### IPM Model – Revisions to Cost a nd Performance for APC Technologies

Dry Sorbent Injection Cost Development Methodology

FINAL

August 2010
Project 12301-007
Perrin Quarles Associates, Inc.

Prepared by

55 East Monroe Street • Ch icago, IL 60603 USA • 312-269-2000LEGAL NOTICE

This analysis (“Deliverable”) was prepared by Sargent & Lundy, L.L.C. ("S&L"), expressly for the sole use of Perrin Quarles Associates, Inc. ("Client") in accordance with the agreement between S&L and Client. This Deliverable was prepared using the degr ee of skill and care ordinarily exercised by engineers practicing under similar circumstances. Client acknowledges: (1) S&L prepared this Deliverable subject to the particular scope limitations, budgetary and time constraints, and business objectives of the Client; (2) information and data provided by others may not have been independently verified by S&L; and (3) the information and data contained in this Deliverable are time sensitive and changes in the data, applicable codes, standards, and acceptable engineering practices may invalidate the findings of this Deliverable. Any use or reliance upon this Deliverable by third parties shall be at their sole risk.

This work was funded and reviewed by the U.S. Environmental Protection Agency under the supervision of William A. Stevens, Senior Advisor – Power Technologies. Additional input and review was provided by Dr. Jim Staudt, President of Andover Technology Partners.Project No. 12301-007 IPM Model – Revisions to Cost and Performance for APC Technologies August 20, 2010 

### Dry Sorbent Injection Cost De velopment Methodology – Final

Page 3 

### Technology Description Dry sorbent injection (DSI) is a viable technology for moderate SO 2 reduction on coal fired boilers. Demonstrations and r ecent utility testing have shown SO 2 removals greater than 80% for systems using sodium based sorbents. The most common sodium based sorbent is Trona.

The level of removal for Trona can vary from 0 to 90% depending on the Normalized Stoichiometric Ratio (NSR) and particulat e capture device. NS R is defined as:

The target removal efficiency is a requiremen t from the utility and is independent of unit size. The costs for a DSI system are primaril y dependant on sorbent fe ed rate which is a function of NSR and SO 2 mass feed rate per hour. Ther efore, the cost estimation was based on sorbent feed ra te and not on unit size.

The sorbent solids can be collected in either an ESP or a baghouse. Baghouses generally achieve greater SO 2 removal efficiencies than ESPs by virtue of the filter cake on the bags, which allows for longer reaction time between the sorbent solids and the flue gas. For a given removal effi ciency with Trona, the NSR is reduced when a baghouse is used for particulate capture.

The dry sorbent capture ability is also a functi on of particle surface area. To increase the particle surface area, the sorb ent must be heated. Heati ng the solids produ ces micropores on the particle surface which greatly improve the sulfur capture ability. For Trona, the sorbent should be injected into flue ga s above 275°F to maximize the micropore structure. However, if the flue gas is too hot (greater than 800°F), the solids may sinter and surface area is reduced.

Another way to increase surface area is to mechanically reduce the particle size by grinding the sorbent. Typical Trona is delivered unmilled. The ore is ground such that the unmilled product has an average size around 30 μ m. Commercial testing has shown that the reactivity of the Trona can be incr eased when the sorbent is ground to less than 30 μ m. In the cost estimati ng methodology, the Trona is always delivered in the unmilled state. To mill the Trona, in-line mills are continuously used during the Trona injection process. Therefore, the delivere d cost of the Trona will not change, only the reactivity and usage changes as the Trona is milled.Project No. 12301-007 IPM Model – Revisions to Cost and Performance for APC Technologies August 20, 2010 

### Dry Sorbent Injection Cost De velopment Methodology – Final

Page 4 Ultimately, the NSR required for a given removal is a function of Trona particle size and particulate capture equi pment. Either as delivered Trona (around 30 μ m average size) or in-line milled Trona (around 15 μ m average size) can be chosen for injection in the cost program. The average Trona particle size and the type of particulat e removal both contribute to the predic ted Trona feed rate.



### Establishment of Cost Basis For the wet or SDA FGD systems, the sulfur removal is generally specified at the maximum achievable level. W ith those systems, costs are primarily a function of plant size and sulfur rate. However, the DSI systems are quite different. The major cost for the DSI system is the sorbent itself. The sorb ent feed rate is a f unction of su lfur rate, particulate collection device, a nd removal efficiency. To account for all of the variables, the capital cost was established based on a sorb ent feed rate. The sorbent feed rate is calculated from user input variables. Cost data for several DSI systems was reviewed and a relationship was de veloped for the capital costs of the system on a sorbent feed rate basis.



### Methodology Inputs Several input variables are required in order to predict fu ture retrofit costs. The sulfur feed rate and NSR are the major variables fo r the cost estimate. The NSR is a function of:

• Removal efficiency;

• Trona particle size; and

• Particulate capture device.

A retrofit factor that equates to difficulty in construction of the system must be defined. The gross unit size and gross heat rate will fa ctor into the amount of sulfur generated.

