CN111947171A - Denitration method for circulating fluidized bed boiler - Google Patents
Denitration method for circulating fluidized bed boiler Download PDFInfo
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- CN111947171A CN111947171A CN201910409949.XA CN201910409949A CN111947171A CN 111947171 A CN111947171 A CN 111947171A CN 201910409949 A CN201910409949 A CN 201910409949A CN 111947171 A CN111947171 A CN 111947171A
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- denitration
- denitration catalyst
- fluidized bed
- catalyst
- circulating fluidized
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 239000003054 catalyst Substances 0.000 claims abstract description 121
- 239000002245 particle Substances 0.000 claims abstract description 41
- 238000002485 combustion reaction Methods 0.000 claims abstract description 24
- 239000000463 material Substances 0.000 claims abstract description 20
- 230000003197 catalytic effect Effects 0.000 claims abstract description 7
- 229910052684 Cerium Inorganic materials 0.000 claims description 23
- -1 phosphorus modified gamma-alumina Chemical class 0.000 claims description 22
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- 229910052698 phosphorus Inorganic materials 0.000 claims description 16
- 239000011574 phosphorus Substances 0.000 claims description 16
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 13
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 13
- 239000004927 clay Substances 0.000 claims description 11
- 239000011148 porous material Substances 0.000 claims description 10
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 9
- 229910017052 cobalt Inorganic materials 0.000 claims description 9
- 239000010941 cobalt Substances 0.000 claims description 9
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 9
- 229910052802 copper Inorganic materials 0.000 claims description 9
- 239000010949 copper Substances 0.000 claims description 9
- 229910052742 iron Inorganic materials 0.000 claims description 9
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 8
- 229910052748 manganese Inorganic materials 0.000 claims description 8
- 239000011572 manganese Substances 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- 239000000440 bentonite Substances 0.000 claims description 6
- 229910000278 bentonite Inorganic materials 0.000 claims description 6
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 6
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims description 6
- 239000005995 Aluminium silicate Substances 0.000 claims description 5
- 235000012211 aluminium silicate Nutrition 0.000 claims description 5
- 229960000892 attapulgite Drugs 0.000 claims description 5
- 229910052625 palygorskite Inorganic materials 0.000 claims description 5
- 229910000311 lanthanide oxide Inorganic materials 0.000 claims description 3
- 235000012216 bentonite Nutrition 0.000 claims 1
- 239000003546 flue gas Substances 0.000 abstract description 20
- 238000010531 catalytic reduction reaction Methods 0.000 abstract description 8
- 239000003638 chemical reducing agent Substances 0.000 abstract description 6
- 239000003245 coal Substances 0.000 abstract description 6
- 239000000779 smoke Substances 0.000 abstract description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 3
- 229910052799 carbon Inorganic materials 0.000 abstract description 3
- 230000007704 transition Effects 0.000 abstract description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 abstract description 2
- 239000007789 gas Substances 0.000 description 28
- 239000000243 solution Substances 0.000 description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 22
- 239000000203 mixture Substances 0.000 description 20
- 238000003756 stirring Methods 0.000 description 17
- 239000002002 slurry Substances 0.000 description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 14
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical class [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 13
- 239000012153 distilled water Substances 0.000 description 13
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 12
- 238000006243 chemical reaction Methods 0.000 description 11
- 238000005303 weighing Methods 0.000 description 10
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 9
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- 238000001694 spray drying Methods 0.000 description 9
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 8
- 150000003839 salts Chemical class 0.000 description 8
- 238000001035 drying Methods 0.000 description 7
- 238000005516 engineering process Methods 0.000 description 7
- 239000007921 spray Substances 0.000 description 7
- 229910021380 Manganese Chloride Inorganic materials 0.000 description 6
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 description 6
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 6
- 238000011156 evaluation Methods 0.000 description 6
- 239000000446 fuel Substances 0.000 description 6
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 6
- 229940099607 manganese chloride Drugs 0.000 description 6
- 235000002867 manganese chloride Nutrition 0.000 description 6
- 239000011565 manganese chloride Substances 0.000 description 6
- 238000002156 mixing Methods 0.000 description 6
- 230000003647 oxidation Effects 0.000 description 6
- 238000007254 oxidation reaction Methods 0.000 description 6
- 238000009718 spray deposition Methods 0.000 description 6
- 238000005299 abrasion Methods 0.000 description 5
- 229910021529 ammonia Inorganic materials 0.000 description 5
- 229910052779 Neodymium Inorganic materials 0.000 description 4
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 4
- 229910052777 Praseodymium Inorganic materials 0.000 description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 4
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 239000003344 environmental pollutant Substances 0.000 description 4
- 229910052746 lanthanum Inorganic materials 0.000 description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 4
- 239000004005 microsphere Substances 0.000 description 4
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 4
- 229910052757 nitrogen Inorganic materials 0.000 description 4
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 4
- 231100000719 pollutant Toxicity 0.000 description 4
- PUDIUYLPXJFUGB-UHFFFAOYSA-N praseodymium atom Chemical compound [Pr] PUDIUYLPXJFUGB-UHFFFAOYSA-N 0.000 description 4
- YWECOPREQNXXBZ-UHFFFAOYSA-N praseodymium(3+);trinitrate Chemical compound [Pr+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O YWECOPREQNXXBZ-UHFFFAOYSA-N 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- 238000006722 reduction reaction Methods 0.000 description 4
