A lignite-fired unit regulation system of an integrated boiler-furnace coupling system and a working method thereof

Abstract

The application discloses a lignite-fired unit regulation system of an integrated machine-boiler coupling system and a working method, the lignite-fired power generation system comprising a boiler, a steam turbine and a generator; the machine-boiler coupling system comprising a primary air reheater, an air preheater bypass system and a tail flue gas waste heat utilization system. The primary air reheater is arranged to improve the temperature of the primary air entering the pulverizing system, ensure the drying output of the pulverizing system, improve the lignite combustion in the furnace and improve the boiler efficiency. Meanwhile, the arrangement of the machine-boiler coupling system enhances the automatic generation control adjustment performance and the load increase / decrease rate of the unit. When the unit needs to increase the load, the steam flow regulation valve opening of the primary air reheater is increased, the baffle opening of the air preheater bypass system is increased, the boiler heat storage is used more to heat the feed water, the steam turbine backheating extraction is reduced, the unit climbing capacity and the primary frequency modulation capacity are increased, and the operation flexibility of the lignite-fired power generation unit is enhanced.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation, and relates to the technical field of thermal system control optimization design. Specifically, it relates to a control system and working method for a lignite-fired power unit with an integrated boiler-machine coupling system. Background Technology

[0002] Lignite is characterized by high volatile matter, high moisture content, low calorific value, high ash content, low ash fusion point, low abrasiveness, and easy spontaneous combustion. my country has vast lignite reserves, it is easy to mine, and its price is generally low. It is mainly distributed in Inner Mongolia, Northeast China, and Yunnan. The total moisture content of lignite is generally between 30% and 60%. Before entering the boiler furnace, lignite must undergo drying treatment to facilitate subsequent pulverized coal grinding and combustion. Because the unit burns high-moisture lignite, the pulverizing system must have sufficient drying capacity. For a positive-pressure direct-fired pulverizing system using hot air as a desiccant, the hot air entering the coal mill must have a sufficiently large volume and a relatively high temperature. The inlet air temperature generally needs to reach 330℃~370℃, which is about 100℃ higher than the approximately 260℃ air temperature for conventional bituminous coal. This high air temperature is obtained by heating the high-temperature flue gas through a rotary preheater, which determines that the flue gas temperature entering the rotary preheater generally needs to reach above 420℃. Therefore, the exhaust gas temperature of the lignite furnace is relatively high. If the exhaust gas temperature is reduced by increasing the heat exchange area of ​​the air preheater, the area of ​​the air preheater would exceed a reasonable range and be impractical. If the pulverizing system adopts a flue gas extraction and drying system, that is, extracting part of the boiler flue gas at 600-800℃ and sending it together with the flue gas passing through the preheater into the coal mill to dry the lignite before sending it into the furnace, this method can solve the problem of lignite drying, but it has some drawbacks: a high-temperature flue gas extraction system is required, which reduces the thermal utilization efficiency of the flue gas and increases the complexity of the system; all the extracted flue gas and the moisture evaporated from the coal enter the boiler furnace, which increases the boiler size and cost; it increases the boiler exhaust volume and the power consumption of the fans; and the ventilation volume inside the coal mill is large, requiring a larger coal mill capacity. Summary of the Invention

[0003] In response to the high moisture content of lignite, which can reach up to 60%, this invention provides a high-moisture lignite power generation thermal system with integrated boiler reheat steam extraction and drying. This system can effectively reduce the moisture content of lignite, improve the operation of the pulverizing system, enhance boiler combustion efficiency, and increase the system's power generation efficiency. At the same time, by utilizing the regulation of the primary air reheater and the boiler-turbine coupling system, the system can enhance the automatic power generation control regulation performance of the unit during peak shaving and frequency regulation, reduce the response time of the automatic power generation control, increase the regulation rate, enhance the unit's load-changing capacity, and improve the flexibility of unit operation.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A control system for a lignite-fired power plant unit with an integrated boiler-turbine coupling system includes a lignite-fired power generation system and a boiler-turbine coupling system;

[0006] The lignite-fired power generation system includes a boiler, a steam turbine, and a generator. The main steam outlet of boiler 100 is connected to the steam inlet of the high-pressure cylinder 201 of the steam turbine. The outlet of the high-pressure cylinder 201 is connected to the inlet of the boiler's low-temperature reheater 102. The steam outlet of the low-temperature reheater 102 is divided into two paths: one connected to the high-temperature reheater 103, and the other connected to the steam inlet of the primary air reheater 401. The outlet of the high-temperature reheater 103 is connected to the intermediate-pressure cylinder 202 of the steam turbine. The secondary air inlet of boiler 100 is connected to the environment via air preheater 105 and secondary air heater 306. The primary air inlet of boiler 100 is connected to the pulverizing system 101, primary air reheater 401, and air preheater 306. Heater 105 and primary air heater 305 are in communication with the environment; the outlet of intermediate pressure cylinder 202 of the steam turbine is connected to the inlet of low pressure cylinder 203 of the steam turbine; the steam outlet of low pressure cylinder 203 of the steam turbine is connected to the steam inlet of condenser 204; the water outlet of condenser 204 is connected in sequence to condensate pump 205, low pressure heater 206, deaerator 207, feedwater pump 208, and high pressure heater 210; the feedwater outlet of high pressure heater 210 is connected to the feedwater inlet of boiler 100; the extraction ports of each regenerative steam extraction of the steam turbine are connected to the high pressure heater 210 and low pressure heater 206 of the steam turbine regenerative system; generator 501 is connected to the steam turbine through mechanical transmission equipment.

[0007] The boiler-turbine coupling system includes a primary air reheater, an air preheater bypass system, and a tail-end flue gas waste heat utilization system. The air preheater bypass system is connected in parallel with the air preheater. The flue gas inlet of the air preheater bypass system is connected to the flue gas inlet of the air preheater 105 through the air preheater bypass system regulating baffle 301. The outlet of the air preheater bypass system is connected to the flue gas outlet of the air preheater 105. The air preheater bypass system includes a flue gas feedwater heat exchanger 302 located at the top and a flue gas condensate heat exchanger 303 located at the bottom. The flue gas feedwater heat exchanger 302 is connected in parallel with the turbine high-pressure heater 210, and the flue gas condensate heat exchanger 303 is connected in parallel with the turbine low-pressure heater 206.

