US 8,691,719 B2 

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(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 

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

Control of NOX Emissions from Stationary Combustion Sources; 

Ind. Eng. Chem. Res. 2001 (published on the Internet on Jun. 22, 

2001), 40, pp. 3287 to 3293. 

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

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

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. 

Virpi Kroger; Poisoning of Automotive Exhaust Gas Catalyst Com 

ponentsiThe Role of Phosphorus in the Poisoning Phenomena; 

Academic Dissertation, University of Oulu, 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/environmenta 1 / 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 Report dated Aug. 17, 2012 in correspond 

ing PCT application No. PCT/US2012/039175. 

* cited by examiner 
US. Patent Apr. 8, 2014 Sheet 1 0f 2 US 8,691,719 B2 

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US 8,691,719 B2 

1 

SYSTEM AND METHOD FOR INCREASING 

THE SERVICE LIFE AND/OR CATALYTIC 

ACTIVITY OF AN SCR CATALYST AND 

CONTROL OF MULTIPLE EMISSIONS 

RELATED APPLICATION DATA 

This patent application claims priority to and is a continu 

ation-in-part of US. patent application Ser. No. 12/691,527 

?led Jan. 21, 2010 and titled “System and Method for Pro 

tection of SCR Catalyst and Control of Multiple Emissions,” 

which itself claims priority to and is a non-provisional of 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 these patent applications are 

hereby incorporated by reference as though fully set forth 

herein in their entireties. 

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. 

In still another embodiment, the present invention relates 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 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,C 

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,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 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. 

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Regulations issued by the EPA promise to increase the 

portion of utility boilers equipped with SCRs. SCRs are gen 

erally designed for a maximum ef?ciency of about 90%. This 

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

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

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 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 SO3; 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 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 can also act as oxidiZing catalysts, converting CO to CO2 

under proper temperature conditions. However, SO2 oxida 

tion to SO3 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 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. In a typical 100 MWe coal plant the downtime 

and cost associated with the replacement of underperforrning 

catalyst can be in the neighborhood of one million US dollars 

or more. 

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 
US 8,691 ,719 B2 

3 

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. 

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 increase catalytic life span and/or catalytic 

activity of an SCR catalyst while permitting, in some 

instances, the simultaneous removal of various gaseous com 

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

process. 

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 the SCR catalyst. 

In still another embodiment, the present invention relates 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 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; (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 of the ?ue gas into the 

SCR; (c) providing at least one halide-bearing compound to a 

combustion 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 (d) per 

mitting 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 

of at least about 10 percent at an operational time of at 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, the method comprising the steps of: (i) 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; (ii) permitting the at least one iron-bearing 

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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; (Iii) providing at least one halide-bearing com 

pound to a combustion 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 (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, or both, of a catalytic activity and/or a 

catalytic lifespan of at least about 10 percent at an operational 

time of at 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, 

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; (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; (C) provid 

ing at least one halide-bearing compound to a combustion 

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 (D) 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 of at 

least about 10 percent at an operational time of at 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, 

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

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

stream of a fumace, or boiler; (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 or ?ue gas to form one or more less 

reactive iron-phosphorus-containing compounds; (III) pro 

viding at least one halide-bearing compound to a combustion 

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 (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 of at 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 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 compound to a combustion zone or ?ue gas stream of 

a furnace, or boiler; permitting the at least one iron-bearing 

compound to react with any gaseous phosphorus 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 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, of a 

catalytic activity and/or a catalytic lifespan of at least about 

15 percent at an operational time of at least about 4,000 hours. 

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 

FIG. 1 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; 

and 

FIG. 2 is a graph illustrating one example of an increase in 

catalytic activity and catalytic lifespan as realized via utiliza 

tion of a system and method in accordance with one embodi 

ment 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 can be 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,C 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 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 of FIG. 1. In this con?guration, the wet scrubber is 

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

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

advantageously a fabric ?lter (FF) bag house, or an 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 

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particulate or SO3. Alternatively, the present invention 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 FIG. 1. In 

this con?guration, the SDA or dry scrubber is typically fol 

lowed (with respect 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 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, 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. 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 phosphorus 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 another embodiment, the present invention is directed to a system and method 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, or known, rate of decline in catalytic 

activity and/or life for a given a boiler, fossil fuel boiler, kiln, 

heater, or any other type of device 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 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: 
US 8,691,719 B2 

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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 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 can uti 

lize a combination of one or more iron-containing com 

pounds and one or more 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 

halide containing compound. In still another embodiment, the 

at least one iron compound has a generic formula of AX, 

where A is equal to iron and X is either an oxide or carbonate 

ion, anion, group, and/or moiety and the at least one halide 

compound has a generic formula of BY where B is any atom, 

element, or cation except for iron andY is a halide selected 

from chlorine, bromine, ?uorine, or iodine. 

