Deep peak regulation system configuration of coal-fired thermal power generating unit

Abstract

The utility model provides a deep peak regulation system configuration of a coal-fired thermal power generating unit, which is characterized in that on the basis of an existing boiler feed water heating system, an external steam cooler is additionally arranged in a water supply pipeline, and a steam side inlet of the external steam cooler is connected with a temperature reduction module; steam with the pressure grade higher than that of regenerative steam extraction of the high-pressure cylinder is introduced into an inlet of the temperature reduction module, and a steam side outlet of the newly-added external steam cooler communicates with a steam inlet of the existing final-stage high-pressure heater; in other words, steam at a steam outlet of the newly-added external steam cooler is conveyed into an existing final-stage high-pressure heater to heat feed water located at the front end of the newly-added external steam cooler; and meanwhile, certain feed water pressure is maintained, so that feed water at an outlet of the economizer is kept at a certain supercooling degree, dry-state operation of the boiler is maintained under the deep peak regulation working condition, hydrodynamic stability is maintained, 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 a deep peak shaving system configuration for coal-fired power units. 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] In recent years, the installed capacity and power generation of new energy sources have reached new highs. However, due to the uncertainty of power generation from new energy sources, traditional thermal power units, especially coal-fired power units, still need to play the role of basic backup power supply and flexible peak-shaving power supply in coordination with new energy power generation.

[0004] Taking a 1000MW ultra-supercritical unit as an example, its high-pressure cylinder adopts a partial steam intake method and is equipped with a regulating stage. The regional power grid dispatch load range 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 regional power grid 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, such as those with load variations ranging from 20% to 100% THA, where the deep peak shaving load range is 20% to 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 3The 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's dry operation under deep peak shaving conditions, and maintain hydrodynamic stability and the continuous and 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 in the deep peak shaving condition of the ultra-supercritical unit, and maintain the hydrodynamic stability and the continuous and stable operation of the denitrification system. It provides a deep peak shaving system configuration for coal-fired power units.

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

[0013] This utility model provides a deep peak-shaving system configuration for a coal-fired power unit, comprising: a boiler, a deaerator system, a high-pressure cylinder, an existing final-stage high-pressure heater, a feedwater pipeline, and a steam pipeline. The boiler includes an economizer, a water-cooled wall, and a superheater connected sequentially by pipelines. The high-pressure cylinder adopts a partial steam inlet method and is equipped with a regulating stage. In the feedwater pipeline, the deaerator system, the existing final-stage high-pressure heater, and a newly added external steam cooler are sequentially arranged along the feedwater flow direction. The feedwater outlet of the newly added external steam cooler is connected to the boiler feedwater inlet. The steam... The 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. The main steam pipeline is equipped with a regulating stage inlet valve group, and the extraction steam pipeline is equipped with an extraction steam isolation valve. The steam-side inlet of the newly added external steam cooler is connected to a desuperheating module. The inlet of the desuperheating module is connected to steam with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder. The steam-side outlet of the newly added external steam cooler is connected to the inlet of the existing final-stage high-pressure heater.

[0014] In this scheme, feedwater is sequentially heated through a deaeration system, an existing final-stage high-pressure heater, and a newly added external steam cooler before being sent to the boiler feedwater inlet. The steam-side inlet of the newly added external steam cooler is connected to a desuperheating module. The inlet of the desuperheating module receives steam with a higher pressure rating than the regenerative extraction steam from the high-pressure cylinder. This higher-pressure steam, after being desuperheated by the desuperheating module, first heats the feedwater in the newly added external steam cooler. The steam-side outlet of the newly added external steam cooler is connected to the steam inlet of the existing final-stage high-pressure heater, i.e., the new... The steam from the outlet of the newly added external steam cooler is then sent to the existing final-stage high-pressure heater to heat the feedwater located in front of the newly added external steam cooler. In other words, the steam from the outlet of the newly added external steam cooler replaces the existing final-stage high-pressure heater regenerative extraction steam. This not only increases the feedwater temperature of the unit under deep peak shaving conditions, but also improves the heat utilization rate. As the feedwater temperature of the unit 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, the cooling module includes an isolation valve, a pressure reducing valve, and a cooler connected in sequence by pipes, with cooling water connected to the cooler.

[0016] In this scheme, steam with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder enters the desuperheating module, is depressurized by the pressure reducing valve, and then enters the desuperheater to mix with desuperheating water to achieve desuperheating and pressure reduction. Through the function of the desuperheating module, the steam with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is desuperheated and depressurized, ensuring the safe operation of the system.

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

[0018] In this scheme, the steam pressure at the steam-side outlet of the newly added external steam cooler is higher than the regenerative extraction steam pressure of the high-pressure cylinder, which makes the steam pressure entering the existing final-stage high-pressure heater higher than the regenerative extraction steam of the high-pressure cylinder, thereby further increasing the feedwater temperature entering the boiler.

