System configuration for coal power unit to adapt to deep peak regulation flexible operation

Abstract

The utility model provides a system configuration for a coal power unit to adapt to deep peak regulation flexible operation, which is characterized in that a newly-added external steam cooler is arranged at an existing final-stage high-pressure water supply outlet of 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 communicates with a steam inlet of an existing final-stage high-pressure heater; the steam lower than the target steam extraction pressure grade is pressurized by the pressurization module, firstly enters the newly-added external steam cooler to heat the feed water, and then enters the existing final-stage high-pressure heater to heat the feed water, so that the temperature of the feed water entering the furnace of the unit is increased; and meanwhile, a 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, the hydrodynamic stability is maintained, and the denitration system is continuously and stably put into operation.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of power generation, especially to a system configuration for coal power unit to adapt to deep peak shaving flexible operation. BACKGROUND

[0002] At present, the ultra (ultra) supercritical unit with high parameters, large capacity, high efficiency and low carbon has become the mainstream of the new unit selection of thermal power plants. For the ultra (ultra) supercritical unit, its capacity is mainly in the 350MW, 660MW, 1000MW level, and there are also a small amount of 1200MW, 1350MW level.

[0003] Although the installed capacity and power generation of new energy have reached a new high, due to the uncertainty of power generation of new energy generation, traditional thermal power units, especially coal-fired thermal power units, must bear the role of basic guarantee power supply and flexible peak shaving power supply for new energy power generation.

[0004] Taking a 1000MW ultra-supercritical unit as an example, the load range of the regional power grid dispatching is 40%-100%THA, the feedwater flow of the boiler equipment corresponding to the load of the unit is higher than the minimum flow of the boiler to keep dry operation, so in the current normal load dispatching range, the boiler always keeps dry operation and there is no dry-wet state conversion process. However, with the rapid development of new energy, the regional power grid has informed the unit that it needs to run in deep peak shaving, and the lower limit of load dispatching needs to be as low as 20%, the feedwater flow of the boiler equipment corresponding to 20% load of the unit has been lower than the minimum flow of the boiler to keep dry operation, and the boiler will have to be converted to wet operation.

[0005] For the ultra (ultra) supercritical unit that needs to participate in deep peak shaving operation, if the load changes in the range of 20%-100%THA, among which the deep peak shaving load range is 20%-30%THA, or even lower, the following problems will be faced:

[0006] (1) Under the condition of deep peak shaving, the boiler dry state and wet state are converted frequently, the control of coal, water and wind is very difficult, and the risk of non-stop of the boiler increases sharply;

[0007] (2) Under the condition of deep peak shaving, due to the increase of water underpotential at the inlet of water wall, the water power stability of the boiler water wall is poor, and the risk of water wall over-temperature explosion increases sharply;

[0008] (3) Under the condition of deep peak shaving, the flue gas temperature at the outlet of the economizer will be lower than the lower limit of the normal operation temperature of the denitration catalyst, such as 300℃, the denitration system will not be able to operate normally, and it is predicted that the NO X emission will increase sharply and be much higher than the standard value, such as the emission index from 25mg / Nm 3 to 200mg / Nm 3 The above is far beyond the standard value of 50mg / Nm3 .

[0009] (4) Boiler wet operation condition, if the boiler water wall outlet of the steam-water separator separates the water directly to the atmospheric expander, then cause a large amount of working fluid and energy loss, the unit energy consumption will rise sharply, the operation economy will be greatly reduced.

[0010] Therefore, how does the unit maintain the boiler dry operation under the deep peak shaving condition, and keep the water power stability and the denitration system continuously and stably put into operation, become the problem to be solved. Practical new type content

[0011] The technical problem to be solved by the utility model is how to maintain the boiler dry operation under the deep peak shaving condition, and keep the water power stability and the denitration system continuously and stably put into operation, and provide a system configuration of coal power unit adaptive deep peak shaving flexible operation.

