A flue gas denitrification purification system for alkali recovery boilers in the papermaking industry

Abstract

The invention provides a flue gas denitration purification system for an alkali recovery boiler in the papermaking industry, and relates to the technical field of denitration. The flue gas denitration purification system comprises a denitration tower and a compressed air component. The denitration tower comprises an inlet, a reaction part and an outlet. The outlet is connected to the bottom end of the reaction part, and the inlet is connected to the top end of the reaction part. An air outlet hood which is hollow inside and open at both ends is arranged in the inlet. The outer wall of the air outlet hood and the inner wall of the inlet together form a receiving groove which is closed at the bottom and open at the top. A centrifugal component is rotatably connected to the top of the air outlet hood. The compressed air component delivers compressed air to the inlet to drive the centrifugal component to rotate. The rotating centrifugal component drives the flue gas passing therethrough to rotate, and throws the sticky substances in the flue gas into the receiving groove. By arranging the centrifugal component in the inlet, the continuously rotating centrifugal component throws the sticky substances adsorbed on the surface of the centrifugal component into the receiving groove, and avoids the sticky substances from being adsorbed on the catalyst in large quantities.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas denitration, and in particular to a flue gas denitration purification system for an alkali recovery boiler in the papermaking industry. Background Art

[0002] The papermaking industry is an indispensable part of people's life. Alkali recovery process is one of the core links in the pulping production process of the papermaking industry. The waste liquid (commonly known as black liquor) in the pulping process is burned through the alkali recovery boiler to recover salt substances such as Na and K in the black liquor. At the same time, the pollution emission load of organic and inorganic substances in the production process is greatly reduced. The heat generated by combustion can also be reused in the black liquor evaporation and concentration process, avoiding a huge waste of resources.

[0003] Related research shows that the main pollutants in the flue gas normally discharged by the alkali recovery boiler burning black liquor are particulate matter and NOx. The emission of particulate matter will cause the generation of severe weather such as haze, and the emission of NOx will cause the destruction of the atmospheric ozone layer and even directly poison the human body, animals and plants. At the same time, NOx is also one of the main causes of acid rain and acid mist. Therefore, the dust removal and denitrification purification link of the flue gas of the alkali recovery boiler in the papermaking industry is indispensable; the papermaking industry generally uses the upstream of the electrostatic precipitator to connect the alkali recovery boiler flue, such as Figure 1 As shown, the flue gas enters the electrostatic precipitator, which removes most of the particulate matter in the flue gas. The electrostatic precipitator mainly uses a high-voltage electrostatic field to achieve electrical separation of the dust-containing gas and has a high dust removal efficiency.

[0004] In the denitrification purification process, SCR denitrification technology is one of the most effective methods to remove NOx from flue gas so far. Ammonia water or other suitable reducing agents are sprayed into the flue gas after dust removal using ammonia spraying equipment, and then through the catalytic action of the catalyst in the denitrification tower, the NOx in the flue gas will be reduced to harmless nitrogen and water, thereby achieving the purpose of flue gas denitrification.

[0005] like Figure 1 As shown, it is an existing flue gas denitration purification system for alkali recovery boilers in the papermaking industry. The flue gas after dust removal by the electrostatic precipitator enters the denitration tower. In the process of the flue gas entering the denitration tower, ammonia water is sprayed into the flue gas after dust removal through an ammonia spraying device. The flue gas after spraying with ammonia water enters the denitration tower 1. The denitration tower is loaded with a catalyst 2 to reduce NOx in the flue gas into harmless nitrogen and water. During the ammonia spraying process, a certain amount of sticky substances such as ammonium hydrogen sulfate will be produced after the flue gas contacts with ammonia molecules. The sticky substances are easy to adhere to the surface of the catalyst 2. The sticky substances adhered to the surface of the catalyst 2 are not easy to remove and collect, which affects the service life of the catalyst and also hinders the contact between the flue gas and the catalyst, thereby affecting the denitration efficiency of the flue gas. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a flue gas denitration purification system for an alkali recovery boiler in the papermaking industry.

