A load adjusting device for a circulating fluidized bed boiler

Abstract

The application discloses a circulating fluidized bed boiler load adjusting device, which comprises a boiler furnace, a cyclone separator, a hot primary air system, and a return feeder.The boiler furnace is connected with the cyclone separator through an exhaust pipe.The bottom of the cyclone separator is connected with the boiler furnace through a return pipe of the return feeder.The return feeder is provided with an ash outlet.The hot primary air system comprises a cold ash collector and an air preheater.The ash inlet of the cold ash collector is communicated with the ash outlet through a communication pipe, and the communication pipe is provided with a cold ash collector ash inlet valve.The cold ash collector is provided with a primary air heat exchange pipeline.The primary air heat exchange pipeline is provided with a primary air inlet and a primary air outlet.The primary air inlet of the cold ash collector is communicated with an air preheater outlet air duct of the air preheater.The primary air outlet of the cold ash collector is communicated with a distribution air plate of the boiler furnace, so that the primary air discharged from the air preheater outlet air duct is heated in the cold ash collector and then is sent into the boiler furnace.The application improves the ascending and descending load rate of the circulating fluidized bed boiler and improves the denitration reaction efficiency.

Description

Technical Field

[0001] This invention relates to the field of circulating fluidized bed boiler combustion technology, and more particularly to a circulating fluidized bed boiler load adjustment device. Background Technology

[0002] The circulating fluidized bed boiler will expand the minimum stable combustion and peak shaving depth from 40% BMCR (Boiler maximum continuous rating) to 20% BMCR through various optimization and transformation technologies, thereby significantly increasing the proportion of new energy consumption by the power grid and realizing the construction of a new power system with new energy as the main body.

[0003] Currently, large-scale circulating fluidized bed boilers with a capacity of 300MW are required to achieve nitrogen oxide emissions of 50mg / Nm³ during periods of deep peak shaving. 3 To meet the following ultra-low emission standards, in-service circulating fluidized bed boilers are undergoing flue gas recirculation combustion retrofitting, combined with technical upgrades to optimize the in-furnace SNCR (selective non-catalytic reduction) denitrification system, in order to ensure that the initial nitrogen oxide emissions of the boilers meet the emission standards during deep peak shaving.

[0004] However, circulating fluidized bed (CFB) boilers currently exhibit problems such as high thermal inertia and slow peak-shaving rates when participating in deep peak shaving. It is noteworthy that, on the one hand, the circulating ash in a CFB boiler is fundamental for maintaining fluidized combustion. During different load operations, a reasonable amount of circulating ash is needed to participate in combustion and heat transfer within the furnace, thereby achieving rapid load changes and stable combustion. However, the ash content of the coal used in CFB boilers at different power plants, and even within the same power plant at different stages, varies significantly. When a CFB boiler using high-ash coal participates in deep peak shaving for rapid load reduction, the large amount of circulating ash in the furnace stores a significant amount of heat and exhibits high thermal inertia. This prevents the circulating ash from decreasing rapidly during load reduction, resulting in a low load reduction rate. Simultaneously, during deep peak shaving for rapid load increase, the rate of increase in circulating ash within the furnace is slow, leading to localized overheating and coking. The lack of circulating ash participating in fluidized combustion and heat transfer further contributes to a low boiler load increase rate. On the other hand, when the circulating fluidized bed boiler is burning steadily at 20% load, the combustion temperature inside the furnace is low, which is lower than the reaction temperature window of SNCR denitrification of 750℃~950℃, resulting in low SNCR denitrification reaction efficiency.

[0005] Therefore, how to improve the denitrification reaction efficiency while increasing the load increase / decrease rate of circulating fluidized bed boilers is a problem that engineers and technicians in this field urgently need to solve. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a load adjustment device for a circulating fluidized bed boiler, so as to improve the denitrification reaction efficiency while increasing the load adjustment rate of the circulating fluidized bed boiler.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A load adjustment device for a circulating fluidized bed boiler includes:

[0009] Boiler furnace;

[0010] The boiler furnace is connected to the cyclone separator via a flue gas pipe. The bottom of the cyclone separator is connected to the boiler furnace via a return pipe of a return feeder. The return feeder is equipped with an ash discharge port.

[0011] The hot primary air system includes an ash cooler and an air preheater. The ash inlet of the ash cooler is connected to the ash outlet via a connecting pipe, and the connecting pipe is equipped with an ash inlet valve for the ash cooler. The ash cooler has a primary air heat exchange pipeline with a primary air inlet and a primary air outlet. The primary air inlet of the ash cooler is connected to the air preheater outlet duct of the air preheater, and the primary air outlet of the ash cooler is connected to the air distribution plate of the boiler furnace, so that the primary air discharged from the air preheater outlet duct exchanges heat with the ash cooler and is sent into the boiler furnace.

