Cross-flow multi-stage adsorption denitration device and denitration method

Abstract

The application discloses a kind of crossflow multi-stage adsorption denitration device and denitration method, including adsorption tower, adsorption tower includes multiple adsorption stages, adsorption tower is used for flue gas and adsorbent crossflow contact, the gas inlet end of adsorption tower is connected with pre-cooler by pipeline, the flue gas import end of pre-cooler is connected with the flue gas export end of boiler, the gas outlet end of adsorption tower is connected with ozone removal device by pipeline, the gas inlet end of adsorption stage is connected with ozone generator device by pipeline, the volume ratio of ozone and nitric oxide in the gas inlet end of each adsorption stage is not less than 1:1, the present application is by using molecular sieve adsorption nitrogen oxide, while maintaining the moderate excess of ozone, it is favorable for the molecular sieve in adsorption tower to fully adsorb nitrogen oxide in flue gas, and the excess ozone is reduced and decomposed by ozone removal device, to avoid the secondary pollution emission caused by excess ozone through flue gas emission to the environment.

Description

Technical Field

[0001] This invention relates to the field of flue gas denitrification technology, specifically to a cross-flow multi-stage adsorption denitrification device and denitrification method. Background Technology

[0002] Nitrogen oxides (NOx) are the main pollutants in various flue gases. NOx emissions into the atmosphere not only directly harm human health, but also cause a series of environmental problems such as smog, acid rain, and photochemical smog. Therefore, controlling NOx emissions from flue gases is crucial for improving air quality.

[0003] The mainstream technology for flue gas denitrification is SCR flue gas denitrification. SCR flue gas denitrification technology has advantages such as high denitrification efficiency and small footprint. However, conventional SCR flue gas denitrification technology requires a relatively high temperature (350-420℃). If the reaction temperature is too low, it will not only affect the denitrification efficiency, but more importantly, the catalyst is prone to poisoning. In recent years, ozone (O3) oxidation combined with activated carbon adsorption has been proposed for flue gas denitrification. This technology first uses O3 to oxidize nitric oxide (NO) into higher valence NOx, and then uses adsorption carbon to adsorb the higher valence NOx, thereby removing nitrogen oxides from the flue gas. However, existing methods for O3 oxidation combined with activated carbon adsorption for flue gas denitrification are prone to disproportionation reactions during the absorption process, especially NO2, which releases NO again, leading to a decrease in denitrification efficiency. Since activated carbon has a strong reducing ability, ozone is easily reduced and decomposed by activated carbon. Therefore, in order to avoid the large-scale disproportionation reaction caused by the reduction and decomposition of ozone, a large amount of O3 needs to be added, resulting in problems such as large O3 dosage and high operating costs. At the same time, the large amount of O3 added can easily cause secondary pollution emissions by overflowing into the environment through flue gas. Summary of the Invention

[0004] The purpose of this invention is to improve and innovate upon the shortcomings and problems existing in the prior art, and to provide a cross-flow multi-stage adsorption denitrification device and denitrification method.

[0005] To achieve the above objectives, according to a first aspect of the present invention, a cross-flow multi-stage adsorption denitrification device is provided, comprising an adsorption tower and an ozone generator. The adsorption tower includes multiple adsorption sections, and the adsorption tower is used for cross-flow contact between flue gas and adsorbent. The inlet end of the adsorption tower is connected to a precooler via a pipe, and the flue gas inlet end of the precooler is connected to the flue gas outlet end of a boiler. The outlet end of the adsorption tower is connected to an ozone removal device via a pipe. The inlet ends of each adsorption section are connected to the ozone generator via outlet pipes, and a solenoid valve is installed on the outlet pipe. A nitric oxide concentration sensor is installed at the inlet end of each adsorption section, and the volume ratio of ozone to nitric oxide in the flue gas at the inlet end of each adsorption section is not less than 1:1.

[0006] A further embodiment is that the ozone removal device includes a removal tower, which is equipped with two layers of filter screens and activated carbon filler is placed between the two layers of filter screens. An activated carbon feed channel is fixedly connected to the top of the ozone removal device, and an activated carbon discharge channel is fixedly connected to the bottom of the ozone removal device. Both the activated carbon feed channel and the activated carbon discharge channel are equipped with shut-off valves.

[0007] A further embodiment is that the ozone removal device includes a removal tower, in which several activated carbon mesh plates are spaced apart. The two ends of the activated carbon mesh plates are slidably connected to a limiting plate, and the two ends of the activated carbon mesh plates are connected to the bottom wall of a sliding groove opened on the limiting plate by springs. The limiting plate is installed on the inner wall of the removal tower. The activated carbon mesh plates have through holes evenly distributed on them. The activated carbon mesh plates are fixedly connected together by connecting plates. A cam is provided inside the removal tower. The cam is driven to rotate by a motor, and the cam abuts against the connecting plate.

[0008] A further option is to install a water separator on the pipeline between the adsorption tower and the precooler.

[0009] A further option is that the adsorbent is a molecular sieve, silica gel, resin, or activated alumina.

[0010] A further embodiment is that the adsorption tower includes a first adsorption sub-tower, a second adsorption sub-tower, and a third adsorption sub-tower. The outlet of the first adsorption sub-tower is connected to the inlet of the second adsorption sub-tower via a pipe, and the outlet of the second adsorption sub-tower is connected to the inlet of the third adsorption sub-tower via a pipe. Ozone dosing points are provided at the inlets of the first, second, and third adsorption sub-towers, and the ozone generator is connected to the ozone dosing points via an outlet pipe.

[0011] A further embodiment is that the adsorption tower includes a first adsorption section, a second adsorption section, and a third adsorption section. A first flue and a second flue are respectively provided on the two side walls of the adsorption tower. Adsorbent redistributors are provided between the first adsorption section and the second adsorption section, and between the second adsorption section and the third adsorption section. The first flue is used to introduce flue gas from the first adsorption section to the second adsorption section, and the second flue is used to introduce flue gas from the second adsorption section to the third adsorption section.

