Andover Technology Partners Page 1 March 10 , 2009

To: Ravi Srivastava , Samudra Vijay, Elineth Torres Fm: Jim Staudt

Re: Costs and Performance of Controls

– revised from comments

In this program we will examine the costs, performance, and impacts of NOx and SO 2 controls for cement kilns as well as energy

- saving approaches that may have a beneficial impact on fuel consumption and/or CO 2 release and may be incorporated into the ISIS model

. In this memo I will frequently refer to the memo regarding “NOx , SO 2 and CO 2 E missions from Cement Kilns” and dated September 23, 2003 that I will refer to as the “Emissions Memo”.

Although this effort is intended to examine NOx, SO 2 , and energy (CO 2 ) saving technologies, some of these technologies offer multiple ben efits. So, categorizing technologies by benefit (NOx reduction, SO 2 reduction, or CO 2 reduction, etc.) can be misleading. In this effort, I will categorize the technologies by method, such as combustion technologies, gas treatment technologies, process m odifications (including material substitution), etc . For each technology I will provide estimates of each of the benefits or impacts as well as cost. For instance, the following will be provided:

**•** Capital Cost algorithm

**•** Fixed Operating Cost algorithm

**•** Var iable Operating Cost algorithm

**•** NOx reduction (if any)

**•** SO 2 reduction (if any)

**•** Fuel Savings or increase (if any)

**•** Power Increase or Decrease

**•** Calcination CO 2 impact (if any)

**•** By product benefits (if any)

**•** Water usage

Costs and Benefits of Controls or Process Modifications

The addition of controls or the modification of a cement kiln process entails the addition of equipment and perhaps annual costs for reagent or energy in order to realize the benefit of reduced emissions.

Costs of controls can be broken dow n to:

**•** Capital costs (CC)

– these are the costs of purchasing, installing, and commissioning the equipment that are realized on a one

- time basis



# Andover Technology PartnersAndover Technology Partners Page 2 **•** Variable annual costs (V C)

– these are the costs that are realized in proportion to the operation of the facilit y. Regents, parasitic power, and t hermal energy are examples of V C.

**•** Fixed annual costs (F C)

– these are costs that are realized each year that are not realized in proportion to the operation of the facility. Additional staffing and training of personnel, and taxes and insurance are examples of F C.

Generally, the most difficult costs to estimate are the capital costs. This is for the following reasons:

**•** Capital costs for retrofit s can be very site specific . So, actual costs for installing a technology on a specific kiln will vary based upon factors that are not well characterized by the general kiln characteristics

- kiln type and capacity

- which

are included in the database of kilns

.

**•** The relationship between capital cost and kiln output or another indicator of size is rarely constant. There frequently are “economies of scale” that make costs per unit output lower for larger units. To characterize these economies of scale it is necessary to have multiple data points for different sized kilns of the same type. Alternatively, some scaling factors can be assumed, but should be examined for their applicab ility.

**•** Data on capital cost can be sparse. Facility owners don’t always p ublish the capital cost or may not provide adequate detail on what the cost includes to make the information as useful as it could be

. Also, in the case of some technologies, there may be very few actual installations to base estimates on.

**•** Cost information can be from different years, which makes it less comparable. It is necess ary to adjust for this when possible. To address th is , a ll reported capital costs are shown in the year dollars of the source, and also for 2005$. Converting to 2005$ was performed using the Chemical Engineering Plant Cost Index (CEPCI) that is published in Chemical Engineering magazine.

Technologies

In the following sections, the technologies will be briefly described, recognizing that these technologies are described in more detail in referenced documents. The three major categories of technologies con sidered include Combustion Technologies, Gas Treatment Technologies, and Process Modification Technologies. Combustion Technologies operate by reducing emissions or otherwise improving operation by making changes to the firing process. Gas treatment tech nologies treat the gas and remove the pollution by addition of a reagent or by otherwise treating the gas without affecting the pyroprocessing portion of the kiln

. Process modifications actually c hange the process or change the feed materials. A final category of technologies is “Other”. These are generally energy saving methods that don’t easily fit into the other categories.Andover Technology Partners Page 3 

### Combustion Technologies

There are up to three possible combustion locations on a cement kiln facility. There are

two possible locations to add fuel within the kiln itself (at the hot end and mid

- kiln) , and the third location is the calciner. The most modern kilns are calciner type kilns with at least two combustion locations

– kiln and calciner. The other kiln types ge nerally only fire fuel within the kiln. Therefore, combustion technologies will be distinguished by whether they are in the kiln or in the calciner.

Kiln Combustion Technologies

There are two possible kiln combustion locations, the primary combustion zone and the mid

- kiln zone. The technologies include low NOx burners and Mid Kiln Firing. Mid Kiln Firing may be firing of coal or waste

– often tires.

Low NOx burner (LNB)

Low NOx burners may be supplied in a direct firing mode where the burner is fed directly from the coal mill. However low NOx burners for the primary kiln combustion

zone are typically used in an indirect firing mode, where the fuel is fed from a particle collection devic e that collects pulverized fuel downstream of the fuel mill. Indirect firing enables the low NOx burner to be run with lower primary air levels than a direct firing system. The low primary air levels help to reduce NOx formation. A low NOx burner retrof it is possible on all kiln types.

Reference 1

, showed cost algorithms for the Purchased Equipment Cost (PEC) for low NOx burners:

For a direct fired low NOx burner:

PEC (1997$) = 172,000 + 152 * H

, or E.1 PEC (2005$) = 216 ,000 + 19 1 H, where PEC = Multi

- channel direct fired low NO X burner purchase equipment cost in $,
and

H = Burner heat duty in MM Btu/hr.

Reference 1 showed annual costs for maintenance and operation of $59,200/year. Other
annual costs included in this reference we re Taxes, insurance, and admin of 4% of total capital costs

.

For an indirect fired low NOx burner:

1 NOX Control Technologies for the Cement Industry, FINAL REPORT

, EPA Contract No. 68

- D98

- 026, Work Assignment No. 2

- 28, EC/R Project No. ISD

- 228, September 19, 2000Andover Technology Partners Page 4 PEC (1997$) = 835,000 * (H/225) ^ 0.6 , or E. 2

PEC (2005$) = 1,050,000 * (H/225) ^ 0.6 , where

PEC = Multi

- channel direct fired low NO X burner purchase equipment cost in $,
and

H = Burner heat duty in MM Btu/hr.

The exponent of 0.6 that is used in Reference 1 in these algorithms to scale capital cost to kiln capacity will be used for all other equipment except where there is data to support another scaling factor.

To arrive at total capital costs, it is necessary to multiply PEC by a factor that accounts for other costs . Based on Reference 1 , these other costs are direct installation costs (45% of PEC), indirect installation costs (33% of PEC), Contingency (20% of PEC), Sales Tax (3% of PEC), and Freight (5% of PEC), totaling 108% of PEC. An allowance for production downtime should be included as well. In Reference 1, this was roughly $3500/ tph of clinker capacity. So, to arrive at the capital costs, the PEC should be multiplied by 2 .08 and production downtim e added. Assuming an 85% capacity factor, the equation for total capital is:

Total Capital ( 2005 $) = 2.08 * PEC + $3500 * ( TPY/(0.85*8760) ) E.3

Where TPY is the tons per year of annual capacity.

Also, H can be determined from the kiln specific fuel consumption SFC . For all kilns except for precalciners, specific fuel consumption times the clinker capacity will prov ide H. For precalciner kilns, the kiln burner receives anywhere from about 40% to 60% of the fuel, depending upon whether or not there i s bypass. The more modern kilns bypass gas from the cooler and use more fuel in the calciner than in the kiln to provide fully calcined material to the kiln

. 2 So, about 0.5 0 times specific fuel consumption times kiln capacity will provide H for precalcin er kilns. However, recognize that some older precalciner kilns may have a greater portion of total heat go to the kiln than the precalciner.

Applicability

All kilns

Capital Cost

For a direct fired low NOx burner:

2 Wikipedia, http://en.wikipedia.org/wiki/Cement_kiln#PrecalcinersAndover Technology Partners Page 5 **•** Capital Cost (2005 $) = 2.08 * [ 216,000 + 191 * SFC * ( TPY/(0.85*8760) ] + 3500* ( TPY/(0.85*8760) for all kilns but precalciners

**•** Capital Cost (2005 $) = 2.08 * [ 216,000 + 191 * 0.5 0 SFC * ( TPY/(0.85*8760) ] + 3500* ( TPY/(0.85*8760) for precalciners

For an indirect fired low NOx burner:

**•** Capital Cost ( 2005 $) = 2.08 * 1,050,000 * ( SFC * ( ( TPY/(0.85*8760) ) /225) ^ 0.6 + 3500* TPY /(0.85*8760 for all kilns but precalciners

**•** Capital Cost ( 2005 $) = 2.08 * 1,050,000 * (0. 5 0 * SFC * ( ( TPY/(0.85*8760) ) /225) ^ 0.6 + 3500* TPY/(0.85*8760) for precalciners

Fixed Costs

According to Reference 1, thes e are estimated at $59,200/year plus 4% of capital cost for taxes, insurance, etc.

Variable Costs

Variable annual costs are negligible for low NOx burners.

Impacts of burners:

The amount of NOx reduced by installation of a low NOx burner will be determined by the particulars of the kiln. Reference 1 showed data from low NOx burner installat ion s that varied from 15% to 47% for burners with indirect firing. No data was shown for direct firing, although the impact would certainly be less than indirect firing. A reasonable estimate of NOx reduction might therefore be in the range of 30% for a low NOx burner with indirect firing . For a low NOx burner with direct firing, the reduction would be less, perhaps in the range of 10%. However, due to the small benefit of direct firing, it would be reasonable to neglect it for the ISIS model.

Low NOx b urners will have no impact on SO 2 emissions and will have minimal impact on plant efficiency. However, there is a small impact on power demand that can be estimated. Assuming that there is roughly 6% primary air passing into the direct fired burner and t hat this air has a higher pressure drop of 15 IWC and is driven with a fan that is 75% efficient, for a kiln with a nominal flowrate of 50,000 SCF/ton, the incremental load of an indirect fired system is estimated to be about 0.09 kW per short ton. E .5 E.4

E .7 E .6Andover Technology Partners Page 6 Mid Kiln Firing (MKF)

Mid kiln firing allows the firing of tires, coal or other fuels at the mid

- kiln area. This permits less intense firing at the primary burner and will reduce NOx formation in the kiln. Tires or other waste fuels are often used at the mid

- kiln location because of the high temperatures and residence time in the kiln that permit good combustion and because these waste fuels also come with tipping fees. The other benefit is that MKF permits reduction of fossil fuel consumption when waste fue ls are used.

Reference 1 included estimates of capital cost for MKF

. Figure 1 shows the estimated $/TPY from the Reference 1 capital cost estimates

. Table 1 from R eference 3 is a more recent estimate that shows a tot al purchased equipment cost of roughly $1.1 million for a mid

- kiln firing system that fires lump coal mid

- kiln , including mixing air technology, which improves the perfo rmance of the mid

- kiln firing

. To address direct and indirect installation costs, this should be multiplied by about 2.08 an d then an allowance for production downtime might be added

. The result is close to the range of the estimates of Reference 1

.
Figure 1. Capital cost of Mid Kiln Firing (MKF) in $/TPY (1997$)

Applicability

Primarily Wet and Long Dry.

