CN111644029A - Low-temperature denitration, dedusting and whitening process device after wet desulphurization - Google Patents
Low-temperature denitration, dedusting and whitening process device after wet desulphurization Download PDFInfo
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Abstract
A low-temperature denitration dedusting and whitening process device after wet desulphurization comprises a desulphurization spraying system connected with a desulphurization circulating tank; the desulfurization spraying system is communicated with the first flue, the initial condensing system, a low-temperature side inlet and a low-temperature side outlet of the heat exchanger, the temperature compensation heating system, the denitration reducing agent ammonia spraying grid, the flue gas flow field mixer, the flue gas flow field rectifier, the SCR denitration catalyst reserved space, the SCR denitration catalyst I and the SCR denitration catalyst II in sequence through the desulfurization tower; the flue gas flow field rectifier is communicated with a high-temperature side inlet of the heat exchanger; the high-temperature side outlet is communicated with the bag-type dust collector through a communicating flue II, a communicating flue III, an induced draft fan power system, a communicating flue IV and a secondary condensation system; the water discharged by the desulfurization liquid reflux system, the primary condensation system return water system and the secondary condensation system return water system all flow back to the desulfurization circulating tank; the flue gas is subjected to desulfurization, primary condensation, denitration reducing agent injection system, denitration, dust removal, secondary condensation, whitening treatment and synergistic whitening treatment, and the method has the characteristics of simple structure, energy conservation and water conservation.
Description
Technical Field
The invention belongs to the technical field of flue gas denitration, dust removal and whitening, and particularly relates to a low-temperature denitration, dust removal and whitening process device after wet desulphurization.
Background
In recent years, the environment protection situation of China is increasingly severe, although a good treatment effect is achieved, the factors such as development of environmental protection technologies in various industries and regions, limit values of regional policies and the like exist, and the emission of smoke is still not effectively treated. Resulting in the threat of human health and life to Nitrogen Oxides (NOX), sulfur dioxide (SO2), and particulate matter in the flue gas. The main source of the pollutants is fuel combustion, namely man-made source, and the nitrogen oxides can penetrate deep into the lung of a human body to induce respiratory diseases; and is also one of the causes of acid rain; sulfur dioxide is a toxic gas to which people with heart and respiratory diseases are most sensitive, i.e., normal people are ill too long in places with too high a concentration of sulfur dioxide. And is also one of the causes of acid rain.
In order to realize better environmental protection treatment, the national environmental protection emission standard is carried out for a plurality of times in recent years, a plurality of enterprises are discharged for environmental protection up to the standard, and a large amount of funds are invested for environmental protection treatment.
Although the existing technology in the wet desulphurization or low-temperature flue gas treatment industry is various, although the corresponding pollutants can be quantitatively discharged, the existing technology has certain problems, or causes that the equipment is unstable in operation, the operation cost is overhigh, new pollution is generated, the investment cost is too high, the removal efficiency is low, the treatment technology is not properly selected, or the local government forbids the use of the technology, and the like. Because desulfurization, denitration, dust removal can not realize administering simultaneously, to different pollutants, the main treatment technique of trade is as follows:
low-temperature denitration technology
The denitration treatment technology is inseparable from the flue gas temperature, and the denitration treatment technology of the high-temperature flue gas tends to be mature, which is not described herein any more. At present, low-temperature denitration treatment technology is mainly discussed. The main low-temperature denitration treatment technology in the industry is as follows.
