CN115282768A - Low-temperature flue gas denitration method for coal-fired unit and additive thereof - Google Patents
Low-temperature flue gas denitration method for coal-fired unit and additive thereof Download PDFInfo
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- CN115282768A CN115282768A CN202210780714.3A CN202210780714A CN115282768A CN 115282768 A CN115282768 A CN 115282768A CN 202210780714 A CN202210780714 A CN 202210780714A CN 115282768 A CN115282768 A CN 115282768A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/90—Injecting reactants
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/02—Other waste gases
- B01D2258/0283—Flue gases
Abstract
The invention provides a low-temperature flue gas denitration method of a coal-fired unit and an additive thereof, which do not need to modify a boiler and do not influence the efficiency of the boiler; convenient to use, the flexible operation, SCR denitration temperature range is wider, can realize coal-fired generating set full load denitration. The invention comprises 5-95% of ethanolamine and 5-95% of isopropylamine according to the parts by weight. When the temperature of the flue gas is low between 200 and 300 ℃, denitration is carried out by adopting the following method to obtain SO in the flue gas 2 According to the amount of ethanolamine and SO in the flue gas 2 Determining the use amount of the ethanolamine according to the linear relation of the concentration; acquiring the temperature of the flue gas, and determining the dosage parts of the isopropylamine according to the linear relation between the dosage of the isopropylamine and the temperature of the flue gas; according to the determined using parts of the ethanolamine and the isopropylamine, the ethanolamine and the isopropylamine are mixed to obtain a mixtureAt NH 3 The flue gas is injected into the position upstream of the injection hole.
Description
Technical Field
The invention relates to the technical field of flue gas denitration treatment, in particular to a low-temperature flue gas denitration method of a coal-fired unit and an additive thereof.
Background
The SCR denitration device in the coal-fired power plant adopts ammonia gas as a reducing agent, and is V 2 O 5 -WO 3 (MoO 3 )/TiO 2 NO in the flue gas and a reducing agent NH under the action of a catalyst 3 The following reaction takes place:
4NH 3 +4NO+O 2 →4N 2 +6H 2 O(1)
4NH 3 +2NO 2 +O 2 →3N 2 +6H 2 O(2)
because the NO content in the smoke gas accounts for NO X The concentration is 90-95%, and the SCR denitration chemical reaction mainly takes (1) as the main reaction. NH 3 And NO reacts heterogeneously on the surface of the catalyst, and the active center on the surface of the catalyst and the adsorbed reactant molecule form a transition state to generate a chemical reaction. Denitration reaction proceeds according to the Eley-Rideal mechanism, NH 3 Is adsorbed and then reacts with the NO molecules. As shown in fig. 1, flue gas NH 3 And NO X The Eley-riedal reaction mechanism process on the catalyst can be summarized as: (1) NH 3 By gas phase diffusion to the catalyst surface; (2) NH 3 Diffusing from the outer surface to the catalyst pores; (3) NH (NH) 3 Adsorbing on the active center; (4) NO X Diffusion from the gas phase to adsorbed NH 3 A surface; (5) NH (NH) 3 And NO X Reaction to form N 2 And H 2 O；(6)N 2 And H 2 O diffuses to the surface of the catalyst through micropores; (7) N is a radical of 2 And H 2 O diffuses into the bulk gas phase; the reaction process is shown in FIG. 2.
At present, coal-fired power plant V 2 O 5 -WO 3 (MoO 3 )/TiO 2 The optimal activity temperature range of the catalyst is 300-380 ℃, namely the denitration catalyst has the lowest ammonia spraying temperature which is specifically determined according to the moisture and SO in the flue gas 2 The concentration and denitration efficiency are related, and the approximate range is 280-320 ℃. When the temperature of the flue gas is lower than the lowest ammonia spraying temperature, the coal-fired unit needs to be stopped to avoid causing catalyst poisoning and inactivationThe ammonia injection is stopped, and the environmental protection assessment is caused after the nitrogen oxides exceed the standard; or measures are needed to improve the flue gas temperature, and the schemes comprise a coal economizer flue gas bypass, hot water recycling and the like, so that the improvement cost is high, the boiler efficiency is influenced, and the running economy of a power plant is reduced.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a low-temperature flue gas denitration method for a coal-fired unit and an additive thereof, which do not need to modify a boiler and do not influence the efficiency of the boiler; convenient to use, the flexible operation, SCR denitration temperature range is wideer, can realize coal-fired generating set full load denitration.
