Single bypass control extraction steam hybrid heat exchange frequency modulation system

Abstract

A single bypass controlled steam extraction hybrid heat exchange frequency modulation system includes a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a condenser connected to the low-pressure cylinder through a pipeline, a condensate pump, a lower-level low-pressure heater connected to the condensate pump through a pipeline, a bypass controller connected to the lower-level low-pressure heater through a main pipeline, an upper-level low-pressure heater connected to the bypass controller through a main pipeline, a deaerator directly connected to the upper-level low-pressure heater through a pipeline, a high-pressure heater directly connected to the deaerator through a pipeline, and a reheater whose inlet is connected to the high-pressure cylinder through a steam pipeline and whose outlet is connected to the medium-pressure cylinder through a steam pipeline. The present invention can quickly respond to the frequency modulation requirements of the power grid to the load changes of the unit, avoid the frequent switching of the steam inlet automatic regulating valve during the frequency modulation of the turbine, operate stably and reliably, ensure the safe operation of the turbine, significantly improve the life and flexibility of the unit, and save energy significantly. It can be widely used in the field of flexible frequency modulation of power plants.

Description

Technical Field

[0001] The invention relates to a single bypass controlled steam extraction type hybrid heat exchange frequency modulation system, which can be widely used in the field of flexible frequency modulation of power plants. Background Art

[0002] The electricity demand on the user side is changing all the time. In addition, renewable energy is unstable, and power plants need to adjust the load to ensure the balance of supply and demand in the power grid. In summary, due to the instantaneous imbalance between the supply and demand sides of the power grid, it is very easy to cause disturbances in the power grid and its frequency, and frequency is an important technical indicator for the safe and stable operation of the power system.

[0003] At present, power plants mainly respond to the frequency regulation needs of the power grid by increasing or decreasing the fuel of the boiler or adjusting the steam intake of the turbine, but the above measures have certain limitations, such as boiler delays and limited turbine regulation margins. In addition, there are many other frequency regulation methods, such as the energy storage frequency regulation method of batteries and heat storage tanks, and the energy conversion method of electrode boilers. The above methods have the problems of slow frequency regulation response speed, high investment cost and high operating cost. Summary of the invention

[0004] The object of the present invention is to provide a single bypass controlled steam extraction hybrid heat exchange frequency modulation system which can quickly respond to the frequency modulation requirements of the power grid to the changes in the unit load, avoid the frequent switching of the steam inlet automatic regulating valve during the frequency modulation of the turbine, operate stably and reliably, ensure the safe operation of the turbine, significantly improve the life and flexibility of the unit, and significantly save energy.

[0005] In order to achieve the above-mentioned object, the single bypass control extraction steam type hybrid heat exchange frequency modulation system of the present invention comprises a high-pressure cylinder, a medium-pressure cylinder connected to the high-pressure cylinder through a pipeline, a low-pressure cylinder connected to the medium-pressure cylinder through a pipeline, a condenser connected to the low-pressure cylinder through a pipeline, a condensate pump connected to the condenser through a pipeline, a lower-level low-pressure heater connected to the condensate pump through a pipeline, a bypass controller connected to the lower-level low-pressure heater through a main pipeline, a bypass controller connected to the bypass controller through a main pipeline and directly connected to the lower-level low-pressure heater through a drain pipeline, and An upper low-pressure heater directly connected to the medium-pressure cylinder through a steam extraction pipeline, a deaerator directly connected to the upper low-pressure heater through a pipeline, a high-pressure heater directly connected to the deaerator through a pipeline, a reheater whose inlet is connected to the high-pressure cylinder through a steam pipeline and whose outlet is connected to the medium-pressure cylinder through a steam pipeline; the bypass controller includes a buffer tank with a steam inlet interface and a water discharge interface at the bottom, a cold water interface and a hot water interface in the middle, located below the liquid level of the buffer tank, connected to the water discharge interface of the buffer tank through a pipeline and connected to the drain pipeline through a pipeline The lower booster pump connected to the buffer tank, the lower automatic regulating valve located below the buffer tank liquid level, connected to the buffer tank steam inlet interface through a pipeline and connected to the steam extraction pipeline through a pipeline, the upper booster pump located above the buffer tank liquid level, connected to the buffer tank hot water interface through a pipeline, the bypass automatic shut-off valve connected to the upper booster pump through a pipeline and connected to the main pipeline through the left bypass pipeline, the main line automatic shut-off valve located on the main pipeline connecting the upper low-pressure heater and the lower low-pressure heater, connected to the buffer tank cold water interface through a pipeline and connected to the right bypass pipeline. A bypass automatic regulating valve connected to the main pipeline, an upper automatic regulating valve connected between the inlet and outlet of the main automatic shut-off valve through a pipeline, a branch automatic shut-off valve on the pipeline connecting between the upper booster pump outlet and the bypass automatic shut-off valve at one end, a heat network circulation pump outlet connected to the branch automatic shut-off valve through a pipeline, a branch automatic regulating valve on the pipeline connecting between the buffer tank and the bypass automatic regulating valve at one end connected to the heat network circulation pump outlet through a pipeline and the other end; the buffer tank is a mixed heat exchanger, and steam and water are directly mixed for heat exchange.

