### IPM Model

– Updates to Cost and Performance for APC Technologies

Dry Sorbent Injection for SO 2 

### Control Cost Development Methodology

Final

March 2013

Project 12847

- 002

Systems Research and Applications Corporation

Prepared by

55 East Monroe St reet • Chicago, 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 Systems Research and Applications Corporation ("Client") in accordance with th e agreement

between S&L and Client. This Deliverable was prepared using the degree 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 s ensitive 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 fu nded by the U.S. Environmental Protection Agency and reviewed by William A. Stevens,

Senior Advisor

– Power Technologies

.IPM Model

– Updates to Cost and Performance for

APC Technologies Project No. 12847

- 002

March 2013



### Dry Sorbent Injection for SO 2 

### Control

Cost Devel opment Methodology

Page 1 

### Technology Description

Dry sorbent injection (DSI) is a viable technology for moderate SO 2 reduction on coal

fired boilers. D emons trations and recent utility testing have shown SO 2 removal s greater
than 80% for system s 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

Stoichi ometric Ratio (NSR) and particulate capture device. NSR is defined as:

The target removal efficiency is a requirement from the utility and is independent of unit size. The costs for a DSI system are primarily depend e nt on sorbent feed rate which is a function of NSR and SO 2 mass feed rate per hour . Therefore, the cost estimation was based on sorbent feed rate 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 e fficiencies 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 efficiency with Trona, the NSR is reduced when a baghouse is used for particulate captur e.

The dry sorbent capture ability is a lso a function of particle surface area. To increase the particle surface area, the sorbent must be injected into a relatively hot flue gas . Heating the solids produce s micropores on the particle surface which grea tly improve the sulfur capture ability. For Trona, the sorbent should be injected into flue gas 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 t hus lowering the SO 2 removal efficiency of the sorbent

.

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 m. Commercial t esting has shown

that the reactivity of the Trona can be increased when the sorbent is ground to less than

30 m. In the cost estimating methodology, the Trona is always delivered in the unmilled state. To mill the Trona, in

- line mills a re continuously used during the Trona injection process. Therefore, the delivered cost of the Trona will not change, only the reactivity and usage changes as the Trona is milled.IPM Model

– Updates to Cost and Performance for

APC Technologies Project No. 12847

- 002

March 2013



### Dry Sorbent Injection for SO 2 

### Control

Cost Devel opment Methodology

Page 2 Ultimately, the NSR required for a given removal is a function of Trona par ticle size and particulate capture equipment. Either as delivered Trona (around 30 m average size) or

in

- line milled Trona (around 15 m average size) can be chosen for injection in the cost program. The average Trona particle size and the type of particulate removal both contribute to the predicted Trona feed rate

.



### Establishment of C ost Basis

For the wet or SDA FGD systems, the sulfur removal is generally specified at the maximum achievable level. With those systems, costs are primarily a function of plant size and sulfur rate. However, the DSI systems are quite different. The majo r cost for the DSI system is the sorbent itself. The sorbent feed rate is a function of sulfur rate, particulate collection device, and removal efficiency. To account for all of the variables, the capital cost was established based on a sorbent feed rate . The sorbent feed rate is calculated from user input variables. Cost data for several DSI systems was reviewed and a relationship was developed for the capital costs of the system on a sorbent feed rate

basis.



### Methodology

Inputs

Several input variables are required in order to predict future retrofit costs. The sulfur

feed rate and NSR are the major variables for the cost estimate

. The NSR is a function

of:

Removal efficiency;

Trona particle size; and Particulate capture device.

A retrofit factor th at equates to difficulty in construction of the system must be defined.

The gross unit size and gross heat rate will factor into the amount of sulfur generated

.

Based on commercial testing, removal efficiencies with DSI are limited by the particulate

cap ture device employed. When 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 sulfur content of greater than 2 lb SO 2 /MMBtu.IPM Model

– Updates to Cost and Performance for

APC Technologies Project No. 12847

- 002

March 2013



### Dry Sorbent Injection for SO 2 

### Control

Cost Devel opment Methodology

Page 3 Units with a baghouse and limited NOx control that target a high SO 2 removal efficiency

with sodium sorbents may experience a brown plume result ing from the conversion of

NO to NO 2 . The formation of NO 2 would then have to be addressed by adding adsorbent

in to the flue gas. However, many coal

- fired units control NOx to a sufficiently low level that a brown plume should not be an issue with sodium

- based DSI. Therefore, t his study

d oes not incorporate any additional cost s to control NO 2

.

