CN111888908A - Flue gas denitration device and method - Google Patents
Flue gas denitration device and method Download PDFInfo
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- CN111888908A CN111888908A CN202010871879.2A CN202010871879A CN111888908A CN 111888908 A CN111888908 A CN 111888908A CN 202010871879 A CN202010871879 A CN 202010871879A CN 111888908 A CN111888908 A CN 111888908A
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- 239000003546 flue gas Substances 0.000 title claims abstract description 77
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 76
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000003860 storage Methods 0.000 claims abstract description 84
- 239000002002 slurry Substances 0.000 claims abstract description 70
- 239000002253 acid Substances 0.000 claims abstract description 58
- 230000002378 acidificating effect Effects 0.000 claims abstract description 35
- 239000012670 alkaline solution Substances 0.000 claims abstract description 29
- 239000003929 acidic solution Substances 0.000 claims abstract description 22
- 239000007789 gas Substances 0.000 claims abstract description 13
- 239000000243 solution Substances 0.000 claims description 48
- 239000007788 liquid Substances 0.000 claims description 47
- OSVXSBDYLRYLIG-UHFFFAOYSA-N dioxidochlorine(.) Chemical compound O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 claims description 41
- 239000007921 spray Substances 0.000 claims description 27
- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 23
- 239000004155 Chlorine dioxide Substances 0.000 claims description 18
- 235000019398 chlorine dioxide Nutrition 0.000 claims description 18
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 12
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 12
- 230000007797 corrosion Effects 0.000 claims description 9
- 238000005260 corrosion Methods 0.000 claims description 9
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 4
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 4
- 229910000019 calcium carbonate Inorganic materials 0.000 claims description 4
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims description 4
- 239000000292 calcium oxide Substances 0.000 claims description 4
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 4
- 239000000463 material Substances 0.000 claims description 3
- 238000001514 detection method Methods 0.000 claims description 2
- 239000011521 glass Substances 0.000 claims description 2
- 230000001590 oxidative effect Effects 0.000 description 9
- JCXJVPUVTGWSNB-UHFFFAOYSA-N Nitrogen dioxide Chemical compound O=[N]=O JCXJVPUVTGWSNB-UHFFFAOYSA-N 0.000 description 8
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 8
- 238000010521 absorption reaction Methods 0.000 description 8
- 239000002585 base Substances 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 5
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 5
- 230000003647 oxidation Effects 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 4
- 239000007800 oxidant agent Substances 0.000 description 4
- 238000005507 spraying Methods 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- MGWGWNFMUOTEHG-UHFFFAOYSA-N 4-(3,5-dimethylphenyl)-1,3-thiazol-2-amine Chemical compound CC1=CC(C)=CC(C=2N=C(N)SC=2)=C1 MGWGWNFMUOTEHG-UHFFFAOYSA-N 0.000 description 3
- 229910002089 NOx Inorganic materials 0.000 description 3
- 239000003344 environmental pollutant Substances 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000006229 carbon black Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 238000004939 coking Methods 0.000 description 2
- 125000004122 cyclic group Chemical group 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- 238000005245 sintering Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 230000005619 thermoelectricity Effects 0.000 description 2
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000003034 coal gas Substances 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000003303 reheating Methods 0.000 description 1
- 239000000779 smoke Substances 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
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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
- B01D53/46—Removing components of defined structure
- B01D53/54—Nitrogen compounds
- B01D53/56—Nitrogen oxides
-
- 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
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
-
- 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
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
- B01D53/502—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific solution or suspension
-
- 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
- B01D53/46—Removing components of defined structure
- B01D53/48—Sulfur compounds
- B01D53/50—Sulfur oxides
- B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
- B01D53/504—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific device
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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
- B01D53/46—Removing components of defined structure
- B01D53/64—Heavy metals or compounds thereof, e.g. mercury
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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
- B01D53/46—Removing components of defined structure
- B01D53/68—Halogens or halogen compounds
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- 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
- B01D53/75—Multi-step processes
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- 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
- B01D53/77—Liquid phase processes
- B01D53/78—Liquid phase processes with gas-liquid contact
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- 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
- B01D53/80—Semi-solid phase processes, i.e. by using slurries
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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Abstract
The invention relates to a flue gas denitration device, which comprises: the denitration system comprises an acidic denitration tower (2), an alkaline denitration tower (11), an acidic solution storage tank (5), an alkaline slurry storage tank (14) and a tail flue (19), wherein acidic denitration slurry and alkaline denitration slurry are stored in the acidic solution storage tank (5) and the alkaline solution storage tank (14) respectively; the middle part of the acid denitration tower (2) is provided with a flue gas inlet (1) which is connected with a draught fan in front, the top of the acid denitration tower (2) is communicated with a flue gas inlet (8) of the alkaline denitration tower (11), and a purified gas outlet at the top of the alkaline denitration tower (11) is communicated with a tail flue (19). The invention also relates to a flue gas denitration method.