Capital Cost

The following capital costs are determined from Figure 1 :

3 E

- mail from Eric Hansen, Cadence Technologies, 6/20/08Andover Technology Partners Page 7 Capital Cost (1997$) = $2.0 (10) 6 * TPY - 0.959 * TPY = $2.0 (10) 6 * TPY 0.041 Capital Cost (2005$) = $2.52 (10) 6 * TPY 0.041 E.8

Table 1

. Budgetary cost for MKF with MA from Reference 3

Lump coal handling system $500,000
Mid

- Kiln equipment on kiln $250,000 MA equipment $250,000
Variabl e Frequency Drive $ 20,000 MKT and MA installation $ 35,000 Technical support commissioning and training $ 40,000

MA Equipment = overfire air injection sys tem

Fixed Costs

According to Reference 1, these are estimated at $59,200/year plus 4% of capital cost for taxes, insurance, etc. Reference 1 also shows a n annual license fee for tire injection that is equal to $300/MMBtu/hr of heat input. Or, on an annua l basis is equal to:

License fee = TPY * SFC *$300/(8760*0.85) E.9

Variable Costs

Variable costs include some additional power (about 50KW per Ref 3 ) and also a reduction in fuel costs if tires are used. Since MKF is installed mainly on wet and long dry kilns, which have typical capaciti es in the range of 300,000 TPY, the power usage would be roughly :

50 kW* 760*0.85 hr/300,000 TPY = 1.24 kWhr/ton cli nker E.10

Assuming an electrici y cost of $35/MWhr, then the energy cost is roughly:

VC power = 1.24 kWhr / ton clinker * 35/1000 = 4.34 cents per ton of clinker E.11

Mid

- kiln firing will a lso reduce fuel costs if tires are added. Rather than paying for the cost of coal, with mid

- kiln firing of tires it is possible to receive a tipping fee for burning the tires. In this case, the cement plant is actually paid to receive the fuel, called a tipping fee. Tipping fees were found to range from around $70/ton to around $150/ton, as shown
in the inset on the next page

.
If tires have a heating value of about 14,000 Btu/lb and a tipping fee of $100/ton can be received, then the tipping fee is about $3.60 per MMBtu. For a $70/ton tipping fee, the tipping fee is equal to about $2.50/MMBtu. This also offsets purchased fuel. If it offsetsAndover Technology Partners Page 8 coal, a rough delivered cost of $2.50/MMBtu might apply (this, of course, will vary based upon location). So, the net benefit might be in the range of $5/MMBtu or more for each Btu of displaced coal.

As a result of this fuel benefit, it might be expected that all virtually kilns would use tires. However, some don’t. Used tires may be abundant in some locations, but not in others

. Another reason some kilns don’t burn tires is likely due to permitting and community perception issues that create an obstacle.

For the mid

- kiln firing cases of Reference 4 , heat inputs for mid kiln firing range from 8% to 20 percent of the thermal input without mixing air technology. Wet kilns are typically limited to 15% to 20% substitution and dry kilns to 20% to 25% substitution without mixing air. With mixing air, fue l substitution rat e can be doubled in some cases

. 5 With mixing air technology, coal can be injected mid

- kiln at rates of about 35%, according to Cadence

. 6

So, for tire injection, an assumption of 15% displacement of heat input is reasonable and

conserv ative, and is consistent with what was assumed in Ref. 1 . In this case, the net fuel cost benefit might be in the range of:

VC Annual Savings from tires = TPY * SFC * 0.15 * 5 E.12

4 Northeast States for Coordinated Air Use Management (NESCAUM), “Status Report on NOx

– Control Technologies and Cost Effectiveness for Industri al Boilers, Gas Turbines, IC Engines, and Cement Kilns”, 2000

5 Hansen, E., “ "Staged Combustion for NOx Reduction Using High Pressure Air Injection", IEEE/PCA Conference 2002

6 http://www.cadencerecycling.com/pages/NOxReduction.html

Tire Tipping Fees

**California Integrated Waste Management Board** : http://www.ciwmb.ca.gov/landfills/tipfees/

2000 Survey Tires $/Each Tires $/Ton
Lowest (Except 0) $.75 $42.00
Highest $14.65 $280.00

Median $2.00 $95.00

Average $2.61 $102.70
Weighted Average (Landfills Only) $3.55 $67.67

Weighted Average (All Facilities) $3.53 $71.41

**Tennessee Solid and Hazardous Waste Management** $70per ton http://www.state.tn.us/environment/swm/tires/tiresfaq.shtml

**Waseca county Minnesota** : current tipping fee $100/ton and $150/ton proposed. http://www.co.waseca.mn.us/E

- board%20meetings/2008/04

- 01

- 08/tipping%20fee%203.pdAndover Technology Partners Page 9 Impacts of MKF

Mid kiln firing of tires or fuel can reduce NOx emissions significantly

– in the range of about 35%, per Reference 1 and shown in Table 2 . Mid

- Kiln Firing, particularly when used with mixing air, can have a positive impact on SO 2 emissions because it helps promote oxidation of SO 2 to sulfate (SO 4 ) in kilns where there may be poor mixing

. 5

, 7

The SO 2 benefit is hard er to predict because mixing air technology is relatively new and because the amount of SO 2 benefit will vary based upon particular conditions in the kiln.

Carbon dioxide may be affected. Tires make about the same amount of CO 2 per unit heat input as coal ( slightly less CO 2 per MMBtu than bituminous coal, about the same amount as PRB coal, ) and significantly more CO 2 per MMBtu than natural gas

. Tires, how ever, are not fossil fuel , although fossil fuel is used to make them . I f CO 2 emissions from tire comb ustion are treated differently from a regulatory perspective than CO 2 emissions from fossil fuel , the regulatory difference will need to be factored in to how CO 2 emissions are accounted for

. In any event , if the Mid

- Kiln fuel is different than the primary fuel, then the actual CO 2 emissions would change. The calc ulation is straightforward.

CO2FUEL = MCLINKER * SFC * ( FF 1 *LBCO2MMBTU 1 + FF 2 * LBCO2MMBTU 2
+ . . . FF i * LBCO2MMBTU i ) E.13

Where FF i is the fuel f raction for each fuel in thermal input

. A typical heat input for mid kiln firing is 15%. However, higher values are possible. If an annual estimate is desired , simply substitute TPY for MCLINKER.

Table 2. NOx missions from Kilns with Mid

- Kiln Firing (from Reference 1)

Kiln Emissions (lb NOX/ton of clinker) Percent Reduction (%) Emissions Based on CEMS
Data Dry Kilnsa
A not given 13.6 unknown
B not given 11.1 unknown
C not given 45.1 yes C not given 55.3 yes D 2.7 not given unknown
E 10.2 13.9 unknown
F not given 46.6 unknown
F not given 50.4 unknown
F not given 28.3 unknown Average (Dry Kilns) 6.4 33.3
Wet Kilns
G not given 59.0 yes H not given 35.0 unknown
I not given 27.6 unknown Average (Wet Kilns) n/a 40.5 Average (Dry & Wet Kilns) 6.4 35.1

Source: NOX Control Technologies for the Cement Industry, FINAL REPORT

, EPA Contract No. 68

- D98

- 026

, Work Assignment No. 2

- 28, EC/R Project No. ISD

- 228, September 19, 2000

7 Hansen, E., "Changing Process Priorities when Firing Alternate Fuels" IEEE/PCA Conference 2003Andover Technology Partners Page 10 Mixing Air Technology (MAT)

Mixing Air Technology may be used in combination with or not in combination with Mid Kiln firing or in combination with fuel addition at the preheater inlet (also called Riser Duct Firing) . MAT will help to enhance NOx reduction by facilitating staged combustion and can also help to reduce SO 2 emissions from long kilns or preheaters equipped in this way

. MAT is beneficia l even without mid

- kiln firing. Higher temperature oxygen

- rich gasses tend to travel along the top of the kiln while cooler, carbon dioxide

- ri ch gasses tend to travel along the bottom. When Mixing Air is added, stratified kiln gasses begin to rotate and mix , as shown in Figure 2 . This rotation improves combustion, serves to reduce emissions and improves th e overall stability of the kiln. Kiln s tability will improve NOx emissions, by reducing high NOx excursions, and can improve product quality and kiln output. Figure 3 shows a photo of a MAT installation.

By enhancing oxidizing conditions in a region where there is ample free lime, MAT will als o improve conversion of SO 2 to sulfate. Reductions of fuel SO 2 in excess of 90% have been reported

. 5 However, this may not be typical . The actual reduction in SO 2 emissions will vary depending upon the particular facility

. 5 Figure 4 shows the improvement in NOx, SO 2 , CO and to tal hydrocarbons when using MAT at one kiln.

Applicability

Primarily Wet, Long Dry and Preheater

– not as widely used on precalciner , except to facilitate stag ed combustion on the precalciner

.

Capital Cost

MAT equipment PEC is $250,000 per kiln per Reference 3 . Accounting for other costs, the total capital cost is therefore, roughly 2.08 times that, or about $520,000, plus an allowance for lost production. Using the same allowance for lost production as the low NOx burner would be conservatively high.

MAT Capital Cost (2008$) = $520,000 + 3500 * TPY/(0.85*8760)
MAT Capital Cost (2005$) = $470,000 + 3500 * TPY/(0.85*8760) E.14

Fixed Annual Costs

Being a combustion technology that does not require additional material handling equipment, F ixed Annual costs are expected to be similar to those of a low NOx burner.Andover Technology Partners Page 11 Variable Costs

There will be a small amount of power needed. If it is assumed that MAT uses about 5% of the total gas flow (probably conservatively high) the additional kW load can be estimated to be equal to roughly 0.025 kWhr per short ton if 50,000 S CF /short ton is typical . In fact, there may be no increase in power usage at all if the outlet oxygen is maintained the same because the primary or secondary air flow into the kiln would have to be reduced by an equivalent amount to keep outlet oxygen con stant.

Impacts

The impacts of MAT will va ry from one facility to another and are not as well characterized as the impacts of other technologies that have been available longer. CO emissions will be reduced quite a bit. NOx reductions will be determined by how much the operation is improved and stabilized. SO 2 emissions from the fuel will likely be reduced; however, MAT will have little effect on SO 2 that is produced by pyritic sulfur in feed materials. Since output of the ki ln might be improved somewhat, CO 2 emissions (on

a lb/ton clinker basis) might be reduced slightly. Figure 3 shows emissions impacts at one kiln equipped with Mixing Air Technology. Although impacts are not well characterized for MAT, MAT can have an imp ortant role for some technologies, su ch as MKF, riser duct firing low NOx precalciner and is therefore discussed here

.
Figure 2 . Mixing Air Technology from Ref. 5Andover Technology Partners Page 12 Figure 3 . Photo of Mixing Air Technology (Ref 5 )

Figure 4 . Emissions improvement with MAT at one kiln. (Ref. 5 )Andover Technology Partners Page 13 Non

- Kiln Combustion Technologies

For calciner kilns a substantial amount of combustion occurs in the calciner

– typically 60 % of the heat input (Ref 38 at p 245), but sometimes 50% (See Ref 22 at p 168). Preheater kilns typically only have combustion in the kiln. However, f or preheater kilns, the practice of riser duct firing has been employed in some cases primarily to reduce the thermal load on the kiln and to increase the amount of calcination that occurs in the preheater. About 15% of the fuel heat input may be into the preheater riser duct. 8 Due to the temperature in t he calciner and riser duct , thermal NOx formation in the calciner or riser duct burners is low , although thermal NOx is generated in greater amounts within the kiln

.
Preheater Riser Duct Firing (RDF)

In the case of preheater kilns with riser duct firing (RDF), the use of tires in the preheater (13% of heat input) produced a reduction of NOx of about 30%

- 40% at Mitsubishi Cement Company’s Cushenbury Plant in Lucerne Valley, CA. 8 According to Reference 5

, some NOx reduction should be possible using lump fuel, such as lump coal, if tires are not available , and with mixing air technology (MAT) the combustion in the preheater riser duct can be s taged to provide lower NOx emissions. Use of high volatile fuels are preferred.

