### US008303919B2



# (12) Ulllted States Patent (10) Patent N0.: US 8,303,919 B2 Gadgil et al. (45) Date of Patent: Nov. 6, 2012



## (54) SYSTEMANDMETHOD FOR PROTECTION 20027050059204 21* 11/200? ThubetlMk‘ 1 423/244 04

sy uevs 1yeta.

.. . 0F SCR CATALYST AND CONTROL OF 2005/0261122 A1 * 11/2005 Quesada Perez et al.

..... .. 502/80 MULTIPLE EMISSIONS 2007/0140940 A1 6/2007 Varma et al.
2007/0243996 A1 * 10/2007 Pujado

.......................... .. 502/38 (75) Inventors: Mandar R. Gadgil, Akron, OH (US); S. 2010/0273643 A1 10/2010 Gadgil et al. 

### Behrooz Ghorishi, UniontoWn, OH OTHER PUBLICATIONS 

### (US); Bryan J. Jankura, UniontoWn, OH (Us) W.A. Punjak et al.; Aluminosilicate Sorbents for Control ofAlkali Vapors during Coal Combustion and Gasi?cation; Energyand Fuels, (73) Assignee: Babcock & Wilcox Power Generation vol. 2(5), 1988, pp. 702 to 708. 

### Group, Inc,’ Barbertons OH (Us) W.A. Punjaketal.;High-TemperatureAdsorptionofAlkaliVaporson Solid Sorbents; AIChE Journal, vol. 35(7), Jul. 1989, pp. 1186 to ( * ) Notice: Subject to any disclaimer, the term ofthis 1194 patent is extended or adjusted under 35 M. Uberoi et al.; The Kinetics and Mechanism ofAlkali Removal from Flue Gas by Solid Sorbents; Progress in Energy and Combus USC‘ 1546)) by 0 days‘ tion Science, vol. 16(4), 1990, pp. 205 to 211.
M. Uberoi et al.; Aluminosilicates as Potential Sorbents for Control 

### (21) Appl' NO" 12/909’753 ling Metal Emissions; Clean Energy from Waste and Coal, ACS 22 F1 d‘ 0 t 21 2010 Symposium, 1992, pp. 214 to 222. ( ) 1 e ' c ‘ ’ P.O. MWabe et al.; Mechanisms Governing Trace Sodium Capture by

_ _ _ Kaolinite in a Down?ow; Twenty-Sixth Symposium (International) (65) Pnor Pubhcatlon Data on Combustion, The Combustion Institute, 1996, pp. 2447 to 2453. BM. Steenari et al.; High-Temperature Reactions of StrawAsh and Us 2012/0100052 A1 Apr' 26’ 2012 the Anti-Sintering Additives Kaolin and Dolomite; Biomass and (51) Int Cl Bioenergy, vol. 14(1), Mar. 1998, pp. 67 to 76. 

### B01D 53/46 (2006.01) (Continued) B01D 53/64 (2006.01) B01J 33/00 (2006.01) Primary Examiner * TimothyVanoy (52) U.S. Cl.

....... .. 423/210; 502/439; 502/520; 502/521 (74) Attorney, Agent, or Firm * Eric Marich (58) Field of Classi?cation Search

................ .. 423/210; 

### 502/439, 520, 521 (57) ABSTRACT See application ?le for Complete Search history- The present invention relates generally to the ?eld of emis

_ sioncontrol equipment forboilers, heaters, kilns, or other ?ue 

### (56) References Clted gas-, or combustion gas-, generating devices (e.g., those

4,061,716 4,572,085 4,843,980 4,871,522 4,925,633 5,540,897 5,567,394 US. PATENT DOCUMENTS 12/1977 2/1986 7/1989 10/1989 5/1990 7/1996 10/1996 

### Doyle Doyle McGauley Hepworth Markham et al.

Chu et al. Chu et al.

140 

## a 11

GOAL 1 1o PULV. 

### located at poWer plants, processing plants, etc.) and, in par ticular to a neW andusefulmethod and apparatus forprevent 

### ing thepoisoning and/orcontaminationofan SCRcatalyst. In 

### anotherembodiment, themethodandapparatus ofthepresent invention is designedto protect an SCR catalyst, While simul 

### taneously providing emission control.

26 Claims, 1 Drawing Sheet

20

## US 8,303,919 B2 Page 2

OTHER PUBLICATIONS

S .Q. Turn et al.; A Review ofSorbent Materrials for FixedBedAlkali Getter Systems in Biomass Gasi?er Combined Cycle Power Genera tion Applications; Journal of the Institute of Energy, vol. 71, Dec. 1998, pp. 163 to 177. SB. Davis et al.; Competition for Sodium andToxic Metals Capture
on Sorbents; Aerosol Science andTechnology, vol. 32(2), Feb. 2000,
pp. 142 to 151. M. Ohman et al.; The Role ofKaolin in Prevention ofBedAgglom erationduring FluidiZedBedCombustion ofBiomasss Fuels; Energy & Fuels, vol. 14, 2000, pp. 618 to 624. V. V. Lissianski et al.; Utilization of Iron Additives for Advanced Control of NOx Emissions from Stationary Combustion Sources; Ind. Eng. Chem. Res. 2001 (published on the Internet on Jun. 22, 2001), 40, pp. 3287 to 3293. SQ. Turn et al.; An Experimental Investigation ofAlkali Removal fromBiomass Producer GasUsing aFixedBedofSolid Sorbent; Ind. Eng. Chem. Res., vol. 40, 2001, pp. 1960 to 1967. T.K. Gale et al.; High-Temperature Interactions Between Multiple Metals and Kaolin; Combustion and Flame vol. 131 (3), Nov. 2002,
pp. 299 to 307. T.K. Gale et al.; Mechanisms and Models Describing Sodium and Lead ScavengingbyaKaoliniteAerosolatHighTemperatures;Aero sol Science and Technology, vol. 37, 2003, pp. 865 to 876. T. Ake et al.; Limestone Injection for Protection of SCR Catalyst; Riley Power, Duke Energy, Cormetech, Inc. Paper #175, 2003. K.Q. Tran et al.; On the Application of Surface Ionization Detector for the Study ofAlkali Capture by Kaolin in a Fixed Bed Reactor; Fuel, vol. 83(718), May 2004, pp. 807-812. Q.K. Tran et al.; Capture of Potassium and Cadmium by Kaolin in 

### OxidiZing and Reducing Atmospheres; Energy & Fuels, vol. 18, 2004, pp. 1870 to 1876. K.Q. Tran et al.; A Kinetic Study of Gaseous Alkali Capture by Kaolin in the Fixed Bed Reactor Equipped with an Alkali Detector; Fuel, vol. 84(2/3), Jan/Feb. 2005, pp. 807-812. V. Kroger; Poisoning ofAutomotive Exhaust Gas Catalyst Compo nentsiThe Role of Phosphorus in the Poisoning Phenomena; Aca demic Dissertation, University ofOulu, Finlandi2007. B. Jens etal.; The Behavior ofParticle BoundPhosphorus Duringthe 

### Combustion of Phosphate Doped Coal; Fuel, 86, 2007 (available online Sep. 27, 2006), pp. 632 to 640. E. Matinde et al.; Phosphorus Gasi?cation from Sewage Sludge During Carbothermic Reduction; ISIJ International, vol. 48, 2008, No. 7, pp. 912 to 917. A. Tate et al.; Environmentally Sound Handling ofDeactivated SCR Catalyst; Downloaded from the Internet on May 13, 2009 at http:// www.coalpowermag.com/environmenta1/136 .html.

* cited by examiner

## US 8,303,919 B2 1
SYSTEMAND METHOD FOR PROTECTION

OF SCR CATALYSTAND CONTROL OF MULTIPLE EMISSIONS

FIELDAND BACKGROUND OF THE INVENTION

1. Field ofthe Invention 

### Thepresent inventionrelates generally to the ?eld ofemis 

### sioncontrol equipment forboilers,heaters, kilns, orother ?ue gas-, or combustion gas-, generating devices (e.g., those 

### located at poWer plants, processing plants, etc.) and, in par ticularto aneW andusefulmethod and apparatus forreducing

or preventing the poisoning and/or contamination ofan SCR 

### catalyst. Inanotherembodiment, themethodandapparatus of 

### the present invention is designed to protect the SCR catalyst.

2. Description ofthe RelatedArt NO,C refers to the cumulative emissions of nitric oxide 

### (NO), nitrogen dioxide (N02) and trace quantities of other 

### nitrogen oxide species generated during combustion. Com bustion ofany fossil fuel generates some level ofNO,C due to 

### hightemperatures andthe availability ofoxygenandnitrogen fromboth the air and fuel. NO,C emissions may be controlled 

### using loW NO,C combustion technology andpost-combustion techniques. One such post-combustion technique involves selective catalytic reduction (SCR) systems in Which a cata lyst facilitates a chemicalreactionbetWeenNO,Candareagent 

### (usually ammonia) to produce molecular nitrogen and Water vapor. 

### SCR technology is used WorldWide to control NO,C emis sions from combustion sources. This technology has been 

### usedWidely inJapanforNO,Ccontrol fromutilityboilers since the late 1970’s, in Germany since the late 1980’s, and in the US since the 1990’s. Industrial scale SCRs have been 

### designed to operate principally in the temperature range of 500° F. to 900° F., but most often in the range of 550° F. to 750° F. SCRs are typically designed to meet a speci?edNO,C reduction e?iciency at a maximum alloWable ammonia slip. 