In one embodiment, suitable halides for use in conjunction 

with the present invention 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, calcium iodide, aluminum bromide, alumi 

num chloride, aluminum ?uoride, aluminum iodide, other 

transition metal halides (e.g., bromides, chlorides, ?uorides 

and/ or iodides) with the proviso that the transition metal is not 

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 of phosphorus 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 of phosphorus in a ?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 

rently 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. 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 

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compounds, or mercury-containing compounds, that contain 

primarily, or only, oxidized mercury. 

As used herein, any iron compound suitable for use in 

conjunction with the present invention can be utilized in a 

hydrated or non-hydrated form. As such, reference to any iron 

compound herein by de?nition includes any hydrated forms 

that exists whether or not speci?cally mentioned 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 one or more 

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, or aqueous solution of 

the one or more iron-bearing compounds and/or the one or 

more halide compounds to the combustion zone of a 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 

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 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/or heat 

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 of a 

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?ed as coal pulverizers A-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 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 
US 8,691 ,719 B2 

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

burner line is identi?ed atA in FIG. 1; 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 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 

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

corner- 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 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 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 FIG. 1, 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 

FIG. 1. The upper equipment con?guration in FIG. 1 com 

prises a particulate collection device (PCD) schematically 

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 (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, 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,C 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% e?icient, 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 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

10 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, one or more 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 

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

apparatus for accomplishing this desired result 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; 

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. 

Although not illustrated individually, the system of the 

present invention can, in one embodiment, utilize indepen 

dent storage, delivery and control means (in accordance with 

those described above) for each individual iron and/or halide 

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 referred to 

as 140. Advantageously, the iron-based phosphorus 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 

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 iron-based phosphorus 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, 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, if a suitable, 

real-time sensor 200 for measuring levels of gaseous phos 

phorus in the ?ue gas 28 is not available, ?ue gas samples may 

instead be taken at 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. Provided that subsequent laboratory analyses do not indi 

cate any signi?cant variation in gaseous phosphorus levels in 

the ?ue gas 28, there may be no need for real-time, close 

control of the introduction of iron-based phosphorus reducing 

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, 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 iron-based phosphorus reduction 

compound can be supplied at one or more of the locations G 

through Q shown in FIG. 1. More particularly, the iron-based 

phosphorus 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, it should be noted that in addition to the 

introduction of the one or more iron-based phosphorus reduc 

tion compounds, the above-mentioned systems, methods and/ 

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, the present 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 

ner per the various methods and/ or systems described herein. 

In another embodiment, each type of compound, or even each 

separate compound regardless of type, can be supplied indi 

vidually. In still another embodiment, any combination of two 

or more compounds regardless of type (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, 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 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 of the phos 

phorus present in the combustion and/or ?ue stream is seques 

tered in a suitable iron-phosphorus-oxygen-containing 

compound thereby substantially reducing the amount of cal 

cium/phosphorus/oxygen-containing compounds that are 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

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 combustion and/or ?ue gas stream to react with 

various SO,C compounds resulting in the unwanted production 

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 of iron-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, calcium iodide, aluminum bromide, aluminum chlo 

ride, aluminum ?uoride, aluminum iodide, other transition 

metal halides (e.g., bromides, chlorides, ?uorides and/or 

iodides) with the proviso that the transition metal 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 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 

this instance, if so utilized the one or more 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, aluminum bromide, 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, in this embodiment, soluble in water, 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, 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 cost 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. In one embodiment, the present invention is 

directed to a method and system whereby a stoichiometric 

excess one or more 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 of an SCR catalyst can be unexpect 

edly increased. As can be seen from the graph of FIG. 2, the 

addition of a stoichiometric excess of one or more iron-based 

compounds not only protects the SCR catalyst from poison 

ing via various phosphorus compounds but also increases 

both the catalytic activity and catalytic lifespan over a period 

of at least about 2,000 operational hours. 
US 8,691,719 B2 

13 

Regarding FIG. 2, FIG. 2 is a graph plotting the original 

expected deactivation for a catalyst without the addition of the 

iron-bearing compound, or compounds, of the present inven 

tion versus the actual deactivation of a catalyst with the addi 

tion of an iron-bearing compound of the present invention 

versus the observed deactivation of a catalyst without the 

addition of the iron-bearing compound, or compounds, of the 

present invention. The y-axis of the graph of FIG. 2 is cata 

lytic activity in decimal terms where 0.9 is equivalent to 90 

percent activity as measured when compared to unused virgin 

catalyst as determined using any suitable method for deter 

mining catalytic activity known to those of skill in the art. 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 of a 100 MWe coal plant. 