(I) ozone denitration technology:
the strong oxidizing property of ozone is utilized to oxidize NO (the NO content in the flue gas nitrogen oxide is about more than 95 percent and is difficult to dissolve in water) in the nitrogen oxide into high-valence nitrogen oxide (mainly NO2 which is easy to dissolve in water), alkali washing is carried out in a subsequent alkali washing tower, and nitric acid formed by dissolving NO2 in water is neutralized by alkali liquor. The problems of the technology are as follows:
1) the source of the ozone is mainly prepared by oxygen, the source of the oxygen is directly purchased by a using unit or prepared by an oxygen generator, the investment cost of the ozone generator and the oxygen generator is high, and the later operation cost is huge (high-power equipment, mainly electricity consumption);
2) can cause excessive discharge of ozone, resulting in new environmental pollution;
3) the method is more suitable for treating low-concentration nitrogen oxides, and is not ideal for treating high-concentration nitrogen oxides;
4) the final removal treatment is completed by using a post-positioned alkaline washing tower, so that the final removal treatment can be only arranged before desulfurization, otherwise, the investment waste is caused;
(II) wet oxidation denitration technology:
the method is characterized in that a denitration agent solution is prepared by utilizing sodium hypochlorite (NaClO2) with strong oxidizing property, a process of oxidizing nitrogen oxides into nitric acid by using the denitration agent, and a process of reacting with liquid alkaline absorption liquid to generate sulfate and nitrate. The removal principle is similar to that of the ozone denitration technology. The problems of the technology are as follows:
1) the source of the denitrifier is mainly provided by professional suppliers, although the equipment investment cost is not high, the procurement cost of the denitrifier is high, and the later-stage operation cost is huge;
2) a large amount of sewage is generated, new environmental pollution is caused, and sewage treatment is needed;
3) the method is more suitable for treating low-concentration nitrogen oxides, and is not ideal for treating high-concentration nitrogen oxides;
4) the final removal treatment is completed by using a post-positioned alkaline washing tower, so that the final removal treatment can be only arranged before desulfurization, otherwise, the investment waste is caused;
(III) SCR denitration technology
Under the action of catalyst, reducing agent (generally ammonia water, urea and hydrogen peroxide) is used to convert nitrogen oxide into nitrogen (N) at high temp. (above 280 deg.C)2) And water (H)2O), harmless desorption, the technology has low cost and running cost, is widely applied to conventional flue gas denitration and is widely supported by the government, but has the following defects in the industry of wet desulphurization or low-temperature flue gas treatment:
1) the catalytic reaction temperature requirement is high, the temperature needs to reach more than 280 ℃, and the low-temperature flue gas does not meet the treatment requirement;
2) the wet desulfurization flue gas has high water vapor content, and the catalyst is easy to inactivate when meeting water, so that the catalyst is damaged;
3) after the reducing agent is sprayed into the flue gas at a low temperature, the reducing agent can react with sulfur dioxide in the flue gas to generate ammonium sulfate salt, and the ammonium sulfate salt can adhere to the catalyst to cause the blockage and inactivation of the catalyst;
4) in order to reach the reaction temperature, the flue gas (generally about 50 ℃) subjected to wet desulphurization needs to be heated to more than 280 ℃, so that huge energy is needed, and the energy cannot be borne by common enterprises;
(IV) SNCR denitration technology
Under the action of high temperature (over 800 ℃) of a hearth, nitrogen oxides are converted into nitrogen (N2) and water (H2O) by using reducing agents (generally ammonia water, urea and hydrogen peroxide) for harmless removal, the manufacturing cost and the operating cost of the technology are low, but the removal efficiency is also low, and the current environment-friendly policy of ultralow emission cannot be met.
Second, desulfurization technique
The desulfurization technology (removing sulfur dioxide) has little relation with the temperature of the flue gas, and the mainstream desulfurization technologies in the industry at present comprise a wet desulfurization technology, a semi-dry desulfurization technology and a dry desulfurization technology, which can effectively treat the sulfur dioxide to meet the requirement of ultralow emission. And the government has no excessive limit on which desulfurization technology is used. The following problems still remain.
1) The wet desulphurization flue gas has high humidity and hidden danger of whitening of the flue gas, and the existing flue gas whitening treatment is incorporated into the content of environmental protection treatment;
2) the semi-dry desulfurization and dry desulfurization technologies can cause the exceeding of particulate matters, and a dust remover needs to be matched to finish the ultra-low emission treatment target. The method is not suitable for reforming enterprises, and is generally suitable for newly-built enterprises.