- 235000019738 Limestone Nutrition 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 229910052747 lanthanoid Inorganic materials 0.000 description 3
- 150000002602 lanthanoids Chemical class 0.000 description 3
- 239000006028 limestone Substances 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 239000002893 slag Substances 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- 230000008901 benefit Effects 0.000 description 2
- 230000005587 bubbling Effects 0.000 description 2
- UFMZWBIQTDUYBN-UHFFFAOYSA-N cobalt dinitrate Chemical compound [Co+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O UFMZWBIQTDUYBN-UHFFFAOYSA-N 0.000 description 2
- 229910001981 cobalt nitrate Inorganic materials 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 239000003085 diluting agent Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- RBTARNINKXHZNM-UHFFFAOYSA-K iron trichloride Chemical compound Cl[Fe](Cl)Cl RBTARNINKXHZNM-UHFFFAOYSA-K 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- CFYGEIAZMVFFDE-UHFFFAOYSA-N neodymium(3+);trinitrate Chemical compound [Nd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O CFYGEIAZMVFFDE-UHFFFAOYSA-N 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000005070 sampling Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 239000004408 titanium dioxide Substances 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- QCQCHGYLTSGIGX-GHXANHINSA-N 4-[[(3ar,5ar,5br,7ar,9s,11ar,11br,13as)-5a,5b,8,8,11a-pentamethyl-3a-[(5-methylpyridine-3-carbonyl)amino]-2-oxo-1-propan-2-yl-4,5,6,7,7a,9,10,11,11b,12,13,13a-dodecahydro-3h-cyclopenta[a]chrysen-9-yl]oxy]-2,2-dimethyl-4-oxobutanoic acid Chemical compound N([C@@]12CC[C@@]3(C)[C@]4(C)CC[C@H]5C(C)(C)[C@@H](OC(=O)CC(C)(C)C(O)=O)CC[C@]5(C)[C@H]4CC[C@@H]3C1=C(C(C2)=O)C(C)C)C(=O)C1=CN=CC(C)=C1 QCQCHGYLTSGIGX-GHXANHINSA-N 0.000 description 1
- 229910021578 Iron(III) chloride Inorganic materials 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- ODUCDPQEXGNKDN-UHFFFAOYSA-N Nitrogen oxide(NO) Natural products O=N ODUCDPQEXGNKDN-UHFFFAOYSA-N 0.000 description 1
- 239000006004 Quartz sand Substances 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 238000006757 chemical reactions by type Methods 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000005243 fluidization Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000011344 liquid material Substances 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical class [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 239000007800 oxidant agent Substances 0.000 description 1
- FGIUAXJPYTZDNR-UHFFFAOYSA-N potassium nitrate Chemical compound [K+].[O-][N+]([O-])=O FGIUAXJPYTZDNR-UHFFFAOYSA-N 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000005086 pumping Methods 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
- 239000003403 water pollutant Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C10/00—Fluidised bed combustion apparatus
- F23C10/18—Details; Accessories
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/14—Phosphorus; Compounds thereof
- B01J27/185—Phosphorus; Compounds thereof with iron group metals or platinum group metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/14—Phosphorus; Compounds thereof
- B01J27/185—Phosphorus; Compounds thereof with iron group metals or platinum group metals
- B01J27/1853—Phosphorus; Compounds thereof with iron group metals or platinum group metals with iron, cobalt or nickel
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
- B01J27/14—Phosphorus; Compounds thereof
- B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
- B01J27/187—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with manganese, technetium or rhenium
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J7/00—Arrangement of devices for supplying chemicals to fire
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23C—METHODS OR APPARATUS FOR COMBUSTION USING FLUID FUEL OR SOLID FUEL SUSPENDED IN A CARRIER GAS OR AIR
- F23C2206/00—Fluidised bed combustion
- F23C2206/10—Circulating fluidised bed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23J—REMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES
- F23J2215/00—Preventing emissions
- F23J2215/10—Nitrogen; Compounds thereof
Abstract
The specific embodiment of the invention provides a denitration method for a circulating fluidized bed boiler, which is characterized in that a denitration catalyst is added into bed materials of the circulating fluidized bed boiler, and catalytic denitration is carried out in the combustion process inside the circulating fluidized bed boiler, wherein the denitration catalyst mainly comprises particles with the particle size of below 400 mu m. By controlling the particle size of the denitration catalyst, the denitration catalyst can be uniformly distributed in a dense-phase section, a transition section and a dilute-phase section of a hearth, a separator and a material returning device to catalyze NO in smoke in the combustion process of the coal fired in the circulating fluidized bed boilerxWith carbon particles in the boiler system, CO and NH in the flue gas3Reacting with reducing substance in furnace such as HCN to increase NOxCatalytic reduction efficiency.
Description
Technical Field
The invention belongs to a denitration method, and particularly relates to a denitration method of a circulating fluidized bed boiler.
Background
Circulating Fluidized Bed (CFB) boilers are an advanced technology for clean coal combustion that began to emerge in the end of the 70's 20 th century. The circulating fluidized bed boiler mainly comprises a combustion chamber, a separator and a material returning device. The ash and desulfurized limestone produced by the combustion of the fuel accumulate in the system, forming a bubbling bed or turbulent bed in the lower part of the combustion chamber and a fast bed in the upper part. The large amount of hot material in the lower part provides enough heat source for the fuel to catch fire, so the requirement for the fuel is relatively loose.
The combustion temperature in the circulating fluidized bed can be controlled within the range of 850-950 ℃ for stable and efficient combustion, and the combustion temperature inhibits the thermal reaction type Nitrogen Oxide (NO)x) While using staged combustionAbout 30-40% of secondary air is fed into the hearth in a burning mode, a large amount of reducing materials exist in the hearth, and fuel type NO can be controlledxIs generated. In case of stable operation of the boiler, NO can be controlled generallyxThe discharge amount of (2) is 200mg/m3On the other hand, the production amount is only 1/3-1/4 of a pulverized coal furnace, and the emission standard of most countries and regions in the world can be met.
