Operation system configuration of coal power unit based on water supply supplementary heating

Abstract

The utility model provides an operation system configuration of a coal power unit based on feed water supplementary heating, which is characterized in that on the basis of an existing boiler feed water heating system, a newly-added final-stage high-pressure heater and a newly-added external steam cooler are additionally arranged on a water supply pipeline, and a steam side inlet of the newly-added external steam cooler is connected with a pressurization module; steam lower than the target steam extraction pressure grade is introduced into an inlet of the pressurization module, and a steam side outlet of the newly-added external steam cooler is connected with a steam inlet of the newly-added final-stage high-pressure heater; supplementary heating is conducted on feed water heated by an existing final-stage high-pressure heater at the position of a newly-added external steam cooler and in the newly-added final-stage high-pressure heater, so that the temperature of feed water entering a furnace of a unit under the deep peak regulation working condition is increased, and meanwhile certain feed water pressure is maintained to enable the feed water at an outlet of a coal economizer to be kept at a certain supercooling degree; dry-state operation of the boiler is maintained under the deep peak regulation working condition, the hydrodynamic stability is kept, and the denitration system is continuously and stably put into operation.

Description

Technical Field

[0001] This utility model relates to the field of power generation technology, and in particular to an operating system configuration for a coal-fired power unit based on supplementary heating of feedwater. Background Technology

[0002] Currently, high-parameter, large-capacity, high-efficiency, and low-carbon ultra-supercritical units have become the mainstream choice for new thermal power plant units. For ultra-supercritical units, their capacities are mainly in the 350MW, 660MW, and 1000MW range, with a small number in the 1200MW and 1350MW range.

[0003] Although the installed capacity and power generation of new energy sources have reached new highs, traditional thermal power units, especially coal-fired power units, must assume the role of basic backup power supply and flexible peak-shaving power supply to support new energy power generation due to the uncertainty of power generation from new energy sources.

[0004] Taking a 1000MW ultra-supercritical unit as an example, the power grid dispatch load range in this region is 40%-100% THA. The feedwater flow rate of the boiler equipment corresponding to the unit's load is higher than the minimum flow rate required for the boiler to maintain dry operation. Therefore, within the current normal load dispatch range, the boiler always maintains dry operation without any dry-wet transition process. However, with the rapid development of new energy sources, the power grid in this region has now notified the unit to operate under deep peak shaving conditions, and the lower limit of load dispatch needs to be as low as 20%. The feedwater flow rate of the boiler equipment corresponding to 20% load of this unit is already lower than the minimum flow rate required for the boiler to maintain dry operation, and the boiler will have to switch to wet operation.

[0005] For ultra-supercritical units that need to participate in deep peak shaving operation, if the load variation range is 20%-100% THA, and the deep peak shaving load range is 20%-30% THA or even lower, the following problems will be faced:

[0006] (1) Under deep peak shaving conditions, the boiler frequently switches between dry and wet states, making the control of coal, water, and air very difficult and drastically increasing the risk of boiler outages.

[0007] (2) Under deep peak shaving conditions, due to the increased under-enthalpy of the feedwater at the water-cooled wall inlet, the hydrodynamic stability of the boiler water-cooled wall is poor, and the risk of water-cooled wall overheating and tube rupture increases sharply.

[0008] (3) Under deep peak-shaving conditions, the economizer outlet flue gas temperature will be lower than the lower limit of the normal operating temperature of the denitrification catalyst, such as 300℃. The denitrification system will then be unable to operate normally, and NO2 is expected to rise. X Emissions will surge and far exceed standard requirements, such as the emission limit being raised from 25 mg / Nm³. 3 The concentration of Nm2 surged to 200 mg / Nm3 3 The above levels far exceed the standard value of 50 mg / Nm³.3 ;

[0009] (4) Under the wet operation of the boiler, if the water separated from the steam-water separator at the outlet of the boiler water-cooled wall is directly discharged into the atmospheric expansion tank, a large amount of working fluid and its energy will be lost, the unit's energy consumption will increase significantly and the operating economy will decrease significantly.

[0010] Therefore, how to maintain the boiler in dry state operation under deep peak shaving conditions, and maintain hydrodynamic stability and continuous stable operation of the denitrification system, has become an urgent problem to be solved. Utility Model Content

[0011] The technical problem to be solved by this utility model is how to maintain the dry operation of the boiler under deep peak shaving conditions, while maintaining hydrodynamic stability and continuous stable operation of the denitrification system, and to provide a flexible operation system configuration for coal-fired power units based on feedwater supplementary heating.

