A multi-stage countercurrent adsorption denitration device and a denitration method

Abstract

The application discloses a countercurrent multi-stage adsorption denitration device and a denitration method, and relates to the technical field of denitration, in particular to a countercurrent multi-stage adsorption denitration device and a denitration method. The device comprises an adsorption tower, the adsorption tower comprises a plurality of adsorption stages, the adsorption tower is used for countercurrent contact of flue gas and adsorbents, a pre-cooler is connected to the gas inlet end of the adsorption tower through a pipeline, the flue gas inlet end of the pre-cooler is connected with the flue gas outlet end of a boiler, an ozone removal device is connected to the gas outlet end of the adsorption tower through a pipeline, the gas inlet end of each adsorption stage is connected with an ozone generator through a pipeline, and the volume ratio of ozone to nitrogen monoxide in the gas inlet end of each adsorption stage is not less than 1:1. The device is used for adsorbing nitrogen oxides by adopting molecular sieves, and meanwhile, the proper excess of ozone is maintained, which is beneficial to the full adsorption of nitrogen oxides in flue gas by the molecular sieves in the adsorption tower. The ozone removal device reduces and decomposes the excess ozone, so that the secondary pollution caused by the discharge of the excess ozone into the environment through flue gas is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of flue gas denitration technology, in particular to a countercurrent multi-stage adsorption denitration device and a denitration method. BACKGROUND

[0002] Nitrogen oxides (NOx) are the main pollutants of various flue gases. The emission of NOx into the atmosphere not only directly harms human health, but also causes a series of environmental problems such as haze, acid rain and photochemical smog. Therefore, controlling the emission of NOx in flue gas is crucial to improving air environmental quality.

[0003] The mainstream technology for flue gas denitration is SCR flue gas denitration. SCR flue gas denitration technology has the advantages of high denitration efficiency and small occupied area, but conventional SCR flue gas denitration technology requires a relatively high temperature (350-420℃). If the reaction temperature is too low, not only the denitration efficiency is affected, but more importantly, the catalyst is easily poisoned. In recent years, people have proposed using ozone (O3) oxidation in combination with activated carbon adsorption for flue gas denitration. This technology first oxidizes nitrogen monoxide (NO) to high-valence NOx using O3, and then adsorbs the high-valence NOx using activated carbon, achieving the purpose of removing nitrogen oxides from flue gas. However, in the existing technology for flue gas denitration using O3 oxidation in combination with activated carbon adsorption, the high-valence nitrogen oxides after oxidation, especially NO2, are prone to disproportionation during the absorption process, which can release NO again, resulting in a decrease in denitration efficiency. Since activated carbon has strong reducing ability, ozone is easily reduced and decomposed by activated carbon. Therefore, in order to avoid the large-scale occurrence of disproportionation caused by the reduction and decomposition of ozone, a large amount of O3 needs to be added, resulting in the problems of large O3 addition amount and high operating cost. At the same time, a large amount of O3 added through flue gas overflow into the environment can also easily cause secondary pollution emissions. SUMMARY

[0004] The purpose of the present application is to improve and innovate in view of the shortcomings and problems in the background art, and to provide a countercurrent multi-stage adsorption denitration device and a denitration method.

[0005] To achieve the above-mentioned purpose, according to the first aspect of the present application, a countercurrent multi-stage adsorption denitration device is provided, comprising an adsorption tower and an ozone generating device, the adsorption tower comprising a plurality of adsorption stages, the adsorption tower being used for countercurrent contact of flue gas and adsorbent, the gas inlet end of the adsorption tower being connected with a pre-cooler through a pipeline, the flue gas inlet end of the pre-cooler being connected with the flue gas outlet end of a boiler, the gas outlet end of the adsorption tower being connected with an ozone removal device through a pipeline, the gas inlet end of each adsorption stage being connected with the ozone generating device through a gas outlet pipeline, an electromagnetic valve being provided on the gas outlet pipeline, and a nitrogen monoxide concentration sensor being provided at the gas inlet end of each adsorption stage, the volume ratio of ozone to nitrogen monoxide in the flue gas at the gas inlet end of each adsorption stage being not less than 1:1.

[0006] Further, the ozone removal device comprises a removal tower, two layers of filter screens are arranged in the removal tower, and activated carbon fillers are filled between the two layers of filter screens; an activated carbon feeding channel is fixedly connected to the top end of the ozone removal device; an activated carbon discharging channel is fixedly connected to the bottom end of the ozone removal device; and a shut-off valve is arranged on the activated carbon feeding channel and the activated carbon discharging channel.

[0007] Further, the ozone removal device comprises a removal tower, a plurality of activated carbon screen plates are arranged in the removal tower at intervals, the two ends of each activated carbon screen plate are slidably connected to a limiting plate, the two ends of each activated carbon screen plate are connected to the bottom wall of a sliding groove formed in the limiting plate through a spring, the limiting plate is mounted on the inner wall of the removal tower, a plurality of through holes are uniformly distributed on each activated carbon screen plate, and the activated carbon screen plates are fixedly connected to each other through connecting plates; a cam is arranged in the removal tower, the cam is driven to rotate by a motor, and the cam abuts against the connecting plates.

[0008] Further, a water separator is arranged on the pipeline between the adsorption tower and the pre-cooler.

