Flue gas purification device and multi-stage flue gas purification method

Abstract

The application discloses a flue gas purification equipment and a multi-stage flue gas purification method, and relates to the technical field of environmental protection engineering construction. In the application, a desulfurization part is arranged as a spray water washing purification tower, the inside of the spray water washing purification tower is provided with a spraying part and a water washing part, the water washing part can wash and treat flue gas by using alkali liquor, the alkali liquor can be fully contacted and mixed with the flue gas by water washing, so that the alkali liquor can be fully contacted and reacted with sulfur oxides in the flue gas, and the removal effect of the sulfur oxides in the flue gas is improved. In addition, the water washing part is further provided with the spraying part, one or more spraying structures can be arranged in the spraying part, the flue gas after water washing and desulfurization is sprayed and desulfurized again, so that the desulfurization effect of the flue gas is further improved. In addition, the spraying part can spray and add liquid to the water washing part, so that the alkali liquor in the water washing part can be kept in a state of continuous updating, and the reaction and removal effect of the alkali liquor on the sulfur oxides is improved.

Description

Technical Field

[0001] This invention belongs to the field of environmental engineering construction technology, and specifically relates to a flue gas purification device and a multi-stage flue gas purification method. Background Technology

[0002] Boilers and other combustion equipment generate high-temperature flue gas during operation, which contains pollutants such as nitrogen oxides, dust and sulfur oxides. Therefore, it is necessary to carry out multi-stage purification treatment of the flue gas through purification equipment such as catalytic reactors, dust collectors and spray towers to remove pollutants such as nitrogen oxides, dust and sulfur oxides from the flue gas and make the flue gas meet emission standards.

[0003] In existing technologies, spray towers typically employ multi-stage spraying with alkaline solutions to remove sulfur oxides from the flue gas through a reaction with the alkaline solution. For example, Chinese patent application CN108201782A discloses a boiler flue gas purification process where the flue gas is sequentially purified through a multi-stage spray purification chamber and an ultraviolet sterilization and disinfection purifier. A nitrogen-fixing and deodorizing agent is pumped into the multi-stage spray purification chamber by a circulating pump, subjecting the flue gas to multi-stage spraying of sulfur and nitrogen oxides and toxic and harmful gases. This ensures sufficient contact and reaction between the denitrifying, sulfur-fixing, and deodorizing agent and the sulfur and nitrogen oxides and toxic and harmful gases in the flue gas, resulting in purification.

[0004] In the aforementioned patent, although the multi-stage spraying improves the contact and mixing effect between flue gas and alkaline solution, the spray droplets cannot completely cover the space inside the spray tower. As a result, some flue gas will escape directly from the gaps without droplets and will not come into contact with the alkaline solution. Therefore, the sulfur oxides in the flue gas cannot be completely reacted and removed, thus reducing the purification effect of the flue gas. Summary of the Invention

[0005] In view of the problems in related technologies, the present invention proposes a flue gas purification device and a multi-stage flue gas purification method to overcome the above-mentioned technical problems existing in the existing related technologies.

[0006] To solve the above-mentioned technical problems, the present invention is achieved through the following technical solution: This invention relates to a flue gas purification device, comprising a denitrification section, a dust removal section, and a desulfurization section connected in sequence. Flue gas can flow through the denitrification section, the dust removal section, and the desulfurization section in sequence. The denitrification section can perform denitrification treatment on the flue gas when it passes through, the dust removal section can filter and remove dust from the flue gas when it passes through, and the desulfurization section can perform desulfurization treatment on the flue gas when it passes through. The desulfurization unit includes a spray water washing purification tower. The spray water washing purification tower is equipped with a spray section and a water washing section. The water washing section can wash the flue gas with alkaline solution so that the alkaline solution can react with the flue gas to remove sulfur oxides in the flue gas. The water washing section is also equipped with a gas-liquid mixing section, which can premix and atomize the flue gas and alkaline solution before passing it into the alkaline solution for water washing. The spray section can spray alkaline solution into the spray water washing purification tower. The sprayed alkaline solution comes into contact with the flue gas after water washing and desulfurization, so as to perform desulfurization treatment on the flue gas again.

[0007] Preferably, the denitrification section includes a selective catalytic reduction reactor, the bottom of which is provided with a flue gas inlet, and the top of which is connected to a selective catalytic reduction reactor flue gas outlet duct, one end of which is connected to the flue gas inlet of the dust removal section.

[0008] Preferably, the dust removal section includes a dust collector, the end of which is provided with a flue gas inlet communicating with the denitrification section, and the top of the dust collector is connected to a dust collector flue gas output duct, one end of which is connected to the flue gas inlet of the spray water washing purification tower.