The invention is realized by the following technical scheme:
the low-temperature flue gas denitration additive for the coal-fired unit comprises, by mass, 5% -95% of ethanolamine and 5% -95% of isopropylamine.
Optionally, the ethanolamine is at least one of monoethanolamine, diethanolamine and triethanolamine.
Optionally, the additive is mixed in pure water or pyridine for use, and 10 parts by mass of the additive is mixed in 2 parts by mass of pure water or pyridine.
Optionally, the mass part of the ethanolamine is in positive correlation with the concentration of the acid gas in the low-temperature flue gas.
Optionally, the mass part of the isopropylamine is inversely related to the low-temperature flue gas temperature.
A low-temperature flue gas denitration method of a coal-fired unit, when the temperature of flue gas is 200-300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas 2 Determining the use amount of the ethanolamine according to the linear relation of the concentration;
acquiring the flue gas temperature, and determining the using amount of isopropylamine according to the linear relation between the using amount of the isopropylamine and the flue gas temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 Upstream of the injection holeAnd then the flue gas enters the flue gas.
Optionally, the amount of ethanolamine and SO in flue gas 2 The linear relationship of the concentrations is as follows,
when SO in flue gas 2 When the concentration is 1000ppm, the dosage of the ethanolamine is 1 part; when the content of the ethanolamine in the flue gas is 5000ppm, the amount of the ethanolamine is 19-20 parts.
Alternatively, the linear relationship between the dosage of the isopropylamine and the flue gas temperature is as follows,
when the smoke temperature is 300 ℃, the using amount of the isopropylamine is 1 part; when the temperature of the flue gas is reduced to 200 ℃, the using amount of the isopropylamine is 18 to 19 parts.
Optionally, the mixture is injected at a distance NH from the injection point 3 The position of the injection hole is at least 2m or more.
Compared with the prior art, the invention has the following beneficial technical effects:
the components of the additive are conventional chemical medicines, so the additive is convenient to purchase and low in price; the additive system does not influence the normal operation of the unit, and can be put into operation when needed or be stopped when not needed, so that the full-load denitration of the coal-fired generator set can be realized. Wherein, the ethanolamine mainly acts as acid gas SO 3 、SO 2 、HCl、HF、P 2 O 5 Etc. absorbent for preventing reducing agent NH 3 With acid gas SO 3 、SO 2 HCl, etc. to form NH 4 HSO 4 、NH 4 Cl, and the like. At the same time, ethanolamine diffused to the surface of the catalyst is decomposed into-NH 2 、-CH 3 A functional group such as-HCO, -CH 3 Functional groups such as-HCO and O in flue gas 2 The combustion reaction is carried out to release heat, the surface temperature of the catalyst is heated, the activity of the catalyst is improved, and the-NH is further improved 2 、NH 3 And the reaction rate with NO. Isopropylamine is mainly present as a surfactant to enhance the catalyst, further enhancing the catalyst's NH-to-NH ratio 3 Adsorption characteristics of (1) and acceleration of NH 3 Reaction with NO. Similarly, the isopropylamine diffused to the surface of the catalyst also decomposes to-NH at 200-400 deg.C 2 、-CH 3 -CH, -HCO and the like 3 Functional groups such as-HCO and O in flue gas 2 The combustion reaction is carried out to release heat, the surface temperature of the catalyst is heated, the activity of the catalyst is improved, and the-NH is further improved 2 、NH 3 And the reaction rate with NO.
Further, when SO in the flue gas 2 When the content of the ethanolamine is higher, the ethanolamine content in the additive needs to be properly increased to form positive correlation, so that more acid gases can be conveniently absorbed; when the temperature of the flue gas at the denitration inlet is lower, the need of increasing the content of the isopropylamine in the additive is negative correlation, so that the catalyst is conveniently heated by using the combustion heat of the isopropylamine in the micropores of the catalyst.
Further, the position of the additive injection flue should be arranged at NH 3 Upstream of the injection hole, additive and NH 3 The position of the injection hole is at least more than 2m away, SO that the additive can fully absorb the acid gas SO in the flue gas in the first step 3 、SO 2 HCl, and the like.
Drawings
FIG. 1 is a schematic diagram of the Eley-Rideal mechanism of SCR denitration reaction in the prior art.