Description
Technical Field
The invention relates to a flue gas denitration device and a denitration method thereof, in particular to a flue gas denitration device combining chlorine dioxide and acid-base double-tower washing and a denitration method thereof.
Background
Nitrogen oxides, the most predominant atmospheric pollutants behind smoke and sulfur dioxide, are N2O、NO、NO2、NO3、N2O5Etc. are a generic term for a series of nitrogen oxides. NOxHas great harm to human body, animals and plants, can form acid rain and acid mist to destroy ecological environment, and can also combine with volatile organic compounds to form photochemical smog to destroy the ozone layer and cause global warming. Along with the gradual improvement of environmental awareness, the national environmental protection requirements are increasingly strict, the requirements of various industrial industries on ultralow emission are also increasingly strict, and along with the gradual implementation of the ultralow emission control of the flue gas of the large-scale power station boiler, NO is addedx、SO2The total amount of the discharged pollutants is obviously reduced. However, the combustion equipment such as vast middle and small-sized thermoelectricity, heat supply stations, industrial kilns, carbon black tail gas furnaces, coking furnaces, steel sintering machines and the like has certain difficulty in flue gas treatment due to large quantity, wide area, small capacity and complex furnace types, and the coal gas change is subsidized and popularized only in important cities such as Beijing, Tianjin, Shanghai and the like, and other areas face huge financial subsidy gaps, so that the flue gas treatment in a typical industrial process needs vigorous support of national policies and a targeted novel technology is developed. On one hand, an ultra-low emission technical route of 'SCR + low-temperature dust removal + FGD + WFGD' developed for a large power station boiler is too complex and expensive, and the investment is too large for small and medium-sized enterprises; on the other hand, due to the limitation of the production process and the low temperature of the flue gas at the outlet of the production line: (<200 ℃ and the like, and the traditional Selective Catalytic Reduction (SCR) and selective non-catalytic reduction (SNCR) technologies are difficult to implement.
Chlorine dioxide ClO2The oxidant is a high-efficiency green oxidant, is widely applied to water treatment, has strong oxidizing property and has the oxidation-reduction potential of 1.511V. At present, paper industry enterprises widely adopt chlorine dioxide as a bleaching agent, and have lower cost for preparing chlorine dioxideAnd (4) fertilizing capacity. Thus, use of ClO2The denitration process as an oxidant has a relatively low operating cost.
Ozone is also a common oxidant for oxidative denitration. The denitration principle is similar, and the strong oxidizing property of the denitration catalyst is utilized to oxidize NO into NO2And then absorbed with alkaline solution. The problem of ozone is that the instability of ozone makes it difficult to store in bottles, and generally, ozone generators can be used only on site and can be used at any time. Although the efficiency of the existing ozone generator is obviously improved compared with the prior art, about 90% of electric energy is not used for generating ozone but converted into heat, which causes the ozone generator to consume serious electricity and has relatively high operation cost.
In principle: NO of boiler flue gasxMore than 95% of NO is insoluble in water, so that the NO is difficult to be effectively absorbed in the process similar to a desulfurization washing tower device. And high valence state of NO2Etc. can react with water to produce HNO3Its dissolving power is greatly raised. Using chlorine dioxide ClO2The strong oxidizing property of (2) oxidizing NO and in a scrubber column2When the nitrogen oxides are absorbed by the alkaline slurry, the removal of the nitrogen oxides NO is realizedxThe purpose of (1). Removal of NO by oxidationxCan be divided into two processes, i.e. the oxidation of nitric oxide NO to nitrogen dioxide NO2Then NO of the next step2Is absorbed by the spray liquid.