### Ammonia slip is the concentration, expressed in parts per million by volume, ofunreacted ammonia exiting the SCR.

For additional details concerning NO,C removal technolo 

### gies used in the industrial and poWer generation industries, the reader is referred to Steam/its generation and use, 41“ 

### Edition, Kitto andStultZ, Eds., Copyright 2005, TheBabcock 

### & Wilcox Company, Barberton, Ohio, U.S.A., particularly Chapter 34iNitrogen Oxides Control, the text ofWhich is 

### hereby incorporated by reference as though fully set forth herein.



### Regulations issued by the EPA promise to increase the portion ofutility boilers equippedWith SCRs. SCRs are gen 

### erallydesigned foramaximum e?iciency ofabout 90%. This limit is not set by any theoretical limits on the capability of 

### SCRs to achievehigher levels ofNO,Cdestruction. Rather, itis

a practical limit set to prevent excessive levels of ammonia 

### slip. This problem is explained as folloWs.

In an SCR, ammonia reacts With NO,C according to one or 

### more ofthe folloWing stoichiometric reactions (a) to (d):

The above catalysis reactions occur using a suitable cata 

### lyst. Suitable catalysts arediscussedin, forexample,US. Pat. 20

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## 2
Nos. 5,540,897; 5,567,394; and 5,585,081 to Chu etal., all of 

### Which are hereby incorporated by reference as though fully set forthherein. Catalyst formulations generally fall into one 

### ofthree categories: base metal, Zeolite andprecious metal.

Base metal catalysts use titanium oxide With small amounts ofvanadium, molybdenum, tungsten or a combina tion of several other active chemical agents. The base metal 

### catalysts are selective and operate in the speci?ed tempera ture range. The major draWback ofthe base metal catalyst is 

### its potential to oxidiZe SO2 to S03; the degree of oxidation variesbased on catalyst chemical formulation. The quantities of SO3 Which are formed can react With the ammonia carry
over to form various ammonium-sulfate salts.

Zeolite catalysts are aluminosilicatematerials Which func 

### tion similarlytobasemetal catalysts. Onepotentialadvantage 

### of Zeolite catalysts is their higher operating temperature of about 9700 F. (5210 C.). These catalysts can also oxidiZe SO2 to S03 and must be carefully matched to the ?ue gas condi tions.



### Precious metal catalysts are generally manufactured from 

### platinum and rhodium. Precious metal catalysts also require careful consideration of ?ue gas constituents and operating 

### temperatures. While effective in reducing NOX, these cata lysts canalso actas oxidiZingcatalysts, converting COto CO2 

### under proper temperature conditions. HoWever, SO2 oxida tionto S03 andhighmaterial costs oftenmakepreciousmetal 

### catalysts less attractive.

As is knoWn to those of skill in the art, various SCR cata 

### lysts undergo poisoning Whenthey become contaminatedby various compounds including, but not limited to, certain phosphorus compounds such as phosphorous oxide (P0) or 

### phosphorous pentoxide (P205). Additionally, certain com pounds that contain potassium (K), sodium (Na) and phos phorous (P) that are found in, or generated by, various coal based fuels are knoWn to cause rapid deactivation of SCR 

### catalyst in full-scale units and also in slip-stream units. In these fuels, potassium and sodium are mainly in the form of 

### organically bonded inorganics, or Water soluble salts, (see, e.g., Steenari et al.; Energy and Fuels; Vol. 18 (2004) 6, pp. 1870 to 1876). This form of association in the fuel makes it 

### very easy forpotassium and sodium to vaporiZe during com bustion. Phosphorus canalso be contained inthe fuel Where it 

### is organically bonded (as in the case inbiomass) or inorgani 

### cally bonded (as is the case in PoWder River Basin (PRB) 

### coal). Phosphorus is released in the gas phase due to carbo 

### ther'mic reduction reaction happening during char combus tion as folloWs:



### (see, e.g., Hino, et. al.;lSlJlnlernali0nal,Vol. 48 (2008)7,pp. 912 to 917). Ofparticular concernWithbiomass, phosphorus is released in the gas phase as a result of the combustion 

### process itselfirrespectiveofWhetherthecombustionis staged


### orun-staged sincephosphorus is organically associatedWith/ in the fuel.

More particularly, as the SCR catalysts are exposed to the dust laden ?ue gas there are numerousmechanisms including 

### blinding, masking andpoisoning thatdeactivates the catalyst and causes adecrease inthe catalyst’s performance overtime. Themost common catalystpoisonencounteredWhenburning eastern domestic coal (i.e., coal mined in the eastern United States) is arsenic. Themost common catalystpoison encoun 

### teredWhenburningWesterndomestic coal (i.e., coalmined in 

### the WesternUnited States) is phosphorus and calcium sulfate is the most commonmasking mechanism. Themost common 

### catalystpoisons encounteredWhenburningbiomass aretypi

## US 8,303,9l9 B2 3 cally potassium and sodium, orpotassium- and sodium-con taining compounds. One method ofrecycling the used cata lyst is the process called regeneration Washing or 

### rejuvenation. The initial steps of the regeneration process involve the removal of these toxic chemicals by processing the catalysts through various chemical baths in Which the poisons are soluble. While this treatment process does an 

### excellent job of removing the desired poisons it produces WasteWater With very high arsenic concentrations.

Furthermore, as is knoWn to those of skill in the art, selec 

### tive catalyst reduction (SCR) technology is used WorldWide to control NO,C emissions from combustion sources at high 

### temperatures (550° F. to 750° F). High temperature SCR technology has been used in Japan for NO,C control from utility boilers since the late 1970s, in Germany since the late l980’s, in US since the 1990’s and in China since 2000. The function of the SCR system is to react NO,C With ammonia (NH3) and oxygento formmolecularnitrogenandWater. Due 

### to anticipated requirements for loWer NO,C emission limits there is a groWingneedto control NO,Cemissions from lignite 

### ?red coal poWer plants in the US and Canada. Some lignite ?red units are already in the process of retro?tting SCR to control NOX. Other units Will have to folloW suit in the near future. There is also an increasing trend to co-combust coal and biomass on existing units With or Without SCR. Some 

### older units are completely sWitching from pulveriZed coal ?ring to pulverized biomass combustion. These units even With biomass alone or With coal and biomass co-combustion 

### Will have to comply With strict NO,C emissions. The most 

### effective method of complying With loW NO,C emission 

### requirements isby SCRtechnology.Themain issueWith SCR performance onthese units is the deactivation ofthe catalyst. 

### Both lignite and biomass fuels have potassium, sodium and 

### phosphorous and/orvariouspotassium, sodiumandphospho

rous compounds Which are knoWn catalyst poisons. These 

### poisons attack the catalyst resulting in deactivation of the catalyst over a period of time, thereby shortening the cata lyst’s active life cycle. As a result of the deactivation, the catalyst cannot function to carry out NO,C reduction as effec 

### tively for a longerperiod oftime. Giventhis, the deactivation reduces the effective life cycle of a catalyst and as a result


### more frequent catalyst changes are needed for NO,C compli

ance. Although, there are some catalyst vendors that claim resistance to arsenic poisoning oftheir catalystsvia the use of 

### molybdenum in the catalyst formulation, to date no catalyst 

### have been brought to market that resist poisoning by various 

### potassium, sodium and phosphorous compounds, their elemental species, or their ionic species.



### Additionally, beyond controlling NO,C emissions, other emission controls must be considered and/or met in order to 

### comply Withvarious state, EPA and/or CleanAirAct regula tions. Some other emission controls Whichneed to be consid ered forboilers, heaters, kilns, or other ?ue gas-, or combus 

### tion gas-, generating devices (e.g., those located at poWer 

### plants, processingplants, etc.) include, but arenot limited to, 

### mercury, SOX, and certainparticulates.

Given the above, a need exists for a method that provides for an economical and environmentally suitable method and/

or system to remove the gaseous potassium, sodium and 

### phosphorous compounds, their elemental species, or their ionic species from a combustion process prior to any phos 

### phorus compounds poisoning a catalyst in an SCR.

SUMMARY OF THE INVENTION



### Thepresent inventionrelates generally to the ?eld ofemis 

### sioncontrol equipment forboilers,heaters, kilns, orother ?ue 20

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## 4
gas-, or combustion gas-, generating devices (e.g., those 

### located at poWer plants, processing plants, etc.) and, in par ticularto aneW andusefulmethod and apparatus forreducing

or preventing the poisoning and/or contamination ofan SCR 

### catalyst. Inanotherembodiment, themethodandapparatus of the present invention is designed to protect an SCR catalyst.

Accordingly, one aspect ofthe present invention is draWn to a method for increasing the active life of an SCR catalyst, 

### themethod comprising the steps of: (a)providing at least one kaolin-bearing compound to a combustion Zone or ?ue gas stream ofa fumace, orboiler, priorto entry ofthe ?ue gas into


### an SCR; and (b) permitting the at least one kaolin-bearing 

### compound to react With any gaseous potassium and/or 

### sodium compounds, orpotassium- and/or sodium-containing compoundspresent inthe combustion Zone or ?ue gaspriorto the entry ofthe ?ue gas into the SCR.