FIG. 2 is a schematic diagram of the SCR reaction process in the prior art.
FIG. 3 is a bench for testing the performance of the additive in the present example.
In the figure: 1-a filter; 2-self-operated pressure regulating valve; 3-a pressure gauge; 4-mass flow meter; 5-a float flow meter; 6-a one-way valve; 7-a mixer; 8-controlling the temperature of a heater; 9-a flow meter; 10-flue gas analyzer; 11-temperature control of the reactor.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
In the prior art, SO exists in flue gas of a coal-fired unit 2 、SO 3 、HCl、HF、P 2 O 5 Equal amount of acid gas and H 2 O, gaseous arsenic (As) 2 O 3 ) And the like, and carries smoke dust generated after coal combustion, wherein the main components of the smoke dust comprise CaO and N 2 O、K 2 O, etc., which affect the activity of the catalyst. Alkaline gas when the temperature of flue gas is lowNH 3 Is easier to react with acid gas SO 3 、SO 2 、HCl、HF、P 2 O 5 Isotropic reaction to produce NH 4 HSO 4 、NH 4 Cl、CaSO 4 、KCl、ZnCl 2 And the like, which affect the activity of the catalyst, and such substances block catalyst micropores or occupy active sites of the catalyst.
In order to solve the denitration of the lower condition of gas temperature, all adopt technical means to reform transform the boiler in a large number at present, improve the problem that denitration device entry gas temperature satisfies the minimum ammonia injection temperature of denitration catalyst. The method for improving the denitration flue gas temperature of the conventional coal-fired power plant mainly comprises the steps of classifying an economizer, bypassing the flue gas of the economizer, bypassing the water side of the economizer, recycling hot water and the like, wherein a large amount of improvement needs to be carried out on a boiler in several schemes, the efficiency of the boiler is influenced after the improvement, the economy is reduced, the overhaul and maintenance workload is large, and the inlet flue gas temperature of the denitration reactor is generally required to be improved to 300-320 ℃.
The invention provides an additive and a method for improving the denitration efficiency of a coal-fired unit under the condition of low-temperature flue gas, the method does not need to modify a boiler, only a set of injection system is additionally arranged at the position of a flue at a denitration inlet to inject an additive solution into the flue, even if the temperature of the flue gas at the denitration inlet can be used at 200-300 ℃, the operation cost is low, the modification workload is small, and the boiler efficiency is not influenced.
The invention provides an additive which can be assisted by V 2 O 5 -WO 3 (MoO 3 )/TiO 2 Catalyst function, NH adsorbed on the surface of the catalyst 3 Conversion to-NH 2 The catalyst can directly generate rapid denitration reaction with NO in the flue gas at the active point position on the surface of the SCR catalyst, thereby improving the reaction rate of the SCR, improving the low-temperature catalytic activity of the catalyst and greatly reducing ammonia escape; at the same time, -NH 2 With SO in flue gas 2 Acid gases such As HCl do not react with each other and As is not produced 2 O 3 、NH 4 HSO 4 And NH 4 Cl, etc., which cause catalyst deactivation.
The additive is an amine-containing substance, the main component of the additive is a mixture of ethanolamine and isopropylamine, the mass ratio of the ethanolamine in the mixture is 5-95%, and the mass ratio of the isopropylamine is 5-95%. Among these, various amine-containing organic compounds can be used as ethanolamine, for example: at least one of monoethanolamine, diethanolamine, and triethanolamine; in addition, for the convenience of storage at ambient temperature, the additive is mixed with other chemicals capable of raising the boiling point of the additive, such as, for example, pure water, pyridine, etc.; according to the mass portion, 10 portions of additive are mixed into 2 portions of pure water or pyridine.
The content of ethanolamine in the additive of the invention is mainly composed of SO 2 The concentration of ethanolamine, the amount of ethanolamine and SO in flue gas 2 The concentration is substantially linear. SO in flue gas 2 When the concentration is 1000ppm, the dosage of the ethanolamine is 1 part; when the content of the ethanolamine in the flue gas is 5000ppm, the amount of the ethanolamine is 19-20 parts.
The content of the isopropylamine in the additive is mainly determined by the temperature of the flue gas, and the dosage of the isopropylamine and the temperature of the flue gas are basically in a linear relationship. When the smoke temperature is 300 ℃, the using amount of the isopropylamine is 1 part; when the temperature of the flue gas is reduced to 200 ℃, the using amount of the isopropylamine is 18 to 19 parts.