[0012] A further embodiment is that the adsorption tower has an ozone dosing point at its inlet, the ozone generator is connected to the ozone dosing point via an outlet pipe, the outlet of the ozone generator is also connected to a pipe extending into the first flue and the second flue, and multiple nozzles are spaced apart on the pipes located in the first flue and the second flue. Nitric oxide concentration sensors are also installed in the first flue and the second flue.

[0013] A further embodiment is that the adsorbent redistributor includes a grid plate installed on the inner wall of the adsorption tower, the grid plate having uniformly opened mesh holes, a square cone tube fixedly connected to the lower surface of the grid plate, and a round tube fixedly connected to the bottom end of the square cone tube, the square cone tube corresponding to the mesh holes one by one.

[0014] According to a second aspect of the present invention, a cross-flow multi-stage adsorption denitrification method is provided, specifically comprising:

[0015] The flue gas is introduced into the precooler, which reduces the temperature of the flue gas to below 80°C.

[0016] The cooled flue gas is introduced into the adsorption tower, where it flows laterally and comes into cross-flow contact with the adsorbent flowing from top to bottom. The adsorbent can be molecular sieve, silica gel, resin, or activated alumina. The adsorbent adsorbs nitrogen dioxide from the flue gas. The adsorption tower includes multiple adsorption sub-towers or multiple adsorption towers. The nitrogen monoxide concentration in the flue gas at the inlet of each adsorption sub-tower or multiple adsorption towers is monitored by a nitrogen monoxide concentration sensor. A moderate excess of ozone is introduced to ensure that the volume ratio of ozone to nitrogen monoxide in the flue gas is not less than 1:1. The ozone converts the nitrogen monoxide in the flue gas into nitrogen dioxide.

[0017] The flue gas after nitrogen dioxide removal is introduced into an ozone removal device, which reduces and decomposes the excess ozone in the flue gas.

[0018] Compared with the prior art, the beneficial effects of the present invention are: (1) The present invention connects the inlet of each adsorption section or adsorption sub-tower of the adsorption tower to the ozone generator, so that the content of nitric oxide in the flue gas in the inlet of each adsorption section or adsorption sub-tower is adapted to the amount of ozone added, and the amount of ozone added in each adsorption section or adsorption sub-tower decreases in turn. While ensuring the adsorption of nitrogen oxides in the flue gas, the amount of ozone added can be saved to the maximum extent, preventing the waste of ozone and solving the problem of excessive ozone added to the adsorption tower causing excessive cost. Appropriate amount of ozone can inhibit the disproportionation reaction to produce nitric oxide. At the same time, the molecular sieve in the adsorption tower will not reduce the ozone, which is conducive to the molecular sieve in the adsorption tower fully adsorbing nitrogen oxides in the flue gas. The ozone removal device at the tail reduces and decomposes the excess ozone, avoiding the excess ozone from being emitted into the environment through the flue gas and causing secondary pollution emissions.

[0019] (2) The adsorbent of the present invention can be reused after being regenerated by heating. The nitrogen oxides desorbed by heating can be returned to the heating furnace for re-burning and reduction treatment; or be treated by alkaline absorption; or be reduced by SCR; or be made into nitric acid or nitrate products through resource utilization, which is conducive to the repeated recycling of resources.

[0020] (3) The motor in the removal tower drives the cam to rotate, which intermittently squeezes the connecting plate and compresses the spring, causing the activated carbon mesh plate to move up and down reciprocally. The activated carbon mesh plate is in full contact with ozone molecules, which is conducive to the activated carbon mesh plate reducing and decomposing excess ozone. This avoids the excess ozone being discharged directly from the removal tower without sufficient contact with the activated carbon due to the excessively large through holes in the activated carbon mesh plate. Compared with the method of filling activated carbon packing to remove excess ozone, this method can significantly reduce the wind resistance brought by the removal tower and improve the economic operating efficiency of the device.

[0021] (4) Inside the adsorption tower, the flue gas and the adsorbent come into contact in a cross-flow manner, resulting in lower overall resistance and making it suitable for large-scale projects. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the cross-flow multi-stage adsorption denitrification device provided in the first embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the ozone removal device provided in the first embodiment of the present invention;

[0025] Figure 3 This is a schematic diagram of the cross-flow multi-stage adsorption denitrification device provided in the second embodiment of the present invention;

[0026] Figure 4 This is a schematic diagram of the ozone removal device provided in the second embodiment of the present invention;

[0027] Figure 5 This is a schematic diagram of the internal structure of the adsorption tower provided in the second embodiment of the present invention;

[0028] Figure 6 This is a top view of the adsorbent redistributor provided in the second embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of the cross-flow multi-stage adsorption denitrification device provided in the third embodiment of the present invention;

[0030] Figure 8 This is a schematic diagram of the ozone removal device provided in the third embodiment of the present invention;

[0031] Figure 9 This is a schematic diagram of the cross-flow multi-stage adsorption denitrification device provided in the fourth embodiment of the present invention;

[0032] Figure 10 This is a schematic diagram of the ozone removal device provided in the fourth embodiment of the present invention;

[0033] Figure 11 This is a schematic diagram of the internal structure of the adsorption tower provided in the fourth embodiment of the present invention;

[0034] Figure 12 This is a top view of the adsorbent redistributor provided in the fourth embodiment of the present invention.

