CN112169573A - Flue gas desulfurization and denitrification process - Google Patents
Flue gas desulfurization and denitrification process Download PDFInfo
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Abstract
The invention relates to a flue gas desulfurization and denitrification process, which comprises the following steps: s1: introducing chlorine into the solution A containing bromide ions to generate solution B containing elemental bromine; s2: introducing flue gas into the solution B, spraying alkali liquor above the solution B while introducing the flue gas, and mixing and reacting the flue gas, the solution B and the alkali liquor to obtain a solution C; s3: introducing chlorine into the solution C, and merging the chlorine into the solution A through a circulating pipeline; when the concentration of the sodium nitrite in the solution A reaches 70g/100ml, stopping introducing the flue gas and the chlorine gas, and emptying the reaction system; the key substances of the invention can be recycled, the cost of nitrogen oxide treatment agents is reduced on the premise of higher denitration efficiency, the total material cost of desulfurization and denitration is greatly reduced, the removal rate of sulfur oxides is improved by more than 2-5%, the removal rate of nitrogen oxides is 90-98%, and the ultra-clean emission of desulfurization and denitration is realized.
Description
Technical Field
The invention belongs to the field of environmental protection, and particularly relates to a flue gas desulfurization and denitrification process.
Background
The combustion of fossil fuels generates a large amount of nitrogen oxides and sulfur dioxide, and the development of flue gas desulfurization and denitrification technology is promoted. Some wet scrubbing processes including limestone-gypsum process, magnesium oxide process, and double alkali scrubbing process have been used for sulfur dioxide removal. The ammonia desulfurization technology is a wet desulfurization technology which is widely applied at present, can produce valuable products such as ammonium sulfate fertilizer and the like as byproducts during desulfurization, does not produce any secondary pollution, belongs to a green and clean desulfurization technology, and has low denitration capability.
Currently, NOx emission control is mainly developed from fuel improvement, in-process combustion treatment, and post-combustion treatment. The use of high-quality fuels entails increased costs from the viewpoint of fuel improvement, while the use of alternative fuels is currently associated with disadvantages in plant technology. In view of treatment in the combustion process, the low-nitrogen combustion technology is always the most widely applied, economical and practical measure, can inhibit and reduce the generation of NOx to a certain extent, but has the integral denitration rate of about 30-50 percent and can not meet the control requirement on the emission concentration of the NOx. In consideration of post-combustion treatment, establishing a flue gas denitration facility to meet the emission requirement of NOx is the currently preferred emission reduction strategy, so that developing a high-efficiency and low-cost flue gas denitration system is an important research direction for controlling NOx emission.
In addition, NOx can cause problems such as acid rain, photochemical pollution, ozone layer depletion, and the like. Acidic substances in acid rain can directly or indirectly affect soil and aquatic ecosystems, photochemical smog (comprising ozone, aldehyde, ketone, acid, peroxyacetyl nitrate and the like) generated by pollutants in the atmosphere under the action of ultraviolet rays has strong oxidizing property, stimulates respiratory tracts and eyes of human bodies, and has irreversibility on the damage of buildings. Therefore, research on nitrogen oxide control is increased by various scientific research institutions at home and abroad.
Flue gas denitration technologies developed by research in various countries in the world can be divided into dry denitration and wet denitration in terms of treatment processes. The dry method mainly comprises Selective Catalytic Reduction (SCR), selective non-catalytic reduction (SNCR), an adsorption method, a red-hot carbon reduction method, a high-energy electron activation oxidation method and the like; the wet method mainly comprises a water absorption method, a hydrochloric acid method, a yellow phosphorus method, a hydrogen peroxide method, a complex absorption method, a liquid membrane method, a microbial degradation method and the like; the dry-wet combination method is a denitration method formed by combining catalytic oxidation and a wet method. For denitration techniques, the major industrial applications are SCR (selective catalytic reduction) and SNCR (selective non-catalytic reduction). The SCR denitration efficiency is high, but the process is complex, and the catalyst is expensive and volatile; the SNCR process is simple, the operation cost of the device is low, but the denitration efficiency is low; the microbiological method, yellow phosphorus method, nitrogen peroxide method, etc. have certain difficulties in practical application due to the limitations of operating conditions, toxicity, cost, etc.
