A kind of structure for the environmental protection reconstruction of SCR denitration of water fire tube industrial boiler

Abstract

The utility model relates to a kind of to water fire tube industrial boiler carries out the structure of SCR denitration environmental protection reconstruction. It is related to water fire tube industrial boiler field. The existing water fire tube boiler body is small, and temperature rises fast, usually without the space suitable for SCR denitration, which affects the ability of boiler to achieve ultra-low emission. The utility model includes threaded flue and smoke plug device, threaded flue and smoke plug device connection, smoke plug device is closed threaded flue at the front end of boiler shell flue inlet;Water fire tube industrial boiler also includes high-temperature flue gas supplement flue, high-temperature flue gas regulating door and non-metal expansion joint, high-temperature flue gas supplement flue is installed in the rear wall of boiler body and SCR reactor inlet flue, high-temperature flue gas supplement flue is connected with high-temperature flue gas regulating door and non-metal expansion joint respectively;Water fire tube industrial boiler also includes economizer, economizer is connected with SCR reactor, and economizer is arranged below SCR reactor. The utility model is applied to the field of SCR denitration of water fire tube industrial boiler.

Description

Technical Field

[0001] This utility model relates to the field of industrial boiler denitrification and emission control, specifically to a structure for SCR denitrification and environmental protection retrofit of water-fire tube industrial boilers. Background Technology

[0002] Nitrogen oxides, one of the three major pollutants emitted from industrial boilers, seriously threaten air quality and human health. To effectively curb pollution, the national and provincial governments have successively issued a series of strict mandatory standards for boiler pollutant emission limits. Among these, industrial boilers with a capacity of 40 tons or more are required to comply with stringent ultra-low emission limits: under a baseline oxygen content of 6%, the emission concentrations of particulate matter, sulfur dioxide, and nitrogen oxides must not exceed 10, 35, and 50 mg / m³, respectively. This standard significantly raises the environmental threshold for industrial boilers, aiming to promote the industry's transformation towards a green and low-carbon direction.

[0003] Currently, water-tube and fire-tube boilers occupy a high proportion of use in the heating sector and industrial production enterprises due to their small boiler size and rapid heating. Using threaded smoke tubes as the main heating surface, they effectively improve heat exchange efficiency. However, these compact boiler bodies typically lack suitable space for SCR (Selective Catalytic Reduction) denitrification, making it difficult to install SCR denitrification equipment. As the current mainstream technology for efficiently removing nitrogen oxides, the lack of suitable space for SCR denitrification significantly limits the ability of these boilers to achieve ultra-low emission standards for pollutants such as nitrogen oxides, thus increasing the emission of air pollutants. Utility Model Content

[0004] This invention addresses the problem that existing water-tube and fire-tube boilers are small in size and heat up quickly, often lacking suitable space for SCR denitrification, which affects their ability to achieve ultra-low emissions and increases air pollutant emissions. Therefore, it provides a structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers.

[0005] The technical solution of this utility model is:

[0006] A structure for SCR denitrification environmental protection retrofit of a water-fire tube industrial boiler, comprising: a boiler body and an SCR reactor, wherein the boiler body is connected to the SCR reactor through an inlet flue of the SCR reactor; the boiler body also includes a threaded flue and a set of flue plug devices, wherein the threaded flue and the set of flue plug devices are connected, and the set of flue plug devices seals a portion of the threaded flue near the inlet of the flue near the front end of the boiler shell.

[0007] The water-tube and fire-tube industrial boiler also includes a high-temperature flue gas supply flue, a high-temperature flue gas regulating valve, and a non-metallic expansion joint. A high-temperature flue gas supply flue is installed on the rear wall of the boiler body and the inlet flue of the SCR reactor. The high-temperature flue gas supply flue is connected to the high-temperature flue gas regulating valve and the non-metallic expansion joint respectively.

[0008] The water-tube industrial boiler also includes an economizer, which is connected to the SCR reactor and is located below the SCR reactor.

[0009] Furthermore, the cigarette plug device includes a plug plate and an insert plate;

[0010] The blocking plate and the insert plate are vertically welded together. The insert plate is located in the middle of the blocking plate and is inserted into the end of the threaded smoke pipe. The blocking plate is located outside the threaded smoke pipe and blocks the smoke from entering the threaded smoke pipe.