Applicability

Preheater Kiln only

.

Capital cost

The cost of the addition of riser duct firing would likely be on the same order as mid

- kiln firing, since similar material hand ling equipment would be needed.

Fixed Annual Cost

This also should be similar to that of mid

- kiln firing

Variable Cost

Variable cost and power consumption will also be similar to that of mid kiln firing. It is important to include the fuel benefit when firing tires.

8 ASSESSMENT OF NOx EMI SSIONS REDUCTION STRATEGIES FOR CEMENT KILNS

- ELLIS

COUNTY FINAL REPORT

, TCEQ Contract No. 582

- 04

- 65589, Work Order No.05

- 06, July 14, 2006Andover Technology Partners Page 14 Impacts

The impacts will be to reduc e NOx by roughly 30% if tires are used. For use o f coal, the NOx reduction is likely to be less due to the lower volatile content of the coal versus tires.

Carbon dioxide may be affected. Tires make s lightly less CO 2 per MMBtu than bituminous coal, about the same amount as PRB coal, and significantly more CO2 per MMBtu than natural gas. Use the same equation described in the MKF section.

Low NOx Calciner ( LNC )

Combustion in the calciner can be s taged t o reduce NOx emissions with a rich combustion zone and a downstream air addition zone, as shown in Figure 5

. In this approach, NOx from the kiln is reduced in the fuel rich zone and then there is a burnout

zone. According to Reference 9 , there are three ways to achieve staging depending upon the kiln. Table 3 shows the emissions reduction from some plants that used staged precaliners

. As shown in Table 3 , the use of tires significantly enhanced performance. The minimum NOx level achieved under any condition was 1.4 lb/ton clinker and the highest was 3.0 lb/ton clinker, depending upon the kiln. With NOx reduction ranging from 17% to 44%, a reasonable “average” might be around 30%. However, it should be unde rstood that the actual level achievable for any particular kiln might differ from this.

Applicability

Precalciner only . Most precalciners likely use this to some degree.

Capital Costs

Capital cost information was not found. However, t o add fuel staging t o an existing calciner kiln might be similar to the cost of adding mixing air technology (MAT)

.

Fixed Annual Costs

Again, this is likely to be similar to adding mixing air technology..

Variable Costs

Variable cost changes should be negligible, except if ti res are substituted, which will actually be a cost reduction.

Impacts

NOx reduction of about 30% with few other impacts.

9 Alternat ive Control Techniques Document Update

- NOx Emissions from New Cement Kilns, EPA

- 453/R

- 07

- 006, November 2007Andover Technology Partners Page 15 Figure 5

. Principle of NO x reduction by SCC 9

Table 3. Summary of NO x Performance of SCC in U.S. Kilns

Source/Location NO x Uncontrolled (lb/t) NO x Controlled (lb/t) Efficiency

11 US kilns(from Table
7

- 2) NA 2.2

– 3.3 NA

(avg. 2.7)

Florida Rock 3.5 3.0

- w/o tires 17%

- w/otires

1.5

– 2.5 (midpoint 2.0)

- w/ tires 43%

- w/ tires

Suwannee American NA 2.2

– 2.6 (range) NA
2.4 (midpoint)

Titan American NA 2.0 NA

Lone Star 2.8 1.8 35%

Cemex Santa Cruz 9 NA 2.5 (0% coal to reducing zone NA
1.7 (50% coal to reducing zone) 32%
1.4 (100% coal to reducing zone) 44%
1.8 (midpoint) 28%

Alternat ive Control Techniques Document Update

- NOx Emissions from New Cement Kilns, EPA

453/R

- 07

- 006, November 2007Andover Technology Partners Page 16 

### Gas Treatment

SNCR

SNCR is commercially used on cement kilns to provide NOx reduction. It has been generally accepted as an approach for providing significant reduction on preheater and precalciner kilns. However, for long wet and long dry kilns an approach for admitting the reagent (ammonia or ur ea) to the furnace has been an obstacle to implementation of SNCR on long kilns. Cadence Technology has developed a method for injecting ammonia using technology similar to their mixing air t echnology, and shown in Figure 6 installed on a long kiln. 10

Figure 7 shows nominal capital equipment costs of SNCR from Reference 9 plotted on a $/ton clinker
basis versus year basis of the estimate. As shown, costs appear to have generally declined over time. 9 The most recent costs, in 2004 and 2006 base yea r dollars, are in the range of about $1/ tpy of clinker capacity for new kilns. The 1992 costs shown in Figure 6 are not costs for actual projects, but are based upon model kilns estimates. At the time of these estimates, SNCR had not been implemented on any kiln. So, the cost estimates were speculative. In any event, it is apparent that nominal costs have not risen and real costs have likely declined for SNCR. Or, the previous estimates were simply too high. Reference 8 project ed higher costs as well; but, these were based upon a speculative approach for how to employ SNCR on long

- wet cement kilns using mid

- kiln tire injection with urea in the tires, not the f airly simple approach that has been used by Cadence pictured in Figure 5.

10 Hansen, E, Reese, T,, “Eliminating NOx Barriers to Fuel Conversions with SNCR and Staged Combustion”, Global Fuels Conference, London, February 3

- 5, 2008, available for download at: http://www.cadencerecycling.com/pdf/CadenceGlobalFuelsPaper.pdf Figure 6. SNCR installed on a long kiln (Ref 10 )

Figure 7. SNCR Capital Costs in $/TPY from 2007 ACTAndover Technology Partners Page 17 Reference 11 cited a European study that found SNCR cost at around $ 1 /tpy on a roughly 1.2 million tpy kiln. So, an assumption of cost of $1/ TPY would be a reasonable estimate for S NCR costs for a 1.2 million TPY kiln

.

Captial Cost

So, for capital cost of SNCR, a reasonable estimate is :

CC (2005$) = $1 * TPY * ( 1,200,000 / TPY )^0.4

= $270 * TPY ^0.6 E.15

Fixed Cost

Fixed annual cost is relatively low, probably on the order of that for low NOx burners

Variable Cost

The single largest annual cost item for SNCR is reagent. Reference 12 , which is a recent study, included prices shown in Table 4 for SNCR reagent.

Table 4 . SNCR Reagent Cost (COSTNH3LB)

Reagent $/lb Anhydrous Ammonia 0.425 19% Ammonia 0.475
Urea 0.125

Source: PCA R&D SN3046, “Current State of Practice for Selective Non

- Catalytic Reduction (SNCR)” by Schreiber & Yonley Associates, Portland Cement Association 2008

As described in Reference 13 , ammonia SNCR in particular can be very effective on cement kilns, producing high reduction levels at moderate treatment rates. On the kilns that used ammonia, reduction rates of 50% were achieved with normalized stoichiometric ratios (NSR) of 0.50 and r eduction of about 70% with NSRs of about 1.0. According to this reference, urea is somewhat less effective, no doubt due to its higher reaction temperature. At least part of the reason for the high effectiveness of ammonia is the time and temperature cha racteristics of cement kilns. The SNCR performance results of Table 5 are from Reference 9

.

11 TECHNICAL EVALUATION PRELIMINARY DETERMINATION

, DRAFT BACT
DETERMINATIONS

, CEMEX CEMENT COMPANY BROOKSVILLE, HERNANDO COUNTY New Portland Cement Lin e DEP File N o. 0530010

- 029

- AC (PSD

- FL

- 384) Department of Environmental Protection Division of Air Reso urces Management Bureau of Air Regulation, April 3, 2007 12 PCA R&D SN3046, “Current State of Practice for Selective Non

- Catalytic Reduction (SNCR)” by Schreiber & Yonley Associates, Portland Cement Association 2008
13 Linero, A., SNCR Technology for the Cement Sector, CEMTECH Florida, 2006, OrlandoAndover Technology Partners Page 18 Table 5 . NOx reduction with SNCR (Ref. 9 )

Plant/Source Control Level (lb/t) Efficiency (%) NSR 3 European kilns 9 NA 25

– 50; 35

– 60; 42

– 72 0.6; 0.8; 1.0
Ash Grove, Seattle 2.2; 1.3 25; 55 0.5; 1.0
Hercules; PA 300 ppm ~3.0 12

– 25 NA

Suwannee American 38 2.0 33

– 50 NA

Florida Rock without tires 1.9; 2.6 47; 29 0.47; 0.35

Florida Rock with tires 2.1 34 0.12

– 0.25

Holcim

– Texas 54 (2 kilns) NA 47, 32 0.7
Skovde, Sweden 0.5

– 1.0 80

– 85 1.0

– 1.1
Slite, Sweden 1.1 80 1.0

Taiwan

- 2 kilns 1 194 ppm; 284 ppm ~2.0; 2.9 50; 46 NA

Cemex; FL

- preheater kiln 24 2.0 50 0.6

– 0.7
European Report

- achievable 1.0 80

– 85 NA

European Report

- actual operation 2.5

– 4.0 10

– 50 0.5

– 0.9

Although the performance will vary somewhat from one kiln to another, a conservative reduction and treatment rate would be around 50% reduction with an NSR of roughly 0.70. Using these to estimate cost of ammonia, the

Cost of ammonia per year (COSTNH3YR ) =
TPY *SFC*NOXMMBTU*(17/60)*0.70*COSTNH3LB E.16

SNCR may use water. Assuming (DIL) dilution at the injectors, Water use of SNCR (SNCRH2OYR) in lb/yr = TPY*SFC*NOXMMBTU*(17/60)*0.70*(1

- DIL)/DIL E.17

If aqueous ammonia (~18% by weight) is used and not diluted , DIL = 0.18. However, it is often diluted to match injector flow requirements to, say, 10%. In that case, DIL = 0.10.

A small amount of pumping power is necessary for SNCR. Assuming 40 psi pumping pressure, 90% efficient pump, and the flowrate above, annual power needs in kWhr i s estimated as :

(SNCRH2OYR/62.4) * (1/(1

- DIL))* 144 * 40/(1.3558 * 0.9 *3,600,000) = 2.10 *(10) - 5 * SNCRH2OYR* (1/(1

- DIL)) E.18Andover Technology Partners Page 19 Impacts

SNCR will reduce NOx roughly 50%.

Use of urea will have very small impact on CO 2 emissions. This effect is relatively small since it amounts to perhaps a few hundred ppm of CO 2 versus percent levels in the flue gas. Ammonia SNCR will not have an impact on CO 2 emissions.

SNCR will have no impact on SO 2 emissions.

There can be an energy benefit or disadvantage to SNCR, depending upon the concentration of the ammonia or urea. The SNCR reaction is exothermic. But, injection of ammonia or urea and water offset this effect by cooling the gas. Reference 14 showed the results of an estimate of fuel savings based upon use of ammonia SNCR and other assumption s. In this estimate it was determined that the effect could result in a reduction of fuel CO 2 in the range of 0.40

- 0.88 kg of CO 2 per metric ton of clinker, dependin g upon kiln type. However, the actual dilution rate of the ammonia in water will vary based upon the injection system, as the flowrate is usually matched to the injectors to optimize atomization. So, this effect is really not possible to gene ralize and i s nevertheless very small compared to other sources of CO 2

.

