CN105833725A - Synchronous denitration complexing agent regeneration process based on flue gas ammonia-process desulfurization - Google Patents

Abstract

The invention discloses a synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization, which comprises the steps of sending the flue gas into a concentration tower for contact reaction with the concentrated liquid in the tower after being pressurized, and sending the flue gas out of the concentration tower into an absorption tower, The flue gas enters the absorption tower from the flue gas inlet in the middle of the absorption tower, passes through at least one layer of photochemical reaction layer, packing layer and spray layer arranged on the upper part of the tower in turn, and reversely contacts and reacts with the circulating absorption liquid, and then is discharged from the flue gas outlet; The circulating absorption liquid sprayed from the spray layer on the upper part of the absorption tower passes through the packing layer, the photochemical reaction layer and the flue gas reverse contact reaction in turn, then enters the bottom of the absorption tower, and then is pumped to the photocatalytic regeneration reaction system for regeneration and then enters the regeneration slurry tank, and then add ammonia water, complexing agent, oxalic acid and ferrous sulfate in the regenerated slurry tank as a circulating absorption liquid and send it back to the spray layer on the upper part of the absorption tower to spray into the tower. The invention has the advantages of simple process, low operating cost, low energy consumption, simple control, good denitrification effect and good quality of by-products.

Description

A synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization

technical field

The invention relates to a flue gas ammonia synchronous desulfurization and denitrification process in the field of environmental protection, in particular to a synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization.

Background technique

my country's flue gas desulfurization and denitrification technology started late, but with the introduction of stricter environmental protection measures, flue gas desulfurization and denitrification has become imperative. The Ministry of Science and Technology of the People's Republic of China has included the development of flue gas simultaneous desulfurization and denitrification technology in the "863" major research plan. In recent years, my country's research on integrated desulfurization and denitrification technologies has been relatively active. Although most new technologies are still in the stage of laboratory development and pilot testing, some technologies have been greatly improved. At the same time, the desulfurization and denitrification technology can realize desulfurization and denitrification in the same system, which has the following characteristics: ① The equipment is simplified and the floor area is small. The traditional combined flue gas desulfurization and denitrification process generally installs a denitrification device such as selective catalytic reduction (SCR) or selective non-catalytic reduction (SNCR) in front of the dust collector to achieve combined desulfurization and denitrification. This hierarchical treatment method not only has a lot of equipment, but also occupies a large area. It is not as simple as the equipment that realizes desulfurization and denitrification at the same time in the same system. ②Less infrastructure investment and low production cost. Simultaneous flue gas desulfurization and denitrification technology can achieve desulfurization and denitrification in the same system, which does not require a large amount of infrastructure investment like traditional processes, which reduces production and operation costs. ③High degree of automation and convenient management. The integration of desulfurization and denitrification in the same system brings convenience to equipment management. In order to meet the current and future needs of air pollution control, the development of new technologies and equipment for simultaneous desulfurization and denitrification has gradually become one of the development directions in the field of air pollution control.

The traditional wet desulfurization technology can remove SO: more than 90%, and then combine it with the SCR dry process. The two processes work independently due to different technologies, and there are problems of large investment and high cost. As early as 1986, Sada and his collaborators discovered that some metal complexes, such as Fe(II)EDTA, can react rapidly with NO, which can promote the absorption of nitrides. These have prepared the conditions for the design of the wet FGD+metal complex process. The wet FGD+metal complex process is to add ferrous ions to the non-acidic solution to form ferrous amino acid chelates such as Fe(II)EDTA. NO can be combined with it to form a ferrous nitrosyl complex, thereby accelerating the absorption rate of NO. At the same time, the ferrous nitrosyl complex can react with dissolved SO ₂ in the solution to generate N ₂ , a series of N, S compounds etc. However, the Fe(II)EDTA washing solution will be gradually inactivated, resulting in complex regeneration of the absorption solution, and this process is still in the experimental stage. In this regard, some researchers explored the simultaneous removal of NO and SO ₂ in flue gas by renewable ferrous cysteine solution through experiments, and found that the removal rates were 82.3% and 94.4% respectively in 20 minutes. Ferrous cysteine complexation method can not only remove NO and SO ₂ , but also cystine can be reduced to cysteine so that the reaction can be cycled, showing a certain application potential.

