# Vinson&Elkins

Molly Cagle mcagle@vclaw.con1 Tel 512.542.8552 Fax 512.236.3280

ViaRegularand ElectronicMail

Chance Goodin Texas Commissionon Environmental Quality 12100Park 35 Circle MC-206 Austin Texas 78753**C~(** lodin«f:tceq.slak.lx.us

Re: Initial Control StrategyDevelopmentfor DFW OzoneNonattainmentArea

DearMr. Goodin:

We are writing on behalf of Ash Grove Texas, L.P., which appreciates TCEQ's interest in gathering infonnation as early as possible in its next round ofair qualityplanning for the DFW ozone nonattainment area. Ash Grove operates one of three cement manufacturing plants in Midlothian, Ellis County, which is located within the designated DFW nonattainment area. Ash Grove's kilns usethe wet process, the others use dry. We are submitting these informal comments in the interest ofreminding TCEQ about Ash Grove's history of controlling its NOx emissions, and to provide current information about NOx control options for cement plants generally. Those seeking purportedly easy solutions for DFW's ozone nonattainment often tout yet further controls on Ash Grove's kilns, but such controls areneithereasynorsolutions.

I. Ash Grove History

Ash Grove's Midlothian Plant has a proven history of reducing NOx emISSIOns. From 1996 (a yearbeforeEPA promulgatedthe current 0.08 ppm ozone standard) until 2006, the Plant reduced its annual NOx emissions by around 45%. These emission reductions occurred as a result of methodical and judicious implementation of various technologies, such as optimized computer controls for the kilns, improvements to kiln burners, and installation ofoneofthe most successful tire-derived fuel systems in the country. Theuseof tire-derived fuel, injected mid-kiln, not onlyreduces NOx emissions generated at theburning
zone ofthe kiln, but safely eliminates millions ofscrap tires that otherwise might end up in Texaslandfills and illegal dumpsites.

But Ash Grove's NOx reductions did not end in 2006. In 2007, after substantial investigation of the French cement plant that pioneered the first use of Selective Noncatalytic Reduction (SNCR) on wet-process cement kilns, Ash Grove purchased and installed

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# \/&£ Chance Goodin July30, 2010 Page 2

an SNCR system on its three Midlothian kilns. Ash Grove started operating this SNCR system-thefirst ever pm a wet cement kiln in the U.S.--duringthe 2008 ozone season, one full year before it was required under the 2007 SIP. SNCR operation has resulted in an additional 35% reduction in NOx emissions, on top ofthe roughly 45% reduction achieved from the othercontrol measures alreadydiscussed.

As a result ofAsh Grove's efforts, the Midlothian Plant is among the best-controlled cement plants in Texas, measured in amount ofNOx emissions per ton ofcement produced: Only 3 of21 operatingkilns in Texas did anybetter in 2008. Ash Grove was the first in the U.S. and now is among the very few wet process kilns in the world to successfully run SNCR. As compared to the experience of those who have experimented with Selective CatalyticReduction (SCR) technology, it is clearthatAsh Grovemadetherightchoice.

II. SNCRIstheBestAvailableNOx ControlTechnologyfor CementKilns

Ash Grovedid not install SNCR on all three ofits kilns without carefully evaluating all options available to reduce NOx emissions. In 2006, Ash Grove representatives visited the cement plants in Europe that pioneered each ofthe two competing technology options under consideration, SCR at the Solnhofen Plant in Germany and SNCR at the Lumbres Plant in France. As a result of these visits and after carefully evaluating the technical challenges, costs, and expected results associated with each technology option for its Midlothian Plant, Ash Groveconcludedthat SNCR was thebestoption, for several reasons:

• Catalyst Degradation is a Major Problem for Cement Kiln Application ofSCR. SNCRdoes not rely on a catalystto reduceNOx emissions, so there is no degradation ofreduction efficiency over time. Ash Grove observed this degradation during its site visit to the Solnhofen Plant, and the problem has persisted to the point that Solnhofen instead has been operating an SNCR system instead of SCR since 2006. The SCR system operated only for very short periods, and required extensive offline repairs and replenishment. As a result, the highest rate of compliance with the applicableNOx limitjumped from 90.8 percent in 2005 using SCR, to 96.4 percent in 2006, when theplant switchedto using SNCR.

• Catalytic Systems Generate Unintended Emission Consequences. For SCR to work at the Midlothian Plant, the gas leavingthe kiln would needto bereheated from its current exhaust temperature of around 350 OF, to the catalysis temperature of around 650 OF. It is not possible to increase the temperature ofthe exhaust gases from the kiln by several hundred degrees by choosing to run the kiln hotter, at least without severely affecting the operational performanceofthe kiln. Accordingly, any

# V&£ Chance GoOdin July30, 2010 Page 3

SCR installation also would require a reheat system, with its attendant fuel costs and higher emissions.