### In yet another aspect of the present invention, there is provided a method for increasing the active life of an SCR 

### catalyst, the method comprising the steps of: (i) providing at least one kaolin-bearing compound to a combustion Zone ofa furnace or boiler; and (ii) permitting the at least one kaolin 

### bearing compound to react With any gaseous potassium and/

or sodium compounds, orpotassium- and/or sodium-contain 

### ing compounds present in the combustion Zone prior to the entry ofthe ?ue gas into an SCR, Wherein the kaolin-bearing compound is selected from one or more kaolin-containing 

### clays, kaolinite-containing clays, kaolinite, or mixtures of

tWo or more thereof.



### In yet another aspect of the present invention, there is provided a method for sequestering one or more potassium 

### and/or sodium compounds, or potassium- and/or sodium containing compounds, in the form ofone ormore less reac 

### tive sodium aluminosilicate-containing, orpotassium alumi 

### nosilicate-containing, compounds, the method comprising the steps of: (A) providing at least one kaolin-bearing com pound to a combustion Zone or ?ue gas stream ofa furnace, or 

### boiler; and (B) permitting the at least one kaolin-bearing compound to react With any potassium and/or sodium com 

### pounds, orpotassium- and/or sodium-containing compounds present in the combustion Zone or ?ue gas to form one ormore less reactive sodium aluminosilicate or potassium alumino 

### silicate compounds.

In yet another aspect of the present invention, there is provided a method for increasing the active life of an SCR 

### catalyst While concurrently controlling mercury in a gas, the 

### method comprising the steps of: (I) providing at least one kaolin-bearing compound to a combustion Zone or ?ue gas stream ofa fumace, orboiler, priorto entry ofthe ?ue gas into
an SCR; (II) providing at least one iron-bearing halide com pound to a combustion Zone or ?ue gas stream ofa furnace, or 

### boiler, prior to entry ofthe ?ue gas into an SCR; (III) permit ting the kaolin portion of the at least one kaolin-bearing compound to react With any gaseous potassium and/or 

### sodium compounds, orpotassium- and/or sodium-containing compoundspresent inthe combustion Zone or ?ue gaspriorto 

### the entry ofthe ?ue gas into the SCR; (IV) permittingthe iron portion of the at least one iron-bearing halide compound to 

### react With any gaseous phosphorus compounds, or phospho rus-containing compounds present in the combustion Zone or 

### ?ue gaspriorto the entry ofthe ?ue gas into the SCR; and (V) permitting the halide portion ofthe at least one iron-bearing halide compound to react With any gaseous mercury com 

### pounds, or mercury-containing compounds, present in the combustion Zone or ?ue gas.



### In yet another aspect of the present invention, there is provided a method for sequestering one or more potassium 

### and/or sodium compounds, or potassium- and/or sodium

## US 8,303,919 B2 5 containing compounds, in the form ofone or more less reac 

### tive sodium aluminosilicate-containing, orpotassium alumi nosilicate-containing, compounds, as Well as sequestering

one ormore phosphorus compounds, orphosphorus-contain ing compounds, in the form of one or more less reactive 

### iron-phosphorus-containing compounds While concurrently sequesteringmercury, themethodcomprisingthe stepsof: (1) providing at least onekaolin-bearing compoundto a combus tion Zone or ?ue gas stream of a furnace, or boiler; (2) pro viding at least one iron-bearing halide compound to a com bustion Zone or ?ue gas stream of a furnace, or boiler; (3) permitting the kaolin portion ofthe at least one kaolin-bear 

### ing compound to react With any gaseous potassium and/or sodium compounds, orpotassium- and/or sodium-containing compounds present inthe combustion Zone or ?ue gas to form

one ormore less reactive sodium aluminosilicate-containing, 

### or potassium aluminosilicate-containing, compounds; (4) permitting the iron portion of the at least one iron-bearing halide compound to react With any gaseous phosphorus com 

### pounds, orphosphorus-containing compounds,present inthe combustion Zone or ?ue gas to form one ormore less reactive 

### iron-phosphorus-containing compounds; and (5) permitting the halide portion of the at least one iron-bearing halide compound to react With any gaseous mercury compounds, or 

### mercury-containing compounds, present in the combustion

Zone or ?ue gas.



### The various features of novelty Which characteriZe the invention are pointed out With particularity in the claims annexed to and forming a part ofthis disclosure. For a better 

### understanding ofthe invention, its operating advantages and speci?c bene?ts attainedby its uses, reference is made to the 

### accompanying draWings and descriptive matter in Which exemplary embodiments ofthe invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

The sole FIGURE is a schematic representation ofatypical 

### fossil fuel burning facility With an SCR system, and Which includes a system for practicing the methods of the present invention.

DESCRIPTION OF THE INVENTION

While the present invention Will be described in terms of SCR systemsWhichuse ammonia as theNO,Creducing agent, 

### since ammonia is frequently preferred for economic reasons, the present invention is not limited to ammonia based sys tems. The concepts ofthepresent inventioncanbeused in any system Whichuses an ammoniacal compound.As used in the present disclosure, an ammoniacal compound is a termmeant to include compounds such as urea, ammonium sulfate, cya nuric acid, and organic amines as Well as ammonia (NH3). 

### These compounds could be used as reducing agents in addi tion to ammonia, but as mentioned above, ammonia is fre quently preferred for economic reasons. Some non-ammo niacal compounds such as carbon monoxide or methane can be used as Well, but With loss in effectiveness.



### As used herein, the terms “-bearing compound(s)” and 

### “-containing compound(s)” are used interchangeably. For example, the terms “kaolin-bearing compoun ” and “kaolin containing compound” are to be construed as the same and as noted above are utiliZed interchangeably.As Would be appar 

### ent, this distinctionapplies equally to all terms thatutiliZe the

same constructs noted herein. Additionally, as used herein, the term “gas phase” includes and/or encompasses both a compound, or compounds, in a gaseous state as Well as the

same compound, or compounds, in an aerosol state. Also, as 20

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## 6 used herein, the term “species” includes both a compound and/or an element in an ionic form/state as Well as a com pound and/or an element in a atomic form/state.

Although the present invention is described in relation to a boiler, or a fossil fuel boiler, it is not limited solely thereto. Instead, the present invention can be applied to any combus tion source that generates NO,C regardless ofWhether such a combustion source is utiliZed in conjunction With a boiler, or a steam generator. For example, the present invention could beused in combinationWith a kiln, aheater, or any other type of combustion process that generates, in Whole or in part, a 

### ?ue gas or combustion gas containing NOX.Accordingly, the description beloW is to be construed as merely exemplary.

As illustrated inthe FIGURE, thepresent inventionmaybe applied to a boiler installation Which employs a Wet ?ue gas desulfuriZation (WFGD orWet scrubber) for removal of sul fur oxides from the ?ue gases, as shoWn in the upper right hand side of the FIGURE. In this con?guration, the Wet 

### scrubber is typically preceded (With respect to a direction of 

### ?ue gas ?oW through the system) by a particulate collection 

### device (PCD), advantageously a fabric ?lter (FF) bag house,

or an electrostatic precipitator (ESP). If desired, there may also be provided a Wet electrostatic precipitator (Wet ESP or 

### WESP) Which may be provided as a ?nal “polishing” stage 

### for ?ne particulate or SO3. Alternatively, the present inven tionmaybe applied to a system Which employs a spray dryer 

### apparatus (SDA) ordry scrubber forremoval ofsulfuroxides from the ?ue gases, as shoWn in the loWer right-hand side of the FIGURE. Inthis con?guration, the SDAordry scrubberis typically folloWed (Withrespect to a direction of?ue gas ?oW 

### throughthe system)by aparticulate collectiondevice (PCD), advantageously a fabric ?lter or baghouse, an electro static precipitator (ESP) or even a Wet electrostatic precipita 

### tor (Wet ESP).

Additionally, the present invention can be applied to any 

### SCR catalyst that is adversely affected by poisoning With a phosphorus-based compound such as, but not limited to, 

### H3PO4, PO or P2O5, potassium-based compounds such as, 

### butnot limitedto,potassiumchloride (KCl) and/orpotassium sulfate (K2SO4), and/or sodium-based compounds such as, but not limited to, sodium chloride (NaCl) and/or sodium 

### sulfate (Na2SO4).As such, thepresent inventionisnot limited to any one type of SCR catalyst, but rather is broadly appli cable to a Wide range of SCR catalyst systems. Suitable 

### catalyst systems forWhichthepresent invention is applicable include, but are not limited to, honeycomb, plate or corru 

### gated type con?gurations.

In one embodiment, the present invention is directed to reducing the rate of SCR catalyst deactivation on PoWder 

### River Basin (PRB) coal combustionunits. It shouldbe noted 

### that although the present invention is described in relation to 

### PRB coal, thepresent inventionisnot limitedthereto. Rather, 

### the present invention is broadly applicable to any situation Where an SCR catalyst is poisoned by one or more gaseous phosphorus compounds, one or more gaseous potassium compounds, one ormore gaseous sodium compounds, and/or any combination of tWo or more of such compounds.



