Advanced air staged combustion denitration system of cyclone combustion boiler

Abstract

The invention discloses an advanced air staged combustion denitration system of a cyclone combustion boiler, and relates to the technical field of combustion boilers, the advanced air staged combustion denitration system comprises a boiler body, the interior of the boiler body is sequentially provided with a main combustion zone, a re-combustion reduction zone and a burnout zone along the flue gas flow direction; the combustion optimization controller is mounted on the boiler body, and a first signal output end of the combustion optimization controller is connected with the air distribution controller; the NOx / O online monitor is installed on the boiler body and arranged at an outlet of the burnout area, and the signal output end of the NOx / O online monitor is connected with the first signal input end of the combustion optimization controller. By arranging a linkage structure of the NOx / O online monitor and the combustion optimization controller, NOx and O concentration data of an outlet of a burnout area can be obtained in real time, the secondary air supply amount of a main combustion area and a recombustion reduction area can be dynamically adjusted, meanwhile, a second fluid channel of a spray gun can be switched according to monitoring data, recombustion fuel can be flexibly supplemented, and the combustion efficiency is improved. And boiler load fluctuation is effectively adapted, denitration efficiency fluctuation caused by fixed parameter operation is avoided, and it is ensured that NOx emission stably reaches the standard.

Description

Technical Field

[0001] This invention belongs to the field of combustion boiler technology, specifically, it relates to an advanced air-staged combustion and denitrification system for cyclone combustion boilers. Background Technology

[0002] Cyclone combustion boilers are widely used in industrial heating, power generation, and other fields due to their high-intensity combustion, efficient burnout, and good load regulation performance. However, in the traditional cyclone combustion process, the high-temperature and oxygen-rich environment in the furnace easily promotes the generation of large amounts of nitrogen oxides (NOx). As a major air pollutant, NOx can cause environmental problems such as acid rain and photochemical smog, seriously endangering the ecological environment and human health. Therefore, flue gas denitrification has become a key limiting factor for the widespread application of cyclone combustion boilers.

[0003] Staged air combustion technology is one of the mainstream technologies for reducing NOx emissions from boilers. Its core idea is to create a fuel-rich reduction zone in the furnace by supplying air in stages, allowing the generated NOx to be reduced and decomposed by hydrocarbons in the reduction zone. However, existing staged air combustion systems in cyclone boilers have several shortcomings: First, the air volume distribution between the main combustion zone and the reburning reduction zone is mostly fixed, and cannot be dynamically adjusted according to the real-time concentration of NOx and O2 in the flue gas, resulting in unstable denitrification efficiency and difficulty in adapting to fluctuating boiler load conditions; Second, the reducing agent spray guns in the reburning reduction zone are mostly fixed installation structures, which cannot achieve flexible adjustment of the spray position and angle, resulting in uneven mixing of the reducing agent and flue gas, and insufficient reduction reaction, which restricts the improvement of denitrification efficiency; Third, the spray guns have a single function, usually only able to spray reducing agent, and cannot supplement reburning fuel or optimize the spray effect through atomization media according to the needs of combustion conditions.

[0004] No effective solutions have yet been proposed to address the problems in the relevant technologies.

[0005] Therefore, in order to solve the above problems, the present invention provides an advanced air-staged combustion and denitrification system for cyclone combustion boilers. Summary of the Invention

[0006] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide an advanced air-staged combustion and denitrification system for cyclone combustion boilers.