[0007] The present invention solves the above-mentioned technical problems through the following technical means: a flue gas denitrification purification system for an alkali recovery boiler in the papermaking industry, comprising a denitrification tower and a compressed air component, the denitrification tower having an inlet portion, a reaction portion and an outlet portion, the outlet portion being connected to the bottom end of the reaction portion, the inlet portion being connected to the top end of the reaction portion, an air inlet hood which is hollow inside and open at both ends of the upper and lower portions being arranged in the inlet portion, the outer wall of the air inlet hood and the inner wall of the inlet portion together enclose a receiving groove which is closed at the bottom and open at the top, a centrifugal component being rotatably connected to the top end of the air inlet hood, the centrifugal component being fixed to the air inlet hood by a connecting piece, the compressed air component conveying compressed air to the inlet portion driving the centrifugal component to rotate, the rotating centrifugal component driving the flue gas passing therethrough to rotate, and throwing the viscous substances in the flue gas into the receiving groove.

[0008] Furthermore, the air inlet cover is in the shape of a cone, and the opening diameter of the air inlet cover gradually increases from the top end to the bottom end.

[0009] Furthermore, the connecting member includes a first fixing block arranged in the top opening of the air inlet cover, a plurality of first connecting rods are fixed to the outside of the first fixing block, and one end of the first connecting rod away from the first fixing block is fixed to the air inlet cover.

[0010] Furthermore, the centrifugal assembly includes a rotating shaft and a centrifugal fan rotatably sleeved on the outer side of the rotating shaft, and the bottom end of the rotating shaft is fixed to the first connecting rod.

[0011] Furthermore, the compressed air component includes a compressed air tank and a compressed air pipeline. The compressed air tank compresses external air and stores it inside. The output end of the compressed air tank is connected to the compressed air pipeline. The output end of the compressed air pipeline passes through the inlet part and extends into the inlet part. The output end of the compressed air pipeline points to the centrifugal component.

[0012] Furthermore, the compressed air component also includes a flue gas heat exchanger connected to the air outlet end of the outlet portion, the air inlet of the flue gas heat exchanger is connected to the output end of the compressed air tank, and the air outlet of the flue gas heat exchanger is connected to the input end of the compressed air pipeline.

[0013] Furthermore, a draft component with upper and lower openings is provided on the top of the centrifugal fan, and the opening size of the draft component gradually increases from the top end to the bottom end.

[0014] Furthermore, the air induced assembly includes a second connecting cover and a connecting ring with a through cavity in the middle, the bottom end of the second connecting cover is fixed to the top edge of the through cavity, a second fixing block is provided in the through cavity, a plurality of second connecting rods are fixed to the outside of the second fixing block, the second connecting rod is fixed to the inner wall of the through cavity at one end away from the second fixing block, and the top end of the rotating shaft is fixed to the second fixing block.

[0015] Furthermore, a cleaning tube is fixedly provided on the surface of the inlet portion, the inlet end of the cleaning tube extends into the receiving groove, the outlet end of the cleaning tube is located outside the inlet portion, and the outlet end is sealed with a sealing cover, which is detachably fixed to the cleaning tube by bolts.

[0016] Furthermore, compressed air circulates inside the flue gas heat exchanger, and the cold compressed air is heated by utilizing the waste heat of the flue gas. A rake soot blower is also connected to the outlet end, and the outlet end of the rake soot blower extends to the reaction part, and the outlet end thereof is located 20-30 cm above the catalyst.

[0017] Beneficial effects of the present invention:

[0018] (1) By arranging a centrifugal assembly in the inlet part, the centrifugal assembly drives the flue gas to rotate and generate centrifugal force. Due to the high density of the viscous substance in the flue gas, the viscous substance is thrown toward the inner wall of the inlet part under the action of the centrifugal force. The viscous substance sinks into the receiving tank under the action of its gravity and the impact of the flue gas, which is convenient for collecting the viscous substance; the viscous substance in the flue gas is removed in the inlet part 11 of the denitrification tower 1, so as to prevent a large amount of viscous substance from entering the reaction part 12, and prevent the viscous substance from clogging the catalyst channel and micropores in the reaction part 12;

[0019] Secondly, the continuously rotating centrifugal component constantly collides with some sticky substances in the flue gas, and the sticky substances are adsorbed on the surface of the centrifugal component. The continuously rotating centrifugal component then throws the sticky substances adsorbed on the surface of the centrifugal component into the storage tank, thereby improving the removal effect of the sticky substances in the flue gas, facilitating the collection of the sticky substances in the flue gas, and avoiding the sticky substances from being adsorbed on the catalyst in large quantities.