[0008] The tail-end flue gas waste heat utilization system includes a flue gas heat transfer medium water exchanger 304, a primary air heater 305, and a secondary air heater 306. The outlet of the flue gas heat transfer medium water exchanger 304 is divided into three paths: the first path is connected to the outlet of the flue gas condensate heat exchanger 303 via a booster pump A308; the second path is connected to the inlet of the primary air heater 305 via a heat transfer medium water circulation pump 309 and a flow regulating valve B312; and the third path is connected to the inlet of the secondary air heater 306 via a heat transfer medium water circulation pump 309 and a flow regulating valve C313. The condensate outlet of the flue gas condensate heat exchanger 303 is divided into... Two paths are provided: one path connects to the outlet of the low-pressure heater 206 of the steam turbine, and the other path connects to the outlet of the heat medium water of the flue gas heat medium water exchanger 304 via a booster pump A308. The inlet of the flue gas heat medium water exchanger 304 is connected in three ways: the first path connects to the outlet of the primary air heater 305, the second path connects to the outlet of the secondary air heater 306, and the third path connects to the inlet of the flue gas condensate heat exchanger 303 via a flow regulating valve A307. By setting the flow regulating valve A307 and the booster pump A308, the flue gas heat medium water exchanger 304 and the flue gas condensate heat exchanger 303 are connected in parallel.

[0009] Preferably, the high-pressure heater 210 extraction section and the primary air reheater 401 extraction section, which are connected in parallel with the primary air reheater 401, are respectively equipped with flow regulating valve E403 and flow regulating valve D402, which are used to regulate the flow of the two circuits. The flow regulating valve D402 is closed to disconnect the primary air reheater 401 from the system. The steam extraction of the primary air reheater 401 and the high-pressure heater 210 extraction section can operate in parallel or independently.

[0010] Preferably, the flue gas feedwater heat exchanger 302 is connected in parallel with the turbine high-pressure heater 210. Feedwater from the outlet of the feedwater pump 208 is split into two paths: one enters the high-pressure heater 210, and the other enters the flue gas feedwater heat exchanger 302. The two feedwater paths then merge and enter the boiler 100 feedwater inlet. The flue gas condensate heat exchanger 303 is connected in parallel with the low-pressure heater 206. The condensate at 60-80℃ in the low-pressure heater 206 is split into two paths: one enters the next stage low-pressure heater 206. 06. Another path enters the flue gas condensate heat exchanger 303, and the two condensate streams converge at the deaerator 207. A flue gas feedwater heat exchanger flow regulating valve 310 is installed at the inlet of the flue gas feedwater heat exchanger 302 to regulate the inlet feedwater flow of the flue gas feedwater heat exchanger 302 or to shut off the feedwater. A flue gas condensate heat exchanger flow regulating valve 311 is installed at the inlet of the flue gas condensate heat exchanger 303 to regulate the condensate flow of the flue gas condensate heat exchanger 303 or to shut off the condensate.

[0011] Preferably, the air preheater bypass system is provided with an air preheater bypass system baffle 301, which is used to regulate the flue gas flow entering the air preheater bypass system or to disconnect the air preheater bypass system.

[0012] Preferably, the outlet temperature settings of the primary air heater 305 and the secondary air heater 306 are 45-60℃; the steam inlet temperature of the primary air reheater 401 is 540-560℃, and the outlet temperature is 360-390℃; the inlet primary air temperature of the primary air reheater 401 is 320-360℃, and the outlet temperature is 380-420℃.

[0013] Preferably, the coal mill of the pulverizing system 101 is a medium-speed coal mill. The coal mill is designed with 8-12% of cold air bypass mixed with reheated primary air before entering the coal mill to dry lignite. The outlet exhaust gas temperature of the coal mill is 60-70℃.

[0014] Preferably, the condensate inlet temperature of the flue gas condensate heat exchanger 303 is 60-80℃, and the condensate outlet temperature is 130-160℃; the feedwater inlet temperature of the flue gas feedwater heat exchanger 302 is 130-160℃, and the feedwater outlet temperature is 270-310℃; the flue gas inlet temperature of the flue gas heat medium water heat exchanger 304 is 120-140℃, and the flue gas outlet temperature is 80-100℃; the heat medium water inlet temperature of the flue gas heat medium water heat exchanger 304 is 60-80℃, and the outlet temperature is 110-120℃.

[0015] Preferably, the feedwater pump is driven by a small steam turbine, and the exhaust steam from the small steam turbine is introduced into the condenser.

[0016] The operating method of the lignite-fired unit control system of the integrated boiler-furnace coupling system is as follows: Primary air is heated by primary air heater 305 and air preheater 105, and then passes through primary air reheater 401. The steam from the outlet of low-temperature reheater 102 releases heat to the primary air in primary air reheater 401 and then merges with the extraction steam from high-pressure heater 210 to heat the feedwater. The steam flow rate through primary air reheater 401 is adjusted according to the moisture content of raw coal, ambient temperature and unit load factors to increase the primary air temperature by 40-60℃. The heated primary air enters the pulverizing system 101 to dry lignite, ensuring the drying output of the boiler pulverizing system. The dried coal powder and primary air are mixed and then enter the furnace of boiler 100 for combustion to release heat and heat the boiler water-side working fluid. Secondary air is also heated by secondary air heater 306 and air preheater 105 and then enters the boiler furnace to provide sufficient air for coal powder combustion.

[0017] After absorbing heat, the water in boiler 100 becomes high-temperature steam. This high-temperature steam enters the high-pressure cylinder 201 of the turbine to perform work. The exhaust steam from the high-pressure cylinder 201 then splits into two paths: one path enters the low-temperature reheater 102 and the high-temperature reheater 103 to absorb heat before entering the intermediate-pressure cylinder of the turbine; the other path provides extraction steam to the turbine to heat the feedwater. The exhaust steam from the intermediate-pressure cylinder 202 enters the low-pressure cylinder of the turbine, and the exhaust steam from the low-pressure cylinder 203 enters the condenser (204) for condensation. Afterward, the steam passes through the condensate pump (…). 205), low-pressure heater (206), deaerator 207, and then pressurized by feedwater pump 208 driven by small steam turbine 209 before entering high-pressure heater 210, and finally entering boiler 100 to complete the working fluid circulation; in addition, in order to coordinate the heat utilization on both sides of the boiler and turbine, part of the feedwater passes through flue gas feedwater heat exchanger regulating valve 310 to flue gas feedwater heat exchanger 302 to absorb flue gas heat, and then mixes with high-pressure heater feedwater 210 before entering boiler 100 feedwater inlet, and part of the condensate passes through The flue gas condensate heat exchanger regulating valve 311 leads to the flue gas condensate heat exchanger 303, where it absorbs heat and then converges at the deaerator 207. The air preheater bypass system baffle 301 is adjusted to regulate the amount of flue gas entering the air preheater bypass, thereby adjusting the heat absorption of the flue gas feedwater heat exchanger 302 and the flue gas condensate heat exchanger 303. The heat transfer water, after absorbing heat in the flue gas heat transfer water heat exchanger 304, is pressurized by the heat transfer water circulation pump 309 and then divided into two paths, entering the primary air heater 305 and the secondary air heater 305 respectively. Heater 306 preheats the air; if the outlet temperature of primary air heater 305 and secondary air heater 306 differs from the design value by 20°C or more, then the flow regulating valve A307 and booster pump A308 are opened to connect flue gas condensate heat exchanger 303 in series with primary air heater 305 and secondary air heater 306, mixing condensate and heat transfer water to increase the outlet temperature of heat transfer water, ensuring that the outlet air temperature of primary air heater 305 and secondary air heater 306 reaches the set value.

