CN111228991A - A denitrification system for flue gas denitrification using chlorine dioxide and packed towers - Google Patents

Abstract

The invention discloses a denitrification system using chlorine dioxide and a packing tower for denitrification of flue gas. The system includes a packing tower, a chlorine dioxide supply system and a nitric acid supply system. A packing layer is arranged inside the packing tower, and a flue gas inlet of the packing tower is provided. It is arranged above the packing layer, and the flue gas outlet is arranged below the packing layer. The chlorine dioxide supply system transports chlorine dioxide to the top of the packing layer of the packed tower through the chlorine inlet pipe, and the nitric acid supply system also transports the nitric acid through the acid inlet pipe. Above the packing layer, chlorine dioxide in the packing layer oxidizes NO in the flue gas, and nitric acid simultaneously absorbs the oxidation products. The invention can solve the problem of low denitrification efficiency in the prior oxidation technology, and combines chlorine dioxide and nitric acid in a packed tower for denitration, which has good economic and social benefits.

Description

A denitrification system for flue gas denitrification using chlorine dioxide and packed towers

technical field

The invention relates to the technical field of flue gas denitrification, in particular to a denitration system for denitrifying flue gas by utilizing chlorine dioxide and a packing tower.

Background technique

Coal-fired power generation, steelmaking in steel mills, and other processes that use coal and petroleum as heat sources are one of the main sources of elevated nitrogen oxides in the environment. In order to reduce the impact on the environment, various manufacturers have adopted many methods to reduce the emission of nitrogen oxides in the combustion tail gas ("flue gas" in the present invention), that is, denitrification treatment of the flue gas. In general flue gas, NO often accounts for about 90% of the total nitrogen oxides, but NO is insoluble in water, so it is difficult to remove it by water washing or nitric acid neutralization, which is also the current difficulty of flue gas denitrification. . Existing flue gas denitrification technologies mainly fall into two categories, one is catalytic reduction, and the other is oxidation. Compared with the catalytic reduction method, the oxidation method has the advantages of simple process and low cost in theory, so it has become the current research and development direction in the field of flue gas denitrification. ClO2 is a green oxidant with strong oxidizing ability, and at the same time, the cost is relatively low, so it is a better choice to apply it in the oxidation absorption method for denitrification. Publication number CN109718653A, titled "a flue gas desulfurization and denitrification device and method" discloses a technology for denitrification using chlorine dioxide, and patents with publication numbers CN110624385A, CN106975337A, CN105771577A, CN105169913A, etc., also disclose the use of two The technology of flue gas denitrification by chlorine oxide. In the mentioned patent technology, the technical idea of denitrification adopts the idea of "oxidizing NO in flue gas by chlorine dioxide to become high-valence nitrogen oxides that are easy to react with nitric acid, and then wash and absorb them with alkaline solution. "Technical route. However, in actual production, the denitration effect of this technical route is not very good. Analysis of the reasons shows that this technical route has oxidation space and absorption space in the process, and the existing process does not pay attention to the connection between the two spaces, resulting in poor removal of nitrogen oxides in flue gas.

SUMMARY OF THE INVENTION

In order to solve the above-mentioned technical problems, the present invention provides a denitration system using chlorine dioxide and a packed tower for flue gas denitration, which can solve the technical problems of poor chlorine dioxide denitration effect and high cost in the prior art. Its content is:

A denitration system using chlorine dioxide and a packed tower for flue gas denitration, characterized in that the denitration system includes a packed tower, a chlorine dioxide supply system, and a nitric acid supply system, and a packing layer is arranged inside the packed tower, and the flue gas of the packed tower is provided with a packing layer. The inlet is arranged above the packing layer, and the flue gas outlet is arranged below the packing layer. The chlorine dioxide supply system transports chlorine dioxide into the packed tower through the chlorine inlet pipe, and the nitric acid supply system transports the nitric acid into the packed tower through the acid inlet pipe. The distributor of chlorine dioxide in the tower is set above the packing layer, the distributor of nitric acid in the tower is also set above the packing layer, the flue gas enters the packing layer from above the packing layer, and the chlorine dioxide and nitric acid also pass from the packing layer. The top of the layer enters the packing layer. In the space between the packings, chlorine dioxide oxidizes NO in the flue gas, and nitric acid absorbs the oxidation products at the same time. After the flue gas exits the packing layer, it exits the packed tower from the flue gas outlet. Flow to the acid tank at the bottom of the column.

