Combined denitration system

Abstract

The utility model provides a combined denitration system. The combined denitration system comprises a hearth, a horizontal flue and a vertical flue, a plurality of first reducing agent spray guns are installed on the side wall of the hearth, a first valve is installed on a branch pipe in front of each first reducing agent spray gun, a first detector is installed at a spray head of each first reducing agent spray gun, and each first valve and each first detector are electrically connected with a first controller. A second reducing agent spray gun is installed above the first-stage economizer, and a second valve is installed between the second reducing agent spray gun and the second reducing agent supply device. And a second detector and a third detector are mounted beside the second reducing agent spray gun. And the second valve, the second detector and the third detector are electrically connected with the second controller. According to the combined denitration system provided by the utility model, the reducing agent is sprayed into the flue gas in a targeted manner according to the operation load of the boiler, so that the consumption of the reducing agent is reduced, the denitration efficiency is improved, and the adaptability of a combined denitration process to the load change of the boiler is also improved.

Description

Technical Field

[0001] The utility model relates to the technical field of flue gas treatment, in particular to a combined denitration system. Background Art

[0002] Denitrification is the process of converting nitrogen oxides in flue gas into nitrogen and water. Nitrogen oxides are one of the air pollutants. Nitrogen oxide emissions mainly come from human activities such as industrial production, transportation and energy consumption. When fuel is burned, the nitrogen and oxygen in it react under high temperature conditions to form nitrogen oxides. These nitrogen oxides interact with other pollutants in the atmosphere to form secondary pollutants such as ozone and fine particulate matter, which have serious impacts on human health and the environment. Therefore, denitrification technology plays an extremely important role in the prevention and control of air pollution.

[0003] At present, the commonly used denitrification methods include SNCR (non-catalytic reduction denitrification), SCR (catalytic reduction denitrification), and SNCR+SCR (non-catalytic reduction denitrification and catalytic reduction denitrification combined denitrification). The method of non-catalytic reduction denitrification is to directly spray the reducing agent in the furnace to purify the nitrogen oxides in the flue gas. No catalyst is required in the denitrification process, the cost is low, and it is easy to arrange, but the denitrification efficiency is low, and the temperature required for the reaction of nitrogen oxides and reducing agent is high. The method of catalytic reduction denitrification is that the reducing agent reacts with the flue gas under the action of the catalyst to remove the nitrogen oxides in the flue gas. Although the denitrification efficiency is high and does not require a high reaction temperature, the investment and operation costs of catalytic reduction denitrification equipment are high, the catalyst is expensive and easily poisoned and polluted. Combined denitrification combines the advantages of catalytic reduction denitrification and non-catalytic reduction denitrification. A reducing agent spraying device is set in the furnace and at the end of the flue, and a catalyst bed is also installed at the end of the flue. The two are combined to treat the nitrogen oxides in the flue gas, which improves the treatment effect of nitrogen oxides while reducing the amount of catalyst and equipment cost.

[0004] However, the combined denitration process in the prior art has poor adaptability to boiler load changes and can only perform denitration on boilers operating at a given load. When the boiler load changes, the distribution of the temperature field inside the boiler will change, and the spraying of the reducing agent cannot change according to the change of the boiler load, which will lead to waste of reducing agent and reduced denitration efficiency. Utility Model Content

[0005] The utility model provides a combined denitration system, which is used to solve the problem of poor adaptability of the combined denitration process to boiler load changes in the prior art.

[0006] The utility model provides a combined denitration system, including a furnace, a horizontal flue connected above the furnace, and a vertical flue connected at the end of the horizontal flue; a primary economizer, a catalyst bed and a secondary economizer are sequentially installed in the vertical flue along the flue gas flow direction. A plurality of first reducing agent spray guns are installed on the side wall of the furnace, and each first reducing agent spray gun is connected to a first reducing agent supply device through a branch pipe and a main pipe. A first valve is installed on the branch pipe connected to each first reducing agent spray gun, and a first detector is installed at the nozzle of each first reducing agent spray gun, and each first valve and each first detector are electrically connected to a first controller. A second reducing agent spray gun is installed above the primary economizer, and the second reducing agent spray gun is connected to a second reducing agent supply device, and a second valve is installed between the second reducing agent supply device and the second reducing agent spray gun. A second detector and a third detector are installed at the connection between the horizontal flue and the vertical flue, and the second valve, the second detector and the third detector are electrically connected to the second controller.

