable pressure reducing valve and the pressure measuring device, and the pressure reducing ratio of the adjustable pressure reducing valve can be controlled in real time according to the water tank pressure value, thereby ensuring the power of the recirculating water while minimizing the pressure difference before and after the water supply recirculation valve, thereby significantly improving the economy and safety of the unit during operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural diagram of a preferred embodiment of the present invention.

[0020] Among them: 10. Deaerator; 11. Water tank; 12. Water supply pipe; 20. Water supply pump; 30. Water supply recirculation pipeline; 41. Electric stop valve; 42. Water supply recirculation valve; 43. Manual stop valve; 44. Pressure reducing assembly; 441. Adjustable pressure reducing valve; 442. Proportional pressure reducing valve; 45. Pressure measuring device; 46. Controller; 47. Desuperheater; 471. Cooling water pipe; 472. Electric valve; 48. Temperature sensor. DETAILED DESCRIPTION

[0021] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0022] like Figure 1As shown, the water supply recirculation valve protection system provided by the present invention includes an electric stop valve 41, a water supply recirculation valve 42, and a manual stop valve 43 which are sequentially arranged on the water supply recirculation pipeline 30, wherein one end of the water supply recirculation pipeline 30 is connected to the outlet of the water supply pump 20, and the other end is connected to the water tank 11 of the deaerator 10, and the inlet of the water supply pump 20 is connected to the water outlet of the water tank 11, and the electric stop valve 41 is located on the side of the water supply recirculation pipeline 30 close to the water supply pump 20; the water supply recirculation valve protection system also includes a pressure reducing component 44, a pressure measuring device 45, and a controller 46. The pressure reducing component 44 is arranged on the water supply recirculation pipeline 30. Specifically, the pressure reducing assembly 44 is located between the electric stop valve 41 and the water recirculation valve 42. The pressure reducing assembly 44 includes an adjustable pressure reducing valve 441 and a proportional regulating valve 442. The proportional regulating valve 442 is located between the electric stop valve 41 and the adjustable pressure reducing valve 441. The pressure reducing ratio of the proportional pressure reducing valve is 3:1. The pressure measuring device 45 is provided on the water tank 11 of the deaerator 10. The pressure measuring device 45 is used to detect the pressure value of the water tank 11. The controller 46 is electrically connected to the adjustable pressure reducing valve 441 and the pressure measuring device 45. The controller 46 controls the pressure reducing ratio of the adjustable pressure reducing valve 441 according to the pressure value of the water tank 11 of the deaerator 10.

[0023] The advantage of this arrangement is that the pressure reducing assembly can be used to reduce the valve inlet pressure of the water supply recirculation valve, thereby reducing the degree of scouring, extending the service life, reducing the frequency of inspection and maintenance, ensuring tightness, and reducing leakage. By adopting a pressure reducing assembly that combines an adjustable pressure reducing valve and a proportional pressure reducing valve, the proportional pressure reducing valve can be used to roughly adjust the valve inlet pressure of the water supply recirculation valve, and then the adjustable pressure reducing valve can be used to finely adjust the valve inlet pressure of the water supply recirculation valve. When one of them fails, it can also play a pressure reducing role and will not cause a sharp increase in the valve inlet pressure of the water supply recirculation valve. By electrically connecting the controller to the adjustable pressure reducing valve and the pressure measuring device, the pressure reducing ratio of the adjustable pressure reducing valve can be controlled in real time according to the pressure value of the water tank, thereby minimizing the pressure difference before and after the water supply recirculation valve while ensuring the power of the recirculating water, and significantly improving the economy and safety of the unit during operation.

[0024] The pressure measuring device 45 includes three to five pressure sensors arranged in the water tank 11. The pressure value measured by the pressure measuring device 45 is the average of the detection values of all pressure sensors. In order to improve the accuracy of the pressure value, the pressure sensor is further arranged near the connection port between the water tank 11 and the water supply recycling pipeline 30, and all pressure sensors are distributed in a circular array along the axial center line of the connection port.