Preferably, wherein the chlorine dioxide distributor is located below the nitric acid distributor.

Preferably, the chlorine dioxide and the flue gas enter the packing layer in the same direction.

Preferably, wherein the nitric acid is sprayed into the packing layer.

Preferably, a nitric acid cooling device is provided on the acid inlet pipe of the nitric acid supply system.

Preferably, wherein the liquid recycle in the acid tank is used in the nitric acid supply system.

The content of the present invention is specifically described as follows:

(1) Theoretical basis of the present invention

1. The reason for the poor denitration effect of the existing oxidative denitration technology is:

(1) The applicant believes that in the gaseous state, there is an equilibrium relationship when NO is converted to NO ₂ :

2NO ₂ ↔ O ₂ + 2NO ①

At higher temperature, lower pressure and lower NO concentration, NO is not easily converted into NO ₂ , or the converted NO ₂ is immediately converted into NO. In this way, even if the NO in the flue gas can be oxidized by oxidants such as chlorine dioxide, because the concentration of NO in the flue gas is very low, the formula ① moves to the right, and even if the NO in the flue gas is oxidized, there will be a larger proportion in the end. NO exists. This is verified experimentally in the comparative example.

2ClO ₂ +4NO →4NO2+Cl ₂ ②

2NO ₂ → O ₂ + 2NO ③

According to the equilibrium relationship (formula ①), if the concentration of NO in the flue gas is low (NO in the actual flue gas generally does not exceed 300mg/m ₃ ), even if NO is oxidized to high-valence NO ₂ (formula ②), the According to the above formula ③, NO ₂ is converted back to NO, and a large proportion of NO will also exist in the final flue gas. This is also the reason why the denitration effect of oxidants (including chlorine dioxide) in the existing oxidation denitration technology is not high. Of course, in the prior art, the denitration effect can be improved by increasing the input amount of the oxidant, which will inevitably increase the cost greatly.

(2) In the prior art, the link of NO oxidation in the flue gas is separated from the high-valence nitrogen oxide absorption environment.

As mentioned above, the prior art adopts the method of "oxidizing NO in flue gas by chlorine dioxide to become high-valence nitrogen oxides that are easy to react with lye, and then wash and absorb with alkaline solution". technical route. Based on the above analysis, in this technical route, due to the separation of oxidation and absorption, although the NO in the flue gas has undergone oxidation, due to the equilibrium conversion relationship between NO and NO2, when the flue gas is in contact with the absorption liquid, there will still be a large proportion. The NO of the absorbing liquid cannot be adsorbed, and the final result is that the denitration effect of the flue gas is not good.

2. The difference between the present invention and the prior art is:

(1) In the system, the absorbent of the oxidation product is changed from alkaline solution to nitric acid.

The main product of NO oxidation in the flue gas is NO2, and the absorption of the oxidation product is mainly the absorption of NO2. The technical route of absorption in the prior art is that NO2 reacts with soluble lye to generate nitrate and (or) nitrite, thereby removing NO2 from flue gas.

Existing theories reveal that NO2 can dissolve in water:

