NZ716901A - Method and apparatus for removing mercury from a flue gas stream - Google Patents
Method and apparatus for removing mercury from a flue gas streamInfo
- Publication number
- NZ716901A NZ716901A NZ716901A NZ71690116A NZ716901A NZ 716901 A NZ716901 A NZ 716901A NZ 716901 A NZ716901 A NZ 716901A NZ 71690116 A NZ71690116 A NZ 71690116A NZ 716901 A NZ716901 A NZ 716901A
- Authority
- NZ
- New Zealand
- Prior art keywords
- compounds
- mercury
- ntaining
- flue gas
- stream
- Prior art date
Links
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 title claims abstract description 256
- 229910052753 mercury Inorganic materials 0.000 title claims abstract description 195
- 239000003546 flue gas Substances 0.000 title claims abstract description 170
- UGFAIRIUMAVXCW-UHFFFAOYSA-N carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 title claims abstract description 164
- 239000000567 combustion gas Substances 0.000 claims abstract description 109
- 230000001590 oxidative Effects 0.000 claims abstract description 10
- 150000001875 compounds Chemical class 0.000 claims description 152
- -1 mercury halide compounds Chemical class 0.000 claims description 72
- 239000000203 mixture Substances 0.000 claims description 45
- 239000000446 fuel Substances 0.000 claims description 34
- 239000007789 gas Substances 0.000 claims description 25
- 238000002347 injection Methods 0.000 claims description 25
- 239000007924 injection Substances 0.000 claims description 25
- WKBOTKDWSSQWDR-UHFFFAOYSA-N bromine atom Chemical class [Br] WKBOTKDWSSQWDR-UHFFFAOYSA-N 0.000 claims description 22
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 22
- 239000003245 coal Substances 0.000 claims description 22
- 239000011780 sodium chloride Substances 0.000 claims description 18
- 239000002803 fossil fuel Substances 0.000 claims description 17
- GDTBXPJZTBHREO-UHFFFAOYSA-N bromine Substances BrBr GDTBXPJZTBHREO-UHFFFAOYSA-N 0.000 claims description 16
- 229910052736 halogen Inorganic materials 0.000 claims description 16
- 150000002367 halogens Chemical class 0.000 claims description 16
- 239000002028 Biomass Substances 0.000 claims description 14
- 238000005260 corrosion Methods 0.000 claims description 14
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 claims description 14
- 241000196324 Embryophyta Species 0.000 claims description 12
- 229910052740 iodine Inorganic materials 0.000 claims description 11
- 239000011630 iodine Substances 0.000 claims description 11
- 239000000460 chlorine Substances 0.000 claims description 10
- 239000002655 kraft paper Substances 0.000 claims description 10
- 238000003908 quality control method Methods 0.000 claims description 10
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- SATVIFGJTRRDQU-UHFFFAOYSA-N Potassium hypochlorite Chemical compound [K+].Cl[O-] SATVIFGJTRRDQU-UHFFFAOYSA-N 0.000 claims description 7
- 239000004744 fabric Substances 0.000 claims description 7
- JHJLBTNAGRQEKS-UHFFFAOYSA-M Sodium bromide Chemical compound [Na+].[Br-] JHJLBTNAGRQEKS-UHFFFAOYSA-M 0.000 claims description 6
- 150000001805 chlorine compounds Chemical class 0.000 claims description 6
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 6
- FAPWRFPIFSIZLT-UHFFFAOYSA-M sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 6
- FVAUCKIRQBBSSJ-UHFFFAOYSA-M sodium iodide Inorganic materials [Na+].[I-] FVAUCKIRQBBSSJ-UHFFFAOYSA-M 0.000 claims description 6
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate dianion Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 5
- 229940068479 POTASSIUM SULFIDE Drugs 0.000 claims description 5
- DPLVEEXVKBWGHE-UHFFFAOYSA-N Potassium sulfide Chemical compound [S-2].[K+].[K+] DPLVEEXVKBWGHE-UHFFFAOYSA-N 0.000 claims description 5
- HYHCSLBZRBJJCH-UHFFFAOYSA-M Sodium hydrosulfide Chemical compound [Na+].[SH-] HYHCSLBZRBJJCH-UHFFFAOYSA-M 0.000 claims description 5
- GRVFOGOEDUUMBP-UHFFFAOYSA-N Sodium sulfide Chemical compound [Na+].[Na+].[S-2] GRVFOGOEDUUMBP-UHFFFAOYSA-N 0.000 claims description 5
- YUKQRDCYNOVPGJ-UHFFFAOYSA-N Thioacetamide Chemical compound CC(N)=S YUKQRDCYNOVPGJ-UHFFFAOYSA-N 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 5
- 239000003518 caustics Substances 0.000 claims description 5
- 229910052801 chlorine Inorganic materials 0.000 claims description 5
- 230000000875 corresponding Effects 0.000 claims description 5
- 229910052979 sodium sulfide Inorganic materials 0.000 claims description 5
- UNHKSXOTUHOTAB-UHFFFAOYSA-N sodium;sulfane Chemical compound [Na].S UNHKSXOTUHOTAB-UHFFFAOYSA-N 0.000 claims description 5
- 239000002351 wastewater Substances 0.000 claims description 5
- SISAYUDTHCIGLM-UHFFFAOYSA-N Bromine dioxide Chemical compound O=Br=O SISAYUDTHCIGLM-UHFFFAOYSA-N 0.000 claims description 4
- QWPPOHNGKGFGJK-UHFFFAOYSA-N Hypochlorous acid Chemical compound ClO QWPPOHNGKGFGJK-UHFFFAOYSA-N 0.000 claims description 4
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L MgCl2 Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 claims description 4
- 241000872931 Myoporum sandwicense Species 0.000 claims description 4
- 235000009518 sodium iodide Nutrition 0.000 claims description 4
- 229910014265 BrCl Inorganic materials 0.000 claims description 3
- CODNYICXDISAEA-UHFFFAOYSA-N Bromine monochloride Chemical compound BrCl CODNYICXDISAEA-UHFFFAOYSA-N 0.000 claims description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N HCl Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 3
- 125000004429 atoms Chemical group 0.000 claims description 3
- 229910052794 bromium Inorganic materials 0.000 claims description 3
- ZAMOUSCENKQFHK-UHFFFAOYSA-N chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 claims description 3
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 239000001257 hydrogen Substances 0.000 claims description 3
- 229910000042 hydrogen bromide Inorganic materials 0.000 claims description 3
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 3
- 150000002497 iodine compounds Chemical class 0.000 claims description 3
- 239000001301 oxygen Substances 0.000 claims description 3
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims description 3
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Inorganic materials [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 claims description 3
- WGEFECGEFUFIQW-UHFFFAOYSA-L Calcium bromide Chemical compound [Ca+2].[Br-].[Br-] WGEFECGEFUFIQW-UHFFFAOYSA-L 0.000 claims description 2
- UNMYWSMUMWPJLR-UHFFFAOYSA-L Calcium iodide Chemical compound [Ca+2].[I-].[I-] UNMYWSMUMWPJLR-UHFFFAOYSA-L 0.000 claims description 2
- CUILPNURFADTPE-UHFFFAOYSA-N Hypobromous acid Chemical compound BrO CUILPNURFADTPE-UHFFFAOYSA-N 0.000 claims description 2
- VLTRZXGMWDSKGL-UHFFFAOYSA-M Perchlorate Chemical compound [O-]Cl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-M 0.000 claims description 2
- UXVMQQNJUSDDNG-UHFFFAOYSA-L cacl2 Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 2
- 229910001622 calcium bromide Inorganic materials 0.000 claims description 2
- 229910001640 calcium iodide Inorganic materials 0.000 claims description 2
- 229910001914 chlorine tetroxide Inorganic materials 0.000 claims description 2
- 229910000117 dibromine monoxide Inorganic materials 0.000 claims description 2
- 229910000454 diiodine tetroxide Inorganic materials 0.000 claims description 2
- 238000011143 downstream manufacturing Methods 0.000 claims description 2
- WXDJHDMIIZKXSK-UHFFFAOYSA-N iodine dioxide Inorganic materials O=I=O WXDJHDMIIZKXSK-UHFFFAOYSA-N 0.000 claims description 2
- BIZCJSDBWZTASZ-UHFFFAOYSA-N iodine pentoxide Inorganic materials O=I(=O)OI(=O)=O BIZCJSDBWZTASZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910001896 tribromine octoxide Inorganic materials 0.000 claims description 2
- NHYCGSASNAIGLD-UHFFFAOYSA-N chlorine monoxide Chemical compound Cl[O] NHYCGSASNAIGLD-UHFFFAOYSA-N 0.000 claims 10
- 239000007769 metal material Substances 0.000 claims 4
- JLKDVMWYMMLWTI-UHFFFAOYSA-M Potassium iodate Chemical compound [K+].[O-]I(=O)=O JLKDVMWYMMLWTI-UHFFFAOYSA-M 0.000 claims 3
- 229910001901 bromine monoxide radical Inorganic materials 0.000 claims 3
- 125000000684 bromosyl group Chemical group O=Br[*] 0.000 claims 3
- ICIWUVCWSCSTAQ-UHFFFAOYSA-N Iodic acid Chemical compound OI(=O)=O ICIWUVCWSCSTAQ-UHFFFAOYSA-N 0.000 claims 2
- YZHUMGUJCQRKBT-UHFFFAOYSA-M Sodium chlorate Chemical compound [Na+].[O-]Cl(=O)=O YZHUMGUJCQRKBT-UHFFFAOYSA-M 0.000 claims 2
- UKLNMMHNWFDKNT-UHFFFAOYSA-M Sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 claims 2
- BAZAXWOYCMUHIX-UHFFFAOYSA-M Sodium perchlorate Chemical compound [Na+].[O-]Cl(=O)(=O)=O BAZAXWOYCMUHIX-UHFFFAOYSA-M 0.000 claims 2
- 125000004435 hydrogen atoms Chemical class [H]* 0.000 claims 2
- 150000002894 organic compounds Chemical class 0.000 claims 2
- 229910001488 sodium perchlorate Inorganic materials 0.000 claims 2
- XTEGARKTQYYJKE-UHFFFAOYSA-N 7790-93-4 Chemical compound OCl(=O)=O XTEGARKTQYYJKE-UHFFFAOYSA-N 0.000 claims 1
- SXDBWCPKPHAZSM-UHFFFAOYSA-N Bromate Chemical compound OBr(=O)=O SXDBWCPKPHAZSM-UHFFFAOYSA-N 0.000 claims 1
- OTCKOJUMXQWKQG-UHFFFAOYSA-L Magnesium bromide Chemical compound [Mg+2].[Br-].[Br-] OTCKOJUMXQWKQG-UHFFFAOYSA-L 0.000 claims 1
- BLQJIBCZHWBKSL-UHFFFAOYSA-L Magnesium iodide Chemical compound [Mg+2].[I-].[I-] BLQJIBCZHWBKSL-UHFFFAOYSA-L 0.000 claims 1
- VLTRZXGMWDSKGL-UHFFFAOYSA-N Perchloric acid Chemical compound OCl(=O)(=O)=O VLTRZXGMWDSKGL-UHFFFAOYSA-N 0.000 claims 1
- OCATYIAKPYKMPG-UHFFFAOYSA-M Potassium bromate Chemical compound [K+].[O-]Br(=O)=O OCATYIAKPYKMPG-UHFFFAOYSA-M 0.000 claims 1
- FJVZDOGVDJCCCR-UHFFFAOYSA-M Potassium periodate Chemical compound [K+].[O-]I(=O)(=O)=O FJVZDOGVDJCCCR-UHFFFAOYSA-M 0.000 claims 1
- XUXNAKZDHHEHPC-UHFFFAOYSA-M Sodium bromate Chemical compound [Na+].[O-]Br(=O)=O XUXNAKZDHHEHPC-UHFFFAOYSA-M 0.000 claims 1
- JQWHASGSAFIOCM-UHFFFAOYSA-M Sodium periodate Chemical compound [Na+].[O-]I(=O)(=O)=O JQWHASGSAFIOCM-UHFFFAOYSA-M 0.000 claims 1