[0012] Optionally, in the above-mentioned circulating fluidized bed boiler load adjustment device, the hot primary air system further includes a steam heater, the steam heater includes a steam circuit and an air circuit, the steam circuit includes a steam inlet and a steam outlet, the steam inlet is connected to the low-pressure steam extraction device of the steam turbine, and the steam outlet is connected to the deaerator through a steam outlet pipeline;

[0013] The primary air outlet of the ash cooler is connected to the boiler furnace through the air circuit of the steam heater.

[0014] Optionally, in the above-mentioned circulating fluidized bed boiler load adjustment device, the primary air inlet of the ash cooler is connected to the air preheater outlet air duct of the air preheater through a first connecting pipe, and a first regulating valve is connected in series on the first connecting pipe.

[0015] The hot primary air system also includes a second connecting pipe, through which the air preheater outlet air duct is connected to the boiler furnace, and a second regulating valve is connected in series on the second connecting pipe.

[0016] Optionally, the above-mentioned circulating fluidized bed boiler load adjustment device also includes a furnace front ash storage silo, which is connected to the ash discharge port of the ash cooler through an ash storage pipe, and the ash storage pipe is equipped with an ash storage silo pump.

[0017] The boiler furnace is equipped with a secondary air nozzle for ash replenishment. The outlet of the ash storage bin in front of the furnace is connected to the secondary air nozzle for ash replenishment via a circulating ash pipe, and an ash replenishment bin pump is installed on the circulating ash pipe.

[0018] Optionally, in the above-mentioned circulating fluidized bed boiler load adjustment device, the ash cooler further includes water-cooled heat exchange pipelines;

[0019] The water-cooled inlet of the water-cooled heat exchange pipeline is connected to the condenser through a water-cooled inlet pipeline, and an inlet control valve is installed on the water-cooled inlet pipeline. The water-cooled outlet of the water-cooled heat exchange pipeline is connected to the deaerator through a water-cooled outlet pipeline.

[0020] Optionally, in the above-mentioned circulating fluidized bed boiler load adjustment device, the return pipe connecting the return feeder to the boiler furnace is provided with a return feeder inclined leg ash filling port, the circulating ash pipe is connected to the return feeder inclined leg ash filling port, and the ash filling silo pump is located upstream of the return feeder inclined leg ash filling port.

[0021] Optionally, in the above-mentioned circulating fluidized bed boiler load adjustment device, the primary air heat exchange pipeline and the water-cooled heat exchange pipeline are arranged sequentially along the direction from the ash inlet to the ash outlet of the ash cooler.

[0022] Optionally, the above-mentioned circulating fluidized bed boiler load adjustment device further includes a first temperature sensor for detecting the temperature at the ash discharge port of the ash cooler and obtaining the ash discharge temperature;

[0023] The second temperature sensor is used to detect the temperature at the water-cooled outlet of the water-cooled heat exchange pipeline and obtain the drainage temperature.

[0024] The controller is used to close the ash inlet valve and the water inlet control valve of the ash cooler when the ash discharge temperature is lower than the first preset temperature or the drainage temperature is lower than the second preset temperature.

[0025] Optionally, the above-mentioned circulating fluidized bed boiler load adjustment device also includes an alarm, wherein the controller controls the alarm to sound when the ash discharge temperature is lower than a first preset temperature or when the drainage temperature is lower than a second preset temperature.

[0026] Optionally, in the above-mentioned circulating fluidized bed boiler load adjustment device, the controller is further configured to control the ash inlet valve of the ash cooler to close when the drainage temperature is higher than the third preset temperature, wherein the third preset temperature is higher than the second preset temperature.

[0027] Optionally, the above-mentioned circulating fluidized bed boiler load adjustment device further includes:

[0028] The third temperature sensor is used to detect the temperature at the ash inlet of the ash cooler and obtain the ash inlet temperature;

[0029] The fourth temperature sensor is used to detect the temperature at the location between the primary air heat exchange pipe and the water cooling heat exchange pipe of the ash cooler, and to obtain the temperature in the middle of the ash cooler.

[0030] The controller is configured to output a maintenance signal for the primary air heat exchange pipeline when the difference between the temperature in the middle of the ash cooler and the ash inlet temperature is less than a first preset difference; and to output a maintenance signal for the water-cooled heat exchange pipeline when the ash discharge temperature and the temperature in the middle of the ash cooler are less than a second preset difference.

[0031] The circulating fluidized bed boiler load adjustment device provided by this invention connects the boiler furnace to a cyclone separator via a flue gas duct. The bottom of the cyclone separator is connected to the boiler furnace via a return pipe of a return feeder, which is equipped with an ash discharge port. The hot primary air system includes an ash cooler and an air preheater. The ash inlet of the ash cooler is connected to the ash discharge port via a connecting pipe, which is equipped with an ash inlet valve. The ash cooler has a primary air heat exchange pipeline connected to the air preheater outlet duct and the air distribution plate of the boiler furnace. When the boiler needs to operate at low load or rapidly reduce load, the high-temperature return ash discharged from the ash discharge port of the return feeder heats the primary air through the ash cooler, increasing the primary air temperature. Finally, the primary air is sent into the boiler furnace to participate in combustion, thereby increasing the bed temperature and the upper part of the boiler furnace temperature during deep peak shaving and low load operation. This is beneficial to improving the efficiency of the SNCR denitrification system in the furnace. At the same time, the increased bed temperature during low load operation also helps to stabilize boiler combustion and reduce the carbon content of boiler fly ash and bottom ash.