[0009] Preferably, the desulfurization section further includes a storage tank containing alkali solution. A hydraulic pump is fixedly installed at the top of the storage tank. The input end of the hydraulic pump is connected to the inside of the storage tank, and the output end of the hydraulic pump is connected to a supply pipe. One end of the supply pipe is connected to the spray section for supplying alkali solution to the spray section.

[0010] Preferably, the spraying section includes a spraying liquid distribution conduit, which is fixedly installed at the upper end inside the spraying water washing purification tower. The liquid inlet of the spraying liquid distribution conduit is connected to the liquid supply conduit, and multiple spray heads are connected and installed at the bottom end of the spraying liquid distribution conduit.

[0011] Preferably, the washing section includes a washing tank and a sealing support frame. The sealing support frame is fixedly installed at the lower end inside the spray washing purification tower. A positioning frame is fixedly installed on the outer ring of the washing tank. The positioning frame is sealed and fixedly installed on the top surface of the sealing support frame. A flue gas diversion duct is fixedly installed inside the washing tank. The inlet end of the flue gas diversion duct is connected to the dust removal section. Multiple gas-liquid mixing sections are connected and installed on the outer ring of the flue gas diversion duct. The gas-liquid mixing sections can mix and atomize the flue gas with alkaline solution before conveying it to the alkaline solution in the washing tank. The bottom of the spray water washing purification tower is provided with a reflux chamber. The side wall of the water washing tank is provided with an overflow structure that communicates with the reflux chamber. The overflow structure is located above the gas-liquid mixing section. The bottom of the reflux chamber is connected to a reflux conduit, and one end of the reflux conduit is connected to a liquid storage tank.

[0012] Preferably, the gas-liquid mixing section includes a gas-liquid mixing conduit, one end of which is connected to and installed on the side wall of the flue gas diversion conduit, and the other end of which is connected to and installed with a rotating liquid distribution structure. A liquid suction conduit is connected to and installed on the side wall of the gas-liquid mixing conduit. The liquid suction conduit can draw and transport the alkaline solution in the water washing tank into the gas-liquid mixing conduit under the negative pressure suction force during flue gas transportation, so that the alkaline solution and flue gas are pre-mixed in the gas-liquid mixing conduit. The gas-liquid mixing conduit is provided with an air inlet booster nozzle with a gradually decreasing inner diameter. The liquid suction conduit is inclined and connected to the air inlet booster nozzle. The liquid outlet end of the liquid suction conduit is provided with a liquid inlet booster nozzle with a gradually decreasing inner diameter. The gas-liquid mixing conduit is also equipped with an atomizing structure inside. The atomizing structure can impact and guide the alkaline solution and flue gas during transportation, so that the alkaline solution is atomized and mixed with the flue gas during transportation.

[0013] Preferably, the atomizing structure includes multiple gas-liquid atomizing guide vanes one and multiple gas-liquid atomizing guide vanes two, both of which are helical blades, and the multiple gas-liquid atomizing guide vanes one and multiple gas-liquid atomizing guide vanes two are distributed alternately in the gas-liquid mixing conduit, while the contact surfaces of adjacent gas-liquid atomizing guide vanes one and gas-liquid atomizing guide vanes two are arranged crosswise; The rotating liquid distribution structure includes a gas-liquid delivery conduit, which is rotatably installed at the end of a gas-liquid mixing conduit. Both ends of the gas-liquid delivery conduit are fixedly installed with gas-liquid output elbows, and the outlet directions of the gas-liquid output elbows at both ends are reversed.

[0014] Preferably, the overflow structure includes an overflow trough and a plurality of overflow holes. The overflow trough is disposed at the upper end of the outer ring of the washing tank, and the plurality of overflow holes are circumferentially distributed on the side wall of the washing tank. The washing tank is connected to the overflow trough through the overflow holes.

[0015] A multi-stage flue gas purification method, the specific steps of which are as follows: The denitrification section, dust removal section and desulfurization section are connected in sequence to form a multi-stage filtration and purification structure. The flue gas flows through the multi-stage filtration and purification structure under the conveying of the fan. The denitrification unit denitrates the flue gas when it passes through, while the dust removal unit filters and removes dust from the flue gas as it passes through. When the flue gas flows through the spray water washing purification tower in the desulfurization section, the gas-liquid mixing section premixes and atomizes the flue gas with the alkaline solution before passing it into the alkaline solution for water washing desulfurization. After that, the flue gas rises and is transported along the spray water washing purification tower, and the spray section sprays and desulfurizes the flue gas. Finally, the flue gas that has undergone denitrification, dust removal, and desulfurization treatment is discharged from the spray water washing purification tower.

