Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 1

Best Available Retrofit Technology (BART) Analysis of Control Options

For

CEMEX Inc.

– Lyons Cement Plant

I. Source Description

Owner/Operator: C emex Source Type: Portland Cement Manufacturing Kiln Type: Modified Long

- dry Kiln

Review: Best Available Re trofit Technology (BART)

History :
The Cemex facility manufactures Portland cement and is located in Lyons, Colorado, approximately 20 miles from Rocky Mountain National Park. The Lyons plant was originally constructed with a long dry kiln. This plant sup plies approximately 25% of the clinker used in the regional cement market. There are two potential BART eligible units at the facility: the dryer

and the kiln.

In 1980, the kiln was cut to one

- half its original length, and a flash vessel was added with a single

- stage preheater. The permitted kiln feed rate is 120 tons per hour of raw material (kiln feed), and on average yields approximately 62 tons of clinker per hour. The kiln is the main source of SO2 and NOx emissions. The raw material dryer emits min or amounts of SO2 and NOx; in 2008 Cemex reported SO2 and NOx emissions from the dryer as 0.89 and 10.41 tons per year respectivel y based on stack test results.

Newer multistage preheater/precalciner kilns are designed to be more energy efficient and yie ld lower emissions per ton of clinker due to this when compared to the Cemex Lyons kiln. TheColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 2 newer Portland cement plants studied by EPA, utilize multistage preheater/precalciner designs that are not directly comparable. Cemex has a unique single stage p reheater/precalciner system with different emission profiles and energy demands. New Portland cement plants have further developed the preheater/precalciner design with multiple stages to reduce emissions and energy requirements for the process. Addition ally, new plant designs allow for the effective use of

Selective Non

- Catalytic Reduction (SNCR), which requires ammonia like compounds to be injected into appropriate locations of the preheater/precalciner vessels where temperatures are ideal (between 1600

- 2000oF) for reducing NOx to elemental Nitrogen.

Process Description :
Limestone and other raw materials extracted from the quarry are processed through a primary crusher at the Dowe Flats quarry. The crushed material is transported to the plant on a 2.0 m ile belt conveyor system and discharged to a stockpile. The stockpiled material is placed on a belt by means of a front end loader to be processed through a primary crusher, the dryer, and a secondary crusher. The material from the secondary crusher is s tored in raw material storage

silos.

These storage silos contain silica and iron ore and various quarried raw materials. Material from these storage silos is discharged to weigh belts for the formulation of a desired product. The weigh belts discharge to the raw mill. The raw mill mixes and crushes the blended materials and delivers the homogenized material to storage silos. The homogenized material from the storage silos is delivered to the calciner portion of the kiln. Pulverized coal from the coal m ill is fired at

the bottom of the flash calciner. The partially calcined material from the calciner then enters the

14 foot 3 inch diameter

- 245 foot long rotary kiln, which is located at a slight incline along its horizontal axis. The Cemex kiln proces s

- type is best categorized as a modified long dry kiln. The material travels towards the clinker discharge end where additional pulverized coal is fired for the clinkering process. The clinker is discharged from the kiln into the clinker cooler where

it is cooled by air forced through the clinker bed by un der grate fans. The cooled clinker is then moved to internal storage in an A

- Frame building, or outside storage stockpiles. The stored

clinker is the raw material for the finish mill. In the finish mi ll the clinker is combined with

gypsum and other additives , ground to a fine material and stored in product silos. The material in the product silos can be loaded for bulk transport, or sent to a packaging system.

From an overall perspective, the manufact uring process may be viewed as two segments

-- clinker production and cement production. The clinker storage allows the two processes to operate at different production rates. During periods of low demand for cement, clinker is

accumulated. If cement is in high demand, the clinker production can be supplemented by purchase of clinker from other sources. The overall result is the clinker production can operate at a rather steady rate, while the cement production can operate in response to the current or

p rojected demands.

II. Source Emissions

There are two BART eligible units at the Cemex facility, the dryer (point 003) and the kiln (point 007). Regulation Number 3 requires sources to submit an Air Pollution Emission Notice (APEN) on each emission point a t least every five years. Typically, emission points with low emissions are updated every five years whereas points with higher emissions are updated annually, since fees are assessed on these emissions.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 3 Table 1 lists the APEN reported emissions from th e dryer and emission inventory records collected during routine inspections

. The 1999 APEN is based on emission factors, whereas the 2003, 200 8 and 200 9 APEN s are based on a stack test. The Division has determined that the 2008 emissions best represent s b aseline emissions for the dryer since stack test data is considered

more reliable then emission factors. Furthermore, the 2008 clinker production is representative of typical operations because it falls within the normal range of the historical average (p lease see Table 3 below). Consequently, for purposes of this analysis t he dryer has baseline emissions of NOx = 10.41 tpy; SO2= 0.89 tpy ; and PM10 = 5.12 tpy; based on a recent stack test

. Table 1: Dryer Emissions

Dryer SCC

- 30500620

Pollutant SO2 NOx P M10 CO

Allowable Emissions * [ tpy ] 36.70 13.90 22.80 57.30

1999 APEN Emissions [ tpy ] 31.10 13.30 22.20 55.40

2003 APEN Emissions [ tpy ] 0.64 1.83 1.89 3.83

2008 APEN Emissions [tpy ] 0.89 10.41 5.12 2.97

200 9 APEN Emissions [tpy] 0.37 4.27 2.10 1.22

Baseline [tpy] 0.89 10.41 5.12 2.97

% Baseline is b elow Allowable Emissions

- 97.8%

- 25.1%

- 77.5%

- 94.8%

Baseline Emissions [lbs/ton of Clinker] 0.004 0.04 0.02 0.01

* Current emission limitations are contained in operating permit (95OPBO082)

Table 2 b elow lists the emissions from the k iln. The APEN reported SO2, NOx and CO

e missions are based on continuous emission monitoring systems (CEMS) and the PM10

emissions are based on periodic stack test s

. The Division has determined that the 2002

emissions b est represent baseline emissions for the k iln because it corresponds to the high range for SO2 emissions (which can vary significantly due to pyrites in the limestone) and NOx

emissions are within the normal historical range along with clinker production w hich is near the historical average. There is an increase in kiln PM10 emissions starting in 2007 because of a change in CDPHE’s APEN reporting policy, which allows for the grouping of common stacks associated with kiln ( process group P007 ) and a change t o reporting PM10 emissions based on periodic stack tests rather than the use of emission factors . Consequently, the 2002 PM10

emissions are not the most realistic depiction of anticipated baghouse controls and actual

emissions that are listed in more rece nt kiln (P007) APEN reports.

The EPA BART guidelines suggest that “the baseline emissions rate should represent a realistic depiction of anticipated annual emissions for the source.” See [70 FR 39167]. There is some variation in the short

- term and long

- te rm SO2 emissions depending on the raw material mix, type of clinker produced, and fuel used. Thus, historically there was some flexibility provided in developing the original permit limits to allow of the use of alternative fuels and raw materials, as

wel l as longer averaging periods. The 10

- year period ( 2000

- 200 9 ) may represent a different kiln operation condition when compared to earlier periods because no petroleum coke was burned inColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 4 the kiln despite being permitted to burn such fuel. The Division det ermined that looking back at kiln operations prior to the year 2000 were not reasonable for purposes of BART. Consequently,

the selection of 2002 as the kiln emissions baseline essentially precludes the use of petroleum

coke since the use of such fuel wou ld result in SO2 emissions far above 95 tons per year.

The justification for selecting the highest SO2 emission rate over a baseline period is associated with the fact that cement kiln SO2 emissions are not as predictable as a coal

- fired boiler (power plan t). The sulfur in the coal is sole source of SO2 at a power plant, whereas a cement kiln has two sources, the coal fuel and the sulfide impurities (iron pyrite) in the limestone and other raw materials added to the kiln. Consequently, it is much easier, although still a challenge, to maintain compliance with SO2 limits at coal

- fired power plants through careful blending of various coals, or purchasing complian t coal to achieve more consistent sulfur content. Conversely, coal blending for cement kilns onl y addresses one source of SO2, the other source (the raw materials) varies depending on impurities in the mining deposit and other additives used in clinker production.

Table 2: Kiln Emissions

Kiln SCC

– 30500606

(120 tons/hour maximum feed rate

– 967,680 tons/year dry basis)

Pollutant SO2 NOx PM10 CO

Allowable Emissions [tpy] 1,340.0 2,649.0 133.0 396.0

200 0 APEN Emissions [tpy] 14.4 1,729.6

2001 APEN Emissions [tpy] 18.7 1,858.9 8.7 233.2

2002 APEN Emissions [tpy] 95.0 1,747.1 8.5 235.3

2003 APEN Emissions [tpy] 48.0 1,835.0 9.6 210.0

2004 APEN Emissions [tpy] 26.3 1,708.9 9.1 209.0

2005 APEN Emissions [tpy] 27.2 1,591.3 8.5 156.0

2006 APEN Emissions [tpy] 44.7 2,011.7 8.5 239.2

2007 APEN Emissions [tpy] 65.0 1,689.0 56.0 311.0

2008 APEN Emissions [tpy] 55.8 1,295.5 42.0 345.1

2009 APEN Emissions [tpy] 15.5 495.5 17.5 102.4

Baseline [tpy] 95.0 1,747.1 8.5 235.3

% Baseline is b elow Allowable Emissions - 92.9%

- 34.0%

- 93.6%

- 40.6%

Baseline Emissions [lbs/ton of Clinker] 0.402 7.388 0.036 0.995

The average clinker production over the period (200 0

– 2008) is 486

, 031 tons. The year 2009 was excluded from the average as clinker production was well below the average production

level.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 5 Table 3: Kiln

- Flash Calciner

– Historical Emissions

Year Actual Clinker

Production [tpy] SO2 [tpy] SO2 [lbs/ton of Clinker] NOx [tpy] NOx [lbs/ton of Clinker]