However, the 100mg/m required by the emission standard of atmospheric pollutants for thermal power plants (GB 13223-2011) issued and implemented in China3Even further stringent to 50mg/m3The ultra-low emission, circulating fluidized bed boiler flue gas emission faces a great challenge. Because the combustion temperature in the CFB boiler is close to the temperature range of selective non-catalytic reduction (SNCR) ammonia injection denitration, and a circulation loop in the CFB boiler is a relatively stable temperature zone, ammonia or other reducing agents are injected at a proper position, such as the upper part of a hearth or the vicinity of an inlet of a cyclone separator, selective non-catalytic reduction reaction can be carried out, and NO is converted into ammoniaxReduction to N2Thereby reducing NO in the smokexThe amount of discharge of (c). Generally, selective non-catalytic reduction (SNCR) technology is capable of removing about 50% of NO in flue gasxMost of the existing circulating fluidized bed boilers adopt a selective non-catalytic reduction (SNCR) technology in the boiler to discharge NO in the flue gasxReduced to 100mg/m3The following are provided to satisfy NO in general flue gasxAnd (5) discharging requirements.
However, with the stricter environmental regulations in our country, the "coal-electric energy saving and emission reduction upgrade and reform action plan (2014 + 2020)" proposed by the national development and modification commission (development and modification energy [ 2014 ] 2093) requires the implementation of ultra-clean emission and NO emission of coal-fired boilerxEmission concentration (converted to NO)2) Is 50mg/m3Therefore, only the selective non-catalytic reduction technology is used for reducing NO in the flue gasxThe method of (a) has been far from meeting the ultra-low emission requirements. In order to deal with ultra-low emission, the existing circulating fluidized bed boiler mainly adopts the steps of installing Selective Catalytic Reduction (SCR) and low-temperature ozone oxidation (LoTO) at the tail partx) Adding wet flue gas washing or circulating oxidation absorption. SCR technology through the use ofIn a suitable temperature range and NH3Under the condition of/NO (molar ratio), the denitration rate of 80-90 percent can be obtained. The low-temperature ozone oxidation is to oxidize NO with low valence and difficult water solubility into N with high valence and easy solubility by adding ozone into the flue gas2O5And the rear part of the tower washes N in the flue gas through a water washing tower2O5Removing; the cyclic oxidation absorption is to oxidize NO in the flue gas into high-valence NO by adding oxidant into the flue gasxThen the water is sprayed to be converted into salt by the solid absorbent reaction, thereby realizing the purpose of removing NO in the flue gas.
The SCR denitration technology needs a new device, and a large amount of capital construction cost is needed; liquid ammonia is needed, so that the risk of ammonia escape and secondary pollution is caused; the SCR catalyst can increase SO2Formation of SO3The conversion rate of (1) and the emission of blue smoke plume are increased, and SO is simultaneously generated3Reaction with escaped ammonia to form (NH)4)HSO4The air preheater and the SCR catalytic bed layer can be blocked, and the long-period safe operation of the denitration device is difficult to realize. The existing circulating fluidized bed boiler almost completely adopts the desulfurization in the limestone furnace, if low-temperature ozone oxidation denitration is needed, an alkali washing system is additionally arranged at the rear part, the denitration cost is high, the problem of pollutant transfer exists, gas pollutants are converted into water pollutants, and salt-containing wastewater needs to be treated. The circulating oxidation absorption also has the problems of relatively high operation cost and pollutant transfer.
CN109201067A discloses a method for catalytic denitration in the internal combustion process of CFB boiler, but the denitration catalyst used in the method is in the shape of spherule with the particle size of 1.0-10.0 mm, the spherule catalyst is added into a dense bed of a boiler combustion chamber, and CO or carbon and NO are catalyzed in the dense bedxBy reaction of (A) with NOxConversion to N2。
Disclosure of Invention
The invention aims to provide a high-efficiency denitration method for a circulating fluidized bed boiler, which comprises the following specific scheme:
a denitration method of a circulating fluidized bed boiler is characterized in that a denitration catalyst is added into bed materials of the circulating fluidized bed boiler, and catalytic denitration is carried out in the combustion process inside the circulating fluidized bed boiler, wherein the denitration catalyst mainly comprises particles with the particle size of below 400 mu m.
Optionally, the volume percentage of the particles with the particle size of less than 400 μm of the denitration catalyst is more than 90%.
Optionally, the volume percentage of the particles with the particle size of 160-320 μm of the denitration catalyst is more than 40%.
Optionally, the denitration catalyst accounts for 0.5-5.0 wt% of the hearth material in the furnace.
Optionally, the denitration catalyst accounts for 1.5-2.5 wt% of the bed material in the furnace.
Optionally, the denitration catalyst comprises the following components in percentage by weight: 8 to 30 weight percent of phosphorus modified gamma-alumina, 5 to 15 weight percent of cerium modified titanium dioxide, 3 to 15 weight percent of lanthanide oxide except cerium, 3 to 10 weight percent of one or more oxides selected from copper, iron, manganese or cobalt, 20 to 65 weight percent of clay component and 5 to 20 weight percent of aluminum sol or silica sol.
Optionally, the clay component is selected from one or more of attapulgite, china clay, bentonite and kaolin.
Optionally, the attrition index of the denitration catalyst is not more than 2.5%/h.
Optionally, the pore volume of the denitration catalyst is not less than 0.10 mL/g.