Therefore, in the wet denitration, aiming at the characteristic that NO is insoluble in water, the oxidation-reduction process is often adopted to oxidize NO into NO2Higher order nitrogen oxides that are isosoluble in water, followed by reduction of NO with a reducing agent2The nitrogen is reduced, and the process uses an oxidant and a reducing agent with higher price, so that the cost for finally treating the nitrogen oxide is higher.
Disclosure of Invention
One object of the present invention is to provide a flue gas desulfurization and denitrification process,
the method comprises the following steps:
s1: introducing chlorine into the solution A containing bromide ions to generate solution B containing elemental bromine;
s2: and introducing the flue gas into the solution B, spraying alkali liquor above the solution B while introducing the flue gas, and mixing and reacting the flue gas, the solution B and the alkali liquor to obtain a solution C.
Preferably, it further comprises S3: introducing chlorine into the solution C, and merging the chlorine into the solution A through a circulating pipeline;
and when the concentration of the sodium nitrite in the solution A reaches 70g/100ml, stopping introducing the flue gas and the chlorine gas, and emptying the reaction system.
Preferably, the solution A further comprises a complexing agent, wherein the complexing agent is selected from one or more of ferrous EDTA (ethylene diamine tetraacetic acid) and cobalt ethylenediamine; preferably ferrous EDTA salt.
Because the elemental bromine has strong NO and SO2The reaction capability, therefore, the invention utilizes the stronger reaction activity of the bromine simple substance and NO and SO in the flue gas2And reacting to eliminate nitric oxide and sulfur dioxide in the flue gas.
However, because NO is insoluble in water, a complexing agent is added into the solution a, and the complexing agent can react with NO to generate an as-NO structure, so that NO in the flue gas is captured to enter a water phase, and a bromine simple substance generated by the reaction of bromine salt in the solution a and chlorine reacts with NO to generate nitrosyl bromide NOBr, thereby achieving the effect of removing NO.
Preferably, the solution a further comprises a polyether, and the polyether has the following structure:
RO-(EO)m-(PO)nH
wherein R is a C3-C8 starting group, preferably n-propyl or n-butyl;
m, n are independently selected from integers from 10-20, and 25< m + n < 35;
the polyether has a unique effect of supporting the liquid film, so that when the flue gas is introduced into the solution B, the integrity of the liquid film can be maintained, bubbles are reduced, and the contact efficiency of the flue gas and the solution is promoted.
Preferably, in the present invention, the bromide: complexing agent: the mass ratio of the polyether is 22-35:2-4.5: 1-3.
The alkali liquor is one or two of sodium hydroxide, potassium hydroxide and calcium hydroxide;
the chlorine gas introduction amount and the chlorine gas introduction speed are not particularly limited in the present application, and may be adjusted according to the actual scale of the reaction system and the concentration of the solution without departing from the present invention.
The chlorine source is not particularly limited, a chlorine storage tank can be adopted, the chlorine is stored in a storage container, when the reaction system actually works, the chlorine storage tank is opened to form the access, so that the chlorine in the chlorine storage tank can be accessed into the solution A, and preferably, a gas flowmeter is arranged between the chlorine storage tank and the reaction system to quantitatively control the chlorine; as another embodiment, the chlorine generating raw materials can be stored in respective storage containers, and when the reaction system actually works, the chlorine generating raw materials react to form chlorine gas, so that compared with chlorine gas, the chlorine generating raw materials are convenient to store, and the storage cost of the chlorine gas is reduced; known chlorine generating means can be used in this application without departing from the inventive concept, such as hypochlorite reaction with hydrochloric acid, perchlorate reaction with hydrochloric acid, chlorite reaction with hydrochloric acid, and the like.
NaClO+2HCl→Cl2+NaCl+H2O；
KClO3+ 6HCl (dilute) → KCl + 3Cl2＋3H2O；
Ca（ClO）2+ 4HCl (dilute) → CaCl2＋2Cl2＋2H2O。
The present application does not specifically limit the amount and rate of introduction of the flue gas, and it is advantageous to introduce as much as possible according to the actual scale and throughput of the reaction system without departing from the concept of the present invention.
