USOO8716169B2 

(12) United States Patent (10) Patent N0.: US 8,716,169 B2 

Gadgil et a]. (45) Date of Patent: May 6, 2014 

(54) SYSTEM AND METHOD FOR PROTECTION 4,572,085 A * 2/1986 Hepworth ................... .. 110/345 

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

4,843,980 A * 7/1989 Markham et al. ........... .. 110/342 MULTIPLE EMISSIONS 4,871,522 A 10/1989 Doyle 

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

Behrf’oz Ghonsm’ Unlomown’ OH 5,567,394 A * 10/1996 Chu 61 a1. .................... .. 422/177 

(Us), Donald P- T011“, Copley, OH (Us) 5,585,081 A 12/1996 Chu 61 a1. 

(73) Assignee: Babcock Grou Inc &Wilcox Barbenon Power OH Generation (Us) 7,741,239 5,899,679 A B2 * 6/2010 51999Euzen Hartensteln et et a1. .......... .. 502/25 

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

_ _ _ _ _ 2006/0245993 A1 11/2006 Magumbe 61 a1. 

( * ) Notice: SubJeCI to any disclaimer, the term of this 2007/0140940 A1 * 6/2007 Varma 6131. ............. .. 423/2155 

patent is extended or adjusted under 35 2007/0154374 A1 7/2007 Johnson et a1. 

U_s_c_ 15403) by 154 days_ 2007/0160517 A1 7/2007 Fan et a1. 

2008/0107579 A1 5/2008 Downs et al. 

(21) Appl' NO; 12/691527 2009/0065414 A1 3/2009 Nelson et al. 

_ OTHER PUBLICATIONS 

(22) F11ed: Jan. 21, 2010 

Vitali V. Lissianski et al.; Utilization of Iron Additives for Advanced 

(65) PFIOI‘ Pllblication Data Control of NOX Emissions from Stationary Combustion Sources; 

Us ' ’ 2001), 40, pp. 3287 Res. to3293. On the Internet On 

Related US. Application Data (Continued) 

(60) Provisional application No. 61/171,619, ?led on Apr. 

22, 2009. Primary Examiner * Melvin C Mayes 

Assistant Examiner * Michael Forrest 

(51) Int“ Cl“ (74) Attorney, Agent, or Firm 4 Eric Marich 

BOIJ27/185 (2006.01) 

F23J11/00 (2006.01) 

F23] 15/00 (2006.01) (57) ABSTRACT 

C10L 5/00 (200601) The present invention relates generally to the ?eld of emis 

(52) US Cl- sion control equipment for boilers, heaters, kilns, or other ?ue 

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

(58) Field of Classi?cation Search located at power plants, processing plants, etc.) and, in par 

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

See application ?le for complete search history. ing the poisoning and/or contamination of an SCR catalyst. In 

another embodiment, the method and apparatus of the present 

(56) References Cited invention is designed to protect an SCR catalyst, While simul 

U.S. PATENT DOCUMENTS 

4,061,716 A * 12/1977 McGauley ............. .. 423/244.06 

taneously providing emission control. 

57 Claims, 1 Drawing Sheet 

140 

18 it A 

COAL 

PULVv 110 

20 

100 [120 70 I 150 160 

\i I 0/ 

, u, 19 110 v? '- ------- 

130 -' 365 

135 ; 38 

110 $ M l 16 10071119115 y 

chL 12\ -N I BUNKER 

14 |-o-> 9‘: C-O-> 52—} 26 XL? ---- FEEDER B» 
US 8,716,169 B2 

Page 2 

(56) References Cited 

OTHER PUBLICATIONS 

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

lyst; Riley Power, Duke Energy, Cormetech, Inc. Paper #175, 2003. 

Virpi Kroger; Poisoning of Automotive Exhaust Gas Catalyst Com 

ponentsiThe Role of Phosphorus in the Poisoning Phenomena; 

Academic Dissertation, University of Oulu, Finlandi2007. 

Beck Jens et al.; The Behavior of Particle Bound Phosphorus During 

the Combustion of Phosphate Doped Coal; Fuel, 86, 2007 (available 

online Sep. 27, 2006), pp. 632 to 640. 

Elias Matinde et al.; Phosphorus Gasi?cation from Sewage Sludge 

During Carbothermic Reduction; ISIJ International, vol. 48 (2008), No. 7, pp. 912 to 917. 

Athen Tate et al.; Environmentally Sound Handling of Deactivated 

SCR Catalyst; Downloaded from the Internet on May 13, 2009 at 

http ://WWW. coalpowermag .com/environmenta l / l 36 .htrnl. 

J .P. Chen et al.; Mechanism of Poisoning of the V2OS/TiO2 Catalyst 

for the Reduction of NO By NH3; Journal of Catalysis, vol. 125, pp. 

411 to 420 (Oct. 1990). 

Xiaoyu Guo et al.; Effects of sulfate species on V2OS/TiO2 SCR 

Catalysts in Coal and Biomass-?red Systems; Applied Catalysis B: 

Environmental, vol. 92, pp. 30 to 40 (Oct. 2009). 

PCT International Search Report dated Aug. 17, 2012 in related PCT 

application No. PCT/US2012/039l75. 

* cited by examiner 

US 8,716,169 B2 

1 

SYSTEM AND METHOD FOR PROTECTION 

OF SCR CATALYST AND CONTROL OF 

MULTIPLE EMISSIONS 

RELATED APPLICATION DATA 

This patent application claims priority to US. Provisional 

Patent Application No. 61/171,619 ?led Apr. 22, 2009 and 

titled “System and Method for Protection of SCR Catalyst.” 

The complete text of this application is hereby incorporated 

by reference as though fully set forth herein in its entirety. 

FIELD AND BACKGROUND OF THE 

INVENTION 

1. Field of the Invention 

The present invention relates generally to the ?eld of emis 

sion control equipment for boilers, heaters, kilns, or other ?ue 

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

located at power plants, processing plants, etc.) and, in par 

ticular to a new and useful method and apparatus for reducing 

or preventing the poisoning and/ or contamination of an SCR 

catalyst. In another embodiment, the method and apparatus of 

the present invention is designed to protect the SCR catalyst. 

2. Description of the Related Art 

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 of any fossil fuel generates some level of NO,C due to 

high temperatures and the availability of oxygen and nitrogen 

from both the air and fuel. NO,C emissions may be controlled 

using low NO,C combustion technology and post-combustion 

techniques. One such post-combustion technique involves 

selective catalytic reduction (SCR) systems in which a cata 

lyst facilitates a chemical reaction between NO,C and a reagent 

(usually ammonia) to produce molecular nitrogen and water 

vapor. 

