WO2023070756A1

WO2023070756A1 - Ammonia desulfurization method and ammonia desulfurization apparatus

Info

Publication number: WO2023070756A1
Application number: PCT/CN2021/130671
Authority: WO
Inventors: 罗静; 徐天奇; 刘凡
Original assignee: 江南环保集团股份有限公司; 江苏新世纪江南环保股份有限公司
Priority date: 2021-10-25
Filing date: 2021-11-15
Publication date: 2023-05-04
Also published as: CN113856441A; CN113856441B

Abstract

An ammonia desulfurization method. A flue gas containing SO₂ and SO₃ is desulfurized by means of an ammonia desulfurization apparatus, ammonia being used as a first desulfurizing agent and a metal alkaline desulfurizing agent being used as a second desulfurizing agent. The desulfurization method can synergistically remove SO₂ and SO₃ from flue gas, and achieve improvements in resolving flue gas tailings and aerosol generation.

Description

Ammonia desulfurization method and ammonia desulfurization device

technical field

The invention belongs to the technical field of environmental protection, and in particular relates to a method and a device for desulfurizing flue gas containing _SO2 and _SO3 based on the ammonia method.

Background technique

Currently there are many desulfurization technologies, among which wet desulfurization technology is the most widely used. Common flue gas wet desulfurization technologies include limestone-gypsum method, alkali method, ammonia method, etc.

In the limestone-gypsum wet desulfurization process, limestone or lime is used as the desulfurization absorbent. The limestone can be crushed, ground into powder, and mixed with water to make an absorption slurry. When lime is used as absorbent, lime powder can be stirred with water to make absorption slurry. In the desulfurization tower, the absorption slurry can be contacted and mixed with the flue gas, and the _SO2 in the flue gas can react with the calcium carbonate or calcium hydroxide in the slurry to generate calcium sulfite, and the calcium sulfite can be further combined with the oxidized The air reacts to form calcium sulfate (commonly known as gypsum), which is eventually discharged.

The ammonia desulfurization technology of flue gas belongs to the new clean technology of circular economy, which has obvious advantages such as high desulfurization efficiency, no secondary pollution, resource recovery of sulfur dioxide, and meeting the requirements of circular economy. In China, it has been successfully applied to a desulfurization device with a single flue gas volume equivalent to a 500MW generating set, and has developed rapidly. After entering the desulfurization tower, the SO2 _- containing flue gas can fully contact and react with the ammonia-containing solution, so that most of the _SO2 in the flue gas can be absorbed, and the net flue gas can be discharged through the top chimney of the desulfurization tower. The ammonium sulfite solution obtained by absorbing _SO2 in the flue gas can form an ammonium sulfate slurry with a certain solid content after oxidation, concentration and crystallization. Next, the ammonium sulfate slurry can undergo solid-liquid separation, drying process and packaging to become a solid ammonium sulfate product.

Compared with calcium desulfurization, the advantages of ammonia desulfurization can include:

(1) The SO ₂ removed from the flue gas can be converted into ammonium sulfate fertilizer, turning waste into treasure. Among them, there is basically no waste water, solid waste, and no secondary pollution, which is in line with the concept of environmental protection.

(2) No CO ₂ is produced, low-carbon and environmentally friendly.

(3) The desulfurizer can be readily available liquid chemical raw materials, which can avoid solid limestone mining, transportation and by-product gypsum, and the operating environment at the production site can be better.

The ammonia desulfurization process can be mainly divided into three processes: absorption, oxidation, and concentration (crystallization). First, ammonium sulfite solution can be used as the absorbing liquid to absorb sulfur dioxide in the flue gas to obtain a mixed solution of ammonium sulfite and ammonium bisulfite, which becomes ammonium sulfite solution after neutralization by adding ammonia. Ammonium sulfite can be oxidized to ammonium sulfate by passing oxidizing air through the ammonium sulfite solution. The ammonium sulfate solution is concentrated, crystallized, solid-liquid separated and dried to obtain the final solid product ammonium sulfate.

In the process of ammonia desulfurization, the three processes of absorption, oxidation and concentration actually affect each other. For a long time, in order to ensure the absorption efficiency, in the absorption liquid, the content of ammonium sulfite and free ammonia is higher, while the content of ammonium sulfate is lower. While this is good for absorption, it is bad for oxidation and concentration, which can lead to ammonia escape, aerosol generation, and smoke tailing during absorption.

The following technical problems exist in the ammonia desulfurization process of flue gas:

(1) About ammonia escape and aerosol generation

In the ammonia desulfurization process, since ammonia is easy to volatilize, when there is free ammonia in the absorption liquid, ammonia, SO ₂ and SO ₃ can exist in the gas phase at the same time, so it is easy to form the mist of ammonium sulfite and ammonium sulfate. With this fog as the core, the saturated water vapor in the flue gas can condense on these fogs to form dense white fog. On the one hand, it can cause ammonia loss, and on the other hand, it can cause secondary pollution. This is a key technical problem that has not been well resolved in the past for a long time in the ammonia desulfurization process.

(2) About the recovery of ammonia entrained in the tail gas

As just mentioned, ammonia is volatile. In the traditional countercurrent contact desulfurization tower, no matter it is a spray tower, packed tower or plate tower, in order to ensure the desulfurization efficiency and final discharge index, the pH value of the solution is the highest at the contact point at the top of the absorption zone, and the SO in the gas phase ₂ has the lowest concentration and ammonia has the highest concentration in the gas phase. This means that the amount of ammonia overflowing the desulfurization tower with the tail gas is large. This will not only cause waste loss of ammonia, but also cause new pollution.