- 239000001110 calcium chloride Substances 0.000 claims 1
- 235000011148 calcium chloride Nutrition 0.000 claims 1
- 229910001628 calcium chloride Inorganic materials 0.000 claims 1
- XLYOFNOQVPJJNP-ZSJDYOACSA-N heavy water Substances [2H]O[2H] XLYOFNOQVPJJNP-ZSJDYOACSA-N 0.000 claims 1
- 229910001623 magnesium bromide Inorganic materials 0.000 claims 1
- 229910001629 magnesium chloride Inorganic materials 0.000 claims 1
- 229910001641 magnesium iodide Inorganic materials 0.000 claims 1
- 235000019396 potassium bromate Nutrition 0.000 claims 1
- 229910001487 potassium perchlorate Inorganic materials 0.000 claims 1
- 239000011697 sodium iodate Substances 0.000 claims 1
- 235000015281 sodium iodate Nutrition 0.000 claims 1
- 238000002485 combustion reaction Methods 0.000 abstract description 14
- 230000003647 oxidation Effects 0.000 description 32
- 238000007254 oxidation reaction Methods 0.000 description 32
- 150000004763 sulfides Chemical class 0.000 description 14
- 241000283986 Lepus Species 0.000 description 12
- 239000003513 alkali Substances 0.000 description 12
- 239000000523 sample Substances 0.000 description 12
- 229910052956 cinnabar Inorganic materials 0.000 description 11
- 239000006096 absorbing agent Substances 0.000 description 10
- 238000006477 desulfuration reaction Methods 0.000 description 10
- 230000003009 desulfurizing Effects 0.000 description 10
- 238000005201 scrubbing Methods 0.000 description 10
- 239000007921 spray Substances 0.000 description 10
- 239000000243 solution Substances 0.000 description 8
- 241000894007 species Species 0.000 description 8
- 238000000034 method Methods 0.000 description 7
- 239000002002 slurry Substances 0.000 description 7
- 239000000126 substance Substances 0.000 description 7
- QXKXDIKCIPXUPL-UHFFFAOYSA-N sulfanylidenemercury Chemical compound [Hg]=S QXKXDIKCIPXUPL-UHFFFAOYSA-N 0.000 description 7
- RAHZWNYVWXNFOC-UHFFFAOYSA-N sulphur dioxide Chemical compound O=S=O RAHZWNYVWXNFOC-UHFFFAOYSA-N 0.000 description 7
- 230000001603 reducing Effects 0.000 description 6
- UCKMPCXJQFINFW-UHFFFAOYSA-N sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 6
- 239000000654 additive Substances 0.000 description 5
- 239000003153 chemical reaction reagent Substances 0.000 description 5
- 238000009434 installation Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 230000001376 precipitating Effects 0.000 description 4
- 238000001556 precipitation Methods 0.000 description 4
- 239000002594 sorbent Substances 0.000 description 4
- SUKJFIGYRHOWBL-UHFFFAOYSA-N Sodium hypochlorite Chemical compound [Na+].Cl[O-] SUKJFIGYRHOWBL-UHFFFAOYSA-N 0.000 description 3
- 230000033228 biological regulation Effects 0.000 description 3
- 239000003795 chemical substances by application Substances 0.000 description 3
- 239000000295 fuel oil Substances 0.000 description 3
- 150000004820 halides Chemical class 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 239000007791 liquid phase Substances 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- SCDFUIZLRPEIIH-UHFFFAOYSA-N Dichlorine heptoxide Chemical compound O=Cl(=O)(=O)OCl(=O)(=O)=O SCDFUIZLRPEIIH-UHFFFAOYSA-N 0.000 description 2
- RCJVRSBWZCNNQT-UHFFFAOYSA-N Dichlorine monoxide Chemical compound ClOCl RCJVRSBWZCNNQT-UHFFFAOYSA-N 0.000 description 2
- 206010022000 Influenza Diseases 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 239000000809 air pollutant Substances 0.000 description 2
- 239000000356 contaminant Substances 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 239000000428 dust Substances 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 239000010881 fly ash Substances 0.000 description 2
- 230000001965 increased Effects 0.000 description 2
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006011 modification reaction Methods 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000002910 solid waste Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- YALMXYPQBUJUME-UHFFFAOYSA-L Calcium chlorate Chemical compound [Ca+2].[O-]Cl(=O)=O.[O-]Cl(=O)=O YALMXYPQBUJUME-UHFFFAOYSA-L 0.000 description 1
- PAWIVBWALDNUJP-UHFFFAOYSA-N Iodine trichloride Chemical compound ClI(Cl)Cl PAWIVBWALDNUJP-UHFFFAOYSA-N 0.000 description 1
- LWJROJCJINYWOX-UHFFFAOYSA-L Mercury(II) chloride Chemical compound Cl[Hg]Cl LWJROJCJINYWOX-UHFFFAOYSA-L 0.000 description 1
- YFDLHELOZYVNJE-UHFFFAOYSA-L Mercury(II) iodide Chemical compound I[Hg]I YFDLHELOZYVNJE-UHFFFAOYSA-L 0.000 description 1
- 235000013290 Sagittaria latifolia Nutrition 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 230000000996 additive Effects 0.000 description 1
- 238000003915 air pollution Methods 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 230000002238 attenuated Effects 0.000 description 1
- 235000019397 calcium bromate Nutrition 0.000 description 1
- 235000019390 calcium iodate Nutrition 0.000 description 1
- 230000003197 catalytic Effects 0.000 description 1
- OSVXSBDYLRYLIG-UHFFFAOYSA-N chlorine dioxide Inorganic materials O=Cl=O OSVXSBDYLRYLIG-UHFFFAOYSA-N 0.000 description 1
- 235000019398 chlorine dioxide Nutrition 0.000 description 1
- RCTYPNKXASFOBE-UHFFFAOYSA-M chloromercury Chemical compound [Hg]Cl RCTYPNKXASFOBE-UHFFFAOYSA-M 0.000 description 1
- 230000001721 combination Effects 0.000 description 1
- 235000015246 common arrowhead Nutrition 0.000 description 1
- 230000002939 deleterious Effects 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N dihydrogen sulfide Chemical compound S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000002708 enhancing Effects 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229910000037 hydrogen sulfide Inorganic materials 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-M hydrosulfide Chemical compound [SH-] RWSOTUBLDIXVET-UHFFFAOYSA-M 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- NGYIMTKLQULBOO-UHFFFAOYSA-L mercury dibromide Chemical compound Br[Hg]Br NGYIMTKLQULBOO-UHFFFAOYSA-L 0.000 description 1
- 229940008718 metallic mercury Drugs 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 125000000621 oxo-lambda(3)-chloranyloxy group Chemical group *OCl=O 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000000737 periodic Effects 0.000 description 1
- 238000011020 pilot scale process Methods 0.000 description 1
- 239000012265 solid product Substances 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 230000002588 toxic Effects 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 239000002341 toxic gas Substances 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
Abstract
The present invention relates generally to the field of emission control equipment for boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices (e.g., those located at power plants, processing plants, etc.) and, in particular to a new and useful method and apparatus for capturing, oxidizing, lowering the concentration and/or level of, and/or eliminating mercury present in any flue gas and/or combustion gas stream. In one embodiment, the method and/or apparatus of the present invention is applied to boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices that have connected thereto at least one type of flue gas, or combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber). pturing, oxidizing, lowering the concentration and/or level of, and/or eliminating mercury present in any flue gas and/or combustion gas stream. In one embodiment, the method and/or apparatus of the present invention is applied to boilers, heaters, kilns, or other flue gas-, or combustion gas-, generating devices that have connected thereto at least one type of flue gas, or combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber).
Description
METHOD AND APPARATUS FOR REMOVING
MERCURY FROM A FLUE GAS STREAM
RELATED APPLICATION DATA
This patent application claims priority to United States Provisional Patent
Application No. 62/116,061 filed February 13, 2015 and titled "Method and Apparatus
for Removing Mercury from a Flue Gas Stream." The complete text of this patent
application is hereby incorporated by reference as though fully set forth herein in its
entirety.
FIELD AND BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to the field of emission control
equipment for boilers, heaters, kilns, or other flue gas, or combustion gas, generating
devices (e.g., those located at power plants, processing plants, etc.) and, in particular to
a new and useful method and apparatus for capturing, oxidizing, lowering the
concentration and/or level of, and/or eliminating mercury present in any flue gas and/or
combustion gas stream. In one embodiment, the method and/or apparatus of the
present invention is applied to boilers, heaters, kilns, or other flue gas, or combustion
gas, generating devices that have connected thereto at least one type of flue gas, or
combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber).
2. Description of the Related Art
In recent years, the U.S. Department of Energy (DOE) and the U.S.
Environmental Protection Agency (EPA) have supported research to measure and
control the emissions of Hazardous Air Pollutants (HAPs) from coalf ired utility boilers
and waste to energy plants. The initial results of several research projects showed that
the emissions of heavy metals and volatile organic carbons (VOCs) are very generally
low, except for mercury (Hg). Unlike most of the other metals, most of the mercury
remains in the vapor phase and does not substantially condense onto fly ash particles
at temperatures typically used in electrostatic precipitators and fabric filters. Therefore,
it cannot be collected and disposed of along with fly ash like the other metals in order to
meet strict mercury stack emission limits (e.g., MATS in the United States, the
European Community's mercury emission limits and/or regulations, and/or any other
countries' and/or organization's mercury emission limit guidelines and/or regulations) .
