## US 8,691,719 B2 Page 2

(56) References Cited

U.S. PATENT DOCUMENTS
4,871,522 A 10/1989 Doyle 4,925,633 A 5/1990 Doyle 5,540,897 A 7/1996 Chu et al. 5,567,394 A 10/1996 Chu et al. 5,585,081 A 12/1996 Chu et al. 5,899,679 A 5/1999 Euzen et al. 7,741,239 B2 * 6/2010 Hartenstein et al.

.......... .. 502/25 8,124,036 B1* 2/2012 Baldrey et a1.

................ .. 423/99 2006/0245993 A1 2007/0140940 A1 2007/0154374 A1 2007/0160517 A1 2008/0107579 A1 2009/0065414 A1 2010/0273643 A1 11/2006 Magumbe et a1. 6/2007 Varma et a1. 7/2007 Johnson et al. 7/2007 Fan et al. 5/2008 Downs et al. 3/2009 Nelson et al. 10/2010 Gadgil et al.

OTHER PUBLICATIONS

VitaliV. Lissianski et al.; Utilization ofIronAdditives forAdvanced 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. Terence Ake et al.; Limestone Injection for Protection of SCR Cata 

### lyst; Riley Power, Duke Energy, Cormetech, Inc. Paper #175, 2003. 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. Virpi Kroger; Poisoning ofAutomotive Exhaust Gas Catalyst Com ponentsiThe Role of Phosphorus in the Poisoning Phenomena; Academic Dissertation, University ofOulu, Finlandi2007. 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/environmenta1/136.html. 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 ReportdatedAug. 17, 2012 in correspond ing PCT application No. PCT/US2012/039175.

* cited by examiner

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## US 8,691,719 B2 1
SYSTEMAND METHOD FOR INCREASING THE SERVICE LIFE AND/OR CATALYTIC

ACTIVITY OFAN SCR CATALYST AND CONTROL OF MULTIPLE EMISSIONS

RELATEDAPPLICATION DATA



### This patent application claims priority to and is a continu 

### ation-in-part ofUS. patent application Ser. No. 12/691,527 ?led Jan. 21, 2010 and titled “System and Method for Pro 

### tection of SCR Catalyst and Control ofMultiple Emissions,” which itselfclaimspriorityto and is anon-provisional ofUS. 

### Provisional PatentApplicationNo. 61/171,619 ?ledApr. 22, 2009 and titled “System and Method for Protection of SCR 

### Catalyst.” The complete text ofthese patent applications are 

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

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. In still another embodiment, thepresent inventionrelates to a 

### method and apparatus for increasing the service life and/or 

### catalytic activity of an SCR catalyst while simultaneously controlling various emissions.

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 availabilityofoxygenandnitrogen fromboth the air and fuel. NO,C emissions may be controlled 

### using lowNO,C combustiontechnology 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 molecularnitrogen 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?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. 20

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

### erally designed foramaximum ef?ciency ofabout 90%. This limit is not set by any theoretical limits on the capability of 

### SCRsto achievehigherlevels 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. 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 basemetal catalyst is 

### its potential to oxidize SO2 to SO3; 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 SO3 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 SO3 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 phosphorus oxide (PO) or 

### phosphorus pentoxide (P205). Additionally, it is also well known that SCR catalysts degrade over time and have to be 

### replaced periodically at a signi?cant cost and loss of gener 

### ating capacity. Ina typical 100MWe coalplantthedowntime and cost associatedwiththe replacement ofunderperforrning catalyst canbe in the neighborhood ofonemillionUS dollars

or more.

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

## US 8,691 ,719 B2 3 recycling the used catalyst is theprocess called regeneration washing orrejuvenation. The initial steps ofthe regeneration process involve the removal ofthese toxic chemicals by pro 

### cessingthecatalysts 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 evenpure biomass combustionpower 

### plants will suffer from phosphorus contamination of their 

### SCR catalysts.



### 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 limitedto, 

### 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 increase catalytic life span and/or catalytic activity of an SCR catalyst while permitting, in some instances, the simultaneous removal ofvarious gaseous com 

### pounds (e.g., phosphorus or mercury) from a combustion
process.

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 

### thepresent invention is designed to protect the SCR catalyst. In still another embodiment, thepresent inventionrelates to a 

### method and apparatus for increasing the service life and/or 

### catalytic activity of an SCR catalyst while simultaneously controlling various emissions.

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; (b) permitting the at least one iron-bearing com 

### pound to react with any gaseous phosphorus compounds, or 

### phosphorus-containing compounds, present in the combus tion zone or ?ue gas prior to the entry ofthe ?ue gas into the 

### SCR; (c)providingat least onehalide-bearing compoundto a combustion zone or ?ue gas stream of a furnace, or boiler, 

### priorto entry ofthe ?ue gas into an SCR, withtheproviso that 

### halide-bearing compound is not an iron halide; and (d) per mittingthe at leastonehalide-bearing compoundtoreactwith and/or oxidize anymercurypresent inthe combustion zone or ?ue gas, wherein the method achieves an increase in either 

### one, orboth, ofa catalytic activity and/or a catalytic lifespan ofat least about 10 percent at an operational time ofat least 

### about 2,000 hours.



### 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 compoundto a combustion zone or ?ue gas stream ofa fumace, orboiler, priorto entry ofthe ?ue gas 

### into an SCR; (ii) permitting the at least one iron-bearing 20

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## 4 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; (Iii) providing at least one halide-bearing com pound to a combustion zone or ?ue gas stream ofa furnace, or 

### boiler, prior to entry of the ?ue gas into an SCR, with the 

### proviso that halide-bearing compound is not an iron halide; 

### and (iv) permitting the at least one halide-bearing compound to react with and/or oxidize any mercury present in the com bustion zone or ?ue gas, wherein the method achieves an increase in either one, orboth, ofa catalytic activity and/or a 

### catalytic lifespanofat leastabout 10percentat anoperational time ofat least about 3,000 hours.



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

### more phosphorus compounds, or phosphorus-containing compounds, in the form of one or more less reactive iron 

### phosphorus-containing compounds, and oxidizing mercury, themethodcomprisingthe steps of: (A)providingat least one iron-bearing compound to a combustion zone or ?ue gas stream ofa fumace, orboiler; (B) permitting the at least one 

### iron-bearing compoundtoreactwithanygaseousphosphorus 

### compounds, or phosphorus-containing compounds, present in the combustion zone or ?ue gas to form one or more less 

### reactiveiron-phosphorus-containingcompounds; (C)provid ing at least one halide-bearing compound to a combustion

zone or ?ue gas stream ofa furnace, orboiler, priorto entry of 

### the ?ue gas into an SCR, withthe proviso thathalide-bearing 

### compoundisnot anironhalide; and (D)permittingtheat least
one halide-bearing compound to react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or 

### both, of a catalytic activity and/or a catalytic lifespan of at least about 10 percent at an operational time ofat least about 

### 4,000 hours.

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

### more phosphorus compounds, or phosphorus-containing compounds, in the form of one or more less reactive iron 

### phosphorus-containing compounds, and oxidizing mercury, themethod comprising the steps of: (I) providing at least one iron-bearing compound to a combustion zone or ?ue gas stream ofa fumace, orboiler; (II) permitting the at least one 

### iron-bearing compoundtoreactwithanygaseousphosphorus 

### compounds, or phosphorus-containing compounds, present in the combustion zone or ?ue gas to form one or more less 

### reactive iron-phosphorus-containing compounds; (III) pro viding at least onehalide-bearing compound to a combustion

zone or ?ue gas stream ofa furnace, orboiler, priorto entry of 

### the ?ue gas into an SCR, withthe proviso thathalide-bearing 

### compound is not an iron halide; and (IV) permitting the at least one halide-bearing compound to react with and/or oxi dize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or 

### both, of a catalytic activity and/or a catalytic lifespan of at least about 15 percent at an operational time ofat least about 

### 3,000 hours.

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 less reactive iron-phosphorus-containing 

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

### compoundtoreactwithanygaseousphosphorus compounds,
or phosphorus-containing compounds, present in the com

## US 8,691,719 B2 5
bustion zone or ?ue gas to form one or more less reactive 

### iron-phosphorus-containing compounds; providing at least

one halide-bearing compound to a combustion zone or ?ue gas stream ofa furnace, orboiler, priorto entry ofthe ?ue gas 

### into an SCR, with theproviso that halide-bearing compound is not an iron halide; and permitting the at least one halide 

### bearing compound to react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or both, of a 

### catalytic activity and/or a catalytic lifespan ofat least about 15 percent at anoperational time ofat leastabout 4,000hours.



