Circulating fluidized bed boiler air chamber and low-temperature steam collaborative denitration system and method

Abstract

The invention provides a circulating fluidized bed boiler air chamber and low-temperature steam collaborative denitration system and method.The circulating fluidized bed boiler air chamber and low-temperature steam collaborative denitration system comprises a circulating fluidized bed boiler, an economizer, an adjusting assembly and a conveying assembly, and the economizer is provided with a heat exchange circulating pipeline; the heat exchange circulating pipeline is used for introducing a circulating heat exchange medium, an inlet of the adjusting assembly is connected with an outlet of the heat exchange circulating pipeline so as to be used for introducing pressure steam into the adjusting assembly, the adjusting assembly is used for reducing the pressure of the pressure steam to 0.2-0.8 MPa and reducing the temperature to 120-180 DEG C, the conveying assembly is connected with an outlet of the adjusting assembly, and the conveying assembly is used for conveying the pressure steam into the adjusting assembly. An inlet of the conveying assembly is connected with the circulating fluidized bed boiler, and the conveying assembly is used for introducing the cooled and depressurized pressure steam into the circulating fluidized bed boiler. The air chamber and low-temperature steam collaborative denitration system of the circulating fluidized bed boiler has the advantages of stable denitration efficiency and good denitration effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of circulating fluidized bed boiler denitration, in particular to a circulating fluidized bed boiler air chamber and low-temperature steam collaborative denitration system and method. BACKGROUND

[0002] The circulating fluidized bed boiler (CFB) widely uses denitration technologies, mainly including selective catalytic reduction (SCR) denitration technology and selective non-catalytic reduction (SNCR) denitration technology. These methods have the advantages of low investment, simple equipment and process, high efficiency of removing NOx, no waste water and waste treatment, and no secondary pollution. Domestic and foreign researches show that the denitration efficiency of single SNCR process is generally 40% to 60%, the denitration efficiency of single SCR process is generally about 50% to 70%, and the mixed SNCR-SCR process can obtain higher denitration rate (more than 80% to 85%) to meet the current environmental protection emission requirements.

[0003] In the related art, in the actual application process, SNCR and SCR have strong dependence on temperature window, and the denitration efficiency is unstable due to the furnace temperature fluctuation when the load changes, and the efficiency significantly decreases at low load. Especially when the boiler is running at low load, the furnace temperature is lower than the optimal reaction window (usually 850-1100℃) of SNCR, which causes incomplete reaction of the ammonia water / urea solution sprayed into the upper part of the furnace, serious ammonia escape, and environmental pollution, air preheater blockage and ammonium bisulfate corrosion risk. SUMMARY

[0004] The present application aims to at least partially solve one of the technical problems in the related art.

[0005] To this end, the embodiments of the present application provide a circulating fluidized bed boiler air chamber and low-temperature steam collaborative denitration system and method, which has the advantages of stable denitration efficiency and good denitration effect.

[0006] The circulating fluidized bed boiler air chamber and low-temperature steam collaborative denitration system according to the embodiments of the present application comprises:

[0007] The circulating fluidized bed boiler and the economizer are connected, the economizer is provided with a heat exchange circulation pipeline, and the heat exchange circulation pipeline is used for circulating heat exchange medium;

[0008] The adjusting assembly is connected with the outlet of the heat exchange circulation pipeline, and is used for circulating pressure steam into the adjusting assembly, and the adjusting assembly is used for reducing the pressure of the pressure steam to 0.2-0.8 MPa and reducing the temperature to 120-180℃;

[0009] A conveying assembly is connected with the outlet of the adjusting assembly, the inlet of the conveying assembly is connected with the circulating fluidized bed boiler, and the conveying assembly is used for conveying the pressure-reduced and temperature-reduced pressure steam into the circulating fluidized bed boiler.

[0010] In the circulating fluidized bed boiler air chamber and low-temperature steam synergic denitration system, the circulating fluidized bed boiler air chamber and low-temperature steam synergic denitration system is adopted, the denitration condition is optimized by accurately controlling the temperature and pressure of the steam, the denitration efficiency is improved, and the risk of ammonia escape and secondary pollution is reduced.