[0009] Further, a dust remover is arranged on the pipeline between the boiler and the pre-cooler, the flue gas outlet end of the boiler is connected to the flue gas inlet end of the dust remover through a pipeline, and the flue gas outlet end of the dust remover is connected to the flue gas inlet end of the pre-cooler through a pipeline.

[0010] Further, the adsorption tower comprises a first adsorption sub-tower, a second adsorption sub-tower and a third adsorption sub-tower, the gas outlet end of the first adsorption sub-tower is connected to the gas inlet end of the second adsorption sub-tower through a pipeline, the gas outlet end of the second adsorption sub-tower is connected to the gas inlet end of the third adsorption sub-tower through a pipeline, ozone adding points are arranged at the gas inlet ends of the first adsorption sub-tower, the second adsorption sub-tower and the third adsorption sub-tower, and the ozone generating device is connected to the ozone adding points through a gas outlet pipeline.

[0011] Further, the adsorption tower comprises a first adsorption section, a second adsorption section and a third adsorption section, an ozone adding point is arranged at the gas inlet end of the adsorption tower, the ozone generating device is connected to the ozone adding point through a gas outlet pipeline, the gas outlet end of the ozone generating device is further connected to a pipeline extending between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section, and a plurality of nozzles are arranged on the pipeline between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section at intervals.

[0012] Further, the adsorbent is molecular sieve, resin, silica gel or activated alumina.

[0013] According to a second aspect of the present application, a multi-stage adsorption denitration method in a counter-flow mode is provided, and specifically comprises the following steps:

[0014] The flue gas is introduced into a pre-cooler, which reduces the temperature of the flue gas to below 80 DEG C;

[0015] The cooled flue gas is introduced into an adsorption tower, and the flue gas flows from bottom to top and is in countercurrent contact with the adsorbent flowing from top to bottom, the adsorbent being molecular sieve or resin or silica gel or activated alumina, and the adsorbent adsorbs nitrogen dioxide in the flue gas; wherein the adsorption tower comprises a plurality of adsorption sub-towers or a plurality of adsorption towers, the concentration of nitric oxide in the flue gas at the gas inlet end of each adsorption sub-tower or a plurality of adsorption towers is monitored by a nitric oxide concentration sensor, and a moderate excess of ozone is introduced so that the volume ratio of ozone to nitric oxide in the flue gas is greater than 1:1, and the ozone converts the nitric oxide in the flue gas into nitrogen dioxide;

[0016] The flue gas after removal of nitrogen dioxide is introduced into an ozone removal device, which reduces and decomposes the excess ozone in the flue gas.

[0017] Compared with the prior art, the present application has the following advantages: (1) the present application connects each adsorption section of the adsorption tower or the gas inlet end of each adsorption sub-tower with an ozone generator, so that the content of nitric oxide in the flue gas at the gas inlet end of each adsorption section or adsorption sub-tower is adapted to the amount of ozone introduced, and the amount of ozone introduced into each adsorption section or adsorption sub-tower is gradually reduced, thereby ensuring the adsorption of nitrogen oxides in the flue gas while minimizing the amount of ozone introduced, preventing waste of ozone, solving the problem of excessive cost caused by the introduction of excessive ozone into the adsorption tower, and the appropriate amount of ozone can inhibit the production of nitric oxide by disproportionation, while the molecular sieve in the adsorption tower will not reduce the ozone, which is conducive to the full adsorption of nitrogen oxides in the flue gas by the molecular sieve in the adsorption tower, and the ozone removal device at the tail end reduces and decomposes the excess ozone, avoiding the emission of excess ozone into the environment through the flue gas and causing secondary pollution;

[0018] (2) the adsorbent of the present application can be reused after heating and regeneration, the nitrogen oxides desorbed by heating are returned to the heating furnace for reduction treatment, or are treated by alkali absorption, or are reduced by SCR, or are used to produce nitric acid or nitrate products by resource utilization, which is conducive to the recycling of resources;

[0019] (3) the motor in the removal tower drives the cam to rotate, the cam intermittently presses the connecting plate and compresses the spring, driving 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 reduction and decomposition of excess ozone by the activated carbon mesh plate, avoiding the excessive ozone being directly discharged from the removal tower without being in full contact with the activated carbon due to the excessively large through holes in the activated carbon mesh plate, compared with the method of removing excess ozone by filling activated carbon packing, the wind resistance caused by the removal tower can be significantly reduced, and the economic operation benefit of the device is improved. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0021] Figure 1 A flow diagram of the countercurrent multi-stage adsorption denitration device provided by the first embodiment of the present application;

[0022] Figure 2 A structural diagram of the ozone removal device provided by the first embodiment of the present application;

[0023] Figure 3 A flow diagram of the countercurrent multi-stage adsorption denitration device provided by the second embodiment of the present application;

[0024] Figure 4 A structural diagram of the ozone removal device provided by the second embodiment of the present application;

[0025] Figure 5 A flow diagram of the countercurrent multi-stage adsorption denitration device provided by the third embodiment of the present application;

[0026] Figure 6 A structural diagram of the ozone removal device provided by the third embodiment of the present application;

[0027] Figure 7 A flow diagram of the countercurrent multi-stage adsorption denitration device provided by the fourth embodiment of the present application;

[0028] Figure 8 A structural diagram of the ozone removal device provided by the fourth embodiment of the present application;