[0018] This system enhances the performance of the unit's automatic power generation control, reduces the response time of the automatic power generation control, and increases the regulation rate of the automatic power generation control. Specifically, when the unit receives an automatic power generation control load increase command, it reduces the opening of flow regulating valve E403 and increases the opening of flow regulating valve D402, thereby reducing the flow rate at the regenerating extraction point of the turbine cylinder and correspondingly increasing the turbine output. Meanwhile, the extraction steam from the boiler low-temperature reheater 102 to the primary air reheater 401 increases to compensate for the reduction in the turbine's regenerating extraction steam, ensuring that the feedwater outlet temperature of the high-pressure heater and low-pressure heater of the turbine's regenerating system reaches the predetermined value. If the unit receives an automatic power generation control load decrease command, it increases the opening of flow regulating valve E403 and decreases the opening of flow regulating valve D402, utilizing the heat storage of the primary air reheater 401 to heat the primary air, ensuring that the feedwater outlet temperature of the high-pressure heater and low-pressure heater of the turbine's regenerating system reaches the predetermined value.

[0019] This can increase the unit's ramp-up capability and improve its primary frequency regulation capability. Specifically, when the grid frequency is lower than the rated value and the turbine speed is lower than the rated speed, the unit needs to quickly increase the load. Therefore, the opening of flow regulating valve E403 is reduced, and the opening of flow regulating valve D402 is increased. This reduces the regenerative extraction steam flow rate in the turbine cylinder, resulting in a corresponding increase in turbine output. Meanwhile, the extraction steam flow rate from the boiler low-temperature reheater 102 to the primary air reheater 401 increases to compensate for the reduced regenerative extraction steam flow rate from the turbine. Simultaneously, the baffle 3 of the air preheater bypass system is increased. The opening degrees of valves 01, 310, and 311 of the flue gas feedwater heat exchanger and the flue gas condensate heat exchanger utilize more flue gas heat from the air preheater bypass flue to heat the feedwater and condensate, reducing the turbine regenerative extraction steam flow and rapidly increasing the turbine output. Increasing the opening degree of the air preheater bypass system damper 301 will reduce the flue gas flow through the air preheater 105, resulting in a decrease in the primary and secondary air temperatures at the outlet of the air preheater 105. At this point, the opening degree of flow control valve B312 can be reduced or even closed. Increasing the opening of flow regulating valve C313 utilizes more heat from the heat medium water in flue gas heat medium water exchanger 304 to heat the secondary air in the secondary air heater (306), thereby increasing the secondary air temperature at the air preheater inlet. The decrease in primary air temperature is compensated by increasing the opening of flow regulating valve D402 to increase the steam extraction rate of boiler low-temperature superheater 102. Increasing its steam extraction rate can increase the rise in primary air temperature in primary air reheater 401, ensuring that the drying output of the pulverizing system matches the current load. When the grid frequency is higher than the rated value... When the turbine speed is higher than the rated speed, the unit needs to reduce the load quickly. Therefore, the opening of the flow regulating valve E403 is increased and the opening of the flow regulating valve D402 is decreased, thereby increasing the regenerative extraction steam flow of the turbine cylinder and reducing the turbine output accordingly. Meanwhile, the extraction steam from the boiler low-temperature reheater 102 to the primary air reheater 401 is reduced to maintain the feedwater temperature of the high-pressure heater and low-pressure heater of the regenerative system at the predetermined value. The heat release part corresponding to the reduced extraction steam of the primary air reheater is compensated by the heat storage of the primary air reheater 401.Simultaneously, the opening of the air preheater bypass system damper 301, the opening of the flue gas feedwater heat exchanger flow regulating valve 310, and the opening of the flue gas condensate heat exchanger flow regulating valve 311 are reduced. This reduces the use of flue gas heat from the air preheater bypass flue to heat the feedwater and condensate, increases the turbine regenerative extraction steam flow, and rapidly reduces the turbine output. Reducing the opening of the air preheater bypass system damper 301 leads to an increase in the flue gas flow of the air preheater 105, resulting in a greater increase in the primary and secondary air temperatures at the outlet of the air preheater 105. At this point, the flow regulating valve B3 is increased. The opening degree of flow regulating valve C313 is reduced by 12 to utilize more heat from the heat medium water in the flue gas heat medium water heat exchanger 304 to heat the primary air in the primary air heater, thereby increasing the primary air temperature at the inlet of air preheater 105. This ensures that the outlet temperature of primary air reheater 401 reaches the predetermined value, guaranteeing that the drying output of the pulverizing system matches the current load. The resulting decrease in the secondary air temperature at the outlet of secondary air heater 306 is compensated by reducing the opening degree of the air preheater bypass system baffle 301 to increase the increase in secondary air temperature within the air preheater.

[0020] This invention proposes using the reheat heat of low-temperature reheat steam to reheat primary air to ensure the drying output of the pulverizing system. The primary air, after being heated, then re-enters the pulverizing system to dry lignite. The design is simple, easy to operate, and explosion-proof. The integrated primary air reheater can reduce the flue gas temperature entering the air preheater and the exhaust gas temperature of the air preheater, improving boiler efficiency and offering good economic benefits.

[0021] This invention also enhances the flexibility of lignite-fired power generating units. On the one hand, the proportion of residential electricity consumption is increasing; on the other hand, the proportion of renewable energy sources such as wind and solar power, which are intermittent and unpredictable, connected to the grid is constantly increasing. This leads to increased volatility on both the load and power supply sides of the power grid, thus requiring thermal power units to participate more in peak shaving and frequency regulation. This invention utilizes the regulation of the primary air reheater and the boiler-turbine coupling system to enhance the unit's AGC (Automatic Generation Control) performance during peak shaving and frequency regulation, reducing the AGC response time and increasing the regulation rate, thereby increasing the unit's load-changing capacity and improving operational flexibility. Compared with existing technologies, this invention has the following advantages:

[0022] 1. This invention uses low-temperature reheat steam as a heat source and utilizes a primary air reheater to increase the temperature of the primary air entering the pulverizing system, thereby ensuring the drying output of the pulverizing system under low ambient temperature and low load conditions. The system has a simple structure, is easy to operate, and is safe and explosion-proof, which increases the safety of the power generation system, improves the combustion of lignite in the furnace, increases boiler efficiency, and has good economic benefits.

[0023] 2. The present invention is equipped with a boiler-turbine coupling system including a primary air reheater. When responding to the unit's automatic power generation control command, the steam flow regulating valve of the primary air reheater, the extraction steam regulating valve, the baffle of the air preheater bypass system, etc., can be adjusted to achieve the goal of rapid response to the automatic power generation control command.