In the application, the reaction circulation is realized through the replacement reaction of chlorine and bromine salt, the reaction of bromine simple substance with sulfur dioxide and nitric oxide, and the reaction of nitrogen dioxide with alkali solution, and the reaction principle is as follows:
2NaBr+Cl2→2NaCl+Br2；
and (3) denitration reaction: 2NO + Br2→2NOBr，NOBr+H2O→HNO2+HBr；
And (3) desulfurization reaction: SO (SO)2+Br2+2H2O→2HBr+H2SO4；
Alkaline solution reaction: HBr + NaOH → NaBr + H2O，HNO2+NaOH→NaNO2+H2O，
2NO2+2NaOH→NaNO3+NaNO2+H2O。
Therefore, the chlorine reacts with the bromide to obtain the bromine simple substance, the bromine simple substance has extremely strong reaction activity with NO, the bromine simple substance reacts with NO instantly to generate nitrosyl bromine NOBr under the coordination of other auxiliary agents in the composition, then bromide ions are replaced through the subsequent reaction of the NOBr, and then the bromide ions react with the continuously supplied chlorine and continue to react with the next NO molecule, and the cycle is repeated, so that the bromide plays a role similar to a catalyst and is free of consumption.
Meanwhile, in the system, the reaction activity and volatility of the hydrogen bromide are moderate, so that the requirement on reaction conditions is not high, and the cost is reduced.
As an embodiment, the flue gas can be subjected to a desulfurization process to reduce the amount of chlorine used, and the separate desulfurization process is performedKnown as, for example, CaCO3(limestone) -based calcium process, MgO-based magnesium process, Na2SO3Sodium process based on NH3The basic ammonia process, the organic base based organic base process, and any known desulfurization process can be used in the present invention without departing from the spirit of the present invention.
As an embodiment of the present invention, the desulfurization and denitrification process is a batch process, and includes:
s1: introducing chlorine into the solution A containing bromide ions, and stopping introducing the chlorine after 95% of bromide ions in the solution are converted into elemental bromine to obtain a solution B containing the elemental bromine;
s2: introducing flue gas into the solution B, spraying alkali liquor above the solution B while introducing the flue gas, and mixing and reacting the flue gas, the solution B and the alkali liquor to obtain a solution C;
s3: and when 95% of bromine in the solution C is converted into bromide ions, stopping introducing the flue gas, repeating the steps S1 and S2 until the concentration of the sodium nitrite in the solution C reaches 70g/100ml, stopping introducing the flue gas and the chlorine gas, and finishing the reaction.
As another embodiment of the present invention, the desulfurization and denitrification process is a continuous process, including:
s1: putting the solution A into a reaction system A, and introducing chlorine into the solution A containing bromide ions to generate a solution B containing elemental bromine;
s2: transferring the generated solution B with a certain volume V into a reaction system B, introducing flue gas into the solution B, spraying alkali liquor above the solution B while introducing the flue gas, and mixing and reacting the flue gas, the solution B and the alkali liquor to obtain a solution C;
s3: extracting a certain volume V' of solution C, and circulating the solution C into the solution A;
and when the concentration of the sodium nitrite in the solution A reaches 70g/100ml, stopping introducing the flue gas and the chlorine gas, and emptying the reaction system.
Preferably, in step S3, the solution C is introduced into the solution a through the circulation line after the chlorine gas reaction.
Preferably, V = V'.
Preferably, the volume V of solution B withdrawn in step S2 is 10-90%, preferably 40-70%, more preferably 50-55% of the total volume of solution B in reaction system a.
Preferably, the volume V' of solution C withdrawn in step S3 is 10-90%, preferably 40-70%, more preferably 50-55% of the total volume of solution C in reaction system B.
The structure and composition of the reaction system are not particularly required, and the reaction system can be a single reaction kettle, a reaction tower or other known single reactor structures, or can also be a reactor group consisting of a plurality of reaction kettles and reaction towers, and the reaction kettles and the reaction towers can be connected in parallel or in series to form a whole so as to achieve the required solution B or solution C.
The structure of feeding chlorine and flue gas into the reaction system is known, and any known gas inlet and liquid inlet structure can be adopted without departing from the concept of the invention.