The catalyst used in all SCR systems also contributes to the production of sulfuric acid gas, at least if there is S02 gases present in the kiln exhaust stream. The expected increase in sulfuric acid production would require the installation of a scrubber system at a significantcapital and operatingcost.

• Capital Costs ofSNCR are SubstantiallyLower. An SNCR system does not need
a catalyst or a catalyst tower. The SNCR reagent used at Ash Grove (water-based solutions of ammonia or urea) is pumped into a point in the kiln where the temperature of the gases already is hot enough to allow NOx reductions to occur without affecting the process. The capital cost to install an SNCR system were significantly lower than for SCR, and the operating and maintenance costs also are lower. Of course the incremental cost associated with SCR now would be astronomical in terms ofNOx removal because Ash Grove's SNCR is operating so efficiently. And because there is no catalytic production of sulfuric acid with an SNCR system, there is no need to install yet another emission control device for this unintended co-product.

• SCR Has Not Been Demonstrated at All in Any Substantially Similar Application. Any rational consideration of a major capital expenditure requires proofthat the technology to bepurchased will work in the application for which it is being considered; indeed, demonstration ofthetechnology is a majorconsideration in any BACT analysis conducted for new source permitting. Even worldwide experience offers no such demonstration.

Ifthe Solnhofen experience demonstrates anything, it is that SCR does NOT work consistentlyon cementplants. And whatever Solnhofen had demonstrated would not likelybeuseful to Ash Grove's Midlothian Plant due to the substantial differences in kiln design and raw materials.

SCR has been installed on two other plants in Europe, but neither ofthese provides a demonstration of likely success if applied to Ash Grove's Midlothian Plant. Like Solnhofen, each is substantiallydifferent from Ash Grove in terms ofdesign and raw materials.

The experience with the high-dust SCR system at Monselice, Italy, a small preheater kiln plant, parallels that ofSolnhofen. The Monselice SCR started around the time

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that Solnhofen gave up (in June 2006). A primary purpose ofthe catalytic system
was to control ammonia (and odor), not NOx. Like Solnhofen, Monselice also has experienced significant problems with dust buildup on the catalyst, and has had to replace andregeneratethecatalystoften andperform manual cleaning:

June 2006 SCRbegan operation. July2007 Catalyst was removed and sent for regeneration. New catalystinstalled. February2008 The second set of catalyst was removed, and the regenerated catalyst was installed. The SCR was modified to reduce the catalyst bed from 24 m3 to 16 m3 in an attempt to reduce pressure drop
acrossthecatalyst. October2008 Installed alargerpitch catalyst in the first layer. Installed heated compressed air cleaning system to try to reduce sticky buildup on the catalyst particularly duringthe wintermonths. April 2009 Replaced second and third catalyst

.layers with larger pitch. System still requires catalystbypass 2 to 3 times per year for manual removal ofthe dust buildup on the catalyst. These cleaning periods are approximately 72 hours in duration.
Monselice, in short, remains in the shakedown mode more than five years after installing SCR, and hasbeen unable to achieve sustained operations and performance usingthattechnology.

The other European cement plant to try SCR, in Sarche, Italy, is a 700 ton per day Lepol kiln, much smaller and ofmuch different design than Ash Grove's Midlothian Plant. A Lepol kiln consists of a shorter kiln system with a traveling grate heater preceding the kiln. None ofthe kilns in Texas are of this type. The Sarche SCR system started operation in 2007, primarily to control ammonia emissions and odors and to reduce visible emissions; that is, the catalyst was installed to reduce ammonia gases generated from the processing ofthe raw materials available to that facility. Becausethekiln processgeneratesNOx as well, ammonia is reducedbyreacting with NOx in the SCR unit. The same couldoccurin an SNCRreaction ifthe ammonia and NOx were in contact at the right temperature. However, most ofthe ammonia at the Sarche facility is released at a temperature too low for the 

### non-catalytic reduction of NOx and ammonia. Therefore, Sarehe needed to use catalyst to achieve its objection.. TQ...r'**\:~L** Chance Goodin July 30. 2010 Page 5

of reducing ammonia. The Midlothian Plant's exhaust, substantial reheating. In contrast, would need

In addition to fundamental design differences, raw material differences also prevent reliance on any successful performance ofSCR in Europe to draw conclusions about performance at facilities in Texas. None of the three SCR units in Europe are installed on kilns that process high-sulfurraw materials, such as those in Midlothian. The sulfur in raw materials exits the kilns, regardless ofkiln type, as sulfur dioxide (SOz) in the kiln gases. The SCRcatalyst will oxidize the SOz to S03. The S03 then reacts with moisture in the stack gases to form HzS04, which corrodes duct work and steel stacks. There are catalyst formulations to minimize the conversion of SOz to S03, but some conversion will occur. Therefore, the Midlothian kilns would likely require awet scrubberto address SO)!HzS04, at a significant additional cost.

