CN111992011A - Ozone oxidation synchronous desulfurization and denitrification method for sludge gasification melting tail gas - Google Patents
Ozone oxidation synchronous desulfurization and denitrification method for sludge gasification melting tail gas Download PDFInfo
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- CN111992011A CN111992011A CN202010686445.5A CN202010686445A CN111992011A CN 111992011 A CN111992011 A CN 111992011A CN 202010686445 A CN202010686445 A CN 202010686445A CN 111992011 A CN111992011 A CN 111992011A
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- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 title claims abstract description 106
- 238000002309 gasification Methods 0.000 title claims abstract description 67
- 239000010802 sludge Substances 0.000 title claims abstract description 65
- 238000002844 melting Methods 0.000 title claims abstract description 64
- 230000008018 melting Effects 0.000 title claims abstract description 64
- 238000007254 oxidation reaction Methods 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 55
- 230000003647 oxidation Effects 0.000 title claims abstract description 33
- 238000006477 desulfuration reaction Methods 0.000 title claims abstract description 24
- 230000023556 desulfurization Effects 0.000 title claims abstract description 24
- 230000001360 synchronised effect Effects 0.000 title claims abstract description 10
- 239000007789 gas Substances 0.000 claims abstract description 134
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000003546 flue gas Substances 0.000 claims abstract description 35
- 239000007788 liquid Substances 0.000 claims abstract description 20
- 238000005406 washing Methods 0.000 claims abstract description 17
- 238000005507 spraying Methods 0.000 claims abstract description 9
- 239000002253 acid Substances 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 5
- 239000000428 dust Substances 0.000 claims description 35
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims description 33
- 230000008569 process Effects 0.000 claims description 25
- 230000003009 desulfurizing effect Effects 0.000 claims description 8
- 230000009467 reduction Effects 0.000 claims description 8
- -1 polypropylene Polymers 0.000 claims description 7
- 239000007921 spray Substances 0.000 claims description 7
- 239000004743 Polypropylene Substances 0.000 claims description 6
- 229920001155 polypropylene Polymers 0.000 claims description 6
- 239000010865 sewage Substances 0.000 claims description 5
- 239000000779 smoke Substances 0.000 claims description 5
- 239000012209 synthetic fiber Substances 0.000 claims description 5
- 229920002994 synthetic fiber Polymers 0.000 claims description 5
- 238000005201 scrubbing Methods 0.000 claims description 4
- 239000011259 mixed solution Substances 0.000 claims description 3
- 230000035699 permeability Effects 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 3
- 239000002918 waste heat Substances 0.000 claims description 3
- 230000009471 action Effects 0.000 claims description 2
- 230000004927 fusion Effects 0.000 claims 4
- 239000003500 flue dust Substances 0.000 claims 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 20
- 230000000694 effects Effects 0.000 description 16
- 238000006243 chemical reaction Methods 0.000 description 10
- 238000002156 mixing Methods 0.000 description 10
- 238000010521 absorption reaction Methods 0.000 description 9
- 229910021529 ammonia Inorganic materials 0.000 description 9
- RAHZWNYVWXNFOC-UHFFFAOYSA-N Sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 8
- 230000001590 oxidative effect Effects 0.000 description 7
- 238000006722 reduction reaction Methods 0.000 description 7
- 239000003513 alkali Substances 0.000 description 6
- 238000000354 decomposition reaction Methods 0.000 description 6
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 6
- 239000007800 oxidant agent Substances 0.000 description 6
- 230000035484 reaction time Effects 0.000 description 6
- 238000010531 catalytic reduction reaction Methods 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 5
- 238000003860 storage Methods 0.000 description 4
- 238000012423 maintenance Methods 0.000 description 3
- 150000004767 nitrides Chemical class 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 239000003344 environmental pollutant Substances 0.000 description 2
- 239000000945 filler Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
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- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
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- 231100000252 nontoxic Toxicity 0.000 description 1
- 230000003000 nontoxic effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 1
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 1
- 239000002994 raw material Substances 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
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/76—Gas phase processes, e.g. by using aerosols
-
- 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
- B01D53/14—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 by absorption
- B01D53/1456—Removing acid components