[0032] When the boiler needs to rapidly increase load and operate stably at medium to high loads, the ash inlet valve of the ash cooler is closed. This allows the primary air in the air preheater outlet duct to no longer be heated by the high-temperature hot ash discharged from the return feeder's ash discharge port, but instead directly enters the boiler furnace for combustion through the ash cooler. The configuration of the primary air heat exchange pipeline in the ash cooler allows for dynamic adjustment of the primary air temperature entering the boiler furnace according to the needs of load increases and decreases, which is beneficial for the boiler's deep peak-shaving and variable load operation. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the principle of the circulating fluidized bed boiler load adjustment device provided in Embodiment 1 of the present invention;

[0035] Figure 2 This is a schematic diagram of the principle of the circulating fluidized bed boiler load adjustment device provided in Embodiment 2 of the present invention.

[0036] Figure 1 The meanings of the various reference numerals in the attached figures are as follows:

[0037] 100 is the boiler furnace, and 101 is the secondary air nozzle ash inlet;

[0038] 200 is a cyclone separator;

[0039] 300 is the return feeder, 301 is the ash discharge port, and 302 is the ash filling port of the return feeder's inclined leg;

[0040] 400 is the hot primary air system, 401 is the ash cooler, 4011 is the primary air heat exchange pipeline, 4012 is the water-cooled heat exchange pipeline, 402 is the air preheater outlet duct, 403 is the steam air heater, 404 is the first connecting pipeline, 4041 is the first regulating valve, 405 is the second connecting pipeline, and 4051 is the second regulating valve.

[0041] 501 is the furnace front ash storage bin, 502 is the ash storage bin pump, 503 is the ash inlet valve of the ash cooler, 504 is the ash replenishment bin pump, 505 is the condenser, 506 is the turbine low-pressure extraction device, and 507 is the deaerator. Detailed Implementation

[0042] The core of this invention is to provide a load adjustment device for a circulating fluidized bed boiler, so as to improve the denitrification reaction efficiency while increasing the load adjustment rate of the circulating fluidized bed boiler.

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] like Figures 1-2 As shown in the figure, an embodiment of the present invention discloses a circulating fluidized bed boiler load adjustment device, including a boiler furnace 100, a cyclone separator 200 and a hot primary air system 400.

[0045] like Figure 1As shown, the boiler furnace 100 is connected to the cyclone separator 200 via a flue gas duct. Flue gas carrying solid particles enters the cyclone separator 200 tangentially. Under centrifugal force, the solid particles (ash) in the flue gas are thrown against the cylinder wall of the cyclone separator 200 and slide down the wall into the return feeder 300 connected to the cyclone separator 200. From there, they enter the boiler furnace 100 through the return pipe, participating in the circulating combustion within the boiler furnace 100. The flue gas inside the cyclone separator 200 enters the tail flue. It should be noted that the cyclone separator 200 is a commonly used device for gas-solid system separation, and there is more than one of them.

[0046] The hot primary air system 400 includes an ash cooler 401 and an air preheater. The return feeder 300 is equipped with an ash discharge port 301. The ash inlet of the ash cooler 401 is connected to the ash discharge port 301 via a connecting pipe. That is, the returned ash in the return feeder 300 can enter the boiler furnace 100 through the return pipe, or it can enter the ash cooler 401 through the ash discharge port 301. It should be noted that the returned ash has a high temperature, approximately 850℃~950℃, and high fluidity. Under the action of gravity, it enters the boiler furnace 100 or the ash cooler 401 through the return pipe. An ash inlet valve 503 is installed on the connecting pipe. By controlling the opening of the ash inlet valve 503, the amount of returned ash entering the ash cooler 401 and the opening and closing of the ash inlet circuit can be adjusted. Those skilled in the art will understand that the ash inlet valve 503 is a commonly used regulating valve; its specific type is not limited here, but can be selected according to actual conditions. It should be noted that each cyclone separator 200 has a ash discharge port 301 at the bottom of the return feeder 300. According to the bed temperature deviation control requirements, the ash discharge ports 301 of different return feeders 300 can be opened to put the returned ash into the ash cooler 401, so as to realize the differentiated control requirements of bed temperature and material layer along the width of the air distribution plate.