[0007] The objective of this invention can be achieved through the following technical solutions: An advanced air-stage combustion and denitrification system for a cyclone combustion boiler includes: The boiler body has, in sequence, a main combustion zone, a reburning and reduction zone, and a burnout zone along the flue gas flow direction. The combustion optimization controller is installed on the boiler body, and its first signal output terminal is connected to the air volume distribution controller. The NOx / O2 online monitor is installed on the boiler body and located at the outlet of the burnout zone. Its signal output terminal is connected to the first signal input terminal of the combustion optimization controller. The main combustion zone includes a cyclone, and the secondary air inlet of the cyclone is provided with an adjustable swirl secondary air damper; the reburning reduction zone is connected to the outlet of the cyclone, and its inlet throat is provided with a reburning zone secondary air damper; the first control output terminal of the air volume distribution controller is connected to the adjustable swirl secondary air damper, and the second control output terminal is connected to the reburning zone secondary air damper. Multiple retractable multi-functional spray guns are arranged circumferentially in the transition area connecting the reburning reduction zone and the burnout zone; each spray gun is equipped with a telescopic mechanism, a swing mechanism, a first fluid channel and a second fluid channel; the second signal output terminal of the combustion optimization controller is connected to the telescopic mechanism and the swing mechanism of each spray gun respectively. The inlet of the first fluid channel is connected to the reducing agent supply system; the inlet of the second fluid channel can be selectively connected to the outlet of the reburning fuel supply system or the outlet of the atomizing medium system via a medium switching valve; and the third signal output of the combustion optimization controller is connected to the control end of the medium switching valve.

[0008] As a preferred embodiment of the present invention, the combustion optimization controller has a first preset value for NOx concentration and a second preset value for O2 concentration pre-stored in its internal storage. When the real-time data input by the NOx / O2 online monitoring instrument shows that the NOx concentration is higher than the first preset value and the O2 concentration is lower than the second preset value, the combustion optimization controller outputs a control command to the medium switching valve through its third signal output terminal, causing the valve to switch to the state of connecting to the reburning fuel supply system.

[0009] As a preferred embodiment of the present invention, the gun body axis of the telescopic multi-functional spray gun forms a downward tilt angle of 10°-45° with the horizontal direction, and the gun body axes of all the spray guns intersect at the geometric center region of the cross-section at the inlet of the burnout zone.

[0010] As a preferred embodiment of the present invention, the cross-sectional area of ​​the furnace in the reburning reduction zone is 1.5-2.5 times the cross-sectional area of ​​the cyclone outlet, and 0.4-0.6 times the cross-sectional area of ​​the furnace in the burnout zone.

[0011] As a preferred embodiment of the present invention, at least two layers of burnout air nozzles are provided on the front sidewall of the burnout zone.

[0012] As a preferred embodiment of the present invention, the vertical distance between the centers of the burnout air nozzles of two adjacent layers is adjustable, and the adjustment range is 0.8-1.2 times the hydraulic diameter of a single-layer burnout air nozzle.

[0013] As a preferred embodiment of the present invention, the nozzle of the retractable multi-functional spray gun is equipped with a temperature sensor; the signal output terminal of the temperature sensor is connected to the second signal input terminal of the combustion optimization controller to form a temperature monitoring path.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. In this invention, by setting up a linkage structure between the NOx / O2 online monitoring instrument and the combustion optimization controller, it is possible to obtain NOx and O2 concentration data at the burnout zone outlet in real time, dynamically adjust the secondary air supply to the main combustion zone and the reburning reduction zone, and switch the second fluid channel of the spray gun according to the monitoring data to flexibly supplement reburning fuel, effectively adapt to boiler load fluctuations, avoid denitrification efficiency fluctuations caused by fixed parameter operation, and ensure that NOx emissions are stably up to standard.

[0015] 2. In this invention, the telescopic multi-functional spray gun has telescopic and swing functions, which can flexibly adjust the spray position and angle. Combined with the specific tilt angle design and converging layout of the spray gun axis, the reducing agent can be evenly diffused to the transition area connecting the reburning reduction zone and the burnout zone, and fully contact and mix with the flue gas. This solves the problem of uneven mixing in fixed spray guns, significantly improves the reduction reaction efficiency, and further reduces NOx emissions.