The spraying method of the alkali liquor is known, and the spraying operation of the alkali liquor can be realized by arranging a liquid distributor at the top of a reaction system, so that flue gas is contacted with the sprayed alkali liquor to react in the upward escaping process after reacting with the solution B so as to eliminate the conversion of nitrogen dioxide in the solution into nitrite; meanwhile, after the sprayed alkali liquor enters the solution B, the alkali liquor and the acidic materials in the solution B are subjected to neutralization reaction to generate salts.
Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages:
the key substances of the composition can be recycled, so that the cost of nitrogen oxide treatment agents is reduced on the premise of higher denitration efficiency, part of desulfurization can be realized, the total material cost of desulfurization and denitration is reduced to a greater extent, the removal rate of sulfur oxides is improved by more than 2-5%, the removal rate of nitrogen oxides is more than 90%, the highest removal rate is more than 98%, ultra-clean emission of desulfurization and denitration is easier to realize, the usage amount of the composition is lower, and the use concentration of a single substance is usually one ten thousandth to five thousandth.
Detailed Description
The first embodiment is as follows:
to be treatedThe physical object is 30000CMH, and the NO content is 900mg/m3，NO2Is 100mg/m3The flue gas of (1).
Adding 25 parts per million of sodium bromide in mass ratio of the total circulating liquid (about 6-8 tons), adding 3 parts per million of ferrous EDTA in mass ratio of the total circulating liquid (about 6-8 tons), and adding 2 parts per million of polyether in mass ratio to prepare a solution A; simultaneously respectively adding 10% sodium hypochlorite liquid and 30% hydrochloric acid liquid into a first chlorine production storage tank and a second chlorine production storage tank, spraying sodium hypochlorite into a first spray pipe of a first reactor at the speed of 30-50Kg/hr (calculated by pure substances) and spraying hydrochloric acid into a second spray pipe at the speed of 30-60Kg/hr (calculated by pure substances), introducing chlorine generated by reaction into the first storage tank to react with the solution A, stopping spraying the sodium hypochlorite and the hydrochloric acid into the first reactor after 95% of bromide ions in the solution are converted into the bromine, and stopping introducing the chlorine at the same time to obtain solution B containing the bromine; and simultaneously adding a sodium hydroxide (1-10 mass percent) aqueous solution into an alkaline storage tank, introducing nitrogen-containing flue gas into a first storage tank, spraying the sodium hydroxide in the alkaline storage tank to the solution B through a liquid conveying pipe and a liquid distributor, reacting the flue gas, the alkaline solution and the solution B to generate a solution C, stopping introducing the flue gas when 95 percent of bromine simple substance is converted into bromide ions, continuously spraying sodium hypochlorite and hydrochloric acid into the first reactor, and continuously introducing chlorine gas into the solution A to repeat the steps, after the concentration of sodium nitrite in the solution C is close to 70g/100ml, stopping introducing the flue gas and the chlorine gas, and discharging the solution C to a water treatment process. The total nitrogen oxide removal rate of the treated smoke is more than or equal to 95 percent, and the total medicament cost is lower.
Example two:
the object to be treated is 30000CMH and the NO content is 900mg/m3，NO2Is 100mg/m3The flue gas of (1).
