### FORMATION OF NO x
IN IRON OXIDE
PELLETIZING FURNACESFinal Report



## FORMATION OF NO x IN IRON OXIDE
PELLETIZING FURNACES

SUBMITTED TO

MINNESOTA DEPARTMENT OF NATURAL RESOURCES
DIVISION OF MINERALS

by Robert K. Zahl, Larry A. Haas, and John Engesser

Submitted September 29, 1995 by: U.S. Bureau of Mines Twin Cities Research Center Minneapolis, MN 55417 and: Natural Resources Research Institute - Coleraine Research Laboratory University of Minnesota, Duluth Duluth, MN 55811

### Formation of NO in Iron Oxide Pelletizing Furnaces

TABLE OF CONTENTS Page

LIST OF TABLES LIST OF FIGURES 

### ii ABSTRACT 1 1. INTRODUCTION 3 Formation of nitrogen oxides 4 Toxicity 6 Emission regulations 7 Emission control 9 2. EQUIPMENT AND PROCEDURES 10 Gas sampling probe 10 Emission monitoring equipment 10 CEM instrument descriptions 10 Process gas flow measurement 12 Mass flow calculation procedure 12 Error analysis 17 3. GRATE-KILN PRODUCING ACID PELLETS 19 Furnace description 19 Discussion of samples 20 Results for the furnace 23 4. STRAIGHT-GRATE PRODUCING ACID PELLETS 24 Furnace description 24 Discussion of samples 25 Results for the furnace 26 5. GRATE-KILN PRODUCING FLUXED PELLETS 28 Furnace description 28 Discussion of samples 28 Results for the furnace 30 6. STRAIGHT-GRATE PRODUCING FLUXED PELLETS 31 Furnace description 31 Discussion of samples 32 Results for the furnace 35 7. DISCUSSION 37 Grate-Kiln 37 Straight-Grate 38 Furnace Comparisons 38 8. CONCLUSIONS 40 REFERENCES 42 TABLES FIGURES APPENDICES

### LIST OF TABLES

2.1 Weather data for the field study - Hibbing, MN airport 2.2 Sensitivity analysis for the NO x mass flow calculations

3.1 Average gas analyses for selected periods for a Grate-Kiln producing acid pellets. 3.2 Feed & product chemistry for the Grate-Kiln producing acid pellets. 3.3 Summary of measurements for the Grate-Kiln producing acid pellets. 3.4 Summary of results for the Grate-Kiln producing acid pellets.

4.1 Average gas analyses for selected periods for a Straight-Grate producing acid pellets. 4.2 Feed & product chemistry for the Straight-Grate producing acid pellets. 4.3 Summary of measurements for the Straight-Grate producing acid pellets. 4.4 Summary of results for the Straight-Grate producing acid pellets.

5.1 Average gas analyses for selected periods for the Grate-Kiln producing fluxed pellets. 5.2 Feed & product chemistry for the Grate-Kiln producing fluxed pellets. 5.3 Summary of measurements for the Grate-Kiln producing fluxed pellets. 5.4 Summary of results for the Grate-Kiln producing fluxed pellets.

6.1 Average gas analyses for the Straight-Grate producing fluxed pellets. 6.2 Feed & product chemistry for the Straight-Grate producing fluxed pellets. 6.3 Summary of measurements & estimates for the Straight-Grate producing fluxed pellets. 6.4 Chemical analyses of windbox dust samples from a Straight-Grate producing fluxed pellets. 6.5 Summary of results for the Straight-Grate producing fluxed pellets.

### LIST OF FIGURES

1.1 Pellet bed inside a laboratory furnace. 1.2 Photolytic cycle for nitrogen oxides in the atmosphere.

2.1 Gas sampling probe. 2.2 Filter and liner insert for the gas sampling probe.

3.1 Process flow diagram for the Grate-Kiln producing acid pellets. 3.2 Gas analyses vs. time for the sample GKA-6a 3.3 Gas analyses vs. time for the sample GKA-5 3.4 Gas analyses vs. time for the sample GKA-3 3.5 Gas analyses vs. time for the sample GKA-6b 3.6 Gas analyses vs. time for the sample GKA-6c 3.7 Selected operating data during the GKA-3 sampling period. 3.8 Selected operating data during the GKA-5 sampling period. 3.9 Selected operating data during the GKA-6a sampling period. 3.10 Selected operating data during the GKA-6b sampling period. 3.11 Selected operating data during the GKA-6c sampling period. 3.12 Measured waste gas flow vs. fan current draw. 3.13 Combustion curves for the Grate-Kiln producing acid pellets. 3.14 NO vs. CO 2 analyses for the Grate-Kiln producing acid pellets. 3.15 NO„ mass flow vs fuel flow for the Grate-Kiln producing acid pellets. 3.16 Ratio of NO mass flow to fuel flow for the Grate-Kiln producing acid pellets.

4.1 Process flow diagram for the Straight-Grate producing acid pellets. 4.2 Gas analyses vs. time for the sample SGA-WB16. 4.3 Gas analyses vs. time for the sample SGA-WB18. 4.4 Combustion curves for the sample SGA-WB18. 4.5 NO. vs. CO 2 analyses for the Straight-Grate producing acid pellets. 4.6 NO mass flow vs fuel flow for the Straight-Grate producing acid pellets. 4.7 Ratio of NO mass flow to fuel flow for the Straight-Grate producing acid pellets.

5.1 Process flow diagram for the Grate-Kiln producing fluxed pellets. 5.2 Gas analyses vs. time for the sample GKF-1 5.3 Gas analyses vs. time for the sample GKF-3 5.4 Gas analyses vs. time for the

, sample GKF-4 5.5 Gas analyses vs. time for the sample GKF-5 5.6 Gas analyses vs. time for the sample GKF-6a 5.7 Gas analyses vs. time for the sample GKF-6b 5.8 Selected operating data during the GKF-4 sampling period. 5.9 Combustion curves for the Grate-Kiln producing fluxed pellets. 5.10 NO vs. CO 2 analyses for the Grate-Kiln producing fluxed pellets.

ii

### LIST OF FIGURES, cont.

5.11 NO mass flow vs fuel flow for the Grate-Kiln producing fluxed pellets. 5.12 Ratio of NO mass flow to fuel flow for the Grate-Kiln producing fluxed pellets.

6.1 Process flow diagram for the Straight-Grate producing fluxed pellets. 6.2 Gas analyses vs. time for the sample SGF-WB6. 6.3 Gas analyses vs. time for the sample SGF-WB10. 6.4 Gas analyses vs. time for the sample SGF-WB12. 6.5 Gas analyses vs. time for the sample SGF-WB26. 6.6 Burn-through temperature and NO for the SGF-WB12 sampling period. 6.7 Combustion curves for the Straight-Grate producing fluxed pellets. 6.8 NO vs. CO 2 analyses for the Straight-Grate producing fluxed pellets.

7.1 NO„ mass flow vs. fuel flow for all gas samples. 7.2 Ratio of NO flow to fuel flow vs. fuel flow for all gas samples.



### iii

## FORMATION OF NO x IN IRON OXIDE PELLETIZING FURNACES

By Robert K. Zah1 1 , Larry A. Haas', and John Engesser 2



## ABSTRACT

A gas sampling survey was conducted to characterize the formation of nitrogen oxides in the iron ore pelletizing process. The nitrogen oxide, NO R , concentration was determined in various parts of two types of commercial furnaces, the Grate-Kiln and Straight-Grate, while producing conventional acid pellets as well as fluxed pellets. Process gases were found to contain 43 to 781 ppm NO„ by volume (wet basis) depending on the furnace and the sampling location. A range of 400-700 lb NO 2 /hr and 2.5 to 4.5 lb NO 2 /million BTU was measured depending upon the furnace type, its operating conditions, and whether acid or fluxed pellets were being produced. Generally, mass flow of NO was found to correlate with fuel flow to the process. Linear relationships between NO mass flow and fuel flow were found for some furnaces where conditions for NO formation were substantially similar. The emission rate normalized to fuel input was found to increase with fuel input only for one furnace. NO. formation in the pellet cooler was not supported by the measurements. The work was a collaborative effort between the U.S. Bureau of Mines and the Natural Resource Research Institute - Coleraine Minerals Research Laboratory as part of the Iron Ore Cooperative Research Committee's program. The work was partially funded by the Minnesota Department of Natural Resources - Minerals Division, the Iron Ore Cooperative Research Committee as well as the participating pelletizing plants.

Robert K. Zahl and Larry A. Haas, Metallurgist and Research Chemist(retired), respectively, Twin Cities Research Center,U.S. Bureau of Mines, Minneapolis, MN

2 John Engesser, Engineer, CMRL/NRRI, U of M, Duluth, MN

1

## 1. INTRODUCTION

Many high temperature mineral and metallurgical processes generate oxides of nitrogen by virtue of their reliance on combustion. Nitrogen oxides, NO R , were classified as criteria pollutants under the National Air Quality Standards of the Clean Air Act passed by Congress in 1990. Consequently, greater emphasis has been given, Nationally, to the determination and reduction of NO,, from all sources. Most of the previous nitrogen oxide research was conducted with simulated gases from mobile (mobile vehicles) and stationary sources (power plants). No research has been conducted on the formation and destruction of nitrogen oxides in iron ore pelletizing processes.

The iron ore pelletizing process has been well described by a number of authors ( /-7) 1 . Pellet furnaces, besides burning fuel, modify the chemical content of the iron and alkaline-earth oxides. Pelletizing, in turn, significantly modifies the products of combustion. The process operates at elevated temperatures, normally 2400-2475°F, requires high rates of heat transfer, and is characterized by gases with high oxygen contents at high temperatures for long residence times. Iron ore pelletizing includes the following sequential steps: drying, preheating, induration, and cooling. Induration is defined as "heat hardening" and includes oxidation and sintering. The major portion of the heat is added in the induration step and the major portion of the air is added in the pellet cooler. The majority of NO„ formation is presumed to be caused by fossil fuel combustion in the induration step but high temperatures exist in the cooler and the process is significantly different if fluxed pellets are produced.

There are three types of pelletizing furnaces which heat the pellets by different mechanisms. In the two types of furnaces investigated in this study, the Grate-Kiln and the Straight-Grate, combustion takes place with large amounts of preheated, high temperature air in a high temperature refractory-lined chamber. The air:fuel ratio is typically 250-350% of stoichiometric requirements.

No systematic studies have been conducted but it is well known that several hundred parts per million are emitted 

### (8) by the pelletizing process. To better characterize the process, gas samples from various process locations were analyzed. Both the Grate-Kiln and the Straight-Grate furnaces were sampled during production of conventional "acid" pellets and fluxed pellets. The production of fluxed pellets involves adding

References are given by italic, underlined numbers in parentheses.

3limestone and dolomite to the iron ore concentrates prior to pelletizing.

The most effective way of preventing the emission of NO into the atmosphere is to suppress it at the source. The most obvious method to suppress the formation of NO in any furnace would be selection of "low NO N " burners. The pelletizing process, however, embodies a unique combustion environment and demonstrated "low NO." burner technology is not commercially available. To aid development of such technology, a systematic base-line study is required to 1) quantify NO production at different points in the processes and 2) understand the conditions most responsible for NO formation. It is for these reasons that the U.S. Bureau of Mines, as part of its Environmental Research Program, and the Colleraine Minerals Laboratory of the Natural Resources Research Institute of the University of Minnesota, Duluth collaborated to conduct a gas sampling survey. This research was funded by The Iron Ore Cooperative Research Committee, the Minnesota Department of Natural Resources, the U. S. Bureau of Mines and the participating companies in Minnesota's pelletizing industry.

Phase I involved simulating the pellet cooler in the laboratory as well as test some of the gas sampling equipment to be used in the field survey (9). The pellet cooler has the most hot air and could possibly form nitrogen oxides. Localized areas of the pellet bed in the cooler could have high concentrations of magnetite and in the presence of air, considerable oxidation can occur which can generate a lot of localized heat (5). The pellets are porous and temperatures greater than in the bulk pellet bed, 2280°F, could exist. Catalytic reactions were also considered possible. The laboratory study involved heating a bed of pellets in a 17 kilowatt electric furnace. The configuration is shown in figure 1.1. The pellets were oxidized at bed temperatures up to 2450°F. No NO was detected unless a small oxygen-natural gas flame was present. The results of these experiments were taken as evidence that NO will not be produced in the pellet cooler of a pelletizing plant.



### FORMATION OF NITROGEN OXIDES At least six stable oxides of nitrogen have been reported. The order of decreasing stability of the three most stable oxides above 600° C are: nitric oxide (NO), nitrogen dioxide (NO 2 ) and nitrous oxide (N 2 0).

In this report, NO is defined as a mixture of NO and NO 2 . This mixture is the most common method of defining NO although in the past, the nitric acid and nitrate ion content have also been included. These gases usually occur together because they are interconvertible in the atmosphere (10).

4NO 2 can be converted to NO and atomic oxygen by ultraviolet sunlight. The atomic oxygen can react with air to form ozone which in turn can oxidize NO. These reactions, shown in figure 1.2, have been referred to as the photolytic NO 2 cycle (11).

Fuel combustion is the major source of man-made oxides of nitrogen which are produced in approximately equal quantities by stationary and mobile sources. In the combustion process, NO is the main direct product and only subsequently is the NO partially oxidized to NO 2 . Experimentally NO is measured but the emission rate is usually expressed as NO 2

. NO can be formed by three mechanisms: (1) thermal, (2) fuel, and (3) prompt (12-14). "Thermal" NO results from the fixation of the molecular nitrogen with atomic oxygen at high temperature. It has been reported that the quantity of thermal NO„ formed usually increases exponentially as the peak flame temperature is increased above 2200°F (15). Some of the commonly accepted mechanisms for the thermal NO formation are referred to as the Zeldovich exchange reactions:

( 1 ) N 2 + 0 = NO + N (2) 0 2 N = NO + 0 (3) N + OH = NO + H

Reaction (1) is the rate-limiting step and it occurs at significant rates only at temperatures greater than 2750-2800°F. Kinetic calculations indicate that these reactions essentially cease when temperatures fall below this range. Atomic nitrogen and oxygen are formed by thermal dissociation of molecular nitrogen and oxygen. The concentration of the atomic species is known to increase with increasing temperature. In hydrogen-air flames reactions 1-3 are the only reactions available to consume atomic oxygen whereas in hydrocarbon-air flames, atomic oxygen can react with hydrocarbon radicals. Consequently, hydrogen-air flames generally produce more NO. than hydrocarbon-air flames

"Fuel" (also referred to as "chemical") NO results from the oxidation of the nitrogen compounds in the fuel. Generally, gaseous fuels, such asnatural gas and propane, contain very low concentrations of chemicallybound nitrogen. However, in the combustion of coal or fuel oils, significant quantities of fuel-bound NO can be generated.

A third and lesser known type of NO formation is called "prompt" NO R

. This NO is formed from hydrocarbon radicals (CH, CH 2 , etc.) generated from fuel fragmentation which readily reacts with nitrogen in the combustion air to form the hydrogen cyanide (HCN) intermediate. The

5HCN then reacts with oxygen and nitrogen in the combustion air to form NO as shown by the following equations:

(4) CH• + N 2 = HCN + N (5) HCN + OH = CN + H 2 O (6) CN + 0 2 = NO + CO

Prompt NO R formation is usually proportional to the number of carbon atoms present in the fuel and it has weak temperature dependence. Prompt NO R forms early in the combustion process, too early to spatially resolve a concentration profile in laboratory experiments. The mechanism is generally thought to be significant only in fuel-rich flames which inherently produce low NO R levels. However, prompt NO R may be important in large industrial turbulent diffusion flames (16,17) even when the overall combustion is oxidizing. The prompt mechanism may dominate on the fuel-rich side of the flame front and the thermal mechanism dominates on the fuel-lean side.

N 2 0 is the third most common nitrogen oxide and is also referred to as dinitrogen oxide, nitrous oxide or laughing gas. Its apparent formation in combustion is thought to be due to artifacts of the sampling technique. The atmospheric concentration in the troposphere of this long-lived gas (estimated atmospheric lifetime of 100 years) is about 0.3 ppm. Measurements taken during the past two decades have shown that N 2 0 concentration is rising at about 0.25 pct/yr. The concentration of this gas was not determined in this study.



### TOXICITY Even at low levels (0.3 ppm) of NO R , clinical studies have shown- that asthmatics experience decreased lung function. NO 2 is the most toxic of the nitrogen oxides. In Japan the maximum 'allowed ambient concentration 0.02 ppm. The Clean Air Act Amendments (CAAA) reported that 0.05 ppm NO 2 can be harmful. NO is not very soluble in water but it is deposited on vegetation by being oxidized to nitric acid. NO R -dominated acid fogs have been recorded with a pH reading of an astounding 1.7 value. Nitrogen oxides have been more responsible for the acidity in California than sulfur dioxide. In California, the NO R emissions exceed sulfur oxides by a factor of four. Acid precipitation has been reported to have cause extensive forest damage in Germany (EPA/600/S7-90/002)

NO R in the presence of sunlight and free radicals of volatile organic compounds (VOC's) can form the most pervasive pollutant, ozone (18,19). The reaction produces photochemical smog which can result in climatological changes. The precise mechanism that is involved in the

6formation of smog is not clearly understood but it is known that NO. plays an important part. Presently, ozone-smog pollution exists in large parts of our nation in concentrations unhealthy to breathe. Ozone reduces the pulmonary functions and causes asthma attacks, cough, and chest discomfort. Ozone has been found to be damaging to human health in concentrations as low as 0.1 ppm. It is also harmful to vegetation and the Congressional Research Service estimates that the damage to crops and forests may be as high as $4.3 billion annually. The depletion of the stratospheric ozone layer is expected to increase skin cancer, cataracts and birth defects, as well as decrease crop yields.

In urban areas and for short periods of time, NO 2 can exceed 150 ppb. The average NO. ambient level for both NO and NO 2 ranges from 20 to 40 ppb. The nearly constant NO levels are due to the relatively short lifetime of NO (between a few minutes and a few days). This is not true for N 2 0, which has a long lifetime (100 to 200 years) in the troposphere (1.4).

Nitrous oxide is the most abundant nitrogen oxide in the atmosphere and is not directly hazardous to human health but it is a "greenhouse gas" that may contribute to global warming. It also is one of the gases that destroys stratospheric ozone.


## EMISSION REGULATIONS The nitrogen oxides that are considered the main contributors to environmental problems are NO and NO 2 . California and a number of other states are stringently regulating NO emission sources (15). The fee in Minnesota for NO. emissions is $18.30 per ton emitted 

### (8.20).

Since 1971, new boilers come under Federal regulation for NO emissions, but more recently, regulations on all combustion sources have become more stringent (2 1). NO is one of six chemical species classified as criteria pollutants under the National Ambient Air Quality Standards (NAAQS) of the Clean Air Act Amendments; this Act, passed by Congress in November 1990, was the most comprehensive legislation ever enacted in the area of air pollution. Congress included a milestone in Title I of the CAAA and after 1996, a 3 %/yr reduction of the NO./VOC ratio is required in serious, severe and extremely polluted areas. By the year 2000, NO emissions must be cut by 2 million tons to reach an annual level of 11 million tons 

### (22).

NO reductions fall under Title I (ozone nonattainment areas) and Title IV (acid rain) of the CAAA. In special ozone transport regions (e.g., between District of Columbia and Maine), sources emitting more than 100 tons of NO per year were expected by the U.S. EPA to expand the NO measuring

7equipment between 1992 and 1995 by 100 million dollars yearly (22). By year 2000, every utility is required to have NO,, equipment to meet the requirements of Title IV. The purpose of Title IV of the 1990 CAAA is to decrease the 1990's NO,, emissions by approximately 2 million tons/year. Most of this reduction will come from the utilities ( 18).

Section III of the CAAA directs the New Source Performance Standards (NSPS) to periodically review and tighten the standards as new technology is developed. In 1990, the NO,, limit for residual-oil-fired industrial package boilers built after July 6, 1984 was set at 172 ng/J (0.3956 lb/10 6 BTU) on a NO 2 basis which corresponds to about 330 ppm. The most severe standards are those of the Southern California Air Quality Management District (SCAQMD) which required new sources to comply with Best Available Control Technology (BACT). In 1992 the SCAQMD considered BACT to be about 40 ppm NO,, (at 3 pct 0 2 ) or 0.05 lb/MM BTU. The NO x emissions for new boilers with a capacity of 20,000 Btu/h and lower is 30 ppm; those over 20,000 Btu/h are limited to 9 ppm. Existing boilers are generally limited to 40 ppm.

Low toxic emission maximums are expected to proliferate as regulation stemming from the CAAA are promulgated. Title II of the CAAA targeted the industrial emissions. The Act established a specific timetable for the EPA to promulgate emission limits for the criteria pollutants and it was intended to reduce these emissions by 70-90 pct.

Enforcement has been left up to the states or local agencies, but they must set up standards that are within the Federal guidelines. The basic specification is that "ambient" NO,, must be less than 0.05 ppm. This is an allowed average over a 24-hour period, not to be exceeded more than once per year. Relating ambient standards to "source" (in stack) values is complex. Source review programs include new source performance standards, prevention of significant deterioration in attainment areas, and non-attainment area bubbles, offsets, trading, or banking.

All NO,, generating plants that have the potential of emitting 100 tons per year must meet the compliance deadline of November 1996.

If the emission level is expressed per unit of weight of toxic per unit weight of fuel used or product produced, then the size of production operation and the dilution rate is not as important. The EPA standard for new nitric acid plants is 3 pounds NO,, per ton of nitric acid produced. For incineration wastes, an NO. emission of less than 0.2 lb NO 2 /MMBTU has been targeted.

8

## EMISSION CONTROL There are two alternatives to obtain low NO x emissions: either prevent its formation or remove it from the off-gases and a variety of solutions have been proposed (22-25). Its formation may be decreased by minimizing the residence time of the gas at the peak temperature, keeping the temperature as low as possible, and by minimizing the availability of oxygen for its reaction with nitrogen. Various methods have been proposed for incorporating these principles in combustion processes. Most burner manufacturers offer products described as "low NO." burners. The manufacturers recognize that all combustion environments are different and a burner design that does reduce NO x formation in one environment may not in another. The design strategies may involve staging the mixing of air and fuel to reduce peak flame temperature or quenching the reactions by rapid mixing with air or combustion products. These strategies are often successful where furnace temperatures are relatively low and where near-stoichiometric conditions prevail. Such conditions do not exist in pelletizing furnaces.

Gas turbines represent a combustion environment somewhat similar to pelletizing furnaces. Temperatures are 2600-2800°F at 15% 02. In traditional non-premixed combustion NO x emissions are approximately 200 ppm. Lean premixed combustion techniques, however, can result in emissions approximately 20 ppm (17). The techniques employed in stationary gas turbines are possible because preheat temperatures are limited to 600-700°F. Natural gas and air at 2100-2200°F will auto-ignite precluding premix techniques. Extraordinarily rapid mixing would be necessary to establish lean combustion in non-premixed systems. Thus, iron ore pelletizing presents a unique combustion environment where none of the established "low NO x " burner strategies apply.

A wide variety of proprietary post-combustion NO x control technologies are being marketed. These include injection of ammonia or urea with and without a catalyst. The performance reported by vendors for many of these systems have not been well documented in the independent public literature but generally require long residence times at narrow temperature ranges. Little primary data are available to demonstrate the actual applicability and long-term operation performance of the current generation of NO x control technologies.

9

## 2. EQUIPMENT AND PROCEDURES

GAS SAMPLING PROBE The sampling probe used in the field study is similar to the probe shown in figure 2.1. The probe was 10 ft long and had a diameter of 1 5/8 inches. It was supported by a rail when inserted into a sampling port. The probe can withstand high temperature combustion environments outside a flame envelope if the water flow is maintained at 5 gallons per minute. If a controlled water flow is supplied to the outer jacket, the drain water can exit at temperatures greater than the dew point of the gas sample. A filter and liner tube, shown in figure 2.2, is supported within the sampling tube. The liner could be stainless steel, as used in this study, or quartz if secondary reactions within the gas sample are catalyzed by the steel. Some laboratory tests (9) were conducted with a 6 mm quartz liner tube but no catalytic reactions were noted.



## EMISSION MONITORING SYSTEM The continuous emission monitoring, CEM, system that was used for the pelletizing plant gas survey was assembled by PACE Associates Incorporated of Warrington, Pennsylvania. The CEM System is packaged in a self-contained 12 foot by 8 foot by 8 foot shelter. The shelter is mounted on a double axle trailer for over the road transport. The shelter is provided with electric heaters and an air conditioner for maintaining proper working temperatures for the instrumentation.

The CEM contains a Wet/Dry Gas Conditioner, a NO-NO. gas analyzer, a SO 2 gas analyzer, a 02 gas analyzer, a CO - CO 2 gas analyzer, a 32 channel recorder/datalogger and a computer. External to the CEM is a 300 foot heated umbilical cord for delivery of the emission gas to the CEM and an air compressor for providing dry instrument air to the CEM.



## CEM INSTRUMENT DESCRIPTIONS Heated Umbilical Cord. The gas sample is transported to the CEM through a 0.25 inch diameter teflon tube within an insulated and heated umbilical cord which was maintained at 180 degrees Fahrenheit.

Wet/Dry Gas Conditioner. The conditioner first removes particulate from the gas stream. After filtration the sample is divided into two parts. One portion is conditioned on a wet basis and the other on a dry basis.

The portion of the sample that is conditioned on a wet basis is accurately diluted with clean dry instrument air (10:1 dilution). This reduces the dirt load and the dewpoint of the sample and prevents the deposition of

10particles and the formation of condensate in the analyzers that receive the sample. This diluted sample was delivered to the NO-NO, gas analyzer and the SO 2 gas analyzer.

The portion of the sample that is conditioned on a dry basis is drawn through a permeation dryer which drys the sample by transporting water vapor continuously across a permeable membrane. The dried sample has a dewpoint of approximately 35 degrees Fahrenheit. This sample was then transported to the 0 2 gas analyzer and the CO-0O 2 gas analyzer.

NO-NO. Gas Analyzer. The NO-NO. gas analyzer is a Model 10A Chemiluminescent NO-NO. Gas Analyzer manufactured by Thermo Electron Corporation of Hopkinton, Massachusetts. The instrument can measure NO and total NO,,. The instrument measures the quantity of NO in the gas stream via the chemiluminescent process. When total NO,, is determined, the NO,, is thermally converted to NO and the measurement of NO is then performed via chemiluminescence. The instrument provides a meter readout and a voltage output.

512 2

Gas Analyzer. The SO 2 gas analyzer is a Model 40 Pulsed Fluorescent

. SO 2 Analyzer manufactured by Thermo Electron Corporation of Hopkinton, Massachusetts. The principle of the SO 2 analysis is based upon the measurement of the fluorescence of SO 2 produced after the absorption of ultraviolet radiation. The instrument provides a meter readout and a voltage output.

0O Gas Analyzer. The 0 2 gas analyzer is a Model IR-2200 manufactured -2 by Infrared Industries, Inc. of Santa Barbara, California. The instrument is an electrochemical analyzer with a disposable sensor cell. The instrument provides a digital readout and a voltage output.

CO-CO 2 Gas Analyzer. The CO-0O 2 gas analyzer is a Model IR-732 manufactured by Infrared Industries, Inc. of Santa Barbara, California. The analyzer contains dual-cell detectors and uses non-dispersive infrared gas analyzers for measuring the gas concentrations. The instrument simultaneously measures both CO and CO 2 concentrations in the gas stream and provides a meter readout and a voltage output for each gas.

32 Channel Recorder/Datalogger. The recorder/datalogger was manufactured by Cole-Parmer. The datalogger is programmable and has a RS-232 output which is connected to a computer. The voltage output from each analyzer is collected by the datalogger and is transferred to the computer via the RS-232 output. The recorder/datalogger also maintains a continuous record of each analyzer output via a strip chart recorder.

11Comauter. The computer used to collect the analyzer data is a CompuAdd (IBM Compatible) with 640 kilobytes of memory and a 20 megabyte hard drive. The computer has both a 3.5" disk drive and a 5.25" disk drive.