[0024] 3. The unit is equipped with a boiler-turbine coupling system including a primary air reheater. When the unit needs to adjust the primary frequency to increase or decrease the load, the steam flow regulating valve of the primary air reheater, the extraction steam regulating valve, the baffle of the air preheater bypass system, etc., can be adjusted to achieve the goal of rapid load change of the unit, thereby enhancing the unit's primary frequency regulation capability and operational flexibility. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a lignite-fired power unit with an integrated machine-furnace coupling system according to the present invention.

[0027] Explanation of reference numerals in the attached drawings: 100, Boiler; 101, Pulverizing system; 102, Low-temperature reheater; 103, High-temperature reheater; 104, Flue gas damper; 105, Air preheater; 201, High-pressure cylinder; 202, Intermediate-pressure cylinder; 203, Low-pressure cylinder; 204, Condenser; 205, Condensate pump; 206, Low-pressure heater; 207, Deaerator; 208, Feedwater pump; 209, Small steam turbine; 210, High-pressure heater; 301, Air preheater bypass system damper; 302, Flue gas feedwater heat exchanger; 3 03. Flue gas condensate heat exchanger; 304. Flue gas heat transfer medium water heat exchanger; 305. Primary air heater; 306. Secondary air heater; 307. Flow regulating valve A; 308. Booster pump A; 309. Heat transfer medium water circulation pump; 310. Flue gas feedwater heat exchanger flow regulating valve; 311. Flue gas condensate heat exchanger flow regulating valve; 312. Flow regulating valve B; 313. Flow regulating valve C; 401. Primary air reheater; 402. Flow regulating valve D; 403. Flow regulating valve E; 501. Generator. Detailed Implementation

[0028] like Figure 1As shown, the present invention discloses an integrated boiler-turbine coupling system for a lignite-fired power generation unit, comprising a lignite-fired power generation system and a boiler-turbine coupling system. The boiler-turbine coupling system includes a primary air reheater, an air preheater bypass system, and a tail-end flue gas waste heat utilization system. The lignite-fired power generation system consists of a boiler, a steam turbine, and a generator.

[0029] The overall system connections are as follows:

[0030] The main steam outlet of boiler 100 is connected to the steam inlet of high-pressure cylinder 201 of steam turbine. The outlet of high-pressure cylinder 201 of steam turbine is connected to the inlet of low-temperature reheater 102 of boiler. The steam outlet of low-temperature reheater 102 of boiler is divided into two paths: one path is connected to high-temperature reheater 103 of boiler, and the other path is connected to the steam inlet of primary air reheater 401. The outlet of high-temperature reheater 103 of boiler is connected to intermediate-pressure cylinder 202 of steam turbine. The secondary air inlet of boiler 100 is connected to the environment through air preheater 105 and secondary air heater 306. The primary air inlet of boiler is connected to the environment through pulverizing system 101, primary air reheater 401, air preheater 105, and primary air heater 305.

[0031] The outlet of the intermediate-pressure cylinder 202 of the steam turbine is connected to the inlet of the low-pressure cylinder 203 of the steam turbine; the steam outlet of the low-pressure cylinder 203 of the steam turbine is connected to the steam inlet of the condenser 204; the water outlet of the condenser 204 is connected in sequence to the condensate pump 205, the low-pressure heater 206, the deaerator 207, the feedwater pump 208, and the high-pressure heater 210; the feedwater outlet of the high-pressure heater 210 is connected to the feedwater inlet of the boiler 100; the extraction ports of each regenerative steam extraction of the steam turbine are connected to the high-pressure heater 210 and the low-pressure heater 206 of the steam turbine regenerative system.

[0032] Generator 501 is connected to the steam turbine via a mechanical transmission device;

[0033] The air preheater bypass system is connected in parallel with the air preheater. The flue gas inlet of the air preheater bypass system is connected to the flue gas inlet of the air preheater 105 through the air preheater bypass system regulating baffle 301. The outlet of the air preheater bypass system is connected to the flue gas outlet of the air preheater 105. The air preheater bypass system includes a flue gas feedwater heat exchanger 302 located at the top and a flue gas condensate heat exchanger 303 located at the bottom. The flue gas feedwater heat exchanger 302 is connected in parallel with the turbine high-pressure heater 210, and the flue gas condensate heat exchanger 303 is connected in parallel with the turbine low-pressure heater 206.

[0034] The tail-end flue gas waste heat utilization system includes a flue gas heat transfer medium water exchanger 304, a primary air heater 305, and a secondary air heater 306. The outlet of the flue gas heat transfer medium water exchanger 304 is divided into three paths: the first path is connected to the outlet of the flue gas condensate heat exchanger 303 via a booster pump A308; the second path is connected to the inlet of the primary air heater 305 via a heat transfer medium water circulation pump 309 and a flow regulating valve B312; and the third path is connected to the inlet of the secondary air heater 306 via a heat transfer medium water circulation pump 309 and a flow regulating valve C313. The condensate outlet of the flue gas condensate heat exchanger 303 is divided into... Two paths are provided: one path connects to the outlet of the low-pressure heater 206 of the steam turbine, and the other path connects to the outlet of the heat medium water of the flue gas heat medium water exchanger 304 via a booster pump A308. The inlet of the flue gas heat medium water exchanger 304 is connected in three ways: the first path connects to the outlet of the primary air heater 305, the second path connects to the outlet of the secondary air heater 306, and the third path connects to the inlet of the flue gas condensate heat exchanger 303 via a flow regulating valve A307. By setting the flow regulating valve A307 and the booster pump A308, the flue gas heat medium water exchanger 304 and the flue gas condensate heat exchanger 303 are connected in parallel.

[0035] The high-pressure heater 210 extraction section and the primary air reheater 401 extraction section, which are connected in parallel with the primary air reheater 401, are respectively equipped with flow regulating valve E403 and flow regulating valve D402. The flow of the two circuits can be regulated, and the flow regulating valve D402 can be closed to disconnect the primary air reheater 401 from the system. The steam extraction of the primary air reheater 401 can be operated in parallel with the high-pressure heater 210 extraction section, or it can be operated independently.

[0036] The flue gas feedwater heat exchanger 302 is connected in parallel with the turbine high-pressure heater 210. The feedwater from the outlet of the feedwater pump 208 splits into two paths: one enters the high-pressure heater 210, and the other enters the flue gas feedwater heat exchanger 302. The two feedwater paths then merge and enter the boiler 100 feedwater inlet. The flue gas condensate heat exchanger 303 is connected in parallel with the low-pressure heater 206. The condensate at 60-80℃ in the low-pressure heater 206 splits into two paths: one enters the next stage low-pressure heater 206. One stream of condensate enters the flue gas condensate heat exchanger 303, and the two streams of condensate converge at the deaerator 207. The flue gas feedwater heat exchanger 302 is equipped with a flue gas feedwater heat exchanger flow regulating valve 310, which can regulate the inlet feedwater flow of the flue gas feedwater heat exchanger 302 or shut off the feedwater. The flue gas condensate heat exchanger 303 is equipped with a flue gas condensate heat exchanger flow regulating valve 311, which can regulate the condensate flow entering the flue gas condensate heat exchanger 303 or shut off the condensate.