To complicate matters, mercury can exist in its oxidized (Hg ) form, principally as
mercuric halide (e.g., HgCl , HgBr , HgI , etc.), or in its elemental (Hg ) form as
2 2 2
vaporous metallic mercury. The relative amount of each species appears to depend on
several factors such as fuel type, boiler combustion efficiency, the type of particulate
collector installed, and various other factors.
The search for industrially acceptable methods for the capture of mercury
from industrial flue gases has included a significant effort to determine how much
mercury can be removed by existing, conventional air pollution control equipment, such
as wet or dry scrubbers.
Accordingly, tests have been performed on several commercial scale and
pilot scale wet scrubbers. In addition to being applicable to dry scrubber situations,
these tests have produced some expected and some surprising results. It was
generally expected that the oxidized mercury would be easily captured and the
elemental mercury would be difficult to capture. These expectations were based on the
high solubility of mercuric halides in water and the very low solubility of elemental
mercury in water. This expectation was generally fulfilled.
The surprising result concerned elemental mercury. Repeated tests
during which the concentration of elemental mercury in the flue gas was measured
revealed that more elemental mercury was leaving the wet scrubber than was entering.
While not wishing to be bound to any one theory, it is believed that various
ions present in wet scrubber slurries and/or in the flue gas stream of wet and/or dry
scrubbers cause reduction of a portion of any oxidized mercury present in a flue gas
and/or combustion gas stream converting same back to elemental mercury (Hg ). This
portion is then emitted out of the stack of, for example, a power plant as elemental
mercury is much more difficult to capture in any one or more downstream emission
control devices and/or downstream air quality control system (AQCS) devices.
Thus, there is a need in the art for a method that accomplishes both an
acceptable level of mercury oxidation (e.g., "a high degree of mercury oxidation") in a
flue gas, or combustion gas, stream as well as a method that simultaneously
accomplishes control of mercury emission from a scrubber, be it wet or dry.
SUMMARY OF THE INVENTION
As noted above, the present invention relates generally to the field of
emission control equipment for boilers, heaters, kilns, or other flue gas, or combustion
gas, generating devices (e.g., those located at power pla nts, processing plants, etc.)
and, in particular to a new and useful method and apparatus for capturing, oxidizing,
lowering the concentration and/or level of, and/or eliminating mercury present in any
flue gas and/or combustion gas stream. In one embodiment, the method and/or
apparatus of the present invention is applied to boilers, heaters, kilns, or other flue gas,
or combustion gas, generating devices that have connected thereto at least one type of
flue gas, or combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber). In
another embodiment, the flue gas, or combustion gas, scrubber device is a wet flue gas
desulfurization (WFGD) device.
Accordingly, one aspect of the present invention is drawn to a method for
oxidizing elemental mercury present in a flue gas, or combustion gas, stream wherein
the method comprises the steps of: (I) burning at least one fuel so as to yield a
mercuryco ntaining flue gas, or combustion gas, stream wherein at least a portion of the
mercury in the mercuryco ntaining flue gas, or combustion gas, stream is elemental
mercury; (II) injecting one or more halogenco ntaining compou nds into the mercury
containing flue gas, or combustion gas, stream in order to oxidize at least a portion of
the elemental mercury in the mercuryco ntaining flue gas, o r combustion gas, stream
into oxidized mercury and form one or more corresponding mercury halide compounds;
and (III) injecting one or more sulfurco ntaining compounds and/or sulfide salt
compounds into at least one air quality control device in order to convert the one or
more mercury halide compounds into one or more insoluble mercurysu lfur compounds.
In yet another aspect of the present invention, there is provided a method
for oxidizing and capturing elemental mercury present in a flue gas, or combustion gas,
stream wherein the method comprises the steps of: (A) burning at least one fuel so as
to yield a mercuryco ntaining flue gas, or combustion gas, st ream wherein at least a
portion of the mercury in the mercuryco ntaining flue gas, or combustion gas, stream is
elemental mercury; (B) injecting one or more halogenco ntainin g compounds into the
mercuryco ntaining flue gas, or combustion gas, stream in order to oxidize at least a
portion of the elemental mercury in the mercuryco ntaining flue gas, or combustion gas,
stream into oxidized mercury and form one or more corresponding mercury halide
compounds; (C) injecting one or more sulfurco ntaining compo unds and/or sulfide salt
compounds into at least one air quality control device in order to convert the one or
more mercury halide compounds into one or more insoluble mercurysu lfur compounds;
and (D) capturing the one or more insoluble mercurysu lfur compo unds in at least one
air quality control device and/or downstream process equipment device.
In yet another aspect of the present invention, either of the above methods
further comprises at least one, or both, of the steps of: supplying at least one control
device and one or more mercury sensing devices, or sensors, wherein the at least one
control device is operatively connected to the one or more mercury sensing devices, or
sensors, in order to provide data on at least one of: (i) oxidized mercury concentration
level in the flue gas, or combustion gas, stream, (ii) elemental mercury concentration
level in the flue gas, or combustion gas, stream, and/or (iii) mercury speciation levels in
the flue gas, or combustion gas, stream; and optionally using the data from Step (IV) to
determine the amount of either one, or both, of: (a) the one or more halogenco ntaining
compounds that are injected in Step (II), and/or (b) the one or more sulfurco ntaining
compounds and/or sulfide salt compounds that are injected in Step (III). In still yet
another aspect of the present invention, the two additional steps detailed above are
performed in realt ime.
The various features of novelty which characterize the invention are
pointed out with particularity in the claims annexed to and forming a part of this
disclosure. For a better understanding of the invention, its operating advantages and
specific benefits attained by its uses, reference is made to the accompanying drawings
and descriptive matter in which exemplary embodiments of the invention are illustrated.
BRIEF DESCRIPTION OF THE DRAWINGS
is an illustration of a coalf ired boiler install ation;
is an illustration of the mercury emission control portion of the
present invention;
is an illustration of another embodiment of the mercury emission
control portion of the present invention;
is an illustration of still another embodiment of the mercury
emission control portion of the present invention; and
is an illustration of a complete mercury oxidation and mercury
emission control system of the present invention according to one embodiment of the
present invention.
DESCRIPTION OF THE INVENTION
As noted above, the present invention relates generally to the field of
emission control equipment for boilers, heaters, kilns, or other flue gas, or combustion
gas, generating devices (e.g., those located at power pla nts, processing plants, etc.)
and, in particular to a new and useful method and apparatus for capturing, oxidizing,
lowering the concentration and/or level of, and/or eliminating mercury present in any
flue gas and/or combustion gas stream. In one embodiment, the method and/or
apparatus of the present invention is applied to boilers, heaters, kilns, or other flue gas,
or combustion gas, generating devices that have connected thereto at least one type of
flue gas, or combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber). In
another embodiment, the flue gas, or combustion gas, scrubber device is a wet flue gas
desulfurization (WFGD) device.
In one embodiment, the present invention provides a method and/or
apparatus that simultaneously accomplishes at least the following two objectives. The
first objective is to affect the oxidation of elemental mercury (Hg ), such as gasp hase
elemental mercury and/or any other elemental mercury in the AQCS train, that is
present in any flue gas and/or combustion gas stream into any suitable oxidized state
(e.g., Hg ). The second objective of the present invention is to affect the capture of
such oxidized mercury by converting, binding and/or precipitating such oxidized mercury
into a chemical form that is considered insoluble in an aqueous environment (i.e., a
waterb ased environment). In one embodiment, the oxi dized mercury is captured by
converting any one or more compounds carrying oxidized mercury into an insoluble
mercury (II) sulfide. Mercury (II) sulfide has a solubility constant of between 3×10
and 2×10 . Thus, for the purposes of meeting various stack mercury emission
regulations the conversion of various oxidized mercuryco ntain ing compounds into
mercury sulfide permits the precipitation and thus capture and removal of mercury from
a flue gas, or combustion gas, stream.
An optional third objective of the present invention is the control of
elemental mercury emission across a SO scrubber (e.g., a wet FGD, or dry FGD), a
reduction in and/or a lowering of the concentration and/or level of elemental mercury
that is either emitted and/or present in a flue gas stream, and/or the elimination of at
least a portion of any mercury that may be emitted from any type of flue gas
desulfurization unit such as a wet flue gas desulfurization (WFGD) unit and/or dry flue
gas desulfurization (DFGD) unit. In some instances emission of mercury from a wet, or
dry, scrubber is termed "ree mission" in that a portion of wh at was previously oxidized
mercury is reduced in the scrubber environment to elemental mercury and then is able
to "escape" the scrubber and is emitted at, for example, the stack as elemental mercury.
For the purposes of this patent application, any oxidized mercury that is reduced in a
scrubber environment and then subsequently escapes and is emitted at a stack will be
considered mercury emission and shall include any mercury that could be considered to
fall under the term ree mission as used by those skilled in t he art. An optional fourth
objective of the present invention is to integrate the mercury oxidation process and the
mercury capture process by using at least one suitable mercury sensing device or
sensor (e.g., a gasp hase mercury concentration probe, a gas phase mercury
speciation probe, an aqueousp hase mercury concentration prob e, an aqueousp hase
mercury speciation probe, etc., or even any combination of two or more probes and/or
probe types, three or more probes and/or probe types, or four or more probes and/or
probe types) to determine the amount of various types of mercury (i.e., oxidized
mercury, elemental mercury and/or various mercuryco ntaining com pounds, regardless
of whether such mercury and/or mercuryco ntaining compounds a re gasp hase, liquid
phase, and/or solid phase compounds) present at various locations in one or more
boilers, heaters, kilns, or other flue gas, or combustion gas , generating devices and/or
any one or more emission control devices and/or air quality control system (AQCS)
devices so as to permit a more exact level of mercury control throughout the whole flue
gas, or combustion gas stream through the use of at least one feedback loop, logic
control system, or other automated system. An optional fifth objective of the present
invention is to integrate the gasp hase mercury oxidatio n process and the mercury
capture process while permitting the control of mercury ree mi ssion, the reduction in
and/or the lowering of the concentration and/or level of elemental mercury that is either
emitted and/or present in a flue gas stream, and/or the elimination of at least a portion
of any mercury that may be emitted from any type of flue gas desulfurization unit by
using at least one suitable mercury sensing device or sensor (e.g., a gasp hase
mercury concentration probe, a gasp hase mercury speciation prob e, an aqueous
phase mercury concentration probe, an aqueousp hase mercury sp eciation probe, etc.,
or even any combination of two or more probes and/or probe types, three or more
probes and/or probe types, or four or more probes and/or probe types) to determine the
amount of various types of mercury (i.e., oxidized mercury, elemental mercury and/or
various mercuryco ntaining compounds, regardless of whether such mercury and/or
mercuryco ntaining compounds are gasp hase, liquid phase, and/or solid phase
compounds) present at various locations in one or more boilers, heaters, kilns, or other
flue gas, or combustion gas, generating devices and at at least one location in a flue
gas desulfurization unit so as to permit a more exact level of mercury control throughout
the whole flue gas, or combustion gas stream through the use of at least one feedback
loop, logic control system, or other automated system. This fifth objective can further
include determining the amount of various types of mercury at any one or more
locations in any one or more other emission control devices and/or air quality control
system (AQCS) devices beyond a flue gas desulfurization unit.