3) The cost and the operating cost of wet desulphurization are low, a large number of enterprises have established wet desulphurization at present, and the investment cost is huge when the desulphurization is directly carried out, so that a large amount of resources are wasted; if the semi-dry desulfurization and dry desulfurization are pushed to be newly built, the resource waste is larger, and the problems are generally faced to the reconstruction and upgrading of enterprises.
4) The wet desulphurization flue gas has high humidity, great influence on subsequent equipment, and the SCR denitration technology with optimal cost performance is difficult to be widely applied after wet desulphurization;
dust removing technology
Under the environment-friendly situation of ultralow emission, the technologies such as gravity dust removal and cyclone dust removal can not meet the requirements, the electric dust removal and bag dust removal technologies can efficiently meet the purpose of removing particles, a large amount of particles in flue gas are removed by the general preposition of electric dust removal, and the postposition of a bag dust remover can ensure that the particles meet the requirement of ultralow emission. Therefore, the cloth bag dust removal plays an important role in ultra-low emission. However, under the condition of low-temperature flue gas after wet desulphurization, the flue gas humidity and temperature can affect the dust removal technology (removing particulate matters), mainly as follows;
1) the flue gas humidity is high, so that a bag of the bag-type dust collector is stuck, the resistance is increased, and the filtering effect is reduced;
2) the temperature of the flue gas is lower than the dew point temperature (below 100 ℃), which causes the corrosion of the interior of the dust remover, bag pasting of the cloth bag and the like;
3) the electric dust removal has a poor treatment effect on low-concentration particles, but has a good treatment effect on high-concentration particles, so that the electric dust removal is generally used as a preposition;
4) flue gas with high low temperature and humidity can form a large amount of condensed water in the dust remover, so that the dust removal efficiency and stable operation of equipment are influenced;
in conclusion, aiming at the treatment problems of wet desulphurization, low-temperature flue gas desulphurization, denitration and dust removal, the comprehensive treatment technology in the wet desulphurization and low-temperature flue gas industry has the following problems:
1) in order to reduce the cost of equipment, an SCR denitration system is arranged in front of desulfurization, high-concentration sulfur dioxide reacts with sprayed reducing agent, and reactants are deposited on the surface and pore channels of the catalyst, so that the serious problems of catalyst activity reduction, blockage and the like are caused. Meanwhile, a large amount of moisture in the flue gas causes catalyst deactivation, and the stable operation of system equipment is seriously influenced;
2) in order to reduce equipment investment, wet oxidation denitration and wet desulfurization technologies are selected, so that the equipment operation cost is huge, the potential hazard of whitening treatment exists, the operation cost is too high, and the equipment dismantling risk exists due to the fact that the local government forbids wet oxidation denitration;
3) the method adopts ozone denitration or wet oxidation denitration, so that new environmental pollution is generated, hidden danger of whitening treatment exists, the operation cost is too high, and the risk of equipment dismantling exists due to the fact that ozone denitration is forbidden by local governments;
4) SCR denitration or ozone denitration is adopted by heating flue gas, so that the equipment investment cost is high, and the later operation cost is huge;
5) in order to reduce the operation cost and the equipment cost, the SNCR denitration technology with low removal efficiency is selected, and the treatment requirement of ultralow emission cannot be met;
6) wet oxidation denitration or ozone denitration is added behind the desulfurizing tower, and meanwhile, a newly-built alkaline washing tower is used for removing nitric oxides, so that improper treatment technology selection causes resource waste;
7) the operation problems of bag pasting, serious corrosion and the like caused by newly building a bag-type dust remover after wet desulphurization and low-temperature flue gas are not treated, and the treatment technology is not properly selected;
8) the treatment technologies forbidden by local governments such as ozone denitration, wet oxidation denitration and the like are selected, so that the demolition risk is high, and the long-term investment is not facilitated;
9) the treatment technology of whitening the flue gas caused by wet desulphurization, wet denitration, ozone denitration and the like is selected, and the later-stage whitening treatment cost is high;
10) in the treatment of the problems of wet desulphurization, low-temperature flue gas desulphurization, denitration and dust removal, social and civil problems such as flue gas whitening, energy conservation, water conservation and the like are not considered as resources, and the aim of diversified and systematic treatment cannot be achieved.