SCR technology is used worldwide to control NO,C emis 

sions from combustion sources. This technology has been 

used widely in Japan for NO,C control from utility boilers since 

the late 1970’s, in Germany since the late 1980’s, and in the 

US since the 1990’s. Industrial scale SCRs have been 

designed to operate principally in the temperature range of 

500° F. to 900° F., but most often in the range of 550° F. to 

750° F. SCRs are typically designed to meet a speci?ed NO 

reduction e?iciency at a maximum allowable ammonia slip. 

Ammonia slip is the concentration, expressed in parts per 

million by volume, of unreacted ammonia exiting the SCR. 

For additional details concerning NO removal technolo 

gies used in the industrial and power generation industries, 

the reader is referred to Steam/its generation and use, 41“ 

Edition, Kitto and StultZ, Eds., Copyright 2005, The Babcock 

& Wilcox Company, Barberton, Ohio, U.S.A., particularly 

Chapter 34iNitrogen Oxides Control, the text of which is 

hereby incorporated by reference as though fully set forth 

herein. 

Regulations issued by the EPA promise to increase the 

portion of utility boilers equipped with SCRs. SCRs are gen 

erally designed for a maximum e?iciency of about 90%. This 

limit is not set by any theoretical limits on the capability of 

SCRs to achieve higher levels of NO destruction. Rather, it is 

a practical limit set to prevent excessive levels of ammonia 

slip. This problem is explained as follows. 

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In an SCR, ammonia reacts with NO according to one or 

more of the following stoichiometric reactions (a) to (d): 

The above catalysis reactions occur using a suitable cata 

lyst. Suitable catalysts are discussed in, for example, US. Pat. 

Nos. 5,540,897; 5,567,394; and 5,585,081 to Chu et al., all of 

which are hereby incorporated by reference as though fully 

set forth herein. Catalyst formulations generally fall into one 

of three categories: base metal, zeolite and precious metal. 

Base metal catalysts use titanium oxide with small 

amounts of vanadium, 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 of the base metal catalyst is 

its potential to oxidize SO2 to S03; the degree of oxidation 

varies based 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 aluminosilicate materials which func 

tion similarly to base metal catalysts. One potential advantage 

of zeolite catalysts is their higher operating temperature of 

about 970° F. (521° C.). These catalysts can also oxidize SO2 

to S03 and must be carefully matched to the ?ue gas condi 

tions. 

Precious metal catalysts are generally manufactured from 

platinum and rhodium. Precious metal catalysts also require 

careful consideration of ?ue gas constituents and operating 

temperatures. While effective in reducing NOX, these cata 

lysts can also act as oxidiZing catalysts, converting CO to CO2 

under proper temperature conditions. However, SO2 oxida 

tion to S03 and high material costs often make precious metal 

catalysts less attractive. 

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

lysts undergo poisoning when they become contaminated by 

various compounds including, but not limited to, certain 

phosphorus compounds such as phosphorous oxide (P0) or 

phosphorous pentoxide (P205). 

More particularly, as the SCR catalysts are exposed to the 

dust laden ?ue gas there are numerous mechanisms including 

blinding, masking and poisoning that deactivates the catalyst 

and causes a decrease in the catalyst’s performance over time. 

The mo st common catalyst poison encountered when burning 

eastern domestic coal (i.e., coal mined in the eastern United 

States) is arsenic. The most common catalyst poison encoun 

tered when burning western domestic coal (i.e., coal mined in 

the western United States) is phosphorus and calcium sulfate 

is the most common masking mechanism. One method of 

recycling the used catalyst is the process called regeneration 

washing or rejuvenation. The initial steps of the regeneration 

process involve the removal of these toxic chemicals by pro 

cessing the catalysts through various chemical baths in which 

the poisons are soluble. While this treatment process does an 

excellent job of removing the desired poisons it produces 

wastewater with very high arsenic concentrations. 

In another situation, Powder River Basin/Lignite coal 

plants, any coal/biomass co-combustion, or any coal/bone 

meal co-combustion or even pure biomass combustion power 

plants will suffer from phosphorus contamination of their 

SCR catalysts. 
US 8,716,169 B2 

3 

Additionally, beyond controlling NO,C emissions, other 

emission controls must be considered and/ or met in order to 

comply with various state, EPA and/or Clean Air Act regula 

tions. Some other emission controls which need to be consid 

ered for boilers, heaters, kilns, or other ?ue gas-, or combus 

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

plants, processing plants, etc.) include, but are not limited to, 

mercury, SOX, and certain particulates. 

Given the above, a need exists for a method that provides 

for any economical and environmentally suitable method 

and/ or system to remove the gaseous phosphorus from a 

combustion process prior to any phosphorus compounds poi 

soning a catalyst in an SCR. 

SUMMARY OF THE INVENTION 

The present invention relates generally to the ?eld of emis 

sion control equipment for boilers, heaters, kilns, or other ?ue 

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

located at power plants, processing plants, etc.) and, in par 

ticular to a new and useful method and apparatus for reducing 

or preventing the poisoning and/ or contamination of an SCR 

catalyst. In another embodiment, the method and apparatus of 

the present invention is designed to protect an SCR catalyst. 

Accordingly, one aspect of the present invention is drawn 

to a method for increasing the active life of an SCR catalyst, 

the method comprising the steps of: (a) providing at least one 

iron-bearing compound to a combustion zone or ?ue gas 

stream of a fumace, or boiler, prior to entry of the ?ue gas into 

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

compound to react with any gaseous phosphorus compounds, 

or phosphorus-containing compounds, present in the com 

bustion zone or ?ue gas prior to the entry of the ?ue gas into 

the SCR. 

In yet another aspect of the present invention, there is 

provided a method for increasing the active life of an SCR 

catalyst, the method comprising the steps of: (i) providing at 

least one iron-bearing compound to a combustion zone of a 

furnace or boiler; and (ii) permitting the at least one iron 

bearing compound to react with any gaseous phosphorus 

compounds, or phosphorus-containing compounds, present 

in the combustion zone prior to the entry of the ?ue gas into an 

SCR, wherein the iron-bearing compound is selected from 

one or more iron (II) halides, iron (III) halides, iron (III) 

iodate, iron (III) oxide, iron (II) carbonate, or mixtures of two or more thereof. 

In yet another aspect of the present invention, there is 

provided a method for sequestering one or more phosphorus 

compounds, or phosphorus-containing compounds, in the 

form of one or more less reactive iron-pho sphorus -containing 

compounds, the method comprising the steps of: (A) provid 

ing at least one iron-bearing compound to a combustion zone 

or ?ue gas stream of a furnace, or boiler; and (B) permitting 

the at least one iron-bearing compound to react with any 

gaseous phosphorus compounds, or phosphorus-containing 

compounds, present in the combustion zone or ?ue gas to 

form one or more less reactive iron-phosphorus-containing 

compounds. 