[0016] The present invention has the following beneficial effects: 1. In this invention, the desulfurization unit is configured as a spray water washing purification tower. The spray water washing purification tower is internally equipped with a spray unit and a water washing unit. The water washing unit can wash the flue gas with alkaline solution. Through water washing, the alkaline solution and flue gas can be fully contacted and mixed, thereby allowing the alkaline solution to fully react with the sulfur oxides in the flue gas, thus improving the removal effect of sulfur oxides in the flue gas. In addition, the water washing unit is also equipped with a spray unit, which can be equipped with one or more spray structures to spray the flue gas after water washing desulfurization again to further improve the desulfurization effect of the flue gas. The spray unit can also add liquid to the spray in the water washing unit, so that the alkaline solution in the water washing unit is continuously renewed to improve the reaction and removal effect of the alkaline solution on sulfur oxides.

[0017] 2. In this invention, the washing section is further provided with a gas-liquid mixing section and a rotating liquid distribution structure. The gas-liquid mixing section can premix and atomize the flue gas and alkaline solution before introducing them into the alkaline solution for washing, thereby preventing the flue gas from agglomerating and forming bubbles in the alkaline solution. The atomization also helps the flue gas and alkaline solution to come into more thorough contact and mix. The rotating liquid distribution structure can rotate and evenly distribute the premixed and atomized flue gas into the alkaline solution in the washing tank, improving the uniformity of the flue gas distribution in the alkaline solution. At the same time, the rotating liquid distribution structure can agitate the alkaline solution to help the alkaline solution and flue gas mix thoroughly. Thus, the combination of the gas-liquid mixing section and the rotating liquid distribution structure can improve the desulfurization effect on the flue gas, so as to fully remove sulfur oxides in the flue gas.

[0018] 3. The present invention is provided with a denitrification section, a dust removal section and a desulfurization section connected in sequence. When the flue gas flows through the denitrification section, the dust removal section and the desulfurization section in sequence under the conveying of the fan, the denitrification section can perform denitrification treatment on the flue gas, the dust removal section can filter and remove dust from the flue gas, and the desulfurization section can perform desulfurization treatment on the flue gas. In order to remove pollutants such as nitrogen oxides, dust and sulfur oxides from the flue gas through the cooperation of the denitrification section, the dust removal section and the desulfurization section, the flue gas can meet the emission standards and prevent air pollution.

[0019] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a three-dimensional structural diagram of the flue gas purification device of the present invention; Figure 2 This is a schematic diagram of the front structure of the flue gas purification device of the present invention; Figure 3 This is one of the three-dimensional structural schematic diagrams of the spray water washing purification tower of the present invention; Figure 4 This is the second three-dimensional structural schematic diagram of the spray water washing purification tower of the present invention; Figure 5 For the present invention Figure 4 A magnified structural diagram at point A; Figure 6 This is the third three-dimensional structural schematic diagram of the spray water washing purification tower of the present invention; Figure 7 This is a schematic diagram of the internal structure of the spray water washing purification tower of the present invention; Figure 8 For the present invention Figure 7 A magnified structural diagram at point B; Figure 9 This is one of the three-dimensional structural schematic diagrams of the washing tank of the present invention; Figure 10 This is a second three-dimensional structural schematic diagram of the washing tank of the present invention; Figure 11 For the present invention Figure 10 A magnified structural diagram at point C; Figure 12 This is a three-dimensional internal structure diagram of the washing tank of the present invention; Figure 13 For the present invention Figure 12 A magnified structural diagram at point D; Figure 14 This is a schematic diagram of the atomizing mixing section of the present invention.

[0022] In the diagram: 1. Selective catalytic reduction reactor; 11. Selective catalytic reduction reactor flue gas output duct; 2. Dust collector; 21. Dust collector flue gas output duct; 3. Spray water washing purification tower; 31. Liquid storage tank; 32. Hydraulic pump; 33. Liquid supply duct; 34. Return duct; 35. Spray liquid distribution duct; 36. Water washing tank; 37. Flue gas diversion duct; 38. Gas-liquid mixing duct; 39. Gas-liquid conveying duct; 310. Spray head; 311. Sealing support frame; 312. Positioning frame; 313. Overflow hole; 314. Overflow trough; 315. Liquid suction duct; 316. Gas-liquid output elbow; 317. Air inlet pressurizing guide nozzle; 318. Liquid inlet pressurizing guide nozzle; 319. Gas-liquid atomizing guide blade one; 320. Gas-liquid atomizing guide blade two. Detailed Implementation

[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.

[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.