### 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

FIG. 1 is a schematic representation ofa typical fossil fuel burning facility with an SCR system, and which includes a 

### system for practicing the methods of the present invention; and

FIG. 2 is a graph illustrating one example ofan increase in 

### catalytic activity and catalytic lifespanas realizedviautiliza tion ofa system andmethod in accordance with one embodi ment ofthe 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 inventioncanbeused inany systemwhichuses an ammoniacal compound.As used in the present disclosure, anammoniacal 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 thepresent invention is described inrelation 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 be used in combinationwitha kiln, a heater, orany 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 in FIG. 1, the present invention may be applied to a boiler installation which employs a wet ?ue gas desulfurization (WFGD or wet scrubber) for removal of sul fur oxides from the ?ue gases, as shown in the upper right hand side ofFIG. 1. Inthis con?guration, thewet scrubber is 

### typicallypreceded (withrespectto adirectionof?uegas ?ow 

### throughthe system)by aparticulate collectiondevice (PCD), advantageously a fabric ?lter (FF) bag house, or an electro 

### static precipitator (ESP). If desired, there may also be pro vided a wet electrostatic precipitator (wet ESP or WESP) which may be provided as a ?nal “polishing” stage for ?ne 20

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## 6 particulate or SO3. Alternatively, the present invention may be appliedto a systemwhich employs a spraydryerapparatus (SDA) or dry scrubber for removal of sulfur oxides from the ?ue gases, as shown in the lowerright-hand side ofFIG. 1. In 

### this con?guration, the SDA or dry scrubber is typically fol lowed (withrespect to a direction of?ue gas ?ow through the 

### system) by a particulate collection device (PCD), advanta geously a fabric ?lter (FF) or baghouse, an electrostatic pre cipitator (ESP) or even a wet electrostatic precipitator (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 P205. As such, the present invention is not limited to any one type ofSCR 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 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.

In one embodiment, phosphorus 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 releasegas phasephosphorus by the following reaction:
P205(solidphase compounds)+3C(s)—>2PO(g)+ 3CO(g). 

### This gas phase phosphorus 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/or eliminating 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.

Inanotherembodiment, thepresent inventionis directedto 

### a system andmethod designed to increase the catalytic activ 

### ity and/or catalytic life span. In this case, the increase in catalytic activity and/or increase in catalytic life span is mea 

### sured against a standard, orknown, rate ofdecline incatalytic 

### activity and/or life for a given a boiler, fossil fuel boiler, kiln, heater, or any other type ofdevice that generates a ?ue gas or 

### combustion gas containing NOX.

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 (FeZO3), also known as red iron oxide orhematite. 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:

## US 8,691,719 B2 7
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 generateddueto 

### 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 furnace, 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 a combination of one or more iron-containing com pounds and one ormore halide compounds, with the proviso that the halide containing compound is not an iron halide. Thus, in this embodiment at least one iron-containing com pound is utilized in conjunction with at least one non-iron 

### halidecontaining compound. Instillanotherembodiment, the at least one iron compound has a generic formula of AX, whereA is equal to iron and X is either an oxide or carbonate 

### ion, anion, group, and/or moiety and the at least one halide compoundhas a generic formula ofBYwhere B is any atom, element, or cation except for iron andY is a halide selected 

### from chlorine, bromine, ?uorine, or iodine.

In one embodiment, suitablehalides foruse in conjunction with the present invention include, but are not limited to, 

## potassiumbromide, potassium chloride, potassium ?uoride, potassium iodide, sodiumbromide, sodium chloride, sodium ?uoride, sodium iodide, calciumbromide, calcium chloride, calcium ?uoride, calcium iodide, aluminumbromide, alumi
num chloride, aluminum ?uoride, aluminum iodide, other 

### transition metal halides (e.g., bromides, chlorides, ?uorides and/or iodides)withtheproviso that thetransitionmetal isnot iron, or any mixture of two or more thereof. In still another embodiment, any one or more halide compounds in accor dance with the proviso de?ned above can be used in combi nation with one or more non-halide containing iron com 

### pounds (e.g., iron (II) carbonate). In still another embodiment, the present invention utilizes a combination of iron (II) carbonate with calcium bromide to control the amount ofphosphorus in a ?ue gas, or combustion gas while 

### concurrently permitting both the control of mercury com pounds, or mercury-containing compounds, in a ?ue gas, or 

### combustion gas and the increase in catalytic activity and/or service life. In still yet another embodiment, the present invention utilizes a combination of iron (II) carbonate with calcium chloride to control the amount ofphosphorus ina ?ue 

### gas, or combustion gas while concurrently permitting both 

### the control of mercury compounds, or mercury-containing compounds, in a ?ue gas, or combustion gas and the increase 

### in catalytic activity and/or service life. In still yet another embodiment, the present invention utilizes a combination of iron (II) carbonate with either one, or both, of aluminum bromide and/or aluminum chloride to control the amount of phosphorus in a ?ue gas, or combustion gas while concur 

### rentlypermitting both the control ofmercury compounds, or mercury-containing compounds, in a ?ue gas, or combustion gas andthe increase incatalytic activityand/or service life.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 anotherembodiment, thepresent inventionis 

### directed to concurrently permitting the control of mercury 20

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## 8 compounds, ormercury-containing compounds, that contain primarily, or only, oxidizedmercury.

As used herein, any iron compound suitable for use in conjunction with the present invention can be utilized in a 

### hydratedornon-hydrated form.As such, referenceto any iron 

### compound hereinby de?nition includes any hydrated forms that exists whether ornot speci?callymentionedby chemical formula.

As is known in the art, (see, e.g., United States Patent Application PublicationNo. 2008/0107579 the text ofwhich 

### is hereby incorporatedby 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.

In any ofthe above embodiments, the suitable one ormore iron-bearing compounds, and if so desired the one or more halide compounds, can be added to the coal via one or more pulverizers. In still another embodiment, the one or more iron-bearing compounds, and if so desired the one or more halide compounds, of the present invention can be added to the combustion zone of a boiler and/or fumace via one or more suitable supply lines designed to deliver a powderized, 

### solid, aqueous suspension, suspension, oraqueous solutionof the one or more iron-bearing compounds and/or the one or
more halide compounds to the combustion zone ofa furnace and/or boiler. To this end, FIG. 1 illustrates several embodi 

### ments of suitable design schemes for accomplishing this result.

Referring to FIG. 1, there is illustrated a schematic repre 

### sentation of a typical fossil fuel burning facility, generally designated 10, with an SCR system, and which includes a 

### systemforpracticingthemethods ofthepresent invention.As 

### shown, boiler 12 is provided for extracting the heat from the combustion ofa fossil fuel, such as coal, through combustion 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 generator apparatus (not shown) or for industrial processes and/orheat 

## ing.

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 FIG. 1, there are 

### six (6) coal pulverizers, identi?edas coal pulverizersA-F.As is known to those skilled in the art, each coal pulverizer 20 

### grinds the coal to a desired ?neness (e.g., 70% through 200 

### mesh) and as it is ground, hot primary air from primary air 

### fans (not shown) is conveyed into each coal pulverizer 20 to preheat andremovemoisture fromthe coal to desiredlevels as 

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

## US 8,691 ,719 B2

it along a plurality ofpulverized coal supply lines (one such burner line is identi?edatA inFIG. 1; a single coalpulverizer 