[0011] Furthermore, the diameter of the blocking plate is larger than the outer diameter of the threaded smoke pipe, completely sealing the opening of the threaded smoke pipe. The insert plate is a rectangular steel plate, and the inner diameter of the threaded smoke pipe is close to the long side of the insert plate.

[0012] Furthermore, the high-temperature flue gas supplementary flue is located in the middle area between the boiler body and the SCR reactor inlet flue. The high-temperature flue gas regulating valve on the high-temperature flue gas supplementary flue is installed on the side near the rear wall of the boiler body, and the non-metallic expansion joint is installed on the side near the SCR reactor inlet flue.

[0013] Furthermore, the opening degree of the high-temperature flue gas regulating valve is adjusted by the change in flue gas temperature after mixing.

[0014] Furthermore, the economizer includes a high-temperature economizer and a low-temperature economizer;

[0015] The high-temperature economizer is connected to the low-temperature economizer via a connecting flue. The high-temperature economizer and the low-temperature economizer are respectively installed below the SCR reactor, and the high-temperature economizer is installed above the low-temperature economizer.

[0016] Furthermore, the SCR reactor shares the same supporting steel frame with the high-temperature economizer and the low-temperature economizer, respectively. The upper end of the connecting flue is connected to the outlet of the SCR reactor, and the lower end is connected to the inlet of the high-temperature economizer.

[0017] Furthermore, the high-temperature economizer and the low-temperature economizer are connected by a steel connecting flue, and the high-temperature economizer and the low-temperature economizer supplement the heating area of ​​the threaded flue at the front end, which is blocked by the flue plug device.

[0018] Furthermore, the water circulation of the high-temperature economizer and the low-temperature economizer is connected in parallel with the boiler body, and the supply and return water pipes of the economizer are directly connected to the main system pipe.

[0019] Furthermore, the lower part of the threaded smoke pipe is an airfoil-shaped flue.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] This invention involves appropriate adjustments to a water-tube boiler without damaging its original main structure or affecting the boiler's water circulation and structural safety. The modifications create a space and reaction temperature range suitable for SCR denitrification. Employing the SCR denitrification process and using a 40% urea solution as the denitrification reducing agent, the boiler operates safely under various load conditions, achieving ultra-low emissions. By modifying the constrained structure of the boiler body, it allows for the adoption of a mature selective catalytic reduction (SCR) denitrification process, thereby meeting the boiler's ultra-low emission requirements.

[0022] This invention utilizes a smoke plug device to seal the threaded smoke tubes of a large water-tube boiler at a certain ratio. Without damaging the main structure of the boiler's convection smoke tubes during the sealing process, it enables the water-tube boiler to use SCR technology for the treatment of nitrogen oxides in flue gas.

[0023] This invention ensures stable SCR operation under various load conditions by using a high-temperature flue gas regulating damper installed on the rear wall of the boiler furnace. The non-metallic expansion joint absorbs the expansion of the high-temperature flue due to temperature changes, thus ensuring stable SCR operation under various load conditions.

[0024] This invention adds an economizer at the rear of the SCR reactor, which is equivalent to supplementing the heat-receiving area of ​​the shielded threaded flue tubes, further reducing the exhaust gas temperature and improving boiler thermal efficiency. Ultimately, it effectively controls and enables large industrial boilers, such as those with a large market share of water-fire tube boilers and relatively outdated technologies, to fully meet the national standards for ultra-low emissions of boiler pollutants. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of this utility model;

[0026] Figure 2 yes Figure 1 A magnified view of part A in the middle;

[0027] Figure 3 This is a schematic diagram showing the connection between the smoke plug device and the threaded smoke pipe;

[0028] Figure 4 yes Figure 3 A magnified view of part B in the image;

[0029] Figure 5 This is a schematic diagram of the structure when the smoke plug device is inserted into the threaded smoke pipe;

[0030] Figure 6 yes Figure 5 Side view;

[0031] Figure 7 This is a schematic diagram of the layout of the economizer and SCR reactor;

[0032] Figure 8 This is a schematic diagram of the flue gas flow path;

[0033] In the diagram: 1. Boiler body, 2. Smoke plug device, 3. Threaded smoke pipe, 4. SCR reactor inlet flue, 5. High-temperature flue gas supplement flue, 6. High-temperature flue gas regulating valve, 7. Non-metallic expansion joint, 8. SCR reactor, 9. Economizer, 10. Connecting flue, 11. Airfoil flue.