Patent document CN106000043A proposes a single-tower six-stage cascade purification desulfurization and dust removal integrated device with ultra-low emissions, which includes an oxidation section, a concentration section, an absorption section, a purification water washing section, a demister section, a partition, and a wet electricity section. The electric section further removes the tiny mist droplets carried in the flue gas after demisting through electrostatic adsorption, so as to ensure that the flue gas can still achieve standard emission when the flue gas working conditions change, and it is used as an insurance measure for this device. This process has large investment and high operating costs, and there is room for further improvement in the effect of wet electricity control of ammonia escape and aerosol.

Patent document CN106474895A proposes a method and device for deep removal of sulfur oxides in flue gas, wherein the flue gas is sequentially subjected to primary desulfurization and secondary desulfurization from bottom to top, and in the primary desulfurization, calcium carbonate slurry and flue gas For desulfurization reaction, in the secondary desulfurization, sodium-based desulfurizer, magnesium-based desulfurizer, potassium-based desulfurizer or calcium hydroxide are atomized in the form of solution or slurry, sprayed into the flue gas, and desulfurization reaction is carried out. Among them, by adjusting the new Calcium carbonate slurry is supplemented to control the pH value of the circulating slurry, and the concentration of sulfur oxides in the flue gas at the outlet of the desulfurization tower is controlled by adjusting the desulfurizing agent solution or slurry of the secondary desulfurization.

Patent document CN101053744A proposes a segmented sodium-calcium double-alkali desulfurization process and device, in which calcium-based desulfurization and sodium-alkali flue gas desulfurization are combined in one reactor, so that the flue gas is pre-desulfurized by calcium-based, and then Sodium base is used for fine desulfurization to ensure discharge requirements.

The above two methods add secondary desulfurization on the basis of limestone-gypsum wet desulfurization to improve the desulfurization effect, but still have the disadvantages of calcium desulfurization.

Patent document CN112708475A proposes a process combining ammonia desulfurization and alkali desulfurization, wherein the combination of ammonia desulfurization and alkali desulfurization is applied to remove _H2S in coal gas instead of SO in flue gas ₂ , where the reaction conditions and process flow for removing H ₂ S from coal gas are completely different from those for removing SO ₂ from flue gas.

Contents of the invention

Aiming at the problem of aerosol and ammonia escape, various solutions have been proposed in the prior art, such as wet electricity, multi-stage water washing, multi-stage demisting or a suitable combination of these measures. The inventors of the present application have found in their research that the source of aerosol and ammonia slip generation during absorption has not been recognized in these prior methods, and these prior methods are also unable to generate aerosol and ammonia slip generation during absorption. source to solve the problem. The applicant found in the research that in these existing methods, the concern is how to eliminate the escaped ammonia and the generated aerosol during the absorption process. Solving the existing understanding problems according to the current understanding level will make the number of desulfurization towers more and more, and the system will become more and more complex. However, such a desulfurization tower not only has room for improvement in treatment effect, but also has high investment and operation costs.

The object of the present invention is to propose an ammonia-based method and device for desulfurization of flue gas containing SO ₂ and SO ₃ , wherein SO ₂ and SO ₃ in the flue gas can be removed synergistically, which can solve the problem of flue gas Improvements in gas tailing and aerosol generation.

The first aspect of the present invention relates to a method for removing _SO by ammonia desulfurization and solving flue gas tailing and aerosol, which is characterized in that ammonia is used as the main desulfurizer, and metal alkaline desulfurization is added to the ammonia desulfurization device at the same time agent as an auxiliary desulfurization agent.

The second aspect of the present invention relates to an ammonia desulfurization method, which is characterized in that the flue gas containing _SO2 and _SO3 is desulfurized by using an ammonia desulfurization device, wherein ammonia is used as the first desulfurizer, and metal alkali is used An active desulfurizing agent is used as the second desulfurizing agent, preferably, the first desulfurizing agent is a main desulfurizing agent and the second desulfurizing agent is an auxiliary desulfurizing agent.

In some embodiments, the added amount of metal basic desulfurizer can be ≤45%, preferably ≤25%, more preferably ≤10%.

In the meaning of the present invention, the percentage of the added amount of the metal basic desulfurizer can be understood as the ratio of the sub-desulfurization amount and the total desulfurization amount of the metal basic desulfurizer (or auxiliary desulfurizer) under the situation of fully participating in the desulfurization reaction. Ratio, the total desulfurization amount is equal to the sum of the sub-desulfurization amount and another sub-desulfurization amount when the ammonia desulfurizer (or main desulfurizer) fully participates in the desulfurization reaction. Assuming that the first desulfurizer solution per unit volume and the second desulfurizer solution per unit volume have the same desulfurization amount under the condition that they fully participate in the desulfurization reaction, then the first desulfurizer solution added to the ammonia desulfurization device in the same operating cycle The volume of the second desulfurizing agent solution may be smaller than the volume of the first desulfurizing agent solution added to the ammonia desulfurization device, for example, the ratio of the volume of the second desulfurizing agent solution to the volume of the first desulfurizing agent solution may be 1:2-5.

In some embodiments, the metal alkaline desulfurizer may include at least one of metal hydroxides, metal oxides and carbonates. In the case where the metallic alkaline desulfurization agent includes a plurality of substances, these substances may be used in the form of a mixture, or sequentially used separately from each other, or supplied to the ammonia desulfurization unit at different parts of the ammonia desulfurization unit.

In some embodiments, the metal hydroxide may include at least one of sodium hydroxide and potassium hydroxide.

In some embodiments, the metal oxide may include at least one of potassium oxide and sodium oxide.