In light of the above, the present invention utilizes any suitable technique
to accomplish mercury oxidation. Such techniques include, but are not limited to,
adding, placing, injecting or combining with the fuel (e.g., coal, fuel oil, other fossil fuels,
biomass, or a blend of biomass with one or more fossil fuels, etc.) for a boiler, heater,
kiln, or other flue gas, or combustion gas, generating d evice one or more halogen
containing compounds. Such act of adding, placing, injecting or combining one or more
halogenco ntaining compounds with the fuel for a boiler, heater, kiln, or other flue gas,
or combustion gas, generating device can occur on the fuel itself (e.g., on the coal, the
coal belt, in the coal pulverizer, on the biomass, mixed in with the biomass, etc.), in one
or more burners, at one or more places in the boiler, heater, kiln, or other flue gas, or
combustion gas, generating device (e.g., an economizer pa ss, one or more burners, a
combustion grate, etc.), at one or more places in the flue gas, or combustion gas,
stream after exit from the boiler/furnace, at one or more places in any one or more
emission control, or AQCS, devices, etc. Thus, it should be understood that when the
phrase "injecting one or more halogenc ontaining compound s into the mercury
containing flue gas, or combustion gas, stream" is utilized herein and/or in the claims,
that such phrase is to be broadly construed to include all forms of injection and all
possible injection points including, but not limited to, onto the fuel itself (e.g., on the
coal, the coal belt, in the coal pulverizer, on the biomass, mixed in with the biomass,
etc.), directly or indirectly into one or more of the burners or other devices used to
combust such fuel, at one or more places in the boiler, heater, kiln, or other flue gas, or
combustion gas, generating device (e.g., an economizer pa ss, one or more burners, a
combustion grate, etc.), at one or more places in the flue gas, or combustion gas,
stream after exit from the boiler/furnace, at one or more places in any one or more
emission and/or emissions control (generically referred to herein as emission control),
or AQCS, devices, etc.
Such halogenc ontaining compounds include, but are not l imited to, one or
more chlorineco ntaining compounds, one or more bromineco nt aining compounds, one
or more iodineco ntaining compounds, or any combination of two or more thereof, three
or more thereof, four or more thereof, or even five or more thereof. The one or more
chlorineco ntaining compounds include, but are not limited to, one or more inorganic
chlorine compounds, organic chlorineco ntaining compounds, o ne or more diatomic
chlorine compounds, or any combination of two or more thereof, three or more thereof,
four or more thereof, or even five or more thereof. The one or more bromineco ntaining
compounds include, but are not limited to, one or more inorganic bromine compounds,
organic brominec ontaining compounds, one or more diatomi c bromine compounds, or
any combination of two or more thereof, three or more thereof, four or more thereof, or
even five or more thereof. The one or more iodineco nta ining compounds include, but
are not limited to, one or more inorganic iodine compounds, organic iodineco ntaining
compounds, one or more diatomic iodine compounds, or any combination of two or
more thereof, three or more thereof, four or more thereof, or even five or more thereof.
In another embodiment, any combination of one or more, two or more, three or more,
four or more, or even five of more halogenco ntaining comp ounds containing different
halogen portions thereof can be used together. Thus, in this embodiment any suitable
number of chlorineco ntaining compounds discussed herein can be combined with any
suitable number of bromineco ntaining compounds and/or any suitable number of
iodineco ntaining compounds. In still another embodimen t the halogenco ntaining
compound utilized in the various methods of the present invention contains at least one
of the chlorineco ntaining compounds discussed herein in com bination with at least one
of the bromineco ntaining compounds discussed herein and in further combination with
at least one of the iodineco ntaining compounds discussed herein.
Nonl imiting examples of the above compounds include al kalim etal
halides (e.g., NaCl, NaBr, NaI, KCl, KBr, KI, etc.), any alkalim etal halogenco ntaining
compounds (e.g., NaClO , NaClO , NaClO , NaBrO , NaIO , NaIO , Na IO , Na H IO ,
2 3 4 3 3 4 5 6 3 2 6
KClO, KClO , KClO , KBrO , KIBr , KIO , KIO •HIO , KIO •2HIO , KIO , KI •½H O,
3 4 3 2 3 3 3 3 3 4 3 2
etc.), any alkalie arth halogenco ntaining compounds (e.g., MgCl , MgBr , MgI , CaCl ,
2 2 2 2
CaBr2, CaI2, Ca(ClO3)2, (CaClO4)2, Ca(BrO3)2, Ca(IO3)2, etc.), any compound that
contains at least two different halogens (e.g., BrCl, IBr, IBr3, ICl, ICl3, etc.), any
compound that contains at least one halogen and oxygen (e.g., ClO2, Cl2O7, Cl2O, ClO4,
Cl2O8, BrO2, Br2O, Br3O8, IO2, I2O4, I2O5, I4O9, etc.), any compound that contains at
least one halogen and hydrogen (e.g., HCl, HClO , HClO , HBr, HBrO , HI, HIO , etc.),
3 4 3 3
any diatomic halogenco ntaining compounds (e.g., Cl , Br , I , etc.), any organic
2 2 2
compounds that contain therein at least one atom of chlorine, bromine, and/or iodine, or
any combination of two or more thereof, or even all three thereof. It should be noted
that any of the above classes of compounds can be used in either the anhydrous form
and/or any hydrated form (if one or both of such compounds are available). Although
the above compounds are represented by the anhydrous forms such forms are meant to
encompass all available hydrated forms and related forms of such compounds that are
known to those of skill in the art.
In one embodiment, the present invention provides a means in a wet or
dry scrubber to rapidly precipitate at least a portion of any aqueous oxidized mercury, or
other form of oxidized mercury (e.g., a gasp hase form), in the scrubber before it can be
reduced by other factors, ions, and/or compounds that may be present therein. One of
the most insoluble forms of mercury is mercuric sulfide, which in mineral form is
cinnabar. One means for supplying a source of sulfide to react with the oxidized
mercury is aqueous sulfide ions. Thus, at the gas/liquid interface in the scrubber, the
following reaction is proposed for the absorption and precipitation of ionized (oxidized)
mercury:
2− −
S (aq) + HgCl2(g) → HgS(s) + 2Cl (aq)
2− −
S (aq) + HgBr2(g) → HgS(s) + 2Br (aq)
2− −
S (aq) + HgI2(g) → HgS(s) + 2I (aq)
HgS has a solubility product of approximately 3×10 and therefore
precipitates essentially completely. The aqueous sulfide species is added to the
scrubbing liquor of the scrubber and comes into contact with the mercury in the flue gas,
such that HgS is formed when the mercury is absorbed into the liquor. Therefore, the
oxidized mercury will rapidly precipitate as cinnabar in the scrubber and thereby prevent
the reduction of that mercury back to sparingly soluble elemental mercury. The
precipitation of mercury as cinnabar has a distinct advantage over other mercury
sequestering methods in that it converts mercury to a very insoluble form.
Accordingly, one aspect of the present invention is drawn to an
improvement in a method using a scrubber for receiving and scrubbing an industrial gas
containing mercury, the improvement comprising: adding an aqueous sulfide salt to the
industrial gas and scrubbing the industrial gas in the scrubber. The method according
to the present invention is particularly suited to the task of reducing mercury emissions
in an industrial process which burns coal in a furnace to produce an exhaust flue gas,
including conveying the exhaust flue gas through a dust collector, such as a fabric filter
or electrostatic precipitator.
Another aspect of the present invention is drawn to an apparatus using a
scrubber for receiving and scrubbing an industrial gas containing mercury with an
aqueous alkali reagent, and particularly the improvement comprising: means for
providing sulfide ions and means for controlling the sulfide ions provided to the industrial
gas in the scrubber. The present invention is again particularly suited to utility
installations which burn fossil fuels such as coal, or solid wastes, and which use a dust
collector (such as an electrostatic precipitator or a fabric filter), in addition to the
scrubber, and/or other conventional components for reducing emissions to the
atmosphere.
Another aspect of the present invention is drawn to an apparatus for
receiving and scrubbing an industrial gas containing mercury with an aqueous alkali
reagent, comprising a scrubber, having a scrubber liquor, for scrubbing the industrial
gas with the aqueous alkali reagent; flue means for conveying the industrial gas to the
scrubber; means for providing sulfide ions; and means for controlling the sulfide ions
provided to the industrial gas. The present invention is again particularly suited to utility
installations which burn fossil fuels, such as coal, and can be incorporated into a wet
and/or or dry scrubber.
All aspects of the present invention contemplate means for providing
sulfide ions, including but not limited to bisulfide (HS ) ions. Notably, such bisulfide ions
– 2–
(HS ) provide sulfide ions (S ) by virtue of the equilibrium in an aqueous solution:
2− − −
S + H O HS + OH
(aq) 2 (aq) (aq)
This means can be accomplished through the addition of one or more
aqueous sulfide compounds, or species, including, but not limited to, sulfidic waste
water, kraft caustic liquor, kraft carbonate liquor, potassium sulfide, sodium sulfide,
sodium hydrogen sulfide (NaHS), thioacetamide, or suitable mixtures of two or more
thereof, suitable mixtures of three or more thereof, or even suitable mixtures of four or
more thereof to the scrubbing liquor in the scrubber. In another embodiment, any
suitable inorganic source of aqueous sulfide species can be utilized herein as the later
described one or more sulfide precipitating agents. Further, control means, such as a
separate storage tank and metering pump, can be employed to selectively control the
provision of sulfide to meet specific operational requirements.
This system has an inherent safety advantage in that no H S, which is
odorous and toxic, is accumulated or stored. Further, the system is versatile in that it is
equally applicable to wet and/or dry scrubbers and can be incorporated into current
emissions control systems with minimal modifications or additions.