Given the above, in one embodiment the present invention 

achieves either one, or both, of an increase in catalytic activity 

and/ or an increase in catalytic lifespan via the use, introduc 

tion and/or delivery of one or more 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 of a given catalyst when subjected to similar opera 

tional conditions but not subjected to a supply of one or more 

iron-based compounds as disclosed herein. As would be 

apparent to those of skill in the art, various known methods 

are available to measure the baseline catalytic activity as well 

as the catalytic activity of various catalysts, including SCR 

catalysts. As such, a detailed discussion herein is omitted for 

the sake of brevity. 

In 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 is achieved at an 

operational time of about 2,000 hours, an increase of at least 

about 12.5 percent is achieved at an operational time of about 

2,000 hours, an increase of at least about 15 percent is 

achieved at an operational time of about 2,000 hours, an 

increase of at least about 17.5 percent is achieved at an opera 

tional time of about 2,000 hours, an increase of at least about 

20 percent is achieved at an operational time of about 2,000 

hours, an increase of at 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 2,000 hours, an increase of at least about 27.5 percent is 

achieved at an operational time of about 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 of one 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. 

In still 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 is achieved at an 

operational time of about 2,500 hours, an increase of at least 

about 12.5 percent is achieved at an operational time of about 

2,500 hours, an increase of at least about 15 percent is 

achieved at an operational time of about 2,500 hours, an 

increase of at least about 17.5 percent is achieved at an opera 

tional time of about 2,500 hours, an increase of at least about 

20 percent is achieved at an operational time of about 2,500 

hours, an increase of at 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 

25 

30 

35 

40 

45 

50 

55 

60 

65 

14 

about 2,500 hours, an increase of at least about 27.5 percent is 

achieved at an operational time of about 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 of one 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. 

In still yet another embodiment, the present invention 

achieves an increase in either one, orboth, 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 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 of about 3,000 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 of one 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 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 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 10,000 hours, about 1 1,000 hours, about 12,000 hours, 

about 13,000 hours, about 14,000 hours, about 15,000 hours, or even about 16,000 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 of one 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 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, an 

excess stoichiometric ratio is utilized. In one embodiment, 

the excess stoichiometric ratio of iron to phosphorus is in the 

range of about 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 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 5 pounds of “iron” per 1,000 

pounds of coal to about 20 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 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 1,000 pounds of coal to about 15 pounds 

of “iron” per 1,000 pounds of coal, or from about 7 pounds of 

“iron” per 1,000 pounds of coal to about 12.5 pounds of 

“iron” per 1,000 pounds of coal, or from about 7.5 pounds of 

“iron” per 1,000 pounds of coal to about 10 pounds 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?cation and claims, individual range values can be 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 in the range of about 95 weight parts iron based 

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 in the range of about 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 of the 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 

more halide compounds, if so utilized in conjunction with the 

present invention, for controlling mercury in a ?ue gas, or 

combustion gas, is based on a non-limiting example of a 100 

MWe coal power plant. In this case, the injection rate for the 

one or more halide compounds, if in solution, is 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, regardless of power plant or combus 

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 in place on the device generat 

ing the ?ue gas, or combustion gas, it may 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 of such an instance the concentration 

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

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, in accordance with the process of 

the present invention will vary depending upon the size of the 

device generating such ?ue gas, or combustion gas. The same 

can be said of the one or more halide 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 of halide to a ?ue gas, or combustion gas, in accor 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

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 of halide 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 halide. 

As would be apparent to one of skill in the art, other 

additional factors can impact the amount of iron-based, iron 

bearing and/ or iron compounds supplied in connection with 

the various embodiments of the present invention. Such addi 

tional factors include, but are not limited to, the amount 

and/or type of phosphorus present in the coal, or other com 

bustible 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 

and/or the one or more halide compounds utilized in conjunc 

tion 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, 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, can be supplied in the form of one or more particle 

geometries. In one embodiment, the one or more iron com 

pounds and/ or the one or more halide compounds of the 

present invention, if water soluble, can be supplied in 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 

soluble halide 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 per 

cent, at least about 35 weight percent, 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 and/or the one or more water soluble halide 

compounds is utilized in conjunction with the present 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 

ciated by those of skill in the art, the solution concentration of 

any one or more water 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 or more iron compounds and/ or the one or more 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, or a combination 

of two or more thereof. In the case of an aqueous suspension, 

the one or more iron compounds and/ or the one or more halide 
US 8,691,719 B2 

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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 and/ or the 

one or more halide compounds of the present invention into 

an aqueous solution, the one or more iron compounds and/or 

the one or more halide compounds should have a suitable 

particle size that facilitates a higher degree of reactivity when 

placed into contact with a ?ue, or combustion, gas. In one 

embodiment, both 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 

of the particles have a particle size of less 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 of the particles have a particle 

size of less 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 of the particles have a particle size of less than about 