Therefore, the key point is to find a novel low-temperature denitration dedusting and whitening process after wet desulphurization, and meanwhile, the aims of energy conservation and water conservation can be achieved in the treatment process, and diversified and systematic treatment is realized.
Under the condition of fully utilizing wet desulphurization and low-temperature flue gas, reasonable technology and process arrangement are added, the characteristics of desulphurization, denitration, dust removal and de-whitening process are fully combined, the influence of the existing process parameters mentioned in the desulphurization, denitration and dust removal processes on the treatment technology is avoided, the desulphurization, denitration and dust removal are ensured to stably run, the de-whitening treatment is cooperatively realized, and the treatment purposes of energy conservation and water conservation are achieved. And unnecessary huge economic loss is not brought to the existing enterprises. Meanwhile, the integration of desulfurization, denitration, dust removal, whitening removal, energy conservation and water conservation treatment is ensured, and the optimal matching is realized, so that the invention is the problem to be solved.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention aims to provide a low-temperature denitration dust-removal and whitening process device after wet desulphurization, which can realize wet desulphurization, denitration of low-temperature flue gas, dust removal, whitening removal, energy conservation and water conservation treatment, so that the flue gas meets the requirement of ultralow emission, and the principle of minimizing construction cost and operation cost can be realized; and a large amount of heat energy and water resources in the discharged flue gas can be recovered, and the method has the characteristics of energy conservation, water conservation and reasonable utilization of resources.
In order to achieve the purpose, the invention adopts the technical scheme that: a novel low-temperature denitration dedusting and whitening process device after wet desulphurization comprises a desulphurization spraying system, a desulphurization liquid reflux system, an initial condensation system return water system and a secondary condensation system return water system which are connected with a desulphurization circulating tank; the outlet of the desulfurization spraying system is connected with the left flue gas inlet of the desulfurization tower; a top flue gas outlet of the desulfurizing tower is communicated with a low-temperature side inlet of the heat exchanger sequentially through a first communicating flue, a first initial condensing system and a first pipeline; the low-temperature side outlet of the heat exchanger is sequentially connected with a temperature compensation heating system, a denitration reducing agent ammonia spraying grid, a flue gas flow field mixer and a flue gas flow field rectifier; the lower side of the flue gas flow field rectifier is provided with a reserved space for the SCR denitration catalyst; the lower part of the SCR denitration catalyst reserved space is sequentially provided with an SCR denitration catalyst I and an SCR denitration catalyst II; the denitration reducing agent storage system sprays the reducing agent into the denitration reducing agent injection grid through the denitration reducing agent injection system; the outlet end of the reactor is communicated with the high-temperature side inlet of the heat exchanger; the high-temperature side outlet of the heat exchanger is communicated with the bag-type dust collector through a communicating flue II; the outlet of the bag-type dust collector is communicated with the secondary condensation system through a third communicating flue, an induced draft fan power system and a fourth communicating flue;
the desulfurization solution reflux system pipeline is connected with the bottom of the desulfurization tower; and outlet pipelines of the primary condensation system water return system and the secondary condensation system water return system are respectively communicated with the desulfurization circulating tank.
A denitration reducing agent injection grid and a flue gas flow field mixer are arranged in the second pipeline; the denitration reducing agent injection grid is connected with the denitration reducing agent storage system through the denitration reducing agent injection system.
And the temperature compensation heating system is connected with the outlet at the low-temperature side of the heat exchanger.
And the high-temperature side outlet of the heat exchanger is connected with the bag-type dust collector through a communicating flue II, the high-temperature side inlet of the heat exchanger is connected with the reactor, the low-temperature side outlet of the heat exchanger is connected with the temperature compensation heating system, and the low-temperature side inlet of the heat exchanger is connected with the initial condensation system.
The reactor is internally provided with an SCR denitration catalyst reserved space, an SCR denitration catalyst I and an SCR denitration catalyst II.
The heat exchanger realizes heat exchange through a rotary heating surface.