[0012] The present invention solves the above-mentioned technical problems through the following technical solution:

[0013] This utility model provides a coal-fired power unit operating system configuration based on feedwater supplemental heating, including a boiler, a deaerator system, a high-pressure cylinder, an existing final-stage high-pressure heater, feedwater pipelines, and steam pipelines. The boiler includes an economizer, a water-cooled wall, and a superheater connected sequentially via pipelines. The high-pressure cylinder employs a partial steam inlet method and is equipped with a regulating stage. In the feedwater pipeline, along the feedwater flow direction, the deaerator system, the existing final-stage high-pressure heater, a newly added final-stage high-pressure heater, and a newly added external steam cooler are sequentially arranged. The steam pipeline includes a main steam pipeline connecting the boiler steam outlet and the high-pressure cylinder steam inlet, and an extraction steam pipeline connecting the high-pressure cylinder extraction steam inlet and the existing final-stage high-pressure heater steam inlet. A regulating stage steam inlet valve group is installed on the main steam pipeline, and an extraction steam isolation valve is arranged on the extraction steam pipeline. The steam-side inlet of the newly added external steam cooler is connected to a booster module, with the booster module inlet receiving steam at a pressure lower than the target extraction steam pressure level. The steam-side outlet of the newly added external steam cooler is connected to the steam inlet of the newly added final-stage high-pressure heater.

[0014] In this scheme, a new final-stage high-pressure heater and a new external steam cooler are sequentially installed at the feedwater outlet of the existing final-stage high-pressure section of the feedwater pipeline. The steam-side inlet of the new external steam cooler is connected to a booster module, and the inlet of the booster module receives steam at a pressure lower than the target extraction pressure. The steam-side outlet of the new external steam cooler is connected to the steam inlet of the new final-stage high-pressure heater. The steam at a pressure lower than the target extraction pressure is boosted by the booster module and first goes to the new external steam cooler to supplement the feedwater at that location before going to the new final-stage high-pressure heater. The feedwater, after being heated by the existing final-stage high-pressure heater, is supplemented with additional heating. That is, in addition to the existing final-stage high-pressure heater heating the feedwater normally, steam lower than the target extraction steam pressure level is introduced, pressurized by the booster module, and then supplemented twice in the newly added external steam cooler and the newly added final-stage high-pressure heater to increase the unit's feedwater temperature. As the unit's feedwater temperature increases, the economizer inlet water temperature increases, which in turn increases the economizer outlet water temperature, and the economizer outlet flue gas temperature increases to meet the denitrification inlet flue gas temperature requirements.

[0015] Preferably, a steam compressor is installed in the pipeline of the booster module. The steam compressor is used to boost the steam entering the booster module that is below the target extraction pressure level, so that the steam below the target extraction pressure level is boosted by the steam compressor to a pressure higher than the pressure of the final stage extraction steam of the high-pressure cylinder.

[0016] In this scheme, a steam compressor is installed in the pressurization module. The steam compressor pressurizes the steam that is below the target extraction pressure level and then sequentially enters the newly added external steam cooler and the newly added final stage high-pressure heater to supplement the heating of the feedwater. The steam that is below the target extraction pressure level is pressurized by the steam compressor to a pressure higher than the final stage extraction pressure of the high-pressure cylinder. This ensures that the steam pressure entering the newly added external steam cooler after being compressed by the steam compressor is higher than the final stage extraction pressure entering the existing final stage high-pressure heater, thereby ensuring that the feedwater is heated to a higher temperature to improve the boiler feedwater temperature of the unit under deep peak shaving conditions.

[0017] Preferably, the steam pressure at the steam-side outlet of the newly added external steam cooler is higher than the final stage extraction pressure of the high-pressure cylinder.

[0018] In this scheme, the steam pressure at the steam outlet of the newly added external steam cooler is higher than the final stage extraction steam pressure of the high-pressure cylinder, which makes the steam pressure entering the newly added final stage high-pressure heater higher than the final stage extraction steam pressure of the high-pressure cylinder, thereby achieving supplementary heating of the feedwater that has been heated by the existing final stage high-pressure heater at the newly added final stage high-pressure heater.