Adding 25 parts per million of sodium bromide in mass ratio of the total circulating liquid (about 6-8 tons), adding 3 parts per million of ferrous EDTA in mass ratio of the total circulating liquid (about 6-8 tons), and adding 2 parts per million of polyether in mass ratio to prepare a solution A; simultaneously, respectively adding 10% sodium hypochlorite liquid and 30% hydrochloric acid liquid into a first chlorine generating storage tank and a second chlorine generating storage tank, spraying sodium hypochlorite into a first spraying pipe of a first reactor at the speed of 30-50Kg/hr (calculated by pure substances) and spraying hydrochloric acid into a second spraying pipe at the speed of 30-60Kg/hr (calculated by pure substances), introducing chlorine generated by reaction into the first storage tank to react with the solution A, intermittently opening a liquid outlet switch during the reaction, and removing the solution B with the total volume of 50% into a second reactor; simultaneously adding a sodium hydroxide (1-10 mass percent) aqueous solution into an alkaline storage tank, introducing flue gas containing sulfur and nitrogen into a second reactor, simultaneously spraying the sodium hydroxide in the alkaline storage tank to a solution B through a liquid conveying pipe and a liquid distributor, reacting the flue gas, the alkaline solution and the solution B to generate a solution C, intermittently removing the solution C with the same volume as that of the solution C flowing into the second reactor from the second reactor, reacting the solution C with chlorine gas, and then circulating the solution C into a solution A in a first storage tank, wherein the removing of the solution C from the second reactor and the removing of the solution B from the first storage tank are simultaneously finished, and the flow rates of the solution C and the solution B are kept to be the same. And stopping introducing the flue gas and the chlorine after the concentration of the sodium nitrite in the solution C is close to 70g/100ml, and discharging the solution C to a water treatment process. The total nitrogen oxide removal rate of the treated smoke is more than or equal to 95 percent, and the total medicament cost is lower.
Example three:
the object to be treated is 50000CMH containing SO2Is 900mg/m3NO of 1300mg/m3，NO2Is 100mg/m3The flue gas of (1).
Adding 25 parts per million of sodium bromide in mass ratio of the total circulating liquid (about 6-8 tons), adding 3 parts per million of ferrous EDTA in mass ratio of the total circulating liquid (about 6-8 tons), and adding 2 parts per million of polyether in mass ratio to prepare a solution A; simultaneously respectively adding 10% sodium hypochlorite liquid and 30% hydrochloric acid liquid into a first chlorine production storage tank and a second chlorine production storage tank, spraying sodium hypochlorite into a first spraying pipe of a first reactor at the speed of 30-50kg/hr (calculated by pure substances) and spraying hydrochloric acid into a second spraying pipe at the speed of 30-60kg/hr (calculated by pure substances), introducing chlorine generated by reaction into the first storage tank to react with the solution A, stopping spraying the sodium hypochlorite and the hydrochloric acid into the first reactor after 95% of bromide ions in the solution are converted into the bromine, and stopping introducing the chlorine at the same time to obtain solution B containing the bromine; and simultaneously adding a sodium hydroxide (1-10 mass percent) aqueous solution into an alkaline storage tank, introducing flue gas containing sulfur and nitrogen into a first storage tank, spraying the sodium hydroxide in the alkaline storage tank to the solution B through a liquid conveying pipe and a liquid distributor, reacting the flue gas, the alkaline solution and the solution B to generate a solution C, stopping introducing the flue gas when 95 percent of bromine simple substance is converted into bromide ions, continuously spraying sodium hypochlorite and hydrochloric acid into the first reactor, continuously introducing chlorine gas into the solution A, repeating the steps, stopping introducing the flue gas and the chlorine gas after the concentration of sodium nitrite in the solution C is close to 70g/100ml, and discharging the solution C to a water treatment process. The total sulfur removal rate of the treated smoke is 97 percent, the total nitrogen oxide removal rate is more than or equal to 95 percent, and the total medicament cost is lower.
Example four:
the object to be treated is 50000CMH containing SO2Is 900mg/m3NO of 1300mg/m3，NO2Is 100mg/m3The flue gas of (1).