Based on commercial testing, remo val efficiencies with DSI ar e limited by the particulate capture device employed. Wh en the sorbent is captured in an ESP, a 40 to 50% SO 2 removal is typically achieved without an increase in particulate emissions. A higher efficiency (70 – 75%) is generally achieved with a baghouse. The DSI technology should not be applied to fuels with a sulf ur content of greater than 2 lb SO 2 /MMBtu.Project No. 12301-007 IPM Model – Revisions to Cost and Performance for APC Technologies August 20, 2010 

### Dry Sorbent Injection Cost De velopment Methodology – Final

Page 5 The equations provided in the cost methodology spreadsheet a llow the user to input the required removal efficiency, within the limits of the t echnology. To simplify the correlation, the removal with an ESP should be set at 50% and 70% with a baghouse. The simplified sorbent NSR would then be:

For an ESP at the target 50% removal: Unmilled Trona NSR = 2.85 Milled Trona NSR = 1.40

For a baghouse at the target 70% removal: Unmilled Trona NSR = 2.00 Milled Trona NSR = 1.55

The correlation could be further simplified by assuming that only milled Trona is used. The current trend in the industry is to use in-line milling of the Trona to improve the utilization. For a minor increas e in capital, the milling can greatly reduce the variable operating expenses. It is recommended that only milled Trona be considered in the simplified model.

Outputs Total Project Costs (TPC) First the base installed cost for the complete DSI system is calculated (BM). The base installed cost includes:

• All equipment;

• Installation;

• Buildings;

• Foundations;

• Electrical; and

• Average retrofit difficulty.

The base module cost is adjusted by the sel ection of in-line milling equipment. The base installed cost is then increased by:

• Engineering and c onstruction management costs at 5% of the BM cost;

• Labor adjustment for 6 x 10 hour shift pr emium, per diem, etc., at 5% of the BM cost; and

• Contractor profit and fees at 5% of the BM cost.Project No. 12301-007 IPM Model – Revisions to Cost and Performance for APC Technologies August 20, 2010 

### Dry Sorbent Injection Cost De velopment Methodology – Final

Page 6 A capital, engineering, and cons truction cost subtotal (CECC) is established as the sum of the BM and the additional engi neering and construction fees.

Additional costs and financi ng expenditures for the project are computed based on the CECC. Financing and additi onal project costs include:

• Owner’s home office costs (owner’s engineering, management, and procurement) at 5% of the CECC; and

• Allowance for Funds Used During Construction (A FUDC) at 0% of the CECC and owner’s costs as these projects are expected to be completed in less than a year.

The total project cost is based on a multiple lump sum contract approach. Should a turnkey engineering procurem ent construction (EPC) contra ct be executed, the total project cost could be 10 to 15% higher than what is currently estimated.

Escalation is not included in the estimate. The total project cost (TPC) is the sum of the CECC and the additional costs and financing expenditures.

Fixed O&M (FOM) The fixed operating and main tenance (O&M) cost is a function of the additional operations staff (FOMO), main tenance labor and materials (FOMM), and administrative labor (FOMA) associated with the DSI inst allation. The FOM is the sum of the FOMO, FOMM, and FOMA.

The following factors and assumptions underlie calc ulations of the FOM:

• All of the FOM costs were tabulated on a per kilowatt-year (kW-yr) basis.

• In general, 2 additional operators are required for a DSI system. The FOMO was based on the numb er of additional opera tions staff required.

• The fixed maintenance materi als and labor is a direct function of the process capital cost (BM).

• The administrative labor is a fu nction of the FOMO and FOMM.Project No. 12301-007 IPM Model – Revisions to Cost and Performance for APC Technologies August 20, 2010 

### Dry Sorbent Injection Cost De velopment Methodology – Final

Page 7 Variable O&M (VOM) Variable O&M is a function of:

• Reagent use and unit costs;

• Waste production and unit disposal costs; and

• Additional power require d and unit power cost.

The following factors and assumptions underlie calc ulations of the VOM:

• All of the VOM costs were tabulated on a per megawatt- hour (MWh) basis.

• The reagent usage is a function of NSR and SO 2 feed rate. The gross unit size and gross heat rate factor multiplied by the SO 2 rate determine the SO 2 feed rate. The estimated NSR is a function of removal efficien cy required. The basis for the total reagent ra te is a Trona purity of 98%.

• The waste generation rate is a function of the Trona fe ed rate and is adjusted for the excess sorbent fed. The wast e generation ra te is based on reaction products of Na 2 SO 4 and unreacted dr y sorbent as Na 2 CO 3
.

• With the addition of a sodium sorb ent, any fly ash produced must be landfilled. Typical ash contents for each fuel are used to calculate a total fly ash production rate. The fly ash producti on is added to the sorbent waste to account for a total waste st ream in the O&M analysis.

• The additional power required includes air blowers for the injection system, drying equipment for the transport air, and in-line Trona milling equipment as needed.

Input options are provided for the user to adjust the variable O&M costs per unit. Average default values are included in the ba se estimate. The variable O&M costs per unit options are:

• Trona cost in $/ton;

• Waste disposal costs in $/ton;

• Auxiliary power cost in $/kWh;

• Operating labor rate (including all be nefits) in $/hr.Project No. 12301-007 IPM Model – Revisions to Cost and Performance for APC Technologies August 20, 2010 

### Dry Sorbent Injection Cost De velopment Methodology – Final

Page 8 The variables that contribute to the overall VOM are:

VOMR = Variable O&M costs for trona reagent VOMW = Variable O&M costs for waste disposal VOMP = Variable O&M costs for additional auxiliary power

The total VOM is the sum of VOMR, VOMW, and VOMP. Table 1 co ntains an example of the complete capital and O&M cost estimate worksheet.Project No. 12301-007IPM Model – Revisions toCost and Performance forAPC TechnologiesAugust 20, 2010Dry Sorbent Injection Cost Development Methodology – FinalPage 9Table 1. Example Complete Cost Estimate for a DSI System(Costs are all based on 2009 dollars)Project No. 12301-007IPM Model – Revisions toCost and Performance forAPC TechnologiesAugust 20, 2010Dry Sorbent Injection Cost Development Methodology – FinalPage 10