[0047] The ash cooler 401 has a primary air heat exchange pipe 4011, which has a primary air inlet and a primary air outlet. The primary air inlet of the ash cooler 401 is connected to the air preheater outlet duct 402 of the air preheater, and the primary air outlet of the ash cooler 401 is connected to the air distribution plate of the boiler furnace 100. After being heated by the air preheater, the primary air discharged from the air preheater outlet duct 402 enters the ash cooler 401. The return ash in the return feeder 300 flows from top to bottom, exchanging heat with the primary air. The temperature of the return ash is higher, heating the primary air and increasing its temperature. The primary air after heat exchange is then sent into the boiler furnace 100. It should be noted that the ash cooler 401 adopts an indirect cooling counter-current heat exchange method, with the primary air flowing through the tubes and the return ash flowing through the shell. The air preheater is a commonly used heat exchange device in boilers, and its specific principle will not be elaborated here.

[0048] The circulating fluidized bed boiler load adjustment device provided by this invention utilizes the high-temperature return ash discharged from the ash discharge port 301 of the return feeder 300 to heat the primary air through the ash cooler 401, thereby increasing the primary air temperature. Finally, the primary air is sent into the boiler furnace 100 to participate in combustion, thereby increasing the bed temperature and the upper part of the boiler furnace 100 to above 750°C during the deep peak-shaving low-load operation. This is beneficial to improving the efficiency of the SNCR denitrification system in the furnace. At the same time, the increase in bed temperature during low-load operation is also beneficial to the stable combustion of the boiler and the reduction of carbon content in the boiler fly ash bottom ash.

[0049] When the boiler needs to rapidly increase load and operate stably at medium to high loads, the ash inlet valve 503 of the ash cooler 401 is closed. This allows the primary air from the air preheater outlet duct 402 to no longer be heated by the high-temperature hot ash discharged from the ash discharge port 301 of the return feeder 300, but instead directly enters the boiler furnace 100 for combustion through the ash cooler 401. The primary air heat exchange pipeline 4011 of the ash cooler 401 can dynamically adjust the temperature of the primary air entering the boiler furnace 100 according to the needs of load increases and decreases, which is beneficial for the boiler's deep peak-shaving and load-changing operation.

[0050] When the boiler needs to operate at low load or rapidly reduce load, in order to further increase the temperature of the primary air, such as Figure 2 As shown, in a specific embodiment of the present invention, the hot primary air system 400 further includes a steam heater 403. The steam heater 403 includes a steam circuit and an air circuit. The steam circuit includes a steam inlet and a steam outlet. The steam inlet is connected to the turbine low-pressure extraction steam device 506. The turbine low-pressure extraction steam device 506 provides steam as a heat transfer medium to the steam heater 403 to heat the primary air and increase its temperature. The steam outlet is connected to the deaerator 507 through a steam outlet pipeline. After the steam heater 403 heats the primary air, the steam is cooled and becomes condensate, which enters the deaerator 507, thus realizing the reuse of waste heat and water. The primary air outlet of the ash cooler 401 is connected to the boiler furnace 100 through the air circuit of the steam heater 403. That is, after the primary air passes through the air preheater outlet duct 402, it flows through the ash cooler 401 and the steam heater 403 in sequence. The primary air exchanges heat with the return ash at the ash cooler 401 and is heated for the first time. Then it enters the steam heater 403 and is heated by steam for the second time, which increases the temperature of the primary air and improves the load reduction rate and denitrification reaction efficiency of the circulating fluidized bed boiler.

[0051] To improve the load response rate during load adjustment of the circulating fluidized bed boiler, based on the above embodiment, the primary air inlet of the ash cooler 401 is connected to the air preheater outlet duct 402 of the air preheater via a first connecting pipe 404. A first regulating valve 4041 is connected in series on the first connecting pipe 404 to regulate the primary air volume entering the ash cooler 401. The hot primary air system 400 also includes a second connecting pipe 405. The air preheater outlet duct 402 is connected to the boiler furnace 100 via the second connecting pipe 405, and a second regulating valve 4051 is connected in series on the second connecting pipe 405. That is, the primary air in the air preheater outlet duct 402 is divided into two branches, one of which is the first connecting pipe 404. The primary air enters the ash cooler 401 through the first connecting pipe 404 and then enters the boiler furnace 100 through the connecting pipe between the ash cooler 401 and the boiler furnace 100 after exiting the ash cooler 401. The other branch is the second connecting pipe 405, through which the primary air directly enters the boiler furnace 100. It should be noted that the primary air from the two branches can be mixed before entering the boiler furnace 100. After mixing, it enters the boiler furnace 100. The setting of the first connecting pipe 404 increases the temperature of the primary air entering the boiler furnace 100.

[0052] The configuration of the first regulating valve 4041 and the second regulating valve 4051 allows for the adjustment of the primary air volume entering the first connecting pipe 404 and the second connecting pipe 405. When the boiler requires low-load operation or rapid load reduction, adjusting the openings of the first regulating valve 4041 and the second regulating valve 4051—increasing the opening of the first regulating valve 4041 and decreasing the opening of the second regulating valve 4051—ensures sufficient primary air enters the ash cooler 401 from the air preheater outlet duct 402, achieving both primary air heating and ash cooling. When the boiler requires rapid load increase or stable operation at medium to high loads, closing the first regulating valve 4041 allows the primary air from the air preheater outlet duct 402 to bypass the ash cooler 401 for heating and instead directly enter the boiler furnace 100 for combustion via the second connecting pipe 405. The two branch lines improve the rate of load adjustment in the circulating fluidized bed boiler, making load adjustment more flexible.