[0029] Boiler 101, 201, 301, 401, ozone dosing point 102, 202, 302, 402, dust remover 103, 203, 303, 403, pre-cooler 104, 204, 304, 404, water separator 105, 205, 305, 405, adsorption tower 106, 206, 306, 406, ozone generator 107, 207, 307, 407, removal tower 108, 208, 308, 408, nitric oxide concentration sensor 109, 209, 309, 409, air pump 110, 210, 310, 410, activated carbon feeding channel 1081, 2081, filter screen 1082, 2082, activated carbon discharging channel 1083, 2083, first adsorption sub-tower 1061, 3061, second adsorption sub-tower 1062, 3062, third adsorption sub-tower 1063, 3603, activated carbon screen plate 3081, 4081, through hole 3082, 4082, limiting plate 3083, 4083, cam 3084, 4084, spring 3085, 4085, connecting plate 3086, 4086. DETAILED DESCRIPTION

[0030] In order to make the objects, features and advantages of the present application more clear, the specific embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] It should be noted that when an element is referred to as being "on" another element, it can be directly on the other element or intervening elements can also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements can also be present.

[0032] 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 application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0033] Example 1

[0034] Reference Figures 1-2The application provides a countercurrent multi-stage adsorption denitration device, which comprises a boiler 101 and an adsorption tower 106, and a dust remover 103, a pre-cooler 104 and a water separator 105 are sequentially arranged on a pipeline between a flue gas outlet end of the boiler 101 and a flue gas inlet end of the adsorption tower 106. In the adsorption tower 106, nitrogen oxides in flue gas are adsorbed by an adsorbent, so that the purpose of flue gas denitration is achieved; the dust remover 103 is used for removing dust in the flue gas; the pre-cooler 104 is used for cooling the flue gas to below 80 DEG C, so as to avoid decomposition of ozone caused by excessively high temperature of the flue gas; and the water separator 105 is a cyclone water separator and is used for removing water in the flue gas. It can be understood that, since the adsorbent adsorbs nitrogen oxides through pores, removal of water in the flue gas can avoid occupation of the pores of the adsorbent by water in the flue gas, so that the adsorption capacity of the adsorbent for nitrogen oxides is reduced.

[0035] The adsorption tower 106 comprises a first adsorption sub-tower 1061, a second adsorption sub-tower 1062 and a third adsorption sub-tower 1063, the flue gas outlet end of the first adsorption sub-tower 1061 is connected with the flue gas inlet end of the second adsorption sub-tower 1062 through a pipeline, the flue gas outlet end of the second adsorption sub-tower 1062 is connected with the flue gas inlet end of the third adsorption sub-tower 1063 through a pipeline, and the flue gas inlet end of the first adsorption sub-tower 1061 is connected with the flue gas outlet end of the water separator 105 through a pipeline. Ozone adding points 102 are arranged at the flue gas inlet ends of the first adsorption sub-tower 1061, the second adsorption sub-tower 1062 and the third adsorption sub-tower 1063, and an ozone generating device 107 is connected with the ozone adding points 102 through an outlet pipeline. The ozone generating device 107 generates ozone through an ozone oxidation method or a catalytic oxidation method or a plasma method, and the ozone is used for oxidizing nitrogen monoxide into nitrogen dioxide which is easy to be adsorbed by the adsorbent. The adsorption tower 106 is used for countercurrent contact of the flue gas and the adsorbent. The adsorbent is fed into the adsorption tower 106 from a feeding pipe at the top end of the adsorption tower 106 and is discharged from a discharging pipe at the bottom end of the adsorption tower 106. Since the feeding pipe has resistance, the flue gas cannot be discharged from the adsorption tower 106 through the feeding pipe, but is preferentially discharged from the adsorption tower 106 through the flue gas outlet end with small resistance. The adsorbent in the adsorption tower 106 is molecular sieve, resin, silica gel or active alumina. The molecular sieve, the resin, the silica gel and the active alumina all have strong N02 adsorption capacity but no reduction capacity, and thus cannot reduce ozone, so that a proper amount of ozone can be maintained in the adsorption tower 106 to inhibit the occurrence of disproportionation reaction.

[0036] The ozone generator 107 is provided with an electromagnetic valve on the gas outlet pipeline, and a nitrogen monoxide concentration sensor 109 is arranged at the gas inlet end of each adsorption sub-tower. The nitrogen monoxide concentration sensor 109 is used to monitor the concentration of nitrogen monoxide in the flue gas at the gas inlet end of each adsorption sub-tower. The ozone generator 107 controls the opening degree of the electromagnetic valve on the gas outlet pipeline, so that the volume ratio of ozone to nitrogen monoxide at the ozone dosing point 102 is not less than 1:1, and the ozone is moderately excessive to inhibit the occurrence of disproportionation reaction.

[0037] It should be noted that, since the first adsorption sub-tower 1061 adsorbs most of the nitrogen oxides in the flue gas, the ozone dosing amount at the ozone dosing point 102 on the gas inlet end of the first adsorption sub-tower 1061, the ozone dosing point 102 at the gas inlet end of the second adsorption sub-tower 1062, and the ozone dosing point 102 at the gas inlet end of the third adsorption sub-tower 1063 decreases in turn. The ozone dosing amount decreases in turn, while ensuring the adsorption of nitrogen oxides in the flue gas, which can maximize the saving of ozone dosing amount and prevent the waste of ozone.