[0012] The utility model solves the above-mentioned technical problem through the following technical scheme:

[0013] The utility model provides a system configuration of coal power unit adaptive deep peak shaving flexible operation, including boiler, deaerating system, high pressure cylinder, existing last stage high pressure heater, feedwater pipeline and steam pipeline, the boiler includes economizer, water wall, superheater that are connected in proper order through pipeline, high pressure cylinder adopts full circumferential admission, is not configured adjustment level, in the feedwater pipeline, deaerating system, existing last stage high pressure heater, newly added external steam cooler are sequentially arranged along the feedwater flow direction, and the feedwater outlet of newly added external steam cooler is communicated with the boiler feedwater inlet, the steam pipeline includes main steam pipeline connected between the boiler steam outlet and high pressure cylinder admission and steam extraction pipeline connected between high pressure cylinder steam extraction port and the admission of existing last stage high pressure heater, main steam throttling assembly is arranged on the main steam pipeline, and steam extraction isolation valve is arranged on the steam extraction pipeline, the steam side import of newly added external steam cooler is connected with pressure boosting module, the import of pressure boosting module accesses the steam below target steam extraction pressure level, and the steam side export of newly added external steam cooler is communicated with the admission of existing last stage high pressure heater.

[0014] In the scheme, an additional external steam cooler is arranged at the existing final high-pressure water outlet of the feedwater pipeline, and the steam side inlet of the additional external steam cooler is connected with a pressurizing module, the inlet of the pressurizing module is connected with steam below the target steam extraction pressure level, and the steam side outlet of the additional external steam cooler is connected with the steam inlet of the existing final high-pressure heater. Steam below the target steam extraction pressure level is first heated in the additional external steam cooler and then heated in the existing final high-pressure heater, so that the feedwater is heated twice in the additional external steam cooler and the existing final high-pressure heater, so as to improve the inlet feedwater temperature of the unit. With the improvement of the inlet feedwater temperature of the unit, the inlet water temperature of the economizer is improved, and then the outlet water temperature of the economizer is improved, and the outlet flue gas temperature of the economizer is improved and meets the requirement of the denitration inlet flue gas temperature.

[0015] Preferably, a steam compressor is arranged in the pipeline of the pressurizing module, and the steam compressor is used to pressurize the steam below the target steam extraction pressure level entering the pressurizing module, so that the pressure of the steam below the target steam extraction pressure level after being pressurized by the steam compressor is higher than the pressure of the final steam extraction of the high-pressure cylinder.

[0016] In the scheme, a steam compressor is arranged in the pressurizing module, and the steam below the target steam extraction pressure level is pressurized by the steam compressor and then heated in the additional external steam cooler and the existing final high-pressure heater. The pressure of the steam below the target steam extraction pressure level after being pressurized by the steam compressor is higher than the pressure of the final steam extraction of the high-pressure cylinder, so that the pressure of the steam entering the additional external steam cooler after being pressurized by the steam compressor is higher than the pressure of the final steam extraction entering the existing final high-pressure heater, thereby ensuring that the feedwater is heated to a higher temperature, so as to improve the inlet feedwater temperature of the unit in the deep peak shaving condition.

[0017] Preferably, when the steam at the steam side outlet of the additional external steam cooler enters the existing final high-pressure heater to heat the feedwater, the steam extraction isolation valve on the steam extraction pipeline of the existing final high-pressure heater is in a closed state, and the steam pressure at the steam side outlet of the additional external steam cooler is higher than the final steam extraction pressure of the high-pressure cylinder.

[0018] In the scheme, the steam extraction isolation valve is in a closed state, the steam at the steam side outlet of the additional external steam cooler is sent into the existing final high-pressure heater to replace the final steam extraction of the high-pressure cylinder of the steam extraction pipeline, and the steam pressure at the steam side outlet of the additional external steam cooler is higher than the regenerative steam extraction pressure of the high-pressure cylinder, so that the steam pressure entering the existing final high-pressure heater is higher than the regenerative steam extraction of the high-pressure cylinder, thereby further improving the feedwater temperature entering the boiler.

[0019] Preferably, a new steam extraction isolation valve is arranged in the pipeline of the pressurizing module, and the new steam extraction isolation valve is arranged upstream of the steam compressor.