[0019] Preferably, the booster module is equipped with a new steam extraction isolation valve in its pipeline, and the new steam extraction isolation valve is located at the front end of the steam compressor.

[0020] In this solution, a new extraction steam isolation valve is installed in the booster module and positioned at the front end of the steam compressor. The new extraction steam isolation valve regulates the fluid flow rate entering the booster module. In the event of a malfunction in the steam compressor, the new external steam cooler, or other equipment, the new extraction steam isolation valve can be closed to prevent steam from entering the booster module, ensuring system safety and improving system operational flexibility.

[0021] Preferably, the steam below the target extraction pressure level originates from a portion of the final stage extraction steam from the high-pressure cylinder, and the inlet of the booster module is connected to the extraction steam pipeline via a pipeline.

[0022] In this scheme, the inlet of the booster module is connected to the existing extraction steam pipeline of the final stage high-pressure heater through a pipeline. Part of the final stage extraction steam from the high-pressure cylinder enters the existing final stage high-pressure heater to heat the feedwater, while the other part of the final stage extraction steam from the high-pressure cylinder is pressurized by the booster module and then enters the newly added external steam cooler and the newly added final stage high-pressure heater in sequence to supplement or reheat the feedwater that has been heated by the existing final stage high-pressure heater, so as to improve the feedwater temperature of the unit under deep peak shaving conditions.

[0023] Preferably, the interface of the booster module connected to the extraction steam pipeline is located upstream of the extraction steam isolation valve.

[0024] In this scheme, the interface of the booster module to the extraction steam pipeline is located upstream of the extraction steam isolation valve, so that a portion of the final stage extraction steam is drawn out from the front end of the extraction steam isolation valve inlet. This allows the extraction steam isolation valve to independently control a portion of the final stage extraction steam from the high-pressure cylinder to enter the existing final stage high-pressure heater to heat the feedwater. Even if the existing final stage high-pressure heater cannot work, closing the extraction steam isolation valve will not affect the normal operation of the booster module and the newly added final stage high-pressure heater, thus improving the flexibility of unit operation.

[0025] Preferably, the steam source below the target extraction pressure level is regenerative extraction steam or reheat system steam or superheater system steam in this unit or other units.

[0026] In this scheme, steam below the target extraction pressure level is optimized into reheat extraction steam or reheat system steam or superheater system steam in this unit or other units. Under the premise of ensuring that the steam compressor outlet steam pressure is higher than the final stage extraction steam of the high-pressure cylinder, the operation flexibility of this unit is improved.

[0027] Preferably, the number of valves in the regulating stage inlet valve group is four or six.

[0028] In this scheme, the number of valves in the regulating stage inlet valve group is four or six. By regulating the main steam flow through multiple valves, not only is the flow control accuracy high, but the flow of a single valve is relatively small, which makes the pressure control of the main steam more precise and convenient.

[0029] Preferably, the operating system is configured to: throttle the main steam using the regulating stage inlet steam valve group to maintain a certain feedwater pressure and keep the economizer outlet feedwater at a certain degree of subcooling.

[0030] In this scheme, steam below the target extraction pressure level is pressurized by a booster module and then sequentially enters the newly added external steam cooler and the newly added final-stage high-pressure heater to supplement the feedwater that has been heated by the existing final-stage high-pressure heater. This is to increase the feedwater temperature at the boiler inlet of the unit under deep peak shaving conditions. At the same time, the main steam is throttled by operating the original regulating stage inlet valves. The purpose is to maintain a certain feedwater pressure and keep the economizer outlet feedwater at a certain degree of subcooling. Furthermore, the regulating stage inlet valve group can control the main steam while also obtaining a certain steam enthalpy drop, thereby relatively improving the unit's economy.

[0031] Preferably, a throttling device is installed in the feedwater or steam pipeline system from the economizer outlet to the high-pressure cylinder inlet to maintain a certain feedwater pressure.

[0032] In this scheme, throttling components, such as regulating valves, can be installed in the feedwater or steam pipeline from the economizer outlet to the high-pressure cylinder inlet to maintain a certain feedwater pressure, thereby keeping the economizer outlet feedwater at a certain degree of subcooling.