In practical engineering applications, the PH of the absorption liquid is a key process operating parameter. ClO2The oxidation property of the solution is related to the acid-base property of the solution, the stronger the acidity of the solution is, the stronger the oxidation capacity of the solution is, and the over-acidity of the absorption solution can also cause HCl to escape. On the other hand, the more basic the solution, the greater its ability to absorb acid gases. It can be seen that the PH requirements of the solution are reversed in the two processes of oxidation and absorption.
For the condition that the environmental protection requirement has low requirement on the emission index of nitrogen oxides, only one absorption tower is used, the pH value is controlled to be in a range close to the neutral range, and the denitration rate can still be accepted even if the denitration rate is low. With the increasing environmental protection requirements in recent years, the requirements for denitration equipment are higher and higher, and the requirements must be the same as those for denitration equipmentThe strengthening of the two aforementioned processes of oxidation and absorption makes it possible to achieve the current or future NOxEmission limit standards.
Therefore, it is desirable to provide a low-cost and high-efficiency flue gas denitration technology combining chlorine dioxide and acid-base absorption, which is used for denitration of boiler flue gas in the paper industry.
Disclosure of Invention
In order to solve the above technical problems, the present invention provides a flue gas denitration device, including: the denitration system comprises an acidic denitration tower, an alkaline denitration tower, an acidic solution storage tank, an alkaline slurry storage tank and a tail flue, wherein acidic and alkaline denitration slurries are stored in the acidic solution storage tank and the alkaline solution storage tank respectively; in the inner cavity of the tower body of the acid denitration tower, the top part is provided with a spray header, the demister is arranged above the spray header, in the inner cavity of the tower body of the alkaline denitration tower, the top part is provided with the spray header, and the demister is arranged above the spray header; a circulating liquid outlet is formed in the bottom of the acidic denitration tower, the circulating liquid outlet of the acidic denitration tower is communicated with a liquid inlet of the acidic solution storage tank, and a liquid inlet of a spray header of the acidic denitration tower is communicated with a liquid outlet of the acidic solution storage tank through an acidic solution circulating pump; a circulating liquid outlet is formed in the bottom of the alkaline denitration tower, the circulating liquid outlet of the alkaline denitration tower is communicated with a liquid inlet of the alkaline solution storage tank, and a liquid inlet of a spray head of the alkaline denitration tower is communicated with a liquid outlet of the alkaline solution storage tank through an alkaline solution circulating pump; the middle part of the acid denitration tower is provided with a flue gas inlet which is connected with a draught fan in front, an outlet at the top of the acid denitration tower is communicated with a flue gas inlet of the alkaline denitration tower, and a purified gas outlet at the top of the alkaline denitration tower is communicated with a tail flue.
Thus, the acidic denitrified solution (ClO) is lifted by the acidic denitrified tower (pH 4-6)2Solution) to oxidize and absorb NO, and an alkaline denitration tower (with the PH value of 8-10) is utilized to promote the NO of the alkaline solution2Thereby maximizing the efficiency of flue gas denitration.
In addition, since denitration by acidity is easy, particularly ClO2The oxidized and absorbed flue gas is absorbed again by alkali liquor, thereby avoiding HCl from escaping and reducing secondary pollution. Through the double absorption of chlorine dioxide combined with alkaline absorption liquid, the comprehensive denitration efficiency of more than 90 percent can be achieved, the cost is low, reheating is not needed, a catalyst is not needed, the equipment is simple, and the operation is easy.
In a preferred embodiment of the flue gas denitration apparatus according to the present invention, PH detectors for detecting the PH of the denitration slurry are disposed in the acidic solution storage tank and the alkaline solution storage tank, respectively.
The acid solution storage tank and the alkaline solution storage tank are communicated with each other through a pH value adjusting circulating pump, and the pH value adjusting circulating pump is used for starting when the pH value of the denitration slurry in the acid solution storage tank is lower than a preset value, and introducing the denitration slurry in the alkaline slurry storage tank into the acid solution storage tank. Preferably, the predetermined value is 4.
Preferably, the denitration slurry stored in the acidic solution storage tank is a chlorine dioxide solution. It is further preferred that the chlorine dioxide solution has a mass concentration in the range of 0.2 to 2g/L and a pH in the range of 4 to 6.