Compared with the prior art, the invention has the beneficial effects that:
1) the invention utilizes the treatment technologies of wet desulfurization, low-temperature flue gas, an initial condensation system, a special heat exchanger, temperature compensation heating, SCR denitration, a bag-type dust remover and a secondary condensation system (chimney), thereby realizing the treatment of wet desulfurization, low-temperature flue gas desulfurization, denitration, dust removal, whitening, energy conservation and water conservation;
2) the invention utilizes wet desulphurization and low-temperature flue gas to pass through the primary condensation system, the temperature is reduced to about 20 ℃, a large amount of moisture in the flue gas can be condensed and separated out, and the moisture condition of the flue gas is ensured to reach the inlet standard of a heat exchanger. Meanwhile, the recovered condensate water is collected and then conveyed to a desulfurization system for recycling, so that primary water saving is realized;
3) the invention utilizes the special heat exchanger technology, recovers 70 percent of heat in the discharged flue gas through reasonable technical design, realizes that the low-temperature original flue gas is heated to more than 260 ℃ at 50 ℃, realizes the recovery and reutilization of waste heat of the discharged flue gas, and achieves the aim of energy conservation;
4) because the low-temperature flue gas has certain corrosivity before entering the heat exchanger, the invention carries out anticorrosion treatment on the inner wall of the heat exchanger, and simultaneously carries out special design on the heat exchange sheets, adds an enamel anticorrosion process to the special-shaped heat exchange sheets and ensures the technical performance of the heat exchanger; \ u
5) According to the invention, by utilizing a temperature compensation heating technology and through reasonable structural arrangement, if the temperature of flue gas after a heat exchanger cannot reach more than 280 ℃ of the SCR denitration inlet temperature, proper temperature compensation heating is carried out;
6) the invention fully utilizes the characteristics of high SCR denitration efficiency and low investment and operation cost. Through reasonable ammonia spraying flow field design, temperature compensation heating flow field design, flue gas diversion design and the like, flue gas, a reducing agent and high-temperature flue gas are fully and uniformly mixed through a denitration reducing agent spraying grid, a flue gas flow field mixer and a flue gas flow field rectifier, and SCR efficient denitration is realized;
7) the invention utilizes the characteristics of high removal efficiency of the bag-type dust remover and suitability for ultra-low emission, and enables low-temperature flue gas to pass through the technologies of condensation, heat exchange, compensation heating and the like, and simultaneously ensures that the temperature entering the bag-type dust remover is above the dew point temperature of 105 ℃, and the humidity of the treated flue gas is far lower than the inlet index of the bag-type dust remover, thereby realizing the reasonable, high-efficiency and practical use of the bag-type dust remover;
8) the invention fully utilizes the chimney as a secondary condensation system to carry out secondary condensation on the moisture in the discharged flue gas, and condensed water enters a desulfurization circulating system after being collected. The water is saved, and the synergistic treatment of the white removal of the flue gas is realized without any investment of white removal treatment after the flue gas is subjected to a two-stage condensation process, a temperature rise and drop heat exchange process and a temperature compensation heating process;
9) the technology realizes the whitening treatment on the basis of desulfurization, denitrification and dust removal through resource design, and avoids the huge investment of the enterprise whitening treatment;
10) the invention is designed by two-section condensate water process technology, thereby greatly reducing the water loss of wet desulphurization flue gas with water and greatly reducing the operation cost of enterprise desulphurization systems;
11) according to the invention, through reasonable heat exchanger process design, 70% of flue gas waste heat in the discharged flue gas is recovered to heat the inlet flue gas, so that the operation cost of an enterprise denitration system is greatly reduced;
12) according to the invention, a catalyst filling space is reserved in the denitration reaction, and when the environmental protection index is raised in the later period, lower emission can be realized only by adding the catalyst, secondary modification is not needed, and the secondary upgrading later-period modification cost is greatly reduced.
13) The invention opens up a new treatment concept for wet desulphurization and low-temperature flue gas treatment, realizes resource and diversified energy-saving and water-saving treatment, and provides precious technology for wet desulphurization, low-temperature flue gas desulphurization, denitration, dust removal and whitening treatment.