[0011] In some embodiments, the heat exchange circulation pipeline is multiple, multiple heat exchange circulation pipelines are arranged along the flue gas flow direction in the economizer, and at least one of the multiple heat exchange circulation pipelines is connected with the adjusting assembly.

[0012] In some embodiments, the adjusting assembly comprises a pressure-reducing valve, a temperature detection part and a pressure detection part connected in sequence, the inlet of the pressure-reducing valve is connected with the outlet of the heat exchange circulation pipeline, and the pressure detection part is connected with the conveying assembly.

[0013] In some embodiments, the conveying assembly comprises a regulating valve and a check valve, and the pressure detection part, the regulating valve, the check valve and the circulating fluidized bed boiler are connected through an insulation conveying pipeline.

[0014] In some embodiments, the circulating fluidized bed comprises an air chamber and a dense phase zone of a furnace chamber arranged in sequence along the gas flow direction, and the check valve is connected with the air chamber through the insulation conveying pipeline.

[0015] In some embodiments, the extension direction of the outlet of the insulation conveying pipeline is tangentially arranged with the inner wall surface of the air chamber.

[0016] In some embodiments, an air preheater and a primary air duct are further included, the air preheater is installed on the economizer and located downstream of the heat exchange circulation pipeline, a first end of the primary air duct is connected with the air preheater, and a second end of the primary air duct is connected with the air chamber.

[0017] In some embodiments, a wind distribution plate is further included, the wind distribution plate is installed inside the circulating fluidized bed and located at the outlet of the air chamber.

[0018] The circulating fluidized bed boiler air chamber and low-temperature steam synergic denitration method utilizes the circulating fluidized bed boiler air chamber and low-temperature steam synergic denitration system in any one of the above embodiments to complete, and comprises the following steps:

[0019] Saturated steam with moderate pressure is obtained from the heat exchange circulating pipeline of the economizer;

[0020] The pressure of the saturated steam is reduced to 0.2-0.8 MPa, and the temperature is reduced to 120-180℃;

[0021] The saturated steam after pressure reduction and temperature control is delivered to the air chamber of the circulating sulfurization boiler through the heat preservation pipeline, the steam flow into the air chamber is accurately controlled, and the saturated steam is sprayed into the air chamber through the nozzle.

[0022] In some embodiments, the circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitration method of the embodiment of the present application further comprises the following steps: after the saturated steam is sprayed into the air chamber, primary air is introduced into the air chamber. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitration system of the embodiment of the present application.

[0024] Reference signs:

[0025] 10, economizer, 20, heat exchange circulating pipeline,

[0026] 1, adjusting assembly, 11, connecting pipeline, 12, pressure reducing valve, 13, temperature detection part, 14, pressure detection part,

[0027] 2, delivery assembly, 21, heat preservation delivery pipeline, 22, regulating valve, 23, check valve, 24, primary air duct, 25, air chamber,

[0028] 3, air preheater,

[0029] 4, air distribution plate,

[0030] 5, dense phase zone of the furnace, DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0032] The circulating fluidized bed boiler air chamber 25 and low-temperature steam synergistic denitration system of the embodiment of the present application will be described below according to the accompanying drawings.

[0033] As shown in the drawings, Figure 1 the circulating fluidized bed boiler air chamber 25 and low-temperature steam synergistic denitration system of the embodiment of the present application comprises: a circulating fluidized bed boiler, an economizer 10, an adjusting assembly 1 and a delivery assembly 2.

[0034] The economizer 10 is provided with a heat exchange circulation pipeline 20, which is used to pass the circulating heat exchange medium. The inlet of the adjusting assembly 1 is connected with the outlet of the heat exchange circulation pipeline 20, so as to pass the pressure steam into the adjusting assembly 1. The adjusting assembly 1 is used to reduce the pressure of the pressure steam to 0.2-0.8 MPa and reduce the temperature to 120-180℃. The delivery assembly 2 is connected with the outlet of the adjusting assembly 1, and the inlet of the delivery assembly 2 is connected with the circulating fluidized bed boiler. The delivery assembly 2 is used to pass the pressure steam after the temperature and pressure reduction into the circulating fluidized bed boiler.