[0020] In the present scheme, the new steam extraction isolation valve is arranged in the pressurizing module, and the new steam extraction isolation valve is arranged upstream of the steam compressor. The flow rate of the fluid entering the pressurizing module is adjusted through the new steam extraction isolation valve. When the steam compressor, the new external steam cooler and other equipment fail, the steam is prevented from entering the pressurizing module by closing the new steam extraction isolation valve, thereby ensuring the safety of the system operation and improving the flexibility of the system operation.

[0021] Preferably, a heat exchanger is further arranged in the pipeline of the pressurizing module, and the heat exchanger is arranged upstream of the steam compressor or between the steam compressor and the new external steam cooler.

[0022] In the present scheme, the heat exchanger is arranged in the pipeline of the pressurizing module. The steam in the pipeline enters the heat exchanger to heat other working substances such as air, water and coal, and then enters the corresponding equipment. When the heat exchanger is arranged upstream of the steam compressor, the steam below the target steam extraction pressure level enters the heat exchanger to heat other working substances such as air, water and coal, and then enters the new external steam cooler through the steam compressor to heat the feed water. In this way, the steam temperature entering the steam compressor is reduced, and the steam flow rate entering the new external steam cooler is relatively increased. When the heat exchanger is arranged between the steam compressor and the new external steam cooler, the steam below the target steam extraction pressure level is compressed by the steam compressor, enters the heat exchanger to heat other working substances such as air, water and coal, and then enters the new external steam cooler to heat the feed water. In this way, the steam temperature entering the new external steam cooler is reduced, and the steam flow rate entering the new external steam cooler is relatively increased.

[0023] Preferably, the steam below the target steam extraction pressure level is derived from the last stage extraction steam of the high-pressure cylinder, the inlet of the pressurizing module is connected to the extraction pipeline through a pipeline, and the interface of the pressurizing module connected to the extraction pipeline is arranged upstream of the steam extraction isolation valve.

[0024] In the scheme, the steam lower than the target extraction pressure level accessed by the inlet of the pressurizing module is the last stage extraction steam of the high pressure cylinder of the unit, the inlet of the pressurizing module is accessed by the existing extraction steam pipeline of the last stage high pressure heating, the last stage extraction steam of the high pressure cylinder is pressurized by the pressurizing module, and then enters the newly added external steam cooler to heat the feed water at the position, and then enters the existing last stage high pressure heater to heat the feed water, so as to improve the inlet feed water temperature of the unit in the deep peak shaving condition; the interface of the pressurizing module accessed by the extraction steam pipeline is located upstream of the extraction isolation valve, the last stage extraction steam of the high pressure cylinder is led out at the front end of the inlet of the extraction isolation valve, the extraction isolation valve is closed, and the last stage extraction steam of the high pressure cylinder can enter the pressurizing module, so as to improve the flexibility of the unit operation.

[0025] Preferably, the steam lower than the target extraction pressure level is the extraction steam of the regenerative system or the steam in the reheating system or the steam in the superheater system in the unit or in other units.

[0026] In the scheme, the steam lower than the target extraction pressure level is optimized to be the extraction steam of the regenerative system or the steam in the reheating system or the steam in the superheater system in the unit or in other units, which improves the flexibility of the unit operation on the premise that the outlet steam pressure of the steam compressor is higher than the last stage extraction steam of the high pressure cylinder.

[0027] Preferably, the main steam throttling assembly is a high pressure cylinder inlet valve group or a regulating valve.

[0028] In the scheme, the main steam throttling assembly adopts the high pressure cylinder inlet valve group or the regulating valve to conveniently adjust the pressure and flow of the main steam.

[0029] Preferably, the system configuration is configured to throttle the main steam by the main steam throttling assembly to maintain a certain feed water pressure and keep a certain subcooling degree of the economizer outlet feed water.

[0030] When the steam lower than the target extraction pressure level is pressurized by the pressurizing module and then enters the newly added external steam cooler and the existing last stage high pressure heater to heat the feed water, so as to improve the inlet feed water temperature of the unit in the deep peak shaving condition, the main steam is throttled by operating the main steam throttling assembly to maintain a certain feed water pressure and keep a certain subcooling degree of the economizer outlet feed water.

[0031] Preferably, a throttling assembly is arranged in the feed water or steam pipeline system from the economizer outlet to the high pressure cylinder inlet, and the throttling assembly is adjusted to maintain a certain feed water pressure.