[0035] Figure reference numerals: Boilers 101, 201, 301, 401; Ozone dosing points 102, 202, 302, 402; Dust collectors 103, 203, 303, 403; Precoolers 104, 204, 304, 404; Water separators 105, 205, 305, 405; Adsorption towers 106, 206, 306, 406; First flue 2061, 4061; Second flue 2062, 4062; Adsorbent distributors 2063, 4063; Grid plates 20631, 40631; Square cone tubes 20632, 40632; Circular tubes 20633, 40633; Ozone generators 107, 207, 307, 407; De-oiling equipment... The following components are included: 108, 208, 308, and 408; 109, 209, 309, and 409 nitric oxide concentration sensors; 110, 210, 310, and 410 vacuum pumps; 1081 and 2081 activated carbon feed channels; 1082 and 2082 filter screens; 1083 and 2083 activated carbon discharge channels; 1061 and 3061 first adsorption sub-towers; 1062 and 3062 second adsorption sub-towers; 1063 and 3603 third adsorption sub-towers; 3081 and 4081 activated carbon mesh plates; 3082 and 4082 through holes; 3083 and 4083 limiting plates; 3084 and 4084 cams; 3085 and 4085 springs; and 3086 and 4086 connecting plates. Detailed Implementation

[0036] To make the objectives, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] It should be noted that when a component is said to be "fixed to" another component, it can be directly attached to the other component or there may be an intervening component. When a component is said to be "connected to" another component, it can be directly connected to the other component or there may be an intervening component.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0039] Example 1

[0040] See Figures 1-2 This invention provides a cross-flow multi-stage adsorption denitrification device, including a boiler 101 and an adsorption tower 106. A dust collector 103, a precooler 104, and a water separator 105 are sequentially installed on the pipeline between the flue gas outlet of the boiler 101 and the flue gas inlet of the adsorption tower 106. Inside the adsorption tower 106, the adsorbent adsorbs nitrogen oxides in the flue gas, thereby achieving flue gas denitrification. The dust collector 103 removes dust from the flue gas. The precooler 104 cools the flue gas to below 80°C to prevent excessively high flue gas temperatures from causing ozone decomposition. The water separator is a cyclone-type water separator. The water separator 105 removes moisture from the flue gas. It is understood that since the adsorbent adsorbs nitrogen oxides through pores, removing moisture from the flue gas prevents moisture from occupying the pores of the adsorbent and reducing its ability to adsorb nitrogen oxides.

[0041] The adsorption tower 106 includes a first adsorption sub-tower 1061, a second adsorption sub-tower 1062, and a third adsorption sub-tower 1063. The gas outlet located in the middle of the first adsorption sub-tower 1061 is connected to the gas inlet located in the middle of the second adsorption sub-tower 1062 via a pipe. The gas outlet located in the middle of the second adsorption sub-tower 1062 is connected to the gas inlet located in the middle of the third adsorption sub-tower 1063 via a pipe. The gas inlet located in the middle of the first adsorption sub-tower 1061 is connected to the flue gas outlet of the water separator 105 via a pipe. An ozone dosing point 102 is provided at the gas inlet of each of the first adsorption sub-tower 1061, the second adsorption sub-tower 1062, and the third adsorption sub-tower 1063. An ozone generator 107 is connected to the ozone dosing point 102 via an outlet pipe. Ozone generator 107 generates ozone through ozone oxidation, catalytic oxidation, or plasma method. Ozone is used to oxidize nitric oxide into nitrogen dioxide, which is easily adsorbed by the adsorbent. Adsorption tower 106 is used for cross-flow contact between flue gas and adsorbent. The flue gas flows laterally within the adsorption tower 106. The adsorbent is fed into the adsorption tower 106 through the feed pipe at the top and discharged through the discharge pipe at the bottom. Due to the resistance in the feed pipe, the flue gas will not be discharged from the adsorption tower 106 through the feed pipe, but will preferentially be discharged from the adsorption tower 106 through the outlet end with less resistance. The adsorbent in the adsorption tower 106 is molecular sieve, silica gel, resin, or activated alumina. Molecular sieve, silica gel, resin, and activated alumina all have strong NO2 adsorption capacity but no reduction capacity and will not reduce ozone. Therefore, it is beneficial to maintain an appropriate amount of ozone in the adsorption tower 106 to inhibit the occurrence of disproportionation reaction.

[0042] An electromagnetic valve is installed on the outlet pipe of the ozone generator 107, and a nitric oxide concentration sensor 109 is installed at the inlet end of each adsorption sub-tower. The nitric oxide concentration sensor 109 is used to monitor the concentration of nitric oxide in the flue gas at the inlet end of each adsorption sub-tower. The ozone generator 107 then controls the opening of the electromagnetic valve on the outlet pipe so that the volume ratio of ozone to nitric oxide at the ozone dosing point 102 is not less than 1:1, preferably 1.2:1 to 1.5:1, to maintain a moderate excess of ozone to suppress the occurrence of disproportionation reaction.

[0043] It should be noted that, since the first adsorption sub-tower 1061 adsorbs most of the nitrogen oxides in the flue gas, the ozone dosage at the ozone injection point 102 at the inlet of the first adsorption sub-tower 1061, the ozone injection point 102 at the inlet of the second adsorption sub-tower 1062, and the ozone injection point 102 at the inlet of the third adsorption sub-tower 1063 decreases sequentially. This sequential decrease in ozone dosage, while ensuring the adsorption of nitrogen oxides in the flue gas, maximizes the conservation of ozone dosage and prevents ozone waste.

[0044] A vacuum pump 110 is fixedly connected to the flue gas outlet of the third adsorption sub-tower 1063. An ozone removal device is fixedly connected to the flue gas outlet of the vacuum pump 110. The ozone removal device includes a removal tower 108, which contains two layers of filter screens 1082. Activated carbon packing is filled between the two layers of filter screens 1082. An activated carbon feed channel 1081 is fixedly connected to the top of the removal tower 108, and an activated carbon discharge channel 1083 is fixedly connected to the bottom of the removal tower 108. Both the activated carbon feed channel 1081 and the activated carbon discharge channel 1083 are equipped with shut-off valves. It is understood that activated carbon has a strong reducing ability and can reduce excess ozone in the flue gas discharged from the third adsorption sub-tower 1063, preventing excess ozone from being emitted into the environment through the flue gas and causing secondary pollution.

