Power generation device based on flue gas and steam cooperative coupling and heat standby maintenance method

Abstract

The application provides a power generation device based on flue gas and steam cooperative coupling and a heat standby maintaining method. In the device, a flue gas coupling pipeline is arranged between the horizontal flue of each power generator set and the furnace of the remaining power generator sets, a steam coupling pipeline is arranged between the input end of the reheater and the input end of the deaerator of the remaining power generator sets, the output end of the superheater is connected with the input end of the reheater, the output end of the deaerator is connected with the high-pressure bypass main pipeline, the output end of the reheater is connected with the input end of the condenser, and the output end of the condenser is connected with the low-pressure bypass main pipeline. The device can keep the heat standby state of quick start when the power generator set is shut down, and has the advantages of short preparation time, low temperature fluctuation of heating surface, low temperature rise amplitude, small heat stress of start and stop, improved safety margin of start and stop process, and reduced operation risk caused by the constraints of minimum flow and temperature rise rate of the boiler.

Description

Technical Field

[0001] This application relates to the field of power generation equipment technology, specifically to a power generation device based on the coordinated coupling of flue gas and steam and a method for maintaining thermal standby. Background Technology

[0002] In recent years, the power grid load has exhibited a more pronounced peak-valley differentiation, with low electricity demand at night creating stable troughs, while concentrated daytime electricity consumption causes the load to rise rapidly. At the same time, the installed capacity of new energy sources continues to expand, and their output is intermittent and fluctuating, further increasing the pressure on peak shaving. As a crucial support for the power system, coal-fired power units need to participate in peak shaving operations more frequently, while ensuring safe and stable operation, and possess greater output adjustment capabilities and response speeds.

[0003] Currently, most coal-fired power plants achieve peak shaving by operating multiple units simultaneously at reduced loads. This method does not require frequent changes to the unit status and is relatively simple to implement. However, as the proportion of renewable energy continues to increase and the peak shaving requirements for coal-fired power units during off-peak hours become more stringent, significant economic and safety issues arise.

[0004] Once the unit load decreases to a certain level, the boiler and turbine deviate significantly from their design operating conditions, resulting in decreased cycle efficiency, increased coal consumption for power generation, and an accelerated deterioration trend at lower load ranges. Boiler-side combustion stability worsens, flue gas losses and incomplete combustion losses increase, heat exchange conditions at the heating surfaces weaken, and unit thermal efficiency further declines. Turbine-side main steam parameters decline, flow efficiency decreases, and wet steam losses in the low-pressure cylinder increase. Multiple units operating at low loads simultaneously often lead to a significant increase in fuel consumption per unit of electricity, resulting in decreased economic efficiency.

[0005] Meanwhile, the combustion and steam-water system are less stable under low loads, parameter fluctuations are more easily amplified, operational adjustments are more frequent, and control becomes more difficult. To meet the requirements of heating surface cooling and hydrodynamic safety, it is necessary to maintain the necessary minimum flow rate and corresponding operating boundaries. Deep load reduction will reduce the operating margin and increase operational risks. At the same time, long-term operation under adverse conditions may exacerbate equipment wear and tear and affect unit reliability.

[0006] As the trough deepens and lasts longer, the strategy of simultaneously reducing load on multiple units gradually approaches the limits of unit stability and safety, leaving limited room for further load reduction. At this point, even if there is still a demand for peak shaving, simply relying on multiple units operating at low loads together will make it difficult to further expand the depth of peak shaving, thus limiting the capacity for renewable energy consumption and the improvement of system flexibility.

[0007] Therefore, the existing peak-shaving method, which mainly relies on multiple units to reduce load simultaneously, has significant shortcomings in terms of economy, operational safety, and peak-shaving depth. There is an urgent need to seek new peak-shaving methods and technical routes to reduce energy consumption and improve operational reliability while meeting dispatch requirements. Summary of the Invention

[0008] This application addresses the problems existing in the prior art by providing a power generation device based on the coordinated coupling of flue gas and steam. When the generator set is disconnected from the grid, the flue gas coupling pipe, steam coupling pipe, high-pressure bypass, and low-pressure bypass keep the shut-down generator set in a hot standby state that can be quickly started. When the dispatch requires the generator set to start, the start-up preparation time is shortened, the temperature fluctuation of the heated surface metal is reduced, the temperature rise is reduced, and the start-up and shutdown thermal stress is reduced, thereby improving the safety margin during start-up and shutdown and reducing the operational risks caused by the minimum flow rate and temperature rise rate constraints of the once-through boiler.

[0009] To achieve the above objectives, the technical solution adopted in this application is as follows: In a first aspect, embodiments of this application propose a power generation device based on the coordinated coupling of flue gas and steam, including at least two generator sets, a flue gas coupling pipeline, a steam coupling pipeline, and a high-pressure bypass and a low-pressure bypass respectively installed on each generator set. The generator set includes a boiler, a steam turbine, and a main steam circuit assembly. The boiler includes a furnace and a horizontal flue. The main steam circuit assembly includes a superheater, a reheater, a condenser, and a deaerator. Each generator set's horizontal flue is connected to the furnace of the other generator sets via a flue gas coupling pipeline; each generator set's reheater input is connected to the deaerator input of the other generator sets via a steam coupling pipeline; the high-pressure bypass includes a high-pressure bypass main line and a high-pressure regulating branch line, with the high-pressure bypass main line connected between the superheater output and the reheater input, and the high-pressure regulating branch line connected between the deaerator output and the high-pressure bypass main line; the low-pressure bypass includes a low-pressure bypass main line and a low-pressure regulating branch line, with the low-pressure bypass main line connected between the reheater output and the condenser input, and the low-pressure regulating branch line connected between the condenser output and the low-pressure bypass main line.

[0010] In some embodiments, the steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. The main steam circuit assembly also includes a low-pressure heater and a high-pressure heater. The high-temperature side of the low-pressure heater is located between the output end of the low-pressure cylinder and the input end of the condenser, and the low-temperature side of the low-pressure heater is located between the output end of the condenser and the input end of the deaerator. The high-temperature side of the high-pressure heater is located between the output end of the high-pressure cylinder and the input end of the deaerator, and the low-temperature side of the high-pressure heater is located between the output end of the deaerator and the input end of the superheater.

[0011] In some embodiments, the power generation device based on flue gas and steam co-coupling further includes a low-pressure feedwater bypass and a high-pressure feedwater bypass. The low-pressure feedwater bypass is connected between the input and output terminals of the low-temperature side of the low-pressure heater, and the high-pressure feedwater bypass is connected between the input and output terminals of the low-temperature side of the high-pressure heater.

[0012] In some embodiments, the flue gas coupling pipeline includes a coupling flue gas control valve and an auxiliary flue gas header; The coupling flue gas control valve is used to control the on / off state of the flue gas coupling pipeline; The auxiliary flue gas header is used to acquire and transport coupled flue gas when the flue gas coupling pipeline is connected. Coupled flue gas represents the flue gas transported from the horizontal flue of the operating generator set to the furnace of the non-operating generator set.

[0013] In some embodiments, the boiler also includes water-cooled walls and a tail flue, with the water-cooled walls surrounding the lower end of the furnace. The superheaters are respectively arranged in the tail flue, in the water-cooled wall and in the upper part of the furnace; The reheaters are located in the tail flue and the horizontal flue, respectively; The inlet of the flue gas coupling pipeline is located near the reheater inside the horizontal flue.

[0014] In some embodiments, the steam coupling line includes an auxiliary steam header and a coupling steam regulating valve; The coupling steam regulating valve is used to control the on / off state of the steam coupling pipeline, and to regulate the steam in the steam coupling pipeline to obtain coupling steam when the steam coupling pipeline is connected. The coupling steam is characterized by the steam supplied from the input end of the reheater of the operating generator set to the input end of the deaerator of the non-operating generator set.

[0015] In some embodiments, the valve opening of the coupling steam regulating valve is adjusted according to the deviation between the outlet water temperature at the deaerator output end of the generator set and the target temperature range, and the adjusted valve opening is limited to the valve opening range so that the coupling steam can maintain the temperature requirements of the main water-steam circuit under the hot standby state of the generator set.