[0032] In the scheme, a throttling assembly such as a regulating valve can also be arranged in the feed water pipeline or steam pipeline from the economizer outlet to the high pressure cylinder inlet, and the throttling assembly is adjusted to maintain a certain feed water pressure, so as to keep a certain subcooling degree of the economizer outlet feed water.

[0033] The positive progress effect of the utility model lies in: the existing last-stage high-pressure water supply outlet of the water supply pipeline is provided with a newly-added external steam cooler, a steam-side inlet of the newly-added external steam cooler is connected with a pressure boosting module, an inlet of the pressure boosting module is connected with steam with a pressure lower than a target steam extraction pressure level, a steam-side outlet of the newly-added external steam cooler is communicated with a steam inlet of an existing last-stage high-pressure heater; that is, the water supply is heated twice in the newly-added external steam cooler and the existing last-stage high-pressure heater respectively, so as to improve the furnace-inlet water supply temperature of the unit, maintain a certain water supply pressure to keep the water supply at the outlet of the coal economizer with a certain supercooling degree, and realize the maintenance of the dry operation of the boiler under the deep peak regulation condition and the stability of the water power and the continuous and stable operation of the denitration system. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 It is a system schematic diagram for the boiler water supply heating in the prior art.

[0035] Figure 2 It is a system configuration for the flexible operation of the coal power unit under the deep peak regulation according to an embodiment of the utility model. DETAILED DESCRIPTION

[0036] The utility model will be described below in combination with the preferred embodiments and the drawings.

[0037] Figure 1 It is a system schematic diagram for the boiler furnace-inlet water supply heating in the prior art. The system comprises a boiler, a deaeration system, a high-pressure cylinder and an existing last-stage high-pressure heater, the boiler comprises a coal economizer, a water cooling wall and a superheater which are connected in sequence through pipelines; the deaeration system comprises a deaerator, a pre-pump and a water supply pump which are connected in sequence through pipelines; the water supply inlet of the existing last-stage high-pressure heater is communicated with the water supply outlet of the deaeration system, the water supply outlet of the existing last-stage high-pressure heater is communicated with the water supply inlet of the boiler, the steam outlet of the boiler is communicated with the high-pressure cylinder through a main steam pipeline, and the steam inlet of the existing last-stage high-pressure heater is communicated with the steam extraction port of the high-pressure cylinder through a steam extraction pipeline; the low-pressure condensate at the outlet of the deaerator is pressurized by the pre-pump and the water supply pump in sequence and then enters the existing last-stage high-pressure heater to be heated, the heated water supply enters the boiler and is heated by the heating surfaces such as the coal economizer, the water cooling wall and the superheater in sequence, and finally the main steam is obtained and enters the high-pressure cylinder to do work.

[0038] The utility model provides a kind of system configuration for the flexible operation of the coal power unit under the deep peak regulation, as shown in Figure 2As shown, it comprises: a boiler, an oxygen removal system, a high-pressure cylinder and an existing final-stage high-pressure heater, the boiler comprising a coal economizer, a water cooling wall and a superheater connected in sequence by pipelines; the oxygen removal system comprising a deaerator, a pre-pump and a feedwater pump connected in sequence by pipelines; the high-pressure cylinder adopts full-circumferential admission, and is not configured with an adjusting stage; in the feedwater pipeline, the oxygen removal system, the existing final-stage high-pressure heater and the newly-added external steam cooler are arranged in sequence along the feedwater flow direction, and the feedwater outlet of the newly-added external steam cooler is communicated with the boiler feedwater inlet; the steam pipeline comprises a main steam pipeline connected between the boiler steam outlet and the high-pressure cylinder admission port, and a steam extraction pipeline connected between the high-pressure cylinder extraction port and the admission port of the existing final-stage high-pressure heater, the high-pressure cylinder admission valve group is arranged on the main steam pipeline, and the steam extraction isolation valve is arranged on the steam extraction pipeline; the steam-side inlet of the newly-added external steam cooler is connected with a pressure boosting module, the inlet of the pressure boosting module is connected with steam at a pressure lower than the target steam extraction pressure level, and the steam-side outlet of the newly-added external steam cooler is communicated with the admission port of the existing final-stage high-pressure heater.