Preferably, the alkaline denitration slurry stored in the alkaline solution storage tank is an aqueous solution of at least one of sodium hydroxide, potassium hydroxide, calcium oxide, calcium carbonate and ammonia water, and has a PH value in the range of 8 to 10.
Preferably, the tower body and parts of the acidic denitration tower are subjected to corrosion resistance treatment only by using corrosion-resistant materials or glass flakes, and the alkaline denitration tower is not subjected to corrosion resistance treatment. Due to the adoption of the acid-base double-tower design, only corrosion-resistant materials or corrosion-resistant treatment (chloride ions have strong corrosivity) are needed to be selected for the acid denitration tower, and special corrosion-resistant treatment on the alkaline denitration tower is not needed, so that the denitration cost is greatly reduced.
Preferably, a nitric oxide concentration detection sensor is arranged in the inlet pipeline of the acid denitration tower.
According to another aspect of the present invention, there is also provided a flue gas denitration method, which uses the flue gas denitration device, and is characterized by comprising the following steps:
the method comprises the following steps: enabling the flue gas to enter the acidic denitration tower through a flue gas inlet of the acidic denitration tower, starting an acidic solution circulating pump, enabling acidic denitration slurry in an acidic solution storage tank to be sprayed out from a spray header, and enabling the acidic denitration slurry to reenter the acidic solution storage tank through a circulating liquid outlet of the acidic denitration tower and a liquid inlet of the acidic solution storage tank after the acidic denitration slurry reaches the bottom of the acidic denitration tower;
step two: demisting the flue gas sprayed by the acidic denitration slurry by a demister of the acidic denitration tower, and continuously flowing into the alkaline denitration tower from an outlet at the top of the acidic denitration tower;
step three: when the flue gas enters the alkaline denitration tower, starting an alkaline solution circulating pump to enable alkaline denitration slurry in the alkaline slurry storage tank to be sprayed out from the spray header, and after reaching the bottom of the alkaline denitration tower, enabling the alkaline denitration slurry to enter the alkaline slurry storage tank again through a circulating liquid outlet of the alkaline denitration tower and a liquid inlet of the alkaline solution storage tank;
step four: and after the flue gas sprayed by the alkaline denitration slurry is demisted by a demister of the alkaline denitration tower, the flue gas enters the tail flue from the top outlet of the alkaline denitration tower and is discharged.
Preferably, the denitration slurry stored in the acidic solution storage tank is a chlorine dioxide solution.
Preferably, the mass concentration of the chlorine dioxide solution is in the range of 0.2 to 2g/L, and the pH value is in the range of 4 to 6.
Preferably, the alkaline denitration slurry stored in the alkaline solution storage tank is an aqueous solution of at least one of sodium hydroxide, potassium hydroxide, calcium oxide, calcium carbonate and ammonia water, and has a PH value in the range of 8 to 10.
Preferably, the flue gas denitration method further comprises the following step five: and detecting the pH value in the acid solution storage tank by using a pH value detector, and introducing the alkaline denitration slurry in the alkaline slurry storage tank into the acid solution storage tank by switching on a pH value adjusting circulating pump when the pH value of the denitration slurry in the acid solution storage tank is lower than a preset value. Preferably, the predetermined value is 4.
Preferably, the residence time of the flue gas in the acid denitration tower is in the range of 1.0 to 3.0 seconds.
Preferably, the liquid-gas ratio in the acid denitration tower is in the range of 8 to 12L/m 3.
Preferably, the residence time of the flue gas in the alkaline denitration tower is in the range of 1.0 to 3.0 seconds.
Preferably, the liquid-gas ratio in the alkaline denitration tower is in the range of 8 to 12L/m 3.
It should be noted that the above technical scheme is suitable for tail gas purification projects such as medium and small-sized thermoelectricity, heat supply stations, industrial kilns, carbon black tail gas furnaces, coking furnaces, steel sintering machines, paper making rows and special boilers and the like. And the technology can realize integrated removal of pollutants such as SO2/HCl/Hg and the like while removing NOx, thereby meeting the requirement of ultra-clean emission.
Drawings
Fig. 1 shows a schematic view of the overall structure of a flue gas denitration apparatus according to the present invention.