[0007] Optionally, a guide plate group is installed at the connection between the furnace and the horizontal flue, and the guide plate group includes a plurality of curved guide plates which are parallel to each other and installed equidistantly, and each curved guide plate is composed of three straight plates, the two straight plates at the ends are parallel to the axes of the furnace and the horizontal flue respectively, and the straight plate in the middle has an angle of 30-60° with the horizontal flue along the direction of flue gas flow.

[0008] Optionally, a rectifying grid is horizontally installed at the entrance of the vertical flue. The second reducing agent spray gun is located above the rectifying grid.

[0009] Optionally, a bag filter, an induced draft fan and a chimney are sequentially connected to the smoke outlet of the vertical flue along the smoke flow direction.

[0010] Optionally, soot blowers are installed above the primary economizer, the catalyst bed and the secondary economizer. An ash hopper is installed at the bottom of the vertical flue. The dust outlets of the bag filter and the ash hopper are connected to the ash bin.

[0011] Optionally, the rectifying grid comprises a multi-grid grid body composed of a plurality of steel plates arranged in a staggered manner horizontally and vertically, and a cyclone plate is installed in each grid in the horizontal direction of the grid body.

[0012] Optionally, each cyclone plate includes a fixed plate matching the grid size of the grid body, a through hole is opened at the center of the fixed plate, a blind plate is arranged at the center of the through hole, and an inclined cyclone blade is installed between the through hole and the blind plate.

[0013] Optionally, the aperture of each through hole gradually decreases along the direction of smoke flow in the horizontal flue.

[0014] Optionally, the reducing agent in the first reducing agent supply device and the second reducing agent supply device is ammonia water or urea.

[0015] The combined denitrification system provided by the utility model realizes the effect of spraying reducing agent into the flue gas in a targeted manner according to the load of boiler operation through the coordinated action of the first valve, the first detector, the first controller, the second valve, the second detector, the third detector and the second controller, thereby reducing the amount of reducing agent used, improving the denitrification efficiency, and also improving the adaptability of the combined denitrification process to changes in boiler load.

[0016] By installing guide plate groups and rectifier grids in the furnace and flue, the flow field of the flue gas is adjusted to make the flue gas velocity relatively uniform, thereby improving the catalytic denitrification rate.

[0017] By installing soot blowers above each device in the vertical flue and installing an ash hopper at the bottom of the vertical flue, the dust accumulated on the equipment is cleaned, thereby improving the efficiency and service life of the equipment.

[0018] By adding a swirl plate to the grille body and setting the aperture of the swirl plate specifically according to the flow field of the flue gas, the mixing effect between the flue gas and the reducing agent is improved, the flue gas is further evenly distributed, and the denitrification efficiency of the flue gas is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic diagram of the structure of a combined denitration system provided in one embodiment of the utility model;

[0021] Figure 2 A schematic diagram of the structure of a reducing agent spraying device in a furnace provided by an embodiment of the utility model;

[0022] Figure 3 A schematic structural diagram of a combined denitration system provided in another embodiment of the utility model;

[0023] Figure 4 A schematic diagram of the top view of the rectifying grid provided in one embodiment of the utility model;

[0024] Figure 5 A schematic structural diagram of a cyclone tray provided in one embodiment of the utility model.

[0025] Description of reference numerals:

[0026] 1-furnace, 2-horizontal flue, 3-vertical flue, 4-bag collector, 5-induced draft fan, 6-chimney, 11-first reducing agent spray gun, 12-branch pipe, 13-main pipe, 14-first reducing agent supply device, 15-first valve, 16-first detector, 17-first controller, 18-second controller, 19-guide plate group, 21-rectifier grid, 22-grid body, 23-swirl plate, 24-fixed plate, 25-through hole, 26-swirl blade, 27-blind plate, 31-first economizer, 32-catalyst bed, 33-secondary economizer, 34-second reducing agent spray gun, 35-second reducing agent supply device, 36-second valve, 37-soot blower, 38-ash hopper, 41-ash storage, 171-second detector, 172-third detector, 191-bent guide plate. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the embodiments of the utility model clearer, the technical solution in the embodiments of the utility model is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work also fall within the scope of protection of the utility model.