14 Arcadis, for US EPA, “Air Pollution Controls and Efficiency Improvement Measures for Cement Kilns”
Contrac t No.: EP

- C

- 04

- 023

, Project No.: RN990234.0030Andover Technology Partners Page 20 SCR

SCR is not in use at any cement facilities in the US. However, it has been installed on cement plants in Europe. SCR is capable of about 90% reduction of NOx. SCR is more expensive than S NCR. Figure 8 shows normalized cost in $/ TPY clinker versus the year of the estimate. 9 The two estimates from 1992 are far above the more current estimates. It should be noted that the estimates in 1992 dollars are from the 1994 cement kiln ACT, and was before there was any e xperience with SCR on cement kilns. The basis of the 1992 estimate was a 1991 estimate provided by a Japanese company for an SCR on a US cement kiln. Translation of the estimate entailed currency exchange estimates, as described in Reference 1. Referenc e 1 uses the same algorithms developed from the 1994 ACT on the basis of that 1991 estimate. However, in the early 1990s there was limited experie nce with SCR on coal power plants overseas and virtually no experience with SCR on coal

- fired power plants in the US. As a result, these 1992 estimates

– and others developed from the same original 1991 Japanese company estimate

– are not especially relia ble because they were based upon very limited knowledge of SCR. Recent studies are fairly consistent with one another. Reference 15 cited a European kiln study of a ~1

, 25 0, 000 tpy kiln at a cost of about $7/ TPY

. Reference 8 , produced in 2006, also had estimates of SCR capital cost in the range of $6.5

- $7.6 /TPY to retrofit dry calciner kilns, to $10.26

- $13.5/tpy to retrofit wet kilns with SCR. There is additional equipment necessary for the wet kilns that makes them more expensive to retrofit than dry kilns. The more recent estimates are in a fairly consistent range . Because the recent estimates build up on the knowledge gained from actual applicati on of SCR on numerous high

- dust sources such as coal

- fired boilers and cement kilns , they are likely more reliable than the estimates based upon the algorithms in the old ACT document.

Capital Costs

All of the estimates in the 2004 to 2006 time frame shown in Figure 8 are in the size range of about 1 million TPY to about 1.25 million TPY

. It might be reasonable to estimate Capital cost for a dry kiln at $7/ TPY at 1 million tpy. For a wet kiln, it might be reasonable to estimate the cost as $12/tpy for a kiln (or group of kilns ) in the range of 1 million tpy (the average of the two Ash Grove and TXI wet kiln “groups” that are evaluated in Reference 8 )

.

To estimate the capi tal cost of S CR for a dry kiln , a reasonable estimate is :

CC (2005 $) = $7 * TPY * ( 1,000,000/tpy )^0.4

= $1758 * TPY ^0.6 E.19

15 TECHNICAL EVALUATION PRELIMINARY DETERMINATION

, DRAFT BACT
DETERMINATIONS

, CEMEX CEMENT COMPANY BROOKSVILLE, HERNANDO COUNTY New Portland Cement Line DEP File N o. 0530010

- 029

- AC (PSD

- FL

- 384) Department of Environmental Protection Division of Air Reso urces Management Bureau of Air Regulation, April 3, 2007Andover Technology Partners Page 21 To estimate the capital cost of SCR for a wet kiln , or wet kilns , a reasonable estimate is :

CC (2005 $) = $12 * TPY * (1,000,000/tpy)^0.4 = $3014* TPY^0.6 E. 20

Fixed Costs

These are estimated in Reference 1 to be equal to:

$54,300 + 4% of Capital Costs

Since this is similar to the cost for low NOx burners, when adjusting for year dollars, we will make it the same as for burners :

$ 59,200 + 4% of Capital Costs E. 21

Variable Costs

Variable costs are comprised of:

**•** Ammonia reagent

**•** Parasitic Loads for pressure drop

**•** Catalyst Figure 8. SCR Capital Costs in $/TPY from Ref. 9Andover Technology Partners Page 22 Ammonia

- Assuming 90% reduction and 98% chemical utilization, the NSR will be 0.92, and could be less depending upon the presence of ammonia in raw materials. This results in:

Cost of ammonia per year = TPY *SFC*NOXMMBTU*(17/60)*0.92*COSTNH3LB E.22

Parasitic Loads

- Parasitic loads are mostly related to overcoming pressure drop. At the Solnhofen Plant in Germany and the Monselice plant in Italy, the pressure drop was 5 millibars or less (500 N/m2 or less) 13

, 16 At Monselice, at 1800 tpd the gas flow was 110,000 Nm2/hr (wet), or about 235,000 m3/hr at about 370 C. Assuming 75% efficient blower, this equates to an additional 44 KW of load. At 180 0 tpd, the heat input of the Monselice preheater kiln can be estimated from characteristic heat demand data as about 360 MMBtu/hr or about 380 GJ/hr.

Assuming the gas flow is directly related to the heat input, the load associated with this pressure drop c an be estimated by:

Annual Power Demand (in KW hr ) = 44* TPY * SFC/360 E.2 3

Other power demands, such as pumping power for urea or ammonia, and carrier air, tend to be small when compared to the fan demand, and would typically be less than 10% of the fan power demand.

Catalyst

- Catalyst is another variable cost. Catalyst is generally installed in layers. At Solnhofen and Monselice, six layers were available, although only three layers were filled with catalyst initially. 13

, 16 Assuming a space velocity of 2 000/hr, which is significantly below typical SV for coal plants , then the catalyst loading can be estimated by the EGFW (see Table 1 of the Emissions Memo ).

Catalyst loading = MCLINKERHR * EGFW /2000 E.2 4

A conservatively high estimate of catalyst cost is $10,000/m3, or about $285/cubic foot,

Assuming a life of 40,000 hours, which was experience in Solnhofen 13 and, then the annual catalyst usage and catalyst cost are :

Annual catalyst usage (in cubic meters) = TPY * EGFW/(2000*40,000) =1.25 (10) - 8 * TPY * EGFW E.2 5

Annual catalyst cost = TPY * EGF W * 285 / ( 2000 *40

, 000) Annual catalyst cost = 3.56 (10) - 6 * TPY * EGFW E.26

16 Ulrich Leibacher, Alvaro Linero, “High Dust SCR Solutions”, International Cement Review , December 2006Andover Technology Partners Page 23 With T P Y in short tons per year and EGFW in SCF /short ton

So, the total variable costs for SCR are:

VC = TPY * ( SFC*NOXMMBTU*(17/60)*0.92*COSTNH3LB + 44 * COSTKWH * SFC/360 + 3.56 (10) - 6 * EGFW) E.27

With COSTKWH is equal to the cost of power in $/KWhr

.

Impacts

The impact of SCR is to reduce NOx by close to 90%. A reasonable assumption is 85% NOx reduction which has proven to be effective at these levels on coal fired boilers.

Other pollutants will be affected as well. Oxidation of organics occurs to some degree

across SCR catalyst. CO 2 will not be affected. SO 2 will not be affected except that a small portion of the SO 2 (typically 1% or less) of the SO 2 will be oxidized acros s the SCR catalyst to form SO 3

.Andover Technology Partners Page 24 Limestone Wet Scrubber (LWS)

Limestone Wet Scrubbers can provide in excess of 90% SO 2 removal

– often over 95%.

Capital costs

Some capital cost estimates are shown in Table 6.

Table 6. Wet FGD Capital Costs

Kiln type Size, tph, ( TPY ) Capital Cost Estimated $/dscfm Reference

PH/PC 150 (1,200,000) $28 million $276 ** 17
PH/PC 125 (990,000) $5.5 million $65 ** 18 Any $30

- $60/dscfm $30

- $60/dscfm 19

PH/PC 170 $6.6 million $58 ** 20

PH/PC 250 (1,964,000) $13 million $77 ** 21 * installed, not including fans and ducting ** estimated using estimated dscfm, not from references

Some of the reported scaled costs were in terms of $ per dry scfm. When costs are scaled against scfm, this is generally dry scfm because moisture in the exhaust gas would otherwise have to be added to achieve saturation. So, moisture should be subtracted from the gas flow to arrive at dry scfm

. Using the average SFC f rom Table 1 of the Emissions
Memo and the EGFW from that t able and also the moisture from combustion, it is possible to estimate dry gas flow by subtracting combustion moisture from the wet exit gas flowrate. This neglects for the moment moisture from inp ut materials, which is very significant for wet kilns, but it is less important for dry kilns. According to Reference 22 the difference between gases from the feed for a wet kiln versus a dry kiln is 19,329 SCF/sh.ton clinker (1,536 lb/sh. Ton clinker) , an d this is mostly moisture. Reducing the EFGW for a wet kiln by this amount results in 89,661 SCF/sh.ton.

So, dry SCFH for a kiln can be estimated by:

(TPY/(8760*0.85)) * 89661

– moisture from combustion (for a wet kiln), and

17 Bahner, Icenhour, Lany, Barnett, Summary o f Environmental and Cost Impacts of Proposed Revisions to Portland Cement New Source Performance Standards (40CFR Part 60, subpart F), Docket Number EPA

HQ

- OAR

- 2007

- 0877

18 Miller, S., Hansen, J., “Controlling SO2 Emission” Cement International , 5/2004

19 Young, G., REVIEW OF SO2

- (HCl) SCRUBBERS, Portland Cement Association, SP129, 2002

20 REPORT IN SUPPORT OF AN APPLICATION FOR A PSD CONSTRUCTION PERMIT REVIEW FLORIDA ROCK INDUSTRIES, INC. Thompson S. Baker Cement Plant Newberry, Alachua County, Florida, N ovember 8, 2004, http://www.dep.state.fl.us/air/permitting/construction/fri/PSDREPT.pdf

21 Telephone conversation with Al Linero, FL DEP,8/22/08

22 Peray, K., The Rotary Cement Kiln,Andover Technology Partners Page 25 (TPY/(8760*0.85)) * EGFW

– mo isture from combustion (for other kilns)

Where EGFW is taken from the

Moisture from combustion can be estimated by multiplying

(TPY/(8760*0.85)) * SFC * LBMH20MMBTU * 379.63

,
Where 379.63 cubic feet is the volume of a lb mole of gas at 60 F and one atmos phere and LBMH20MMBTU is fuel dependent and is from Table 3 of the Emissions Memo

. So, equations to estimate dry SCFM are:

DSCFM = (TPY/(8760*0.85)) * (89661

– SFC * LBMH20MMBTU * 379.63 )/60 E.28 (for a wet kiln), and

DSCFM = (TPY/(8760*0.85)) * (EGFW

– SFC * LBMH20MMBTU * 379.63 )/60 E.2 9 (for dry kilns)

Using these equations to estimate dry SCFM, t he capital cost scaling in $/dry SCFM are fairly consistent for References 18

, 19

, 20 , and 21

. But, Reference 17 seems to result in a much higher cost estimate in $/dry SCFM

. The Reference 17 estimate was based upon a PSD analysis for a Lehigh Cement plant. The original source of information cited in Reference 17 was not available to determine if there was anything uniq ue about the plant in that study that made a scrubber so costly to install . A ccording to Refe rence 21 , this project included a plant expansion, which might mean other costs are incorporated into the reported scrubber cost

. On the other hand

, the other re ferences were relatively consistent

. Based upon these references, a cost in the range of $75/DSCFM (2004$) was assumed for an estimated 114,000 DSCFM plant . On this basis, assume the following algorithm:

CC (2004 $) = $ 75 *DSCFM* (114,000/DSCFM)^0.4 = $7900 * DSCFM ^0.6 CC (2005$) = $ 8650 * DSCFM^0.6 E.30

Fixed Costs

Reference 23 estimated $186,553 in annual costs for Operating, Supervisory, and
Maintenance Labor and Maintenance Materials on a 1.2 million tpy plant

. These fixed costs do tend to scale somewhat with size. Additional costs estimated were replacement parts at roughly 5% of purchased equipment cost (or, roughly 2.5% of capital cost). Also assume 4% of capital costs for taxes, insurance, etc.