[0033] The positive and progressive effects of this utility model are as follows: A new final-stage high-pressure heater and a new external steam cooler are sequentially installed at the feedwater outlet of the existing final-stage high-pressure heater on the feedwater pipeline. The steam-side inlet of the new external steam cooler is connected to a booster module, and the inlet of the booster module receives steam at a pressure lower than the target extraction pressure. The steam-side outlet of the new external steam cooler is connected to the steam inlet of the new final-stage high-pressure heater. That is, while the existing final-stage high-pressure heater is normally operating to heat the feedwater, steam at a pressure lower than the target extraction pressure is introduced, boosted by the booster module, and then subjected to two supplementary heating processes in the new external steam cooler and the new final-stage high-pressure heater. This increases the feedwater temperature entering the boiler and simultaneously maintains a certain feedwater pressure to keep the economizer outlet feedwater at a certain degree of subcooling. This achieves dry-state operation of the boiler under deep peak-shaving conditions, while maintaining hydrodynamic stability and ensuring the continuous and stable operation of the denitrification system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a boiler feedwater heating system in the prior art.

[0035] Figure 2 This is a schematic diagram of the operating system configuration of a coal-fired power unit based on feedwater supplementary heating according to an embodiment of the present invention. Detailed Implementation

[0036] The present invention will be described more clearly and completely below with reference to the accompanying drawings, using a preferred embodiment.

[0037] Figure 1 This is a schematic diagram of a current boiler feedwater heating system. The system includes a boiler, a deaerator system, a high-pressure cylinder, and an existing final-stage high-pressure heater. The boiler includes an economizer, water-cooled walls, and a superheater connected sequentially via pipelines. The deaerator system includes a deaerator, a pre-pump, and a feedwater pump connected sequentially via pipelines. The feedwater inlet of the existing final-stage high-pressure heater is connected to the feedwater outlet of the deaerator system, and the feedwater outlet of the existing final-stage high-pressure heater is connected to the boiler feedwater inlet. The boiler steam outlet is connected to the high-pressure cylinder via the main steam pipeline, and the steam inlet of the existing final-stage high-pressure heater is connected to the extraction port of the high-pressure cylinder via an extraction steam pipeline. The high-pressure cylinder uses a partial steam inlet method and is equipped with a regulating stage. A regulating stage inlet valve group is arranged on the main steam pipeline, and an extraction steam isolation valve is arranged on the extraction steam pipeline. The low-pressure condensate from the deaerator outlet is pressurized sequentially by the pre-pump and feedwater pump before entering the existing final-stage high-pressure heater for heating. The heated feedwater enters the boiler and is subsequently heated by the economizer, water-cooled walls, and superheater, ultimately producing main steam that enters the high-pressure cylinder to perform work.

[0038] This utility model provides an operating system configuration for a coal-fired power unit based on feedwater supplemental heating, such as... Figure 2 As shown, the boiler includes an economizer, a water-cooled wall, and a superheater connected in sequence by pipelines. The high-pressure cylinder adopts a partial steam inlet method and is equipped with a regulating stage. In the feedwater pipeline, a deaeration system, an existing final-stage high-pressure heater, a newly added final-stage high-pressure heater, and a newly added external steam cooler are arranged in sequence along the feedwater flow direction. The feedwater outlet of the newly added external steam cooler is connected to the boiler feedwater inlet. The steam pipeline includes a main steam pipeline connecting the boiler steam outlet and the high-pressure cylinder inlet, and an extraction steam pipeline connecting the high-pressure cylinder extraction steam outlet and the existing final-stage high-pressure heater inlet. A regulating stage inlet steam valve group is installed on the main steam pipeline, and an extraction steam isolation valve is arranged on the extraction steam pipeline. The steam-side inlet of the newly added external steam cooler is connected to a pressurization module, and the inlet of the desuperheating module is connected to steam with a pressure lower than the target extraction steam pressure level through a pipeline. The steam-side outlet of the newly added external steam cooler is connected to the inlet of the newly added final-stage high-pressure heater.