[0016] 3. In this invention, the spray gun is equipped with a dual fluid channel, which can be selectively connected to the reburning fuel supply system or the atomizing medium system through the medium switching valve. It can not only supplement the reburning fuel to enhance the reduction reaction when needed, but also optimize the reducing agent injection effect through the atomizing medium. This solves the defect of the traditional spray gun having a single function and improves the system's adaptability to different combustion conditions.

[0017] 4. In this invention, by rationally designing the furnace cross-sectional area ratio of the reburning reduction zone, the cyclone outlet, and the burnout zone, the flue gas forms a stable flow state within the furnace, providing sufficient space and reaction time for the reduction reaction. At the same time, the burnout zone is equipped with multiple layers of burnout air nozzles with adjustable spacing between adjacent nozzles, which can dynamically optimize the burnout air supply distribution according to the flue gas volume, avoiding the problem of incomplete fuel combustion or secondary NOx generation, and achieving a synergistic improvement in combustion efficiency and denitrification effect.

[0018] 5. In this invention, a temperature sensor is installed at the nozzle of the spray gun and linked with the combustion optimization controller. This allows for real-time monitoring of temperature changes in the spray area, providing additional data support for the combustion optimization controller to adjust the spray gun's operating parameters and airflow distribution. This prevents localized temperature anomalies from affecting the reaction effect or damaging the equipment, further improving the stability and reliability of the system operation. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0020] Figure 1 This is a schematic diagram of the structure of the present invention.

[0021] Figure label: 1. Boiler body; 2. Main combustion zone; 21. Cyclone tube; 22. Cyclone secondary air damper; 3. Reburning reduction zone; 31. Reburning zone secondary air damper; 4. Combustion zone; 41. Combustion air nozzle; 5. Air volume distribution controller; 6. Retractable multi-functional spray gun; 7. Combustion optimization controller; 8. NOx / O2 online monitor. Detailed Implementation

[0022] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention: Example: Please refer to Figure 1 According to an embodiment of the present invention, an advanced air-stage combustion denitrification system for a cyclone combustion boiler includes a boiler body 1, a combustion optimization controller 7, a NOx / O2 online monitor 8, an air volume distribution controller 5, multiple retractable multi-functional spray guns 6, and related pipelines and control components.

[0023] Specifically, the boiler body 1 is equipped with a main combustion zone 2, a reburning and reduction zone 3, and a burnout zone 4 arranged sequentially along the flue gas flow direction. These zones are connected sequentially along the axial direction of the boiler body 1 to form a complete combustion and denitrification process channel. The main combustion zone 2 includes a cyclone separator 21, which is the core combustion component of the cyclone combustion boiler and is used to achieve efficient fuel combustion. An adjustable swirl secondary air damper 22 is provided at the secondary air inlet of the cyclone separator 21. The adjustable swirl secondary air damper 22 is used to adjust the secondary air flow rate and swirl intensity entering the cyclone separator 21, thereby controlling the combustion conditions of the main combustion zone 2.

[0024] Specifically, the reburning reduction zone 3 is connected below the outlet of the cyclone 21, and its inlet throat is equipped with a reburning zone secondary air damper 31. The reburning zone secondary air damper 31 is used to regulate the secondary air flow entering the reburning reduction zone 3, so that the reburning reduction zone 3 forms a fuel-rich reducing atmosphere. The cross-sectional area of ​​the furnace of the reburning reduction zone 3 is set to be 1.5-2.5 times the cross-sectional area of ​​the outlet of the cyclone 21, and 0.4-0.6 times the cross-sectional area of ​​the furnace of the burnout zone 4. This cross-sectional area ratio allows the flue gas discharged from the cyclone 21 to obtain a suitable flow rate and residence time in the reburning reduction zone 3, ensuring that the reduction reaction proceeds fully and that it smoothly transitions to the burnout zone 4.

