FOSTER WHEELER

SUCCESSFUL NOx REDUCTION AND

CONVERSION TO POWDER RIVER BASIN

FUEL ON WALL FIRED BOILERS

Sara Woldehanna, Firing systems Engineer

Tom Steitz, P.E., Firing systems Manager

Brian Exner, Performance Engineer

Foster Wheeler Energy Corporation

Perryville Corporate Park, Clinton, NJ 08809

Brian Skinner, Manager or Performance Resources

Jim Smoeyink, Operations Team Leader

Northern Indiana Public Service Company

5265 Hohman Avenue, Hammond, IN, U.S.A

Presented at:

ASME International Joint Power Generation Conference

Houston, Texas, U.S.A.

October 14-16, 1996

Power Engineering PowerGen Conference

Orlando, Florida, U.S.A.

December 4-6, 1996
SUCCESSFUL NOx REDUCTION AND CONVERSION TO POWDER

RIVER BASIN FUEL ON WALL FIRED BOILERS

Sara Woldehanna,

Firing Systems

Engineer

Tom Steitz,

Firing Systems

Manager

Brian Exner,

Performance Engineer

Foster Wheeler Energy Corporation, Perryville Corp. Park, Clinton, NJ, 08809, USA;

Ph: (908) 713-3005 Fax: (908) 713-2405

Brian Skinner,

Manager of Performance

Resources,

Jim Smoeyink,

Operations Team Leader,

Northern Indiana Public Service Company, 5265 Hohman Aye, Hammond, IN, USA;

Ph: (219) 853-5200 Fax: (219) 956-2398

ABSTRACT

This paper presents the project goals and

evaluations along with the operating results of the Low

NOx/Powder River Basin (PRB) fuel conversion at

Northern Indiana Public Service Company’s (NIPSCO),

Schahfer unit 15, 500 MW boiler. In adherence to the

New Source Performance Standards (NSPS), the

original firing equipment produced NOx emissions

slightly below 0.70 lb/MMBtu burning Bituminous coal

with overt fire air.

The overall objectives were to burn cost effective

PRB coal at NOx emissions below 0.45 lb/MMBtu while

maximizing boiler performance. Working closely with

NIPSCO, Foster Wheeler Energy Corporation (FWEC)

designed and supplied the necessary Low NOx burners

and pressure parts modification to enable PRB coal

firing on this unit.

Post-retrofit NOx emissions, without overfire air, are

consistently below 0.35 lb/MMBtu with repeatable loss of

ignition performance below 1%. The pressure part

modifications met NIPSCO’s boiler performance

requirements, with successful unit operation above 90%

MCR.

Experiences with PRB coal at other Foster Wheeler

units are also briefly described.

Northern Indiana Public Service Company: Schahfer

unit 15

INTRODUCTION TO BOILER AND ORIGINAL

EQUIPMENT

The unit, a 500 MW Foster Wheeler boiler, is owned by

Northern Indiana Public Service Company (NIPSCO)

and was commissioned into service in 1979. The original

equipment was designed to perform under the New

Source Performance Standards (NSPS) of the 1970’s.

The boiler is a natural circulation, reheat type steam

generator rated for a maximum capacity of 3,800,000

lbs/hr of superheated steam at 2620 psig and 1005 F

design outlet (Fig. 1). At 100% MOR, reheat steam was

designed at 3,366,000 lbs/hr of flow at 562 psig with an

outlet temperature of 1005 F. Superheat steam

temperature control is achieved by sprays.

Originally, six MB-23 vertical spindle mills were used

for coal pulverizing. These mills were eventually

replaced by six MPS 89 N mills by NIPSCO. At MOR,

the design coal flow for the specified fuel was 480 klb/hr

resulting in approximately 80 Klb/hr coal flow per mill.

Coal is fed to a balanced draft opposed fired furnace

with 24 burners. The furnace is 59 1⁄2 feet wide by 52 feet

deep. Each wall has 4(columns) by 3 (rows) of burners

with one row of overfire air ports located above the

center line of each burner column. The original design

fuel is a Bituminous coal with higher heating value of

11,000 Btu/lb (refer to Table 1 for proximate and ultimate

analysis of design coal). At MCR the total heat input

from coal was designed to be approximately 5600

MMBtu/hr, resulting in a relatively cool furnace. The

efficiency of the unit at MCR was predicted to be 87%.