FC (2008$) = ( $186,55 3/1.2 million tpy)*TPY * (1.2 million/TPY) ^0.4 + 0.04* CC

= $42*TPY^0.6 + 0.04* CC

23 Bahner, M., Icenhour., M., Laney, M., Barnett, K., memo to Docket #: EPA

- HQ

- OAR

- 2007

- 0877, Re: Summary of Environmental and Cost Impacts of Proposed Revisions to Portland Cement New Source Performance Standards (40 CFR Part 60, subpart F), May 29, 2008Andover Technology Partners Page 26 FC (2005$) = $38*TPY^0.6+ 0.04* CC E.31

Variable Costs

The kiln uses calcite (CaCO 3 ) which is the major constituent in limestone. It also consumes power and water, and it will also produce gypsum. The gypsum is a useful by product that is used to make the finished cement

.

**•** Limestone

**•** Water

**•** Power

**•** Gypsum

Limestone

- Calcite is used at a stoichiometric rate of about 1.03 moles of CaCO 3 pe r mol e of SO 2 to achieve over 9 0 % reduction , and typically 95% or so reduction

. 18 Since CaCO 3 has a molecular weight of 100 and SO 2 has a molecular weight of 64, it takes about 1.70 pounds of pure calcite to capture one pound of SO 2

. If limestone cost is $15/ton, then the limestone cost is roughly $25.5 /ton of SO 2 removed divided by the limestone purity

. A limestone of 90% calcite would then cost $28/ton of SO 2 removed

Water

- Makeup water is necessary for the scrubber to compensate for the moisture that is added to humidify the gas and is released to the atmosphere . The amount of makeup water was estimated in two ways that produced r esults that came out close to one another:

**•** comparing moisture inherent to kiln gas to the moistur e to saturate gas at roughly 140 F.

**•** using a rule of thumb for power plant scrubbers (1.4 gal/MW and 2500 SCFM per MW) and applying it to the estimated gas flow for cement kilns

For most kiln types the estimated makeup water came out to abou t 30 gallons per ton of clinker. At $0.05/1000 lb of water ($0.0004 2 /gallon), this is equal to $0.0125/ton of
clinker.

Power

- The D ynawave scrubber by Monsanto has roughly a n 18 IWC pressure drop according to Ref. 19 and a pressure drop of 8 IWC according to Ref. 24 . The pressure drop will req uire additional fan power. Reference 25 shows that to estimate fan kW,

Shaft kW = Q * dp / (367,000 * fan efficiency) E.32

Where Q is in actual cubic meters per hour dp is in mm H 2 O

24 Koskolos, B, “Unique Slurry Scrubber for Cement Kilns”, International Cem ent Journal, 2/1998

25 The Cement Plant Operations Handbook, Third Edition, International Cement Review , November 2001Andover Technology Partners Page 27 T here are about 35.5 SCF/N m 3 . And, if the exit tempera ture of the wet scrubber is 150 0 F (65 ° C), 18 inches of water pressure drop is assumed, and a fan efficiency of 75% is assumed, the equation can be shown to be equal to:

Shaft kW= (TPY/(8760*0.85)) * (EGFW/35.5) * ((273+65)/273)* 18 * 25.4 /(367,000* 0.75)

= (TPY/(8760*0. 85)) * EGFW * 5.8 (10) - 5 E.33

So, for a 150 tph precalciner kiln, the fan load would be

150 * 44,878 * 5.8 (10) - 5 = 390 kW

To account for additional power for pumping liquids and slurry and for preparing limestone, etc., add roughly 15%, or about 450 kW for 150 tph kiln, or 3 kW hr per ton of clinker.
To get annual kWhrs, multiply 3 kWh/ton time s the TPY of clinker. And, to get the cost of power, multiply by COSTKWH in $/kWhr.

Gypsum

- The final effect is the gypsum, which is useful and has a value to t he cement

making process if it offsets purchased gypsum . Gypsum values vary based upon location. A ccording to Reference 26 , this is worth about $45/ton to a cement plant since they would otherwise have to buy it

. For every 64 tons of SO 2 captured, this re sults in about 136 tons of CaSO 4 , or 172 tons of gypsum (CaSO 4 :2H 2 O)

. So, this may have the effect of producing an offsetting benefit worth about $ 120 /ton of SO 2 removed.
Using the data of T able 9 from the Emissions Memo as LBSO2 CLINKER in lbs of SO 2 per ton of clinker, and assuming 95% removal, you get

Total Variable cost = TPY * {[ LBSO2CLINKER * 0.95* ( 28

- 120 ) /2000] + EGFW * 5.8 (10) - 5 * 1.15* COSTKWH } +TPY*0.0125 = TPY* { EGFW*6.67 (10) - 5 * COSTKWH

- 4.4 (10) - 2 LBSO2CLINKER + 0.0125 } E.34 a If gypsum from the FGD cannot be used, then

= TPY*{EGFW*6.67 (10) - 5 * COSTKWH +1.3 (10) - 2 LBSO2CLINKER+ 0.0125} E.34b

Impacts
The primary impact of a scrubber is SO 2 removal

– 95% removal of SO 2 is a reasonable assumption to make considering that Reference 27 found scrubbers providing capture efficiencies ranging from about 91% to about 99% . There are other pollutants removed as well, such as mercury, PM, and heavy metals.
Water consumption and power demand are significant, and were discussed earlier

.

26 Laney, M., memo to Docket # EPA

- HQ

- OAR

- 2007

- 0877, Re: Use of Synthetic Gypsum at Holcim Plant with Wet Scrubbers, May 23, 2008

27 Bahner , M., Laney, M., Barnett, K., memo to Docket # EPA

- HQ

- OAR

- 2007

- 0877, Re: Summary of Cement Kiln Wet Scrubber and Lime Injection Design and Performance Data, May 29, 2008Andover Technology Partners Page 28 Dry Li me Injection (DLI)

Dry Lime injection (DLI) simply entails injecting dry lime from a silo into a location in the ductwork where the lime can react with the SO 2

. SO 2 released from pyritic sulfur in feed materials doesn’t get exposed to lime from the calcined feed materials because of where this SO 2 is released. Lime might be added to a location in the preheater tower or at another location to capture some of the SO 2 released from feed materials as CaSO 4

. Generally, this approach is lo w in cost but results in modest SO 2 emissions reduction

.

Capital Cost

Table 7 shows estimates of capital cost for a dry lime injection system

Table 7. Dry Lime Injection Capital Costs

Kiln type Size, tph, (TPY) Capital Cost Reference
PH/PC 125 (990,000) $160,000 18

Scaling this to estimate capital cost:

CC (2004$) = (160000/990000) * TPY * (990000/TPY)^0.4 = 40 * TPY ^ 0.6

CC (2005$) = 44 * TPY ^ 0.6 E.35

Fixed Cost

The fixed cost would be fairly low since the equipment is simple. Assume 4% of capital for taxes, insurance and overhead. Plus assume similar maintenance costs as for low NOx burners

- $59,00

.

Variable Cost

Variable cost is the cost of the lime plus power

. There is power used to transport the lime, but this is very small

.
According to Reference 18 , a stoichiometric ratio of 3:1 or 5:1 might be needed , and this provides about 50% reduction. However, this will vary quite a bit from plant to plant.

Using 4 :1, this means that you would react 4.63 tons of Ca(OH) 2 for every ton of SO 2 and capture half of that SO 2 , or 9.25 tons of hydrated lime for ea ch ton of SO 2 removed. With the hydrated lime cost at about $ 130 /ton, this equates to $ 1200 /ton of SO 2 captured or $ 600 /ton of SO 2 in the gas stream

.
Power can be estimated by assuming that a gas flow of perhaps 5% of the kiln volume is used to transport the lime. If a pressure drop of 10 IWC is assumed, this is estimated to be about 0.05 kWhr per short ton of clinker.Andover Technology Partners Page 29 No water is necessary for dry lime injection and there is no by

- product to dispose of. In fact, the by

- product, calcium sulfate, actually contributes to the final product.

Total Variable cost = TPY * [ LBSO2CLINKER * 345 /2000 = 0.17 * TPY * LBSO2CLINKER + 0.05*COSTKWH E.36

I

mpacts

The major impact is a roughly 50% reduction in SO 2 , that will in fact vary from facility to facility. There may be an impact on the kiln’s particulate control device. But this will be very site specific.Andover Technology Partners Page 30 CKD wet scrubber (Passamaquoddy Technolo gy)

Passamaquoddy Technology (PassTech) is a technology that enables SO 2 reduction by use of cement kiln dust (CKD). CKD is composed primarily of oxides of calcium, potassium, magnesium and silicon . Without a means of utilizing CKD, CKD must be disposed of. CKD was shown to be effective as an SO 2 capture reagent in the Pa ssTech technology. PassTech was in operation at the Dragon Cement wet kiln in Maine as part of a DOE sponsored program

. However, this wet kiln has since been modified to a precalciner kiln.

PassTech is primarily applicable to wet kilns because on other kiln types CKD disposal is not an issue. For dry kilns CKD can be readmitted to the kiln depending upon whether or not the kiln has an alkali bypass system and the alkali co ntent of the CKD and the resulting clinker. W ith wet kilns the CKD can increase the viscosity of the slurry too much to be readmitted to the kiln , which may require more water or less CKD

.
According to Reference 28 , the capital cost of a PassTech scrubber is roughly $10.5 million (1996$) for a 450,000 TPY kiln, or about $23.3/ton of clinker , which is significantly more expensive than a wet scrubber. According to Reference 28 , the economics of the PassTech technology are heavily impacted by the ability to receive tipping fees for accepting waste from paper mills and also to sell potassium sulfate fertilizer. Moreover, in light of the general trend toward replacement of wet process kilns with larger and more efficient precalciner kilns, expenditure of large amounts of capital on these kilns is probably unlikely. As a result, this technology is probably only a niche technology and is not examined further.

28 US DOE, “Cement Kiln Flue Gas Recovery Scrubber Project: A DOE Assessment”, DOE/NETL

2002/1163, November 201Andover Technology Partners Page 31 

### Oxidation Technologies

Oxidation technologies entail oxidizing NOx to soluble forms and then washing them

out. Lo

- Tox is one such technology offered by BOC gases to remove NOx from the gas stream. It consists of an ozone generator that introduces ozone into the e xhaust gas to oxidize NOx to water soluble species. Other approaches entail injection of hydrogen peroxide or other means. In any event, after the oxidation the soluble forms of the pollutants are then washed out of the gas in a downstream water wash or a wet scrubber.

Reference 8 developed a cost estimate of LoTox for some kilns in Texas

. C apital cost for wet kilns (unscrubbed) ranged from $10/ tpy to $20/tpy. This averaged out to $16.80/tpy for kilns in the range of 280 tpy.

