# E C 

# / R Incorporated Providing Environmental Technical Support Since 198 9

501 Eastowne Drive, Suite 250  Chapel Hill, North Carolina 27514 Telephone: (919)484-0222  Fax: (919) 484-0122 MEMORANDUM

Date: August 31, 2010

To: Anita Lee, U.S. EPA/Region 9

From: Nancy Jones and Stephen Edgerton, EC/R Incorporat ed

Subject: Impact of Ammonia in Fly Ash on its Beneficial Use

1. Purpose

This memo describes the qualitative impacts of amm onia adsorption to fly ash in response to a comment EPA received from the Salt Ri ver Pima-Maricopa Indian Community (SRPMIC) on the Advanced Notice of Proposed Rulemak ing (ANPR) of the Best Available Retrofit Technology (BART) for the Four Corners Pow er Plant (FCPP) located on the Navajo Nation, near Farmington, New Mexico. SRPMIC expres sed concern about adverse economic impact on their fly ash business unit at FCPP if se lective catalytic reduction (SCR) were required to meet BART. Although the comment letter did not provide further detail on the nature of the adverse economic impacts, we assume their concerns relate to the possibility that the use of

ammonia for SCR would result in ammonia contaminati on in the fly ash they obtain from FCPP and make it unusable for certain applications.

In addition to the qualitative discussion of how S CR at FCPP may affect SRPMIC’s fly ash business, we also present information about the ir business and on fly ash beneficial uses in general. We also present an estimate of the amount of ammonia in fly ash from FCPP.

SRPMIC’s comment letter is included in this memora ndum as Attachment 1. Note that the commenter referred to previous testimony that w as not readily available for review.

2. Background

Fly ash is a fine, glass-like powder recovered fro m gases created by coal-fired electric power generation. U.S. power plants produce millio ns of tons of fly ash annually, which is usually landfilled at costs estimated by the Electr ic Power Research Institute (EPRI) to range from $5 to $60 per ton. However, there is a market for fly ash to ready-mix concrete plants, wallboard manufacturers, agricultural soil amendmen t distributers, roadway builders, and others, with sales prices ranging from $10 to $20 per ton. 1

1 http://portfolio.epri.com/ProgramTab.aspx?sId=GEN&r Id=166&pId=557302

The interests of SRPMIC relate to the use of fly a sh in cement manufacturing. Fly ash is an inexpensive replacement for portland cement used in concrete, while it actually improves strength, segregation, and ease of pumping of the c oncrete. As an admixture, fly ash functions as either a partial replacement for, or an addition to , portland cement and is added directly into ready-mix concrete at the batch plant.

Phoenix Cement Company owns the Clarkdale cement m anufacturing plant and has manufactured portland cement since 1959 at its Clar kdale facility, located 100 miles north of Phoenix. Phoenix Cement Company is one of Arizona’ s leading manufacturers of portland cement and other building products. Founded in 195 9 by the American Cement Company to supply materials for the development of Glen Canyon Dam, Phoenix Cement Company has been

a division of SRPMIC since 1987. 2

Phoenix Cement Company has four fly ash sources: t he Escalante Plant is located approximately 90 miles west of Albuquerque, New Mex ico; the Cholla Plant near Holbrook, Arizona; FCPP near Farmington, New Mexico; and the San Juan Plant, also near Farmington -

all of which are within 150 miles of each other. I ts distribution territory includes the states of Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah. In addition to fly ash, the company markets other coal combustion products, seven types of portland cement products, and agricultural gypsum.

3. Effect of SCR on Fly Ash and Subsequent Beneficial Uses

Post-combustion NO

x controls such as SCR result in a certain level of inefficiency in regards to the ammonia reducing process. This inef ficiency results in unreacted ammonia, called “ammonia slip,” in the exhaust gases. Some or all of the ammonia slip ultimately may be adsorbed or deposited on the fly ash. Typically, S CR systems operate with ammonia slip values in the 2 to 5 parts per million by volume (ppmv) ra nge, while SNCR systems operate considerably higher. Ammonia slip can be expected to vary widely depending on changes in operating conditions.