[0038] The flue gas outlet end of the third adsorption sub-tower 1063 is fixedly connected with an air pump 110, and the flue gas outlet end of the air pump 110 is fixedly connected with an ozone removal device. The ozone removal device includes a removal tower 108, which is provided with two layers of filter screens 1082. The two layers of filter screens 1082 are filled with activated carbon filler. The top end of the ozone removal device 108 is fixedly connected with an activated carbon feeding channel 1081, and the bottom end of the ozone removal device 108 is fixedly connected with an activated carbon discharging channel 1083. The activated carbon feeding channel 1081 and the activated carbon discharging channel 1083 are both provided with shut-off valves. It can be understood that the activated carbon has strong reducing capacity and can reduce the excess ozone in the flue gas discharged by the third adsorption sub-tower 1063, avoiding the secondary pollution caused by the excess ozone discharged into the environment through the flue gas.

[0039] The specific working process of the embodiment is: in specific use, flue gas is discharged from the gas outlet end of the boiler 101, passes through the dust remover 103, the pre-cooler 104 and the water removal separator 105 in turn, and reaches the ozone adding point 102. The nitrogen monoxide concentration sensor 109 monitors the content of nitrogen monoxide in the flue gas, and controls the opening of the electromagnetic valve on the gas outlet pipeline of the ozone generator 107 according to the monitored content of nitrogen monoxide, so that after the ozone generator 107 adds ozone to the ozone adding point 102, the volume ratio of ozone to nitrogen monoxide in the flue gas is greater than 1:1, so that after the nitrogen monoxide is converted into nitrogen dioxide by the ozone, the flue gas still maintains a proper amount of ozone. The flue gas then enters the first adsorption sub-tower 1061, the second adsorption sub-tower 1062 and the third adsorption sub-tower 1063 in turn, the molecular sieve adsorbs N02 in the flue gas, and after adsorption, the molecular sieve is discharged through the bottom end of the first adsorption sub-tower 1061, the second adsorption sub-tower 1062 and the third adsorption sub-tower 1063. At the same time, the ozone inhibits the occurrence of disproportionation reaction, but cannot completely inhibit the generation of N0 by the disproportionation reaction, and the ozone will decompose. Therefore, ozone is added again at the ozone adding point 102 between the first adsorption sub-tower 1061 and the second adsorption sub-tower 1062 and between the second adsorption sub-tower 1062 and the third adsorption sub-tower 1063, so that the volume ratio of ozone to nitrogen monoxide in the flue gas entering the second adsorption sub-tower 1062 and the third adsorption sub-tower 1063 is kept greater than 1:1. Finally, the flue gas after removal of nitrogen oxides is discharged from the flue gas outlet end of the third adsorption sub-tower 1063, enters the ozone removal device, and the activated carbon filler in the ozone removal device reduces and decomposes the excess ozone, avoiding the overflow of excess ozone to the external environment.

[0040] Embodiment 2

[0041] Referring to Figures 3-4 The present application provides a countercurrent multi-stage adsorption denitration device, comprising a boiler 201 and an adsorption tower 206. A dust remover 203, a pre-cooler 204 and a water removal separator 205 are sequentially arranged on the pipeline between the flue gas outlet end of the boiler 201 and the flue gas inlet end of the adsorption tower 206. In the adsorption tower 206, the adsorbent adsorbs nitrogen oxides in the flue gas, thereby achieving the purpose of flue gas denitration. The dust remover 203 is used for removing dust in the flue gas. The pre-cooler 204 is used for cooling the flue gas to below 80℃, avoiding the decomposition of ozone due to excessively high flue gas temperature. The water removal separator is a cyclone type water removal separator, and the water removal separator 205 is used for removing water in the flue gas. It can be understood that, since the adsorbent adsorbs nitrogen oxides through pores, removing water in the flue gas can avoid the occupation of the pores of the adsorbent by water in the flue gas, thereby preventing the adsorption capacity of the adsorbent for nitrogen oxides from being reduced.

[0042] The adsorption tower 206 comprises 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. The gas inlet end of the adsorption tower 206 is connected to the flue gas outlet end of the water separator 205 through a pipeline, and an ozone dosing point 202 is arranged at the gas inlet end of the adsorption tower 206. An ozone generator 207 is connected to the ozone dosing point 202 through a gas outlet pipeline. The gas outlet end of the ozone generator 207 is also connected to a pipeline extending between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section. A plurality of nozzles are arranged at intervals on the pipeline between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section. The ozone generator 207 generates ozone by ozone oxidation method or catalytic oxidation method or plasma method. The ozone is used to oxidize the nitrogen monoxide into nitrogen dioxide which is easy to be adsorbed by the adsorbent. The flue gas and the adsorbent in the adsorption tower 206 are countercurrently contacted. The adsorbent is fed into the adsorption tower 206 from the top end of the feeding pipe of the adsorption tower 206 and is discharged from the bottom end of the discharging pipe of the adsorption tower 206. Due to the resistance of the pipe, the flue gas will not be discharged from the pipe of the adsorption tower 206, but will be preferentially discharged from the gas outlet end with small resistance. The adsorbent in the adsorption tower 206 is molecular sieve, resin, silica gel or activated alumina. The molecular sieve, resin, silica gel and activated alumina all have strong N02 adsorption capacity but no reduction capacity, and thus will not reduce the ozone, so that the adsorption tower 206 can maintain an appropriate amount of ozone to inhibit the occurrence of disproportionation reaction.