[0039] The feedwater is sent to the boiler feedwater inlet in sequence through the oxygen removal system, the existing final-stage high-pressure heater and the newly-added external steam cooler, the steam at a pressure lower than the target steam extraction pressure level is boosted by the pressure boosting module, and then heated to the required temperature in the existing final-stage high-pressure heater, that is, the feedwater is heated twice in the newly-added external steam cooler and the existing final-stage high-pressure heater respectively, so as to improve the inlet boiler feedwater temperature of the unit, with the improvement of the inlet boiler feedwater temperature of the unit, the coal economizer inlet water temperature is improved, and then the coal economizer outlet water temperature is improved, and the coal economizer outlet flue gas temperature is improved and meets the requirement of the denitration inlet flue gas temperature; at the same time, the feedwater pressure is maintained, the coal economizer outlet feedwater is kept at a certain degree of supercooling, the boiler dry operation is maintained under the deep peak shaving condition, and the water power stability and the continuous and stable operation of the denitration system are maintained.

[0040] Figure 2The high-pressure cylinder inlet valve group is arranged on the main steam pipeline, and of course, it can also be arranged for other main steam throttling components, such as a regulating valve, to regulate the pressure and flow of the main steam. It is emphasized here that the steam below the target extraction pressure level is pressurized by the booster module and then sequentially enters the newly added external steam cooler and the existing final high-pressure heater to heat the feed water, so as to improve the feed water temperature of the unit under the deep peak shaving condition. The high-pressure cylinder inlet valve group can also be used to throttle the main steam, and the purpose is to maintain a certain feed water pressure and keep the feed water at the economizer outlet at a certain supercooling degree, so as to ensure the normal operation of the unit. Of course, in other embodiments, a throttling component, such as a regulating valve, can also be arranged in the feed water or steam pipeline system from the economizer outlet to the high-pressure cylinder inlet, so as to maintain a certain feed water pressure and keep the feed water at the economizer outlet at a certain supercooling degree.

[0041] As shown in Figure 2 The steam compressor is arranged in the pipeline of the booster module, and is used to pressurize the steam below the target extraction pressure level entering the booster module, so that the pressure of the steam below the target extraction pressure level pressurized by the steam compressor is higher than the pressure of the final extraction steam of the high-pressure cylinder. The steam below the target extraction pressure level is pressurized by the steam compressor, and then sequentially enters the newly added external steam cooler to heat the feed water and then enters the existing final high-pressure heater to heat the feed water. The pressure of the steam below the target extraction pressure level pressurized by the steam compressor is higher than the pressure of the final extraction steam of the high-pressure cylinder, so as to ensure that the pressure of the steam entering the newly added external steam cooler after being compressed by the steam compressor is higher than the pressure of the final extraction steam entering the existing final high-pressure heater, thereby ensuring that the feed water is heated to a higher temperature, so as to improve the feed water temperature of the unit under the deep peak shaving condition.

[0042] When the steam at the steam side outlet of the newly added external steam cooler enters the existing final high-pressure heater to heat the feed water, the extraction isolation valve on the extraction steam pipeline of the existing final high-pressure heater is in a closed state, and the steam pressure at the steam side outlet of the newly added external steam cooler is higher than the final extraction steam pressure of the high-pressure cylinder. The extraction isolation valve is in a closed state, and the steam at the steam side outlet of the newly added external steam cooler is sent into the existing final high-pressure heater to replace the high-pressure cylinder final extraction steam of the extraction pipeline. 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, so that the steam pressure entering the existing final high-pressure heater is higher than the regenerative extraction steam of the high-pressure cylinder, thereby further improving the feed water temperature entering the boiler.

[0043] As shown in Figure 2As shown, the pipeline of the booster module is provided with a newly added steam extraction isolation valve, which is located upstream of the steam compressor. By adjusting the flow of fluid into the booster module through the newly added steam extraction isolation valve, the safety and flexibility of system operation can be ensured and improved when the steam compressor, the newly added external steam cooler and other equipment fail by closing the newly added steam extraction isolation valve to prevent steam from entering the booster module.