A 2001 EPRI White Paper 3 on the impacts of ammonia contamination on fly ash disposal and use addresses the problems associated with ammo niated ash as a result of increased use of ammonia-based environmental control technologies. The White Paper notes that these processes can result in a fly ash with ammonia content greate r than currently acceptable in the concrete industry, which represents the largest market for t he ash. The sale of fly ash is an important component of ash management at many utilities. It represents both revenue enhancement and reduced disposal costs. A 1996 EPRI study 4 investigated the impacts of the post-combustion

NO

x technologies on ash use. Key findings of this stu dy reported in the White Paper relative to

the ammonia issue were as follows:

• Ash with high ammonia levels may not be acceptable as a cement feedstock. Although the ammonia does not impact the strength of the res ulting concrete, its presence generates

2 http://www.aggregateresearch.com/articles/415/Phoen ix-Cement-Company-Acquires.aspx

3 http://mydocs.epri.com/docs/public/0000000000010046 09.pdf

4 Assessment of Impacts of NOx Reduction Technologie s on Coal Ash Use, “Volume 1: North American Perspective,” TR-106747 V-1, EPRI, November, 1996.3

an odor, and hence, nuisance conditions for workers during placement. Construction and other bulk applications are not impacted unless per sonnel exposure in enclosed spaces is possible.

• With suitable mitigation measures, ash containing a mmonia can still be used in existing pozzolan and concrete markets—albeit at a cost.

• Disposal costs for ash containing ammonia can incre ase due to lower bulk density. The lower density requires more water for compaction an d greater volumes; landfills will not last as long.

• Methods are known for treating ammonia-contaminated fly ash.

The acceptance of ammoniated ash by the ready–mix concrete industry is a function of both technical and economic factors, as well as ins titutional barriers. The relative supply of ash

that does not have an ammonia odor will influence i ts acceptance. If clean ash is available at the same price and quantities, then the ammoniated ash will not be accepted. The ash marketers were surveyed by EPRI in August 2001 to obtain an u pdate on the acceptance of the ashes from

NO

x control systems. They found the acceptable level o f ammonia in ash that the marketplace will accept is in the range of 20 to 60 ppm. This compares to the level of 50 to 100 ppm that is standard practice in Europe. Although ash buyers h ave expressed “philosophical concerns” about the presence of ammonia on ash, there does no t appear to be a significant impact on ash quality or beneficial use potential.

A 2005 EPRI report indicates that there has been n o extensive implementation of ammonia removal technologies, reflecting the genera lly low levels of ammonia contamination in ash that are currently being experienced by the ind ustry, which in turn reflects the relatively

small amount of service hours on the installed cata lyst. This implies that the majority of SCR installations are operating within their design cri teria. However, certain individual sites have

found a need for ammonia removal and several full-s cale installations are in place covering several technologies. This trend is expected to st rengthen as the fleet of SCRs ages and as the issue of ammonia contamination receives higher prio rity. 5

In further research on ammonia-contaminated fly as h, EPRI conducted a survey in early 2007 to which 44 SCR-equipped units responded, whic h were believed to offer a good representation of the domestic SCR-equipped fleet a s a whole. The responding SCR-equipped units were typical of the current "standard" high-d ust type SCR design, having high NO

x removal efficiency and guaranteed ammonia slip on t he order of 2 ppmv. Overall the survey indicated that the adverse impacts associated with ammonia contamination of fly ash are minimal, at least based upon the responding units. The survey overwhelmingly indicated that ammonia contamination is not impacting the ability of plants to sell ash, although it was common for the ash marketer to place maximum limits on the allowable ammonia contamination for ash intended for sale and to independently measure the ammonia concentration. 6

4. Estimate of Ammonia Concentration in Fly Ash if SCR Were Installed at FCPP

We estimated the ammonia concentration in ppm by w eight (ppmw) that might occur if

SCR were installed at FCPP. We based this estimate on site-specific information regarding

5 http://my.epri.com/portal/server.pt?Abstract_id=000 000000001008310

6 http://my.epri.com/portal/server.pt?Abstract_id=000 0000000010142694

Unit 5 at the facility that was submitted by the fa cility as part of their BART analysis, 7 as well as the following assumptions:

• 5 ppmv ammonia slip.

• As-fired ash content of the coal used at the facili ty is 25% by weight.

• 100% of ammonia ends up in the fly ash.

Finally, to estimate the mass of fly ash, we used t he appropriate emission factor for particulate matter from EPA’s AP-42, Compilation of Air Pollutant Emission Factors

. 8

Our analysis resulted in an estimated ammonia cont ent of 245 ppmw in the fly ash. 9 We believe this to be a conservative analysis in that we used an ammonia slip of 5 ppmv, whereas many modern SCR systems operate closer to 2 ppmv. In addition, our analysis assumed that 100% of the ammonia ends up in the fly ash, while i t is typically assumed that only 70 to 80% is retained in the fly ash. Although high, the ash co ntent assumed for the facility is representative

of the coal combusted at FCPP.