[0020] (2) The centrifugal component can also further mix and homogenize the flue gas and ammonia. The ammonia molecules entering the flue gas will be fully mixed and contacted with the flue gas under the rotation of the centrifugal component, thereby further improving the mixing of ammonia water and NOx in the flue gas and improving the denitrification efficiency.

[0021] (3) The centrifugal assembly is driven to rotate by the compressed air assembly, and oxygen is also input into the denitrification tower. The compressed air is rapidly sprayed toward the centrifugal assembly through the compressed air pipeline. The rapidly sprayed airflow drives the centrifugal assembly to rotate, and the sprayed airflow carries oxygen into the denitrification tower. Relevant studies have shown that the increase of an appropriate amount of oxygen can promote the denitrification reaction, thereby improving the overall removal rate of NOx. While the centrifugal assembly drives the flue gas to rotate, it can also increase the mixing effect of the oxygen entering the inlet and the flue gas, further promoting flue gas denitrification. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the existing alkali recovery boiler flue gas denitrification purification system;

[0023] Figure 2 It is a schematic diagram of the alkali recovery boiler flue gas denitration purification system of the present invention;

[0024] Figure 3 for Figure 2 The enlarged structural diagram at a in FIG.

[0025] Figure 4 It is a schematic diagram of the structure of the centrifugal assembly of the present invention;

[0026] Figure 5 It is a schematic diagram of the air inlet cover connection structure of the present invention;

[0027] Figure 6 It is a line graph showing the effect of oxygen content on NOx removal.

[0028] In the figure: 1. denitrification tower; 11. inlet; 12. reaction part; 13. outlet; 2. catalyst; 21. filter layer; 3. air inlet hood; 4. rake soot blower; 41. solenoid valve; 5. compressed air assembly; 51. compressed air tank; 52. flue gas heat exchanger; 54. compressed air pipeline; 6. centrifugal assembly; 61. centrifugal fan; 62. rotating shaft; 7. connecting piece; 72. first connecting rod; 73. first fixed block; 8. induced draft assembly; 81. connecting ring; 82. second connecting rod; 83. second fixed block; 84. second connecting hood; 9. cleaning pipe; 91. sealing cover; 10. storage tank. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0031] Example

[0032] See also Figure 2 The present embodiment describes a flue gas denitration purification system for an alkali recovery boiler in the papermaking industry, comprising a denitration tower 1 and a compressed air component 5. The denitration tower 1 has an inlet 11, a reaction part 12 and an outlet 13. The inlet 11, the reaction part 12 and the outlet 13 are all cylindrical bodies with openings at both ends and hollow inside. The outlet 13 is connected to the bottom end of the reaction part 12, and the inlet 11 is connected to the top end of the reaction part 12.

[0033] A conical air inlet hood 3 which is hollow inside and open at both ends is provided in the inlet portion 11. The flue gas can enter the reaction portion 12 through the air inlet hood 3. The outer wall of the air inlet hood 3 and the inner wall of the inlet portion 11 are combined to form a receiving groove 10 with a closed bottom and an open top. The top of the air inlet hood 3 is rotatably connected to a centrifugal assembly 6, and the bottom end of the centrifugal assembly 6 is fixed to the air inlet hood 3 by a connecting piece 7. The compressed air assembly 5 transports external air into the inlet portion 11 and blows it toward the centrifugal assembly 6, driving the centrifugal assembly 6 to rotate.

[0034] The rotating centrifugal assembly 6 drives the flue gas passing through it to rotate, and throws the viscous substances in the flue gas to the receiving tank 10. The receiving tank 10 receives the separated viscous substances and removes the viscous substances in the flue gas in the inlet 11 of the denitrification tower 1, thereby preventing a large amount of viscous substances from entering the reaction part 12 and preventing the clogging of the channels and micropores of the catalyst 2 in the reaction part 12.

[0035] When in use, the rotation of the centrifugal assembly 6 first drives the smoke to generate centrifugal force. Since the density of the viscous material in the smoke is relatively large, much greater than the density of the smoke, the viscous material in the smoke will be thrown toward the inner wall of the inlet portion 11 under the action of the centrifugal force, and the viscous material will sink into the storage tank 10 under the action of its own gravity and the impact of the smoke;

[0036] Secondly, the continuously rotating centrifugal component 6 continuously collides with some sticky substances in the flue gas, and the sticky substances are adsorbed on the surface of the centrifugal component 6. The continuously rotating centrifugal component 6 then throws the sticky substances adsorbed on the surface of the centrifugal component 6 into the storage tank 10, thereby improving the removal effect of the sticky substances in the flue gas, facilitating the collection of the sticky substances in the flue gas, and avoiding the sticky substances from being adsorbed on the catalyst 2 in large quantities.