3NO ₂ + H2O = 2HNO ₃ + NO ④

Thus water can act as an absorbent for NO2. However, pure water absorption has shortcomings in absorption speed and efficiency. Existing theories and experiments show that the absorption capacity of nitric acid for NO2 is significantly higher than that of water. For example, Geng Jiao et al. pointed out in "Research on Absorption of NO2 by Water and Dilute Nitric Acid" that when 15% nitric acid is used as the absorbent, the absorption efficiency of NO2 increases with The absorbed dose increased significantly. This is because NO2 is more soluble in nitric acid than water. Moreover, it has been reported in the literature that when the concentration of nitric acid is greater than 12%, the solubility of NO in nitric acid increases significantly, and the oxidizing property of nitric acid solution also increases gradually with the increase of nitric acid concentration, both of which are beneficial to the oxidation of NO to NO2 for re-oxidation. Reacts with water, resulting in a significant increase in absorption capacity. However, it has been verified by experiments that when the mass concentration of nitric acid exceeds 50%, especially 60%, the nitrogen oxides detected by the flue gas terminal will increase instead, which shows that high concentration nitric acid is not conducive to being used as the absorbent of the present invention. Experiments show that the optimal concentration of nitric acid is 10-30%.

In this application, combined with the oxidation of chlorine dioxide, nitric acid can not only be used as an absorbent for NO2, but also can synergistically absorb NO, thereby saving the use of oxidants and having greater economical efficiency.

4NO+2ClO ₂ =Cl ₂ +4NO ₂ ②

3NO ₂ +H2O=2HNO ₃ +NO ④

Cl ₂ + NO + H ₂ O = NO ₂ +2HCl ⑤

2NO+ClO ₂ +H ₂ O=NO ₂ +HNO ₃ + HCl ⑥

2HNO ₃ + 3NO = 2HNO ₂ + N ₂ O ₄ ⑦

2ClO ₂ + 4HNO ₂ = 4HNO ₃ + Cl ₂ ⑧

2ClO ₂ + 2N ₂ O ₄ + H ₂ O = 4HNO ₃ + Cl ₂ ⑨

In the prior art in the art, the reason for not using nitric acid as the absorbent is that, first, the technology of absorbing NO with nitric acid is generally used under conditions with higher NO content, such as the NO absorption technology used in the nitric acid preparation process; Second, as mentioned above, in the art, NO2 is converted back to NO when the flue gas is absorbed, and the content of NO2 in the flue gas is not high.

(2) In the present invention, the NO oxidation link in the flue gas and the absorption link of the high-valence nitrogen oxides are almost synchronized, that is, the NO is absorbed immediately after the oxidation.

In the present invention, the oxidant (chlorine dioxide), the flue gas and the absorbent (nitric acid) simultaneously enter the packing layer and descend in the irregular gaps between the packings. While going down, chlorine dioxide oxidizes NO in the flue gas, and the oxidation product is in direct contact with the absorbent (nitric acid), and the oxidation product is immediately absorbed. Since the oxidation and absorption are synchronized in the nitric acid environment, each reactant will be carried out according to the above formulas ②, ④-⑨, and formula ③ has no chance to occur. Therefore, the technical means of oxidizing NO in the flue gas and absorbing it immediately is to solve the problem of NO in the flue gas. The key to the technical problem of low denitration efficiency is also the technical means of the present invention that is different from the prior art.

(3) Compared with the prior art, the chlorine dioxide remaining in the absorption liquid in the present invention can be reused.

In the present invention, the absorption liquid is nitric acid, the reaction product is also mainly nitric acid, and chlorine dioxide can exist stably in the nitric acid. When the chlorine dioxide reacts with NO in the flue gas and there is residual, the chlorine dioxide will remain in the nitric acid, and can be contacted with the flue gas again through the circulation system to oxidize the NO in the flue gas. In the prior art, the absorbing liquid is soluble lye, such as CN109718653A, CN110624385A, CN106975337A, CN105771577A, CN105169913A and other patents all adopt lye as absorbent.

The disadvantage of using soluble lye as the absorbent is that the chlorine dioxide that is not involved in the reaction after oxidation will undergo a neutralization reaction and thus be consumed, and a corresponding part of the lye will also be consumed.

ClO ₂ + OH ^- = ClO ₃ ^- + H ₂ O

In this way, the present invention has a very obvious cost advantage over the prior art. In addition, sodium chlorite and nitric acid can be used as raw materials for the preparation of chlorine dioxide, and nitric acid can directly use the denitration product in the present invention, so that the cost of the present invention is lower.