[0025] Specifically, the front sidewall of the burnout zone 4 is provided with two or more layers of burnout air nozzles 41. The burnout air nozzles 41 are arranged along the axial direction of the boiler body 1. The vertical distance between the centers of two adjacent layers of burnout air nozzles 41 is adjustable, with an adjustment range of 0.8-1.2 times the hydraulic diameter of a single layer of burnout air nozzles 41. By adjusting the spacing between adjacent nozzles, the flue gas volume requirements under different boiler loads can be adapted to ensure that the burnout air evenly covers the flue gas area and improves the fuel combustion rate.

[0026] Specifically, the combustion optimization controller 7 is installed on the boiler body 1, and its first signal output terminal is connected to the air volume distribution controller 5 to send air volume adjustment commands to the air volume distribution controller 5. The first control output terminal of the air volume distribution controller 5 is connected to the adjustable swirl secondary air damper 22, and the second control output terminal is connected to the reburning zone secondary air damper 31. It can adjust the opening of the adjustable swirl secondary air damper 22 and the reburning zone secondary air damper 31 respectively according to the commands of the combustion optimization controller 7, so as to realize the dynamic distribution of air volume between the main combustion zone 2 and the reburning reduction zone 3.

[0027] Specifically, the NOx / O2 online monitor 8 is installed on the boiler body 1 and located at the outlet of the combustion zone 4. It is used to monitor the NOx and O2 concentrations in the flue gas discharged from the combustion zone 4 in real time. Its signal output terminal is connected to the first signal input terminal of the combustion optimization controller 7, enabling it to transmit real-time monitoring data to the combustion optimization controller 7, providing a basis for the controller's control decisions. The combustion optimization controller 7 has a first preset value for NOx concentration and a second preset value for O2 concentration pre-stored. In this embodiment, the first preset value for NOx concentration is set to 150 mg / m³, and the second preset value for O2 concentration is set to 3%.

[0028] Specifically, multiple retractable multi-functional spray guns 6 are circumferentially and evenly arranged in the transition area connecting the reburning reduction zone 3 and the burnout zone 4. Each retractable multi-functional spray gun 6 is equipped with a telescopic mechanism, a swing mechanism, a first fluid channel, and a second fluid channel. The second signal output terminal of the combustion optimization controller 7 is connected to the telescopic mechanism and swing mechanism of each spray gun, respectively, which can control the telescopic amount and swing angle of the spray gun, realizing flexible adjustment of the spray position and angle. The gun body axis of the retractable multi-functional spray gun 6 forms a downward tilt angle of 10°-45° with the horizontal direction. The gun body axes of all spray guns intersect at the geometric center area of ​​the inlet cross-section of the burnout zone 4. This design allows the medium (reducing agent, reburning fuel, or atomizing medium) sprayed by the spray gun to converge and diffuse evenly in the geometric center area, improving the mixing effect with the flue gas. Specifically, the inlet end of the first fluid channel of the retractable multi-functional spray gun 6 is connected to the reducing agent supply system for spraying denitrification reducing agents (such as ammonia water, urea solution, etc.) into the furnace; the inlet end of the second fluid channel can be selectively connected to the outlet of the reburning fuel supply system or the outlet of the atomizing medium system via a medium switching valve, wherein the reburning fuel supply system is used to provide supplementary reburning fuel (such as natural gas, pulverized coal, etc.), and the atomizing medium system is used to provide atomizing media (such as compressed air, steam, etc.). The third signal output end of the combustion optimization controller 7 is connected to the control end of the medium switching valve to control the on / off state of the medium switching valve, thereby realizing the medium switching of the second fluid channel. In addition, the nozzle of the retractable multi-functional spray gun 6 is equipped with a temperature sensor; the signal output end of the temperature sensor is connected to the second signal input end of the combustion optimization controller 7 to form a temperature monitoring path, which can monitor the furnace temperature in the nozzle area in real time and transmit the temperature data to the combustion optimization controller 7.