2000 539, 992 14.4 0.053 1,729.6 6.42

2001 508,733 18.7 0.074 1, 858.9 7.31

2002 472,945 95.0 0.402 1,747 .1 7.39

2003 516,251 48 .0 0.186 1,835 .0 7 .11

2004 472,053 26.3 0.111 1,708.9 7.24

2005 440,384 27.2 0.123 1,591 .3 7.23

2006 466,173 44.7 0.192 2,01 1.7 8.63

2007 479,225 65.0 0.271 1,689 .0 7.05

200 8 478,520 55.8 0.233 1,29 5.5 5.41

2009 185,076 15.5 0.167 49 5.5 5.35

III

. BART Evaluation

Ther e are two BART eligible units at the Cemex facility, the dryer and the kiln. The dryer is natural gas

- fired with actual emissions of NOx = 10.41 tpy; SO2= 0.89 tpy ; and PM10 = 5.12 tpy; based on a recent stack test

. CALPUFF modeling 1 , of the dryer and ki ln combined indicates

a 98 th percentile visibility impact (at Rocky Mountain National Park) of 0.78 delta deciview 2
(Δdv) and 98 th percentile visibility impact at of only the kiln is 0.76 Δdv 3 . Thus, the visibility impact of the dryer alone is the resulta nt difference which is 0.02 Δdv

. Because the dryer uses the cleanest fossil fuel available and post combustion controls on such extremely low concentrations are not practical, the Division has determined that no meaningful emission reductions (and thus no meaningful visibility improvements) would occur pursuant to any conceivable controls on the dryer. Accordingly, the Division has determined that no additional emission control analysis of the dryer is necessary or appropriate since the total elimination of the emissions would not result in any measurable visibility improvement which is a fundamental factor in the BART evaluation. Consequently, the current SO2, NOx and PM10 emission limits (see Table 1

– Dryer Allowable Emissions) established in the Cemex

– Lyons Operating Permit (95OPBO082) have been determined to satisfy the requirements for BART.

III. A. Review of Sulfur Dioxide Controls on the Kiln

Step 1: Identify All Available Technologies

Cemex originally identified four available technologies for the removal of sulfur dioxide from Portland cement kilns. A copy of Cemex’s BART analysis is included with this analysis as an attachment, and provides further support and documentation for the conclusions reached herein. The Division added Dry Sorbent Inje ction (DSI) as another option that is available for control of

1 Cemex Inc., Lyons Colo rado

- BART Five Factor Analysis; dated August 29, 2008

2 Table 3

- 6 of the Cemex BART Five Factor Analysis

3 Table 4

- 7 of the Cemex BART Five Factor AnalysisColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 6 SO2 emissions. The Division also reviewed the RACT/ BACT / LAER clearinghouse and other BART analyses develop the following list of available technologies :

1. Fuel Substitution

2. Raw Material S ubstitution

3. Lime Addition to Kiln Feed

4. Dry Sorbent Injection

5

. Wet Lime Scrubbing

Step 2: Eliminate Technically Infeasible Options

Cemex concluded that fuel substitution and raw material substitution are not technically feasible at the plant. Beca use of the physical, chemical and engineering principles involved in manufacturing Portland cement, technical difficulties would arguably preclude the successful use of these control options at the plant. Nonetheless, the Division has determined that each of the foregoing technologies is “technically feasible” for the facility, as that term is discussed in

EPA ’s BART guidelines.

Step 3: Evaluate Control Effectiveness of Each Remaining Control Technology

Step 4: Evaluate Impacts and Document Results

1. Fuel Substitution:

Cemex is authorized to burn coal, coke and tire derived fuel (TDF) at the facility , although coal

is the primary fuel. The c oal used in the kiln typically has a sulfur content of less than 1. 5%,

whereas the sulfur content of coke can be as high as 6% sulfur. Removal of SO2 is inherent to the cement manufacturing process as the hot combustion gases come in contact with the limestone generating free lime, which then reacts with the SO2 in the free gas stream resulting in

removal of sulfur in the clinker product . Removal efficiencies in rotary kiln systems can range between 38% and 99% of sulfur input. Cemex estimates the SO2 removal efficiency of about

80%. Based on the low level of SO2 emissions (based on CEMS) emitted from the k iln, it is apparent that a high level of SO2 control is achieved through the inherent removal process within

the kiln . Since inherent removal accounts for a t least 80% reduction in kiln SO2 emissions , any further lowering of the sulfur content of the fuel results i n about a 20% reduction in directly

emitted SO2.

In November 2002, a preliminary performa n ce (stack) test was conducted on the kiln that compared fossil fuel (coal & natural gas) with coal supplemented with TDF (coal & tires) which

indicated about a 40% re duction in SOx in the exhaust stream. The stack tests show that TDF can be burned without exceeding applicable emission limits for either criteria pollutants or hazardous air pollutants. Both the Division and Cemex continue to believe that firing TDF is a viable emission control strategy under appropriate conditions along with consideration of the stack tests results and the fact that TDF is widely used as an alternative fuel. Nevertheless, some in the Lyons community have expressed reservations about th e tire burning, and requested a moratorium on using TDF. In response to concerns, and in consideration of a Division issued Compliance Order on Consent (Case No. 2005

- 049), Cemex agreed not to use TDF as an alternative fuel in the kiln for a period that e xpired on December 31, 2007. Presently, Cemex may commence using TDF as permitted in accordance with the terms and conditions of Permit No. 95OPBO082, unless TDF is prohibited by another legally enforceable requirement.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 7 Cost of Compliance:
Cemex provide d limited TDF cost information because of ongoing community concerns associated with burning tires. The annualized costs are about $172,179 per year; however the costs of acquiring TDF and the transportation costs were not included. Assuming the above

an nual cost and the estimated 40% SO2 reduction, the control cost is estimated at about $4,531 per ton of SO2 reduced.

Energy Impacts and Non Air

- Quality Impacts : There is community concern associated with fuel switching to TDF.

Existing Controls in Use at S ource :

The source uses low sulfur coal and i nherent removal of SO2 emissions through contact with the

clinker results in about 80% control.

Remaining Useful Life:

No impact

2. Raw Material Substitution:

Sulfide sulfur in the raw materials (primarily limest one) , usually in the form of iron pyrite, is thermally decomposed and oxidized or “roasted” to form SO2. The pyritic sulfur reacts with oxygen according to the following reaction:

4FeS2 + 11O2 2Fe2O3 + 8SO2
Using raw materials with lower pyritic sulfur co ntent would reduce the potential for SO2

emissions from the k iln system. However, while pyrites are present in the limestone and other raw materials used at the plant, concentrations of sulfide sulfur in these materials is typically

low. On average, the sulfide content of the raw materials is less than 2%. It is uncertain that lower sulfur content materials are available. Since the raw materials and fuel used at the plant already have very low sulfide sulfur, raw material substitution is not likely to p roduce significant

sulfur reductions.

Similar to most cement plants, the Cemex facility is built near the mine source of limestone, the primary raw material for cement manufacture. To require transport of materials with lower

sulfide concentrations from e lsewhere would impose an economic penalty that would cause most plants to be economically infeasible. During the production of cement clinker, the limestone

loses about one

- third of its weight as CO2. The shipping costs for the “lost” weight in the

limes tone can be economically prohibitive.

The Division has determined that raw material substitution with a different source of limestone is not a practical control option as SO2 emissions vary depending on the level of pyrite contamination which is inherently diff icult to predict. Consequently, raw material substitution

has been eliminated from further review and consideration.

3. Lime Addition to Kiln Feed:

Lime Addition to Kiln Feed at the Lyons plant would consist of mixing lime (CaO) with the raw

Kiln fee d. The CaO would re act with SO2 driven off in the k iln to form calcium sulfite (CaSO3) and calcium sulfate (CaSO4) according to the following reactions:

CaO + SO2 CaSO3Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 8 CaSO3 + 1⁄2 O2 CaSO4
These reactions can occur in the calciner, throughout the rotary k iln, and in the lower stages of the flash calciner (i.e., at any location in the system at which CaO and SO2 are present simultaneously and are mixed adequately). The amount of SO2 absorbed through this mechanism at any location in the pyroprocess is dependent on the site

- specific temperature and

other factors such as the time of contact between the reactants. Once sulfur is absorbed as

CaSO4 in the materials in the pyroprocess, it is unlikely to be released again as SO2. CaSO4 would be retained in the raw mix and ultimately be converted into clinker. Cemex anticipates

that Lime Addition to Kiln Feed could achieve 25 % control of the SO2 emitted from the system. Considering the length of the kiln and the corresponding amount of contact time, it appears that

25 % control of SO2 is possible depending on the amount of lime that is fed into the kiln.

Cost of Compliance:

The cost of Lime Addition to K iln Feed was determ ined by calculating the cost of the CaO needed to react with the SO2 in the system. In an exhaust gas stream, the molar ratio of CaO

needed to react with a mole of SO2 ( to achieve a near 90% reaction ) is o n the order of 1:1.

However in the situation of Ce mex

– Lyons, adding the CaO directly to the feed would result in

a diminished effectiveness because of the lower SO2 concentrations. Cemex has indicated that, based on data from Cemex’s Wampum, PA plant, an addition of 2

- 3 ton/hr of CaO to a similar

Kiln feed stream resulted in approximately a 25% reduction in the SO2 concentration (from 600 ppm down to 450 ppm). The concentration of SO2 in the gas stream at the Lyons plant is significantly lower (a typical 24

- hr average is in the 6 ppm range) and it is u nknown how much

more CaO is needed to achieve the desired reduction. Since the typical emission range at

Cemex

- Lyons is 100 times lower than the tested levels at Cemex

- Wampum, it is expected that more CaO would be needed to achieve adequate contact time w ith the lower concentrations of

s ulfur in the exhaust stream. Moreover, the effectiveness of CaO addition i s further limited by the alkali byproducts associated with the use of more CaO. C onsequently, Cemex has conservatively estimated that it could take about 4 tons per hour of CaO addition to achieve a

25% SO2 reduction

.
Cemex

– Lyons kiln is limited to 8,064 hours per year of operation based on a permit limit in the Operating Permit (95OPBO082)

, thus the resulting annual CaO usage is 32,256 tons (4*806 4)

. Cemex’s 2007 BART application identified the CaO cost at $60/ton, but this was for raw CaO ( un

- calcined ) which has different properties. The appropriate material is the use of calcined CaO ( lime or quick lime) which cost about $143/ton. Therefore, t he annual operating cost would be 32,256 tons x $ 143 /ton = $ 4

, 612

, 608 . The lime (CaO) addition would yield approximately 90% conversion to clinker, or 29,030 tpy of clinker, which has a value of $1,161,216 @ $40/ton. Therefore, the actual operating cost would be approximately $ 4,612,608

- $1,161,216 = $ 3,451,392 . At 2 5 % control effectiveness, the annual SO2 emissions would be lowered from the proposed permit limit of 95.0 tpy to 71.25 tons/year. The cost effectiveness would be approximately $ 153,271 per ton of SO2 removed.

