### USOO8716169B2



# (12) United States Patent (10) Patent N0.: US 8,716,169 B2 Gadgil et a]. (45) Date ofPatent: May 6, 2014

(54) SYSTEM AND METHOD FOR PROTECTION 4,572,085 A * 2/1986 Hepworth

................... .. 110/345 01: SCR CATALYST AND CONTROL 01: 4,831,942 A * 5/1989 Morimoto et a1.

. 110/345 4,843,980 A * 7/1989 Markham et al.

........... .. 110/342 MULTIPLE EMISSIONS 4,871,522 A 10/1989 Doyle 

### (75) Inventors: Mandar R. Gadgil,Akron, OH (US); S. 2 B?ylet l

. . - , , u e a. Behrf’oz Ghonsm’ Unlomown’ OH 5,567,394 A * 10/1996 Chu 61 a1.

.................... .. 422/177 

### (Us), Donald P- T011“, Copley, OH (Us) 5,585,081 A 12/1996 Chu 61 a1.
(73) Assignee: Babcock & Wilcox Power Generation 5,899,679 A * 51999 Euzen et Grou Inc Barbenon OH (Us) 7,741,239 B2 6/2010 Hartensteln et a1.

............ 502/25
P’ " ’ 8,124,036 B1 2/2012 Baldrey et al.

_ _ _ _ _ 2006/0245993 A1 11/2006 Magumbe 61 a1. ( * ) Notice: SubJeCI to any disclaimer, the term ofthis 2007/0140940 A1 * 6/2007 Varma 6131.

............. .. 423/2155 patent is extended or adjusted under 35 2007/0154374 A1 7/2007 Johnson et a1. U_s_c_ 15403) by 154 days_ 2007/0160517 A1 7/2007 Fan et a1. 2008/0107579 A1 5/2008 Downs et al. (21) Appl' NO; 12/691527 2009/0065414 A1 3/2009 Nelson et al.

_ OTHER PUBLICATIONS 

### (22) F11ed: Jan. 21, 2010 Vitali V. Lissianski et al.; Utilization of IronAdditives forAdvanced (65) PFIOI‘ Pllblication Data Control of NOX Emissions from Stationary Combustion Sources;

Us Res. On the Internet On ' ’ 2001), 40, pp. 3287 to 3293.


### Related US.Application Data (Continued) (60) Provisional applicationNo. 61/171,619, ?led onApr. 22, 2009. Primary Examiner * Melvin C Mayes Assistant Examiner * Michael Forrest (51) Int“ Cl“ (74) Attorney, Agent, or Firm 4 Eric Marich 

### BOIJ27/185 (2006.01) 

### F23J11/00 (2006.01) F23] 15/00 (2006.01) (57) ABSTRACT C10L 5/00 (200601) The present invention relates generally to the ?eld of emis 

### (52) US Cl- sioncontrol equipment forboilers, heaters,kilns, orother ?ue USPC

.............................. 502/213; 110/345; 44/620 gas-, of combustion gas-, generating devices (e,g., those 

### (58) Field ofClassi?cation Search located at power plants, processing plants, etc.) and, in par USPC

........................................... .. 44/620; 1 10/345 ticular to a new and useful method and apparatus forprevent 

### See application ?le for complete search history. ingthepoisoningand/orcontaminationofan SCRcatalyst. In anotherembodiment, themethodandapparatus ofthepresent (56) References Cited inventionis designedto protect an SCR catalyst, While simul

U.S. PATENT DOCUMENTS

4,061,716 A * 12/1977 McGauley

............. .. 423/244.06 

### taneously providing emission control.

57 Claims, 1 Drawing Sheet

140 

### 18 it A

COAL PULVv 110 20 100 [120 70 I 150 160 \i I 0/



## , u, 19 110 v? '- -------
130 -' 365 135 ; 38 

### 110 $ M l 

# 16 10071119115 y chL 12\ -N I
BUNKER
14 |-o->



# 9‘: 52—} XL? C-O-> 26

---- FEEDER B»

## US 8,716,169 B2 Page 2

(56) References Cited
OTHER PUBLICATIONS

Terence Ake et al.; Limestone Injection for Protection of SCR Cata 

### lyst; Riley Power, Duke Energy, Cormetech, Inc. Paper #175, 2003. Virpi Kroger; Poisoning ofAutomotive Exhaust Gas Catalyst Com ponentsiThe Role of Phosphorus in the Poisoning Phenomena; Academic Dissertation, University ofOulu, Finlandi2007. BeckJens et al.; The Behavior ofParticle Bound Phosphorus During the Combustion ofPhosphate Doped Coal; Fuel, 86, 2007 (available online Sep. 27, 2006), pp. 632 to 640. Elias Matinde et al.; Phosphorus Gasi?cation from Sewage Sludge During Carbothermic Reduction; ISIJ International, vol. 48 (2008), No. 7, pp. 912 to 917. Athen Tate et al.; Environmentally Sound Handling of Deactivated SCR Catalyst; Downloaded from the Internet on May 13, 2009 at http ://WWW.coalpowermag .com/environmental/l36 .htrnl. J.P. Chen et al.; Mechanism ofPoisoning oftheV2OS/TiO2 Catalyst for the Reduction ofNO ByNH3; Journal ofCatalysis, vol. 125, pp. 411 to 420 (Oct. 1990). Xiaoyu Guo et al.; Effects of sulfate species on V2OS/TiO2 SCR Catalysts in Coal and Biomass-?red Systems; Applied Catalysis B: Environmental, vol. 92, pp. 30 to 40 (Oct. 2009). PCT International Search Report datedAug. 17, 2012 in related PCT application No. PCT/US2012/039l75.