[0037] The air preheater bypass system is equipped with an air preheater bypass system baffle 301, which can adjust the flue gas flow into the air preheater bypass system or disconnect the air preheater bypass system.

[0038] The operating method of the lignite-fired unit control system of the integrated boiler-furnace coupling system is characterized in that: after the primary air is heated by the primary air heater 305 and the air preheater 105, it passes through the primary air reheater 401. The steam from the outlet of the low-temperature reheater 102 releases heat to the primary air in the primary air reheater 401 and then merges with the steam extracted from the high-pressure heater 210 to heat the feedwater. The steam flow rate through the primary air reheater 401 is adjusted according to factors such as the moisture content of the raw coal, the ambient temperature, and the unit load to increase the primary air temperature by 40-60°C. The heated primary air enters the pulverizing system 101 to dry the lignite, ensuring the drying output of the boiler pulverizing system. The dried coal powder and primary air are mixed and then enter the furnace of the boiler 100 for combustion to release heat and heat the boiler water-side working fluid. The secondary air, after being heated by the secondary air heater 306 and the air preheater 105, also enters the boiler furnace to provide sufficient air for the combustion of the coal powder.

[0039] After absorbing heat, the water in boiler 100 becomes high-temperature steam. This high-temperature steam enters the high-pressure cylinder 201 of the turbine to perform work. The exhaust steam from the high-pressure cylinder 201 then splits into two paths: one path enters the low-temperature reheater 102 and the high-temperature reheater 103 to absorb heat before entering the intermediate-pressure cylinder of the turbine; the other path provides extraction steam to the turbine to heat the feedwater. The exhaust steam from the intermediate-pressure cylinder 202 enters the low-pressure cylinder of the turbine, and the exhaust steam from the low-pressure cylinder 203 enters the condenser (204) for condensation. Afterward, the steam passes through the condensate pump (…). 205), low-pressure heater (206), deaerator 207, and then pressurized by feedwater pump 208 driven by small steam turbine 209 before entering high-pressure heater 210, and finally entering boiler 100 to complete the working fluid circulation; in addition, in order to coordinate the heat utilization on both sides of the boiler and turbine, part of the feedwater passes through flue gas feedwater heat exchanger regulating valve 310 to flue gas feedwater heat exchanger 302 to absorb flue gas heat, and then mixes with high-pressure heater feedwater 210 before entering boiler 100 feedwater inlet, and part of the condensate passes through The flue gas condensate heat exchanger regulating valve 311 leads to the flue gas condensate heat exchanger 303, where it absorbs heat and then converges at the deaerator 207. Adjusting the air preheater bypass system baffle 301 regulates the amount of flue gas entering the air preheater bypass, thereby adjusting the heat absorption of the flue gas feedwater heat exchanger 302 and the flue gas condensate heat exchanger 303. The heat transfer water, after absorbing heat in the flue gas heat transfer water heat exchanger 304, is pressurized by the heat transfer water circulation pump 309 and then divided into two paths, entering the primary air heater 305 and the secondary air heater 306 respectively. The air heater 306 preheats the air; if the outlet temperature of the primary air heater 305 and the secondary air heater 306 differs from the design value by 25°C or more, the flow regulating valve A307 and the booster pump A308 are opened to connect the flue gas condensate heat exchanger 303 in series with the primary air heater 305 and the secondary air heater 306, mixing the condensate and the heat transfer water to increase the outlet temperature of the heat transfer water, ensuring that the outlet air temperature of the primary air heater 305 and the secondary air heater 306 reaches the set value.

[0040] This can enhance the automatic power generation control and regulation performance of the unit, reduce the response time of the automatic power generation control, and increase the regulation rate of the automatic power generation control. Specifically, when the unit receives an automatic power generation control load increase command, it reduces the opening of the flow regulating valve E403 and increases the opening of the flow regulating valve D402, thereby reducing the flow rate at the regenerating extraction point of the turbine cylinder and increasing the turbine output accordingly. Meanwhile, the extraction steam from the boiler low-temperature reheater 102 to the primary air reheater 401 increases to compensate for the reduction in the turbine's regenerating extraction steam, so that the feedwater outlet temperature of the turbine's regenerating heater reaches the predetermined value. If the unit receives an automatic power generation control load decrease command, it increases the opening of the flow regulating valve E403 and decreases the opening of the flow regulating valve D402, using the heat storage of the primary air reheater 401 to heat the primary air, so that the feedwater outlet temperature of the high-pressure heater and low-pressure heater of the turbine's regenerating system reaches the predetermined value.