Energy Impacts and Non Air

- Quality Impacts : Alkali impurities in the CaO could result in additional wasting of kiln dust to meet low alkali

limits

. Additional fugitive PM10 emission may result from handling of the CaO.

Existing Contro ls in Use at Source :Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 9 The source uses low sulfur coal and inherent removal of SO2 emissions through contact with the
clinker results in about 80% control.

Remaining Useful Life:
The remaining useful life of the kiln does not impact the annualized costs for lime addition to

kiln feed.

4. Dry Sorbent Injection:

Dry Sorbent Injection (DSI) utilizes finely ground sorbent which is injected in the gas stream of the kiln. The sorbent typically used is a hydrated lime, sodium bicarbonate or Trona (soda ash).

Water may be injected separately from the sorbent either downstream or upstream of the dry sorbent injection point to humidify the flue gas. The relative position of the dry sorbent and water injection is optimized to maximally promote droplet scavenging or im pacts between sorbent particles and water droplets, both suspended in gas stream. Fly ash, reaction products, and any unreacted sorbent are collected in the particulate control device.

Cost of Compliance:

Cem ex did not provide any DSI costs specific to th e Lyons kiln

.

Energy Impacts and Non Air

- Quality Impacts : There are no energy or non

- air quality impacts associated with dry sorbent injection.

Existing Controls in Use at Source : The source uses low sulfur coal and inherent removal of SO2 emissions throug h contact with the

clinker which results in about 80% control.

Remaining Useful Life:
The remaining useful life of the kiln does not impact the annualized costs for dry sorbent injection.

5

. Wet Lime Scrubbing:
Wet lime scrubbing (WLS) is the term used for a traditional tailpipe wet scrubber. This process involves passing the flue gas from the main PMCD through a sprayed aqueous suspension of Ca(OH)2 or CaCO3 (limestone) that is contained in an appropriate scrubbing device. In WLS

the SO2 reacts with the scrubbing reagent to form CaSO3 that is collected and retained as aqueous sludge. Typically, the sludge is dewatered and disposed in an on

- site landfill. In some cases involving cement plants, the CaSO3 sludge could be oxidized to CaSO4 and used in the

fi nish mills as a substitute for purchased gypsum for regulation of the setting time of the cement product. Typically, WLS is considered to have a scrubbing efficiency of up to 90 percent of the SO2 in the flue gas treated by the scrubber. See Cemex BART s ubmittal at 4

- 4, citing “EPA

Fact Sheet

– Flue Gas Desulfurization (FGD) Wet, Spray Dry, and Dry Scrubbers.”

Cost of Compliance:
Cemex performed an economic analysis to determine the annualized cost for WLS based on a recent vendor bid for a cement plant w ith a similar exhaust flow rate. The “annual tons reduced” were determined by subtracting the estimated controlled annual emissions from the Division proposed annual permit limit of 95 tpy SO2. The estimated controlled annual emissions, 9.5 tpy,Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 10 were cal culated by applying 90 percent control efficiency to the 95 tpy of SO2. Utilizing this methodology and correcting a math error on the amount of sludge generated, the estimated

annualized cost 4 is $ 2

, 529

, 018 for WLS, the projected SO2 control cost per ton is $ 29,579 /ton. A detailed cost analysis is included in Table 4

- 5 of Cemex’s BART submittal, which was corrected by the Division to account for the longer amortization period

.

Energy and Non Air

- Quality Impacts: Wet Lime Scrubbing (WLS)

Based upon its ex perience, the Division has determined that wet scrubbing has several negative energy and non air quality environmental impacts, including significant water usage which is a precious commodity in the arid West. Cemex estimates that an appropriately sized w et scrubber would consume approximately 16 million gallons of water per year. Most of this water would be

emitted as a steam vapor with a small portion in the sludge that would be generated by the control device. A wet scrubber would also require an addi tional fan of considerable horsepower to move the flue gas through the scrubber.
Wet scrubbing may also lead to an increase in PM emissions at the Cemex facility, because some particles of limestone or CaSO4 will be entrained in the flue gas and subsequent ly be emitted

from the scrubber. Wet scrubbing is also known to increase e missions of sulfuric acid mist.

Existing Controls in Use at Source : The source uses low sulfur coal and inherent removal of SO2 emissions through contact with the

clinker results in about 80% control.

Remaining Useful Life:

Th e remaining useful life of the k iln is impacted by the remaining life of the quarry, which Cemex has estimated to be approximately 8 years from the date that a BART control would be required based on the expirat ion of Boulder County SUP 93

- 14 for quarry operations

. The continued viability of the cement production operation relies on finding additional limestone feedstock of very similar composition within a distance that allows for economic operation. The

Divis ion is not aware that Cemex has successfully secured additional limestone supplies that would provide additional useful life to the facility. Presently, Cemex is unwilling to consent to closure date in the operating permit therefore the Division has used 20 years as t he capital recovery period.

4 Capital Recovery based on an assumed 20 year life and 7% interest rateColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 11 Table 4 below lists the most feasible and effective options, ranked by control effectiveness.

Table 4 : Kiln SO2 Control O ptions

Control Technology Estimated

Control Efficiency Annual

Controlled Hourly SO2

Emissions [lbs/hr] Annual

Controlled

SO2

Emissions [tpy] Annual

Controlled SO2

Emissions [lb/ton of Clinker]

Baseline SO2 Emissions 25.3 95.0 0.40

Lime Addition to Kiln Feed 25% 1 9.0 71.3 0.3 0

Fuel Substitution (coal supplemented with TDF) 40% 15.2 57.0 0.24

D ry Sorbent Injection 50% 12. 7 47.5 0.20

Wet Lime Scrubbing (Tailpipe scrubber) 90% 2.5 9.5 0.04

Table 5 below lists the SO2 emission reduction, annualized costs and the control cost effectiveness for the feasible controls, ranked by control effectiveness

.

T able 5 : S ummary of Cost Effectiveness of SO2 Control Technologies for the Kiln

Control Technology SO2 Emission

Reduction Annualized

Cost Cost

Effectiveness Incremental Cost

Effectiveness

[tons/yr] [$/yr] [$/ton] [$/ton]

Baseline SO2 Emissions

-

L ime Addition to Kiln Feed 23.8 $3,640,178 $153,271

Fuel Substitution (coal supplemented with TDF) 38.0 $172,179 $4,531

- $24 3

, 368

Dry Sorbent Injection 47.5 Not provided -
Wet Lime Scrubbing (Tailpipe scrubber) 85.5 $ 2,529,018 $ 29

, 579 $ 49,618

Step 5: Evaluate Visibility Results

CALPUFF modeling was used to determine the projected visibility improvement associated with various control scenarios. Cemex also conducted refined CALMET modeling which indicates that Rocky Mountain National Park is the only Class I Area where the Lyons plant causes or contributes to visibility impairment. Cemex’s refined modeling is dis c us s ed in detail in the

attached Cemex BART 5

- Factor Analysis which was reviewed by the Division and found to meet all required performance r equirements.

The amount of visibility improvement associated with various SO2 control scenarios using

C ALPUFF modeling are listed in Table 6

.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 12 Table 6 : Visibility improvement for SO2 Controls

– Kiln Only

Control Method 98 th

Percentile Impact 98 th Percenti le

Improvement (f rom 24

- hr Max ) Cost

Effectiveness

( Δ dv) ( Δ dv) ($/ Δ dv)

24

- hr M ax imum (≈ 104 lbs/hr ) 0.76 0

- Baseline ( ≈ 25.3 lbs/hr ) * 0.73 0 0.030

Lime Addition to Kiln ( ≈ 19 .0 lbs/hr )* 0.72 7 0.0 33 $ 110

, 308

, 420

Fuel Substitution ( ≈ 15.2 lbs/hr )* 0.72 6 0.03 4 $5,064,088

Dry Sorbent Injection ( ≈ 12.7 lb s/hr )* 0.724 0.036

Wet Lime Scrubbing ( ≈ 2.5 lbs/hr ) 0.720 0.040 $ 63,225,462

*

- Visibility impacts interpolated from original BART modeling

The SO2 baseline of 95 tons/year is based on 2002 APEN report which results in a 0.03 Δ dv of visibility improvem ent over the 24

- hour maximum emission rate of 104 lb/hour (419 tons/year). The SO2 reduction from lime addition to kiln feed is estimated at 25% and the anticipated degree visibility improvement (from 24

- hr Maximum) is about 0.033 Δ dv at a cost of $110.3 million dollars per Δ dv . The control efficiency of fuel substitution could be as high as 40% (about 38 tons/year) based on very limited testing and the anticipated degree of visibility improvement (from 24

- hr Maximum) is about 0.034 Δ dv at a cost of $5 mi llion dollars per Δ dv . Dry sorbent injection has a visibility improvement of 0.036 Δ dv , based on an estimated 47.5 tpy reduction in SO2 emissions. Wet lime scrubbing reduces SO2 emissions by about 85.5 tpy with 0.04 Δ dv visibility improvement at a cost o f $ 6 3 million dollars per Δ dv. The visibility projections for the below listed emission levels are based on scaling the existing BART modeling.

Step 6: Select BART Control

The Division reviewed the Cemex data on raw material substitution. Since the raw materials (mostly limestone) consumed at the plant typically have low sulfide sulfur content, material

substitution would not result in a significant reduction in SO2 in t he Kiln. The Division agrees that raw material substitution is not an appropriate or realistic SO2 control technology for the

Kiln.

The Division has eliminated the Lime Addition to Kiln Feed SO2 control option from consideration based on excessive cost ($ 153,271 per ton) and minimal visibility improvement ( 0.033 Δdv ). Despite not having cost information on Dry Sorbent Injection, the Division has determined that the minimal visibility improvement of 0.036 Δdv does not justify further consideration of this control technology.