* cited by examiner

## US 8,716,169 B2 1
SYSTEMAND METHOD FOR PROTECTION

OF SCR CATALYSTAND CONTROL OF MULTIPLE EMISSIONS

RELATEDAPPLICATION DATA



### This patent application claims priority to US. Provisional 

### Patent Application No. 61/171,619 ?led Apr. 22, 2009 and titled “System and Method for Protection of SCR Catalyst.” 

### The complete text ofthis application is hereby incorporated by reference as though fully set forth herein in its entirety.

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 andapparatus forreducing

orpreventing the poisoning and/or contamination ofan SCR 

### catalyst. Inanotherembodiment, themethodandapparatus of 

### thepresent 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 andwater 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?ed NO 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 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 destruction. Rather, it is
a practical limit set to prevent excessive levels of ammonia 

### slip. This problem is explained as follows. 20

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## 2

In an SCR, ammonia reacts with NO 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. 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 similarlytobasemetalcatalysts. Onepotentialadvantage 

### of zeolite catalysts is their higher operating temperature of about 970° F. (521° C.). These catalysts canalso 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, convertingCOto 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 

## phosphorouspentoxide (P205).

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’sperformance overtime. Themost commoncatalystpoisonencounteredwhenburning 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 common masking mechanism. One method of 

### recycling the used catalyst is the process called regeneration washing orrejuvenation. The initial steps ofthe regeneration process involve the removal ofthese toxic chemicals by pro 

### cessing the catalysts throughvarious chemicalbaths inwhich 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.



### In another situation, Powder River Basin/Lignite coal plants, any coal/biomass co-combustion, or any coal/bone meal co-combustion or evenpurebiomass combustionpower 

### plants will suffer from phosphorus contamination of their 

### SCR catalysts.

## US 8,716,169 B2 3 Additionally, beyond controlling NO,C emissions, other emission controls must be considered and/ormet in order to 

### comply withvarious state, EPA and/or CleanAirAct regula tions. Some other emission controlswhichneed 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 any economical and environmentally suitable method and/or system to remove the gaseous phosphorus from a 

### combustionprocesspriorto anyphosphorus compoundspoi soning a catalyst in an SCR.

SUMMARY OF THE 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 andapparatus forreducing

orpreventing 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 ofan SCR catalyst, 

### themethod comprising the steps of: (a) providing at least one iron-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 iron-bearing 

### compoundtoreactwithanygaseousphosphorus compounds,
or phosphorus-containing compounds, present in the com bustion zone or ?ue gas prior to 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, themethod comprising the steps of: (i) providing at least one iron-bearing compound to a combustion zone of a furnace or boiler; and (ii) permitting the at least one iron 

### bearing compound to react with any gaseous phosphorus 

### compounds, or phosphorus-containing compounds, present inthe combustion zonepriorto the entry ofthe ?ue gas into an 

### SCR, wherein the iron-bearing compound is selected from
one or more iron (II) halides, iron (III) halides, iron (III) 

### iodate, iron (III) oxide, iron (II) carbonate, ormixtures oftwo

or more thereof.



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

### compounds, or phosphorus-containing compounds, in the form ofone ormore lessreactive iron-phosphorus-containing 

### compounds, themethod comprising the steps of: (A) provid ing at least one iron-bearing compound to a combustion zone
or ?ue gas stream ofa furnace, or boiler; and (B) permitting the at least one iron-bearing 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-containing 

## 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: providing at least one iron bearing halide compound to a combustion zone or ?ue gas stream ofa fumace, orboiler, priorto entry ofthe ?ue gas into
an SCR; permitting the iron portion ofthe at least one iron 

### bearinghalide compoundto reactwith any gaseous phospho
rus compounds, or phosphorus-containing compounds, 20

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## 4 present inthe combustion zone or ?ue gaspriorto the entry of 

### the ?uegas into the SCR; andpermittingthehalideportion 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.



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

### compounds, or phosphorus-containing compounds, in the form ofone ormore lessreactive iron-phosphorus-containing 

### compounds while concurrently sequestering mercury, the method comprising the steps of: providing at least one iron bearing halide compound to a combustion zone or ?ue gas stream of a furnace, or boiler; permitting the iron portion of the at least one iron-bearing halide compound to react with 

### anygaseousphosphorus compounds, orphosphorus-contain ing compounds, present in the combustion zone or ?ue gas to form one or more less reactive iron-phosphorus-containing 

### compounds; andpermitting the halide portion ofthe 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 schematicrepresentationofatypical 

### 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 frequentlypreferred for economic reasons, the present invention is not limited to ammonia based sys tems. The concepts ofthepresent inventioncanbeusedinany systemwhich uses an ammoniacal compound.As used in the presentdisclosure, 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.