### 20may supplycoal through 4-8pulverizedcoal supply lines)
to the burners 22 on the front and rear walls ofthe 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 comers of the boiler in installations known as 

### corner-?red or tangentially-?red units (not shown). The present invention can be utilized in conjunction with, but is 

### notlimited solelyto, single-wall ?red, opposed-wall ?redand

corner- or tangentially-?red units. Typically, a single coal 

### pulverizer 20 only provides coal to a single elevation of bumers 22 on awall. Thus, in the embodiment shown in FIG. 

### 1, the six coal pulverizers A-F supply corresponding burner elevations A-F. However, as is known to those skilled in the 

### art, other pulverizer and burner con?gurations are known 

### (e.g., single pulverizers supplying bumers onmultiple walls and/or elevations or multiple pulverizers supplying bumers

on a single elevation) and thepresent inventionapplies 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 FIG. 1, and downstream ofthe airheaters 

### 42, the ?ue gas 28 undergoes further treatment for the removal ofparticulates and sulfur oxides. Two typical con 

### ?gurations of the downstream equipment employed to accomplish these tasks are shown on the right-hand side of FIG. 1. The upper equipment con?guration in FIG. 1 com 

### prises a particulate collection device (PCD) schematically indicated at 44, for removal ofparticulates from the ?ue gas 28, and which may comprise in practice a fabric ?lter or an 

### electrostatic precipitator. 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 (option ally) be conveyed through a wet ESP 47 for removal of ?ne 

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

### charge to the atmosphere.

The lower equipment con?guration in FIG. 1 comprises a 

### spray dryer apparatus (SDA) schematically indicated at 50, also known as a dry scrubber, for removal of sulfur oxides from the ?ue gas 28. Downstream of the SDA 50 there is 

### provided a particulate collection device (PCD) 44, as described above, forremoval ofparticulates fromthe ?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 thatno combustionprocess is 100% e?icient, 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 20

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## 10

zone 24, areducing atmosphere is created inthe lowerportion 

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

Inaccordancewitha ?rst embodiment ofthepresent inven tion, one ormore suitable iron-bearing compounds, and if so desired one or more suitable halide compounds, are added to the one or more coal pulverizers 20 prior to supplying the pulverizedcoal to the one ormoreburners 22. The system and 

### apparatus for accomplishing this desiredresult is also shown in FIG. 1, generally designated 100. The system 100 com prises a storage means 120 for temporarily storing the iron based phosphorus reduction compound, and if so desired the 

### mercury reducing 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 storage means as required. 

### Although not illustrated individually, the system of the present invention can, in one embodiment, utilize indepen 

### dent storage, delivery and controlmeans (in accordance with those described above) for each individual iron and/orhalide 

### compound. In still another embodiment, the system of the present invention can comprise one set of storage, delivery and control means for the iron compounds or compounds utilized herein and one set of storage, delivery and control


### means (in accordance with those described above) for the 

### halide compound or compounds utilized herein.

In FIG. 1, the raw coal 14 to which the iron-based phos 

### phorus reducing compound 110 has been added is referredto


### as 140.Advantageously, the iron-basedphosphorus reducing compound 110 may be provided along with the raw coal 14 via the feeder 18, which permits close control and measure ment of the delivery of both raw coal 14 and iron-based 

### phosphorus reducing compound 110 into the coal pulverizer 20. Alternatively, the iron-based phosphorus reducing com 

### pound 110 may be provided directly into the coal pulverizer 20 and/or directly into one or more individual burner lines 

### A-F providing the pulverized coal to individual burners 22, 

### with suitable sealing devices against the positive pressure withinthe coalpulverizer 20 orburner linesA-F. Thedelivery
means may be slurry-based or pneumatic as required by the 

### particulars ofthe iron-basedphosphorus 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, iron-based phosphorus 

### reducing compound 110 level signals, and phosphorus level signals in the ?ue gas 28 (from a sensor 200) to permit the 

### introduction of the iron-based phosphorus reducing com pound 110 into the ?ue gas 28 to be controlled by a human 

### operator, or automatically controlled. However, ifa suitable, real-time sensor 200 for measuring levels of gaseous phos 

### phorus inthe ?uegas 28 isnot available, ?uegas samplesmay insteadbe takenat the location 200 for later laboratory analy sis via suitable test methods, which may be inductively 

### coupled plasma-mass spectrometry (ICP-MS). Based upon 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 iron-based phos 

### phorus reducing compound 110 introduced into the ?ue gas 28. Providedthat subsequent laboratory analyses do not indi cate any signi?cantvariation ingaseous phosphorus levels in the ?ue gas 28, there may be no need for real-time, close 

### control ofthe introductionofiron-basedphosphorusreducing 

### compound 110. Instead, the amount of iron-based phospho

## US 8,691,719 B2 11

rus reducing compound 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, thepresent 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. In particular, the iron-based phosphorus reduction compound can be supplied at one or more ofthe locations G 

### through Q shown in FIG. 1. Moreparticularly, the iron-based phosphorus reduction compound can also be provided into the ?ue gas 28 at one or more ofthe 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 or more of the 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. Given the above, it should be noted that in addition to the introduction ofthe one ormore iron-basedphosphorus reduc 

### tioncompounds, theabove-mentioned systems,methodsand/

or control apparatuses and/or technologies can also be uti lized to introduce one or more halide compounds in accordance with the present invention as detailed above. Thus, in one embodiment, thepresent invention is directed to
a system whereby both one or more iron-based compounds and one or more halide compounds are supplied in any man nerper the various methods and/or systems describedherein. Inanother embodiment, eachtype ofcompound, or even each 

### separate compound regardless oftype, canbe supplied indi vidually. Instill anotherembodiment, anycombinationoftwo
ormore compounds regardless oftype (i.e., whether an iron based compound or a halide compound) can be supplied together so long as the one compound does not react detri 

### mentally with the other compound.

Furthermore, giventhe above, thereduced iron, or iron (II) oxide, ofthepresent inventionis ableto remove the gasphase 

### phosphorus inthe formofiron-phosphorusalloyswhichupon coming in contactwiththe over ?re air from iron-phosphorus 

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

### gas phase phosphorus accumulation in an SCR catalyst. 

### Another advantage of the present invention is that through addition of iron a signi?cant portion of any phosphorus present will be iron-bound. Iron-bound phosphorus com 

### pounds are less leachable thereby minimizing the transfer of 

### phosphorus 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 embodi ment, directed to the situation where a majority ofthe phos 

### phoruspresent inthe combustionand/or ?ue streamis seques tered in a suitable iron-phosphorus-oxygen-containing 

### compound thereby substantially reducing the amount ofcal cium/phosphorus/oxygen-containing compounds that are 20

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## 12 able to react with SOX. This in turn substantially reduces the amount of gaseous phosphorus that is produced in the com 

### bustion and/or ?ue gas stream by restricting the amount of 

### calcium/phosphorus/oxygen-containing compounds that are present in the combustionand/or ?ue gas stream to reactwith 

### various SO,Ccompoundsresulting intheunwantedproduction of gaseous phosphorus compounds, or phosphorus/oxygen compounds, that can lead to the undesired poisoning of an 

### SCR catalyst.

In still another embodiment, the iron-bearing compounds and/or halide compounds of the present invention can be added in any suitable manner, including the manner detailed 

### in the FIG. 1. Suitable iron-bearing compounds include, but
are not limited to, aqueous and soluble forms ofiron-bearing compounds such as metallic iron, one or more iron oxides, iron carbonate, or mixtures of two or more thereof. Suitable 

### halide compounds include, but are not limited to, potassium 

## bromide, potassium chloride, potassium ?uoride, potassium iodide, sodium bromide, sodium chloride, sodium ?uoride, sodium iodide, calcium bromide, calcium chloride, calcium ?uoride, calciumiodide, aluminumbromide, aluminumchlo ride, aluminum ?uoride, aluminum iodide, other transition 

### metal halides (e.g., bromides, chlorides, ?uorides and/or iodides) with theproviso that the transitionmetal is not iron,

or any mixture of two or more thereof. If an existing skid is used then one or more aqueous reagents 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 coalpasses ona feederbeltupstream ofthepulverizers. In this instance, ifso utilized the one ormore halide compounds

are chosen to be soluble in water, or an aqueous-based sol vent. Suitable halides soluble halides include, but are not 

### limited to, potassium bromide, potassium chloride, potas sium ?uoride, potassium iodide, sodium bromide, sodium chloride, sodium ?uoride, sodium iodide, calcium bromide, calcium chloride, calcium iodide, aluminumbromide, alumi

num chloride, aluminum iodide, or any mixtures of two or more thereof. In still another embodiment, other transition 

### metal halides (e.g., bromides, chlorides, ?uorides and/or iodides) that are not iron halides can be utilized so long as such compounds are, inthis embodiment, soluble inwater, or an aqueous-based solvent.