Iron-based and cobalt-based complexes have better complexing effects on NO. Although Fe(II)EDTA and ferrous cysteine have shown certain application potential in simultaneous desulfurization and denitrification, due to the high price of EDTA and cysteine, they bring great cost pressure to simultaneous desulfurization and denitrification. Therefore, seeking efficient regeneration of complexing agents, converting NO in the liquid phase, releasing complexing agents, and establishing a stable and effective process cycle are the keys to achieving simultaneous desulfurization and denitrification.

Contents of the invention

The invention provides a synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization with simple process, low operating cost, low energy consumption, simple control, good denitrification effect and good quality of by-products, which solves the existing problems in the prior art. problems such as low regeneration efficiency.

The technical scheme includes that after the flue gas is pressurized, it is sent to the concentration tower and the concentrated liquid in the tower is contacted and reacted. Discharge from the top; the partly reacted concentrated liquid drawn from the bottom of the concentration tower is sent to the ammonium sulfate crystallization system after iron removal by the iron removal system, and the flue gas enters the absorption tower from the flue gas inlet in the middle of the absorption tower, and passes through the upper part of the tower in turn. At least one layer of photochemical reaction layer, filler layer and spray layer are discharged from the flue gas outlet after the reverse contact reaction with the circulating absorption liquid; the circulating absorption liquid sprayed from the upper part of the absorption tower passes through the packing layer, photochemical reaction, After the layer and the flue gas reverse contact and react, it enters the bottom of the absorption tower, and then is pumped to the photocatalytic regeneration reaction system for regeneration, and then ammonia water, complexing agent, oxalic acid and ferrous sulfate are added to the regeneration slurry tank as a circular absorption The liquid is returned to the spray layer on the upper part of the absorption tower and sprayed into the tower.

Control the total concentration of Fe(II)EDTA+Fe(III) in the circulating absorption liquid sprayed into the absorption tower to be 0.015-0.05mol/L, the concentration of oxalate ion to be 0.09-0.3mol/L, and the pH of the circulating absorption liquid to be 5.0～5.5.

The absorption liquid drawn from the bottom of the absorption tower into the concentration tower is mixed with the concentrated liquid drawn from the concentrated liquid circulation pump at the bottom of the concentration tower, and then sent to the upper part of the concentration tower to be circulated and sprayed out.

The concentrated solution drawn from the bottom of the concentration tower and entering the iron removal system is first sent to the concentrated sedimentation tank for precipitation, the suspension at the bottom of the concentrated sedimentation tank is sent to the photocatalytic regeneration reaction system, and the clarified liquid in the upper stage is sent to the iron removal system.

The photochemical reaction layer is composed of multi-layer mesh-structured light strips, and the light strips are connected to the power supply through terminal posts.

The porosity of the light strip with the mesh structure is 0.6-0.9.

In the photochemical reaction layer in the upper section of the absorption tower, the light strips of adjacent two layers of network structure are controlled to emit light alternately.

The photocatalytic regeneration reaction system is a photocatalytic reactor provided with a light source.

The iron removal system is an electrolytic iron removal reactor.

The present invention adds oxalic acid to the circulating absorption liquid in the double-tower synchronous desulfurization and denitrification process of the existing compound ammonia-Fe(II) EDTA complexing agent, and the oxalic acid can react with the iron ions and ferrous ions in the absorption liquid to form ferric oxalate and Ferrous oxalate. Ferric oxalate and ferrous oxalate are salts of oxalate ions with iron and ferrous ions.