- B01D53/1481—Removing sulfur dioxide or sulfur trioxide
-
- 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
- B01D53/14—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 by absorption
- B01D53/18—Absorbing units; Liquid distributors therefor
-
- 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
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F33/00—Other mixers; Mixing plants; Combinations of mixers
- B01F33/80—Mixing plants; Combinations of mixers
- B01F33/82—Combinations of dissimilar mixers
- B01F33/821—Combinations of dissimilar mixers with consecutive receptacles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/30—Sulfur compounds
- B01D2257/302—Sulfur oxides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/40—Nitrogen compounds
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
- B01F2101/00—Mixing characterised by the nature of the mixed materials or by the application field
- B01F2101/25—Mixing waste with other ingredients
Abstract
The invention provides a synchronous ozone oxidation desulfurization and denitrification method for sludge gasification melting tail gas, which comprises the following steps: cooling sludge gasification melting tail gas formed by gasifying and melting the sludge, and leading out the sludge gasification melting tail gas through a flue; an ozone generator is adopted to generate ozone, and the ozone is put into the flue through a first gas mixer arranged in the flue, so that the ozone and the sludge gasification melting tail gas are preliminarily mixed and reacted to obtain first pretreatment flue gas; the first pretreated flue gas is subjected to mixed oxidation reaction through a plurality of second gas mixers in sequence to obtain second pretreated flue gas; and sending the second pretreated flue gas into a gas washing tower, and absorbing acid gas in the second pretreated flue gas through spraying liquid in the gas washing tower so as to complete desulfurization and denitrification, wherein ozone is added in a graded adding manner through the first gas mixer and the second gas mixer.
Description
Technical Field
The invention belongs to the technical field of sludge treatment, and particularly relates to a synchronous desulfurization and denitrification method for ozone oxidation of sludge gasification melting tail gas.
Background
Compared with tail gas of a coal-fired boiler or other industrial kilns, the flue gas volume of in-situ gasification melting tail gas in a sludge plant is small, and the content of nitrogen oxides is not high. Meanwhile, the land for sewage treatment plants is in short supply. The conventional desulfurization and denitrification process has high investment and operation cost, large floor area and high operation and maintenance difficulty, and most of sludge gasification and melting projects are not suitable.
Currently, the mainstream denitration processes are two processes of SCR (selective catalytic reduction) and SNCR (selective non-catalytic reduction). Wherein, the selective catalytic reduction SCR method denitration adopts ammonia, CO or hydrocarbon and the like as reducing agents in the presence of a catalyst to reduce NO in the flue gas into N in the presence of oxygen2. The SCR reaction reductant may be NH3、CO、H2And methane, ethylene, propane, propylene, and the like. The removal efficiency of NO can be maximized when ammonia is used as the reducing agent. At the same time, however, the risk of deactivation of the SCR catalyst is high and there is an environmental safety risk of ammonia slip. SNCR is a selective non-catalytic reduction, and is a mature low-cost denitration technology. In the selective non-catalytic reduction denitration process, urea or amino compound is injected into flue gas at a higher reaction temperature (930-xReduction of (Nitrogen oxides) to N2. The reducing agent is typically injected into the furnace or flue immediately adjacent the furnace exit. NO of SNCR ProcessXThe removal efficiency of (A) is mainly determined by the reaction temperature, NH3With NOXThe stoichiometric ratio of (a), the degree of mixing, the reaction time, etc. Among them, the temperature control of the SNCR process is crucial. If the temperature is too low, NH3Is incomplete and easily causes NH3And (4) leakage. If the temperature is too high, NH3Is easily oxidized into NOXThereby counteracting NH3The removal effect of (1). Thus, if the temperature is not properly controlled, either too high or too low will result in reductant loss and NOXThe removal rate is reduced. In summary, the conventional denitration process is complex to control, high in raw material preparation and storage difficulty, high in investment and operation cost, large in occupied area and high in operation and maintenance difficulty. In addition, the sludge gasification melting project is usually located in a sewage plantInternally, this results in ground strain. The sludge gasification melting equipment is high in integration degree in order to save occupied area, and the conventional denitration process cannot meet the requirements of simple process, follow-up production, small occupied area, easiness in control and the like, and is not applicable.