Referring to the drawings generally, wherein like reference numerals
designate the same or functionally similar elements throughout the several drawings,
and to in particular, illustrates a coalf ir ed utility boiler installation of the
type used by utilities in the generation of electric power, generally designated 10, and
which represents one type of industrial process to which the present invention is
applicable. In its broadest form, the present invention comprises a method for removing
mercury from the flue gas generated during the combustion of fossil fuels or solid
wastes through the use of aqueous sulfide ions. Of course, while the aforementioned
coalf ired utility boiler installations are but one exam ple, and the method of the present
invention will likely first find commercial application to the removal of mercury from the
flue gases produced by such utility boiler installations which combust such fossil fuels,
any industrial process using a wet scrubber type of absorber module to purify such flue
gases may benefit. Such processes could include incineration plants, waste to energy
plants, or other industrial processes which generate gaseous products containing
mercury. Thus for the sake of convenience, the terms industrial gas, flue gas, or simply
gas will be used in the following discussion to refer to any gas from an industrial
process and from which an objectionable component, such as mercury, is to be
removed.
As will be described herein, an alternate embodiment of the present
invention involves methods and apparatus for the addition of aqueous sulfide ions to
industrial gases which are treated by dry scrubber flue gas desulfurization systems.
Thus, while the majority of the following description is presented in the context of the
present invention as being applied to wet scrubber systems, it will be appreciated that
the present invention is not limited thereto. Further, since both wet and dry scrubbers
remove sulfur species from the flue gas by introduction of an alkali sorbent, some
common terminology is used for the sake of convenience. In the case of wet scrubbers,
the alkali sorbent can be provided as an aqueous alkali solution or slurry; in dry
scrubbers, the alkali sorbent is usually provided as an aqueous alkali slurry. Thus, for
the sake of convenience in the following description, the term aqueous alkali reagent
will be used to encompass both aqueous alkali solutions and/or aqueous alkali slurries
as appropriate to the type of scrubber means being used.
As illustrated in and proceeding in the direction of flue gas flow
generated during the combustion process, the boiler installation 10 includes a furnace
12 having a gas outlet 14 which conveys flue gases, generally designated 16, to an air
heater 18 used to preheat incoming air 20 for combustion. In this exemplary
embodiment, pulverizers 22 grind a fossil fuel 24 (e.g., coal) to a desired fineness and
the pulverized coal 24 is conveyed via burners 25 into the furnace 12 where it is burned
to release heat used to generate steam for use by a steam turbinee lectric generator
(not shown). Flue gas 16 produced by the combustion process is conveyed through the
gas outlet 14 to the air heater 18 and thence to various types of downstream flue gas
cleanup equipment. The flue gas cleanup equipment can comprise a fabric filter or, as
shown, an electrostatic precipitator (ESP) 26 which removes particulates from the flue
gas 16. A flue 28 downstream of the ESP 26 conveys the flue gas 16 to a wet scrubber
absorber module 30 which is used to remove sulfur dioxide and other contaminants
from the flue gas 16. Flue gas 16 exiting from the wet scrubber absorber module or,
simply, the wet scrubber 30, is conveyed to a stack 32 and exhausted to atmosphere.
Forced draft fans 34 and induced draft fans 36 are used to propel the air 20, fuel 24,
and flue gases 16 through the installation 10. For further details of various aspects of
such installations 10, the reader is referred to Steam/its generation and use, 41
Edition, Kitto and Stultz, Eds., Copyright 2005, The Babcock & Wilcox Company,
Barberton, Ohio, U.S.A., particularly to Chapter 35 – Sulfur Dioxide Control, the text of
which is hereby incorporated by reference as though fully set forth herein. While the
aforementioned Steam reference contains a description of one form of wet scrubber 30
produced by The Babcock & Wilcox Company (B&W) and to which the present
invention is applicable, the present invention is not limited to such B&W wet scrubber
designs. Persons skilled in the art will appreciate that the principles of the present
invention apply equally well to other types of wet scrubber designs, available from other
manufacturers.
The wet scrubber 30 contains, in a lower portion thereof, an inventory of
scrubber liquor 38. During operation of the wet scrubber 30, recirculation pumps 40
pump and recirculate the scrubber liquor 38 up through pipes 42 and into absorber
spray headers 44 (see for an internal illustration of spray headers 44 in wet
scrubber 30) located in an upper portion of the wet scrubber 30. The scrubber liquor 38
is sprayed into the flue gas 16 where it absorbs SO2. The scrubber liquor 38 falls down
through various devices and drains back into the lower portion of the wet scrubber 30.
The scrubbed flue gas 16 then exits from a wet scrubber outlet 46 and is eventually
conveyed to the stack 32.
depicts a detailed schematic of one possible embodiment of the
wet scrubber 30. Wet scrubber 30 comprises a main chamber 300 with scrubber inlet
45 and scrubber outlet 46. As above, main chamber 300 has a lower portion containing
an inventory of scrubber liquor 38 which recirculates from the main chamber 300 into
absorber spray headers 44 by means of general recirculation line 302. General
recirculation line 302 can comprise pipes 42 and recirculation pumps 40. Frequently,
the lower portion of main chamber 300 containing scrubber liquor 38 will include means
for injecting air, such as air sparger 41, into the scrubber liquor 38. The use of air
sparger 41 oxidizes the products of SO absorption in scrubbing liquor 38. Finally,
scrubber liquor 38 can be contained in a bulk storage vessel which forms the lower
portion of main chamber 300 (as pictured), or it can comprise a separate holding tank
connected to a drain in the main chamber 300 and recirculation line 302.
A sulfidec ontaining salt can be added directly to scrubbe r liquor 38 and
mixed with the flue gas 16 via spray headers 44, thereby creating an aqueous sulfide
ion solution (hereafter referred to as an aqueous sulfide species). In turn, by injecting
this aqueous sulfide species directly into recirculation pump 40 and/or general
recirculation line 302, the added sulfide solution will not be prematurely oxidized before
contacting and scrubbing flue gas 16 in the main chamber 300. In another embodiment,
the source of the sulfide ions can be provided by means of sulfidic waste water, kraft
caustic liquor, kraft carbonate liquor, or an aqueous solution containing potassium
sulfide, sodium sulfide, sodium hydrogen sulfide (NaHS), thioacetamide, or any
combination of two or more thereof, three or more thereof, four or more thereof, or even
five or more thereof.
Alternatively, sulfide ion solution can be added to an isolated sulfide
storage tank 310 which is connected to recirculation line 302 upstream of recirculation
pump 40. This is but one possible addition and/or injection point out of numerous
places where sulfide ions and/or a sulfide ion solution in accordance with the present
invention can be added and/or injected and is by no means meant to be seen in any
manner as limiting and/or exhaustive of any other possible addition and/or injection
points. Further, a metering pump 312 can be employed to control the flow of sulfide
ions into the wet scrubber 30 and, more particularly, into and/or through recirculation
line 302 (a system employing metering pump 312 for control of sulfide into recirculation
line 302 only is shown). The concentration of sulfide ion and/or rate of flow into and/or
through the recirculation line 302 permits the selective control of the scrubber's overall
mercury removing ability. Thus, a coordinated control system, such as using storage
tank 310 and/or metering pump 312, is one possible embodiment of the present
invention. The rate of sulfide addition must be proportional to the flue gas flow rate
through the scrubber.
In operation, flue gas 16 flows from inlet 45 into main chamber 300.
Sulfide ions added to recirculation line 302 allow spray header 44 to mix the sulfide ions
and scrubber liquor 38 with the flue gas 16. This contact initiates the chemical reaction
which removes mercury. The flue gas then flows through outlet 46 and into the stack
32. The precipitated mercury remains in scrubber liquor 38 and can be subsequently
removed and disposed of by various methods known to those skilled in the art.
As described earlier and as illustrated in the present invention is
also applicable to combustion systems employing dry scrubbers for flue gas
desulfurization. Again, like reference numerals designate the same or functionally
similar parts. Flue gas 16 produced by the combustion process are conveyed through
the gas outlet 14 to the air heater 18 and thence to various types of downstream flue
gas cleanup equipment. A flue 28 conveys the flue gas 16 to a dry scrubber absorber
module 150 which is used to remove sulfur dioxide and other contaminants from the flue
gas 16. Flue gas 16 exiting from the dry scrubber 150 is conveyed to a fabric filter or,
as shown, an electrostatic precipitator (ESP) 26 which removes particulates from the
flue gas 16 and then the flue gas 16 is conveyed to a stack 32 and exhausted to the
atmosphere. Regarding arrow 58, arrow 58 represents an input line, or supply line, for
the injection of sorbent, or absorbent, for use in dry scrubber 150 from vessel 401 (see
that contains therein scrubber liquor 38 (see . As in forced draft
fans 34 and induced draft fans 36 (not shown in are used to propel the air 20,
fuel 24, and flue gases 16 through the installation 10 as before.
depicts a detailed schematic of one possible embodiment of a dry
scrubber 150. Dry scrubber 150 comprises a main chamber 400 with spray header 44,
scrubber inlet 445, and scrubber outlet 446. Notably, scrubber liquor 38 can be
contained in a bulk storage vessel 401 and provided to main chamber 400 by means of
first feed line 402a. Feed line 402a can contain a scrubber liquor feed pump 440.
A sulfideco ntaining salt can be added directly to scrubber liquor 38 in
vessel 401, pumped to main chamber 400 via first feed line 402a, and mixed with flue
gas 16 via spray headers 44. In another embodiment, sulfide ions can be provided by
means of sulfidic waste water, kraft caustic liquor, kraft carbonate liquor, or an aqueous
solution containing potassium sulfide, sodium sulfide, sodium hydrogen sulfide (NaHS),
thioacetamide, or any combination of two or more thereof, three or more thereof, four or
more thereof, or even five or more thereof.
Alternatively, sulfide ion solution can be added to an isolated sulfide
storage tank 410 and introduced into the main chamber 400 via spray header 44. It
should be noted that addition via a solution form is only one possible embodiment, other
exemplary manners of addition include, but are not, slurry, moist powder, powder, etc.
Tank 410 is connected to second feed line 402b. Further or in the alternative, a
metering pump 412 can be employed to control the flow of sulfide ions into the dry
scrubber 150 and, more particularly, into feed line(s) 402a and/or bulk storage vessel
401 (a system employing metering pump 412 for control of feed line 402a only is
pictured). The concentration of sulfide ion and/or rate of flow into and/or through the
feed line(s) 402a and/or 402b permits the selective control of the scrubber's overall
mercury removing ability. Thus, a coordinated control system, such as using storage
tank 410 and/or metering pump 412, is one possible embodiment of the present
invention. However, control of sulfide ions provided to the gas can also be achieved by
periodic and/or manual addition of the aqueous sulfide ions into the scrubber system by
way of a valve, port, or other injection device or by means of a separate system (i.e.,
chamber, storage means, spray headers, and/or recirculation line).
In operation, flue gas 16 flows from inlet 445 into main chamber 400.