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 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

## 5 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 S03. Alternatively, the present inven tionmaybe applied to a systemwhich employs a spray dryer 

### apparatus (SDA) ordry scrubber forremoval ofsulfur oxides 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 adirection of?ue gas ?ow 

### throughthe system)by aparticulate collectiondevice (PCD), advantageously a fabric ?lter (FF) 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, P0 or PZOS. As such, the present invention is not limited to any one type of SCR catalyst, but rather is broadly applicable 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 invention is not limitedthereto. Rather, 

### the present invention is broadly applicable to any situation where an SCR catalyst is poisoned by one or more gaseous 

## phosphorus compounds.

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

### units. This deactivation is suspected to be caused by the gas phase phosphorus released via carbothermic reduction reac 

### tion. Inthis reactionunderoxygende?cient conditions, phos 

### phorus bearing compounds release gasphasephosphorus by the following reaction: P205(solidphase compounds)+3C(s)—>2PO(g)+ 3CO(g). 

### 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 one embodiment, the present invention relates to a sys 

### tem andmethod to prevent formation ofgas phase phospho
rus species in the combustion environment thus reducing, mitigating and/oreliminating therate ofSCRdeactivation. In


### one embodiment, the present invention accomplishes the aforementioned goal by the addition of at least one iron 

### bearing compound to the PRB coal prior to combustion.

In one embodiment, the iron-bearing compounds of the present invention is any iron compound (e.g., an iron oxide 

### compound) that is able to undergo reduction in the combus tion environments common to boilers, fumaces, power 

### plants, etc. In one particular embodiment, the iron-bearing compound is iron (III) oxide (Fe203), also known as red iron oxideorhematite. Inthe embodimentwhere iron (III) oxide is utilized the reactions ofinterest that occur in the combustion portion of a boiler or furnace are as shown below: 20

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## 6
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.FeZO3. The FeO or iron (II) 

### oxide, also known as ferrous oxide, which is generateddue to 

### the reduction ofFeZO3 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 compounds in particulate phase prior to arrival at the SCR. The particulate will pass 

### through the catalyst and avoid the catalyst 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 canuti 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 

### tiongas 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 PublicationNo. 2008/0107579 the text ofwhich 

### is hereby incorporated by reference as though fully set forth herein) halide-containing compounds are utilized to oxidize elemental mercurypresent in a ?ue, or combustion, gas. Due to this oxidation reaction, the halide portion of a suitable 

### halide-containing compound permits elemental mercury to be converted into a more favorable form for subsequent cap ture, or sequestration, via one ormore 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 particulate collecting system such as a fabric ?lter (FF) or a electrostatic precipitator (ESP)). Inone instance, as is known inthe art, the addition of one or more suitable halide-containing com 

### pounds also increases the amount ofmercury that is particu 

### late-bound. Giventhatnumerouspatents andpublishedappli cations detail themannerbywhich suitablehalide-containing compounds permit the increased recovery ofmercury from a ?ue, or combustion, gas, a detailed discussionhereofis omit 

### ted for the sake ofbrevity.

Inany ofthe above embodiments, the suitable iron-bearing compound can be added to the coal in the pulverizer. In still 

### another embodiment, the iron-bearing compound 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 a powderized iron-bearing compound to the combus

## US 8,716,169 B2 7 tion zone ofa furnace and/orboiler. 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 coalto 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 inconjunctionwith, but 

### 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 bumers 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 bumers 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 ?uegas, andpreheatthe incomingairused for combustion.

As illustrated in the FIGURE, and downstream of the air 

### heaters 42, the ?ue gas 28undergoes furthertreatment for the 

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

### ?gurations of the downstream equipment employed to accomplishthesetasks are shownontheright-hand side ofthe 

### FIGURE. Theupperequipmentcon?guration inthe FIGURE 20

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## 8 comprises a particulate collection device (PCD) schemati cally indicatedat 44, forremoval ofparticulates fromthe ?ue gas 28, and which may comprise in practice a fabric ?lter or anelectrostaticprecipitator. 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 conveyedthroughawetESP 47 forremoval of 

### ?ne particulate or $03, and then conveyed to stack 48 for 

### discharge to the atmosphere.

The lower equipment con?guration in the FIGURE com 

### prises a spraydryerapparatus (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 fromthe ?uegas 28. The cleaned, scrubbed ?ue gas is then conveyed to stack 

### 48 for discharge to the atmosphere.

In order to further reduce NO 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% ef?cient, is provided above the burner zone 24 via


### over?reair (OFA)ports 52. Ifstagedcombustionis employed in a boiler 12, due to the reduced air supplied to the burner


### zone 24, areducing atmosphere is created inthe lowerportion 

### ofthe fumace 26, including the hopper region 54.

Inaccordancewitha ?rst embodiment ofthepresent inven tion, a suitable iron-bearing compound is added to the one or 

### more coal pulverizers 20 prior to supplying the pulverized coal to the one ormore burners 22. The system and apparatus 

### for accomplishing this desired result is also shown in the 

### FIGURE, generally designated 100. The system 100 com prises a storage means 120 for temporarily storing the phos 

### phorous reduction compound, generally designated 110; deliverymeans 130, 135 for conveying the compound 110 to
a desired location, including valves, seals, etc. as required; 

### and control means 150, advantageously microprocessor based control means, which are accessed via an operator via 

### human operator interface (I/O) station 160, which includes display and data collection and storagemeans as required. In the FIGURE, the raw coal 14 to which the phosphorous reducing compound 110 has been added is referred to as 140. 