[0041] This can increase the unit's ramp-up capability and improve its primary frequency regulation capability. Specifically, when the grid frequency is lower than the rated value and the turbine speed is lower than the rated speed, the unit needs to quickly increase the load. Therefore, the opening of flow regulating valve E403 is reduced, and the opening of flow regulating valve D402 is increased. This reduces the regenerative extraction steam flow rate in the turbine cylinder, resulting in a corresponding increase in turbine output. Meanwhile, the extraction steam flow rate from the boiler low-temperature reheater 102 to the primary air reheater 401 increases to compensate for the reduced regenerative extraction steam flow rate from the turbine. Simultaneously, the baffle 301 of the air preheater bypass system is increased. The opening degrees of the flue gas feedwater heat exchanger flow regulating valve 310 and the flue gas condensate heat exchanger flow regulating valve 311 utilize more flue gas heat from the air preheater bypass flue to heat the feedwater and condensate, reducing the turbine regenerative extraction steam flow and rapidly increasing the turbine output. Increasing the opening degree of the air preheater bypass system damper 301 will reduce the flue gas flow through the air preheater 105, lowering the primary and secondary air temperatures at the outlet of the air preheater 105. At this point, the opening degree of the flow regulating valve B312 can be reduced or even closed to increase the flow rate. The flow regulating valve C313 is opened to utilize more heat from the heat medium water in the flue gas heat medium water exchanger 304 to heat the secondary air in the secondary air heater (306), thereby increasing the secondary air temperature at the air preheater inlet. The decrease in primary air temperature can be compensated by increasing the opening of the flow regulating valve D402 to increase the steam extraction rate of the boiler low-temperature superheater 102. Increasing the steam extraction rate can increase the rise in primary air temperature in the primary air reheater 401, ensuring that the drying output of the pulverizing system matches the current load. When the grid frequency is higher than the rated value... When the turbine speed is higher than the rated speed, the unit needs to reduce the load quickly. Therefore, the opening of the flow regulating valve E403 is increased and the opening of the flow regulating valve D402 is decreased, thereby increasing the regenerative extraction steam flow of the turbine cylinder and reducing the turbine output accordingly. Meanwhile, the extraction steam from the boiler low-temperature reheater 102 to the primary air reheater 401 is reduced to maintain the feedwater temperature of the high-pressure heater and low-pressure heater of the regenerative system at the predetermined value. The heat released corresponding to the reduced extraction steam of the primary air reheater can be partially compensated by the heat storage of the primary air reheater 401.Simultaneously, reduce the opening of the air preheater bypass system damper 301, the flue gas feedwater heat exchanger flow regulating valve 310, and the flue gas condensate heat exchanger flow regulating valve 311. This reduces the use of flue gas heat from the air preheater bypass flue to heat feedwater and condensate, increases the turbine regenerative extraction steam flow, and rapidly reduces turbine output. Reducing the opening of the air preheater bypass system damper 301 leads to an increase in the flue gas flow of the air preheater 105, resulting in a greater increase in the primary and secondary air temperatures at the air preheater 105 outlet. At this point, the flow regulating valve B312 can be increased. The opening degree of the flow regulating valve C313 is reduced to utilize more heat from the heat medium water in the flue gas heat medium water exchanger 304 to heat the primary air in the primary air heater, thereby increasing the primary air temperature at the inlet of the air preheater 105. This ensures that the outlet temperature of the primary air reheater 401 reaches the predetermined value, guaranteeing that the drying output of the pulverizing system matches the current load. The resulting decrease in the secondary air temperature at the outlet of the secondary air heater 306 can be compensated for by reducing the opening degree of the air preheater bypass system baffle 301, thus increasing the increase in secondary air temperature within the air preheater.

[0042] As a preferred option, the outlet temperature setting of the primary air heater 305 and the secondary air heater 306 is 45-60℃; the temperature setting ensures that the air and the heat transfer medium water in the primary air heater and the secondary air heater maintain an average heat exchange temperature difference of 50-70℃, and the heater has a suitable heat exchange area and heat exchange performance.

[0043] As a preferred option, the steam inlet temperature of the primary air reheater is 540-560℃ and the outlet temperature is 360-390℃; this ensures a large heat exchange temperature difference between the steam and the hot primary air, and that the steam outlet temperature is higher than the saturation temperature, allowing the steam to enter the turbine high-pressure heater in a vapor state to heat the feedwater.

[0044] As a preferred option, the inlet primary air temperature of the primary air reheater is 320-360℃, and the outlet temperature is 380-420℃; increasing the primary air temperature by 40-60℃ increases the inlet air temperature of the coal mill and increases the dryness of the lignite.

[0045] As a preferred option, a medium-speed coal mill is selected for the pulverizing system. The coal mill is designed with 8-12% of cold air bypass mixed with reheated primary air before entering the coal mill to dry lignite. The outlet exhaust gas temperature of the coal mill is 60-70℃. The exhaust gas temperature is 7-10℃ higher than the dew point temperature of the humid air, which can not only avoid condensation of exhaust gas during coal powder transportation, but also make full use of the drying potential of the reheated primary air to achieve a good drying effect.

[0046] As a preferred option, the condensate inlet temperature of the flue gas condensate heat exchanger is 60-80℃, and the condensate outlet temperature is 130-160℃. The feedwater inlet temperature of the flue gas feedwater heat exchanger is 130-160℃, and the feedwater outlet temperature is 270-310℃. The inlet water temperature of the flue gas condensate heat exchanger is consistent with the condensate intake temperature of the steam turbine, and the outlet water temperature is close to the inlet water temperature of the deaerator, which is conducive to the safe, economical, and stable operation of the deaerator. The inlet water temperature of the flue gas feedwater heat exchanger is consistent with the outlet water temperature of the steam turbine feedwater pump, and the outlet water temperature is close to the boiler feedwater temperature, which is conducive to the economical operation of the unit.

[0047] As a preferred option, the flue gas inlet temperature of the flue gas heat transfer water heat exchanger is 120-140℃, the flue gas outlet temperature is 80-100℃, the heat transfer water inlet temperature of the flue gas heat transfer water heat exchanger is 60-80℃, and the outlet temperature is 110-120℃; the flue gas outlet temperature of the waste heat utilization system is kept at 80-100℃, which can not only prevent low-temperature corrosion of the waste heat utilization system, but also make full use of the waste heat of the flue gas to improve the economic efficiency of the unit.

[0048] As a preferred option, the feedwater pump is driven by a small steam turbine, and the exhaust steam from the small steam turbine is introduced into the condenser; the use of a steam-driven feedwater pump in the unit has higher operating economy and can save investment.

Claims

1. A control system for a lignite-fired power unit with an integrated boiler-machine coupling system, characterized in that: This includes lignite-fired power generation systems and boiler-turbine coupling systems; The lignite-fired power generation system includes a boiler, a steam turbine, and a generator; the main steam outlet of the boiler (100) is connected to the steam inlet of the high-pressure cylinder (201) of the steam turbine, the outlet of the high-pressure cylinder (201) of the steam turbine is connected to the inlet of the boiler low-temperature reheater (102), the steam outlet of the boiler low-temperature reheater (102) is divided into two paths, one path is connected to the high-temperature reheater (103) of the boiler, and the other path is connected to the steam inlet of the primary air reheater (401); the outlet of the high-temperature reheater (103) of the boiler is connected to the intermediate-pressure cylinder (202) of the steam turbine, the secondary air inlet of the boiler (100) is connected to the environment through the air preheater (105) and the secondary air heater (306); the primary air inlet of the boiler is connected to the pulverizing system (101), the primary air reheater (401), and the air preheater (105) through the pulverizing system (101), the primary air reheater (401), and the air preheater (105). 05) The primary air heater (305) is connected to the environment; the outlet of the intermediate pressure cylinder (202) of the steam turbine is connected to the inlet of the low pressure cylinder (203) of the steam turbine; the steam outlet of the low pressure cylinder (203) of the steam turbine is connected to the steam inlet of the condenser (204); the water outlet of the condenser (204) is connected in sequence to the condensate pump (205), the low pressure heater (206), the deaerator (207), the feed water pump (208), and the high pressure heater (210); the feed water outlet of the high pressure heater (210) is connected to the feed water inlet of the boiler (100); the extraction ports of each regenerative steam extraction of the steam turbine are respectively connected to the high pressure heater (210) and the low pressure heater (206) of the steam turbine regenerative system; the generator (501) is connected to the steam turbine through a mechanical transmission device; The boiler-turbine coupling system includes a primary air reheater, an air preheater bypass system, and a tail flue gas waste heat utilization system. The air preheater bypass system is connected in parallel with the air preheater. The flue gas inlet of the air preheater bypass system is connected to the flue gas inlet of the air preheater (105) through the air preheater bypass system regulating baffle (301). The outlet of the air preheater bypass system is connected to the flue gas outlet of the air preheater (105). The air preheater bypass system includes a flue gas feedwater heat exchanger (302) located at the top and a flue gas condensate heat exchanger (303) located at the bottom. The flue gas feedwater heat exchanger (302) is connected in parallel with the turbine high-pressure heater (210), and the flue gas condensate heat exchanger (303) is connected in parallel with the turbine low-pressure heater (206). The tail-end flue gas waste heat utilization system includes a flue gas heat transfer medium water heat exchanger (304), a primary air heater (305), and a secondary air heater (306). The outlet of the flue gas heat transfer medium water heat exchanger (304) is divided into three paths. The first path is connected to the outlet of the flue gas condensate heat exchanger (303) through a booster pump A (308). The second path is connected to the inlet of the primary air heater (305) through a heat transfer medium water circulation pump (309) and then through a flow regulating valve B (312). The third path is connected to the inlet of the secondary air heater (306) through a heat transfer medium water circulation pump (309) and then through a flow regulating valve C (313). The condensate outlet of the flue gas condensate heat exchanger (303) is... The system is divided into two paths: one path is connected to the outlet of the low-pressure heater (206) of the steam turbine, and the other path is connected to the outlet of the heat medium water of the flue gas heat medium water exchanger (304) through the booster pump A (308); the first path of the inlet of the flue gas heat medium water exchanger (304) is connected to the outlet of the primary air heater (305), the second path is connected to the outlet of the secondary air heater (306), and the third path is connected to the inlet of the flue gas condensate heat exchanger (303) through the flow regulating valve A (307); by setting the flow regulating valve A (307) and the booster pump A (308), the flue gas heat medium water exchanger (304) and the flue gas condensate heat exchanger (303) are connected in parallel.