[0039] Feedwater is sequentially delivered to the boiler feedwater inlet via the deaeration system, the existing final-stage high-pressure heater, the newly added final-stage high-pressure heater, and the newly added external steam cooler. Steam with a pressure lower than the target extraction pressure is pressurized by the booster module and first sent to the newly added external steam cooler to heat the feedwater there. Then, the steam from the steam-side outlet of the newly added external steam cooler is sent to the newly added final-stage high-pressure heater to supplement the feedwater heated by the existing final-stage high-pressure heater, thereby increasing the unit's feedwater temperature under deep peak shaving conditions. By introducing steam with a pressure lower than the target extraction pressure for supplementary heating in the newly added external steam cooler and the newly added final-stage high-pressure heater, not only is the feedwater temperature of the unit under deep peak shaving conditions increased, but the heat utilization rate is also improved. At the same time, the regulating stage inlet steam valve group installed on the main steam pipeline is used to throttle the main steam to maintain a certain feedwater pressure and keep the economizer outlet feedwater at a certain degree of subcooling, so as to maintain the boiler dry-state operation under deep peak shaving conditions, maintain hydrodynamic stability, and ensure the continuous and stable operation of the denitrification system. The steam at the target extraction pressure level can be understood as steam that, if the existing boiler feedwater heating system is used, without setting up a booster module, directly enters the existing final-stage high-pressure heater to heat the feedwater to the required temperature.

[0040] Compared to the scheme of replacing the inlet steam of the final stage high-pressure heater with the main steam after cooling and depressurization, this utility model can save the amount of high-temperature and high-pressure pipeline used, avoid the negative safety impact caused by the instantaneous change in the heat absorption ratio of the main and reheat steam due to the use of main steam, and the extraction steam used in this utility model is lower than the target extraction steam pressure level, which has better thermal economy than the main steam that does not do work in the steam turbine. Therefore, this scheme has the advantages of relative safety, low cost, high operational flexibility and good economy.

[0041] When increasing the boiler feedwater temperature under deep peak-shaving conditions, the main steam is throttled by operating the regulating stage inlet steam valve group to maintain a certain feedwater pressure and keep the economizer outlet feedwater at a certain degree of subcooling. Compared to the isenthalpic throttling method using valves without a regulating stage, the regulating stage inlet steam valve group achieves the same pressure control effect for the main steam while also obtaining a certain steam enthalpy drop, thus improving the unit's economy. Furthermore, because the flow rate of each valve in the regulating stage inlet steam valve group is relatively small, its pressure control of the main steam is more precise and convenient. Of course, in other embodiments, throttling components, such as regulating valves, can also be installed in the feedwater or steam pipeline from the economizer outlet to the high-pressure cylinder inlet to maintain a certain feedwater pressure, thereby keeping the economizer outlet feedwater at a certain degree of subcooling.

[0042] like Figure 2As shown, a steam compressor is installed in the pipeline of the booster module. The steam compressor is used to pressurize the steam entering the booster module that is below the target extraction pressure level, so that the steam below the target extraction pressure level, after being pressurized by the steam compressor, has a pressure higher than the pressure of the final stage extraction steam of the high-pressure cylinder. After being pressurized by the steam compressor, the steam below the target extraction pressure level enters the newly added external steam cooler and the newly added final stage high-pressure heater in sequence to supplement the heating of the feedwater. The steam below the target extraction pressure level, after being pressurized by the steam compressor, has a pressure higher than the pressure of the final stage extraction steam of the high-pressure cylinder. This ensures that the steam pressure entering the newly added external steam cooler after being compressed by the steam compressor is higher than the pressure of the final stage extraction steam entering the existing final stage high-pressure heater, thereby ensuring that the feedwater is heated to a higher temperature to improve the boiler feedwater temperature of the unit under deep peak shaving conditions.

[0043] Preferably, the steam pressure at the steam-side outlet of the newly added external steam cooler is higher than the final stage extraction steam pressure of the high-pressure cylinder, so that the steam pressure entering the newly added final stage high-pressure heater is higher than the final stage extraction steam pressure of the high-pressure cylinder, thereby achieving supplementary heating of the feedwater heated by the existing final stage high-pressure heater at the newly added final stage high-pressure heater.

[0044] like Figure 2 As shown, a new steam extraction isolation valve is installed in the pipeline of the booster module, and the new steam extraction isolation valve is located at the front end of the steam compressor. By installing the new steam extraction isolation valve in the booster module and placing it at the front end of the steam compressor, the flow rate of fluid entering the booster module can be regulated. Furthermore, in the event of a malfunction in the steam compressor, the new external steam cooler, or other equipment, the new steam extraction isolation valve can be closed to prevent steam from entering the booster module, ensuring system safety and improving system operational flexibility.