In some embodiments, the carbonate may include at least one of potassium carbonate and sodium carbonate.

In some embodiments, a metal base desulfurizer may be employed in solution.

In some embodiments, the metallic alkaline desulfurizer may be employed in the form of powder particles.

In some embodiments, the following ammonia-based desulfurization device can be used when implementing the method. The ammonia-based desulfurization device includes a flue gas cooling unit, a flue gas absorption unit, and a fine particle control unit in sequence along the flue gas flow direction, wherein the flue gas The cooling unit has a flue gas inlet for inputting raw flue gas.

In some embodiments, ammonia may be added to the absorption liquid used in the flue gas absorption unit.

In some embodiments, the ammonia-based desulfurization device may include an oxidation device for oxidizing the absorption liquid, and the oxidation device and the flue gas absorption unit form an absorption liquid circulation through an associated pipeline, wherein ammonia is added to the absorption In the liquid cycle, especially in the oxidation plant and/or in the pipeline of the absorption liquid cycle.

In some embodiments, a metallic alkaline desulfurizer may be added to the water wash circulating fluid for the fine particulate matter control unit.

In some embodiments, the ammonia-based desulfurization device may include a water washing circulation tank that can be supplied with process water, and the water washing circulation tank and the fine particle control unit form a water washing cycle through an associated pipeline, wherein the metal alkaline desulfurization agent Added to the water washing cycle, especially can be added to the water washing cycle tank and/or added to the pipeline of the water washing cycle.

In some embodiments, the pH value of the water washing circulation tank can be controlled within the range of 3-10, for example, 4-8.

In some embodiments, a mist eliminator may be used to remove mist in the flue gas absorption unit.

In some embodiments, a demister can be used to remove mist in the fine particulate matter control unit.

A third aspect of the present invention relates to an ammonia-based desulfurization device, characterized in that the ammonia-based desulfurization device is configured to desulfurize flue gas containing _SO2 and _SO3 , wherein the ammonia-based desulfurization device includes A first desulfurizing agent supply system and a second desulfurizing agent supply system, the first desulfurizing agent supply system is configured to supply ammonia as the first desulfurizing agent to the ammonia desulfurization device, and the second desulfurizing agent supply system is configured to use In order to supply the metal alkaline desulfurizing agent to the ammonia desulfurization device as the second desulfurizing agent, preferably, the first desulfurizing agent is a main desulfurizing agent and the second desulfurizing agent is an auxiliary desulfurizing agent.

In some embodiments, the first desulfurizing agent supply system and the second desulfurizing agent supply system can be configured such that the added amount of metal alkaline desulfurizing agent is ≤45%, preferably ≤25%, more preferably ≤10%.

In some embodiments, the second desulfurizing agent supply system may be configured to supply the metallic alkaline desulfurizing agent in solution.

In some embodiments, the first desulfurizer supply system may be configured to add ammonia to the absorption liquid for the flue gas absorption unit.

In some embodiments, the ammonia-based desulfurization device may include oxidation equipment for oxidizing the absorption liquid, and the oxidation equipment and the flue gas absorption unit form an absorption liquid circulation through an associated pipeline, wherein the first desulfurization The agent supply system is configured for adding ammonia to the absorption liquid circuit, in particular to the oxidation device.

In some embodiments, the ammonia-based desulfurization device may include an oxidation air supply system configured to supply compressed air to oxidation equipment.

In some embodiments, the second desulfurizing agent supply system may be configured to add the metal alkaline desulfurizing agent into the water washing circulating fluid for the fine particulate matter control unit.

In some embodiments, the ammonia-based desulfurization device may include a water washing circulation tank that can be supplied with process water, and the water washing circulation tank and the fine particle control unit form a water washing cycle through an associated pipeline, wherein the second desulfurizer The supply system is configured for adding the metallic alkaline desulfurizer into the water wash cycle, especially into the water wash cycle tank.

In some embodiments, at least one unit among the flue gas cooling unit, the flue gas absorption unit, and the fine particle control unit may be provided with a circulating liquid spray layer, and the circulating liquid spray layer is configured to be used in the corresponding Spray circulating fluid in the unit.

In some embodiments, the flue gas cooling unit, the flue gas absorption unit and the fine particulate matter control unit may respectively be provided with at least one circulating liquid spray layer.

In some embodiments, the flue gas cooling unit, the flue gas absorption unit and the fine particle control unit may be configured as separate units.

In some embodiments, the flue gas cooling unit, the flue gas absorption unit, and the fine particle control unit are respectively used as separate towers and can be connected in series, and the flue gas can flow from the previous tower (for example, in the tower The flue gas outlet at the top) is piped to the flue gas inlet of the next tower (for example at the lower part of the tower).

In some embodiments, at least two units among the flue gas cooling unit, the flue gas absorption unit and the fine particle control unit may be integrated together.

In some embodiments, the flue gas cooling unit, flue gas absorption unit and fine particle control unit can be integrated into an ammonia desulfurization tower.

In some embodiments, the ammonia desulfurization unit may comprise towers in series, one of which may be configured as an ammonia desulfurization tower, and the other tower may be configured as an alkaline scrubber. The first desulfurizing agent or main desulfurizing agent or ammonia desulfurization can be passed through the ammonia desulfurization tower. In this alkali cleaning device, further desulfurization can be carried out by means of a second desulfurizing agent or an auxiliary desulfurizing agent or a metallic alkaline desulfurizing agent.

In some embodiments, the flue gas cooling unit, the flue gas absorption unit and the fine particle control unit may be arranged sequentially from bottom to top in the ammonia desulfurization tower.