[0016] Secondly, embodiments of this application propose a thermal standby maintenance method based on the coordinated coupling of flue gas and steam, implemented using a power generation device based on the coordinated coupling of flue gas and steam, comprising: Based on at least two generator sets, at least one operating generator set and at least one hot standby generator set are obtained respectively; At least one first flue gas coupling pipeline is obtained based on at least one operating generator set, at least one hot standby generator set and flue gas coupling pipeline. Each hot standby generator set corresponds to one first flue gas coupling pipeline. The first flue gas coupling pipeline represents the flue gas coupling pipeline connected between the first horizontal flue and the corresponding second furnace. The first horizontal flue represents the horizontal flue of the operating generator set, and the second furnace represents the furnace of the hot standby generator set. At least one first steam coupling pipeline is obtained based on at least one operating generator set, at least one hot standby generator set and a steam coupling pipeline. Each hot standby generator set corresponds to one first steam coupling pipeline. The first steam coupling pipeline is characterized by a steam coupling pipeline connected between the input end of the first reheater and the input end of the second deaerator. The first reheater is characterized by the reheater of the operating generator set, and the second deaerator is characterized by the deaerator of the hot standby generator set. A second high-pressure bypass and a second low-pressure bypass are obtained according to at least one hot standby generator set. The second high-pressure bypass represents the high-pressure bypass corresponding to the hot standby generator set, and the second low-pressure bypass represents the low-pressure bypass corresponding to the hot standby generator set. The second high-pressure bypass includes a second high-pressure bypass main line and a second high-pressure regulating branch line. The second high-pressure bypass main line is connected between the output end of the second superheater and the input end of the second reheater. The second superheater represents the superheater of the hot standby generator set, and the second reheater represents the reheater of the hot standby generator set. The second high-pressure regulating branch line is connected between the output end of the second deaerator and the second high-pressure bypass main line. The second low-pressure bypass includes a second low-pressure bypass main line and a second low-pressure regulating branch line. The second low-pressure bypass main line is connected between the output end of the second reheater and the input end of the second condenser. The second condenser represents the condenser of the hot standby generator set. The low-pressure regulating branch line is connected between the output end of the second condenser and the second low-pressure bypass main line. The corresponding coupling flue gas is obtained according to each first flue gas coupling pipeline and the corresponding operating generator set; The corresponding coupling steam is obtained according to each first steam coupling pipeline and the corresponding hot standby generator set; The coupled flue gas is delivered to each of the second furnaces through the first flue gas coupling pipeline; The coupled flue gas is sequentially transported from the second furnace to the second horizontal flue and the second tail flue. The second horizontal flue represents the horizontal flue of the hot standby generator set, and the second tail flue represents the tail flue of the hot standby generator set. The coupling steam is delivered to each of the second deaerators via the first steam coupling pipeline; The main hot standby steam-water circuit is obtained by coupling steam, hot standby generator set, second high-pressure bypass and second low-pressure bypass. The transmission path of coupling steam in the main hot standby steam-water circuit includes sequentially passing through the second deaerator, the second superheater, the second high-pressure bypass main line, the second reheater, the second low-pressure bypass main line, the second condenser and the second deaerator.

[0017] In some embodiments, the corresponding coupled flue gas is obtained according to each first flue gas coupling pipeline and the corresponding operating generator set, including: The extracted flue gas is obtained from the first horizontal flue of the operating generator set, which is corresponding to the first flue gas coupling pipeline; When the flue gas temperature fluctuation within the statistical window does not exceed the preset temperature: The extracted flue gas is pretreated to obtain coupled flue gas.

[0018] In some of these embodiments, the time range of the statistical window includes a continuous duration of 5 minutes to a continuous duration of 30 minutes.

[0019] In some embodiments, corresponding coupling steam is obtained according to each first steam coupling pipeline and the corresponding hot standby generator set, including: Adjust the valve opening of the first coupled steam regulating valve, which represents the coupled steam regulating valve on the first steam coupling pipeline; Obtain the outlet water temperature at the output end of the second deaerator in the hot standby generator set, which corresponds to the first steam coupling pipeline; Compare the outlet water temperature with the target temperature range; Adjust the valve opening of the first coupling steam regulating valve according to the comparison results. The first coupling steam regulating valve represents the coupling steam regulating valve on the first steam coupling pipeline. When the outlet water temperature is within the target temperature range: Coupled steam is obtained based on the adjusted valve opening.

[0020] Compared with the prior art, this application has the following advantages: When the generator set in this application is disconnected from the grid for power generation, it is kept in a hot standby state through flue gas coupling pipe, steam coupling pipe, high-pressure bypass and low-pressure bypass. In the hot standby state, the generator set is kept in a state that can be started quickly. When the dispatch requires the generator set to start, the start-up preparation time is shortened, the temperature fluctuation of the heated surface metal is reduced, the temperature rise is reduced and the start-up and shutdown thermal stress is reduced, the safety margin during start-up and shutdown is improved, and the operational risks caused by the minimum flow rate and temperature rise rate constraints of the once-through boiler are reduced. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the power generation device based on the coordinated coupling of flue gas and steam in the embodiments of this application.

[0022] The reference numerals in the attached drawings are as follows: 1000, operating generator set; 1100, first boiler; 1110, first furnace; 1120, first horizontal flue; 1130, first tail flue; 1140, first water-cooled wall; 1200, first steam turbine; 1201, first high-pressure cylinder; 1202, first intermediate-pressure cylinder; 1203, first low-pressure cylinder; 1204, first generator; 1300, first main steam circuit assembly; 1301, first superheater; 13011, first interface; 13012, second interface; 13013, third interface; 13014, fourth interface; 1302, first reheater; 1303, first condenser; 1304, first condensate pump; 1405, first low-pressure heater; 1306, first deaerator; 1307, first feedwater pump; 1308, first high-pressure heater; 1309, first pipeline; 2000, Hot standby generator set; 2100, Second boiler; 2110, Second furnace; 2120, Second horizontal flue; 2130, Second tail flue; 2140, Second water-cooled wall; 2200, Second steam turbine; 2201, Second high-pressure cylinder; 2202, Second intermediate-pressure cylinder; 2203, Second low-pressure cylinder; 2204, Second generator; 2300, Second main steam circuit assembly; 2301, Second superheater; 23011, Fifth connection. 23012, Sixth Interface; 23013, Seventh Interface; 23014, Eighth Interface; 2302, Second Reheater; 2303, Second Condenser; 2304, Second Condensate Pump; 2305, Second Low-Pressure Heater; 2306, Second Deaerator; 2307, Second Feedwater Pump; 2308, Second High-Pressure Heater; 2309, Second Pipeline; 23091, First Valve; 2310, Third Pipeline; 23101, Second Valve; 3000, First flue gas coupling pipeline; 3100, First auxiliary flue gas header; 3200, First coupling flue gas control valve; 4000, Second high-voltage bypass; 4100, Second high-voltage bypass main line; 4110, Second high-voltage bypass control valve; 4200, Second high-voltage regulating branch; 4210, Second high-voltage bypass regulating valve; 5000, First steam coupling pipeline; 5100, First auxiliary steam header; 5200, First coupling steam regulating valve; 6000, Second low-pressure bypass; 6100, Second low-pressure bypass main line; 6110, Second low-pressure bypass control valve; 6200, Second low-pressure regulating branch; 6210, Second low-pressure bypass regulating valve; 7000, Second low-pressure water supply bypass; 7100, Second low-pressure water supply control valve; 8000, Second high-pressure water supply bypass; 8100, Second high-pressure water supply control valve. Detailed Implementation

[0023] To clearly illustrate the technical features of this solution, the implementation methods of this application will be described in detail below with reference to the accompanying drawings and embodiments. This will allow for a full understanding and implementation of how this application uses technical means to solve technical problems and achieve corresponding technical effects. The embodiments of this application and the various features within them can be combined with each other without conflict, and the resulting technical solutions are all within the protection scope of this application.