The total mass of the additive is positively correlated with the flue gas quantity of the unit, and the specific value is the flue gas quantity and SO 2 The concentration and the flue gas temperature are determined and can be calculated by the prior art; the dosage parts of the ethanolamine and the isopropylamine are unit parts of the ethanolamine and the isopropylamine under the corresponding flue gas amount of the unit, and the ethanolamine and the isopropylamine are calculated independently.
The additive comparative tests were carried out using the test stand of fig. 3, using the same denitration catalyst, while controlling the denitration inlet flue gas temperatures at 250 ℃ and 270 ℃ under load. The test conditions were as follows: the concentration of NO at the denitration inlet is 200ppm and SO 2 The concentration is 2500ppm, O 2 The concentration was 6%.
The temperature of the flue gas at the denitration inlet is 250 ℃, and NH at the denitration inlet is controlled 3 Concentration 180ppm, NO concentration 52ppm at the reactor outlet without addition of additives, denitration efficiency 74%, according to mass conservation, about 32ppm of NH 3 Does not participate in the reaction. Adding 8 parts of ethanolamine and 10 parts of isopropylamine to prepareOf an additive capable of providing-NH 2 About 50ppm of functional groups, and adjusting denitration inlet NH 3 At a concentration of 130ppm, the reactor outlet NO concentration was 26ppm and the denitration efficiency was 87%, according to the mass conservation, about 6ppm of NH 3 Does not participate in the reaction.
The temperature of the flue gas at the denitration inlet is 270 ℃, and NH at the denitration inlet is controlled 3 Concentration 180ppm, NO concentration 38ppm at the reactor outlet without addition of additives, denitration efficiency 81%, according to mass conservation, about 18ppm of NH 3 Does not participate in the reaction. Adding an additive prepared from 8 parts of ethanolamine and 6-7 parts of isopropylamine, wherein the additive provides-NH 2 About 30ppm of functional group, and NH at denitration inlet 3 At a concentration of 150ppm, the reactor outlet NO concentration was 22ppm and the denitration efficiency was 89%, according to the mass conservation, about 2ppm of NH 3 Does not participate in the reaction.
Therefore, the additive can improve the activity of the catalyst under the condition of low temperature, improve the denitration efficiency and reduce the escape of ammonia.
Example 1
When the temperature of the flue gas is low between 200 and 300 ℃, the method is adopted for denitration,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas, the concentration of the ammonium sulfate is 1000ppm 2 Determining the linear relation of concentration, wherein the use amount of the ethanolamine is 1 part;
obtaining the smoke temperature of 200 ℃, and determining 19 parts of isopropylamine according to the linear relation between the usage of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected at a position upstream of the injection hole, and the denitration efficiency at a temperature of 200 ℃ was found to be 83%.
Example 2
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in flue gas, the concentration of (A) is 1000ppm 2 Linear relationship of concentration, determining the amount of ethanolamineIs 1 part;
acquiring the smoke temperature of 250 ℃, and determining the using amount of isopropylamine in 10 parts according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and reacting the mixture with NH 3 The flue gas was injected upstream of the injection holes to obtain a denitration efficiency of 86% at a temperature of 250 ℃.
Example 3
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in flue gas, the concentration of (A) is 1000ppm 2 Determining the use amount of the ethanolamine as 1 part according to the linear relation of the concentration;
acquiring the smoke temperature of 300 ℃, and determining the using amount of the isopropylamine to be 1 part according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected at a position upstream of the injection hole, and the denitration efficiency at a temperature of 300 ℃ was found to be 87%.
Example 4
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in flue gas, the concentration of (A) is 1000ppm 2 Determining the use amount of the ethanolamine as 1 part according to the linear relation of the concentration;
obtaining the smoke temperature of 200 ℃, and determining the using amount of the isopropylamine to be 18 parts according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected at a position upstream of the injection hole, and the denitration efficiency at a temperature of 300 ℃ was 82%.
Example 5
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas, the concentration of (A) is 2000ppm 2 Determining the linear relation of concentration, wherein the part of the ethanolamine is 5 parts;
acquiring the smoke temperature of 250 ℃, and determining the using amount of isopropylamine in 10 parts according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected at a position upstream of the injection hole, and the denitration efficiency at a temperature of 250 ℃ was found to be 83%.