### 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 doesnot 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. In one embodiment, the present invention is directed to a method and system whereby a stoichiometric

excess one ormore iron compounds are supplied to any point prior to an SCR. While not wishing to be bound to any one 

### theory, it has been found that by supplying a stoichiometric
excess of iron upstream of an SCR, the catalytic activity 

### and/or catalytic lifespan ofan SCR catalyst canbeunexpect edly increased. As can be seen from the graph ofFIG. 2, the addition ofa stoichiometric excess ofone ormore iron-based 

### compounds not only protects the SCR catalyst from poison ing via various phosphorus compounds but also increases boththe catalytic activity and catalytic lifespan overaperiod ofat least about 2,000 operational hours.

## US 8,691,719 B2 13 Regarding FIG. 2, FIG. 2 is a graph plotting the original expecteddeactivation foracatalystwithoutthe additionofthe 

### iron-bearing compound, or compounds, ofthepresent inven tionversus the actual deactivation ofa catalyst with the addi 

### tion of an iron-bearing compound of the present invention

versus the observed deactivation of a catalyst without the 

### addition ofthe iron-bearing compound, orcompounds, ofthe present invention. The y-axis ofthe graph ofFIG. 2 is cata 

### lytic activity in decimal terms where 0.9 is equivalent to 90 

### percentactivityasmeasuredwhencomparedtounusedvirgin catalyst as determined using any suitable method for deter 

### mining catalytic activityknownto thoseofskill intheart. The x-axis of the graph of FIG. 2 is the number of operational 

### hours that the catalyst in question is exposed to the average operational conditions ofa 100 MWe coal plant.

Given the above, in one embodiment the present invention achieves eitherone, orboth, ofan increase incatalytic activity and/or an increase in catalytic lifespan via the use, introduc tionand/ordelivery ofone ormore iron-based compounds. In

one embodiment, an increase in either one, or both, of cata 

### lytic activity and/or catalytic lifespan of at least about 10 percent is achieved at an operational time of at least about 

### 2,000 hours versus the catalytic activity and/or catalytic 

### lifespan ofa given catalyst when subjected to similar opera tional conditions but not subjected to a supply ofone ormore iron-based compounds as disclosed herein. As would be apparent to those of skill in the art, various known methods

are available tomeasure the baseline catalytic activity as well


### as the catalytic activity ofvarious catalysts, including SCR catalysts. As such, a detailed discussionherein is omitted for 

### the sake ofbrevity.

In another embodiment, the present invention achieves an increase in either one, or both, of catalytic activity and/or catalytic lifespanofat least about 10percent is achieved at an 

### operational time ofabout 2,000 hours, an increase ofat least about 12.5 percent is achieved at an operational time ofabout 2,000 hours, an increase of at least about 15 percent is achieved at an operational time of about 2,000 hours, an increase ofat least about 17.5 percent is achieved at an opera tional time ofabout 2,000 hours, an increase ofat least about 20 percent is achieved at an operational time ofabout 2,000 hours, an increase ofat least about 22.5 percent is achieved at
an operational time of about 2,000 hours, an increase of at least about 25 percent is achieved at an operational time of about 2,000hours, an increase ofat least about 27.5 percent is achieved at an operational time ofabout 2,000 hours, or even
an increase of at least about 30 percent is achieved at an 

### operational time of about 2,000 hours versus the catalytic 

### activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected
to a supply ofone ormore iron-based compounds as disclosed herein. Here, as well as elsewhere in the speci?cation and claims, individual numerical values canbe combined to form additional and/or non-disclosed ranges.



### In still anotherembodiment, thepresent inventionachieves
an increase in either one, orboth, ofcatalytic activity and/or catalytic lifespanofat least about 10percent is achieved at an 

### operational time ofabout 2,500 hours, an increase ofat least about 12.5 percent is achieved at an operational time ofabout 2,500 hours, an increase of at least about 15 percent is achieved at an operational time of about 2,500 hours, an increase ofat least about 17.5 percent is achieved at an opera tional time ofabout 2,500 hours, an increase ofat least about 20 percent is achieved at an operational time ofabout 2,500 hours, an increase ofat least about 22.5 percent is achieved at
an operational time of about 2,500 hours, an increase of at least about 25 percent is achieved at an operational time of 20

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## 14 about 2,500hours, an increase ofat leastabout 27.5 percent is achieved at an operational time ofabout 2,500 hours, or even
an increase of at least about 30 percent is achieved at an 

### operational time of about 2,500 hours versus the catalytic 

### activity and/or catalytic lifespan of a given catalyst when subjected to similar operational conditions but not subjected
to a supply ofone ormore iron-based compounds as disclosed herein. Here, as well as elsewhere in the speci?cation and claims, individual numerical values canbe combined to form additional and/or non-disclosed ranges.



### In still yet another embodiment, the present invention achieves anincrease ineitherone, orboth, ofcatalytic activity and/or catalytic lifespan ofat least about 10 percent, at least about 12.5 percent, at least about 15 percent, at least about 17.5 percent, at least about 20 percent, at least about 22.5 percent, at least about 25 percent, at least about 27.5 percent,

or even at least about 30 percent is achieved at an operational 

### time ofabout 3,000 hours versus the catalytic activity and/or 

### catalytic lifespanofagivencatalystwhen subjectedto similar operational conditions but not subjected to a supply ofone or more iron-based compounds as disclosed herein. In still yet another embodiment, the present invention achieves an 

### increase in either one, or both, of catalytic activity and/or catalytic lifespan of at least about 10 percent, at least about 12.5 percent, at least about 15 percent, at least about 17.5 percent, at least about 20percent, at least about 22.5 percent, at least about 25 percent, at least about 27.5 percent, or even at least about 30 percent is achieved at an operational time of 

### about 3,500 hours, about 4,000 hours, about 4,500 hours, about 5,000 hours, about 6,000 hours, about 7,000 hours, about 7,500 hours, about 8,000 hours, about 9,000 hours, 

### about 10,000hours, about 1 1,000hours, about 12,000hours, about 13,000hours, about 14,000hours, about 15,000hours,
orevenabout 16,000hoursversus the catalytic activity and/or 

### catalytic lifespanofagivencatalystwhen subjectedto similar operational conditions but not subjected to a supply ofone or
more iron-based compounds as disclosed herein. Here, as 

### well as elsewhere in the speci?cation and claims, individual numerical values can be combined to form additional and/or non-disclosed ranges.

As is known to those of skill in the art, the phosphorus content ofcoal canbe determinedbyvarious knownmethods. 