[0024] In a first aspect, embodiments of this application propose a power generation device based on the coordinated coupling of flue gas and steam, comprising at least two generator sets, a flue gas coupling pipeline, a steam coupling pipeline, and a high-pressure bypass and a low-pressure bypass respectively installed on each generator set. Each generator set includes a boiler, a steam turbine, and a main steam circuit assembly. The boiler includes a furnace and a horizontal flue, with the upper end of the furnace connected to the horizontal flue. The steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. The output shafts of the high-pressure cylinder, the intermediate-pressure cylinder, and the low-pressure cylinder are coaxial with the input shaft of the generator. The main steam circuit assembly includes a superheater, reheater, condenser, and deaerator. The input end of the high-pressure cylinder is connected to the output end of the superheater; the output end of the high-pressure cylinder is connected to the input end of the reheater; the output end of the reheater is connected to the input end of the intermediate-pressure cylinder; the output end of the intermediate-pressure cylinder is connected to the input end of the low-pressure cylinder; the output end of the low-pressure cylinder is connected to the input end of the condenser; the input end of the deaerator is connected to the output ends of both the intermediate-pressure cylinder and the condenser; and the output end of the deaerator is connected to the input end of the superheater. During generator unit operation, fuel is in the boiler... Internal combustion heats both the superheater and reheater separately. The superheated steam, after being heated in the superheater, is transferred to the high-pressure cylinder, driving its output shaft to rotate. This converts the internal energy of the superheated steam into the mechanical energy of the high-pressure cylinder's output shaft, which in turn drives the generator's input shaft to generate electricity. The steam output from the high-pressure cylinder is then input into the reheater for reheating, forming reheated steam. This reheated steam is then transferred to the intermediate-pressure cylinder, driving its output shaft to rotate. This converts the internal energy of the reheated steam into the mechanical energy of the intermediate-pressure cylinder's output shaft, which in turn drives the generator's input shaft to generate electricity. The input shaft of the generator rotates to generate electricity; a portion of the steam output from the intermediate-pressure cylinder is transferred to the low-pressure cylinder, driving the output shaft of the low-pressure cylinder to rotate, converting the internal energy of the steam into the mechanical energy of the low-pressure cylinder output shaft, which in turn drives the input shaft of the generator to rotate to generate electricity; a portion of the steam output from the intermediate-pressure cylinder is also input to the deaerator to heat the deaerator and maintain its pressure; the steam output from the low-pressure cylinder condenses into liquid water in the condenser and is transferred to the deaerator for deoxygenation; the deoxygenated liquid water then re-enters the superheater, completing one cycle.

[0025] The boiler also includes water-cooled walls and a tail flue, with the water-cooled walls surrounding the lower end of the furnace. The superheaters are respectively arranged in the tail flue, the water-cooled wall and the upper end of the furnace. The deoxygenated liquid water enters the superheater from the tail flue, and is heated in sequence through the tail flue and the water-cooled wall before returning to the tail flue for heating again. After being heated again at the upper end of the furnace, it is output from the superheater.

[0026] Each generator set's horizontal flue is connected to the furnace of the other generator sets via a flue gas coupling pipeline; each generator set's reheater input is connected to the deaerator input of the other generator sets via a steam coupling pipeline; the high-pressure bypass includes a high-pressure bypass main line and a high-pressure regulating branch line, with the high-pressure bypass main line connected between the superheater output and the reheater input, and the high-pressure regulating branch line connected between the deaerator output and the high-pressure bypass main line; the low-pressure bypass includes a low-pressure bypass main line and a low-pressure regulating branch line, with the low-pressure bypass main line connected between the reheater output and the condenser input, and the low-pressure regulating branch line connected between the condenser output and the low-pressure bypass main line.

[0027] During periods of high daytime load and significant fluctuations in renewable energy output, all or multiple generator units in the power generation facility operate in parallel to share the system load of the electricity consumption area. When entering a nighttime off-peak period with prolonged peak-shaving demand, upon receiving a deep peak-shaving command or detecting a drop in system load below a preset threshold, the power plant, based on predictions of the off-peak duration, will disconnect at least one generator unit from the grid and place it into hot standby mode if the predicted off-peak duration is not less than a preset critical shutdown time. Maintaining a corresponding number of generator units within a relatively stable load range, while keeping all generator units in a low-load range simultaneously, significantly improves operating efficiency. The following day, when load increases or renewable energy output decreases requiring rapid restoration of power plant output, upon receiving a start-up command or detecting a rebound in system load to a level not lower than a preset threshold, the power plant organizes a rapid start-up process for the generator units in hot standby mode. This allows the generator units in hot standby mode to complete start-up preparation and grid connection within a short time, enabling the power plant to resume the sharing of system load with all or multiple generator units. To avoid a single generator unit bearing the burden of start-stop cycles for an extended period, power plants, based on the principle of balanced start-stop frequency or according to a preset rotation cycle, change the operating status of generator units in subsequent operating cycles. This means that generator units alternate between operating status and hot standby status, ensuring that at least two generator units in the power generation unit take turns undertaking operating and hot standby tasks, thereby forming a sustainable rotation start-stop operation mode.

[0028] The number of generator units in the power generation unit is determined based on the electricity consumption situation in the power consumption area. Taking a power generation unit based on flue gas and steam synergistic coupling, which includes two generator units, as an example: During the daytime, when the load is high and the output of new energy sources fluctuates significantly, the two generator units operate in parallel to share the system load of the power consumption area. When entering the nighttime off-peak period and the peak-shaving demand lasts for a long time, after receiving a deep peak-shaving command from the dispatch center or detecting that the system load has dropped below a preset threshold, the power plant, based on the prediction of the duration of the off-peak period, will disconnect one of the generator units from the grid and put it into hot standby mode if the predicted duration of the off-peak period is not less than the preset critical shutdown time. The next day, when the load rises or the output of new energy sources decreases and a rapid recovery of the power plant's output is required, the power plant, after receiving a start-up command or detecting that the system load has rebounded to a level not lower than the preset threshold, will organize a rapid start-up process for the generator unit in hot standby mode, enabling the generator unit in hot standby mode to complete start-up preparation and achieve grid connection in a short time, and the power plant will resume the two generator units sharing the system load. To avoid a single generator unit bearing the burden of start-stop cycles for an extended period, the power plant changes the operating status of the generator units in subsequent operating cycles based on the principle of balanced start-stop frequency or according to a preset rotation cycle. That is, the generator units alternate between operating status and hot standby status, so that the two generator units in the power generation unit take turns to undertake operating and hot standby tasks, thereby forming a sustainable two-shift rotation start-stop operation mode.

[0029] To ensure normal power supply, at least one of the two generator sets is in operation. The operation status of the two generator sets includes a first operation status and a second operation status: the first operation status indicates that both generator sets are in operation; the second operation status indicates that one generator set is in operation and the other generator set is in hot standby status.

[0030] In the second operating state, the two generator sets include an operating generator set 1000 and a hot standby generator set 2000. The operating generator set 1000 represents the generator set in the operating state, and the hot standby generator set 2000 represents the generator set in the hot standby state. That is, one generator set is in the operating state and the other generator set is in the hot standby state.

[0031] To ensure that the standby generator set 2000 can start up quickly when needed, a flue gas coupling pipeline is connected between the horizontal flue of the operating generator set 1000 and the furnace of the standby generator set 2000. This allows coupling flue gas to be obtained from the horizontal flue of the operating generator set 1000 and transferred to the furnace of the standby generator set 2000. The coupling flue gas flows sequentially from the furnace of the standby generator set 2000 along the horizontal flue and the tail flue of the standby generator set 2000, introducing the heat from the flue gas in the boiler of the operating generator set 1000 into the furnace of the boiler of the standby generator set 2000. This heat is used to preheat the heating surfaces of the furnace of the standby generator set 2000, the horizontal flue, and the tail flue. The coupling flue gas keeps the furnace, horizontal flue, and tail flue of the standby generator set 2000 in a hot state, thus achieving the flue gas insulation and preheating effect of the standby generator set 2000.

[0032] Simultaneously, a steam coupling pipeline is connected between the input end of the reheater of the operating generator set 1000 and the input end of the deaerator of the hot standby generator set 2000. This allows coupling steam to be obtained from the input end of the reheater of the operating generator set 1000 and transmitted to the deaerator of the hot standby generator set 2000. This increases the base temperature of the feedwater of the hot standby generator set 2000 and improves deaeration conditions, reducing the temperature drop during the shutdown of the hot standby generator set 2000. It also heats and maintains the temperature of the deaerator of the hot standby generator set 2000, providing feedwater conditions closer to the start-up requirements for the boiler of the hot standby generator set 2000. This creates a deaeration heating maintenance effect for the hot standby generator set 2000 and is used in conjunction with the high-pressure bypass and low-pressure circuits in the hot standby generator set 2000 to ensure safe and controllable start-up and shutdown processes.