Optionally, the pore volume of the denitration catalyst is 0.15-0.25 mL/g.
Compared with the prior art, the technical scheme of the invention has the following advantages:
the catalyst is directly added into the boiler, the operation is simple, and a new facility is not needed; the reducing agent in the combustion environment is directly utilized to catalyze denitration without adding NH3Reducing agents such as urea and the like, so that the problem of ammonia escape is solved; by controlling the particle size of the denitration catalyst, the denitration catalyst can be uniformly distributed in a dense-phase section, a transition section and a dilute-phase section of a hearth, a separator and a material returning device to catalyze smoke in the combustion process of the coal fired in the circulating fluidized bed boilerNO in (1)xWith carbon particles in the boiler system, CO and NH in the flue gas3Reacting with reducing substance in furnace such as HCN to increase NOxCatalytic reduction efficiency of NO in flue gas in situ inside boiler combustion chamberxConversion to N2Realize the reduction of NO in the flue gasxThe purpose of (1).
Detailed Description
Because the hearth temperature of the circulating fluidized bed boiler is relatively low, NO in the flue gasxAlmost all comes from nitride in fuel, and combustion air is divided into primary air and secondary air, so that a stronger reducing atmosphere exists in the circulating fluidized bed boiler, and NO in discharged flue gasxThe content of NO is generated by combustion processxWith reduced NOxIs determined by how much. Raw NO produced by combustion of fuel without changing combustion conditionsxIn substantially constant amounts, already producing NO by fortificationxTo reduce the NO of the exhaust gas of the circulating fluidized bed boilerxThe key to the content. The inventor of the invention discovers through research that due to the adoption of the staged combustion technology, the dense-phase section of the hearth is in a strong reducing atmosphere, and the nitrides in the coal are mainly converted into NOxIntermediate NH of (2)3Or HCN, NO formedxNot so high that intermediate species are converted primarily to NO in the transition or dilute phase section following the secondary windxIf the added denitration catalyst particles are too large and only act on the dense phase section, the denitration rate of the catalyst is greatly reduced, and the possibility of removing a hearth along with slag exists, so that the loss rate of the catalyst is increased, so that in order to improve the utilization efficiency of the catalyst, the denitration catalyst is added into the bed material of the circulating fluidized bed boiler, and catalytic denitration is carried out in the combustion process in the circulating fluidized bed boiler, wherein the denitration catalyst mainly comprises particles with the particle size of below 400 microns, further, the volume percentage of the particles with the particle size of 160-320 microns controlled by the denitration catalyst is more than 40%, the volume percentage of the particles with the particle size of below 400 microns controlled by the denitration catalyst is more than 90%, preferably more than 95%The volume percentage of the particles with the particle size of below 80 mu m is below 20 percent, so that the particles with the particle size of below 80 mu m can not only play a role in a dense-phase section or be discharged along with slag, but also can be far larger than the average particle size (about 30 mu m) of circulating ash of the circulating fluidized bed boiler, so that the catalyst can be greatly remained in a system in the circulating fluidized bed boiler separator and can not be lost along with flue gas, and meanwhile, the particle size of most particles can be ensured to be close to the average particle size (about 200 mu m) of bed material particles of the circulating fluidized bed boiler, the fluidization state in the circulating fluidized bed boiler is not influenced, and the particles can be uniformly distributed in all the regions of a dense-phase region, a dilute-phase region, a separator, a return feeder and the like of the.
In the denitration method of the circulating fluidized bed boiler according to the embodiment of the present invention, the using efficiency and the denitration effect of the denitration catalyst are comprehensively considered, and the denitration catalyst may be selected to be 0.1 to 8.0 wt% of the bed material in the boiler, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or 7 wt%, preferably 0.5 to 5.0 wt%, and more preferably 1.5 to 2.5 wt%.
In the denitration method of the circulating fluidized bed boiler according to the embodiment of the present invention, the composition of the denitration catalyst is not particularly limited, and NO is preferably usedxWith carbonaceous particles, CO, NH3Or a substance having a high reduction catalytic action on a reducing substance such as HCN.
The denitration method of the circulating fluidized bed boiler according to the embodiment of the present invention provides the following high-efficiency denitration catalyst, for example, but is not limited to the following denitration catalyst. The denitration catalyst comprises the following components in percentage by weight: 8 to 30 weight percent of phosphorus modified gamma-alumina, 5 to 15 weight percent of cerium modified titanium dioxide, 3 to 15 weight percent of lanthanide oxide except cerium, 3 to 10 weight percent of one or more oxides selected from copper, iron, manganese or cobalt, 20 to 65 weight percent of clay component, 5 to 20 weight percent of aluminum sol or silica sol, and further, the weight of the phosphorus-modified gamma-alumina component is preferably 10 to 25 wt%, the weight of the cerium-modified titanium dioxide is preferably 7 to 13 wt%, the weight of the oxide of lanthanide except cerium is preferably 5 to 12 wt%, the weight of one or more oxides selected from copper, iron, manganese or cobalt is preferably 5 to 8 wt%, the weight of the clay component is preferably 25 to 60 wt%, the weight of the aluminum sol or silica sol is preferably 8 to 15 wt%, and the weight of each component of the denitration catalyst is calculated by the weight of the dry basis of each component. In the denitration catalyst, the strength of the catalyst is improved by adopting sol and clay components. In some embodiments, in the denitration catalyst, the phosphorus element in the phosphorus-modified gamma-alumina is present in an amount of 0.3 wt% to 1.5 wt% in the phosphorus-modified gamma-alumina, and the phosphorus-modified gamma-alumina can improve hydrothermal stability of the denitration catalyst; the cerium content of the cerium modified titanium dioxide is 5 wt% -15 wt% (in weight percentage of the titanium dioxide, calculated by the titanium dioxide), and the cerium modified titanium dioxide can improve the denitration performance of the integral catalyst and can also improve the wear-resistant strength of the catalyst. In some embodiments, in the denitration catalyst, the oxide selected from one or more oxides of copper, iron, manganese or cobalt may be a mixture obtained by mixing one or more oxides of copper, iron, manganese or cobalt, or may be an oxide obtained by mixing one or more salts of copper, iron, cobalt and manganese, and oxidizing the mixed salt, and the salt may be, for example, a hydrochloride salt or a nitrate salt thereof. The oxide of the lanthanide element other than cerium is one or more oxides of lanthanum, praseodymium or neodymium, and the oxide may be a mixture obtained by mixing one or more oxides of lanthanum, praseodymium or neodymium, or an oxide obtained by mixing one or more salts of lanthanum, praseodymium or neodymium and then oxidizing the mixed salt, and the salt may be hydrochloride or nitrate thereof. The combination of oxides of copper, iron, manganese or cobalt and oxides of lanthanum, praseodymium or neodymium can further improve the denitration performance of these single elements as active components. In some embodiments, in the denitration catalyst, the clay is one or more of attapulgite, clay, bentonite, and kaolin.