[0006] The single bypass control steam extraction type hybrid heat exchange frequency modulation system of the present invention, the bypass controller also needs to maintain a basic load when not modulating the frequency, so as to achieve a rapid response of the frequency modulation.

[0007] The single bypass control steam extraction type hybrid heat exchange frequency modulation system of the present invention has a bypass controller and a heat exchange medium which is boiler condensate or winter heating network circulating water.

[0008] The single bypass controlled steam extraction type hybrid heat exchange frequency modulation system of the present invention, the buffer tank is a pressure tank or a normal pressure tank.

[0009] The single bypass control steam extraction hybrid heat exchange frequency modulation system of the present invention needs to reduce the bypass controller load when the grid frequency needs to be increased, that is, when the power plant power generation load needs to be increased. The bypass controller reduces steam extraction, and more steam is used for steam turbine power generation, which can quickly increase the unit load and quickly respond to the requirements of increased grid frequency. Its specific working process is:

[0010] First, when the heat exchange medium is condensate, the main line automatic shut-off valve, branch line automatic regulating valve, and branch line automatic shut-off valve are in a closed state, and the bypass automatic shut-off valve is in an open state. The opening of the lower automatic regulating valve is reduced, and the steam extraction to the medium pressure cylinder is reduced. Due to the reduction in steam extraction, in order to maintain the liquid level in the buffer tank, the frequency of the lower booster pump needs to be reduced so that the amount of water discharged from the buffer tank is equivalent to the amount of steam extraction. Due to the reduction in steam extraction, in order to keep the condensate temperature in the buffer tank within the design value range, it is necessary to reduce the flow of condensate entering the buffer tank, increase the opening of the upper automatic regulating valve, and reduce the opening of the bypass automatic regulating valve. In order to maintain the water flow balance of the system, the frequency of the upper booster pump at the outlet of the buffer tank also needs to be reduced so that the hot water output of the buffer tank is equivalent to the cold water inlet.

[0011] Second, when the heat exchange medium is the heat network circulating water, the upper automatic regulating valve, bypass automatic regulating valve, and bypass automatic shut-off valve are closed, and the main line automatic shut-off valve and branch line automatic shut-off valve are open. The lower automatic regulating valve has a reduced valve opening, which reduces the steam extraction from the intermediate pressure cylinder. Due to the reduced steam extraction, in order to maintain the liquid level in the buffer tank, the frequency of the lower booster pump needs to be reduced so that the amount of water discharged from the buffer tank is equivalent to the amount of steam extraction. Due to the reduced steam extraction, in order to keep the temperature of the heat network circulating water in the buffer tank within the design value range, it is necessary to reduce the flow of the heat network circulating water entering the buffer tank and reduce the opening of the branch automatic regulating valve. In order to maintain the balance of the heat network circulating water flow, the frequency of the upper booster pump at the buffer tank outlet also needs to be reduced so that the hot water output from the buffer tank is equivalent to the cold water inlet.