[0045] The specific workflow of this embodiment is as follows: In actual use, flue gas is discharged from the outlet of boiler 101, passes through dust collector 103, precooler 104 and water separator 105 in sequence, and then reaches ozone injection point 102. Nitric oxide concentration sensor 109 monitors the nitric oxide content in the flue gas, and controls the opening of the solenoid valve on the outlet pipe of ozone generator 107 based on the monitored nitric oxide content, so that ozone generator 107 injects ozone into ozone injection point 102. After adding ozone, the volume ratio of ozone to nitric oxide in the flue gas is greater than 1:1. This ensures that after the ozone converts nitric oxide to nitrogen dioxide, a suitable amount of ozone remains in the flue gas. The flue gas then sequentially enters the first adsorption sub-tower 1061, the second adsorption sub-tower 1062, and the third adsorption sub-tower 1063. The flue gas undergoes cross-flow contact with the molecular sieve in the first adsorption sub-tower 1061, the second adsorption sub-tower 1062, and the third adsorption sub-tower 1063. The flue gas flows laterally within sub-tower 1062 and the third adsorption sub-tower 1603. Molecular sieves adsorb NO2 from the flue gas. After adsorption, the molecular sieves are discharged through the bottom of the first adsorption sub-tower 1061, the second adsorption sub-tower 1062, and the third adsorption sub-tower 1063. Simultaneously, ozone inhibits the disproportionation reaction, but it cannot completely suppress the production of NO2, and ozone decomposes. Therefore, ozone is added again at ozone injection points 102 between the first and second adsorption sub-towers 1061 and 1062, and between the second and third adsorption sub-towers 1062 and 1063, ensuring that the volume ratio of ozone to nitric oxide in the flue gas entering the second and third adsorption sub-towers 1062 and 1063 remains at no less than 1:1. Finally, the flue gas with nitrogen oxides removed is discharged from the flue gas outlet of the third adsorption sub-tower 1063 and enters the ozone removal device. The activated carbon packing in the ozone removal device reduces and decomposes excess ozone, preventing excess ozone from spilling into the external environment.

[0046] Example 2

[0047] See Figures 3-6This invention provides a cross-flow multi-stage adsorption denitrification device, including a boiler 201 and an adsorption tower 206. A dust collector 203, a precooler 204, and a water separator 205 are sequentially installed on the pipeline between the flue gas outlet of the boiler 201 and the flue gas inlet of the adsorption tower 206. Inside the adsorption tower 206, the adsorbent adsorbs nitrogen oxides in the flue gas, thereby achieving flue gas denitrification. The dust collector 203 removes dust from the flue gas. The precooler 204 cools the flue gas to below 80°C to prevent excessively high flue gas temperatures from causing ozone decomposition. The water separator is a cyclone-type water separator. The water separator 205 removes moisture from the flue gas. It is understood that since the adsorbent adsorbs nitrogen oxides through pores, removing moisture from the flue gas prevents moisture from occupying the pores of the adsorbent and reducing its ability to adsorb nitrogen oxides.

[0048] The adsorption tower 206 includes a first adsorption section, a second adsorption section, and a third adsorption section. The second adsorption section is directly above the first adsorption section, and the third adsorption section is directly above the second adsorption section. A first flue 2061 and a second flue 2062 are respectively provided on the two side walls of the adsorption tower 206. Adsorbent redistributors 2063 are provided between the first adsorption section and the second adsorption section, and between the second adsorption section and the third adsorption section. The first flue 2061 is used to introduce flue gas from the first adsorption section to the second adsorption section, and the second flue 2062 is used to introduce flue gas from the second adsorption section to the third adsorption section.

[0049] In this embodiment, the adsorbent includes a grid plate 20631 installed on the inner wall of the adsorption tower 206. The grid plate 20631 has uniformly distributed mesh holes. A square cone tube 20632 is fixedly connected to the lower surface of the grid plate 20631, and a round tube 20633 is fixedly connected to the bottom end of the square cone tube 20632. The square cone tube 20632 corresponds one-to-one with the mesh holes. It is understood that because the adsorbent enters the lower adsorption section through the round tube 20633, the round tube 20633 experiences resistance. Therefore, the flue gas will not directly enter the upper adsorption section from the round tube 20633, but will preferentially enter the upper adsorption section from the first flue duct 2061 or the second flue duct 2062, which have lower resistance.

[0050] The air inlet of the adsorption tower 206 is connected to the flue gas outlet of the water separator 205 via a pipe, and an ozone dosing point 202 is provided at the air inlet of the adsorption tower 206. The ozone generator 207 is connected to the ozone dosing point 202 via an air outlet pipe. The air outlet of the ozone generator 207 is also connected to a pipe extending to the first flue 2061 and the second flue 2062. Multiple nozzles are spaced apart on the pipes located in the first flue 2061 and the second flue 2062. The nozzles are not shown in the figure. Ozone generator 207 generates ozone through ozone oxidation, catalytic oxidation, or plasma method. Ozone is used to oxidize nitric oxide into nitrogen dioxide, which is easily adsorbed by the adsorbent. Flue gas and adsorbent are in cross-flow contact within adsorption tower 206. The flue gas flows laterally in the first, second, and third adsorption sections. The adsorbent is fed into adsorption tower 206 through the top feed pipe and discharged from the bottom discharge pipe. Due to the resistance in the feed pipe, the flue gas will not exit adsorption tower 206 through the feed pipe but will preferentially exit adsorption tower 206 from the outlet end with less resistance. The adsorbent in adsorption tower 206 is molecular sieve, silica gel, resin, or activated alumina. Molecular sieve, silica gel, resin, and activated alumina have strong NO2 adsorption capacity but no reduction capacity and will not reduce ozone. Therefore, it is beneficial to maintain an appropriate amount of ozone in adsorption tower 206 to inhibit the occurrence of disproportionation reaction.

[0051] An electromagnetic valve is installed on the outlet pipe of the ozone generator 207, and a nitric oxide concentration sensor 209 is installed at the inlet end of each adsorption section. The nitric oxide concentration sensor 209 corresponding to the second adsorption section is installed in the first flue 2061, and the nitric oxide concentration sensor 209 corresponding to the third adsorption section is installed in the second flue 2062. The nitric oxide concentration sensor 209 is used to monitor the concentration of nitric oxide in the flue gas at the inlet end of each adsorption section. The ozone generator 207 then controls the opening of the electromagnetic valve on the outlet pipe so that the volume ratio of ozone to nitric oxide at the inlet end of each adsorption section is not less than 1:1, preferably 1.2:1 to 1.5:1, to maintain a moderate excess of ozone to suppress the occurrence of disproportionation reaction.