[0045] like Figure 2As shown, the steam below the target extraction pressure level originates from a portion of the final-stage extraction steam from the high-pressure cylinder. The inlet of the booster module is connected to the extraction steam pipeline via a pipe. A portion of the final-stage extraction steam from the high-pressure cylinder enters the existing final-stage high-pressure heater to heat the feedwater. The other portion of the final-stage extraction steam from the high-pressure cylinder is pressurized by the booster module and then sequentially enters the newly added external steam cooler and the newly added final-stage high-pressure heater to supplement or reheat the feedwater that has already been heated by the existing final-stage high-pressure heater, thereby increasing the feedwater temperature entering the boiler under deep peak-shaving conditions. The interface of the booster module connected to the extraction steam pipeline is located upstream of the extraction steam isolation valve so that a portion of the final-stage extraction steam is drawn out from the front end of the extraction steam isolation valve inlet. This allows the extraction steam isolation valve to independently control a portion of the final-stage extraction steam from the high-pressure cylinder to enter the existing final-stage high-pressure heater to heat the feedwater. Even if the existing final-stage high-pressure heater is not working, closing the extraction steam isolation valve will not affect the normal operation of the booster module and the newly added final-stage high-pressure heater, improving the flexibility of unit operation.

[0046] Of course, in other embodiments, the steam source below the target extraction pressure level is regenerative extraction steam or steam in the reheat system or superheater system of this unit or other units. Optimizing the steam below the target extraction pressure level to regenerative extraction steam or steam in the reheat system or superheater system of this unit or other units improves the operational flexibility of the unit while ensuring that the steam compressor outlet steam pressure is higher than the final stage extraction steam of the high-pressure cylinder.

[0047] Figure 2 In the regulating stage, the number of valves in the steam inlet valve group is four, but it can also be set to six. By regulating the main steam flow through multiple valves, the main steam flow can be controlled, and a certain steam enthalpy drop can be obtained, which improves the economic efficiency of the unit. Not only is the flow control accuracy high, but the flow of a single valve is relatively small, making the pressure control of the main steam more precise and convenient.

[0048] The coal-fired power unit provided by this utility model, based on a feedwater supplementary heating operating system, is configured under deep peak-shaving conditions. Taking a 20% THA condition as an example: the feedwater temperature at the boiler inlet can be increased to 75% THA or even 100% THA. As the feedwater temperature at the boiler inlet increases, the economizer inlet water temperature increases, leading to an increase in the economizer outlet water temperature, and the economizer outlet flue gas temperature increases to meet the denitrification inlet flue gas temperature requirements. Furthermore, while the economizer outlet water temperature increases, a certain feedwater pressure is maintained, ensuring that the economizer outlet feedwater maintains a certain degree of subcooling. Furthermore, as the economizer outlet water temperature increases, the water-cooled wall inlet water temperature increases, thereby reducing the water-cooled wall inlet underenthalpy and enhancing hydrodynamic stability. Furthermore, as the water-cooled wall inlet water temperature increases, the water-cooled wall outlet steam can maintain a certain degree of superheat, thus achieving dry-state boiler operation. Furthermore, it avoids large-scale modifications to boiler and turbine thermal systems, better adapts to the wide load range of unit operation in response to deep grid peak shaving, and improves the unit's operating economy and flexibility.

[0049] Taking a 1000MW ultra-supercritical unit with a partial steam inlet in its high-pressure cylinder and a regulating stage as an example, under 20% THA conditions.

[0050] The current configuration is as follows: The main generator load is 200MW. The existing final stage high-pressure heater inlet steam pressure and temperature parameters are 1.75MPa and 436℃, and the outlet feedwater pressure and temperature parameters are 6MPa and 192℃. The economizer outlet water temperature is 240℃, the subcooling degree is 36℃, the enthalpy deficit is 176kJ / kg, and the economizer outlet flue gas temperature is 245℃. The water-cooled wall outlet is wet saturated steam, and the unit is operating in a wet state, so the denitrification system cannot be put into use.