For precalciner kilns with scrubbers, the cost per tpy ranged from $3/tpy for a 1,964,000 tpy kiln and from $5

- $7/tpy for roughly one million tpy kilns.

Table 8. Economics of LoTox at Texas cement kilns 8

Existing Unit Control Technology Capital

Cost per

kiln
millions Capacity per kiln

1000 tpy * Normalized

Cost $/tpy Annual

Cost
millions Effectiveness $/ton NOx Burden
Cost $/tonne
clinker
Ash Grove

#1

- wet (c} LoTOxTM $4.80 291 16 $1.4 $3,400 $5.00

Ash Grove

#2

- wet (c} LoTOxTM $5.20 291 18 $1.5 $3,500 $5.40

Ash Grove
#3

- wet (c} LoTOxTM $5.80 291 20 $1.6 $3,700 $5.70

TXI #1 & #4

– wet (b,c) LoTOxTM $5.40 273 20 $1.6 $3,300 $4.70

TXI #2 & #3

– wet (b,c) LoTOxTM $2.80 273 10 $0.5 $11,000 $10.50

TXI#5

– dry LoTOxTM $5.20 1,964 3 $2.4 $2,600 $0.90
Holcim #1

– dry LoTOxTM $6.70 987 7 $3.1 $2,400 $2.35

Holcim #2

– dry LoTOxTM $5.40 1,028 5 $2.5 $2,300 $1.90
*From US and Canadian Portland Cement Industry: Plant Information Survey, December 31, 2006

Using this information, the following algorithms might be used to estimate the cost of a LoTOX system

For scrubbed kilns:

CC(2006$) = $6 * TPY* ( 1 million/TPY)^0.4 = $1500 * TPY^0.6

CC(2005 $) = $1 460 * TPY^0.6 E.37Andover Technology Partners Page 32 For unscrubbed kilns:

CC (2006$) = $16.8 * TPY * (280000/TPY) ^0.4 = $2536 * TPY^0.6

CC (2005$) = $2 467 * TPY^0.6 E.38

Fixed Cost

4% of capital cost for taxes, insurance, overhead, etc. Other fixed costs should also be relatively low

– similar to that of a dry injection system.

Variable cost

A major variable cost is power to produce ozone . Based upon information in a table in Reference 29 , the power consumption appears to be roughly 2300 kW per ton of NOx removed. Another cost is oxygen , and then a modest cost for water

. The information in the table provided in this reference enables the total variable cost to be estimated at about $2,17 5/ton of NOx removed. So, annual variable costs would be calculated by:

VC= $2175* (0.90)* TPY*SFC*NOXLBMMBTU /2000 E.39

Impacts

LoTOX can produce about 90% NOx removal. Reference 8 assumed 85% , but the variable cost calculations are based upon 90% removal . Other pollutants that are destroyed by oxidation, such as hydrocarbons, can be reduced as well.

29 Letter from Steve Eckhardt, BOC Gases, to Christa O. Russell, Schreiber Yonley & Associates, October 4, 2006Andover Technology Partners Page 33 Combinations of Combustion and Gas Treatment Technologies

This memo covered a range of control technologies. However, the ISIS model being developed by EPA will initially incorporate only those technologies or technology combinations that are most likely to be applied. This is not to disparage any technology

o r technology combination. However, this is to initially keep the modeling options simple. The other technologies and technology combinations can be added later as experience with the model is gained, and it is envisioned that this will be done with time.

C ombustion and post combustion technologies normally can be combined. However, some combinations may be technically infeasible or may be feasible but very unlikely. An example of a situation that is feasible but unlikely is addition of SNCR or SCR with out LNB or some form of combustion controls. P ost combustion NOx control technologies would not likely be used without first installing combustion controls, since combustion controls are generally less expensive.

Some of the technologies discussed in thi s memo are feasible but have not been employed , likely due to less expensive alternatives . LoTox is an example of this. For the purpose of the model, LoTox will not be included. It may be added later. M ixing Air Technology (MAT) appears to have signifi cant application potential since it can improve performance of Mid Kiln Firing systems. However, we will not include it at this time due

to uncertainties in how much improvement results from it. Ris er Duct Firing (RDF) of tires on preheater kilns and MKF effectively provide similar benefits and are expected to have similar cost. For the purpose of the model they are being treated as similar technologies

. Low NOx Calciner (LNC) is a technology that, for the time being, will be assumed to be instal led on existing precalciner kilns. Once more information is gained on application of LNC , we may decide to include it in ISIS.

Table 9 shows technology combinations and kiln types where these combinations may apply:

Table 9. Technology Combinations and Applicable Kiln Types Technology Combination Applicable Kiln Types
LNB all LNB + MKF (coal or tires ) W, LD, PH *
LNB + SNCR all
LNB + MKF + SCR W, LD, PH *
LNB + SCR all
Wet FGD May be combined with NOx controls all

Dry Lime Injection May be combined with NOx controls PH, PC

* For the purpose of the model, RDF for PH kilns is being treated as MKFAndover Technology Partners Page 34 

### Process Modification

Slag injection (ie, Cemstar) or Fly Ash addition

Cemstar, or slag injection or power plant fly ash addition has several benefits:

**•** Reduction of NOx

**•** Reduction of heat input

**•** Increase of kiln output

**•** Reutilization of what would otherwise be a waste

**•** Reduction of CO 2 emissions per unit of clinker produced

As noted in the discussion on calculation of CO 2 emissions when using steel slag, the amount of slag used varies between about 5% and 10% of the clinker output because of the need to obtain the right mineral matter constituents in the clinker. So, 7.5% slag addition might be considered a reasonable ave rage.

Applicability

All kiln types

Capital Costs

The capital costs for CemStar are mostly associated with the material handling equipment to handle the slag, and are in the range of $1 million, as shown in Table 10 from Reference 1. 1

, 4

Table 10

. Basis for Cost Analysis of CemStar (1997 $) Capital Cost of Material Handling Equipment $500,000 Type of Kiln Wet Primary Fuels Coal and natural gas
Kiln Production Rate

Before CemStar 42 tons/hour
After CemStar 45 tons/hour Quantity of Steel Slag 3.2 tons/hour Average kiln heat requirement 5.00 MMBtu/ton Total Capital Investment $1,176,000
Annualized Cost a $220,000

a Includes cost of steel slag, royalties, and credit for the reduction in raw materials.

The $1.17 million would be $1.47 million in 2005$

No information was found for capital cost associated with fly ash addition. Assume similar capital costs for addition of fly ash.Andover Technology Partners Page 35 Fixed Costs

Because the equipment for Cemstar is very minimal, the additional fixed cost should be fairly low. Assume 4% of capital for taxes, insurance, etc. plus additional maintenance in the range of $59,200 (similar to combustion technologies).

Variable Cost Although steel slag may be used as a substitute for limestone that reduces the limestone

n ecessary for the same clinker output, the cases I have evaluated have been where limestone feed was not reduced, but output of the kiln was simply increased in proportion to the slag being added on roughly a ton

- for

- ton basis. As a result, in most cases I would not envision a reduction in limestone demand for the kiln, although a reduction in limestone used per ton of clinker due to the increased output would be experienced. There is a reduction in iron to be added from other minerals. And Reference 1 es timates the savings to be roughly $0.50

- $1.00 per ton of clinker.

Because in most cases CemStar is used to increase kiln clinker output o n close to a ton

for

- ton basis with the use of steel slag, the variable cost (or be nefit) equals the difference betw een increased clinker revenues and increased cost of using steel slag. Steel slag

cost s in the range of $5

- 15 per ton, whereas clinker cost is estimated in Reference 1 to

cost $72.59 per ton. Market conditions will also affect these prices. Average cost savings equal $62.59 per ton times increase in production. Most plants increase production by five to ten percent with the addition of the CemStar process. The Levy Company that offers CemStar is also a marketer of slag. So, the revenues they receive from selling the steel slag address any license fees. In the past when TXI owned Cemstar and often didn’t sell the slag, royalties we re imposed at approximately $16 per ton of steel slag used. 1

The variable cost will be equal to the cost for purchasing slag and for power plus the cost of any additional fuel to pyroprocess the incremental steel slag . According to Reference
1 , the costs include roughly $16/ton of slag in royalties plus the cost of slag, roughly $5

- $15 per ton, or a total cost of $21

- $31/ton. With clinker cost at $72.59/ton (2000$), and

av erage slag cost of $10/ton, savings are about $62.59 per ton. 1 If royalties of $16/ton of slag are considered, this will cause net savings to equ al about $45

- $50/ton, neglecting incremental pyroprocessing fuel. However, in most cases this license fee will not apply since Levy Company would likely sell the slag to the user. Because the steel slag is chemically similar to clinker, most of the incre mental heat needed is simply to melt and dissociate the slag . With slag t here is no energy requirement for calcining or for some of the other chemical transformations that are necessary for limestone, shale, clay and sand.

According to EIA 767 data, fl y ash costs are similar to those of steel slag (on the order of $5

- $15/ton, sometimes more and sometimes less). Fly ash would likely be used as a substitute for shale. But, depending upon the mineral composition of the fly ash, it might be used as a subs titute for other materials , such as limestone . There are no royalties for use of fly ash as a substitute material. Assume similar economics as Cemstar for variable cost, with the exception of the royalty.Andover Technology Partners Page 36 In most cases, slag is used to increase the output of the kiln. The increased output of the kiln will increase the power demand for finish milling the clinker to Portland Cement. According to Reference 25

, finish milling requires roughly 27

- 35 kW/ton, depending upon the mill types and characteristics of the clinker. Using the average and assuming roughly one ton of additional clinker per ton of slag added, that would be 31 kW/ton of slag added . Assuming that slag addition is 7.5% of kiln clinker output, the incremental power would be about 2.2 kW/ton of total clinker output . There is additional power associated with handling the slag on the front end. But, thi s is minimal compared to the additional milling demands from the increased kiln output. The incremental power for finish milling is important fo r the particular cement plant . However, finish milling is necessary for all clinker. So, assuming a constant total demand, to the extent that the finish milling load for one plant increases, it may alternatively decrease elsewhere.

Impacts

Studies have shown that Cemstar reduces CO 2 emissions and NOx emissions per ton of clinker. Testing on a precalciner kiln showed CO 2 reductions of 4% on a ton of CO 2 per ton of clinker basis . On a long

- term test on a wet kiln when firing coal the CO 2 reductions were from 4.7% to 13.9% on a ton of CO 2 per ton of clinker basis. Reductions in NOx emissions were even greater at about 10%

- 44%, depending upon the feed mix

– 30%

- 44% at the optimal feed mix depending upon slag addition rate. At a wet kiln when firing coal, a 24% reduction in NOx was observed. 1

, 30

CO 2 reduction (on a ton/ton of clinker basis) can be assumed to be about equal to the percent of slag added because the slag is contributing to higher output on roughly a ton for ton basis without additional cal cination and with minimal additional heat demand. So, if 7.5% of rated clinker output without slag is the average percentage for slag addition, that is roughly the average for CO 2 reduction on a ton of CO 2 per ton of slag basis. This is roughly consisten t with the results of testing. By and large, operators tend to use the slag to increase output of the kiln rather than to reduce the limestone being added or the fuel use.

NOx emission reductions will vary by kiln. But, a NOx reduction of about 30% on a lb/ton of clinker basis should be reasonable for most kilns.