The original burners were Foster Wheeler’s

turbulent type with scroll inlets designed to achieve NOx

slightly less than 0.70 lbs/MMBtu with overfire air. The

twenty-four turbulent burners had 48’ throat diameters

with an inner barrel housing oil ignition equipment.

OBJECTIVE OF PROJECT

To meet 1990 Clean Air Act, NIPSCO decided to

explore different options to bring NOx down from the

nominal current values of 0.70 lbs/MMBtu to below the

regulatory limits of 0.45 lbs/MMBtu. In conjunction with

attaining this objective, NIPSCO wanted the option of

burning Powder River Basin (PRB) coal, which is

significantly different from the Eastern Bituminous coal

for which this unit was designed Requirements of the

1990 Clean Air Act have increased utility interest in

burning PRB coal. This coal is not only inexpensive to

burn, but is low in sulfur content. Thus, PRB can be an

economical alternative to various methods of flue gas

desulfrization. However, burning PRB is not without its

disadvantages.
FWEC was contracted by NIPSCO, with a two fold

purpose in mind:

• conduct a study on the effect of burning PRB fuel on

boiler performance, recommend modifications, and

design and install required modifications;

• modify or supply any combustion equipment to

reduce NOx reduction below regulatory limits.

Although the project was broken down into two

smaller projects related to these two objectives, award of

both to FWEC allowed for the natural mating of the two

designs. FWEC undertook both these projects which

included design and supply of pressure part

modifications and low NOx IFS burners.

IMPACT OF BURNING PRB WITH ORIGINAL

PRESSURE PARTS

PRB is not considered to be a high slagging coal in

the traditional sense of the word. Unlike high slagging

eastern coals, the ash accumulation caused by burning

PRB is thin. However, the impact on surface

effectiveness is generally the same as that of high

slagging coals.

The ash in PRB coal contains high amounts of

calcium oxide (CaO). Because the calcium oxide is

white, it causes the ash to be light colored and to have a

reflective quality. When fired, a thin layer of light-colored

ash quickly builds on the furnace water walls and any

other radiant heat transfer surface. The reduction in

surface effectiveness causes less heat to be absorbed in

the water walls, roof and radiant superheater. The

suppressed absorption in the furnace results in a high

furnace exit gas temperature.

PRB also has a relatively high fouling potential

which must be considered. Due to the high gas

temperatures, the hemispherical softening temperature

of the ash can be exceeded at the furnace exit and into

the convection surface, causing the ash to be “sticky”.

As a result, a layer of ash forms on the convection

surfaces, and reacts chemically with the tubes and the

hot flue gas to form a tenacious deposit which is difficult

to remove.

Fouling in the convection surfaces (HRA) generally

begins as the ash accumulates in the back spacing

between the tubes. This is known as “profiling”. Profiling

with PRB coals is not uncommon in the primary

superheater and the reheater. Over time, the backspace

can become completely closed. This not only insulates a

significant area of the heat transfer surface, but it

changes the gas flow around the tubes and thus reduces

the effectiveness of the surface.

Experience has indicated that fouling in the HRA is

more significant in the primary superheater and the

upper banks of the reheater. The severity of the fouling

appears to be reduced in the lower HRA. Consequently,

from a design standpoint, it is desirable to have ample

clear space between elements in the upper HRA. If

ample space between coils is not maintained, the ash

accumulation may bridge the space between tubes. The

higher gas temperature also helps drive the transfer of

heat in spite of the decreased surface effectiveness.

This is due to the higher log mean temperature

differential (LMTD) between the gas and the steam.

Even with the higher LMTD, heat transfer to the fouled

tubes can not be maintained at the rate achieved with

the clean tubes

The elevated flue gas temperature is then carried

through the entire boiler. The result is a higher gas

temperature leavingthe economizer. If significant, this

can potentially weaken the structural supports and the

flue plate in the area above and below the lower

economizer. All structural equipment must be carefully

examined for the gas temperatures experienced when

burning PRB.

The high gas temperatures combined with the high

moisture content of PRB together results in lower boiler

efficiency. In some cases, as much as a 5% reduction in

boiler efficiency has been noted when switching to PRB

coal firing.

PROPOSED BOILER AND BURNER MODIFICATIONS

To achieve the above expressed objectives, FWEC

performed a study, and proposed a retrofit of the

turbulent burners and OFA system with FWEC’s low

NOx IFS burner, as well as changes to the original

pressure parts to accommodate firing PRB coal.