(2) Packed tower

The packed tower in the prior art is one of the important equipments for gas-liquid mass transfer in chemical production. The tower body is often a vertical cylinder, and there is a packing support plate at the lower part of the tower. The packing is used as a contact member between the gas and liquid phases, or is placed on the support plate in a random stack or in a structured way, and a packing pressure plate is placed above the packing. , press the packing, and then install the liquid distributor above. The working principle of the packed tower is: the liquid is sprayed onto the packing from the upper part through the liquid distributor, and flows down along the surface of each packing; the gas is fed from the bottom of the tower, is in a countercurrent state with the liquid, and is in contact with the liquid in the gap of the packing. quality.

The packed tower described in the present invention is basically the same as the aforementioned packed tower in structure, and also includes tower shell, packing support plate, packing, liquid distributor, etc. However, the working principle of the packed tower of the present invention is different from the prior art. In the invention, the flue gas and the nitric acid pass through the filler in a gas-liquid co-current manner, and in addition, the chlorine dioxide is also co-current with the nitric acid. The working principle of the packed tower of the present invention is as follows: flue gas enters from the upper part of the packed tower, passes through the gap between the packings, and exits the packed tower from the outlet of the flue gas; chlorine dioxide enters the packing layer from the upper part of the packing layer; nitric acid also enters the packing layer from the upper part of the packing layer Enter the packing layer, pass through the gap between the packings, and finally flow to the bottom of the packed tower. The bottom of the packed tower is used as an acid tank to collect and store the reacted acid. The flue gas, chlorine dioxide and nitric acid contact and collide in the irregular void channels of the filler to complete the aforementioned reaction and absorption.

The first reason why the present invention adopts the co-current flow of flue gas and nitric acid is that the media involved in the packed tower of the present invention are: flue gas, chlorine dioxide and nitric acid, which are different from traditional packed towers, which only involve two kinds of gas and one liquid. The reaction involved between the medium and the packing is also different from the pure mass transfer reaction between the traditional packing. As mentioned above, the reactions between various substances mainly include the oxidation reaction of chlorine dioxide to NO in flue gas and the absorption reaction of nitric acid to high-valence nitrogen oxides. The co-current flow can ensure the reaction time of each reaction.

The second reason for adopting the gas-liquid co-current flow is that the exhaust gas of chemical plants, power plants, steel mills, etc. has a large amount of flue gas, complex components, and equipment with high mass transfer effect, but it is difficult to adapt to this occasion. However, in the present invention, the flue gas and the liquid adopt a co-current route, which can not only meet the process requirements, but also reduce the air resistance and save the cost, so that the traditional packed tower can be applied to the flue gas treatment occasion.

The fillers in the present invention can be those involved in the prior art, such as Raschig ring fillers, Pall ring fillers, stepped ring fillers, saddle-shaped fillers, rectangular-saddle-shaped fillers, etc. in bulk fillers, and even spherical fillers can be used ; Grid packing, corrugated packing, etc. in structured packing. Considering the process environment, it is best to use materials that are resistant to oxidation and acid and alkali, such as ceramics, stainless steel, PE, PP, PVC and other plastics, stainless steel, etc.

The liquid distributor corresponds to the nitric acid distributor in the present invention, and the function is the same as that of the traditional packed column. The types of distributors are tube type, double-layer tube type, trough type, disc type, impact type, nozzle type, pagoda type, lotus type and so on. According to the diameter of the packed tower, the nitric acid in the present invention can be used in any of the above types; considering that the gas and liquid are in a co-current state, this component can also be omitted, and the liquid is directly injected into the packing layer through the acid inlet pipe.

(3) Chlorine dioxide and chlorine dioxide supply system

1. Preparation of chlorine dioxide

The chlorine dioxide in the present invention may be a chlorine dioxide-containing aqueous solution, a chlorine dioxide-containing gas, or a mixture of a chlorine dioxide-containing aqueous solution and a chlorine dioxide gas.