There will be a slight increase in power demand on the kiln since the slag requires some additional material handling

.
Finally, questions have arisen about the possibility of Cr +6 release from steel slag. Studies have shown that Cr is generally present in the trivalent form , rather than the more mobile and toxic hexavalent form

, in steel slag

. 31

30 Staudt, J., “Steelmaking Slag as Recovered Mineral Components (RMC) in Portland Cement Production”, for National Slag Association, December 12, 2007

31 Chaurand, et. Al., “Environmental impacts of steel slag reused in road construction: A crystallographic and molecular (XANES) approach ”, Journal of Hazardous Materials

, HAZMAT

- 5460 , Elsevier, 2006, http://www2.ademe.fr/theses

- fichiers/604_ChaurandJHM.pdf , viewed March 9, 2009Andover Technology Partners Page 37 Conversion from Wet to Dry

Conversion of an existing Wet kiln to a preheater/precalci ner kiln is estimated to be between $50/tpy and $100/tpy in capital by Reference 32 . This is likely in 1999$. A more recent study estimated costs in the range of $130/tpy for TXI’s Midlothian Plant wet kilns and about $190/tpy for the Ash Grove Midlothian plant wet kilns. 8 These costs start to approach the cost of a new plant of around $200/tpy. 33 However, in that particular study , the kilns were assumed to be replaced with a single precalciner kiln that was of the same size. So, the existing kilns were not modified, but replaced. In practice, it would make more sense to replace those small, wet kilns with a precalciner with much more capacity th an the multiple wet kilns altogether. 8 So, the $130

- $180/tpy cost may be artificially high due to the constraints of that study. Using a value of $ 75 /tpy (1999$) for the cost of conversion of a single existing wet kiln to a shor ter kiln and addition of a precalciner with a median size of about 300,000 tpy from the Cap+Trade workbook, would provide the formula below.

Applicability

Wet kilns only

Capital Cost :

CC(1999 $) = $75 * TPY * (300,000/TPY) ^ 0.4 = $ 11,638 * TPY^0.6

CC(200 5$) = $ 14,442 * TPY^0.6 E.40

Where TPY is the annual clinker capacity in short tons per year of the final kiln size (if expanded.

Fixed Costs

The increase in fixed costs would partly be additional taxes and insurance, at 4% of capital.

Another effect would be on labor. According to Reference 34 productivity at dry kilns in 2006 was 3.15 tons per employee hour and at wet kilns it was 2.15 tons per employee hour.

32 Energy Efficiency Improvement Opportunities for Cement Making An ENERGY STAR Guide for Energy and Plant Managers, Lawrence Berkel ey National Laboratory, January 2004.

33 E

- mail from Greg Mayes, TXI, June 2, 2008 34 Portland Cement Association, U.S. AND CANADIAN LABOR

- ENERGY INPUT SURVEY , 2006,
ER374Andover Technology Partners Page 38 Variable Costs

Variable costs would entail a significant reduction in fuel d emand and a likely increase in power use. Reference 32 showed roughly a 9 kW/ton clinker increase in electric load. This is because dry materials are harder to g rind.

Impacts

Specific Fuel consumption would drop, from an estimated 6.38 MMBtu per short ton of clinker to 4.05 MMBtu per short ton of clinker, or a roughly 2.3 MMBtu per short ton reduction in fuel requirement.

Capaci ty c ould increase since the thermal demand on the kiln per ton of c linker is much lower for a precalciner.

Overall, all emissions would drop. CO 2 emissions would drop due to the reduction in fuel demand. NOx and SO 2 emissions would both to emissions levels typical of a precalciner, which h as lower emissions than a wet kiln.

Water consumption would also drop. Moisture added to the materials of a wet kiln amount to about 0.3

- 0.4 tons per ton of raw material, or about 0.6 tons of water per short ton of clinker , assuming about 1.7 tons of raw material per ton of clinker

. 35

35 Peray, The Rotary Cement Kiln , Chemical Publish ing Company, New York, 1986 , pg 6Andover Technology Partners Page 39 Conversion from Wet to Semi

- Wet

Conversion from a Wet kiln to Semi

- Wet using filter presses to reduce moisture consumption is described in Reference 36 to cost about $1.6/tpy (1996$).

Applicability

Wet kilns only

Capital Cost :

Using $1.6/tpy and an average kiln size of about 280 tpy.

CC(199 6$) = $1.6 * TPY * (280,000/TPY) ^ 0.4 = $241 * TPY^0.6

CC(2005$) = $306 * TPY^0.6 E.41

Fixed Costs

The increase in fixed costs would partly be additional taxes and insurance, at 4% of capital.

Variable Costs

Variable costs would entail a significant reduction in fuel demand and a likely increase in power use. Reference 36 showed roughly a 3

- 5 kW/ton clinker increase in electric load and a reduction in heat input of 1 MMBtu/ton.

Impacts

NOx, SO 2 and CO 2 emissions would all drop as a result of the reduction in heat input. Reductions in NOx and combustion CO 2 can be directly related to the reduction in heat input. SO 2 emissions reduction is more difficult to estimate because SO 2 emissions also result from materials.

36 Energy Efficiency Improvement Opportunities for Cement Making An ENERGY STAR Guide for Energy and Plant Managers, Lawrence Berkeley National Laboratory, January 2004.Andover Technology Partners Page 40 Conversion from Dry to Multi

- Stage Preheater

According to Reference 32 , the cost of upgrading a long dry kiln to a multi

- stage preheater kiln is about $36

- $37/tpy (1993$) for conversion to a multi

- stage preheater, while addition of a suspension preheater would be in the range of $25/ tpy (1994$).

Applicability

Long Dry Kilns

Capital cost

From the Cap+Trade worksheet, the median long dry kiln is about 250,000 tpy. Using this as the basis to estimate capital cost,

CC (1993$) = $36.5 * TPY * (250000/TPY)^0.4 = $5256 * TPY ^ 0.6

CC (2005$) = $ 7114 * TPY ^ 0.6 E.42

Fixed Cost

This will largely be the insurance and taxes, about 4% of capital cost.

Variable Cost

Fuel Costs will drop due to the higher efficiencies of preheater kilns. This is determined by the change in the Specific Fu el Consumption associated with dry and preheater kilns.

Impacts

NOx, CO 2 , and SO 2 will be reduced because preheater kilns have significantly lower emissions of each of these. This will result in change in SFC as well as change in the specific emissions ra tes for the kiln type.Andover Technology Partners Page 41 Conversion from Long Dry to Preheater Precalciner

Applicability

Long Dry Kilns

Capital Cost

Conversion of a long dry kiln to a preheater/precalciner is estimated to cost in the range of $21

- $26/tpy (1993$). 32 This is actually lower than the reported cost in Reference 32

to convert a long dry kiln to a preheater kiln, which is contrary to what is expected. As a result, I recommend that a higher number be used, perhaps $45/tpy.

CC (1993$) = $45 * TPY * (250000/TPY)^0.4 = $6492 * TPY ^ 0.6

CC (2005$) = $8787 * TPY ^ 0.6 E. 43

Fixed Cost

This will largely be the insurance and taxes, about 4% of capital cost.

Variable Cost

Fuel Costs will drop due to the higher efficiencies of precalciner kilns. This is determined by the change in the Specific Fuel Consumption.

Impacts

NOx, CO 2 , and SO 2 will be affected by the change in SFC as well as change in the specific emissions rates for the kiln type.Andover Technology Partners Page 42 Conversion from Preheater to Precalciner

This primarily entails addition of a calciner and associated ductwork and burner piping.
It may also entail an additional preheater stage. As such, it would be expected to be much less expensive than conversion of a long dry kiln to a precalciner. This will generally have the effect of increasing capacity, reducing specific fuel consumption and reducing some emissions.

Applicability

Preheater only

Capital Cost

Reference 32 assumes a cost of around $15/ton of clinker based upon two data points, $28/TPY i n 1994 and $8.5/TPY in 1996). The median preheater kiln size in the Cap+Trade workbook is 414,000 TPY. Using these numbers,

CC (1995$) = $15 * TPY * (414000/TPY)^0.4 = $2648 * TPY ^ 0.6

CC (2005$) = $3123 * TPY ^ 0.6 E.44

Fixed Cost

This will largely be the insurance and taxes, about 4% of capital cost.

Variable Cost

Specific fuel consumption will drop due to the higher efficiencies of precalciner kilns. This is determined by the change in the Specific Fuel Consumption. Also, capacity will be increas ed. Reference 32 gave examples of capacity increases from 58% to about 80%. An average capacity increase might be 65%.

Impacts

NOx, CO 2 , and SO 2 will be affected by the change in SFC as well as change in the specific emissions rates for the kiln type.

Note:

This may seem like an easy and inexpensive a way to increase capacity. However, there are other issues to consider, such as the adequacy of l imestone reserves, the triggering of harsher environmental requirements, and how much of a boost in capacity will occur versus other capacity expansion options.Andover Technology Partners Page 43 Low Pressure Drop Cyclones

Cyclones are a basic component of most preheating systems. Newer cyclones with lower pressure losses will reduce gas pressure drop and load on the exhaust gas system. For most olker kilns this amounts to 0.6

- 1.0 kWh/ton of clinker, but examples of kiln s where 4 kWh/ton were saved exist. 32 It may be beneficial to also add an in

- line raw mill to address possible increases in dust loading carried over from the preheater tower.

Applicability

Preheater kilns

Capital Cost

Reference 32 indicates a capital cost of $2.7/TPY for a low pressure drop cyclone system.

Fixed Cost

None, other than 4% for additional taxes, insurance, etc.

Variable cost

Reduction of load will reduce v ariable cost of operating the plant by about $0.03/ton assuming 0.8kWh/ton saving and electric cost of $35/MWhr.

Impacts

Reduced power demand and possible increase in dust carryover from preheater tower.Andover Technology Partners Page 44 New kiln or Expansion

Generally, new kilns are ins talled as part of facility expansions or upgrades, as new kilns are usually larger in capacity than older kilns that they replace. Or, new kilns can be installed as part of new plants. Most new kilns are part expansion of existing sites. But,

some are new, green

- field facilities. According to Cement Americas:

Significant increases in clinker capacity are expected to materialize during 2008

— 2012. The U.S. cement industry has announced plans to increase clinker capacity by nearly 25 million metric ton s between 2007 and 2012. The aggressive capacity expansion reflects a $5.9 billion investment, which will increase capacity 27% compared to 2006 U.S. clinker capacity. The expansion spans seven greenfield sites and expansion of 18 existing facilities 37

Th us, the “blended” cost of all of these facilities is about $236/ tonne or about $213/short

ton , which is consistent with information from Reference 33 . Reference 25 provides some insight to the difference in cost between expansions and green

- field plants.

New green

- fie l d ce m ent p l an t s cost $ 2 0 0

- 300 pe r t onne of a n n u a l prod u c t io n ,
w hi le k iln ex pan s i ons co s t $8 0

- 150 d e p en d ing u po n th e u sa bl e excess c ap aci t y o f

ex i sti n g a n c ill ary e qui p m en t and s t orage

. Per mitt i n g of h eavy i n dus t r i al faci lit ies b eco m es ev er more diff ic ul t a nd ex p e n s i ve, so t h a t co n si d era bl e inta n g ibl e value
may at t ac h t o an ex i s t i n g o p era t io n a nd it s m ark et , ev e n i f th e e qui pm e nt is

a nt i qu a t ed a nd i n eff i cient

.

Reference 25 provided the estimate in Table 11 for a “typical” project to add 1.5 million tonne per year to an existing plant.