[0053] To further improve the load adjustment rate of circulating fluidized bed boilers, the circulating fluidized bed boiler load adjustment device disclosed in this invention also includes a furnace front ash storage silo 501. The furnace front ash storage silo 501 is connected to the ash discharge port of the ash cooler 401 through an ash storage pipe, and an ash storage silo pump 502 is installed on the ash storage pipe. That is, after the return ash exchanges heat with the primary air in the ash cooler 401, the cooled return ash enters the furnace front ash storage silo 501 for storage after being powered by the ash storage silo pump 502. The boiler furnace 100 is equipped with a secondary air nozzle ash supply port 101. The outlet of the furnace front ash storage bin 501 is connected to the secondary air nozzle ash supply port 101 through a circulating ash pipe. An ash supply hopper pump 504 is installed on the circulating ash pipe. That is, the cooled return ash stored in the furnace front ash storage bin 501 can be fed into the boiler furnace 100 through the circulating ash pipe and the secondary air nozzle ash supply port 101. In order to ensure the amount of ash supplied, an ash supply hopper pump 504 is installed on the circulating ash pipe to provide power to the circulating ash.

[0054] When the boiler needs to operate at low load or rapidly reduce load, the ash inlet valve 503 of the ash cooler is opened, and the returned ash in the return feeder 300 enters the ash cooler 401 to exchange heat with the primary air. The cooled returned ash is then pneumatically transported to the ash storage silo 501 in front of the furnace by the ash storage silo pump 502. At this time, the amount of circulating ash entering the boiler furnace 100 is reduced, that is, the amount of returned ash entering the boiler furnace 100 through the return pipe in the return feeder 300 is reduced, thereby reducing the heat transfer in the furnace by the circulating ash and achieving the purpose of rapidly reducing the boiler load. At the same time, the reduction in the amount of returned ash will increase the bed temperature and furnace combustion temperature level when the boiler is operating at low load. This can extend the stable combustion load of the circulating fluidized bed boiler from 40% to 100% BMCR to 20% to 100% BMCR, which is conducive to improving the efficiency of the SNCR denitrification system in the furnace at low load, while improving the burnability of ash and slag and the stable combustion capability of the boiler at low load.

[0055] When the boiler needs to rapidly increase load and operate stably at medium to high loads, the circulating ash content in the boiler furnace 100 is too low. Due to the lack of cooling effect from the circulating ash, the local bed temperature is prone to overheating and coking. The boiler coal feeding rate cannot be too fast either, further limiting the boiler load increase rate. Therefore, the ash replenishment pump 504 is turned on to transport the cold ash in the furnace front ash storage silo 501 to the secondary air nozzle ash replenishment port 101 via pneumatic conveying, replenishing ash into the boiler furnace 100, increasing the circulating ash content, and facilitating the uniform and rapid entry of the circulating ash into the dense phase zone and high-temperature zone of the boiler furnace 100. The circulating ash quickly fluidizes, thereby rapidly carrying the heat from the bottom of the boiler into the upper dilute phase zone of the boiler furnace 100, increasing the upper furnace temperature and ash concentration, thus enhancing the heat exchange of the upper water-cooled wall of the boiler furnace 100 and improving the boiler's load-carrying capacity. At the same time, the amount of circulating ash replenished, combined with the control of the coal feed rate, can ensure that the bed temperature does not exceed the standard during boiler load increase, improve the uniformity of the bed temperature during load increase, and avoid the problem of slag coking caused by excessively high local bed temperature during rapid load increase.

[0056] To further cool the returned ash, in a specific embodiment of the present invention, the ash cooler 401 further includes a water-cooled heat exchange pipeline 4012. That is, the ash cooler 401 is a dual-medium ash cooler, including a primary air heat exchange pipeline 4011 and a water-cooled heat exchange pipeline 4012. In the ash cooler 401, two media exchange heat with the returned ash: primary air in the primary air heat exchange pipeline 4011 exchanges heat with the returned ash, and water in the water-cooled heat exchange pipeline 4012 exchanges heat with the returned ash. The returned ash undergoes two heat exchanges, further reducing its temperature. To allow the water entering the water-cooled heat exchange pipeline 4012 to be recycled, the water-cooled inlet of the water-cooled heat exchange pipeline 4012 is connected to the condenser 505 via a water-cooled inlet pipeline. That is, low-temperature condensate (water temperature approximately 35-50°C) from the condenser 505 exchanges heat with the returned ash, causing the temperature of the returned ash to decrease and the temperature of the low-temperature condensate to increase. To control the amount of condensate entering the water-cooled heat exchanger pipe 4012, an inlet control valve is installed on the water-cooled inlet pipe. The valve only needs to control the amount of water entering the water-cooled heat exchanger pipe 4012; its specific type is not limited here. The water-cooled outlet of the water-cooled heat exchanger pipe 4012 is connected to the deaerator 507 via a water-cooled outlet pipe, allowing the heated condensate to enter the deaerator 507 to participate in deaeration, thus realizing the recovery and reuse of heat from the returned ash. It should be noted that the specific arrangement of the primary air heat exchanger 4011 and the water-cooled heat exchanger 4012 in the ash cooler 401 is not limited here. That is, the primary air heat exchanger 4011 and the water-cooled heat exchanger 4012 can be arranged sequentially along the direction from the ash inlet to the ash outlet of the ash cooler 401, or the water-cooled heat exchanger 4012 and the primary air heat exchanger 4011 can be arranged sequentially along the direction from the ash inlet to the ash outlet of the ash cooler 401.