The preparation of chlorine dioxide is the content of the prior art. As disclosed in the patent with publication number CN 209362207 U: the chlorine dioxide generating device applied to the disinfection treatment of drinking water and sewage is mainly a chlorine dioxide preparation device using sodium chlorate and hydrochloric acid as raw materials. The solution and the hydrochloric acid solution enter the chlorine dioxide generating device in a certain proportion, and a chemical reaction occurs inside the device to produce reaction products such as chlorine dioxide, chlorine gas, sodium chloride and water. The raw materials for producing chlorine dioxide are sodium chlorate and hydrochloric acid; publication number CN110624385A also discloses a production method for chlorine dioxide denitration: a low-temperature denitration method of sodium chlorite solution, the oxidant adopts 25% sodium chlorite Aqueous solution, using acid solution as activator, continuously adding the acid solution to the sodium chlorite solution during use, pumping it into the flue gas inlet pipe, and spraying the oxidant into the flue gas through the atomizing spray gun , the sodium chlorite reacts with the acid solution to generate chlorine dioxide, and the chlorine dioxide generated by the evaporation of flue gas heat will oxidize nitrogen monoxide to nitrogen dioxide, and the sodium hydroxide sprayed by the alkali washing tower will be oxidized absorption of nitrogen oxides. The raw material is sodium chlorite and acid; Publication No. CN105771577A discloses an improved method for preparing chlorine dioxide: carry out according to the following steps: (1) with mass concentration of 15~18% sodium chlorate solution and mass concentration of 31 % industrial hydrochloric acid is used as the raw material, the raw material is preheated to 55~70℃, and then a metering pump is used to mix the sodium chlorate solution and industrial hydrochloric acid according to the volume ratio of industrial hydrochloric acid:sodium chlorate solution=1:(1~1.2). They are respectively sent into the two V-shaped pipes with an included angle of 55°~65° in the three-way pipe, and the mixing reaction is carried out in the third pipe; (2) After the mixing reaction occurs in the pipe, a mixture containing strong oxidant ClO2 is obtained, The gas-liquid mixture is evenly distributed through the distribution spray device at the outlet end of the pipe, and the gas-liquid mixture is dispersed into a fine mist. Nitrogen oxides (NO) undergo a redox reaction with ClO2, and low-valence nitrogen oxides (NO) are oxidized to high-valence nitrogen oxides (NO2), and the oxidized products are absorbed by lye. The raw materials also used sodium chlorate and hydrochloric acid.

The preparation of large-scale chlorine dioxide is usually obtained by electrolyzing salt water to obtain sodium chlorate, and then reacting sodium chlorate with hydrochloric acid (or sulfuric acid) under specific conditions.

In a word, all the technical means for preparing chlorine dioxide in the prior art can be applied in the present invention as a technical feature of the present invention.

When the present invention is applied, the chlorine dioxide generator and corresponding raw materials can be directly purchased from the market to obtain chlorine dioxide.

In the present invention, chlorine dioxide can be prepared from sodium chlorite and dilute nitric acid, and dilute nitric acid generally refers to nitric acid with a mass concentration of less than 65%. Compared with the prior art, by using dilute nitric acid instead of sulfuric acid or hydrochloric acid in the present invention, the out-of-stock product can be applied to the denitration raw material, which can optimize the process and save costs. But through experimental verification, when the mass concentration of nitric acid exceeds 30%, the output of its chlorine dioxide will obviously decline instead, so in each scheme of the present invention, generally take the mass concentration of nitric acid to be less than 30%.

The amount of chlorine dioxide should be determined according to the amount of NO in the flue gas. According to the formula ②④⑤⑥, 1 mole of chlorine dioxide can oxidize 5 moles of NO. Therefore, theoretically, the ratio of the amount of input chlorine dioxide per unit time to the amount of NO in flue gas per unit time is 3:5. According to formula ⑦, nitric acid can play the role of auxiliary oxidation, and the input amount of chlorine dioxide can be smaller, such as 1:2, 1:3, or even smaller, which has a cost advantage compared to the existing technology.

2. Chlorine dioxide supply system

The chlorine dioxide supply system includes chlorine dioxide generator, booster pump, valve, chlorine inlet pipe, chlorine dioxide distributor, etc. The function is to supply chlorine dioxide to the turbulent ball tower and distribute the chlorine dioxide in the flue gas.