[0034] 21. Blocking plate; 22. Insert plate;

[0035] 91. High temperature economizer, 92. Low temperature economizer. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate this utility model, but are not intended to limit the scope of this utility model.

[0037] Specific implementation method one: Combining Figure 1 This embodiment describes a structure for SCR denitrification environmental retrofitting of a water-fire tube industrial boiler. The structure includes a boiler body 1 and an SCR reactor 8. The boiler body 1 is connected to the SCR reactor 8 through an SCR reactor inlet flue 4. The boiler body 1 also includes a threaded flue 3 and a set of flue plug devices 2. The threaded flue 3 and the set of flue plug devices 2 are connected, and the set of flue plug devices 2 blocks part of the threaded flue 3 near the flue inlet at the front end of the boiler shell.

[0038] The water-fire tube industrial boiler also includes a high-temperature flue gas supply flue 5, a high-temperature flue gas regulating valve 6, and a non-metallic expansion joint 7. The high-temperature flue gas supply flue 5 is installed on the rear wall of the boiler body 1 and the inlet flue 4 of the SCR reactor. The high-temperature flue gas supply flue 5 is connected to the high-temperature flue gas regulating valve 6 and the non-metallic expansion joint 7 respectively.

[0039] The water-tube industrial boiler also includes an economizer 9, which is connected to the SCR reactor 8 and is located below the SCR reactor 8.

[0040] Specific Implementation Method Two: Combining Figure 2This embodiment describes a structure for SCR denitrification environmental protection retrofit of a water-tube and fire-tube industrial boiler. The high-temperature flue gas supplementary flue 5 is located in the middle area between the boiler body 1 and the SCR reactor inlet flue 4. The high-temperature flue gas regulating valve 6 on the high-temperature flue gas supplementary flue 5 is installed on one side near the rear wall of the boiler body 1, and the non-metallic expansion joint 7 is installed on one side near the SCR reactor inlet flue 4.

[0041] When the denitrification flue gas temperature is insufficient under low load, a high-temperature flue gas regulating valve 6 and a high-temperature flue gas supplementary flue 5 are installed in the middle of the rear wall of the boiler body 1. Here, the high-temperature flue gas has passed through the furnace and partition wall but has not yet entered the airfoil flue 11. The resistance of the high-temperature bypass flue is small, and it can be drawn out and mixed with the flue gas discharged through the threaded flue 3 when the denitrification flue gas temperature is insufficient to improve the denitrification flue gas temperature.

[0042] Specific implementation method three: Combining Figure 2 This embodiment describes a structure for SCR denitrification environmental protection retrofit of a water-tube and fire-tube industrial boiler, wherein the opening of the high-temperature flue gas regulating valve 6 is adjusted by the change in flue gas temperature after mixing.

[0043] When the boiler is under low load and the flue gas temperature is low, and the flue gas temperature discharged through the threaded flue pipe 3 of the boiler body 1 does not reach the flue gas temperature required for denitrification, the high-temperature flue gas regulating valve 6 of the high-temperature flue gas supplement flue 5 needs to be opened to extract some of the higher-temperature flue gas in the furnace in advance and mix it with the flue gas discharged from the main flue pipe to reach the temperature range of 320-420℃ required for denitrification. The opening degree of the high-temperature flue gas regulating valve 6 is adjusted according to the change in flue gas temperature after mixing. When the boiler load increases and the flue gas temperature of the threaded flue pipe 3 of the boiler body 1 reaches the denitrification temperature, the high-temperature flue gas regulating valve 6 can be closed. All the flue gas in the furnace enters the denitrification SCR reactor inlet flue 4 of the SCR reactor 8 after heat exchange through the flue pipe. At the same time, the non-metallic expansion joint 7 plays the role of absorbing the expansion of the flue length due to temperature changes, ensuring that the SCR can still operate stably under various load conditions.

[0044] Specific implementation method four: Combination Figure 3 — Figure 6 This embodiment describes a structure for SCR denitrification environmental protection retrofit of a water-fire tube industrial boiler. The smoke plug device 2 includes a plug plate 21 and an insert plate 22.