Sulfide ions added to feed line 402a and/or bulk storage vessel 401 allow spray header
44 to mix the sulfide ions and scrubber liquor 38 with the flue gas 16. This contact
initiates the chemical reaction which removes mercury. The flue gas then flows through
outlet 446 and into the stack 32 (see . The precipitated mercury remains in the
dried solid product of scrubber 150 (see and can be subsequently removed and
disposed of by various methods known to those skilled in the art.
Advantages of the present invention include the fact that the cost of
control of mercury emissions according to the present invention is relatively low
compared to the costs for control of other hazardous air pollutants. Further, the use of
aqueous sulfide ions can be incorporated with minimal modifications or additions to
current emissions control systems. Most significantly, use of aqueous sulfide ions
eliminates the need to produce or have available toxic gases, such as hydrogen sulfide
gas, which, when mixed with flue gas containing mercury oxidized by an aqueous alkali
reagent can be another method for removing mercury from flue gas. Also, aqueous
sulfide ions can be easily metered into the main scrubbing liquor inventory at a specific,
desired rate in order to enhance efficiency of the scrubber or to achieve specific results.
According to the present invention, the mercury in the flue gas 16 ends up
as mercuric sulfide (also known as cinnabar). This is the chemical form that mercury is
most often found in nature and is probably the most desirable chemical form to
sequester mercury.
Thus, the present invention is, in one embodiment, a combination of two
technologies necessary for a WFGD system to achieve Hg MATS compliance, upf ront
mercury oxidation in a flue, or combustion, gas prior to entrance of same into a WFGD
system, and then the addition of one or more additives to subsa turate the liquid phase
of the WFGD absorber slurry to permit "capture" of such oxidized mercury as an
insoluble, or nearly insoluble, compound such as, for example, mercuric sulfide (i.e.,
cinnabar). In another embodiment, the present invention also permits upf ront mercury
oxidation in a flue, or combustion, gas prior to entrance of same into a DFGD system,
and then the addition of one or more additives to a DFGD to convert some portion of
such oxidized mercury into an insoluble, or nearly insoluble, form so that such oxidized
mercury can be "captured" in any appropriate AQCS device in the form of, for example,
mercuric sulfide (i.e., cinnabar).
As discussed herein, various methods including the use of one or more
halogenco ntaining compounds can be utilized to achieve mercury oxidation in a flue
gas, or combustion gas, stream. Although a detailed discussion of a method that
utilizes one or more halogenco ntaining compounds to ach ieve gasp hase mercury
oxidation is discussed herein, the present invention is not limited to solely this method to
achieve mercury oxidation. Rather, any mercury oxidation method known to those of
skill in the art can be utilized such as one or more catalytic methods, one or more SCR
based methods, one or more chemical additiveb ased method s (e.g., the use of one or
more halogenco ntaining compounds, or other mercury oxidatio n achieving
compounds), or any two or more of the above, or other known, mercury oxidation
methods that can achieve mercury oxidation in a flue gas, or combustion gas, stream.
In one embodiment, the various methods of the present invention utilize a
method and/or chemical additive that achieve a high degree of mercury oxidation in a
flue gas, or combustion gas, stream while minimizing the negative, or deleterious,
effects produced from the execution of such a mercury oxidation method. As utilized
herein, "a high degree of mercury oxidation" means that at least about 70 weight
percent, at least about 75 weight percent, at least about 80 weight percent, at least
about 85 weight percent, at least about 90 weight percent, at least about 92.5 weight
percent, at least about 95 weight percent, at least about 97.5 weight percent, or even at
least about 98 weight percent of any elemental mercury (i.e., Hg ) present in a flue gas,
or combustion gas, stream is oxidized to at least one oxidized mercury state (e.g., Hg ,
Hg , etc.). In one embodiment, the mercury oxidation methods of the present invention
are designed to achieve the oxidation of the majority (i.e., more than about 50, about
60, about 70, about 80, about 90, about 95, or even about 99 percent by weight) of
elemental mercury to Hg . In another embodiment the methods of the present
invention achieve the oxidation of at least about 50 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 55 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 60 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 65 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 70 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 75 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 80 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 85 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 90 weight percent of the elemental
mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one oxidized
+ 2+
mercury state (e.g., Hg , Hg , etc.), or at least about 92.5 weight percent of the
elemental mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one
+ 2+
oxidized mercury state (e.g., Hg , Hg , etc.), or at least about 95 weight percent of the
elemental mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one
+ 2+
oxidized mercury state (e.g., Hg , Hg , etc.), or at least about 97.5 weight percent of
the elemental mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one
+ 2+
oxidized mercury state (e.g., Hg , Hg , etc.), or at least about 98 weight percent of the
elemental mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least one
+ 2+
oxidized mercury state (e.g., Hg , Hg , etc.), or even at least about 99 weight percent
of the elemental mercury (i.e., Hg ) in a flue gas, or combustion gas, stream to at least
+ 2+
one oxidized mercury state (e.g., Hg , Hg , etc.). Here, as well as elsewhere in the
specification and claims, individual numerical values can be combined to form additional
and/or nond isclosed ranges.
Thus, in one embodiment, one or more iodineco ntaining compounds, or
chemical additives, are utilized to achieve a desired level of mercury oxidation. One
nonl imiting advantage to the use of one or more iodi neco ntaining compounds is that
such a mercury oxidation method can utilize lower iodine levels to achieve a desired
level of mercury oxidation. This in turn results in the flue gas, or combustion gas,
stream, having a lower corrosion potential while still resulting in a mercury oxidation of,
in one embodiment, at least about 87.5 weight percent of any elemental mercury
present in a flue gas, or combustion gas, stream. In another embodiment, the use of
one or more iodineco ntaining compounds, or chemical additi ves, are utilized to achieve
a mercury oxidation of, in one embodiment, at least about 90 weight percent, at least
about 92.5 weight percent, at least about 95 weight percent, at least about 97.5 weight
percent, or even at least about 98 weight percent of any elemental mercury present in a
flue gas, or combustion gas, stream. Here, as well as elsewhere in the specification
and claims, individual numerical values can be combined to form additional and/or non
disclosed ranges. With such elevated mercury oxidation levels in the flue gas, this
allows the above described one or more sulfide precipitating agents including, but not
limited to, those described herein to be used in the WFGD absorber to meet, for
example, an Hg MATS limit.
is an illustration of one method of the present invention that can
achieve a controll oop and/or control feedback method of achieving a desired level of
compliance with regard to mercury emissions.
In one embodiment, coal 1002 is added to a pulverizer 1004 where it is
ground up prior to entrance to the boiler 1006 where it is burned. A halogenco ntaining
compound such as a bromineco ntaining compound (e.g., CaBr ) is added by, for
example, injecting the brominec ontaining compound int o the at least one coal
pulverizer 1004 at such a level to achieve a bromine concentration in the flue gas, or
combustion gas, stream based on the amount of mercury present in the fuel source
(e.g., coal, fuel oil, other fossil fuels, biomass, or a blend of biomass with one or more
fossil fuels, etc.) of between about 0.5 ppm to about 250 ppm, or between about 1 ppm
to about 237.5 ppm, or between about 2.5 ppm to about 225 ppm, or between about 5
ppm to about 212.5 ppm, or between about 7.5 ppm to about 200 ppm, or between
about 10 ppm to about 187.5 ppm, or between about 12.5 ppm to about 175 ppm, or
between about 15 ppm to about 162.5 ppm, or between about 17.5 ppm to about 150
ppm, or between about 20 ppm to about 137.5 ppm, or between about 22.5 ppm to
about 125 ppm, or between about 25 ppm to about 112.5 ppm, or between about 27.5
ppm to about 100 ppm, or between about 30 ppm to about 87.5 ppm, or between about
32.5 ppm to about 75 ppm, or between about 35 ppm to about 62.5 ppm, or between
about 37.5 ppm to about 50 ppm, or between about 40 ppm to about 47.5 ppm, or even
about 45 ppm. Here, as well as elsewhere in the specification and claims, individual
range values can be combined to form additional and/or nond isclosed ranges.
In another embodiment, coal 1002 is added to a pulverizer 1004 where it
is ground up prior to entrance to the boiler 1006 where it is burned. In this embodiment,
one or more halogenco ntaining compounds selected from an y of various halogen
containing compounds disclosed herein is/are added by, for example, injecting such one
or more halogenc ontaining compound, or compounds, into the at least one coal
pulverizer 1004 at such a level to achieve a halogen concentration in the flue gas, or
combustion gas, stream based on the amount of mercury present in the fuel source
(e.g., coal, fuel oil, other fossil fuels, biomass, or a blend of biomass with one or more
fossil fuels, etc.) of between about 5 ppm to about 250 ppm, or between about 7.5 ppm
to about 237.5 ppm, or between about 10 ppm to about 225 ppm, or between about
12.5 ppm to about 212.5 ppm, or between about 15 ppm to about 200 ppm, or between
about 17.5 ppm to about 187.5 ppm, or between about 20 ppm to about 175 ppm, or
between about 22.5 ppm to about 162.5 ppm, or between about 25 ppm to about 150
ppm, or between about 27.5 ppm to about 137.5 ppm, or between about 30 ppm to
about 125 ppm, or between about 32.5 ppm to about 112.5 ppm, or between about 35
ppm to about 100 ppm, or between about 37.5 ppm to about 87.5 ppm, or between
about 40 ppm to about 75 ppm, or between about 42.5 ppm to about 62.5 ppm, or
between about 45 ppm to about 55 ppm, or even about 50 ppm. Here, as well as
elsewhere in the specification and claims, individual range values can be combined to
form additional and/or nond isclosed ranges.
As noted above, although illustrates injection of the bromine
containing compound into the coal pulverizer, the present invention is not limited thereto
but can be anywhere prior to entrance of the flue gas into a wet, or dry, scrubber. The
bromine (or another bromineco ntaining compound, or even a nother halogenco ntaining
compound, or even a combination of one or more of the same and/or different halogen
containing compounds) helps to oxidize the mercury that is contained within the coal,
such that it presents itself in the flue gas as Hg , making it much easier to capture in
the downstream environmental equipment. While some fraction of the oxidized mercury
is captured in the particulate collection device 1008, the WFGD system 1010 can
remove most of the remainder of the Hg in the WFGD absorber. However, within the
WFGD 1010 system, the slurry liquid can become saturated with mercury, requiring the
addition of at least one precipitating agent 1012. Once the WFGD 1010 liquid is sub
saturated with respect to mercury, stack 1014 Hg MATS compliance can only be met so
long as the WFGD 1010 absorber inlet flue gas elemental mercury Hg concentration is
below the mercury MATS limit. As is also illustrated in the system and/or
method of the present invention utilizes a control device 1016 that is connected to one
or more mercury sensing devices or sensors, and/or receives mercury concentration
and/or speciation data from one or more points in the boiler and/or AQCS train so as to
enable the integrated control, or even realt ime integrat ed control, of the mercury
oxidation method in conjunction with the mercury precipitation method of the present
invention thereby resulting in a desired level of mercury emission compliance at stack
1014 and/or mercury capture in the overall boiler/furnace and/or in one or more AQCS
devices or flues attached thereto. As per the location of the one or more mercury
sensing devices or sensors discussed herein can be located at one or more of the
various locations denoted by the arrows that come out of control device 1016 and end
at the various positions in the flue gas stream and/or one or more of the devices of the
AQCS train. The arrow head that points back to control device 1016 denotes the fact
that various mercury concentration, speciation and/or other mercuryre lated data "flows"
back to control device 1016 so as to permit realt ime control of the injection of one or
more halogenco ntaining compounds discussed herein and/or th e injection of one or
more aqueous sulfide compounds or species and/or sulfide salt compounds discussed
herein.