[0052] It should be noted that since the first adsorption section adsorbs most of the nitrogen oxides in the flue gas, the ozone dosage at the inlet of the first adsorption section, the inlet of the second adsorption section, and the inlet of the third adsorption section decreases sequentially. This sequential reduction in ozone dosage ensures the adsorption of nitrogen oxides in the flue gas while maximizing ozone conservation and preventing ozone waste.

[0053] An air extraction pump 210 is fixedly connected to the flue gas outlet of the adsorption tower 206. An ozone removal device is fixedly connected to the flue gas outlet of the air extraction pump 210. The ozone removal device includes a removal tower 208, which contains two layers of filter screens 2082. Activated carbon packing is filled between the two layers of filter screens 2082. An activated carbon feed channel 2081 is fixedly connected to the top of the removal tower 208, and an activated carbon discharge channel 2083 is fixedly connected to the bottom of the removal tower 208. Both the activated carbon feed channel 2081 and the activated carbon discharge channel 2083 are equipped with shut-off valves. It is understood that activated carbon has a strong reducing ability and can reduce excess ozone in the flue gas discharged from the third adsorption stage, preventing excess ozone from being emitted into the environment through the flue gas and causing secondary pollution.

[0054] The specific workflow of this embodiment is as follows: In actual use, flue gas is discharged from the outlet of boiler 201, passes through dust collector 203, precooler 204 and water separator 205 in sequence, and then reaches ozone injection point 202. Nitric oxide concentration sensor 209 monitors the nitric oxide content in the flue gas, and controls the opening of the solenoid valve on the outlet pipe of ozone generator 207 based on the monitored nitric oxide content. This ensures that after ozone generator 207 adds ozone to ozone injection point 202, the volume ratio of ozone to nitric oxide in the flue gas is greater than 1:1. This ensures that after ozone converts nitric oxide into nitrogen dioxide, the flue gas still retains an appropriate amount of ozone. The flue gas first enters the first adsorption section of adsorption tower 206. The flue gas in adsorption tower 206 is in cross-flow contact with the molecular sieve. The flue gas flows laterally within the adsorption tower 206, and the molecular sieve adsorbs NO2 from the flue gas. The adsorbed molecular sieve is discharged through the bottom of the adsorption tower 206. At the same time, ozone inhibits the occurrence of disproportionation reaction, but it cannot completely inhibit the production of NO by disproportionation reaction, and ozone will decompose. Therefore, ozone is added again to the first flue duct 2061 and the second flue duct 2062 to ensure that the volume ratio of ozone to nitric oxide in the flue gas entering the second and third adsorption sections is not less than 1:1. Finally, the flue gas with nitrogen oxides removed is discharged from the top of the adsorption tower 206 and enters the ozone removal device. The activated carbon packing in the ozone removal device reduces and decomposes the excess ozone, preventing excess ozone from overflowing into the external environment.

[0055] Example 3

[0056] See Figures 7-8This invention provides a cross-flow multi-stage adsorption denitrification device, including a boiler 301 and an adsorption tower 306. A dust collector 303, a precooler 304, and a water separator 305 are sequentially installed on the pipeline between the flue gas outlet of the boiler 301 and the flue gas inlet of the adsorption tower 306. Inside the adsorption tower 306, the adsorbent adsorbs nitrogen oxides in the flue gas, thereby achieving flue gas denitrification. The dust collector 303 removes dust from the flue gas. The precooler 304 cools the flue gas to below 80°C to prevent excessively high flue gas temperatures from causing ozone decomposition. The water separator is a cyclone-type water separator. The water separator 305 removes moisture from the flue gas. It is understood that since the adsorbent adsorbs nitrogen oxides through pores, removing moisture from the flue gas prevents moisture from occupying the pores of the adsorbent and reducing its ability to adsorb nitrogen oxides.

[0057] The adsorption tower 306 includes a first adsorption sub-tower 3061, a second adsorption sub-tower 3062, and a third adsorption sub-tower 3063. The gas outlet located in the middle of the first adsorption sub-tower 3061 is connected to the gas inlet located in the middle of the second adsorption sub-tower 3062 via a pipe. The gas outlet located in the middle of the second adsorption sub-tower 3062 is connected to the gas inlet located in the middle of the third adsorption sub-tower 3063 via a pipe. The gas inlet located in the middle of the first adsorption sub-tower 3061 is connected to the flue gas outlet of the water separator 305 via a pipe. An ozone dosing point 302 is provided at the gas inlet of each of the first adsorption sub-tower 3061, the second adsorption sub-tower 3062, and the third adsorption sub-tower 3063. An ozone generator 307 is connected to the ozone dosing point 302 via an outlet pipe. Ozone generator 307 generates ozone through ozone oxidation, catalytic oxidation, or plasma method. Ozone is used to oxidize nitric oxide into nitrogen dioxide, which is easily adsorbed by the adsorbent. Adsorption tower 306 is used for cross-flow contact between flue gas and adsorbent. The flue gas flows laterally within the adsorption tower 306. The adsorbent is fed into the adsorption tower 306 through the feed pipe at the top and discharged through the discharge pipe at the bottom. Due to the resistance in the feed pipe, the flue gas will not be discharged from the adsorption tower 306 through the feed pipe, but will preferentially be discharged from the outlet end of the adsorption tower 306 where the resistance is low. The adsorbent in the adsorption tower 306 is molecular sieve, silica gel, resin, or activated alumina. Molecular sieve, silica gel, resin, and activated alumina all have strong NO2 adsorption capacity but no reduction capacity and will not reduce ozone. Therefore, it is beneficial to maintain an appropriate amount of ozone in the adsorption tower 306 to inhibit the occurrence of disproportionation reaction.

