INTERNATIONAL APPLIED ENGINEERING, INC ENGINEERS & CONSULTANTS

Environmentally Friendly Energy Solutions 

C:\Users\Gary\Desktop\Methodology for Calculating FEGT for Domtar.doc

1165 ALLGOOD ROAD  SUITE 6  MARIETTA, GA 30062  PHONE: (770) 977-4248  FAX: (770) 977-2832  E-MAIL: iae@iaeinc.com 

Methodology for Calculating Furnace Exit Gas Temperature

The following fuel heating values were used: 

 Bark @ 50% moisture: 4,200 Btu/lb 

 Coal: 11,884 Btu/lb 

 Tire Derived Fuel (TDF): 16,513 Btu/lb 

 Natural Gas: 1,000 Btu/scf 

For grate fired fuels (bark & TDF) an equivalent flat projected furnace wall area (Sc) of 

10,884 ft2 (Sc4) was used. For wall fired fuels (coal & natural gas) two different Sc 

values were used depending on the number of burner levels in service. When the coal 

flow was calculated to fall below 10 t/h, the bottom row of coal burners was turned off. 

The Sc used when coal flow is calculated to be 10 t/h or more was 10,539 ft2 (Sc3). 

The Sc used when coal flow is calculated to be under 10 t/h was 9,509 ft2 (Sc2). 

The heat input from each fuel was calculated by multiplying the fuel flow by the 

corresponding heating value. The furnace heat release rate was obtained by dividing 

the fuel heat inputs by the corresponding Sc. Two empirical curves were used for 

determining the furnace exit gas temperature (FEGT). One is for grate fired fuels and 

one is for pulverized coal fired from a single wall. The curves were converted into 

mathematical equations in the spreadsheet, and the weighted average between the 

two curves, based on the ratio of grate fired heat input versus wall fired heat input, is 

displayed as the FEGT. 

Methodology for Calculating Absorptive Surface Area in Domtar PB#2 

Empirical Data: 

 Form P-3 Manufacturer’s Data Report for Water-tube Boilers, Superheaters, 

Waterwalls, and Economizers; 114-0253 Babcock & Wilcox Company 1975 

 Sectional Side View at “E–E” DWG. 36057F

 Front and Rear Wall dimension of 19’-11” centerline to centerline per 

Domtar 

Protocols: 

 2-1/2” tubes on 3” centerline to centerline spacing with 1⁄2” web converted to 

4.427” flat projected surface measurement

 Corrected absorptive surface area (Sc) is calculated from five (5) feet below 

centerline of burner for conditions Sc1, Sc2, and Sc3

ASHDOWN-Supp09-000001
INTERNATIONAL APPLIED ENGINEERING, INC ENGINEERS & CONSULTANTS

Environmentally Friendly Energy Solutions 

C:\Users\Gary\Desktop\Methodology for Calculating FEGT for Domtar.doc

1165 ALLGOOD ROAD  SUITE 6  MARIETTA, GA 30062  PHONE: (770) 977-4248  FAX: (770) 977-2832  E-MAIL: iae@iaeinc.com 

 Sc4 is calculated from centerline of headers above the grate to the roof in 

front of the superheater for front wall and sidewalls, and from centerline of 

header above grate to apex of neck on back wall 

 A correction factor for dirty furnace walls for pulverized coal firing was used 

on the portion of the furnace affected by the burners on Sc4

Respectfully Submitted 

September 9, 2014, by: 

Gerald R. (Gary) Elliott 

Principal Engineer 

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INTERNATIONAL APPLIED ENGINEERING, INC ENGINEERS & CONSULTANTS

Environmentally Friendly Energy Solutions 

C:\Users\showard\AppData\Local\Microsoft\Windows\Temporary Internet Files\Content.Outlook\AUGXGWWV\Observations of Charted Steam Rates and Furnace Exit Gas Temperature.doc

1165 ALLGOOD ROAD  SUITE 6  MARIETTA, GA 30062  PHONE: (770) 977-4248  FAX: (770) 977-2832  E-MAIL: iae@iaeinc.com 

Observations of Charted Steam Rates and Furnace Exit Gas Temperature (FEGT) 

Based upon empirical data received from Domtar on Power Boiler #2 (PB2) in the form 

of a spreadsheet recording data on an hourly basis from 0600 7/14/2014 to 0600 

7/26/2014, PB2 Fuel Analysis Current Operation Summer, calculated absorptive surface 

area in the boiler, and custom heat transfer to furnace curves, an estimated FEGT for 

this period was calculated. International Applied Engineering (IAE) has charted the 

measured Steam Rate and calculated FEGT over the 12-day period covered by the 

data supplied. Overlaying the charted data is a band representing the range of 

temperature (1700-1800°F) where an SNCR technology could be expected to reach 

40% denitrification efficiency at the current boiler conditions of 10% excess O2 and 

typical fuel blend at that corresponding steam demand rate, provided the Normalized 

Stoichiometric Ratio (NSR) was appropriate for the fuels mixture input and the ammonia 

or urea application was effective. 

 There is a direct positive relationship between Steam Demand and FEGT 

 Only a Steam Demand above 350 klb/hr will generate FEGT in the range for 

optimal Denitrification Efficiency 

 At no time during the 12-day period studied did conditions exist for longer than 

four (4) hours continuously that would satisfy Denitrification Efficiency equal to or 

above 40% 

 Steam Demand fluctuates from 10 klb/hr to as much as 50 klb/hr on at least an 

hourly basis (minimum recorded period) 

 There are nine (9) recorded periods of at least one (1) hour when expected 

Denitrification Efficiency should equal or exceed 40% 

 These periods total twenty (20) hours over the 12-day period (288 continuous 

hours) and equal less than 7% of the evaluation period 

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0.00

50.00

100.00150.00200.00250.00300.00350.00400.00450.00500.00

7/12/2014 0:00 7/14/2014 0:00 7/16/2014 0:00 7/18/2014 0:00 7/20/2014 0:00 7/22/2014 0:00 

Steam Rate (klb/hr)

Domtar PB#2 Steam Rates (klb/hr) & FEGT (F)

Steam FEGT

SNCR >40% Denitrification Efficiency @ 10% O2 level