[0045] The blocking plate 21 and the insert plate 22 are vertically welded together. The insert plate 22 is located in the middle of the blocking plate 21 and is inserted into the end of the threaded smoke pipe 3. The blocking plate 21 is located outside the threaded smoke pipe 3 and blocks the smoke from entering the threaded smoke pipe 3.

[0046] The above-described structure is used to perform thermal verification calculations on the main heating surface of the boiler body 1, the threaded smoke tubes. Based on the load parameters, the effective area of ​​the threaded smoke tubes required to meet the denitrification window temperature of 320-420℃ is determined. At the smoke tube inlet at the front end of the boiler shell, the threaded smoke tubes 3 are selectively blocked in a certain proportion. The blocking of the threaded smoke tubes 3 uses a smoke plug device 2, which is welded from heat-resistant steel plates and inserted into the end of the threaded smoke tube 3 to prevent flue gas from entering the tube. After blocking, the flue gas velocity in the remaining threaded smoke tube 3 is relatively increased, but it must still be maintained at the standard upper limit under full load to avoid wear on the tube. The higher flue gas velocity also prevents ash accumulation inside the tube. After blocking, the heat absorption of the heating surface of the threaded smoke tube is greatly reduced, and the exhaust flue gas temperature is controlled within the range of 260-350℃, approaching or reaching the denitrification window temperature.

[0047] Specific Implementation Method Five: Combining Figure 3 — Figure 6 This embodiment describes a structure for SCR denitrification environmental retrofitting of a water-fire tube industrial boiler. The diameter of the blocking plate 21 is larger than the outer diameter of the threaded smoke pipe 3, completely sealing the opening of the threaded smoke pipe 3. The insert plate 22 is a rectangular steel plate, and the inner diameter of the threaded smoke pipe 3 is close to the long side of the insert plate 22.

[0048] The threaded flue tubes 3 of a large water-tube boiler are plugged with smoke plugs at a certain ratio, ranging from 30% to 40%. Assuming a specific plugging ratio, the flue gas temperature after passing through the effective flue tubes under full-load conditions is calculated to be within the SCR denitrification temperature range, and the flue gas velocity within the flue tubes meets safe flow velocity requirements. This achieves flue gas nitrogen oxide treatment using SCR technology in a water-tube boiler without damaging the main structure of the threaded flue tubes 3.

[0049] Specific Implementation Method Six: Combination Figure 7 This embodiment describes a structure for SCR denitrification environmental protection retrofit of a water-tube and fire-tube industrial boiler, wherein the economizer 9 includes a high-temperature economizer 91 and a low-temperature economizer 92.

[0050] The high-temperature economizer 91 is connected to the low-temperature economizer 92 via the connecting flue 10. The high-temperature economizer 91 and the low-temperature economizer 92 are respectively installed below the SCR reactor 8, and the high-temperature economizer 91 is installed above the low-temperature economizer 92.

[0051] Specific implementation method seven: Combining Figure 7 This embodiment describes a structure for SCR denitrification environmental retrofitting of a water-tube and fire-tube industrial boiler. The SCR reactor 8 shares the same supporting steel frame with the high-temperature economizer 91 and the low-temperature economizer 92 below. The upper end of the connecting flue 10 is connected to the outlet of the SCR reactor 8, and the lower end of the connecting flue 10 is connected to the inlet of the high-temperature economizer 91.

[0052] Because part of the heating surface of the threaded smoke tube 3 was blocked, the exhaust gas temperature of the boiler body 1 was high and uneconomical. Therefore, after SCR denitrification, the heating surface of the economizer 9 was added to make the exhaust gas temperature reach the overall economical exhaust gas effect of the boiler and ensure the overall thermal efficiency of the boiler.

[0053] Specific implementation method eight: Combination Figure 7 This embodiment describes a structure for SCR denitrification environmental protection retrofit of a water-fire tube industrial boiler. The high-temperature economizer 91 and the low-temperature economizer 92 are connected by a steel connecting flue 10. The high-temperature economizer 91 and the low-temperature economizer 92 supplement the heating area of ​​the threaded flue 3 at the front end, which is blocked by the flue plug device 2.