In aqueous solution, ferrous oxalate is easily oxidized to ferric oxalate in the presence of oxygen. Ferric oxalate can form stable ferric oxalate complexes in aqueous solution. These complexes have good photochemical activity and have relatively active redox properties under ultraviolet light irradiation, in which Fe ³⁺ is reduced to Fe ²⁺ , the oxalate is oxidized under the action of photocatalysis and generates H ₂ O ₂ . The Fe ²⁺ produced by photoreduction reacts with H ₂ O ₂ to produce ·OH and Fe ³⁺ , and Fe ³⁺ will re-form iron oxalate complex with oxalate ions. When there are excessive oxalate ions and H ₂ O ₂ in the solution, hydroxyl radical·OH will be continuously generated, and the quantum yield of the generated·OH radical can reach about 1. OH free radical is a strong oxidizing agent, which can quickly oxidize and absorb and NO. Oxalate ions are continuously consumed as the reaction progresses, and finally carbon dioxide is generated. The inventors utilize the characteristic of ferric oxalate to generate ·OH free radicals under the action of photocatalysis to oxidize the absorbed NO into nitrate for final removal, and at the same time reduce the oxidized Fe ³⁺ to Fe ²⁺ . The increase of Fe ²⁺ concentration in the absorption liquid is beneficial to the formation of Fe(II)EDTA and the regeneration of complexing agent. The above reaction process is a complex multi-reaction process. Studies have shown that adding oxalic acid to the circulating absorption solution to generate ferrous oxalate combined with light reaction can not only realize the removal of part of nitrogen oxides, but also replace the iron filings method to realize the complexing agent. The regeneration of Fe (II) EDTA, in the process of the present invention, when ferrous oxalate and Fe (II) EDTA complexing agent are used simultaneously, not only can replace traditional iron filings method, also can reduce Fe (II) EDTA complexing agent usage, effectively reducing system operating costs.

Based on the above principles, in order to improve the denitrification efficiency and the regeneration efficiency of the circulating absorption liquid, the inventor installed a photochemical reaction layer under the original packing layer on the upper part of the absorption tower, and created light conditions in the tower, which has three functions: a. Flue gas from bottom to top When passing through the photochemical reaction layer, a chemical absorption reaction occurs with the circulating absorption liquid flowing through the layer from top to bottom, and the sulfur dioxide and nitrogen oxides in the flue gas are absorbed, and there is also a side reaction: the complexed absorbent in the absorption liquid Fe(II)EDTA, Oxidized by the oxygen in the flue gas to Fe(III)EDTA, b, Since the photochemical reaction layer has a multi-layer network structure lamp strip, which provides effective lighting conditions, the absorption liquid contains Under the action of photocatalysis, a chemical reaction occurs, and the two molecules Finally, one molecule of Fe ²⁺ and one hydroxyl radical·OH will be generated, and the generated hydroxyl radical·OH will further oxidize the and NO; the absorbed nitrogen oxides are oxidized, and the oxidized Fe ³⁺ is reduced, which has a synchronous regeneration effect; c, the multi-layer network structure of the light strip is similar to the filler structure, which is conducive to the circulation of the absorption liquid and the flue gas Evenly distributed and mixed, and prolong the gas-liquid contact time between the flue gas and the circulating absorption liquid, which is beneficial to the renewal of the gas-liquid interface. The circulating absorption liquid and the flue gas are regenerated while reacting, further improving the removal effect.

In order to ensure the regeneration effect, it is preferable that the porosity of the lamp strip with a network structure is 0.6-0.9. If it is too large, the specific surface area for gas-liquid contact will be too small, resulting in low tower efficiency. If it is too small, the gas phase resistance will increase. The light strips adjacent to the two-layer network structure emit light alternately, so that the absorption liquid mainly undergoes regeneration reactions in the light-emitting one-layer light strip area, and then mainly performs absorption reactions in the non-luminous one-layer light strip area, ensuring the completeness of each reaction. Efficiently carry out, and finally achieve the purpose of efficient desulfurization and denitrification. Experiments show that the control method using alternate light emission is more efficient and energy-saving than the control method of full light emission.

The photocatalytic regeneration reaction system in the present invention is a photocatalytic reactor, and the photocatalytic reactor can use natural light to react during the day, and in the case of insufficient natural light conditions, it can turn on its own light source to carry out photocatalytic reaction, and the light source It is a multi-layer light strip with a cross-arranged mesh structure. After the reacted absorption liquid is sent to the photocatalytic reactor, the iron oxalate complex in the circulating absorption liquid undergoes a photochemical redox reaction under light conditions, Fe ³⁺ is reduced to Fe ²⁺ , and at the same time, a strong oxidizing hydroxyl The free radical OH oxidizes the absorbed NO into nitrate for final removal. Fe ³⁺ is reduced to Fe ²⁺ , the concentration of Fe ²⁺ in the solution increases, breaking the complexation balance between Fe ³⁺ and EDTA, the concentration of Fe(III)EDTA decreases, and the concentration of Fe(II)EDTA increases, realizing Fe (II) The regeneration of EDTA uses a photocatalytic reactor to replace the iron filing method of the traditional iron filing tower, which reduces the cost of iron removal, avoids the large consumption of iron filings, and the occurrence of problems such as excessive concentration of iron ions in the absorption liquid, and improves the The quality of by-products.