[0025] Example 1 Please see Figures 1-4 As shown, this embodiment is a flue gas purification device, including a denitrification section, a dust removal section, and a desulfurization section connected in sequence. Flue gas can flow through the denitrification section, dust removal section, and desulfurization section in sequence. The denitrification section can perform denitrification treatment on the flue gas when it passes through. The dust removal section can filter and remove dust from the flue gas when it passes through. The desulfurization section can perform desulfurization treatment on the flue gas when it passes through. The desulfurization section includes a spray water washing purification tower 3. The spray water washing purification tower 3 is equipped with a spray section and a water washing section. The water washing section can perform water washing treatment on the flue gas with alkaline solution so that the alkaline solution can react with the flue gas to remove sulfur oxides in the flue gas. The water washing section is also equipped with a gas-liquid mixing section. The gas-liquid mixing section can premix and atomize the flue gas and alkaline solution before passing it into the alkaline solution for water washing. The spray section can spray alkaline solution into the spray water washing purification tower 3. The sprayed alkaline solution comes into contact with the flue gas after water washing and desulfurization to perform desulfurization treatment on the flue gas again.

[0026] When the flue gas purification equipment is working, the denitrification section, dust removal section, and desulfurization section are connected in sequence to form a multi-stage filtration and purification structure. The flue gas flows through the multi-stage filtration and purification structure under the conveying of the fan. The denitrification section performs denitrification treatment on the flue gas when it passes through, and the dust removal section filters and removes dust from the flue gas as it passes through. When the flue gas flows through the spray water washing purification tower 3 in the desulfurization section, the gas-liquid mixing section premixes and atomizes the flue gas with alkaline solution before it is introduced into the alkaline solution for water washing and desulfurization. Afterward, the flue gas rises and is conveyed along the spray water washing purification tower 3, and the spray section sprays and desulfurizes the flue gas. Finally, the flue gas that has completed denitrification, dust removal, and desulfurization treatment is discharged from the spray water washing purification tower 3. In this embodiment, the denitrification section, dust removal section, and desulfurization section work together to remove pollutants such as nitrogen oxides, dust, and sulfur oxides from the flue gas, enabling the flue gas to meet emission standards and preventing air pollution. The spray water washing purification tower 3 uses the spray section and water washing section to perform water washing and spray desulfurization on the flue gas. During water washing desulfurization, the flue gas and alkaline solution are premixed and atomized through the gas-liquid mixing section before being introduced into the alkaline solution for water washing. This prevents the flue gas from agglomerating and forming bubbles in the alkaline solution. The atomization also helps the flue gas and alkaline solution to come into more thorough contact and mix, thereby improving the desulfurization and purification effect of the flue gas.

[0027] Example 2 Please see Figure 1 , Figure 2 As shown, the difference between this embodiment and the above embodiment is that the denitrification section includes a selective catalytic reduction reactor 1, the bottom of the selective catalytic reduction reactor 1 is provided with a flue gas inlet, the top of the selective catalytic reduction reactor 1 is connected to a selective catalytic reduction reactor flue gas output pipe 11, and one end of the selective catalytic reduction reactor flue gas output pipe 11 is connected to the flue gas inlet of the dust removal section.

[0028] The selective catalytic reduction reactor 1 is equipped with a honeycomb catalyst and an ammonia nozzle. When the flue gas flows through the honeycomb catalyst in the selective catalytic reduction reactor 1, the nitrogen oxides in the flue gas react with ammonia under the catalytic action of the honeycomb catalyst to generate harmless nitrogen and water, thereby achieving the removal of nitrogen oxides. The flue gas after denitrification is then transported to the dust removal section through the flue gas output duct 11 of the selective catalytic reduction reactor, where the dust removal section filters and removes dust from the flue gas.

[0029] Furthermore, the selective catalytic reduction reactor 1 is connected to the exhaust port of the combustion equipment through a flue gas duct. By measuring the temperature with thermocouples and adjusting the amount of ammonia injected, the selective catalytic reduction reactor 1 is operated between 350-380℃. At this temperature, ammonium sulfate is in a gaseous state, which avoids poisoning and failure of the honeycomb catalyst, thereby improving the stability of the denitrification reaction in the selective catalytic reduction reactor 1.

[0030] Example 3 Please see Figure 1 , Figure 2 As shown, the difference between this embodiment and the above embodiment is that the dust removal section includes a dust collector 2, the end of the dust collector 2 is provided with a flue gas inlet that communicates with the denitrification section, and the top of the dust collector 2 is connected to and installed with a dust collector flue gas output duct 21, one end of the dust collector flue gas output duct 21 is connected to the flue gas inlet of the spray water washing purification tower 3.

[0031] Among them, the dust collector 2 is a pulse filter bag dust collector or an electrostatic precipitator. When the flue gas is conveyed into the dust collector 2, the dust collector 2 can intercept and filter the dust and other particulate matter in the flue gas to remove solid impurities in the flue gas. Then the flue gas is conveyed to the spray water washing purification tower 3 through the flue gas output duct 21 of the dust collector, and spray water washing and denitrification are carried out in the spray water washing purification tower 3.