The Division has eliminated the Wet Lim e Scrubbing SO2 control option from consideration based on excessive cost ($ 29,579 per ton) and minimal visibility improvement ( 0.04 Δdv improvement). Moreover, wet scrubbing has a number of adverse energy and environmental impacts as described above.

The Division has considered the five factors and has thoroughly reviewed the data supplied by

Cemex to determine that process control (inherent removal in the kiln) from the 2002 baseline period represents Best Available Retrofit Technology for control of SO2 emissions in the kiln. Table 7 specifies the Division SO2 BART determination of 25.3 pounds per hour and 95.0 tonsColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 13 per year that are 12

- month rolling averages. The Division considered establishing an SO2 emissions limit based on clinker production, howe ver, the Cemex

- Lyons facility does not have the capability to weigh clinker product upon exiting the kiln. Consequently, compliance with the SO2 BART limits will be determined by a continuous emissions monitor system (CEMS).

Table 7: SO2 Emission Limits on the Kiln Subject Unit SO2 Control Technology SO2 Emission Limits

Kiln System Inherent Removal 25.3 lbs/hr (12

- month rolling average) 95.0 tons/yr (12

- month rolling average )

The federal BART rule requires that emission limits must be enforceable an d specify a reasonable averaging time consistent with established reference methods. The Division finds

that in consideration of the potential for variability in SO2 emissions associated with pyrites i n the limestone and other raw materials used at the pl ant , an annual averaging period provides long

- term compliance with the low levels of SO2 emitted from the kiln while allowing for short

term variability in SO2 emissions. Shorter term averaging periods are not practical as the sources of the sulfur impuri ties are not readily detectable in the quarry materials. The type of cement produced also potentially impacts the variability of SO2 emissions in the kiln feed mix which necessitates longer averaging periods.

In consideration of establishing the SO2 emiss ion limit, the Division reviewed not only the 5 factor analysis, but also looked at emission limits from the RACT/BACT/LAER clearinghouse to

determine SO2 emission limits for other cement kilns across the nation

. The Division was unable to find an operati onally similar kiln to the Cemex

- Lyons kiln, but the SO2 emission limits for newer higher efficiency kilns do establish a reasonable range to consider. Table 8 identifies SO2 limits ranging from 0.2 to 12.0 lb per ton of clinker. In comparing the Divis ion proposed SO2 BART limit (approximately equal t o 0.40 lb per ton of clinker ) to the values approved for new Portland cement kilns in the RACT / BACT / LAER clearinghouse, it is well

below the higher limits established in Missouri, and is slightly higher tha n those established in

Florida.

Table 8: RACT/BACT/LAER data for Cement Kilns

RBLC ID SO2 Control SO2 Limit Units Year

FL 0297 Process 0.2 lb/ton clinker 2007

MO

- 0072 Process 1.93 lb/ton clinker 2006

FL

- 0271 Process 0.2 lb/ton clinker 2006

FL

- 0268 Pro cess 0.23 lb/ton clinker 2004

FL

- 0267 Process 0.28 lb/ton clinker 2004

SD

- 003 Process 632 ton/hr 2003

MO

- 0059 Wet Scrubber 12 lb/ton clinker 2002

IA

- 0052 Process 4850 ton/year 2002

TX

- 0355 Process 20 lb/hr 2001

FL

- 0139 Process 0.27 lb/ton clinker 200 0Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 14 The Division also evaluated a recent local BACT determination (2007) on Grupo Cementos de Chihuahua (GCC) Rio Grande Pueblo Portland cement plant that establishes a SO2 emission limit of 1.99 lb/ton of clinker. In considering the RBL clearinghouse ran ges and a recent Colorado BACT determination, the Division finds that the proposed SO2 BART limits (approximately equal to 0.40 lb/ton of clinker ) to be a reasonable limit for such a relatively small

SO2 emission source.

Accordingly, based upon its conside ration and weighing of the five factors, the Division has determined that the use of low sulfur coal and the inherent control resulting from the Portland cement process provides sufficient basis to establish a nnual SO2 emission limit s of 25.3 lbs/hour

and 95.0 tpy (approximately equal to 0.40 lb per ton of clinker ) as SO2 BART for the kiln at this facility. No additional controls are warranted because about 80% of the sulfur is captured in the clinker, making the inherent control of the process the SO2 con trol. Additional SO2 scrubbing is also provided by the limestone coating in the baghouse as the exhaust gas passes through the baghouse filter surface.

III.B. Review of Nitrogen Oxide Controls on the Kiln

As explained above

, in S ection III, no evaluation of the dryer is warranted because of extremely

low emissions. Based on actual 2008 data, the NOx emissions from the kiln are 1295.5 tpy and the raw material dryer are 10.41 tpy. Since the average emissions from the dryer (about 2.8 pounds per hour) are v ery small compared to the kiln (about 343.9 pounds per hour); the following BART evaluation focuses only on the kiln.

Step 1: Identify All Available Technologies

The primary pollutant of concern for regional haze from the Lyons plant is the NOx generated from the kiln system. Cemex’s current allowable NOx emission rate is 2

, 649 tpy NOx, which equates to an average allowable emission rate of 667 pounds NOx per hour based on the permit

limit of 8064 hours of operation per year. Using 2002 as the baseline, the annual average NOx emission rate is 464.3 lbs/hr (1,747.1 tpy) or about 4.73 lbs/ton of dry kiln feed

. Variations in kiln NOx emissions occur with the composition of the raw materials used to produce different types of cement, which depends on market d emand. Also, changes in the raw materials ( natural rock composition ) and seasonal temperature variations occur, as indicated in

the following excerpt from a study 5

, “The results of these changes range from zero emissions of NOx during a complete outage of the system to significantly higher than normal NOx emissions when the fuel input is increased to restore the process equilibrium and a normal production rate.

More su btle changes in the process, e.g. variations in ambient temperature (short

- term and

seas onal), variations in the feed rates or fuel or raw materials, demand operator responses that also serve to vary NOx emissions. For a variety of factors, the operation of some pre

- calciner kiln systems is more stable than others. Almost invariability, how ever, pre

- calciner kiln systems exhibit more stable operation than the three other t ypes of kiln systems, and experience the least variability in NOx emissions.” The Cemex

- Lyons kiln is a modified long dry kiln, thus some consideration of a longer avera ging period is appropriate to account for variation in NOx emissions depending on cement product produced and variations in raw materials.

5 See “Variability of NOx Emissions from Precalciner Cement Kiln Systems”, Walter L. Greer, Curtis D. LesslieColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 15 Cemex identified six available technologies for the removal of NOx from Portland cement kilns.

The Division reviewed the RACT /BACT/ LAER Clearinghouse and other BART analyses and agrees with CEMEX’s identification of available technologies. The available technologies are the following:

1. Water Injection

2. CKD Insufflation

3. Firing Tire

- Derived Fuel

4. Indirect Firin g with Low NOx Burners (LNB)

5. Selective Non Catalytic Reduction (SNCR)

6. LNB with SNCR

7

. Selective Catalytic Reduction (SCR)

Step 2: Eliminate Technically Infeasible Options

Cemex has concluded that water injection and kiln dust insufflation are not te chnically feasible at the plant. Because of the physical, chemical and engineering principles involved in manufacturing Portland cement, technical difficulties would arguably preclude the successful use of these control options at the plant. Nonetheless, the Division has determined that these technologies are “technically feasible” for the facility, as that term is discussed in EPA’s BART guidelines. As further discussed below, however, the Division has also determined that water injection and kiln dust insufflation are not appropriate NOx controls for purposes of BART at the facility.

7

. Selective Catalytic Reduction (SCR):
Selective catalytic reduction (SCR) refers to the reduction of NOx in the presence of ammonia to water and elemental nitrogen in the presence of a catalyst. The term “selective” refers to the unique ability of ammonia to react selectively with NOx. The EPA released a NOx control technology update for new cement kilns entitled “ Alternative Control Techniques Document Update

– NOx Emis sions from New Cement Kilns,” EPA

- 453/R

- 07

- 006, November 2007 that discusses SCR control for cement kilns. The following discussion is excerpted from the EPA
report:

SCR is the process of adding ammonia or urea in the presence of a catalyst to selective ly

reduce NO x emissions from exhaust gases. The SCR process has been used extensively on gas turbines, internal combustion (IC) engines, and fossil fuel

- fired utility boilers. In the SCR system, anhydrous ammonia, usually diluted with air or steam or aqu eous ammonia solution, is injected through a catalyst bed to reduce NO x emissions. A number of catalyst materials have been used, such as titanium dioxide, vanadium pentoxide, and zeolite

- based materials. The catalyst is typically supported on ceramic ma terials (e.g., alumina in a honeycomb monolith form) and promotes the NO x reduction reactions by providing a site for these reactions to occur. The catalyst is not consumed in the process, but allows the reactions to occur at a lower temperature. The opt imum temperature for the catalyst reactions depends on the specific catalyst used. Several different catalysts are available for use at different exhaust gas temperatures. Base metal catalysts are useful between 450 °F and 800 °F (232 °C and 427 °C). Fo r high temperature operations (675 °F [357 °C] to over 1100 °F [593 °C] ), zeolite catalysts containing precious metals such as platinum and palladium are useful. The two principal reactions in the SCR process at cement plants using SCR are the following:Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 16 4 NH3+ 4 NO + O2 4 N2 + 6 H2O

and

4 NH3 + 2 NO2 + O2 3 N2 + 6 H2O

The first equation is the predominant reaction because 90

- 95% of NO x in flue gas is NO. It is important to note that the desired chemical reactions are identical with SNCR and SCR. The only difference is that a catalyst is present with SCR, which allows the reactions to occur at a lower temperature. In an SCR system, ammonia is typically injected to produce a NH 3 : NO x molar ratio of 1.05

– 1.1:1 to achieve a NO x conversion of 80

– 90% w ith an ammonia slip of about 10 ppm of unreacted ammonia in gases leaving the reactor. The NO x removal efficiency depends on the flue gas temperature, the molar ratio of ammonia to NO x , and the flue gas residence time in the catalyst bed. All these facto rs must be considered in designing the

desired NO x reduction, the appropriate reagent ratios, the catalyst bed volume, and the operating conditions. As with SNCR, the appropriate temperature window must be maintained to assure that ammonia slip does not re sult in a visible plume. SCR can be installed at a cement kiln at two possible locations:

After the PM control device

– a “low

- dust” system After the last cyclone without ducting

– a “high

- dust” system.