[0019] Preferably, the steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is a mixture of the main steam of the unit, the steam in the superheater system, the steam in the rear chamber of the high-pressure cylinder regulating stage, or any one of the main steam, the steam in the superheater system, and the steam in the rear chamber of the high-pressure cylinder regulating stage, with the regenerative extraction steam or reheat steam of the unit.

[0020] This solution makes full use of the steam in the unit and provides multiple options for steam sources with higher pressure levels than the regenerative extraction steam of the high-pressure cylinder. Under the premise that the steam entering the newly added external steam cooler is higher than the existing regenerative extraction steam, the operational flexibility of the unit is improved.

[0021] Preferably, the steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is the main steam of the unit, and the inlet of the desuperheating module is connected to the main steam pipeline or the superheater outlet to introduce part of the main steam.

[0022] In this scheme, the inlet of the desuperheating module is connected to the main steam pipeline or the superheater outlet. By introducing a portion of the main steam into the desuperheating module, it is desuperheated and depressurized before being sent to the newly added external steam cooler to heat the feedwater, thereby increasing the feedwater temperature of the unit under deep peak shaving conditions.

[0023] Preferably, the steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is a mixture of main steam from other units, steam in the superheater system, steam in the regulating chamber of the high-pressure cylinder, or steam in the main steam, steam in the superheater system, or steam in the regulating chamber of the high-pressure cylinder, and regenerative extraction steam or reheat steam.

[0024] In this scheme, steam from other units is used to improve the operational flexibility of the unit and optimize the thermodynamic cycle of the entire system, provided that the steam entering the newly added external steam cooler is higher than that of the existing regenerative extraction steam.

[0025] Preferably, the number of valves in the regulating stage inlet valve group is four or six.

[0026] 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.

[0027] Preferably, a heat exchanger is provided between the outlet of the desuperheater and the steam-side inlet of the newly added external steam cooler.

[0028] In this scheme, a heat exchanger is provided between the outlet of the desuperheater and the steam-side inlet of the newly added external steam cooler. This allows the steam after the desuperheater to first enter the heat exchanger to heat other working media, such as air, water, or coal, before entering the newly added external steam cooler to heat the feedwater. This ensures the steam temperature entering the newly added external steam cooler and relatively increases the steam flow rate of the newly added external steam cooler.

[0029] Preferably, the deep peak shaving 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 with a higher pressure rating than the regenerative extraction steam from the high-pressure cylinder is de-cooled and depressurized in the de-cooling module before entering the newly added external steam cooler to supplement the feedwater heating. It also enters the existing final-stage high-pressure heater after the newly added external steam cooler to heat the feedwater, thereby increasing the unit's feedwater temperature under deep peak-shaving conditions. By operating the high-pressure cylinder inlet valve group, the original high-pressure cylinder inlet valve group is used to throttle the main steam. The purpose is to maintain a certain feedwater pressure and keep the economizer outlet feedwater at a certain degree of subcooling. Furthermore, by utilizing the regulating stage inlet valve group to control the main steam, a certain steam enthalpy drop can also be achieved, thus relatively improving the unit's economic efficiency.

[0031] Preferably, a throttling component is installed in the feedwater or steam pipeline system from the economizer outlet to the high-pressure cylinder inlet, and the throttling component is adjusted 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: Based on the existing boiler feedwater heating system, a new external steam cooler is added to the feedwater pipeline with a desuperheating module connected to the steam-side inlet. The desuperheating module inlet is connected to steam with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder. The steam-side outlet of the new external steam cooler is connected to the steam inlet of the existing final-stage high-pressure heater. That is, the steam from the steam outlet of the new external steam cooler is then sent to the existing final-stage high-pressure heater to heat the feedwater located at the front end of the new external steam cooler. At the same time, a certain feedwater pressure is maintained to keep the economizer outlet feedwater at a certain degree of subcooling, so as to maintain the dry operation of the boiler under deep peak shaving conditions, and maintain hydrodynamic stability and 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 configuration of a deep peak-shaving system for a coal-fired power unit 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 a main steam pipeline. 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 successively 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 a deep peak-shaving system configuration for coal-fired power units, such as... Figure 2 As shown, the boiler includes an economizer, water-cooled walls, and a superheater connected sequentially by pipes. The high-pressure cylinder uses a partial steam inlet and is equipped with a regulating stage. In the feedwater pipeline, a deaeration system, an existing final-stage high-pressure heater, and a newly added external steam cooler are sequentially arranged 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. The main steam pipeline is equipped with a regulating stage inlet valve group, and the extraction steam pipeline is equipped with an extraction steam isolation valve. The steam-side inlet of the newly added external steam cooler is connected to a desuperheating module. The inlet of the desuperheating module receives steam with a higher pressure level than the regenerative extraction steam from the high-pressure cylinder. The steam-side outlet of the newly added external steam cooler is connected to the inlet of the existing final-stage high-pressure heater. Figure 2In this system, the steam-side outlet of the newly added external steam cooler is connected to the extraction steam pipeline via a pipe, with the connection point located downstream of the extraction steam isolation valve. The steam exiting the desuperheating module first heats the feedwater downstream of the new external steam cooler before being sent to the existing final-stage high-pressure heater to heat the feedwater upstream. This not only increases the feedwater temperature at the boiler inlet under deep peak shaving conditions but also improves heat utilization. At this time, the extraction steam isolation valve on the extraction steam pipeline is closed, and 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. This enables the boiler to maintain dry operation under deep peak shaving conditions, while also maintaining hydrodynamic stability and ensuring the continuous and stable operation of the denitrification system.