In some embodiments, the ammonia desulfurization unit may further include an ammonium sulfate treatment system configured to treat the ammonium sulfate solution or slurry output from the ammonia desulfurization unit.

In some embodiments, the flue gas containing sulfur oxides can first enter the flue gas cooling unit, and the flue gas is in contact with the spray liquid circulating in the flue gas cooling unit, and the temperature of the flue gas is reduced; the flue gas with reduced temperature then enters the flue gas Gas absorption unit, in which the flue gas absorption unit is in contact with the first desulfurizer or the main desulfurizer, and most of the sulfur oxides in the flue gas are removed; then, the residual sulfur oxides enter the fine particle control unit along with the flue gas , where it can be further removed, and fine particles in the flue gas can be eliminated at the same time.

In some embodiments, the main desulfurizer is preferably added to the flue gas absorption unit, and the auxiliary desulfurizer is preferably added to the fine particle control unit.

In some embodiments, the flue gas containing SO ₂ and SO ₃ from a coal-fired boiler in a thermal power plant can be desulfurized, or the flue gas containing SO ₂ and SO ₃ from a chemical process (such as from an oil refinery flue gas) for desulfurization.

In the sense of the present invention, the main desulfurizer can remove most of the sulfur oxides in the flue gas (at least half of the total amount of sulfur oxides in the original flue gas), and the auxiliary desulfurizer can remove a small part of sulfur oxides (less than half of the total amount of sulfur oxides in the original flue gas, such as at most 30%, preferably at most 25% or 15%).

In the method and device according to the present invention, SO ₂ and SO ₃ in flue gas can be removed synergistically, improvements can be achieved in solving flue gas tailing and aerosol generation, especially can significantly reduce or even substantially eliminate flue gas Tailing and aerosol generation. According to the method and device of the invention, the process flow can be simplified and the investment can be reduced.

In the method and device according to the present invention, compared with the conventional desulfurization by simply using the ammonia desulfurizer, the metal alkaline desulfurizer is used for further desulfurization or auxiliary desulfurization, for example, the additional auxiliary desulfurization function in the fine particle control unit can be used. The energy-saving effect is achieved, so that the whole process and device can be more environmentally friendly.

The technical features mentioned above, the technical features to be mentioned later and the technical features shown individually in the drawings can be combined with each other arbitrarily, as long as the combined technical features are not mutually contradictory. All technically feasible combinations of features are the technical content contained in this document.

Description of drawings

Now, an ammonia desulfurization device and an ammonia desulfurization method implemented using the ammonia desulfurization device according to exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of an ammonia desulfurization device according to an embodiment of the present invention.

Detailed ways

FIG. 1 shows an ammonia desulfurization device according to an exemplary embodiment of the present invention. The ammonia desulfurization device can be used to treat the flue gas of coal-fired boilers in thermal power plants, or can be used to treat other chemical flue gases containing sulfur oxides. The ammonia desulfurization process involved in the present invention is different from the traditional simple ammonia desulfurization, but additionally utilizes metal alkaline desulfurization agent on the basis of ammonia desulfurization.

The ammonia-based desulfurization device includes an ammonia-based desulfurization tower 1, and the ammonia-based desulfurization tower includes a flue gas cooling unit 4, a flue gas absorption unit 5, and a fine particle control unit 6 sequentially from bottom to top. The flue gas cooling unit 4 has a flue gas inlet 9 . The flue gas containing SO ₂ and SO ₃ , as the original flue gas, usually has a relatively high temperature, and enters the flue gas cooling unit 4 through the flue gas inlet 9 . The flue gas cooling unit 4 forms a concentrated liquid circulation through the associated pipeline 12 and the circulation pump 21 arranged in the pipeline 12 . The concentrated liquid can be sprayed against the flow direction of the flue gas on the upper part of the flue gas cooling unit 4 through a spray layer not shown in the figure. After the original flue gas enters from the flue gas inlet 9, it passes through the solution or slurry contained in the flue gas cooling unit 4, and the residual heat of the original flue gas can evaporate and concentrate the solution or slurry. At the same time, the original flue gas is cooled and dust is removed in the flue gas cooling unit 4 . Depending on the degree of concentration in the flue gas cooling unit 4, the substance contained in the flue gas cooling unit 4 may be a solution or a slurry of ammonium sulfate, wherein the slurry has a solid content. The concentrated solution or slurry mainly containing ammonium sulfate contained in the flue gas cooling unit 4 can be output to the ammonium sulfate treatment system 16 schematically shown in FIG. 1 through the circulation pump 21 and the branch pipeline 12a. The output solution or slurry can be treated in the ammonium sulfate treatment system 16 . In one exemplary processing scheme, the solution or slurry may be crystallized by evaporation into a solid ammonium sulfate product and finally packaged into bags of ammonium sulfate fertilizer having a predetermined weight. In another exemplary process, the solution or slurry may be directly filled as a salable commodity.