2. The control system for a lignite-fired power unit with an integrated boiler-furnace coupling system according to claim 1, characterized in that, The high-pressure heater (210) extraction section and the primary air reheater (401) extraction section, which are connected in parallel with the primary air reheater (401), are respectively equipped with flow regulating valve E (403) and flow regulating valve D (402) to regulate the flow of the two circuits. The flow regulating valve D (402) is closed to disconnect the primary air reheater (401) from the system. The steam extraction of the primary air reheater (401) and the steam extraction of the high-pressure heater (210) are operated in parallel or separately.

3. The lignite-fired unit control system of an integrated boiler-furnace coupling system according to claim 2, characterized in that, The flue gas feedwater heat exchanger (302) is connected in parallel with the turbine high-pressure heater (210). The feedwater is split into two paths from the outlet of the feedwater pump (208), one path entering the high-pressure heater (210) and the other path entering the flue gas feedwater heat exchanger (302). After the two paths merge, the feedwater enters the boiler (100) feedwater inlet. The flue gas condensate heat exchanger (303) is connected in parallel with the low-pressure heater (206). The condensate at 60-80℃ in the low-pressure heater (206) is split into two paths, one path entering the next stage low-pressure heater (204). 6) Another path enters the flue gas condensate heat exchanger (303), and the two condensate streams converge in the deaerator (207); the flue gas feed water heat exchanger (302) is equipped with a flue gas feed water heat exchanger flow regulating valve (310) to regulate the inlet feed water flow of the flue gas feed water heat exchanger (302) or to shut off the feed water; the flue gas condensate heat exchanger (303) is equipped with a flue gas condensate heat exchanger flow regulating valve (311) to regulate the condensate flow of the flue gas condensate heat exchanger (303) or to shut off the condensate.

4. The control system for a lignite-fired power unit with an integrated boiler-machine coupling system according to claim 1, characterized in that, The air preheater bypass system is equipped with an air preheater bypass system baffle (301) for regulating the flue gas flow into the air preheater bypass system or disconnecting the air preheater bypass system.

5. The control system for a lignite-fired power unit with an integrated boiler-furnace coupling system according to claim 1, characterized in that, The outlet temperature settings of the primary air heater (305) and the secondary air heater (306) are 45-60℃; the steam inlet temperature of the primary air reheater (401) is 540-560℃ and the outlet temperature is 360-390℃; the inlet primary air temperature of the primary air reheater (401) is 320-360℃ and the outlet temperature is 380-420℃.

6. The control system for a lignite-fired power unit with an integrated boiler-machine coupling system according to claim 1, characterized in that, The pulverizing system (101) uses a medium-speed pulverizer. The pulverizer is designed with 8-12% of cold air bypass mixed with reheated primary air before entering the pulverizer to dry lignite. The outlet exhaust gas temperature of the pulverizer is 60-70℃.

7. The lignite-fired unit control system of an integrated boiler-machine coupling system according to claim 1, characterized in that, The condensate inlet temperature of the flue gas condensate heat exchanger (303) is 60-80℃, and the condensate outlet temperature is 130-160℃. The feedwater inlet temperature of the flue gas feedwater heat exchanger (302) is 130-160℃, and the feedwater outlet temperature is 270-310℃. The flue gas inlet temperature of the flue gas heat medium water heat exchanger (304) is 120-140℃, and the flue gas outlet temperature is 80-100℃. The heat medium water inlet temperature of the flue gas heat medium water heat exchanger (304) is 60-80℃, and the outlet temperature is 110-120℃.