[0032] Furthermore, a waste heat recovery heat exchanger and a spray evaporation cooling tower are sequentially connected and installed on the flue gas duct between the selective catalytic reduction reactor 1 and the dust collector 2. The waste heat recovery heat exchanger can use softened water or boiler return water to cool and exchange heat with the high-temperature flue gas, reducing the flue gas temperature from 350-380℃ to the target temperature (usually 160-180℃). This not only realizes the recovery of flue gas heat but also prevents the dust collector 2 bags from becoming clogged due to excessively high flue gas temperature. The spray evaporation cooling tower can spray demineralized water into the flue gas. The demineralized water evaporates and absorbs heat to further cool and regulate the flue gas temperature, while increasing the moisture content of the flue gas and assisting in the agglomeration of fine particles in the flue gas, thereby improving the subsequent flue gas dust removal effect.

[0033] Example 4 Please see Figures 3-5 As shown, the difference between this embodiment and the above embodiment is that the desulfurization section also includes a storage tank 31, which stores alkaline solution. A hydraulic pump 32 is fixedly installed at the top of the storage tank 31. The input end of the hydraulic pump 32 is connected to the inside of the storage tank 31, and the output end of the hydraulic pump 32 is connected to a supply pipe 33. One end of the supply pipe 33 is connected to the spray section for supplying alkaline solution to the spray section. The spray section includes a spray liquid distribution pipe 35, which is fixedly installed at the upper end inside the spray water washing purification tower 3. The inlet of the spray liquid distribution pipe 35 is connected to the supply pipe 33, and multiple spray heads 310 are connected to the bottom end of the spray liquid distribution pipe 35.

[0034] The spray liquid distribution conduit 35 is either a cross-shaped or annular liquid distribution conduit, so that the multiple spray heads 310 at the bottom of the spray liquid distribution conduit 35 can be evenly distributed in the spray water washing purification tower 3. When the flue gas is sprayed for desulfurization, the hydraulic pump 32 draws the alkali solution from the storage tank 31 and continuously delivers the alkali solution to the spray liquid distribution conduit 35 through the liquid supply conduit 33. Finally, the multiple spray heads 310 spray the alkali solution densely into the spray water washing purification tower 3, so that the alkali solution is fully mixed and contacted with the flue gas rising in the spray water washing purification tower 3. At this time, the alkali solution neutralizes and absorbs the sulfur oxides in the flue gas to achieve desulfurization and purification of the flue gas.

[0035] Example 5 Please see Figure 1 , Figure 2 As shown, the difference between this embodiment and the above embodiment is that the washing section includes a washing tank 36 and a sealing support frame 311. The sealing support frame 311 is fixedly installed at the lower end inside the spray washing purification tower 3. A positioning frame 312 is fixedly installed on the outer ring of the washing tank 36. The positioning frame 312 is sealed and fixedly installed on the top surface of the sealing support frame 311. A flue gas diversion duct 37 is fixedly installed inside the washing tank 36. The inlet end of the flue gas diversion duct 37 is connected to the dust removal section. Multiple gas-liquid mixing sections are connected and installed on the outer ring of the flue gas diversion duct 37. The gas-liquid mixing sections can mix and atomize the flue gas and alkaline solution before transporting it to the alkaline solution in the washing tank 36. The washing tank 36 is located below the spray section and can receive the alkaline solution falling from the spray, so that the washing tank 36 is filled with alkaline solution. During flue gas purification, the flue gas can be transported from the dust removal section to the flue gas diversion duct 37. Then, the flue gas is diverted from the flue gas diversion duct 37 to multiple gas-liquid mixing sections in the outer ring. In the gas-liquid mixing section, the flue gas is first premixed and atomized with a small amount of alkaline solution. Then, the moistened and atomized flue gas is transported to the alkaline solution in the washing tank 36, so that the alkaline solution and the flue gas can fully contact and mix. At this time, the alkaline solution neutralizes and absorbs the sulfur oxides in the flue gas to achieve flue gas desulfurization. Afterwards, the desulfurized and purified flue gas overflows from the alkaline solution and is transported upward for spray desulfurization again to improve the desulfurization and purification effect of the flue gas.

[0036] Furthermore, the bottom of the spray water washing purification tower 3 is provided with a reflux chamber, and the side wall of the water washing tank 36 is provided with an overflow structure that communicates with the reflux chamber. The overflow structure is located above the gas-liquid mixing section. The bottom of the reflux chamber is connected to and installed with a reflux conduit 34, and one end of the reflux conduit 34 is connected to the liquid storage tank 31. As the spraying unit continues to spray, the liquid level in the water washing tank 36 will continue to rise. When the alkaline solution in the water washing tank 36 is full, as the alkaline solution continues to spray, the alkaline solution in the water washing tank 36 can overflow outward through the overflow structure and be discharged into the return chamber at the bottom of the spray water washing purification tower 3. Then, the alkaline solution in the return chamber flows back to the storage tank 31 through the return pipe 34, thereby realizing the recycling of the alkaline solution.