Calibration Gases. Calibration gases for NO-NO., SO 2 , 0 2 , CO, and CO 2were purchased from Matheson Gases of Joliet, Illinois. A certified NONO. standard, SRM-2630, was also purchased from The National Institute of Standards and Technology to check the Matheson NO-NO. calibration gases. The zero gas (Utra High Purity Nitrogen) was purchased from Genex Corporation.

CEM °aeration. Prior to the beginning of an emission gas sampling test, the instruments in the CEM were actuated and allowed to warm up for an hour. The instruments were calibrated by using the zero gas and the calibration gases. After the calibration of each instrument was complete, the zero gas and calibration gases were circulated to the instruments. The outputs of the instruments were recorded by the computer. The emission gas sampling and analyses then began. The outputs from the instruments were recorded by the computer at three minute intervals. At the end of the sampling test period, the calibration gases were circulated to the instruments and outputs were recorded.



### PROCESS GAS FLOW MEASUREMENT Measurement of the process gas flow at the sampling point was made with a multi-point pitot tube traverse. A 10 ft long "S" type pitot tube was available for the study. The traverse was made in accordance with standard practice for large ducts except that long up- and down-stream pipe lengths were not available. The flow measurements were generally made at 1-2 duct diameters from a fan outlet. The flow measurements were made by personnel from the participating pelletizing plant who also recorded the fan's motor current draw during the traverse.



### MASS FLOW CALCULATION PROCEDURES When the process gas flow can be measured at the sampling point, the mass flow of NO. is relatively simple to determine. The wet-basis gas analysis is used to estimate the molecular weight or density of the gas. The volumetric flow of the gas and the NO analysis is then used to calculate the volumetric and mass flow of NO 2 . The gas at the sampling point must, of course, be representative of the upstream fuel flow if the NO mass flow is to be normalized to the fuel input.

When the flow of process gas at the sampling location is not known, the gas analyses can be used to calculate the mass flow of NO. if the fuel flow

12and pellet feed rates are known. This is the only method that could be used for most of the gas sampling campaigns. Process gas flow rates were available for some of the tests conducted on the Grate-Kiln making it possible to compare the two methods. The pellets are a source of H 2 O and CO 2 and they consume 0 2 . A general equation can be written using methane in place of natural gas:

F*CH, + 1 ■ 1*(a0 2 +bN 2 +cCO 2 +dH 2 O) - P1 + P2 + P3 ==>

(Nc+P2+F)*CO 2 + (Nd+P3+2*F)*H 2 0 + (Na-P1-2*F)'0 2 + (Nb)*N 2 (1)

The coefficient F is the number of moles of methane per unit time. The coefficients a, b, c, d provide the analysis of atmospheric air and N is the number of moles of air per unit time. Since moisture in the air is variable, a = 0.20946*(1-d), c = 0.00033*(1-d), and b = (1-a-c-d) are used in this report. For typical moisture levels and ambient temperatures d will range from 0.003 to 0.011. P1 represents the oxygen consumed by the pellets during the sampling period and is expressed as a flow of moles of oxygen per unit time. P2 represents the CO 2 driven off the pellets, moles of CO 2 per unit time, and is dependent upon the amount of carbonates and other sources of carbon present. P3 represents the moisture driven off the pellets, moles of water vapor per unit time.

Ideal gas behavior was assumed and volumetric flows at the standard reference condition of 70°F and 1 atmosphere were used for all calculations. All volumetric flows given in this report are given for standard conditions. Ideal gas densities were used for the calculations.

Depending upon the sampling location some of the pellet factors may be near zero or justifiably less than the maximum theoretical amounts calculated from pellet analyses. Also, the residence time of the pellets in the process is 40-60 minutes and the gas residence time is 3-10 seconds, depending on sampling location, and it may be necessary to choose the appropriate averaging periods to obtain P1, P2, and P3. For example, it may be necessary to compensate for the fact that the H 2 O is driven from the pellets 3-15 minutes, depending on the furnace, before the CO 2 begins to be driven off and the pellets begin to consume oxygen. If the feed rate is fairly constant, a long period average may be used with reasonable confidence.

When the total flow of process gas at the sampling location is calculated from the 0 2 and CO 2 analyses, the flow will include all upstream air leaks into the process. Air leaks in the sampling system will cause the process gas flow to be over-estimated. This procedure is only valid if all upstream process gases to the fuel source pass the sampling location. Gas handling

13in the two pelletizing processes is fairly complex and this procedure is not valid for all sampling locations without estimating bypass flows.

To calculate the flow:

N(R) = {R * (P2 + F) + P1 + 2 * F}/{a - Rc}, (2)

where R is the ratio of 02/CO2 measured at the sampling location. In principal, the flow can also be calculated from either the CO2 or 02 analyses using:

N(CO2) = (11/11 * (P2

- P1

- F) - F - P2)/(c - M1 * (1

- d)) (3)

or
N(02) = (M2 * (P2-P1-F) + 2 * F + P1)/(a - M2 * (1-d)). (4)

where M1 and M2 are the measured values CO2 and 02, respectively, in units of volume fraction. Care must be taken when using these two equations since neither is fully representative of all the parameters in equation 1. When the calculated air flows are different, a measurement error is indicated.

By setting equation 3 equal to equation 4 it is possible to solve for one parameter or measurement in terms of all others. For example, after solving for M2 it is possible to construct the theoretical combustion curve over the range of CO2 analyses observed. This procedure is useful to test the internal consistency of the data as well as indicate systematic errors. For measurements in volume fraction, the equation is:

M2 = ati * fa * (P2

- P1

- F) + (1-d) * (P1 + 2 * F)1 - a * (P2 +F) - c * (P1 +2 * F)1 { c * (P2-P1

- F) - (1-d) * (P2+F) (5)

Assuming ideal gas behavior, the total moist flow at the sampling location will be (N+F-P1 +P2 + P3) and the mass flow of NO., expressed as NO2 is:

NO2, mass/time = Flow * NO x (measured) * Density of NO2. (6)

In this study the NO„ was measured on a wet basis. If a dry-basis analysis is used the flow must be the dry flow, (N * (1-d)-F-P1 +P2). N may be calculated if the process gas and fuel flows and pellet parameters are known. Then the gas analyses may be calculated using:

CO2, dry vol % = 100 * (Nc + P2 + F)/(N * (1-d)

- F-P1 + P2), (7)

14and

0 2 , dry vol % = 100 * (Na-2*F-P1)/(N*(1-d)-F-P1+ P2). (8)

Moisture in the process gas may be calculated using:

H20, wet vol % = 100 * (Nd + P3 + 2*F)/(N + F-P1 + P2 + P3). (9)

Equations 3 and 4 or 7 and 8 may be used to validate the calculation of N using the ratio, R, but the preferred method is to calculate the theoretical combustion curve for a set of pellet parameters and compare the results on a graph of 0 2 vs CO 2 as well as calculate the process gas mass flows. If the calculations can not be validated the gas analyses or the pellet parameters are probably in error. Generally it is always possible to adjust the pellet parameters to force the calculations into agreement but the adjusted parameters and/or the process gas flow may be unreasonable. In that case the gas analyses are probably in error.

The pellet parameters P1, P2, and P3 are determined from a chemical analysis of the pellet feed and product as well as the feed rate. Pellet oxidation is the result of oxidizing magnetite, Fe 3 0 4 , to hematite, Fe 2 O 3 , and is determined from the ferrous iron, Fe+ 2 , and total iron, Fe', analyses of the feed and product expressed as mass fractions. Because pellet chemistry can be altered in a number of ways two calculations are involved. The maximum theoretical fractional weight gain of dry feed due to oxidation is determined from the ferrous iron content of the feed and the ratio of the molecular weight of oxygen and the atomic weight of iron:

Gain = Fe+ 2 (0.25*31.9994/55.847). (10)

The fractional degree of oxidation of the final pellet product is:

Oxidation = 1 - ((3*Fe+ 2 )/Fe t )).

Knowing the dry feed rate during the sampling period:

P1 = (Gain)*(Oxidation)*(Feed)*(1/0 2 density). (12)

A typical value for (P1/F) is 3.15 scf 0 2 /scf Fuel which means that the pellets consume 30-35% more oxygen than is consumed by the fuel.

The manufacture of fluxed pellets involves the addition of calcium and magnesium carbonates. The carbonates are calcined in the process and CO 2 is driven off. Other sources of carbon include organic binders,

15carbonates in the ore and process water, and residual flotation reagents. Conventional acid pellets contain a few tenths of a percent carbon whereas fluxed pellets contain 1-1.5 % carbon. The maximum theoretical rate of evolution of CO 2 is determined from the carbon analysis of the dry feed and the ratio of the molecular weight of CO 2 and the atomic weight of carbon:

P2 = (C)*(44.010/12.0112)*(Feed)*(1/CO 2 density). (13)

Residual carbon is often present in the fired pellets, especially fluxed pellets. The degree of calcination may be estimated by using ratios of C/Fe t or C/Si. P2 is then multiplied by the degree of calcination. Carbon in the green pellet feed may vary from 0.2 to 1.5 percent and typical values of (P2/F) will range from 0.35 to 3.1 scf CO 2 /scf Fuel. During acid pellet production the pellets give off CO 2 equivalent to 55-65% of the amount of CO 2 formed by combustion. The typical range for fluxed pellets is 190- 210%. If carbon is present in small amounts as a hydrocarbon then it will also consume oxygen but the effect will be masked by variations and uncertainties in the Fe+ 2 analysis.

The parameter P3 is simply:

P3 = (Pellet Moisture)*(wet Feed)*(1/H 2 0, density). (14)

Typical values of (P3/F) vary from 10-15 scf water vapor/scf fuel or 5-8 times the amount formed by combustion. Chemically bound water that is driven off at high temperatures may be present on the order of a few tenths of a percent. Based on that level (P3/F) would be approximately 0.3-0.5 scf water vapor/scf fuel or 15-25 % of the water produced by natural gas combustion and about the same contribution as moisture in the atmosphere on a typical day. Ignoring chemically bound water would have a less than 1% effect on the NO. mass flow calculation. Moisture in the atmosphere is easy to determine and it was included in all calculations in spite of its small effect. Atmospheric moisture and other weather data relevant to this study are given in table 2.1

Clearly, depending on the sampling location, the gas analyses are strongly dependent on the pellet feed rate, pellet moisture, degree of oxidation, and the amount of carbonates present. For fluxed pellets variations in the feed can be much more important than variations in the fuel. Fuel efficiency of the pelletizing furnace is also a factor. Variations in P1, for example, will be more important as efficiency is increased.

NO mass flows are often normalized to combustion products containing

163% 0 2 to facilitate comparisons among fuels and furnaces. Since gas chemistry is significantly altered by the pelletizing process and is not simply a function of combustion, such a normalization procedure would have little meaning.



### ERROR ANALYSIS When measured process gas flows are used to determine the mass flow of NO,, the main sources of error are the flow measurement and the NO. measurement. The NO,, mass flow errors are directly related to the errors in these measurements. Volumetric flow measurements depend on gas density and the overall gas analysis is also a source of error. Moisture in the gas can be determined but its measurement is often difficult and prone to relatively greater error. At a sampling location where P3 has the maximum effect, variations in pellet feed rate and moisture may have a significant affect on the process gas density. In the pelletizing process the dry gas density is close to that of air. For air containing 10% moisture, an increase to 15% would lead to a decrease of 2.7% in the velocity measurement with a pitot tube. For an ill-conditioned flow, the pitot tube traverse itself is a major source of error. In this report an error of ± 10% was assumed for all process gas flow measurements. There was insufficient information to determine if the measurements contained any positive or negative bias.

When process gas flows are not available, the gas analyses and the parameters in equation 1 are the sources of error. The use of methane for natural gas introduces an error into the calculations. Several data sets were analyzed using the natural gas analyses and the results were compared with calculations using methane. Depending on the effective air:fuel ratio at the sample location the error in using methane was found to be -0.002 to -0.11 percent for the mass flow calculations. For fluxed pellet production the use of methane would contribute a + 0.2% error in the mass flows. In the interest of keeping the equations simple, it was decided to ignore these errors. The magnitude of these errors is less than expected instrument error and is much smaller than the uncertainties associated with the pellet parameters. Ignoring the moisture in the air would contribute a -0.4 to -0.8 percent error and ignoring the CO 2 in the air would contribute approximately a -3.0 percent error for acid pellets. Since the CO 2 cannot be ignored it did not seem unreasonable to include the moisture in spite of its small contribution.

Measurement errors are to be expected but the final error in NO,, mass flow is not a simple function of the independent measurements. A sensitivity analysis was conducted using data obtained for acid pellet production in a Grate-Kiln (10/21/93). Equations (2) and (5) were used to calculate the

17NO mass flow. Each measurement and parameter in the equations was independently varied by + 5%. The results are shown in table 2.2 for the most important parameters. The combined effect of changing all parameters is given along with the maximum effect of a ± change. The values for pellet moisture are valid for sample locations where the moisture has the maximum effect. For fluxed pellet production the pellet parameters are more important. For the data obtained on Oct 4, 1993 a + 5% error in estimating P2 would lead to a + 2.3% error in the mass flows. These values should only be used as a guide. Every data set appears to have different sensitivities to the parameters.

A sample-line air leak would have the effect of increasing the calculated air flows as well as result in a low value for NO.. The effect of a sample-line air leak was investigated using the data set obtained on Oct. 21, 1993, sample GKA-6b. For example, to correct for an air leak that would have raised the 0 2 measurement 1.025 times the actual value, the CO 2 and NO values would have to increase by a factor of 1.135 but the final NO mass flow would increase by a factor of only 1.018 when calculated with equations 2 and 3. When using measured process gas flows such an air leak would lead to a -13% error in the NO mass flow. A further discussion of the effect of a sample-line air leak is given in section 5 for the Grate-Kiln producing fluxed pellets.

18

## 3. RESULTS: GRATE-KILN PRODUCING ACID PELLETS

FURNACE DESCRIPTION The Grate-Kiln pelletizing furnace consists of a traveling grate that is used to dry and preheat the pellets, a rotary kiln to further heat the pellets, and an annular cooler to cool the pellets and recuperate heat for the process. The process flow sheet and sampling locations, numbered 1-6, for this furnace are shown in figure 3.1.

The grate includes three zones, the first and second down-draft-drying (DDD) zones, and the preheat (PH) zone. Wet, green pellets are fed to the 14.5 ft wide grate to a bed depth of 5-6.5 in. Pellets are completely dried in the 72 ft long drying zones. Pellet temperature begins to climb above 212°F in the 56 ft long PH zone. Depending on the location in the bed, the pellets attain temperatures of 800-1803°F and are generally 65 pct oxidized and 60-90 pct calcined when they discharge into the kiln.

The rotary kiln is 130 ft long with an inside diameter of 20 ft. The pellets attain a temperature of 2370-2460°F. Very little oxidation (<5 pct) takes place in the kiln but the calcination could be completed. The pellets discharge into the cooler. The kiln burner was configured for natural gas, oil, or coal firing. Only natural gas was used during this test program. The burner consists of concentric tubes with air in the center, gas in the first annulus, and air in the second annulus. Both air flows are referred to as primary air. Air flow through the central nozzle was 72 mcfh and flow through the outer annulus was 84 mcfh. The flows are held constant and do not vary with the fuel. Consequently, the primary air varies between 10 and 12% of stoichiometric requirements. The nozzles are designed for highly turbulent mixing. The burner produces a typical turbulent-diffusion flame. The visible flame envelope was not tight and generally filled a roughly conical volume 5-15 ft in diameter and 25-35 ft long.

The annular cooler is essentially similar to the grate but arranged in a circular configuration. Two fans supply air to cool the pellets. The hottest air is directed into the kiln, some directly up into the kiln hood but most is directed above and along the center-line of the kiln with a large duct. The kiln burner is located below the recuperated cooler air duct. The final 30- 35% of pellet oxidation is completed in the cooler. Consequently, the bed temperature in the cooler increases before the pellets begin to cool. Due to the higher temperatures experienced by the pellets oxidizing the most, the final 5-10% of the calcination also occurs in the cooler.

Gas samples were taken at three locations during the period October 18- 22, 1993. The samples are identified with the prefix GKA representing

19

### "Grate-Kiln producing Acid pellets". The waste gas fan outlet, sample port 6, was sampled three times. Those samples are designated as GKA-6a, fib, 6c in the order they were taken. The summary of gas analyses are given in table 3.1. To avoid complex interactions in the NO„ mass flow calculations, all values were maintained with 5 significant figures even though only 3 significant figures is justified. The gas analyses are listed in Appendix A and are shown in figures 3.2-3.6. Plant operating data were also obtained at 3 or 5 minute intervals and are shown in figures 3.7-3.11. The natural gas flows were averages over the sampling interval, 3 or 5 minutes, reported at the end-time. Pellet analyses were provided as shift averages and are shown in table 3.2. Averages of plant operating data, gas analyses, and the maximum effect of the pellets for selected periods are given in table 3.3. The data set for this sampling campaign is the most complete. Equation parameters and the results for the combustion and mass flow calculations are given in table 3.4.

The waste gas and preheat fan flows were generally measured early in the gas sampling period and variations were estimated with the recorded motor current draw. Figure 3.12 shows the results of several measurements of the waste gas fan flow and a linear regression with the fan's current draw. Some of the data are from measurements made on the same machine when fluxed pellets were being produced. The fan's current draw would also be affected by the pressure drop through the pellet bed but this data was not recorded. Because of that and the scatter in figure 3.12 the uncertainty in the measured flow is probably ± 10-15%. Having measured values for the process gas flows for seven gas sampling periods makes it possible to compare the two methods for estimating the NO. mass flow. The measured flows were determined from the recorded fan current draw for the selected time periods. The measured process gas flows and associated NO x mass flows are given in table 3.4.



## DISCUSSION OF SAMPLES The gas samples, GKA-6a through GKA-6c, the waste gas fan exhaust, included all contributions from all fuel sources as well as the full effect of all the pellet parameters. All of the process gases are drawn through the waste gas fan. It was possible to designate five sampling periods for the three days spent at this location to calculate NO. mass flows. Certain plant operating conditions were purposely changed to form these five periods. This sampling location is characterized by modest temperatures but high moisture contents. In spite of a heated sample line moisture would condense and the line required repeated purging to continue sampling. Some of the sampling periods showed evidence that suggests air leakage into the sampling system but the sample, designated GKA-6b, is the most striking example. The gas analyses for this period shows a

20distinct "saw-tooth" pattern that exactly coincides with sample line purging. After each purge flow to the analyzers was restored, the oxygen analysis decreased stepwise and all other analyses increased. The average stepwise decrease in oxygen was 0.36 vol% implying an air leak that raised the average measured oxygen by a factor of 1.021. As noted in section 2, correcting for such an air leak would raise the calculated mass flow of NO. by 1.8% when computed by means of equations 2 and 5 and by 13 % when computed from the measured flows. Since the average, uncorrected, analyses were used to determine the results in table 3.4, the expected errors are not likely to be more than half these values.

The GKA-6b sample also poses a more difficult dilemma. Figure 3.13 is a plot of 0 2 vs CO 2 for all "G KA" gas samples. The lines on the graph represent the calculated theoretical combustion curves using the parameters in table 3.4 whereas the points are the gas analyses which form the apparent combustion curves. The 6b sample is obviously far off its theoretical combustion curve which is similar for all samples. The theoretical combustion curve can be made to coincide with the measurements only if 15-25% of the theoretical CO 2 evolved from the pellets and 100% of the theoretical oxygen was consumed. Unless the pellets happened to contain significantly less carbon during the sampling period, this is an unreasonable assumption and indicates that the gas analyses are in error. Those factors would also cause the calculated process gas flow to be unreasonably low. Although an air leak is known to be present, correcting for the leak would simply move the data points along the combustion curves and would not cause the apparent and theoretical curves to converge. The authors believe that the 0 2 analyses contain an offset error which accounts for most and essentially all the error in this data set. No calibration anomalies were noted and the authors were unable to determine the cause of this systematic error. Increasing all the 0 2 analyses by 6.8% would bring the measured values in agreement with the theoretical curve and increase the calculated NO. mass flow by a factor of 1.055. Of course the CO 2 analyses could also be in error but increasing the CO 2 analyses would cause the calculated process gas flow to be unreasonably low. Results based on the measured process gas flows would be unaffected by these calibration adjustments. The 0 2 data also exhibit a continual increase during the sampling period while the CO 2 and NO trends show a slight decrease suggesting a continual degradation of sample line integrity. The plant operating data, however, suggest that these trends may be real. The data were treated assuming the trends are related to the process and not an air leak.

Although the calculated process gas flow is much lower than the measuredvalue there are no obvious problems with sample G KA-6a. Sample GKA216c, however, may contain a small constant sample-line air leak. Such an air leak would explain the relative differences in the calculated and measured process gas flows for this location. If a sample-line air leak of 15.14% was present the "measured-flow" value would increase and the "calculated-flow" value would decrease to 592 lb NO 2 /hr to bring the measured and calculated flows into agreement. Other than the lack of agreement, there is no evidence of such an air leak.

The sample GKA-5, the exhaust of preheat fan 1A, should include the effects of pellet parameters P1 and P2 but not P3. It is assumed that the kiln exhaust gases and any air leakage into the furnace are fully and evenly mixed in the PH zone and pellet oxidation and calcination does not vary across the width of the grate. These assumptions allow calculations to proceed on the basis that the fuel flow to the kiln and process leak air flows are fully represented in this sample even though the flow is split between the 1A and 1B fans approximately in the ratio of 60:40. The flows were measured for both fans. The CO 2 analyses for this sample were recorded manually from the instrument dial and show virtually no scatter. It was assumed that the values are a reasonable estimate of the mean, however, the apparent and theoretical combustion curves do not coincide. Evidence from performing the mass flow calculations suggests that there may have been a bias in the sample where not all of the process leak air is represented or a greater proportion of the P1 flow is represented. More oxidation could have occurred on the 1 A side of the grate because of the slightly greater process gas flow. A calculation was performed assuming 60% of the fuel flow, 85.6% of the oxidation, and 66.5% of the calcination. The result was a very good correlation between the apparent and theoretical combustion curves and an NO. flow of 310.1 lb/hr through fan 1A. Since the source of NO was the kiln and 60% of the kiln flow is represented, the implied NO„ flow is 517 lb/hr and 3.34 lb/million BTU. This is greater than the values obtained from the unsplit flow shown in table 3.4 and in much better agreement with the value obtained using the measured process gas flow.

Sample GKA-3 at the kiln exhaust should represent all the fuel flow to the kiln but include only partial effect of pellet parameters P1 and P2. It was assumed that 35% of the oxidation and 5% of the CO 2 evolution takes place in the kiln and cooler. These values were suggested by the plant operators and are the result of a material sampling survey conducted two years earlier. Air leakage is known to enter the process at this location. Incomplete mixing of the leak air and kiln combustion gases at the sampling probe would yield a high or low value for the flow calculations. There is no obvious problem with the GKA-3 sample.

22

### RESULTS FOR THE FURNACE The results in table 3.4 are summarized in figures 3.14 and 3.15. The NO„ mass flows are given in figure 3.14 and the mass flows normalized to fuel consumption are given in figure 3.15. Based on the above discussion it is likely that all the values for the 6b sample should be increased by 5-10% due to a sample-line air leak and the slope of a line fitted to the data should decrease. The scatter among the data determined by measured and calculated process gas flows for this sample would be substantially the same. The agreement between the measured and calculated process flows is generally within ± 10% except for the 6a sample where the difference is 22%. The reason for this difference is unknown. As noted above the two values for the GKA-5 sample can be brought into closer agreement. The GKA-5 sample like the GKA-6 samples should represent the process. The reason for the lower NO. mass flows for the GKA-5 sample is not known but could have been due to a lower secondary air temperature.

The mass flow of NO„ is seen to increase with fuel flow. The values obtained with measured process gas flows show much less scatter and a more obvious fuel-NO„ relationship but it was not possible to judge which "method" yielded the more reliable results. Since the NO is produced only in the kiln, the conditions for NO. formation are substantially the same for all gas samples. The relationship with fuel flow can also be seen in figure 3.16. Although the pellets contribute CO 2 , their effect is to "base load" the CO 2 measurements and the variation is mostly due to the variation in fuel flow. The small variation in air:fuel ratio in the kiln is also primarily affected by fuel flow.

The data are not available for all sampling periods in this study, but variations in the secondary air temperature should also lead to variations in NO R . Secondary air temperatures during the GKA-3, GKA-6b, and GKA-6c sampling periods were 2184-2196°F, 2150-2164°F, and 2112-2118°F, respectively. Fuel use also decreased from 155 mcfh to 135 mcfh in the same order. These data are given in figures 3.7, 3.10, and 3.11. The combination of fuel and secondary air temperature probably contributed to the steepness of the apparent curve in figure 3.15. The fuel flows duringGKA-6b and GKA-6c were similar and the lower NO mass flow for GKA6c could have been due to a lower secondary air temperature.

In a private communication with the operators at the participating pelletizing plant it was learned that the NO. mass flow results calculated in this study were in agreement with stack samples taken to satisfy compliance with environmental regulations.

23

### 4. RESULTS: STRAIGHT-GRATE PRODUCING ACID PELLETS

FURNACE DESCRIPTION The Straight-Grate pelletizing furnace consists of a traveling grate with alternating updraft and downdraft zones to dry, preheat, indurate, and cool the pellets. The process flow sheet for this furnace is given in figure 4.1. A "hearth layer" of previously fired pellets is fed to the grate. The green pellets form a bed on top of the hearth layer. Total bed thickness is generally 13-15 inches with the hearth layer comprising 20-25% of the bed. The grate was 13.12 ft wide and each of the 38 windboxes was 6.56 ft long. The numbers in the figure are windbox numbers, ie. WB1- WB38. Baffles separating the hood zones were located as indicated in figure 4.1. The bottom of each baffle was approximately 13-14 in above the bed except at windboxes 7 and 24 where it was 2-3 in above the bed. Not labeled in figure 4.1 is the firing zone, WB17 through WB22, and the after-firing zone, WB23 - WB24.

Each combustion chamber had a diameter of 10.67 ft and a height of 34.83 ft. The two burners on this furnace were located at the bottom of each combustion chamber, centered with and firing along the centerline of the crossover duct between each combustion chamber and the firing zone hood. There are also two burners mounted at the top of each chamber which fire downward but these burners were not in use during the test. The lower burners reduce the heat loss from the combustion chambers, therefore requiring less fuel than the upper burners. The recuperated cooling air, secondary combustion air, is supplied to each combustion chamber at the top and the air and combustion products enter the firingzone hood through 6 ft ID openings horizontally near the top of the 15 fthigh firing zone hood. A separate supply of recuperated air enters above windboxes 23 and 24 (mostly 24) through a 6.75 ft ID duct vertically downward through the roof approximately 6 ft above the bed. Recuperated air is also directed downward through two 6.75 ft ID ducts in the 15 ft-high roof of the preheat zone.

Each burner consisted of a gas nozzle and an annular primary air nozzle. The gas and air mix at the nozzle and into a short mixing pipe before injecting into the preheated recuperated air stream. Neither the air nor the gas is swirled. The injection occurs at high velocity where the hot secondary air makes a right-angle turn toward the firing zone hood. The short mixing pipe had a diameter of 5 inches. The primary air flow to each burner was approximately a constant 130 mcfh and varied from 20 to 40% of stoichiometric requirements.

Gas samples were taken at two locations on April 20 and April 21, 1994.

24The sampling locations were approximately 3 ft above the pellet bed at the indicated windbox. The sample at windbox 18 was taken with the sampling probe angled steeply upward resulting in a sample that is considered well representative of the combustion products from the first combustion chamber. The primary air flow pressure to each burner was decreased by 50% for part of the WB18 sample period designated "low primary air". The summary of analyses are given in table 4.1. Pellet analyses are given in table 4.2. Plant operating data were available as 30 minute averages and are given in table 4.3. The gas analyses are given in Appendix B as well as figures 4.2 and 4.3. Secondary air temperatures were for this furnace were 1560 ± 10°F during the SGA-WB16 sampling period and 1610± 15°F during the SGA-WB18 period. Secondary air temperatures are normally 1650-1700°F for this furnace.