[0033] The system connects the high-pressure bypass and low-pressure bypass of the standby generator set 2000, respectively. A controllable steam flow path is established between the output of the superheater and the input of the reheater in the standby generator set 2000 via the high-pressure bypass main line. The steam temperature in the high-pressure bypass main line is regulated by the high-pressure regulating branch. Similarly, a controllable steam venting path is established between the output of the reheater and the input of the condenser in the standby generator set 2000 via the low-pressure bypass main line. The steam temperature in the low-pressure bypass main line is also regulated by the low-pressure regulating branch. The high-pressure and low-pressure regulating branches control the steam parameters entering the downstream pipe section. To meet the safety requirements of the 2000 hot standby generator set, it maintains unobstructed steam passages on the boiler side and controls the rate of temperature rise when the high-pressure, intermediate-pressure, and low-pressure cylinders are not engaged or the load is limited. In addition, when the low-pressure cylinder is not engaged or the load changes abruptly, it quickly establishes a controllable venting channel, stabilizes the reheat steam pressure, and protects the turbine and boiler heating surfaces of the 2000 hot standby generator set. This reduces the risk of pressure and temperature changes during the start-up and shutdown phases of the 2000 hot standby generator set, thus forming a bypass stabilization effect for the 2000 hot standby generator set. At the same time, it maintains the necessary thermal conditions during generator set shutdown and quickly restores output when needed.

[0034] In hot standby mode, the flue insulation and preheating effect is used to continuously maintain the thermal foundation of the boiler furnace, horizontal flue, and tail flue of the hot standby generator unit 2000. The deaerator heating maintenance effect is used to continuously maintain the hot state of the deaerator of the hot standby generator unit 2000 and support the feedwater temperature foundation of the hot standby generator unit 2000. The bypass stabilization effect is used to ensure that the steam channel is controllable during the start-up and shutdown phases of the hot standby generator unit 2000. Through the above synergistic maintenance, the shut-down generator unit can maintain a rapid start-up state in hot standby mode, and when the dispatch requires start-up, the start-up preparation time is shortened, the temperature fluctuation of the heated surface metal is reduced, the temperature rise is reduced, and the start-up and shutdown thermal stress is reduced, thereby increasing the safety margin during start-up and shutdown and reducing the operational risks caused by the minimum flow rate and temperature rise rate constraints of the once-through boiler.

[0035] In some embodiments, the main steam circuit assembly further includes a low-pressure heater and a high-pressure heater. The high-temperature side of the low-pressure heater is located between the output end of the low-pressure cylinder and the input end of the condenser, and the low-temperature side of the low-pressure heater is located between the output end of the condenser and the input end of the deaerator. The low-pressure heater uses the low-temperature extraction steam from the low-pressure cylinder to heat the condensate output from the condenser, reducing the heating requirement of the condensate when it enters the deaerator. The high-temperature side of the high-pressure heater is located between the output end of the high-pressure cylinder and the input end of the deaerator, and the low-temperature side of the high-pressure heater is located between the output end of the deaerator and the input end of the superheater. The high-pressure heater uses the high-temperature extraction steam from the high-pressure cylinder to heat the feedwater before it enters the boiler, significantly increasing the feedwater temperature.

[0036] In some embodiments, the power generation device based on flue gas and steam co-coupling further includes a low-pressure feedwater bypass and a high-pressure feedwater bypass. The low-pressure feedwater bypass is connected between the input and output terminals of the low-temperature side of the low-pressure heater, and the high-pressure feedwater bypass is connected between the input and output terminals of the low-temperature side of the high-pressure heater. In hot standby mode, the low-pressure feedwater bypass and the high-pressure feedwater bypass are connected respectively. The low-pressure feedwater bypass is used to connect the output end of the condenser to the input end of the deaerator. A low-pressure feedwater control valve is installed on the low-pressure feedwater bypass to regulate the flow rate of the low-pressure feedwater bypass and to isolate and protect the low-pressure heater from the low-pressure heater. This ensures continuous flow of the feedwater system during the commissioning and decommissioning of the low-pressure heater and prevents the low-pressure heater from overheating or water hammer. The high-pressure feedwater bypass is used to connect the output end of the deaerator to the input end of the superheater. A high-pressure feedwater control valve is installed on the high-pressure feedwater bypass to regulate the flow rate of the high-pressure feedwater bypass and to isolate and protect the high-pressure heater from the high-pressure heater. This ensures continuous water supply of the feedwater system during the commissioning and decommissioning of the high-pressure heater and reduces the risk of thermal shock. In the feedwater circuit of the 2000 hot standby generator set, supported by the deaeration heating maintenance effect, the condensate output from the condenser enters the deaerator through the low-pressure feedwater bypass. After being heated and deaerated in the deaerator, it is transported to the superheater through the high-pressure feedwater bypass, then to the reheater through the high-pressure bypass, and finally to the input end of the condenser through the low-pressure bypass, completing a continuous flow cycle, thereby forming the feedwater hot standby state of the 2000 hot standby generator set.

[0037] In some embodiments, the flue gas coupling pipeline includes a coupling flue gas control valve and an auxiliary flue gas header; The coupling flue gas control valve is used to control the on / off state of the flue gas coupling pipeline; The auxiliary flue gas header is used to acquire and transport coupled flue gas when the flue gas coupling pipeline is connected. Coupled flue gas represents the flue gas transported from the horizontal flue of the operating generator set to the furnace of the non-operating generator set. The operating generator set is the operating generator set 1000, and the non-operating generator set is the generator set in hot standby mode. Specifically, when the coupled flue gas control valve is opened, the flue gas coupling pipeline is connected, and the auxiliary flue gas header draws flue gas from the horizontal flue of the operating generator set 1000. Isolation, backflow prevention, and pressurization measures are taken for the drawn flue gas to achieve flue gas on / off control, backflow suppression, and stable transport. At the same time, the flue gas extraction rate is controlled to keep it within an appropriate range to avoid excessive extraction from adversely affecting the heat exchange conditions of the furnace, horizontal flue, and tail flue of the boiler of the operating generator set 1000. The flue gas after stable transport forms coupled flue gas and is transported to the furnace of the hot standby generator set 2000.

[0038] In some embodiments, the reheaters are respectively arranged in the tail flue and the horizontal flue; the steam output from the high-pressure cylinder enters the reheater from the tail flue, and is reheated in the tail flue and the horizontal flue before being output from the reheater.

[0039] The inlet of the flue gas coupling pipeline is located near the reheater inside the horizontal flue, and the outlet of the flue gas coupling pipeline is located at the upper end of the furnace of the corresponding generator set.

[0040] In some embodiments, the steam coupling line includes an auxiliary steam header and a coupling steam regulating valve; The coupling steam regulating valve is used to control the on / off state of the steam coupling pipeline, and to regulate the steam within the steam coupling pipeline to obtain coupling steam when the steam coupling pipeline is connected. Coupled steam represents the steam supplied from the inlet of the reheater of the operating generator unit to the inlet of the deaerator of the non-operating generator unit. The coupling steam flows into the auxiliary steam header, making the auxiliary steam header a relatively stable steam storage and distribution node in terms of pressure and flow, and buffering steam fluctuations; thus forming coupling steam that can be used for stable supply.