The denitration catalyst can be prepared by adopting the following steps: 1) placing phosphorus modified gamma-alumina, cerium modified titanium dioxide and clay into a container, mechanically and uniformly mixing, 2) weighing a salt compound of lanthanide except cerium, adding deionized water to completely dissolve the salt compound, 3) weighing one or more salt compounds selected from copper, iron, manganese or cobalt, adding deionized water to completely dissolve the salt compound, 4) sequentially adding the aqueous solution of 2) and 3) and aluminum sol or silica sol into 1) under stirring, adding a proper amount of deionized water, acidifying with dilute hydrochloric acid, fully stirring for 4-12 hours, forming slurry, homogenizing by a homogenizer, and standing for 16-24 hours to prepare the slurry; then, spray-drying the slurry by using spray-drying equipment, and controlling the temperature of a hearth of the spray-drying forming equipment to be 350-400 ℃, the outlet temperature to be 180-250 ℃ and the spray pressure to be 30-50 atmospheric pressures to obtain the catalyst microspheres; and baking the catalyst microspheres in an oven at 120-140 ℃ for 2-6 hours, baking in a muffle furnace at 800-1000 ℃ for 4-10 hours, and sieving to obtain the denitration catalyst.
According to the denitration method of the circulating fluidized bed boiler, the abrasion index of the denitration catalyst is not more than 2.5%/h, so that the abrasion of the catalyst to circulating bed materials and furnace walls can be greatly reduced, and the loss caused by the abrasion of the catalyst can also be reduced.
In the denitration method of the circulating fluidized bed boiler, the specific surface area of the denitration catalyst composition is not less than 40m2A/g, preferably of 50m2/g～100m2The denitration catalyst has a pore volume of not less than 0.10mL/g, preferably 0.15mL/g to 0.25 mL/g. The higher specific surface area and pore volume of the catalyst are the basis for ensuring the full contact and reaction of reactant molecules and the surface of the catalyst, and especially, the microspherical catalyst with small particle size not only has higher specific surface area and pore volume, but also is beneficial to overcoming the internal and external diffusion resistance and improving the reaction speed because of small particles.
The denitration catalyst can be added into the dense bed layer of the boiler through the existing coal feeding port and limestone feeding port, and the denitration catalyst is preferably added into the bed material of the boiler after being fully dispersed by the spiral feeder in the material returning device, so that the denitration catalyst is more favorably dispersed in the bed material.
Examples
Description of raw materials: the raw materials used in the implementation are all conventional products sold in the market.
Preparation of denitration catalyst
Example 1
378.9g of phosphorus-modified gamma-alumina with the phosphorus content of 0.8% (dry basis is 95 wt%), 168.4g of cerium-modified titanium dioxide with the cerium content of 10.0% (dry basis is 95 wt%) and 1175.5g of attapulgite (dry basis is 85 wt%) are weighed and placed in a container 1, and are stirred uniformly; 333.3g lanthanum nitrate (La) was weighed2O3Content 42 wt%) was put into a beaker 1 having a volume of 2000ml, and 500g of distilled water was added and stirred to be completely dissolved; 193.5g of copper nitrate (with a CuO content of 62 wt%) is weighed and placed in a beaker 2 with a volume of 2000ml, 300g of distilled water is added, and the mixture is stirred to be completely dissolved; 1100.0g of alumina sol (20 wt% on a dry basis) was weighed into a beaker 3; 160g of a 12% dilute hydrochloric acid solution is weighed and placed in a beaker 4; starting stirring, sequentially adding the lanthanum nitrate solution in the beaker 1, the copper nitrate solution in the beaker 2, the aluminum sol in the beaker 3 and the dilute hydrochloric acid solution in the beaker 4 into the container 1 in batches, fully stirring for 8 hours, homogenizing to form uniform slurry, and standing the slurry for 18 hours. And then spray drying and forming under the conditions that the hearth temperature is 380 ℃, the outlet temperature is 190 ℃ and the spray pressure is 38 atmospheric pressures, drying is carried out for 5 hours at 120 ℃, and the obtained sample is roasted and activated for 10 hours at 850 ℃ to obtain the denitration catalyst 1.