[0051] This embodiment's scheme: The main generator load is 200MW. The existing final-stage extraction steam pressure and temperature parameters are 1.03MPa and 341℃. After being pressurized by the steam compressor and then by a newly added external steam cooler, the new final-stage high-pressure heater inlet steam pressure and temperature parameters are 5.9MPa and 393℃, and the outlet feedwater pressure and temperature parameters are 12MPa and 275℃. The water-side temperature rise of the newly added external steam cooler is 6℃. The economizer outlet water temperature is 306℃, the subcooling degree is 18.7℃, the underenthalpy is 116.3kJ / kg, and the economizer outlet flue gas temperature is... With a temperature of 311℃ and a superheat of 10℃ at the water-cooled wall outlet, the unit operates in a dry state. The enthalpy deficit of the water-cooled wall inlet water is reduced by 54 kJ / kg, the steam temperature deviation at the water-cooled wall outlet is controlled, the hydrodynamic stability is enhanced, and the denitrification system is stably and continuously put into operation. Meanwhile, the inlet and outlet flow rates, pressures, and temperatures of the regulating stage are 607 t / h, 13.4 MPa, and 593℃, and 607 t / h, 6.2 MPa, and 545℃, respectively. The effective enthalpy drop per unit working fluid is 51.6 kJ / kg, corresponding to a power output of 8.7 MW. Compared to the isenthalpic throttling method using valves without a regulating stage, the regulating stage inlet valve group achieves the same pressure control effect for the main steam, resulting in a relatively improved unit economy. Furthermore, because the flow rate of each valve in the regulating stage inlet valve group is relatively small, its pressure control of the main steam is more precise and convenient.

[0052] While specific embodiments of this utility model have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of this utility model is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of this utility model, but all such changes and modifications fall within the scope of protection of this utility model.

Claims

1. A coal-fired power unit operating system configuration based on feedwater supplemental heating, comprising a boiler, a deaerator system, a high-pressure cylinder, an existing final-stage high-pressure heater, feedwater pipelines, and steam pipelines, characterized in that, The boiler includes an economizer, a water-cooled wall, and a superheater connected sequentially by pipes. The high-pressure cylinder adopts a partial steam inlet method and is equipped with a regulating stage. In the feedwater pipeline, a deaeration system, an existing final-stage high-pressure heater, a newly added final-stage high-pressure heater, and a newly added external steam cooler are sequentially arranged along the feedwater flow direction. The steam pipeline includes a main steam pipeline connecting the boiler steam outlet and the high-pressure cylinder steam inlet, and an extraction steam pipeline connecting the high-pressure cylinder extraction steam inlet and the existing final-stage high-pressure heater steam inlet. A regulating stage steam inlet valve group is installed on the main steam pipeline, and an extraction steam isolation valve is arranged on the extraction steam pipeline. The steam-side inlet of the newly added external steam cooler is connected to a pressurization module. The inlet of the pressurization module is connected to steam with a pressure lower than the target extraction steam pressure level. The steam-side outlet of the newly added external steam cooler is connected to the steam inlet of the newly added final-stage high-pressure heater.

2. The operating system configuration as described in claim 1, characterized in that, A steam compressor is installed in the pipeline of the booster module. The steam compressor is used to boost the steam entering the booster module that is below the target extraction pressure level, so that the steam below the target extraction pressure level is boosted by the steam compressor to a pressure higher than the pressure of the final stage extraction steam of the high-pressure cylinder.

3. The operating system configuration as described in claim 2, characterized in that, The steam pressure at the steam-side outlet of the newly added external steam cooler is higher than the extraction steam pressure of the last stage of the high-pressure cylinder.

4. The operating system configuration as described in claim 3, characterized in that, The booster module is equipped with a new steam extraction isolation valve in its pipeline, and the new steam extraction isolation valve is located at the front end of the steam compressor.

5. The operating system configuration as described in claim 4, characterized in that, The steam below the target extraction pressure level originates from a portion of the final stage extraction steam from the high-pressure cylinder, and the inlet of the booster module is connected to the extraction steam pipeline via a pipeline.

6. The operating system configuration as described in claim 5, characterized in that, The interface of the booster module connected to the extraction steam pipeline is located upstream of the extraction steam isolation valve.

7. The operating system configuration as described in claim 4, characterized in that, Steam sources below the target extraction pressure level are reheat extraction steam or reheat system steam or superheater system steam in this unit or other units.

8. The operating system configuration as described in claim 1, characterized in that, The regulating stage inlet valve group has four or six valves.

9. The operating system configuration as described in any one of claims 1-8, characterized in that, A throttling device is installed in the feedwater or steam pipeline from the economizer outlet to the high-pressure cylinder inlet.

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