[0012] The single bypass control steam extraction hybrid heat exchange frequency modulation system of the present invention needs to increase the bypass controller load when it is necessary to reduce the grid frequency, that is, to reduce the power plant power generation load. The bypass controller extracts more steam, reduces the steam used for steam turbine power generation, and the unit load drops quickly and responds quickly to the requirements of reducing the grid frequency. Its specific working process is:

[0013] First, when the heat exchange medium is condensate, the main line automatic shut-off valve, branch line automatic regulating valve, and branch line automatic shut-off valve are in the closed state, and the bypass automatic shut-off valve is in the open state. The opening of the lower automatic regulating valve increases, and the steam extraction to the intermediate pressure cylinder increases. Due to the increase in steam extraction, in order to maintain the liquid level in the buffer tank, the frequency of the lower booster pump also needs to be increased to make the water discharge amount of the buffer tank equal to the steam extraction amount. Due to the increase in steam extraction, in order to keep the condensate temperature in the buffer tank at the design value, it is necessary to increase the flow of condensate entering the buffer tank, reduce the opening of the upper automatic regulating valve, and increase the opening of the bypass automatic regulating valve. In order to maintain the water flow balance of the main system, the frequency of the upper booster pump at the outlet of the buffer tank also needs to be increased, so that the hot water output of the buffer tank is equal to the cold water inlet.

[0014] Second, when the heat exchange medium is the heat network circulating water, the upper automatic regulating valve, bypass automatic regulating valve, and bypass automatic shut-off valve are closed, and the main line automatic shut-off valve and branch line automatic shut-off valve are open. The lower automatic regulating valve opens wider, increasing the steam extraction to the intermediate pressure cylinder. As the steam extraction increases, in order to maintain the liquid level in the buffer tank, the frequency of the lower booster pump needs to be increased so that the amount of water discharged from the buffer tank is equivalent to the amount of steam extraction. As the steam extraction increases, in order to keep the temperature of the heat network circulating water in the buffer tank at the design value, it is necessary to increase the flow of the heat network circulating water entering the buffer tank and increase the opening of the branch automatic regulating valve. In order to maintain the balance of the heat network circulating water flow in the main system, the frequency of the upper booster pump at the buffer tank outlet also needs to be increased so that the hot water output of the buffer tank is equivalent to the cold water inlet.

[0015] In the single bypass control steam extraction hybrid heat exchange frequency modulation system of the present invention, the buffer tank is designed to have a capacity according to the frequency modulation amplitude requirements of the power grid to meet the heat storage requirements. It is designed to be a pressure tank or a normal pressure tank according to the steam temperature, pressure and inlet and outlet water temperature requirements. The drain pipe connected to the buffer tank drain interface is a drain pipe with the same quality as the steam extraction of the buffer tank or a drain pipe corresponding to the temperature and pressure of the drain port.

[0016] The single bypass controlled steam extraction hybrid heat exchange frequency modulation system of the present invention, the main line automatic shut-off valve, bypass automatic shut-off valve, and branch line automatic shut-off valve are electrically, pneumatically or hydraulically driven valves, which can automatically, quickly and reliably cut off the medium.

[0017] The single bypass controlled steam extraction hybrid heat exchange frequency modulation system of the present invention, the lower automatic regulating valve, bypass automatic regulating valve, upper automatic regulating valve, branch automatic regulating valve are electric, pneumatic or hydraulically driven valves, which can automatically, quickly and reliably regulate the medium flow.

[0018] The single bypass controlled steam extraction type hybrid heat exchange frequency modulation system of the present invention, the lower booster pump and the upper booster pump can automatically control and adjust the medium flow.

[0019] The single bypass controlled extraction steam type hybrid heat exchange frequency modulation system of the present invention adopts a bypass controller. Without changing the structure of the steam turbine and the opening of the steam inlet automatic regulating valve, it can directly increase or decrease the steam flow of the high and medium pressure cylinders of the extraction steam turbine, so as to quickly respond to the frequency modulation requirements of the power grid to the load changes of the unit, avoid frequent switching of the steam inlet automatic regulating valve during the frequency modulation of the steam turbine, operate stably and reliably, ensure the safe operation of the steam turbine, and significantly improve the life and flexibility of the unit.