Example 2
589.5g of phosphorus modified gamma-alumina with the phosphorus content of 0.5 percent (dry basis is 95 weight percent), 231.6g of cerium modified titanium dioxide with the cerium content of 8.0 percent (dry basis is 95 weight percent) and 785.6g of pottery clay (dry basis is 87 weight percent) are weighed and put into a container 1 to be uniformly stirred; 238.1g of praseodymium nitrate (Pr) is weighed2O3Content 42 wt%) was put into a beaker 1 having a volume of 2000ml, and 500g of distilled water was added and stirred to be completely dissolved; 168.4g of ferric chloride (Fe) were weighed2O3Content 95 wt%) was put into a beaker 2 having a volume of 2000ml, 300g of distilled water was added thereto, and stirred to be completely dissolved(ii) a 1071.4g of silica sol (28 wt% on dry basis) was weighed into beaker 3; weighing 180g of 12% dilute hydrochloric acid solution and putting the solution into a beaker 4; starting stirring, sequentially adding praseodymium nitrate solution in a beaker 1, ferric trichloride solution in a beaker 2, silica sol in a beaker 3 and dilute hydrochloric acid solution in a beaker 4 into a container 1 in batches, fully stirring for 8 hours, homogenizing to form uniform slurry, and standing the slurry for 18 hours. And then spray drying and forming under the conditions that the hearth temperature is 390 ℃, the outlet temperature is 210 ℃ and the spray pressure is 40 atmospheric pressures, drying is carried out for 5 hours at 130 ℃, and the obtained sample is roasted and activated for 8 hours at 950 ℃ to obtain the denitration catalyst 2.
Example 3
252.6g of phosphorus modified gamma-alumina with the phosphorus content of 1.0 percent (dry basis is 95 weight percent), 273.7g of cerium modified titanium dioxide with the cerium content of 5.0 percent (dry basis is 95 weight percent) and 1195.4g of bentonite (dry basis is 87 weight percent) are weighed and put into a container 1 and stirred uniformly; 476.2g of neodymium nitrate (Nd) were weighed2O3Content 42 wt%) was put into a beaker 1 having a volume of 2000ml, and 500g of distilled water was added and stirred to be completely dissolved; 181.8g of anhydrous manganese chloride (MnO content 55 wt%) is weighed and placed into a beaker 2 with the volume of 2000ml, 300g of distilled water is added, and the mixture is stirred to be completely dissolved; weighing 571.4g of silica sol (28 wt% of dry silica) and putting the silica sol into a beaker 3; weighing 150g of 12% dilute hydrochloric acid solution and putting the solution into a beaker 4; starting stirring, adding the neodymium nitrate solution in the beaker 1, the manganese chloride solution in the beaker 2, the silica sol in the beaker 3 and the dilute hydrochloric acid solution in the beaker 4 into the container 1 in turn in batches, fully stirring for 7 hours, homogenizing to form uniform slurry, and standing the slurry for 20 hours. And then spray drying and forming under the conditions that the temperature of a hearth is 360 ℃, the outlet temperature is 200 ℃ and the spray pressure is 40 atmospheric pressures, drying is carried out for 5 hours at 140 ℃, and the obtained sample is roasted and activated for 7 hours at 950 ℃ to obtain the denitration catalyst 3.
Example 4
Weighing 168.4g of phosphorus modified gamma-alumina with the phosphorus content of 1.2% (dry basis is 95 wt%), 273.7g of cerium modified titanium dioxide with the cerium content of 12.0% (dry basis is 95 wt%) and 1129.4g of kaolin (dry basis is 85 wt%) into a container 1, and uniformly stirring; 571.4g of nitre are weighedLanthanum acid (La)2O3Content 42 wt%) was put into a beaker 1 having a volume of 2000ml, and 500g of distilled water was added and stirred to be completely dissolved; 560.0g of cobalt nitrate (CoO content 25 wt%) was weighed into a beaker 2 having a volume of 2000ml, and 300g of distilled water was added thereto and stirred to be completely dissolved; 1200.0g of alumina sol (20 wt% on a dry basis) is weighed and placed in a beaker 3; 160g of a 12% dilute hydrochloric acid solution is weighed and placed in a beaker 4; starting stirring, sequentially adding the lanthanum nitrate solution in the beaker 1, the cobalt nitrate solution in the beaker 2, the alumina sol in the beaker 3 and the dilute hydrochloric acid solution in the beaker 4 into the container 1 in batches, fully stirring for 7 hours, homogenizing to form uniform slurry, and standing the slurry for 24 hours. And then spray drying and forming under the conditions that the temperature of a hearth is 380 ℃, the outlet temperature is 230 ℃ and the spray pressure is 45 atmospheric pressures, drying is carried out for 6 hours at 120 ℃, and the obtained sample is roasted and activated for 8 hours at 1000 ℃ to obtain the denitration catalyst 4.
Example 5
421.1g of phosphorus-modified gamma-alumina with the phosphorus content of 1.4 percent (dry basis is 95 weight percent), 189.5g of cerium-modified titanium dioxide with the cerium content of 12.0 percent (dry basis is 95 weight percent) and 1103.4g of bentonite (dry basis is 87 weight percent) are weighed and put into a container 1 and stirred uniformly; 381.0g of lanthanum nitrate (La) was weighed out2O3Content 42 wt%) was put into a beaker 1 having a volume of 2000ml, and 500g of distilled water was added and stirred to be completely dissolved; 225.8g of copper nitrate (with the CuO content of 62 wt%) is weighed and placed into a beaker 2 with the volume of 2000ml, 300g of distilled water is added, and the mixture is stirred to be completely dissolved; 900.0g of alumina sol (20 wt% of dry alumina) is weighed and put into a beaker 3; 160g of a 12% dilute hydrochloric acid solution is weighed and placed in a beaker 4; starting stirring, sequentially adding the lanthanum nitrate solution in the beaker 1, the copper nitrate solution in the beaker 2, the aluminum sol in the beaker 3 and the dilute hydrochloric acid solution in the beaker 4 into the container 1 in batches, fully stirring for 7 hours, homogenizing to form uniform slurry, and standing the slurry for 24 hours. And then spray drying and forming under the conditions that the hearth temperature is 400 ℃, the outlet temperature is 240 ℃ and the spray pressure is 47 atmospheric pressures, drying is carried out for 6 hours at 130 ℃, and the obtained sample is roasted and activated for 9 hours at 980 ℃ to obtain the denitration catalyst 5.