### Inone embodiment, phosphorous in PRB coal is suspected to cause rapid deactivation in staged combustion and other 

### units.This deactivationis suspectedtobe causedbygasphase phosphorus released via carbothermic reduction reaction. In 

### this reactionunder oxygen de?cient conditions, phosphorus 

### bearing compounds release gas phasephosphorus by the fol loWing reaction:

P2O5(solidphase compounds)+3C(s)—>2PO(g)+ 3CO(g).

## US 8,303,919 B2 7 This gas phase phosphorous attaches to the active sites 

### Within the catalyst causing the deactivation of the sites for NO,C reduction. As a result ofthis deactivation the SCR cata lyst cannot carry out the NO,C reduction process to the same 

### performance level as unused catalyst.



### In another embodiment, potassium, sodium, potassium containing compounds, and/or sodium-containing com pounds in PRB coal and/orbiomass is/are suspected to cause 

### rapid deactivation in staged combustion and other units. While not Wishing to be bound to any one theory, this deac 

### tivation is suspected to be caused by gas phase potassium and/or sodium released via the combustion process due to 

### presence ofvarious potassium and/or sodium compounds in the coal and/or biomass. In this situation, the release of such alkali metal ions and/or atoms occurs due to the temperatures utiliZedto conduct combustionofthe coal and/orbiomass and 

### the subsequent vaporization and/or dissociation ofthe afore 

### mentionedpotassium and/or sodium compounds.

This gasphasepotassium and/or sodium ions and/oratoms attach to the active sites Within the catalyst causing the deac tivation of such sites for NO,C reduction. As a result of this 

### deactivation, the SCR catalyst cannot carry out the NO,C reduction process to the same performance level as unused and/or “fresh” catalyst.

In one embodiment, the present invention relates to a sys 

### tem andmethodto prevent formation ofgasphasepotassium, 

### sodium and/or phosphorus species in the combustion envi ronment thus reducing, mitigating and/or eliminating therate of SCR deactivation. In one embodiment, the present inven 

### tionaccomplishes the aforementionedgoalby theaddition of at least one kaolin-bearing compound, at least iron-bearing compound, or any suitable combination thereof to the PRB 

### coal prior to combustion.



### Inoneembodiment, thekaolin-bearing compound(s) ofthe 

### present invention is/are any kaolin-containing compound (e.g., kaolinite Which is a mineral that is contained in kaolin 

### clays and Which has a chemical composition of Al2Si2O5 (OH)4). Accordingly, as used herein, “kaolin” is de?ned to mean, and encompass, any clay that contains a suf?cient amount of kaolin therein (e.g., any clay that is at least 25 

### Weight percent kaolin), or any clay or other compound that contains a suf?cient amount of the mineral kaolinite 

### (Al2Si2O5 (OH)4) (e.g., any clay, orothercompound, that is at 

### least 25 Weight percent kaolinite). In another embodiment, the amount of kaolin in kaolin-containing compound is at 

### least about 30 Weight percent, at least about 40 Weight per cent, at least about 50Weightpercent, at least about 60Weight percent, at least about 70 Weight percent, at least about 75 

### Weightpercent, at leastabout 80Weightpercent, at leastabout 90Weightpercent, or evenat least about 95 Weightpercent. In 

### still another embodiment, any kaolin-containing compound regardless of kaolin content can be utiliZed in conjunction With the present invention so long as the kaolin content thereof is at least about 10 Weight percent. Here, as Well as 

### elseWhere in the speci?cation and claims, individual range values can be combined to form additional and/or non-dis closed ranges. While not Wishing to be bound to any one 

### theory, it is believed that the aluminosilicate portion of the kaolin reacts With “free” potassium and/or sodium ions that

are generated due to the combustion of coal and/or biomass 

### that contains various potassium, sodium and/orphosphorous 

### compounds to generate potassium and/or sodium alumino 

### silicate compounds (e.g., NaAlSi3O8 andKAlSi3O8). This in turnpermits the sequestrationofthepotassiumand/or sodium ions and/or atoms that Would otherWise be “free” to poison 

### the SCR catalyst. 20

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## 8 Regarding anyphosphorous compounds thatare contained in the combustiongases, such compounds are sequesteredvia the inclusion ofone ormore iron-bearing compounds in com bination With a kaolin-bearing compound as de?ned above. 

### Thus, in one embodiment, the present invention enables the 

### sequestration of multiple species selected from potassium, sodium, phosphorus and any combination thereof.

In one embodiment, the iron-bearing compound(s) ofthe present invention is/are any iron compound (e.g., an iron 

### oxide compound) that is/are able to undergo reduction in the combustion environments common to boilers, furnaces, 

### poWer plants, etc. In one particular embodiment, the iron 

### bearing compound is iron (III) oxide (Fe2O3), also knoWn as red iron oxide orhematite. Inthe embodimentWhere iron (III) oxide is utiliZed the reactions of interest that occur in the combustionportion ofaboiler or furnace are as shoWnbeloW:

It shouldbe noted that the Fe3O4, also knoWn as black iron oxide or magnetite, of the ?rst reaction above can also be Written more accurately as FeO.Fe2O3. The FeO or iron (II) oxide, also knoWn as ferrous oxide, Which is generated due to 

### the reduction ofFe2O3 is then available to tie-up, bind and/or sequester any PO gas present in the combustion Zone, or the ?ue gas, of a boiler, or fumace, prior to arrival at the SCR. This PO gas Will then form FeiP and/or FeiP4O com 

### pounds in particulate phase prior to arrival at the SCR. The particulate Will pass through the catalyst and avoid the cata 

### lyst deterioration.

In another embodiment, the present invention can utilize 

### iron (II) carbonate Which is converted to the desired iron (II) oxide in the combustion Zone via the reaction shoWn beloW:

In still another embodiment, the present invention can uti liZe one or more iron halides. Suitable iron halides include, 

### but are not limited to, iron (II) bromide, iron (III) bromide, 

### iron (II) chloride, iron (III) chloride, iron (II) iodide, iron (III) iodate (Fe(IO3)3), or any mixture of tWo or more thereof. In still another embodiment, any one ormore ironhalides canbe 

### used in combinationWith anothernon-halide containing iron 

### compound (e.g., iron (II) carbonate). In still another embodi ment, thepresent inventionutiliZes a combination ofiron (II) 

### bromide and/or iron (III) bromide With iron (II) carbonate to control the amount ofphosphorous in a ?ue gas, or combus 

### tion gas While concurrentlypermittingthe control ofmercury compounds, ormercury-containing compounds, in a ?ue gas,
or combustion gas. As used herein, mercury compounds, or 

### mercury-containing compounds, include, but are not limited to, any compound that contains either oxidiZed mercury, or bound elemental mercury. In still another embodiment, the 

### present invention is directed to concurrently permitting the control ofmercury compounds, ormercury-containing com 

### pounds, that containprimarily, or only, oxidiZedmercury. As used herein any iron compound, halide or otherwise, can be utiliZed in a hydrated or non hydrated form. As such, refer
ence to any iron compound herein by de?nition includes any hydrated forms that exist Whether or not speci?cally men 

### tioned by chemical formula.

As is knoWn in the art, (see, e.g., United States Patent Application Publication No. 2008/0107579 DoWns et al. the 

### text ofWhich is hereby incorporated by reference as though 

### fully set forth herein) halide-containing compounds are uti liZed to oxidiZe elemental mercury present in a ?ue, or com 

### bustion, gas. Due to this oxidationreaction, thehalideportion

## US 8,303,919 B2 9 ofa suitable halide-containing compoundpermits elemental
mercury to be converted into a more favorable form for sub sequent capture, or sequestration, via one or more suitable environmental control technologies (e.g., a Wet scrubber or 

### spray dry absorber (SDA), a ?ue gas desulfuriZation system (FGD), a poWdered activated carbon system (PAC), or a par ticulate collecting system such as a fabric ?lter (FF) or a electrostatic precipitator (ESP)). In one instance, as is knoWn in the art, the addition ofone ormore suitable halide-contain 

### ing compounds also increases the amount ofmercury that is 

### particulate-bound. Given that numerous patents and pub lished applications detail the manner by Which suitable 

### halide-containing compounds permit the increased recovery ofmercury from a ?ue, or combustion, gas, a detailed discus 

### sion hereofis omitted for the sake ofbrevity.



### As such, in still anotherembodiment, thepresent invention encompasses utiliZing at least one kaolin-bearing compound in conjunctionWithat least one ironhalide compoundinorder to achieve amulti-faceted control ofvarious gas phasepotas 

### sium, sodium, phosphorus and mercury compounds, ions and/or atoms, as discussed above.

In any of the above embodiments, one or more suitable kaolin-bearing compounds, one ormore suitable iron-bearing compounds, one or more suitable iron halide compounds, or anymixture thereofcanbe added to the coal inthepulveriZer.
In still another embodiment, one or more suitable kaolin bearing compounds, one or more suitable iron-bearing com pounds, one or more suitable iron halide compounds, or any mixture thereof of the present invention can be added to the combustion Zone of a boiler and/or furnace via a suitable supply line designed to deliver one ormore poWderiZed com pounds to the combustion Zone ofa furnace and/or boiler. To this end, the FIGURE illustrates several embodiments of 

### suitable design schemes for accomplishing this result.

Referring to the FIGURE, there is illustrated a schematic 

### representation ofa typical fossil fuel burning facility, gener ally designated 10, With an SCR system, andWhich includes
a system forpracticing the methods ofthe present invention. 