### Thus, in this instance, the present invention is not limited to any one range ofiron compounds that areutilized. Instead, an
excess stoichiometric ratio is utilized. In one embodiment, the excess stoichiometric ratio ofiron to phosphorus is in the range ofabout 2.5:1 to about 10: 1, or from about 3:1 to about 9:1, or from about 3.5:1 to about 8:1, or from about 4:1 to about 7.5:1, or from about 5:1 to about 7:1, or from about 5.5:1 to about 6.5:1, or even about 6:1. 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 the range ofabout 5 pounds of “iron” per 1,000 

### pounds ofcoal to about 20pounds 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 5.5 

### pounds of “iron” per 1,000 pounds of coal to about 17.5

## US 8,691,719 B2 15 pounds of “iron” per 1,000 pounds of coal, or from about 6 

### pounds of“iron”per 1,000pounds ofcoal to about 15pounds of“iron”per 1,000pounds ofcoal, or from about 7 pounds of 

### “iron” per 1,000 pounds of coal to about 12.5 pounds of “iron” per 1,000 pounds ofcoal, or from about 7.5 pounds of “iron” per 1,000 pounds ofcoal to about 10pounds of “iron” per 1,000 pounds of coal, or even from about 8 pounds of 

### “iron” per 1,000 pounds of coal to about 9 pounds of “iron” per 1,000 pounds of coal. Here, as well as elsewhere in the speci?cationand claims, individual rangevalues canbe com bined to form additional and/or non-disclosed ranges.

In another embodiment, where both an iron-based com pound and a halide compound as de?ned above are utilized, the amount of iron-based compound, or compounds, as com pared on a weight basis to the amount of one or more halide 

### compounds is intherange ofabout 95 weightparts ironbased 

### compound, or compounds to about 5 weight parts halide 

### compound, or compounds. In another embodiment, the weight ratio of iron-based compound, or compounds, to halide compound, or compounds, is intherange ofabout 95:5 to about 75:25, or from about 93.5:65 to about 80:20, or from about 92:8 to about 82.5:17.5, or from about 91:9 to about 85:15, or even from about 90:10 to about 87.5:12.5. Thus, in

one embodiment, the amount ofthe one or more halide com pounds, if so utilized, can be calculated based on any of the above stated iron-based compound, or compounds, amounts via the ratios disclosed in this paragraph. 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 injection rate of the one or 

### morehalide compounds, ifso utilized in conjunctionwiththe present invention, for controlling mercury in a ?ue gas, or combustion gas, is based on a non-limiting example ofa 100 MWe coal powerplant. In this case, the injection rate for the

one ormore halide compounds, if in solution, is in the range ofabout 0.25 gallonsperhourto about 10 gallonsperhour, or fromabout 0.5 gallonsperhourto about 5 gallonsperhour, or even from about 1 gallonperhourto about 4 gallons perhour. 

### Inanotherembodiment, regardless ofpowerplant orcombus tion plant size, the one or more halide compounds are sup plied at any rate to a ?ue gas, or combustion gas, suf?cient to yield a concentration of halide (e.g., bromide, chloride or iodide) between about 10 ppm 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 depending upon the 

### emissions control technology inplace on the device generat ing the ?ue gas, or combustion gas, itmay be desirable to use a lower halide concentration in order to prevent any type of detrimental effects to such downstream emissions technol ogy. In one embodiment ofsuch an instance the concentration ofhalide is between about 10ppm 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 elsewhere in the speci?cation 

### and claims, individual range values (even from different embodiments) can be combined to form additional and/or non-disclosed ranges.



### In light ofthe above, one ofskill in the artwouldrecognize that the amount of one or more iron, or iron-based, com pounds necessary to supply the desired amount of iron to a ?ue gas, or combustion gas, inaccordancewiththeprocess of 

### thepresent inventionwillvary dependinguponthe size ofthe device generating such ?ue gas, or combustiongas. The same
canbe said ofthe one ormorehalide compounds. That is, one of skill in the art would recognize that the amount of one or more halide compounds necessary to supply the desired
amount ofhalide to a ?ue gas, or combustion gas, in accor 20

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## 16 dance with the process of the present invention will vary 

### depending upon the size of the 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 power plant 

### the amount ofhalide solution (25 weight percent solution) supplied to the ?ue gas, or combustion gas, is in the range of about 0.25 gallons per hour to about 6 gallons per hour, or from 0.5 gallons perhour to about 5 gallons perhour, 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 

### 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 ofhalide.

As would be apparent to one of skill in the art, other additional factors can impact the amount ofiron-based, iron 

### bearing and/or iron compounds supplied in connection with thevarious embodiments ofthepresent invention. Such addi tional factors include, but are not limited to, the amount and/or type ofphosphorus present in the coal, or other com 

### bustible fuel; the size and/or output ofthe boiler, heater, kiln,

or other ?ue gas-, or combustion gas-, generating device; and 

### the desired stoichiometric ratio to be achieved; the type and/

ormanner ofcombustion, the type and/or arrangement ofany 

### applicable equipment or structure.

In another embodiment, the one or more iron compounds and/orthe one ormorehalide compounds utilized in conjunc tion with the present invention can be of any 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. As would be apparent to those of skill in the art, each different compound, or even the same compound, canbe supplied inthe form ofone ormoreparticle geometries. In one embodiment, the one or more iron com pounds and/or the one or more halide compounds of the 

### present invention, ifwater soluble, canbe suppliedin solution form, either independently or together so long as the active components to be delivered to the ?ue, or combustion, gas do not adversely react. In such an instance, a solution concen tration of at least about 15 weight percent of one or more water soluble iron compounds and/or one or more water 

### solublehalidecompounds isutilized. Inanotherembodiment,

a solutionconcentration ofat least about 20weightpercent, at 

### least about 25 weight percent, at least about 30 weight per cent, at least about 35 weightpercent, at least about 40weight percent, at leastabout 45 weightpercent, orevenat leastabout 50 weight percent ofmore of the one or more water soluble iron compounds and/or the one or more water soluble halide 

### compounds is utilized in conjunctionwith thepresent inven tion. 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 would be appre 

### ciatedby those ofskill intheart, the solutionconcentrationof
any one ormorewater soluble iron compounds and/or the one
or more water soluble halide compounds should not, in one 

### embodiment, exceed the solubility amount, respectively, for the one ormore iron compounds and/orthe one ormore halide 

## compounds.

In still another embodiment, the one or more iron com pounds and/or the one or more halide compounds of the present invention can be supplied in a powdered form, a solution form, an aqueous suspension form, ora combination oftwo ormore thereof. In the case ofan aqueous suspension, the one ormore iron compounds and/orthe one ormore halide

## US 8,691,719 B2 17 compoundsutilized in conjunctionwiththepresent invention shouldhave a suitableparticle size.Additionally, even absent the desire to place the one ormore iron compounds and/or the

one or more halide compounds ofthe present invention into

an aqueous solution, the one ormore iron compounds and/or the one or more halide compounds should have a suitable 

### particle sizethat facilitates ahigherdegree ofreactivitywhen placed into contact with a ?ue, or combustion, gas. In one embodiment, both of these conditions can be met, whether individually or in combination, by one or more iron com pounds and/or one or more halide 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 ofthe particles have a particle 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), where at least about 95 percent oftheparticles have aparticle size ofless than about 250 um (microns), where at least about 

### 95 percent of the particles have a particle size of less than about 200 um (microns), or even where at least about 95 

### percent ofthe particles have a particle size ofless than about 175 um (microns). Here, as well as elsewhere in the speci? cationandclaims, individualrangevalues canbe combinedto 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 percent of its particles are less than 

### 200 um (microns) in size. Additionally, the concentration of iron (II) carbonate in this product is about 80 percent by 

### weightwith substantially all ofthe remaining 20 weightper cent being non-reactive in light of the use here. A suitable 

### halide compound for use, if so desired, in conjunction with thepresent invention is calciumbromide available fromTetra 

### Chemical (located in The Woodlands, Tex.).

In the instance where one or more aqueous suspensions 

### is/areutilized in conjunctionwiththepresent invention, such aqueous suspension(s) 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 lim 

### itedto, sodiumpolyacrylates, carbomers, acrylates, and inor 

### ganic thickening agents. Other suitable anti-settling, suspen sion, thickening or emulsi?cation agents are known to those ofskill in the art and as sucha discussionherein is omitted for the sake of brevity. In another embodiment, a suitable sus pension or emulsi?cation can be achieved via agitation and does not necessarily require the use of one or more anti 