[0028] like Figure 1 and Figure 2 As shown, the utility model provides a combined denitrification system, including a furnace 1, a horizontal flue 2 is connected to the top of the furnace 1, and a vertical flue 3 is connected to the end of the horizontal flue 2. A primary economizer 31, a catalyst bed 32 and a secondary economizer 33 are sequentially installed in the vertical flue 3 along the flue gas flow direction. A plurality of first reducing agent spray guns 11 are installed on the side wall of the furnace 1, and each first reducing agent spray gun 11 is connected to a first reducing agent supply device 14 through a branch pipe 12 and a main pipe 13. A first valve 15 is installed on the branch pipe 12 connected to each first reducing agent spray gun 11, and a first detector 16 is installed at the nozzle of each first reducing agent spray gun 11, and each first valve 15 and each first detector 16 are electrically connected to a first controller 17. A second reducing agent spray gun 34 is installed above the first-stage economizer 31, and the second reducing agent spray gun 34 is connected to the second reducing agent supply device 35, and a second valve 36 is installed between the second reducing agent supply device 35 and the second reducing agent spray gun 34; a second detector 171 and a third detector 172 are installed at the connection between the horizontal flue 2 and the vertical flue 3, and the second valve 36, the second detector 171 and the third detector 172 are electrically connected to the second controller 18.

[0029] During operation, the combustion material is burned in the furnace 1 of the boiler, and the flue gas generated during the combustion process enters the horizontal flue 2 from the top of the furnace 1, and then enters the vertical flue 3 after passing through the horizontal flue 2. After entering the vertical flue 3, the flue gas passes through the primary economizer 31, the catalyst bed 32 and the secondary economizer 33 in sequence, and finally is discharged from the end of the vertical flue 3 and enters the next stage. The primary economizer 31 and the secondary economizer 33 are devices for recovering heat from the flue gas and reducing the flue gas temperature, and the catalyst bed 32 is a device for purifying nitrogen oxides in the flue gas.

[0030] The first detector 16 located at the nozzle of the first reducing agent spray gun 11 is a temperature detector, which is used to detect the temperature of the flue gas flowing near the first reducing agent spray gun 11. When the temperature measured by the first detector 16 is within the temperature range suitable for non-catalytic reduction denitrification, the signal is fed back to the first controller 17, and the first controller 17 controls the corresponding first valve 15 to open. At this time, the first reducing agent supply device 14 provides the reducing agent, and sprays it through the corresponding first reducing agent spray gun 11. At this time, non-catalytic reduction denitrification is carried out in the furnace 1. It should be noted that the first reducing agent spray gun 11 is distributed in the furnace 1 in both the circumferential and axial directions, and the figure only shows a schematic diagram of the axial distribution along one side.

[0031] After the non-catalytic reduction denitrification in the furnace 1 is completed, the flue gas and the unreacted reducing agent reach the vertical flue 3 through the horizontal flue 2.

[0032] The second detector 171 located at the connection between the horizontal flue 2 and the vertical flue 3 is a reducing agent content detector, and the third detector 172 is a nitrogen oxide content detector. The second detector 171 detects the content of the reducing agent, and the third detector 172 detects the nitrogen oxide content of the flue gas, and the detection results are fed back to the second controller 18. When the reducing agent content detected by the second detector 171 and the third detector 172 is high and the nitrogen oxide content is low, the second controller 18 controls the second valve 36 to be closed, and there is no need to replenish the reducing agent for the second time. On the contrary, the second valve 36 is opened to replenish the reducing agent into the flue gas. The flue gas and the reducing agent enter the vertical flue 3 together, and catalytic reduction denitrification is completed in the catalyst bed 32. After the denitrification is completed, the flue gas is discharged from the end of the vertical flue 3 and enters the next section.