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

cation and claims, individual range values can be combined to 

form additional and/ or non-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 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 

weight with substantially all of the remaining 20 weight per 

cent being non-reactive in light of the use here. A suitable 

halide compound for use, if so desired, in conjunction with 

the present invention is calcium bromide available from Tetra 

Chemical (located in The Woodlands, Tex.). 

In the instance where one or more aqueous suspensions 

is/are utilized in conjunction with the present 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 

ited to, sodium polyacrylates, carbomers, acrylates, and inor 

ganic thickening agents. Other suitable anti-settling, suspen 

sion, 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 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 60 weight percent, at least about 65 weight 

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

weight percent, at least about 80 weight percent, at least about 

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

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

percent or higher. 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. 

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18 

As for the portion of the one or more 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, if reactive, such impurities 

should either be 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 and/ or the one or more 

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 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 percent. 

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 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 should be zero. That is, in this embodi 

ment the one or more iron compounds and/or the one or more 

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 sequester various phosphorus 

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. 

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 or more 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 

taining halogen compound (e. g., calcium bromide 10 percent 

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 bonded mineral 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 

iron separately, provides “free” iron that, while not wishing to 

be bound to any one theory, is believed to settle onto and/or be 

deposited onto the surface of ?y ash which makes it available 

for further chemical reactions. 

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

above can then provide iron for increasing the catalytic activ 

ity and/ or catalytic lifespan of the DeNO,C catalyst while, if so provided, the halogen portion of the one or more halide com 

pounds of the present invention acts to aid, or achieve, mer 

cury oxidation. While not wishing to be bound to any one 

theory, is believed that when the ?y ash gets deposited on the 

surface of SCR catalyst the iron on the surface of ?y ash or 

iron deposited on catalyst as a result of the injection process 
US 8,691,719 B2 

19 

provides sites onto which ammonia and NO,C can react to form 

N2 and water. As the iron is injected continuously at a low rate 

of injection, any active iron sites that become depleted are 

replaced by 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 similar untreated 

catalyst as explained in detail above. The halogen portion of 

the halide compound, or compounds, oxidizes elemental mer 

cury into its oxidized form and make it easier for removal by 

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

While not wishing to be bound to any one example, data to 

support this invention is supplied from a long-term injection 

test of iron carbonate at a 100 MWe coal power plant. Before 

exposure of the 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 of catalyst. 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 

percent Fe in bulk. Previously used catalyst (no FeCO3 inj ec 

tion from the same site) had 0.26 percent Fe on surface and 

0.06 percent Fe in bulk after 11,000 hours of operation. 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 2.6 ppm. This proves that iron injection into the furnace 

is indeed reaching the SCR. The increase in SO3 concentra 

tion can be related to the presence of iron 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 of operation. The lower plot (diamonds) illus 

trates the actual performance for this catalyst. The catalyst 

actually lasts for only 6,800 hours of operation due to phos 

phorus deactivation. The middle line (triangles) illustrates the 

performance of a catalyst subjected to at least the iron com 

pound injection of the 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 reaction by injection of one 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 invention provide 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 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. 

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20 

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 or ?ue gas stream of the 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; 

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

an iron phosphorus-containing compound; 

(e) providing at least one halide-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, with the 

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, of a catalytic activity and/ or a catalytic lifespan of 

at least about 10 percent at an operational time of at least 

about 2,000 hours. 

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

pound is selected from 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 (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. The method of claim 1, wherein the halide-bearing com 

pound is selected from potassium bromide, potassium chlo 

ride, potassium ?uoride, potassium iodide, sodium bromide, 

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 of claim 1, wherein the at least one halide 

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

bearing compound is provided at suf?cient amount to yield a 

halide concentration of between about 10 ppm to about 200 

PPm~ 

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

pound is a water soluble iron-bearing compound. 

15. 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. 

16. 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. 

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

bearing halide compound is provided to the combustion zone 

via addition to raw coal which is thereafter pulverized. 

18. 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. 

19. 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 or ?ue gas stream of the 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; 

(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 or ?ue 

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

an iron phosphorus-containing compound; 

(v) providing at least one halide-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, with the 

proviso that halide-bearing compound is not an iron 

halide; and 

(vi) 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 of 

at least about 15 percent at an operational time of at 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 of two or more thereof. 