The flue gas absorption unit 5 is separated from the flue gas cooling unit 4 through a gas-liquid separator 11a. The flue gas can enter the flue gas absorption unit 5 from the flue gas cooling unit 4 through the gas-liquid separator 11a, but the liquid cannot basically enter the flue gas cooling unit 4 from the flue gas absorption unit 5 through the gas-liquid separator 11a, or In the case of intentional design, it can only pass through the gas-liquid separator 11a from the flue gas absorption unit 5 into the flue gas cooling unit 4 in a controlled manner within a predetermined degree. In the flue gas absorption unit 5, the ammoniated absorption liquid absorbs the sulfides in the flue gas, especially SO ₂ . The flue gas absorption unit 5 , the oxidation device 2 as well as the associated

lines

23 , 24 and the circulation pump 22 arranged in the line 23 form an absorption liquid circuit 7 . The absorption liquid in the flue gas absorption unit 5 is transported from the lower part of the flue gas absorption unit 5 to the oxidation device 2 via the pipeline 24, and is oxidized in the oxidation device 2. The oxidation device 2 can be connected with an oxidation air supply system 14, and the compressed air with a predetermined pressure is delivered to the oxidation device 2 through the oxidation air supply system 14, so as to oxidize the absorption liquid delivered to the oxidation device 2. The oxidation device 2 can be connected to the first desulfurizer supply system 13 constituted as an ammonia supply system, and ammonia can be added to the oxidation device 2 through the ammonia supply system. Ammonia as a desulfurizing agent may be elemental ammonia, ammonia water, ammonium bicarbonate or the like. For example, ammonia water with a concentration of 20% (mass) can be used as the first desulfurizing agent. The first desulfurizing agent may be a primary desulfurizing agent. The absorption liquid oxidized in the oxidation device 2 can be sent to the flue gas absorption unit 5 through the circulation pump 22 and the pipeline 23 . In the embodiment shown in FIG. 1 , three spray layers are provided in the smoke absorption unit 5 , and the absorption liquid is sprayed into the smoke absorption unit 5 through these spray layers against the flow direction of the smoke. In the flue gas absorption unit 5, the absorption liquid containing ammonium sulfite can remove sulfides in the flue gas, especially sulfur dioxide. The absorption liquid which has absorbed sulfur dioxide contains ammonium bisulfite. Ammonium bisulfite can be converted to ammonium sulfite by adding ammonia. A mist eliminator 18a may be provided on the upper part of the smoke absorption unit 5 to demist the smoke flowing through the mist eliminator 18a.

The secondary oxidation air used in the oxidation device 2 can be sent from the oxidation device 2 to the flue gas cooling unit 4 of the ammonia desulfurization tower 1 through a pipeline 25 . The oxidized absorption liquid in the oxidation device 2 can be replenished into the flue gas cooling unit 4 through the circulation pump 22 and the branch pipeline 29 . As an alternative or supplement, in an unshown embodiment, the absorption liquid can be added to the flue gas cooling unit 4 from the flue gas absorption unit 5, for example, through a branch line of the pipeline 24 leading to the flue gas cooling unit 4 .

The fine particle control unit 6 is separated from the smoke absorption unit 5 by a gas-liquid separator 11b. The flue gas can enter the fine particulate matter control unit 6 from the flue gas absorption unit 5 through the gas-liquid separator 11b, but the liquid basically cannot enter the flue gas absorption unit 5 from the fine particulate matter control unit 6 through the gas-liquid separator 11b, or In the case of intentional design, it can only pass through the gas-liquid separator 11b from the fine particle control unit 6 and enter the smoke absorption unit 5 in a controlled manner within a predetermined degree. The fine particle control unit 6 , the water washing circulation tank 3 , the associated

pipelines

27 , 28 and the circulation pump 26 can form a water washing cycle 10 . The water washing circulation tank 3 can be connected with a process water supply system 15 , and the process water supply system 15 can deliver process water to the water washing circulation tank 3 . The water washing circulation liquid can be delivered from the water washing circulation tank 3 to the fine particle control unit 6 via the circulation pump 26 and the pipeline 27, for example, sprayed in the fine particle control unit 6 through a spray layer not shown. The water washing circulation liquid can be returned to the water washing circulation tank 3 through the pipeline 28 at the lower part of the fine particle control unit 6 . The flue gas can be washed with circulating fluid in the fine particle control unit 6 to remove fine particles.

The smoke absorption unit 5 can obtain supplementary liquid from the fine particulate matter control unit 6 and/or the water washing circulation tank 3, so that the amount of the absorption liquid can be kept within a predetermined range, for example, substantially stable. The liquid replenished into the smoke absorption unit 5 from the fine particle control unit 6 and/or the water washing circulation tank 3 becomes a component of the absorption liquid. As shown in FIG. 1 , the water washing circulation tank 3 may be connected to the oxidation device 2 through a pipeline 30 for replenishing liquid to the oxidation device. As an alternative or supplement, in an unshown embodiment, the pipeline 28 may have a branch pipeline leading to the smoke absorption unit 5, for supplementing liquid from the fine particle control unit 6 to the smoke absorption unit 5; and/ Or the water washing circulation tank 3 may have a pipeline leading to the smoke absorption unit 5 for supplementing liquid from the water washing circulation tank 3 to the smoke absorption unit 5 .

The water washing circulation tank 3 may be connected to a second desulfurizing agent supply system 17 . The second desulfurizing agent supply system 17 can deliver metal alkaline desulfurizing agent to the water washing circulation tank 3 . The metal alkaline desulfurizer can be added to the water washing circulation tank in the form of powder particles or in the form of solution, for example. Metal alkaline desulfurizer can be used as auxiliary desulfurizer. The pH value of the liquid in the washing circulation tank 3 can be controlled within the range of 3-10, for example, 4-8. As the second desulfurizing agent, the metal alkaline desulfurizing agent may include at least one of metal hydroxides, metal oxides and carbonates. The metal hydroxide may include at least one of sodium hydroxide and potassium hydroxide. The metal oxide may include at least one of potassium oxide and sodium oxide. The carbonate may include at least one of potassium carbonate and sodium carbonate.

A mist eliminator 18b may be provided on the upper part of the fine particle control unit 6 to demist the flue gas flowing through the mist eliminator 18b. The net flue gas demisted by the mist eliminator 18b can be discharged from the ammonia desulfurization tower 1 to the environment through the chimney 8 .