### Advantageously, the phosphorous reducing compound 110 maybeprovided alongwith theraw coal 14 via the feeder 18, 

### whichpermits close control andmeasurement ofthe delivery ofbothraw coal 14 andphosphorous reducing compound 110 

### into the coal pulverizer 20. Alternatively, the phosphorous 

### reducing compound 110 may be provided directly into the coal pulverizer 20 and/or directly into one ormore individual 

### burner lines A-F providing the pulverized coal to individual 

### bumers 22, with suitable sealing devices against thepositive pressurewithinthe coalpulverizer 20 orburnerlinesA-F. The deliverymeansmaybe slurry-basedorpneumatic as required 

### by the particulars of the phosphorous reducing compound 110 and the amount and location ofintroduction into the ?ue gas 28. An interconnected arrangement of control or signal 

### lines 170, 180, 190 and 195 interconnect these various 

### devices to provide control signals, phosphorous reducing compound 110 level signals, andphosphorous level signals in the ?ue gas 28 (from a sensor 200) to permit the introduction 

### ofthephosphorous reducing compound 110 into the ?ue gas 28 to be controlled by a human operator, or automatically controlled. However, if a suitable, real-time sensor 200 for 

### measuring levels ofgaseous phosphorous inthe ?uegas 28 is not available, ?ue gas samples may instead be taken at the

## US 8,716,169 B2

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 of phosphorus reducing compound 110 intro duced into the ?ue gas 28. Provided that subsequent labora 

### tory analyses do not indicate any signi?cantvariation in gas eous phosphorus levels in the ?ue gas 28, there may be no 

### need for real-time, close control ofthe introduction ofphos 

### phorusreducing compound 110. Instead, theamountofphos phorus reducing compound 110 introduced into the ?ue gas 28 may be simply a function ofboiler load or coal feed rate values.



### In still yet another embodiment, the present invention uti lizes iron (II) oxide. Inthis embodiment, theneed fora reduc tionreactionto occur is eliminatedand the additionpoints for the iron (II) oxide ofthis embodiment are therefore broader 

### then previous embodiments. In this case, the iron (II) oxide
can be added at any suitable point post-combustion and pre SCR in order to tie up, bind and/or sequester any PO gas present in the ?ue gas ofaboiler, or fumace, prior to arrival at 

### the SCR. Inparticular, thephosphorous reduction compound

can be supplied at one or more ofthe locations G through Q 

### shown in the FIGURE. More particularly, the phosphorous reduction compound can also beprovided into the ?ue gas 28 at one or more of the following locations:

G: into or below the burner zone 24, in one or more of the

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 ormore ofthe front, rear or side walls; I, J: into the furnace 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 remove the gas phase phosphorus 

### in the form ofiron-phosphorus alloys whichupon coming in contact with the over ?re air from iron-phosphorus oxide 

### compounds. This signi?cantly reduces the amount of gas 

### phasephosphorus accumulation in an SCR catalyst.Another 

### advantage ofthepresent invention is that throughaddition of iron a signi?cant portion of any phosphorus present will be iron-bound. 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 situationwhereamajority ofthephosphoruspresent inthe combustion and/or ?ue stream is sequestered in a suitable 

### iron-phosphorus-oxygen-containing compoundthereby sub stantially reducing the amount of calcium/phosphorus/oxy gen-containing compounds that are able to react with SOX. This in turn substantially reduces the amount of gaseous 

### phosphorus that isproducedinthe combustionand/or ?uegas 

### streambyrestrictingthe amount ofcalcium/phosphorus/oxy gen-containing compoundsthatarepresent inthecombustion and/or ?ue gas stream to react with various SO,C compounds 

### resulting in the unwantedproduction ofgaseous phosphorus 20

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65 

## 10 compounds, orphosphorus/oxygen compounds, that can lead to the undesired poisoning ofan SCR catalyst.



### In still another embodiment, the iron-bearing compounds ofthepresent invention canbe added in any suitablemanner, including themanner detailed in the FIGURE. Suitable iron 

### bearing compounds include, but are not limited to, aqueous 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 of two or more thereof. If an existing skid is used then an aqueous reagent can be pumped via positive displacementpumps from a storage tankto the one or
more coal feeders where the reagent is sprayed on the coal as the coal passes on a feeder belt 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 in a cost-effectivemannerutilizing low costhardware designed to supply the necessary iron compound to a com bustionprocess. Thepresent inventionalso does not affectthe current design ofboilers and SCRs.