### As shoWn, boiler 12 is provided for extracting the heat from the combustion of a fossil fuel, such as coal, through com bustion With an oxidant, typically air. The heat is transferred to a Working ?uid, such as Water, to generate steam used to 

### either generate poWer via expansion through a turbine gen erator apparatus (not shoWn) or for industrial processes and/
or heating.

The raW coal 14 must be crushed to a desired ?neness and dried to facilitate combustion. RaW coal 14 is temporarily stored in a coal bunker 16 and then transferred by means ofa gravimetric or volumetric feeder 18 to one or more coal 

### pulveriZers 20. In the embodiment shoWn in the FIGURE, there are six (6) coalpulveriZers, identi?edas coalpulveriZers A-F. As is knoWn to those skilled in the art, each coal pulver iZer 20 grinds the coal to adesired ?neness (e.g., 70% through 

### 200mesh) andas itis ground,hotprimaryairfromprimaryair 

### fans (not shoWn) is conveyed into each coal pulveriZer 20 to preheat andremovemoisture fromthe coal to desired levels as 

### it is ground. The primary air is also used to convey the pul veriZed coal (PC) out ofeach coal pulveriZer 20 and delivers 

### it along a plurality ofpulverized coal supply lines (one such burner line is identi?ed at A in the FIGURE; a single coal 

### pulveriZer 20 may supply coal through 4-8 pulveriZed coal supply lines) to the burners 22 on the front and rear Walls of the boiler 12. Typically, the burners 22 are located in spaced elevations on one or both ofthe opposed front and rear Walls ofthe boiler 12, or at the corners ofthe boiler in installations 

### knoWn as comer-?redor tangentially-?redunits (not shoWn). 

### Thepresent invention canbeutiliZed in conjunctionWith, but 20

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## 10 is not limited solely to, single-Wall ?red, opposed-Wall ?red and comer- ortangentially-?redunits. Typically, a single coal 

### pulveriZer 20 only provides coal to a single elevation of burners 22 on a Wall. Thus, in the embodiment shoWn in the 

### FIGURE, the six coal pulveriZersA-F supply corresponding burner elevationsA-F. HoWever, as is knoWn to those skilled 

### in the art, other pulveriZer and burner con?gurations are 

### knoWn (e.g., singlepulveriZers supplyingburners onmultiple Walls and/or elevations or multiple pulveriZers supplying burners on a single elevation) and the present invention 

### applies to any such con?gurations.

The combustionprocessbegins intheburner Zone 24 ofthe 

### boiler 12’s furnace 26, releasingheatandcreatinghot ?uegas 28 Which is conveyedupWardly to theupperportion 30 ofthe boiler 12, across heating surfaces schematically indicated as rectangles 32. The ?ue gas 28 is then conveyed across the 

### heating surfaces in the pendant convection pass 34, into the upper portion 36 of the horiZontal convection pass 38. The 

### ?ue gas 28 is then conveyed through a selective catalytic 

### reduction (SCR) apparatus 40 Where NO,C in the ?ue gas is 

### reduced, and then through primary and secondary air heater devices schematically indicated at 42. The air heaters 42 

### extract additional heat from the ?ue gas 28, loWering the 

### temperature ofthe ?ue gas, andpreheat the incomingairused for combustion.

As illustrated in the FIGURE, and doWnstream of the air heaters 42, the ?ue gas 28 undergoes furthertreatment forthe 

### removal ofparticulates and sulfur oxides. TWo typical con 

### ?gurations of the doWnstream equipment employed to accomplishthese tasks are shoWnontheright-hand side ofthe 

### FIGURE. Theupperequipment con?guration inthe FIGURE 

### comprises a particulate collection device (PCD) schemati cally indicated at 44, forremoval ofparticulates fromthe ?ue gas 28, and Which may comprise in practice a fabric ?lter or
an electrostaticprecipitator. Downstream ofthe PCD 44 there 

### is provided a Wet ?ue gas desulfuriZation (WFGD) device, also knoWn as a Wet scrubber, for removal of sulfur oxides from the ?ue gas 28. The cleaned, scrubbed ?ue gas may 

### (optionally)be conveyedthroughaWet ESP 47 forremoval of 

### ?ne particulate or S03, and then conveyed to stack 48 for 

### discharge to the atmosphere.

The loWer equipment con?guration in the FIGURE com 

### prises a spray dryerapparatus (SDA) schematically indicated at 50, also knoWn as a dry scrubber, for removal of sulfur oxides from the ?ue gas 28. Downstream ofthe SDA 50 there 

### is provided a particulate collection device (PCD) 44, as 

### describedabove, forremoval ofparticulates from the ?ue gas 28. The cleaned, scrubbed ?ue gas is then conveyed to stack 

### 48 for discharge to the atmosphere.

In order to further reduce NO,C emissions, some boilers 12 

### employ staged combustionWherein onlypart ofthe stoichio metric amount ofair is provided in the main burner Zone 24, 

### With the balance ofthe air for combustion, togetherWith any
excess air required due to the fact that no combustionprocess is 100 percent e?icient, is provided above theburner Zone 24 

### via over ?re air (OFA) ports 52. If staged combustion is employed in aboiler 12, due to the reducedair suppliedto the burner Zone 24, a reducing atmosphere is created in the loWer 

### portion ofthe furnace 26, including the hopper region 54.

InaccordanceWitha ?rst embodiment ofthepresent inven tion, one or more suitable kaolin-bearing compounds, one or
more suitable iron-bearing compounds, one or more suitable ironhalide compounds, or anymixture thereofis/are addedto the one or more coal pulveriZers 20 prior to supplying the pulverizedcoal to the one ormoreburners 22. The system and 

### apparatus for accomplishing this desired result is also shoWn 

### in the FIGURE, generally designated 100. The system 100

## US 8,303,919 B2 11 comprises a storage means 120 for temporarily storing the 

### potassium, sodium, phosphorous and/or mercury reduction/ 

## sequestration compound, generally designated 110; delivery

means 130, 135 for conveying the compound(s) 110 to a 

### desired location, includingvalves, seals, etc. as required; and 

### control means 150, advantageously microprocessor-based control means, Which are accessedvia an operatorvia human 

### operator interface (I/O) station 160, Which includes display and data collection and storage means as required. In the FIGURE, the raW coal 14 to Which compound(s) 110 has/ have been added is referred to as 140. Advantageously, com 

### pound(s) 110 maybeprovided alongWith the raW coal 14 via the feeder 18, Which permits close control and measurement ofthe delivery ofbothraW coal 14 and compound(s) 110 into 

### the coal pulverizer 20. Alternatively, compound(s) 110 may beprovideddirectly intothe coalpulverizer 20 and/ordirectly into one or more individual burner lines A-F providing the 

### pulverizedcoal to individualburners 22, With suitable sealing 

### devices against the positive pressure Within the coal pulver izer 20 or burner lines A-F. The delivery means may be 

### slurry-based or pneumatic as required by the particulars of compound(s) 110 and the amount and location of introduc tion into the ?ue gas 28. An interconnected arrangement of 

### control or signal lines 170, 180, 190 and 195 interconnect 

### thesevariousdevicestoprovide control signals, compound(s) 

### 110 level signals, andpotassium, sodium, phosphorous and/

ormercury level signals in the ?ue gas 28 (from a sensor 200) 

### to permit the introduction of the potassium, sodium, phosphorous and/or mercury reducing/sequestration com pound(s) 110 into the ?ue gas 28 to be controlledby a human operator, or automatically controlled. HoWever, ifa suitable, 

### real-time sensor 200 for measuring levels of gaseous potas sium, sodium, phosphorous and/ormercury in the ?ue gas 28 is/are not available, ?ue gas samples may insteadbe taken at 

### the location 200 for later laboratory analysis via suitable test 

### methods, Which may be inductively coupled plasma-mass spectrometry (ICP-MS). Basedupon the laboratory results, a human operator could then use the operator interface 160 to manually input a desired set-point into control means 150 for 

### the amount ofpotassium, sodium, phosphorous and/or mer 

### cury reducing/sequestration compounds 110 introduced into the ?ue gas 28. Provided that subsequent laboratory analyses do not indicate any signi?cant variation in gaseous potas 

### sium, sodium, phosphorous and/ormercury levels in the ?ue gas 28, theremaybenoneed forreal-time, close control ofthe 

### introduction ofpotassium, sodium, phosphorous and/ormer 

### cury reducing/sequestration compound(s) 110. Instead, the amount ofpotassium, sodium, phosphorous and/or mercury 

### reducing/sequestration compound(s) 110 introduced into the ?ue gas 28 may be simply a function of boiler load or coal feed rate values.