[0020] The single bypass controlled steam extraction hybrid heat exchange frequency modulation system of the present invention can directly heat boiler condensate or hot network water with extracted steam, and the energy loss in the frequency modulation process is very small, almost no energy loss, and significant energy saving.

[0021] In summary, the single bypass controlled steam extraction hybrid heat exchange frequency modulation system of the present invention can quickly respond to the frequency modulation requirements of the power grid for changes in unit load, avoid frequent switching of the steam inlet automatic regulating valve during turbine frequency modulation, operate stably and reliably, ensure safe operation of the turbine, significantly improve the life and flexibility of the unit, and significantly save energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described below in conjunction with the accompanying drawings and embodiments thereof.

[0023] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0024] exist Figure 1The single bypass control steam extraction type hybrid heat exchange frequency modulation system of the present invention comprises a high pressure cylinder 1, an intermediate pressure cylinder 2 connected to the high pressure cylinder through a pipeline, a low pressure cylinder 3 connected to the intermediate pressure cylinder through a pipeline, a condenser 4 connected to the low pressure cylinder through a pipeline, a condensate pump 5 connected to the condenser through a pipeline, a lower low pressure heater 6 connected to the condensate pump through a pipeline, a bypass controller 7 connected to the lower low pressure heater through a main pipeline 12, a bypass controller 7 connected to the lower low pressure heater through a main pipeline, a bypass controller 7 connected to the lower low pressure heater through a drain pipeline 13, and a bypass controller 7 connected to the lower low pressure heater through a main pipeline, a bypass controller 7 connected to the lower low pressure heater through a drain pipeline 14, and a bypass controller 7 connected to the lower low pressure heater through a main pipeline, a bypass controller 7 connected to the lower low pressure heater through a drain pipeline 15, and a bypass controller 7 connected to the lower low pressure heater through a drain pipeline 16. The upper low-pressure heater 8 is directly connected to the medium-pressure cylinder, the deaerator 9 is directly connected to the upper low-pressure heater through a pipeline, the high-pressure heater 10 is directly connected to the deaerator through a pipeline, and the inlet is connected to the high-pressure cylinder through a steam pipeline, and the outlet is connected to the medium-pressure cylinder through a steam pipeline. The reheater 11; the bypass controller 7 includes a buffer tank 7-1 with a steam inlet interface and a water discharge interface at the bottom, a cold water interface and a hot water interface in the middle, and a lower booster pump 7-1 located below the buffer tank liquid level, connected to the buffer tank water discharge interface through a pipeline and connected to the drain pipeline through a pipeline. 2, the lower automatic regulating valve 7-3 located at the lower part of the buffer tank liquid level, connected to the buffer tank steam inlet interface through a pipeline and connected to the steam extraction pipeline 14 through a pipeline, the upper booster pump 7-4 located at the upper part of the buffer tank liquid level, connected to the buffer tank hot water interface through a pipeline, the bypass automatic shut-off valve 7-5 connected to the upper booster pump through a pipeline and connected to the main pipeline through the left bypass pipeline, the main line automatic shut-off valve 7-6 located on the main pipeline connecting the upper low-pressure heater and the lower low-pressure heater, connected to the buffer tank cold water interface through a pipeline and connected to the main pipeline through the right bypass pipeline a bypass automatic regulating valve 7-7 connected to the main automatic shut-off valve through a pipeline, an upper automatic regulating valve 7-8 connected between the inlet and outlet of the main automatic shut-off valve through a pipeline, a branch automatic shut-off valve 7-9 with one end connected to the pipeline connecting the upper booster pump outlet and the bypass automatic shut-off valve, a heat network circulation pump outlet 7-10 connected to the branch automatic shut-off valve through a pipeline, and a branch automatic regulating valve 7-11 with one end connected to the heat network circulation pump outlet through a pipeline and the other end connected to the buffer tank and the bypass automatic regulating valve on the pipeline; the buffer tank is a mixed heat exchanger, in which steam and water are directly mixed for heat exchange.