In yet another aspect of the present invention, there is 

provided a method for increasing the active life of an SCR 

catalyst while concurrently controlling mercury in a gas, the 

method comprising the steps of: providing at least one iron 

bearing halide compound to a combustion zone or ?ue gas 

stream of a fumace, or boiler, prior to entry of the ?ue gas into 

an SCR; permitting the iron portion of the at least one iron 

bearing halide compound to react with any gaseous phospho 

rus compounds, or phosphorus-containing compounds, 

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4 

present in the combustion zone or ?ue gas prior to the entry of 

the ?ue gas into the SCR; and permitting the halide portion of 

the at least one iron-bearing halide compound to react with 

any gaseous mercury compounds, or mercury-containing 

compounds, present in the combustion zone or ?ue gas. 

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 of one or more less reactive iron-phosphorus -containing 

compounds while concurrently sequestering mercury, the 

method comprising the steps of: providing at least one iron 

bearing halide compound to a combustion zone or ?ue gas 

stream of a furnace, or boiler; permitting the iron portion of 

the at least one iron-bearing halide compound to react with 

any gaseous phosphorus compounds, or phosphorus-contain 

ing compounds, present in the combustion zone or ?ue gas to 

form one or more less reactive iron-phosphorus-containing 

compounds; and permitting the halide portion of the at least 

one iron-bearing halide compound to react with any gaseous 

mercury compounds, or mercury-containing compounds, 

present in the combustion zone or ?ue gas. 

The various features of novelty which characterize the 

invention are pointed out with particularity in the claims 

annexed to and forming a part of this disclosure. For a better 

understanding of the invention, its operating advantages and 

speci?c bene?ts attained by its uses, reference is made to the 

accompanying drawings and descriptive matter in which 

exemplary embodiments of the invention are illustrated. 

BRIEF DESCRIPTION OF THE DRAWINGS 

The sole FIGURE is a schematic representation of a typical 

fossil fuel burning facility with an SCR system, and which 

includes a system for practicing the methods of the present 

invention. 

DESCRIPTION OF THE INVENTION 

While the present invention will be described in terms of 

SCR systems which use ammonia as the NO,C reducing agent, 

since ammonia is frequently preferred for economic reasons, 

the present invention is not limited to ammonia based sys 

tems. The concepts of the present invention canbe used in any 

system which uses an ammoniacal compound. As used in the 

present disclosure, an ammoniacal compound is a term meant 

to include compounds such as urea, ammonium sulfate, cya 

nuric acid, and organic amines as well as ammonia (NH3). 

These compounds could be used as reducing agents in addi 

tion to ammonia, but as mentioned above, ammonia is fre 

quently preferred for economic reasons. Some non-ammo 

niacal compounds such as carbon monoxide or methane can 

be used as well, but with loss in effectiveness. 

Although the present invention is described in relation to a 

boiler, or a fossil fuel boiler, it is not limited solely thereto. 

Instead, the present invention can be applied to any combus 

tion source that generates NO regardless of whether such a 

combustion source is utilized in conjunction with a boiler, or 

a steam generator. For example, the present invention could 

be used in combination with a kiln, a heater, or any other type 

of combustion process that generates, in whole or in part, a 

?ue gas or combustion gas containing NOX. Accordingly, the 

description below is to be construed as merely exemplary. 

As illustrated in the FIGURE, 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 of the FIGURE. In this con?guration, the wet 
5 

scrubber is typically preceded (with respect to a direction of 

?ue gas ?ow through the system) by a particulate collection 

device (PCD), advantageously a fabric ?lter (FF) bag house, or an electrostatic precipitator (ESP). If desired, there may 

also be provided a wet electrostatic precipitator (wet ESP or 

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

for ?ne particulate or S03. Alternatively, the present inven 

tion may be applied to a system which employs a spray dryer 

apparatus (SDA) or dry scrubber for removal of sulfur oxides 

from the ?ue gases, as shown in the lower right-hand side of 

the FIGURE. In this con?guration, the SDA or dry scrubber is 

typically followed (with respect to a direction of ?ue gas ?ow 

through the system) by a particulate collection device (PCD), 

advantageously a fabric ?lter (FF) or baghouse, an electro 

static precipitator (ESP) or even a wet electrostatic precipita 

tor (wet ESP). 

Additionally, the present invention can be applied to any 

SCR catalyst that is adversely affected by poisoning with a 

phosphorus-based compound such as, but not limited to, 

H3PO4, P0 or PZOS. As such, the present invention is not 

limited to any one type of SCR catalyst, but rather is broadly 

applicable to a wide range of SCR catalyst systems. Suitable 

catalyst systems for which the present 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 combustion units. It should be noted 

that although the present invention is described in relation to 

PRB coal, the present invention is not limited thereto. Rather, 

the present invention is broadly applicable to any situation 

where an SCR catalyst is poisoned by one or more gaseous 

phosphorus compounds. 

In one embodiment, phosphorous in PRB coal is suspected 

to cause rapid deactivation in staged combustion and other 

units. This deactivation is suspected to be caused by the gas 

phase phosphorus released via carbothermic reduction reac 

tion. In this reaction under oxygen de?cient conditions, phos 

phorus bearing compounds release gas phase phosphorus by 

the following reaction: 

P205(solid phase compounds)+3C(s)—>2PO(g)+ 

3CO(g). 

This gas phase phosphorous attaches to the active sites 

within the catalyst causing the deactivation of the sites for 

NO,C reduction. As a result of this 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 and method to prevent formation of gas phase phospho 

rus species in the combustion environment thus reducing, 

mitigating and/ or eliminating the rate of SCR deactivation. In 

one embodiment, the present invention accomplishes the 

aforementioned goal by the addition of at least one iron 

bearing compound to the PRB coal prior to combustion. 

In one embodiment, the iron-bearing compounds of the 

present invention is any iron compound (e.g., an iron oxide 

compound) that is able to undergo reduction in the combus 

tion environments common to boilers, fumaces, power 

plants, etc. In one particular embodiment, the iron-bearing 

compound is iron (III) oxide (Fe203), also known as red iron 

oxide or hematite. In the embodiment where iron (III) oxide is 

utilized the reactions of interest that occur in the combustion 

portion of a boiler or furnace are as shown below: 

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It should be 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 generated due to 

the reduction of FeZO3 is then available to tie-up, bind and/or 

sequester any PO gas present in the combustion zone, or the 

?ue gas, of a boiler, or fumace, prior to arrival at the SCR. 