[0035] Specifically, as shown in the figure, the circulating fluidized bed boiler is connected with the economizer 10, and the economizer 10 is internally provided with the heat exchange circulation pipeline 20. When the high-temperature flue gas discharged from the boiler passes through the economizer 10, the heat can be transferred to the circulating heat exchange medium in the pipeline, so as to preheat the feed water and improve the thermal efficiency of the boiler. Figure 1 The outlet of the heat exchange circulation pipeline 20 is connected with the inlet of the adjusting assembly 1, so that the low-temperature steam after the heat exchange can be introduced into the adjusting assembly 1 for further pressure and temperature adjustment. The outlet of the adjusting assembly 1 is connected with the inlet of the delivery assembly 2. The steam after the pressure and temperature reduction by the adjusting assembly 1 is sent into the circulating fluidized bed boiler through the delivery assembly 2.

[0036] It can be understood that, through the heat recovery of the economizer 10, the heat energy loss is reduced. After the preheating of the feed water, the exhaust gas temperature is reduced, and the pollution to the environment is reduced. In addition, since the flue gas temperature is high, when passing through the heat exchange circulation pipeline 20 of the economizer 10, the circulating medium (such as water) in the heat exchange circulation pipeline 20 is heated to form saturated steam with a certain pressure.

[0037] The adjusting assembly 1 can extract the saturated steam with moderate pressure in the heat exchange circulation pipeline 20 for subsequent temperature and pressure reduction operation. That is, the temperature and pressure of the pressure steam are adjusted to the range suitable for the denitration reaction (0.2-0.8 MPa, 120-180℃), which is helpful to improve the denitration efficiency. Moreover, through the accurate control of the temperature and pressure by the adjusting assembly 1, the incomplete reaction of the ammonia water / urea solution during the low-load operation can be reduced, and the ammonia escape phenomenon can be reduced.

[0038] It should be noted that the delivery assembly 2 can adopt a pipeline with certain heat preservation function to deliver the saturated steam after the temperature and pressure reduction, so as to avoid that the gas pressure and temperature of the saturated steam change too much during the delivery process, which affects the subsequent use.

[0039]

[0040] ​In other words, in the circulating fluidized bed boiler air chamber 25 and low-temperature steam co-denitrification system of this embodiment of the invention, the circulating fluidized bed boiler air chamber 25 and low-temperature steam co-denitrification system optimize the denitrification conditions and improve the denitrification efficiency by precisely controlling the temperature and pressure of the steam, while reducing the risk of ammonia escape and secondary pollution.

[0041] In some embodiments, there are multiple heat exchange circulation pipes 20, which are arranged at intervals along the flue gas flow direction in the economizer 10, and at least one of the multiple heat exchange circulation pipes 20 is connected to the regulating component 1.

[0042] Understandably, the arrangement of multiple pipelines helps to achieve a uniform distribution of heat within the economizer 10, preventing local overheating or insufficient heat, and ensuring the uniformity of heat exchange throughout the economizer 10. Furthermore, at least one heat exchange circulation pipeline 20 is connected to the regulating component 1, allowing for independent adjustment of the circulating medium in one or more heat exchange circulation pipelines 20 according to the boiler operating status and denitrification requirements, thereby achieving more precise temperature and pressure control.

[0043] In other words, local regulation can be achieved without disrupting the entire circulation system by adjusting the flow rate and temperature of the medium in the pipeline connected to the regulating component 1 without affecting other pipelines.

[0044] In some embodiments, the regulating assembly 1 includes a pressure reducing valve 12, a temperature detection unit 13, and a pressure detection unit 14 connected in sequence. The inlet of the pressure reducing valve 12 is connected to the outlet of the heat exchange circulation pipeline 20, and the pressure detection unit 14 is connected to the delivery assembly 2.