It should be noted that although illustrates various components of a
boiler/furnace system and some of its attenuated flues and/or AQCS devices, the
present invention is not limited to just the illustrated layout. Rather, any furnace/boiler
system known to those of skill in the art can be utilized in conjunction with the present
invention. As such, the present invention can utilize feedback and/or data obtained
from any number of furnace/boiler sources and/or AQCS device sources.
In another embodiment of the present invention, the bromineco ntaining
compound noted above is replaced with one or more iodine containing compounds. In
this embodiment, much lower quantities of the one or more iodineco ntaining
compounds (e.g., NaI) are able to achieve comparable, or even greater, levels of
mercury oxidation than one or more bromineco ntaining compo unds. Another
advantage of utilizing lower levels of the one or more halogenco ntaining compounds to
achieve a desired level of mercury oxidation in a flue gas, or combustion gas, stream is
that the corrosion rate for the one or more iodineco ntain ing compounds while achieving
an equivalent, or even greater, mercury oxidation rate (or level) is lower. This
addresses an increasing important issue that concerns, for example, utility customers
as such increased corrosion in downstream AQCS devices and/or other systems is
highly undesirable.
Halogen Testing Results
Rate of
Stack (µg/dscm) % of Total corrosion
mil/hr
Run Injection Periods Oxidized Elemental Total Hg Oxidized
1 0 (baseline) 1.89 1.87 3.76 50.30% 0.004
2 0 (baseline) 2.0* 1.97* 3.75* 50.4%*
Not available, used two
3 0 (baseline) 3.54 NA
unspeciated traps
4 0 (baseline) 1.87* 1.61* 3.60* 53.8%*
Average 51.50%
150 ppm Bromine 3.05 0.4 3.45 88.40% 0.029
6 150 ppm Bromine 3.18 0.18 3.36 94.90%
7 150 ppm Bromine 3.23 0.3 3.53 91.50%
8 150 ppm Bromine 3.53 0.1 3.63 97.30%
9 150 ppm Bromine 5.01 0.13 5.13 97.60%
150 ppm Bromine 2.78 0.08 2.86 97.20%
Average 94.50%
11 0 (baseline) 1.14 0.91 2.04 55.50%
12 10 ppm Iodine 4.90* 0.49* 5.39* 90.9%*
13 10 ppm Iodine 3.95 0.14 4.09 96.50% 0.004
Average 93.70%
14 25 ppm Iodine 4.58* 0.04* 4.62* 99.0%* 0.008
25 ppm Iodine 4.03 0 4.03 100.00%
Average 99.50%
16 25 ppm Bromine 1.02 0.33 1.35 75.30% 0.006
17 25 ppm Bromine 2.31 0.5 2.82 82.10%
Average 78.70%
18 75 ppm Bromine 2.5 0.51 3.01 83.10% 0.01
19 75 ppm Bromine 2.46 0.46 2.92 84.20%
Average 83.70%
Thus, in one embodiment, the present invention relates to various
methods that permit one to achieve a desired level of mercury control via oxidation of
elemental mercury in a flue gas, or combustion gas, stream as detailed herein while
simultaneously realizing a rate of corrosion in various AQCS devices and conduits that
is equal to or only slightly more than the rate of corrosion realized without injection of
one or more halogenco ntaining compounds for mercury oxidatio n. It should be
understood for the following discussion that although the differences in the corrosion
rates covered by the methods of the present invention when viewed in terms of
percentage difference, or percentage increase over baseline, show large numerical
increases such increases while seemingly large only translate into slight increase in the
real rate of corrosion expressed as mil per hour. Given this, the rates of corrosion
obtained by the various methods of the present invention will be expressed in numerical
values stated in mil per hour. In one embodiment the present invention achieves the
simultaneous oxidation of elemental mercury at one or more of the levels discussed
herein while also achieving a corrosion rate of between about 0.001 mil/hour to about
0.05 mil/hour, or between about 0.0015 mil/hour to about 0.045 mil/hour, or between
about 0.002 mil/hour to about 0.04 mil/hour, or between about 0.0025 mil/hour to about
0.035 mil/hour, or between about 0.003 mil/hour to about 0.03 mil/hour, or between
about 0.0035 mil/hour to about 0.025 mil/hour, or between about 0.004 mil/hour to about
0.02 mil/hour, or between about 0.0045 mil/hour to about 0.015 mil/hour, or between
about 0.005 mil/hour to about 0.01 mil/hour, or between about 0.0055 mil/hour to about
0.0095 mil/hour, or between about 0.006 mil/hour to about 0.009 mil/hour, or between
about 0.006 mil/hour to about 0.0085 mil/hour, or between about 0.0065 mil/hour to
about 0.008 mil/hour, or even between about 0.007 mil/hour to about 0.0075 mil/hour.
Here, as well as elsewhere in the specification and claims, individual range values can
be combined to form additional and/or nond isclosed ranges.
While specific embodiments of the present invention have been shown
and described in detail to illustrate the application and principles of the invention, it will
be understood that it is not intended that the present invention be limited thereto and
that the invention may be embodied otherwise without departing from such principles.
In some embodiments of the invention, certain features of the invention may sometimes
be used to advantage without a corresponding use of the other features. Accordingly,
all such changes and embodiments properly fall within the scope of the following claims.
Claims (61)
1. A method for oxidizing elemental mercury present in a flue gas, or combustion gas, stream wherein the method comprises the steps of: (I) burning at least one fuel so as to yield a mercuryco nt aining flue gas, or combustion gas, stream wherein at least a portion of the mercury in the mercuryco ntaining flue gas, or combustion gas, stream is eleme ntal mercury; (II) injecting one or more halogenco ntaining compounds into the mercuryco ntaining flue gas, or combustion gas, stream in order to oxidize at least a portion of the elemental mercury in the mercuryco ntaining f lue gas, or combustion gas, stream into oxidized mercury and form one or more corresponding mercury halide compounds; and (III) injecting one or more sulfurco ntaining compounds and /or sulfide salt compounds into at least one air quality control device in order to convert the one or more mercury halide compounds into one or more insoluble mercurysu lfur compounds.
2. The method of claim 1, wherein the at least one fuel is selected from at least one fossil fuel.
3. The method of claim 2, wherein the at least one fossil fuel is coal.
4. The method of claim 1, wherein the fuel is at least one biomass fuel.
5. The method of claim 1, wherein the fuel is a mixture of at least one fossil fuel and at least one biomass fuel.
6. The method of claim 1, wherein the one or more halogenc ontaining compounds are selected from one or more chlorineco ntaining compounds, one or more bromineco ntaining compounds, one or more iodineco ntainin g compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
7. The method of claim 6, wherein the one or more chlorinec ontaining compounds are selected from one or more inorganic chlorine compounds, organic chlorineco ntaining compounds, one or more diatomic chlorine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
8. The method of claim 6, wherein the one or more bromineco ntaining compounds are selected from one or more inorganic bromine compounds, organic bromineco ntaining compounds, one or more diatomic bromine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
9. The method of claim 6, wherein the one or more iodineco ntaining compounds are selected from one or more inorganic iodine compounds, organic iodine containing compounds, one or more diatomic iodine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
10. The method of claim 6, wherein the one or more halogenc ontaining compounds are selected from a combination of at least one chlorinec ontaining compound in combination with at least one bromineco ntai ning compound and in further combination with at least one iodineco ntaining compoun d.
11. The method of claim 6, wherein the one or more halogenc ontaining compounds are selected from any suitable combination of one or more alkalim etal halide compounds, one or more alkalim etal halogenco ntai ning compounds, one or more alkalie arth halogenco ntaining compounds, one or more compounds that contain at least two different halogens, one or more compounds that contain at least one halogen and oxygen, one or more compounds that contain at least one halogen and hydrogen, one or more diatomic halogenc ontaining compo unds, one or more organic compounds that contain therein at least one atom of chlorine, bromine, and/or iodine, or any combination of two or more thereof, or even all three thereof.
12. The method of claim 6, wherein the one or more halogenc ontaining compounds are selected from NaCl, NaBr, NaI, KCl, KBr, KI, NaClO2, NaClO3, NaClO4, NaBrO3, NaIO3, NaIO4, Na5IO6, Na3H2IO6, KClO, KClO3, KClO4, KBrO3, KIBr2, KIO3, KIO3•HIO3, KIO3•2HIO3, KIO4, KI3•½H2O, MgCl2, MgBr2, MgI2, CaCl2, CaBr2, CaI2, Ca(ClO ) , (CaClO ) , Ca(BrO ) , Ca(IO ) , BrCl, IBr, IBr , ICl, ICl , ClO , Cl O , Cl O, 3 2 4 2 3 2 3 2 3 3 2 2 7 2 ClO , Cl O , BrO , Br O, Br O , IO , I O , I O , I O , HCl, HClO , HClO , HBr, HBrO , 4 2 8 2 2 3 8 2 2 4 2 5 4 9 3 4 3 HI, HIO , Cl , Br , I , or any suitable combination of two or more thereof, three or more 3 2 2 2 thereof, four or more thereof, or even five or more thereof.
13. The method of claim 1, wherein the one or more sulfurco ntaining compounds and/or sulfide salt compounds are selected from sulfidic waste water, kraft caustic liquor, kraft carbonate liquor, potassium sulfide, sodium sulfide, sodium hydrogen sulfide (NaHS), thioacetamide, or any combination of two or more thereof, three of more thereof, four or more thereof, or even five or more thereof.
14. The method of claim 13, wherein the one or more sulfurco ntaining compounds and/or sulfide salt compounds are supplied as an aqueous solution.
15. The method of claim 1, wherein the one or more halogenc ontaining compounds are injected at a rate of between about 0.5 ppm to about 250 ppm based on the amount of mercury present in the fuel source.
16. The method of claim 1, wherein the one or more halogenc ontaining compounds are injected at a rate of between about 2.5 ppm to about 225 ppm based on the amount of mercury present in the fuel source.