[0057] In a specific embodiment of this invention, to increase the participation of circulating ash in heat transfer within the boiler furnace when the boiler requires rapid load increase and stable operation at medium to high loads, a return feeder 300 is provided on the return pipe connecting it to the boiler furnace 100. A return feeder inclined leg ash filling port 302 is connected to the return feeder inclined leg ash filling port 302, and the circulating ash pipe is connected to the return feeder inclined leg ash filling port 302. Specifically, the outlet of the furnace front ash storage silo 501 is connected to the secondary air nozzle ash filling port 101 and the return feeder inclined leg ash filling port 302 via the circulating ash pipe. When the boiler requires rapid load increase and stable operation at medium to high loads, the ash filling port pump 504 is activated, and the cold ash in the furnace front ash storage silo 501 is transported to the secondary air nozzle ash filling port 101 and the return feeder inclined leg ash filling port 302 via pneumatic conveying, replenishing ash into the boiler furnace 100 and increasing the amount of circulating ash. The multiple ash inlets ensure that the circulating ash can evenly cover the entire air distribution plate bed surface, ensuring uniform bed temperature during load increases and preventing local overheating and coking.

[0058] When the boiler needs to operate at low load or rapidly reduce load, in order to increase the temperature of the primary air, the return ash in the return feeder 300 is used to heat the primary air. In a specific embodiment of the present invention, the primary air heat exchange pipeline 4011 and the water-cooled heat exchange pipeline 4012 of the ash cooler 401 are arranged sequentially along the direction from the ash inlet to the ash outlet of the ash cooler 401. This arrangement can make full use of the heat of the return ash in the return feeder 300 to heat the primary air, thereby increasing the temperature of the primary air, thereby improving the bed temperature and combustion temperature levels, and improving the efficiency of the SNCR denitrification system in the furnace.

[0059] To achieve automatic control of the device and detect whether the equipment is blocked, in a specific embodiment of the present invention, the circulating fluidized bed boiler load adjustment device further includes a first temperature sensor, a second temperature sensor, and a controller. The first temperature sensor detects the temperature at the ash discharge port of the ash cooler 401 and obtains the ash discharge temperature. When the ash discharge temperature is too low, it indicates that the amount of returned ash entering the ash cooler 401 is insufficient, and the ash cooler 401 is blocked. Therefore, the blockage status of the ash cooler 401 can be determined by the ash discharge temperature, and maintenance can be performed. The second temperature sensor detects the temperature at the water-cooled outlet of the water-cooled heat exchange pipeline 4012 and obtains the drainage temperature. When the drainage temperature is too low, it indicates that the heat exchange between the returned ash and water in the water-cooled heat exchange pipeline 4012 is insufficient, meaning that the amount of returned ash entering the ash cooler 401 is insufficient, resulting in a low drainage temperature, indicating that the ash cooler 401 is blocked. Therefore, the blockage status of the ash cooler 401 can be determined by the drainage temperature, and maintenance can be performed. The controller is used to close the ash inlet valve 503 and the water inlet control valve of the ash cooler 401 when the ash discharge temperature is lower than the first preset temperature or the drainage temperature is lower than the second preset temperature, thereby enabling maintenance to check whether the ash cooler 401 is blocked. The first and second temperature sensors are commonly used temperature sensors, and their specific temperature measurement principles will not be elaborated here. Those skilled in the art should understand that the values ​​of the first and second preset temperatures are not limited here, and can be set based on experience, or can be obtained experimentally when a blockage occurs in the ash inlet of the ash cooler 401. The key is to ensure that a blockage in the ash cooler 401 can be determined when the ash discharge temperature is lower than the first preset temperature or the drainage temperature is lower than the second preset temperature.

[0060] In order to enable staff to promptly detect faults and problems that occur during equipment operation, in addition to the above embodiments, an alarm is also included. When the ash discharge temperature is lower than the first preset temperature, or the drainage temperature is lower than the second preset temperature, the controller controls the alarm to sound, so that staff can promptly detect the faults in the equipment and carry out maintenance.