[0045] Understandably, the inlet of the pressure reducing valve 12 is connected to the outlet of the heat exchange circulation pipeline 20 via the connecting pipe 11, and its function is to reduce the steam pressure to the required range (0.2~0.8MPa). The pressure reducing valve 12 can automatically or manually adjust the steam pressure according to the boiler's operating status and the needs of the denitrification system, ensuring that the steam pressure entering the boiler meets the optimal conditions for the denitrification reaction.

[0046] The temperature detection unit 13 is located after the pressure reducing valve 12 and is used to monitor the temperature of the regulated steam in real time. The temperature detection unit 13 can feed back the monitored temperature data to the control system, which adjusts the opening of the pressure reducing valve 12 or other adjustment methods based on this data to maintain the steam temperature within the optimal denitrification reaction range (120-180°C).

[0047] The pressure detection unit 14 is connected between the conveying assembly 2 and the temperature detection unit 13, and is used to monitor the steam pressure entering the boiler. The pressure detection unit 14 can also feed back the monitored pressure data to the control system to achieve further monitoring and regulation of the steam pressure.

[0048] In other words, the pressure reducing valve 12 ensures that the steam pressure is suitable for the denitrification reaction, avoiding the adverse effects of excessive pressure on denitrification efficiency. The temperature detection unit 13, by reducing the steam pressure, can correspondingly reduce the steam temperature to meet the temperature requirements of the denitrification reaction. This achieves precise control of the steam temperature, ensuring the denitrification reaction proceeds under optimal temperature conditions. It also responds promptly to temperature changes, preventing a decrease in denitrification efficiency due to temperature fluctuations. The pressure detection unit 14 ensures stable steam pressure delivered to the boiler, avoiding the impact of pressure fluctuations on the denitrification effect. The auxiliary temperature detection unit 13 ensures that both the steam pressure and temperature are within their optimal operating range.

[0049] It should be noted that the temperature detection unit 13 can be a thermometer, and the pressure detection unit 14 can be a pressure gauge.

[0050] In some embodiments, the conveying assembly 2 includes a regulating valve 22 and a check valve 23. The pressure detection unit 14, the regulating valve 22, the check valve 23, and the circulating fluidized bed boiler are all connected through an insulated conveying pipeline 21.

[0051] It is understandable that, such as Figure 1 As shown, the regulating valve 22 is located after the pressure detection unit 14 and is connected to the delivery pipeline. The regulating valve 22 adjusts the steam flow rate entering the circulating fluidized bed boiler based on the data provided by the pressure detection unit 14 and the requirements of the denitrification system. By adjusting the opening degree of the regulating valve 22, the steam flow rate can be precisely controlled to adapt to the boiler operating conditions and denitrification efficiency requirements.

[0052] The check valve 23 is located after the regulating valve 22 and connected to the circulating fluidized bed boiler. Its function is to prevent steam backflow and ensure that steam can only flow into the boiler in one direction. The check valve 23 is crucial for preventing the pressure inside the boiler from acting in reverse on the regulating valve 22 and the pressure detection unit 14, thus protecting the safe operation of the system.

[0053] Understandably, regulating valve 22 ensures that the steam flow matches the boiler's denitrification requirements, optimizing the denitrification effect and improving the system's response speed and regulation accuracy. Check valve 23 prevents steam backflow, protecting the system from reverse pressure and enhancing system safety and reliability.

[0054] In some embodiments, the circulating fluidized bed includes a wind chamber 25 and a dense phase zone 5 of the furnace arranged sequentially along the gas flow direction, and a check valve 23 is connected to the wind chamber 25 through an insulated conveying pipe 21.

[0055] Understandably, the air chamber 25 is located at the bottom of the circulating fluidized bed boiler and is used to distribute air or other mixed gases entering the furnace. The dense phase zone 5 of the furnace is a region within the furnace where the bed material is at a high concentration, and it is where combustion and denitrification reactions mainly occur.

[0056] Check valve 23 is connected to air chamber 25 via insulated conveying pipe 21, ensuring that steam can only flow into air chamber 25 in one direction, preventing materials or gas in the boiler from flowing back into the conveying pipe. The installation of check valve 23 is crucial for maintaining stable internal pressure and system safety in the boiler.