[0041] Secondly, embodiments of this application propose a thermal standby maintenance method based on the coordinated coupling of flue gas and steam, implemented using a power generation device based on the coordinated coupling of flue gas and steam, comprising: At least one operating generator set 1000 and at least one hot standby generator set 2000 are obtained from at least two generator sets respectively; the operating generator set 1000 includes a first boiler 1100, a first steam turbine 1200 and a first main steam circuit assembly 1300, the first boiler 1100 includes a first furnace 1110, a first horizontal flue 1120, a first tail flue 1130 and a first water-cooled wall 1140, the first steam turbine 1200 includes a first high-pressure cylinder 1201, a first intermediate-pressure cylinder 1202, a first low-pressure cylinder 1203 and a first generator 1204, and the first main steam circuit assembly 1300 includes a first superheater 1301, a first reheater 1302, a first condenser 1303 and a first deaerator 1306. In the operating generator set 1000, the path of condensate entering the first superheater 1301 for heating and then inputting superheated steam is as follows: Condensate first enters the portion of the first superheater 1301 located in the first tail flue 1130 for preheating, then sequentially enters the portion located in the first water-cooled wall 1140 via the first interface 13011 and the second interface 13012 for heating, then sequentially returns to the portion located in the first tail flue 1130 via the third interface 13013 and the fourth interface 13014, and finally exits through the portion located at the outlet of the first furnace 1110 to form superheated steam. To ensure the efficiency of condensate or feedwater in the operating generator set 1000, a first condensate pump 1304 is connected between the output end of the first condenser 1303 and the input end of the first deaerator 1306, and a first feedwater pump 1307 is connected between the output end of the first deaerator 1306 and the input end of the first superheater 1301.

[0042] The hot standby generator set 2000 includes a second boiler 2100, a second steam turbine 2200, and a second main steam circuit assembly 2300. The second boiler 2100 includes a second furnace 2110, a second horizontal flue 2120, a second tail flue 2130, and a second water-cooled wall 2140. The second steam turbine 2200 includes a second high-pressure cylinder 2201, a second intermediate-pressure cylinder 2202, a second low-pressure cylinder 2203, and a second generator 2204. The second main steam circuit assembly 2300 includes a second superheater 2301, a second reheater 2302, a second condenser 2303, and a second deaerator 2306. In the hot standby generator set 2000, the condensate flows through the second superheater 2301 in a similar path: first, it enters the portion of the second superheater 2301 located in the second tail flue 2130; then, it sequentially enters the portion located in the second water-cooled wall 2140 via the fifth port 23011 and the sixth port 23012; subsequently, it returns to the portion located in the second tail flue 2130 via the seventh port 23013 and the eighth port 23014; finally, it is output through the portion located at the outlet of the second furnace 2110. To ensure the efficiency of the condensate or feedwater in the hot standby generator set 2000, a second condensate pump 2304 is connected between the output end of the second condenser 2303 and the input end of the second deaerator 2306, and a second feedwater pump 2307 is connected between the output end of the second deaerator 2306 and the input end of the second superheater 2301.

[0043] At least one first flue gas coupling pipeline 3000 is obtained based on at least one operating generator set 1000, at least one hot standby generator set 2000 and a flue gas coupling pipeline. Each hot standby generator set 2000 corresponds to one first flue gas coupling pipeline 3000. The first flue gas coupling pipeline 3000 represents the flue gas coupling pipeline connected between the first horizontal flue 1120 and the corresponding second furnace 2110. The first horizontal flue 1120 represents the horizontal flue of the operating generator set 1000, and the second furnace 2110 represents the furnace of the hot standby generator set 2000. At least one first steam coupling line 5000 is obtained based on at least one operating generator set 1000, at least one hot standby generator set 2000 and a steam coupling line. Each hot standby generator set 2000 corresponds to one first steam coupling line 5000. The first steam coupling line 5000 represents a steam coupling line connected between the input end of the first reheater 1302 and the input end of the second deaerator 2306. The first reheater 1302 represents the reheater of the operating generator set 1000, and the second deaerator 2306 represents the deaerator of the hot standby generator set 2000. A second high-voltage bypass 4000 and a second low-voltage bypass 6000 are obtained according to at least one hot standby generator set 2000, wherein the second high-voltage bypass 4000 represents a high-voltage bypass corresponding to the hot standby generator set 2000, and the second low-voltage bypass 6000 represents a low-voltage bypass corresponding to the hot standby generator set 2000.

[0044] The second high-pressure bypass 4000 includes a second high-pressure bypass main line 4100 and a second high-pressure regulating branch line 4200. The second high-pressure bypass main line 4100 is connected between the output terminal of the second superheater 2301 and the input terminal of the second reheater 2302. The second superheater 2301 represents the superheater of the thermal standby generator set 2000, and the second reheater 2302 represents the reheater of the thermal standby generator set 2000. Optionally, the second high-pressure bypass main line 4100 is connected between the second pipe 2309 and the input terminal of the second reheater 2302. The pipeline connecting the output of the second superheater 2301 and the input of the second high-pressure cylinder 2201 is characterized. A first valve 23091 is installed on the second pipeline 2309, which is located between the input of the second high-pressure bypass main line 4100 and the input of the second high-pressure cylinder 2201. When the first valve 23091 is closed, i.e., in hot standby mode, the generator set's superheater does not supply superheated steam to the high-pressure cylinder. The second high-pressure regulating branch 4200 is connected between the output of the second deaerator 2306 and the second high-pressure bypass main line 4100. A second high-pressure bypass control valve 4110 is installed on the second high-pressure bypass main line 4100, and a second high-pressure bypass regulating valve 4210 is installed on the second high-pressure regulating branch 4200. The flow rate in the second high-pressure bypass main line 4100 is controlled by the second high-pressure bypass control valve 4110, and the temperature in the second high-pressure bypass main line 4100 is controlled by the second high-pressure bypass regulating valve 4210.

[0045] The second low-pressure bypass 6000 includes a second low-pressure bypass main line 6100 and a second low-pressure regulating branch line 6200. The second low-pressure bypass main line 6100 is connected between the output end of the second reheater 2302 and the input end of the second condenser 2303. The second condenser 2303 represents the condenser of the hot standby generator set 2000. Optionally, the second low-pressure bypass main line 6100 is connected between a third pipeline 2310 and the input end of the second condenser 2303. The third pipeline 2310 represents the pipeline connecting the output end of the second reheater 2302 and the input end of the second intermediate-pressure cylinder 2202. A second valve 23101 is installed on the third pipeline 2310. The second valve 23101 is located on the second low-pressure bypass main line. Between the input end of 6100 and the input end of the second intermediate pressure cylinder 2202, the second valve 23101 is closed. That is, in hot standby mode, the reheater of the generator set does not supply reheat steam to the intermediate pressure cylinder. The second low-pressure regulating branch 6200 is connected between the output end of the second condenser 2303 and the second low-pressure bypass main line 6100. A second low-pressure bypass control valve 6110 is installed on the second low-pressure bypass main line 6100, and a second low-pressure bypass regulating valve 6210 is installed on the second low-pressure regulating branch 6200. The flow rate in the second low-pressure bypass main line 6100 is controlled by the second low-pressure bypass control valve 6110, and the temperature in the second low-pressure bypass main line 6100 is controlled by the second low-pressure bypass regulating valve 6210.

[0046] Each first flue gas coupling pipeline 3000 and its corresponding operating generator set 1000 obtain the corresponding coupling flue gas. The first flue gas coupling pipeline 3000 includes a first coupling flue gas control valve 3200 and a first auxiliary flue gas header 3100. When the first coupling flue gas control valve 3200 is opened, the first auxiliary flue gas header 3100 obtains and delivers coupling flue gas from the operating generator set 1000. The first auxiliary flue gas header 3100 extracts flue gas from the first horizontal flue 1120 and takes measures to isolate, prevent backflow, and pressurize the extracted flue gas to achieve flue gas on / off control, backflow suppression, and stable delivery. At the same time, the amount of flue gas extracted is controlled to keep it within an appropriate range, so as to avoid excessive extraction from adversely affecting the heat exchange conditions of the first furnace 1110, the first horizontal flue 1120, the first tail flue 1130, and the first water-cooled wall 1140. Each first steam coupling pipeline 5000 and its corresponding hot standby generator set 2000 obtains corresponding coupling steam. Optionally, the first steam coupling pipeline 5000 is connected between the first pipeline 1309 and the input end of the second deaerator 2306. The first pipeline 1309 is characterized by connecting the output end of the first high-pressure cylinder 1201 and the input end of the first reheater 1302. The first steam coupling pipeline 5000 includes a first auxiliary steam header 5100 and a first coupling steam regulating valve 5200. When the first coupling steam regulating valve 5200 is opened, the coupling steam flows into the first auxiliary steam header 5100, making the first auxiliary steam header 5100 a steam storage and distribution node with relatively stable pressure and flow, and buffering steam fluctuations to form coupling steam that can be used for stable supply.