[0033] When performing non-catalytic reduction denitrification, the first reducing agent spray gun 11 is often installed at a position of 850-1100°C (i.e., the suitable temperature range for non-catalytic reduction denitrification) in the furnace 1 based on experience. However, the position of the temperature range may change at the beginning of boiler operation or when the operating conditions are changed, thereby reducing the efficiency of non-catalytic reduction denitrification and wasting the reducing agent.

[0034] By installing a first valve 15 on the branch pipe 12 in front of each first reducing agent spray gun 11, and installing a first detector 16 at the nozzle of each first reducing agent spray gun 11. The first detector 16 detects the temperature of the flue gas at the nozzle of each first reducing agent spray gun 11, and feeds back the detection result to the first controller 17, and the first controller 17 controls the opening and closing of the first valve 15 on the branch pipe 12 in front of each first reducing agent spray gun 11. Only when one or some first detectors 16 detect that the temperature of the flue gas at the corresponding nozzle is within the suitable temperature range of non-catalytic reduction denitrification, the first valve 15 corresponding to the first detector 16 will be opened, and then the reducing agent will be sprayed into the furnace 1 through the first reducing agent spray gun 11, so as to spray the reducing agent into the flue gas in a targeted manner, which is conducive to avoiding the waste of reducing agent. The above-mentioned devices work together to improve the efficiency of flue gas denitrification and reduce the amount of reducing agent.

[0035] The second valve 36, the second detector 171, the third detector 172 and the second controller 18 are provided to further detect and process the flue gas that has completed the non-catalytic reduction denitrification, so as to ensure that the nitrogen oxide content in the discharged flue gas is qualified.

[0036] A first reducing agent supply device 14 and a second reducing agent supply device 35 are respectively provided at the furnace 1 (non-catalytic reduction denitration) and the vertical flue 3 (catalytic reduction denitration). The operating states of the two reducing denitration devices are determined according to the operating load of the boiler, and the reducing agent is sprayed into the flue gas in a targeted manner, thereby reducing the amount of reducing agent, improving the denitration efficiency, and improving the adaptability of the combined denitration process to changes in boiler load.

[0037] like Figure 3 As shown, further, a guide plate group 19 is installed at the connection between the furnace 1 and the horizontal flue 2, and the guide plate group 19 includes a plurality of curved guide plates 191 that are parallel to each other and installed at equal distances, and each curved guide plate 191 is composed of three straight plates, and the two straight plates at the ends are parallel to the axes of the furnace 1 and the horizontal flue 2 respectively, and the straight plate in the middle has an angle of 30-60° with the horizontal flue 2 along the flue gas flow direction. The straight plate in the middle of the curved guide plate 191 can also be replaced with an arc plate.

[0038] A guide plate group 19 is installed at the connection between the furnace 1 and the horizontal flue 2 to guide the flue gas. The guide plate group 19 uses the parallel bends between the curved guide plates 191 to smoothly introduce the flue gas in the furnace 1 into the horizontal flue 2. The curved guide plates 191 can avoid the occurrence of backflow and help improve the uniformity of the flue gas flow field in the horizontal flue 2.

[0039] like Figure 3 As shown, further, a rectifying grid 21 is horizontally installed at the entrance of the vertical flue 3. The second reducing agent spray gun 34 is located above the rectifying grid 21.

[0040] The rectifying grid 21 plays a role in stabilizing the flue gas. After the flue gas collides and integrates in the rectifying grid 21, the flue gas flowing horizontally before entering the rectifying grid 21 is adjusted to flow downward. At the same time, the flue gas speed that is different before entering the rectifying grid 21 is distributed and integrated to make it relatively uniform, which is conducive to improving the catalytic denitrification rate.

[0041] The second reducing agent spray gun 34 is located above the rectifying grid 21 and sprays the reducing agent into the flue gas before the flue gas passes through the rectifying grid 21. The flue gas and the flue gas can be mixed more evenly through the rectifying grid 21, which helps to improve the denitration efficiency.

[0042] like Figure 3 As shown, further, a bag filter 4, an induced draft fan 5 and a chimney 6 are sequentially connected to the smoke outlet of the vertical flue 3 along the smoke flow direction.