Table 11 . “Typical” 1.5 million tonne/year expansion to an existing plant (Ref 25 )

Equipment Qua r ry equipment US$3,000,000 Raw milling & blending 13,000,000

Kiln

, preheater & cooler 18,000,000

Coal s y s tem & storage 5,000

, 000 Clinker storage 3

, 000,000 Cement milling 9,000

, 000 Cement storage and pac k ing 3,000,000

Electrical & cont r ol 9.000,000

Sub

- total $63,000,000
Civil, structural & erection $38

, 000,000 Engineeri n g, construct i o n m a nagement, f r eight,

co mmis s ioning $19

, 000,000

Owner's c apitalised cost $5

, 000,000

Construction interest $ 14

, 000

, 000 Spares $4,000,000
Contingency (5%) $7,000,000
Total project cost $150,000,000

37 Cement Americas: downloaded at http://cementamericas.com/mag/cement_forecast_0101/Andover Technology Partners Page 45 The choice between expansion of an existing facility to fulfill growing demand and Greenfield is complex. If cost alone were used, expansion would most often be chosen over Greenfield

. However, the re are other factors. The three most important decision criteria

– starting with the most important

- are:

1. Environmental Factors

– The attainment status of a location or the location relative to a non

- attainment area is very important. If a facility is in an oz one or fine PM non

- attainment area (or upwind of one) , expansion is far more difficult than if it is located in an attainment area. Expansion would certainly be limited by Prevention of Significant Deterioration (PSD) impacts. If no existing plant servin g a market is in an attainment area , and there is a Greenfield site available in an attainment area that can serve the market, Greenfield development may be more attractive than expansion. If there are no sites

– existing or Greenfield

– without non

- attai nment issues, then importing may be the best way to meet increased market demand. 2. Available mineral deposits

– A rule of thumb is that a site needs 100 years of limestone to be viable. Keeping in mind that many existing plants were put in place 40 or mor e years ago with smaller kilns, some sites may not be suitable for expanding with much more capacity due to inadequate limestone reserves

. 3. Qualified labor pool

– Modern cement plants are sophisticated. As a result, the labor pool needs to be able to suppl y workers that can operate and service the equipment and manage the overall plant . Limited labor pools may favor expansion of existing facilities over Greenfield plants that will require addition of more people.

Addressing the choice between expansion and g reenfield will be di fficult in the ISIS model. However, a suggested approach follows. EPA probably knows the attainment status of the county where each kiln is

– or the kiln’s location relative to non

- attainm ent

areas . So, the first effect can be addressed. USGS may have information on available limestone deposits. This information, if available, will make it possible to rule out some sites for expansion. If available, it will also make it possible to iden tify potential

g reenfield sites. The third factor is harder to address . But, perhaps it may be unnecessary to do so. A suggested decision tree is shown in Figure 9 to help with the choice between expansion and g reenfield

. The decision tree assumes that it may be possible (albeit, difficult) to expand a facility that is within a non

- attainment area. However, if that is considered too difficult, the decision to meet demand with increased imports to the region may be an alternative

. Another option a ceme nt company might consider is adding a terminal or other options that could provide for demand from outside the immediate area.Andover Technology Partners Page 46 Figure 9. Suggested decision tree for expansion of existing facility or Greenfield

.

If limestone information isn’t available, a nother way to approach the decision is to see if there are any plants in a market that are in attainment areas, and these would always be expanded first. If none were in attainment areas, then build a Greenfield plant in an attainment area within the market region. If there are no attainment areas within a market region, then the solution would be to increase imports to the market. Expansion might occur then in an adjacent market.

Capital Costs

So, depending up on the circumstances, green

- field plan t s cost in the range of $180

- $270/short ton (2001$), while expansions can be performed between $72

- $135/short ton (2001$). Selecting the Mid

- Points,

Green

- field CC(2001$) = $225/short ton
Green

- field CC(2005 $) = $277/short ton E.45

Expansions CC(2001$) = $105/short ton Expansions CC(2005$) = $130/short ton E.46 Is existing facility in/near non

- attainment area?

Is there a Greenfield site available to serve market that is outside

non

- attainment and has adequate adequate limestone? Expand facility (3 years) Does existing facility have adequate mineral reserves?

no yes yes no

no

yes yes no

Does existing facility have adequate mineral reserves?

Expand existing facility within PSD limits (6 years) Build Greenfield (5 years)

No additional capacity

Or possibly no expansionAndover Technology Partners Page 47 However, it should be recognized that actual costs could vary s ubstantially from these numbers

.

Fixed Costs

Fixed costs would be roughly 4% of capita l for taxes, insurance, etc., plus the costs to staff and operate the plant. As a first cut at staffing, use 3.15 tons of clinker per employee hour (average for dry plants in 2006 PCA survey). However, a modern plant would likely be more productive than t his. A 20% greater productivity than average for dry plants, assuming a modern plant, would yield about 3.8 tons per employee hour. In fact, 20% may be conservative.

Variable Costs

Variable costs would be consistent with state

- of

- the

- art technology since new technology would typically be installed . Assume SFC and energy consumption consistent with the most efficient kilns.

Impacts

Expansions would generally be with modern, more efficient, and lower emitting technology. NOx, SO 2 emissions would be consis tent with recent BACT determinations. CO 2 emissions would be consistent with state of the art as well.Andover Technology Partners Page 48 Other Energy Saving Methods

Reference 32 identified numerous energy efficiency improvement opportunities for

cemen t production plants . In addition to kiln process modifications to improve thermal efficiency that were discussed earl ier , there are opportunities facility

- wide to improve energy efficiency. Some of these are discussed below:

High Efficiency Motors

– replacing older motors with higher efficiency electric motors could reduce electric load from 3%

- 8%, and this is estimate d to cost in the range o f $0.2 per annual ton of cement. Assuming that this was in 1993$, in 2005$ this would be $0.27 pr annual ton of cement.

Use of adjustable speed drives (ASD)

– Instead of using single

- speed motors, ASDs permit the speed of the moto r to be varied to match the load for more efficient operation. In this manner pumps, fans and mechanical drives can be operated more efficiently.
R eference 32 c ites that potential savings are at 15%

- 44% of the installed power, or roughly 7 KW per ton of cement

. Costs to u pgrade to ASDs vary, but are estimated in a

range around $0.9 per annual ton of cement (1993 $), or $1.2 2/annual ton of cement in 2005$.

Compre ssed Air Systems

– Compressed air system efficiency can be improved substantially. It is often overlooked because it is a small part of the total plant load. Reference 32 cites numerous maintenance activities that can improve efficiency; but, there isn’t good quantitative information on the cost and benefit. However, Reference 32 cites that air leakage is another source of inefficiency, and that typical air leakage is between 20% and 50% of total production capacity. Reference states that overall a 20% reduction in annual compressor energy consumption is projected for fixing leaks.

Possible improvement in electric load Overall, each of the above points to a possible improvement in electric load for cement plants. According to Reference 38

, electric loads range from about 17

- 25 kW/ton, with dry kilns generally at the higher end of the range due to the higher grinding energy needed.

It also seems reasonable that the greatest improvement in efficiency is likely from older kiln s that have olde r equipment. A reasonable approach to estimating this might entail assuming a level of potential improvement that is associated with the age of the plant. The cost to achieve the improvement would then be associated with the amount of improvement, to tha t larger improvements cost more money. At this point, am contemplating an approach that would entail, for each kiln estimates of the potential reduction in electricity demand and estimates of capital cost or maintenance cost for that reduction in demand, each of which increase based upon the age of the facility.

For high efficiency motor or ASD savings, I suggest the following:

38 “I nnovations in Portland Cement Manufacturing”, Portland Cement Association, 2004Andover Technology Partners Page 49 **•** 2 kW/ton of cl inker in savings for every $0.27 /annual ton of clinker (2005 $) in investment in new motors , with the maximum savings on a sliding scale based upon age of the plant. New plants would have new motors, so the savings would be nil. But, perhaps plants 30 years old or older could get up to the maximum benefit.

**•** For ASD’s I suggest a similar approach

– Up to 7 kW/ton of clinker for every $1.2 0/annual ton of clinker (1993$) in capital investment, with the maximum benefit and maximum cost on a sliding scale based upon age of the plant. New plants would have new equipment, so the savings and cost would be nil. But,

per haps plants 30 years old or older could get up to the maximum benefit for the maximum cost

.

**•** I also suggest that you might not want to be able to do both motor upgrade and ASD upgrade

– you could pick one or the other. The reason is that if you replace th e largest motors (such as fans, mills and pumps) with ASDs, you will also be replacing the motors as well. So, the motor replacement option is a less costly approach to get electric savings.

For compressors, according to Reference 32 , the bigg est benefits are li kely from increased maintenance and also from newer controls , and the bigge st benefit is from older plants that have less efficient equipment and more leak s

– the biggest source of inefficiency. The activities identified maintenance measures to improve efficiency and reduce leaks . Improved controls were also identified. Unfortunately, Reference 32 did not quantify the amount of energy that could be saved or at what cost. So we will need to get some more information before quantifying it. However, I suggest a similar approach as the one I suggested for motors

, where the newest plants have no benefit possible and the older plants have the maximum potential benefit.Andover Technology Partners Page 50 Appendix List of Terms
Term Definition
CAPACITYHR CASUB

CC CO2FUEL CO2CLINKER COSTKWH COSTNH3LB COSTNH3YR
DLI DSCFM EGFW

FC
FF i H LBCO2MMBTU LBMCO2MMBTU LBH20MMBTU LBMH20MMBTU LBNOXHR LBSO2CLINKER
LNB LWS
MAT MCLINKER MCLINKERHR
MKF MLIMESTONE MLIMESTONEHR MSLAG MSLAGHR NOXMMBTU PEC PURLIMESTONE PSD Q SCC SCR SFC SCFH SNCR TDFPC
TPY VC Clinker capacity of the kiln in tons per hour Calcium Substitution Fraction

– fraction of total calcium from material that does not need to be calcined Capital Cost Fuel CO 2 in pounds that is released from fuel combustion CO 2 produced by calcination during clinker production Cost of Power in $/KWhr
Cost of am monia in $ per pound Cost of ammonia in $ per year Dry Lime Injection Dry standard cubic feet per minute Exhaust Gas Flowrate (wet) in standard cubic feet per short ton of clinker

Fixed Cost Fuel Fraction of i th component of fuel on a Btu basis Burner hea t duty in MM Btu/hr Pounds (mass) of CO2 per MMBtu of fuel input Pound moles of CO2 per MMBtu of fuel input Pounds (mass) of H2O per MMBtu of fuel Pound moles of H2O per MMBtu of fuel Pounds (mass) of NOx per hour Lbs of SO 2 per ton of clinker Low NOx Burn er Limestone Wet Scrubber Mixing Air Technology Mass of clinker in tons Mass rate of clinker in tons per hour Mid Kiln Firing Mass of limestone, tons Mass rate of limestone, tons/hr Mass of slag, tons Mass rate of slag, tons/hr NOx lb/MMBtu for the kiln Purchased Equipment Cost Purity of the limestone

– fraction as CaCO 3 Prevention of Significant Deterioration Flow in actual cubic meters per hour Staged Combustion Calciner Selective Catalytic Reduction Specific Fuel Consumption in MMBtu per ton of clinker Standard Cubic Feet per Hour of gas Selective Non

- Catalytic Reduction Tire Derived Fuel Precalciner Tons per Year of clinker Variable Cost