**Page 1 of 33** Administrative Order by Consent Alternative Method Proposal for Furnace Line 3

**As indicated in the February 19, 2008 Administrativ e Order by Consent, effective March 3,**  **2008, signed by the Minnesota Pollution Control Age ncy (MPCA) and Hibbing Taconite**  **Company (HTC), item # 8 states:**

**“Hibtac agrees to undertake the testing and analyse s set forth**  **below to provide the MPCA with data to determine wh ether an**  **Alternative NOx Emissions Measurement Method is appr ovable by**  **the MPCA and agrees to implement the Alternative Me thod, if it is**  **approved by the MPCA.”**

**This document serves as the Alternative Method Prop osal for Furnace Line 3, as explained in**  **items # 10-12 of the Administrative Order by Consen t and contains the following information in**  **each respective Appendix:**

Appendix A: Data Points for Operating Parameters du ring 150-hour NOx Test

**Administrative Order Requirement : “The data points recorded during emissions testin**  **g conducted for these parameters at a minimum: ferrou**  **s iron content of the feed materials, pellet type, production rate, heat input, stack gas flow r**  **ate, and combustion zone temperature. Data for other parameters shall be submitted if Hibtac deter**  **mines they are relevant to NOx formation. If the MPCA determines that any further parameters tha**  **t are currently measured are relevant to NOx formation, those parameters shall be added to th**  **e list of operating parameters recorded and**
**submitted.”**

Appendix B: Stack Testing Results with Validated Da ta

**Administrative Order Requirement : “Hibtac shall submit all results of the testing t**  **o the MPCA. If Hibtac believes that any data resulting from the**  **testing is not valid, Hibtac shall include an explanation of why it believes the data is not vali**  **d with the test report and test data. All data shall be provided in an unlocked electronic spreads**  **heet.”**

Appendix C: Relative Variability Index (RVI) Determ ination

**Administrative Order Requirement :**  **“Hibtac shall analyze the calculated hourly NOx concentration for each furnace weighted by stack fl**  **ow rate and determine the relative variability index (RVI) for the data set. The variability of t**  **he stack-flow weighted NOx concentration for each furnace will be quantified by a RVI, which is**  **defined by the MPCA as the ratio of the width of a 95 percent prediction interval to the center o**  **f the interval. The stack-flow weighted NOx concentration for each hourly data point shall be c**  **alculated as follows: Page 2 of 33** 

**If the RVI for the [NOx] Fj**  **data is less than or equal to 0.20, then variabili ty will be considered to**  **be “low”. If the relative variability is greater t han 0.20, then variability will be considered to be**  **“high”.”**

Appendix D: Predictive Equation Supporting Data and Calculations

**Administrative Order Requirement : “If the RVI for the data is high, then Hibtac ma**  **y evaluate whether operating parameters (predictors) can be us**  **ed to predict NOx concentration for each stack, from which hourly mass rate emissions in pou**  **nds per hour can be calculated using hourly stack gas flow rate measurement. The MPCA will acc**  **ept a multiple regression-based predictive equation for each stack for NOx emission calculation**  **, if: 1) the residual standard deviation of the**
**random differences between the actual measured conc entration and the regression equation**  **predicted value divided by the average NOx concentra tion is less than or equal to 0.09 at the**  **midpoint of the predicted concentration; 2) the pre dictors used in the regression equations**  **incorporate, either directly or by proxy, significa nt plant parameters that could affect the NOx**  **concentration; and 3) the leverage is not large, as determined by the MPCA (leverage is a**  **measure used by statisticians to identify the exten t to which the predictors are extrapolations).**  **All supporting calculations and data used in develo ping the predictive equation shall be provided** 
**to the MPCA.”**

Appendix E: Quality Assurance and Control

**Administrative Order Requirement : “A description of and schedule for quality assur**  **ance and quality control methods by which Hibtac will ensure**  **the continuing validity of the data collected**
**for RVI determination or for the calibration of the predictive equation. The description shall** 
**include at a minimum: annual extended method 7E emi ssions testing with justification for the**  **proposed duration of testing, and the quarterly sub mittal of relevant hourly operating parameters**  **to demonstrate that operating conditions continue t o be 1) within the range of the data collected**  **during testing under Part 10, if the RVI is low or 2) within the range of data collected during**  **calibration testing of a predictive equation, if th e RVI is high. If the RVI is high and a predictive**  **equation is used, Hibtac shall provide a protocol c onsistent with US EPA’s monitoring protocol** 
**for an industrial furnace Predictive Emission Monit oring System. The protocol is available at:**  **http://www.epa/gov/ttn/emc/furnace.pdf .”** 

Appendix F: Stack Gas Flow Monitor Schedule

**Administrative Order Requirement : “A schedule for installation and certification of**  **permanent stack gas flow monitors such that installation and**  **certification occurs no later than November 30,**