[0037] After being disturbed by the centrifugal component 6, the ammonia molecules entering the flue gas will be fully mixed and contacted with the flue gas under the rotation of the centrifugal component, thereby once again improving the mixing of ammonia and NOx in the flue gas and improving the denitrification efficiency.

[0038] In order to facilitate the removal of sticky substances in the storage groove 10, a cleaning tube 9 is fixedly provided on the surface of the inlet portion 11. The inlet end of the cleaning tube 9 extends into the storage groove 10, and the outlet end of the cleaning tube 9 is located outside the inlet portion 11. The outlet end is sealed with a sealing cover 91, and the sealing cover 91 is detachably fixed to the cleaning tube 9 by bolts.

[0039] See also Figure 2 As shown, the opening diameter of the top end of the air inlet hood 3 gradually increases to the opening diameter of the bottom end of the air inlet hood 3. This design is used to slow down the speed of the flue gas passing through the air inlet hood 3, so that the speed of the flue gas entering the reaction part 12 is slowed down, and the contact time between the flue gas and the catalyst 2 arranged in the reaction part 12 is increased, thereby improving the removal rate of NOx in the flue gas.

[0040] The compressed air component 5 includes a compressed air tank 51 and a compressed air pipe 54. The compressed air tank 51 compresses external air and stores it inside. The output end of the compressed air tank 51 is connected to the compressed air pipe 54. The output end of the compressed air pipe 54 passes through the inlet part 11 and extends into the inlet part 11. The output end of the compressed air pipe 54 points to the centrifugal component 6.

[0041] The external air carries oxygen, and the compressed air component 5 also inputs oxygen to the inlet portion 11. When in use, the compressed air is rapidly sprayed toward the centrifugal component 6 through the compressed air pipe 54. The rapidly sprayed airflow drives the centrifugal component 6 to rotate, and the sprayed airflow carries oxygen into the inlet portion 11. The increase of an appropriate amount of oxygen can promote the denitration reaction. While the centrifugal component drives the flue gas to rotate, it can also increase the mixing effect of the oxygen and flue gas entering the inlet portion, further promoting flue gas denitration, thereby improving the overall removal rate of flue gas NOx.

[0042] See also Figure 6 The normal oxygen content in flue gas is about 3%. When other conditions remain unchanged, when the oxygen concentration increases from 3% to 5%, the NOx removal rate increases from about 75% to about 85%. By increasing the oxygen concentration, flue gas denitrification can be further promoted.

[0043] As mentioned above, the compressed air drives the centrifugal assembly 6, and the compressed air uses redundant compressed air in the factory to achieve low carbon and energy saving.

[0044] See also Figure 2As shown, the compressed air component 5 also includes a flue gas heat exchanger 52 connected to the air outlet end of the outlet portion 13 , the air inlet of the flue gas heat exchanger 52 is connected to the output end of the compressed air tank 51 , and the air outlet of the flue gas heat exchanger 52 is connected to the input end of the compressed air pipeline 54 .

[0045] When in use, the flue gas after catalytic denitrification treatment by the catalyst 2 still has a relatively high temperature and contains relatively rich waste heat resources. The flue gas heat exchanger 52 transfers the heat in the flue gas to the high-pressure airflow transported by the compressed air pipe 54. The heat carried by the high-pressure airflow is used to preheat the flue gas in the inlet part 11, thereby increasing the temperature of the flue gas entering the reaction part 12. The flue gas entering the reaction part 12 transfers the heat to the catalyst 2, thereby heating the catalyst 2 to reach the catalyst activity temperature and improving the catalytic effect. The flue gas heat exchanger is set to rationally utilize the waste heat of the outlet flue gas to achieve an organic integration of energy saving and environmental protection.