[0057] In other words, the sequential arrangement of the air chamber 25 and the dense phase zone 5 in the furnace helps optimize the gas-solid two-phase flow, improving combustion efficiency and denitrification effect. The check valve 23 prevents material or gas in the furnace from flowing back into the conveying pipeline during pressure fluctuations, protecting the integrity of the pipeline and system. By preventing backflow, the check valve 23 reduces the risk of equipment damage and personal injury that may be caused by backflow. The insulated conveying pipeline 21 reduces heat loss during the conveying process, helping to maintain the temperature and pressure of the steam and ensuring that the denitrification reaction proceeds under optimal conditions.

[0058] Preferably, the outlet of the insulated conveying pipe 21 extends tangentially to the inner wall of the air chamber 25.

[0059] Understandably, the outlet direction of the insulated conveying pipe 21 is arranged tangentially to the inner wall of the air chamber 25, so that when steam or mixed gas is ejected from the pipe outlet, its flow direction is tangential to the inner wall of the air chamber 25. This arrangement helps the steam or gas to be evenly distributed in the air chamber 25, avoids direct impact on the inner wall of the air chamber 25, and reduces wear on the inner wall of the air chamber 25.

[0060] In other words, because the flow direction of steam or gas is tangential to the inner wall surface of the air chamber 25, the direct impact of high-speed fluid on the inner wall of the air chamber 25 is reduced, thereby lowering the wear rate of the inner wall of the air chamber 25. This helps to extend the service life of the inner wall of the air chamber 25 and reduce the frequency and cost of maintenance and replacement of the inner wall of the air chamber 25.

[0061] In some embodiments, the system further includes an air preheater 3 and a primary air duct 24. The air preheater 3 is installed on the economizer 10 and is located downstream of the heat exchange circulation pipeline 20. The first end of the primary air duct 24 is connected to the air preheater 3, and the second end of the primary air duct 24 is connected to the air chamber 25.

[0062] It is understandable that, such as Figure 1 As shown, the air preheater 3 is installed above the economizer 10 and downstream of the heat exchange circulation pipeline 20, so that the heat-exchanged medium continues to flow to the air preheater 3 after passing through the economizer 10, further recovering heat from the flue gas. The first port of the primary air duct 24 is connected to the air preheater 3, allowing preheated air to flow from the air preheater 3 into the primary air duct 24. The second port of the primary air duct 24 is connected to the air chamber 25, allowing preheated air to enter the air chamber 25 through the primary air duct 24, providing the necessary oxygen for combustion in the circulating fluidized bed boiler.

[0063] In some embodiments, an air distribution plate 4 is also included, which is installed inside the circulating fluidized bed and located at the outlet of the air chamber 25.

[0064] It is understandable that, such as Figure 1 As shown, the air distribution plate 4 is located at the outlet of the air chamber 25. The function of the air distribution plate 4 is to evenly distribute the air entering the furnace at the outlet of the air chamber 25, ensuring that the bed material is evenly fluidized in the furnace and improving the combustion efficiency.

[0065] The air distribution plate 4 typically consists of multiple evenly distributed small holes, which distribute air evenly to the bottom of the furnace. The installation position and design of the air distribution plate 4 are crucial for ensuring uniform fluidization of the bed material, thus ensuring good mixing and combustion of the bed material.

[0066] In other words, the air distribution plate 4 can evenly distribute air, ensuring uniform fluidization of the bed material within the furnace, thereby improving combustion efficiency. The uniform distribution of the air distribution plate 4 optimizes the combustion process, reduces losses from incomplete combustion, and improves the boiler's thermal efficiency. Uniform combustion helps reduce pollutant emissions due to incomplete combustion, improving the boiler's environmental performance. The uniform distribution of the air distribution plate 4 also helps improve system stability, reducing combustion fluctuations caused by uneven bed material distribution.