[0047] The coupled flue gas is delivered to each of the second furnace chambers 2110 through the first flue gas coupling pipeline 3000. The flue gas after stable delivery forms coupled flue gas and is delivered into the second furnace chamber 2110. The coupled flue gas is sequentially conveyed from the second furnace 2110 to the second horizontal flue 2120 and the second tail flue 2130. The second horizontal flue 2120 represents the horizontal flue of the hot standby generator set 2000, and the second tail flue 2130 represents the tail flue of the hot standby generator set 2000. The coupling steam is delivered to each of the second deaerators 2306 through the first steam coupling pipeline 5000, and the first auxiliary steam header 5100 delivers coupling steam to the input end of the second deaerator 2306. The main hot standby steam-water circuit is obtained by coupling steam, hot standby generator set 2000, second high-pressure bypass 4000 and second low-pressure bypass 6000. The transmission path of coupling steam in the main hot standby steam-water circuit includes sequentially passing through second deaerator 2306, second superheater 2301, second high-pressure bypass main line 4100, second reheater 2302, second low-pressure bypass main line 6100, second condenser 2303 and second deaerator 2306.

[0048] Optionally, the first main steam circuit assembly 1300 further includes a first low-pressure heater 1305 and a first high-pressure heater 1308, and the second main steam circuit assembly 2300 further includes a second low-pressure heater 2305 and a second high-pressure heater 2308.

[0049] The hot standby maintenance method based on the coordinated coupling of flue gas and steam further includes connecting the second low-pressure feedwater bypass 7000 and the second high-pressure feedwater bypass 8000 respectively, and ensuring the normal operation of the first low-pressure heater 1305 and the first high-pressure heater 1308 to guarantee the connection of the feedwater channel for the out-of-service generator unit in hot standby mode. Optionally, a second low-pressure feedwater control valve 7100 is provided on the second low-pressure feedwater bypass 7000, and the second low-pressure feedwater bypass 7000 is opened and closed by controlling the second low-pressure feedwater control valve 7100. A second high-pressure feedwater control valve 8100 is provided on the second high-pressure feedwater bypass 8000, and the second high-pressure feedwater bypass 8000 is opened and closed by controlling the second high-pressure feedwater control valve 8100.

[0050] In some embodiments, the corresponding coupled flue gas is obtained based on each first flue gas coupling pipe 3000 and the corresponding operating generator set 1000, including: The extracted flue gas is obtained from the first horizontal flue 1120 of the operating generator set 1000, which corresponds to the first flue gas coupling pipeline 3000. When the flue gas temperature fluctuation within the statistical window is not greater than the preset temperature, the extracted flue gas is pre-treated to obtain the coupling flue gas. Optionally, the preset temperature is 30℃.

[0051] In some embodiments, the time range of the statistical window includes a continuous duration of 5 minutes to 30 minutes, and optionally, the statistical window is a continuous duration of 10 minutes.

[0052] In some embodiments, corresponding coupling steam is obtained based on each first steam coupling pipeline 5000 and the corresponding hot standby generator set 2000, including: Adjust the valve opening of the first coupling steam regulating valve 5200, which represents the coupling steam regulating valve on the first steam coupling pipeline 5000; Obtain the outlet water temperature of the second deaerator 2306 in the hot standby generator set 2000, which corresponds to the first steam coupling pipeline 5000; Compare the outlet water temperature with the target temperature range. The target temperature range is determined based on the heat maintenance requirements of the boiler of the 2000 hot standby generator set in the hot standby state, so that the feedwater temperature of the boiler of the generator set entering the hot standby state is within the target range that can maintain the metal temperature of the boiler heating surface and the temperature of the water working medium inside the boiler. Adjust the valve opening of the first coupling steam regulating valve 5200 based on the comparison results; When the outlet water temperature is below the lower limit of the target temperature range, the opening of the first coupling steam regulating valve 5200 is gradually increased to increase the steam supply of the first steam coupling pipeline 5000. When the opening of the first coupling steam regulating valve 5200 increases and the rate of temperature rise of the outlet water decreases and tends to stabilize, it is determined that the outlet water temperature has reached the achievable stable value of the current generator set under the current operating conditions, and the opening of the first coupling steam regulating valve 5200 is stopped from being increased further. When the outlet water temperature is within the target temperature range, the opening of the first coupling steam regulating valve 5200 is maintained to keep the outlet water temperature stable within the target temperature range. When the outlet water temperature is above the upper limit of the target temperature range, the opening of the first coupling steam regulating valve 5200 is decreased to reduce the steam supply. After adjusting the opening of the first coupling steam regulating valve 5200, the outlet water temperature is maintained within the target temperature range, thereby providing a stable heat source for the feedwater side of the hot standby generator set 2000. Simultaneously, when the outlet water temperature is within the target temperature range: Coupled steam is obtained based on the adjusted valve opening.

[0053] Based on the comparison results, adjust the valve opening of the first coupled steam regulating valve 5200, including: Obtain the initial valve opening; The outlet water temperature of the second deaerator 2306 is obtained based on the initial valve opening. When the outlet water temperature is within the target temperature range: the adjusted valve opening is obtained based on the initial valve opening; When the outlet water temperature is outside the target temperature range: The valve opening adjustment amount is obtained based on the initial valve opening, the outlet water temperature, and Formula 1, which is: ; In the formula, For the first Valve opening adjustment amount per control cycle To minimize the function, The first preset adjustment coefficient, This is the second preset adjustment coefficient. This is the lower limit temperature value of the target temperature range. This represents the upper limit temperature value of the target temperature range. For the first The outlet water temperature detected in each control cycle This represents the maximum allowable change in opening degree within a single control cycle. The current valve opening is obtained based on the initial valve opening, the valve opening adjustment amount, the valve opening range, and Formula 2, which is: ; In the formula, For the first The valve opening degree per control cycle, i.e. The current valve opening. To maximize the function, This represents the lower limit of the valve opening range. For the first The valve opening degree per control cycle, i.e. This is the initial valve opening. This represents the upper limit of the valve opening range; Set the current valve opening to the initial valve opening, and repeat the process of obtaining the outlet water temperature based on the initial valve opening.

[0054] This paper describes the typical peak-valley day operation of two 660MW ultra-supercritical once-through boiler generator units. During the daytime, when the load is high and the output of new energy sources fluctuates significantly, the two generator units operate in parallel to bear the system load. When entering the nighttime valley and the peak-shaving demand lasts for a long period, after receiving the dispatch deep peak-shaving instruction or detecting that the system load has dropped to a preset threshold, the power plant, based on the prediction of the valley duration, and when the predicted valley duration is not less than the preset critical shutdown time, implements the hot standby maintenance method based on flue gas and steam synergistic coupling proposed in this application: first, the generator unit to be decommissioned is reduced to a load level that meets the safety, stability, and minimum allowable operating boundary; then, the generator unit is disconnected from grid-connected power generation and put into hot standby status; at the same time, only one generator unit is retained as the operating generator unit 1000, maintaining operation in a relatively economical stable load range to reduce the significant efficiency drop caused by both generator units being simultaneously in the low load range. When the load increases the following day or the output of new energy sources decreases, requiring a rapid restoration of power plant output, the power plant, upon receiving a start-up command or detecting that the system load has rebounded to a preset threshold, organizes a rapid start-up process for the hot standby units. This allows the hot standby units to complete start-up preparation and achieve grid connection within a short period, and the power plant resumes having both generator units share the load. To avoid a single generator unit bearing the start-up and shutdown cycle for an extended period, the power plant, based on the principle of balanced start-up and shutdown frequency or according to a preset rotation cycle, exchanges the roles of operating generator unit 1000 and hot standby generator unit 2000 in subsequent operating cycles. This allows the two generator units to alternate between operating and hot standby tasks, thus forming a sustainable two-shift rotation start-up and shutdown operation mode.