## DISCUSSION OF SAMPLES The gas sample SGA-WB16 in the hood above windbox 16 should be air slightly depleted in 0 2 and slightly enriched in CO 2 due to pellet oxidation and calcination in the cooler. It should represent the secondary combustion air for the process but include only part of the P1 and P2 flows from the cooling zone. Assuming no NO. is produced in the cooler there must have been some gas from the firing zone (FZ) in this sample. The sample location and configuration of the Grate makes it more likely that the FZ gases came from the windbox 17-19 region rather than the windbox 22-24 region. With that assumption in mind, a simple volumetric ratio of the NO. values in table 4.1 implies that 6.50% of the sample at windbox 16 is gas from the firing zone. The average analyses excluding SGA-WB18.4 through SGA-WB18.6 were combined to represent the FZ gases. The calculation implies that the recuperated cooler air contained 20.683% 0 2 and 0.1237% CO 2 on a dry basis. An air flow survey was completed by plant engineers 21 months earlier. Those data indicate a recuperated air flow of 14880 mcfh that is directed to the preheat zone, both combustion chambers, and the after-firing zone. Using the pellet parameters P1 and P2 in table 4.3, the implied 0 2 and CO 2 content of the recuperated air, and the estimated flow leads to the conclusion that 59% of the oxidation and 17.6% of the CO 2 evolution occurred in the cooler. Both values are higher than expected but not entirely unreasonable. A series of dust samples were taken from a sister machine and analyzed (see section 6). The results indicated that high values are possible but the oxidation in the cooler is more likely to be 40% of the theoretical maximum P1 flow.

The gas sample SGA-WB18 at windbox 18 should be the products of combustion from the south combustion chamber but include only part of the P1 and P2 flows from the cooler. From the gas flow surveys provided

25by the plant operators and the mass flow calculations it was estimated that 13% of the cooler air is diverted to each combustion chamber. A plot of 0 2 vs CO 2 given in figure 4.4 clearly demonstrates that some error must be present because the data do not fall on or near any reasonable estimate of the theoretical combustion curve. The curve was computed assuming 35% of the oxidation and 20% of the calcination occurred in the cooler and 13% of the cooler air flow was directed to the south combustion chamber. In the graph, any increase in P1 causes the theoretical curve to move away from the apparent curve. Increasing P2 moves the curves closer but the sample must represent 7% of the maximum calcination and 0% of the oxidation to bring the curves together. Also, the slopes of the curves would be significantly different. With 13% of the cooler flow representing 7% of P2max the calculation implies that 54% of the calcination takes place in the cooler. It is unreasonable to assume no oxidation and so much calcination takes place in the cooler. This implies that the gas analyses are in error. The authors examined the instrument calibration records and operating logs but were unable to find the source of the error. The gas analyses could only be correct if there was an unexpectedly large source of CO 2 or if the fuel was oil rather than natural gas. Using the data in table 4.4 a -3% error in the 0 2 measurement or a - 12% error in the CO 2 measurement or some combination of both is implied. The potential CO 2 error helps the data analyses for both days. The implied error in the mass flow calculations is +2.5% to -9.5%. It appears to be a systematic offset error and the relative changes between high and low primary air flows are considered significant.



### RESULTS FOR THE FURNACE The two combustion chambers provide essentially identical environments for the formation of NO x . Consequently, the production for the whole furnace can, in principle, be estimated from the operation of one chamber. Using the calculated NO„ mass flows for the south combustion chamber appearing in table 4.4 yields mass flow values that are linearly related to the fuel flow. The data are shown in figure 4.6 along with the regression line. Similar behavior for the Grate-Kiln furnace as well as the relation between NO x and CO 2 shown in figure 4.5 lends credibility to the observation. Although the fuel flows to the two combustion chambers are significantly different, the regression line for the south chamber was used to estimate the mass flow of NO„ for the north combustion chamber. The results are tabulated in table 4.4. The extrapolation is somewhat excessive and, of course, it is sensitive to the slope of the south chamber regression line. The two mass flows should be added to obtain the total NO x production for the process. The total mass flow should then be normalized to the total fuel flow. The procedure assumes that the

26formation of NO x is much less affected by the air:fuel ratio in this combustion environment than by the fuel flow as long as a large, high temperature excess air flow is present. This assumption is discussed later in this report.

In a private communication with the operators at the participating pelletizing plant it was learned that the NO x mass flow results calculated in this study were in agreement with stack samples taken to satisfy compliance with environmental regulations.

27

## 5. RESULTS: GRATE-KILN PRODUCING FLUXED PELLETS

FURNACE DESCRIPTION This pelletizing furnace is identical to the Grate-Kiln previously described except for the addition of five burners in the preheat zone and one burner in the second down-draft drying (DDD2) zone. Two of the preheat burners are rated at 40 million. BTU/hr and three are rated at 20. The DDD2 burner, rated at 20 million BTU/hr, was operated at a constant 9 million BTU/hr during all sampling periods. The process flow sheet and sampling locations, numbered 1-6, are shown in figure 5.1.

Gas samples were taken at five locations during September 28 through October 8, 1993. The summary of analyses are given in table 5.1. Pellet analyses given in table 5.2 represent shift averages. Plant operating data were available every 5 minutes after Oct. 5 and are summarized in table 5.3. The gas analyses are given in Appendix C as well as figures 5.2 through 5.8. Some plant operating data are shown in figures 5.9 through 5.12.



## DISCUSSION OF SAMPLES Gas samples GKF-6a and GKF-6b at the waste gas fan exhaust, were taken on Sept. 28 and 30, 1993, respectively. These samples represent all the fuel used in the process and include the entire effect of pellet drying, oxidation and calcination. Plant data are available only as averages for these sampling periods. The GKF-6a sample is believed to contain very significant sample-line air leaks and was not used to characterize the process. It is included only to demonstrate the effect of such leaks. In table 5.4 the calculated process gas flow is seen to be approximately twice the fan's capacity.

Gas sample GKF-5 was taken at the 1B preheat fan exhaust, on Oct 4, 1993. This sample should represent all the fuel used in the process except for the small burner in DDD2 and should include the entire effect of pellet oxidation and calcination. Plant data are available only as averages for this sampling period.

Sample GKF-4, taken on Oct. 5, 1993, is not representative of all the fuel used in the kiln or grate. The port is located near the feed end of the preheat (PH) zone of the grate. Much of the kiln exhaust is drawn through the pellet bed possibly before fully mixing with the additional air and fuel used in the PH zone. Plant operators guess that 70-90% of the kiln exhaust is bypassed in this manner but no estimate can made of the amount of PH zone fuel represented in this sample. Plant data were

28recorded every 5 minutes during this period but calculating a mass flow to represent this location would have no meaning.

Sample GKF-3, taken on Oct. 6, 1993, should represent the kiln exhaust gas and some air leakage into the process. The entire exhaust and leak flows are assumed to be fully mixed at the sample point but may not be. The sample is representative of the kiln fuel only. It consists of combustion products with an unknown amount of air and the P1 and P2 flows associated with the kiln and cooler. It was assumed that 35% of the pellets' oxidation and 5% of the calcination occurs in the kiln and cooler. Plant data were recorded every 5 minutes during this period. The PH zone fuel was increased from nominally 71 mcfh to 90 mcfh at 32 minutes into the sampling period and returned to 71 mcfh at 202 minutes. No gas composition change was observed when the PH zone fuel was changed which indicates that the GKF-3 sample did not contain any PH zone gases and implies that this location does represent the kiln exhaust. An argument could be made for a small decrease in NO„ at 72 minutes, 40 minutes after the change, but the statistical significance is in doubt. The gas analyses show a distinct change at 145 minutes. The kiln fuel increased and 3A fan amps decreased at this time. Those changes are consistent with the observed (small) decrease in 0 2 and significant increase in CO 2 . The NO. values also decreased significantly. The significant fluctuations in kiln fuel flow during the period 32 to 100 minutes were not observed to have much effect on the gas analyses. These observations are not consistent with other observations made during this study.

The GKF-1 and GKF-2 samples taken on Oct. 7 and 8, 1993, respectively, should represent recuperated air from the pellet cooler. The mass flow at sampling port 1 is estimated to be 10% of the flow at port 2. Some combustion products may be represented in the port 1 sample but the amount would have to be very small. Complete analyses for port 1 are not available but it should represent air that first contacts the pellets and would more likely be 0 2 -depleted. A reasonable assumption is for the pellets to complete their oxidation early in the cooling cycle. The 0 2 analyses are consistent with these assumptions. The port 2 NO analyses may indicate some NO formation in the cooler or an analysis error since it is highly unlikely that any combustion products could have flowed or diffused to this location. The port 1 sample was immediately followed by analysis of the ambient air outside of port 1 for 12 minutes. There was a 0.25-0.50 ppm decrease in the NO analyses when the sampling probe was withdrawn and the port closed but the significance of this is highly questionable. Since it was never possible to detect any NO formation in a bed of hot pellets in a laboratory furnace and the GKF-1 and 2 samples have very low NO. values, it is assumed that NO formation does not occur

29in the cooler.



### RESULTS FOR THE FURNACE Figures 5.9 and 5.10 are plots of 0 2 and NO,, vs CO 2 , respectively, for all gas samples taken during the fluxed pellet campaign. The combustion curves demonstrate the data are internally consistent. The implied relation between NO x and fuel flow in figure 5.10 is consistent with previous observations. When the NO,, mass flows and NO,, flow-to-fuel ratio are plotted against fuel flow, figures 5.11 and 5.12, the relations are not as clear as with the GKA and SGA samples. The scatter in the data may be due to variations in the feed and the ultimate effect of the pellet parameters which are more important for fluxed pellet production. It was not possible to make judgements for individual samples that would serve to reduce the scatter between the results determined from measured gas flows and calculated gas flows. The agreement between the two results was generally within a t 10% range of uncertainty.

In a private communication with the operators at the participating pelletizing plant it was learned that the NO,, mass flow results calculated in this study were in agreement with stack samples taken to satisfy compliance with environmental regulations.

30

## 6. RESULTS: STRAIGHT-GRATE PRODUCING FLUXED PELLETS

The sampling campaign for this furnace produced data that apparently contain significant errors. The data are presented for completeness and to demonstrate the subsequent analysis for this type of furnace.



## FURNACE DESCRIPTION This pelletizing furnace is almost identical to the traveling grate previously described except for the addition of 8 burners. The process flow sheet is given in figure 6.1. Not labeled is the firing zone in the windbox 18-22 region and the after-firing zone in the windbox 23-24 region. Baffles separating the hood zones were located as indicated in figure 6.1. The bottom of the baffle at windbox 11 was approximately 13-14 inches above the bed and the baffles at windboxes 7 and 24 were 2-3 inches above the bed. Because there are no baffles between windboxes 12-24 considerable mixing of the combustion products from all 10 burners could occur in the hood area. As in the previously described Straight-Grate, a bed of green pellets is placed on top of a bed of fired pellets, the hearth layer.

Each combustion chamber had a diameter of 10.67 ft and a height of 34.83 ft. The main burners were located in the roof of each combustion chamber and fire downward. The recuperated cooling air is supplied to each combustion chamber at the top and the air and combustion products enter the 15 ft-high firing zone hood through 6 ft ID openings horizontally into the top of the firing zone hood. A separate supply of recuperated air enters above windboxes 23 and 24 (mostly 24) through a 6.75 ft ID duct vertically downward through the roof approximately 6 ft above the bed. This is designated the after-firing zone. Air preheat temperatures for this furnace are normally 2000-2100°F which is more like a Grate-Kiln than the Straight-Grate producing acid pellets.

There were eight burners firing into the 9.75 ft-high preheat zone hood, four on each side of the furnace. The four pairs of burners were located above windboxes 13, 14, 15 and 16. The four burners above windboxes 13 and 14 are controlled together but separately from the four above windboxes 15 and 16. The two preheat control zones as well as each combustion chamber are controlled separately to obtain the desired temperature profile in the furnace. Each preheat burner is located at the center-line in the horizontal section of a 4 ft diameter downcomer that supplies hot recuperated air. The center-line is approximately 6 ft above the pellet bed and each burner is approximately 12 ft from the center-line of the furnace. The preheat burners are designed to induce a recirculating flow of furnace gases, in this case hot air, through the burner tile by means of the fuel and primary air injector. The injector is an arrangement

31of two concentric pipes with the fuel in the center pipe. The injector is located at the entrance of a venturi with a 4.75 inch diameter throat and 8.25 inch diameter exit nozzle.

Gas samples were taken at four process locations on four successive days from November 29 through December 2, 1993. All sampling locations were in the hood approximately 3 ft above the pellet bed at the noted windbox. The summary of gas analyses are given in table 6.1. Pellet analyses are given in table 6.2. Estimated plant operating data for the sampling campaign are given in table 6.3. The gas analyses are given in Appendix D and figures 6.2 to 6.5.

Several months after the sampling campaign a series of dust samples was obtained from the individual windbox dust legs. These samples were used in an attempt to estimate the progress of pellet oxidation and calcination as the pellets travelled from WB12 to WB24. The samples contained mostly recognizable pellet fragments. The samples were dry-screened and only the dust fraction smaller than 100 mesh was analyzed. Some samples•had insufficient dust for chemical analyses. It is reasoned that the fine dust is the fraction most likely to have come from the green pellet layer whereas the coarser material could easily have come from the hearth layer. Partial chemical analyses are given in table 6.4 and indicate that only 50-60% of the oxidation and 40-50% of the calcination is completed by the time the pellets reach windbox 24. The degree of oxidation appears to lead the degree of calcination throughout the process although, logically, there shouldn't be a large difference. Based on these samples there appears to be some rational for assuming 30-50% of the oxidation occurs in the cooler for the Straight-Grate. A range of 50-60% of the calcination occurring in the cooler appears to be excessive but the data do support a value larger than that used for the Grate-Kiln. A large amount of calcination could occur toward the very end of the firing cycle and a range of 30-50% of the calcination could be assumed to occur in the cooling

zone.


## DISCUSSION OF SAMPLES Analysis of the gas sampling data were found to be extraordinarily difficult due to the complexity of the flow pattern, limited availability of plant operating data, no flow measurements, and the numerous assumptions that were required. There was a significant process upset prior to the SGF-WB12 sampling period leading to additional uncertainties. For each assumption reasonable estimates for the parameters in equations 2-5 could be adjusted to obtain a wide range of results.

The gas sample at windbox 6 should include air plus some of the pellet

32moisture. If the sample was taken much further downstream or at the hood exhaust fan, more but not all of the pellet moisture would have been represented. Pellet moisture is removed while the pellets travel from windbox 1 to 10 or 11. If it is assumed that very little moisture is removed above windbox 1 then the simplest assumption would lead to the expectation that 1/10 of the pellet moisture is removed by the hot air from each successive windbox. From the gas analyses given in table 6.1, however, it is clear that some gases from the downdraft drying zone (DDD) must have mixed with the moist air above windbox 6. Air from the second cooling zone can be assumed to contain no NO N . If the WB10 sample is representative of the DDD zone gases, a simple volumetric ratio of the NO values in table 6.1 implies that the sample at windbox 6 contains 27.5% gases from the DDD zone and 72.5% is air plus moisture. The moisture should probably be 10-20% of the maximum P3 flow given in table 6.2. The sample demonstrates the large amount of cross-flow between zones in the hood of a Straight-Grate.

The gas sample SGF-WB26 should be air with small P1 and P2 flows but may contain some gases from the firing and after-firing zones above windboxes 19-24. Assuming no NO is formed in the cooling zone the sample must have contained combustion products from the firing zone despite of the seal at the baffle between windboxes 24 and 25. Using the analyses SGF-WB12 to represent the gases above windboxes 21-24 is a significant assumption but no alternative is available. NO ratios imply that the WB26 sample contained 2.29% gases from the firing zone but the CO 2 concentrations imply less than 1 %. Further analyses of the data were attempted but all calculations implied either that the gas analyses contained significant errors or the cross-flow gases were considerably different from the WB12 sample. The NO./CO 2 ratio, for example, would have to be lower. It was not possible to confirm that a large amount of oxidation and calcination occurs in the cooler. No further analysis of this sample is presented.

The gas samples taken at windbox 12 and 10 can, in principle, be used to estimate the NO„ emissions from the furnace. Two approaches can be used subject to different assumptions. The windbox 10 sample could be assumed to represent most or all of the preheat and firing zones as well as most or all or all of the effects of pellet oxidation and calcination, the P1 and P2 flows. The windbox 12 sample could be assumed to represent part of the preheat zone or all of the preheat and firing zone gases but only part of or all of the pellet oxidation and calcination that occurred in the cooler. If all of the burners generate NO at equivalent rates per unit heat input, then either sample could be used to represent the entire furnace. If the burners do not generate NO at the same normalized rate then the samples

33must be analyzed separately to represent different portions of the furnace. The NO x mass flows would then be added together to estimate the total emissions from the furnace. Of course, the furnace must be operating with the same fuel flows, air preheat temperatures, and production rates during the two sampling periods.

Daily pellet production rates were provided and used to estimate the hourly pellet feed rates during the sampling periods. Those data are given in table6.3. A daily fuel consumption estimate was provided for the day the SGFWB12 sample was taken. The data implied an average fuel consumption of 0.622 million BTU per long ton of dry pellet product for the day. The fuel and feed rates normally vary during a 24 hour period and the values during the sampling period are not known. Assuming a ± 25% demand variation, the fuel flow during the SGF-WB12 sampling period was estimated to be 167 ± 42 mcfh. The same methodology yielded a fuel flow estimate of 208 ± 52 mcfh during the SGF-WB10 sampling period. Those data are given in table 6.3 as fuel estimate A. Fuel estimate B is the result of a 10 day average fuel consumption of 0.548 million BTU per long ton of dry pellet product that was determined a few months earlier.

Figure 6.6 demonstrates that there was a significant excursion in theoperation of the furnace during the WB12 gas sampling period. The burnthrough temperature is the average of two measurements below the pallet cars in windboxes 22 and 24. Fuel flow will automatically increase when this temperature decreases sharply. The graph clearly demonstrates the strong relationship between NO x formation and fuel flow. A graph of the burn-through temperature for the WB10 sampling period was also made available. It shows a slow decrease from 900 to 880 F during the sampling period, and the whole graph implies a fairly steady operation.

Figure 6.7 and 6.8 present the combustion curves and the relation between NO„ and CO 2 , respectively. As in previous sections of this report, the combustion curves demonstrate the internal consistency of the data and the NO x appears to follow the fuel flow.

The gas sample at windbox 10 should include combustion products from most of the fuel, excess air, and most of the theoretical maximum P1 and P2 flows. The sample may be assumed to represent the flows through windboxes 15-24 even though some of that flow is bypassed before reaching the hood over windboxes 8-11. The assumption requires that no air entered the furnace between the bypass and the hood. Some gases from the preheat zone (PH) may also be present but there were no independent means to determine if that was true. Oxidation and calcination that occurs in the windbox 12-14 region and the portion of the

34cooler air flow that is directed to that region were not represented in the WB10 sample. The sample was assumed to represent 60% of the 0 2 consumed by the pellets. To balance the flows calculated by equations 3 and 4 the sample was assumed to represent 52.2% of the calcination. The third pair of preheat burners are directly above windbox 15 which is evenly split between the Windbox Recuperation Fan and the Windbox Exhaust Fan. The sample SGF-WB10 would represent 73% of the fuel if the flows were perfectly balanced. If the combustion products from the third pair were to go fully in one direction or the other, the fuel representation would be 73 ± 7%. Although these assumptions are not unreasonable, they are only educated guesses. From the values in table 6.3 and assuming 73% of the indicated fuel flow, 152 ± 38 mcfh, was represented by the gases at windbox 10, the NO x mass flow for this location in the process was 321 ± 43 lb NO 2 /hr and 2.12 ± 0.30 lb NO 2 /million BTU. The higher NO x mass flow corresponds to the lower normalized ratio with the fuel. The same calculations estimate the process gas flow was 15406 ± 2000 mcfh which implies that the low fuel rate is more likely because this flow is too high for the fan. That is, values closer to 278 lb NO./hr and 2.44 lb NO x /MMBTU at an implied fuel flow of 114 mcfh are more likely. A wider range of conditions is given in table 6.7, particularly at the lowest fuel flows with 65-75% of the oxidation represented in the sample.

The gas sample SGF-WB12 should include combustion products from some of the fuel and excess air. The sample may also contain some gases from the DDD zone. The mixing of gases between the PH and DDD zones is dependent on the respective hood and windbox pressures. Since the samples at windbox 10 and 12 were taken one day apart the direction of mixing could be different. No mixing was assumed. The sample is assumed to represent the flows through windboxes 12-14. To account for oxidation and calcination in the cooler, 0 2 consumption and CO 2 evolution, P1 and P2 were 9.7 and 21.96 mcfh, respectively. The data are presented in table 6.5. Assuming this sample represents 27% of the fuel flow, 47 ± 12 mcfh, the mass flow was 205 ± 50 lb NO 2 /hr and 4.55 ± 0.17 lb NO 2 /million BTU for this location. The process gas flow estimate through windboxes 12-14 that this sample represents was calculated to be 2836 ± 600 mcfh. A wider range of conditions is given in table 6.6 at the lowest fuel flows with 9-15% of the oxidation represented in the sample.



### RESULTS FOR THE FURNACE The whole process could be characterized by the sum of the mass flows calculated from the WB10 and WB12 analyses. This would be valid if the fuel consumption and pellet feed rates, etc. were the same on both days. Unfortunately, the pelletizing furnace was operating at a much lower

35production rate on the second day. Only a single estimated fuel flow is available eliminating the possibility of measuring the slope of the NO 2 mass flow with fuel flow. Therefore, there appears to be no rational basis for normalization based on the available data. It was noted, however, that the WB10 sample was most likely representative of operations at the lower range of the given fuel flow. This means that the fuel flow rates during the WB10 and WB12 sampling periods may have been fairly close. If that were true the mass flows can be added to represent the process. The resulting mass flow is 483 lb NO 2 /hr and 3.00 lb NO 2 /million BTU although it is unclear how to establish an error range to these estimates.

If it were assumed that the combustion environments for all ten burners were not radically different then either the WB10 or WB12 samples could be considered representative of the entire preheat and firing zones, WB12- 24, and, therefore, the furnace. Results based on that assumption are given in tables 6.6 and 6.7 for the estimated fuel flows, ± 25%, and appropriate estimates of oxidation. In all cases the calcination values were selected to yield the same calculated air flows from equations 3 and 4 for the given oxidation estimates. The resulting values are consistent with the data presented in table 6.4. The WB10 sample analysis results in a process gas flow that is too large unless the fuel flow was much lower than expected. The WB12 sample analysis yields process gas flows that are considered low but not unreasonable. These calculations suggests that the preheat burners produce more NO x per million BTU than the two main burners and this method of analysis should not be used.

In a private communication with the operators of the participating pelletizing plant it was learned that stack testing for compliance with environmental regulations has repeatedly yielded values of 900-1200 lb NO 2 /hr for this furnace at fuel flows ranging from 160 to 210 mcfh. This implies that the WB12 sample may be a fair representation of the hood gases over windboxes 12-24. However, the extraordinarily wide range of results for what could be considered reasonable estimates of operating conditions readily demonstrates that this study could not determine the mass flow of NO„ for this furnace with any degree of certainty.

36

## 7. DISCUSSION

All the flames in the two pelletizing furnaces sampled for this study have some basic similarities relevant to NO„ formation. In all cases a fuel flow varies on demand and a flame is established within a refractory-lined chamber containing a large volume of air preheated to 1650-2200°F. The fuel-air mixing rates probably varied from burner-to-burner and the effective air:fuel ratio within each flame envelope also probably varied. In all cases, however, the amount of hot secondary air in the neighborhood of the flame envelope was 2-4 times the fuel's requirements. That is, the flame is established within a volume of hot air that does not directly participate in the combustion reactions but only mixes with the combustion products when the reactions are substantially complete. By this reasoning, the environment for producing NO,, is determined by the volume of the flame envelope, the temperature of the secondary air, the radiative heat loss to the surroundings during combustion, and to a lessor extent the rate of mixing prior to and during combustion. The mixing of the combustion products with the remaining air then serves to quench the NO,, reactions. More rapid quenching would serve to lower the NO. production from the furnace. This reasoning is consistent with the general observation that NO,, increases with fuel flow. NO„ mass flows for all the samples are given in figure 7.1 which demonstrates this general trend. The same trend appears in figure 7.2 which demonstrates that NO,, is also generated at a higher rate per unit heat input as the fuel flow to a furnace is increased. Only for the SGA samples is the trend clearly seen with little scatter. Where the combustion conditions are significantly different, ie. different furnaces and different burner configurations, the groupings maintain the trend.



## GRATE-KILN The two samples GKA-3 and GKF-3.1 represent virtually identical combustion environments, the kiln in a Grate-Kiln. The fuel flow in bothcases was 149 ± 1 mcfh but the NO,, mass flow was 400 lb/hr for GKF3.1 and 637 lb/hr for GKA-3. The air flow for GKF-3.1 was 350% stoichiometric fuel requirements and it was 500% for GKA-3. The secondary air temperature was 100°F higher for the GKA sample. Although oxygen content should have some effect on NO,, formation, it is unlikely that variations in 0 2 concentrations from 15.2% to 17.5% could account for the difference. The increased secondary air temperature is the most likely explanation for the differences in NO. production. Using the values in figure 7.1 determined from measured process gas flows, the slope of the line for samples GKF-3.1 and 3.2 is similar to the slope of the line for the GKA samples. Such a result is expected lending support to the higher value for the GKF-3.2 sample.

37When producing fluxed pellets the Grate-Kiln requires auxiliary burners in the preheat zone of the grate. The increased production of NO with the increased fuel flow, however, is not as steep as would be expected from the kiln burner alone. This observation leads to the conclusion that the auxiliary burners do not produce NO as efficiently as the single, larger kiln burner. The "secondary air" for the grate burners is leak air plus kiln exhaust gas containing 15-16% 0 2 at a temperature 100°F hotter than the kiln burner's secondary air. The leak air raises the oxygen content at the expense of temperature. Because of the uncertainty regarding the amount of leak air and degree of mixing near the burners, it is not possible to state with certainty whether the .grate burners' secondary air is hotter or cooler than the kiln burner's secondary air. In fact, the nature of the flow pattern in the preheat zone hood makes it likely the five burners see significantly different environments. It is reasonable, however, to consider that a combination of lower oxygen content and lower secondary air temperature is the reason why the grate burners produce less NO„ per unit heat input than the kiln burner. Lower wall temperatures (the pellet bed especially) would induce a greater rate of radiative heat loss from the flames thereby lowering the peak flame temperature. This should also contribute to lower NO production.



### STRAIGHT-GRATE Only a very limited discussion is possible for the Straight-Grate furnace because of the difficulties noted in Section 6. The SGF data appear to support the statement that the auxiliary burners in the preheat zone of the grate produce more NO per unit heat input than the two burners in the main combustion chambers. This is most likely due to design differences because secondary air temperatures are the same and the radiative environments are similar. The two Straight-Grate furnaces were operated with significantly different air preheat temperatures. The higher preheat temperatures along with the greater use of fuel is most likely responsible for the much greater production of NO in the Straight-Grate when producing fluxed pellets.



### FURNACE COMPARISONS Extrapolating the SGA results to higher heat inputs places the NO production rate in the same region as the GKA results. It has not been demonstrated that such a large extrapolation is reasonable but the flames are qualitatively similar and it may not be an accident that they would agree. Air temperatures during the SGA tests were 500-550°F cooler than for the GKA tests and, logically, the SGA results should not extrapolate to the GKA results. It is reasoned, therefore, that the burners/combustion environment for the SGA tests may be more favorable for NO formation than the GKA burner/combustion environment. That may be due to the

38larger radiative load on the kiln's flame which would serve to decrease the peak flame temperature.