The chlorine dioxide distributor is a device that evenly distributes the chlorine dioxide produced by the chlorine dioxide generator in the flue gas flowing through the packed tower. When chlorine dioxide is supplied in liquid or gas-liquid mixed form in the system, various liquid nozzles, liquid atomizing nozzles and special liquid distributors disclosed in the aforementioned patents can be used. When the chlorine dioxide is supplied in gaseous form, gas distributors, gas nozzles, etc. disclosed in the prior art can be used.

(4) Nitric acid and nitric acid supply system

The nitric acid in the present invention refers to an aqueous solution of HNO3. Nitric acid is an absorbent of NO2. In terms of absorption effect, the higher the concentration, the better the absorption effect. However, when the concentration of nitric acid exceeds a certain value, such as the mass fraction of 50-70%, nitric acid becomes extremely easy volatilize, forming a new source of pollution. Therefore, the requirement for the concentration of nitric acid used in the present invention is that the concentration of nitric acid does not exceed 60%, preferably 10--30%.

The amount of nitric acid used in the present invention should be determined according to specific process parameters. Generally speaking, the nitric acid used is suitable to ensure that the NO2 obtained by oxidation in the process can be fully absorbed.

In the present invention, nitric acid can be used as an absorbent for nitrogen oxides, and can also be used as a raw material for chlorine dioxide preparation. Therefore, chlorine dioxide is prepared from sodium chlorite and nitric acid, which is beneficial to environmental protection (reducing the amount of chloride ions in the process). use). In addition, in the present invention, the nitric acid further selects an acid solution containing an absorption product, which can save costs (the absorption product is also used for the preparation of the oxidant).

The nitric acid supply system of the present invention includes a nitric acid tank, a pressure pump, a valve, an acid inlet pipe, a nitric acid distributor, and the like. The function is to transport nitric acid to the packing layer. After nitric acid absorbs the oxidized product, the concentration becomes larger and the absorption capacity is stronger. Therefore, in a preferred solution, the nitric acid in the acid tank is reused to simplify the process and save costs; , its volatility increases, which will lead to the leakage of relatively concentrated nitric acid with the flue gas. Therefore, in a preferred solution, a nitric acid cooling device is set on the nitric acid circulation pipeline to cool the nitric acid.

Beneficial effects of the present invention:

1. Nitric acid can be recycled as an absorbent, saving costs.

2. Provide guarantee for both the oxidation and absorption of NO in nitric acid, and the oxidation and absorption are almost synchronized, which improves the denitration efficiency.

3. Using chlorine dioxide combined with packed tower and nitric acid for flue gas denitrification, an unexpected effect was achieved and the denitration efficiency was improved.

Instruction drawings

Figure 1: Schematic diagram of the denitration system of the best embodiment.

best practice

In conjunction with accompanying drawing 1, the present invention is described:

The packed tower is a cylinder with a diameter of 0.8m, a tower height of 5m, a wall thickness of 8mm, and is made of 304L stainless steel. The flue gas inlet 1 is opened at the top of the packed tower, and a 90° conical solid nozzle 2 is installed in the upper part of the tower. The nozzle 2 is a nitric acid distributor, and the nozzle 2 is connected with the acid inlet pipe 3 of nitric acid; the position 0.5 meters below the nozzle 2 A chlorine dioxide distributor 4 is arranged at the place, and the chlorine dioxide distributor 4 is a 120° solid cone atomizing nozzle, and the distance from the packing layer 6 is 0.5m. The chlorine dioxide distributor 4 is connected to the chlorine inlet pipe 5 of chlorine dioxide, and the chlorine inlet pipe 5 is connected to the chlorine dioxide generator 10. The pipeline is also provided with a gas booster pump 11 and a flow regulating valve 12. The lower part of the chlorine dioxide distributor 4 is a packing layer 6 , the packing is a ceramic Raschig ring, the layer height of the packing layer 6 is 2 m, and the packing is supported by the packing support plate 7 . The flue gas outlet 8 is opened at the lower 0.8m position of the packing support plate 7 and at a distance of 0.6m from the bottom of the tower. The bottom of the packed tower is used as an acid tank 9, and nitric acid with a mass concentration of 20% is put in before the tower starts to operate. The pipeline of the acid inlet pipe 3 of nitric acid is provided with a booster pump 13 and a flow regulating valve 14, and the other end of the pipeline is connected to the acid tank 9 at the bottom of the packed tower.