[0054] The high-temperature economizer 91 and the low-temperature economizer 92 effectively supplement the heating area of ​​the front-end shielded threaded flue tubes. Before the modification, the exhaust temperature of the threaded flue tube 3 was approximately 150℃, which was the boiler exhaust temperature. After the modification, due to the shielding of the threaded flue tube 3, the exhaust temperature of the threaded flue tube 3 reached over 320℃, the denitrification temperature. Therefore, economizer 9 needs to be installed after denitrification to further reduce the flue gas temperature and improve the overall thermal efficiency of the boiler. Ultimately, this effectively controls and enables large industrial boilers, such as those with a large proportion of water-fire tube systems and relatively outdated original technologies, to fully meet the national standards for ultra-low emissions of boiler pollutants.

[0055] Specific Implementation Method Nine: Combining Figure 7 This embodiment describes a structure for SCR denitrification environmental retrofitting of a water-fire tube industrial boiler. The water circulation of the high-temperature economizer 91 and the low-temperature economizer 92 is connected in parallel with the boiler body 1. The supply and return water pipes of the economizer 9 are directly connected to the main system pipe, thus not affecting the safety of the boiler's water circulation.

[0056] Specific Implementation Method Ten: Combining Figure 1 — Figure 8 This embodiment describes a structure for SCR denitrification environmental protection retrofit of a water-fire tube industrial boiler, wherein the threaded flue 3 is located below an airfoil flue 11.

[0057] Working principle:

[0058] (1) This application sets up a smoke plug device 2, which is used to plug the threaded smoke tube 3 of a large water-tube boiler at a certain ratio (the ratio range is 30%-40%, and after assuming the specific plugging ratio, the flue gas temperature after passing through the effective smoke tube under full load conditions is within the temperature range of SCR denitrification, and the flue gas velocity in the smoke tube is still within the safe flow velocity). Without damaging the main structure of the threaded smoke tube 3 of the boiler, the water-tube boiler can use SCR technology to treat nitrogen oxides in the flue gas.

[0059] (2) In this application, a high-temperature flue gas supplement flue 5 is set between the rear wall of the boiler body 1 and the inlet flue 4 of the denitrification SCR reactor. A high-temperature flue gas regulating valve 6 and a non-metallic expansion joint 7 are set on the high-temperature flue gas supplement flue 5. When the boiler is under low load and the flue gas temperature is low, the flue gas temperature discharged through the threaded flue pipe 3 of the boiler body 1 does not reach the flue gas temperature required for denitrification. The high-temperature flue gas regulating valve 6 of the high-temperature flue gas supplement flue 5 is opened to extract some of the higher temperature flue gas in the furnace in advance and mix it with the flue gas discharged through the threaded flue pipe 3 of the boiler body 1 to reach the temperature range of 320-420℃ required for denitrification. The opening degree of the high-temperature flue gas regulating valve 6 is adjusted according to the change of flue gas temperature after mixing. When the boiler load increases and the flue gas temperature of the threaded flue pipe 3 reaches the denitrification temperature, the high-temperature flue gas regulating valve 6 can be closed. All the flue gas in the furnace enters the inlet flue 4 of the denitrification SCR reactor 8 after heat exchange through the flue pipe. The non-metallic expansion joint 7 absorbs the expansion of the flue length due to temperature changes, ensuring that the SCR can still operate stably under various load conditions of the boiler.

[0060] (3) The economizer 9 added to the rear of the SCR in this application is divided into a high-temperature economizer 91 and a low-temperature economizer 92. The two stages of high-temperature economizer 91 and low-temperature economizer 92 are located below the SCR reactor 8 and share the same supporting steel frame with the SCR reactor 8. The upper end of the connecting flue is connected to the outlet of the SCR reactor 8, and the lower end is connected to the inlet of the high-temperature economizer. The two stages of economizer are also connected by a steel connecting flue. The two stages of economizer are equivalent to supplementing the heat-receiving area of ​​the threaded flue tube that was blocked at the front end. Before the modification, the flue tube exhaust temperature was about 150°C, which was the boiler exhaust temperature. After the modification, due to the blockage of the flue tube, the flue tube exhaust temperature reached more than 320°C, which is the denitrification temperature. Therefore, it is necessary to arrange economizers after denitrification to further reduce the flue gas temperature and improve the overall thermal efficiency of the boiler. Finally, it effectively controls and realizes that large industrial boilers with a large proportion of water and fire tubes and relatively backward original technology can fully meet the relevant national standards for ultra-low emissions of boiler pollutants.