This PO gas will then form FeiP compounds in particulate 

phase prior to arrival at the SCR. The particulate will pass 

through the catalyst and avoid the catalyst deterioration. 

In another embodiment, the present invention can utilize 

iron (II) carbonate which is converted to the desired iron (II) 

oxide in the combustion zone via the reaction shown below: 

In still another embodiment, the present invention can uti 

lize one or more iron halides. Suitable iron halides include, 

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

iron (II) chloride, iron (III) chloride, iron (II) iodide, iron (III) 

iodate (Fe(IO3)3), or any mixture of two or more thereof. In 

still another embodiment, any one or more iron halides can be 

used in combination with another non-halide containing iron 

compound (e.g., iron (II) carbonate). In still another embodi 

ment, the present invention utilizes a combination of iron (II) 

bromide and/or iron (III) bromide with iron (II) carbonate to 

control the amount of phosphorous in a ?ue gas, or combus 

tion gas while concurrently permitting the control of mercury 

compounds, or mercury-containing compounds, in a ?ue gas, 

or combustion gas. As used herein, mercury compounds, or 

mercury-containing compounds, include, but are not limited 

to, any compound that contains either oxidized mercury, or 

bound elemental mercury. In still another embodiment, the 

present invention is directed to concurrently permitting the 

control of mercury compounds, or mercury-containing com 

pounds, that contain primarily, or only, oxidized mercury. As 

used herein any iron compound, halide or otherwise, can be 

utilized in a hydrated or non hydrated form. As such, refer 

ence to any iron compound herein by de?nition includes any 

hydrated forms that exist whether or not speci?cally men 

tioned by chemical formula. 

As is known in the art, (see, e. g., United States Patent 

Application Publication No. 2008/0107579 the text of which 

is hereby incorporated by reference as though fully set forth 

herein) halide-containing compounds are utilized to oxidize 

elemental mercury present 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 or more suitable environmental 

control technologies (e.g., a wet scrubber or spray dry 

absorber (SDA), a ?ue gas desulfurization system (FGD), a 

powdered activated carbon system (PAC), or a particulate 

collecting system such as a fabric ?lter (FF) or a electrostatic 

precipitator (ESP)). In one instance, as is known in the art, the 

addition of one or more suitable halide-containing com 

pounds also increases the amount of mercury that is particu 

late-bound. Given that numerous patents and published appli 

cations detail the manner by which suitable halide-containing 

compounds permit the increased recovery of mercury from a 

?ue, or combustion, gas, a detailed discussion hereof is omit 

ted for the sake of brevity. 

In any of the above embodiments, the suitable iron-bearing 

compound can be added to the coal in the pulverizer. In still 

another embodiment, the iron-bearing compound of the 

present invention can be added to the combustion zone of a 

boiler and/or furnace via a suitable supply line designed to 

deliver a powderized iron-bearing compound to the combus 
US 8,716,169 B2 

7 

tion zone of a furnace and/or boiler. To this end, the FIGURE 

illustrates several embodiments of suitable design schemes 

for accomplishing this result. 

Referring to the FIGURE, there is illustrated a schematic 

representation of a typical fossil fuel burning facility, gener 

ally designated 10, with an SCR system, and which includes 

a system for practicing the methods of the present invention. 

As shown, boiler 12 is provided for extracting the heat from 

the combustion of a fossil fuel, such as coal, through com 

bustion with an oxidant, typically air. The heat is transferred 

to a working ?uid, such as water, to generate steam used to 

either generate power via expansion through a turbine gen 

erator apparatus (not shown) or for industrial processes and/ 

or heating. 

The raw coal 14 must be crushed to a desired ?neness and 

dried to facilitate combustion. Raw coal 14 is temporarily 

stored in a coal bunker 16 and then transferred by means of a 

gravimetric or volumetric feeder 18 to one or more coal 

pulverizers 20. In the embodiment shown in the FIGURE, 

there are six (6) coal pulverizers, identi?ed as coal pulverizers 

A-F. As is known to those skilled in the art, each coal pulver 

izer 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 and remove moisture from the coal to desired levels as 

it is ground. The primary air is also used to convey the pul 

verized coal (PC) out of each coal pulverizer 20 and delivers 

it along a plurality of pulverized coal supply lines (one such 

burner line is identi?ed at A in the FIGURE; a single coal 

pulverizer 20 may supply coal through 4-8 pulverized coal 

supply lines) to the burners 22 on the front and rear walls of 

the boiler 12. Typically, the burners 22 are located in spaced 

elevations on one or both of the opposed front and rear walls 

of the boiler 12, or at the corners of the boiler in installations 

known as comer-?red or tangentially-?red units (not shown). 

The present invention can be utilized in conjunction with, but 

is not limited solely to, single-wall ?red, opposed-wall ?red 

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

pulverizer 20 only provides coal to a single elevation of 

bumers 22 on a wall. Thus, in the embodiment shown in the 

FIGURE, the six coal 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 burners on multiple 

walls and/ or elevations or multiple pulverizers supplying 

bumers on a single elevation) and the present invention 

applies to any such con?gurations. 

The combustion process begins in the burner zone 24 of the 

boiler 12’s furnace 26, releasing heat and creating hot ?ue gas 

28 which is conveyed upwardly to the upper portion 30 of the 

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 of the ?ue gas, and preheat the incoming air used 

for combustion. 

As illustrated in the FIGURE, and downstream of the air 

heaters 42, the ?ue gas 28 undergoes further treatment for the 

removal of particulates and sulfur oxides. Two typical con 

?gurations of the downstream equipment employed to 

accomplish these tasks are shown on the right-hand side of the 

FIGURE. The upper equipment con?guration in the FIGURE 

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8 

comprises a particulate collection device (PCD) schemati 

cally indicated at 44, for removal of particulates from the ?ue 

gas 28, and which may comprise in practice a fabric ?lter or 

an electrostatic precipitator. Downstream of the PCD 44 there 

is provided a wet ?ue gas desulfurization (WFGD) device, 

also known as a wet scrubber, for removal of sulfur oxides 

from the ?ue gas 28. The cleaned, scrubbed ?ue gas may 

(optionally) be conveyed through a wet ESP 47 for removal of 

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

discharge to the atmosphere. 

The lower equipment con?guration in the FIGURE com 

prises a 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, for removal of particulates from the ?ue gas 

28. The cleaned, scrubbed ?ue gas is then conveyed to stack 

48 for discharge to the atmosphere. 

In order to further reduce NO emissions, some boilers 12 

employ staged combustion wherein only part of the stoichio 

metric amount of air is provided in the main burner zone 24, 

with the balance of the air for combustion, together with any 

excess air required due to the fact that no combustion process 

is 100% ef?cient, is provided above the burner zone 24 via 

over ?re air (OFA) ports 52. If staged combustion is employed 

in a boiler 12, due to the reduced air supplied to the burner 

zone 24, a reducing atmosphere is created in the lowerportion 

of the fumace 26, including the hopper region 54. 