8. The operating method of the lignite-fired unit control system of the integrated machine-furnace coupling system as described in claim 3, characterized in that: After being heated by the primary air heater (305) and air preheater (105), the primary air passes through the primary air reheater (401). The outlet steam of the low-temperature reheater (102) releases heat to the primary air in the primary air reheater (401) and then merges with the steam extracted from the high-pressure heater (210) to heat the feedwater. The steam flow rate through the primary air reheater (401) is adjusted according to the moisture content of the raw coal, the ambient temperature and the unit load factors to increase the temperature of the primary air by 40-60°C. The heated primary air enters the pulverizing system (101) to dry the lignite, ensuring the drying output of the boiler pulverizing system. The dried coal powder and primary air are mixed and then enter the furnace of the boiler (100) to burn and release heat to heat the working fluid on the boiler water side. The secondary air, after being heated by the secondary air heater (306) and air preheater (105), also enters the boiler furnace to provide sufficient air for the combustion of coal powder. After absorbing heat, the water in the boiler (100) becomes high-temperature steam. The high-temperature steam enters the high-pressure cylinder (201) of the steam turbine to do work. Then, the exhaust steam from the high-pressure cylinder (201) of the steam turbine is divided into two paths. One path enters the low-temperature reheater (102) and the high-temperature reheater (103) to absorb heat and then enters the intermediate-pressure cylinder of the steam turbine. The other path is provided to the steam turbine for extraction to heat the feedwater. The exhaust steam from the intermediate-pressure cylinder (202) of the steam turbine enters the low-pressure cylinder of the steam turbine. The exhaust steam from the low-pressure cylinder (203) of the steam turbine enters the condenser (204) for condensation. Then, it passes through the condensate pump (205) in sequence. The feedwater is fed through a low-pressure heater (206), a deaerator (207), and then pressurized by a feedwater pump (208) driven by a small steam turbine (209) before entering a high-pressure heater (210), and finally into the boiler (100) to complete the working fluid circulation. In addition, to coordinate the heat utilization on both sides of the boiler and turbine, part of the feedwater passes through the flue gas feedwater heat exchanger regulating valve (310) to the flue gas feedwater heat exchanger (302) to absorb the heat of the flue gas, and then mixes with the feedwater of the high-pressure heater (210) before entering the feedwater inlet of the boiler (100). Part of the condensate passes through the flue gas condensate inlet. The regulating valve (311) of the condensate heat exchanger goes to the flue gas condensate heat exchanger (303) to absorb heat and then collects at the deaerator (207). The baffle (301) of the air preheater bypass system is adjusted to regulate the amount of flue gas entering the air preheater bypass, thereby adjusting the heat absorption of the flue gas feedwater heat exchanger (302) and the flue gas condensate heat exchanger (303). After absorbing heat in the flue gas heat medium water heat exchanger (304), the heat medium water is pressurized by the heat medium water circulation pump (309) and then divided into two paths to enter the primary air heater (305) and the secondary air heater respectively. The device (306) preheats the air; if the outlet temperature of the primary air heater (305) and the secondary air heater (306) differs from the design value by 20°C or more, the flow regulating valve A (307) and the booster pump A (308) are opened, and the flue gas condensate heat exchanger (303) is connected in series with the primary air heater (305) and the secondary air heater (306) to mix the condensate and the heat transfer medium water to increase the outlet temperature of the heat transfer medium water, so as to ensure that the outlet air temperature of the primary air heater (305) and the secondary air heater (306) reaches the set value.

9. The working method according to claim 8, characterized in that: This can enhance the automatic power generation control and regulation performance of the unit, reduce the response time of the automatic power generation control, and increase the regulation rate of the automatic power generation control. Specifically, when the unit receives the automatic power generation control load increase command, the opening of the flow regulating valve E (403) is reduced and the opening of the flow regulating valve D (402) is increased, thereby reducing the flow rate at the regenerating extraction point of the turbine cylinder and increasing the turbine output accordingly. Meanwhile, the extraction steam from the boiler low-temperature reheater (102) to the primary air reheater (401) is increased to compensate for the reduction in the turbine regenerating extraction steam, so that the feedwater outlet temperature of the high-pressure heating and low-pressure heater of the turbine regenerating system reaches the predetermined value. If the unit receives the automatic power generation control load reduction command, the opening of the flow regulating valve E (403) is increased and the opening of the flow regulating valve D (402) is reduced. The heat storage of the primary air reheater (401) is used to heat the primary air, so that the feedwater outlet temperature of the high-pressure heating and low-pressure heater of the turbine regenerating system reaches the predetermined value.

10. The working method according to claim 8, characterized in that: This can increase the unit's climbing ability and improve its primary frequency regulation capability. Specifically, when the grid frequency is lower than the rated value and the turbine speed is lower than the rated speed, the unit needs to quickly increase the load. Therefore, the opening of the flow regulating valve E (403) is reduced and the opening of the flow regulating valve D (402) is increased. As a result, the reheat extraction steam flow of the turbine cylinder is reduced, and the turbine output is increased accordingly. Meanwhile, the extraction steam from the boiler low-temperature reheater (102) to the primary air reheater (401) is increased to compensate for the reduction in the turbine's reheat extraction steam flow. At the same time, the baffle plate (301) of the air preheater bypass system is increased. The opening degree of the flue gas feedwater heat exchanger flow regulating valve (310) and the flue gas condensate heat exchanger flow regulating valve (311) are used to heat the feedwater and condensate by utilizing more flue gas heat from the air preheater bypass flue, thereby reducing the turbine regenerative extraction steam flow and rapidly increasing the turbine output. Increasing the opening degree of the air preheater bypass system baffle (301) will reduce the flue gas flow through the air preheater (105), and lower the primary air temperature and secondary air temperature at the outlet of the air preheater (105). At this time, by reducing or even closing the opening degree of the flow regulating valve B (312), Increase the opening of flow regulating valve C (313) to utilize more heat from the heat medium water in the flue gas heat medium water exchanger (304) to heat the secondary air in the secondary air heater (306), thereby increasing the secondary air temperature at the air preheater inlet. The decrease in primary air temperature is compensated by increasing the opening of flow regulating valve D (402) to increase the steam extraction rate of the boiler low-temperature superheater (102). Increasing its steam extraction rate can increase the rise in primary air temperature in the primary air reheater (401), ensuring that the drying output of the pulverizing system matches the current load. When the grid frequency is higher than the rated value When the turbine speed is higher than the rated speed, the unit needs to reduce the load quickly. Therefore, the opening of the flow regulating valve E (403) is increased and the opening of the flow regulating valve D (402) is decreased, thereby increasing the reheat extraction steam flow of the turbine cylinder and reducing the turbine output accordingly. The extraction steam from the boiler low-temperature reheater (102) to the primary air reheater (401) is reduced to maintain the feedwater temperature of the high-pressure heating and low-pressure heater of the reheat system at the predetermined value. The heat release part corresponding to the reduced extraction steam of the primary air reheater is compensated by the heat storage of the primary air reheater (401).Simultaneously reduce the opening of the air preheater bypass system damper (301), the opening of the flue gas feedwater heat exchanger flow regulating valve (310), and the opening of the flue gas condensate heat exchanger flow regulating valve (311), thereby reducing the use of flue gas heat from the air preheater bypass flue to heat feedwater and condensate, increasing the turbine regenerative extraction steam flow, rapidly reducing turbine output, and reducing the opening of the air preheater bypass system damper (301) leads to an increase in the flue gas flow of the air preheater (105), resulting in a greater increase in the primary air temperature and secondary air temperature at the outlet of the air preheater (105). At this time, by increasing the flow regulating valve B (311), 12) Reduce the opening of the flow regulating valve C (313) to utilize more heat from the heat medium water in the flue gas heat medium water exchanger (304) to heat the primary air in the primary air heater, thereby increasing the primary air temperature at the inlet of the air preheater (105). This ensures that the outlet temperature of the primary air reheater (401) reaches the predetermined value, ensuring that the drying output of the pulverizing system matches the current load. The resulting decrease in the secondary air temperature at the outlet of the secondary air heater (306) is compensated by reducing the opening of the baffle (301) of the air preheater bypass system to increase the increase in secondary air temperature in the air preheater.

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