Drawings
FIG. 1 is a schematic structural diagram of the present invention.
In the figure: 1-a desulfurization circulating tank; 2-desulfurization spraying system; 3-desulfurization solution reflux system; 4-a desulfurizing tower; 5, an initial condensation system; 6-denitration reducing agent injection grid; 7-flue gas flow field mixer; 8-temperature compensation heating system; 9-SCR denitration catalyst I; 10-SCR denitration catalyst II; 11-flue gas flow field rectifier; 12-reserving space for SCR denitration catalyst; 13-low temperature side inlet of heat exchanger; 14-bag dust collector; 15-power system of induced draft fan; 16-secondary condensation system; 17-a return water system of the initial condensation system; 18-secondary condensation system water return system; 19-a first communicating flue; 20-a denitration reductant storage system; 21-denitration reducing agent injection system; 22-high temperature side outlet of heat exchanger; 23-low temperature side outlet of heat exchanger; 24-high temperature side inlet of heat exchanger; 25-a heat exchanger; 26-a second communicating flue; 27-a third communicating flue; 28-communicating a flue IV; 29-reactor.
Detailed Description
The structural and operational principles of the present invention are explained in further detail below with reference to the accompanying drawings and examples.
Referring to fig. 1, a low-temperature denitration dust-removal and whitening process device after wet desulfurization comprises a desulfurization spraying system 2, a desulfurization liquid reflux system 3, an initial condensation system return water system 17 and a secondary condensation system return water system 18 which are connected with a desulfurization circulating tank 1; the outlet of the desulfurization spraying system 2 is connected with the left flue gas inlet of the desulfurization tower 4; a top flue gas outlet of the desulfurizing tower 4 is communicated with a low-temperature side inlet 13 of the heat exchanger sequentially through a first communicating flue 19, an initial condensing system 5 and a first pipeline; a low-temperature side outlet 23 of the heat exchanger is connected with a temperature compensation heating system 8, a denitration reducing agent ammonia spraying grid 6, a flue gas flow field mixer 7 and a flue gas flow field rectifier 11; the lower side of the flue gas flow field rectifier 11 is provided with an SCR denitration catalyst reserved space 12; the lower part of the SCR denitration catalyst reserved space 12 is sequentially provided with a first SCR denitration catalyst 9 and a second SCR denitration catalyst 10; the denitration reducing agent storage system 20 sprays the reducing agent into the denitration reducing agent injection grid 6 through the denitration reducing agent injection system 21; the outlet end of the reactor 29 is communicated with the high-temperature side inlet 24 of the heat exchanger; the high-temperature side outlet 22 of the heat exchanger is communicated with the bag-type dust collector 14 through a second communicating flue 26; the outlet of the bag-type dust collector 14 is communicated with a secondary condensation system (chimney) 16 through a third communicating flue 27, an induced draft fan power system 15 and a fourth communicating flue 28;
the pipeline of the desulfurization liquid reflux system 3 is connected with the bottom of the desulfurization tower 4; and outlet pipelines of the primary condensation system water return system 17 and the secondary condensation system water return system 18 are respectively communicated with the desulfurization circulating tank 1.
A denitration reducing agent injection grid 6 and a flue gas flow field mixer 7 are arranged in the second pipeline; denitration reductant injection grid 6 is connected with denitration reductant storage system 20 through denitration reductant injection system 21.
The temperature compensation heating system 8 is connected with a low-temperature side outlet 23 of the heat exchanger.
And a high-temperature side outlet 22 of the heat exchanger is connected with the bag-type dust collector 14 through a second communicating flue 26, a high-temperature side inlet 24 of the heat exchanger is connected with a reactor 29, a low-temperature side outlet 23 of the heat exchanger is connected with the temperature compensation heating system 8, and a low-temperature side inlet 13 of the heat exchanger is connected with the initial condensation system 5. The desulfurized low-temperature flue gas and the denitrated high-temperature flue gas exchange heat through the heat exchanger 25.