### settling, suspension, thickening or emulsi?cation agents. In another embodiment, a combination of one or more anti 

### settling, suspension, thickening or emulsi?cation agents can be utilized in combination with agitation.

In still another embodiment, the one or more iron com pounds and/or the one or more halide compounds of the 

### present invention should independently have a purity of at 

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

### weightpercent, at leastabout 80weightpercent, at leastabout 85 weight percent, at least about 90 weight percent, at least about 95 weight percent, or even at least about 99 weight percent orhigher. 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. 20

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## 18
As for the portion ofthe one ormore iron compounds that is not “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/orsequestered,

or shouldnot add signi?cantlyto any furthercontaminationof 

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

### amount of phosphorus-containing compound impurities in
any ofthe one ormore iron compounds and/orthe one ormore 

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

### present invention should independently be less than about 5 

### weight percent, less than about 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 ofphosphorus-containing compound impurities in any of the one or more iron compounds and/or the one or more halide compounds that are utilized in conjunction with the present invention shouldbe zero. That is, in this embodi
ment the one ormore iron compounds and/or the one ormore 

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

### present invention should independently be free from any 

## phosphorus-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 phosphorus compounds, or phospho 

### rus-containing compounds, to sequestervarious phosphorus 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.

In another embodiment, the present invention is direct to a 

### system and method for the injection of iron carbonate, another suitable iron compound, or a blend of one or more iron compounds and one ormore non-iron-containing halide 

### compounds with coal in the furnace in order to replenish the active catalytic sites on the surface of SCR catalyst with Fe 

### active sites while simultaneously achieving mercury oxida tion. In one instance, the injection material is a blend of iron 

### carbonate (about 90 percent by weight) and a non-iron-con 

### taininghalogen compound (e.g., calciumbromide 10percent by weight). As is known to those of skill in the art, any iron that is present in coal ash (including but not limited to PRB coal ash) is not catalytically active as it bonds, or is bonded, with various silicates and/or aluminates in the coal combus tion process. In PRB coal more than 90 percent of total iron
occurs as a bondedmineral meaning that it is mostly trapped 

### in glassy silica and/or alumina compounds during the com bustion process thereby making it unavailable for any other 

### chemical reaction. Thus, the present invention, by injecting ironseparately,provides “free” ironthat,whilenotwishingto beboundto any onetheory, isbelievedto settle onto and/orbe 

### deposited onto the surface of?y ashwhichmakes it available for further chemical reactions.

This blended material that contains “free” iron as de?ned 

### above canthenprovide iron for increasing the catalytic activ 

### ityand/or catalytic lifespanofthe DeNO,C catalystwhile, ifso provided, the halogenportion ofthe one ormore halide com pounds ofthe present invention acts to aid, or achieve, mer cury oxidation. While not wishing to be bound to any one 

### theory, is believedthatwhenthe ?y ash gets deposited onthe surface of SCR catalyst the iron on the surface of ?y ash or iron deposited on catalyst as a result ofthe injection process

## US 8,691,719 B2 19 provides sites ontowhichammonia andNO,C canreact to form N2 andwater.As the ironis injected continuously at a lowrate 

### of injection, any active iron sites that become depleted are replacedby new iron sites at a reasonable rate thereby allow 

### ing for the extension and/or increase of catalytic lifespan and/or catalytic activity when compared to similaruntreated 

### catalyst as explained in detail above. The halogenportion of thehalide compound, orcompounds, oxidizes elementalmer 

### cury into its oxidized form andmake it easier forremoval by

a downstream wet or dry scrubber, or with PAC injection.

While notwishing to be bound to any one example, data to 

### support this invention is supplied from a long-term injection test ofiron carbonate at a 100 MWe coal powerplant. Before exposure ofthe catalyst to the combustion ?ue gas, the cata 

### lyst analysis by XRF technique showed negligible iron present both on the surface and in the bulk ofcatalyst. After 

### approximately 2,000 hours of operation and injection of FeCO3 a catalyst sample is obtained and analyzed by XRF. This sample shows 0.35 percent Fe on the surface and 0.13 

### percentFe inbulk. Previouslyusedcatalyst (no FeCO3 injec tion from the same site) had 0.26 percent Fe on surface and 

### 0.06percent Fe inbulkafter 11,000hours ofoperation. Base 

### line testing prior to the injection of iron carbonate indicates that the SO3 concentration is less than 1 ppm in ?ue gas at the 

### outlet of air heater. After 8,000 plus hours of operation the SO3 concentration is measured at the air heater outlet and is about 2.6ppm. Thisproves that iron injection into the furnace 

### is indeed reaching the SCR. The increase in SO3 concentra tion can be related to the presence ofiron on catalyst surface, 

### since Fe is also a good catalyst for conversion of $02 to $03.

As noted above, FIG. 2 illustrates catalyst performance with and without iron injection. The upper line plot (the one 

### with the lower case “Xs”) is the originally expected catalyst deactivation curve. This catalyst is expected to last for about 

### 16,000 hours ofoperation. The lower plot (diamonds) illus trates the actual performance for this catalyst. The catalyst 

### actually lasts for only 6,800 hours ofoperation due to phos phorus deactivation. Themiddle line (triangles) illustrates the performance ofa catalyst subjected to at least the iron com 

### pound injection ofthe present invention. The catalyst in this example is not new when it is installed but is regenerated 

### catalyst with 15 percent lower initial activity than virgin 

## catalyst.

Thus, in one embodiment, the present invention provides additional sites for the DeNO,C reactionby injection ofone or 

### more iron-bearing compounds thereby making it possible to signi?cantly improve the life and/or catalytic activity of an 

### SCR catalyst beyond presently accepted, or believed, time
spans. When utilized, the one or more halide compounds of 

### the present inventionprovide a halogen component that per mits for increased mercury oxidation and makes possible 

### mercury removal downstream by any suitable technology 

## (e.g.,AQCS equipment).

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. 20

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## 20 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 compoundto a com

bustion zone or ?ue gas stream ofthe furnace, or boiler, prior to entry of the ?ue gas into an SCR, wherein the SCR is located upstream ofat least one air heater; 

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


### an ironphosphorus-containing compound; (e) providing at least one halide-bearing compound to a

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

### boiler, priorto entry ofthe ?ue gas into an SCR, withthe 

### proviso that halide-bearing compound is not an iron 

### halide; and (f) permitting the at least one halide-bearing compound to

react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or



### both, ofa catalytic activity and/or a catalytic lifespan of at least about 10percent at an operational time ofat least 

### about 2,000 hours. 2. The method of claim 1, wherein the iron-bearing com pound is selected frommetallic iron, one ormore ironoxides, iron carbonate, or mixtures of two or more thereof.

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

### pound is selected from iron (Ill) oxide, iron (11) carbonate, iron (11) oxide, or mixtures of two or more thereof.

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

### pound is selected from iron (Ill) oxide, iron (11) 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. Themethod ofclaim 1, wherein thehalide-bearing com 

### pound is selected from potassium bromide, potassium chlo 

### ride, potassium ?uoride, potassium iodide, sodiumbromide, sodium chloride, sodium ?uoride, sodium iodide, calcium 

### bromide, calcium chloride, calcium ?uoride, calcium iodide, aluminum bromide, aluminum chloride, aluminum ?uoride, aluminum iodide, transition metal halides with the proviso that the transition metal is not iron, or any mixture of two or

more thereof or mixtures of two or more thereof.

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

### pound is selected from iron (11) carbonate and the halide 

### bearing compound is selected from calcium bromide.

9. The method of claim 1, wherein the at least one halide 

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

10. The method ofclaim 1, wherein the at least onehalide bearing compound is provided to the combustion zone via a 

### dedicated supply line.

## US 8,691,719 B2 21 11. The method of claim 1, wherein the at least one iron bearing compound is provided at an excess stoichiometric ratio of iron to phosphorus is in the range of about 2.5:1 to about 10:1.