Ash Grove is aware ofa dry process cement plant located in Joppa, Illinois, that has agreed to install an SCR system as part ofa consent decree with EPA. Ifbuilt, this will be the only full-scale application ofSCR on a cement kiln in the U.S. But the technology is certainly not yet proven: Under the terms ofthe consent decree, the Joppa SCRis notrequiredto be installed until 2013, whichmeans thatit is atbest still is design phase, and not yetproving anything about actual performance.

But even ifit were put into successful operation, it would not prove up SCR for Ash Grove's Midlothian Plant any more than do the cxperiences in Europe. As with the European plants, the designs are not comparable: Ash Grove has only wet kilns in Midlothian, whereas the Joppa plant consists oftwo long dry kilns. As noted, Ash Grove would need to reheat the exit gas to achieve catalysis temperatures, whereas Joppa already operates with much higher exhaust gas temperatures and so will not have to reheat its exhaustgases.
And there is no guaranteethat thenew SCR atJoppa-ifinstalled and operated-will achieve NOx levels as low as those already achieved with SNCR at Ash Grove. The Joppa consent decree compels no specific level of NOx reductions; instead, the facility is required to monitor the performance ofthe SCR unit and establish a new NOx limitbased onsite-specificconditions. Ash Grove already has demonstrated the ability to achieve NOx emission rates lower than those achieved by SCR-equipped plants, cvenduringtheperiods when those SCR systems are working.

• Ash Grove's SNCR System Achieves Lower NOx Emission rates than the SCR Systems Attempted in Europe. It makes no sense to impose any further technicalChance Goodin July 30, 2010 Page 6

risk or cost in search oflower NOx emissions from Ash Grove's Midlothian Plant, when SNCR works so well. Ash Grove's Midlothian Plant achieves an outlet NOx emission rate ofabout 280 mglNm3 using SNCR. Even when their SCR systems actually function, none ofthe SCR systems tried in Europe are able to do as well: Ash Grove's emission rate is over 40 % less than achieved by Solnhofen (500 mg/Nm3 ), 30% less than Monselice (400 mg/Nm3 ), andalmost 50% less than Sarche (540 mg/Nm3 ).



### • Ash Grove's Decision to Choose SNCR is Affirmed by National Practice. No BACTdetermination has compelled installationofSCRon a cementkiln anywhere in the U.S., no doubt becauseofthe various factors discussed above.



### III. Any Further Reductions in NOx Emissions from Midlothian Cement Plants OfferNo MarginalOzoneAttainmentBenefit. Regulation should never impose undemonstrated technology at great cost, especially when-ashert>-itwould accomplish none ofthe intended goals ofthe regulation even ifthe technology succeeds. TCEQ and other experts have understood that, historically, the ozone monitoring sites that drove DFW's ozone status were dominated by concentrated mobile
source emissions. Even total elimination ofAsh Grove's NOx emissions had no meaningful effects on the DFW ozone design values. Even the maximum attributed ozone reduction (eliminating all ofAsh Grove's NOx emissions) is far below the ability ofthe monitor to
even detect, and amounts to modeling "noise,"at best.



### IV. Conclusions
Althoughthe impact from Ash Grove's NOx emissions onthe attainment status ofthe region is immeasurable, Ash Grove has continued to reduce its emissions by implementing emission control technologies that are economically sustainable and reliable. Ash Grove's Midlothian Plant has achieved 60% reductions in its NOx emissions overthe last decade. As
a result, its NOx emissions per unit ofproduct are now among the lowest ofany kiln in the State. The Midlothian Plant not only produces a product essential to the growth and maintenance of the region, but contributes significant positive effect on the State's environment byprovidingreuse ofmillions ofscrap tires. When considering additional NOx reductions from Ellis County cement kilns, TCEQ should continue to consider the modeled impact of such reductions on ozone design values, and weigh that against the very real economic and operational impact on the facilities that need to comply with even tighter NOx emission limits.T rfl--I:"'**V~L** ChanceGoodin July 30. 2010 Page 7

Although SCR has been promoted in the past as an alternative or even superior technology to SNCR in controlling NOx emissions at cement plants, in practice, SCR is significantly more difficult to implement, requires more capital investment, is likely to require significant catalyst maintenance, and-ultimately-it has not been shown to consistently and reliablyofferEllis Countykilns abetter solution than SNCR to reduce NOx emissions.
Again, we are grateful for the opportunity to help inform yourjudgment, as TCEQ continues its efforts to achieve ever-lower ozone standards in the DFW area. Should you have any questions, please contact me at (512) 542-8552, or Curtis Lesslie at (913) 319­ 6065.
Verytrulyyours,

# 0~~**MOllYCa~**

cc: Curtis Lesslie ]acquelineClark FranciscoPinto Eric Groten

US 493781v.1