Further, part of the concentrated solution drawn from the bottom of the concentration tower and sent to the iron removal system is first sent to the concentrated sedimentation tank for precipitation, and after standing for precipitation, the suspension at the bottom of the concentrated sedimentation tank is sent to the photocatalytic regeneration reaction system , the clarified liquid in the upper section is sent to the iron removal system. Concentration and sedimentation tanks are used to concentrate the concentrated solution into layers, and the suspension with high iron oxalate content at the bottom is used as oxalic acid to be added to the circulating absorption solution by the photocatalytic regeneration reaction system, while the clarified solution in the upper section is sent to the iron removal system for iron removal. It can not only reduce the consumption of iron in the solution, but also reduce the burden of the iron removal system, improve the iron removal efficiency of the concentrate, and reduce the iron content in by-products.

In the present invention, the amount of ammoniacal liquor, complexing agent, oxalic acid and ferrous sulfate in the regenerated slurry tank can be adjusted according to the ammonium sulfate concentration, Fe(II)EDTA+Fe(III) concentration, oxalate ion concentration and solution in the circulating absorption liquid. Replenish according to the requirements of the pH value, in line with the principle of replenishing if it is damaged.

Beneficial effect:

(1) Oxalic acid is added to the synchronous desulfurization and denitrification process of flue gas ammonia water and Fe(II) EDTA. Since oxalic acid is a strong reducing agent, oxalic acid can inhibit the oxygen in the flue gas from oxidizing Fe ²⁺ , to ensure that the absorption liquid has a relatively high concentration of Fe(II)EDTA, which is beneficial to denitrification; due to the low market cost of oxalic acid, it can save energy and reduce consumption, reduce operating costs, and at the same time reduce the use of EDTA in complexing agents and loss amount.

(2) A photochemical reaction layer is set on the upper part of the absorption tower, so that the circulating absorption liquid in reverse contact with the flue gas is regenerated while absorbing in the photochemical reaction layer, and the denitrification efficiency of the flue gas is improved; The luminous control method has higher reaction efficiency, is more energy-saving, and also improves the service life of the light strip.

(3) Precipitate and stratify the concentrated solution by using the concentrated sedimentation tank to increase the recovery rate of iron, reduce the burden on the iron removal system, and improve the quality of by-products.

(4) The suspension at the bottom of the concentrated sedimentation tank has a high concentration of ferric oxalate and enters the photocatalytic regeneration reaction system, which improves the regeneration effect and denitrification efficiency.

(5) By adopting the method of the present invention, the absorbed NO can be oxidized and converted, and the denitrification complexing agent can be reduced and regenerated, and the denitrification efficiency can reach more than 50%. The invention has simple process, easy operation and good reliability.

Description of drawings

Fig. 1 process flow chart of the present invention.

Figure 2 is a schematic diagram of the absorption and oxidation process of circulating absorption liquid and flue gas in the presence of oxalic acid.

Fig. 3 is a schematic diagram of the regeneration reaction process of circulating absorption liquid under light conditions.

Among them, 1-concentration tower, 2-absorption tower, 2.1-packing layer, 2.2-spray layer, 2.3-washing layer, 2.4-photochemical reaction layer, 3-iron removal system, 4-photocatalytic regeneration reaction system, 5- Regeneration slurry tank, 6-concentrated sedimentation tank, 7-crystallization system.

detailed description

Example:

Referring to Fig. 1, in a flue gas desulfurization system, the flue gas volume is about 14-16Nm ³ /h, the SO ₂ concentration: 800-1200mg/Nm ³ , and the NOx concentration (mainly NO): 300-400mg/Nm ³ . Desulfurization uses a twin-tower process. The flue gas enters the upper part of the concentration tower 1 after being pressurized, and flows from top to bottom. During the flow process, it contacts with the concentrated liquid (containing ammonia water) extracted from the bottom of the tower and sent to the top of the concentration tower by the circulation pump of the concentration tower 1, and undergoes chemical absorption reaction to absorb sulfur dioxide and nitrogen oxides in the flue gas. At the same time, most of the particles in the flue gas are washed down.

The physical parameters and related composition of the concentrate are as follows:

pH value: 5.0~5.5;

Ammonium sulfate concentration: 20-45% (mass percentage);

EDTA-Fe(II)+EDTA-Fe(III) concentration: 0.045～0.15mol/L;

Oxalic acid concentration: 0.27～0.9mol/L;

Absorption liquid temperature: 50-55°C.