The advantages of a “low

- dust” system are longer cat alyst life and lower danger of blockage. The disadvantage is the additional energy costs required to heat the cooled exhaust to achieve proper reaction temperatures in the catalyst. On a worldwide basis, three cement kilns have used SCR: Solnhofen Zement werkes in Germany and Cementeria di Monselice and Italcementi Sarche di Calavino in Italy. The SCR system was operated at the Solnhofen plant from 2001 to January 2006, at which time the plant began using SNCR to compare the operational costs of

the two s ystems to evaluate which technology is better and more economical. Both Solnhofen and Cementeria di Monselice have preheater kilns. The Italcementi plant operates a small Polysius Lepol technology kiln, which is a traveling grate preheater kiln. Both pl ants use a 25% aqueous ammonia solution, have 6 catalyst layers but only use 3 layers. Both plants have similar designs and facilities that are similar in size and raw materials. At Solnhofen, 200 mg/m 3 (~ 0.8 lb/t) of NO x is typically achieved from an i nlet of 1,050 mg/Nm 3 (4.2 lb/t) or 80% control. Also, ammonia slip was less than 1 mg/m 3 . Greater than 80% control is frequently achieved. At the end of 2003, the catalyst had logged 20,000

– 25,000 hours with no discernable problems. The catalyst was gua ranteed for 16,000 hrs, with an expected catalyst life of 3

– 4 yrs.

The SCR system at Cementeria di Monselice in Bergamo, Italy began operation in June 2006. Catalyst activity remains high after 3,500 hours of operation. Following startup in June 2006,

co ntinuous testing was conducted for six weeks.

The design of a SCR system is expected to be site specific. According to Schreiber 6

, the technology transfer of SCR systems from the power plant industry to the Portland cement industry requires substantial re search and pilot testing before the technology could be considered commercially available. Figure 1 , from Granger 7 shows the performance of a typical catalyst under different conditions of temperature and gas composition. The highest NOx reduction

6 See Schreiber, R, et al “Evaluation of Suitability of Selective Catalytic Reduction and Selective Non

- Catalytic Reduction for use in Portland Cement Industry”, (2006)

7 See Granger, P. Elsevier, “Past and Present in DeNOx Catalysis: From Molecular Modeling to Chemical Engineering”, (2007)Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 17 effici encies for this particular catalyst (vanadium pentoxide with titanium dioxide substrate)

were achieved at a temperature range of 350 o C to 4 5 0 o C. At a particular temperature, as denoted by the sweeping arcs, small incremental increases in ammonia result in an increase in the NOx

reduction until the optimal rate is achieved beyond which a rapid increase in ammonia slip

results . This also provides evidence of the narrow temperature window for effective SCR performance.

Figure 1: Catalyst Performance for NOx Control and Ammonia slip at Various Temperatures

Additionally, multiple challenges exist to achieve SCR effectiveness: selection of catalyst type, positioning of the catalyst, management of catalyst life, catalyst poisoning an d ammonia slip.

E ach challenge presents additional confounding issues related to the application at the Cemex

– Lyons facility due to the unique design of the modified long dry kiln. A good catalyst must ensure high activity and selectivity for NOx reduc tion and low activity in the oxidation of SO2 to SO4. Because of the high selectivity, the catalyst will have a specific temperature window at which the NOx reduction is optimal (Granger 2007). Specific to the Cemex

– Lyons kiln, the exit temperature, af

ter the baghouse, will require reheating of the exhaust gases to reach the optimal temperature for effective NOx control. If post NOx control cooling is required, additional water usage would be necessary along with the challenges of the resultant high

mo isture (20

- 25%) exhaust gas stream.

There is limited information regarding the geometry and optimal positioning of the catalyst to allow for effective NOx reduction and low pressure loss. Further, engineering analysis on overall efficiency during the cata lyst life

- cycle would be required t o ascertain effectiveness. According to Benson 8 , alkali and alkaline

- earth rich oxides (sodium, magnesium, calcium and potassium) have strong influence on catalyst deactivation ( See also Nicosia et al.

, 2008, and Strege et al., 2008). Figure 2 shows evidence of catalyst poisoning by both sulfur and alkalies 9

.

8 See Benson, S. et al. “SCR catalyst performance in flue gases derived from subbituminous and lignite coals, Fuel Processing Technolog y, Vol. 86” (2005)

9 See Strege, J. et al., “SCR deactivation in a full

- scale cofired utility boiler, Fuel 87” (2008)Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 18 The contaminants occupy active sites that otherwise would be available for ammonia storage thus reducing the reactivity and selectivity of the catalyst resulting i n lower NOx control

effectiveness. Also , particulates from the calcining process would likely combine with available ammonia to form a sticky dust that may adhere to the active sites on the catalyst thereby further reducing the effectiveness of the NOx re duction. Particulate scouring of the catalyst surface has been identified as another mechanism that reduces the effectiveness of the catalyst. The exit gas

of the Cemex

– Lyons kiln presents additional specific issues including moisture in the exhaust

st ream and alkali dust. The combination of both could result in rapid loss of catalyst activity depending on the type of catalyst materials used.

Figure 2: Sulfur and Alkali Penetration into the pores of the catalyst

The above figure indicates that sulfu r and alkali compounds penetrate into the catalyst surface resulting in a reduction in the number of active sites thereby reducing the activity and selectivity

toward NOx reduction (see Strege et al. , 2008)

.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 19 Figure 3: Bench Scale Test Results of Catalyst Deactivation over a Period of Time

The above figure provides evidence of catalyst deactivation. If the catalyst life is assumed to end when activity coefficient is around 0.6, then the catalyst life is about 130 days or 3,100 hours,

which is much lower than the 23,000 hour catalyst life cited in the report on the Solnhofen Zementwerkes in Germany

. Ammonia slip is also an issue of concern as it readily reacts to form secondary particulates. A catalyst must combine high NOx conversions to elemental nitr ogen and water along with low ammonia slip. In principle, the catalyst has acidic surfaces t hat retain unreacted ammonia; the storage capacity of these acidic sites depends on temperature. According to Barbaro 10 , a good

flow distribution is needed to ensu re minimal ammonia slip. The Cemex

– Lyons kiln has neither the temperature nor the flow characteristics necessary for optimal catalyst performance.

Another concern for t he Cemex

– Lyons kiln

, is the potential for ammonia slip to create visibility impair ment that is readily transported into nearby Rocky Mountain National Park.

Presently, SCR has not been applied to a cement plant of any type in the United States. Cemex notes that the major SCR vendors have indicated that SCR is not commercially available for

cement kilns at this time

. Of the four major vendors contacted, two, Lurgi PSI Inc. (Lurgi) and Babcock & Wilcox, did not provide any proposal, with Lurgi stating that their technology was not yet ready for commercial

release. A third with relevant ex perience from the Solnhofen demonstration plant, KWH, indicated that technical uncertainties prevented th em from designing an SCR system . Only Alstom provided a proposal that suggested SCR could be supplied to a cement kiln system.

10 See Barbaro, P.; Bianxhini, C. Wiley

- VCH, Catalysis for Sustainable Energy Production (2009)Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 20 However, careful revie w of the Alstom proposal indicated that the Alstom proposal did not identify a commercial SCR system that would be viable for a cement kiln system application.

The Division finds that a limited use

- trial basis application of an SCR control technology on three modern kilns in Europe that differ significantly from the Cemex

– Lyons kiln design does

not constitute “available” control technology for purposes of BART. The Division notes that very specific temperature and dust content parameters must be achiev ed prior to the catalyst reactor elements to preclude plugging issues. As mentioned in the EPA report, “The advantages to the low dust configuration are longer catalyst life and lower danger of blockage. The disadvantage is the additional energy costs re quired to heat the cooled exhaust to achieve proper reaction temperatures in the catalyst .” Cement kilns are inherently very dusty environments; consequently for many cement kilns, the catalyst reactor must be installed after the baghouse as would be requ ired for the Cemex

- Lyons kiln

, which is a modified long

- dry kiln design. The Division believes that commercial demonstration of SCR controls on a cement plant in the United States is necessary for a control technology to be “ available ” for purposes of r etrofitting such control technology on an existing source. BART should not be a forum to test new experimental controls to see if they work, particularly when ideal design parameters are constrained in retrofit situations. Therefore, the Division has eli minated SCR as an available

control t echnology for purposes of BART.

Step 3: Evaluate Control Effectiveness of Each Remaining Control Technology

Step 4: Evaluate Impacts and Document Results

1

. Water Injection:
The injection of water or steam into the mai n flame of a k iln can act as a heat sink to reduce the flame temperature. Since NOx formation is a function of the flame temperature and residence time at that temperature, water injection reduces the generation of thermal NOx. Cemex

- Lyons

has stated t hat its own experience indicates that water injection can reduce the thermal NOx by approximately 7%. The Division anticipates some reduction in thermal NOx formation when water is injected into the area where the flame temperature is the highest. Aside from actual testing in the kiln, a 7% reduction seems reasonable.

Cost of Compliance:

Based on information from Cemex

– Lyons , the Division estimates the annualized costs of water injection at about $ 43,598 with minimal ann ual operating cost s . Assuming a 7% NOx reduction, the control cost is about $356 per ton of NOx reduced.

Energy Impacts and Non Air

- Quality Impacts : The only non

- air quality impacts associated with water injection is the use of a precious resource in limited supply in the arid west.

Exis ting Controls in Use at Source :

None.

Remaining Useful Life:
The remaining useful life of the kiln does not impact the annualized costs for water injection.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 21 2

. Cement Kiln Dust Insufflation:
Cement Kiln Dust (CKD) is a residual byproduct that can be produc ed by any of the four basic types of cement k iln systems. CKD is most often treated as a waste even though there are some

beneficial uses. However, as a means of recycling usable CKD to the cement pyroprocess, CKD sometimes is injected or insufflated int o the burning zone of the rotary k iln in or near the main

flame. The presence of these cold solids within or in close proximity to the flame has the effect of cooling the flame and/or the burning zone thereby reducing the formation of thermal NOx.