In accordance with a ?rst embodiment of the present inven 

tion, a suitable iron-bearing compound is added to the one or 

more coal pulverizers 20 prior to supplying the pulverized 

coal to the one or more burners 22. The system and apparatus 

for accomplishing this desired result is also shown in the 

FIGURE, generally designated 100. The system 100 com 

prises a storage means 120 for temporarily storing the phos 

phorous reduction compound, generally designated 110; 

delivery means 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. In 

the FIGURE, the raw coal 14 to which the phosphorous 

reducing compound 110 has been added is referred to as 140. 

Advantageously, the phosphorous reducing compound 110 

may be provided along with the raw coal 14 via the feeder 18, 

which permits close control and measurement of the delivery 

of both raw coal 14 and phosphorous reducing compound 110 

into the coal pulverizer 20. Alternatively, the phosphorous 

reducing compound 110 may be provided directly into the 

coal pulverizer 20 and/or directly into one or more individual 

burner lines A-F providing the pulverized coal to individual 

bumers 22, with suitable sealing devices against the positive 

pressure within the coal pulverizer 20 or burner lines A-F. The 

delivery means may be slurry-based or pneumatic as required 

by the particulars of the phosphorous reducing compound 

110 and the amount and location of introduction into the ?ue 

gas 28. An interconnected arrangement of control or signal 

lines 170, 180, 190 and 195 interconnect these various 

devices to provide control signals, phosphorous reducing 

compound 110 level signals, and phosphorous level signals in 

the ?ue gas 28 (from a sensor 200) to permit the introduction 

of the phosphorous reducing compound 110 into the ?ue gas 

28 to be controlled by a human operator, or automatically 

controlled. However, if a suitable, real-time sensor 200 for 

measuring levels of gaseous phosphorous in the ?ue gas 28 is 

not available, ?ue gas samples may instead be taken at the 
US 8,716,169 B2 

location 200 for later laboratory analysis via suitable test 

methods, which may be inductively coupled plasma-mass 

spectrometry (ICP-MS). 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 phosphorus reducing compound 110 intro 

duced into the ?ue gas 28. Provided that subsequent labora 

tory analyses do not indicate any signi?cant variation in gas 

eous phosphorus levels in the ?ue gas 28, there may be no 

need for real-time, close control of the introduction of phos 

phorus reducing compound 110. Instead, the amount of phos 

phorus 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, the present invention uti 

lizes iron (II) oxide. In this embodiment, the need for a reduc 

tion reaction to occur is eliminated and the addition points for 

the iron (II) oxide of this 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 of a boiler, or fumace, prior to arrival at 

the SCR. In particular, the phosphorous reduction compound 

can be supplied at one or more of the locations G through Q 

shown in the FIGURE. More particularly, the phosphorous 

reduction compound can also be provided into the ?ue gas 28 

at one or more of the following locations: 

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

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

burners 22; 

H: into the furnace 26 at a location above the burner zone 

24, in one 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 the boiler 12 in the upper portion 36 of the horizon 

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, the reduced iron, or iron (II) oxide, of the 

present invention is able to remove the gas phase phosphorus 

in the form of iron-phosphorus alloys which upon coming in 

contact with the over ?re air from iron-phosphorus oxide 

compounds. 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 compounds 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 embodiment, directed to 

the situation where a majority of the phosphorus present in the 

combustion and/or ?ue stream is sequestered in a suitable 

iron-phosphorus-oxygen-containing compound thereby sub 

stantially reducing the amount of calcium/phosphorus/oxy 

gen-containing compounds that are able to react with SOX. 

This in turn substantially reduces the amount of gaseous 

phosphorus that is produced in the combustion and/or ?ue gas 

stream by restricting the amount of calcium/phosphorus/ oxy 

gen-containing compounds that are present in the combustion 

and/ or ?ue gas stream to react with various SO,C compounds 

resulting in the unwanted production of gaseous phosphorus 

20 

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45 

50 

55 

60 

65 

10 

compounds, or phosphorus/oxygen compounds, that can lead 

to the undesired poisoning of an SCR catalyst. 

In still another embodiment, the iron-bearing compounds 

of the present invention can be added in any suitable manner, 

including the manner detailed in the FIGURE. Suitable iron 

bearing compounds include, but are not limited to, aqueous 

and soluble forms of iron-bearing compounds such as iron 

halides (e.g., iron chlorides, iron bromides, iron iodide, or 

iron iodate), metallic iron, one or more iron oxides, iron 

carbonate, or mixtures of two or more thereof. If an existing 

skid is used then an aqueous reagent can be pumped via 

positive displacement pumps from a storage tank to the one or 

more coal feeders where the reagent is sprayed on the coal as 

the coal passes on a feeder belt upstream of the pulverizers. 

In one embodiment, the present invention is advantageous 

in that it is applicable to both existing SCRs (retro?ts) and 

new SCRs. Additionally, the present invention can be applied 

to plants that utilize biomass as a fuel source. In one embodi 

ment, implementation of the present invention can be accom 

plished in a cost-effective manner utilizing low co st hardware 

designed to supply the necessary iron compound to a com 

bustion process. The present invention also does not affect the 

current design of boilers and SCRs. 

In one embodiment, the amount of iron compound, or 

compounds, utilized in conjunction with the present inven 

tion varies depending upon the phosphorus content in the coal 

to be burned. As is known to those of skill in the art, the 

phosphorus content of coal can be determined by various 

known methods. Thus, in this instance, the present invention 

is not limited to any one range of iron compounds that are 

utilized. Instead, a stoichiometric ratio is utilized. In one 

embodiment, the stoichiometric ratio of iron to phosphorus is 

in the range of about 1:3 to about 3:1, or from about 1:2 to 

about 2:1, or from about 1:1.5 to about 1.5:1, or from about 

1:1.25 to about 1.25:1, or even about 1:1. Here, as well as 

elsewhere in the speci?cation and claims, individual range 

values can be combined to form additional and/or non-dis 

closed ranges. 