In one embodiment, the amount of iron compound, or 

### compounds, utilized in conjunction with the present inven tionvaries dependinguponthephosphorus content inthe coal to be burned. As is known to those of skill in the art, the phosphorus content of coal can be determined by various 

### knownmethods. Thus, in this instance, thepresent invention is not limited to any one range of iron compounds that are utilized. Instead, a stoichiometric ratio is utilized. In one 

### embodiment, the stoichiometric ratio ofirontophosphorus 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 1.5:1, or from about 1:1.25 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 ofiron compound, or 

### compounds, utilized in conjunction with the present inven tion is within a given range when the coal utilized is Powder 

### River Basin/Lignite coal. In this embodiment, the amount of the iron compound, or compounds, to Powder River Basin/ Lignite coal is expressed as the amount ofiron compound, or 

### compounds, (hereinafterreferredto asjust “iron” in only this instance) in pounds for every 1,000 pounds of coal. In one embodiment, the amount of iron compound, or compounds, utilized is in therange ofabout 0.7pounds of“iron”per 1,000 

### pounds ofcoal to about 6 pounds of “iron”per 1,000pounds of coal. In another embodiment, the amount of iron com pound, or compounds, utilized is in the range of about 1 

### pound of“iron”per 1,000pounds ofcoal to about 5.5 pounds of“iron” per 1,000 pounds ofcoal, or from about 1.5 pounds of“iron”per 1,000pounds ofcoal to about 5 pounds of“iron” per 1,000pounds ofcoal, orfromabout 2pounds of“iron”per 

### 1,000 pounds ofcoal to about 4.5 pounds of“iron”per 1,000 pounds ofcoal, or from about 2.5 pounds of“iron” per 1,000 

### pounds ofcoal to about 4 pounds of “iron”per 1,000pounds ofcoal, or from about 3 pounds of“iron”per 1,000pounds of 

### coal to about 3.5 pounds of “iron” per 1,000 pounds ofcoal. 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, where both iron (II) bromide and iron (II) carbonate is to be utilized for controlling various compounds in a ?ue gas, or combustion gas, of a 100 MWe 

### coal powerplant the injection rate for the iron (II) carbonate

## US 8,716,169 B2 11 is as discussedabovewhilethe iron (II)bromide is suppliedas
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 per hour to about 5 gallons per hour, or even from about 1 gallonperhourto about 4 gallonsperhour. Inanother 

### 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 10ppm to about 200 ppm, or from about 25 ppm to about 175 ppm, or from about 50 ppm to about 150 ppm. It should be 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 of detrimental 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 in the artwouldrecognize 

### that the amount of iron compounds necessary to supply the desired amount of iron and halogen to a ?ue gas, or combus tion gas, in accordance with theprocess ofthe present inven 

### tionwill vary depending upon the size ofthe device generat ing such ?ue gas, or combustion gas. Thus, the present invention is not limitedto any speci?c rate orrange ofsupply.

In another embodiment, for a 100 MWe coal power plant 

### the amount of iron (II) bromide solution (25 weight percent solution) suppliedto the ?ue gas, or combustiongas, is in the range of about 0.25 gallons per hour to about 6 gallons per 

### hour, or from 0.5 gallons perhourto about 5 gallonsperhour,
or even from 1 gallon per hour to about 4 gallons per hour. Here, as well as elsewhere in the speci?cation and claims, individual range values can be combined to form additional and/or non-disclosedranges. 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 ofskill in the art, other additional factors can 

### impact the amount of iron-bearing compounds supplied in connection with the various embodiments of the present invention. Such additional factors include, but are not limited 

### to, the amount and/ortype ofphosphorus present in the coal,
orother combustible fuel; the size and/or output oftheboiler, heater, kiln, orother ?ue gas-, or combustiongas-, generating 

### device; and the desired stoichiometric ratio to be achieved; the type and/or manner of combustion, the type and/or 

### arrangement ofany applicable equipment or structure.

In another embodiment, the one or more iron compounds utilized in conjunction with the present invention can be of 

### any particle size and/or particle geometry. Suitable particle geometries include, but are not limitedto, spherical, platelet like, irregular, elliptical, oblong, or a combination oftwo or more different particle geometries. In one embodiment, the
one ormore iron compounds ofthepresent invention, ifwater soluble, canbe supplied in solution form. In suchan instance,
a solution concentration ofat least about 15 weightpercent of the one or more water soluble iron compounds is utilized. In another embodiment, a solution concentration of at least 

### about 20 weight percent, at least about 25 weight percent, at least about 30 weight percent, at least about 35 weight per cent, at least about 40weightpercent, at least about 45 weight percent, or even at least about 50 weight percent ofmore of the one or more water soluble iron compounds is utilized is 20

25

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65 

## 12 utilized in conjunction with the present invention. Here, as well as elsewhere in the speci?cation and claims, individual
range values can be combined to form additional and/or non 

### disclosedranges.As wouldbe appreciatedbythose ofskill in the art, the solution concentration of any one or more water 

### soluble iron compounds should not, in one embodiment, exceed the solubility amount for the one or more iron com 

## pounds.

In still another embodiment, the one or more iron com 

### pounds ofthepresent inventioncanbe supplied inapowdered form, a solution form, an aqueous suspension form, or a combination thereof. In the case of an aqueous suspension, the one ormore 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 iron compounds of the present invention into an aqueous solution, the one or more iron compounds should have a 