After the flue gas flows to the middle part of the concentration tower 1, it is introduced into the middle part of the absorption tower 2 through the communicating flue. In the absorption tower 2, the flue gas passes through at least one layer of photochemical reaction layer 2.4 (two layers in this embodiment), the packing layer from bottom to top. 2.1 and spray layer 2.2 flow to the top of the tower, and finally discharged to the chimney after being further washed by the washing layer 2.3.

The physical parameters and related composition of the circulating absorption liquid are as follows:

pH value: 5.0~5.5;

Ammonium sulfate concentration: 5-15% (mass percentage);

EDTA-Fe(II)+EDTA-Fe(III) total concentration: 0.015～0.05mol/L;

Oxalic acid concentration: 0.09～0.3mol/L;

Absorption liquid temperature: 50°C.

The rising flue gas undergoes a chemical absorption reaction with the circulating absorption liquid sprayed from top to bottom in the photochemical reaction layer 2.4 (see Figure 2 for the principle of the reaction process), and the sulfur dioxide and nitrogen oxides in the flue gas are absorbed; The effect of oxygen carried by the gas, and there are side reactions at the same time, that is, Fe(II), Fe(II)EDTA and Fe(II)EDTA in the circulating absorption liquid Oxidized by oxygen in flue gas to Fe(III), Fe(III)EDTA and The oxidized Fe(III) further reacts with oxalate ions in the circulating absorption liquid to form iron oxalate complexes Fe(C ₂ O ₄ ) ⁺ , and etc.; because the photochemical reaction layer 2.4 has a regeneration effect on the circulating absorption liquid, the absorbed nitrogen oxides and oxidized Fe(III)EDTA are reduced thereupon, and have a synchronous regeneration effect (see Figure 3 for the principle of the reaction process).

The main steps of circulating the absorbing liquid for photocatalytic reaction are as follows:

In an air-saturated solution, under acidic conditions and It further reacts with dissolved oxygen O ₂ in water to finally form H ₂ O ₂ .

Fe ²⁺ +H ₂ O ₂ →Fe ³ +OH ^- + OH (4)

2mol After the photocatalytic reaction, 1 mol of Fe ²⁺ is generated, 1 mol of oxalate ion is consumed, and 1 mol of hydroxyl radical·OH is provided to further oxidize the absorbed NO. Due to the consumption of oxalate, the generation of Fe ²⁺ breaks the Fe(III) The complexing equilibrium concentration of EDTA generates Fe(II)EDTA, that is, Fe(II)EDTA is regenerated.

The photochemical reaction layer 2.4 is composed of multi-layer network structure light strips, which are connected to the power supply through terminal posts, and the porosity of the network structure is controlled at 0.6-0.9. During operation, it is preferable that the light strips with two adjacent layers of network structure in the photochemical reaction layer 2.4 on the upper part of the absorption tower 2 emit light alternately.

In the lower part of the absorption tower, the absorption liquid is drawn out from the circulating liquid absorption liquid in the lower part of the tower by the regeneration slurry pump and enters the photocatalytic regeneration reaction system 4 (a photocatalytic reactor equipped with a light source), which can pass sunlight and assist light irradiation, in the circulating absorbing fluid For photocatalytic reaction: 2mol After the photocatalytic reaction, 1 mol of Fe ²⁺ is generated, 1 mol of oxalate ion is consumed, and 1 mol of hydroxyl radical · OH is provided to further oxidize the absorbed NO. Due to the consumption of oxalate and Fe ³⁺ , the concentration of Fe ²⁺ in the solution increases, breaking the complexation balance between Fe ³⁺ and EDTA, the concentration of Fe(III)EDTA decreases, and the concentration of Fe(II)EDTA increases, realizing the complexation Mixture Fe (II) EDTA regeneration.

Draw 6-9L of slurry from the bottom of absorption tower 2 per hour to combine with part of the concentrated liquid extracted from the bottom of concentration tower 1, and then spray it into the upper part of concentration tower 1, and draw 2-3L of slurry from the bottom of concentration tower 1 to enter concentration sedimentation tank 6 every hour. The precipitation time is 30-40 hours, and the supernatant enters the iron removal system 4 (that is, the electrolytic iron removal reactor, such as the patent application number is 201520886784.2, and the invention name is "a directional flow electrolysis device", which can also be used for other electrolytic iron removal devices. The electrolysis reactor based on the principle), the suspension with a higher iron oxalate content in the lower layer is sent back to the photocatalytic regeneration reaction system 4.