In addition, the use of ozone in the desulfurization and denitrification process is an auxiliary means for other denitrification processes, and the aim of finally realizing denitrification needs to be fulfilled by adopting a conventional denitrification process. And the conventional ozone denitration adopts a one-time adding mode. However, since the decomposition rate of ozone is increased with the increase of temperature at a temperature of 150 ℃ or higher, and the oxidation rate and the oxidation efficiency of ozone are decreased at a temperature of 150 ℃ or lower, the oxidation efficiency of ozone cannot be precisely controlled, and the amount of ozone added is increased, which further increases the operation cost.
Disclosure of Invention
In view of the above technical problems, the present invention aims to provide a method for simultaneous desulfurization and denitrification by ozone oxidation of sludge gasification melting tail gas, which uses ozone to realize denitrification of sludge gasification melting tail gas, can accurately control the input amount of ozone as an oxidant, ensures sufficient oxidation of ozone, improves desulfurization and denitrification efficiency, and can avoid environmental safety risks caused by ammonia leakage. Meanwhile, the method can synchronously realize the removal of sulfur dioxide through ozone oxidation and alkali liquor absorption.
Therefore, the invention provides a method for synchronously desulfurizing and denitrifying sludge gasification melting tail gas through ozone oxidation, which comprises the following steps: cooling sludge gasification melting tail gas formed by gasifying and melting the sludge, and leading out the sludge gasification melting tail gas through a flue; an ozone generator is adopted to generate ozone, and the ozone is put into the flue through a first gas mixer arranged in the flue, so that the ozone and the sludge gasification melting tail gas are preliminarily mixed and reacted to obtain first pretreatment flue gas; the first pretreated flue gas is subjected to mixed oxidation reaction through a plurality of second gas mixers in sequence to obtain second pretreated flue gas; and sending the second pretreated flue gas into a gas washing tower, and absorbing acid gas in the second pretreated flue gas through spraying liquid in the gas washing tower so as to complete desulfurization and denitrification, wherein ozone is added in a graded adding manner through the first gas mixer and the second gas mixer.
In one embodiment, in the temperature reduction treatment process, the sludge gasification melting tail gas is subjected to heat exchange through an air preheater and a waste heat recoverer in the gasification melting furnace, so that the temperature is reduced from 1200-1300 ℃ to 150-200 ℃, and the concentration of nitrogen oxides in the sludge gasification melting tail gas after the temperature reduction treatment is 80-200mg/Nm3，SO2The concentration is 800-3The smoke concentration is 3000-5000mg/Nm3. In one embodiment, the ozone is based on nitrogen oxides and SO in the exhaust gas2The concentration of the ozone is added according to the amount which is 1.05 to 1.1 times of the theoretical required ozone.
In one embodiment, the number of the second gas mixers is 1-2, and the downstream ends of the first gas mixer and the second gas mixer are respectively and correspondingly provided with a cyclone plate.
In one embodiment, the first mixer and the second mixer are venturi mixers, and the ozone generated by the ozone generator can form turbulent flow under the action of the first mixer or the second mixer.
In one embodiment, the scrubber tower adopts a wet scrubber tower, and the concentration of nitrogen oxides in the tail gas subjected to scrubbing treatment by the scrubber tower is 10-30mg/Nm3，SO2The concentration is 80-250mg/Nm3。
In one embodiment, the spray liquid of the gas washing tower is Na2S2O3And Na2(OH)2Mixed solution of the Na2S2O3And Na2(OH)2The mass concentration of the spraying liquid is 2 percent, and the adding amount of the spraying liquid is 5L/Nm3。
In one embodiment, a first dust remover for removing dust from the sludge gasification melting tail gas is arranged in the flue, and the sludge gasification melting tail gas is subjected to dust removal by the first dust remover and then subjected to temperature reduction treatment.