In another embodiment, the amount of iron 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 of iron compound, or 

compounds, (hereinafter referred to as just “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 of about 0.7 pounds of “iron” per 1,000 

pounds of coal to about 6 pounds of “iron” per 1,000 pounds 

of coal. In another embodiment, the amount of iron com 

pound, or compounds, utilized is in the range of about 1 

pound of “iron” per 1,000 pounds of coal to about 5.5 pounds 

of “iron” per 1,000 pounds of coal, or from about 1.5 pounds 

of “iron” per 1,000 pounds of coal to about 5 pounds of “iron” 

per 1,000 pounds of coal, or from about 2 pounds of “iron” per 

1,000 pounds of coal to about 4.5 pounds of “iron” per 1,000 

pounds of coal, or from about 2.5 pounds of “iron” per 1,000 

pounds of coal to about 4 pounds of “iron” per 1,000 pounds 

of coal, or from about 3 pounds of “iron” per 1,000 pounds of 

coal to about 3.5 pounds of “iron” per 1,000 pounds of coal. 

Here, as well as elsewhere in the speci?cation and claims, 

individual range values can be combined to form additional 

and/or non-disclosed ranges. 

In another embodiment, where both iron (II) bromide and 

iron (II) carbonate is to be utilized for controlling various 

compounds in a ?ue gas, or combustion gas, of a 100 MWe 

coal power plant the injection rate for the iron (II) carbonate 
US 8,716,169 B2 

11 

is as discussed above while the iron (II) bromide is supplied as 

a solution and at an amount in the range of about 0.25 gallons 

per hour to about 10 gallons per hour, or from about 0.5 

gallons per hour to about 5 gallons per hour, or even from 

about 1 gallon per hour to about 4 gallons per hour. In another 

embodiment, where just an iron halide is utilized (e.g., iron 

(II) bromide and/or iron (III) bromide) the amount of iron 

halide supplied to the ?ue gas, or combustion gas, is suf?cient 

to yield a concentration of bromide 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 in place on 

the device generating the ?ue gas, or combustion gas, it may 

be desirable to use a lower bromide concentration in order to 

prevent any type of detrimental effects to such downstream 

emissions technology. In one embodiment of such an instance 

the concentration of bromide is between about 10 ppm to 

about 125 ppm, or from about 25 ppm to about 100 ppm, or 

from about 50 ppm to about 75 ppm. Here, as well as else 

where 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 of the above, one of skill in the art would recognize 

that the amount of iron compounds necessary to supply the 

desired amount of iron and halogen to a ?ue gas, or combus 

tion gas, in accordance with the process of the present inven 

tion will vary depending upon the size of the device generat 

ing 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 of iron (II) bromide 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 per hour to about 5 gallons per hour, 

or even from 1 gallon per hour to about 4 gallons per hour. 

Here, as well as elsewhere in the speci?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 of bromide and/or iron. As would be 

apparent to one of skill in the art, other additional factors can 

impact the amount of iron-bearing compounds supplied in 

connection with the various embodiments of the present 

invention. Such additional factors include, but are not limited 

to, the amount and/or type of phosphorus present in the coal, 

or other combustible fuel; the size and/ or output of the boiler, 

heater, kiln, or other ?ue gas-, or combustion gas-, generating 

device; and the desired stoichiometric ratio to be achieved; 

the type and/ or manner of combustion, the type and/or 

arrangement of any applicable equipment or structure. 

In another embodiment, the one or more iron compounds 

utilized in conjunction with the present invention can be of 

any particle size and/or particle geometry. Suitable particle 

geometries include, but are not limited to, spherical, platelet 

like, irregular, elliptical, oblong, or a combination of two or 

more different particle geometries. In one embodiment, the 

one or more iron compounds of the present invention, if water 

soluble, can be supplied in solution form. In such an instance, 

a solution concentration of at least about 15 weight percent of 

the one or more water soluble iron compounds is utilized. In 

another embodiment, a solution concentration of at least 

about 20 weight percent, at least about 25 weight percent, at 

least about 30 weight percent, at least about 35 weight per 

cent, at least about 40 weight percent, at least about 45 weight 

percent, or even at least about 50 weight percent of more of 

the one or more water soluble iron compounds is utilized is 

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45 

50 

55 

60 

65 

12 

utilized in conjunction with the present invention. Here, as 

well as elsewhere in the speci?cation and claims, individual 

range values can be combined to form additional and/ or non 

disclosed ranges. As would be appreciated by those of skill in 

the art, the solution concentration of any one or more water 

soluble iron compounds should not, in one embodiment, 

exceed the solubility amount for the one or more iron com 

pounds. In still another embodiment, the one or more iron com 

pounds of the present invention can be supplied in a powdered 

form, a solution form, an aqueous suspension form, or a 

combination thereof. In the case of an aqueous suspension, 

the one or more iron compounds utilized in conjunction with 

the present invention should have a suitable particle size. 

Additionally, even absent the desire to place the one or more 

iron compounds of the present invention into an aqueous 

solution, the one or more iron compounds should have a 

suitable particle size that facilitates a higher degree of reac 

tivity when 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 

compounds where at least about 95% of the particles have a 

particle size of less than about 400 um (microns), where at 

least about 95% of the particles have a particle size of less 

than about 350 um (microns), where at least about 95% of the 

particles have a particle size of less than about 300 um (mi 

crons), where at least about 95% of the particles have a 

particle size of less than about 250 um (microns), where at 

least about 95% of the particles have a particle size of less 

than about 200 um (microns), or even where at least about 

95% ofthe particles have a particle size ofless than about 175 

um (microns). Here, as well as elsewhere in the speci?cation 

and claims, individual range values can be combined to form 

additional and/or non-disclosed ranges. 

Although not limited hereto, a suitable iron compound for 

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

carbonate available from Prince Agri Products (a subsidiary 

of Phibro Animal Health Corporation located in Ridge?eld 

Park, N.J.). This iron (II) carbonate is a powdered compound 

where at least about 95% of its particles are less than 200 um 

(microns) in size. Additionally, the concentration of iron (II) 

carbonate in this product is about 80% by weight with sub 

stantially all of the remaining 20 weight percent being non 

reactive in light of the use here. 

In the instance where an aqueous suspension is utilized in 

conjunction with the present invention, such an aqueous sus 

pension can further comprise a suitable amount of one or 

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

agents. Suitable anti-settling, suspension, thickening or 

emulsi?cation agents include, but are not limited to, sodium 

polyacrylates, carbomers, acrylates, inorganic thickening 

agents. Other suitable anti-settling, suspension, thickening or 

emulsi?cation agents are known to those of skill in the art and 

as such a discussion herein is omitted for the sake of brevity. 

In another embodiment, a suitable suspension or emulsi?ca 

tion can be achieved via agitation and does not necessarily 

require the use of one or more anti-settling, suspension, thick 

ening or emulsi?cation agents. In another embodiment, a 

combination of one or more anti-settling, suspension, thick 

ening or emulsi?cation agents can be utilized in combination 

with agitation. 