[0044] Of course, the pipeline of the booster module is also provided with a heat exchanger, which is located upstream of the steam compressor or between the steam compressor and the newly added external steam cooler. By arranging a heat exchanger in the pipeline of the booster module, the steam in the pipeline can enter the heat exchanger to heat other working substances such as air, water and coal, and then enter the corresponding equipment such as the heat exchanger. If the heat exchanger is arranged upstream of the steam compressor, the steam below the target steam extraction pressure level first enters the heat exchanger to heat other working substances such as air, water and coal, and then enters the newly added external steam cooler to heat the feed water after being pressurized by the steam compressor. In this way, the steam temperature entering the steam compressor can be reduced, and the steam flow of the newly added external steam cooler can be relatively increased. If the heat exchanger is arranged between the steam compressor and the newly added external steam cooler, the steam below the target steam extraction pressure level first enters the heat exchanger to heat other working substances such as air, water and coal after being pressurized by the steam compressor, and then enters the newly added external steam cooler to heat the feed water. In this way, the steam temperature entering the newly added external steam cooler can be reduced, and the steam flow of the newly added external steam cooler can be relatively increased.

[0045] As shown, Figure 2 The steam below the target steam extraction pressure level entering the inlet of the booster module is the last stage extraction steam of the high-pressure cylinder of the unit, the inlet of the booster module is connected to the extraction pipeline through a pipeline, and the interface of the booster module connected to the extraction pipeline is located upstream of the extraction isolation valve. The last stage extraction steam of the high-pressure cylinder is pressurized by the booster module, then enters the newly added external steam cooler to heat the feed water, and then enters the existing last stage high-pressure heater to heat the feed water, so as to improve the feed water temperature entering the furnace of the unit under deep peak regulation condition. The interface of the booster module connected to the extraction pipeline is located upstream of the extraction isolation valve, the last stage extraction steam of the high-pressure cylinder is led out at the front end of the inlet of the extraction isolation valve, and the extraction isolation valve is closed. The last stage extraction steam of the high-pressure cylinder can enter the booster module, and the flexibility of the unit operation is improved.

[0046] Of course, in other embodiments, the steam source lower than the target extraction pressure level is the extraction steam in the regenerative system or the steam in the reheating system or the steam in the superheater system in the unit or in other units. Optimizing the steam lower than the target extraction pressure level to the extraction steam in the regenerative system or the steam in the reheating system or the steam in the superheater system in the unit or in other units improves the operation flexibility of the unit on the premise that the outlet steam pressure of the steam compressor is higher than the last-stage extraction steam pressure of the high-pressure cylinder.

[0047] The system configuration of the coal-fired unit for adaptive deep peak shaving flexible operation provided by the utility model is under the deep peak shaving working condition, taking 20% THA working condition as an example: the unit furnace inlet feed water temperature can be raised to 75% THA or even 100% THA feed water temperature level; further, with the increase of the unit furnace inlet feed water temperature, the economizer inlet water temperature is improved, and then the economizer outlet water temperature is improved, and the economizer outlet flue gas temperature is improved and meets the denitration inlet flue gas temperature requirement; while the economizer outlet water temperature is improved, a certain feed water pressure is maintained, so that the economizer outlet feed water maintains a certain subcooling degree; further, with the increase of the economizer outlet water temperature, the water wall inlet water temperature is improved, and then the water wall inlet enthalpy deficit is reduced, and the hydrodynamic stability is strengthened; with the increase of the water wall inlet water temperature, the water wall outlet steam can maintain a certain superheat degree, that is, the boiler dry running is realized. And the large-scale modification of the boiler and the steam turbine thermal system is avoided, the wide load range operation of the unit responding to the deep peak shaving of the power grid is better adapted, and the operation economy and flexibility of the unit are improved.

[0048] Taking the data of 20% THA working condition of a 1000MW ultra-supercritical unit as an example, the high-pressure cylinder of the unit adopts full-circumferential admission, and no regulating stage is configured.