[0037] Specifically, the overflow structure includes an overflow trough 314 and multiple overflow holes 313. The overflow trough 314 is located at the upper end of the outer ring of the washing tank 36, and the multiple overflow holes 313 are arranged in a circular pattern on the side wall of the washing tank 36. The washing tank 36 is connected to the overflow trough 314 through the overflow holes 313. When the alkaline liquid level in the washing tank 36 is higher than the position of the overflow hole 313, the alkaline liquid can be transported from the overflow hole 313 to the overflow trough 314, and then overflow from the overflow port at the top of the overflow trough 314 to the return chamber below. The overflow port at the top of the overflow trough 314 is higher than the overflow hole 313, so that when the alkali solution flows into the overflow trough 314 through the overflow hole 313 and fills the overflow trough 314, both sides of the overflow hole 313 can be submerged by the alkali solution, thereby sealing the overflow hole 313 with the alkali solution and preventing the flue gas from being transported from the overflow hole 313 to the return chamber below.

[0038] Furthermore, the gas-liquid mixing section includes a gas-liquid mixing conduit 38. One end of the gas-liquid mixing conduit 38 is connected and installed on the side wall of the flue gas diversion conduit 37, and the other end of the gas-liquid mixing conduit 38 is connected and installed with a rotating liquid distribution structure. A liquid suction conduit 315 is connected and installed on the side wall of the gas-liquid mixing conduit 38. The liquid suction conduit 315 can draw and transport the alkaline solution in the water washing tank 36 into the gas-liquid mixing conduit 38 under the negative pressure suction force during flue gas transportation, so that the alkaline solution and flue gas are premixed in the gas-liquid mixing conduit 38. The gas-liquid mixing conduit 38 is internally equipped with an inlet pressure boosting nozzle 317 with a gradually decreasing inner diameter. The liquid suction conduit 315 is inclined and connected to the inlet pressure boosting nozzle 317. When flue gas is transported through the inlet pressure boosting nozzle 317 in the gas-liquid mixing conduit 38, the flue gas transport speed and transport pressure will increase significantly as the flue gas transport channel gradually narrows. At this time, the gas-liquid mixing conduit 38 can generate negative pressure in the liquid suction conduit 315 under the action of the flue gas transport pressure, so as to draw part of the alkaline solution in the water washing tank 36 through the liquid suction conduit 315. The flue gas is drawn into the gas-liquid mixing conduit 38, allowing the flue gas and alkaline solution to be premixed. The outlet end of the liquid suction conduit 315 is equipped with an inlet pressure guide nozzle 318 with a gradually decreasing inner diameter. As the alkaline solution flows into the inlet pressure guide nozzle 318 within the liquid suction conduit 315, the flow channel locking the alkaline solution gradually narrows, significantly increasing the alkaline solution delivery speed and hydraulic pressure. This allows the alkaline solution to be sprayed at high speed into the gas-liquid mixing conduit 38, where it collides and mixes with the flue gas, thereby improving the premixing effect of the flue gas and alkaline solution and thus enhancing the subsequent desulfurization effect of the flue gas and alkaline solution mixture. Furthermore, the gas-liquid mixing conduit 38 is also equipped with an atomizing structure inside. The atomizing structure can impact and guide the alkaline solution and flue gas during transportation, so that the alkaline solution is atomized and mixed with the flue gas during transportation. The atomization structure includes multiple gas-liquid atomizing guide vanes 319 and multiple gas-liquid atomizing guide vanes 320. Both the gas-liquid atomizing guide vanes 319 and 320 are helical blades. The multiple gas-liquid atomizing guide vanes 319 and 320 are arranged alternately in the gas-liquid mixing conduit 38. At the same time, the contact surfaces of adjacent gas-liquid atomizing guide vanes 319 and 320 are arranged crosswise. When the flue gas and alkaline solution mixture is transported in the gas-liquid mixing duct 38, the mixture impacts the end face of the spiral blades, causing the mixture to be atomized. At the same time, the spiral blades can cut the mixture into two groups and guide them for transport. This process is repeated, and the mixture is repeatedly impacted, atomized, and cut by the staggered spiral blades, which can improve the atomization effect of the flue gas and alkaline solution and make the flue gas and alkaline solution fully and evenly mixed. This improves the premixing effect of the flue gas and alkaline solution, which in turn helps to improve the subsequent desulfurization effect of the flue gas and alkaline solution mixture.