In still another embodiment, the one or more iron com 

pounds of the present invention should have a purity of at least 

about 50 weight percent, at least about 55 weight percent, at 

least about 60 weight percent, at least about 65 weight per 

cent, at least about 70 weight percent, at least about 75 weight 

percent, at least about 80 weight percent, at least about 85 
US 8,716,169 B2 

13 

weight percent, at least about 90 weight percent, at least about 

95 weight percent, or even at least about 99 weight percent or 

higher. Here, as well as elsewhere in the speci?cation and 

claims, individual range values can be combined to form 

additional and/ or non-disclosed ranges. 

As for the portion of the one or more iron compounds that 

is not “an iron compoun ,” such impurities should be non 

reactive in the environments present in conjunction with the 

present invention. Alternatively, if reactive, such impurities 

should eitherbe easily captured, removed and/or sequestered, or should not add signi?cantly to any further contamination of 

any catalyst downstream. In still another embodiment, the 

amount of phosphorus-containing compound impurities in 

any of the one or more iron compounds that are utilized in 

conjunction with the present invention should be less than 

about 5 weight percent, less than about 2.5 weight percent, 

less than about 1 weight percent, less than about 0.5 weight 

percent, less than about 0.25 weight percent, less than about 

0.1 weight percent, or even less than about 0.01 weight per 

cent. Here, as well as elsewhere in the speci?cation and 

claims, individual range values can be combined to form 

additional and/or non-disclosed ranges. In still yet another 

embodiment, the amount of phosphorus-containing com 

pound impurities in any of the one or more iron compounds 

that are utilized in conjunction with the present invention 

should be zero. That is, in this embodiment the one or more 

iron compounds that are utilized in conjunction with the 

present invention should be free from any phosphorus-con 

taining compounds. 

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

believed that the present invention exploits various preferen 

tial reactions between phosphorous compounds, or phospho 

rus-containing compounds, to sequester various phosphorous 

compounds, or phosphorus-containing compounds that are 

detrimental to an increased active, or service, life of an SCR 

catalyst. Thus, the reactions discussed herein are to be con 

strued as non-limiting in that other additional reactions may 

be occurring in the combustion and/ or ?ue gas stream. 

While speci?c embodiments of the present invention have 

been shown and described in detail to illustrate the applica 

tion and principles of the invention, it will be understood that 

it is not intended that the present invention be limited thereto 

and that the invention may be embodied otherwise without 

departing from such principles. In some embodiments of the 

invention, certain features of the invention may sometimes be 

used to advantage without a corresponding use of the other 

features. Accordingly, all such changes and embodiments 

properly fall within the scope of the following claims. 

What is claimed is: 

1. A method for increasing the active life of an SCR cata 

lyst, the method comprising the steps of: 

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

boiler; 

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

combustion process, wherein the staged combustion 

process produces at least one gaseous phosphorus com 

pound and/or at least one gaseous phosphorus-contain 

ing compound; 

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

bustion zone of a furnace, or boiler, prior to entry of the 

?ue gas into an SCR, wherein the SCR is located 

upstream of at least one air heater; and 

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

react with the at least one gaseous phosphorus com 

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

taining compound present in the combustion zone or ?ue 

20 

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45 

50 

55 

60 

65 

14 

gas prior to the entry of the ?ue gas into the SCR to form 

an iron phosphorus-containing compound. 

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

pound is selected from one or more iron halides, metallic iron, 

one or more iron oxides, 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 (III) oxide, iron (II) carbonate, 

iron (II) oxide, or mixtures of two or more thereof. 

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

pound is selected from iron (III) oxide, iron (II) carbonate, or 

a mixture thereof. 

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

bearing compound is provided to the combustion zone via 

addition to pulverized coal. 

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

bearing compound is provided to the combustion zone via a 

dedicated supply line. 

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

pound is a water soluble iron-bearing compound. 

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

pound is a water soluble iron-bearing compound that is sup 

plied in the form of an aqueous solution. 

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

pound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

10. The method of claim 1, wherein the staged combustion 

process utilizes over ?re air and the staged combustion pro 

cess results in an increased amount of the at least one gaseous 

phosphorus compound and/or the at least one gaseous phos 

phorus-containing compound and results in the deactivation 

of the SCR catalyst. 

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

catalyst, the method comprising the steps of: 

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

boiler; 

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

combustion process, wherein the staged combustion 

process produces at least one gaseous phosphorus com 

pound and/or at least one gaseous phosphorus-contain 

ing compound; 

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

combustion zone of a fumace, or boiler; and 

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

react with the at least one gaseous phosphorus com 

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

taining compound present in the combustion zone prior 

to the entry of the ?ue gas into an SCR to form an iron 

phosphorus-containing compound, wherein the SCR is 

located upstream of at least one air heater, 

wherein the iron-bearing compound is selected from one or 

more iron (II) halides, iron (III) halides, iron (III) iodate, 

iron (III) oxide, iron (II) carbonate, or mixtures of two or 

more thereof. 

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

iron-bearing compound is provided to the combustion zone 

via addition to pulverized coal. 

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

iron-bearing compound is provided to the combustion zone 

via a dedicated supply line either in aqueous or in powdered 

form. 

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

compound is a water soluble iron-bearing compound. 

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

compound is a water soluble iron-bearing compound that is 

supplied in the form of an aqueous solution. 
US 8,716,169 B2 

15 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

17. The method of claim 11, wherein the staged combus 

tion process utilizes over ?re air and the staged combustion 

process results in an increased amount of the at least one 

gaseous phosphorus compound and/or the at least one gas 

eous phosphorus-containing compound and results in the 

deactivation of the SCR catalyst. 

18. A method for sequestering one or more gaseous phos 

phorus compounds, or gaseous phosphorus-containing com 

pounds, in the form of one or more less reactive iron-phos 

phorus-containing compounds, the method comprising the 

steps of: 

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

boiler; 

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

combustion process, wherein the staged combustion 

process produces at least one gaseous phosphorus com 

pound and/or at least one gaseous phosphorus-contain 

ing compound; 

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

combustion zone of a fumace, or boiler; and 

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

react with the at least one gaseous phosphorus com 

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

taining compound present in the combustion zone or ?ue 

gas to form one or more less reactive iron-phosphorus 

containing compounds. 

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

compound is selected from one or more iron halides, iron 

iodate, metallic iron, one or more iron oxides, iron carbonate, 

or mixtures of two or more thereof. 

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

compound is selected from iron (Ill) oxide, iron (ll) carbon 

ate, iron (ll) oxide, or mixtures of two or more thereof. 

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

compound is selected from iron (Ill) oxide, iron (ll) carbon 

ate, iron (ll) bromide, iron (Ill) bromide, or a mixture of two 

or more thereof. 

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

iron-bearing compound is provided to the combustion zone 

via addition to pulverized coal. 