5. Effect of Alternative NO

x Reduction Technologies on Fly Ash

Combustion modification techniques, such as Low-NO

x burners (LNB), are the alternative to post-combustion treatments, such as SCR or selective non-catalytic reduction (SNCR) systems, for reducing NO

x formation and emissions. Combustion modification techniques also have an impact on fly ash by increa sing the unburned carbon contained in the fly ash, which can raise other fly ash quality issues. Termed “level of ignition” (LOI), the increased carbon in the fly ash impacts its use in cement and other uses and requires treatment to reduce the carbon level before the fly ash can be used. S everal combustion modification techniques obtained from the U.S. Department of Energy 10 are presented below.

Low-NO

x Burners are designed to control the mixing of fuel and air to achieve what amounts to staged combustion. This staged combusti on reduces both flame temperature and oxygen concentration during some phases of comb ustion and, in turn, reduces both

lower thermal NO

x and fuel NO

x production.

Overfire Air (OFA) is air that is injected into the furnace above the normal combustion zone. Generally when OFA is employed, the burners are operated at a lower than normal air-to-fuel ratio, which reduces NO

x formation. OFA, which is frequently used in conjunction with LNBs, completes the combustion pro cess at a lower temperature.

In the reburning process, part of the boiler fuel input (typically 10-25%) is added in a separate reburn zone. The fuel-rich reducing condi tions in this zone lead to the reduction

of NO

x formed in the normal combustion zone. OFA is inje cted above the reburn zone to

7 “Arizona Public Service Company Four Corners Genera ting Plant Units 1 through 5 Best Available Retrofi t Technology Engineering Analysis,” Appendix A Design Basis, Black and Veach, December 4, 2007. Docket

Number EPA-R09-OAR-2009-0598-0004.3.

8 AP-42, “Compilation of Air Pollutant Emission Fact ors,” Volume I, Chapter 1, Section 1.1, U.S. EPA, 1 998.

9 The calculations are included in the docket for th e FCPP BART determination, filename FCPP_ammonia_ppmw.xlsx.

10 http://www.netl.doe.gov/technologies/coalpower/ewr/ nox/NOx-reduct.html5

complete combustion. Thus, with reburn there are t hree zones in the furnace: (1) a combustion zone with an approximately normal air-to -fuel ratio; (2) a reburn zone, where added fuel results in a fuel-rich condition; and (3 ) a burnout zone, where OFA completes the combustion. Coal, oil, or gas can be used as t he reburn fuel.

Flue Gas Recirculation (FGR) , in which part of the flue gas is recirculated to the furnace, can be used to modify conditions in the combustion zone (lowering the temperature and reducing the oxygen concentration) to reduce NO

x formation. FGR is also used as a carrier to inject fuel into a reburn zone to increa se penetration and mixing.

Operational Modifications involve changing certain boiler operational parame ters to
create conditions in the furnace that will lower NO

x production. Examples include burners-out-of-service (BOOS), low excess air (LEA) , and biased firing (BF). In BOOS, selected burners are removed from service by stoppi ng fuel flow, but airflow is maintained to create staged combustion in the furna ce. LEA involves operating at the lowest possible excess air level without interferin g with good combustion, and BF involves injecting more fuel to some burners (typic ally the lower burners) while reducing fuel to other burners (typically the upper burners) to create staged combustion conditions

in the furnace.

6. Example Commercial Methods for Removal of Ammonia ( and Carbon) from Fly

Ash

When ammonia contaminated fly ash is wetted as par t of a concrete mixture, the gas is released, exposing concrete workers to varying leve ls of ammonia, but there is no quality issue with the cement. However, under certain conditions , unburned carbon in fly ash can cause quality control issues such as interfering with the concrete’s ability to reliably entrain correct amounts of air. Discussed below are a few examples of general and proprietary methods for treating fly ash that contains high levels of carbo n or ammonia. Some methods to reduce carbon are also effective at reducing ammonia that results from SCR and SNCR NO

x reduction techniques.