Detailed Description
The present invention will be further described with reference to fig. 1 showing a schematic view of the overall structure of a flue gas denitration apparatus according to the present invention.
The flue gas denitration device combining chlorine dioxide and acid-base double-tower washing shown in fig. 1 comprises an acidic denitration tower 2, an alkaline denitration tower 11, an acidic solution storage tank 5, an alkaline slurry storage tank 14, a pH value adjusting circulating pump 20, a tail flue 19 and corresponding connecting pipelines.
The acid denitration tower 2 comprises a tower body, a spray header 3 and a demister 7. In the tower body inner chamber of acid denitration tower 2, the top is provided with shower head 3, and defroster 7 arranges in the top of shower head 3, forms demisting zone and spraying zone respectively with shower head 3, and the bottom in spraying zone is equipped with circulation liquid outlet 4, and the middle part is equipped with the flue gas entry 1 that connects the induced draft fan in front. The circulating liquid outlet 4 is connected with a liquid inlet of an acid solution storage tank 5. The liquid inlet of the spray header 3 is connected with the liquid outlet of the acid solution storage tank 5 through an acid solution circulating pump 6. The upper part of the acid solution storage tank 5 is provided with a feeding port 8, and the bottom part is provided with a waste liquid collecting outlet 9. The top of the acid denitration tower 2 is communicated with a flue gas inlet 8 of an alkaline denitration tower 11.
The alkaline denitration tower 11 comprises a tower body, a spray header 12 and a demister 16. In the tower body inner chamber of the alkaline denitration tower 11, the bottom of the spray zone is provided with a circulating liquid outlet 13, the middle part is provided with a flue gas inlet 10 connected with the top of the acidic denitration tower 2 in front, the top is provided with a spray header 12, and a demister 16 is arranged above the spray header 12 and forms a demisting zone and a spray zone with the spray header 12 respectively. The circulation liquid outlet 13 is connected to a liquid inlet of an alkaline solution storage tank 14. The liquid inlet of the spray header 3 is connected with the liquid outlet of the alkaline solution storage tank 5 through an acidic solution circulating pump 6. The alkaline solution storage tank 14 is provided with a feed inlet 17 at the upper part and a waste liquid collection outlet 18 at the bottom. And a purified gas outlet at the top of the alkaline denitration tower 11 is communicated with a tail flue 19.
The denitration slurry stored in the acid solution storage tank 5 is chlorine dioxide, and the concentration of the denitration slurry is 0.2-2 g/L. The denitration slurry stored in the alkaline slurry storage tank 12 is an alkaline solution. The acid solution storage tank and the alkaline slurry storage tank are respectively provided with a pH value detector and are communicated with each other through a pH value adjusting circulating pump 20.
The flue gas denitration device combining chlorine dioxide and acid-base double-tower washing and the denitration method thereof are as follows:
the method comprises the following steps: the flue gas containing the nitrate is introduced into an acid denitration tower 2 through a flue gas inlet 1. The acid solution circulation pump 6 is started to make the denitration slurry in the acid solution storage tank 5 be sprayed out from the spray header 3. Nitric oxide in the flue gas reacts with chlorine dioxide in the sprayed denitration slurry to generate nitric acid, hydrochloric acid and nitrogen dioxide. And the sprayed denitration slurry reaches the bottom of the spraying area in the acid denitration tower 2 and then enters the acid solution storage tank 5 again from the circulating outlet of the acid denitration tower 2, so that the cyclic utilization is realized. Acid solution holding vessel 5 upper portion is equipped with feed inlet 8 and is used for adding the denitration thick liquid, and the bottom is equipped with waste liquid and collects export 9, need discharge a certain amount of denitration thick liquid when chloride ion concentration exceedes 10000 ppm.
Step two: demisting the flue gas sprayed by the acidic denitration slurry by a demister 7, and then entering an alkaline denitration tower 11 from an outlet at the top of the acidic denitration tower 2 for further denitration;
step three: flue gas is introduced into an alkaline denitration tower 11 through a flue gas inlet 10. The alkaline solution circulation pump 15 is started to eject the denitration slurry in the alkaline slurry storage tank 14 from the shower head 12. And the nitrogen dioxide in the flue gas is absorbed by the alkaline solution in the sprayed denitration slurry. And the sprayed denitration slurry reaches the bottom of the spraying area in the alkaline denitration tower 11 and then enters the alkaline slurry storage tank 14 again from the circulating outlet of the alkaline denitration tower 11, so that the cyclic utilization is realized. The upper part of the alkaline slurry storage tank 12 is provided with a feeding port 17 for adding the denitration slurry, and the bottom part is provided with a waste liquid collecting outlet 18 for discharging the denitration slurry;
step four: the flue gas sprayed by the alkaline denitration slurry is demisted by a demister 16, and then enters a tail flue 19 from a purified gas outlet at the top of the alkaline denitration tower 11 to be discharged.