[0043] An electromagnetic valve is arranged on the gas outlet pipeline of the ozone generator 207, and a nitrogen monoxide concentration sensor 209 is arranged at the gas inlet end of each adsorption section. The nitrogen monoxide concentration sensor 209 is used to monitor the concentration of nitrogen monoxide in the flue gas at the gas inlet end of each adsorption section. The ozone generator 207 controls the opening degree of the electromagnetic valve on the gas outlet pipeline, so that the volume ratio of ozone to nitrogen monoxide at the gas inlet end of each adsorption section is not less than 1:1, and the ozone is appropriately excessive to inhibit the occurrence of disproportionation reaction.

[0044] It should be noted that, since the first adsorption section adsorbs most of the nitrogen oxides in the flue gas, the ozone dosing amount at the gas inlet end of the first adsorption section, the gas inlet end of the second adsorption section and the gas inlet end of the third adsorption section decreases in turn. The ozone dosing amount decreases in turn, which can save the ozone dosing amount to the greatest extent while ensuring the adsorption of nitrogen oxides in the flue gas, and prevents the waste of ozone.

[0045] The flue gas outlet end of the adsorption tower 206 is fixedly connected with an air extraction pump 210, the flue gas outlet end of the air extraction pump 210 is fixedly connected with an ozone removal device, the ozone removal device comprises a removal tower 208, two layers of filter screens 2082 are arranged in the removal tower 208, activated carbon fillers are filled between the two layers of filter screens 2082, the top end of the ozone removal device 208 is fixedly connected with an activated carbon feeding channel 2081, the bottom end of the ozone removal device 208 is fixedly connected with an activated carbon discharging channel 2083, and a shut-off valve is arranged on the activated carbon feeding channel 2081 and the activated carbon discharging channel 2083. It can be understood that the activated carbon has strong reducing capacity and can reduce the excess ozone in the flue gas discharged from the third adsorption section, so that the secondary pollution caused by the excess ozone discharged into the environment through the flue gas is avoided.

[0046] The specific working process of the embodiment is as follows: in specific use, the flue gas is discharged from the gas outlet end of the boiler 201, sequentially passes through the dust remover 203, the pre-cooler 204 and the water separator 205, and reaches the ozone adding point 202, the nitrogen monoxide concentration sensor 209 monitors the content of nitrogen monoxide in the flue gas, and controls the opening degree of the electromagnetic valve on the gas outlet pipeline of the ozone generator 207 according to the monitored content of nitrogen monoxide, so that after the ozone generator 207 adds ozone to the ozone adding point 202, the volume ratio of ozone to nitrogen monoxide in the flue gas is greater than 1:1, the ozone converts the nitrogen monoxide into nitrogen dioxide, and the flue gas still maintains a proper amount of ozone, the flue gas first enters the first adsorption section of the adsorption tower 206, the molecular sieve adsorbs NO2 in the flue gas, the adsorbed molecular sieve is discharged through the bottom end of the adsorption tower 206, the ozone inhibits the occurrence of disproportionation reaction, but cannot completely inhibit the generation of NO, and the ozone will decompose, therefore, the ozone is added again at the ozone adding point 202 between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section, so that the volume ratio of ozone to nitrogen monoxide in the flue gas entering the second adsorption section and the third adsorption section is kept greater than 1:1, and finally the flue gas in which the nitrogen oxides are removed is discharged from the upper end of the adsorption tower 206, enters the ozone removal device, and the activated carbon fillers in the ozone removal device reduce and decompose the excess ozone, so that the excess ozone is prevented from overflowing into the external environment.

[0047] Embodiment 3

[0048] Reference Figures 5-6The application provides a countercurrent multi-stage adsorption denitration device, which comprises a boiler 301 and an adsorption tower 306, and a dust remover 303, a pre-cooler 304 and a water separator 305 are sequentially arranged on a pipeline between a flue gas outlet end of the boiler 301 and a flue gas inlet end of the adsorption tower 306. In the adsorption tower 306, nitrogen oxides in flue gas are adsorbed by an adsorbent, so that the purpose of flue gas denitration is achieved; the dust remover 303 is used for removing dust in the flue gas; the pre-cooler 304 is used for cooling the flue gas to below 80 DEG C, so as to avoid decomposition of ozone caused by excessively high temperature of the flue gas; and the water separator 305 is a cyclone water separator and is used for removing water in the flue gas. It can be understood that, since the adsorbent adsorbs nitrogen oxides through pores, removal of water in the flue gas can avoid occupation of the pores of the adsorbent by water in the flue gas, so that the adsorption capacity of the adsorbent for nitrogen oxides is reduced.