Carbon Burn-Out (CBO) has long been known as a ver y robust system for carbon removal for various types of ash feedstocks. Ash f eedstocks containing carbon contents as high as 90% have been successfully processed. To date, over 200,000 tons of CBO processed fly ash has been produced. CBO processed ash exhibits exce llent pozzalanic activity, consistent air entrainment, and carbon levels of 21⁄2 % and has gain ed excellent market acceptance in its market areas. CBO’s fluid bed technology provides heat an d residence time dictated by conditions for optimal combustion of carbon found in fly ash. Fly ash residence times of 45 minutes and temperatures in the 1300 degrees Fahrenheit range a re characteristic of the CBO process. Kinetic theory suggests that CBO conditions should be ideal for ammonia removal. Ammonium Sulfate and Ammonium Bisulfate are the two prominen t ammonia compounds found in coal fly ash. Both compounds exhibit low decomposition temp eratures and should readily decompose within the operational conditions of CBO. 11

11 http://www.netl.doe.gov/publications/proceedings/00 /ubc00/GIAMPA.PDF6

A commercial scale carbon separation and ammonia r emoval system designed by Separation Technologies (ST) 12 is operating at the Tampa Electric Big Bend Power Plant and 10 other power stations throughout the U.S., Canada , and the United Kingdom. A three-stage carbon separation process maximizes the fuel value recovered from the company’s ProAsh ® and

EcoTerm TM products. ProAsh ® has been approved for use by over 20 state highway authorities. The ammonia process reduces the ash ammonia level f rom ~2,000 ppm to the less than 75 ppm needed to meet market requirements, and it can hand le up to 52 tons of fly ash per hour.

Headwaters Resources’ 13 proprietary carbon fixation technology is used to pre-treat fly ash using a liquid reagent to coat unburned carbon particles and hinder their impact on the concrete mix. Carbon is not removed, but its effec ts on air entrainment are minimized. The technology also renders some ash products usable fo r the first time without having any impact on the quality of finished concrete. Headwaters Resou rces’ new technology uses a chemical reagent to mitigate ammonia effects. When water is added t o the concrete mix containing ammoniated fly ash, the reagent converts ammonia to harmless c ompounds. The treatment reagent can be added and blended with the dry fly ash at any point between the fly ash collection system at the power plant and final delivery to the ready mixed c oncrete producer.

Carbon BlockerTM 14 is a Patent Pending fly ash treatment process that conditions fly ash

so that desired levels of air entrainment can be ac hieved in concrete products applications. Carbon Blocker works across a broad range of fly as hes even with elevated levels of carbon. Carbon Blocker is used to treat fly ash at more tha n 10 power plants in Kentucky, Indiana, Ohio, Pennsylvania, and West Virginia. Fly ash from thes e plants can now be used at elevated carbon

levels when treated with Carbon Blocker.

In addition, there are products that can be added to the combustion process to reduce fly ash LOI in systems with LNB and OFA. For example, Biofriendly Corporation markets hydrocarbon fuel combustion catalysts (Green Plus ® ) for reducing NO

x and SO 2 emissions and lowering LOI while maintaining or improving fuel us e efficiency.

7. Impact of Other EPA Programs on Beneficial Use of Fly Ash

On June 21, 2010, EPA proposed to regulate the dis posal of coal combustion residuals (75 FR 35128) generated from the combustion of coal at electric utilities and by independent power producers. Under the Resource Conservation a nd Recovery Act (RCRA), EPA’s Office of Solid Waste (OSW) currently regulates coal combu stion residuals (CCR) as non-hazardous waste under the Bevill Amendment that covers high v olume, low toxicity wastes. As a result of the damage caused by a breach and spill of a large CCR sludge impoundment in Tennessee, the proposal contains two options for tightening the re gulations for CCRs. Under one option, CCR

would be listed as hazardous waste under subtitle C of RCRA, while under the other option CCR would continue to be regulated as nonhazardous wast e under subtitle D of RCRA, but EPA would issue national minimum criteria to regulate d isposal of CCR. In either case, EPA is proposing to establish dam safety requirements for CCR disposed of in surface impoundments.

12 http://www.flyash.info/2009/116-gasiorowski2009.pdf

13 http://www.flyash.com/ccpquality.asp

14 http://www.flyashdirect.com/carbonblocker/index.asp7

However, EPA is not proposing to change the May 20 00 Regulatory Determination for beneficially used CCRs. As a result, it is anticip ated the costs for disposal of fly ash as waste will rise and desire for power producers to increas e the beneficial use of fly ash will increase.

8. Discussion

SCR and SNCR use ammonia post combustion to reduce NO

x emissions from coal-fired power plants. Due to ammonia slip, a small amount of the ammonia is emitted to the atmosphere or adsorbed to the fly ash. The resulting ammoniat ed fly ash is less desirable for use in the

cement and other industries because of the odor. T he other option for reducing NO

x emissions from coal-fired power plants are combustion modific ation techniques. These techniques can result in higher carbon content in the fly ash. Un burned carbon in fly ash can interfere with concrete’s ability to reliably entrain correct amou nts of air. There are post-treatments available for both ammonia and carbon in fly ash.