Step five: the acid solution storage tank 5 and the alkaline slurry storage tank 14 are provided with a PH detector and connected by a PH adjusting circulation pump 20, and when the PH of the denitration slurry in the acid solution storage tank 5 is too low (less than 4), the PH adjusting circulation pump 20 is started to introduce the denitration slurry in the alkaline slurry storage tank 14 into the acid solution storage tank 5.
The foregoing describes preferred embodiments of the present invention, but the spirit and scope of the present invention is not limited to the specific disclosure herein. Those skilled in the art can freely combine and expand the above-described embodiments in accordance with the teachings of the present invention to make further embodiments and applications within the spirit and scope of the present invention. The spirit and scope of the present invention are not to be limited by the specific embodiments but by the appended claims.
Claims (19)
1. The utility model provides a flue gas denitration device which characterized in that, this flue gas denitration device includes: an acid denitration tower (2), an alkaline denitration tower (11), an acid solution storage tank (5), an alkaline slurry storage tank (14) and a tail flue (19),
wherein the acidic solution storage tank (5) and the alkaline solution storage tank (14) store acidic and alkaline denitration slurries, respectively;
a spray header (3) is arranged at the top of the inner cavity of the tower body of the acid denitration tower (2), a demister (7) is arranged above the spray header (3), a spray header (12) is arranged at the top of the inner cavity of the tower body of the alkaline denitration tower (11), and a demister (16) is arranged above the spray header (12);
a circulating liquid outlet (4) is formed in the bottom of the acid denitration tower (2), the circulating liquid outlet (4) of the acid denitration tower (2) is communicated with a liquid inlet of the acid solution storage tank (5), and a liquid inlet of a spray header (3) of the acid denitration tower (2) is communicated with a liquid outlet of the acid solution storage tank (5) through an acid solution circulating pump (6);
a circulating liquid outlet (13) is arranged at the bottom of the alkaline denitration tower (11), the circulating liquid outlet (13) of the alkaline denitration tower (11) is communicated with a liquid inlet of an alkaline solution storage tank (14), and a liquid inlet of a spray header (12) of the alkaline denitration tower (11) is communicated with a liquid outlet of the alkaline solution storage tank (14) through an alkaline solution circulating pump (15);
the middle part of the acid denitration tower (2) is provided with a flue gas inlet (1) which is connected with a draught fan in front, the outlet at the top of the acid denitration tower (2) is communicated with a flue gas inlet (8) of the alkaline denitration tower (11), and the purified gas outlet at the top of the alkaline denitration tower (11) is communicated with a tail flue (19).
2. The flue gas denitration apparatus according to claim 1, wherein the denitration slurry stored in the acid solution storage tank (5) is a chlorine dioxide solution.
3. The flue gas denitration apparatus according to claim 1, wherein a PH detector for detecting a PH of the denitration slurry is disposed in each of the acidic solution storage tank (5) and the alkaline solution storage tank (14).
4. The flue gas denitration apparatus according to any one of claims 1 to 3, wherein the acid solution storage tank (5) and the alkaline solution storage tank (14) are communicated with each other by a pH-value adjusting circulation pump (20) for introducing the denitration slurry in the alkaline slurry storage tank (14) into the acid solution storage tank (5) by being activated when the pH value of the denitration slurry in the acid solution storage tank (5) is lower than a predetermined value.
5. The flue gas denitration device according to claim 4, wherein the predetermined value is 4.
6. The flue gas denitration device according to claim 2, wherein the mass concentration of the chlorine dioxide solution is in the range of 0.2 to 2g/L, and the pH value is in the range of 4 to 6.