[0025] The water supply recirculation valve protection system also includes a cooler 47 arranged on the water supply recirculation pipeline 30. The cooler 47 is arranged between the electric stop valve 41 and the pressure reducing assembly 44. The cooler 47 is used to control the temperature of the recirculating water passing through the cooler 47. The temperature cannot be too high or too low. If it is too high, it will easily cause damage to the seals and diaphragms in the adjustable pressure reducing valve 441 and the proportional regulating valve 442. If it is too low, it will affect the water temperature in the water tank 11 of the deaerator 10 and increase the energy consumption of the deaerator 10. Preferably, the temperature is controlled between 85°C and 100°C.

[0026] The water inlet of the desuperheater 47 is connected to the water outlet of the condensate pump through a cooling water pipe 471. The cooling water pipe 471 is provided with an electric valve 472 for controlling the cooling water flow rate. The water recirculation pipeline 30 is provided with a temperature sensor 48 for detecting the temperature of the recirculating water. The temperature sensor 48 is located between the desuperheater 47 and the pressure reducing assembly 44. The controller 46 is electrically connected to the electric valve 472 and the temperature sensor 48 so as to control the opening of the electric valve 472 according to the temperature value measured by the temperature sensor 48 to achieve the above-mentioned temperature control.

[0027] The cooler 47 can be a hybrid cooler or a surface cooler. In this embodiment, the cooler 47 adopts a hybrid cooler. The advantage of this arrangement is that when cooling, the cooling water mixed into the recycled water along the cooler 47 can not only reduce the temperature of the recycled water passing through the cooler 47, but also improve the flow rate of the water recycling pipeline 30. In another embodiment, the cooler 47 adopts a surface cooler, and the temperature of the recycled water passing through the cooler 47 is reduced by means of a cooling coil.

[0028] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable people familiar with this technology to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the scope of protection of the present invention.

Claims

1. A water recirculation valve protection system, comprising an electric stop valve, a water recirculation valve, and a manual stop valve, which are sequentially arranged on a water recirculation pipeline. The electric stop valve is located on the side of the water recirculation pipeline close to the water pump. Its characteristics are: The water supply recirculation valve protection system also includes a pressure reducing assembly, a pressure measuring device, and a controller. The pressure reducing assembly is arranged on the water supply recirculation pipeline, and the pressure reducing assembly is located between the electric stop valve and the water supply recirculation valve. The pressure reducing assembly includes an adjustable pressure reducing valve. The pressure measuring device is arranged on the water tank of the deaerator, and the pressure measuring device is used to detect the pressure value of the water tank. The controller is electrically connected to the adjustable pressure reducing valve and the pressure measuring device, and the controller controls the pressure reduction ratio of the adjustable pressure reducing valve according to the pressure value; the pressure reducing assembly also includes a proportional pressure reducing valve arranged between the electric stop valve and the adjustable pressure reducing valve; the water supply recirculation valve protection system also includes a desuperheater arranged on the water supply recirculation pipeline, and the desuperheater is arranged between the electric stop valve and the pressure reducing assembly. The desuperheater is used to control the temperature of the recirculating water passing through the desuperheater.

2. The water recirculation valve protection system according to claim 1, characterized in that: The pressure measuring device includes a plurality of pressure sensors arranged in the water tank, and the pressure value is an average value of detection values of all the pressure sensors.

3. The water recirculation valve protection system according to claim 2, characterized in that: The pressure sensor is arranged close to the connection port between the water tank and the water supply recirculation pipeline.

4. The water recirculation valve protection system according to claim 3, characterized in that: All the pressure sensors are distributed in a ring array along the axis of the connecting port.

5. The water recirculation valve protection system according to claim 1, characterized in that: The desuperheater is a hybrid desuperheater or a surface desuperheater.

6. The water recirculation valve protection system according to claim 1, characterized in that: The water inlet of the desuperheater is connected to the water outlet of the condensate pump through a cooling water pipe.

7. The water recirculation valve protection system according to claim 6, characterized in that: The cooling water pipe is provided with an electric valve for controlling the cooling water flow rate, and the water recirculation pipeline is provided with a temperature sensor for detecting the temperature of the recirculating water. The temperature sensor is located between the desuperheater and the pressure reducing assembly.

8. The water recirculation valve protection system according to claim 7, characterized in that: The controller is electrically connected to the electric valve and the temperature sensor, and controls the opening of the electric valve according to the temperature value measured by the temperature sensor.

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