[0029] The working principle of an advanced air-stage combustion denitrification system for cyclone boilers is as follows: After the boiler starts up, fuel enters the cyclone 21 of the main combustion zone 2 for combustion. The combustion optimization controller 7 sends an initial control command to the air volume distribution controller 5 according to the initial load of the boiler. The air volume distribution controller 5 adjusts the initial opening of the adjustable swirl secondary air damper 22 and the reburning zone secondary air damper 31 respectively, so that the main combustion zone 2 maintains an oxygen-rich combustion state and the reburning reduction zone 3 forms an initial fuel-rich reduction atmosphere. At the same time, the combustion optimization controller 7 controls the telescopic mechanism and swing mechanism of the telescopic multi-functional spray gun 6 to adjust to the preset spray position and angle. In the initial state of the medium switching valve, the second fluid channel is connected to the atomizing medium system, the first fluid channel is opened, and the reducing agent supply system sprays the reducing agent into the furnace through the first fluid channel. The atomizing medium system provides the atomizing medium through the second fluid channel, so that the reducing agent is atomized and evenly sprayed into the transition area between the reburning reduction zone 3 and the burnout zone 4.

[0030] The NOx / O2 online monitor 8 monitors the NOx and O2 concentrations at the outlet of the burnout zone 4 in real time and continuously transmits the monitoring data to the combustion optimization controller 7; at the same time, the temperature sensor of the retractable multi-functional spray gun 6 monitors the temperature of the nozzle area in real time and transmits the temperature data to the combustion optimization controller 7.

[0031] The combustion optimization controller 7 performs comprehensive analysis on the received NOx concentration, O2 concentration, and temperature data: a) When the real-time data input by the NOx / O2 online monitor 8 shows that the NOx concentration is higher than the first preset value and the O2 concentration is lower than the second preset value, it indicates that the reducing atmosphere in the reburning reduction zone 3 is insufficient and the reducing agent reduction reaction is incomplete. At this time, the combustion optimization controller 7 outputs a control command to the medium switching valve through its third signal output terminal, causing the valve to switch to the state of connecting to the reburning fuel supply system. The second fluid channel begins to inject reburning fuel to supplement the fuel amount in the reburning reduction zone 3 and enhance the reduction reaction. At the same time, the combustion optimization controller 7 sends a command to the air volume distribution controller 5 to appropriately reduce the opening of the secondary air damper 31 in the reburning zone, further enhancing the reducing atmosphere until the NOx concentration drops below the preset value; b) When the NOx concentration is lower than the first preset value but the O2 concentration is higher than the second preset value, it indicates that the air supply in the furnace is excessive, which may lead to secondary NOx generation. The combustion optimization controller 7 reduces the opening of the adjustable swirl secondary air damper 22 and / or the reburning zone secondary air damper 31 by appropriately reducing the total air supply and optimizing the air stage ratio through the air volume distribution controller 5; c. When the temperature sensor detects that the temperature in the nozzle area is abnormally high or low, the combustion optimization controller 7 adjusts the extension and swing angle of the telescopic multi-functional spray gun 6 to change the spray gun spray position, avoid damage to the nozzle from being in a high-temperature area for a long time, and at the same time ensure that the reducing agent undergoes a reduction reaction within a suitable temperature range, thereby improving the denitrification efficiency.

[0032] After the reduction reaction in the reburning reduction zone 3, the flue gas enters the burnout zone 4. The two layers of burnout air nozzles 41 in the burnout zone 4 supply burnout air into the furnace, replenishing the oxygen required for combustion and ensuring that any unburned fuel is completely burned in the burnout zone 4. According to changes in boiler load, the center-to-center distance between adjacent layers of burnout air nozzles 41 can be adjusted to ensure uniform mixing of burnout air and flue gas, avoiding localized oxygen deficiency or excessive air supply. Finally, the fully burned and denitrified flue gas is discharged from the outlet of the burnout zone 4, completing the entire combustion and denitrification process.

[0033] Throughout the operation, the combustion optimization controller 7 continuously receives signals from various monitoring components, dynamically adjusts the air volume distribution, spray gun operating parameters, and media supply status, and realizes real-time optimization of the system's operating conditions to ensure stable denitrification efficiency, complete fuel combustion, and NOx emissions that meet standards.