The reactor 29 is internally provided with an SCR denitration catalyst reserved space 12, an SCR denitration catalyst I9 and an SCR denitration catalyst II 10
The heat exchanger 25 realizes heat exchange through a rotary heating surface.
The working principle of the invention is as follows: referring to FIG. 1, the arrows indicate the direction of flow of flue gas
Firstly, desulfurization:
under the action of an induced draft fan power system 15, the flue gas passes through the desulfurization tower 4, and the desulfurization solution in the desulfurization circulating pool 1 is sprayed into the desulfurization tower 4 through the desulfurization spraying system 2 to be fully mixed with the flue gas, so that the ultralow emission of desulfurization is completed. The ultra-low emission treatment of sulfur dioxide is realized; the desulfurized liquid flows back to the desulfurization circulating pool 1 through a desulfurization liquid reflux system 3;
II, initial condensation:
wet desulphurization and low-temperature flue gas are cooled and condensed by a first communicating flue 19 and an initial condensing system 5, and condensed water flows back into the desulphurization circulating tank 1 through a return water system 17 of the initial condensing system, so that the aims of primarily saving water and reducing the humidity of the flue gas are fulfilled;
thirdly, a denitration reducing agent injection system:
after the denitration system is started to reach the operating temperature, the reducing agent stored in the denitration reducing agent storage system 20 enters the denitration reducing agent injection grid 6 after passing through the denitration reducing agent injection system 21, and the reducing agent is sprayed into the reactor through atomization and evaporation;
fourthly, denitration:
the condensed wet desulfurization and low-temperature flue gas enters a low-temperature side inlet 13 of a heat exchanger through a first communicating flue 19, is heated in the heat exchanger 25, enters a temperature compensation heating system 8 through a low-temperature side outlet 23 of the heat exchanger, and if the temperature does not reach the required temperature, is continuously compensated and heated to the SCR denitration reaction temperature, the compensated and heated flue gas enters a flue gas flow field mixer 7 to complete forced uniform mixing of the flue gas, a reducing agent and the high-temperature flue gas, and enters an SCR denitration catalyst reserved space 12, an SCR denitration catalyst I9 and an SCR denitration catalyst II 10 after being rectified by a flue gas flow field rectifier 11 to complete denitration, so that ultralow emission control of nitrogen oxides is realized. The denitrated high-temperature flue gas enters a heat exchanger 25 through a heat exchanger high-temperature side inlet 24 for heat exchange and then enters a second communicating flue 26 through a heat exchanger high-temperature side outlet 22. The waste heat of the discharged flue gas is recycled, and the aim of energy-saving treatment is fulfilled;
fifthly, dust removal
The flue gas with the temperature and the humidity meeting the requirements of the dust removal inlet enters the bag-type dust remover 14 through the second communicating flue 26 to complete dust removal treatment, and ultralow emission treatment of particulate matters is realized. And the clean flue gas after dust removal enters a third communicating flue 27.
Six, secondary condensation and white removal treatment
The purified flue gas after desulfurization, denitration and dust removal enters a secondary condensation system (chimney) 16 through a communication flue four 28, and the condensed purified flue gas reaches the standard and is discharged. The condensed water flows back into the desulphurization circulating tank 1 through a secondary condensation system backwater system 18, so that the purpose of secondary water saving is realized.
Seven, synergistic whitening treatment
After the wet desulfurization flue gas passes through the primary condensing system 5, the heat exchanger 25, the temperature compensation heating system 8 and the secondary condensing system (chimney) 16, a large amount of water in the flue gas is analyzed after condensation for two times and temperature rise and reduction, meanwhile, the temperature of the discharged flue gas is far higher than that of the inlet flue gas, the humidity content of the flue gas meets the requirement of whitening treatment, and the phenomenon of whitening of the flue gas does not occur in the aspect of visual sense. Through the technical treatment of desulfurization, denitration and dust removal, the smoke whitening treatment is realized at the same time.