[0043] The flue gas discharged from the end of the vertical flue 3 contains a lot of dust, so it needs to be dedusted by the bag filter 4 before being discharged into the atmosphere. The induced draft fan 5 is used to transport and drain the flue gas.

[0044] like Figure 3 As shown, further, soot blowers 37 are installed above the primary economizer 31, the catalyst bed 32 and the secondary economizer 33. An ash hopper 38 is installed at the bottom of the vertical flue 3. The dust outlets of the bag filter 4 and the ash hopper 38 are connected to the ash bin 41.

[0045] During the operation of the system, a large amount of dust in the flue gas will accumulate at the primary economizer 31, the catalyst bed 32 and the secondary economizer 33. The accumulated dust not only affects the working efficiency of the device, but also corrodes the above three. Therefore, the dust accumulated on the primary economizer 31, the catalyst bed 32 and the secondary economizer 33 is blown away by the soot blower 37, and the blown dust falls into the ash hopper 38 at the bottom of the vertical flue 3 for collection.

[0046] The dust outlets of the bag filter 4 and the ash hopper 38 are connected to the ash bin 41 to facilitate the unified collection and treatment of dust.

[0047] like Figure 4 and Figure 5As shown, further, the rectifying grid 21 includes a multi-grid grid body 22 composed of a plurality of steel plates arranged horizontally and vertically in an interlaced manner, and a swirl plate 23 is installed in each grid in the horizontal direction of the grid body 22. Further, each swirl plate 23 includes a fixed plate 24 matching the grid size of the grid body 22, a through hole 25 is opened at the center of the fixed plate 24, a blind plate 27 is arranged at the center of the through hole 25, and an inclined swirl blade 26 is installed between the through hole 25 and the blind plate 27. Further, the aperture of each through hole 25 gradually decreases along the direction of flue gas flow in the horizontal flue 2.

[0048] A swirl plate 23 is installed on the grid body 22, so that when the flue gas and the reducing agent pass through the inclined swirl blades 26 installed on the swirl plate 23, the kinetic energy of the gas itself is used to generate a swirl, further improving the mixing effect between the flue gas and the reducing agent.

[0049] When the flue gas flows in the horizontal flue 2, it changes its flow direction after being blocked by the flue wall at the end of the horizontal flue 2, and flows into the vertical flue 3. Therefore, the distribution of the flue gas entering the vertical flue 3 is gradually increased along the flow direction of the flue gas in the horizontal flue 2. The aperture of each through hole 25 is gradually reduced along the flow direction of the flue gas in the horizontal flue 2, so that the flue gas can be further evenly distributed, thereby improving the denitration efficiency of the flue gas.

[0050] The fixing plate 24 is used to fix the cyclone plate 23 in the grid body 22. In addition, there are fixing devices under the rectifying grid 21, the first economizer 31, the catalyst bed 32 and the second economizer 33, which will not be described here.

[0051] Furthermore, the reducing agent in the first reducing agent supply device 14 and the second reducing agent supply device 35 is ammonia water or urea.

[0052] The present invention is further described in detail below in conjunction with specific embodiments.

[0053] Example 1

[0054] When the combined denitration system is working, the combustion material is burned in the furnace 1 of the boiler, and the flue gas generated during the combustion process enters the horizontal flue 2 from the top of the furnace 1, and then enters the vertical flue 3 after passing through the horizontal flue 2. After entering the vertical flue 3, the flue gas passes through the primary economizer 31, the catalyst bed 32 and the secondary economizer 33 in sequence, and finally is discharged from the end of the vertical flue 3 and enters the next stage. The primary economizer 31 and the secondary economizer 33 are devices for recovering heat in the flue gas and reducing the flue gas temperature, and the catalyst bed 32 is a device for purifying nitrogen oxides in the flue gas.

[0055] The first detector 16 located at the nozzle of the first reducing agent spray gun 11 is a temperature detector, which is used to detect the temperature of the flue gas flowing near the first reducing agent spray gun 11. When the temperature measured by the first detector 16 is within the temperature range suitable for non-catalytic reduction denitrification, the signal is fed back to the first controller 17, and the first controller 17 controls the corresponding first valve 15 to open. At this time, the first reducing agent supply device 14 provides the reducing agent, and sprays it through the corresponding first reducing agent spray gun 11. At this time, non-catalytic reduction denitrification is carried out in the furnace 1.