In an embodiment not shown, the metallic alkaline desulfurizer, as a second desulfurizer or an auxiliary desulfurizer, can be directly or indirectly added to the flue gas absorption unit 5 .

In an embodiment not shown, the metal basic desulfurizer, as the second desulfurizer or auxiliary desulfurizer, can be directly or indirectly added to the flue gas absorption unit 5, and the rest directly or indirectly into the fine particulate matter control unit 6.

In an embodiment not shown, the part of the metal alkaline desulfurizer can be added to the oxidation device 2 , or can be added to the

pipeline

23 or 24 connected to the oxidation device 2 .

In an embodiment not shown, all of the metal basic desulfurization agent or the rest of the metal basic desulfurization agent can be added to the

pipeline

27 or 28 connected to the water washing circulation tank 3 .

All or most of the first desulfurization agent or main desulfurization agent or ammonia desulfurization agent can be directly or indirectly added to the flue gas absorption unit 5 . Ammonia addition locations can be single or multiple.

In an embodiment not shown, a small amount of ammonia can be added in the flue gas cooling unit 4 of the ammonia desulfurization tower 1 , and/or a small amount of ammonia can be added in the fine particle control unit 6 of the ammonia desulfurization tower 1 .

In an embodiment not shown, the flue gas cooling unit 4, the flue gas absorption unit 5 and the fine particulate matter control unit 6 can be constituted as separate towers respectively, and these towers can be connected in series, and the flue gas can flow from the front to the The flue gas outlet of one tower (eg at the top of the tower) is piped to the flue gas inlet of the next tower (eg at the lower part of the tower).

In an embodiment not shown, the flue gas cooling unit 4, the flue gas absorption unit 5, and the fine particle control unit 6 can be configured similarly to the embodiment shown in Figure 1, and they are integrated into an ammonia desulfurization tower 1, but the fine The particle control unit 6 is not provided with the second desulfurizing agent supply system 17 for delivering the metal alkaline desulfurizing agent to the water washing circulation tank 3 . In the ammonia desulfurization tower 1, desulfurization is achieved only by the first desulfurizer or main desulfurizer or ammonia. The ammonia-based desulfurization device also includes an auxiliary desulfurization device separate from the ammonia-based desulfurization tower 1, the auxiliary desulfurization device has a circulating fluid and is equipped with a second desulfurizing agent supply system 17 for delivering a metal alkaline desulfurizing agent to the circulating fluid. The flue gas can be transported from the flue gas outlet of the ammonia desulfurization tower 1 to the auxiliary desulfurization device, and further desulfurized by metal alkaline desulfurizer in the auxiliary desulfurization device. The net flue gas can be discharged into the environment from the flue gas outlet of the auxiliary desulfurization device. The structure of the auxiliary desulfurization device can be constructed similarly to the fine particle control unit 6 shown in FIG. 1, wherein the auxiliary desulfurization device also has a circulation tank with a process water inlet and the already mentioned second desulfurizer supply system 17. The circulating fluid of the auxiliary desulfurization device can be directly or indirectly output to the fine particle control unit 6 of the ammonia desulfurization tower 1 in addition to the circulation operation (for example, the circulating fluid of the auxiliary desulfurization device can be output from its circulation tank to the ammonia desulfurization The water washing circulation tank 3) of the tower 1 and/or the flue gas absorption unit 5 (for example, the circulating liquid of the auxiliary desulfurization device can be output from its circulation tank to the oxidation device 2 of the ammonia desulfurization tower 1).

In an exemplary application of the ammonia desulfurization device designed as shown in Figure 1 according to the present invention, the ammonia desulfurization device can have the following design parameters:

The designed circulation volume of the concentrate liquid circulation is 20m ³ /h, the circulation volume of the absorption liquid circulation is 175m ³ /h, and the circulation volume of the water washing cycle is 55m ³ /h. Ammonia water with a concentration of 20% (mass) is used as the main desulfurizer, a sodium hydroxide solution with a concentration of 20% (mass) is used as the auxiliary desulfurizer, and the amount of the auxiliary desulfurizer is 10%.

The designed flue gas parameters are as follows:

序号serial number	工艺指标Process index	单位unit		数值value
11	原烟气流量Raw gas flow	Nm ³/h Nm ³ /h	80008000
22	原烟气进口温度Raw flue gas inlet temperature	℃℃	230230
33	原烟气SO ₂浓度 Raw flue gas SO ₂ concentration	mg/Nm ³ mg/ ^Nm3	3000030000
44	原烟气SO ₃浓度 Raw flue gas SO ₃ concentration	mg/Nm ³ mg/ ^Nm3	100100
55	原烟气进口粉尘浓度Raw flue gas inlet dust concentration	mg/Nm ³ mg/ ^Nm3	≤20≤20
66	出口烟气SO ₂浓度 Outlet flue gas SO ₂ concentration	mg/Nm ³ mg/ ^Nm3	≤100≤100
77	出口烟气SO ₃浓度 Outlet flue gas SO ₃ concentration	mg/Nm ³ mg/ ^Nm3	≤5≤5
88	出口烟气尘浓度Exit flue gas dust concentration	mg/Nm ³ mg/ ^Nm3	≤20≤20
99	出口烟气氨逃逸浓度Outlet flue gas ammonia escape concentration	mg/Nm ³ mg/ ^Nm3	≤5≤5
1010	氨回收利用率Ammonia recovery rate	％%	≥99≥99

Here, the solution composition of each zone of the ammonia-based desulfurization device is controlled mainly through coordinated control of the addition of ammonia as the first desulfurizer and sodium hydroxide as the second desulfurizer, so as to control ammonia escape and aerosol, and reduce smoke Gas smearing phenomenon.