Extrapolating the GKA results to higher heat inputs places the NO production rate in the same region reported by the operators for the Straight-Grate producing fluxed pellets. Air preheat temperatures for the two machines are 2100-2200°F. The extrapolation, if valid, implies that the fuel flow and air preheat temperatures are the dominant variables whereas burner and furnace design variations, as they currently exist, are much less important.

Some gas samples taken from the pellet cooler for the furnaces did contain some NO R . Cross-flow across the pellet bed was probably the cause for this in the Straight-Grate furnaces but the GKA-1 and 2 samples did support the findings of a prior laboratory investigation that NO. would not be produced in the pellet cooler.

No discussions regarding SO 2 or CO have been given in this report. The measurements for these species were not consistent and did not appear to provide any help in interpreting the NO„ results. Generally, the higher CO values should be present if the combustion reactions were not well established or, possibly, if the flame is quenched quickly. A sulfur balance was beyond the scope of this research but it is obvious that the source of sulfur was the pellets. Very low values of sulfur, 100-200 ppm by weight, in the green pellets would be sufficient the generate the levels of SO 2 observed. The sulfur appears to be released late in the pellet induration stage of the process.

39

## 8. CONCLUSIONS

A gas sampling survey was conducted on two types of pelletizing furnaces producing both fluxed and conventional acid pellets. The survey was able to characterize NO formation in the iron ore pelletizing process.

The pellets alter the gas composition significantly and variations in feed rate can be more significant than variations in fuel flow especially when fluxed pellets are being produced.

The pelletizing furnaces surveyed produce 400-700 lb/hr NO 2 or 2.5 to 4.5 lb NO 2 /million BTU of fuel input depending on the type of furnace and whether acid or fluxed pellets were being produced.

Mass flow of NO. increased, generally linearly, with fuel input for any furnace. NO. emissions normalized to fuel input did not substantially increase with fuel input.

The Grate-Kiln furnace produces 500-700 lb NO 2 /hr when producing acid pellets and roughly the same when producing fluxed pellets. NO generation normalized to fuel input was lower for fluxed pellet production. NO. generation normalized to pellet production was higher for fluxed pellet production than conventional acid pellet production.

The Straight-Grate furnace produced 450-480 lb NO 2 /hr or 4.3 lb NO 2 /million BTU when producing acid pellets but over 900 lb NO 2 /hr when producing fluxed pellets.

The auxiliary burners in a Grate-Kiln, necessary to produce fluxed pellets, produce less NO. per unit heat input than the single, larger kiln burner.

The kiln burner in a Grate-Kiln produces less NO„ when producing fluxed pellets than while producing acid pellets at equivalent heat input. This was most likely due to lower secondary air temperatures.

The auxiliary burners in a Straight-Grate, necessary for the production of fluxed pellets, appeared to produce more NO. per unit heat input than the main burners. This may have been due to burner design or the radiative environment around the flame.

Formation of NO„ in the pellet cooler of either furnace was not supported by the data.

The NO mass flow relationship with fuel flow for the Straight-Grate

40producing acid pellets appears to extrapolate to the same levels of NO„generation at equivalent fuel flows observed in a Grate-Kiln. The GrateKiln results, in turn, appear to extrapolate to NO„ production rates reported for the Straight-Grate producing fluxed pellets. The implication of such extrapolations is that the conditions for NO x formation are substantially the same for both furnaces despite their radically different designs.

There is no single sampling location in the Straight-Grate producing fluxed pellets that can be used to completely characterize the furnace.

Flow measurements of process gases at the sampling location should be supplemented with flow calculations from the gas analyses and furnaceoperations to verify data consistency. Errors is gas analyses and sampleline air leaks could generally be found and adequately characterized. However, CO 2 values found in stack sampling are too low for the technique to be useful.

41

### REFERENCES 1. English, A. and Frans, R.D. Developments in Pelletizing. Chapter in Agglomeration 77, AIME, N.Y., 1977 pp 3-23. 2. Koski, R.A. Pelletizing of Various Iron Ore Concentrates and Natural Ores as Practiced by the Cleveland-Cliffs Iron Company. Chapter in Agglomeration 77, AIME, N.Y., 1977, pp 46-73 3. Nigro, J.C., Zahl, R.K. Pulverized Coal-Firing Systems for Induration of Iron Oxide Pellets. Chapter in Agglomeration 77, AIME, N.Y., 1977, pp 437-464. 4. Fluxed Pellet Panel, section in the Proceedings of the 63rd Annual Meeting of the Minnesota Section of the AIME/SME, Duluth, MN, January, 1990, pp 29-57. 5. Haas, L. A., J. C. Nigro, and R. C. Moe. Use of Oxygen-Enriched Gas for the Oxidation of Acid and Fluxed Taconite Pellets. U.S. Bureau of Mines RI 9473, 1993, pp 22 6. Farnam, H.E. Energy Alternatives for the Taconite Industry. Proceedings of the Annual Meeting of the Minnesota Section of the AIME/SME, Duluth, MN, January 1976, pp. 8-1 to 8-20. 7. Nigro, J.C. and Zahl, R.K. Preliminary Experiments in Pellet Induration using a Coal-fired Cyclone Combuster. Proceedings of the Annual Meeting of the Minnesota Section of the AIME/SME, Duluth, MN, January 1976,pp. 9-1 to 9-47. 8. Private communication with pelletizing companies and operators regarding process operations and the results of emissions tests required by the Minnesota Pollution Control Agency. 9. Haas, L.A., Pojar, M.J., James, M.L. Formation of NO in an Electrical and Fuel-Fired Furnace. Pres. at SME/AIME Annual Meeting, Feb. 14-17, 1994, Albuquerque, New Mexico. 10. Faulkner, Edward Jr. Guide to Efficient Burner Operation: Gas, Oil & Dual Fuel, 1981, pp 156-207. 11. Haas, L. A., C. F. Anderson, and S. E. Khalafalla. Decomposition of Nitric Oxide in a Silent Discharge. Ind. Eng. Chem. Process Des. Dev., Vol. 18, No. 1, 1978, pp. 143-147. 12. Ranzi, E. et al. A Wide Range Modeling Study of Methane Oxidation. Combust. Sci. and Tech. 1994, Vol. 96, pp. 279-325. 13. Miller, J.A., Bowman, C.T. Mechanism and Modeling of Nitrogen Chemistry in Combustion. Prog. Energy Combust. Sci., 1989, Vol. 15, pp. 287-338. 14. Bowman, C. T. Control of Combustion-Generated Nitrogen Oxide Emission: Technology Driven by Regulation. Twenty-Fourth Symposium (International) on Combustion/The Combustion Institute, 1992, pp. 859- 878. 15. Burner Retrofits Reduce Brewery Emissions. Chemical Engineering, April 1993, pp. 177.

4216. Lilleheie, N.I., et.al. Modeling Chemical Reactions - Development and Test of Reduced Chemical Kinetic Mechanism for Combustion of Methane. DE92-70389, NTIS, Wash.D.C., May 1991, pp. 132. 17. Correa, S.M. A Review of NO„ Formation Under Gas-Turbine Combustion Conditions. Combust. Sci. and Tech., 1992, Vol. 87, pp. 329-362 18. Silver, R. G., S. E. Swayer, and J. C. Summers, Editors. Catalytic Control of Air Pollution: Mobile and Stationary Sources. ACS, Washington, DC. 1992, pp. 1-113. 19. Vatsky, J. and E. S. Schindler. Industrial and Utility Boiler Low NO Control Update, PB 89-139695, 1989, p. 15-2. 20. Meersman, T. MPCA Says Proposed Emission Fees Are Too Low in the Dakotas. Minneapolis Star and Tribune, August 25, 1993, p. 6B. 21. Swayer, R. F. The Formation and Destruction of Pollution in Combustion Processes: Clearing the Air on the Role of Combustion Research. Eighteenth Symposium (International) on Combustion. The Combustion Institute, 1981, pp. 1-22. 22. Nitrogen Oxide Control for Stationary Combustion Sources. EPA/625/5-86/020, July 1986, 49 pp. 23. Sourcebook: NO. Control Technology Data, EPA/600/S2-91/029, August 1991, pp 9. 24. Seeley, R. S. Clean Air Act Amendments Spawn Lively Air Pollution Equipment Market. ES&T Environmental Buyers' Guide Edition, ACS, 1993, pp. 14-17. 25. Nielsen, P. B. and 0. L. Jepson. An Overview of the Formation of SO. and NO in Various Pyroprocessing Systems. IEEE Trans. on Industry Applications, v. 27, no. 3, May/June 1991, pp. 431-439.

43

# TABLES

### Table 2.1 Weather data for the field study - Hibbing, MN airport

Date

yyyymmdd Air Temp F WetB DewP Temp Temp F F Rel.H (min)

pct. Rel.H (max)

pct. Wind Speed

mph Wind SeaLev Direct. Press.

deg. mb Solar Pot Radiation MJ/sq m Evap in Local Pressure inHg Moisture in Air vol Tract.

19930928 43 40 36 68 89 10 336 1018 7.4 0.05 28.700 0.00737 19930929 38 33 27 37 85 9 313 1026 17.9 0.09 28.937 0.00509 19930930 0 0 0 0 0 0 0 0 16.2 0.16 ND ND 19931001 38 33 26 50 86 13 315 1007 8.6 0.07 28.374 0.00459 19931002 31 27 20 40 85 11 277 1017 15.6 0.08 28.670 0.00358 19931003 49 43 38 40 85 11 297 1007 12.7 0.13 28.374 0.00807 19931004 39 34 26 35 78 11 316 1016 16.6 0.10 28.641 0.00455 19931005 41 35 27 33 83 9 178 1021 14.0 0.10 28.789 0.00512 19931006 56 48 43 35 85 8 205 1011 15.8 0.12 28.492 0.00977 19931007 43 40 35 61 82 12 40 1019 6.2 0.05 28.729 0.00709 19931008 35 31 25 46 85 12 7 1022 10.8 0.07 28.818 0.00452

19931018 38 35 32 62 89 2 284 1018 6.2 0.00 28.700 0.00628 19931019 40 38 35 71 89 6 166 1019 7.2 0.01 28.729 0.00709 19931020 43 41 37 69 89 10 267 1014 4.7 0.02 28.581 0.00771 19931021 34 31 25 59 79 12 306 1016 5.4 0.04 28.641 0.00455 19931022 38 32 25 31 87 6 204 1024 13.4 0.08 28.877 0.00451

19931129 15 14 11 71 86 6 351 1024 2.6 0.00 28.877 0.00222 19931130 0 0 0 0 0 0 0 0 2.9 0.01 ND ND 19931201 26 25 22 75 91 12 174 1018 2.5 0.00 28.700 0.00454 19931202 30 29 27 83 91 6 291 1015 1.5 -0.01 28.611 0.00515

19940420 39 31 16 27 68 10 331 1025 19.5 0.13 28.907 0.00279 19940421 40 32 18 21 86 3 22 1026 21.0 0.10 28.937 0.00355

## Table 2.2 Results of a sensitivity analysis for a +5% change in the indicated parameters using the data set obtained on Oct. 21, 1993.

Parameter changed by +5% Resulting change in NO,, mass flow Resulting change in NO,, flow per MMBTU Parameter changed by + 5% Resulting change in NO,, mass flow Resulting change in NO,, flow per MMBTU

Pellet feed + 2.22 + 2.22 02 meas. +4.03 +4.03

Pellet moisture + 0.26 + 0.26 CO 2 meas. -3.83 -3.83

Pellet oxidation + 0.30 +0.30 NO,, meas. +5.00 +5.00

Pellet calcination +1.48 + 1.48 All combined +12.3 +7.4

Fuel flow + 2.79 -2.11 Maximum +25.1 +19.2

## Table 3.1 Average gas analyses for the Grate-Kiln producin acid pellets

Date Sample ID Time Period Statistic NOx ppm (wet)



## _ SO2 ppm (wet) 

## CO ppm (dry) 

## CO2 % (dry) 

## 02 % (dry)

10/18/93 GKA-6a Samples 44 44 47 50 48

11:27 Mean 231.72 52.823 8.897 1.437 17.662

to StdDev 18.35 4.36 1.79 0.03 0.11 14:00 CoefVar,% 7.92 8.25 20.15 2.31 0.61 10/19/93

GKA-5 Samples 18 20 19 19 19 13:29 Mean 309.72 121.000 8.895 1.889 15.805

to StdDev 7.76 6.41 1.36 0.02 0.26 15:15 CoefVar,% 2.51 5.30 15.29 1.11 1.64 10/20/93

GKA-3 Samples 58 57 61 58 . 61 10:24 Mean 526.41 32.467 0.307 1.485 17.469

to StdDev 42.09 3.90 0.34 0.13 0.33 13:27 CoefVar,% 8.00 12.00 112.09 8.79 1.92 10/21/93 GKA-6b.1 Samples 36 36 31 37 37 11:46 Mean 212.63 46.944 7.823 1.140 17.136

to StdDev 16.00 2.40 2.71 0.07 0.22 13:34 CoefVar,% 6.68 5.07 35.90 5.53 1.30 10/21/93 GKA-6b.2 Samples 53 52 52 53 53 13:55 Mean 195.59 45.895 9.653 1.043 17.426

to StdDev 11.88 2.68 1.75 0.05 0.15 16:31 CoefVar,% 6.44 5.74 17.57 4.92 0.84 10/

. 21/93 GKA-6b.3 Samples 29 29 29 29 29 13:55 Mean 198.04 45.407 9.641 1.049 17.346

to StdDev 12.25 2.82 1.54 0.06 0.13 15:19 CoefVar,% 28.42 24.97 33.74 28.18 13.89 10/22/93 GKA-6c Samples 41 41 43 41 42

10:28 Mean 199.19 43.663 3.053 0.971 18.622

to StdDev 10.89 2.59 1.49 0.03 0.15 12:34 CoefVar,% 5.67 5.54 94.19 3.99 1.10 utliers removed

## Table 3.2: Feed & product chemistry for the Grate-Kiln producing acid pellets

Date 

### Green Pellets d basis) 1 Fired Pellets

Fe Si02 CaO MgO, C, S Fe+2 Fe Si02 CaO, MgO C S Fe+2 Oxidized Calcined Desulfurized

wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct sot pct

10/18/93 66.61 5.49 0.43 0.29 0.33 143 22.64 65.43 5.28 0.51 0.30 0.023 10 0.50 97.71 92.90 92.88

10/19/93 66.64 5.61 0.38 0.33_ 0.31 146 21.39 63.35 5.42 0.46, 0.34 0.026 10 0.38 98.20 91.18 92.79

10/20/93 69.60 5.97 0.28 0.36 0.29 121 22.04 64.71 5.65 0.32 0.35 0.019 10 0.31 k
98.56 92.95 91.11

10/21/93 66.74 5.53 0.36 0.34 0.29 160 22.47 65.49 5.44 0.27 0.33 0.012 10 0.38 98.26 95.78 93.63

10/22/93 67.00 5.46 0.31 0.33 0.27 159 22.45 65.56 5.35 0.33 0.33' 0.011 10 0.44 97.99 95.84 93.57
Average 1 67.32 5.61 0.35 0.33 0.30 146 22.20 64.91 5A3 0.38 

### South 0.33 

### preheat 0.018 

### fan 10 

### cyclone 0.401 98.14 

### dust 93.73 92.80

09/16/93 64.44 7.63 0.4 0.43 ND ND 7.87 63.36 ND 111•1=11 ND 

### North preheat fan cyclone dust

09/16/93 I 65.11 6.58 0.4_, 0.41 ND, ND, 8.62 60.28 ND ND

Oxidation = (1-(3*Fe++/Fe))*100 Calcination: By means of ratios of C/Fe Desulfurization: By means of ratios of S/Fe Average used for green feed on 9/16/93

## Table 3.3: Summary of measurements for the Grate-Kiln producing acid pellets

Date Sample

Period

H:M - H:M Pellet

Feed

It/hr Pellet

Moisture

wt % Kiln

Fuel

mcfh Grate

Fuel

mcfh P1

(max 02)

mcfh P2

(max CO2)

mcfh P3

(max H2O)

mcfh Gas
Sample

I.D. Gas Analyses Estimated
H2O vapor

v%(wet) Gas
Density

Ibm/cf CO2
v% (dry) 02
v% (dry) NOx
ppm (wet)
10/18/93 11:25 - 14:00 482.8 9.5 155.5 0 379.4 97.3 2201.1 GKA-6a 1.437 17.662 231.720 8 0.0719
10/19/93 13:29 - 15:15 482.8 9.5 154.6 0 360.2 89.7 2201.1 GKA-5 1.889 15.805 309.720 2 0.0736
10/20/93 10:23 - 13:26 499.6 9.5 149.6 0 385.5 88.6 2277.8 GKA-3 1.485 17.469 526.410 3 0.0733
10/21/93 11:50 -13:29 477.5 9.5 150.6 0 374.5 87.2 2176.9 GKA-6b.1 1.140 17.136 212.630 8 0.0717
10/21/93 13:55 - 16:31 460 9.5 140.9 0 360.8 84.0 2097.3 GKA-6b.2 1.040 17.430 195.590 8 0.0717
10/21/93 13:55 - 15:19 510.6 9.5 139.7 0 400.5 93.3 2328.0 GKA-6b.3 1.049 17.350 198.040 8 0.0717
10/22/93 10:29 -12:32 435.5 9.5 135.6 0 340.3 74.1 1985.7 GKA-6c 0.971 18.622 199.190 8 0.0718

### Table 3.4: Summary of results for the Grate-Kiln producing acid pellets

Gas Sampling

Location Gas
Sample

I.D. Kiln

Fuel

mcfh Grate

Fuel

mcfh P1

(actual)
mcfh P2

(actual)
mcfh P3

(actual)
mcfh Gas Analyses Process Gas Flow Measured Process Gas Flow Calculated

CO2 v% (dry) 02 v% (dry) NOx _ppm (wet) Gas Flow

mcfh NOx

lb/hr NOx

lb/MMBTU Gas Flow

mcfh NOx

lb/hr NOx

lb/MMBTU

Waste Gas Fan GKA-6a 155.5 0.0 379.4 97.3 2201.1 1.437 17.662 231.720 25265 692 4.452 20638 566 3.637

PreHeat Fan GKA-5 154.6 0.0 360.2 , 89.7 0.0 1.889 15.805 309.720 14299 524 3.388 13066 479 3.095

Kiln Exhaust GKA-3 149.6 0.0 154.2 4.4 0.0 1.485 17.469 526.410 10235 637 4.259 11063 689 4.604

Waste Gas Fan GKA-6b.1 150.6 0.0 374.5 87.2 2176.9 1.140 17.136 212.630 25391 638 4.239 22899 576 3.823

Waste Gas Fan GKA-6b.2 140.9 0.0 360.8 84.0 2097.3 1.040 17.430 195.590 23665 547 3.885 23675 548 3.887

Waste Gas Fan GKA-6b.3 139.7 0.0 400.5 93.3 2328.0 1.049 17.350 198.040 24024 563 4.028 24461 573 4.101

Waste Gas Fan GKA-6c 135.6 0.0 340.3 74.1 1985.7 0.971 18.622 199.190 21826 514 3.792 24747 583 4.299

### Table 4.1 Average gas analyses for the Straight-Grate producing acid pellets.

Date Sample ID Time Period Statistic SO2 ppm (wet) 

### CO

ppm (dry) 

### NOx ppm (wet) 

### 02 pct (dry) 

### CO2 pct (dry) Samples 42

. 41 42 42 42 04/20/94 Mean 8.027 0.775 43.13 20.464 0.269 SGA-VVB16 StdDev 1.05 0.36 6.57 0.08 0.04 12:35 - 13:50 CoefVar,% 13.14 47.04 15.24 0.39 13.85 Samples 5 8 7 8 6' 04/21/94 Mean 5.780 < 1.0 629.64 17.240 2.318 SGA-WB18.1 StdDev 0.29 ND 47.31 0.17 0.09

9:51 - 9:59 CoefVar,% 5.06 ND 7.51 1.00 3.69 Samples 20 27 24 25' 27 04/21/94 Mean 5.965 < 1 713.13 17.142 2.372 SGA-VVB18.2 StdDev 0.31 ND 36.92 0.13 0.07 10:00 - 10:29 CoefVar,% 5.20 ND 5.18 0.76 2.88 Samples 27 27 27 25 24' 04/21/94 Mean 5.315 < 1 637.60 17.293 2.337 SGA-VVB18.3 StdDev 0.36 ND 36.57 0.15 0.07 10:30 - 10:59 CoefVar,% 6.77 ND 5.74 0.86 3.04 Samples 28 28 28 27 27 04/21/94 Mean 5.136 < 1 648.93 17.136 2.433 SGA-WB18.4 StdDev 0.26 ND 40.29 0.13 0.07 11:00 - 11:29 CoefVar,% 5.13 ND 6.21 0.76 2.82 Samples 25 25' 24 24 ' 25 04/21/94 Mean 5.112 < 1 588.88 17.196 2.417 SGA-WB18.5 StdDev 0.41 ND 39.81 0.13 0.07 11:30 - 11:59 CoefVar,% 8.00 ND 6.76 0.76 2.93 Samples 26 26 26 22 22 04/21/94 Mean 4.765 < 1 609.86 17.136 2.469 SGA-WB18.6 StdDev 0.33 ND 51.73 0.12 0.06 12:00 - 12:29 CoefVar,% 6.96 ND 8.48 0.73 2.54 Samples 28 28 28 27 28 04/21/94 Mean 4.850 < 1 657.99 17.286 2.385 SGA-WB18.7 StdDev 0.32 ND 54.54 0.13 0.07 12:30 - 12:59 CoefVar,% 6.53 ND 8.29 0.73 2.82 Samples 25 26 26 26 26 04/21/94 Mean 4.760 < 1 664.35 17.278 2.396 SGA-WB18.8 StdDev 0.28 ND 40.61 0.12 0.06 13:00 -13:29 CoefVar,% 5.85 ND 6.11 0.71 2.62 Samples 18 18 17 18' 18 04/21/94 Mean 4.639 < 1 674.46 17.248 2.404 SGA-WB18.9 StdDev 0.20 ND 27.38 0.12 0.06 13:30 - 13:50 CoefVar,% 4.32 ND 4.06 0.68 2.52 Outliers removed

## Table 4.2: Feed & product chemistry for the Straight-Grate producing acid pellets

Date 

### Green Pellets (dry basis Fired Pellets

Fe S102 CaO MgO C S Fe+2 Fe 8102 CaO MgO C S Fe+2 Oxidized Calcined Desulfurized

4 wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct pct pct

_ 04/21/94 73.90 5.78 0.22 0.23 0.32 ND 22.30 65.00 0.020 0.40 98.15 92.89 ND

## Table 4.3: Summary of measurements for the Straight-Grate producing acid pellets.

Date Sample

Period

H:M - H:M Pellet

Feed

It/hr Pellet

Moisture

wt % South

Fuel

mcfh North

Fuel

mcfh P1

(max 02)

mcfh P2

(max CO2)

mcfh P3

(max H2O)

mcfh Gas
Sample

I.D. Gas Analyses Estimated
H2O vapor

v%(wet) Gas
Density

Ibm/cf CO2
v% (dry) 02
v% (dry) NOx
ppm (wet)

04/20/94 12:35 - 13:50 382.5 9.25 42.0 68.0 298.2 75.0 1698.1 SGA-WB16 0.269 20.464 43.13 0.6 0.0737

04/21/94 09:30 - 10:00 383.4 9.25 41.0 68.7 298.9 75.2 1702.1 SGA-W618.1 2.318 17.240 629.64 4.5 0.0732

04/21/94 10:00 - 10:30 383.4 9.25 39.5 66.7 298.9 75.2 1702.1 SGA-VVB18.2 2.372 17.142 713.13 4.6 0.0732

04/21/94 10:30 - 11:00 383.4 9.25 38.3 70.5 298.9 75.2 1702.1 SGA-WB18.3 2.337 17.293 637.60 4.5 0.0732

04/21/94 11:00 - 11:30 383.4 9.25 36.6 70.8 298.9 75.2 1702.1 SGA-WB18.4 2.433 17.136 648.93 4.6 0.0732

04/21/94 11:30 - 12:00 382.5 9.25 32.3 68.6 298.2 75.0 1698.1 SGA-WB18.5 2.417 17.196 588.88 4.5 0.0732

04/21/94 12:00 - 12:30 381.6 9.25 33.8 73.5 297.5

... 74.8 1694.1 SGA-WB18.6 2.469 17.136 609.86 4.7 0.0732

04/21/94 12:30 - 13:00 382.5 9.25 36.0 69.9 298.2 75.0 1698.1 SGA-WB18.7 2.385 17.286 657.99 4.5 0.0732

04/21/94 13:00 - 13:30 381.6 9.25 39.1 70.8 297.5 74.8 1694.1 SGA-WB18.8 2.396 17.278 664.35 4.6 0.0732

04/21/94 13:30 - 13:50 383.4 9.25 36.7 67.2 298.9 75.2 1702.1 SGA-WB18.9 2.404 17.248 674.46 4.6 0.0732

Low primary air includes the period 11:00 to 12:30

### Table 4.4: Summary of results for the Straight-Grate producing acid pellets.

Gas Sampling

Location Gas
Sample

I.D. South

Fuel

mcfh North

Fuel

mcfh P1

(actual)

mcfh P2

(actual)

mcfh P3

(actual)

mcfh Gas Analyses Process Gas Flow Calculated North Chamber Estimated

CO2
v% (dry)_ 02
v% (dry) NOx
ppm (wet) Gas Flow

mcfh NOx

Ibm/hr NOx

IbmIMMBTU Gas Flow

mcfh NOx

Ibm/hr NOx

IbmIMMBTU
WindBox 16 Hood SGA-WB16 42.0 68.0 22.9 1.7 0.0 0.269 20.464 43.130 1977 10.08 3.69 ND ND ND
Windbox 18 Hood SGA-WB18.1 41.0 68.7 22.9 1.7 0.0 2.318 17.240 629.640 2069 154.05 3.76 ND 317 4.62
Windbox 18 Hood SGA-WB18.2 39.5 66.7 22.9 1.7 0.0 2.372 17.142 713.130 1956 164.95 4.18. ND 306 4.59

Windbox 18 Hood SGA-WB18.3 38.3 70.5 22.9 1.7 0.0 2.337 17.293 637.600 1935 145.91 3.81 ND 328 4.65

Windbox 18 Hood SGA-W818.4 36.6 70.8 22.9 1.7 0.0 2.433 17.136 648.930 1789 137.27 3.75 ND 330 4.65

Windbox 18 Hood SGA-WB18.5 32.3 68.6 22.9 1.7 0.0 2.417 17.196 588.880 1608 111.96 3.47 ND 317 4.62

Windbox 18 Hood SGA-WB18.6 33.8 .., 73.5 22.8 1.7 0.0 2.469 17.136 609.860 1645 118.61 3.51 ND 345 4.69

Windbox 18 Hood SGA-W918.7 36.0 69.9 22.9 1.7 0.0 2.385 17.286 657.990 1799 140.02 3.89 ND 324 4.64

... Windbox 18 Hood SGA-WB18.8 39.1 70.8 22.8 1.7 0.0 2.396 17.278 664.350 1934 151.93 3.89 ND 330 4.65

WindBox 18 Hood SGA-WB18.9 36.7 67.2 22.9 1.7 0.0 2.404 17.248 674.460 1818 _ 145.01 3.95 ND 309 4.60

Low primary air includes the period 11:00 to 12:30 North Chamber Estimate: NOx (Ibm/hr) = -77.33987 5.74875 *Fuel (mcfh)

### Table 5.1 Average gas analyses for the Grate-Kiln producing fluxed pellets

Date Sample ID Time Period Statistic NOx ppm (wet) 