[0046] See also Figure 3 and Figure 4 As shown, the connecting member 7 includes a first fixing block 73 disposed in the top opening of the air inlet cover 3, a plurality of first connecting rods 72 are fixed to the outside of the first fixing block 73, and one end of the first connecting rod 72 away from the first fixing block 73 is fixed to the air inlet cover 3.

[0047] The centrifugal assembly 6 includes a rotating shaft 62 and a centrifugal fan 61 rotatably mounted on the outer side of the rotating shaft 62. The bottom end of the rotating shaft 62 is fixed to the first connecting rod 72 mentioned above. The centrifugal fan 61 is a propeller fan or a turbofan. When in use, the centrifugal fan 61 rotates along the rotating shaft 62. The blades of the centrifugal fan 61 are made of alkali-resistant and anti-corrosion materials that are not easily adhered to the sticky substances in the flue gas, so that the sticky substances in the centrifugal fan 61 can be easily thrown out.

[0048] See also Figure 2 As shown, a draft component 8 with openings at both ends is provided on the top of the centrifugal fan 61. The opening size of the draft component 8 gradually increases from the top end to the bottom end. The smoke enters the small opening through the large opening, and the flow speed is accelerated. The smoke further impacts the centrifugal fan 61, accelerating the rotation speed of the centrifugal fan 61 and improving the removal effect of sticky substances in the smoke.

[0049] Among them, the air induced assembly 8 includes a second connecting cover 84 and a connecting ring 81 with a through cavity in the middle. The bottom end of the second connecting cover 84 is fixed to the top edge of the through cavity. A second fixing block 83 is provided in the through cavity. A plurality of second connecting rods 82 are fixed to the outside of the second fixing block 83. The end of the second connecting rod 82 away from the second fixing block 83 is fixed to the inner wall of the through cavity. The top end of the rotating shaft 62 is fixed to the second fixing block 83. The two ends of the rotating shaft 62 are fixed between the second fixing block 83 and the first fixing block 73 to avoid shaking of the centrifugal fan 61 during rapid rotation and ensure the rotation stability of the centrifugal fan 61.

[0050] See also Figure 2 As shown, the outlet end of the flue gas heat exchanger 52 is also connected to a rake soot blower 4, the outlet end of the rake soot blower 4 extends into the reaction part 12, and its air outlet end is located 20-30 cm above the catalyst 2 to remove dust on the surface of the catalyst 2, wherein the inlet end of the rake soot blower 4 is connected to a solenoid valve 41.

[0051] See also Figure 2 As shown, a filter layer 21 is provided in the inlet end of the reaction part 12, and the filter layer 21 further filters out the sticky substances in the smoke.

[0052] The filter layer 21 is made of a ceramic-impregnated nickel foam material, which has a high porosity and good corrosion resistance. When the flue gas passes through, sticky substances will adhere to the filter material and then be removed, further reducing the possibility of catalyst clogging.

[0053] The filter layer 21 is placed in a drawer-type structure, which includes an outer frame and a drawer frame (not shown in the figure). The outer frame is mainly a frame beam structure, which is arranged above the catalyst 2 and fixed in the reaction part 12. A drawer frame is movably arranged on the outer frame, and the outer frame is used to support the drawer frame. The filter layer 21 is placed in the drawer frame, which is convenient for regular cleaning of the filter layer 21 and improves the cleaning efficiency and service life of the filter material.

[0054] It should be noted that, in this article, if there are first and second, etc., relational terms are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0055] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A flue gas denitration purification system for an alkali recovery boiler in the papermaking industry, comprising a denitration tower (1) and a compressed air component (5), wherein the front end of the denitration tower (1) is connected to an ammonia spraying device, and during the process of the flue gas entering the denitration tower, ammonia water is sprayed into the flue gas after dust removal through the ammonia spraying device, and the flue gas after the ammonia water is sprayed enters the denitration tower (1), wherein the denitration tower (1) has an inlet portion (11), a reaction portion (12) and an outlet portion (13), wherein the outlet portion (13) is connected to the bottom end of the reaction portion (12), and the inlet portion (11) is connected to the top end of the reaction portion (12), and wherein: The inlet portion (11) is provided with an air inlet hood (3) which is hollow inside and open at both ends. The outer wall of the air inlet hood (3) and the inner wall of the inlet portion (11) are combined to form a receiving groove (10) with a closed bottom and an open top. The top of the air inlet hood (3) is rotatably connected to a centrifugal assembly (6). The centrifugal assembly (6) and the air inlet hood (3) are fixed by a connecting piece (7). The compressed air assembly (5) delivers compressed air to the inlet portion (11) to drive the centrifugal assembly (6) to rotate. The rotating centrifugal assembly (6) drives the passing flue gas to rotate, and throws the viscous substances formed by the contact between the flue gas and the ammonia molecules in the flue gas to the receiving tank (10). The separated viscous substances are received by the receiving tank (10), and the viscous substances in the flue gas are removed in the inlet (11) of the denitrification tower (1), so as to prevent a large amount of viscous substances from entering the reaction part (12), thereby preventing the catalyst channels and micropores in the reaction part (12) from being blocked.