### suitable particle size that facilitates a higher degree ofreac tivity when placed into contact with a ?ue, or combustion, gas. In one embodiment, both ofthese conditions canbemet, whether individually or in combination, by one or more iron compounds where at least about 95% of the particles have a 

### particle size of less than about 400 um (microns), where at least about 95% of the particles have a particle size of less thanabout 350 um (microns), where at least about 95% ofthe 

### particles have a particle size of less than about 300 um (mi crons), where at least about 95% of the particles have a 

### particle size of less than about 250 um (microns), where at least about 95% of the particles have a particle size of less than about 200 um (microns), or even where at least about 95% oftheparticleshave aparticle size ofless thanabout 175


### um (microns). Here, as well as elsewhere in the speci?cation and claims, individual range values canbe combined to form additional and/or non-disclosed ranges.



### Althoughnot limitedhereto, a suitable iron compound for


### use in conjunction with the present invention is iron (II) 

### carbonate available from PrinceAgri 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% ofits particles are less than 200 um 

### (microns) in size.Additionally, the concentration ofiron (II) carbonate in this product is about 80% by weight with sub 

### stantially all ofthe remaining 20 weight percent being non reactive in light ofthe use here.

In the instance where an aqueous suspension is utilized in conjunctionwith 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 iron com pounds ofthepresent invention shouldhaveapurity ofat least 

### about 50 weight percent, at least about 55 weight percent, at least about 60 weight percent, at least about 65 weight per cent, at least about 70weightpercent, at least about 75 weight percent, at least about 80 weight percent, at least about 85

## US 8,716,169 B2 13 weightpercent, at leastabout 90weightpercent, at leastabout 95 weightpercent, or even at least about 99 weightpercent 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-disclosed ranges.

As for the portion ofthe one ormore iron compounds that is not “an iron compoun ,” such impurities should be non 

### reactive in the environments present in conjunction with the 

### present invention. Alternatively, ifreactive, such impurities shouldeitherbeeasilycaptured, removedand/orsequestered,

or shouldnot add signi?cantlyto any furthercontaminationof 

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

### amount of phosphorus-containing compound impurities in
any of the one or more iron compounds that are utilized in 

### conjunction with the present invention should be less than 

### about 5 weight percent, less than about 2.5 weight percent, 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 per cent. 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 still yet another embodiment, the amount of phosphorus-containing com pound impurities in any ofthe one or more iron compounds that are utilized in conjunction with the present invention should be zero. That is, in this embodiment the one or more 

### iron compounds that are utilized in conjunction with the 

### present invention should be free from any phosphorus-con 

## taining compounds.

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

### believed that thepresent invention exploits various preferen 

### tial reactions betweenphosphorous compounds, orphospho 

### rus-containing compounds, to sequestervariousphosphorous compounds, 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 inventionbe 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 ofan SCR cata 

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

(a) providing at least one coal-based fuel to a fumace, or



### boiler; (b) subjecting the at least one coal-based fuel to a staged



### combustion process, wherein the staged combustion process produces at least one gaseous phosphorus com pound and/or at least one gaseous phosphorus-contain 

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

bustion zone ofa furnace, orboiler, prior to entry ofthe ?ue gas into an SCR, wherein the SCR is located upstream ofat least one air heater; and 

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

react with the at least one gaseous phosphorus com pound and/or the at least one gaseous phosphorus-con taining compoundpresent inthe combustion zoneor ?ue 20

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65 

## 14
gaspriorto the entry ofthe ?ue gas into the SCRto form


### an ironphosphorus-containing compound. 2. The method of claim 1, wherein the iron-bearing com poundis selected from one ormore ironhalides,metallic iron,

one ormore iron oxides, iron carbonate, ormixtures oftwo or
more thereof.

3. The method of claim 1, wherein the iron-bearing com 

### pound is selected from iron (III) oxide, iron (II) carbonate, iron (II) oxide, or mixtures of two or more thereof.

4. The method of claim 1, wherein the iron-bearing com 

### pound is selected from iron (III) oxide, iron (II) carbonate, or
a mixture thereof.

5. The method of claim 1, wherein the at least one iron 

### bearing compound is provided to the combustion zone via addition to pulverized coal.

6. The method of claim 1, wherein the at least one iron bearing compound is provided to the combustion zone via a 

### dedicated supply line.

7. The method of claim 1, wherein the iron-bearing com 

### pound is a water soluble iron-bearing compound.

8. The method of claim 1, wherein the iron-bearing com 

### pound is a water soluble iron-bearing compound that is sup plied in the form ofan aqueous solution.

9. The method of claim 1, wherein the iron-bearing com 

### pound is a water insoluble iron-bearing compound that is supplied in the form ofan aqueous suspension or emulsion.



### 10. Themethod ofclaim 1, whereinthe staged combustion process utilizes over ?re air and the staged combustion pro
cess results in an increased amount ofthe at least one gaseous 