[0067] It should be noted that saturated steam at a suitable pressure is obtained from the outlet of the circulating heat exchange pipeline. The steam pressure is reduced to 0.2–0.8 MPa and the temperature to 120–180℃ through the pressure reducing valve 12. The low-temperature saturated steam after pressure reduction and temperature control is transported to the vicinity of the air chamber 25 through the insulated conveying pipeline 21. The steam flow rate entering the air chamber 25 is precisely controlled by the regulating valve 22. The low-temperature saturated steam is injected into the air chamber 25 through corrosion-resistant steam nozzles (such as 316L stainless steel) arranged in a ring on the side wall or bottom of the air chamber 25. The nozzles are designed to be inclined upwards or tangentially to promote thorough mixing of steam and primary air.

[0068] Low-temperature steam is mixed with primary air, increasing the temperature of the primary air entering the furnace (especially when the primary air temperature is low under low load) and significantly increasing the humidity (water (H2O) content) of the primary air. The primary air with increased temperature and humidity enters the dense phase zone at the bottom of the furnace through the air distribution plate 4. In the high-temperature reducing atmosphere at the bottom of the furnace, water (H2O) molecules in the steam react with reducing substances such as carbon monoxide (CO) and hydrocarbons (CHx) in the flue gas to generate active hydroxyl (OH) radicals and hydrogen (H) radicals, which promote the reduction of nitrogen oxides (NOx) to nitrogen (N2). At the same time, OH radicals can also activate ammonia molecules (NH3) or promote the formation of intermediate products, thereby increasing the SNCR reaction rate and the reduction efficiency of nitrogen oxides (NOx).

[0069] The following describes a method for synergistic denitrification of a circulating fluidized bed boiler air chamber and low-temperature steam, according to an embodiment of the present invention.

[0070] The circulating fluidized bed boiler air chamber and low-temperature steam co-processing denitrification method of this invention is completed using any of the circulating fluidized bed boiler air chamber and low-temperature steam co-processing denitrification systems in the above embodiments, and includes the following steps:

[0071] Saturated steam at a suitable pressure is obtained from the economizer's heat exchange circulation pipes. This means that the heat exchange circulation pipes in the economizer are used to recover heat from the boiler flue gas, heat the feedwater through heat exchange, and simultaneously generate saturated steam.

[0072] The pressure of the saturated steam is reduced to 0.2–0.8 MPa, and the temperature is reduced to 120–180°C. It is understandable that reducing the pressure of the obtained saturated steam to 0.2–0.8 MPa and the temperature to 120–180°C can be achieved using a pressure reducing valve and a temperature detection unit. The pressure reducing valve is used to lower the steam pressure, while the temperature detection unit is used to monitor and control the steam temperature to ensure it remains within the optimal temperature range for the denitrification reaction.

[0073] Saturated steam, after pressure reduction and temperature control, is transported to the air chamber of the circulating vulcanizing boiler through insulated pipes. The steam flow rate entering the air chamber is precisely controlled, and the saturated steam is injected into the air chamber through nozzles.

[0074] Understandably, the saturated steam, after pressure reduction and temperature control, is transported to the air chamber of the circulating fluidized bed boiler via insulated pipes. The design of the insulated pipes helps reduce heat loss during steam transport, maintaining its temperature and pressure.

[0075] In the air chamber, the steam flow rate entering the air chamber is precisely controlled by a regulating valve. The opening degree of the regulating valve can be adjusted according to the boiler's operating status and denitrification requirements to ensure that the steam flow rate matches the needs of the denitrification reaction.

[0076] Saturated steam, after pressure reduction and temperature control, is injected into the air chamber through nozzles. The design and arrangement of the nozzles should ensure that the steam is evenly distributed within the air chamber and fully mixed with the bed material to achieve the best denitrification effect.

[0077] In some embodiments, the circulating fluidized bed boiler air chamber and low-temperature steam co-denitrification method of the present invention further includes the following steps: after injecting saturated steam into the air chamber, primary air is introduced into the air chamber.

[0078] Understandably, after the saturated steam, after pressure reduction and temperature control, is injected into the air chamber, primary air is introduced into the air chamber through the primary air duct. Optionally, the source of the primary air can be preheated gas in the air preheater at the tail end of the economizer. The primary air can provide the necessary oxygen for combustion and help maintain the fluidization state of the bed material.