[0058] An electromagnetic valve is installed on the outlet pipe of the ozone generator 307, and a nitric oxide concentration sensor 309 is installed at the inlet end of each adsorption sub-tower. The nitric oxide concentration sensor 309 is used to monitor the concentration of nitric oxide in the flue gas at the inlet end of each adsorption sub-tower. The ozone generator 307 then controls the opening of the electromagnetic valve on the outlet pipe so that the volume ratio of ozone to nitric oxide at the ozone dosing point 302 is not less than 1:1, preferably 1.2:1 to 1.5:1, to maintain a moderate excess of ozone to suppress the occurrence of disproportionation reaction.

[0059] It should be noted that, since the first adsorption sub-tower 3061 adsorbs most of the nitrogen oxides in the flue gas, the ozone dosage at the ozone injection point 302 at the inlet of the first adsorption sub-tower 3061, the ozone injection point 302 at the inlet of the second adsorption sub-tower 3062, and the ozone injection point 302 at the inlet of the third adsorption sub-tower 3063 decreases sequentially. This sequential decrease in ozone dosage, while ensuring the adsorption of nitrogen oxides in the flue gas, maximizes the conservation of ozone dosage and prevents ozone waste.

[0060] A vacuum pump 310 is fixedly connected to the flue gas outlet end located in the middle of the third adsorption sub-tower 3063. An ozone removal device is fixedly connected to the flue gas outlet end of the vacuum pump 310. The ozone removal device includes a removal tower 308. Several activated carbon mesh plates 3081 are spaced apart inside the removal tower 308. The two ends of the activated carbon mesh plates 3081 are slidably connected to the limiting plates 3083. The two ends of the activated carbon mesh plates 3081 are connected to the bottom wall of the sliding groove opened on the limiting plates 3083 through springs 3085. The limiting plates 3083 are installed on the inner wall of the removal tower 308. Through holes 3082 are evenly distributed on the activated carbon mesh plates 3081. The activated carbon mesh plates 3081 are fixedly connected together by connecting plates 3086. A cam 3084 is provided inside the removal tower 308. The cam 3084 is driven to rotate by a motor. The cam 3084 abuts against the connecting plates 3086. Understandably, when the motor in the removal tower 308 drives the cam 3084 to rotate, the cam 3084 intermittently presses the connecting plate 3086 and compresses the spring 3085, causing the activated carbon mesh plate 3081 to move up and down reciprocally. This allows the activated carbon mesh plate 3081 to fully contact ozone molecules, which is beneficial for the activated carbon mesh plate 3081 to reduce and decompose excess ozone. This avoids excess ozone from being discharged directly from the removal tower 308 without sufficient contact with the activated carbon due to the excessively large through holes 3082 on the activated carbon mesh plate 3081. Compared with the above embodiment of filling with activated carbon packing to remove excess ozone, this embodiment can significantly reduce the wind resistance brought by the removal tower 308 and improve the economic operating efficiency of the device.

[0061] The specific workflow of this embodiment is as follows: In actual use, flue gas is discharged from the outlet of boiler 301, passes through dust collector 303, precooler 304 and water separator 305 in sequence, and then reaches ozone injection point 302. Nitric oxide concentration sensor 309 monitors the nitric oxide content in the flue gas, and controls the opening of the solenoid valve on the outlet pipe of ozone generator 307 based on the monitored nitric oxide content. This ensures that after ozone generator 307 adds ozone to ozone injection point 302, the volume ratio of ozone to nitric oxide in the flue gas is greater than 1:1, thus achieving optimal ozone concentration. After oxygen converts nitric oxide into nitrogen dioxide, a suitable amount of ozone remains in the flue gas. The flue gas sequentially enters the first adsorption sub-tower 3061, the second adsorption sub-tower 3062, and the third adsorption sub-tower 3063. The flue gas flows laterally within these three sub-towers. Molecular sieves adsorb NO2 from the flue gas, and after adsorption, the molecular sieves are discharged through the bottom of the three sub-towers. Simultaneously, ozone inhibits the disproportionation reaction, but it cannot completely suppress it. The reaction produces NO, and ozone decomposes. Therefore, ozone is added again at ozone injection point 302 between the first adsorption sub-tower 3061 and the second adsorption sub-tower 3062, and between the second adsorption sub-tower 3062 and the third adsorption sub-tower 3063. This ensures that the volume ratio of ozone to nitrogen oxides in the flue gas entering the second adsorption sub-tower 3062 and the third adsorption sub-tower 3063 remains at no less than 1:1. Finally, the flue gas with nitrogen oxides removed is discharged from the third adsorption sub-tower 3063 and enters the ozone removal device. The motor in the removal tower 308 drives the cam 3084 to rotate. The cam 3084 intermittently presses the connecting plate 3086 and compresses the spring 3085, causing the activated carbon mesh plate 3081 to move up and down reciprocally. This allows the activated carbon mesh plate 3081 to fully contact ozone molecules, which is beneficial for the activated carbon mesh plate 3081 to reduce and decompose excess ozone. This avoids excess ozone from being discharged directly from the removal tower 308 without sufficient contact with the activated carbon due to the excessively large through holes 3082 on the activated carbon mesh plate 3081. Compared with the above embodiment of filling with activated carbon packing to remove excess ozone, this embodiment can significantly reduce the wind resistance brought by the removal tower 308.

[0062] Example 4

[0063] See Figures 9-12This invention provides a cross-flow multi-stage adsorption denitrification device, including a boiler 401 and an adsorption tower 406. A dust collector 403, a precooler 404, and a water separator 405 are sequentially installed on the pipeline between the flue gas outlet of the boiler 401 and the flue gas inlet of the adsorption tower 406. Inside the adsorption tower 406, the adsorbent adsorbs nitrogen oxides in the flue gas, thereby achieving flue gas denitrification. The dust collector 403 removes dust from the flue gas. The precooler 404 cools the flue gas to below 80°C to prevent excessively high flue gas temperatures from causing ozone decomposition. The water separator is a cyclone-type water separator. The water separator 405 removes moisture from the flue gas. It is understood that since the adsorbent adsorbs nitrogen oxides through pores, removing moisture from the flue gas prevents moisture from occupying the pores of the adsorbent and reducing its ability to adsorb nitrogen oxides.