[0061] In one specific embodiment of the present invention, the controller is further configured to control the opening degree of the ash inlet valve 503 of the ash cooler when the drainage temperature is higher than a third preset temperature, wherein the third preset temperature is higher than a second preset temperature. An excessively high drainage temperature indicates that the heat exchange between the returned ash and water at the location of the water-cooled heat exchange pipe 4012 is large, meaning the amount of returned ash is relatively high. Therefore, it is necessary to control the amount of returned ash entering the ash cooler 401 and reduce the opening degree of the ash inlet valve 503.

[0062] To evaluate the heat exchange effect of the equipment, the circulating fluidized bed boiler load adjustment device disclosed in this invention further includes a third temperature sensor and a fourth temperature sensor. The third temperature sensor is used to detect the temperature at the ash inlet of the ash cooler 401 and obtain the ash inlet temperature. The fourth temperature sensor is used to detect the temperature at the location between the primary air heat exchange pipe 4011 and the water-cooled heat exchange pipe 4012 of the ash cooler 401 and obtain the temperature at the middle of the ash cooler. The heat exchange effect of the primary air heat exchange pipe 4011 can be evaluated based on the difference between the temperature at the middle of the ash cooler and the ash inlet temperature, and the heat exchange effect of the water-cooled heat exchange pipe 4012 can be evaluated based on the difference between the temperature at the middle of the ash cooler and the drainage temperature. When the heat exchange effect of the primary air heat exchange pipe 4011 and the water-cooled heat exchange pipe 4012 is poor, the temperature rise of the primary air will not reach the preset value, and the temperature drop of the returned ash will not reach the preset value. When the difference between the temperature in the middle of the ash cooler and the ash inlet temperature is less than the first preset difference, the controller outputs a maintenance signal for the primary air heat exchanger 4011. When the ash discharge temperature and the temperature in the middle of the ash cooler are less than the second preset difference, the controller outputs a maintenance signal for the water-cooled heat exchanger 4012. Based on the maintenance signal, the staff can perform maintenance on the ash cooler 401.

[0063] To facilitate the control of ash quantity delivered to the ash storage silo 501 and boiler furnace 100, the circulating fluidized bed boiler load adjustment device disclosed in this invention includes metering devices and corresponding controllers for the ash storage silo pump 502 and the ash replenishment silo pump 504. When the differential pressure in the boiler furnace 100 is too high or the bed temperature in the boiler furnace 100 is too low, the controller controls the ash replenishment silo pump 504 to reduce the ash replenishment amount, and simultaneously interlocks with the slag cooler to start the bottom slag cooler for slag discharge, thus maintaining the bed pressure within a reasonable range. The ash storage silo 501 is equipped with a level gauge, alarm, and controller. When the ash level in the ash storage silo 501 is higher than the first preset level, the controller activates the alarm and simultaneously stops the ash storage silo pump 502 to stop ash feeding. When the ash level in the ash storage silo 501 is lower than the second preset level, the controller controls the ash replenishment silo pump 504 to stop operating, thus stopping ash feeding into the boiler furnace 100.

[0064] In order to monitor the operating status of the steam heater 403, the circulating fluidized bed boiler load adjustment device disclosed in this invention has a flow metering device installed at the air circuit inlet of the steam heater 403 and temperature sensors installed at the air circuit inlet and outlet, which facilitates the monitoring of the operating status of the steam heater 403.

[0065] To evaluate the heat exchange effect of the primary air heat exchanger 4011 and the steam heater 403, the circulating fluidized bed boiler load adjustment device disclosed in this invention is equipped with a fifth temperature sensor and a pressure sensor on the first connecting pipe 404 and the second connecting pipe 405. These sensors are used to measure the real-time temperature and pressure of the primary air. The real-time temperature is used to evaluate the heat exchange effect of the primary air heat exchanger 4011 and the steam heater 403. The pressure value is used to monitor the primary air pressure and to determine the resistance of the primary air flowing through the primary air heat exchanger 4011 and the steam heater 403. A sixth temperature sensor is installed on the mixing pipe of the first connecting pipe 404 and the second connecting pipe 405 to monitor the temperature of the primary air entering the boiler furnace 100.

[0066] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0067] As indicated in this application and claims, unless the context clearly indicates otherwise, the words "a," "an," "a," and / or "the" are not specifically singular and may include the plural. Generally, the terms "comprising" and "including" only indicate the inclusion of expressly identified steps and elements, which do not constitute an exclusive list, and the method or apparatus may also include other steps or elements. An element defined by the phrase "comprising an..." does not exclude the presence of other identical elements in the process, method, product, or apparatus that includes the element.