Recommendations for Pressure Part Modifications

As an initial step, an engineering study was

performed to predict the effects of burning PRB coal with

the original pressure parts. In order to establish a

baseline for the study, the performance of the boiler was

predicted when firing the current Eastern Bituminous

coal, utilizing the FWEC Boiler Performance computer

program. The boiler load for this prediction was

approximately 90% of the original MCR due to a unit derating necessitated by high gas temperatures entering

the air heater experienced while firing Eastern

Bituminous coal. The performance model was made

without the hot precipitator as it was to be converted to a

cold precipitator during the modification outage. A

summary of this performance appears in Table 2,

Column I.

Performance predictions were then calculated
utilizing the original pressure parts when firing PRB coal.

The predictions were made utilizing computer analysis

with heat transfer surface effectiveness correlations

adjusted to reflect typical operating characteristics of

PRB coals. As seen in Table 2, Column II, the furnace

exit gas temperature (FEGT) was predicted to increase

when switching to PRB coals. This is due mainly to the

highly reflective ash associated with this fuel. In order to

minimize potential fouling of the convection surface, it

was desirable to maintain the FEGT below 2300F, the

ash softening temperature in a reducing atmosphere of

the design PRB coal (see Table 1). At 90% MCR, it was

predicted that the FEGT could be maintained below

2300F when switching to PRB coal.

Additionally, the gas temperature entering the

horizontal primary superheater was predicted to be

1884F. This was found to exceed the acceptable gas

temperature for the original arrangement of this

equipment and could lead to excessive fouling and

possibly plugging of the convection surface.

In order to optimize the conversion to PRB coal, the

following design modification were recomended:

• Increase the clear side spacing in the primary

superheater to minimize the potential for fouling and

plugging;

• Add a vertical loop or ‘dogleg to the top of the

primary superheater in order to maintain

superheater capability that may be lost due to the

above arrangement modification. This would also

reduce flue gas temperatures entering the horizontal

primary superheater to further reduce the propensity

for fouling and plugging;

• Increase the heating surface in the primary

superheater by increasing the tube diameter to help

maintain final steam temperature and to reduce gas

temperatures in the HRA;

• Add a loop to the top of the upper economizer to

further reduce the flue gas temperature;

• Add furnace wall blowers to maintain the highest

degree of furnace cleanliness possible.

A summary of the performance predictions for the

modified pressure parts can be seen in Table 2, Column

Ill. It should be noted that the addition of the primary

superheater dogleg was predicted to reduce the gas

temperature entering the horizontal primary superheater

by 86F. The gas temperature entering the air heater was

predicted to drop by 10F because of the recommended

modifications which results in a slight increase in boiler

efficiency. Additional boiler modifications were to be

considered if a greater reduction in flue gas temperature

entering the air heater was required based on

operational experience.

Low NOx Burner Modification

To reduce NOx from the baseline values of 0.70

lbs/MMBtu to 0.45 lbs/MMBtu, FWEC recommended

replacing the original turbulent burners with the current

state-of -the-art FWEC patented IFS burners (Fig. 2).

Since the prediction of NOx using only these burners

was comfortably below 0.45 lbs/MMBtu, FWEC

proposed that the current overfire air ports be blanked

off to maximize combustion efficiency. In addition,

FWEC believed their closure would allow for increased

reheat steam temperature capability at low loads

following the retrofit. The proposed Low NOx coal wall

fired burner was FWEC’s third generation Internal Fuel

StagedTM (IFS) design. This Low NOx burner is based

on a concept patented by FWEC in the 1970’s. The IFS

burner became available for commercial operation in

1990 and has since become a proven design with

operational experience on a number of boilers.

The IFS burner two-stages the secondary air flow

and internally stages the fuel and primary air flows such

that co-axial flames are developed within the burner’s

throat for NOx reduction, while maintaining classical

turbulent burner flame patterns and low windbox to

furnace pressure drop.

A fundamental design philosophy was strictly

adhered to during the development of this burner:

• Flame length and envelope should be equivalent to

that of the turbulent burners that have been in

historical use;

• Combustion air flow and swirl to each burner should

be independently controllable;

• Primary air/coal velocity should be adjustable to

insure optimum relation between primary and

secondary air streams.

• Primary and secondary air pressure drop should be

no greater than for the turbulent burners, to ensure

the use of existing fans.