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55 

60 

65 

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 transition metal 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 and the halide 

bearing compound is selected from calcium bromide. 

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

halide-bearing compound is provided to the combustion zone 

via addition to pulverized coal. 

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

halide-bearing compound is provided to 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 of iron to phosphorus is in the range of about 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 of iron to phosphorus is in the range of about 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 

yield a halide concentration of between about 10 ppm to 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 of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

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

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

36. The method of claim 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 of the SCR catalyst. 

37. A method for simultaneously sequestering one or more 

gaseous phosphorus compounds, or gaseous phosphorus 

containing compounds, in the form of one or more 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 of the 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; 

(E) providing at least one halide-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, with the 

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, of a catalytic activity and/ or a catalytic lifespan of 

at least about 10 percent at an operational time of at 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 of two 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 transition metal 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 and the halide 

bearing compound is selected from calcium bromide. 

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

halide-bearing compound is provided to the combustion zone 

via addition to pulverized coal. 

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

halide-bearing compound is provided to 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 of iron to phosphorus is in the range of about 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 of iron to phosphorus is in the range of about 3.5:1 to 

about 8:1. 

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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 

yield a halide concentration of between about 10 ppm to about 

200 ppm. 

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

reactive iron-phosphorus-containing compounds further con 

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 of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an aqueous suspension or emulsion. 

54. The method of claim 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. A method for simultaneously sequestering one or more 

gaseous phosphorus compounds, or gaseous phosphorus 

containing compounds, in the form of one or more 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 of the 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 or ?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, prior to entry of the ?ue gas into an SCR, with the 

proviso that halide-bearing compound is not an iron 

halide; and 

(IV) (V l) 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, of a catalytic activity and/ or a catalytic lifespan of 

at least about 15 percent at an operational time of at 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 of two 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, or mixtures of two 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 transition metal 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 and the halide 

bearing compound is selected from calcium bromide. 

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

halide-bearing compound is provided to the combustion zone 

via addition to pulverized coal. 

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

halide-bearing compound is provided to 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 of iron to phosphorus is in the range of about 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 of iron to phosphorus is in the range of about 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 

yield a halide concentration of between about 10 ppm to about 

200 ppm. 

68. The method of claim 55, wherein the one or more less 

reactive iron-phosphorus-containing compounds further con 

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 of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an 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 

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 the furnace, or boiler; 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 

20 

25 

30 

35 

40 

45 

50 

55 

60 

65 

26 

compound present in the combustion zone or ?ue gas to 

form one or more less reactive iron-pho sphorus-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, of a catalytic activity and/ or a catalytic lifespan of 

at least about 15 percent at an operational time of at 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 of two 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, or mixtures of two 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 transition metal 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 and the halide 

bearing compound is selected from calcium bromide. 

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

halide-bearing compound is provided to the combustion zone 

via addition to pulverized coal. 

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

halide-bearing compound is provided to 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 of iron to phosphorus is in the range of about 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 of iron to phosphorus is in the range of about 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 

yield a halide concentration of between about 10 ppm to about 

200 ppm. 

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

reactive iron-phosphorus-containing compounds further con 

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 of an aqueous solution. 

89. The method of claim 73, Wherein the iron-bearing 

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an 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 

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 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 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 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 of at 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, or mixtures of two 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 of iron to phosphorus is in the range of about 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 of iron to phosphorus is in the range of about 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 of an aqueous solution. 

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

compound is a water insoluble iron-bearing compound that is 

supplied in the form of an 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. The method of claim 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 of the SCR catalyst. 

* * * * * 
USOO8691719B2 

(12) United States Patent (10) Patent N0.2 US 8,691,719 B2 

Gadgil et a]. (45) Date of Patent: *Apr. 8, 2014 

(54) SYSTEM AND 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 CATALYST AND 423/99 

CONTROL OF MULTIPLE EMISSIONS 

(75) Inventors: Mandar R. Gadgil, Akron, OH (U S); S. 

Behrooz Ghorishi, Uniontown, OH 

(Us) 

(73) Assignee: Babcock & Wilcox Power Generation 

Group, Inc., Barberton, OH (US) 

( * ) Notice: Subject to any disclaimer, the term of this 

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 2011/0229388 A1 Sep. 22, 2011 

Related US. Application Data 

(63) Continuation-in-part of application No. 12/691,527, 

?led on Jan. 21, 2010. 

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

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 search history. 

(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 of Poisoning of the VZOS/TiOZ Catalyst 

for the Reduction ofNO by NH3; 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 

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. 

In still another embodiment, the present invention relates 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