### In still yet another embodiment, the present invention uti lizes at least one kaolin-bearing compound in combination With iron (II) oxide. In this embodiment, theneed fora reduc tionreactionto occur is eliminated and the additionpoints for the iron (II) oxide ofthis embodiment are therefore broader 

### then previous embodiments. In this case, the kaolin-bearing compound andthe iron (II) oxide canbe addedat any suitable 

### point post-combustion and pre-SCR in order to capture, reduce, tie-up, bind and/or sequester any “free” gaseous 

### potassium, sodium, phosphorus and/ormercury compounds, ions, and/or atoms present in the ?ue gas of a boiler, or 

### furnace, prior to arrival at the SCR. In particular, the phos phorous reduction compound can be supplied at one ormore 

### of the locations G through Q shoWn in the FIGURE. More 

### particularly, thepotassium, sodium,phosphorous and/ormer cury reducing/sequestration compound(s) can also be pro 5

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## 12 vided (e.g., either separately, independently, or in any com bination) into the ?ue gas 28 at one ormore ofthe folloWing locations:

G: into or beloW the burner zone 24, in one or more ofthe

front, rear or side Walls, via means separate from the 

### burners 22; H: into the furnace 26 at a location above the burner zone

24, in one or more of the front, rear or side Walls; I, J: into the fumace 26 in the vicinity of or via the OFA

ports 52 on one or both of the front or rear Walls; 

### K: into the boiler 12 in the pendant convection pass 34; L: into theboiler 12 in the upperportion 36 ofthehorizon



### tal convection pass 38; 

### M, N, O, P: into the boiler 12 in the horizontal convection



### pass 38; and/or 

### Q: into the boiler 12 in the hopper region beloW the hori

zontal convection pass 38. 

### Giventhe above, the reduced iron, or iron (II) oxide, ofthe 

### present invention is able to capture, reduce, tie-up, bind and/
or sequester the gas phase phosphorus in the form of iron 

### phosphorus alloys Which upon coming in contact With the
over ?re air from iron-phosphorus oxide compounds, While 

### the kaolin-bearing compound is able to capture, reduce, tie up, bind and/or sequester any gas phase potassium and/or sodium compounds. This signi?cantly reduces the amount of 

### gas phase potassium, sodium and/or phosphorus accumula tion in an SCR catalyst. Another advantage of the present invention is that through addition of kaolin and/or iron a 

### signi?cantportionofanypotassium, sodiumand/orphospho

rus present Will be aluminosilicate-bound and/or iron-bound.

While not Wishing to be bound to any one theory, alkali aluminosilicates are believed to be less likely to be in a gas phase state in the conditions commonly found in a combus tion process and/or an SCR unit. This enables the minimiza tion ofthe amountpotassiumand sodiumthat is transferredto


### an SCRcatalystandthus availabletopoisonthe SCRcatalyst. 

### Additionally, Iron-bound phosphorus compounds are less leachable thereby minimizing the transfer ofphosphorus to
an SCR catalyst. Furthermore, phosphorus associated With and/or bound to an iron compound (e.g., an iron oxide) is
more stable than phosphorus that is associated With and/or 

### bound to a calcium compound (e.g., calcium oxide). Given this, the present invention is, in one embodiment, directed to the situationWhere a majority ofthe potassium, sodium and/

orphosphoruspresent inthe combustion and/or ?ue stream is 

### sequestered in a suitable alkali aluminosilicate compound 

### and/or iron-phosphorus-oxygen-containing compound thereby substantially reducing the amount of “free” gaseous 

### potassium-/sodium-containing compounds and/or calcium/ phosphorus/oxygen-containing compounds that are able to react With SOX. This in turn substantially reduces the amount 

### of gaseous potassium-/sodium-containing compounds that

can poison the SCR catalyst. Furthermore, the amount of 

### gaseous phosphorus that is produced in the combustion and/
or ?ue gas stream is substantially reduced by restricting the amount of calcium/phosphorus/oxygen-containing com pounds that are present in the combustion and/or ?ue gas 

### stream to react Withvarious SO,C compounds resulting in the 

### unWanted production ofgaseous phosphorus compounds, or phosphorus/oxygen compounds, that can lead to the undes 

### ired poisoning ofan SCR catalyst.

In still another embodiment, the one or more kaolin-bear ing compounds, and/or one ormore iron-bearing compounds ofthepresent invention canbe added in any suitablemanner, including the manner detailed in the FIGURE. Suitable 

### kaolin-bearing compounds are detailed above. Suitable iron 

### bearing compounds include, but are not limited to, aqueous

## US 8,303,919 B2 13 and soluble forms of iron-bearing compounds such as iron 

### halides (e.g., iron chlorides, iron bromides, iron iodide, or iron iodate), metallic iron, one or more iron oxides, iron carbonate, or mixtures oftWo or more thereof. If an existing skid is used then one or more aqueous reagents can be 

### pumpedviapositivedisplacementpumps from a storage tank to the one or more coal feeders Where the reagent is sprayed

on the coal as the coal passes on a feederbelt upstream ofthe 

## pulveriZers.

In one embodiment, the present invention is advantageous 

### in that it is applicable to both existing SCRs (retro?ts) and neW SCRs.Additionally, thepresent invention canbe applied
to plants that utiliZe biomass as a fuel source. In one embodi ment, implementation ofthepresent invention canbe accom plished ina cost-effectivemannerutiliZing loW costhardWare designed to supply the necessary iron compound to a com bustionprocess. Thepresent inventionalso does not affect the current design ofboilers and SCRs.

In one embodiment, the amount ofthe one ormore kaolin 

### bearing compounds and/or iron compound, or compounds, utiliZed in conjunction With the present invention varies depending upon the phosphorus content in the coal to be burned.As is knoWn to those ofskill in the art, thepotassium, sodiumand/orphosphorus content ofcoal and/orbiomass can 

### be determined by various knoWn methods. Thus, in this instance, thepresent invention is not limited to any one range, 

### oramount, ofkaolin-bearing compounds and/or iron-bearing compounds that are supplied/utiliZed. Instead, a stoichiomet ric ratio is utiliZed. In one embodiment, the stoichiometric ratio of potassium and/or sodium to kaolin-bearing com pound is in the range ofabout 1:3 to about 3:1, or from about 1:2 to about 2:1, or from about 1:1.5 to about 1.5:1, or from about 111.25 to about 1.25:1, or even about 1:1. In one 

### embodiment, the stoichiometric ratio ofironto phosphorus is in the range of about 1:3 to about 3:1, or from about 1:2 to about 2:1, or from about 1:1.5 to about 1.511, or from about 111.25 to about 1.25:1, or even about 1:1. Here, as Well as 

### elseWhere in the speci?cation and claims, individual range values can be combined to form additional and/or non-dis closed ranges.



### In another embodiment, the amount of kaolin-bearing 

### compound, orcompounds, and/or iron-bearing compound, or 

### compounds, utiliZed in conjunction With the present inven tion is Within a given range When the fuel utiliZed is PoWder 

### River Basin/Lignite coal, biomass, or any combination thereof. Inthis embodiment, the amountofthekaolin-bearing 

### compound, orcompounds, and/or iron-bearing compound, or compounds, to PoWderRiverBasin/Lignite coal, biomass, or any combination thereof, is expressed as the amount of 

### kaolin-bearing compound, or compounds, and/or iron-bear ing compound, or compounds, (hereinafterreferredto as just 

### “kaolin” and/or “iron” in only this instance) in pounds for every 1,000 pounds of coal and/or biomass. In one embodi ment, the amount of kaolin and/or iron compound, or com 

### pounds, utiliZed is in the range of about 0.7 pounds of “kaolin” and/or “iron” per 1,000 pounds ofcoal and/or bio

mass to about 6 pounds of “kaolin” and/or “iron” per 1,000 

### pounds of coal and/or biomass. In another embodiment, the amount ofkaolin and/or iron compound, or compounds, uti liZed is intherange ofabout 1 poundof“kaolin”and/or “iron” per 1,000 pounds ofcoal and/orbiomass to about 5.5 pounds 

### of “kaolin” and/or “iron” per 1,000 pounds of coal and/or biomass, or from about 1.5 pounds of “kaolin” and/or “iron” per 1,000pounds ofcoal and/orbiomass to about 5 pounds of 

### “kaolin” and/or “iron” per 1,000 pounds ofcoal and/or bio
mass, or from about 2 pounds of “kaolin” and/or “iron” per 

### 1,000 pounds ofcoal and/or biomass to about 4.5 pounds of 20

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## 14 “kaolin” and/or “iron” per 1,000 pounds of coal and/or bio
mass, or from about 2.5 pounds of “kaolin” and/or “iron”per 

### 1,000 pounds of coal and/or biomass to about 4 pounds of “kaolin” and/or “iron” per 1,000 pounds of coal and/or bio
mass, or from about 3 pounds of “kaolin” and/or “iron” per 

### 1,000 pounds ofcoal and/or biomass to about 3.5 pounds of “kaolin” and/or “iron” per 1,000 pounds of coal and/or bio

mass. Here, as Well as elseWhere in the speci?cation and claims, individual range values can be combined to form additional and/or non-disclosed ranges.



### In another embodiment, Wherein the iron portion of the present invention that is to be utiliZed for controlling various compounds in a ?ue gas, or combustion gas, of a 100 MWe coal and/orbiomass poWerplant is both iron (II)bromide and 

### iron (II) carbonate, the injectionrate for the iron (II) carbon ate is as discussed above While the iron (II) bromide is sup plied as a solution and at an amount in the range ofabout 0.25 gallons per hour to about 10 gallons per hour, or from about 0.5 gallons perhour to about 5 gallons perhour, or even from about 1 gallonperhourto about 4 gallonsperhour. In another 

### embodiment, Where just an iron halide is utiliZed (e.g., iron 

### (II) bromide and/or iron (III) bromide) the amount of iron halide suppliedto the ?ue gas, orcombustiongas, is suf?cient to yield a concentration ofbromide betWeen about 10 ppm to about 200 ppm, or from about 25 ppm to about 175 ppm, or from about 50ppm to about 150 ppm. It shouldbe noted that 

### dependinguponthe emissions control technology inplace on the device generating the ?ue gas, or combustion gas, it may be desirable to use a loWer bromide concentration in order to 

### prevent any type ofdetrimental effects to such doWnstream emissions technology. In one embodiment ofsuchan instance the concentration of bromide is betWeen about 10 ppm to about 125 ppm, or from about 25 ppm to about 100 ppm, or from about 50 ppm to about 75 ppm. Here, as Well as else 

### Where inthe speci?cationand claims, individual rangevalues (even from different embodiments) canbe combined to form additional and/or non-disclosed ranges.