[0055] During the process of a generator set switching from grid-connected operation to hot standby, this application adopts a hot standby maintenance method that combines flue gas coupling and steam coupling. The operating generator set 1000 draws a suitable amount of flue gas from the horizontal flue of its boiler and transports it to the furnace of the boiler of the hot standby generator set 2000 through a flue gas coupling pipeline. During the transportation process, isolation and pressurization measures are used to prevent backflow and ensure stable supply, so that the heating surfaces of the furnace, horizontal flue, and tail flue of the boiler of the hot standby generator set 2000 are kept in a hot state. Optionally, the control target is to ensure that the flue gas temperature in the horizontal flue and tail flue of the hot standby generator set 2000 is not lower than the preset lower limit corresponding to the hot standby maintenance requirement. This is to maintain the hot state level of the convective heating surfaces in the horizontal flue and tail flue, thereby reducing the temperature drop rate during generator set shutdown and reducing the temperature rise requirement before startup the next day. The preset lower limit corresponding to the hot standby maintenance requirement represents the flue gas temperature value that is preset to ensure that the heating surfaces and internal working fluid in the horizontal flue and tail flue of the hot standby generator set are in the hot state required for hot standby and to meet the subsequent startup requirements. Meanwhile, cold reheat steam about to enter the reheater is drawn from the operating generator set 1000 side and, after regulation, enters the auxiliary steam header. From the auxiliary steam header, steam is supplied to the hot standby generator set 2000 side. Optionally, the deaerator of the hot standby generator set 2000 is kept at a preset temperature and pressure level, and the feedwater temperature of the hot standby generator set 2000 is not lower than a preset lower limit, as the control objectives. The deaerator and feedwater system of the hot standby generator set 2000 are heated and maintained, so that the deaerator of the hot standby generator set 2000 is kept hot and the feedwater temperature of the hot standby generator set 2000 is increased. Among them, using cold reheat steam about to enter the reheater as the auxiliary steam source can meet the hot standby maintenance requirements of the hot standby generator set 2000 side. At the same time, because its parameter level is relatively moderate, the steam supply regulation response is more stable, and the disturbance to the high temperature main steam system and the high temperature reheat system is relatively smaller, the impact on the flow and safety of the operating generator set 1000 is reduced, and the controllability and stability of the steam supply control under the condition of frequent switching between operating state and hot standby state is improved. The condensate and feedwater passages on the 2000-side of the hot standby generator unit remain continuous. Optionally, the condensate and feedwater passages on the 2000-side of the hot standby generator unit meet the hydrodynamic boundary requirements, such as the minimum feedwater flow rate of the once-through boiler. This ensures that the feedwater system of the 2000-side hot standby generator unit has a stable thermal foundation and hydrodynamic boundary conditions during hot standby, thereby reducing the risk of sudden temperature differences in the heating surfaces caused by low-temperature feedwater during the start-up phase of the once-through boiler. During the start-up and shutdown switching phase, through the regulation and de-temperature control of the high-pressure and low-pressure bypasses in the steam passage, and the channel organization of the high-pressure and low-pressure feedwater bypasses in the feedwater and condensate passages, the control objectives are optionally set to limit the rate of change of steam pressure and temperature and ensure the continuity of the feedwater and condensate passages. This makes the changes in steam parameters smoother and the water-side passages more continuous, improving the safety margin and controllability of the start-up and shutdown process.

[0056] During nighttime shutdowns, if the standby generator set 2000 in this application is only naturally cooled using conventional shutdown methods, the main steam temperature typically drops to approximately 480°C and the reheat steam temperature to approximately 465°C after approximately 8 hours of shutdown. This corresponds to the hot start-up operating condition range, requiring a significant reheating process for startup the following day. By adopting the combined flue gas coupling and steam coupling hot standby maintenance method of this application, the heating surfaces of the horizontal and tail flues of the boiler of the standby generator set 2000 can be preheated and insulated during shutdowns. The deaerator and feedwater systems on the standby generator set 2000 side can also be heated and maintained, thereby slowing down the cooling rate of the main and reheat systems and related heated components. This ensures that at the end of the hot standby state, the main steam temperature is as close as possible to the extremely hot start-up temperature level of approximately 505°C and the reheat steam temperature is as close as possible to the extremely hot start-up temperature level of approximately 490°C. This reduces the start-up heating requirement and minimizes temperature fluctuations and start-up / shutdown thermal stress, creating conditions for rapid subsequent start-up and grid connection.

[0057] Taking an 8-hour nighttime off-peak period as an example, and requiring the total power plant output to remain constant, this paper compares the economics of two peak-shaving organization methods. Method 1 involves both generator units operating at deep load reduction simultaneously, i.e., both generator units operating at approximately 20% load to meet the total output constraint. Method 2 employs the hot standby maintenance method proposed in this application, which alternates between operating and hot standby states. Only one generator unit is maintained at approximately 40% load, while the other generator unit is de-grid and enters hot standby mode. The comparison results show that, under the condition of constant total power plant output, when both generator units are maintained at approximately 20% load, the unit coal consumption for power generation is approximately 345.11 g / kWh; while using the combined flue gas coupling and steam coupling hot standby maintenance method proposed in this application, and maintaining only one generator unit at approximately 40% load, the unit coal consumption for power generation can be reduced to approximately 296.47 g / kWh. The above comparison illustrates that this application achieves superior economic efficiency during longer off-peak periods by shutting down the generator set and maintaining it in a hot standby state, while another generator set undertakes higher load operation. Correspondingly, the critical shutdown time for the alternating start-stop method is approximately 6.50 hours. This means that when the generator set shutdown duration exceeds this critical shutdown time, the fuel cost savings from the alternating start-stop method can cover the additional costs incurred during the start-stop process. In actual operation, if locally applicable deep peak-shaving compensation and start-stop compensation mechanisms are further considered, the overall incremental benefits of the alternating start-stop operation method supported by this application compared to the continuous low-load operation method are typically further increased.

[0058] To verify the applicability of this application over a long-term operating period, calculations were performed based on one year of operating data from two 660MW ultra-supercritical once-through boiler generator units. The calculations assumed that the total power plant output remained constant. A low-load continuous operation mode where both generator units maintained approximately 20% load was compared with a rotational start-stop mode using the flue gas coupling and steam coupling combined hot standby maintenance method proposed in this application, where only one generator unit maintained approximately 40% load while the other generator unit was shut down and entered hot standby. In this case, 50 hot start-stop events with shutdown durations of 5–10 hours were selected as a statistical sample, with an average shutdown duration of approximately 7.96 hours. The calculation results show that, under the condition of constant total output, the rotational start-stop mode allows the operating generator units to avoid the deep low-load operating range of dual-unit synchronization, thereby reducing unit coal consumption for power generation. Based on the conventional revenue calculation excluding ancillary service compensation, the annual conventional revenue for the rotational start-stop method is approximately RMB 6.1559 million, while that for the low-load continuous operation method is approximately RMB 5.2612 million, with the former increasing by approximately RMB 894,700. If applicable deep peak-shaving compensation and start-stop compensation mechanisms are further included, the annual comprehensive revenue for the rotational start-stop method is approximately RMB 62.2229 million, while that for the low-load continuous operation method is approximately RMB 44.6632 million, with the former increasing by approximately RMB 17.5597 million. These results indicate that the rotational start-stop method proposed in this application has long-term economic advantages.

[0059] It should be understood that the phrases "one embodiment" or "some embodiments" throughout the specification mean that a specific feature, structure, or characteristic related to an embodiment is included in at least one embodiment of this application. Therefore, "in one embodiment" or "in one embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. It should be understood that in the various embodiments of this application, the sequence numbers of the above-described processes do not imply a sequential order of execution; the execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application. The sequence numbers of the above-described embodiments are merely descriptive and do not represent the superiority or inferiority of the embodiments.

[0060] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0061] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components may be combined, or integrated into another device, or some features may be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed may be through some interfaces, and the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0062] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0063] In addition, each functional unit in the various embodiments of this application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0064] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0065] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a device (which may be a terminal or platform, etc.) to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0066] Finally, it should be noted that the above content is only used to illustrate the technical solution of this application, and is not intended to limit the scope of protection of this application. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of this application shall not depart from the substance and scope of the technical solution of this application.