At one isIn the embodiment, the first dust remover is a cyclone dust remover, and the concentration of the smoke dust in the outlet gas is 800-3. In one embodiment, a second dust remover is arranged at the downstream end of the gas washing tower and is used for removing dust of second pre-treated flue gas passing through the gas washing tower, the flue gas discharged from the gas washing tower is discharged after reaching the standard through the second dust remover, spray liquid discharged from the gas washing tower flows back to a sewage regulating tank, the second dust remover is a polypropylene synthetic fiber filter bag, and the air permeability of the polypropylene synthetic fiber filter bag is not less than 10m3/㎡·min。
Compared with the prior art, the method has the advantages that:
according to the method for synchronously desulfurizing and denitrating the sludge gasification melting tail gas through ozone oxidation, ozone is used as an oxidant, and low-valence nitrides are oxidized through the ozone to obtain high-valence nitric oxides, so that the method for desulfurizing and denitrating the sludge gasification melting tail gas has no ammonia storage, and the safety and ecological risks caused by ammonia leakage are avoided. Ozone adopts a multi-stage feeding mode and is subjected to graded mixed oxidation reaction, so that the reaction time of each stage is shortened, the ozone oxidation effect is ensured while the ozone decomposition rate is reduced, and the control difficulty of the whole process is reduced. And moreover, the multistage gas mixer and the corresponding rotational flow plate are adopted, so that the mixed oxidation reaction effect of the sludge gasification melting tail gas and the ozone is effectively enhanced, and the mixed oxidation reaction efficiency is greatly improved. In addition, the desulfurization and denitrification method has the advantages of simple process flow, small occupied space of the whole equipment, convenient operation and control, low cost, high ozone utilization rate, no pollutant emission in tail gas treatment and great contribution to environmental protection.
Drawings
The invention will now be described with reference to the accompanying drawings.
FIG. 1 shows a schematic flow chart of the method for ozone oxidation synchronous desulfurization and denitrification of sludge gasification melting tail gas according to the invention.
Detailed Description
The invention is described below with reference to the accompanying drawings.
FIG. 1 shows a schematic flow chart of the method for ozone oxidation synchronous desulfurization and denitrification of sludge gasification melting tail gas according to the invention. As shown in fig. 1, first, sludge is fed into a gasification and melting furnace to be gasified and melted, thereby obtaining sludge gasification and melting off-gas. The temperature in the gasification melting furnace is within the range of 1200-1300 ℃, and the generated high-temperature sludge gasification melting tail gas is firstly subjected to cooling treatment. In the process of temperature reduction treatment, the high-temperature sludge gasification melting tail gas is subjected to heat exchange through an air preheater and a waste heat recoverer in the gasification melting furnace, so that the temperature of the high-temperature sludge gasification melting tail gas is reduced from the initial temperature of 1200-1300 ℃ to the temperature of 150-200 ℃. And then, the sludge gasification melting tail gas subjected to temperature reduction treatment is led out through a flue.
According to the invention, a first dust separator is arranged in the flue. And dedusting the sludge gasification melting tail gas subjected to temperature reduction treatment by a first dust remover. The sludge gasification melting tail gas can be dedusted by a first deduster of 1-2 stages. Preferably, the sludge gasification melting tail gas is subjected to stage 1 dust removal. The first dust separator may be a cyclone. The dust removal efficiency of the first dust remover is more than 80 percent, and the concentration of the smoke dust discharged from the first dust remover is 800-3. After the sludge gasification melting tail gas is dedusted by the first deduster, the influence of smoke dust on equipment of a subsequent process section can be reduced, and thus the treatment efficiency is ensured.
And then, preparing ozone by using an ozone generator, wherein the prepared ozone is used as an oxidant to be fed into a flue so as to be mixed with the sludge gasification melting tail gas and carry out oxidation reaction. Ozone is used as an oxidant, is prepared and used at any time through an ozone generator, does not need to be stored, and is non-toxic and harmless. The pollution accidents caused by leakage in the process links such as preparation and storage of liquid ammonia, urea and the like in the conventional denitration process are effectively avoided.