### phosphorus compound and/or the at least one gaseous phos 

### phorus-containing compound and results in the deactivation ofthe SCR catalyst.

11. A method for increasing the active life of an SCR 

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

(i) providing at least one coal-based fuel to a furnace, or



### boiler; (ii) subjecting the at least one coal-based fuel to a staged



### combustion process, wherein the staged combustion process produces at least one gaseous phosphorus com pound and/or at least one gaseous phosphorus-contain 

## ing compound; (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

react with the at least one gaseous phosphorus com pound and/or the at least one gaseous phosphorus-con 

### taining compoundpresent in the combustion zoneprior to the entry ofthe ?ue gas into an SCR to form an iron 

### phosphorus-containing compound, wherein the SCR is located upstream ofat least one air heater, whereinthe iron-bearing compound is selected from one or



### more iron (II)halides, iron (III)halides, iron (III) iodate, iron (III) oxide, iron (II) carbonate, ormixtures oftwo or
more thereof. 12. The method of claim 11, wherein the at least one 

### iron-bearing compound is provided to the combustion zone via addition to pulverized coal.

13. The method of claim 11, wherein the at least one 

### iron-bearing compound is provided to the combustion zone via a dedicated supply line either in aqueous or in powdered form.



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

### compound is a water soluble iron-bearing compound.

15. The method of claim 11, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.

## US 8,716,169 B2 15 16. The method of claim 11, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.



### 17. The method of claim 11, wherein the staged combus tion process utilizes over ?re air and the staged combustion
process results in an increased amount of the at least one gaseous phosphorus compound and/or the at least one gas 

### eous phosphorus-containing compound and results in the 

### deactivation ofthe SCR catalyst.

18. A method for sequestering one or more gaseous phos 

### phorus compounds, or gaseous phosphorus-containing com pounds, in the form of one or more less reactive iron-phos 

### phorus-containing compounds, the method comprising the steps of: (A) providing at least one coal-based fuel to a fumace, or



### boiler; (B) subjecting the at least one coal-based fuel to a staged



### combustion process, wherein the staged combustion process produces at least one gaseous phosphorus com pound and/or at least one gaseous phosphorus-contain 

## ing compound; (C) providing at least one iron-bearing compound to a

combustion zone of a fumace, or boiler; and 

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

react with the at least one gaseous phosphorus com pound and/or the at least one gaseous phosphorus-con taining compoundpresent inthe combustion zoneor ?ue gas to form one or more less reactive iron-phosphorus 

## containing compounds. 19. The method of claim 18, wherein the iron-bearing compound is selected from one or more iron halides, iron iodate, metallic iron, one ormore ironoxides, iron carbonate,

or mixtures of two or more thereof.



### 20. The method of claim 18, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (ll) carbon ate, iron (ll) oxide, or mixtures oftwo or more thereof.



### 21. The method of claim 18, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (ll) carbon ate, iron (ll) bromide, iron (Ill) bromide, or a mixture oftwo

or more thereof.

22. The method of claim 18, wherein the at least one 

### iron-bearing compound is provided to the combustion zone via addition to pulverized coal.

23. The method of claim 18, wherein the at least one 

### iron-bearing compound is provided to the combustion zone via addition to raw coal which is thereafter pulverized.

24. The method of claim 18, wherein the at least one 

### iron-bearing compound is provided to the combustion zone via a dedicated supply line.

25. The method ofclaim 18, wherein the one ormore less 

### reactive iron-phosphorus-containing compounds furthercon tains oxygen.



### 26. The method of claim 18, wherein the iron-bearing 

### compound is a water soluble iron-bearing compound.

27. The method of claim 18, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 28. The method of claim 18, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.



### 29. The method of claim 18, wherein the staged combus tion process utilizes over ?re air and the staged combustion process results in an increased amount of the at least one gaseous phosphorus compound and/or the at least one gas eous phosphorus-containing compound and results in an increased acid gas concentration in the ?ue gas. 20

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## 16 30. A method for increasing the active life of an SCR 

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

### method comprising the steps of:

providing at least one coal-based fuel to a fumace, or



### boiler; subjecting the at least one coal-based fuel to a staged com



### bustionprocess, wherein the staged combustionprocess 

### produces at least one gaseous phosphorus compound and/or at least one gaseous phosphorus-containing com 

## pound; providing at least one iron-bearing halide compound to a

combustion zone ofa furnace, orboiler, prior to entry of the ?ue gas into an SCR; 

### permitting the iron portion ofthe at least one iron-bearing

halide compound to react with the at least one gaseous phosphorus compound and/or the at least one gaseous 

### phosphorus-containing compound present in the com bustion zone or ?ue gas prior to the entry ofthe ?ue gas into the SCR to form an iron phosphorus-containing 

### compound, wherein the SCR is located upstream of at least one air heater; and permitting the halide portion ofthe at least one iron-bear

inghalide compoundto reactwith any gaseous mercury 

### compounds, ormercury-containing compounds,present in the combustion zone or ?ue gas. 

### 31. The method of claim 30, wherein the iron-bearing 

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

### bromide), iron (11) chloride, iron (Ill) chloride, iron (ll) iodide, iron (Ill) iodate, or mixtures of two or more thereof.