12. The method of claim 1, wherein the at least one iron bearing compound is provided at an excess stoichiometric ratio of iron to phosphorus is in the range of about 3.5:1 to about 8:1.

13. Themethod ofclaim 1, wherein the at least onehalide 

### bearing compound is provided at suf?cient amount to yield a halide concentration ofbetween about 10 ppm to about 200
PPm~

14. The method ofclaim 1, wherein the iron-bearing com 

### pound is a water soluble iron-bearing compound. 15. The method ofclaim 1, wherein the iron-bearing com 

### pound is a water soluble iron-bearing compound that is sup plied in the form ofan aqueous solution. 16. The method ofclaim 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.

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

### bearinghalide compound is providedto the combustion zone via addition to raw coal which is thereafter pulverized. 

### 18. 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.

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

### catalyst, themethod 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 or ?ue gas stream of the furnace, or 

### boiler, priorto entry ofthe ?ue gas into an SCR, wherein the SCR is located upstream ofat least one airheater; 

### (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 inthe combustion zoneor ?ue gas priorto the entry ofthe ?ue gas into the SCR to form


### an ironphosphorus-containing compound; (v) providing at least one halide-bearing compound to a

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

### boiler, priorto entry ofthe ?ue gas into an SCR, withthe 

### proviso that halide-bearing compound is not an iron 

### halide; and (vi)permitting theat least onehalide-bearing compoundto

react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or



### both, ofa catalytic activity and/or a catalytic lifespan of at least about 15 percent at an operational time ofat least 

### about 3,000 hours. 20. The method of claim 19, wherein the iron-bearing compound is selected from metallic iron, one or more iron oxides, iron carbonate, or mixtures of two or more thereof.



### 21. The method of claim 19, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, iron (11) oxide, or mixtures oftwo or more thereof. 20

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

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, or a mixture thereof.

23. The method of claim 19, wherein the at least one 

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

24. The method of claim 19, wherein the at least one 

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



### 25. The method of claim 19, wherein the halide-bearing 

### compound is selected from potassium bromide, potassium 

### chloride, potassium ?uoride, potassium iodide, sodium bro mide, sodium chloride, sodium ?uoride, sodium iodide, cal cium bromide, calcium chloride, calcium ?uoride, calcium 

### iodide, aluminum bromide, aluminum chloride, aluminum ?uoride, aluminum iodide, transition metal halides with the proviso that the transitionmetal is not iron, or any mixture of
two or more thereof or mixtures of two or more thereof.



### 26. The method of claim 19, wherein the iron-bearing 

### compound is selected from iron (11) carbonate andthehalide 

### bearing compound is selected from calcium bromide.

27. The method of claim 19, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via addition to pulverized coal.

28. The method of claim 19, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via a dedicated supply line.

29. The method of claim 19, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 2.5:1 to about 10:1.

30. The method of claim 19, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 3.5:1 to about 8: 1.

31. The method of claim 19, wherein the at least one 

### halide-bearing compound is provided at su?icient amount to yieldahalide concentrationofbetweenabout 10ppmto about 200 ppm.



### 32. The method of claim 19, wherein the iron-bearing 

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

33. The method of claim 19, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 34. The method of claim 19, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.

35. The method of claim 19, wherein the at least one 

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

zone via addition to raw coal which is thereafter pulverized.



### 36. The method ofclaim 19, 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.

37.Amethod for simultaneously sequestering one ormore 

### gaseous phosphorus compounds, or gaseous phosphorus containing compounds, in the form ofone ormore less reac 

### tive iron-phosphorus-containing compounds, and oxidizing mercury, 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

## US 8,691,719 B2 23
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 ofthe 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; (E) providing at least one halide-bearing compound to a

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

### boiler, priorto entry ofthe ?ue gas into an SCR, withthe 

### proviso that halide-bearing compound is not an iron 

### halide; and (F)permitting the at least onehalide-bearing compoundto

react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or



### both, ofa catalytic activity and/or a catalytic lifespan of at least about 10percent at an operational time ofat least 

### about 4,000 hours. 38. The method of claim 37, wherein the iron-bearing compound is selected from metallic iron, one or more iron oxides, iron carbonate, or mixtures of two or more thereof.



### 39. The method of claim 37, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, iron (11) oxide, or mixtures oftwo or more thereof.



### 40. The method of claim 37, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, or a mixture thereof.

41. The method of claim 37, wherein the at least one 

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

42. The method of claim 37, wherein the at least one 

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



### 43. The method of claim 37, wherein the halide-bearing 

### compound is selected from potassium bromide, potassium 

### chloride, potassium ?uoride, potassium iodide, sodium bro mide, sodium chloride, sodium ?uoride, sodium iodide, cal cium bromide, calcium chloride, calcium ?uoride, calcium 

### iodide, aluminum bromide, aluminum chloride, aluminum ?uoride, aluminum iodide, transition metal halides with the proviso that the transitionmetal is not iron, or any mixture of
two or more thereof or mixtures of two or more thereof.



### 44. The method of claim 37, wherein the iron-bearing 

### compound is selected from iron (11) carbonate andthehalide 

### bearing compound is selected from calcium bromide.

45. The method of claim 37, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via addition to pulverized coal.

46. The method of claim 37, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via a dedicated supply line.

47. The method of claim 37, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 2.5:1 to about 10:1.

48. The method of claim 37, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 3.5:1 to about 8:1. 20

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## 24 49. The method of claim 37, wherein the at least one 

### halide-bearing compound is provided at su?icient amount to yieldahalide concentrationofbetweenabout 10ppmto about 200 ppm.

50. The method of claim 37, wherein the one ormore less 

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



### 51. The method of claim 37, wherein the iron-bearing 

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

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



### 53. The method of claim 37, wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.



### 54. The method ofclaim 37, 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.

55.Amethod for simultaneously sequestering one ormore 

### gaseous phosphorus compounds, or gaseous phosphorus containing compounds, in the form ofone ormore less reac 

### tive iron-phosphorus-containing compounds, and oxidizing mercury, the method comprising the steps of: (1) providing at least one coal-based fuel to a furnace, or



### boiler; (11) 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; (Ill) providing at least one iron-bearing compound to a

combustion zone ofthe 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 inthe combustion zoneor ?ue gas to form one or more less reactive iron-phosphorus 

## containing compounds; (V) providing at least one halide-bearing compound to a

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

### boiler, priorto entry ofthe ?ue gas into an SCR, withthe 

### proviso that halide-bearing compound is not an iron 

### halide; and (IV) (Vl) permitting the at least one halide-bearing com

pound to react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or



### both, ofa catalytic activity and/or a catalytic lifespan of at least about 15 percent at an operational time ofat least 

### about 3,000 hours. 56. The method of claim 55, wherein the iron-bearing compound is selected from metallic iron, one or more iron oxides, iron carbonate, or mixtures oftwo or more thereof.



### 57. The method of claim 55, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, iron (11) oxide, ormixtures oftwo or more thereof.



### 58. The method of claim 55, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, or a mixture thereof.

59. The method of claim 55, wherein the at least one 

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

## US 8,691,719 B2 25 60. The method of claim 55, wherein the at least one 

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

### 61. The method of claim 55, wherein the halide-bearing 

### compound is selected from potassium bromide, potassium 

### chloride, potassium ?uoride, potassium iodide, sodium bro mide, sodium chloride, sodium ?uoride, sodium iodide, cal cium bromide, calcium chloride, calcium ?uoride, calcium 

### iodide, aluminum bromide, aluminum chloride, aluminum ?uoride, aluminum iodide, transition metal halides with the proviso that the transitionmetal is not iron, or any mixture of
two or more thereof or mixtures of two or more thereof.



### 62. The method of claim 55, wherein the iron-bearing 

### compound is selected from iron (11) carbonate andthehalide 

### bearing compound is selected from calcium bromide. 63. The method of claim 55, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via addition to pulverized coal. 64. The method of claim 55, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via a dedicated supply line. 65. The method of claim 55, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 2.5:1 to about 10:1.