The in sufflation process is somewhat counterintuitive because a basic req uirement of a cement

k iln is a very hot flame to heat the clinkering raw materials to about 2700°F in as short a time as possible. Because of the thermal inefficiency associated with the p ractice, CKD insufflation is not an attractive control option for NOx. While the Division does not agree that the thermal inefficiency makes kiln dust insufflation technically infeasible, the Division has determined that that inefficiency, coupled with th e much greater reduction achieved through SNCR (discussed below), render insufflation inappropriate for the Cemex plant

. Cemex provided additional

information that indicates that CKD insufflation is not typically done because of operational

issues includi ng ring formation in the kiln. Consequently, the Division is not evaluating this control option further because of operational issues and the greater re duction achieved through

SNCR.

3

. Firing Tire

- Derived Fuel:
Secondary combustion is defined as follows: a portion of the fuel is fired in a location other than the burning zone. This reduces thermal NOx generation because the temperature in the secondary combustion zone is less than 2100 °F. F iring of solid fuels, such as used tires, is an example of seco ndary combustion. The Cemex

– Lyons kiln has conducted testing of tire derived fuel (TDF) which can be introduced at the kiln feed shelf, creating a secondary

combustion zone in the riser between the kiln and the combustion chamber.

In November 2002, a pr eliminary performance (stack) test was conducted to compare fossil fuel (coal & natural gas) with coal supplemented with TDF (coal & tires) which indicated about a

24.4 % reduction in NOx in the exhaust stream. Cemex estimates that firing TDF can reduce

N Ox by 10% on a long term basis if utilized. The stack tests show that TDF can be burned without exceeding applicable emission limits for either criteria pollutants or hazardous air pollutants. Both the Division and Cemex contin ue to believe that firing T DF is a viable NOx reduction control strategy under appropriate conditions along with consideration of the stack

tests results and the fact that TDF is widely used as an alternative fuel. Nevertheless, some in the Lyons community have expressed reservatio ns about the tire burning, and requested a moratorium on using TDF. In response to concerns, and in consideration of a Division issued Compliance Order on Consent (Case No. 2005

- 049), Cemex agreed not to use TDF as an alternative fuel in the kiln for a pe riod that expired on December 31, 2007. Presently, Cemex may commence using TDF as permitted in accordance with the terms and conditions of Permit No. 95OPBO082, unless TDF is prohibited by another legally enforceable requirement

. Potentially, TDF could be used in combination with other control technologies, such as SNCR to meet additional BART NOx reduction objectives.

Cost of Compliance:
Cemex provide d limited TDF cost information because of ongoing community concerns associated with burning tires. The annualized costs are about $172,179 per year; however the costs of acquiring TDF and the transportation costs were not included

. Assuming the aboveColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 22 annual cost and the estimated 10% NOx reduction, the control cost is estimated at about $986 per

ton of NO x reduced.

Energy Impacts and Non Air

- Quality Impacts : There is community concern associated with fuel switching to TDF.

Existing Controls in Use at Source :

None.

Remaining Useful Life:

No impact

4

. Indirect Firing with Low

- NOx Burners:

Low NOx burners (LN Bs) reduce the amount of NOx formed at the flame. The principle of all LNBs is the same: stepwise or staged combustion and localized exhaust gas recirculation (i.e., at the flame). As applied to the rotary cement Kiln, the low

- NOx burner creates primary and secondary combustion zones at the end of the main burner pipe to reduce the amount of NOx initially formed at the flame. In the high

- temperature primary zone, combustion is initiated in a

fuel

- rich environment in the presence of a less than stoichiome tric oxygen concentration. The

oxygen

- deficient condition at the primary combustion site minimizes thermal and fuel NOx formation and produces free radicals that chemically reduce some of the NOx that is being generated in the flame.

In the secondary zone , combustion is completed in an oxygen

- rich environment. The temperature in the secondary combustion zone is much lower than in the first; therefore, lower NOx formation is achieved as combustion is completed. CO that has been generated in the primary com bustion zone as an artifact of the sub

- stoichiometric combustion is fully oxidized in the secondary combustion zone.

The EPA has indicated that a 14% reduction in NOx emissions may be anticipated in switching

from a direct

- fired standard burner to an indir ect

- fired LNB. This is based on a study conducted

on an indirect

- fired LNB at the Dragon Product Company cement kiln at the plant located in Thomaston, Maine. However, the EPA has also determined that the emission reduction

contribution of the LNB itself and of the firing system conversion direct to indirect cannot be

isolated from the limited data available. The terms direct and indirect firing have unique meaning in the context of Kiln firing (unlike the more general meanings where direct firing implie s that the products of combustion contact the process materials whereas indirect firing involves a heat transfer medium). In Kiln firing, direct and indirect firing describes the manner in which pulverized fuel is conveyed from the fuel grinding mill to th e burner. Cemex ha s estimated that a LNB would low er NOx by 20% at the Lyons plant.

Cost of Compliance:
Cemex also provided information from a NESCAUM report (Dec 2000) that indicates 20

- 30% NOx reduction can be achieved through the use of indirect firing with LNBs. Cost data was included from a study of California Portland Cement (Colton, CA) that evaluated TDF along with indirect firing w/LNBs that indicates $7 million capital cost and $350,000 annual O&M costs. This study includes TDF firing and does not separate out the actual cost associated withColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 23 the indirect firing with LNBs. The Division has estimated the annualized cost at about $710,750 with a result control cost of about $2,034 per ton of NOx reduced.

Energy Impacts and Non Air

- Quality Impacts :

None.

Existing Controls in Use at Source :

None.

Remaining Useful Life:

No impact

5

. Selective Non

- Catalytic Reduction (SNCR) : In the relatively narrow temperature window of 1600 to 1995°F, ammonia (NH3) reacts with NOx without the need for a catalyst to f orm water and molecular nitrogen in accordance with the following simplified reactions.

4NO + 4NH3 + O2 4N2 + 6H2O

2NO2 + 4NH3 + O2 3N2 + 6H2O

As applied to NOx control from cement kilns and other combustion sources, this technology is

called Selectiv e Non

- Catalytic Reduction (SNCR). Above this temperature range, the NH3 is oxidized to NOx, thereby increasing NOx emissions. Below this temperature range, the reaction rate is too slow for completion and unreacted NH3 may be emitted from the pyroprocess

. This temperature window generally is available at some location within rotary kiln systems

. The NH3

could be delivered to the kiln s ystem through the use of anhydrous NH3, or an aqueous solution of NH3 (ammonium hydroxide) or urea [(NH2)2CO]. A concer n about application of SNCR technology is the breakthrough of unreacted NH3 as “ammonia slip” and its subsequent reaction in the atmosphere with SO2, sulfur trioxide (SO3), hydrogen chloride (HCl) and/or chlorine (Cl2) to form a detached plume of PM10

– PM2 .5.

SNCR is being evaluated at 45 to 50% control efficiency depending on the averaging period

. The Cemex kiln /flash calciner configuration is best described as a modified long dry kiln. The Division has conducted extensive research and has not found any documentation on similar kiln types. EPA’s Alternative Control Techniques Document Update

– NOx Emissions from New Cement Kilns (November 2007) addresses only new cement kilns. These new kilns are multi

stage (4 or 5 stage) preheater/precalciner kilns an d are not comparable to Cemex

– Lyons

unusual modified long dry kiln. The Division has also considered the Cemex Brooksville plant in Florida, but it is a multi stage preheater design and is not comparable to the Lyons facility.

The Division’s evaluation reveals that the Solnhofen facility achieved only 50% reduction with

SCR. Significantly, t he Division is concerned that requiring a high er reduction through SNCR ( beyond 45 % on a 30 day rolling average) could cause excessive ammonia slip t hat would

exace rbate the nitrogen deposition concerns at Rocky Mountain National Park. Considering the close proximity of Cemex to RMNP, any unreacted ammonia (slip) is available to react with oxides of nitrogen or sulfur to form par ticulates (nitrate or sulfate) a pote ntially significant

contributor to visibility impairment.

It is important to note, that a ll kilns are not created equal. Modern 5

- stage preheater/ c alciner

kilns are not an appropriate comparison to the unusual and modified configuration of the CemexColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 24 – Lyo ns 40

- year old kiln. Consequently, it is difficult to assert what amount of NOx reduction

can be achieved with SNCR controls on this older modified long dry kiln. It is important to realize that a higher SNCR control efficiency in a long type kiln necess itates the injection of

more ammonia (higher molar ratio) to increase the opportunity for reacting with oxides of nitrogen. This is particularly important to understand with old er kilns where operating parameters are often less than the engineering ideal. Often residence time and temperature limit

the effectiveness of the reaction. Any excess ammonia (slip) that fails to react, largely because the temperature is too low, is exhausted out the stack to eventually form particulates which

counter acts the ori ginal basis for the emissions control

– visibility. Thus, if EPA desires higher control efficiency, the penalty is more visibility impairment downwind of the source. Therefore,

the engineer ing evaluation must consider the balance between high control effi ciency and ammonia slip.

Cost of Compliance:
Based on information provided by Cemex

– Lyons, the Division estimates the annual costs at about $1, 636

, 636 per year. Assuming a 48.43% NOx reduction, the control cost is about $1,934 per ton of NOx reduced.

En ergy Impacts and Non Air

- Quality Impacts :

None.

Existing Controls in Use at Source :

None.

Remaining Useful Life:

No impact

.

6. Selective Non

- Catalytic Reduction with Low NOx Burners (LNB):

C emex conducted a BART analysis for the kiln located in Lyons, C olo rado and concluded that

SNCR could reduce nitrogen oxides (NOx) emissions on a long

- term basis by about 50 percent. Various entities have suggested that C emex provide an analysis combining l ow NOx burners and

SNCR with the goal of achieving a higher NOx r eduction , perhaps as high as 60 percent. Accordingly, this analysis has been revised to evaluate the combination of low NOx burners and

SNCR.