Example 6
Weighing 189.5g of phosphorus modified gamma-alumina (dry basis is 95 wt%), 252.6g of cerium modified titanium dioxide (dry basis is 95 wt%) with 15.0% of phosphorus content and 1411.8g of attapulgite (dry basis is 85 wt%) which are put into a container 1 and stirred uniformly; 238.1g of praseodymium nitrate (Pr) is weighed2O3Content 42 wt%) was put into a beaker 1 having a volume of 2000ml, and 500g of distilled water was added and stirred to be completely dissolved; weighing 218.2g of anhydrous manganese chloride (MnO content 55 wt.%) and placing the anhydrous manganese chloride into a beaker 2 with the volume of 2000ml, adding 300g of distilled water, and stirring to completely dissolve the anhydrous manganese chloride; weighing 571.4g of silica sol (28 wt% of dry silica) and putting the silica sol into a beaker 3; 160g of a 12% dilute hydrochloric acid solution is weighed and placed in a beaker 4; and starting stirring, sequentially adding praseodymium nitrate solution in the beaker 1, manganese chloride solution in the beaker 2, silica sol in the beaker 3 and dilute hydrochloric acid solution in the beaker 4 into the container 1 in batches, fully stirring for 7 hours, homogenizing to form uniform slurry, and standing the slurry for 22 hours. Then spray drying and forming are carried out under the conditions that the hearth temperature is 400 ℃, the outlet temperature is 230 ℃ and the spray pressure is 45 atmospheric pressures, drying is carried out for 4 hours at 140 ℃, and the obtained sample is roasted and activated for 10 hours at 880 ℃ to obtain the denitration catalyst 6.
The physical properties of the denitration catalysts prepared in examples 1 to 6 were analyzed by a laser particle size analyzer for particle size distribution, a straight tube abrasion analyzer for abrasion index, and a specific surface area/pore volume analyzer for specific surface area and pore volume, and the specific analytical data are shown in table 1.
Table 1 examples 1-6 main physical properties of denitration catalyst
Examples 1-6 NO of denitration catalystsxThe conditions for evaluating the removal performance and the evaluation results were as follows:
evaluation of NO of the catalyst composition under set conditions on a bubbling fluidized bed quartz reactor unit by simulating CFB boiler combustion reaction conditionsxAnd (4) removing performance. The flue gas is composed of N2、CO、NO、O2、SO2Mixed gas prepared by water vapor according to a certain proportion. The composition of each standard gas was as follows: NO standard gas NO is 2500mg/m3、N2Is a balance gas; the standard CO gas was 8.0 (v)%, N2Is a balance gas; o is2Standard gas O2Is 12.0 (v)%, N2To balance the gas, SO2Is 3000mg/m3、N2In order to balance gas, the water vapor is generated by pumping deionized water into a preheating area of the quartz reactor through a micro metering pump. In the evaluation, the circulating ash of an industrial CFB boiler is used as a diluent, and the content of the denitration catalyst in the circulating ash is 1.5%. Weighing 50g of a mixture of circulating ash and a denitration catalyst, putting the mixture into a quartz tube reactor with the diameter of phi 30 multiplied by 2mm, heating the mixture to 880 ℃ under the nitrogen flow, stopping the nitrogen flow, introducing mixed gas, reacting at a certain gas flow rate, sampling and analyzing the mixture once every 10 minutes for 24 hours, and taking the average value of NO removal rate in 24 hours as the comparison of the performance of the denitration catalyst composition.
The denitration catalyst composition has NO removal performance:
in the formula: DeNO is the NO removal rate of the denitration catalyst,%; theta1In terms of NO content in the gas before reaction, mg/m3；θ2Is the content of NO in the gas mixture after reaction, mg/m3。
Table 2 shows the results of the denitration performance evaluation of the denitration catalyst of the present invention.
Table 2 denitration catalyst denitration performance evaluation results
| Denitration catalyst | Denitration rate% |
| Circulation ofAsh of | — |
| Denitration catalyst 1 | 93.8 |
| Denitration catalyst 2 | 91.6 |
| Denitration catalyst 3 | 90.7 |
| Denitration catalyst 4 | 89.3 |
| Denitration catalyst 5 | 94.3 |
| Denitration catalyst 6 | 96.1 |
Comparative example 1
4211g of phosphorus-modified gamma-alumina (95 wt% on a dry basis) having a phosphorus content of 1.3%, 1895g of cerium-modified titanium dioxide (95 wt% on a dry basis) having a cerium content of 12.0%, 11034g of bentonite (87 wt% on a dry basis), 3810g of lanthanum nitrate (La) were weighed2O342wt percent of copper nitrate, 2258g of copper nitrate (62 wt percent of CuO) are placed in the vessel 1 and stirred uniformly to obtain solid A; 9000g of the alumina sol (20% by weight on dry basis) were weighed into beaker 2 and 9000g of distilled water were added, which was called liquid material B after stirring. Preparing A, B materials into a small ball catalyst with the diameter of 1.5-2.5mm by a turntable ball rolling machine, cooling, drying and roasting to obtain the denitration catalyst 7.