66. The method of claim 55, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 3.5:1 to about 8:1.

67. The method of claim 55, wherein the at least one 

### halide-bearing compound is provided at su?icient amount to yieldahalideconcentrationofbetweenabout 10ppmto about 200 ppm.

68. The method ofclaim 55, wherein the one ormore less 

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



### 69. The method of claim 55, wherein the iron-bearing 

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

70. The method of claim 55, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



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



### 72. The method of claim 55, 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.

73. 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 while concurrently sequestering mercury, the method comprising the steps of:

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, whereinthe 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 ofthe furnace, or boiler; and permitting the at least one iron-bearing compoundto react

with the at least one gaseous phosphorus compound and/or the at least one gaseous phosphorus-containing 20

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## 26 compoundpresent in the combustion zone or ?ue gas to form one ormore lessreactive iron-phosphorus-contain 

## ing compounds; providing at least one halide-bearing compound to a com

bustion zone or ?ue gas stream of a furnace, or boiler, prior to entry of the ?ue gas into an SCR, with the 

### proviso that halide-bearing compound is not an iron 

### halide; and permitting the at least one halide-bearing compound to

react with and/or oxidize any mercury present in the combustion zone or ?ue gas, wherein the method achieves an increase in either one, or



### both, ofa catalytic activity and/or a catalytic lifespan of at least about 15 percent at an operational time ofat least 

### about 4,000 hours. 74. The method of claim 73, wherein the iron-bearing compound is selected from metallic iron, one or more iron oxides, iron carbonate, or mixtures oftwo or more thereof.



### 75. The method of claim 73, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, iron (11) oxide, ormixtures oftwo or more thereof.



### 76. The method of claim 73, wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, or a mixture thereof.

77. The method of claim 73, wherein the at least one 

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

78. The method of claim 73, wherein the at least one 

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



### 79. The method of claim 73, wherein the halide-bearing 

### compound is selected from potassium bromide, potassium 

### chloride, potassium ?uoride, potassium iodide, sodium bro mide, sodium chloride, sodium ?uoride, sodium iodide, cal cium bromide, calcium chloride, calcium ?uoride, calcium 

### iodide, aluminum bromide, aluminum chloride, aluminum ?uoride, aluminum iodide, transition metal halides with the proviso that the transitionmetal is not iron, or any mixture of
two or more thereof or mixtures of two or more thereof.



### 80. The method of claim 73, wherein the iron-bearing 

### compound is selected from iron (11) carbonate andthehalide 

### bearing compound is selected from calcium bromide.

81. The method of claim 73, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via addition to pulverized coal.

82. The method of claim 73, wherein the at least one 

### halide-bearing compound isprovidedto the combustion zone via a dedicated supply line.

83. The method of claim 73, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 2.5:1 to about 10:1.

84. The method of claim 73, wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 3.5:1 to about 8: 1.

85. The method of claim 73, wherein the at least one 

### halide-bearing compound is provided at su?icient amount to yieldahalide concentrationofbetweenabout 10ppmto about 200 ppm.

86. The method of claim 73, wherein the one ormore less 

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



### 87. The method of claim 73, wherein the iron-bearing 

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

## US 8,691,719 B2 27 88. The method of claim 73, wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 89. The method of claim 73, Wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.



### 90. The method of claim 73, 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.

91. 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 furnace, or



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



### bustionprocess, Whereinthe 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 or ?ue gas stream of the fumace, or boiler, prior to entry of the ?ue gas into an SCR, Wherein the SCR is located upstream ofat least one air heater; and permitting the at least one iron-bearing compoundto 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 method achieves an increase in either one, or



### both, ofa catalytic activity and/or a catalytic lifespan of at least about 10percent at an operational time ofat least 

### about 2,000 hours. 92. The method of claim 91, Wherein the iron-bearing compound is selected from metallic iron, one or more iron oxides, iron carbonate, or mixtures of two or more thereof. 20

25

30

35 

## 28 93. The method of claim 91, Wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, iron (11) oxide, ormixtures oftwo or more thereof.



### 94. The method of claim 91, Wherein the iron-bearing 

### compound is selected from iron (Ill) oxide, iron (11) carbon ate, or a mixture thereof.

95. The method of claim 91, Wherein the at least one 

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

96. The method of claim 91, Wherein the at least one 

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

97. The method of claim 91, Wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 2.5:1 to about 10:1.

98. The method of claim 91, Wherein the at least one iron-bearing compound is provided at an excess stoichiomet ric ratio ofiron to phosphorus is in the range ofabout 3.5:1 to about 8: 1.



### 99. The method of claim 91, Wherein the iron-bearing 

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

100. The method of claim 91, Wherein the iron-bearing compound is a water soluble iron-bearing compound that is supplied in the form ofan aqueous solution.



### 101. The method of claim 91, Wherein the iron-bearing compound is awater insoluble iron-bearing compoundthat is supplied in the form ofan aqueous suspension or emulsion.

102. The method of claim 91, Wherein the at least one 

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



### 103. Themethod ofclaim 91, 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.

* * * * *

### USOO8691719B2



# (12) United States Patent (10) Patent N0.2 US 8,691,719 B2 Gadgil et a]. (45) Date ofPatent: *Apr. 8, 2014

(54) SYSTEMAND METHOD FOR INCREASING (52) US. Cl.
THE SERVICE LIFE AND/0R CATALYTIC USPC

............. 502/213; 110/345; 44/620; 502/224; ACTIVITY OF AN SCR CATALYSTAND 423/99 CONTROL OF MULTIPLE EMISSIONS


### (75) Inventors: Mandar R. Gadgil,Akron, OH (US); S. Behrooz Ghorishi, Uniontown, OH 

## (Us)
(73) Assignee: Babcock & Wilcox Power Generation 

### Group, Inc., Barberton, OH (US)
( * ) Notice: Subject to any disclaimer, the term ofthis patent is extended or adjusted under 35 

### U.S.C. 154(b) by 102 days.
This patent is subject to a terminal dis claimer. 

## (21) Appl.No.: 13/117,332
(22) Filed: May 27, 2011
(65) Prior Publication Data


### US 2011/0229388A1 Sep. 22, 2011

Related US. Application Data 

### (63) Continuation-in-part of application No. 12/691,527, ?led on Jan. 21, 2010. 

### (60) Provisional applicationNo. 61/171,619, ?led onApr. 22, 2009.
(51) Int. Cl. 

### B01J27/185 (2006.01) F23J11/00 (2006.01) F23J15/00 (2006.01) C10L 5/00 (2006.01) 

### BOIJ27/06 (2006.01) C01G 9/00 (2006.01) C01G 11/00 (2006.01) C01G 13/00 (2006.01) C223 17/00 (2006.01) C223 19/00 (2006.01) C223 43/00 (2006.01) (58) Field of Classi?cation Search None 

### See application ?le for complete searchhistory.

(56) References Cited

U.S. PATENT DOCUMENTS
4,061,716 A 12/1977 McGauley 4,572,085 A 2/1986 Hepworth 4,831,942 A * 5/1989 Morimoto et al.

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

## (Continued)

OTHER PUBLICATIONS

J.P. Chen et a1; Mechanism ofPoisoning oftheVZOS/TiOZ Catalyst for the Reduction ofNO byNH3; Journal ofCatalysis, vol. 125, pp. 411 to 420 (Oct. 1990). 

## (Continued)

Primary Examiner * Melvin C Mayes Assistant Examiner * Michael Forrest (74) Attorney, Agent, or Firm * Eric Marich


### (57) ABSTRACT
The present invention relates generally to the ?eld of emis 

### 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 toprotect the SCR catalyst. In still another embodiment, thepresent inventionrelates to a 

### method and apparatus for increasing the service life and/or 

### catalytic activity of an SCR catalyst While simultaneously controlling various emissions.

103 Claims, 2 Drawing Sheets