In the test of ammonia desulfurization according to the present invention, the net flue gas SO ₂ concentration is 21 mg/Nm ³ , the total dust (including aerosol) concentration is 3 mg/Nm ³ , the SO ₃ concentration is 2 mg/Nm ³ , and the amount of ammonia slip It is 0.8mg/Nm ³ , basically no tailing phenomenon.

As a comparative example, with other conditions kept constant, the second desulfurizing agent supply system 17 was disconnected from the water-washing circulation tank 3, and thus no metal alkaline desulfurizing agent was supplied.

In the test of the comparative example, the net flue gas SO ₂ concentration is 30 mg/Nm ³ , the total dust (including aerosol) concentration is 19 mg/Nm ³ , the SO ₃ concentration is 5 mg/Nm ³ , and the ammonia escape amount is 4 mg/Nm ³ , the tailing phenomenon is serious.

It should be noted that the terminology used herein is for the purpose of describing specific aspects only, and is not used to limit the disclosure. As used herein, the singular forms "a" and "the one" shall include plural forms unless the context clearly dictates otherwise. It will be understood that the terms "comprises" and "comprises" and other similar terms, when used in the application documents, specify the existence of stated operations, elements and/or parts, but do not exclude one or more other operations, elements , the presence or addition of components and/or combinations thereof. As used herein, the term "and/or" includes all arbitrary combinations of one or more of the associated listed items. Like reference numerals denote like elements throughout the description of the drawings.

It will be understood that although the terms "first", "second", etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. Thus, a first element could be termed a second element without departing from the teachings of the inventive concept.

Finally, it should be pointed out that the above embodiments are only used for understanding the present invention, and do not limit the protection scope of the present invention. For those skilled in the art, modifications can be made on the basis of the above-mentioned embodiments, and these modifications do not depart from the protection scope of the present invention.