Adding 25 parts per million of sodium bromide in mass ratio of the total circulating liquid (about 6-8 tons), adding 3 parts per million of ferrous EDTA in mass ratio of the total circulating liquid (about 6-8 tons), and adding 2 parts per million of polyether in mass ratio to prepare a solution A; simultaneously, respectively adding 10% sodium hypochlorite liquid and 30% hydrochloric acid liquid into a first chlorine generating storage tank and a second chlorine generating storage tank, spraying sodium hypochlorite into a first spraying pipe of a first reactor at the speed of 30-50Kg/hr (calculated by pure substances) and spraying hydrochloric acid into a second spraying pipe at the speed of 30-60Kg/hr (calculated by pure substances), introducing chlorine generated by reaction into the first storage tank to react with the solution A, intermittently opening a liquid outlet switch during the reaction, and removing the solution B with the total volume of 50% into a second reactor; simultaneously adding a sodium hydroxide (1-10 mass percent) aqueous solution into an alkaline storage tank, introducing flue gas containing sulfur and nitrogen into a second reactor, simultaneously spraying the sodium hydroxide in the alkaline storage tank to a solution B through a liquid conveying pipe and a liquid distributor, reacting the flue gas, the alkaline solution and the solution B to generate a solution C, intermittently removing the solution C with the same volume as that of the solution C flowing into the second reactor from the second reactor, reacting the solution C with chlorine gas, and then circulating the solution C into a solution A in a first storage tank, wherein the removing of the solution C from the second reactor and the removing of the solution B from the first storage tank are simultaneously finished, and the flow rates of the solution C and the solution B are kept to be the same. And stopping introducing the flue gas and the chlorine after the concentration of the sodium nitrite in the solution C is close to 70g/100ml, and discharging the solution C to a water treatment process. The total sulfur removal rate of the treated smoke is more than or equal to 96.5 percent, the total nitrogen oxide removal rate is more than or equal to 95 percent, and the total medicament cost is lower.
Example five:
the object to be treated is 50000CMH containing SO2Is 900mg/m3NO of 1300mg/m3，NO2Is 100mg/m3The flue gas of (1).
The flue gas is desulfurized by a calcium desulphurization process.
Adding 25 parts per million of sodium bromide in mass ratio of the total circulating liquid (about 6-8 tons), adding 3 parts per million of ferrous EDTA in mass ratio of the total circulating liquid (about 6-8 tons), and adding 2 parts per million of polyether in mass ratio to prepare a solution A; simultaneously, respectively adding 10% sodium hypochlorite liquid and 30% hydrochloric acid liquid into a first chlorine generating storage tank and a second chlorine generating storage tank, spraying sodium hypochlorite into a first spraying pipe of a first reactor at the speed of 30-50Kg/hr (calculated by pure substances) and spraying hydrochloric acid into a second spraying pipe at the speed of 30-60Kg/hr (calculated by pure substances), introducing chlorine generated by reaction into the first storage tank to react with the solution A, intermittently opening a liquid outlet switch during the reaction, and removing the solution B with the total volume of 50% into a second reactor; simultaneously adding a sodium hydroxide (1-10 mass percent) aqueous solution into an alkaline storage tank, introducing flue gas containing sulfur and nitrogen into a second reactor, simultaneously spraying the sodium hydroxide in the alkaline storage tank to a solution B through a liquid conveying pipe and a liquid distributor, reacting the flue gas, the alkaline solution and the solution B to generate a solution C, intermittently removing the solution C with the same volume as that of the solution C flowing into the second reactor from the second reactor, reacting the solution C with chlorine gas, and then circulating the solution C into a solution A in a first storage tank, wherein the removing of the solution C from the second reactor and the removing of the solution B from the first storage tank are simultaneously finished, and the flow rates of the solution C and the solution B are kept to be the same. And stopping introducing the flue gas and the chlorine after the concentration of the sodium nitrite in the solution C is close to 70g/100ml, and discharging the solution C to a water treatment process. The total sulfur removal rate of the treated smoke is more than or equal to 96.5 percent, the total nitrogen oxide removal rate is more than or equal to 95 percent, and the total medicament cost is lower.
Comparative example one:
30000CMH identical to that of example one, with NO of 900mg/m3，NO2Is 100mg/m3After the NO is oxidized by the ozone to be the high-order nitrogen oxide, the waste gas is introduced into a reaction tower system, the sodium hydroxide and the sodium sulfite are used as absorption liquid, the addition amount of the ozone, the sodium hydroxide and the sodium sulfite is slightly larger than the corresponding molar ratio of the reaction formula of the ozone, the sodium hydroxide and the sodium sulfite to the corresponding nitrogen oxide, after the reaction of the reaction tower, the removal rate of the total nitrogen oxide is more than or equal to 85 percent, and the total medicament cost is higher (about 2 to 4 times of the embodiment) because the main medicament can not be recycled.