2. According to claim 1, a flue gas denitration purification system for alkali recovery boilers in the papermaking industry is characterized by: The air inlet cover (3) is in the shape of a cone, and the opening diameter of the air inlet cover (3) gradually increases from the top end to the bottom end.

3. The flue gas denitration purification system for alkali recovery boiler in papermaking industry according to claim 1 is characterized by: The connecting member (7) comprises a first fixing block (73) arranged in the top opening of the air inlet cover (3), a plurality of first connecting rods (72) are fixed on the outside of the first fixing block (73), and one end of the first connecting rod (72) away from the first fixing block (73) is fixed to the air inlet cover (3).

4. A flue gas denitration purification system for alkali recovery boilers in the papermaking industry according to claim 2, characterized in that: The centrifugal assembly (6) comprises a rotating shaft (62) and a centrifugal fan (61) rotatably sleeved on the outside of the rotating shaft (62); the bottom end of the rotating shaft (62) is fixed to a first fixing block (73).

5. The flue gas denitration purification system for alkali recovery boiler in papermaking industry according to claim 1 is characterized by: The compressed air component (5) comprises a compressed air tank (51) and a compressed air pipeline (54). The compressed air tank (51) compresses external air and stores it therein. The output end of the compressed air tank (51) is connected to the compressed air pipeline (54). The output end of the compressed air pipeline (54) passes through the inlet portion (11) and extends into the inlet portion (11). The output end of the compressed air pipeline (54) points to the centrifugal component (6).

6. A flue gas denitration purification system for alkali recovery boilers in the papermaking industry according to claim 5, characterized in that: The compressed air component (5) further comprises a flue gas heat exchanger (52) connected to the air outlet end of the outlet portion (13); the air inlet of the flue gas heat exchanger (52) is connected to the output end of the compressed air tank (51); and the air outlet of the flue gas heat exchanger (52) is connected to the input end of the compressed air pipeline (54).

7. A flue gas denitration purification system for alkali recovery boilers in papermaking industry according to any one of claims 3 to 6, characterized in that: The top of the centrifugal fan (61) is provided with an air induction component (8) with openings at both ends, and the size of the opening at the top of the air induction component (8) gradually increases towards the size of the opening at the bottom.

8. The flue gas denitration purification system for alkali recovery boiler in papermaking industry according to claim 7 is characterized by: The air induction assembly (8) comprises a second connecting cover (84) and a connecting ring (81) having a through cavity in the middle, the bottom end of the second connecting cover (84) is fixed to the top edge of the through cavity, a second fixing block (83) is provided in the through cavity, a plurality of second connecting rods (82) are fixed to the outside of the second fixing block (83), one end of the second connecting rod (82) away from the second fixing block (83) is fixed to the inner wall of the through cavity, and the top end of the rotating shaft (62) is fixed to the second fixing block (83).

9. The flue gas denitration purification system for alkali recovery boiler in papermaking industry according to claim 1, characterized in that: A cleaning tube (9) is fixedly provided on the surface of the inlet portion (11), the inlet end of the cleaning tube (9) extends into the storage groove (10), the outlet end of the cleaning tube (9) is located outside the inlet portion (11), and the outlet end is sealed with a sealing cover (91), and the sealing cover (91) is detachably fixed to the cleaning tube (9) by bolts.

10. A flue gas denitration purification system for alkali recovery boilers in the papermaking industry according to claim 5 or 6, characterized in that: The outlet end of the flue gas heat exchanger (52) is also connected to a rake soot blower (4), and the outlet end of the rake soot blower (4) extends into the reaction part (12), and its outlet end is located 20-30 centimeters above the catalyst (2).

Images