In light ofthe above, one ofskill inthe artWouldrecogniZe that the amount ofkaolin compounds and/or iron compounds necessary to supply the desired amount ofkaolin, iron and/or halogen to a ?ue gas, or combustion gas, in accordance With 

### theprocess ofthepresent inventionWillvary dependingupon the siZe ofthe device generating such ?ue gas, or combustion 

### gas. Thus, the present invention is not limited to any speci?c rate or range of supply.

In another embodiment, for a 100 MWe coal and/or biom


### ass poWerplant the amount of iron (II) bromide solution (25 

### Weight percent solution) supplied to the ?ue gas, or combus tiongas, is intherange ofabout 0.25 gallonsperhourto about 6 gallons per hour, or from 0.5 gallons per hour to about 5 gallons per hour, or even from 1 gallon per hour to about 4 gallons per hour. Here, as Well as elseWhere in the speci?ca tion and claims, individual range values can be combined to form additional and/or non-disclosed ranges. HoWever, as is 

### noted above, the present invention is not limited to solely these supply rates. Rather, any supply rate can be used in order to achieve the desired concentration ofbromide and/or iron. As Would be apparent to one of skill in the art, other additional factors can impact the amount of iron-bearing 

### compounds supplied in connection With the various embodi ments of the present invention. Such additional factors include, but are not limited to, the amount and/or type of 

### phosphorus present inthe coal, or other combustible fuel; the siZe and/oroutput oftheboiler, heater, kiln, orother ?ue gas-,
or combustion gas-, generating device; and the desired sto

## US 8,303,919 B2 15 ichiometric ratio to be achieved; the type and/or manner of 

### combustion, the type and/or arrangement of any applicable equipment or structure.

In another embodiment, the one or more kaolin com pounds, and/or one or more iron compounds utiliZed in con 

### junctionWith thepresent invention canbe ofany particle siZe 

### and/or particle geometry. Suitable particle geometries include, but arenot limitedto, spherical, platelet-like, irregu lar, elliptical, oblong, or a combination of tWo or more dif ferent particle geometries. In one embodiment, the one or
more kaolin compounds, and/or one ormore iron compounds 

### ofthe present invention, ifWater soluble and/or suspendible,

canbe suppliedin solutionand/or suspension form. In suchan instance, a solution and/or suspension concentration of at least about 15 Weightpercent ofthe one ormoreWater soluble 

### and/or suspendible kaolin compounds and/or iron com pounds is/are utiliZed. In another embodiment, a solution 

### and/or suspension concentration of at least about 20 Weight percent, at least about 25 Weight percent, at least about 30 

### Weightpercent, at leastabout 35 Weightpercent, at leastabout 40Weightpercent, at least about 45 Weightpercent, or evenat least about 50Weightpercent ofmore ofthe one ormoreWater 

### soluble and/or suspendible kaolin compounds and/or iron compounds is utiliZed is utiliZed in conjunction With the present invention. Here, as Well as elseWhere in the speci? cationandclaims, individual rangevalues canbe combinedto form additional and/or non-disclosed ranges. As Would be 

### appreciated by those of skill in the art, the solution and/or suspension concentration of any one or more Water soluble 

### and/or suspendible kaolin compounds and/or iron com 

### pounds shouldnot, in one embodiment, exceedthe solubility amount for the one or more iron compounds.

In still another embodiment, the one or more kaolin com 

### pounds and/or iron compounds of the present invention can be supplied in a poWdered form, a solution form, an aqueous suspension form, orany combinationthereof. Inthe case ofan aqueous suspension, the one ormore kaolin compounds and/


### or iron compounds utiliZed in conjunction With the present invention should have a suitable particle siZe. Additionally,

even absent the desire to place the one or more kaolin com 

### pounds and/or iron compounds ofthe present invention into

an aqueous solution, the one or more kaolin compounds and/
or iron compounds should have a suitable particle siZe that 

### facilitates a higher degree of reactivity When placed into
contact With a ?ue, or combustion, gas. In one embodiment, both ofthese conditions can be met, Whether individually or in combination, by one ormorekaolin compounds and/or iron 

### compounds Where at least about 95 percent of the particles have a particle siZe of less than about 400 um (microns), Where at least about 95 percent oftheparticles have aparticle siZe ofless than about 350 um (microns), Where at least about 

### 95 percent of the particles have a particle siZe of less than about 300 um (microns),Whereat leastabout 95percent ofthe 

### particles have a particle siZe of less than about 250 um (mi crons), Where at least about 95 percent ofthe particles have a particle siZe of less than about 200 um (microns), or even Where at least about 95 percent oftheparticles have aparticle siZe of less than about 175 um (microns). Here, as Well as 

### elseWhere in the speci?cation and claims, individual range values can be combined to form additional and/or non-dis closed ranges.



### Althoughnot limitedhereto, WhenutiliZed, a suitable iron 

### compound foruse inconjunctionWiththepresent inventionis 

### iron (II) carbonate available from Prince Agri Products (a subsidiary of Phibro Animal Health Corporation located in 

### Ridge?eld Park, N.J.). This iron (II) carbonate is apoWdered compound Where at least about 95% of its particles are less 20

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## 16 than 200 um (microns) in siZe. Additionally, the concentra 

### tion of iron (II) carbonate in this product is about 80 percent 

### by Weight With substantially all of the remaining 20 Weight percent being non-reactive in light ofthe use here.

In the instance Where an aqueous suspension is utiliZed in conjunction With the present invention, such an aqueous sus pension can further comprise a suitable amount of one or 

### more anti-settling, suspension, thickening or emulsi?cation 

### agents. Suitable anti-settling, suspension, thickening or emulsi?cation agents include, but are not limited to, sodium 

## polyacrylates, carbomers, acrylates, inorganic thickening agents. Other suitableanti-settling, suspension, thickening or emulsi?cation agents areknoWnto those ofskill inthe art and

as such a discussion herein is omitted for the sake ofbrevity. In another embodiment, a suitable suspension or emulsi?ca tion can be achieved via agitation and does not necessarily require theuse ofone ormore anti-settling, suspension, thick ening or emulsi?cation agents. In another embodiment, a combination of one or more anti-settling, suspension, thick ening or emulsi?cation agents can be utiliZed in combination 

### With agitation.

In still another embodiment, the one or more kaolin com 

### pounds and/or iron compounds of the present invention should have a purity of at least about 50 Weight percent, at 

### least about 55 Weight percent, at least about 60 Weight per cent, at least about 65 Weightpercent, at least about 70Weight percent, at least about 75 Weight percent, at least about 80 

### Weightpercent, at leastabout 85 Weightpercent, at leastabout 90Weightpercent, at least about 95 Weightpercent, or evenat least about 99 Weight percent or higher. Here, as Well as 

### elsewhere in the speci?cation and claims, individual range values can be combined to form additional and/or non-dis closed ranges.

As for the portion of the one or more kaolin compounds and/or iron compounds that is noteither “akaolin compound” 

### and/or “an iron compound,” such impurities should be non 

### reactive in the environments present in conjunction With the 

### present invention. Alternatively, ifreactive, such impurities shouldeitherbe easily captured, removedand/or sequestered,

or shouldnot add signi?cantlyto any furthercontaminationof 

### any catalyst doWnstream. In still another embodiment, the 

### amount ofpotassium-, sodium- and/or phosphorus-contain ing compound impurities in any of the one or more kaolin compounds and/or iron compounds that are utiliZed in con 

### junctionWith the present invention shouldbe less than about 

### 5 Weightpercent, less thanabout 2.5 Weightpercent, less than 

### about 1 Weight percent, less than about 0.5 Weight percent, less than about 0.25 Weight percent, less than about 0.1 Weight percent, or even less than about 0.01 Weight percent. Here, as Well as elseWhere in the speci?cation and claims, individual range values can be combined to form additional 

### and/ornon-disclosedranges. In stillyet another embodiment, 

### the amount ofpotassium-, sodium- and/or phosphorus-con taining compound impurities inany ofthe one ormore kaolin compounds and/or iron compounds that are utiliZed in con 

### junctionWith the present invention shouldbe Zero. That is, in this embodiment the one or more kaolin compounds and/or 

### iron compounds that are utiliZed in conjunction With the 

### present invention should be free from any potassium-, 

### sodium- and/orphosphorus-containing compounds.

While not Wishing to be bound to any one theory, it is 

### believed that the present invention exploits various preferen tial reactions betWeen potassium, sodium and/or phospho

rous compounds, orpotassium-, sodium- and/orphosphorus 

### containing compounds, to sequester various potassium, sodium and/or phosphorous compounds, or potassium-,

## US 8,303,919 B2 17 sodium- and/or phosphorus-containing compounds that are detrimental to an increased active, or service, life ofan SCR catalyst. Thus, the reactions discussed herein are to be con strued as non-limiting in that other additional reactions may be occurring in the combustion and/or ?ue gas stream.