[0025] The single bypass control steam extraction type hybrid heat exchange frequency modulation system of the present invention, the bypass controller also needs to maintain a basic load when not modulating the frequency, so as to achieve a rapid response of the frequency modulation.

[0026] The single bypass control steam extraction type hybrid heat exchange frequency modulation system of the present invention has a bypass controller and a heat exchange medium which is boiler condensate or winter heating network circulating water.

[0027] The single bypass controlled steam extraction type hybrid heat exchange frequency modulation system of the present invention, the buffer tank is a pressure tank or a normal pressure tank.

[0028] To sum up, the above only describes the preferred embodiments of the present invention. It should be pointed out that the present invention is not limited to the above-mentioned specific implementation modes, and the devices and structures not described in detail should be understood to be implemented in a common manner in the art; any technician familiar with the art, without departing from the scope of the technical solution of the present invention, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A single bypass control steam extraction hybrid heat exchange frequency modulation system, characterized in that: It includes a high-pressure cylinder, a medium-pressure cylinder connected to the high-pressure cylinder through a pipeline, a low-pressure cylinder connected to the medium-pressure cylinder through a pipeline, a condenser connected to the low-pressure cylinder through a pipeline, a condensate pump connected to the condenser through a pipeline, a lower-level low-pressure heater connected to the condensate pump through a pipeline, a bypass controller connected to the lower-level low-pressure heater through a main pipeline, an upper-level low-pressure heater connected to the bypass controller through a main pipeline, directly connected to the lower-level low-pressure heater through a drain pipeline, and directly connected to the medium-pressure cylinder through a steam extraction pipeline, a deaerator directly connected to the upper-level low-pressure heater through a pipeline, a high-pressure heater directly connected to the deaerator through a pipeline, and a reheater connected to the high-pressure cylinder through a steam pipeline and to the medium-pressure cylinder through a steam pipeline; the bypass controller includes a buffer tank with a steam inlet interface and a water discharge interface at the bottom, a cold water interface and a hot water interface in the middle, a lower booster pump located below the buffer tank liquid level, connected to the buffer tank water discharge interface through a pipeline and connected to the drain pipeline through a pipeline, and a lower booster pump located below the buffer tank liquid level. The lower automatic regulating valve at the bottom, which is connected to the steam inlet interface of the buffer tank through a pipeline and to the steam extraction pipeline through a pipeline; the upper booster pump located above the buffer tank liquid level, which is connected to the hot water interface of the buffer tank through a pipeline; the bypass automatic shut-off valve, which is connected to the upper booster pump through a pipeline and to the main pipeline through the left bypass pipeline; the main automatic shut-off valve located on the main pipeline connecting the upper low-pressure heater and the lower low-pressure heater, which is connected to the cold water interface of the buffer tank through a pipeline and to the main pipeline through the right bypass pipeline The bypass automatic regulating valve is connected to the upper automatic regulating valve between the inlet and outlet of the main automatic shut-off valve through a pipeline, one end of which is connected to the branch automatic shut-off valve on the pipeline connecting between the upper booster pump outlet and the bypass automatic shut-off valve, the outlet of the heat network circulation pump connected to the branch automatic shut-off valve through a pipeline, one end is connected to the outlet of the heat network circulation pump through a pipeline, and the other end is connected to the branch automatic regulating valve on the pipeline connecting between the buffer tank and the bypass automatic regulating valve; the buffer tank is a mixed heat exchanger, and steam and water are directly mixed for heat exchange.

2. The single bypass control steam extraction hybrid heat exchange frequency modulation system according to claim 1 is characterized in that: The bypass controller needs to maintain a basic load even when the frequency is not modulated, so as to achieve a fast response of the frequency modulation.

3. The single bypass control steam extraction hybrid heat exchange frequency modulation system according to claim 1 is characterized in that: The heat exchange medium of the bypass controller is boiler condensate or winter heating network circulating water.

4. The single bypass control steam extraction hybrid heat exchange frequency modulation system according to claim 1 is characterized in that: The buffer tank is a pressure tank or a normal pressure tank.

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