Claims (5)
1. A low-temperature denitration dedusting and whitening process device after wet desulphurization is characterized by comprising a desulphurization spraying system (2) connected with a desulphurization circulating tank (1), a desulphurization liquid reflux system (3), an initial condensation system return water system (17) and a secondary condensation system return water system (18); the outlet of the desulfurization spraying system (2) is connected with the left flue gas inlet of the desulfurization tower (4); a top flue gas outlet of the desulfurizing tower (4) is communicated with a low-temperature side inlet (13) of the heat exchanger sequentially through a first communicating flue (19), an initial condensing system (5) and a first pipeline; a low-temperature side outlet (23) of the heat exchanger is connected with a temperature compensation heating system (8), a denitration reducing agent ammonia spraying grid (6), a flue gas flow field mixer (7) and a flue gas flow field rectifier (11); the lower side of the flue gas flow field rectifier (11) is provided with a reserved space (12) of the SCR denitration catalyst; the lower part of the SCR denitration catalyst reserved space (12) is sequentially provided with a first SCR denitration catalyst (9) and a second SCR denitration catalyst (10); the denitration reducing agent storage system (20) sprays the reducing agent into the denitration reducing agent injection grid (6) through the denitration reducing agent injection system (21); the outlet end of the reactor (29) is communicated with the high-temperature side inlet (24) of the heat exchanger; a high-temperature side outlet (22) of the heat exchanger is communicated with a bag-type dust collector (14) through a second communicating flue (26); the outlet of the bag-type dust collector (14) is communicated with the secondary condensation system (16) through a third communicating flue (27), an induced draft fan power system (15) and a fourth communicating flue (28);
the pipeline of the desulfurization liquid reflux system (3) is connected with the bottom of the desulfurization tower (4); outlet pipelines of the primary condensation system water return system (17) and the secondary condensation system water return system (18) are respectively communicated with the desulfurization circulating tank (1).
2. The low-temperature denitration dedusting and whitening process device after wet desulphurization according to claim 1, wherein a denitration reducing agent injection grid (6) and a flue gas flow field mixer (7) are arranged in the second pipeline; the denitration reducing agent injection grid (6) is connected with a denitration reducing agent storage system (20) through a denitration reducing agent injection system (21).
3. The device for low-temperature denitration dedusting and whitening process after wet desulphurization as claimed in claim 1, wherein the system-added temperature compensation heating system (8) is connected with the low-temperature side outlet (23) of the heat exchanger.
4. The device for the low-temperature denitration, dedusting and whitening process after wet desulphurization according to claim 1, wherein a high-temperature side outlet (22) of the heat exchanger is connected with a bag-type dust remover (14) through a second communicating flue (26), a high-temperature side inlet (24) of the heat exchanger is connected with a reactor (29), a low-temperature side outlet (23) of the heat exchanger is connected with a temperature compensation heating system (8), and a low-temperature side inlet (13) of the heat exchanger is connected with an initial condensing system (5).
5. The device for low-temperature denitration, dedusting and whitening process after wet desulphurization as claimed in claim 1, wherein the reactor (29) is internally provided with an SCR denitration catalyst headspace (12), an SCR denitration catalyst I (9) and an SCR denitration catalyst II (10).
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| CN202010425784.8A CN111644029A (en) | 2020-05-19 | 2020-05-19 | Low-temperature denitration, dedusting and whitening process device after wet desulphurization |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112090182A (en) * | 2020-09-17 | 2020-12-18 | 曹真武 | Dry dedusting system for proportioning roller of sintering machine |
| CN114504932A (en) * | 2022-02-14 | 2022-05-17 | 山东国舜建设集团有限公司 | Device and method for flue gas combined treatment and wastewater zero discharge |
-
2020
- 2020-05-19 CN CN202010425784.8A patent/CN111644029A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112090182A (en) * | 2020-09-17 | 2020-12-18 | 曹真武 | Dry dedusting system for proportioning roller of sintering machine |
| CN114504932A (en) * | 2022-02-14 | 2022-05-17 | 山东国舜建设集团有限公司 | Device and method for flue gas combined treatment and wastewater zero discharge |
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