[0049] The adsorption tower 306 comprises a first adsorption sub-tower 3061, a second adsorption sub-tower 3062 and a third adsorption sub-tower 3063, the flue gas outlet end of the first adsorption sub-tower 3061 is connected with the flue gas inlet end of the second adsorption sub-tower 3062 through a pipeline, the flue gas outlet end of the second adsorption sub-tower 3062 is connected with the flue gas inlet end of the third adsorption sub-tower 3063 through a pipeline, and the flue gas inlet end of the first adsorption sub-tower 3061 is connected with the flue gas outlet end of the water separator 305 through a pipeline. The flue gas inlet end of each of the first adsorption sub-tower 3061, the second adsorption sub-tower 3062 and the third adsorption sub-tower 3063 is provided with an ozone adding point 302, and an ozone generator 307 is connected with the ozone adding point 302 through an outlet pipeline. The ozone generator 307 generates ozone through an ozone oxidation method or a catalytic oxidation method or a plasma method, and the ozone is used for oxidizing nitrogen monoxide into nitrogen dioxide which is easy to be adsorbed by the adsorbent. The adsorption tower 306 is used for countercurrent contact of the flue gas and the adsorbent. The adsorbent is fed into the adsorption tower 306 from a feeding pipe at the top end of the adsorption tower 306 and is discharged from a discharging pipe at the bottom end of the adsorption tower 306. Since the feeding pipe has resistance, the flue gas cannot be discharged from the adsorption tower 306 through the feeding pipe, but is preferentially discharged from the adsorption tower 306 through the flue gas outlet end with small resistance. The adsorbent in the adsorption tower 306 is molecular sieve, resin, silica gel or active alumina. The molecular sieve, the resin, the silica gel and the active alumina all have strong N02 adsorption capacity but no reduction capacity, and thus cannot reduce ozone, so that a proper amount of ozone can be maintained in the adsorption tower 306 to inhibit occurrence of disproportionation reaction.

[0050] The ozone generator 307 is provided with an electromagnetic valve on the gas outlet pipeline, and a nitrogen monoxide concentration sensor 309 is arranged at the gas inlet end of each adsorption sub-tower. The nitrogen monoxide concentration sensor 309 is used for monitoring the concentration of nitrogen monoxide in the flue gas at the gas inlet end of each adsorption sub-tower. The ozone generator 307 controls the opening degree of the electromagnetic valve on the gas outlet pipeline, so that the volume ratio of ozone to nitrogen monoxide at the ozone dosing point 302 is not less than 1:1, and the ozone is moderately excessive to inhibit the occurrence of disproportionation reaction.

[0051] It should be noted that, since the first adsorption sub-tower 3061 adsorbs most of the nitrogen oxides in the flue gas, the ozone dosing amount at the ozone dosing point 302 on the gas inlet end of the first adsorption sub-tower 3061, the ozone dosing point 302 at the gas inlet end of the second adsorption sub-tower 3062, and the ozone dosing point 302 at the gas inlet end of the third adsorption sub-tower 3063 decrease in turn. The ozone dosing amount decreases in turn, while ensuring the adsorption of nitrogen oxides in the flue gas, so that the ozone dosing amount can be saved to the maximum extent, and the waste of ozone is prevented.

[0052] The flue gas outlet end of the third adsorption sub-tower 3063 is fixedly connected with an air pump 310, and the flue gas outlet end of the air pump 310 is fixedly connected with an ozone removal device. The ozone removal device comprises a removal tower 308. A plurality of active carbon mesh plates 3081 are arranged at intervals in the removal tower 308. The two ends of each active carbon mesh plate 3081 are slidably connected with a limiting plate 3083, and the two ends of each active carbon mesh plate 3081 are connected with the bottom wall of a sliding groove formed in the limiting plate 3083 through a spring 3085. The limiting plate 3083 is installed on the inner wall of the removal tower 308. A plurality of through holes 3082 are uniformly distributed on each active carbon mesh plate 3081. The active carbon mesh plates 3081 are fixedly connected together through a connecting plate 3086. A cam 3084 is arranged in the removal tower 308. The cam 3084 is driven to rotate by a motor. The cam 3084 abuts against the connecting plate 3086. It can be understood that, 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, so as to drive the active carbon mesh plate 3081 to reciprocate up and down. The active carbon mesh plate 3081 is in full contact with ozone molecules, which is beneficial to the reduction and decomposition of excess ozone by the active carbon mesh plate 3081. Compared with the above-mentioned embodiment in which active carbon filler is used to remove excess ozone, the present embodiment can obviously reduce the wind resistance of the removal tower 308 and improve the economic operation benefit of the device.

[0053] The specific working process of the embodiment is as follows: in specific use, flue gas is discharged from the gas outlet end of the boiler 301, sequentially passes through the dust remover 303, the pre-cooler 304 and the water separator 305, reaches the ozone adding point 302, the nitrogen monoxide concentration sensor 309 monitors the content of nitrogen monoxide in the flue gas, and controls the opening of the electromagnetic valve on the gas outlet pipeline of the ozone generator 307 according to the monitored content of nitrogen monoxide, so that after the ozone generator 307 adds ozone to the ozone adding point 302, the volume ratio of ozone to nitrogen monoxide in the flue gas is greater than 1:1, so that after the ozone converts the nitrogen monoxide into nitrogen dioxide, the flue gas still maintains an appropriate amount of ozone, 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 molecular sieve adsorbs N02 in the flue gas, and after adsorption, the molecular sieve is discharged through the bottom end of the first adsorption sub-tower 3061, the second adsorption sub-tower 3062 and the third adsorption sub-tower 3063, meanwhile, the ozone inhibits the occurrence of disproportionation reaction, but cannot completely inhibit the generation of NO due to disproportionation reaction, and the ozone will decompose, therefore, the ozone adding 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 is added with ozone again, so that the volume ratio of ozone to nitrogen monoxide in the flue gas entering the second adsorption sub-tower 3062 and the third adsorption sub-tower 3063 is also greater than 1:1, finally, the flue gas from which the nitrogen oxides are removed is discharged from the third adsorption sub-tower 3063, enters the ozone removal device, the motor drives the cam 3084 to rotate, the cam 3084 intermittently extrudes the connecting plate 3086 and compresses the spring 3085, and drives the active carbon mesh plate 3081 to reciprocate up and down, so that the active carbon mesh plate 3081 is in full contact with ozone molecules, which is conducive to the reduction and decomposition of excess ozone by the active carbon mesh plate 3081, avoids that the excess ozone is directly discharged from the removal tower 308 without being in full contact with the active carbon due to the fact that the through hole 3082 formed in the active carbon mesh plate 3081 is too large, and compared with the above-mentioned embodiment which loads active carbon filler to remove excess ozone, the embodiment can obviously reduce the wind resistance of the removal tower 308.