17. The method of claim 1, wherein the one or more halogenc ontaining compounds are injected at a rate of between about 5 ppm to about 212.5 ppm based on the amount of mercury present in the fuel source.
18. The method of claim 1, wherein the one or more halogenc ontaining compounds are injected at a rate of between about 17.5 ppm to about 150 ppm based on the amount of mercury present in the fuel source.
19. The method of claim 1, wherein the one or more halogenc ontaining compounds are injected at a rate of between about 32.5 ppm to about 75 ppm based on the amount of mercury present in the fuel source.
20. The method of claim 1, wherein the at least about 50 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenco ntaining compounds.
21. The method of claim 1, wherein the at least about 75 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenco ntaining compounds.
22. The method of claim 1, wherein the at least about 85 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenco ntaining compounds.
23. The method of claim 1, wherein the at least about 90 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenco ntaining compounds.
24. The method of claim 1, wherein the at least about 95 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenco ntaining compounds.
25. The method of claim 1, wherein the at least about 97.5 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
26. The method of claim 1, wherein the at least about 98 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenco ntaining compounds.
27. The method of claim 1, wherein the corrosion rate of any metal material or conduit due to contact with the halogenco ntaining flue gas, or combustion gas, stream is between about 0.001 mil/hour to about 0.05 mil/hour.
28. The method of claim 1, wherein the corrosion rate of any metal material or conduit due to contact with the halogenco ntaining flue gas, or combustion gas, stream is between about 0.0015 mil/hour to about 0.045 mil/hour.
29. The method of claim 1, wherein the method further comprises at least one, or both, of the steps of: (IV) supplying at least one control device and one or more mercury sensing devices, or sensors, wherein the at least one control device is operatively connected to the one or more mercury sensing devices, or sensors, in order to provide data on at least one of: (i) oxidized mercury concentration level in the flue gas, or combustion gas, stream, (ii) elemental mercury concentration level in the flue gas, or combustion gas, stream, and/or (iii) mercury speciation levels in the flue gas, or combustion gas, stream; and (V) optionally using the data from Step (IV) to determine the amount of either one, or both, of: (a) the one or more halogenco n taining compounds that are injected in Step (II), and/or (b) the one or more sulfurco ntaining compounds and/or sulfide salt compounds that are injected in Step (III).
30. The method of claim 29, wherein Steps (IV) and (V) are performed in real time.
31. A method for oxidizing and capturing elemental mercury present in a flue gas, or combustion gas, stream wherein the method comprises the steps of: (A) burning at least one fuel so as to yield a mercuryco nta ining flue gas, or combustion gas, stream wherein at least a portion of the mercury in the mercuryco ntaining flue gas, or combustion gas, stream is eleme ntal mercury; (B) injecting one or more halogenco ntaining compounds in to the mercuryco ntaining flue gas, or combustion gas, stream in order to oxidize at least a portion of the elemental mercury in the mercuryco ntaining f lue gas, or combustion gas, stream into oxidized mercury and form one or more corresponding mercury halide compounds; (C) injecting one or more sulfurco ntaining compounds and/ or sulfide salt compounds into at least one air quality control device in order to convert the one or more mercury halide compounds into one or more insoluble mercurysu lfur compounds; (D) capturing the one or more insoluble mercurysu lfur compoun ds in at least one air quality control device and/or downstream process equipment device.
32. The method of claim 31, wherein the at least one fuel is selected from at least one fossil fuel.
33. The method of claim 32, wherein the at least one fossil fuel is coal.
34. The method of claim 31, wherein the fuel is at least one biomass fuel.
35. The method of claim 31, wherein the fuel is a mixture of at least one fossil fuel and at least one biomass fuel.
36. The method of claim 31, wherein the one or more halogenco ntaining compounds are selected from one or more chlorineco ntaining compounds, one or more bromineco ntaining compounds, one or more iodineco ntainin g compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
37. The method of claim 36, wherein the one or more chlorineco ntaining compounds are selected from one or more inorganic chlorine compounds, organic chlorineco ntaining compounds, one or more diatomic chlorine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
38. The method of claim 36, wherein the one or more bromineco ntaining compounds are selected from one or more inorganic bromine compounds, organic bromineco ntaining compounds, one or more diatomic bromine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
39. The method of claim 36, wherein the one or more iodineco ntaining compounds are selected from one or more inorganic iodine compounds, organic iodine containing compounds, one or more diatomic iodine compounds, or any combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
40. The method of claim 36, wherein the one or more halogenco ntaining compounds are selected from a combination of at least one chlorinec ontaining compound in combination with at least one bromineco ntai ning compound and in further combination with at least one iodineco ntaining compoun d.
41. The method of claim 36, wherein the one or more halogenco ntaining compounds are selected from any suitable combination of one or more alkalim etal halide compounds, one or more alkalim etal halogenco ntai ning compounds, one or more alkalie arth halogenco ntaining compounds, one or more compounds that contain at least two different halogens, one or more compounds that contain at least one halogen and oxygen, one or more compounds that contain at least one halogen and hydrogen, one or more diatomic halogenc ontaining compo unds, one or more organic compounds that contain therein at least one atom of chlorine, bromine, and/or iodine, or any combination of two or more thereof, or even all three thereof.
42. The method of claim 36, wherein the one or more halogenco ntaining compounds are selected from NaCl, NaBr, NaI, KCl, KBr, KI, NaClO2, NaClO3, NaClO4, NaBrO , NaIO , NaIO , Na IO , Na H IO , KClO, KClO , KClO , KBrO , KIBr , KIO , 3 3 4 5 6 3 2 6 3 4 3 2 3 KIO •HIO , KIO •2HIO , KIO , KI •½H O, MgCl , MgBr , MgI , CaCl , CaBr , CaI , 3 3 3 3 4 3 2 2 2 2 2 2 2 Ca(ClO ) , (CaClO ) , Ca(BrO ) , Ca(IO ) , BrCl, IBr, IBr , ICl, ICl , ClO , Cl O , Cl O, 3 2 4 2 3 2 3 2 3 3 2 2 7 2 ClO4, Cl2O8, BrO2, Br2O, Br3O8, IO2, I2O4, I2O5, I4O9, HCl, HClO3, HClO4, HBr, HBrO3, HI, HIO3, Cl2, Br2, I2, or any suitable combination of two or more thereof, three or more thereof, four or more thereof, or even five or more thereof.
43. The method of claim 31, wherein the one or more sulfurco ntaining compounds and/or sulfide salt compounds are selected from sulfidic waste water, kraft caustic liquor, kraft carbonate liquor, potassium sulfide, sodium sulfide, sodium hydrogen sulfide (NaHS), thioacetamide, or any combination of two or more thereof, three of more thereof, four or more thereof, or even five or more thereof.
44. The method of claim 43, wherein the one or more sulfurco ntaining compounds and/or sulfide salt compounds are supplied as an aqueous solution.
45. The method of claim 31, wherein the one or more halogenco ntaining compounds are injected at a rate of between about 0.5 ppm to about 250 ppm based on the amount of mercury present in the fuel source.
46. The method of claim 31, wherein the one or more halogenco ntaining compounds are injected at a rate of between about 2.5 ppm to about 225 ppm based on the amount of mercury present in the fuel source.
47. The method of claim 31, wherein the one or more halogenco ntaining compounds are injected at a rate of between about 5 ppm to about 212.5 ppm based on the amount of mercury present in the fuel source.
48. The method of claim 31, wherein the one or more halogenco ntaining compounds are injected at a rate of between about 17.5 ppm to about 150 ppm based on the amount of mercury present in the fuel source.
49. The method of claim 31, wherein the one or more halogenco ntaining compounds are injected at a rate of between about 32.5 ppm to about 75 ppm based on the amount of mercury present in the fuel source.
50. The method of claim 31, wherein the at least about 50 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
51. The method of claim 31, wherein the at least about 75 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
52. The method of claim 31, wherein the at least about 85 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
53. The method of claim 31, wherein the at least about 90 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
54. The method of claim 31, wherein the at least about 95 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
55. The method of claim 31, wherein the at least about 97.5 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
56. The method of claim 31, wherein the at least about 98 weight percent of the elemental mercury in the flue gas, or combustion gas, stream is oxidized by the injection of the one or more halogenc ontaining compoun ds.
57. The method of claim 31, wherein the corrosion rate of any metal material or conduit due to contact with the halogenco ntaining fl ue gas, or combustion gas, stream is between about 0.001 mil/hour to about 0.05 mil/hour.
58. The method of claim 3, wherein the corrosion rate of any metal material or conduit due to contact with the halogenco ntaining flue gas, or combustion gas, stream is between about 0.0015 mil/hour to about 0.045 mil/hour.
59. The method of claim 31, wherein the method further comprises at least one, or both, of the steps of: (E) supplying at least one control device and one or more mercury sensing devices, or sensors, wherein the at least one control device is operatively connected to the one or more mercury sensing devices, or sensors, in order to provide data on at least one of: (i) oxidized mercury concentration level in the flue gas, or combustion gas, stream, (ii) elemental mercury concentration level in the flue gas, or combustion gas, stream, and/or (iii) mercury speciation levels in the flue gas, or combustion gas, stream; and (F) optionally using the data from Step (E) to determine the amount of either one, or both, of: (a) the one or more halogenco n taining compounds that are injected in Step (B), and/or (b) the one or more sulfurco n taining compounds and/or sulfide salt compounds that are injected in Step (C).
60. The method of claim 59, wherein Steps (E) and (F) are performed in real time.
61. The method of claim 31, wherein the at least one air quality control device is selected from a particulate control device selected from one or more of a fabric filter, a pulsej et fabric filter, a baghouse, a wet electrostatic precipitator, a dry electrostatic precipitator, or any suitable combination of two or more thereof. ABSTRACT The present invention relates generally to the field of emission control equipment for boilers, heaters, kilns, or other flue gas, or combustion gas, generating devices (e.g., those located at power plants, processing plants, etc.) and, in particular to a new and useful method and apparatus for capturing, oxidizing, lowering the concentration and/or level of, and/or eliminating mercury present in any flue gas and/or combustion gas stream. In one embodiment, the method and/or apparatus of the present invention is applied to boilers, heaters, kilns, or other flue gas, o r combustion gas, generating devices that have connected thereto at least one type of flue gas, or combustion gas, scrubber device (i.e., a wet scrubber or a dry scrubber). 28 16 TOWASTE DISPOSAL 402a 402b 402b TOWASTE DISPOSAL 1012 Halogen 1002 1006 1010 1014 1004 1008 1016 FIG. 5
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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US62/116,061 | 2015-02-13 | ||
US15/040,345 | 2016-02-10 |
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NZ716901A true NZ716901A (en) |
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