According to the invention, a first gas mixer is arranged in the flue. The ozone generator is communicated with the first gas mixer, and ozone prepared by the ozone generator is fed into the flue through the first gas mixer, so that the ozone and the sludge gasification melting tail gas are subjected to preliminary mixing reaction to obtain first pretreatment flue gas.
Ozone is easily decomposed at high temperature, which affects the utilization efficiency of ozone, but the oxidation reaction speed of ozone is high at high temperature, and the oxidation effect is good. According to the invention, aiming at the characteristic of ozone, the ozone is added in a graded adding manner, so that multi-stage mixed oxidation reaction is carried out, the reaction time of each stage can be shortened, the ozone decomposition rate is reduced, and the oxidation effect of the ozone is ensured. Specifically, a plurality of second gas mixers are arranged at the downstream end of the first gas mixer. And the first pretreated flue gas is subjected to further mixing oxidation reaction through a plurality of second gas mixers in sequence, so that second pretreated flue gas is obtained. The number of the second gas mixers is 1-2, preferably the number of the second gas mixers is 1. Therefore, the first pre-treated flue gas after the primary mixing reaction of the first mixer further passes through the second gas mixer for mixing reaction. Therefore, the multistage mixed oxidation reaction of the ozone obviously shortens the reaction time of each stage, reduces the ozone decomposition rate, ensures the oxidation effect of the ozone, and reduces the control difficulty of the whole process.
In one embodiment, the first gas mixer is a venturi mixer. Ozone is put in through first gas mixer and can be realized throwing to throw and go on with mixing in step to form the turbulent flow under the effect of putting into mouthful cross-section change of venturi mixer, thereby showing the mixed effect that improves ozone, improved mixed oxidation reaction's speed greatly, can further strengthen the oxidation effect of ozone. Therefore, the primary mixing reaction of the ozone and the sludge gasification melting tail gas is realized through the first gas mixer while the ozone is input.
According to the invention, the downstream ends of the first gas mixer and the second gas mixer are respectively and correspondingly provided with the rotational flow plates. In preliminary mixed reaction process, the whirl board of first gas mixer's low reaches end can make mud gasification melting tail gas and ozone intensive mixing to the mixed oxidation reaction effect of reinforcing improves mixed oxidation reaction efficiency. The ozone oxidizes low-valence nitrides in the sludge gasification melting tail gas, so that high-valence nitrogen oxides are generated by oxidation, and a first-stage mixed oxidation reaction is completed.
The sludge gasification melting tail gas passes through the second gas mixer and the cyclone plate correspondingly arranged at the downstream end of the second gas mixer after the primary mixed oxidation reaction, so that the nitrogen oxide which is not completely subjected to the primary mixed oxidation reaction is further reacted. In one embodiment, the second gas mixer may also be a venturi mixer. The ozone generator is respectively communicated with the second gas mixer, so that ozone can be supplemented in time in the process of further mixing and oxidizing reaction of the first pretreated flue gas to ensure the sufficiency of the oxidant. And after the first pretreated flue gas is subjected to multistage mixed oxidation reaction through a plurality of second gas mixers and corresponding cyclone plates, second pretreated flue gas is obtained. In the multistage mixed reaction process, the whirl board of the low reaches end of second gas mixer can make first preliminary treatment flue gas and ozone intensive mixing to the mixed oxidation reaction effect of reinforcing improves mixed oxidation reaction efficiency. Therefore, the ozone is put in a multi-stage mode and is subjected to graded mixed oxidation reaction, so that the reaction time of each stage is shortened, the ozone oxidation effect is ensured while the ozone decomposition rate is reduced, and the control difficulty of the whole process is reduced.