Comparative example two:
30000CMH, containing SO, identical to the phases of the example2Is 800 mg/m3NO of 900mg/m3，NO2Is 100mg/m3The waste gas is desulfurized by a limestone-gypsum method, NO is oxidized into high-order nitrogen oxides by hydrogen peroxide, the high-order nitrogen oxides are introduced into a reaction tower system, potassium hydroxide and sodium thiosulfate are used as absorption liquid, the addition amount of the hydrogen peroxide, the potassium hydroxide and the sodium thiosulfate is slightly larger than the corresponding molar ratio of the reaction formula of the hydrogen peroxide, the potassium hydroxide and the sodium thiosulfate to the corresponding nitrogen oxides, after the reaction of the reaction tower, the total sulfur oxide removal rate is more than or equal to 92 percent, the nitrogen oxide removal rate is more than or equal to 82 percent, and the total medicament cost is higher (about 2 to 4 times of the embodiment) because the main medicament.
In the above examples, the polyethers used have the following structure:
RO-(EO)m-(PO)nH
wherein R is n-butyl;
m=13，n=17。
experimental results show that the first to fifth embodiments realize the recycling of bromine, reduce the cost of nitrogen oxide treatment agents on the premise of higher denitration efficiency, greatly reduce the total material cost of desulfurization and denitration, obviously improve the removal rate of sulfur oxides and nitrogen oxides, realize the ultra-clean emission of desulfurization and denitration and reduce the cost.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes and modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (7)
1. A flue gas desulfurization and denitrification process is characterized by comprising the following steps:
s1: introducing chlorine into the solution A containing bromide ions to generate solution B containing elemental bromine;
s2: introducing flue gas into the solution B, spraying alkali liquor above the solution B while introducing the flue gas, and mixing and reacting the flue gas, the solution B and the alkali liquor to obtain a solution C;
s3: introducing chlorine into the solution C, and merging the chlorine into the solution A through a circulating pipeline;
when the concentration of the sodium nitrite in the solution A reaches 70g/100ml, stopping introducing the flue gas and the chlorine gas, and emptying the reaction system;
the solution A comprises bromide containing bromide ions, a complexing agent and polyether, wherein the ratio of bromide: complexing agent: the mass ratio of the polyether is 22-35:2-4.5: 1-3;
the complexing agent is selected from one of EDTA ferrous salt and ethylenediamine cobalt;
the polyether has the following structure:
RO-(EO)m-(PO)nH
wherein R is a C3-C8 starter group;
m, n are independently selected from integers from 10-20, and 25< m + n < 35;
the alkali liquor is one or two of sodium hydroxide, potassium hydroxide and calcium hydroxide.
2. The process of claim 1, wherein step S1 is preceded by a preceding desulfurization process.
3. The process of claim 2, wherein the pre-desulfurization process is one of a calcium process, a magnesium process, a sodium process, and an ammonia process.
4. The process of claim 1, comprising:
s1: putting the solution A into a reaction system A, and introducing chlorine into the solution A containing bromide ions to generate a solution B containing elemental bromine;
s2: transferring the generated solution B with a certain volume V into a reaction system B, introducing flue gas into the solution B, spraying alkali liquor above the solution B while introducing the flue gas, and mixing and reacting the flue gas, the solution B and the alkali liquor to obtain a solution C;
s3: extracting a certain volume V' of solution C, and circulating the solution C into the solution A;
and when the concentration of the sodium nitrite in the solution A reaches 70g/100ml, stopping introducing the flue gas and the chlorine gas, and emptying the reaction system.
5. In the step S3, after the extracted chlorine gas of the solution C reacts, the chlorine gas is merged into the solution A through a circulating pipeline;
the process of claim 4, wherein V = V'.
6. The process of claim 4, wherein the volume V of solution B extracted in step S2 is 50% -55% of the total volume of solution B in reaction system A.
7. The process of claim 4, wherein the volume V' of solution C extracted in step S3 is 10% -90% of the total volume of solution C in reaction system B.
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| CN116462160A (en) * | 2023-03-29 | 2023-07-21 | 大连交通大学 | By flue gas SO 2 Method and system for preparing steady-state chlorine dioxide for raw materials |
| CN116462160B (en) * | 2023-03-29 | 2024-05-24 | 大连交通大学 | By flue gas SO2Method and system for preparing steady-state chlorine dioxide for raw materials |
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