[0056] After the non-catalytic reduction denitrification in the furnace 1 is completed, the flue gas and the unreacted reducing agent reach the vertical flue 3 through the horizontal flue 2.

[0057] The second detector 171 located at the connection between the horizontal flue 2 and the vertical flue 3 is a reducing agent content detector, and the third detector 172 is a nitrogen oxide content detector. The second detector 171 detects the content of the reducing agent, and the third detector 172 detects the nitrogen oxide content of the flue gas, and the detection results are fed back to the second controller 18. When the reducing agent content detected by the second detector 171 and the third detector 172 is high and the nitrogen oxide content is low, the second controller 18 controls the second valve 36 to be closed, and there is no need to replenish the reducing agent for the second time. On the contrary, the second valve 36 is opened to replenish the reducing agent into the flue gas. The flue gas and the reducing agent enter the vertical flue 3 together, and catalytic reduction denitrification is completed in the catalyst bed 32. After the denitrification is completed, the flue gas is discharged from the end of the vertical flue 3 and enters the next section.

[0058] Example 2

[0059] On the basis of Example 1, Example 2 provides an equipment structure and a specific work flow for further improving the denitrification efficiency: installing a guide plate group 19 at the connection between the furnace 1 and the horizontal flue 2 to guide the flue gas can avoid the occurrence of flue gas backflow, which helps to make the flue gas flow field in the horizontal flue 2 uniform. Installing a rectifying grid 21 at the entrance of the vertical flue 3 can play a role in stabilizing the flue gas. After the flue gas collides and integrates in the rectifying grid 21, the flue gas flowing horizontally before entering the rectifying grid 21 is adjusted to flow downward. At the same time, the poor flue gas velocity distribution before entering the rectifying grid 21 is integrated to be relatively uniform. The second reducing agent spray gun 34 is located above the rectifying grid 21, and the reducing agent is sprayed into the flue gas before it passes through the rectifying grid 21. The two can be mixed more evenly through the rectifying grid 21, which helps to improve the denitrification efficiency.

[0060] Example 3

[0061] Embodiment 3 also provides a device structure and workflow for treating dust in flue gas: a bag filter 4, an induced draft fan 5 and a chimney 6 are sequentially connected to the flue gas outlet of the vertical flue 3 along the flue gas flow direction. The bag filter 4 collects and treats the dust in the flue gas before it is discharged, and the induced draft fan 5 is used to transport and drain the flue gas.

[0062] During the operation of the system, a large amount of dust in the flue gas will accumulate at the primary economizer 31, the catalyst bed 32 and the secondary economizer 33. The accumulated dust not only affects the working efficiency of the device, but also corrodes the above three. Therefore, the dust accumulated on the primary economizer 31, the catalyst bed 32 and the secondary economizer 33 is blown away by the soot blower 37, and the blown dust falls into the ash hopper 38 at the bottom of the vertical flue 3 for collection. The dust outlets of the bag filter 4 and the ash hopper 38 are connected to the ash bin 41, which is convenient for the unified collection and treatment of dust.

[0063] Example 4

[0064] Example 4 also provides an equipment structure and work flow for further improving the denitrification efficiency: a swirl plate 23 is added to the grille body 22, so that when the flue gas and the reducing agent pass through the inclined swirl blades 26 installed on the swirl plate 23, the kinetic energy of the gas itself is used to generate a swirl, thereby further improving the mixing effect between the flue gas and the reducing agent.

[0065] When the flue gas flows in the horizontal flue 2, it changes its flow direction after being blocked by the flue wall at the end of the horizontal flue 2, and flows into the vertical flue 3. Therefore, the distribution of the flue gas entering the vertical flue 3 is gradually increased along the flow direction of the flue gas in the horizontal flue 2. The aperture of each through hole 25 is gradually reduced along the flow direction of the flue gas in the horizontal flue 2, so that the flue gas can be further evenly distributed, thereby improving the denitration efficiency of the flue gas.