[0034] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An advanced air-stage combustion and denitrification system for a cyclone combustion boiler, characterized in that, include: The boiler body (1) has a main combustion zone (2), a reburning and reduction zone (3) and a burnout zone (4) arranged sequentially along the flue gas flow direction. The combustion optimization controller (7) is installed on the boiler body (1), and its first signal output terminal is connected to the air volume distribution controller (5); The NOx / O2 online monitor (8) is installed on the boiler body (1) and located at the outlet of the burnout zone (4). Its signal output terminal is connected to the first signal input terminal of the combustion optimization controller (7). The main combustion zone (2) includes a cyclone separator (21), and an adjustable swirl secondary air damper (22) is provided at the secondary air inlet of the cyclone separator (21); the reburning reduction zone (3) is connected to the outlet of the cyclone separator (21), and a reburning zone secondary air damper (31) is provided at its inlet throat; the first control output terminal of the air volume distribution controller (5) is connected to the adjustable swirl secondary air damper (22), and the second control output terminal is connected to the reburning zone secondary air damper (31); Multiple retractable multi-functional spray guns (6) are arranged circumferentially in the transition area between the reburning reduction zone (3) and the burnout zone (4); each spray gun is equipped with a telescopic mechanism, a swing mechanism, a first fluid channel and a second fluid channel; the second signal output terminal of the combustion optimization controller (7) is connected to the telescopic mechanism and the swing mechanism of each spray gun respectively. The inlet of the first fluid channel is connected to the reducing agent supply system; the inlet of the second fluid channel can be selectively connected to the outlet of the reburning fuel supply system or the outlet of the atomizing medium system via a medium switching valve; and the third signal output of the combustion optimization controller (7) is connected to the control end of the medium switching valve.

2. The advanced air-stage combustion and denitrification system for a cyclone combustion boiler according to claim 1, characterized in that: The combustion optimization controller (7) has a first preset value for NOx concentration and a second preset value for O2 concentration stored in it. When the real-time data input by the NOx / O2 online monitor (8) shows that the NOx concentration is higher than the first preset value and the O2 concentration is lower than the second preset value, the combustion optimization controller (7) outputs a control command to the medium switching valve through its third signal output terminal, so that the valve switches to the state of connecting to the reburning fuel supply system.

3. The advanced air-stage combustion and denitrification system for a cyclone combustion boiler according to claim 1, characterized in that: The telescopic multi-functional spray gun (6) has a gun body axis that forms a downward tilt angle of 10°-45° with the horizontal direction, and the gun body axes of all the spray guns intersect at the geometric center area of ​​the inlet cross section of the burnout zone (4).

4. The advanced air-stage combustion and denitrification system for a cyclone combustion boiler according to claim 3, characterized in that: The cross-sectional area of ​​the furnace in the reburning reduction zone (3) is 1.5-2.5 times the cross-sectional area of ​​the outlet of the cyclone (21), and 0.4-0.6 times the cross-sectional area of ​​the furnace in the burnout zone (4).

5. The advanced air-stage combustion and denitrification system for a cyclone combustion boiler according to claim 1, characterized in that: At least two layers of burnout air nozzles (41) are provided on the front side wall of the burnout zone (4).

6. The advanced air-stage combustion and denitrification system for a cyclone combustion boiler according to claim 5, characterized in that: The vertical distance between the centers of the burnout air nozzles (41) of two adjacent layers is adjustable, and the adjustment range is 0.8-1.2 times the hydraulic diameter of the burnout air nozzles (41) of a single layer.

7. The advanced air-stage combustion and denitrification system for a cyclone combustion boiler according to claim 1, characterized in that: The nozzle of the retractable multi-functional spray gun (6) is equipped with a temperature sensor; the signal output terminal of the temperature sensor is connected to the second signal input terminal of the combustion optimization controller (7) to form a temperature monitoring path.

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