According to the invention, the ozone is dependent on NO in the exhaust gasx(Nitrogen oxide) and SO2Is added according to the concentration of the ozone, and the adding is carried out according to the 1.05-1.1 times of the theoretical required ozone amount. Preferably, ozone is added in a two-stage adding mode, and the adding proportion of the first stage to the second stage is 6: 4. and then sending the second pretreated flue gas into a scrubbing tower. Meanwhile, alkali liquor is prepared through an alkali liquor medicine dissolving machine, and the alkali liquor is used as absorption liquid and added into the gas washing tower in a spraying mode, so that spraying liquid is formed. In one embodiment, the spray is Na2S2O3And Na2(OH)2Mixed solution of Na2S2O3And Na2(OH)2The mass concentration of (A) is 2%. The addition amount of the spray liquid is 5L/Nm3And absorbing the acidic gas in the second pretreated flue gas obtained after the multistage mixed oxidation reaction in the gas washing tower through the spraying liquid, thereby completing desulfurization and denitrification. NO in tail gas after gas washing treatment of gas washing towerxThe concentration is 10-30mg/Nm3，SO2The concentration is 80-250mg/Nm3. The desulfurization and denitrification method provided by the invention adopts ozone to realize sludge gasification melting tail gas denitrification, and can ensure thatThe full oxidation of ozone is proved, the desulfurization and denitrification efficiency is improved, and the environmental safety risk caused by ammonia leakage can be avoided. Meanwhile, the method can synchronously realize the removal of sulfur dioxide through ozone oxidation and alkali liquor absorption.
In one embodiment, the scrubber tower may be a wet scrubber tower. The packing of the wet scrubber tower adopts a polypropylene Haier ring with the specification of phi 50, and the specific surface area of the packing is 107m2/m3Porosity of 94% and stacking number of 8200/m3Compared with other fillers, the adsorption effect of the filler of the scrubber can be improved by 20-40%. The wet scrubber tower can effectively improve the absorption efficiency of the acid gas in the second pretreated flue gas, and the wet scrubber tower is low in cost. Therefore, the absorption efficiency of the acid gas can be improved, the desulfurization and denitrification effects are enhanced, and the cost can be further saved.
In addition, the absorption liquid can be recycled in the process of absorbing the acid gas in the second pretreated flue gas. The absorption liquid becomes waste absorption liquid after absorbing the acid gas, and the waste absorption liquid flows back and is discharged into a regulating tank of a sewage plant, so that secondary pollution of the waste alkali liquid to the environment is avoided.
According to the invention, a second dust separator is provided at the downstream end of the scrubber tower. The second dust remover is used for removing dust from the second pretreated flue gas which is absorbed by the gas washing tower, so that the treated sludge gasification fused tail gas reaches the emission standard, and the environmental pollution is avoided. In one embodiment, the second dust collector is a polypropylene synthetic fiber filter bag, and the air permeability of the polypropylene synthetic fiber filter bag is not less than 10m3Square meter per minute. The bag type dust collector occupies a small space, is low in maintenance cost and can further save the cost.
According to the method for synchronously desulfurizing and denitrating the sludge gasification melting tail gas through ozone oxidation, ozone is used as an oxidant, and low-valence nitrides are oxidized through the ozone to obtain high-valence nitric oxides, so that the method for desulfurizing and denitrating the sludge gasification melting tail gas has no ammonia storage, and the safety and ecological risks caused by ammonia leakage are avoided. Ozone adopts a multi-stage feeding mode and is subjected to graded mixed oxidation reaction, so that the reaction time of each stage is shortened, the ozone oxidation effect is ensured while the ozone decomposition rate is reduced, and the control difficulty of the whole process is reduced. And moreover, the multistage gas mixer and the corresponding rotational flow plate are adopted, so that the mixed oxidation reaction effect of the sludge gasification melting tail gas and the ozone is effectively enhanced, and the mixed oxidation reaction efficiency is greatly improved. In addition, the desulfurization and denitrification method has the advantages of simple process flow, small occupied space of the whole equipment, convenient operation and control, low cost, high ozone utilization rate, no pollutant emission in tail gas treatment and great contribution to environmental protection.