[0054] Embodiment 4

[0055] Reference Figures 7-8The application provides a countercurrent multi-stage adsorption denitration device, which comprises a boiler 401 and an adsorption tower 406, and a dust remover 403, a pre-cooler 404 and a water separator 405 are sequentially arranged on a pipeline between a flue gas outlet end of the boiler 401 and a flue gas inlet end of the adsorption tower 406. In the adsorption tower 406, the adsorbent adsorbs nitrogen oxides in the flue gas, so that the purpose of flue gas denitration is achieved; the dust remover 403 is used for removing dust in the flue gas; the pre-cooler 404 is used for cooling the flue gas to below 80 DEG C, so as to avoid that the decomposition of ozone is caused by the excessively high temperature of the flue gas; the water separator is a cyclone water separator, and the water separator 405 is used for removing water in the flue gas. It can be understood that, since the adsorbent adsorbs nitrogen oxides through pores, the removal of water in the flue gas can avoid that the pores of the adsorbent are occupied by water in the flue gas, so that the adsorption capacity of the adsorbent for nitrogen oxides is reduced.

[0056] The adsorption tower 406 comprises 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. The flue gas outlet end of the water separator 405 is connected with the flue gas inlet end of the adsorption tower 406 through a pipeline, and the flue gas inlet end of the adsorption tower 406 is provided with an ozone adding point 402. The ozone generator 407 is connected with the ozone adding point 402 through an outlet pipeline. The outlet end of the ozone generator 407 is also connected with a pipeline extending between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section, and a plurality of nozzles are arranged on the pipeline between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section. The ozone generator 407 generates ozone by an ozone oxidation method or a catalytic oxidation method or a plasma method. The ozone is used for oxidizing nitrogen monoxide into nitrogen dioxide which is easy to be adsorbed by the adsorbent. The flue gas and the adsorbent in the adsorption tower 406 are countercurrently contacted. The adsorbent is fed into the adsorption tower 406 from the top end of the feeding pipeline of the adsorption tower 406 and is discharged from the bottom end of the discharging pipeline of the adsorption tower 406. Since the pipeline has resistance, the flue gas cannot be discharged from the adsorption tower 406 through the pipeline, but is preferentially discharged from the adsorption tower 406 through the outlet end with small resistance. The adsorbent in the adsorption tower 406 is molecular sieve, resin, silica gel or active alumina. The molecular sieve, the resin, the silica gel and the active alumina all have strong N02 adsorption capacity, but do not have reduction capacity, and thus will not reduce ozone, so that the adsorption tower 406 can maintain appropriate ozone to inhibit the occurrence of disproportionation reaction.

[0057] The ozone generator 407 is provided with an electromagnetic valve on the gas outlet pipeline, and the nitrogen monoxide concentration sensor 409 is arranged at the gas inlet end of each adsorption section. The nitrogen monoxide concentration sensor 409 is used for monitoring the concentration of nitrogen monoxide in the flue gas at the gas inlet end of each adsorption section. The ozone generator 407 controls the opening degree of the electromagnetic valve on the gas outlet pipeline, so that the volume ratio of ozone and nitrogen monoxide at the gas inlet end of each adsorption section is not less than 1:1, and the ozone is kept in moderate excess to inhibit the occurrence of disproportionation reaction.

[0058] 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 gas inlet end of the first adsorption section, the gas inlet end of the second adsorption section, and the gas inlet end of the third adsorption section decreases in turn. The ozone dosage decreases in turn, which can maximize the saving of ozone dosage while ensuring the adsorption of nitrogen oxides in the flue gas, and prevents the waste of ozone.

[0059] The flue gas outlet end of the adsorption tower 406 is fixedly connected with an air pump 410, and the flue gas outlet end of the air pump 410 is fixedly connected with an ozone removal device. The ozone removal device comprises a removal tower 408. A plurality of activated carbon net plates 4081 are arranged at intervals in the removal tower 408. The two ends of the activated carbon net plate 4081 are slidably connected with a limiting plate 4083, and the two ends of the activated carbon net plate 4081 are connected with the bottom wall of a sliding groove formed in the limiting plate 4083 through a spring 4085. The limiting plate 4083 is installed on the inner wall of the removal tower 408. The activated carbon net plate 4081 is uniformly provided with through holes 4082. The activated carbon net plates 4081 are fixedly connected with each other through a connecting plate 4086. A cam 4084 is arranged in the removal tower 408. The cam 4084 is driven to rotate by a motor. The cam 4084 abuts against the connecting plate 4086. It can be understood that, 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, driving the activated carbon net plate 4081 to reciprocate up and down, so that the activated carbon net plate 4081 is in full contact with ozone molecules, which is conducive to the reduction and decomposition of excess ozone by the activated carbon net plate 4081. Avoiding that the excess ozone is directly discharged out of the removal tower 408 without being in full contact with the activated carbon due to the through holes 4082 formed in the activated carbon net plate 4081 being too large. Compared with the above-mentioned embodiment of filling activated carbon filler to remove excess ozone, the present embodiment can significantly reduce the wind resistance of the removal tower 408 and improve the economic operation benefit of the device.