### 32. The method of claim 30, wherein the iron-bearing 

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

33. Themethod ofclaim 30, 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.



### 34. Themethod ofclaim 30, further comprising supplying iron (ll) carbonate in combination with the at least one iron 

### bearing halide.

35. Themethod ofclaim 30, further comprising supplying iron (11) carbonate in combination with one or more of iron 

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



### 36. The method of claim 30, wherein the iron-bearing 

### compound is a water soluble iron-bearing compound.

37. The method of claim 30, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 38. The method of claim 30, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.

39. The method of claim 30, wherein the at least one 

### iron-bearinghalide compound is provided to the combustion

zone via addition to raw coal which is thereafter pulverized.



### 40. The method ofclaim 30, wherein the staged combus tion process utilizes over ?re air and the staged combustion process results in an increased amount of the at least one gaseous phosphorus compound and/or the at least one gas 

### eous phosphorus-containing compound and results in the 

### deactivation ofthe SCR catalyst.

41. A method for sequestering one ormore gaseous phos 

### phorus compounds, or gaseous phosphorus-containing com pounds, in the form of one or more less reactive iron-phos 

### phorus-containing compounds while concurrently sequestering mercury, the method comprising the steps of:

## US 8,716,169 B2 17 providing at least one coal-based fuel to a furnace, or



### boiler; subjecting the at least one coal-based fuel to a staged com



### bustionprocess, wherein the staged combustionprocess 

### produces at least one gaseous phosphorus compound and/or at least one gaseous phosphorus-containing com 

## pound; providing at least one iron-bearing halide compound to a

combustion zone of a fumace, or boiler; and 

### permitting the iron portion ofthe at least one iron-bearing

compound to react with the at least one gaseous phos 

### phorus compound and/or the at least one gaseous phos 

### phorus-containing compoundpresent inthe combustion

zone or ?ue gas to form one or more less reactive iron 

### phosphorus-containing compounds; and permitting the halide portion ofthe at least one iron-bear

inghalide compoundto reactwith any gaseous mercury 

### compounds, ormercury-containing compounds,present in the combustion zone or ?ue gas. 

### 42. The method of claim 41, wherein the iron-bearing 

### halide compound is selected from iron (11)bromide, iron (Ill) 

### bromide, iron (11)chloride, iron (Ill)chloride, iron (11) iodide, iron (Ill) iodate, or mixtures of two or more thereof.



### 43. The method of claim 41, wherein the iron-bearing halide compound is one or more of iron (11) bromide or iron 

### (Ill) bromide.

44. Themethod ofclaim 41, 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 (11) oxide, or mixtures of two or more thereof.



### 45. Themethod ofclaim 41, further comprising supplying iron (ll) carbonate in combination with the at least one iron 

### bearing halide.

46. Themethod ofclaim 41, further comprising supplying iron (11) carbonate in combination with one or more of iron 

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



### 47. The method of claim 41, wherein the iron-bearing 

### compound is a water soluble iron-bearing compound.

48. The method of claim 41, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 49. The method of claim 41, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.

50. The method of claim 41, wherein the at least one 

### iron-bearinghalide compound isprovided to the combustion

zone via addition to raw coal which is thereafter pulverized. 20

25

30

35

40

45 

## 18 51. The method ofclaim 41, wherein the staged combus tion process utilizes over ?re air and the staged combustion process results in an increased amount of the at least one gaseous phosphorus compound and/or the at least one gas eous phosphorus-containing compound and results in an increased acid gas concentration in the ?ue gas.

52. A method for increasing the active life of an SCR 

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

providing at least one coal-based fuel to a fumace, or



### boiler; subjecting the at least one coal-based fuel to a staged com



### bustionprocess, wherein the staged combustionprocess 

### produces at least one gaseous phosphorus compound and/or at least one gaseous phosphorus-containing com 

## pound; providing at least one iron-bearing compoundto a combus

tion zone ofa furnace, orboiler, prior to entry ofthe ?ue gas into an SCR via the addition of the at least one 

### iron-bearing compound to pulverized coal, wherein the SCR is located upstream ofat least one air heater; and permitting the at least one iron-bearing compound to react

with the at least one gaseous phosphorus compound and/or the at least one gaseous phosphorus-containing compound present in the combustion zone or ?ue gas prior to the entry ofthe ?ue gas into the SCR to form an 

### ironphosphorus-containing compound, wherein the at least one iron-bearing compound is selected



### from iron (Ill) oxide, iron (11) carbonate, iron (ll) oxide,

or mixtures of two or more thereof. 

### 53. The method of claim 52, wherein the iron-bearing 

### compound is a water soluble iron-bearing compound.

54. The method of claim 52, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 55. The method of claim 52, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.

56. The method of claim 52, wherein the at least one 

### iron-bearing compound is provided to the combustion zone via addition to raw coal which is thereafter pulverized.



### 57. The method ofclaim 52, wherein the staged combus tion process utilizes over ?re air and the staged combustion process results in an increased amount of the at least one gaseous phosphorus compound and/or the at least one gas 

### eous phosphorus-containing compound and results in the 

### deactivation ofthe SCR catalyst.

* * * * *