Finally, it should be noted that the above-mentioned embodiments are only preferred embodiments of the present invention, and do not limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that modifications may be made to the embodiments described in the foregoing examples, or that equivalents may be substituted for elements thereof. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A method for synchronously desulfurizing and denitrifying sludge gasification melting tail gas through ozone oxidation is characterized by comprising the following steps:
cooling the sludge gasification melting tail gas formed by sludge gasification melting, and leading out the sludge gasification melting tail gas through a flue;
an ozone generator is adopted to generate ozone, and the ozone is put into the flue through a first gas mixer arranged in the flue, so that the ozone and the sludge gasification melting tail gas are preliminarily mixed and reacted to obtain first pretreatment flue gas;
sequentially passing the first pretreated flue gas through a plurality of second gas mixers to carry out mixed oxidation reaction to obtain second pretreated flue gas;
feeding the second pretreated flue gas into a gas washing tower, absorbing the acid gas in the reacted second pretreated flue gas through a spray liquid in the gas washing tower so as to complete desulfurization and denitrification,
wherein the ozone is added in a graded adding mode through the first gas mixer and the second gas mixer.
2. The method for synchronously desulfurizing and denitrating sludge gasification and melting tail gas through ozone oxidation as claimed in claim 1, wherein in the temperature reduction treatment process, the sludge gasification and melting tail gas is subjected to heat exchange through an air preheater and a waste heat recoverer in the gasification and melting furnace, so that the temperature is reduced from 1200-1300 ℃ to 150-200 ℃,
the concentration of nitrogen oxides in the sludge gasification melting tail gas after temperature reduction treatment is 80-200mg/Nm3，SO2The concentration is 800-3The smoke concentration is 3000-5000mg/Nm3。
3. The method for simultaneous ozone oxidation, desulfurization and denitrification of the sludge gasification and fusion tail gas as claimed in claim 1, wherein ozone is selected according to nitrogen oxides and SO in the tail gas2The concentration of the ozone is added according to the amount which is 1.05 to 1.1 times of the theoretical required ozone.
4. The method as claimed in claim 1 or 3, wherein the number of the second gas mixers is 1-2, and the downstream ends of the first gas mixer and the second gas mixer are respectively and correspondingly provided with a rotational flow plate.
5. The method for the ozone oxidation, synchronous desulfurization and denitrification of the sludge gasification and melting tail gas as claimed in claim 1 or 3, wherein the first mixer and the second mixer are venturi mixers, and ozone generated by the ozone generator can form turbulent flow under the action of the first mixer or the second mixer.
6. The method for synchronous ozone oxidation, desulfurization and denitrification of the sludge gasification and fusion tail gas as claimed in claim 1, wherein the scrubber tower is a wet scrubber tower, and the wet scrubber tower is used for scrubbing the sludge gasification and fusion tail gasThe concentration of nitrogen oxides in the tail gas after the gas washing treatment of the gas tower is 10-30mg/Nm3，SO2The concentration is 80-250mg/Nm3。
7. The method for synchronous ozone oxidation, desulfurization and denitrification of the sludge gasification and fusion tail gas as claimed in claim 1 or 6, wherein the spray liquid of the scrubbing tower is Na2S2O3And Na2(OH)2Mixed solution of the Na2S2O3And Na2(OH)2The mass concentration of the spraying liquid is 2 percent, and the adding amount of the spraying liquid is 5L/Nm3。
8. The method for synchronously desulfurizing and denitrifying sludge gasification and melting tail gas through ozone oxidation according to claim 1, wherein a first dust remover is arranged in the flue, and the sludge gasification and melting tail gas is subjected to dust removal by the first dust remover and then is subjected to cooling treatment.
9. The method as claimed in claim 8, wherein the first dust collector is a cyclone dust collector, and the concentration of the flue dust in the exhaust gas is 800-1000 mg/Nm-3。
10. The method for synchronous desulfurization and denitrification through ozone oxidation of sludge gasification melting tail gas as claimed in claim 1 or 6, wherein a second dust remover is arranged at the downstream end of the scrubber for removing dust from the second pre-treated flue gas passing through the scrubber, the flue gas discharged from the scrubber is discharged through the second dust remover after reaching the standard, the spray liquid discharged from the scrubber is returned to the sewage regulating tank,
the second dust collector is a polypropylene synthetic fiber filter bag, and the air permeability of the second dust collector is not less than 10m3/㎡·min。
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