### SO2 ppm (wet) 

### CO ppm (dry) 

### 02 % (dry) 

### CO2 % (dry) Samples 35 35 0 36 0 10/07/93 Mean 4.21 274.14 ND 19.024 ND GKF-1 StdDev 0.25 90.36 ND 0.202 ND 14:06 - 17:00 CoefVar,% 5.87 32.96 ND 1.059 ND Samples 4 4 4 4 4 10/08/93 Mean 3.69 1.25 0.40 20.575 0.040 GKF-2 StdDev 0.54 2.17 0.64 0.043 0.000 09:45 - 10:20 CoefVar,% 14.68 173.21 159.10 0.210 0.000 Samples 34 31 20 34 31 10/06/93 Mean 501.18 17526 0.25 15.288 2.435 GKF-3.1 StdDev 49.63 20.80 0.08 0.314 0.143 13:05 -16:00 CoefVar,% 9.90 11.87 32.82 2.055 5.858 Samples 5 6 6 5 6' 10/06/93 Mean 428.00 151.67 0.12 15.300 2.383 GKF-3.2 StdDev 27.86 5.53 0.04 0.395 0.157 16:05 - 16:30 CoefVar,% 6.51 3.64 31.94 2.581 6.597 Samples y 8 8' 8 8 8 10/05/93 Mean 743.75 259.50 2.50 11.900 4.481 GKF-4.1 StdDev 33.14 22.84 1.41 0.260 0.143 11:45 - 12:45 CoefVar,% 4.46 8.80 56.57 2.183 3.202 Samples 10 10 10 10 9 10/05/93 Mean 781.00 242.40 16.60 11.490 4.900 GKF-4.2 StdDev 24.27 13.15 5.41 0.439 0.271 13:00 - 14:32 CoefVar,% 3.11 5.42 32.57 3.822 5.527 Samples 17 17 17 17' 17 10/04/93 Mean 397.06 112.35 33.18 15.165 4.292 GKF-5.1 StdDev 15.44 13.11 4.26 0.185 0.143 13:00 - 15:05 CoefVar,% 3.89 11.67 12.84 1.217 3.323 Samples 5 5 5 5 3 10/04/93 Mean 369.00 89.00 18.60 15.740 4.053 GKF-5.2 StdDev 6.63 3.74 0.80 0.174 0.038 15:10 - 15:30 CoefVar,% 1.80 4.20 4.30 1.108 0.930 Corrected for drift Samples 27 6 6 28 26 09/28/93 Mean 90.176 2.22 3.36 19.462 1.308 GKF-6a StdDev 8.39 0.57 1.19 0.22 0.16 13:05 - 18:30 CoefVar,% 9.30 25.53 35.50 1.14 12.40 Samples 2 3 3 3 3 09/30/93 Mean 238.50 19.33 19.33 16.933 3.133 GKF-6b.1 StdDev 3.50 3.09 0.47 0.170 0.085 11:42 -11:55 CoefVar,% 1.47 15.99 2.44 1.004 2.712 Samples 31 31 30 29 31' 09/30/93 Mean 247.58 27.39 22.92 16.728 3.246 GKF-6b.2 StdDev 12.50 10.63 3.22 0.069 0.043 12:00 - 14:30 CoefVar,% 5.05 38.81 14.06 0.412 1.336 Samples 4 4 4 4 4 09/30/93 Mean 258.75 27.75 25.00 16.925 3.088 GKF-6b.3 StdDev 4.15 7.95 1.41 0.043 0.013 14:35 - 15:00 CoefVar,% 1.60 28.65 5.66 0.256 0.421 Outliers removed

## Table 5.2: Feed & product chemistry for the Grate-Kiln producing fluxed pellets

Date 

### Green Pellets (dry basis) Fired Pellets

Fe Si02 CaO MgO C S Fe+2 Fe Si02 CaO MgO C S Fe+2 Oxidized Calcined Desulfurized

. pct wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct pct

09/28/93 62.27 4.11



### . 3.47 1.07 1.32 162 20.48 63.35 4.37 3.6 1.1 0.074 30 0.25 98.82 94.49 81.80

. 09/30/93 62.61 4.11 3.44 1.05 1.20 115 20.80 63.79 4.04 3.55 1.06 0.060 19 0.63 97.04 95.09 83.78

10/04/93 63.08 3.98 3.25 1.02 1.20 148 21.68 63.96 4.05 3.36 1.02 0.059 16 0.50 97.65 95.15 89.34

. 10/05/93 62.66 3.99 3.60 1.12 1.23 162 21.49 63.64 4.02 3.65 1.13 0.063 28 0.69 96.75 94.96 82.98
10/06/93 62.93 4.01 3.45 1.07 1.10 143 21.09 63.84 4.00 3.47 1.06 0.058 20 0.94 95.58 94.80 86.21

10/07/93 62.55 4.09 3.49 1.09 1.21 153 20.40 63.67 4.11 3.60 1.09 0.053 24 0.88 95.85 95.70 84.59

10/08/93 62.67 4.19 3.46 1.07 1.17 162 21.20 63.71 4.25 3.54 1.07 0.058 20 0.38 98.21 95.12 87.86

Avera • e 62.75 4.06 3.45 1.07 1.19 147 21.11 63.77 4.08 3.53 1.07 0.06 21 0.67 96.85 95.14 85.79

, South preheat fan cyclone dust

09/29/93 62.35 I 4.09 1 3.55 1 1.11 1 1.24 1 146 I 20.53 62.9 I 4.5 I 3.35 [1.211 0.59 11990 1 9.7 I 53.74 I 52.84 I Conc. ..

North preheat fan cclone dust

09/29/93 62.35 4.09 3.55 1.11 1 1.24 146 

### l 20.53 4 63.17 4.01 1 3.07 Ey 1.1 0.541 453] 9.7 1 53.93 I 57.02 Conc.

Oxidation = (1-(3*Fe++/Fe))*100 Calcination: By means of ratios of C/Fe Desulfurization: By means of ratios of S/Fe

## Table 5.3: Summary of measurements for the Grate-Kiln producing fluxed pellets

Date Sample

Period

H:M - H:M Pellet

Feed

It/hr Pellet

Moisture

wt % Kiln

Fuel

mcfh Grate

Fuel

mcfh P1

(max 02)

mcfh P2

(max CO2)

mcfh P3

(max H2O)

mcfh Gas
Sample

I.D. Gas Analyses Estimated
H2O vapor

v%(wet) Gas
Density

Ibm/cf CO2
v% (dry) 02
v% (dry) NOx
ppm (wet)

09/28193 13:05 - 18:30 459.0 9.5 140.0 90.0 330.0 376.5 2093 GKF-6a 1.308 19.462 90.176 5 0.0728
09/30/93 11:42 - 11:55 459.0 9.5 150.0 70.0 329.1 344.4 , 2093 GKF-6b.1 3.133 16.933 238.50 10 0.0719
09/30/93 12:00 - 14:30 459.0 9.5 140.0 90.0 329.1 344.4 2093 GKF-6b.2 3.246 16.728 247.58 10 0.0719
09/30/93 14:35 - 15:00 459.0 9.5 140.0 81.0 329.1 344.4 2093 GKF-6b.3 3.088 16.925 258.75 10 0.0719
10/04/93 13:00 - 15:07 459.0 9.5 160.0 70.0 345.2 344.6 2093 GKF-5.1 4.292 15.165 397.06 7 0.0730
10/04/93 15:07 - 15;30 459.0 9.5 143.0 90.0 345.2 344.6 2093 GKF-5.2 4.053 15.740 369.00 7 0.0730
10/05/93 11:42 - 12:47 445.1 9.5 166.6 70.9 328.7 341.8 2029 GKF-4.1 4.481 11.900 743.75 8 0.0725
10/05/93 12:57 - 14:47 443.5 9.5 158.3 90.3 327.5 340.6 2022 GKF-4.2 4.900 11.490 781.00 8 0.0727
10/06/93 13:07 - 15:57 443.5 9.5 147.9 89.9 317.6 304.1 2022 GKF-3.1 2.435 15.288 501.18 5 0.0729
10/06/93 16:07 - 16:32 443.1 9.5 157.8 71.8 317.3 303.9 2020 GKF-3.2 2.383 15.300 428.00 5 0.0729
10/07/93 14:37 - 16:57 443.9 9.5 136.5 90.7 „ 308.3 338.0 2024 GKF-1 ND 19.024 4.21 0.4 0.0735
10/08/93 09:47 - 10:17 444.0 9.5 179.1 70.3 328.4 324.9 2024 GKF-2 0.040 20.575 3.69 0.4 0.0737

Sample GKF-6a was corrected for drift and contains a large sample-line air leak.

### Table 5.4: Summary of results for the Grate-Kiln producing fluxed pellets

Gas Sampling

Location Gas
Sample

I.D. Kiln

Fuel

mcfh Grate

Fuel

mcfh P1

(actual)

mcfh P2

(actual)

mcfh P3

(actual)

mcfh Gas Analyses Process Gas Flow Measured Process Gas Flow Calculated

CO2
v% (dry) 02
v% (dryLppm NOx

(wet) Gas Flow

mcfh NOx

Ibm/hr NOx

IbmIMMBTU Gas Flow

mcfh NOx

Ibm/hr NOx

Ibm!MMBTU

Waste Gas Fan GKF-6a 140.0 90.0 330.0 376.5 2092.8 1.308 19.462 90.176 ND ND ND 50539 539 2.343

Waste Gas Fan GKF-6b.1 150.0 70.0 329.1 344.4 2092.8 3.133 16.933 238.50 24775 699 3.176 20794 587 2.686

Waste Gas Fan GKF-6b.2 140.0 90.0 329.1 344.4 2092.8 3.246 16.728 247.58 21857 640 2.782 20457 599 2.604

Waste Gas Fan GKF-6b.3 140.0 81.0 329.1 344.4 2092.8 3.088 16.925 258.75 21848 669 3.025 21042 644 2.913

PreHeat Fan. GKF-5.1 160.0 70.0 • 345.2 344.6 0.0 4.292 15.165 397.06 14958 702 3.178 13648 641 2.900

PreHeat Fan GKF-5.2 143.0 90.0 345.2 344.6 0.0 4.053 15.740 369.00 12342 539 2.404 14699 641 2.864

PreHeat Hood GKF-4.1 166.6 70.9 131.5 17.1 0.0 4.481 11.900 743.75 ND ND ND ND ND ND

PreHeat Hood GKF-4.2 158.3 90.3 131.0 17.0 0.0 4.900 11.490 781.00 ND ND ND ND ND ND

Kiln Exhaust GKF-3.1 147.9 89.9 127.0 15.2 0.0 2.435 15.288 501.18 6750 400 2.705 7040 417 2.822

Kiln Exhaust GKF-3.2 157.8 71.8 126.9 15.2 0.0 2.383 15.300 428.00 9379 475 3.008 7568 383 2.427 Cooler Gas (kiln) GKF-1 136.5 90.7 107.9 16.9 0.0 ND 19.024 4.21 ND ND ND ND ND ND
Cooler Gas (duct) GKF-2 179.1 70.3 114.9 _ 16.2 0.0 0.040 20.575 3.69 ND ND ND ND ND ND

Sample GKF-6a was corrected for drift and contains a large sample-line air leak.

### Table 6.1 Average gas analyses for the Straight-Grate producing fluxed pellets

Date Sample ID Sample Period Statistic SO2 ppm(wet) 

### CO ppm(dry) 

### NOx ppm(wet) 

### 02 pct(dry) 

### CO2 pct(dry)

11/29/93

WB 6 Samples 32 34 33 33 8 13:51 Mean 5.352 < 3 48.51 20.403 0.544

to Std Dev 0.92 ND 2.99 0.06 0.04 15:32 CoefVar, % 17.19 ND 6.17 0.32 8.12 11/30/93 '
WB 10 Samples 20 0 20 19 8 15:56 Mean 34.824 ND 176.14 18.143 2.181

to Std Dev 2.75 ND 12.01 0.13 0.08 16:56 CoefVar, % 7.90 ND 6.82 0.72 3.79 12/01/93 WB 12 Samples 40 0 41 42 18 13:54 Mean 7.404 ND 611.11 17.553 2.483

to Std Dev 1.27 ND 121.86 0.50 0.44 15:57 CoefVar, % 17.18 ND 19.94 2.86 17.62 12/02/93 WB 26 Samples 27 0 27 25 7 10:42 Mean 14.943 ND 13.97 20.758 0.046

to Std Dev 9.94 ND 3.29 0.11 0.01 12:00 CoefVar, % 66.52 ND 23.52 0.53 15.93 Outliers Removed

## Table 6.2: Feed & product chemistry for the Straight-Grate producing fluxed pellets

Date 

### Green Pellets (dry basis) Fired Pellets

Fe Si02 CaO MgO est.0 S Fe+2 Fe Si02 CaO MgO est.0 S Fe+2 Oxidized Calcined

wt.% wt.% wt.% wt.% wt.% ppm wt.% wt.% wt.% wt.% wt.% wt.% ppm wt.% pct pct

11/29/93 61.78 4.17 4.14 1.53 1.50 ND 20.94 62.96 4.18 4.68 1.51 0.012 ND 1.32 93.71 99.21

11/30/93 61.83 4.18 4.07 1.53 1.46 ND 20.73 62.97 4.16 4.52 1.45 0.012 ND 1.07 94.90 99.19

12/01/93 65.50 5.78 3.92 1.24 1.35 ND 20.84 ND ND ND ND ND ND ND 94.31 99.20 Average 63.04 4.71_ 4.04 1.43 1.44 ND 20.84 41.98_ 2.78 3.07 0.99 0.01 ND 0.80 94.31 99.20

Oxidation = (1-(3*Fe++/Fe))

. `100 Estimated C in Green Pellets: From CaO + MgO and 0.01 of Fe as FeCO3 Carbon measured on grab-sample taken on 12/01/93 but average oxidation & calcination assumed Calcination: By means of ratios of C/Fe

## Table 6.3: Summary of measurements & estimates for the Straight-Grate producing fluxed pellets.

Date Sample

Period

H:M - H:M Pellet

Feed

It/hr Pellet

Moisture

wt % Est.A

Fuel

mcfh Est.B

Fuel

mcfh P1

(max 02)

mcfh P2

(max CO2)

mcfh P3

(max H20)

mcfh Gas
Sample

I.D. Gas Analyses Estimated
H2O vapor

v%(wet) Gas
Density
',amid CO2 v% (dry) 02 v% (dry) NOx ppm (wet)

11/29/93 13:51 - 15:32 390.7 9.5 235:2 194.7 272.4 382.4 1781.5 SGF-WB6 0.544 20.403 48.51 0.5 0.0739

11/30/93 15:56 - 16:56 344.8 9.5 207.5 171.8 240.9 328.3 1571.9 SGF-VVB10 2.181 18.143 176.14 1.0 0.0742

12/01/93 13:54 - 15:57 276.9 9.5 166.7 138.0 193.3 243.9 1262.6 SGF-VVB12 2.483 17.553 611.11 1.5 0.0741

12/02/93 10:42 - 12:00 ND ND ND ND ND ND ND SGF-WB26 0.046 20.758 13.97 0.04 0.0738

Fuel Estimate A: From the daily consumption on 12/01/93, 0.662 million BTU per long ton product Fuel Estimate B: From a long-term average of 0.548 million BTU per long ton product

## Table 6.4 Chemical Analyses of windbox dust and pellets for the Straight-Grate producing fluxed pellets.

Sample Description Fet wt % Fe+ 2 wt % Si wt % C wt % S wt % Oxidation' Pct. Calcine 2 Pct.

Green Pellets 60.2 20.2 1.8 1.56 0.0160 0 0

WB 10 60.8 15.7 1.8 1.46 0.0272 22.5 7.3

WB 15 53.2 6.5 2.0 2.25 0.0685 63.4 Conc 3

WB 19 53.2 9.0 1.8 2.38 0.0482 49.3 Conc 3

WB 20 58.0 9.5 ND 1.39 0.137 50.9 7.52

WB 21 60.6 10.6 1.8 1.03 0.181 47.5 34.4

WB 23 61.0 9.7 1.8 0.96 0.165 52.3 39.3

Fired Pellets 61.0 1.4 2.0 0.0115 0.0014 93.1 99.3

1. Oxidation, % = (1 - ((3•Fe+ 2 1/Fe t 11"100 2. Calcination, % : By means of C/Fe ratio. 3. Carbon is concentrated in these samples.

### Table 6.5: Summary of results for the Straight-Grate producing fluxed pellets.

Gas Sampling

Location Gas Sample

I.D. Est.A

Fuel

mcfh E st. B

Fuel

mcfh P1

(actual)

mcfh P2

(actual)

mcfh P3

(actual)

mcfh Gas Analyses Calculation with Fuel Est. A Calculation with Fuel Est. B

_ CO2 v% (dry) 02 v% (dry) NOx ppm (wet) Gas Flow

mcfh NOx

lb/hr NOx

lb/MMBTU Gas Flow

mcfh NOx

lb/hr NOx

lb/MMBTU
Windbox 6 Hood SGF-WB6 235.2 194.7 0.0 0.0 178.1 0.544 20.403 48.510 3271 18.77 1.23 2739 15.71 1.24
Windbox 10 Hood SGF-WB10 207.5 171.8 144.6 171.4 0.0 2.181 18.143 176.140 15406 320.91 2.12 14074 293.16 2.34 Windbox 12 Hood SGF-W812 166.7 138.0 9.7 21.9 0.0 2.483 17.553 611.110 2836 204.96 4.55 2488 179.80 4.83 Windbox 26 Hood SGF-WB26 ND ND ND ND ND 0.046 20.758 13.970 ND ND ND ND ND ND

Fuel Estimate A: From the daily consumption on 12/01/93, 0.662 million BTU per long ton product Fuel Estimate B: From a long-term average of 0.548 million BTU per long ton product Fractional representation of fuel used in calculations: WB6, 6.5%; WB10, 73%; WB12, 27%.

### Table 6.6: Range of results for sample SGF-WB12 as the representation of fuel flow and pellet oxidation and pellet calcination is varied.

Oxidation Fraction 0.3 0.4 0.5 0.3 0.4 0.5 0.3 0.4 0.5 0.09 0.12 0.15 Calcination Fraction 0.4559 0.5090 0.5620 0.3966 0.4496 0.5027 0.3373 0.3903 0.4434 0.1190 0.1349 0.1508
Fuel Fraction 1.25 1.25 1.25 1.00 1.00 1.00 0.75 0.75 0.75 0.30 0.30 0.30 P1, mcfh 57.31 76.41 95.51 57.31 76.41 95.51 57.31 76.41 95.51 17.19 22.92 28.65 P2, mcfh 110.36 123.22 136.05 96.01 108.84 121.69 81.65 94.48 107.34 28.81 32.66 36.51 Fuel, mcfh 208.31 208.31 208.31 166.65 166.65 166.65 124.99 124.99 124.99 50.00 50.00 50.00, Calculated air flow, mcfh 13225 13758 14291 10900 11433 11966 8575 9108 9641 3270 3430 3590 Calculated total flow, mcfh 13009 13534 14058 10722 11246 11771 8436 8959 9484 3217 3374 3531 NOx flow, lb/hr 988 1026 1065 813 852 890 639 677 716 244 256 267



### Table 6.7: Range of results for sample SGF-WB10 as the representation of fuel flow and pellet oxidation and pellet calcination is varied.

Oxidation Fraction 1.00 0.95 0.90 1.00 0.95 0.90 1.00 0.95 0.90 0.75 0.70 0.65 Calcination Fraction 0.9820 0.9540 0.9260 0.8974 0.8695 0.8415 0.8129 0.7849 0.7570 0.5885 0.5606 0.5326
Fuel Fraction 1.25 1.25 1.25 1.00 1.00 1.00 0.75 0.75 0.75 0.50 0.50 0.50 P1, mcfh 238.07 226.17 214.26 238.07 226.17 214.26 238.07 226.17 214.26 178.55 166.65 154.75 P2, mcfh 320.06 310.95 301.82 292.50 283.40 274.28 264.96 255.83 246.72 191.82 182.71 173.58 Fuel, mcfh 259.37 259.37 259.37 207.50 207.50 207.50 155.62 155.62 155.62 103.75 103.75 103.75 Calculated air flow, mcfh 25970 25562 25153 22410 22002 21593 18850 18441 18033 13247 12839 12430 Calculated total flow, mcfh 25674 25271 24866 22155 21752 21347 18636 18231 17828 13096 12693 12288 NOx flow, lb/hr 555 547 538 479 470 461 402 393 385 282 274 265

# FIGURESaqmapewrilequiniv°gold6uijdwesseD 

## Figure 1.1 Pellet bed inside a laboratory furnace



# o o

I 

# (

0 N V o 4uopatuiisnapueseD04seped eup.unlyamprupequinly

# Figure 1.2 Photolytic cycle for nitrogen oxides in the atmosphere

## 1/4" NPT Stainless Steel Type 316

KEY 

# Figure 2.1 Gas sampling probe

Water In Water Out

1 

## - Inner Tube 2- Nut 3- Back Ferrule 4- Front Ferrule 5 - End Body Of Water Jacket 6- Outer Body Of Water Jacket 7- Divider Tube Of Water Jacket

## 1 - --. -- ..- -

14 

# — 1 0 cm 

# Figure 2.2 Filter ancl.liner insert for the gas sampling probe

1 2 5

A. 

# - Filter In Holder

2 3 4

r

om• ■

••• ••••••••



# B. 

# - Filter Outside Of Holder
KEY
1 - Liner 2 

# - Filter Holder 3 - Tapered Sintered Bronze Filter 4 

# - Neoprene 0-Ring 5 

# - End Pipe

### Tempering air fan

Stack Burner


### 0 

# Figure 3.1 Process flow diagram for the Grate-Kiln producing acid pellets

/

1 \ V Drying zone 

### 0

Preheat Green pellets -\

Stack Kiln

Waste gas fan 1A & 1B preheat fans Annular cooler

3A 3BI • Cooling fans mir Fired pellets 

# NI17.9

17.8

i 17,7

O

N 17.8

17.5 1.52

t

1.48 

## It 1.44

1.38 300

280

260

240

220

200

80

55

50

45

40

35 12

10

8


## 8 4

2 20 40 BO 80 100 SAMPUNG TIME, min 120 140 180 

### Figure 3.2 Gas analyses for the sample GKA-6a 10/18/93I I 1.90

O 1.88

1.86

1.84
330

V:

, 320

a 310

O •

300

290 140

f

. ) 130

E a 120

m 110 16.6

1.96

1.94

1.92 15.4 Figure 3.3 Gas analysis for the sample GKA-5 10/19/93

20 40 60 80 100 120 SAMPLING TIME. min18.2

• :;

(*1 17.0

16.8

150 200

1.2

100 SAMPLING TIME, min Figure 3.4 Gas analysis for the sample GKA-3 10/20/9319.5

18.5

-1? 17.5 

### lg.

. 16.5 

### o

N

15.5

14.5 1.4

1.3

1.0

0.9 260

140

60

; 50 E



### 0 40

30 Figure 3.5 Gas analysis for the sample GKA-6b 10/21/93

150 200 250 300 SAMPLING TIME, min1.1

1.0

0.8

240
V; 220 3

ix 200 ;( 0 Z 180

50 100 SAMPLING TIME. min 150 200CO,ppm(dry) Figure 3.6 Gas analysis for the sample GKA-6c 10/22/93I 515 - 

### Figure 3.7 Selected operating data for the GKA-3 sampling period

I 1 I T T •

Air \ \ 

## - V \ 7 '
\ 1 '. I

, / / I i 1 .'--' \ 7 

### I I ' . \. 7 I 1 1 T ' 1 / 77 I ' 

### V 

## N I i 1 

### \ k ■ \ : / 

## 1
, ,li I i



## . I 7 1 1 1 i

I V 1

-...... -- 1 1 1 ■
200

I ,

IVW

114 1/

•

1 1. \ 7 \

A/ 

# ,... \ \



# . , 7 i\ i i \\\\

\ 1 

# A 1 / P 1 j 1 

### i } 

### 1 '1 

### 1\i \ 1 f I

- ..,... 2198 -

1.i. 2196 1 1 1 1 I ---ir\; - 21 1\
so IS 2194

2192 

## I , I 

### / I

2190 1- 2188 1 ,../..„..

r 1 2186 1 \\)/ u1) 2184 

## \ l '\\-- \ 1 7 I 2182 0 50 100 Gas Sampling lime, min 150 200I .11010110

490 i ! !! ! ! ! ! 1 ■ !, ! , ! Ni
480 , I!

470 !reed !
460

450 .." I I

\ !Fuel

\ ! I L
440

430 \ / .--- - , . 

# ' U ! Gas Sampling

. 420 I i a i r
0

a 0

1)

. 0 210

200

190

. 180

0 T. 0

170

1 2 160

Z

150

140

130 

### Figure 3.8 Selected operating data for the GKA-5 sampling period

450 -130



### E

2. 3 120 0 

### E

400 I 3B

WG
• c"

co

110 a ca LL 350 

## IN/



## _ ) /Nz 3A

300 -! C CO U- (6 0 0

100 Gas !Sampling

660 720 780 840 900 960 Time of Day, minU) f)

4:

120 "E

0

ea

110 en

co u_

0 U 

### Figure 3.9 Selected operating data for the GKA-6a sampling period

220

210

200

- 190

180

1 2. 3 170

160

150

140 -. '-...111.4

500 ii\i i i \ 490

480

470 /\ / \ \' I \ I Feed 1 l\ \ 1 I 1 i kui l 

# INF i t li r 

# ., wrii
, 

# vam , NM 

# I

• If Y
1

, I 460

450

440 > Fuel \ /I \

-7 ---- I

. \/)

1 Gasl Sampling

.

, 430 • 1GreenPelletFeed,longton/hr

450

U) a. 

### E

400

03 

### u_ 350 CD a)

300 -- 660 720 3B

WG

3A

780 Time of Day, min Gas Sampling

840 900I 490

480 - 

### Figure 3.10 Selected operating data for the GKA-6b sampling period

A 1 I 1 ■ 1 1 I

1

g °

470 1 / 1 ' I ' I ' ' -"-"''' \ 1J 1 , ' 1 ' • i I i

. 1 1 ;. , t 

### R ivu V fl
,, .1, i , , 1 , 

### , 

## L

, 1:1 0 o Li. 7i

'

- g 46° 1 i 7 I I I ■

i \ ; ! \ ! I I 1\ i I A1t i \ 1, 71 1 1 7

a. c e 12 0 450 I I \ j I n\ I / \/ 1 7 1 1 \ I t I / I I 1 1 '‘,...! 1 i i 

### i ! t v 1 t • 1 \i

,

440 - 165 -

160 1 1 I 1 ! I 1 1
I I I

I I t 1 A i

, f , '

, 155 I ! !7 i k / 1 I i 

## 150 Tv-- 1

. , 1 t , , 1

: \y-, ■ I \ h 1 t - \ ;
0 145 

### 1 , i

,

1 1 I MIIIIIIIIIIIMILIEWMINNIIIMMIL Ali

i A

I i 71 = 1 iao I \i... 1 ! I i I 1 i 135 1 I I y 130 -r 400 - ! YYY 1

,

I ..\. 11 Nr

/

' / i \ 1 1-

! n \

Jul 

### I V i i t

' 

### 1 ,.../

,

, ........ 2166 - 1 

## r\; 1

1 17 

## \.;\ 1 1 

# v 7\"-\jiV , I
1 1 1 1 I 1 1 1 1 1
1 \ 2 1 1
1 1 \ I 

### 1

- .....- I 1 1 I

0 5 0 100 150 200 250 300 350 Gas Sampling Time, min

### Figure 3.11
Selected operating data for the GKA-6c sampling period

1 1 '

. 1 ' % 7 

### A 7.\ \L- ...A \ 

## 7

. \(\

....,. ,- 

## r 1 • \- 

## \1 1 /% 1 / \A 

## / I;NetFeed, 

## I! 1 \ ! v...--\. A 7' \ 7 \ r

155 -

150 

## 7 7 1 i

145

.. 11 I I 1

1 

### g 140


## : 0 135 ! 

## 7-- l



## : n, 

## \ I L
-g 

## i

. N\\\. 