[0060] The specific working process of the embodiment is: in specific use, flue gas is discharged from the gas outlet end of the boiler 401, and reaches the ozone adding point 402 after sequentially passing through the dust remover 403, the pre-cooler 404 and the water removal separator 405. The nitrogen monoxide concentration sensor 409 monitors the content of nitrogen monoxide in the flue gas, and controls the opening degree of the electromagnetic valve on the gas outlet pipeline of the ozone generator 407 through the monitored content of nitrogen monoxide, so that after the ozone generator 407 adds ozone to the ozone adding point 402, the volume ratio of ozone and nitrogen monoxide in the flue gas is greater than 1:1, so that after the ozone converts the nitrogen monoxide into nitrogen dioxide, the flue gas still maintains an appropriate amount of ozone. The flue gas first enters the first adsorption section of the adsorption tower 406, the molecular sieve adsorbs N02 in the flue gas, and after adsorption, the molecular sieve is discharged through the bottom end of the adsorption tower 406. At the same time, the ozone inhibits the occurrence of disproportionation reaction, but cannot completely inhibit the generation of N0, and the ozone will decompose, so that the ozone is added again at the ozone adding point 402 between the first adsorption section and the second adsorption section and between the second adsorption section and the third adsorption section, so that the volume ratio of ozone and nitrogen monoxide in the flue gas entering the second adsorption section and the third adsorption section is also greater than 1:1. Finally, the flue gas in which the nitrogen oxides are removed is discharged from the upper end of the adsorption tower 406, enters the ozone removal device, and the motor drives the cam 4084 to rotate, the cam 4084 intermittently extrudes the connecting plate 4086 and compresses the spring 4085, and drives the active carbon mesh plate 4081 to reciprocate up and down, so that the active carbon mesh plate 4081 is in full contact with ozone molecules, which is conducive to the reduction and decomposition of excess ozone by the active carbon mesh plate 4081, avoiding that the excess ozone is directly discharged from the removal tower 408 because the through hole 4082 opened on the active carbon mesh plate 4081 is too large and the excess ozone does not fully contact with the active carbon. Compared with the above-mentioned embodiment of filling the active carbon filler to remove the excess ozone, the embodiment can obviously weaken the wind resistance brought by the removal tower 408.

[0061] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the application.

[0062] In the description of the application, references to "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" mean that a particular feature, structure, material, or characteristic being described is included in at least one embodiment or example of the application. The appearances of the phrases "in one embodiment", "in some embodiments", "in an example", "in a specific example", or "in some examples" in various places in the specification are not necessarily all referring to the same embodiment or example.

[0063] It is apparent that the described embodiments are only some, but not all, of the embodiments of the present application. Reference to "an embodiment" or "some embodiments" in this specification means that a particular feature, structure, material or characteristic described in connection with the embodiment is included in at least one embodiment or example of the application. The appearances of the phrase "in one embodiment" or "in some embodiments" in various places in the specification are not necessarily all referring to the same embodiment or example, nor are they necessarily mutually exclusive or alternative embodiments or examples. It will be apparent to those skilled in the art from this disclosure that the described embodiments can be combined with other embodiments in a manner not specifically mentioned in the above description. All such possible combinations are within the scope of the present application.

[0064] Although embodiments of the application have been illustrated and described, it will be clear to those of ordinary skill in the art that various changes, modifications, substitutions, and alterations can be made to the embodiments without departing from the principles and spirit of the application. The scope of the application is limited only by the claims and their equivalents.

Claims

1. A countercurrent 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 countercurrent 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 inlets of each adsorption section are connected to the ozone generator via outlet pipes. Solenoid valves are installed on the outlet pipes, and each adsorption section's inlet is equipped with a nitric oxide concentration sensor. 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. An ozone dosing point is provided at the air inlet end of the adsorption tower. The ozone generator is connected to the ozone dosing point through an air outlet pipe. The air outlet end of the ozone generator is also connected to a pipe extending between the first and second adsorption sections and between the second and third adsorption sections. Multiple nozzles are spaced apart on the pipe located between the first and second adsorption sections and between the second and third adsorption sections.

2. The countercurrent 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 countercurrent multi-stage adsorption denitrification device according to claim 1, characterized in that: A dust collector is installed on the pipeline between the boiler and the precooler. The flue gas outlet of the boiler is connected to the flue gas inlet of the dust collector through a pipeline, and the flue gas outlet of the dust collector is connected to the flue gas inlet of the precooler through a pipeline.

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

5. A countercurrent multi-stage adsorption denitrification method, characterized in that, The method is applied to the countercurrent multi-stage adsorption denitrification device as described in any one of claims 1-4, specifically including: 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 from bottom to top and comes into countercurrent contact with the adsorbent flowing from top to bottom. The adsorbent is a molecular sieve, silica gel, resin, or activated alumina. The adsorbent adsorbs nitrogen dioxide from the flue gas. The adsorption tower includes multiple adsorption sections. A nitric oxide concentration sensor monitors the nitric oxide concentration in the flue gas at the inlet of each adsorption section. A moderate excess of ozone is introduced to ensure that the volume ratio of ozone to nitric oxide in the flue gas is greater than 1:

1. The ozone converts the nitric oxide 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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