[0066] The fixing plate 24 is used to fix the cyclone plate 23 in the grid body 22. In addition, there are fixing devices under the rectifying grid 21, the first economizer 31, the catalyst bed 32 and the second economizer 33, which will not be described here.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model, rather than to limit it; although the utility model has been described in detail with reference to the aforementioned embodiments, ordinary technicians in the field should understand that it is still possible to modify the technical solutions recorded in the aforementioned embodiments, or to replace some or all of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solution of the embodiments of the utility model.

Claims

1. A combined denitration system, characterized in that: The furnace comprises a furnace (1), wherein a horizontal flue (2) is connected above the furnace (1), and a vertical flue (3) is connected at the end of the horizontal flue (2); a primary economizer (31), a catalyst bed (32) and a secondary economizer (33) are sequentially installed in the vertical flue (3) along the flue gas flow direction; A plurality of first reducing agent spray guns (11) are installed on the side wall of the furnace (1), and each of the first reducing agent spray guns (11) is connected to a first reducing agent supply device (14) via a branch pipe (12) and a main pipe (13); a first valve (15) is installed on the branch pipe (12) connected to each of the first reducing agent spray guns (11), and a first detector (16) is installed at the nozzle of each of the first reducing agent spray guns (11), and each of the first valves (15) and each of the first detectors (16) are electrically connected to a first controller (17); the first level saving A second reducing agent spray gun (34) is installed above the coal burner (31), the second reducing agent spray gun (34) is connected to a second reducing agent supply device (35), and a second valve (36) is installed between the second reducing agent supply device (35) and the second reducing agent spray gun (34); a second detector (171) and a third detector (172) are installed at the connection between the horizontal flue (2) and the vertical flue (3), and the second valve (36), the second detector (171) and the third detector (172) are electrically connected to a second controller (18).

2. The combined denitration system according to claim 1, characterized in that: A guide plate group (19) is installed at the connection between the furnace (1) and the horizontal flue (2), and the guide plate group (19) includes a plurality of curved guide plates (191) that are parallel to each other and installed at equal distances, and each of the curved guide plates (191) is composed of three straight plates, the two straight plates located at the end are respectively parallel to the axes of the furnace (1) and the horizontal flue (2), and the straight plate located in the middle has an angle of 30-60 degrees with the horizontal flue (2) along the direction of flue gas flow.

3. The combined denitration system according to claim 1, characterized in that: A rectifying grid (21) is horizontally installed at the entrance of the vertical flue (3); The second reducing agent spray gun (34) is located above the rectifying grid (21).

4. The combined denitration system according to claim 1, characterized in that: The smoke outlet of the vertical smoke duct (3) is connected in sequence to a bag filter (4), an induced draft fan (5) and a chimney (6) along the smoke flow direction.

5. The combined denitration system according to claim 4, characterized in that: Soot blowers (37) are respectively installed above the primary economizer (31), the catalyst bed (32) and the secondary economizer (33); An ash hopper (38) is installed at the bottom of the vertical flue (3); The dust outlets of the bag filter (4) and the ash hopper (38) are both connected to the ash bin (41).

6. The combined denitration system according to claim 3, characterized in that: The rectifying grid (21) comprises a multi-grid grid body (22) composed of a plurality of steel plates arranged in a staggered manner horizontally and vertically, and a cyclone plate (23) is installed in each grid in the horizontal direction of the grid body (22).

7. The combined denitration system according to claim 6, characterized in that: Each of the cyclone plates (23) comprises a fixed plate (24) matching the grid size of the grid body (22); a through hole (25) is provided at the center of the fixed plate (24); a blind plate (27) is provided at the center of the through hole (25); and a swirl blade (26) is installed between the through hole (25) and the blind plate (27) at an angle.

8. The combined denitration system according to claim 7, characterized in that: The aperture of each through hole (25) gradually decreases along the direction of smoke flow in the horizontal flue (2).

9. The combined denitration system according to any one of claims 1 to 8, characterized in that: The reducing agent in the first reducing agent supply device (14) and the second reducing agent supply device (35) is ammonia water or urea.

Images