## \ ! ,

125 I %,

120 1 1

365 —

350 i in 

# 1 r z E 355 i 

## I c.)



# . . „. , 1 

# \.-- \

Iwo \Z 

# i\I g / : -i , 1,/ 2 \/"\i i.7

345

-. 2120SecondaryAlrTemperature.deg.F41..,......,,gK.,r.gOD■II.I 1

4.8 OW 0 50 100 150 MO Gas Sampling Time, minCubicFeetper Minute



## 340 345 350 355 360 365 370 375 380 385 390 Motor Amps ACFM + SCFM 395 

# Figure 3.12 Relationship between waste gas flow & fan current draw

## Figure 3.13 

## Combustion curves for the Grate-Kiln producing acid pellets

### 0 0 

### 0 0 

# Figure 3.14 Relationship of NOx with CO2 for a Grate-Kiln producing acid pellets

700

600

47 500

Q 400

>i" 0 z 300

200 -

100 -,
0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 CO2, pct (dry) 0

0



# c2)

0 100 

### 0 00 0 O 

### 9) 0 0 (,' cs9 O 

# .

0

( §--• 0



### 0

+ GKA-6a A GKA-5 0 GKA-3 GKA-6b x GKA-6c

# Figure 3.15 NOx mass flows for the Grate-Kiln producing acid pellets

Li A

AA

Ei Li Cl 11 A

A --A 

## 700

s 

## _ 650



## 0 600

(l) CO

c 

## u 550



# 0 500

450 125 135 145 155 165 

# Natural Gas Flow, mcfh

o Process Flow Measured L 

## Process Flow Calculated

# Figure 3.16 Ratio of NOx flow to fuel input for a Grate-Kiln producing acid pellets

H I

- 7

A A

AD

ila A

A D

ILII -

LI 

## 3.0 125 4.8

4.6

4.4

m 4.2

.2 4.0

3.8

3.6 0 Z 3.4

3.2

135 145 155 165 

# Natural Gas Flow, mcfh

Process Flow Measured IA 

## Process Flow CalculatedHood exhaust fan

Primary combustion From windbox chambers recup. fan Recup.

fan bypass 

# Figure 4.1 Process flow diagram for the Straight-Grate producing acid pellets

Windbox exhaust fan

Green pellets V

First cooling zone

Burners MIC49111

11111111111

Updraft drying zone Down draft drying
zone Preheat zone 1

1 2 3 4 5 8 7 8 9 10 11 12 13 14 Updraft Windbox Windbox No. drying exhaust Windbox recup 15 16 17 18 19 20 21 2223 24 Second cooling zone Fired pellets

25 26 27 28 29 30 31 32 33 34 3538 37 38 Cooling air duct

Ambient air

1 1

—

Dust

collector Updraft drying fan Windbox recup. fan Cooling air fanMa 20.3

40 

### a a x 0



# ND • 4

• 3 

### a O 0

2

1 0 10 20 30 40 50 SAMPLING TIME. min 0.34

--- 0.30

0. 0.26

tV 0 C. )

0.22

0.18

30
11



### • 3

7 

### a

0 49 5

3

5 Figure 4.2
Gas analysis for the sample SGA-WB16 04/20/94

20.7

20.6

15 20.5

o 20.4200 250 50 100 150 SAMPUNG TIME, min Figure 4.3 Gas analysis for the sample SGA-VVB18 04/21/94

Low Primary Air
16.4

2.8

'F 2.6

a s 2.4 iv 0 0 2.2

2.0 800

700 - Low Primary AirNOx,ppm(wet)

5

4

3

2

1 0 

## ND

## Figure 4.4 Combustion curves for the Straight-Grate producing acid pellets

## Figure 4.5 Relationship of NOx with CO2 for a Straight-Grate producing acid pellets

800
O 

### O 0

El 

## 750

0


## 4. -7. 700



# g. 650 a.

0 z 600

550 -

500 , 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 CO2, pct (dry)

o WB18 Normal • WB18 Low Primary Air

# Figure 4.6 NOx mass flows for the Straight-Grate producing acid pellets

350

300 L 

## ._ _c

250

Cl) cn 

## a



## s 200

O 

## 150

100 , 30 40 50 60 70 80 

# Natural Gas Flow, mcfh

A North Chamber Estimated ri 

### South Chamber Regression

# Figure 4.7 Ratio of NOx flow to heat input for a Straight-Grate producing acid pellets

4.6

4.4

m 4.2
0

• 4.0
1

. 23

x

-

3.8 0 

# z 3.6

3.4 20 A AA
f - (_\ \

I

El 171 FT



## n Li 71



### ■ 

## ri

40 60 80 100 120 

# Natural Gas Flow, mcfh

Whole Furnace Estimated o South Combustion ChamberTempering air fan

Stack
A -4(

Burner



### 0 

# Figure 5.1 Process flow diagram for the Grate-Kiln producing fluxed pellets

Green pellets 

### IN V
Burner—•0 Drying zone

Stack 

# • Burners 

# sci \ b

Preheat 2 burners



### •
Kiln

Annular cooler

Waste gas fan 1 A & 1B preheat fans Fired pellet;

3A 3B

• Cooling fans •Figure 5.2 Gas analysis for the sample GKF-1 10/07/93Figure 5.4 Gas analysis for the sample GKF-4 10/05/93Figure 5.5 Gas analysis for the sample GKF-5 10/04/9319.0 1&8 Figure 5.6 Gas analysis for the sample GKF-6a 09/28/93fr

28

a

24 C. O 0

20

16

0 50 100 150 SAMPLING TIME, min 32 Figure 5.7 Gas analysis for the sample GKF-6b 09/30/93

17.1

16.9
1

ON 16.7

16.5

3.3

3.2

o a t

270
I

260

o. - 250 O

x 240

230 50

40

a 30 C.

CV

10

200 250160 —

t 140 — E

-q 120 — LL

I! 100 —

Z -

80 —

60 - Grate

r

L

r r 450

448
E 0 0

, 44 6- 0 ti c

444 tL

113 CL 442 - c co

440 —

438

125 380

370 E 0

- ee

360 a 

### z

350 

## 8

U340 is

330 g

320
50 100 150 200 250 Gas Sampling Time, min 95 0 Figure 5.8 Selected operating data during the GKF-3 sampling period

## ,Figure 5.9 Combustion curves for the Grate-Kiln producing fluxed pellets

2 3 4 5 6 CO2, Volume Percent (dry)

## 0 2 3 4 5 6 CO2, pct (dry) 

# Figure 5.10 Relationship of NOx with CO2 for a Grate-Kiln producing fluxed pellets

1 000

800

600 - 

# E

400 0

200

0

o GKF-3 + GKF-4 ❑ 

## GKF-5 v GKF-6b x GKF-6a r

L

r

L

r

r 

# *NW -

J

. L

## 750

700

X650 .ift 600

0
0 

## 550
co 

# (13 E 500

z o 450

400



# Figure 5.11 NOx mass flows for the Grate-Kiln producing fluxed pellets

LX\

A 

### A r I A

I

A - .1 Ll

Li Li A



## 350 140 160 180 200 220 240 

# Natural Gas Flow, mcfh

A 

## Process Flow Measured Process Flow Calculated

# Figure 5.12 Ratio of NOx flow to fuel input for a Grate-Kiln producing fluxed pellets

3.3

LX\ 

## 3.1

00


## 0 

## c • 2 9

n 2.7

0
2.5 A

A



## 2.3 - 140 160 180 200 

# Natural Gas Flow, mcfh 220 240

A Process Flow Measured IA 

## Process Flow CalculatedWindbox recup. fan Ambient air .4.---

Cooling air fan Updraft Windbox Windbox

drying exhaust recup



## 0 Cooling air duct

Dust 1

collector Updraft drying fan Windbox No. 

# Figure 6.1 Process flow diagram for the Straight-Grate producing fluxed pellets

Hood exhaust fan

Windbox exhaust fan Recup. bypass fan Primary combustion

From windbox chambers n4--Burners recup. fan

•••

Green pellets Updraft drying zone Down draft drying

zone • •

eN. es% 4/**
, 0.

0 "••• / I



## :::-.7"

. = r

...

..) v ::.)

..., 

### r-i 1

...... .....- . 1 Preheat zone..2::2_ " --J (eight burners) .• ■ • ■

• 1111.• • •

First cooling zone = Second cooling

zone Fired pellets

1 2 3 4 5 6 7 8 9 10 1112 1314 1516 17 18 1920 21 22 23 24 2526 2728 29 30 31 32 33 34 35 36 37 38



### VFigure 6.2 Gas analysis for the sample SGF-WB6 11/29/93Figure 6.3 Gas analysis for the sample SGF-WB10 11/30/93

### Figure 6.4 Gas analysis for the sample SGF-WI312 12/01/93Figure 6.5 Gas analysis for the sample SGF-WB26 12/02/93L

-

i I I
I I ; I

I I I I I t I 

## Figure 6.6 Burn-through temperature and NOx for a Straight-Grate producing fluxed pellets.

1100

^ 1000

E 4 15 §. 900 0. ><- 800 0 

# z 700 L 2): 600

T. a) 500 E F a 2 400

300 600 660 720 780 840 900 960 1020 1080 1140 1200 Time of day, min

## Key * WB6 0 WB10 0 WB12
A 

## WB26 Theoretical 

## Figum 6.7 Combustion curves for the Straight-Grate producing flux pellets

21

0-... , 20 G. -

. 0

C 0 4) 19 

## a) a. a) 1 8

=

a 

## 0 17

16 0 0.5 1 1.5 2 2.5 3 3.5 

## CO 2 , Volume Percent (dry)

## Figure 6.8 Relationship of NOx with CO2 for a Straight-Grate producing fluxed pellets.

1000 -

800

.1.7 3

) 600 E a a )i 400 0 z

200

1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 CO2, pct (dry) _,

1 

## Is

WB12 ED

WB10

# Figure 7.1 NOx mass flows measured for iron ore pelletizing furnaces

• • • • • • • • 4 - -4

,

1



### A



# 350 -, 100 750

700

2E 650

*. 

# :c3 - 600 O



## co 

# 550 co 

# E 500

° 450

400 I I I

4
,

4 

### A

L

r

r IIA -

• •

I I
I I

1 • r t I I 

### AP
, -

-



# 120 140 160 180 200 220 240 

# Natural Gas Flow, mcfh

o 

# GKA ❑ GKF v SGA Solid points indicate values derived from process gas flow measurements

# Figure 7.2 Ratio of NOx flow to heat input for iron ore pelletizing furnaces

5.0

4.5

m 4.0
0

•

_ 3.5 

# 113

0 •



## 3.0

z 2.5

2.0 , 100 I I

I I

I I

- I- 4,

I I

I I 1 1

I I

I I

L
,

I I 

### A



## U

r 1111



## 120 140 160 180 200 220 240 

# Natural Gas Flow, mcfh A

A

✓ r



### A 

## GKA a GKF v SGA Solid points indicate values derived from process gas flow measurements

# APPENDIX AGrate-Kiln 10/18/93

Hr : Mn Port 6a CO2 Time % (dry) Acid CO SO2 NOx ppm (dry) ppm (wet) ppm (wet) 02 % (dry) 11 : 27 0 1.49 7.81 44.3 270.6 17.10 11 : 30 3 1.49 7.01 48.7 241.5 16.22 11 : 33 6 1.49 6.57 48.8 228.4 15.85 11 : 39 12 1.49 5.14 17.82 11 : 42 15 1.49 4.93 47.2 281.7 17.71 11 : 45 18 1.50 5.33 46.4 276.0 17.72 11 : 48 21 1.47 4.71 48.0 259.8 17.68 11 : 51 24 1.41 3.91 51.5 266.1 17.74 11 : 54 27 1.46 3.64 50.0 262.4 17.63 11 : 57 30 1.45 3.57 48.5 240.4 17.62 12 : 0 33 1.44 9.92 39.3 222.5 17.66 12 : 3 36 1.42 9.56 49.2 217.3 17.63 12 : 6 39 1.44 8.55 50.3 246.6 17.62 12 : 9 42 1.39 7.58 45.3 215.1 17.69 12 : 12 45 1.38 7.03 48.1 206.5 17.72 12 : 15 48 1.43 6.86 48.3 245.8 17.64 12 : 18 51 1.45 9.79 45.5 235.1 17.64 12 : 21 54 1.42 8.88 50.3 220.9 17.64 12 : 24 57 1.43 8.43 55.6 222.4 17.65 12: 27 60 1.44 8.86 52.1 218.9 17.60 12 : 30 63 1.48 10.59 17.80 12 : 33 66 1.47 9.79 56.6 248.9 17.62 12: 36 69 1.48 9.62 59.2 258.4 17.62 12: 39 72 1.49 9.86 57.3 269.5 17.60 12 : 42 75 1.48 9.88 54.1 276.6 17.66 12 : 45 78 1.45 9.56 55.7 232.4 17.67 12 : 48 81 1.42 9.11 59.0 228.6 17.67 12 : 51 84 1.41 9.11 38.4 202.4 17.82 12: 54 87 1.42 8.81 48.5 220.7 17.76 12 : 57 90 1.41 8.54 53.7 221.9 17.73 13 : 0 93 1.41 8.58 56.0 218.0 17.72 13 : 3 96 1.44 8.37 55.8 252.6 17.68 13 : 6 99 1.40 8.03 55.1 224.3 17.78 13 : 9 102 1.38 8.02 58.2 212.4 17.77 13: 12 105 1.40 7.63 59.2 223.0 17.73 13 : 15 108 1.38 7.60 56.8 203.8 17.73 13 : 18 111 1.39 7.05 58.8 225.8 17.72 13 : 21 114 1.41 10.68 17.82 13 : 24 117 1.42 10.86 48.6 214.6 17.70 13 : 27 120 1.44 10.89 51.4 222.6 17.65 13 : 30 123 1.44 10.96 53.8 219.8 17.64 13 : 33 126 1.44 10.76 57.7 243.2 17.61 13 : 36 129 1.44 10.51 55.6 229.1 17.66 13 : 39 132 1.42 10.41 54.5 216.3 17.67 13 : 45 138 1.44 11.33 40.9 248.7 17.57 13 : 48 141 1.42 11.17 56.8 212.6 17.61 13 : 51 144 1.42 10.91 55.1 227.4 17.60 13 : 54 147 1.44 10.99 55.6 256.2 17.54 13 : 57 150 1.43 10.91 56.7 224.0 17.56 14 : 0 153 1.41 10.65 56.4 218.2 17.57 Boxed values are identified as outliersGrate-Kiln 10/19/93

Hr : Mn Port 5B Acid NO NOx SO2 Time ppm (wet) ppm (wet) ppm (wet) ppm CO (dry) 02 % (dry) CO2 % (dry) 13 : 29 0 300 320 130 10.0 16.60 1.90 13 : 34 5 300 300 130 9.0 16.40 1.90 13 : 40 11 310 310 130 8.5 15.90 1.90 13 : 46 17 330 300 120 8.5 15.80 1.90 13 : 50 21 310 295 120 8.0 15.80 1.90 13 : 55 26 310 305 120 7.5 15.60 1.90 14 : 0 31 310 305 130 7.0 15.50 1.90 14 : 5 36 300 300 120 6.5 15.60 1.90 14 : 10 41 300 315 120 6.5 15.50 1.90 14 : 15 46 330 330 120 6.0 15.40 1.95 14 : 20 51 310 310 130 10.5 16.20 1.90 14 : 27 58 2901 290 120 10.5 16.00 1.90 14 : 35 66 310 315 120 9.5 15.70 1.90 14 : 40 71 310 310 120 10.0 15.70 1.85 14 : 50 81 330 310 110 9.0 15.70 1.85 14 : 55 86 320 310 120 8.5 15.70 1.85 15 : 0 91 320 310 110 8.5 15.70 1.85 15 : 6 97 320 320 110 11.0 16.10 1.90 15 : 10 101 320 320 120 10.0 16.00 1.90 15 : 15 106 320 320 120 10.0 16.00 1.90 Boxed values are identified as outliersGrate-Kiln 10/20/93

Hr : Mn Time Port 3 CO2 % (dry) Acid CO SO2 ppm (dry) ppm (wet) ppm NOx (wet) Page 1 of 2 02 % (dry) 10 : 24 0 1.66 0.00 21.8 574.7 17.17 10 : 27 3 1.66 0.00 34.3 527.4 17.16 10 : 30 6 1.89 0.00 37.5 608.0 16.79 10: 33 9 1.74 0.00 35.4 604.7 16.78 10 : 36 12 1.55 0.00 27.4 582.1 16.88 10 : 39 15 1.55 0.00 36.6 561.6 16.79 10 : 42 18 1.46 0.00 33.9 516.7 16.83 10 : 45 21 1.56 1.15 30.9 536.3 17.56 10 : 48 24 1.64 0.93 32.3 563.2 17.50 10 : 51 27 1.40 0.57 33.4 556.0 17.97 10 : 54 30 1.69 0.28 41.5 543.3 17.14 10 : 57 33 1.49 0.00 35.6 524.2 17.56 11 : 0 36 1.35 0.00 34.5 529.5 17.58 11 : 3 39 1.41 0.00 30.2 487.2 17.49 11 : 6 42 1.27 0.00 29.4 514.6 17.94 11 : 9 45 1.48 0.92 24.8 537.9 17.64 11 : 12 48 1.61 0.37 28.8 506.4 17.49 11 : 15 51 1.52 0.30 30.6 569.6 17.49 11 : 18 54 1.65 0.03 30.2 544.6 16.83 11 : 21 57 1.16 0.00 31.5 461.5 17.84 11 : 24 60 1.38 0.00 28.8 459.5 17.36 11 : 27 63 1.51 0.00 30.1 545.4 17.20 11 : 30 66 1.46 0.00 22.7 558.3 17.45 11 : 33 69 1.57 0.00 30.5 494.2 17.09 11 : 36 72 1.35 0.00 34.9 467.9 17.32 11 : 39 75 1.56 0.00 36.2 575.2 17.17 11 : 42 78 1.52 0.64 27.0 500.9 17.07 11 : 45 81 1.61 0.46 37.3 560.4 17.40 11 : 48 84 1.53 0.27 33.0 612.2 17.63 11 : 51 87 1.59 0.04 44.5 550.4 17.37 11 : 54 90 1.66 0.08 31.7 587.5 17.53 11 : 57 93 1.76 0.14 29.3 677.7 17.04 Boxed values are identified as outliersGrate-Kiln 10/20/93

Hr : Mn Time Port 3 CO2 % (dry) Acid CO SO2 NOx ppm (dry) ppm (wet) ppm (wet) Page 2 of 2 02 % (dry) 12 : 0 96 1.60 0.00 29.7 594.4 17.31 12 : 3 99 1.74 0.00 31.7 610.2 16.61 12 : 6 102 1.36 0.00 27.8 553.3 17.60 12 : 9 105 1.36 0.00 30.5 513.3 17.47 12 : 12 108 1.44 0.00 32.3 540.2 17.49 12 : 15 111 1.55 0.00 38.7 492.7 17.17 12 : 18 114 1.50 0.00 36.9 530.5 17.31 12 : 21 117 1.26 0.00 44.2 491.8 17.73 12 : 24 120 1.39 0.03 15.0 497.7 17.63 12 : 27 123 1.43 0.79 33.7 538.1 17.92 12 : 30 126 1.53 0.45 32.1 489.2 17.75 12 : 33 129 1.56 0.44 35.8 570.6 17.42 12 : 36 132 1.32 0.40 31.7 516.3 18.06 12 : 39 135 1.40 0.42 37.3 497.0 17.73 12 : 42 138 1.33 0.31 33.0 497.7 17.88 12 : 45 141 1.17 0.36 28.9 489.5 18.09 12 : 48 144 1.31 0.40 26.0 486.4 17.64 12 : 51 147 1.41 0.51 27.6 514.1 17.90 12 : 54 150 1.51 0.78 33.6 508.9 17.56 12 : 57 153 1.34 0.63 34.4 482.6 17.80 13 : 0 156 1.53 0.77 29.8 416.0 17.35 13 : 3 159 1.36 0.92 38.0 479.4 17.79 13 : 6 162 1.36 0.96 29.7 482.1 17.67 13 : 9 165 1.40 0.93 30.1 481.0 17.70 13 : 12 168 1.17 0.86 33.6 455.8 18.01 13 : 15 171 1.33 0.721 48.8 464.1 17.62 13 : 18 174 1.53 0.82 40.8 416.01 17.35 13 : 21 177 1.42 0.85 36.3 478.9 17.65 13 : 24 180 1.43 0.68 33.2 514.5 17.30 13 : 27 183 1.39 0.61 37.0 17.64 Boxed values are identified as outliersPage 1 of 2 02 02 (dry) Corrected 20.77 21.61 17.88 18.73 17.80 18.67 19.94 20.82 16.93 17.83 16.42 17.33 16.17 17.10 16.05 16.98 16.04 16.99 16.03 16.99 16.03 17.01 16.10 17.09 15.98 16.99 15.99 17.01 15.99 17.02 15.79 16.84 15.88 16.94 15.86 16.94 15.96 17.05 15.97 17.08 16.00 17.12 16.05 17.19 16.08 17.23 16.11 17.27 15.68 16.86 15.74 16.93 15.81 17.02 15.86 17.08 15.93 17.16 15.93 17.17 15.95 17.22 16.01 17.29 16.03 17.31 16.02 17.32 16.80 18.12 15.64 16.97 15.74 17.08 15.73 17.09 15.80 17.17 15.89 17.28 15.91 17.31 15.97 17.39 15.97 17.40 15.94 17.38 15.90 17.36 15.89 17.36 15.94 17.43 15.93 17.43 15.96 17.47 15.51 17.04 15.62 17.16 NOx ppm (wet) 4.81 258.1 240.6 149.3 209.0 245.8 218.3 207.1 218.8 220.9 236.9 211.3 240.2 213.2 215.3 226.1 225.1 221.6 222.9 207.8 208.9 207.5 196.8 198.8 242.5 229.5 221.3 218.2 203.5 217.1 202.7 195.4 182.0 187.0 I

6.0 213.5 218.5 233.5 211.7 220.3 201.8 187.8 170.7 200.5 223.1 195.7 188.8 178.4 168.7 203.4 195.0 Grate-Kiln 10/21/93

Hr : Mn Time Port 6b CO2 % (dry) Acid CO ppm (dry) SO2 ppm (wet) 11 : 28 0 0.00 0.61 11 : 31 3 1.30 7.66 33.3 11 : 34 6 1.27 7.11 38.7 11 : 37 9 0.00 39.4 11 : 40 12 1.20 6.76 52.4 11 : 43 15 1.28 6.60 51.3 11 : 46 18 1.25 5.85 48.1 11 : 49 21 1.21 5.56 47.7 11 : 52 24 1.22 5.57 45.4 11 : 55 27 1.21 5.53 44.7 11 : 58 30 1.19 4.86 48.4 12 : 1 33 1.14 4.31 46.5 12 : 4 36 1.19 4.24 45.4 12 : 7 39 1.16 4.39 46.0 12 : 10 42 1.16 3.89 47.3 12 : 13 45 1.25 4.31 47.4 12 : 16 48 1.20 3.65 51.5 12 : 19 51 1.21 3.63 50.3 12 : 22 54 1.16 2.88 50.7 12 : 25 57 1.15 2.71 47.9 12 : 28 60 1.13 1.85 48.3 12 : 31 63 1.11 1.38 47.0 12 : 34 66 1.09 1.30 44.8 12 : 37 69 1.07 1.24 44.0 12 : 40 72 1.24 11.38 45.9 12 : 43 75 1.22 10.66 49.2 12 : 46 78 1.17 10.38 49.7 12 : 49 81 1.13 9.86 48.2 12 : 52 84 1.09 9.47 47.2 12 : 55 87 1.11 9.40 46.4 12 : 58 90 1.08 9.16 44.4 13 : 1 93 1.03 8.44 43.7 13 : 4 96 1.01 8.47 43.1 13 : 7 99 1.02 8.55 42.2 13 : 10 102 1.15 10.86 4.71 13 : 13 105 1.21 11.36 46.5 13 : 16 108 1.15 10.86 48.7 13 : 19 111 1.17 10.39 51.7 13 : 22 114 1.12 10.12 48.6 13 : 25 117 1.08 10.08 48.6 13 : 28 120 1.06 9.51 47.0 13 : 31 123 1.02 9.04 44.6 13 : 34 126 1.02 8.74 42.9 13 : 37 129 1.04 8.59 43.6 13 : 40 132 1.05 11.66 44.2 13 : 43 135 1.04 11.59 44.8 13 : 46 138 1.00 9.86 46.9 13 : 49 141 0.97 10.12 44.4 13 : 52 144 0.95 9.60 42.0 13 : 55 147 1.12 11.45 40.7 13 : 58 150 1.08 10.64 47.5 Boxed values are identified as outliersGrate-Kiln 10/21/93

Hr : Mn Port 6b CO2 Time % (dry) Acid CO SO2 NOx ppm (dry) ppm (wet) ppm (wet) 02 % (dry) Page 2 of 2 02 Corrected 14 : 1 153 1.07 9.95 44.3 196.8 15.65 17.20 14 : 4 156 1.10 9.72 44.8 213.0 15.65 17.22 14 : 7 159 1.07 9.80 44.7 196.4 15.69 17.27 14 : 10 162 1.09 10.10 44.5 219.7 15.66 17.26 14 : 13 165 1.08 9.05 45.3 197.3 15.69 17.30 14 : 16 168 0.99 8.62 45.4 183.7 15.79 17.42 14 : 19 171 0.96 8.44 42.2 182.0 15.85 17.49 14 : 22 174 0.97 8.08 43.2 185.1 15.82 17.47 14 : 25 177 1.03 7.86 44.5 191.0 15.75 17.41 14 : 28 180 0.99 7.33 45.2 185.5 15.80 17.49 14 : 31 183 0.99 7.18 42.3 182.8 15.79 17.49 14 : 34 186 0.97 6.53 42.8 191.1 15.80 17.51 14 : 37 189 1.15 10.88 41.3 209.6 15.43 17.15 14 : 40 192 1.15 12.38 51.9 215.0 15.46 17.20 14 : 43 195 1.08 11.36 48.9 198.1 15.55 17.31 14 : 46 198 1.07 11.67 46.8 200.9 15.60 17.37 14 : 49 201 1.03 11.07 45.6 195.0 15.61 17.40 14 : 52 204 1.05 9.98 47.0 201.7 15.58 17.37 14 : 55 207 1.05 10.18 47.2 198.0 15.55 17.36 14 : 58 210 1.05 9.82 47.2 195.0 15.56 17.38 15 : 1 213 1.04 9.17 45.8 201.1 15.56 17.40 15 : 4 216 1.00 8.89 46.6 188.3 15.61 17.46 15 : 7 219 0.98 8.36 44.3 187.6 15.66 17.52 15 : 10 222 0.95 7.62 42.2 178.9 15.71 17.58 15 : 13 225 1.11 11.40 43.4 209.3 15.30 17.19 15 : 16 228 1.10 11.06 49.4 213.3 15.38 17.29 15 : 19 231 1.11 11.00 52.1 228.7 15.40 17.32 15 : 22 234 1.07 10.54 49.7 201.1 15.47 17.40 15 : 25 237 1.06 9.79 49.0 212.0 15.51 17.46 15 : 28 240 1.03 9.79 49.1 206.6 15.56 17.52 15 : 31 243 1.02 9.50 47.6 198.2 15.59 17.56 15 : 34 246 1.05 9.18 48.5 213.1 15.53 17.53 15 : 37 249 1.00 8.44 47.1 188.8 15.60 17.61 15 : 40 252 0.98 7.54 43.6 181.5 15.61 17.63 15 : 43 255 1.11 9.01 46.1 207.1 15.28 17.32 15 : 46 258 1.08 5.47 48.5 200.8 15.41 17.46 15 : 49 261 1.04 7.30 47.4 187.2 15.44 17.50 15 : 52 264 1.06 14.48 45.6 192.0 15.45 17.52 15 : 55 267 1.04 13.84 44.0 191.1 15.46 17.55 15 : 58 270 1.00 12.67 45.0 191.7 15.50 17.60 16 : 1 273 0.97 13.03 45.0 181.5 15.52 17.64 16 : 4 276 1.00 13.14 45.0 178.4 15.48 17.62 16 : 7 279 1.12 9.74 28.7 175.0 15.00 17.15 16 : 10 282 1.07 9.32 51.7 201.6 15.25 17.41 16 : 13 285 1.09 9.07 49.8 194.3 15.30 17.47 16 : 16 288 1.06 8.31 46.7 192.7 15.30 17.49 16 : 19 291 1.02 6.94 45.7 189.9 15.36 17.56 16 : 22 294 1.01 10.08 43.4 185.6 15.39 17.61 16 : 25 297 0.99 10.04 43.5 183.5 15.40 17.63 16 : 28 300 1.00 10.04 44.5 195.1 15.39 17.63 16 : 31 303 0.97 9.59 43.1 173.9 15.44 17.70 Boxed values are identified as outliersGrate-Kiln 10/22/93