[0064] The adsorption tower 406 includes a first adsorption section, a second adsorption section, and a third adsorption section. The second adsorption section is directly above the first adsorption section, and the third adsorption section is directly above the second adsorption section. A first flue 4061 and a second flue 4062 are respectively provided on the two side walls of the adsorption tower 406. Adsorbent redistributors 4063 are provided between the first adsorption section and the second adsorption section, and between the second adsorption section and the third adsorption section. The first flue 4061 is used to introduce flue gas from the first adsorption section to the second adsorption section, and the second flue 4062 is used to introduce flue gas from the second adsorption section to the third adsorption section.

[0065] In this embodiment, the adsorbent includes a grid plate 40631 installed on the inner wall of the adsorption tower 406. The grid plate 40631 has uniformly distributed mesh holes. A square cone tube 40632 is fixedly connected to the lower surface of the grid plate 40631, and a round tube 40633 is fixedly connected to the bottom end of the square cone tube 40632. The square cone tube 40632 corresponds one-to-one with the mesh holes. It is understood that because the adsorbent enters the lower adsorption section through the round tube 40633, the round tube 40633 experiences resistance. Therefore, the flue gas will not directly enter the upper adsorption section from the round tube 40633, but will preferentially enter the upper adsorption section from the first flue duct 4061 or the second flue duct 4062, which has lower resistance.

[0066] The air inlet of the adsorption tower 406 is connected to the flue gas outlet of the water separator 405 via a pipe, and an ozone dosing point 402 is provided at the air inlet of the adsorption tower 406. The ozone generator 407 is connected to the ozone dosing point 402 via an air outlet pipe. The air outlet of the ozone generator 407 is also connected to a pipe extending to the first flue 4061 and the second flue 4062. Multiple nozzles are spaced apart on the pipes located in the first flue 4061 and the second flue 4062. The nozzles are not shown in the figure. Ozone generator 407 generates ozone through ozone oxidation, catalytic oxidation, or plasma method. Ozone is used to oxidize nitric oxide into nitrogen dioxide, which is easily adsorbed by the adsorbent. Flue gas and adsorbent are in cross-flow contact within adsorption tower 406. The flue gas flows laterally in the first, second, and third adsorption sections. The adsorbent is fed into adsorption tower 406 through the top feed pipe and discharged from the bottom discharge pipe. Due to the resistance in the feed pipe, the flue gas will not be discharged from adsorption tower 406 through the feed pipe, but will preferentially be discharged from adsorption tower 406 through the outlet end with less resistance. The adsorbent in adsorption tower 406 is molecular sieve, silica gel, resin, or activated alumina. Molecular sieve, silica gel, resin, and activated alumina all have strong NO2 adsorption capacity but no reduction capacity and will not reduce ozone. Therefore, it is beneficial to maintain an appropriate amount of ozone in adsorption tower 406 to inhibit the occurrence of disproportionation reaction.

[0067] An electromagnetic valve is installed on the outlet pipe of the ozone generator 407, and a nitric oxide concentration sensor 409 is installed at the inlet end of each adsorption section. The nitric oxide concentration sensor 409 corresponding to the second adsorption section is installed in the first flue 4061, and the nitric oxide concentration sensor 409 corresponding to the third adsorption section is installed in the second flue 4062. The nitric oxide concentration sensor 409 is used to monitor the concentration of nitric oxide in the flue gas at the inlet end of each adsorption section. The ozone generator 407 then controls the opening of the electromagnetic valve on the outlet pipe so that the volume ratio of ozone to nitric oxide at the inlet end of each adsorption section is not less than 1:1, preferably 1.2:1 to 1.5:1, to maintain a moderate excess of ozone to suppress the occurrence of disproportionation reaction.

[0068] It should be noted that since the first adsorption section adsorbs most of the nitrogen oxides in the flue gas, the ozone dosage at the inlet of the first adsorption section, the inlet of the second adsorption section, and the inlet of the third adsorption section decreases sequentially. This sequential reduction in ozone dosage ensures the adsorption of nitrogen oxides in the flue gas while maximizing ozone conservation and preventing ozone waste.

[0069] An air pump 410 is fixedly connected to the flue gas outlet end of the adsorption tower 406, and an ozone removal device is fixedly connected to the flue gas outlet end of the air pump 410. The ozone removal device includes a removal tower 408, in which several activated carbon mesh plates 4081 are spaced apart. The two ends of the activated carbon mesh plates 4081 are slidably connected to the limiting plates 4083, and the two ends of the activated carbon mesh plates 4081 are connected to the bottom wall of the sliding groove opened on the limiting plates 4083 by springs 4085. The limiting plates 4083 are installed on the inner wall of the removal tower 408. The activated carbon mesh plates 4081 have through holes 4082 evenly distributed on them. The activated carbon mesh plates 4081 are fixedly connected together by connecting plates 4086. A cam 4084 is provided in the removal tower 408. The cam 4084 is driven to rotate by a motor, and the cam 4084 abuts against the connecting plates 4086. Understandably, when the motor in the removal tower 408 drives the cam 4084 to rotate, the cam 4084 intermittently presses the connecting plate 4086 and compresses the spring 4085, causing the activated carbon mesh plate 4081 to move up and down reciprocally. This allows the activated carbon mesh plate 4081 to fully contact ozone molecules, which is beneficial for the activated carbon mesh plate 4081 to reduce and decompose excess ozone. This avoids excess ozone from being discharged directly from the removal tower 408 without sufficient contact with the activated carbon due to the excessively large through holes 4082 on the activated carbon mesh plate 4081. Compared with the above embodiment of filling with activated carbon packing to remove excess ozone, this embodiment can significantly reduce the wind resistance brought by the removal tower 408 and improve the economic operating efficiency of the device.