[0039] Of course, the steam-side outlet of the newly added external steam cooler can also be connected to the steam inlet of the existing final-stage high-pressure heater through a pipeline. As long as the steam-side outlet of the newly added external steam cooler is connected to the steam inlet of the existing final-stage high-pressure heater, closing the extraction steam isolation valve will not affect the delivery of the steam from the steam-side outlet of the newly added external steam cooler to the existing final-stage high-pressure heater to heat the feedwater. This allows the extraction steam isolation valve to be closed, thus replacing the existing final-stage high-pressure heater regenerative extraction steam with the steam from the outlet of the newly added external steam cooler.

[0040] 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.

[0041] like Figure 2 As shown, the desuperheating module includes an isolation valve, a pressure reducing valve, and a desuperheater connected in sequence by pipes, with desuperheating water connected to the desuperheater. Steam with a higher pressure level than the regenerative extraction steam from the high-pressure cylinder enters the desuperheating module, is depressurized by the pressure reducing valve, and mixes with the desuperheating water in the desuperheater to achieve desuperheating and pressure reduction. Through the action of the desuperheating module, the steam with a higher pressure level than the regenerative extraction steam from the high-pressure cylinder is desuperheated and depressurized, ensuring the safe operation of the system.

[0042] The steam pressure at the steam-side outlet of the newly added external steam cooler is higher than the regenerative extraction pressure of the high-pressure cylinder, which makes the steam pressure entering the existing final-stage high-pressure heater higher than the regenerative extraction pressure of the high-pressure cylinder, thereby further increasing the feedwater temperature entering the boiler.

[0043] like Figure 2 As shown, the steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is the main steam. The inlet of the desuperheating module is connected to the superheater outlet, or it can be connected to the main steam pipeline to introduce part of the main steam. The introduced part of the main steam enters the desuperheater in the desuperheating module through the isolation valve and pressure reducing valve in sequence, mixes with the desuperheating water, and is then sent to the newly added external steam cooler to supplement the heating of the feedwater. The steam from the steam outlet of the newly added external steam cooler is then sent to the existing final stage high-pressure heater to heat the feedwater, so as to improve the feedwater temperature of the unit under deep peak shaving conditions. Of course, in other embodiments, the steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder can be the main steam of the unit, the steam in the superheater system, the steam in the rear chamber of the high-pressure cylinder regulating stage, or a mixture of the main steam, the steam in the superheater system, and the steam in the rear chamber of the high-pressure cylinder regulating stage with the regenerative extraction steam or reheat steam of the unit. This allows for full utilization of the unit's steam and provides multiple options for a steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder. Under the premise that the steam entering the newly added external steam cooler is higher than the existing regenerative extraction steam, it improves... This enhances the operational flexibility of the unit. Furthermore, the steam source with a higher pressure level than the regenerative extraction steam from the high-pressure cylinder can be a mixture of main steam from other units, steam within the superheater system, steam from the regulating chamber after the high-pressure cylinder, or steam from any of the main steam, superheater system, or regulating chamber after the high-pressure cylinder from other units, along with regenerative extraction steam or reheat steam. This allows for full utilization of steam from other units, improving the operational flexibility of the unit while optimizing the overall system's thermodynamic cycle, provided that the steam entering the newly added external steam cooler is higher than the existing regenerative extraction steam.

[0044] 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.

[0045] Preferably, a heat exchanger can be added between the outlet of the desuperheater and the steam-side inlet of the newly added external steam cooler, so that the steam after the desuperheater first enters the heat exchanger to heat other working media, such as air, water, or coal, before entering the newly added external steam cooler to heat the feedwater. This can ensure the steam temperature entering the newly added external steam cooler and relatively increase the steam flow rate of the newly added external steam cooler.