Hr : Mn Port 6c CO2 Time % (dry) Acid CO SO2 NOx ppm (dry) ppm (wet) ppm (wet) Page 1 of 2 02 % (dry) 10 : 16 0 1.06 5.12 43.1 216.9 19.46 10 : 19 3 1.04 5.40 43.2 207.6 19.14 10 : 22 6 1.00 4.70 43.3 207.9 19.01 10 : 25 9 0.98 4.35 41.9 194.9 18.97 10 : 28 12 0.99 4.49 41.6 199.4 18.92 10 : 31 15 0.98 4.27 41.8 209.5 18.90 10 : 34 18 0.99 4.04 42.3 206.4 18.87 10 : 37 21 1.02 4.05 41.7 204.4 18.85 10 : 40 24 0.99 4.02 43.0 202.1 18.86 10 : 43 27 1.01 3.92 43.8 200.9 18.84 10 : 46 30 1.07 4.17 45.4 228.7 18.49 10 : 49 33 1.04 4.08 47.2 213.5 18.61 10 : 52 36 1.01 3.78 46.4 207.7 18.65 10: 55 39 0.98 3.79 44.8 200.0 18.74 10: 58 42 0.98 3.92 45.8 213.8 18.74 11 : 1 45 0.96 3.56 43.7 194.1 18.78 11 : 4 48 0.96 3.74 41.6 193.1 18.76 11 : 7 51 0.99 3.66 44.1 208.9 18.75 11 : 10 54 0.99 3.15 44.4 200.1 18.72 11 : 13 57 0.94 2.99 41.7 183.1 18.81 11 : 16 60 1.03 3.76 34.1 207.6 18.65 11 : 19 63 0.97 3.20 43.3 192.7 18.73 11 : 22 66 0.99 3.25 43.8 204.5 18.51 11 : 25 69 0.96 2.93 44.0 190.0 18.58 11 : 28 72 0.94 2.69 44.6 186.9 18.62 11 : 31 75 0.99 2.38 45.4 216.1 18.55 11 : 34 78 1.05 2.57 48.0 222.3 18.43 11 : 37 81 1.06 2.69 48.3 222.6 18.42 11 : 40 84 0.97 2.26 48.5 195.9 18.55 11 : 43 87 0.94 1.76 44.6 183.3 18.60 11 : 46 90 1.02 3.02 35.4 210.5 18.48 11 : 49 93 0.97 2.05 44.1 201.5 18.55 11 : 52 96 0.95 2.43 42.4 193.7 18.58 11 : 55 99 0.92 2.03 39.9 175.8 18.61 11 : 58 102 0.92 1.81 41.3 184.8 18.63 Boxed values are identified as outliersGrate-Kiln 10/22/93

Hr : Mn Port 6c Acid CO2 CO SO2 NOx Time % (dry) ppm (dry) ppm (wet) ppm (wet) Page 2 of 2 02 % (dry) 12 : 1 105 0.90 1.33 42.5 191.8 18.63 12 : 4 108 0.94 1.32 42.1 190.5 18.55 12 : 7 111 0.95 1.04 42.9 200.6 18.54 12 : 10 114 0.95 1.13 40.9 187.4 18.52 12 : 13 117 0.94 0.83 41.1 181.7 18.51 12 : 16 120 0.95 0.78 43.5 194.1 18.47 12 : 19 123 0.94 0.44 41.2 195.0 18.50 12 : 22 126 0.92 0.37 42.3 196.1 18.50 12 : 25 129 0.99 7.221 21.81 156.31 18.03 12 : 28 132 0.95 6.11 47.5 196.4 18.38 12 : 31 135 0.96 5.34 47.3 199.9 18.35 12 : 34 138 0.95 4.92 45.7 208.1 18.37 12 : 37 141 0.96 18.22 46.3 207.2 18.35 12 : 40 144 0.94 17.62 47.8 192.7 18.35 12 : 43 147 0.92 17.50 44.8 189.1 18.40 12 : 46 150 0.90 17.28 43.5 188.4 18.39 12 : 49 153 0.93 17.58 42.5 188.7 18.33 12 : 52 156 0.93 17.47 43.0 200.0 18.27 12 : 55 159 0.89 16.97 42.3 184.5 18.29 12 : 58 162 0.89 16.68 41.7 176.8 18.28 13 : 1 165 0.92 16.91 42.3 192.3 18.19 13 : 4 168 0.92 16.74 43.0 186.4 18.12 13 : 7 171 0.98 16.85 28.1 180.4 18.45 13 : 10 174 0.93 16.27 44.7 188.3 18.47 13 : 13 177 0.94 15.77 47.3 196.6 18.43 13 : 16 180 1.02 16.05 47.3 217.0 18.29 Boxed values are identified as outliers

# APPENDIX BStraight-Grate 04/20/94 H : M : S Wind Box 16 SO2 Time, min ppm (wet) ppm Acid Pellets CO NOx 02 (dry) ppm (wet) pct (dry) Page 1 of 1 CO2 pct (dry) 12 : 7 : 22 -0.0 7.92 0.07 49.55 20.40 0.304 12 : 8 : 22 1.0 9.00 0.42 48.36 20.40 0.314 12 : 9 : 22 2.0 12 : 10 : 22 3.0 7.38 0.59 40.45 20.46 0.277 12 : 11 : 22 4.0 12 : .12 : 22 5.0 5.66 0.49 45.73 20.34 0.295 12 : 13 : 22 6.0 8.96 1.02 51.09 20.32 0.332 12 : 14 : 22 7.0 8.51 0.76 47.35 20.42 0.310 12 : 15 : 22 8.0 9.43 0.85 49.95 20.36 0.323 12 : 16 : 22 9.0 8.72 0.74 45.88 20.38 0.319 12 : 17 : 22 10.0 8.23 0.33 44.65 20.42 0.288 12 : 18 : 22 11.0 8.84 0.12 46.65 20.37 0.307 12 : 19 : 22 12.0 9.69 0.47 49.26 20.34 0.324 12 : 20 : 22 13.0 9.30 0.52 44.49 20.39 0.306 12 : 21 : 22 14.0 9.05 0.78 44.53 20.38 0.306 12 : 22 : 22 15.0 9.30 1.26 48.23 20.39 0.318

12 : 29 : 22 22.0 8.54 1.18 57.59 20.38 0.306 12 : 30 : 22 23.0 8.92 0.49 51.69 20.39 0.297 12 : 31 : 22 24.0 8.83 0.88 44.13 20.48 0.268 12 : 32 : 22 25.0 7.74 0.38 36.90 20.50 0.235 12 : 33 : 22 26.0 7.79 0.87 37.61 20.50 0.245 12 : 34 : 22 27.0 6.77 1.09 37.53 20.51 0.259 12 : 35 : 22 28.0 7.50 0.54 37.66 20.49 0.248 12 : 36 : 22 29.0 7.64 0.39 37.39 20.51 0.252 12 : 37 : 22 30.0 7.40 0.57 35.05 20.54 0.239 12 : 38 : 22 31.0 7.57 35.42 20.54 0.222 12 : 39 : 22 32.0 7.07 0.34 32.71 20.54 0.219 12 : 40 : 22 33.0 7.92 0.75 35.73 20.51 0.244 12 : 41 : 22 34.0 6.42 1.09 35.75 20.56 0.236 12 : 42 : 22 35.0 6.22 0.68 30.68 20.58 0.207 12 : 43 : 22 36.0 6.23 0.42 33.44 20.62 0.194 12 : 44 : 22 37.0 6.22 0.60 37.28 20.53 0.226 12 : 45 : 22 38.0 8.75 0.94 45.21 20.46 0.277 12 : 46 : 22 39.0 7.77 0.44 40.81 20.53 0.242 12 : 47 : 22 40.0 7.66 0.66 39.13 20.53 0.242 12 : 48 : 22 41.0 6.54 0.99 34.10 20.59 0.206 12 : 49 : 22 42.0 7.38 1.41 39.99 20.57 0.235 12 : 50 : 22 43.0 8.22 1.03 48.43 20.47 0.258 12 : 51 : 22 44.0 8.63 1.38 48.23 20.47 0.273 12 : 52 : 22 45.0 7.33 0.89 41.02 20.55 0.235 12 : 53 : 22 46.0 7.80 1.24 45.87 20.55 0.249 12 : 54 : 22 47.0 9.10 1.46 55.92 20.38 0.301 12 : 55 : 22 48.0 9.25 1.23 50.26 20.40 0.293 12 : 56 : 22 49.0 9.96 1.45 49.75 20.45 0.284

### Straight-Grate 04/21/94 H : M : S Time, min Wind Box SO2 ppm (wet) 18 CO ppm (dry) Acid Pellets NOx ppm (wet) 02 pct (dry) Page 1 of 7 CO2 pct (dry) 9 : 51 : 11 0 6.6 1.01 678.81 16.86 2.48 9: 52 : 16 1.08 5.9 1.0 610.0 17.25 2.29 9 : 53 : 21 2.17 5.8 1.0 578.0 17.32 2.23 9 : 54 : 26 3.25 6.3 1.0 621.8 17.43 2.20 9: 55 : 31 4.33 9: 56 : 36 5.42 5.3 1.0 574.1 17.37 2.14 9: 57 : 41 6.50 6.2 1.0 722.2 17.10 2.37 9 : 58 : 46 7.58 5.7 1.0 648.3 17.36 2.24 9: 59 : 51 8.67 6.4 1.0 653.1 17.23 2.30 10: 0 : 56 9.75 6.4 1.0 701.3 17.20 2.29 10: 2: 1 10.83 6.0 1.0 759.6 17.02 2.40 10 : 3 : 6 11.92 6.2 1.0 719.5 17.09 2.36 10: 4 : 11 13.00 5.7 1.0 737.2 17.09 2.36 10: 5 : 16 14.08 5.9 1.0 745.1 17.15 2.33 10: 6 : 21 15.17 5.9 1.0 759.8 16.96 2.43 10: 7 : 26 16.25 6.4 1.0 694.7 17.14 2.38 10: 8 : 31 17.33 6.0 1.0 689.2 17.23 2.31 10: 9 : 36 18.42 6.4 1.0 685.9 17.09 2.35 10 : 10 : 41 19.50 6.2 1.0 705.8 16.94 2.45 10 : 11 : 46 20.58 5.8 1.0 752.9 16.97 2.47 10 : 12 : 51 21.67 6.2 1.0 742.2 17.10 2.38 10 : 13 : 56 22.75 5.5 1.0 759.1 17.04 2.45 10 : 15 : 1 23.83 6.1 1.0 725.2 17.09 2.39 10 : 16 : 6 24.92 5.9 1.0 741.4 17.17 2.37 10 : 17 : 11 26.00 6.3 1.0 743.9 17.16 2.38 10 : 18 : 16 27.08 6.1 1.0 680.1 17.44 2.24 10 : 19 : 21 28.17 4.9 1.0 624.5 17.39 2.23 10 : 20 : 26 29.25 6.3 1.0 785.5 16.84 2.47 10 : 21 : 31 30.33 6.5 1.0 785.4 16.83 2.49 10 : 22 : 36 31.42 6.1 1.0 797.6 16.99 2.45 10 : 23 : 41 32.50 6.5 1.0 749.5 17.08 2.40 10 : 24 : 46 33.58 6.0 1.0 652.3 17.41 2.25 10 : 25 : 51 34.67 6.2 1

. 

### .0 663.5 17.20 2.34 10 : 26 : 56 35.75 6.1 1.0 669.8 17.25 2.37 10 : 28 : 1 36.83 6.7 1.0 711.6 17.23 2.32 Boxed values are identified as outliersStraight-Grate Wind Box 18 Acid Pellets 04/21/94 SO2 CO NOx 02 H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) Page 2 of 7 CO2 pct (dry) 10 : 29 : 6 37.92 6.2 1.0 701.1 17.13 2.38 10 : 30 : 11 39.00 5.7 1.0 720.9 17.10 2.40 10 : 31 : 16 40.08 5.9 1.0 687.8 17.25 2.33 10 : 32 : 21 41.17 5.2 1.0 643.6 17.31 2.31 10 : 33 : 26 42.25 5.3 1.0 583.7 17.571 2.19 10 : 34 : 31 43.33 5.4 1.0 616.2 17.26 2.32 10 : 35 : 36 44.42 5.4 1.0 577.8 17.53 2.20 10 : 36 : 41 45.50 5.1 1.0 590.3 17.38 2.26 10 : 37 : 46 46.58 4.8 1.0 613.3 17.551 2.20 10 : 38 : 51 47.67 5.4 1.0 645.1 17.46 2.26 10 : 39 : 56 48.75 5.3 1.0 631.9 17.34 2.31 10 : 41 : 1 49.83 5.4 1.0 659.1 17.32 2.32 10 : 42 : 6 50.92 6.0 1.0 647.2 17.40 2.28 10 : 43 : 11 52.00 5.6 1.0 659.9 17.33 2.32 10 : 44 : 16 53.08 5.9 1.0 606.1 17.601 2.17 10 : 45 : 21 54.17 5.5 1.0 631.9 17.34 2.31 10 : 46 : 26 55.25 5.0 1.0 653.4 17.21 2.38 10 : 47 : 31 56.33 4.8 1.0 605.7 17.33 2.32 10 : 48 : 36 57.42 5.1 1.0 571.8 17.47 2.25 10 : 49 : 41 58.50 5.6 1.0 621.7 • 17.11 2.42 10 : 50 : 46 59.58 5.8 1.0 662.4 17.11 2.42 10 : 51 : 51 60.67 5.1 1.0 610.6 17.45 2.27 10 : 52 : 56 61.75 5.0 1.0 670.1 17.10 2.45 10 : 54 : 1 62.83 5.6 1.0 681.8 17.11 2.42 10 : 55 : 6 63.92 10 : 56 : 11 65.00 4.9 1.0 623.5 17.31 2.32 10 : 57 : 16 66.08 5.1 1.0 697.0 16.99 2.50 10 : 58 : 21 67.17 4.9 1.0 637.2 17.34 2.31 10 : 59 : 26 68.25 4.7 1.0 665.1 17.17 2.41 11 : 0 : 31 69.33 4.8 1.0 606.6 17.34 2.33 11 : 1 : 36 70.42 5.3 1.0 603.6 17.40 2.31 11 : 2 : 41 71.50 5.4 1.0 631.3 17.38 2.29 11 : 3 : 46 72.58 4.8 1.0 631.3 17.28 2.37 11 : 4 : 51 73.67 4.8 1.0 587.6 17.29 2.35 11 : 5 : 56 74.75 5.2 1.0 622.1 17.24 2.39 Boxed values are identified as outliersStraight-Grate Wind Box 18 Acid Pellets 04/21/94 SO2 CO NOx 02 H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) Page 3 of 7 CO2 pct (dry) 11 : 7 : 1 75.83 4.7 1.0 637.5 17.31 2.34 11 : 8 : 6 76.92 4.9 1.0 588.1 17.24 2.37 11 : 9 : 11 78.00 5.2 1.0 662.0 17.18 2.38 11 : 10 : 16 79.08 5.5 1.0 719.4 17.14 2.42 xxx 11 : 11 : 21 80.17 5.2 1.0 712.7 17.15 2.42 B 11 : 12 : 26 81.25 5.2 1.0 704.0 17.13 2.44 E 11 : 13 : 31 82.33 5.3 1.0 618.5 17.19 2.41 G 11 : 14 : 36 83.42 4.8 1.0 602.5 17.08 2.48 I 11 : 15 : 41 84.50 4.7 1.0 590.6 17.03 2.49 N 11 : 16 : 46 85.58 5.2 1.0 619.0 16.821 2.60 11 : 17 : 51 86.67 5.1 1.0 630.1 17.04 2.48 L 11 : 18 : 56 87.75 5.5 1.0 701.8 16.91 2.53 0 11 : 20 : 1 88.83 5.2 1.0 685.3 17.07 2.47 W 11 : 21 : 6 89.92 5.3 1.0 678.1 17.07 2.47 11 : 22 : 11 91.00 5.1 1.0 683.1 16.99 2.51 P 11 : 23 : 16 92.08 5.0 1.0 711.7 17.04 2.49 R 11 : 24 : 21 93.17 5.5 1.0 668.5 16.97 2.51 I 11 : 25 : 26 94.25 4.9 1.0 668.9 17.04 2.48 M 11 : 26 : 31 95.33 5.4 1.0 654.7 17.00 2.52 A 11 : 27 : 36 96.42 5.0 1.0 620.6 17.08 2.45 R 11 : 28 : 41 97.50 5.1 1.0 649.9 17.04 2.49 Y 11 : 29 : 46 98.58 5.7 1.0 680.5 17.04 2.49 11 : 30 : 51 99.67 5.8 1.0 661.6 16.99 2.50 A 11 : 31 : 56 100.75 5.3 1.0 660.9 17.07 2.48 I 11 : 33 : 1 101.83 5.8 1.0 637.5 17.23 2.40 R 11 : 34 : 6 102.92 11 : 35 : 11 104.00 T 11 : 36 : 16 105.08 5.4 1.0 608.8 17.27 2.36 E 11 : 37 : 21 106.17 5.6 1.0 654.3 16.94 2.55 S 11 : 38 : 26 107.25 4.5 1.0 665.6 16.99 2.52 T 11 : 39 : 31 108.33 4.7 1.0 591.8 17.24 2.39 11 : 40 : 36 109.42 5.1 1.0 580.0 17.35 2.36 11 : 41 : 41 110.50 5.7 1.0 562.7 17.38 2.33 11 : 42 : 46 111.58 4.8 1.0 558.7 17.39 2.34 11 : 43 : 51 112.67 5.0 1.1 553.9 17.32 2.37 11 : 44 : 56 113.75 4.4 1.0 579.4 17.27 2.40 Boxed values are identified as outliersAcid Pellets CO NOx (dry) ppm (wet)

1.0 1.0 543.5 1.0 556.1 1.0 558.8 1.0 612.9 1.0 587.4 4.0 541.4 1.0 563.1 1.0 606.3 1.0 586.8 1.0 550.3 1.0 548.7 1.0 562.5 1.0 547.5 1.0 575.2 1.5 568.3 1.0 598.3 1.0 649.0 1.0 640.5 1.0 624.8 1.0 537.9 1.0 568.2 1.0 543.7 1.0 576.7 1.0 572.0 1.0 551.6 1.0 547.3 17.35 17.22 17.30 16.97 17.25 17.25 17.17 17.13 17.19 17.21 17.15 17.07 17.31 17.17 17.13 17.15 16.91 17.18 16.96 17.33 16.98 17.22 17.20 17.02 17.25 17.13 526.21 17.58

E N D

L O

w

P R

M A R Y Page 4 of 7 02 CO2 pct (dry) pct (dry) 2.24 2.35 2.42 2.38 2.54 2.40 2.40 2.44 2.47 2.42 2.42 2.45 2.49 2.38 2.45 2.49 2.45 2.58 2.46 2.57 2.38 2.55 2.43 2.42 2.52 2.42 2.48 A

17.04 2.50 R 16.591 2.72 17.06 16.96 16.85 2.62 16.75 2.66 16.79 2.65 1.6 1.4 1.6 1.2 1.8 1.1 1.7 544.0 683.8 605.5 611.4 642.3 621.2 644.1 2.52 T 2.56 E S T

xxx Straight-Grate 04/21/94 H: M: ST Wind Box 18 SO2 ime, min ppm (wet) ppm 11 : 46 : 1 114.83 5.4 11 : 47 : 6 115.92 5.1 11 : 48 : 11 117.00 5.4 11 : 49 : 16 118.08 4.6 11 : 50 : 21 119.17 5.0 11 : 51 : 26 120.25 5.0 11 : 52 : 31 121.33 4.8 11 : 53 : 36 122.42 5.1 11 : 54 : 41 123.50 5.6 11 : 55 : 46 124.58 5.3 11 : 56 : 51 125.67 4.7 11 : 57 : 56 126.75 4.5 11 : 59 : 1 127.83 5.2 12: 0: 6 128.92 5.1 12 : 1 : 11 130.00 4.5 12 : 2 : 16 131.08 4.7 12: 3 : 21 132.17 4.7 12 : 4: 26 133.25 4.8 12: 5 : 31 134.33 4.5 12: 6 : 36 135.42 4.9 12: 7 : 41 136.50 4.4 12 : 8 : 46 137.58 4.6 12 : 9: 51 138.67 5.3 12 : 10 : 56 139.75 4.9 12 : 12 : 1 140.83 4.5 12 : 13 : 6 141.92 5.1 12 : 14 : 11 143.00 4.2 12 : 15 : 16 144.08 12 : 16 : 21 145.17 12 : 17 : 26 146.25 4.6 12 : 18 : 31 147.33 4.7 12 : 19 : 36 148.42 4.3 12 : 20 : 41 149.50 4.4 12 : 21 : 46 150.58 5.4 12 : 22 : 51 151.67 4.8 12 : 23 : 56 152.75 4.7 Boxed values are identified as outliers

### Straight-Grate Wind Box 18 Acid Pellets 04/21/94 SO2 CO NOx 02 H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) Page 5 of 7 CO2 pct (dry) 12 : 25 : 1 153.83 4.9 1.0 651.5 17.41 2.34 12 : 26 : 6 154.92 5.6 1.0 668.1 17.12 2.45 12 : 27 : 11 156.00 4.5 1.0 696.4 17.11 2.48 12 : 28 : 16 157.08 4.9 1.0 695.9 17.20 2.42 12 : 29 : 21 158.17 4.9 1.0 691.1 17.15 2.46 12 : 30 : 26 159.25 5.3 1.0 712.6 17.12 2.48 12 : 31 : 31 160.33 5.6 1.0 734.5 17.20 2.43 12 : 32 : 36 161.42 5.3 1.0 729.1 17.28 2.40 12 : 33 : 41 162.50 4.3 1.0 691.7 17.19 2.44 12 : 34 : 46 163.58 5.0 1.0 654.2 17.31 2.38 12 : 35 : 51 164.67 4.6 1.0 594.6 17.52 2.28 12 : 36 : 56 165.75 4.9 1.0 650.9 17.37 2.36 12 : 38 : 1 166.83 4.9 1.0 699.5 17.09 2.49 12 : 39 : 6 167.92 4.8 1.0 719.0 17.21 2.43 12 : 40 : 11 169.00 5.1 1.0 730.1 17.10 2.48 12 : 41 : 16 170.08 4.9 1.0 727.5 17.11 2.48 12 : 42 : 21 171.17 4.7 1.0 707.9 17.18 2.43 12 : 43 : 26 172.25 4.8 1.0 617.5 17.33 2.36 12 : 44 : 31 173.33 4.8 1.0 656.5 17.18 2.43 12 : 45 : 36 174.42 4.6 1.0 728.0 17.18 2.45 12 : 46 : 41 175.50 5.0 1.0 662.6 17.32 2.37 12 : 47 : 46 176.58 5.1 1.0 686.3 17.28 2.38 12 : 48 : 51 177.67 5.0 1.1 638.6 17.41 2.32 12 : 49 : 56 178.75 4.7 1.0 617.8 17.39 2.33 12 : 51 : 1 179.83 4.2 1.0 576.1 17.60 2.23 12 : 52 : 6 180.92 4.7 1.0 625.8 17.47 2.30 12 : 53 : 11 182.00 5.1 1.0 622.7 17.40 2.33 12 : 54 : 16 183.08 4.7 1.0 596.7 17.41 2.34 12 : 55 : 21 184.17 4.9 1.0 587.7 17.41 2.34 12 : 56 : 26 185.25 5.2 1.0 612.6 17.40 2.36 12 : 57 : 31 186.33 4.4 1.0 539.1 17.48 2.29 12 : 58 : 36 187.42 4.3 1.0 613.9 17.21 2.43 12 : 59 : 41 188.50 4.9 1.0 690.1 17.18 2.44 Boxed values are identified as outliers

### Straight-Grate Wind Box 18 Acid Pellets 04/21/94 SO2 CO NOx H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) 02 pct (dry) Page 6 of 7 CO2 pct (dry) 13 : 0 : 46 189.58 4.7 1.0 603.2 17.34 2.37 13 : 1 : 51 190.67 5.1 1.0 626.7 17.41 2.32 13 : 2 : 56 191.75 4.8 1.1 623.1 17.23 2.43 13 : 4 : 1 192.83 13 : 5 : 6 193.92 4.6 1.5 652.4 17.34 2.39 13 : 6 : 11 195.00 4.7 1.2 676.7 17.32 2.40 13 : 7 : 16 196.08 4.5 1.7 621.1 17.31 2.38 13 : 8 : 21 197.17 4.7 1.0 607.9 17.45 2.31 13 : 9: 26 198.25 4.4 1.0 644.1 17.32 2.37 13 : 10 : 31 199.33 5.1 1.3 711.8 17.03 2.53 13 : 11 : 36 200.42 5.3 1.0 714.3 17.14 2.46 13 : 12 : 41 201.50 4.6 1.2 745.3 17.05 2.52 13 : 13 : 46 202.58 4.7 1.1 760.9 17.12 2.47 13 : 14 : 51 203.67 5.0 1.0 700.3 17.27 2.40 13 : 15 : 56 204.75 4.8 1.0 673.3 17.27 2.40 13 : 17 : 1 205.83 4.9 1.1 663.6 17.22 2.41 13 : 18 : 6 206.92 4.1 1.0 661.5 17.38 2.35 13 : 19 : 11 208.00 4.4 1.4 613.5 17.52 2.28 13 : 20 : 16 209.08 5.0 1.0 639.9 17.34 2.37 13 : 21 : 21 210.17 4.0 1.0 636.2 17.28 2.40 13 : 22 : 26 211.25 5.0 1.1 705.5 17.14 2.45 13 : 23 : 31. 212.33 5.0 1.1 697.0 17.11 2.48 13 : 24 : 36 213.42 4.8 1.1 637.0 17.42 2.33 13 : 25 : 41 214.50 5.1 1.0 654.7 17.43 2.30 13 : 26 : 46 215.58 4.7 1.0 685.5 17.28 2.37 13 : 27 : 51 216.67 4.3 1.4 668.1 17.19 2.44 13 : 28 : 56 217.75 4.7 1.0 649.4 17.33 2.37 13 : 30 : 1 218.83 4.4 1.4 685.8 17.29 2.39 13 : 31 : 6 219.92 4.8 1.2 785.5 16.95 2.55 13 : 32 : 11 221.00 4.9 1.0 722.7 17.03 2.51 13 : 33 : 16 222.08 4.8 1.0 687.1 17.23 2.40 Boxed values are identified as outliersStraight-Grate Wind Box 18 Acid Pellets 04/21/94 SO2 CO NOx 02 H : M : S Time, min ppm (wet) ppm (dry) ppm (wet) pct (dry) Page 7 of 7 CO2 pct (dry) 13 : 34 : 21 223.17 4.7 1.1 650.2 17.32 2.36 13 : 35 : 26 224.25 4.6 1.2 699.8 17.25 2.41 13 : 36 : 31 225.33 4.7 1.0 644.3 17.42 2.31 13 : 37 : 36 226.42 4.8 1.1 673.8 17.35 2.35 13 : 38 : 41 227.50 4.6 1.3 713.4 17.27 2.40 13 : 39 : 46 228.58 4.6 1.2 717.6 17.13 2.46 13 : 40 : 51 229.67 4.4 1.3 667.0 17.25 2.41 13 : 41 : 56 230.75 4.7 1.4 692.5 17.23 2.43 13 : 43 : 1 231.83 4.3 1.5 674.1 17.28 2.39 13 : 44 : 6 232.92 4.8 1.3 646.8 17.31 2.37 13 : 45 : 11 234.00 4.2 1.4 643.2 17.21 2.42 13 : 46 : 16 235.08 13 : 47 : 21 236.17 13 : 48 : 26 237.25 4.8 1.0 630.5 17.18 2.46 13 : 49 : 31 238.33 4.5 1.0 663.7 17.39 2.33 13 : 50 : 36 239.42 4.9 1.0 653.4 17.38 2.33