The flue gas is taken from the sintering flue gas from the sintering workshop of a steel plant. The parameters of the initial flue gas are: flue gas temperature of 137°C, flue gas humidity of 0.01-0.03%, NO content of 181 mg/m ³ , and flue gas flow of 900 m ³ /h.

The chlorine dioxide generator 10 selects the QKJ-2000 type chlorine dioxide generator of Jinan Qili Environmental Protection Technology Co., Ltd., the raw materials are sodium chlorite and hydrochloric acid (30%), the output is a gas-liquid mixture, and the unit produces chlorine dioxide The amount is 2000g/h.

The flue gas enters the packed tower through the flue gas inlet 1 and flows downward from the top of the tower; open the nitric acid regulating valve 14 and the booster pump 13, the nitric acid in the acid tank 9 is transported to the nozzle 2 through the acid inlet pipe 3, and passes through the regulating valve 14 Adjust the flow of nitric acid to ensure that the input amount per hour is not less than 20kg; start the chlorine dioxide generator 10, open the flow control valve 11 and the booster pump 12, and the chlorine dioxide generated by the chlorine dioxide generator 10 passes through the chlorine inlet pipe. 5 is sent to the chlorine dioxide distributor 4. Adjust the flow rate of chlorine dioxide through the regulating valve 11, so that the input amount of pure chlorine dioxide is not less than 600g/h. The flue gas, nitric acid and chlorine dioxide simultaneously enter the packing layer 6 from above, and flow downward along the gaps of the packing. In the space between the fillers, the NO in the flue gas is oxidized by chlorine dioxide, and the nitric acid simultaneously absorbs the oxidation products. After leaving the packing layer 6, the flue gas exits the packed tower from the flue gas outlet 8, and the liquid flows into the acid liquid tank 9 at the bottom of the tower.

Measured at the flue gas outlet 8 of the packed tower, the NO content was 32, 35, 38, 41, etc., ranging from 30-45 mg/m ³ .

Claims (6)

1. a denitrification system utilizing chlorine dioxide and packed tower to carry out flue gas denitration, is characterized in that, denitration system comprises packed tower, chlorine dioxide supply system, nitric acid supply system, the inside of packed tower is provided with packing layer, and the The flue gas inlet is set above the packing layer, and the flue gas outlet is set below the packing layer. The chlorine dioxide supply system transports chlorine dioxide into the packing tower through the chlorine inlet pipe, and the nitric acid supply system transports the nitric acid into the packing through the acid inlet pipe. In the tower, the distributor of chlorine dioxide in the tower is set above the packing layer, the distributor of nitric acid in the tower is also set above the packing layer, the flue gas enters the packing layer from above the packing layer, and the chlorine dioxide and nitric acid are also Entering the packing layer from above the packing layer, in the space between the packings, chlorine dioxide oxidizes NO in the flue gas, and nitric acid absorbs the oxidation products at the same time. Then it flows to the acid tank at the bottom of the tower. 2. The denitration system according to claim 1, wherein the chlorine dioxide distributor is located below the nitric acid distributor. 3. The denitration system according to claim 1, wherein the chlorine dioxide and the flue gas enter the packing layer in the same direction. 4. The denitration system according to claim 1, wherein the nitric acid enters into the packing layer by spraying. 5. The denitration system according to claim 1, wherein a nitric acid cooling device is provided on the acid inlet pipe of the nitric acid supply system. 6. The denitration system for flue gas denitrification utilizing chlorine dioxide and packed towers according to claims 1-5, wherein the liquid recycling in the acid tank is applied in the nitric acid supply system.

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