In the cement manufacturing industry, it is well known that thermal NOx represents the majority

of the NOx format i on in cement kiln systems. T hermal NOx is a side effect of the high temperatures necessary in the cement kiln to produce a quality clinker product . One effort to combat the thermal NOx formation in the cement industry has been the installation and use o f LNB. LNB have been used to a limited degree in the cement industry for over 30 years. The concept of LNB is to minimize primary air as a source of nitrogen, reduce flame turbulence, delay air and fuel mixing, and establish a fuel rich zone for initial combustion. The resulting longer, less intense flame from the staging of combustion in this manner reduces flame temperatures and is therefore thought to reduce thermal NOx formation.

In practice, LNB create two distinct combustion zones: the primary and the secondary combustion zones. In the primary, or initial, combustion zone flame turbulence and air and fuel mixing are suppressed by decreasing the amount of primary air supplied to the burning zone. ItColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 25 is well understood that the higher the primary ai r, the higher the NOx from the kiln system. 11
Typical primary air for LNB ranges from 5 to 7 percent. 12 The result is a fuel

- rich, oxygen

- lean, high temperature combustion zone created by reducing the amount of primary air and delaying

the combustion of al l of the fuel. The peak flame temperatures in the primary combustion zone must be maintained high to initiate the clinkering reactions. However, thermal NOx formation is thought to be suppressed due to the oxygen

- lean environment in the primary combustio n zone which generates excess CO and other radicals known to react with NOx.

The primary combustion zone is followed by an oxygen

- rich secondary combustion zone where fuel combustion is completed. Lower temperature secondary combustion air is mixed into t he secondary combustion zone, thereby lowering the peak combustion temperatures. Although excess oxygen is available, NO x formation is suppressed in the secondary combustion zone because the temperatures are insufficient for significant thermal NOx format ion.

The Lyons Plant is currently equipped with a two channel, straight pipe burner with one channel for coal and a second channel for air used to adjust the momentum of the flame. The burner configuration is closer to a mono

- channel than to a multi

- channe l burner definition. The measured primary air at the Lyons Plant ranges from 40 to 65 percent accordingly to the amount of momentum air used, with most of the primary air coming from the coal mill’s minimum air evacuation requirements. The application of L NB at the Lyons Plant would primarily consist of replacing the existing main kiln burner.

The level of NOx reduction reported in the literature for LNB applications on cement kiln systems vary considerably. Factors affecting the variability include, but a re not limited to the specific type of LNB, pre

- installation NOx emission le vels, kiln type, and fuels used

. According to EPA’s “Alternative Control Techniques Document Update

– NOx Emissions from Cement Manufacturing,” EPA

- 453/R

- 94

- 004, March 2004, the N Ox reducti on achievable with LNB ranges f r o m 20 to 30% for typical kiln systems

. The level of control achieved is generally greater for newer kiln systems. Many older kiln systems may achieve lower NOx reduction s due to the specific operating characteris tics of the kiln systems. There are also a few non

- typical kiln systems in the US, with one being the Lyons Plant. Considering the unique design and age of the

L yons Plant cement kiln system, it is uncertain whether meaningful NOx reduction s would be

exp ected from the installation of LNB in combination with SNCR

.
C emex has proposed the installation and use of SNCR to achieve about a 50% NOx reduction (long term) at the Lyons Plant. This level of NOx reduction has been demonstrated on several

cement kiln systems in the US, is recognized in the recently EPA proposed New Source Performance Standards as the demonstrable control efficiency for SNCR, and represents a high level of control with little risk of the known side effects to ammonia injection. The mai n risk for SNCR is the formation of a detached plume attributable to excessive ammonia slip due to injecting at too high of a normalized stoichiometric ratio ( NSR ) (i.e., pushing the SNCR technology too far to achieve higher levels of NOx reduction leads t o the formation of a detached ammonia plume, called ammonia slip). Ammonia slip from SNCR is non

- existent to minimal when the reagent is injected at or below an NSR of about 0.7. Operating SNCR above this NSR significantly increases the ammonia slip to t he point where conditions are favorable for the

11 Battye, R., Walsh, S., and Greco, J. 2000 . NOx control technologies for the cement industry. Final report. Pages

30

- 31. EPA contract No. 68

- D98

- 026.

12 Battye, R., Walsh, S., and Greco, J. 2000. NOx control technologies for the cement industry. Final report. Page

59. EPA contract No. 68

- D98

- 026.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 26 formation of a detached plume containing ammonium chloride and ammonium sulfide compounds. These compounds, as well as any unreacted ammonia, would result in visibility degradation which is counter to the in tent of BART.

Therefore, the Division concludes that given the reasonable uncertainty in the benefits of LNB,

the exis ting proposal to utilize the existing burner along with SNCR remains the best control option for the Lyons Plant kiln.

Cost of Compliance:
Based on information provided by Cemex

– Lyons, the Division estimates the annual costs at about $1, 686

, 395 per year. Cemex provided an estimated 5 5 % NOx reduction resulting in an

estimated control cost of about $1,755 per ton of NOx reduced.

Energy Impa cts and Non Air

- Quality Impacts :

None.

Existing Controls in Use at Source :

None.

Remaining Useful Life:

No impact

.

Table 10 below contains a ranking by control effectiveness of the remaining control technologies.

Table 10 : Kiln NOx Control Options

Control Technology Estimated

Control Efficiency Annual Controlled

Hourly NOx Emissions [lbs/hr] Annual

Controlled NOx Emissions [tpy] Annual Controlled

NOx Emissions [lb/ton of Clinker]

Baseline NOx Emissions

- 464.3 1,747.1 7.39

Water Injection 7% 431.8 1,624. 8 6.87

Firing TDF 10% 417.8 1,572.3 6.65

Indirect Firing with LNB 20% 371.4 1,397.6 5.91

SNCR 45% 255. 3 960.9 4.06

SNCR 48.43 % 23 9

. 4 901.0 3.81

SNCR w/LNB 55 % 208.9 786.2 3.33

SCR Not technically feasible

Table 11 below lists the NOx emission reduct ion, annualized costs and the control cost effectiveness for the feasible controls, ranked by control effectiveness.Colorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 27 T able 11 : S ummary of Cost Effectiveness of NOx Control Technologies for the Kiln

Control Technology NOx Emission

Reduction Annualized

Cos t Cost

Effectiveness Incremental Cost

Effectiveness

[ tons/yr ] [ $/yr ] [ $/ton ] [$/ton]

Baseline NOx Emissions

- Water Injection 122.3 $ 43

, 598 $356

Firing TDF 174.7 $172,179 $986 $2,45 3

Indirect Firing with LNB 349.4 $710,750 $2,034 $3,083

SNCR (4 5% control) 786.2 $1,636,636 $2,082 $2,120

SNCR (48.43 % control) 846.1 $1,636,636 $1, 934 $ 1

, 864

SNCR w/LNB (55% control w/uncertainty ) 960.9 $1,68 6, 395 $1, 755 $ 434

Based on the above discussion, the combination of SNCR with LNB has an uncertain level o f

control due to the unique nature of the Lyons kiln

. The Division has determined that SNCR is the best available NOx control option for the Cemex

– Lyons modified long dry kiln . Because Cemex has proposed SNCR as the preferred control option, it is not necessary or appropriate to further evaluate the lesser control options, including relative costs.

SNCR requires injection of the reagents in the kiln at a temperature between 870 to 1,090°C (1,600 to 2,000°F). In principle, any of a number of nitrogen com pounds may be used as SNCR reagents (e.g., cyanuric acid, pyridine, and ammonium acetate). However, for reasons of cost, safety, simplicity, and by

- product formation, ammonia and urea have been used in most of the SNCR applications. The selection of reage nts is process and temperature specific. At higher temperatures, urea decomposes to produce ammonia, which is responsible for NO x reduction. In cement kiln applications, ammonia typically has performed best as the reducing reagent. Because no catalyst is used to increase the reaction rate, the temperature window is critical for conducting this reaction. At higher temperatures, the rate of a competing reaction for the direct oxidation of ammonia, which actually forms additional NO x , becomes significant. At lower temperatures, the rates of NO x reduction reactions become too slow resulting in too much unreacted ammonia being released to the atmosphere (i.e., ammonia slip). The effective temperature window range can be lowered to about 700°C (1,300°F) by the a ddition of hydrogen along with the reducing agent.

The NO x reduction efficiency of SNCR depends upon the temperature, oxygen, carbon monoxide, and residence time, as well as the ammonia and NO x concentrations in the flue gas. Injection of ammonia at a NH 3 : 3 NO x proportion of 1 to 1.5 will reduce NO x emissions between 60 to 80 percent. Using a molar ratio of 0.5 will give NO x reductions of approximately 40 percent. Work done by the German equipment supplier Polysius has shown that the optimum temperature f

or reduction of NO x by ammonia is about 950oC (1,740oF), while for urea, the temperature increases to about 1,000oC (1,830oF).

Operating experience has identified several concerns with both ammonia and urea

- based SNCR processes. The most frequently reporte d is the buildup of ammonium bisulfite or bisulfate scale, which is significant for sulfur

- containing fuels. SNCR processes also appear to convert some

NO x to N 2 O. The rate of N 2 O formation is a weak function of both the reactant and the NOColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 28 concentration. However, N 2 O formation seems to be inherently more prevalent in systems using urea than those using ammonia.

The NO x destruction efficiency also depends upon the flue gas residence time in the appropriate temperature window. Unlike an SCR system where t he reaction temperature is controlled in a dedicated reactor, an SNCR system relies on the existing gas temperature profile to provide an adequate residence time for a desired NO x destruction. Maximum achievable NO x reduction in a cement kiln may thus depe nd upon the gas temperature profile.

Based on the foregoing discussion and the potential for ammonia slip , the Division concludes

that an assumed 45 % NOx reduction (30

- day rolling average) and 48.43 % NOx reduction (annual average) from 2002 baseline is rea sonable.