[0046] The deep peak-shaving system for coal-fired power units provided by this utility model, configured under deep peak-shaving conditions (taking 20% ​​THA as an example), allows the boiler feedwater temperature to be increased to 75% THA or even 100% THA. As the boiler feedwater temperature increases, the economizer inlet water temperature rises, leading to an increase in the economizer outlet water temperature, and consequently, the economizer outlet flue gas temperature, meeting the denitrification inlet flue gas temperature requirements. Furthermore, while the economizer outlet water temperature increases, a certain feedwater pressure is maintained, ensuring a certain degree of subcooling at the economizer outlet. Further, as the economizer outlet water temperature increases, the water-cooled wall inlet water temperature also increases, reducing the water-cooled wall inlet enthalpy deficit and enhancing hydrodynamic stability. Finally, 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.

[0047] Taking a 1000MW ultra-supercritical unit with a partial steam inlet in its high-pressure cylinder and a regulating stage as an example, data under 20% THA conditions.

[0048] 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.

[0049] In this embodiment, the main generator load is 200MW. After the addition of an external steam cooler for temperature reduction, the existing final-stage high-pressure heater inlet steam pressure and temperature parameters are 5.86MPa and 431℃, and the outlet feedwater pressure and temperature parameters are 12.1MPa and 274℃. The water-side temperature rise of the new external steam cooler is 7℃. The economizer outlet water temperature is 305℃, the subcooling is 20.3℃, the enthalpy deficit is 126.2kJ / kg, the economizer outlet flue gas temperature is 311℃, and the water-cooled wall outlet superheat is 11℃. The unit is in dry-state operation. The enthalpy deficit of the water-cooled wall inlet water is relatively reduced by 49.8kJ / kg, and the steam temperature deviation at the water-cooled wall outlet is controlled. The power 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 603 t / h, 13.1 MPa, and 592℃, and 603 t / h, 6 MPa, and 546℃, respectively. The effective enthalpy drop per unit working fluid is 47.4 kJ / kg, corresponding to a power output of 7.9 MW. Compared with the isenthalpic throttling method that simply uses valves without a regulating stage, the regulating stage inlet steam valve group achieves the same pressure control effect on the main steam, resulting in a relatively improved unit 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 will be more precise and convenient.

[0050] 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 deep peak-shaving system configuration for a coal-fired power unit, comprising: A boiler, a deaerator system, a high-pressure cylinder, an existing final-stage high-pressure heater, a feedwater pipeline, and a steam pipeline are characterized in that: the boiler includes an economizer, a water-cooled wall, and a superheater connected sequentially by pipelines; the high-pressure cylinder adopts a partial steam inlet method and is equipped with a regulating stage; in the feedwater pipeline, a deaerator system, an existing final-stage high-pressure heater, and a newly added external steam cooler are sequentially arranged along the feedwater flow direction, with the feedwater outlet of the newly added external steam cooler connected to the boiler feedwater inlet; 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, the main steam pipeline being equipped with a regulating stage steam inlet valve group, and the extraction steam pipeline being equipped with an extraction steam isolation valve; the steam-side inlet of the newly added external steam cooler is connected to a desuperheating module, the inlet of the desuperheating module receiving steam with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder, and the steam-side outlet of the newly added external steam cooler connected to the steam inlet of the existing final-stage high-pressure heater.

2. The deep peak shaving system configuration as described in claim 1, characterized in that, The cooling module includes an isolation valve, a pressure reducing valve, and a cooler connected in sequence by pipes, with cooling water connected to the cooler.

3. The deep peak shaving 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 regenerative extraction pressure of the high-pressure cylinder.

4. The deep peak-shaving system configuration as described in claim 3, characterized in that, The steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is the main steam of the unit, the steam in the superheater system, the steam in the back chamber of the high-pressure cylinder regulating stage, or a mixture of the main steam, the steam in the superheater system, and the steam in the back chamber of the high-pressure cylinder regulating stage of the unit with the regenerative extraction steam or reheat steam of the unit.

5. The deep peak-shaving system configuration as described in claim 3, characterized in that, The steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is the main steam of the unit. The inlet of the desuperheating module is connected to the main steam pipeline or the superheater outlet to introduce part of the main steam.

6. The deep peak-shaving system configuration as described in claim 3, characterized in that, The steam source with a higher pressure level than the regenerative extraction steam of the high-pressure cylinder is a mixture of main steam from other units, steam in the superheater system, steam in the regulating chamber after the high-pressure cylinder, or steam in the main steam, steam in the superheater system, or steam in the regulating chamber after the high-pressure cylinder, and regenerative extraction steam or reheat steam.

7. The deep peak-shaving system configuration as described in claim 3, characterized in that, The regulating stage inlet valve group has four or six valves.

8. The deep peak-shaving system configuration as described in claim 7, characterized in that, A heat exchanger is provided between the outlet of the desuperheater and the steam-side inlet of the newly added external steam cooler.

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

Images