The following design features of the IFS burner are

integral in the reduction of NOx and stable combustion:

• Dual Series register provides flame shape control

and NOx reduction by using a two-stage secondary

air adjustment;

• Adjustable coal nozzle allows primary air/coal

velocity to be optimized without changing primary air

flow, thus ensuring optimized NOx reduction with

good combustion;

• Internal Fuel Staged Nozzle segregates the coal into

multiple concentrated stream and develops a coaxial inner flame zone . This results in the volatiles of

the coal being driven out and burned under more

reducing conditions than otherwise would occur. The

volatiles contain a high percentage of the fuel bound

nitrogen, and combustion under reducing conditions

converts bound nitrogen into free N2, substantially

reducing NOx formation.

RETROFIT AND MODIFICATION

The proposed modifications were accepted by

NIPSCO and implemented during a unit outage in May,

1994. FWEC designed and supplied 24 IFS burners and

all necessary auxiliary equipment. Existing burner throat
openings were utilized with some modifications. Twenty

four existing gas ignitors were modified to fit new

burners. In order to equalize conduit to conduit coal

distribution, eighteen coal conduit ceramic lined resistors

were designed and supplied. The design and fabrication

of these resistors were based on a coal flow study.

Existing overfire air ports had been blanked off prior to

this outage.

During the outage, the recomended heat transfer

surface modifications were also installed. The primary

superheater was redesigned and a vertical superheater

“dogleg” was added. An additional upper economizer

loop was added and extra sootblower openings to

adequately clean the new vertical primary superheater

were installed.

FWEC offered NIPSCO the following primary

guarantees with this conversion:

• The pressure part modifications will not prevent the

boiler from achieving 90% of original MCR;

• When operating at 90% of original MCR (3,420,000

lbs/hr main steam flow), the superheater spray flow

will not exceed 275,000 lbs/hr (+10,000 lbs/hr

tolerance);

• NOx emissions, measured at the economizer outlet,

without the use of overfire air, shall not exceed 0.45

lbs/MBtu over the load range;

• Unit carbon monoxide (00) shall not exceed 100

parts per million (ppm) with the unit operating at

guaranteed NOx emissions levels at full load;

• Unburned carbon in ash will be less than or equal to

3%.

• Windbox to furnace differential will not exceed 3.5 in

WO over the load range with all twenty four burners

in service.

POST RETROFIT PERFORMANCE

Following the modifications, FWEC conducted tests

to optimize the burners and evaluate post retrofit

performance. The post-retrofit NOx emissions as

measured by the CEMS during all the optimization tests

were consistently below 0.35 lb/MMBtu (Fig. 3). CO

emissions at the end of the optimization testing were

always less than 75 ppm (Fig. 4). LOI values were less

than 1.2 % for all tested samples (Fig. 5 and 6), 50% the

contract requirements.

At the conclusion of the optimization tests, NOx

guarantee tests were performed by an independent third

party contractor, Mostardi Platt. The tests were

performed at nominal full (90% of original MCR) and

intermediate loads. Low excess air operation (10%)

during these tests produced less than 0.25 lb/MMBtu

NOx, again with less than 1% LOI values (Fig. 7).

Prorating the NOx results to 100% MCR at 20% equates

the NOx emissions to below 0.4 lb/MMBtu, without over

fire air. Prorated emissions at 100% MCR and 10%

excess air fall well below 0.35 lb/MMBtu. Furnace to

windbox pressure drop was only 2.1” WO (Fig. 8).
The pressure part modifications allowed for

successful operation even above the predicted 90%

MCR (Fig. 9). Further increased capacity would be

available should additional pressure part modifications

recommended by FWEC be implemented. The

superheat spray flow was consistently below 225,000

lbs/hr, well below guarantee levels of 275,000 lbs/hr

(Fig. 10).
To compare the effectiveness of the pressure part

modifications, refer back to Table 2. Column IV is a

baseline test taken before the modification of the unit

using the Bituminous coal fired in 1993. It can be seen

that the gas temperatures were higher than those

originally predicted (column I, Table 1). Even with these

higher than predicted baseline temperatures, post retrofit

gas temperatures were reduced to target levels (see

columns Ill, V and VI of Table 2).

PROBLEMS ENCOUNTERED

The only adverse operational experience

encountered has has been burner throat eyebrows.