# APPENDIX CGrate-Kiln Port 6a Fluxed 09/28/93 NO NOx SO2 CO 02 CO2

Hr : Mn Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) % (dry) % (dry) 10 : 25 0 140.0 145.0 5.0 11.0 18.3 2.10 10 : 30 5 140.0 140.0 3.0 9.0 18.4 2.05 10 : 35 10 130.0 137.0 4.0 6.0 18.6 1.80 10 : 40 15 115.0 115.0 5.0 4.0 18.8 1.65 UpSet 10 : 50 25 67.0 67.0 2.0 0.0 19.4 1.00 ShutDown 13 : 5 160 85.0 85.0 3.0 4.5 19.1 1.50 13 : 12 167 85.0 85.0 2.0 4.0 19.2 1.45 13 : 19 174 80.0 80.0 2.0 4.0 19.2 1.45 13 : 29 184 77.0 77.0 1.0 2.0 19.4 1.20 13: 40 195 75.0 75.0 2.0 3.0 19.1 1.40 13 : 50 205 105.01 105.0 2.0 1.0 19.2 1.60 14 : 0 215 85.0 85.0 0.0 0.0 19.4 1.10 14 : 10 225 70.0 70.0 0.0 0.0 19.6 0.95 14 : 20 235 65.0 65.0 0.0 0.0 19.8 0.90 14 : 30 245 60.0 60.0 0.0 0.0 19.8 0.75 14: 40 255 55.0 55.0 0.0 0.0 19.9 0.75 14 : 50 265 50.0 50.0 0.0 0.0 20.0 0.70 15 : 0 275 50.0 50.0 0.0 0.0 20.0 0.70 15 : 10 285 45.0 45.0 0.0 0.0 20.0 0.60 15: 20 295 50.0 50.0 0.0 0.0 20.1 0.60 15 : 30 305 45.0 45.0 0.0 0.0 20.1 0.65 15 : 40 315 50.0 50.0 0.0 0.0 20.1 0.65 15 : 53 328 45.0 45.0 0.0 0.0 20.1 0.60 16 : 10 345 40.0 40.0 0.0 0.0 20.2 0.55 16 : 20 355 40.0 40.0 0.0 0.0 19.9 0:70 16 : 40 375 34.0 34.0 0.0 0.0 20.1 0.10 17 : 0 395 40.0 40.0 0.0 0.0 20.1 0.60 17 : 20 415 41.0 41.0 0.0 0.0 20.2 0.55 17 : 35 430 32.5 32.5 0.0 0.0 20.2 0.50 17 : 45 440 37.0 37.0 0.0 0.0 20.2 0.55 18 : 0 455 35.5 35.5 0.0 0.0 20.2 0.50 18 : 15 470 37.5 38.0 0.0 0.0 20.2 0.46 18 : 30 485 35.0 35.0 0.0 0.0 20.3 0.45 Boxed values are identified as outliers

### Grate-Kiln 09/28/93 Hr : Mn Port 6 Fluxed Time NOx SO2 CO

min ppm (wet) ppm (wet) ppm (dry) 02 pct (dry) CO2 pct (dry)

13 : 5 160 85.00 3.00 4.50 19.10 1:50 13 : 12 167 88.44 2.08 4.16 19.16 1.51 13 : 19 174 86.48 2.16 4.32 19.13 1.57 13 : 29 184 87.70 1.14 2.28 19.28 1.37 13 : 40 195 90.20 2.41 3.61 18.94 1.68 13 : 50 205 2.52 1.26 19.01 14 : 0 215 112.07 0 0 19.17 1.45 14 : 10 225 96.34 0 0 19.34 1.31 14 : 20 235 93.22 0 0 19.51 1.29 14 : 30 245 89.53 0 0 19.48 1.12 14 : 40 255 85.25 0 0 19.56 1.16 14 : 50 265 80.40 0 0 19.63 1.13 15 : 0 275 83.29 0 0 19.61 1.17 15 : 10 285 77.57 0 0 19.59 1.03 15 : 20 295 89.08 0 0 19.67 1.07 15 : 30 305 82.78 0 0 19.65 1.20 15 : 40 315 94.87 0 0 19.64 1.23 15 : 53 328 88.77 0 0 19.62 1.18 16 : 10 345 82.84 0 0 19.69 1.14 16 : 20 355 85.16 0 0 19.39 1.49 16 : 40 375 76.32 0 0 19.56 17 : 0 395 94.42 0 0 19.54 1.42 17 : 20 415 101.53 0 0 19.62 1.36 17 : 35 430 83.30 0 0 19.61 1.28 17 : 45 440 96.98 0 0 19.60 1.44 18 : 0 455 96.13 0 0 19.59 1.35 18 : 15 470 106.20 0 0 19.58 1.27 18 : 30 485 100.86 0 0 19.66 1.30
Data corrected for sample line air leakGrate-Kiln 09/30/93

Hr : Mn Port 6b Fluxed NO NOx SO2 CO Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) 02 % (dry) CO2 % (dry) 11 : 42 0 235 235 21 19.0 17.0 3.10 11 : 45 3 242 242 22 19.0 17.11 3.05 11 : 55 13 3651 365 15 20.0 16.7 3.25 12 : 0 18 270 270 15 18.5 16.8 3.25 12 : 5 23 260 260 12 19.5 16.8 3.25 12 : 8 26 260 260 12 27.0 16.7 3.35

12 : 29 47 260 260 12 23.5 16.8 3.25 12 : 31 49 270 270 10 25.0 16.8 3.25

12 : 46 64 240 240 20 19.0 16.8 3.20 12 : 48 66 240 240 21 25.0 16.8 3.15 12 : 51 69 240 240 30 17.0 16.8 3.20

12: 59 77 240 240 38 22.0 16.8 3.22 13 : 0 78 240 240 38 18.0 16.8 3.22 13 : 2 80 240 240 35 24.0 16.7 3.25 13 : 5 83 240 240 35 21.0 16.7 3.25 13 : 7 85 250 250 35 22.0 16.7 3.25 13: 10 88 240 240 35 19.0 16.7 3.25 13 : 13 91 240 240 35 21.0 16.7 3.25 13: 15 93 245 245 35 20.0 16.7 3.25 13 : 18 96 240 240 35 21.0 16.7 3.25 13: 22 100 240 240 15 19.0 16.7 3.25 13 : 31 109 240 240 35 28.0 16.7 3.25 13 : 38 116 245 245 151 30.0 16.5 3.35 13 : 40 118 240 240 12 27.0 16.5 , 3.32 13 : 50 128 240 240 40 25.0 16.7 3.25 13 : 52 130 240 240 35 25.0 16.7 3.20 13 : 55 133 245 245 32 24.0 16.7 3.25 13: 57 135 245 245 20 22.0 16.7 3.25 14: 2 140 230 230 15 22.0 16.7 3.23 14 : 7 145 240 240 40 26.0 16.6 3.23 14 : 13 151 250 250 32 28.0 16.6 3.30 14 : 17 155 245 245 25 25.0 16.6 3.28 14 : 25 163 280 280 45 27.0 16.7 3.23 14 : 30 168 280 280 35 27.0 16.9 3.15 14 : 35 173 255 255 28 27.0 16.9 3.10 14 : 40 178 255 255 18 25.0 16.9 3.08 14 : 50 188 265 265 40 23.0 17.0 3.07 15 : 0 198 260 260 25 25.0 16.9 3.10 15 : 15 213 260 260 40 19.0 17.0 3.05 Boxed values are identified as outliersGrate-Kiln 10/04/93 Hr : Mn Time Port 5B Fluxed NO NOx SO2 CO ppm (wet) ppm (wet) ppm (wet) ppm (dry) 02 % (dry) CO2 % (dry) 10 : 46 0 4931 6901 4601 501 20.01 4.63 12 : 45 119 380 390 110 20 15.4 4.30 12 : 50 124 420 420 118 20 15.0 4.50 13 : 0 134 420 420 100 25 15.2 4.30 13 : 10 144 415 415 122 35 15.2 4.30 13 : 15 149 385 385 125 31 15.2 4.25 13 : 20 154 400 400 118 36 14.8 4.60 13 : 30 164 400 400 130 30 15.3 4.10 13 : 40 174 410 410 130 32 15.2 4.30 13 : 50 184 390 390 105 36 15.0 4.45 13 : 55 189 400 400 100 38 15.0 4.42 14 : 0 194 410 410 108 37 15.0 4.40 14 : 15 209 400 400 112 33 15.0 4.40 14 : 25 219 385 385 140 28 15.2 4.15 14 : 38 232 360 360 105 37 15.4 4.25 14 : 48 242 400 400 120 30 15.5 4.05 14 : 55 249 380 380 95 38 15.4 4.15 15 : 0 254 380 380 100 35 15.2 4.25 15 : 2 256 420 420 100 38 14.9 4.45 15 : 5 259 395 395 100 25 15.3 4.15 15 : 10 264 380 380 85 20 15.6 4.08 15 : 15 269 365 365 90 19 15.5 4.08 15 : 20 274 360 360 90 18 15.8 3.85 15 : 25 279 370 370 85 18 15.8 4.00 15 : 30 284 370 370 95 18 16.0 3.85 Boxed values are identified as outliersGrate-Kiln 10/05/93 Hr : Mn Port 4 Fluxed NO NOx Time ppm (wet) ppm (wet) ppm SO2 CO (wet) ppm (dry) 02 % (dry) CO2 % (dry) 11 : 40 0 785 785 270 104.0 12.0 4.55 11 : 45 5 780 780 290 5.0 'F1.8 4.75 11 : 50 10 740 740 235 0.0 11.6 4.50 11 : 55 15 770 770 235 2.0 11.5 4.40

12 : 5 25 780 780 300 4.0 12.2 4.30 12 : 24 44 720 720 255 2.0 12.0 4.40 12 : 28 48 760 760 260 2.0 11.8 4.65

12 : 42 62 720 720 240 2.0 12.0 4.50 12 : 45 65 680 680 261 3.0 12.3 4.35 12 : 50 70 760 760 270 8.01 10.5 5.00 12 : 55 75 740 740 260 8.0 11.2 5.60 13 : 0 80 780 780 250 15.0 11.8 4.60 13 : 5 85 760 760 259 20.0 12.3 5.10 13 : 15 95 760 760 230 25.0 11.8 5.50 13 : 28 108 790 790 265 15.0 11.0 5.30 13 : 33 113 760 760 230 11.0 11.6 5.20 13 : 40 120 740 740 255 15.0 11.4 4.80 13 : 49 129 790 790 235 9.0 11.8 4.60 14 : 16 156 820 820 240 11.0 11.4 4.50 14 : 24 164 810 810 225 25.0 11.0 5.00 14 : 32 172 800 800 235 20.0 10.8 5.00 14 : 47 187 720 720 250 5.0 11.5 4.40 14 : 50 190 660 660 220 3.0 12.3 4.30 15 : 0 200 6501 6501 200 2.0 12.4 4.20 15 : 6 206 680 680 210 1.0 12.5 4.10 15 : 12 212 700 700 220 1.0 12.2 4.20 Boxed values are identified as outliersGrate-Kiln 10/06/93 Hr : Mn Port 3 Fluxed NO NOx SO2 CO Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) 02 % (dry) CO2 % (dry) 12 : 35 0 500 500 170 16.5 

### ' 2.3 12 : 40 5 540 540 200 16.0 2.3 12 : 45 10 530 530 200 15.7 2.3 12 : 50 15 490 490 170 15.7 2.3 12 : 55 20 520 520 220 15.7 2.4 13 : 0 25 520 520 220 15.4 2.4 13 : 5 30 560 560 220 15.4 2.4 13 : 10 35 520 520 230 15.3 2.5 13 : 15 40 580 580 240 15.5 2.3 13 : 20 45 540 540 240 15.4 2.4 13 : 25 50 520 520 180 15.5 2.2 13 : 30 55 540 540 190 15.5 2.2 13: 35 60 590 590 230 15.3 2.6 13 : 45 70 520 520 190 15.6 2.4 13 : 55 80 540 540 190 15.6 2.5 14 : 0 85 510 510 190 15.6 2.5 14 : 5 90 530 530 180 15.8 2.2 14 : 7 92 500 500 180 0.10 15.9 2.2 14 : 15 100 540 540 160 0.15 15.3 2.5 14 : 20 105 500 500 150 0.20 15.4 2.4 14 : 25 110 520 520 200 15.4 2.4 14 : 30 115 550 550 200 15.1 2.4 14 : 35 120 520 520 180 15.2 2.4 14 : 40 125 520 540 180 0.10 15.5 2.2 14 : 45 130 510 530 200 0.10 15.1 2.4 14 : 50 135 530 560 180 0.20 15.4 2.4 14 : 55 140 460 550 190 0.20 15.4 2.5 15 : 0 145 440 440 160 0.30 15.2 3.0 15 : 8 153 440 490 150 0.30 15.0 2.7 15 : 12 157 420 420 160 0.40 14.4 2.5 15 : 15 160 440 440 160 0.30 15.4 2.7 15 : 20 165 450 440 155 0.30 15.4 2.9 15 : 25 170 420 460 155 0.30 14.6 2.4 15 : 30 175 430 420 155 0.30 15.1 2.5 15 : 35 180 440 430 155 0.30 15.4 2.4 15 : 40 185 420 430 158 0.30 14.9 2.7 15 : 45 190 440 440 165 0.30 14.6 2.8 15 : 50 195 460 480 150 0.30 15.3 2.4 15 : 55 200 460 440 160 0.30 15.1 2.6 16 : 0 205 460 450 160 0.30 15.2 2.6 16 : 5 210 440 450 160 0.20 14.9 2.5 16 : 10 215 450 460 155 0.10 14.9 2.6 16 : 15 220 440 420 155 0.10 15.2 2.5 16 : 20 225 410 430 150 0.10 15.9 2.2 16 : 25 230 380 380 145 0.10 10.2 2.2 16 : 30 235 2601 280 145 0.10 15.6 2.3 Boxed values are identified as outliersGrate-Kiln Port 1 Fluxed 10/07/93 NO NOx SO2 CO 02 CO2 Hr : Mn Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) % (dry) % (dry) 14: 6 0 350 0 19.40 0 14 : 15 9 3.50 3.50 330 0 19.30 0 14 : 19 13 3.50 3.50 320 0 19.20 0 14 : 20 14 3.50 4.00 230 0 19.10 0 14 : 35 29 4.00 4.00 560 0 18.90 0 14 : 40 34 4.00 4.00 410 0 18.90 0 14 : 45 39 4.25 4.25 250 0 19.20 0 14 : 48 42 4.00 4.00 450 0 18.90 0 14 : 53 47 4.25 4.50 410 0 18.80 0 14 : 55 49 4.00 4.25 340 0 18.70 0 14 : 58 52 4.25 4.50 380 0 18.70 0 15 : 3 57 4.25 4.50 340 0 18.80 0 15 : 5 59 4.25 4.50 300 0 18.90 0 15 : 8 62 4.25 4.50 260 0 19.00 0 15 : 15 69 4.25 4.50 380 0 18.80 0 15 : 25 79 4.50 4.50 370 0 18.70 0 15 : 35 89 4.25 4.50 300 0 19.00 0 15 : 45 99 4.25 4.50 200 0 19.10 0 16 : 0 114 4.25 4.25 310 0 19.00 0 16 : 5 119 4.20 4.20 310 0 19.25 0 16 : 14 128 4.00 4.25 130 0 19.30 0 16 : 20 134 4.00 4.25 240 0 19.00 0 16 : 25 139 4.00 4.25 240 0 19.00 0 16 : 30 144 4.00 4.25 280 0 19.00 0 16 : 31 145 4.00 4.25 410 0 18.70 0 16 : 33 147 4.00 4.25 210 0 19.20 0 16 : 35 149 4.00 4.25 190 0 19.20 0 16 : 41 155 4.00 4.25 180 0 19.20 0 16 : 43 157 4.00 4.25 200 0 19.10 0 16 : 45 159 4.00 4.25 300 0 18.80 0 16 : 50 164 4.00 4.25 185 0 19.20 0 16 : 54 168 3.75 4.00 145 0 19.20 0 16 : 56 170 3.75 4.00 115 0 19.20 0 16 : 57 171 4.00 4.00 250 0 18.70 0 16 : 59 173 4.00 4.25 150 0 19.20 0 17 : 0 174 3.75 4.00 130 0 19.20 0 Special test of air outside of Port #1 17 : 2 176 3.75 4.00 170 0 19.20 0 17 : 5 179 4.00 4.00 165 0 19.20 0 17 : 7 181 4.00 4.00 150 0 19.40 0 17 : 8 182 3.75 4.00 140 0 19.20 0 17 : 9 183 3.75 4.00 50 0 20.10 0 17 : 12 186 3.75 4.00 0 0 20.20 0 Boxed values are identified as outliersGrate-Kiln Port 2 Fluxed 10/08/93 NO NOx SO2 CO 02 CO2 Hr : Mn Time ppm (wet) ppm (wet) ppm (wet) ppm (dry) % (dry) % (dry)

9: 45 0 4.50 4.50 5 1.50 20.6 0.04 10 : 0 15 3.50 3.00 0 0.10 20.6 0.04 10 : 15 30 3.50 3.75 0 0.00 20.5 0.04 10: 20 35 3.50 3.50 0 0.00 20.6 0.04

# APPENDIX D

### Straight-Grate 29/Nov/93

H : M : S Time,min WB 6 SO2 ppm(wet) Fluxed Pellets CO NOx ppm(d ry) ppm(wet) 02 pct(dry) CO2 pct(dry) 13 : 51 : 44 -0.00 2.53 <3 41.71 20.25 13 : 54 : 44 3.00 4.11 <3 46.6 20.31 0.50 13 : 57 : 44 6.00 3.71 <3 45.5 20.36 14: 0 : 44 9.00 3.39 <3 44.8 20.29 14 : 3 : 44 12.00 5.10 <3 52.9 20.24 14 : 6 :44 15.00 6.61 <3 47.1 20.32 0.60 14: 9 : 44 18.00 4.87 <3 45.5 20.39 14 : 12 : 44 21.00 4.06 <3 48.4 20.38 14 : 15 : 44 24.00 5.92 <3 51.2 20.37 0.50 14 : 18 : 44 27.00 6.59 <3 51.7 20.29 14 : 21 : 44 30.00 5.62 <3 47.7 20.37 0.58 14 : 24 : 44 33.00 5.68 <3 44.4 20.43 14 : 27 : 44 36.00 5.84 <3 47.3 20.45 14 : 30 : 44 39.00 7.19 <3 46.7 20.49 14 : 33 : 44 42.00 6.40 <3 47.6 20.46 0.50 14 : 36 : 44 45.00 7.49 <3 51.4 20.43 14 : 39 : 44 48.00 6.96 <3 48.7 20.47 14 : 42 : 44 51.00 5.43 <3 44.9 20.45 14 : 45 : 44 54.00 5.27 <3 45.6 20.51 0.40 14 : 48 : 44 57.00 4.99 <3 49.4 20.49 DATA LOGGER LOCK

14 : 53 : 51 62.12 5.27 <3 44.8 20.45 14 : 56 : 51 65.12 5.81 <3 45.9 20.45 0.50 14 : 59 : 51 68.12 4.46 <3 44.8 20.48 15: 2 : 51 71.12 4.69 <3 45.8 20.47 15 : 5 : 51 74.12 4.35 <3 47.1 20.43 15 : 8 : 51 77.12 5.57 <3 53.5 20.33 15 : 11 : 51 80.12 5.45 <3 52.5 20.37 0.58 15 : 14 : 51 83.12 5.40 <3 48.6 20.40 15 : 17 : 51 86.12 4.89 <3 51.8 20.41 15 : 20 : 51 89.12 5.86 <3 49.8 20.45 15 : 23 : 51 92.12 4.16 <3 51.4 20.40 15 : 26 : 51 95.12 5.63 <3 54.0 20.37 15 : 29 : 51 98.12 6.57 <3 54.1 20.38 15 : 32 : 51 101.12 5.42 <3 49.4 20.38 0.59 Boxed values are identified as outliers

### Straight-Grate WB 10 Fluxed Pellets 30/Nov/93 SO2 CO

H : M : S Time,min ppm(wet) ppm(dry) ppm(wet) NOx 02 pct(dry) CO2 pct(dry) 15 : 56 : 28 -0.00 35.75 ND 198.4 17.831 2.25 15 : 59 : 28 3.00 36.95 ND 180.1 17.91 16 : 2 : 28 6.00 39.71 ND 182.2 17.97 2.25 16 : 5 : 28 9.00 33.87 ND 188.2 17.98 16 : 8 : 28 12.00 35.05 ND 174.7 18.14 16 : 11 : 28 15.00 33.74 ND 180.6 18.17 2.10 16 : 14 : 28 18.00 33.15 ND 169.2 18.19 2.10 16 : 17 : 28 21.00 31.14 ND 160.8 18.23 16 : 20 : 28 24.00 43.08 ND 190.9 18.03 16 : 23 : 28 27.00 38.29 ND 182.6 18.03 16 : 26 : 28 30.00 33.66 ND 173.9 18.09 2.20 16 :29 : 28 33.00 32.75 ND 178.8 18.15 16 : 32 : 28 36.00 34.29 ND 170.3 18.24 2.05 16 : 35 : 28 39.00 31.73 ND 154.0 18.33 16 : 38 : 28 42.00 33.38 ND 154.4 18.36 16 : 41 :28 45.00 33.34 ND 157.2 18.42 1.801 16 : 44 : 28 48.00 29.77 ND1 149.01 18.45 16 : 47 : 28 51.00 38.94 ND 187.2 18.07 16 : 50 : 28 54.00 38.40 ND 187.8 18.08 2.30 16 : 53 : 28 57.00 38.76 ND 175.7 18.19 16 : 56 : 28 60.00 33.83 ND 175.7 18.15 2.20 Boxed values are identified as outtiers

### Straight-Grate 1/Dec/93

H : M : S Time,min WB 12 SO2 ppm(wet) Fluxed Pellets CO NOx ppm(dry) ppm(wet) 02 pct(dry) CO2 pct(dry) 13 : 54 : 23 0.00 8.13 ND 532.7 18.06 1.94 13 : 57 : 23 3.00 7.20 ND 497.1 18.20 1.94 14 : 0 : 23 6.00 7.98 ND 557.6 18.13 14 : 3 : 23 9.00 6.53 ND 480.6 18.20 14 : 6 : 23 12.00 9.39 ND 588.0 17.67 2.20 14 : 9 : 23 15.00 9.77 ND 732.4 17.09 2.45 14 : 12 : 23 18.00 10.50 ND 733.6 17.28 2.70 14 : 15 : 23 21.00 11.56 ND 728.0 17.43 2.60 14 : 18 : 23 24.00 8.07 ND 811.8 17.31 14 : 21 : 23 27.00 9.13 ND 839.5 16.95 14 : 24 : 23 30.00 7.60 ND 900.0 16.67 14 : 27 : 23 33.00 8.11 ND 802.1 16.79 3.10 14 : 30 : 23 36.00 9.08 ND 780.9 16.92 14 : 33 : 23 39.00 7.67 ND 823.5 16.86 2.95 14 : 36 : 23 42.00 6.00 ND 730.0 17.21 14 : 39 : 23 45.00 6.04 ND 716.0 17.12 2.86 14 : 42 : 23 48.00 6.01 ND 708.7 17.14 14 : 45 : 23 51.00 7.45 ND 771.1 16.83 2.95 14 : 48 : 23 54.00 7.94 ND 726:9 16.94 3.00 14 : 51 : 23 57.00 7.43 ND 750.9 16.84 14 : 54 : 23 60.00 7.12 ND 700.6 17.12 2.90 14 : 57 : 23 63.00 6.31 ND 643.8 17.23 15 : 0 : 23 66.00 7.09 ND 567.2 17.45 15 : 3 : 23 69.00 6.36 ND 557.5 17.53 15 : 6 : 23 72.00 6.05 ND 531.3 17.65 15 : 9 : 23 75.00 7.04 ND 555.4 17.63 2.45 15 : 12 : 23 78.00 6.73 ND 499.0 17.82 15 : 15 : 23 81.00 6.75 ND 533.9 17.83 15 : 18 : 23 84.00 7.80 ND 576.5 17.74 15 : 21 : 23 87.00 7.08 ND 568.2 17.71 2.40 15 : 24 : 23 90.00 8.81 ND 529.3 17.60 15 : 27 : 23 93.00 8.88 ND 532.8 17.43 2.70 15 : 30 : 23 96.00 9.29 ND 596.0 17.48 15 : 33 : 23 99.00 9.31 ND 605.5 17.60 15 : 36 : 23 102.00 5.91 ND 527.4 18.16 15 : 39 : 23 105.00 5.58 ND 483.8 18.38 2.03 15 : 42 : 23 108.00 6.72 ND 475.4 17.96 15 : 45 : 23 111.00 8.60 ND 466.2 18.05 15 : 48 : 23 114.00 9.19 ND 477.0 18.04 15 : 51 : 23 117.00 5.59 ND 399.4 18.39 15 : 54 : 23 120.00 5.21 ND 453.6 18.42 1.82 15 : 57 : 23 123.00 5.18 ND 464.2 18.34 1.70 Boxed values are identified as oultiers

### Straight-Grate WB 26 Fluxed Pellets 2/Dec/93 SO2 CO NOx 02 CO2

H : M : S Time,min ppm(wet) ppm(dry) ppm(wet) pct(dry) pct(dry) 10 : 42 : 27 -0.00 28.50 ND 14.1 20.73 10 : 45 : 27 3.00 8.20 ND 16.5 20.76 0.05 10 : 48 : 27 6.00 1.10 ND 17.5 20.89 10 : 51 :27 9.00 1.74 ND 18.5 20.84 0.04 10 : 54 : 27 12.00 4.75 ND 19.2 20.85 10 : 57 : 27 15.00 4.07 ND 19.4 20.85 0.05 11 : 0 : 27 18.00 8.74 ND 18.8 20.86 11 : 3 : 27 21.00 5.73 ND 18.2 20.84 11 : 6 : 27 24.00 6.99 ND 17.0 20.84 11 : 9 : 27 27.00 4.89 ND 16.3 20.82 11 : 12 : 27 30.00 3.50 ND 15.4 20.81 0.03 11 : 15 : 27 33.00 3.48 ND 14.6 20.83 11 : 18 : 27 36.00 16.04 ND 14.4 20.68 11 :21 :27 39.00 34.18 ND 14.3 20.64 11 : 24 : 27 42.00 19.13 ND 13.7 20.75 11 : 27 : 27 45.00 21.82 ND 13.0 20.71 11 : 30 : 27 48.00 21.28 ND 12.3 20.67 0.05 11 :33 : 27 51.00 24.21 ND 11.8 20.62 11 : 36 : 27 54.00 21.24 ND 11.5 20.57 0.10 11 : 39 : 27 57.00 23.92 ND 10.9 20.60 11 :42 : 27 60.00 27.03 ND 10.9 20.51 0.05 11 : 45 : 27 63.00 16.66 ND 10.3 20.74 11 : 48 : 27 66.00 10.04 ND 10.1 20.80 0.05 11 :51 :27 69.00 17.01 ND 9.9 20.77 11 :54 : 27 72.00 24.99 ND 9.6 21.04 11 : 57 : 27 75.00 32.98 ND 9.6 20.46 0.101 12 : 0 : 27 78.00 11.22 ND 9.4 20.96 Boxed values are identified as oultiers SO2 @3-33 & 36-78 min tested separately for outliers