The equations provided in the cost methodology spreadsheet allow the user to input the required removal efficiency, within the limits of the technology. To simplify the correlation, the removal wit h 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 increase in capital

, the mil ling 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 include s :

All equipment ;
Installation ; Buildings ;
Foundations ;
Electrical ; and Average r etrofit d ifficulty

.IPM Model

– Updates to Cost and Performance for

APC Technologies Project No. 12847

- 002

March 2013



### Dry Sorbent Injection for SO 2 

### Control

Cost Devel opment Methodology

Page 4 The base module cost is adjusted by the selection 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 ho ur shift premium, per diem, etc., at 5 % of the

BM cost ; and Contractor profit and fees at 5 % of the BM cost

.

A capital, engineering, and construction cost subtotal (CECC) is established as the sum of the BM and the additional engineering and construction fees.

Additional costs and financing expenditures for the project are computed based on the CECC. Financing and additional 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 (AFUDC) at 0 % of the

CECC and owner’s costs as these projects are expected to be completed in less than a year

.

The t otal project cost is based on a multiple lump sum contract approach. Should a turnkey engineering procurement construction (EPC) contract be executed, the total project cost c ould be 10 to 15% higher than what is currently estimated.

Escalation is not in cluded in the estimate. The total project cost (TPC) is the sum of the

CECC and the additional cos ts and financing expenditures

.

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

The following factors and assumptions underlie calculations of the FOM:

All of the FOM costs were ta bulated on a per kilowatt

- year (kW

- yr) basis.

In general, 2 additional operator s are required for a DSI system

. The FOMO was based on the number of additional operations staff required.IPM Model

– Updates to Cost and Performance for

APC Technologies Project No. 12847

- 002

March 2013



### Dry Sorbent Injection for SO 2 

### Control

Cost Devel opment Methodology

Page 5 The fixed maintenance materials and labor is a direct function of t he process capital cost (BM).

The administrative labor is a function of the FOMO and FOMM.

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 required and unit pow er cost

.

The following factors and assumptions underlie calculations 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 f

actor multiplied by the SO 2 rate determine the SO 2 feed

rate. The estimated NSR is a function of removal efficiency required. The

basis for the total reagent rate is a Trona purity of 9 5 %.

The waste generation rate is a function of the Trona feed rate and is adjusted for the excess sorbent fed. The waste generation rate is based on reaction product s of Na 2 SO 4 and unreacted dry sorbent as Na 2 CO 3

. Waste product adjusted for a maximum of 5% inert in the Trona sorbent.

With the addition of a sodium sorbe nt that is captured in the same particulate control device as the fly ash , 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 production is added to the sorbent w aste to account for a total waste stream in the O&M analysis.

The user has the ability to remove fly ash from the waste disposal cost to reflect the situation where the unit has separate particulate capture devices for fly ash and dry sorbent.

When a bag house is installed downstream of an ESP, the sodium sorbent could be injected before the baghouse with no effect on the fly ash collection.IPM Model

– Updates to Cost and Performance for

APC Technologies Project No. 12847

- 002

March 2013



### Dry Sorbent Injection for SO 2 

### Control

Cost Devel opment Methodology

Page 6 In that case, the disposal costs of the sodium only waste should be increased

to account for the increased difficul ty in handling the pure sodium waste product.

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.

The additional power is reported as a percen t of the total unit gross production. In addition, a cost associated with the additional power requirements can be included in the total variable costs.

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

Trona cost in $/ton ; Waste disposal costs in $/ton that should vary with the type of waste being disposed ; Auxiliary power cost in $/kWh ; Operating labor rate (includin g all benefits) in $/hr

.

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

. The additional auxiliary power requirement is also reported as a percentage of the total gross power of the unit.

Table 1 contains an example of the complete capital and O&M cost estimate worksheet.IPM Model

– Updates to Cost and Performance for APC Technologies Project No. 12847

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March 2013



### Dry Sorbent Injection for SO 2 

### Control Cost Development Methodology

Page 7 Table 1 . Example Complete Cost Estimate for a DSI SystemIPM Model

– Updates to Cost and Performance for APC Technologies Project No. 12847

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March 2013



### Dry Sorbent Injection for SO 2 

### Control Cost Development Methodology

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