Eyebrows are formations of slag on the burner throat

refractory, and usually form on the upper hemisphere of

the throat. They are commonly seen with high slagging

coals where the ash suspended in the hot combustion

gas comes in contact with the refractory walls that are

relatively hotter than tube surfaces. Even though the ash

has little tendency

to accumulate on clean surfaces to begin with, after

a while, a thin layer of ash starts to accumulate on the

refractory walls. This thin layer will have a higher surface

temperature than the retractory, and ash particles now

suspended in the combustion gas will have more of a

propensity to attach to this thinly layered surface. Thus,

after the initial deposition, the ash accumulation tends to

grow very fast.

Even though eye brows are mainly a result of fuel

properties, different flow patterns are suspected to

accelerate or delay their formation of eyebrows. NIPSCO

and FWEC have decided to jointly tackle the formation of

these eyebrows over long term operation through the

exploration of different flow patterns through testing and

flow modeling.

PRB Experiences at other Units

Portland General Electric’s Bordman Station, Unit 1

is a 500 MW Foster Wheeler Unit commissioned into

service in 1980. The boiler was designed to burn AMAX

coal from the Eagle Butte mine in the Powder River

Basin of Wyoming (Table 3) to meet the NSPS NOx

emissions standard of 0.7lbs/MMBtu. The boiler is

opposed fired with four levels of burners with four

burners in each deck. Eight FW MB-23 mills supply the

burners.

The Bordman Station Unit 1 was equipped with what

was at the time the most advanced FW combustion

system: the Controlled Flow! Split Flame Burner (CF/SF)

and overfire air ports (The CF/SF burner is an earlier

generation FW low NOx burner and varies in some

aspects from later generation burners; one key

difference is that the CF/SF has a four port coal tip

instead of the six port tip of the IFS burner.) Four overfire

air ports were located on each wall.

The following performance guarantees were offered

at the MCR steam flow of 3,825 klb/hr: boiler efficiency

will not be less than 84.86 + 0 33 % superheat and

reheat steam temperatures will be 1005 + 10 F; and

reheat spray flows under specifically defined inlet steam

temperatures will be 0 klb/hr.

Testing conducted in 1981 resulted in NOx

emissions of 0.384 lbs/MMBtu without overfire air and

0.248 lbs/MMBtu with overf ire air. UBC in fly ash was

approximately 0.33%. While turbine operation restriction

forced steam temperature set points to 950 F, there was

no reheat spray, and boiler efficiency was 84.7%, well

within guarantee levels.

Central and South West Service’s Oklaunion Unit 1

is a 720 MW Foster Wheeler unit commissioned into

service in 1986 and was designed to burn sub

bituminous coal with PRB characteristics (Table 3) . The

boiler is opposed fired with three decks of CF/SF low

NOx burners with five burners in each deck. Six FW

MBF mills supply the burners.

The following performance guarantees were offered

at the MCR steam flow of 4,913 klb/hr: NOx emissions

will be less than or equal to 0.5 lbs/MMBtu; boiler

efficiency will not be less than 84.99 ± 0.33 %; and

superheat and reheat steam temperatures will be 1005 +

10 F.

Testing conducted by an independent party in 1988

resulted in NOx emissions of 0.37 lbs/MMBtu at MCR

conditions with superheat and reheat temperatures at

996 F and 994 F respectively. The boiler efficiency at

guarantee conditions was 84.84%, well within guarantee

levels.

Grand River Dam’s Unit 2 is a 570 MW Foster

Wheeler unit commissioned into service in 1986. The

unit was designed to burn either a Wyoming sub

bituminous coal (Rawhide) or a 50/50 blend of the

Rawhide with an Oklahoma strip mine bituminous coal

(Table 3) The boiler is opposed fired with three decks of

CF/SF low NOx burners with four burners in each deck.

Six FW MBF mills supply the burners. Four overfire air

ports were located on each wall.

The following performance guarantees were offered

at the MCR steam flow of 3,900 klb/hr: NOx emmissions

will be than or equal to 0.5 lbs/MMBtu; superheat and

reheat steam temperatures will be 1005 + 10 F; and

boiler efficiency will not be less than 86.23 + 0.33 % for

PRB firing, and 88.38 + 0.33% for the blend firing.