The slurry drawn from the top of the photocatalytic regeneration reaction system 4 is sent to the regeneration slurry tank 5, and the consumed ammonia water, complexing agent (Fe(II)EDTA), and oxalic acid are added to the regeneration slurry tank 5 to meet the relevant physical properties of the circulating absorption liquid According to the parameter requirements, it is finally sent to the spray layer 2.2 and sprayed into the absorption tower 2; the concentrated solution after iron removal by the iron removal system 3 enters the crystallization system 7 to produce ammonium sulfate by-products, and the remaining solution contains EDTA, which can be sent back to the photocatalytic regeneration reaction System 4.

The process of the present invention involves existing conventional reactions such as ammonia desulfurization, Fe(II)EDTA complex denitrification and regeneration reaction, the principle of which is the same as that of the prior art, and will not be described in detail here. The removal efficiency of NOx compounds in the flue gas treated by the above method is over 50%, and the removal efficiency of SO ₂ is over 90%.

Claims (9)

1. A synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization, including flue gas pressurized and sent to the concentration tower to contact with the concentrated liquid in the tower, and the flue gas from the concentration tower is sent to the absorption tower and from the tower The circulating absorption liquid sprayed from the upper spraying layer is discharged from the top of the absorption tower after the reverse contact reaction; the partially reacted concentrated liquid drawn from the bottom of the concentration tower is sent to the ammonium sulfate crystallization system after iron removal by the iron removal system. The flue gas enters the absorption tower from the flue gas inlet in the middle of the absorption tower, passes through at least one photochemical reaction layer, packing layer and spray layer arranged on the upper part of the tower in turn, and is discharged from the flue gas outlet after reverse contact with the circulating absorption liquid; The circulating absorption liquid sprayed from the upper spray layer of the absorption tower passes through the packing layer, the photochemical reaction layer and the flue gas reverse contact reaction, and then enters the bottom of the absorption tower, and then is pumped to the photocatalytic regeneration reaction system for regeneration and then enters the regeneration slurry tank , and then add ammonia water, complexing agent, oxalic acid and ferrous sulfate in the regenerated slurry tank as a circulating absorption liquid and send it back to the spray layer on the upper part of the absorption tower to spray into the tower. 2. A kind of synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 1, is characterized in that, in the circulation absorbing liquid that is sprayed into the absorption tower, Fe(II)EDTA+Fe(III ) total concentration is 0.015-0.05mol/L, the concentration of oxalate ion is 0.09-0.3mol/L, and the pH value of the circulating absorption liquid is 5.0-5.5. 3. A kind of synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 1 or 2, it is characterized in that, the absorption liquid that enters the concentration tower drawn from the bottom of the absorption tower is concentrated with the bottom of the concentration tower The concentrated liquid drawn out by the liquid circulation pump is mixed and sent to the upper part of the concentration tower to be circulated and sprayed out. 4. A kind of synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 1, it is characterized in that, the concentrated solution that enters the iron removal system that is drawn from the bottom of the concentration tower is first sent to the concentrated sedimentation tank Precipitation, the suspension at the bottom of the concentrated sedimentation tank is sent to the photocatalytic regeneration reaction system, and the clarified liquid in the upper section is sent to the iron removal system. 5. A kind of synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 1 or 2, characterized in that, the photochemical reaction layer is composed of a multi-layer network structure of light strips, the The light strip is connected to the power supply through the binding post. 6 . The synchronous denitrification and complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 5 , wherein the porosity of the network-shaped light strip is 0.6-0.9. 7. A kind of synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 5 or 6, it is characterized in that, control the lamp of adjacent two layers of network structure in the photochemical reaction layer of absorption tower upper section The bands glow alternately. 8. The synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization according to claim 1, 3 or 4, wherein the photocatalytic regeneration reaction system is a photocatalytic reactor provided with a light source. 9. A synchronous denitrification complexing agent regeneration process based on flue gas ammonia desulfurization as claimed in claim 1, characterized in that the iron removal system is an electrolytic iron removal reactor.