[0039] Furthermore, the rotating liquid distribution structure includes a gas-liquid delivery conduit 39, which is rotatably mounted on the end of a gas-liquid mixing conduit 38. Both ends of the gas-liquid delivery conduit 39 are fixedly mounted with gas-liquid output elbows 316, and the outlet directions of the gas-liquid output elbows 316 at both ends are reversed. After the flue gas and alkaline solution are premixed and atomized in the gas-liquid mixing conduit 38, they are transported to the gas-liquid conveying conduit 39. Then, the mixture of flue gas and alkaline solution is discharged outward from the gas-liquid output elbows 316 at both ends of the gas-liquid conveying conduit 39. Since the outlet directions of the gas-liquid output elbows 316 at both ends are set in opposite directions, the two ends of the gas-liquid conveying conduit 39 receive a reverse thrust. At this time, under the reverse thrust of the mixed gas output, the gas-liquid conveying conduit 39 rotates with the gas-liquid mixing conduit 38 as the fulcrum, thereby driving the gas-liquid output elbows 316 to make a circular motion, so that the gas-liquid output elbows 316 evenly transport the flue gas to the alkaline solution in the water washing tank 36. At the same time, the rotating gas-liquid conveying conduit 39 can disturb the alkaline solution in the water washing tank 36 to help the alkaline solution and flue gas mix fully. Thus, the combination of the gas-liquid mixing part and the rotating liquid distribution structure can improve the reaction desulfurization effect on the flue gas and fully remove sulfur oxides in the flue gas.

[0040] Example 6 This embodiment discloses a multi-stage flue gas purification method, the specific steps of which are as follows: The denitrification section, dust removal section and desulfurization section are connected in sequence to form a multi-stage filtration and purification structure. The flue gas flows through the multi-stage filtration and purification structure under the conveying of the fan. The denitrification unit denitrates the flue gas when it passes through, while the dust removal unit filters and removes dust from the flue gas as it passes through. When the flue gas flows through the spray water washing purification tower 3 in the desulfurization section, the gas-liquid mixing section premixes and atomizes the flue gas with the alkaline solution before passing it into the alkaline solution for water washing desulfurization. After that, the flue gas rises and is transported along the spray water washing purification tower 3, and the spray section sprays and desulfurizes the flue gas. Finally, the flue gas that has undergone denitrification, dust removal, and desulfurization treatment is discharged from the spray water washing purification tower 3.

[0041] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0042] It should be noted that, for the sake of simplicity, the foregoing method embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, because according to the present invention, some steps can be performed in other orders or simultaneously. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily essential to the present invention.

Claims

1. A flue gas purification device, comprising a denitrification unit, a dust removal unit, and a desulfurization unit connected in sequence, characterized in that: The flue gas can flow sequentially through the denitrification section, the dust removal section, and the desulfurization section. The denitrification section can denitrify the flue gas when it passes through, the dust removal section can filter and remove dust from the flue gas when it passes through, and the desulfurization section can desulfurize the flue gas when it passes through. The desulfurization unit includes a spray water washing purification tower. The spray water washing purification tower is equipped with a spray section and a water washing section. The water washing section can wash the flue gas with alkaline solution so that the alkaline solution can react with the flue gas to remove sulfur oxides in the flue gas. The water washing section is also equipped with a gas-liquid mixing section, which can premix and atomize the flue gas and alkaline solution before passing it into the alkaline solution for water washing. The spray section can spray alkaline solution into the spray water washing purification tower. The sprayed alkaline solution comes into contact with the flue gas after water washing and desulfurization, so as to perform desulfurization treatment on the flue gas again.

2. The flue gas purification device according to claim 1, characterized in that: The denitrification section includes a selective catalytic reduction reactor, with a flue gas inlet at the bottom and a selective catalytic reduction reactor flue gas outlet duct connected to the top of the reactor. One end of the selective catalytic reduction reactor flue gas outlet duct is connected to the flue gas inlet of the dust removal section.

3. The flue gas purification device according to claim 1, characterized in that: The dust removal unit includes a dust collector, the end of which is provided with a flue gas inlet communicating with the denitrification unit, and the top of the dust collector is connected to a dust collector flue gas output duct, one end of which is connected to the flue gas inlet of the spray water washing purification tower.

4. The flue gas purification device according to claim 1, characterized in that: The desulfurization unit also includes a storage tank containing alkali solution. A hydraulic pump is fixedly installed at the top of the storage tank. The input end of the hydraulic pump is connected to the inside of the storage tank, and the output end of the hydraulic pump is connected to a supply pipe. One end of the supply pipe is connected to the spray unit for supplying alkali solution to the spray unit.