Step 5: Evaluate Visibility Results

An impact analysis was conducted to assess potential visibility improvements associated with SNCR. CALPUFF modeling was used as part of this analysis. The visibility improvement

associated with various scenari os was calculated as the difference between the existing visibility impairment and the visibility impairment for the controlled emission rates as measured by the

98 th percentile modeled visibility impact. Based upon the modeling, the addition of SNCR is

p rojected to result in a 0.4 1 dv improvement

.
Table 1 2 : Visibility improvement for NOx Controls

– Kiln Only

Control Method 98th

Percentile Impact 98th Percentile

Improvement (f rom 24

- hr Max ) Cost

Effectiveness

( Δ dv) ( Δ dv) ($/ Δ dv)

24

- hr Maximum ( ≈ 656.9 lbs/hr) ) 0.760

Revised Baseline ( ≈ 464.3 lb s /hr) * 0.572 0.188

Original Baseline (≈ 446.8 lb s /hr) * 0.555 0. 205

Water Injection (≈ 431.8 lb s /hr) * 0.540 0.220 $198,174

Firing TDF (≈417.9 lbs/hr) * 0.526 0.234 $735,807

Indirect Firing with LNB (≈ 371.4 lb s /hr) * 0.481 0.279 $2,547,493

Original BART Limit

– SNCR (≈ 2 68 .0 lb s /hr) 0.380 0.38 0
Proposed BART Limit (30

- day)

– SNCR (≈ 2 55.3

lb s /hr) ** 0.368 0.392 $4,175,091

Proposed BART Limit (annual)

– SNCR (≈ 2 3 9 .0

lb s /hr) ** 0.352 0.408 $4,011,363

SNCR w/LNB (≈208.9 lbs/hr) ** 0.322 0.438 $3,850,217

*

- Visibility impacts interpolated from original BART CALPUFF modeling

* *

- Visibility impact s extrap olated from original BART CALPUFF modeling

Step 6: Select BART Control

The Cemex

– Lyons facility is a unique kiln system most accurately described as a modified long dry kiln, the characteristics of a modified long dry kiln system are not similar to either a long wet kiln or a multi stage pr eheater/ precalciner kiln. The temperature prof ile in a long dry kiln system ( >1500 o F) is significantly higher at the exit than a more typical preheater precalciner kiln ( 650 o F). This is a significant distinction that limits the location and residence time available forColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 29 an effect ive NOx control system. As discussed above, the combination of SNCR with LNB has

an uncertain level of control due to unique nature of the Lyons kiln. Furthermore, the associated

incremental reduction in NOx emissions associated with SNCR in combination with LNB would afford only a minimal or negligible visibility improvement (less than 0.03 delta deciview )

. Therefore, the Division believes that SNCR is the best NOx control system available for this

kiln.

The Division has considered the five factors and has thoroughly reviewed the data supplied by

Cemex to determine that SNCR represents Best Available Retrofit Technology for control of NOx emissions from the kiln. Table 13 specifies the Division NOx BART determination of 255.3 pounds per hour (30

- day rol ling average) and 901.0 tons per ye ar (12

- month rolling average). The Division considered establishing a NOx emissions limit based on clinker production, however, the Cemex

- Lyons facility does not have the capability to weigh clinker product upon exiting the kiln. Consequently, compliance with the NOx BART limits will be determined by a continuous emissions monitor system (CEMS).

Table 13: NOx Emission Limits on the Kiln Subject Unit NOx Control Technology NOx Emission Limits

Kiln System Selective Non

- C atalytic Reduction (SNCR) 255.3 lbs/hour (30

- day rolling average)

901.0 tons/year (12

- month rolling average )

The Division has reviewed the analysis provided by Cemex and agrees that SNCR is the appropriate NOx control technology . In reviewing the pro posed emission rate of 255.3 lbs/hour (approximately equal to 4.06 lb/ton of clinker ) , the Division also looked at the

RACT / BACT / LAER clearing house (see Table 1 4 below). The NOx rate of 4.06 lb/ton clinker

is consistent with determinations made in Iowa a nd Missouri, but is about double the proposed

limits for the newer Florida kiln s. The Cemex

– Lyons facility is an older modified long dry kiln and does not have the precalciner systems developed for newer facilities specifically to reduce the temperature s for clinker formation. The use of lower temperatures also reduces the

formation of thermal NOx

.
Table 1 4 : RACT/BACT/LAER data for NOx emissions from Portland Cement Kilns

RBLC ID NOx Control NOx Limit Units Year

FL 0297 SNCR 1.5 lb/ton clinker 2007

F L

- 0271 SNCR 1.95 lb/ton clinker 2006

FL

- 0268 SNCR 1.95 lb/ton clinker 2004

FL

- 0267 SNCR 1.95 lb/ton clinker 2004

SD

- 003 Preheater/calciner 2267 tons/yr 2003

MO

- 0059 SNCR 8 lb/ton clinker 2002

IA

- 0052 Process 4 lb/ton clinker 2002

TX

- 0355 Process 660 lb/hr 2001

FL

- 0139 Process 2.9 lb/ton clinker 2000

The Division also reviewed the U.S. v. Lafarge Consent Decree

, dated January 21, 2010. In that recent action, the NOx reduction requirements established under the kiln retrofit options requireColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 30 SNCR wit h a 12

- month rolling emission limit of 4.89 lbs NOx/ton of clinker. The BART Regulations d o not require the demolition and reconstruction of any facility that is subject

- to

BART. The proposed Cemex BART limit compares favorably to similar units addressed by the Lafarge Consent Decree and the RACT / BACT / LAER clearinghouse. While determinations made by other states do not dictate the emissions rate choice made by the Division, they do provide information on the range to validate the emissions rate chosen by the Division. Because the Cemex kiln is a modified long dry kiln and is not directly comparable to the reported limits

listed in the RACT/BACT/LAER clearinghouse, the Division finds that requiring an emission rate that falls into the range for modern sou rces that are more thermodynamically efficient ( produce less NOx ) help s to further validate the stringency of the NOx emissions rate selection.

The Division is aware that Cemex may be able to do better than a 45 % reduction, and will require that 48.43 % red uction on an annual basis (901.0 ton s per year
, 12

- month rolling

average ). Th is limit results in reductions that are 6 8 % lower than the current allowable NOx

limit (2,649 tpy) contained in the operating permit.

The Division also notes that the flash vesse l at Cemex

- Lyons is unique and may affect how well SNCR will perform at the plant. Because of this uncertainty the Division will not specify the ammonia injection or slip rate but will allow Cemex

- Lyons to meet the NOx limits through SNCR technology a nd process controls. Improving process controls may allow Cemex

- Lyons to limit formation of NOx in the kiln and thus meet the NOx limits while reducing ammonia use. By requiring a 48.43% reduction on an annual basis, the Cemex BART determination almost

matches the reductions achieved for both SCR and SNCR at the Solnhofen facility

. Accordingly, based upon its analysis and consideration of the five factors, the Division has determined that the higher NOx emission rate is reasonable for the older cement k iln process,

and that SNCR control at 255. 3 lb/hr NOx on a 30

- day rolling average (which is about 4.06 lbs of NOx per ton of clinker) is NOx BART for the Cemex

– Lyons facility. This BART

determination will remove 45% of the NOx emissions averaged over 30 days, and is projected to

result in about 0.3 9 Δ dv in visibility improvement.

III.C. Review of Particulate Matter Controls on the Kiln and Dryer

PM emissions from the kiln are currently contr olled by fabric filter baghouse and wet dust suppression techni ques. Emission testing from the kiln has demonstrated compliance with the National Emission Standards for Hazardous Air Pollutants for Source Categories; Portland

C ement Manufacturing Industry, 40 CFR Part 63 Subpart LLL. The NESHAP standard applies

the kiln and establishes PM emissions limit s.
During development of the NESHAP standard, EPA was not able to identify any technologies for existing or new kilns that would consistently achieve lower emissions than the New Source Performance Standards (NSPS). Consequently, the level of the NESHAP standard is the same as NSPS and requires compliance with certain particulate emission limits and opacity limits. The

NESHAP standard also includes emission limits for HCl and other hazardous pollutants;

however these are not considered for their impact on visibility. The provisions of the NESHAP standard are already contained in the operating permit issued to Cemex

– Lyons . For sources already regulated by a NESHAP standard, EPA stated the following in the BART guidelines:

“ We believe that, in many cases, it will be unlikely that States will identify emission controls more stringent than the MACT standards without identifying control options that would cost many tho usands of dollars per ton. Unless there are new technologies subsequent to theColorado Department of Public Health and Environment

- Air Pollution Control Division

Best Available Retrofit Technology (BART) Analysis: Cemex

– Lyons Page 31 MACT standards which would lead to cost effective increases in the level of control, you may rely on the MACT standards for purposes of BART .” [70 FR 39163]

The Division has re viewed the requirements of the NESHAP ( MACT ) for Portland cement production and evaluated the RACT / BACT / LAER clearinghouse database for other available particulate control options (see Table 1 5 ). The Division has determined that no new particulate

control methodologies are identified that would improve upon the PM controls required in the

NESHAP.

Table 1 5 : RACT/BACT/LAER data for PM emissions from Portland Cement Kilns

RBLC ID PM Control PM Limit Units Year

FL 0297 Fabric Filter 0.1 lb/ton clinker 2007

MO

- 0072 Baghouse 0.516 lb/ton clinker 2006

FL

- 0271 Baghouse 0.1 lb/ton clinker 2006

FL

- 0268 Baghouse 0.2 lb/ton clinker 2004

FL

- 0267 ESP 0.2 lb/ton clinker 2004

SD

- 003 Fabric Filter 0.13 lb/ton 2003

MO

- 0059 Fabric Filter 99% 2002

IA

- 0052 Baghouse 0. 5160 lb/ton clinker 2002

TX

- 0355 ESP 40 lb/hr 2001

FL

- 0139 Baghouse 0.11 lb/ton clinker 2000

Therefore, the Division is establishing the following PM and opacity limits as BART for particulate matter control that is based on the NESHAP 40 CFR Part 63 S ubpart LLL:

Table 1 6 : Particulate Matter Emission Limits on the Kiln and Dryer

Subject Unit Control Technology PM Limits from 40 CFR

Part 63 Subpart LLL BART PM Emission

Limit s

Kiln System Fabric Filter

Baghouse 0.3 0 lb/ton of dry feed 20% opacity 0.275 lb/ton of dry feed 20% opacity

Dryer Fabric Filter

Baghouse 10% opacity 22.8 tons/year* 10% opacity

* Current emission limitation from O perating P ermit (95OPBO082)

The Division has established a PM limit on the kiln system that is more stringent than t he NESHAP, which is already in the Cemex

– Lyons Operating Permit. Because the current

NESHAP limits constitute the most stringent level of control , the State does not need to provide

a five

- factor analysis for PM for these units.