Claims

1. A power generation device based on the synergistic coupling of flue gas and steam, characterized in that, It includes at least two generator sets, flue gas coupling pipelines, steam coupling pipelines, and high-pressure bypass and low-pressure bypass respectively installed on each of the generator sets. The generator sets include a boiler, a steam turbine, and a main steam circuit assembly. The boiler includes a furnace and a horizontal flue. The main steam circuit assembly includes a superheater, a reheater, a condenser, and a deaerator. Each of the generator sets has a horizontal flue gas coupling pipeline between its horizontal flue and the furnace of the other generator sets; each of the generator sets has a steam coupling pipeline between the input end of the reheater and the input end of the deaerator of the other generator sets; the high-pressure bypass includes a high-pressure bypass main line and a high-pressure regulating branch line, the high-pressure bypass main line is connected between the output end of the superheater and the input end of the reheater, and the high-pressure regulating branch line is connected between the output end of the deaerator and the high-pressure bypass main line; The low-pressure bypass includes a low-pressure bypass main line and a low-pressure regulating branch line. The low-pressure bypass main line is connected between the output end of the reheater and the input end of the condenser, and the low-pressure regulating branch line is connected between the output end of the condenser and the low-pressure bypass main line.

2. The power generation device based on the synergistic coupling of flue gas and steam according to claim 1, characterized in that, The steam turbine includes a high-pressure cylinder, an intermediate-pressure cylinder, and a low-pressure cylinder. The main steam circuit assembly also includes a low-pressure heater and a high-pressure heater. The high-temperature side of the low-pressure heater is located between the output end of the low-pressure cylinder and the input end of the condenser. The low-temperature side of the low-pressure heater is located between the output end of the condenser and the input end of the deaerator. The high-temperature side of the high-pressure heater is located between the output end of the high-pressure cylinder and the input end of the deaerator. The low-temperature side of the high-pressure heater is located between the output end of the deaerator and the input end of the superheater.

3. The power generation device based on the synergistic coupling of flue gas and steam according to claim 2, characterized in that, The power generation device based on flue gas and steam co-coupling also includes a low-pressure feedwater bypass and a high-pressure feedwater bypass. The low-pressure feedwater bypass is connected between the input and output terminals of the low-temperature side of the low-pressure heater, and the high-pressure feedwater bypass is connected between the input and output terminals of the high-pressure heater.

4. The power generation device based on the synergistic coupling of flue gas and steam according to claim 1, characterized in that, The flue gas coupling pipeline includes a coupling flue gas control valve and an auxiliary flue gas manifold. The coupling flue gas control valve is used to control the on / off state of the flue gas coupling pipeline; The auxiliary flue gas header is used to acquire and transport coupled flue gas when the flue gas coupling pipeline is connected. The coupled flue gas represents the flue gas transported from the horizontal flue of the operating generator set to the furnace of the non-operating generator set.

5. The power generation device based on the coordinated coupling of flue gas and steam according to claim 1 or 4, characterized in that, The boiler also includes a water-cooled wall and a tail flue, with the water-cooled wall surrounding the lower end of the furnace. The superheaters are respectively arranged in the tail flue, in the water-cooled wall and in the upper part of the furnace; The reheaters are respectively arranged in the tail flue and the horizontal flue; The inlet of the flue gas coupling pipeline is located near the reheater located within the horizontal flue.

6. The power generation device based on the synergistic coupling of flue gas and steam according to claim 1, characterized in that, The steam coupling pipeline includes an auxiliary steam header and a coupling steam regulating valve; The coupling steam regulating valve is used to control the on / off state of the steam coupling pipeline, and to regulate the steam in the steam coupling pipeline to obtain coupling steam when the steam coupling pipeline is on. The coupling steam represents the steam supplied from the input end of the reheater of the operating generator set to the input end of the deaerator of the non-operating generator set.

7. A method for maintaining thermal standby based on the coordinated coupling of flue gas and steam, implemented using the power generation device based on the coordinated coupling of flue gas and steam as described in any one of claims 1-6, characterized in that, include: Based on the at least two generator sets, at least one operating generator set and at least one hot standby generator set are obtained respectively; At least one first flue gas coupling pipeline is obtained based on the at least one operating generator set, at least one hot standby generator set and the flue gas coupling pipeline, each of the hot standby generator sets corresponds to one first flue gas coupling pipeline, the first flue gas coupling pipeline represents the flue gas coupling pipeline connected between the first horizontal flue and the corresponding second furnace, the first horizontal flue represents the horizontal flue of the operating generator set, and the second furnace represents the furnace of the hot standby generator set; At least one first steam coupling pipeline is obtained based on the at least one operating generator set, at least one hot standby generator set, and the steam coupling pipeline. Each hot standby generator set corresponds to one first steam coupling pipeline. The first steam coupling pipeline represents the steam coupling pipeline connected between the input end of the first reheater and the input end of the second deaerator. The first reheater represents the reheater of the operating generator set, and the second deaerator represents the deaerator of the hot standby generator set. A second high-voltage bypass and a second low-voltage bypass are respectively obtained according to the at least one hot standby generator set, wherein the second high-voltage bypass represents the high-voltage bypass corresponding to the hot standby generator set, and the second low-voltage bypass represents the low-voltage bypass corresponding to the hot standby generator set. The second high-pressure bypass includes a second high-pressure bypass main line and a second high-pressure regulating branch line. The second high-pressure bypass main line is connected between the output end of the second superheater and the input end of the second reheater. The second superheater represents the superheater of the hot standby generator set, and the second reheater represents the reheater of the hot standby generator set. The second high-pressure regulating branch line is connected between the output end of the second deaerator and the second high-pressure bypass main line. The second low-pressure bypass includes a second low-pressure bypass main line and a second low-pressure regulating branch line. The second low-pressure bypass main line is connected between the output end of the second reheater and the input end of the second condenser. The second condenser represents the condenser of the hot standby generator set. The low-pressure regulating branch line is connected between the output end of the second condenser and the second low-pressure bypass main line. The corresponding coupled flue gas is obtained according to each of the first flue gas coupling pipelines and the corresponding operating generator sets; The corresponding coupling steam is obtained according to each of the first steam coupling pipelines and the corresponding hot standby generator sets; The coupled flue gas is delivered to each of the second furnace chambers through the first flue gas coupling pipeline; The coupled flue gas is sequentially conveyed from the second furnace to the second horizontal flue and the second tail flue, the second horizontal flue representing the horizontal flue of the hot standby generator set, and the second tail flue representing the tail flue of the hot standby generator set. The coupled steam is delivered to each of the second deaerators via the first steam coupling pipeline; The main hot standby steam-water circuit is obtained based on the coupled steam, the hot standby generator set, the second high-pressure bypass, and the second low-pressure bypass. The transmission path of the coupled steam in the main hot standby steam-water circuit includes sequentially passing through the second deaerator, the second superheater, the second high-pressure bypass main line, the second reheater, the second low-pressure bypass main line, the second condenser, and the second deaerator.

8. The thermal standby maintenance method based on the synergistic coupling of flue gas and steam according to claim 7, characterized in that, The corresponding coupled flue gas is obtained according to each of the first flue gas coupling pipelines and the corresponding operating generator set, including: The extracted flue gas is obtained from the first horizontal flue of the operating generator set corresponding to the first flue gas coupling pipeline; When the flue gas temperature of the extracted flue gas flues within the statistical window does not exceed the preset temperature: The extracted flue gas is pretreated to obtain the coupled flue gas.

9. The thermal standby maintenance method based on the synergistic coupling of flue gas and steam according to claim 8, characterized in that, The time range of the statistical window includes a continuous duration of 5 minutes to a continuous duration of 30 minutes.

10. The thermal standby maintenance method based on the synergistic coupling of flue gas and steam according to claim 7, characterized in that, According to each of the first steam coupling pipelines and the corresponding hot standby generator sets, corresponding coupling steam is obtained, including: Adjust the valve opening of the first coupling steam regulating valve, which represents the coupling steam regulating valve on the first steam coupling pipeline; Obtain the outlet water temperature at the output end of the second deaerator in the hot standby generator set, which corresponds to the first steam coupling pipeline; Compare the stated outlet water temperature with the target temperature range; Adjust the valve opening of the first coupling steam regulating valve according to the comparison results. The first coupling steam regulating valve represents the coupling steam regulating valve on the first steam coupling pipeline. When the outlet water temperature is within the target temperature range: The coupled steam is obtained based on the adjusted valve opening.

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