[0049] Prior art scheme: the main generator load is 200MW, the existing last-stage high-pressure heater inlet steam pressure and temperature parameters are 1.75MPa and 436℃, the outlet feed water 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, the economizer outlet flue gas temperature is 245℃, the water wall outlet is wet saturated steam, the unit is in a wet state running state, and the denitration system cannot be put into use.

[0050] The embodiment scheme: the main generator load is 200MW, the existing last stage extraction steam pressure and temperature parameters are 1.01MPa and 339 DEG C, the existing last stage high pressure heater inlet steam pressure and temperature parameters are 5.8MPa and 392 DEG C after steam compressor pressurization and the newly added external steam cooler temperature reduction, and the outlet feed water pressure and temperature parameters are 11.9MPa and 274 DEG C, the water side temperature rise of the newly added external steam cooler is 6 DEG C, the coal economizer outlet water temperature is 307 DEG C, the supercooling degree is 17 DEG C, the coal economizer outlet water temperature is 312 DEG C, the superheating degree of the water cooling wall outlet is 13 DEG C, the unit is in a dry running state, the water cooling wall inlet water is relatively reduced by 69.7kJ / kg, the water cooling wall outlet steam temperature deviation is controlled, the water power stability is strengthened, and the denitration system is stably and continuously put into use.

[0051] The system configuration provided by the embodiment is suitable for deep peak shaving flexible operation of a coal-fired unit, and is suitable for the existing last stage high pressure heater and its extraction steam.

[0052] Although the specific embodiments of the utility model are described above, those skilled in the art should understand that this is only an example, the protection scope of the 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 the utility model, but these changes and modifications all fall within the protection scope of the utility model.

Claims

1. A system configuration for a coal-fired power unit to adapt to flexible operation under deep peak shaving, comprising a boiler, a deaerator system, a high-pressure cylinder, an existing final-stage high-pressure heater, feedwater pipelines, and steam pipelines, wherein the boiler includes an economizer, a water-cooled wall, and a superheater connected sequentially by pipelines, and the high-pressure cylinder adopts full-circumferential steam intake and is not equipped with a regulating stage; characterized in that, In the feedwater pipeline, a deaeration system, an existing final-stage high-pressure heater, and a newly added external steam cooler are sequentially installed 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 main steam throttling component is installed on the main steam pipeline, and an extraction steam isolation valve is arranged on the extraction steam pipeline. A pressurization module is connected to the steam-side inlet of the newly added external steam cooler. Steam with a pressure lower than the target extraction steam pressure level is connected to the inlet of the existing final-stage high-pressure heater. 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.

2. The 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 pressurized by the steam compressor to a pressure higher than the pressure of the final stage extraction steam of the high-pressure cylinder.

3. The system configuration as described in claim 2, characterized in that, When the steam from the steam-side outlet of the newly added external steam cooler enters the existing final stage high-pressure heater to heat the feedwater, the extraction steam isolation valve on the extraction steam pipeline of the existing final stage high-pressure heater is in the closed state, and the steam pressure at the steam-side outlet of the newly added external steam cooler is higher than the extraction steam pressure of the final stage of the high-pressure cylinder.

4. The 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 upstream of the steam compressor.

5. The system configuration as described in claim 4, characterized in that, A heat exchanger is also installed in the pipeline of the booster module. The heat exchanger is located upstream of the steam compressor or between the steam compressor and the newly added external steam cooler.

6. The system configuration as described in claim 4, characterized in that, The steam below the target extraction pressure level originates from the final stage extraction of the high-pressure cylinder. The inlet of the booster module is connected to the extraction steam pipeline via a pipe, and the interface of the booster module connected to the extraction steam pipeline is located upstream of the extraction steam isolation valve.

7. The system configuration as described in claim 6, 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 system configuration as described in claim 1, characterized in that, The main steam throttling assembly is a high-pressure cylinder inlet valve group or a regulating valve.

9. The system configuration as described in any one of claims 1-8, characterized in that, The system is configured to: use the main steam throttling component to throttle the main steam in order to maintain a certain feedwater pressure and keep the economizer outlet feedwater at a certain degree of subcooling.

10. The 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 from the economizer outlet to the high-pressure cylinder inlet, and the throttling component is adjusted to maintain a certain feedwater pressure.

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