[0079] In other words, primary air mixes with the bed material to help maintain its fluidized state, ensuring uniform distribution within the furnace and improving combustion efficiency. Primary air provides oxygen to support the combustion reaction, ensuring complete combustion of fuel and reducing unburned losses.

[0080] Therefore, the synergistic effect of primary air and saturated steam in the air chamber helps improve the denitrification effect. The water vapor in the saturated steam can react with nitrogen oxides (NOx) in the flue gas, while the oxygen provided by the primary air promotes these reactions. This synergistic effect also helps achieve higher denitrification efficiency, reduce NOx emissions, and meet environmental protection requirements.

[0081] Furthermore, by precisely controlling the flow rate and temperature of the primary air, the combustion and denitrification processes can be optimized. The flow rate and temperature of the primary air can be adjusted according to the boiler's operating status and denitrification requirements to ensure optimal combustion and denitrification performance.

[0082] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0083] Furthermore, 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 at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0084] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0085] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0086] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0087] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system, characterized in that, include: A circulating fluidized bed boiler and an economizer are connected together. The economizer is provided with a heat exchange circulation pipeline for introducing a circulating heat exchange medium. A regulating component, the inlet of which is connected to the outlet of the heat exchange circulation pipeline, is used to introduce pressurized steam into the regulating component, the regulating component being used to reduce the pressure of the pressurized steam to 0.2-0.8 MPa and the temperature to 120-180°C; The conveying assembly is connected to the outlet of the regulating assembly and the inlet of the conveying assembly is connected to the circulating fluidized bed boiler. The conveying assembly is used to introduce the cooled and depressurized pressurized steam into the circulating fluidized bed boiler.

2. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 1, characterized in that, There are multiple heat exchange circulation pipelines, which are arranged at intervals along the flue gas flow direction in the economizer, and at least one of the multiple heat exchange circulation pipelines is connected to the regulating component.

3. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 2, characterized in that, The regulating assembly includes a pressure reducing valve, a temperature detection unit, and a pressure detection unit connected in sequence. The inlet of the pressure reducing valve is connected to the outlet of the heat exchange circulation pipeline, and the pressure detection unit is connected to the conveying assembly.

4. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 3, characterized in that, The conveying assembly includes a regulating valve and a check valve. The pressure detection unit, the regulating valve, the check valve, and the circulating fluidized bed boiler are all connected through an insulated conveying pipeline.

5. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 4, characterized in that, The circulating fluidized bed includes a wind chamber and a dense phase zone of the furnace arranged sequentially along the gas flow direction, and the check valve is connected to the wind chamber through the insulated conveying pipeline.

6. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 5, characterized in that, The outlet of the insulated conveying pipe extends tangentially to the inner wall of the air chamber.

7. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 6, characterized in that, It also includes an air preheater and a primary air duct. The air preheater is installed on the economizer and located downstream of the heat exchange circulation pipeline. The first end of the primary air duct is connected to the air preheater, and the second end of the primary air duct is connected to the air chamber.

8. The circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system according to claim 7, characterized in that, It also includes an air distribution plate, which is installed inside the circulating fluidized bed and located at the outlet of the air chamber.

9. A method for synergistic denitrification of a circulating fluidized bed boiler air chamber and low-temperature steam, wherein the method is implemented using the circulating fluidized bed boiler air chamber and low-temperature steam synergistic denitrification system as described in any one of claims 1-8, characterized in that, Includes the following steps: Saturated steam at a suitable pressure is obtained from the heat exchange circulation pipeline of the economizer; Reduce the pressure of the saturated steam to 0.2–0.8 MPa and the temperature to 120–180 °C; Saturated steam, after pressure reduction and temperature control, is transported to the air chamber of the circulating vulcanizing boiler through insulated pipes. The steam flow rate entering the air chamber is precisely controlled, and the saturated steam is injected into the air chamber through nozzles.

10. The method for synergistic denitrification of a circulating fluidized bed boiler air chamber and low-temperature steam according to claim 9, characterized in that, It also includes the following steps: after injecting the saturated steam into the air chamber, primary air is introduced into the air chamber.

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