[0070] The specific workflow of this embodiment is as follows: In actual use, flue gas is discharged from the outlet of boiler 401, passes through dust collector 403, precooler 404 and water separator 405 in sequence, and then reaches ozone injection point 402. Nitric oxide concentration sensor 409 monitors the nitric oxide content in the flue gas, and controls the opening of the solenoid valve on the outlet pipe of ozone generator 407 based on the monitored nitric oxide content. This ensures that after ozone is added to ozone injection point 402 by ozone generator 407, the volume ratio of ozone to nitric oxide in the flue gas is greater than 1:1. This ensures that after ozone converts nitric oxide into nitrogen dioxide, a suitable amount of ozone is still present in the flue gas. The flue gas first enters the first adsorption section of adsorption tower 406, where it flows laterally. Molecular sieves adsorb NO2 in the flue gas, and after adsorption, the molecular sieves are discharged through the bottom of adsorption tower 406. At the same time, ozone inhibits the occurrence of disproportionation reaction, but cannot completely inhibit the production of NO by disproportionation reaction. Furthermore, ozone decomposes, so ozone is added again in the first flue 2061 and the second flue 2062 to ensure that the volume ratio of ozone to nitric oxide in the flue gas entering the second and third adsorption sections is not less than 1:1. Finally, the flue gas with nitrogen oxides removed is discharged from the top of the adsorption tower 406 and enters the ozone removal device. The motor in the removal tower 408 drives the cam 4084 to rotate. The cam 4084 intermittently squeezes the connecting plate 4086 and compresses the spring 4085, causing the activated carbon mesh plate 4081 to move up and down reciprocally. This allows the activated carbon mesh plate 4081 to fully contact the ozone molecules, which is beneficial for the activated carbon mesh plate 4081 to reduce and decompose excess ozone. This avoids excess ozone from being discharged directly from the removal tower 408 due to the excessively large through holes 4082 on the activated carbon mesh plate 4081 without sufficient contact with the activated carbon. Compared with the above embodiment of filling with activated carbon packing to remove excess ozone, this embodiment can significantly reduce the wind resistance brought by the removal tower 408.

[0071] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention.

[0072] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.

[0073] Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. The reference to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with an embodiment can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily indicate the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application,

[0074] All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0075] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A cross-flow multi-stage adsorption denitrification device, characterized in that: The system includes an adsorption tower and an ozone generator. The adsorption tower comprises multiple adsorption sections and is used for cross-flow contact between flue gas and adsorbent. The inlet of the adsorption tower is connected to a precooler via a pipe. The flue gas inlet of the precooler is connected to the flue gas outlet of the boiler. The outlet of the adsorption tower is connected to an ozone removal device via a pipe. The inlet of each adsorption section is connected to the ozone generator via an outlet pipe. A solenoid valve is installed on the outlet pipe, and a nitric oxide concentration sensor is installed at the inlet of each adsorption section. The volume ratio of ozone to nitric oxide in the flue gas at the inlet of each adsorption section is not less than 1:

1. The ozone removal device includes a removal tower, in which several activated carbon mesh plates are spaced apart. The two ends of the activated carbon mesh plates are slidably connected to a limiting plate, and the two ends of the activated carbon mesh plates are connected to the bottom wall of a sliding groove opened on the limiting plate by springs. The limiting plate is installed on the inner wall of the removal tower. The activated carbon mesh plates have through holes evenly distributed on them. The activated carbon mesh plates are fixedly connected together by connecting plates. A cam is provided in the removal tower. The cam is driven to rotate by a motor. The cam abuts against the connecting plate. The adsorption tower includes a first adsorption section, a second adsorption section and a third adsorption section. A first flue and a second flue are respectively provided on the two side walls of the adsorption tower. Adsorbent redistributors are provided between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section. The first flue is used to introduce flue gas from the first adsorption section to the second adsorption section, and the second flue is used to introduce flue gas from the second adsorption section to the third adsorption section. The adsorption tower has an ozone injection point at its inlet. The ozone generator is connected to the ozone injection point via an outlet pipe. The outlet of the ozone generator is also connected to a pipe extending into the first flue and the second flue. Multiple nozzles are spaced apart on the pipes in the first flue and the second flue. A nitrogen oxide concentration sensor is also installed in the first flue and the second flue. The adsorbent redistributor includes a grid plate installed on the inner wall of the adsorption tower. The grid plate has uniformly opened mesh holes. A square cone tube is fixedly connected to the lower surface of the grid plate. A round tube is fixedly connected to the bottom end of the square cone tube. The square cone tube corresponds to the mesh holes one by one.

2. The cross-flow multi-stage adsorption denitrification device according to claim 1, characterized in that: A water separator is installed on the pipeline between the adsorption tower and the precooler.

3. The cross-flow multi-stage adsorption denitrification device according to claim 1, characterized in that: The adsorbent is a molecular sieve, silica gel, resin, or activated alumina.

4. A cross-flow multi-stage adsorption denitrification method, characterized in that, The method is applied to the cross-flow multi-stage adsorption denitrification device as described in any one of claims 1-3, specifically comprising: The flue gas is introduced into the precooler, which reduces the temperature of the flue gas to below 80°C. The cooled flue gas is introduced into the adsorption tower, where it flows laterally and comes into cross-flow contact with the adsorbent flowing from top to bottom. The adsorbent can be molecular sieve, silica gel, resin, or activated alumina. The adsorbent adsorbs nitrogen dioxide from the flue gas. The adsorption tower includes multiple adsorption sections. The concentration of nitrogen monoxide in the flue gas at the inlet of each adsorption section is monitored by a nitrogen monoxide concentration sensor. A moderate excess of ozone is introduced to ensure that the volume ratio of ozone to nitrogen monoxide in the flue gas is not less than 1:

1. The ozone converts the nitrogen monoxide in the flue gas into nitrogen dioxide. The flue gas after nitrogen dioxide removal is introduced into an ozone removal device, which reduces and decomposes the excess ozone in the flue gas.

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