SRPMIC is concerned that if EPA imposes SCR as BAR T for the FCPP it will have an adverse economic effect on its business of buying a nd reselling fly ash for beneficial uses. Figures are not available on what portion of the fl y ash sold by SRPMIC originates at FCPP, but FCPP is the largest of the four power plants from w hich the fly ash is obtained. Questions that figure into the impact of SCR as BART for FCPP on S RPMIC include:

• Will the ammonia have an impact on the market for t heir fly ash?

• Will they be able to replace the FCPP fly ash with a supply from existing or other

sources?

• Will treatment of the fly ash be required and, if s o, what will be the cost for treatment?

• What are the impacts on the tribe if SCR is install ed at FCPP?

It appears that while the ammonia results in odor problems, especially for workers pouring the concrete, there is not an adverse effec t of ammonia on the properties of the concrete or on human or ecological health. As the concrete dries, the ammonia is released at higher levels initially and then more slowly until completely dry

. 15 Ammonia odors can return when concrete is rewetted with the highest concentrations occurri ng within enclosed areas such as basements; however, in the desert Southwest, wet basements may be expected to be less of a concern. Additionally, as more facilities are required to co ntrol NO

x emissions, ammoniated fly ash is likely to become the norm.

As discussed above, EPRI researchers have found th at ammonia contamination resulting from the use of SCR has is not impacting the abilit y of plants to sell ash. Nevertheless, our

conservative estimate of the ammonia content that c ould result from the use of SCR at FCPP indicates at least the potential that ammonia conta mination could be above the acceptable level. If this were the case, SRPMIC could be forced to re place the fly ash from FCPP with other sources. As an alternative, FCPP or SRPMIC could p rocess the fly ash to remove excess

ammonia.

15 Rathbone, B. and Tyra, M., University of Kentucky Center for Applied Energy Research. (2003) http://www.caer.uky.edu/coalash/posters/pcc2002.pdf8

Regarding alternative sources of fly ash, it is no t known whether SRPMIC could replace the fly ash from FCPP with ash from its other three sources. If not, the OSW proposed rule, which would impose more rigid management requiremen ts and potentially reclassify fly ash as a hazardous waste, appears likely to result in an inc reased amount of fly ash available for sale from power plants, because selling fly ash would represe nt an attractive alternative to disposal at a high cost. However, obtaining fly ash from other p ower plants would force changes in SRPMIC’s current processing and distribution system

.

Regarding removal of ammonia from the fly ash, Sec tion 6 above discusses some potential methods. Clearly, this would increase th e cost to ready FCPP fly ash for sale. It is not known whether this increased cost would be borne by SRPMIC or FCPP. As noted above, the OSW rulemaking on power plant ash will affect the e conomics of disposal, which will provide

incentive to utilities to sell as much of the ash a s possible.

In addition to use in concrete manufacturing, fly ash containing ammonia can be used for other purposes as well. For example, the largest u se of ammonia in the U.S. is in the agricultural industry either applied directly to soils or used i n the production of fertilizer. Fly ash has been used in the agricultural industry as a weed prevent ative around trees in orchards. The addition of the ammonia to the fly ash would have a beneficial effect as a fertilizer for the trees. Other uses are covers at animal feed lots and dairy operations to provide a more solid surface than the underlying soil that would become mud when wet. La ndfills use fly ash as daily cover. In both the animal and landfill operations, the odor of amm onia from the fly ash would not be expected to be greater than the ammonia odor from the animal wastes or the multiple odors from landfilled materials. Thus, it appears that ammonia-contamina ted fly ash might still be marketable for

some uses.

Numerous tribes recommended combustion modificatio n techniques, rather than SCR, as BART for FCPP. As described earlier, the option of substituting combustion modification techniques for SCR carries impacts as well. Our qu alitative analysis suggests the impact of increased carbon in the fly ash resulting from comb ustion modification would be greater than the impacts from SCR. Based on the challenges associat ed with higher LOI from LNB and the higher ammonia slip rates from SNCR, we expect that the lowest negative impact to fly ash would be if SCR is installed at FCPP compared to LN B or SNCR. Although not related to any air pollution project, the impact of OSW’s proposed rule could result in a positive impact on the tribe’s fly ash operation.Attachment 1

Salt River Pima-Maricopa Indian Community Comment L etter