Claims

A method for removing SO3 by ammonia desulfurization and solving flue gas tailing and aerosol, which is characterized in that ammonia is used as the main desulfurizer, and a metal alkaline desulfurizer is added to the ammonia desulfurization device as an auxiliary desulfurizer.
An ammonia desulfurization method, characterized in that the flue gas containing SO2 and SO3 is desulfurized by using an ammonia desulfurization device, wherein ammonia is used as the first desulfurizer, and a metal alkaline desulfurizer is used as the second desulfurizer agent.
The method of claim 2, wherein said first desulfurizing agent is a primary desulfurizing agent, and said second desulfurizing agent is an auxiliary desulfurizing agent.
The method according to claim 3, characterized in that the added amount of the metal alkaline desulfurizer is ≤45%.
The method according to claim 3, characterized in that the added amount of the metal alkaline desulfurizer is ≤25%.
The method according to claim 3, characterized in that the added amount of the metal alkaline desulfurizer is ≤10%.
The method according to any one of claims 1 to 6, characterized in that the metal alkaline desulfurizer includes at least one of metal hydroxides, metal oxides and carbonates.
The method of claim 7, wherein the metal hydroxide comprises at least one of sodium hydroxide and potassium hydroxide.
The method of claim 7, wherein the metal oxide comprises at least one of potassium oxide and sodium oxide.
The method of claim 7, wherein the carbonate comprises at least one of potassium carbonate and sodium carbonate.
The method according to any one of claims 1 to 6, characterized in that a metal alkaline desulfurizer in the form of a solution is used.
The method according to any one of claims 1 to 6, characterized in that the ammonia desulfurization device is used, and the ammonia desulfurization device includes a flue gas cooling unit (4), a flue gas absorption unit ( 5) and the fine particle control unit (6), wherein the flue gas cooling unit has a flue gas inlet (9) for inputting raw flue gas.
The method as claimed in claim 12, characterized in that ammonia is added to the absorption liquid for the flue gas absorption unit.
The method according to claim 12, characterized in that the ammonia desulfurization device comprises oxidation equipment (2) for oxidizing the absorption liquid, and the oxidation equipment and the flue gas absorption unit form the absorption liquid through the associated pipeline cycle, wherein ammonia is fed to the oxidation plant.
The method according to claim 12, characterized in that the metal alkaline desulfurizer is added to the water washing circulating liquid used for the fine particle control unit.
The method according to claim 15, characterized in that the ammonia desulfurization device comprises a water washing circulation tank (3) capable of being supplied with process water, and the water washing circulation tank and the fine particle control unit form a water washing cycle through an associated pipeline , wherein the metal alkaline desulfurizer is added to the water washing circulation tank.
The method according to claim 16, characterized in that the pH value in the washing circulation tank is controlled within the range of 3-10.
The method according to claim 12, characterized in that, using a mist eliminator (18a, 18b) to remove mist in at least one unit among the smoke absorption unit and the fine particle control unit.
The method according to any one of claims 1 to 6, characterized in that the method desulfurizes the flue gas containing SO2 and SO3 from coal-fired boilers in thermal power plants, or desulfurizes the flue gas containing The flue gas of SO 2 and SO 3 is desulfurized.
An ammonia-based desulfurization device, characterized in that the ammonia-based desulfurization device is configured to desulfurize the flue gas containing SO2 and SO3 , wherein the ammonia-based desulfurization device includes a first desulfurizer supply system ( 13) and a second desulfurizing agent supply system (17), the first desulfurizing agent supplying system is configured to supply ammonia as the first desulfurizing agent to the ammonia desulfurization device, and the second desulfurizing agent supplying system is configured to be used for The metal alkaline desulfurizer is supplied to the ammonia desulfurization unit as the second desulfurizer.
The ammonia desulfurization device according to claim 20, wherein the first desulfurizing agent is a main desulfurizing agent, and the second desulfurizing agent is an auxiliary desulfurizing agent.
The ammonia-based desulfurization device according to claim 21, characterized in that, the first desulfurizer supply system and the second desulfurizer supply system are configured so that the added amount of metal alkaline desulfurizer is ≤45%.
The ammonia-based desulfurization device according to claim 21, characterized in that, the first desulfurizer supply system and the second desulfurizer supply system are configured so that the added amount of metal alkaline desulfurizer is ≤25%.
The ammonia desulfurization device according to claim 21, characterized in that, the first desulfurizer supply system and the second desulfurizer supply system are configured such that the amount of metal alkaline desulfurizer added is ≤ 10%.
The ammonia-based desulfurization device according to any one of claims 20 to 24, wherein the metal alkaline desulfurizer includes at least one of metal hydroxides, metal oxides and carbonates.
The ammonia desulfurization device according to claim 25, wherein the metal hydroxide comprises at least one of sodium hydroxide and potassium hydroxide.
The ammonia desulfurization device according to claim 25, wherein the metal oxide includes at least one of potassium oxide and sodium oxide.
The ammonia desulfurization device according to claim 25, wherein the carbonate includes at least one of potassium carbonate and sodium carbonate.
The ammonia-based desulfurization device according to any one of claims 20 to 24, wherein the second desulfurizing agent supply system is configured to supply metal alkaline desulfurizing agent in the form of a solution.
The ammonia-based desulfurization device according to any one of claims 20 to 24, characterized in that, the ammonia-based desulfurization device sequentially includes a flue gas cooling unit (4) and a flue gas absorption unit (5) along the flow direction of the flue gas and a fine particle control unit (6), wherein the flue gas cooling unit has a flue gas inlet (9) for inputting raw flue gas.
The ammonia-based desulfurization device according to claim 30, wherein the first desulfurizer supply system is configured to add ammonia to the absorption liquid used in the flue gas absorption unit.
The ammonia-based desulfurization device according to claim 30, characterized in that the ammonia-based desulfurization device includes an oxidation device (2) for oxidizing the absorption liquid, and the oxidation device and the flue gas absorption unit (5) pass through The associated line forms an absorption liquid circuit, wherein the first desulfurizing agent supply system is designed to feed ammonia into the oxidation plant.
The ammonia desulfurization device according to claim 32, characterized in that the ammonia desulfurization device comprises an oxidation air supply system (14), and the oxidation air supply system is configured to supply compressed air to the oxidation equipment.
The ammonia-based desulfurization device according to claim 30, wherein the second desulfurizer supply system is configured to add metal alkaline desulfurizer into the water washing circulation liquid for the fine particle control unit.
The ammonia-based desulfurization device according to claim 34, characterized in that, the ammonia-based desulfurization device includes a water washing circulation tank (3) that can be supplied with process water, and the water washing circulation tank and the fine particle control unit (6) pass The associated pipeline forms a water washing cycle, wherein the second desulfurizing agent supply system is configured to add the metal alkaline desulfurizing agent into the water washing circulating tank.
The ammonia desulfurization device according to claim 35, characterized in that the pH value in the water washing circulation tank can be controlled within the range of 3-10.
The ammonia desulfurization device according to claim 30, characterized in that at least one of the flue gas absorption unit and the fine particle control unit is provided with a mist eliminator (18a, 18b).
The ammonia desulfurization device according to claim 30, wherein at least one unit among the flue gas cooling unit, the flue gas absorption unit and the fine particle control unit is provided with a circulating fluid spray layer, and the circulating fluid The spray level is designed for spraying the circulating fluid in the corresponding unit.
The ammonia-based desulfurization device according to claim 38, wherein the flue gas cooling unit, the flue gas absorption unit and the fine particulate matter control unit are respectively provided with at least one circulating fluid spray layer.
The ammonia desulfurization device according to claim 30, characterized in that, the flue gas cooling unit, the flue gas absorption unit and the fine particle control unit are constituted as separate units, or the flue gas cooling unit, the flue gas absorption At least two of the unit and the fine particulate matter control unit are integrated together.
The ammonia desulfurization device according to claim 30, wherein the flue gas cooling unit, flue gas absorption unit and fine particle control unit are integrated into an ammonia desulfurization tower, wherein the flue gas cooling unit, flue gas The gas absorption unit and the fine particulate matter control unit are arranged sequentially from bottom to top in the ammonia desulfurization tower.
The ammonia-based desulfurization device according to any one of claims 20 to 24, characterized in that the ammonia-based desulfurization device also includes an ammonium sulfate treatment system, and the ammonium sulfate treatment system is configured to treat the output from the ammonia-based desulfurization device. Ammonium sulfate solution or slurry for treatment.
The ammonia-based desulfurization device according to any one of claims 20 to 24, characterized in that the ammonia-based desulfurization device is configured to treat the smoke containing SO 2 and SO 3 from a coal-fired boiler in a thermal power plant Desulfurization of gas, or desulfurization of flue gas containing SO 2 and SO 3 from chemical processes.
The ammonia desulfurization device according to any one of claims 20 to 24, characterized in that the ammonia desulfurization device comprises towers in series, one of which is configured as an ammonia desulfurization tower, and the other tower is configured as an alkali washing A device, wherein, in the ammonia desulfurization tower, the first desulfurizer can be used for desulfurization, and in the alkali washing device, the second desulfurizer can be used for further desulfurization.