5. The flue gas purification device according to claim 4, characterized in that: The spray section includes a spray liquid distribution conduit, which is fixedly installed at the upper end inside the spray water washing purification tower. The liquid inlet of the spray liquid distribution conduit is connected to the liquid supply conduit, and multiple spray heads are connected and installed at the bottom end of the spray liquid distribution conduit.

6. The flue gas purification device according to claim 4, characterized in that: The washing section includes a washing tank and a sealing support frame. The sealing support frame is fixedly installed at the lower end inside the spray washing purification tower. A positioning frame is fixedly installed on the outer ring of the washing tank. The positioning frame is sealed and fixedly installed on the top surface of the sealing support frame. A flue gas diversion duct is fixedly installed inside the washing tank. The inlet end of the flue gas diversion duct is connected to the dust removal section. Multiple gas-liquid mixing sections are connected and installed on the outer ring of the flue gas diversion duct. The gas-liquid mixing sections can mix and atomize the flue gas with alkaline solution before delivering it to the alkaline solution in the washing tank. The bottom of the spray water washing purification tower is provided with a reflux chamber. The side wall of the water washing tank is provided with an overflow structure that communicates with the reflux chamber. The overflow structure is located above the gas-liquid mixing section. The bottom of the reflux chamber is connected to a reflux conduit, and one end of the reflux conduit is connected to a liquid storage tank.

7. The flue gas purification device according to claim 6, characterized in that: The gas-liquid mixing section includes a gas-liquid mixing conduit. One end of the gas-liquid mixing conduit is connected and installed on the side wall of the flue gas diversion conduit, and the other end of the gas-liquid mixing conduit is connected and installed with a rotating liquid distribution structure. A liquid suction conduit is connected and installed on the side wall of the gas-liquid mixing conduit. The liquid suction conduit can draw and transport the alkaline solution in the water washing tank into the gas-liquid mixing conduit under the negative pressure suction force during flue gas transportation, so that the alkaline solution and flue gas are pre-mixed in the gas-liquid mixing conduit. The gas-liquid mixing conduit is provided with an air inlet booster nozzle with a gradually decreasing inner diameter. The liquid suction conduit is inclined and connected to the air inlet booster nozzle. The liquid outlet end of the liquid suction conduit is provided with a liquid inlet booster nozzle with a gradually decreasing inner diameter. The gas-liquid mixing conduit is also equipped with an atomizing structure inside. The atomizing structure can impact and guide the alkaline solution and flue gas during transportation, so that the alkaline solution is atomized and mixed with the flue gas during transportation.

8. The flue gas purification device according to claim 7, characterized in that: The atomization structure includes multiple gas-liquid atomizing guide vanes 1 and multiple gas-liquid atomizing guide vanes 2. Both gas-liquid atomizing guide vanes 1 and gas-liquid atomizing guide vanes 2 are helical blades. The multiple gas-liquid atomizing guide vanes 1 and multiple gas-liquid atomizing guide vanes 2 are distributed alternately in the gas-liquid mixing conduit. At the same time, the contact surfaces of adjacent gas-liquid atomizing guide vanes 1 and gas-liquid atomizing guide vanes 2 are arranged crosswise. The rotating liquid distribution structure includes a gas-liquid delivery conduit, which is rotatably installed at the end of a gas-liquid mixing conduit. Both ends of the gas-liquid delivery conduit are fixedly installed with gas-liquid output elbows, and the outlet directions of the gas-liquid output elbows at both ends are reversed.

9. The flue gas purification device according to claim 6, characterized in that: The overflow structure includes an overflow trough and multiple overflow holes. The overflow trough is located at the upper end of the outer ring of the washing tank, and the multiple overflow holes are arranged in a circular pattern on the side wall of the washing tank. The washing tank is connected to the overflow trough through the overflow holes.

10. A multi-stage flue gas purification method, using the flue gas purification equipment as described in any one of claims 1-9, characterized in that, The specific steps are as follows: The denitrification section, dust removal section and desulfurization section are connected in sequence to form a multi-stage filtration and purification structure. The flue gas flows through the multi-stage filtration and purification structure under the conveying of the fan. The denitrification unit denitrates the flue gas when it passes through, while the dust removal unit filters and removes dust from the flue gas as it passes through. When the flue gas flows through the spray water washing purification tower in the desulfurization section, the gas-liquid mixing section premixes and atomizes the flue gas with the alkaline solution before passing it into the alkaline solution for water washing desulfurization. After that, the flue gas rises and is transported along the spray water washing purification tower, and the spray section sprays and desulfurizes the flue gas. Finally, the flue gas that has undergone denitrification, dust removal, and desulfurization treatment is discharged from the spray water washing purification tower.

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