### While speci?c embodiments ofthe present inventionhave been shoWn and described in detail to illustrate the applica 

### tion andprinciples ofthe invention, itWill beunderstoodthat it is not intended that the present invention be limited thereto and that the invention may be embodied otherWise Without 

### departing from suchprinciples. In some embodiments ofthe invention, certain features ofthe inventionmay sometimesbe used to advantage Without a corresponding use of the other 

### features. Accordingly, all such changes and embodiments properly fall Within the scope ofthe folloWing claims.

What is claimed is: 1. A method for increasing the active life of an SCR cata 

### lyst, the method comprising the steps of:

(a) providing at least one kaolin-bearing compound to a

combustion Zone or ?ue gas stream of a fumace, or 

### boiler, prior to entry ofthe ?ue gas into an SCR; and 

### (b) permitting the at least onekaolin-bearing compoundto

react With any gaseous potassium and/or sodium com 

### pounds, or potassium- and/or sodium-containing com pounds present in the combustion Zone or ?ue gas prior to the entry ofthe ?ue gas into the SCR. 2. Themethod ofclaim 1, Whereinthe kaolin-bearing com pound is selected from one or more kaolin-containing clays, kaolinite-containing clays, kaolinite, or mixtures of tWo or

more thereof.

3. Themethod ofclaim 1, Whereinthe kaolin-bearing com 

### pound is selected from kaolinite.

4. The method ofclaim 1, Wherein the at least one kaolin 

### bearing compound is provided to the combustion Zone via addition to pulverized coal, biomass, or a mixture thereof.

5. The method ofclaim 1, Wherein the at least one kaolin bearing compound is provided to the combustion Zone via a 

### dedicated supply line.

6. The method of claim 1, Wherein the method further 

### comprises the steps of:

(c)providing at least one iron-bearing compound to a com

bustion Zone or ?ue gas stream of a furnace, or boiler, prior to entry ofthe ?ue gas into an SCR; and 

### (d) permitting the at least one iron-bearing compound to

reactWithany gaseousphosphorus compounds, orphos 

### phorus-containing compounds, present in the combus tion Zone or ?ue gaspriorto the entry ofthe ?ue gas into the SCR. 7. A method for increasing the active life of an SCR cata 

### lyst, the method comprising the steps of:

(i) providing at least one kaolin-bearing compound to a

combustion Zone of a fumace or boiler; and 

### (ii) permitting the at least onekaolin-bearing compoundto

react With any gaseous potassium and/or sodium com 

### pounds, or potassium- and/or sodium-containing com 

### pounds present inthe combustion Zonepriorto the entry ofthe ?ue gas into an SCR, 

### Wherein thekaolin-bearing compound is selected fromone



### or more kaolin-containing clays, kaolinite-containing clays, kaolinite, or mixtures of tWo or more thereof. 8. The method ofclaim 7, Wherein the at least one kaolin 

### bearing compound is provided to the combustion Zone via addition to pulverized coal, biomass, or a mixture thereof.

9. The method ofclaim 7, Wherein the at least one kaolin bearing compound is provided to the combustion Zone via a dedicated supply line either in aqueous suspension or in a 

### poWdered form. 5

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## 18 10. The method of claim 7, Wherein the method further 

### comprises the steps of:

(iii) providing at least one iron-bearing compound to a

combustion Zone of a fumace or boiler; and 

### (iv) permitting the at least one iron-bearing compound to

reactWithany gaseousphosphorus compounds, orphos 

### phorus-containing compounds, present in the combus tion Zone prior to the entry ofthe ?ue gas into an SCR. 11. A method for increasing the active life of an SCR 0 catalyst While concurrently controlling mercury in a gas, the



### method comprising the steps of: (1) providing at least one kaolin-bearing compound to a

combustion Zone or ?ue gas stream of a fumace, or 

### boiler, prior to entry ofthe ?ue gas into an SCR; 

### (ll)providingat least one iron-bearinghalide compoundto

a combustion Zone or ?ue gas stream of a furnace, or 

### boiler, prior to entry ofthe ?ue gas into an SCR; 

### (Ill)permitting thekaolinportionofthe at least onekaolin



### bearing compound to react With any gaseous potassium and/or sodium compounds, or potassium- and/or 

### sodium-containing compounds present in the combus tion Zone or ?ue gas prior to the entry ofthe ?ue gas into 

### the SCR; (IV) permitting the iron portion of the at least one iron

bearing halide compound to react With any gaseous 

### phosphorus compounds, or phosphorus-containing compounds present in the combustion Zone or ?ue gas 

### prior to the entry ofthe ?ue gas into the SCR; and (V) permitting the halide portion of the at least one iron

bearinghalide compoundto reactWith any gaseousmer 

### cury compounds, or mercury-containing compounds, present in the combustion Zone or ?ue gas. 

### 12. The method of claim 11, Wherein the kaolin-bearing compound is selected from one or more kaolin-containing 

### clays, kaolinite-containing clays, kaolinite, or mixtures of

tWo or more thereof.



### 13. The method of claim 11, Wherein the kaolin-bearing 

### compound is selected from kaolinite.

14. The method of claim 11, Wherein the iron-bearing 

### halide compound is selected from iron (ll)bromide, iron (Ill) 

### bromide, iron (ll)chloride, iron (Ill)chloride, iron (ll) iodide, iron (Ill) iodate, or mixtures of tWo or more thereof.



### 15. The method of claim 11, Wherein the iron-bearing 

### halide compound is iron (11) bromide.

16. Themethod ofclaim 11, further comprising supplying

one or more non-halogen-containing iron-bearing com pounds in combination With the at least one iron-bearing halide, Where the one or more non-halogen-containing iron 

### bearing compounds are selected from iron (Ill) oxide, iron (11) carbonate, iron (ll) oxide, or mixtures of tWo or more thereof.



### 17. Themethod ofclaim 11, further comprising supplying iron (ll) carbonate in combination With the at least one iron 

### bearing halide.

18. Themethod ofclaim 11, further comprising supplying iron (11) carbonate in combination With one or more of iron 

### (11) bromide or iron (Ill) bromide.

19. A method for sequestering one or more potassium 

### and/or sodium compounds, or potassium- and/or sodium containing compounds, in the form ofone or more less reac 

### tive sodium aluminosilicate-containing, orpotassium alumi nosilicate-containing, compounds, as Well as sequestering

one ormorephosphorus compounds, orphosphorus-contain ing compounds, in the form of one or more less reactive 

### iron-phosphorus-containing compounds While concurrently sequestering mercury, the method comprising the steps of:

## US 8,303,919 B2 19 (1) providing at least one kaolin-bearing compound to a

combustion Zone or ?ue gas stream of a fumace, or 

### boiler; (2) providing at least one iron-bearinghalide compoundto

a combustion Zone or ?ue gas stream of a furnace, or 5 

### boiler; (3) permitting the kaolinportion ofthe at least onekaolin



### bearing compound to react With any gaseous potassium and/or sodium compounds, or potassium- and/or 

### sodium-containing compounds present in the combus tion Zone or ?ue gas to form one or more less reactive 

### sodiumaluminosilicate-containing, orpotassium alumi 

## nosilicate-containing, compounds; (4) permitting the iron portion of the at least one iron

bearing halide compound to react With any gaseous 

### phosphorus compounds, or phosphorus-containing compounds, present in the combustion Zone or ?ue gas to form one or more less reactive iron-phosphorus-con 

### taining compounds; and (5) permitting the halide portion of the at least one iron

bearing halide compoundto reactWithany gaseousmer 

### cury compounds, or mercury-containing compounds, present in the combustion Zone or ?ue gas. 

### 20. The method of claim 19, Wherein the kaolin-bearing compound is selected from one or more kaolin-containing 10

20 

## 20 clays, kaolinite-containing clays, kaolinite, or mixtures of

tWo or more thereof.



### 21. The method of claim 19, Wherein the kaolin-bearing 

### compound is selected from kaolinite.

22. The method of claim 19, Wherein the iron-bearing 

### halide compound is selected from iron (ll)bromide, iron (Ill) 

### bromide, iron (ll)chloride, iron (Ill)chloride, iron (ll) iodide, iron (Ill) iodate, or mixtures of tWo or more thereof.



### 23. The method of claim 19, Wherein the iron-bearing halide compound is one or more of iron (11) bromide or iron 

### (Ill) bromide.

24. Themethod ofclaim 19, further comprising supplying

one or more non-halogen-containing iron-bearing com pounds in combination With the at least one iron-bearing halide, Where the one or more non-halogen-containing iron 

### bearing compounds are selected from iron (Ill) oxide, iron (11) carbonate, iron (ll) oxide, or mixtures of tWo or more thereof.



### 25. Themethod ofclaim 19, further comprising supplying iron (ll) carbonate in combination With the at least one iron 

### bearing halide.

26. Themethod ofclaim 19, further comprising supplying iron (11) carbonate in combination With one or more of iron 

### (11) bromide or iron (Ill) bromide.

* * * * *