The basic properties of the denitration catalyst 7 are shown in table 3.
Table 3 main physical properties of denitration catalyst 7
| Item | Catalyst 2 |
| Particle size distribution, mm | 1.5-2.0 |
| Bulk density, kg/m3 | 1100 |
| Crush strength, N/grain | 0.25％ |
| Specific surface area, m2/g | 38.6 |
| Pore volume, mL/g | 0.12 |
It can be seen from the data in Table 3 that the denitration catalyst 7 has a large particle size and can be present only in the dense phase section, and is difficult to circulate in the entire system. In addition, the denitration catalyst 7 has a large bulk density and is easily discharged with slag.
Denitration performance evaluation comparison of different concentrations of denitration catalysts of example 5 and comparative example 1
The denitration performance of the denitration catalyst 5 and the denitration catalyst 7 was evaluated under set conditions on a fixed bed quartz tube reactor. The flue gas is composed of N2、CO、NO、O2The standard gas is mixed gas prepared according to a certain proportion. The composition of each standard gas was as follows: NO standard gas NO is 1500mg/m3、N2Is a balance gas; the standard CO gas was 3.0 (v)%, N2Is flatGas is balanced; o is2Standard gas O2Is 8.0 (v)%, N2Is the balance gas. And uniformly mixing the quartz sand diluent and the denitration catalyst, and then filling the mixture into a reactor. Heating to 880 ℃ under nitrogen flow, stopping nitrogen, introducing mixed gas, reacting at a certain gas flow rate, sampling and analyzing once every 15 minutes, reacting for 8 hours, and taking the average value of 8-hour denitration rate as the comparison of the performance of the denitration catalyst composition. The denitration performance of the denitration catalyst is represented by the following formula:
in the formula: DenO is the denitration rate of the denitration catalyst; theta1Mg/m3 for the NO content in the gas before reaction; theta2Is the content of NO in the gas mixture after reaction, mg/m3. The denitration catalysts of example 5 and comparative example 1 were tested by the above-described method, and the denitration rate was calculated, and the results are shown in table 4.
TABLE 4 Denitrification Performance comparison of Denitrification catalysts 5, 7 at different concentrations
| Catalyst and process for preparing same | Denitration rate% |
| Circulating Ash (catalyst content, 0 wt%) | — |
| Circulating ash +4.0 wt% denitration catalyst 5 | 98.9 |
| Circulating ash +2.5 wt% denitration catalyst 5 | 97.7 |
| Circulating ash +1.5 wt% denitration catalyst 5 | 95.2 |
| Circulating ash +0.5 wt% denitration catalyst 5 | 75.1 |
| Circulating ash +4 wt% denitration catalyst 7 | 91.5 |
| Circulating ash +1.5 wt% denitration catalyst 7 | 78.0 |
As can be seen from the results in table 4, the microsphere denitration catalyst 5 prepared by the method of the present invention can achieve a very high denitration rate in the gas simulating the circulating fluidized bed boiler environment, and has a significant denitration advantage over the microsphere denitration catalyst 7.
Although the present invention is disclosed above, the present invention is not limited thereto. Various changes and modifications may be effected therein by one skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (10)
1. A denitration method of a circulating fluidized bed boiler is characterized in that a denitration catalyst is added into bed materials of the circulating fluidized bed boiler, and catalytic denitration is carried out in the combustion process inside the circulating fluidized bed boiler, wherein the denitration catalyst mainly comprises particles with the particle size of below 400 mu m.
2. The method according to claim 1, wherein the denitration catalyst has a particle size of 400 μm or less in a volume percentage of 90% or more.
3. The denitration method according to claim 1, wherein the denitration catalyst has a particle size of 160 to 320 μm in a volume percentage of 40% or more.
4. The denitration method according to claim 1, wherein the denitration catalyst is 0.5 to 5.0 wt% based on the weight of the hearth material in the furnace.
5. The denitration method according to claim 4, wherein the denitration catalyst is 1.5 to 2.5 wt% based on the weight of the hearth material in the furnace.
6. The denitration method according to claim 1, wherein the denitration catalyst comprises the following components in percentage by weight: 8 to 30 weight percent of phosphorus modified gamma-alumina, 5 to 15 weight percent of cerium modified titanium dioxide, 3 to 15 weight percent of lanthanide oxide except cerium, 3 to 10 weight percent of one or more oxides selected from copper, iron, manganese or cobalt, 20 to 65 weight percent of clay component and 5 to 20 weight percent of aluminum sol or silica sol.
7. The denitration method according to claim 6, wherein the clay component is selected from the group consisting of attapulgite, kaolin, bentonite, and kaolin.
8. The denitration method according to claim 1, wherein the denitration catalyst attrition index is not more than 2.5%/h.
9. The denitration method according to claim 1, wherein the denitration catalyst has a pore volume of not less than 0.10 mL/g.
10. The denitration catalyst of claim 9, wherein the denitration catalyst has a pore volume of 0.15 to 0.25 mL/g.
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| CN109253448A (en) * | 2017-07-12 | 2019-01-22 | 清华大学 | circulating fluidized bed combustion method |
| CN109201067A (en) * | 2018-11-23 | 2019-01-15 | 中石化炼化工程（集团）股份有限公司 | Denitrating catalyst and preparation method thereof and the method for reducing circulating fluidized bed boiler discharged nitrous oxides |
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