[0061] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model's technical solution. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present utility model's technical solution, based on the technical essence of the present utility model and within the spirit and principles of the present utility model, shall still fall within the protection scope of the present utility model's technical solution.

Claims

1. A structure for SCR denitrification environmental retrofitting of a water-tube and fire-tube industrial boiler, comprising a boiler body (1) and an SCR reactor (8), wherein the boiler body (1) is connected to the SCR reactor (8) through an SCR reactor inlet flue (4), characterized in that, The boiler body (1) also includes a threaded smoke pipe (3) and a set of smoke plug devices (2). The threaded smoke pipe (3) and the set of smoke plug devices (2) are connected. The set of smoke plug devices (2) blocks part of the threaded smoke pipe (3) near the smoke pipe inlet at the front end of the boiler shell. The water-fire tube industrial boiler also includes a high-temperature flue gas supplement flue (5), a high-temperature flue gas regulating valve (6), and a non-metallic expansion joint (7). The high-temperature flue gas supplement flue (5) is installed on the rear wall of the boiler body (1) and the inlet flue (4) of the SCR reactor. The high-temperature flue gas supplement flue (5) is connected to the high-temperature flue gas regulating valve (6) and the non-metallic expansion joint (7) respectively. The water-fire tube industrial boiler also includes an economizer (9), which is connected to the SCR reactor (8) and is located below the SCR reactor (8).

2. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 1, characterized in that, The cigarette plug device (2) includes a plug plate (21) and an insert plate (22); The blocking plate (21) and the insert plate (22) are vertically welded together. The insert plate (22) is located in the middle of the blocking plate (21) and is inserted into the end of the threaded smoke pipe (3). The blocking plate (21) is located outside the threaded smoke pipe (3) and blocks the smoke from entering the threaded smoke pipe (3).

3. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 2, characterized in that, The diameter of the blocking plate (21) is larger than the outer diameter of the threaded smoke pipe (3), completely sealing the opening of the threaded smoke pipe (3). The insert plate (22) is a rectangular steel plate, and the inner diameter of the threaded smoke pipe (3) is close to the long side of the insert plate (22).

4. The structure for SCR denitrification environmental protection retrofit of water-tube and fire-tube industrial boilers according to claim 1, characterized in that, The high-temperature flue gas supplement flue (5) is located in the middle area between the boiler body (1) and the SCR reactor inlet flue (4). The high-temperature flue gas regulating valve (6) on the high-temperature flue gas supplement flue (5) is installed on the side near the rear wall of the boiler body (1), and the non-metallic expansion joint (7) is installed on the side near the SCR reactor inlet flue (4).

5. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 4, characterized in that, The opening degree of the high-temperature flue gas regulating valve (6) is adjusted by the change in flue gas temperature after mixing.

6. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 1, characterized in that, The economizer (9) includes a high-temperature economizer (91) and a low-temperature economizer (92). The high-temperature economizer (91) is connected to the low-temperature economizer (92) through the connecting flue (10). The high-temperature economizer (91) and the low-temperature economizer (92) are respectively installed below the SCR reactor (8), and the high-temperature economizer (91) is installed above the low-temperature economizer (92).

7. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 6, characterized in that, The SCR reactor (8) shares the same supporting steel frame with the high-temperature economizer (91) and the low-temperature economizer (92) below. The upper end of the connecting flue (10) is connected to the outlet of the SCR reactor (8), and the lower end of the connecting flue (10) is connected to the inlet of the high-temperature economizer (91).

8. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 6 or 7, characterized in that, The high-temperature economizer (91) and the low-temperature economizer (92) are connected by a steel connecting flue (10). The high-temperature economizer (91) and the low-temperature economizer (92) supplement the heating area of ​​the threaded flue (3) at the front end, which is blocked by the flue plug device (2).

9. The structure for SCR denitrification environmental retrofitting of water-tube and fire-tube industrial boilers according to claim 6 or 7, characterized in that, The water circulation of the high-temperature economizer (91) and the low-temperature economizer (92) is connected in parallel with the boiler body (1), and the supply and return water pipes of the economizer (9) are directly connected to the main system pipe.

Images