Example 6
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas, the concentration of (A) is 3000ppm 2 Determining the linear relation of concentration, wherein the use amount of the ethanolamine is 10 parts;
acquiring the smoke temperature of 250 ℃, and determining the using amount of isopropylamine in 10 parts according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected at a position upstream of the injection hole, and the denitration efficiency at a temperature of 250 ℃ was found to be 83%.
Example 7
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas, the concentration of (A) is 4000ppm 2 Determining the linear relation of concentration, wherein the use amount of the ethanolamine is 15 parts;
acquiring the smoke temperature of 250 ℃, and determining the using amount of isopropylamine in 10 parts according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 Upstream of the injection holeThe position is injected into flue gas, and the denitration efficiency is 84% at the temperature of 250 ℃.
Example 8
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas, the concentration of (A) is 5000ppm 2 Determining the part of the ethanolamine to be 19 parts according to the linear relation of the concentration;
obtaining the smoke temperature of 250 ℃, and determining 10 parts of isopropylamine according to the linear relation between the dosage of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected at a position upstream of the injection hole to obtain a denitration efficiency of 85% at a temperature of 250 ℃.
Example 9
When the temperature of the flue gas is low between 200 and 300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas, the concentration of (A) is 5000ppm 2 Determining the linear relation of concentration, wherein the use amount of the ethanolamine is 20 parts;
acquiring the smoke temperature of 250 ℃, and determining the using amount of isopropylamine in 10 parts according to the linear relation between the using amount of the isopropylamine and the smoke temperature;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and adding the mixture into NH 3 The flue gas was injected upstream of the injection holes to achieve a denitration efficiency of 85% at a temperature of 250 ℃.
Claims (9)
1. The low-temperature flue gas denitration additive for the coal-fired unit is characterized by comprising 5-95% of ethanolamine and 5-95% of isopropylamine in parts by weight.
2. The low-temperature flue gas denitration additive for the coal-fired unit as set forth in claim 1, wherein the ethanolamine is at least one of monoethanolamine, diethanolamine and triethanolamine.
3. The low-temperature flue gas denitration additive for the coal-fired unit according to claim 1, wherein the additive is mixed in pure water or pyridine for use, and 10 parts of the additive are mixed in 2 parts of pure water or pyridine by mass.
4. The low-temperature flue gas denitration additive for the coal-fired unit according to claim 1, wherein the mass fraction of the ethanolamine is in positive correlation with the concentration of acid gas in low-temperature flue gas.
5. The low-temperature flue gas denitration additive for the coal-fired unit as recited in claim 1, wherein the mass fraction of isopropylamine is inversely related to the low-temperature flue gas temperature.
6. A low-temperature flue gas denitration method for a coal-fired unit is characterized in that when the flue gas temperature is 200-300 ℃, the denitration is carried out by adopting the following method,
obtaining SO in flue gas 2 According to the amount of ethanolamine and SO in the flue gas 2 Determining the use amount of ethanolamine according to the linear relation of concentration;
acquiring the temperature of the flue gas, and determining the dosage parts of the isopropylamine according to the linear relation between the dosage of the isopropylamine and the temperature of the flue gas;
according to the determined using parts of the ethanolamine and the isopropylamine, mixing the ethanolamine and the isopropylamine to obtain a mixture, and reacting the mixture with NH 3 The upstream position of the injection hole injects the flue gas.
7. The low-temperature flue gas denitration method for coal-fired unit as recited in claim 6, wherein the amount of ethanolamine and SO in flue gas are used 2 The linear relationship of the concentrations is as follows,
when SO in the flue gas 2 When the concentration is 1000ppm, the dosage of the ethanolamine is 1 part; when the content of the ethanolamine in the flue gas is 5000ppm, the amount of the ethanolamine is 19-20 parts.
8. The method for low-temperature flue gas denitration of a coal-fired unit according to claim 6, wherein the linear relationship between the usage amount of isopropylamine and the flue gas temperature is as follows,
when the smoke temperature is 300 ℃, the using amount of the isopropylamine is 1 part; when the temperature of the flue gas is reduced to 200 ℃, the using amount of the isopropylamine is 18 to 19 parts.
9. The low-temperature flue gas denitration method for coal-fired unit as defined in claim 6, wherein the injection position of the mixture is distant from NH 3 The position of the injection hole is at least 2m or more.
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