7. The flue gas denitration apparatus according to claim 1 or 2, wherein the alkaline denitration slurry stored in the alkaline solution storage tank (14) is an aqueous solution of at least one of sodium hydroxide, potassium hydroxide, calcium oxide, calcium carbonate, and ammonia water, and has a PH value in a range of 8 to 10.
8. The flue gas denitration apparatus according to claim 1, wherein only the tower body of the acidic denitration tower (2) and its parts are subjected to corrosion-resistant material or glass flake corrosion-resistant treatment, and the alkaline denitration tower (11) is not subjected to corrosion-resistant treatment.
9. The flue gas denitration device according to claim 1, wherein a nitric oxide concentration detection sensor is provided in an inlet pipe of the acid denitration tower (2).
10. A flue gas denitration method using the flue gas denitration apparatus according to any one of claims 1 to 9, characterized by comprising the steps of:
the method comprises the following steps: enabling flue gas to enter an acidic denitration tower (2) through a flue gas inlet (1) of the acidic denitration tower (2), starting an acidic solution circulating pump (6), enabling acidic denitration slurry in an acidic solution storage tank (5) to be sprayed out from a spray header (3), and enabling the acidic denitration slurry to reenter the acidic solution storage tank (5) through a circulating liquid outlet (4) of the acidic denitration tower (2) and a liquid inlet of the acidic solution storage tank (5) after reaching the bottom of the acidic denitration tower (2);
step two: demisting the flue gas sprayed by the acidic denitration slurry by a demister (7) of the acidic denitration tower (2), and continuously flowing into an alkaline denitration tower (11) from a top outlet of the acidic denitration tower (2);
step three: when the flue gas enters the alkaline denitration tower (11), starting an alkaline solution circulating pump (15) to enable alkaline denitration slurry in an alkaline slurry storage tank (14) to be sprayed out from a spray header (12), and after reaching the bottom of the alkaline denitration tower (11), enabling the alkaline denitration slurry to enter the alkaline slurry storage tank (14) again through a circulating liquid outlet (13) of the alkaline denitration tower (11) and a liquid inlet of the alkaline solution storage tank (14);
step four: and the flue gas sprayed by the alkaline denitration slurry is demisted by a demister (16) of the alkaline denitration tower (11), and then enters the tail flue from the top outlet of the alkaline denitration tower (11) to be discharged.
11. The flue gas denitration method according to claim 10, wherein the denitration slurry stored in the acid solution storage tank (5) is a chlorine dioxide solution.
12. The flue gas denitration method of claim 11, wherein the mass concentration of the chlorine dioxide solution is in the range of 0.2 to 2g/L, and the PH value is in the range of 4 to 6.
13. The flue gas denitration method according to claim 10, wherein the alkaline denitration slurry stored in the alkaline solution storage tank (14) is an aqueous solution of at least one of sodium hydroxide, potassium hydroxide, calcium oxide, calcium carbonate and ammonia water, and the PH value is in the range of 8 to 10.
14. The flue gas denitration method of claim 10, further comprising
Step five: and a PH value detector is used for detecting the PH value in the acid solution storage tank (5), and when the PH value of the denitration slurry in the acid solution storage tank (5) is lower than a preset value, a PH value adjusting circulating pump is switched on to introduce the alkaline denitration slurry in the alkaline slurry storage tank (14) into the acid solution storage tank (5).
15. The flue gas denitration method according to claim 14, wherein the predetermined value is 4.
16. The flue gas denitration method according to any one of claims 10 to 15, wherein a residence time of the flue gas in the acid denitration tower (2) is in a range of 1.0 to 3.0 seconds.
17. The flue gas denitration method according to any one of claims 10 to 15, wherein a liquid-gas ratio in the acid denitration tower (2) is 8 to 12L/m3Within the range of (1).
18. The flue gas denitration method according to any one of claims 10 to 15, wherein a residence time of the flue gas in the alkaline denitration tower (11) is in a range of 1.0 to 3.0 seconds.
19. The flue gas denitration method according to any one of claims 10 to 15, wherein a liquid-gas ratio in the alkaline denitration tower (11) is 8 to 12L/m3Within the range of (1).
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| US20190247789A1 (en) * | 2016-06-15 | 2019-08-15 | Yissum Research Development Company Of The Hebrew University Of Jerusalem Ltd. | Process for removing pollutants from a flue gas |
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