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

iron-bearing compound is provided to the combustion zone 

via addition to raw coal which is thereafter pulverized. 

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

iron-bearing compound is provided to the combustion zone 

via a dedicated supply line. 

25. The method of claim 18, wherein the one or more less 

reactive iron-phosphorus-containing compounds further con 

tains oxygen. 

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

compound is a water soluble iron-bearing compound. 

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

compound is a water soluble iron-bearing compound that is 

supplied in the form of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

29. The method of claim 18, wherein the staged combus 

tion process utilizes over ?re air and the staged combustion 

process results in an increased amount of the at least one 

gaseous phosphorus compound and/or the at least one gas 

eous phosphorus-containing compound and results in an 

increased acid gas concentration in the ?ue gas. 

20 

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55 

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65 

1 6 

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

catalyst while concurrently controlling mercury in a gas, the 

method comprising the steps of: 

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

boiler; 

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

bustion process, wherein the staged combustion process 

produces at least one gaseous phosphorus compound 

and/or at least one gaseous phosphorus-containing com 

pound; 

providing at least one iron-bearing halide compound to a 

combustion zone of a furnace, or boiler, prior to entry of 

the ?ue gas into an SCR; 

permitting the iron portion of the at least one iron-bearing 

halide compound to react with the at least one gaseous 

phosphorus compound and/or the at least one gaseous 

phosphorus-containing compound present in the com 

bustion zone or ?ue gas prior to the entry of the ?ue gas 

into the SCR to form an iron phosphorus-containing 

compound, wherein the SCR is located upstream of at 

least one air heater; and 

permitting the halide portion of the at least one iron-bear 

ing halide compound to react with any gaseous mercury 

compounds, or mercury-containing compounds, present 

in the combustion zone or ?ue gas. 

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

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

bromide), iron (11) chloride, iron (Ill) chloride, iron (ll) 

iodide, iron (Ill) iodate, or mixtures of two or more thereof. 

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

halide compound is iron (11) bromide. 

33. The method of claim 30, further comprising supplying 

one or more non-halogen-containing iron-bearing com 

pounds in combination with the at least one iron-bearing 

halide, where the one or more non-halogen-containing iron 

bearing compounds are selected from iron (Ill) oxide, iron 

(11) carbonate, iron (ll) oxide, or mixtures of two or more 

thereof. 

34. The method of claim 30, further comprising supplying 

iron (ll) carbonate in combination with the at least one iron 

bearing halide. 

35. The method of claim 30, further comprising supplying 

iron (11) carbonate in combination with one or more of iron 

(11) bromide or iron (Ill) bromide. 

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

compound is a water soluble iron-bearing compound. 

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

compound is a water soluble iron-bearing compound that is 

supplied in the form of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

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

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

40. The method of claim 30, wherein the staged combus 

tion process utilizes over ?re air and the staged combustion 

process results in an increased amount of the at least one 

gaseous phosphorus compound and/or the at least one gas 

eous phosphorus-containing compound and results in the 

deactivation of the SCR catalyst. 

41. 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: 
US 8,716,169 B2 

17 

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

boiler; 

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

bustion process, wherein the staged combustion process 

produces at least one gaseous phosphorus compound 

and/or at least one gaseous phosphorus-containing com 

pound; 

providing at least one iron-bearing halide compound to a 

combustion zone of a fumace, or boiler; and 

permitting the iron portion of the at least one iron-bearing 

compound to react with the at least one gaseous phos 

phorus compound and/or the at least one gaseous phos 

phorus-containing compound present in the combustion zone or ?ue gas to form one or more less reactive iron 

phosphorus-containing compounds; and 

permitting the halide portion of the at least one iron-bear 

ing halide compound to react with any gaseous mercury 

compounds, or mercury-containing compounds, present 

in the combustion zone or ?ue gas. 

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

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

bromide, iron (11) chloride, iron (Ill) chloride, iron (11) iodide, 

iron (Ill) iodate, or mixtures of two or more thereof. 

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

halide compound is one or more of iron (11) bromide or iron 

(Ill) bromide. 

44. The method of claim 41, further comprising supplying 

one or more non-halogen-containing iron-bearing com 

pounds in combination with the at least one iron-bearing 

halide, where the one or more non-halogen-containing iron 

bearing compounds are selected from iron (Ill) oxide, iron 

(11) carbonate, iron (11) oxide, or mixtures of two or more thereof. 

45. The method of claim 41, further comprising supplying 

iron (ll) carbonate in combination with the at least one iron 

bearing halide. 

46. The method of claim 41, further comprising supplying 

iron (11) carbonate in combination with one or more of iron 

(ll) bromide or iron (Ill) bromide. 

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

compound is a water soluble iron-bearing compound. 

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

compound is a water soluble iron-bearing compound that is 

supplied in the form of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

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

iron-bearing halide compound is provided to the combustion 

zone via addition to raw coal which is thereafter pulverized. 

20 

25 

30 

35 

40 

45 

18 

51. The method of claim 41, wherein the staged combus 

tion process utilizes over ?re air and the staged combustion 

process results in an increased amount of the at least one 

gaseous phosphorus compound and/or the at least one gas 

eous phosphorus-containing compound and results in an 

increased acid gas concentration in the ?ue gas. 

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

catalyst, the method comprising the steps of: 

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

boiler; 

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

bustion process, wherein the staged combustion process 

produces at least one gaseous phosphorus compound 

and/or at least one gaseous phosphorus-containing com 

pound; 

providing at least one iron-bearing compound to a combus 

tion zone of a furnace, or boiler, prior to entry of the ?ue 

gas into an SCR via the addition of the at least one 

iron-bearing compound to pulverized coal, wherein the 

SCR is located upstream of at least one air heater; and 

permitting the at least one iron-bearing compound to react 

with the at least one gaseous phosphorus compound 

and/or the at least one gaseous phosphorus-containing 

compound present in the combustion zone or ?ue gas 

prior to the entry of the ?ue gas into the SCR to form an 

iron phosphorus-containing compound, 

wherein the at least one iron-bearing compound is selected 

from iron (Ill) oxide, iron (11) carbonate, iron (ll) oxide, or mixtures of two or more thereof. 

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

compound is a water soluble iron-bearing compound. 

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

compound is a water soluble iron-bearing compound that is 

supplied in the form of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

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

iron-bearing compound is provided to the combustion zone 

via addition to raw coal which is thereafter pulverized. 

57. The method of claim 52, wherein the staged combus 

tion process utilizes over ?re air and the staged combustion 

process results in an increased amount of the at least one 

gaseous phosphorus compound and/or the at least one gas 

eous phosphorus-containing compound and results in the 

deactivation of the SCR catalyst. 

* * * * *