Testing conducted on the pure Rawhide Wyoming

coal resulted in superheat temperatures of 1004 F and

reheat temperatures of 993 F. NOx emissions for these

tests are not available. NOx compliance tests conducted

a few months later with a 50/50 Wyoming/Oklahoma

blend resulted in 0.42 lbs/MMBtu with over fire air. Boiler

efficiency calculations are not available.

CONCLUSION

Based on the operating results at NIPSCO and the

other units described above, when firing PRB coal NOx

levels in the range of 0.35 to 0.45 with low NOx burners

only, and 0.3 to 0.4 with low NOx burners coupled with

overf ire air are easily achieved. Low excess air

operation is a viable option due to the volatility of the

fuel, with NOx levels below 0.3 lbs/MMBtu with burners

alone and LOI less than 1%. Boiler and HRA pressure

parts can be studied and modified to permit operation

with the inexpensive PRB coal. Most performance

predictions for the units described have been achieved

or exceeded.

Acknowledgments

FWEC would like to acknowledge the major

contributions of NIPSCO to this project. The authors also

appreciate the important assistance of Timothy Sweeney

and Al Edwards of Foster Wheeler Energy Corporation

to the creation of this paper.
Table 1: Coal Analyses for the Various Coals

Constituent (on as

received basis)

Bituminous coal

used in predictions

Design PRB coal

used in predictions

Pre-retrofit test coal

(Bituminous)

Typical PRB coal

during post retrofit

optimization

Volatile Matter % Appx 38 34.87 32.53

Fixed Carbon % Appx 43 44.7 32.18

H2O % 11.03 29.5 13.27 29.63

Ash % 8.01 5.01 7.16 5.66

S2 % 0.41 0.34 0.40 0.33

H2 % 4.2 3.45 4.51 3.47

Carbon % 63 49.1 63.64 48.79

N2 % 1.4 0.72 1.34 0.79

O2 % 11.03 11.8 9.68 11.35

HHV 11.000 8.500 11.205 8.407

CaO % of Ash 4.35 24.5 5.35 20.77

MgO % of Ash 1.3 4.5 1.27 3.73

Ash Softening Temp in

Reducing atm, F 2460 2300 2345 2144

Ash Softening Temp in

Oxidizing atm, F 2550 2350 2520 NA

Table 2: Gas Temperatures at various points in the gas pass

Case I: Baseline

prediction

II: PRB / No

change

III: PRB w/

modification

IV: Baseline

Test V: NOx Test VI: Optimiz.

Test

Main steam flow, klbh 3420 3420 3420 3431 3400 3138

Superheat spray flow, klbh 16 146 242 64 225 120

Furnace Exit Gas

Temperature, F 2121 2290 2289 2254 2246* 2241*

Gas entering horizontal

superheater, F 1745 1884 1798 1883 NA NA

Gas leaving lower

economizer, F 768 822 812 809 742 755

Unit efficiency % 88.51 84.61 84.75 85.89 NA NA

Case I: Predictions with original boiler pressure parts with Eastern Bituminous coal fired prior to pressure part modifications

Case II: Predictions with original boiler pressure parts with PRB fuel

Case III: Predictions with pressure part modifications and PRB fuel

Case IV: Baseline testing with original pressure parts and Eastern Bituminous test coal

Case V: NOx Guarantee post retrofit test: after phase I modifications, firing PRB coal

Case VI: Test conducted during final phase of Low NOx Burner Optimization period, firing PRB coal

• Denotes measured FEGT
Table 3: Design Coal Analyses

Constituent (on as

received basis)

AMAX coal of

Portland Electric

Sub Bit. Coal of

Central & South

West

Grand River Dam’s

sub bituminous coal

Grand River Dam’s

bituminous coal

Volatile Matter % 31.2 30.05 30.05 35.5

Fixed Carbon % 32 32.94 32.94 48.5

H2O % 30.4 31 31 4.62

Ash % 6.4 6.01 6.01 7.7

S2 % 0.3 0.4 0.4 2.69

H2 % 3.4 3.25 3.25 5

Carbon % 47.85 46.81 46.81 69.5

N2 % 0.62 0.66 0.66 1.4

O2 % 10.83 11.87 11.86 5.27

HHV 8020 8055 8055 12000

CaO % of Ash 22.85 20.53 20.68 4.6

MgO % of Ash 4.74 4.59 4.62 1

Ash Softening Temp in

Reducing atm, F 2193 2178 2180 NA

Ash Softening Temp in

Oxidizing atm, F 2255 2234 2234 NA