[0068] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0069] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A load adjustment device for a circulating fluidized bed boiler, characterized in that, include: Boiler furnace (100); Cyclone separator (200), the boiler furnace (100) is connected to the cyclone separator (200) through the flue gas pipe, the bottom of the cyclone separator (200) is connected to the boiler furnace (100) through the return pipe of the return feeder (300), and the return feeder (300) is provided with an ash discharge port (301). The hot primary air system (400) includes a cold ash cooler (401) and an air preheater. The ash inlet of the cold ash cooler (401) is connected to the ash outlet (301) through a connecting pipe, and the connecting pipe is equipped with a cold ash cooler ash inlet valve (503). The cold ash cooler (401) has a primary air heat exchange pipeline (4011), which has a primary air inlet and a primary air outlet. The primary air inlet of the cold ash cooler (401) is connected to the air preheater outlet duct (402) of the air preheater, and the primary air outlet of the cold ash cooler (401) is connected to the air distribution plate of the boiler furnace (100), so that the primary air discharged from the air preheater outlet duct (402) exchanges heat with the cold ash cooler (401) and is sent into the boiler furnace (100). It also includes a furnace front ash storage silo (501), which is connected to the ash discharge port of the ash cooler (401) through an ash storage pipe, and the ash storage pipe is equipped with an ash storage silo pump (502). The boiler furnace (100) is provided with a secondary air nozzle ash filling port (101), and the outlet of the furnace front ash storage bin (501) is connected to the secondary air nozzle ash filling port (101) through a circulating ash pipe, and the circulating ash pipe is provided with an ash filling bin pump (504). The ash cooler (401) also includes a water-cooled heat exchange pipeline (4012). The water-cooled inlet of the water-cooled heat exchange pipeline (4012) is connected to the condenser (505) through the water-cooled water inlet pipeline, and an inlet control valve is provided on the water-cooled water inlet pipeline. The water-cooled outlet of the water-cooled heat exchange pipeline (4012) is connected to the deaerator (507) through the water-cooled water outlet pipeline. Also includes: The first temperature sensor is used to detect the temperature at the ash discharge port of the ash cooler (401) and obtain the ash discharge temperature; The second temperature sensor is used to detect the temperature at the water-cooled outlet of the water-cooled heat exchange pipeline (4012) and obtain the drainage temperature; The controller is used to close the ash inlet valve (503) and the water inlet control valve when the ash discharge temperature is lower than the first preset temperature or the drainage temperature is lower than the second preset temperature.

2. The circulating fluidized bed boiler load adjustment device as described in claim 1, characterized in that, The hot primary air system (400) also includes a steam heater (403), which includes a steam circuit and an air circuit. The steam circuit includes a steam inlet and a steam outlet. The steam inlet is connected to the low-pressure steam extraction device (506) of the steam turbine, and the steam outlet is connected to the deaerator (507) through a steam outlet pipeline. The primary air outlet of the ash cooler (401) is connected to the boiler furnace (100) through the air circuit of the steam heater (403).

3. The circulating fluidized bed boiler load adjustment device as described in claim 2, characterized in that, The primary air inlet of the ash cooler (401) is connected to the air preheater outlet duct (402) of the air preheater through a first connecting pipe (404), and a first regulating valve (4041) is connected in series on the first connecting pipe (404). The hot primary air system (400) also includes a second connecting pipe (405), the air preheater outlet air duct (402) is connected to the boiler furnace (100) through the second connecting pipe (405), and a second regulating valve (4051) is connected in series on the second connecting pipe (405).

4. The circulating fluidized bed boiler load adjustment device as described in claim 1, characterized in that, The return feeder (300) is connected to the boiler furnace (100) by a return feeder inclined leg ash filling port (302) on the return feeder pipe. The circulating ash pipe is connected to the return feeder inclined leg ash filling port (302), and the ash filling silo pump (504) is located upstream of the return feeder inclined leg ash filling port (302).

5. The circulating fluidized bed boiler load adjustment device as described in claim 1, characterized in that, The primary air heat exchange pipeline (4011) and the water-cooled heat exchange pipeline (4012) are arranged sequentially along the direction from the ash inlet to the ash outlet of the ash cooler (401).

6. The circulating fluidized bed boiler load adjustment device as described in claim 1, characterized in that, It also includes an alarm, which the controller activates when the ash discharge temperature is lower than a first preset temperature or when the drainage temperature is lower than a second preset temperature.

7. The circulating fluidized bed boiler load adjustment device as described in claim 1, characterized in that, The controller is also used to control the opening of the ash inlet valve (503) of the ash cooler to decrease when the drainage temperature is higher than the third preset temperature, wherein the third preset temperature is higher than the second preset temperature.

8. The circulating fluidized bed boiler load adjustment device as described in claim 1, characterized in that, Also includes: The third temperature sensor is used to detect the temperature at the ash inlet of the ash cooler (401) and obtain the ash inlet temperature; The fourth temperature sensor is used to detect the temperature at the location between the primary air heat exchange pipe (4011) and the water-cooled heat exchange pipe (4012) of the ash cooler (401) and to obtain the temperature of the middle part of the ash cooler. The controller is used to output a maintenance signal for the primary air heat exchange pipeline (4011) when the difference between the temperature in the middle of the ash cooler and the ash inlet temperature is less than a first preset difference; and to output a maintenance signal for the water-cooled heat exchange pipeline (4012) when the ash discharge temperature and the temperature in the middle of the ash cooler are less than a second preset difference.

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