**2008.” Page 3 of 33** 

Appendix G: Pellet Plant hourly NOx Emissions Reado ut Installation

**Administrative Order Requirement : “If the RVI is high and a predictive equation is**  **used, a schedule for installation of a readout in the pelle**  **t furnace operator control room with the predicted hourly NOx emissions such that installati**  **on occurs no later than November 30, 2008.”**

**It is understood by Hibbing Taconite Company that t he MPCA will either approve or disapprove**  **the use of this Alternative Method Proposal by Augu st 31, 2008.** **Page 4 of 33** 

## Appendix A Data Points for Operating Parameters during 150-hou r NOx Test

**The enclosed CD-ROM contains a folder titled “Furna ce Line 3 Alternative Method Proposal.”**  **This folder contains Barr Engineering’s Microsoft E xcel spreadsheet titled “Line 3 NOx CEMS**  **lb per hour 3-31-08 to 4-8-08.xls”. The spreadshee t’s highlighted regions indicate time periods**  **when Barr Engineering personnel were completing per iodic calibrations, moisture checks, and**  **other minor equipment maintenance, as well as all t ime periods that were determined to be**  **invalid for NOx calculation purposes. HTC used only validated data in the development of a**  **Predictive Emission Monitoring System (PEMS) for Pe llet Indurating Furnace Line 3.** 

**During the stack test, operating parameters were me asured and recorded by HTC’s Distributive**  **Control System (DCS) and retrieved using PI Histori an. A Microsoft Excel spreadsheet titled**  **“Furnace Line 3 Hourly Validated process Data.xls” contains the retrieved, validated data.** **Page 5 of 33** 

## Appendix B Stack Testing Results with Validated Data

**As noted in Appendix A, the validated operating par ameters in the spreadsheet titled “Furnace**  **Line 3 Hourly Validated Process Data.xls” does not include the highlighted cells in Barr**  **Engineering’s spreadsheet titled “Line 3 NOx CEMS lb per hour 3-31-08 to 4-8-08.xls”. In**  **order to obtain the hourly averages, HTC delineated the start and end times of each 60 minute**  **test segment, and then averaged all of the operatin g data required by the MPCA (ferrous iron**  **content of the feed material, pellet type, producti on rate, heat input, stack gas flow rate, and**  **combustion zone temperature), in addition to operat ing parameters that HTC believed may affect**  **NOx variability in the furnace. The operating param eters listed below were used to determine**  **both the relative variability index (RVI), as well as a predictive equation for each stack vent, as**  **required. Barr Engineering’s stack test report for the March 31-April 8, 2008 NOx testing for**  **Furnace Line 3 has been submitted concurrently with this Alternative Method Proposal.** 

**Indurating Furnace Line 3 Monitored Operating Par ameters** 
**1. Airflow Rates for Scrubber Houses 1 through 4 (stan**  **dard cubic feet per minute)**

**2. Furnace Feed Rate (wet long tons per hour)** 

**3. South and North Chamber gas usage (million cubic fe**  **et per hour)**

**4. Demist Differential Pressure for Scrubber Houses 1**  **through 4 (inches of water)**

**5. Venturi Differential Pressure for Scrubber Houses 1**  **through 4 (inches of water)**

**6. Water Flow Rate for Scrubber Houses 1 through 4 (ga**  **llons per minute)**

**7. Hearth Layer Depth (inches)** 

**8. Machine Speed (feet per minute)** 

**9. UDD, WEX, WBR, CAF Pressures (inches of water)** *

**10. UDD Discharge Temperature (degrees Fahrenheit)** *

**11. Burn Thru Temperature (degrees Fahrenheit)** 

**12. 2**  **nd Cooling and Firing Zone Hood Pressures (in. H**  **2 O)** 

**13. Hoods 18 and 22 Temperatures (degrees Fahrenheit)** 

**14. Machine Discharge Temperature (degrees Fahrenheit)** 

**15. Fired Pellet – Total Fe (percent)** 

**16. Fired Pellet – Fe++ (percent)** 

**17. Fired Pellet – Silica (percent)** 

**18. Green Ball Moisture (percent)** 

**19. Fired Pellet – CaO (percent)** 

**20. Satmagan and Wet Fe++ of Plant Concentrate (percent**  **)**

***UDD: Updraft Drying; WEX: Windbox Exhaust; WBR: Wi ndbox Recoup; CAF: Cooling Air Fan** 

**During the 7-day performance test conducted on Indu rating Furnace Line 3, HTC developed a**  **schedule of 7 test runs, each with specific, predet ermined operating conditions. HTC selected**  **the various operating conditions in an attempt to d etermine the relationship between specific**  **furnace operating conditions and NOx emission rates. HTC maintained the respective operating**  **conditions for durations of approximately 11 – 30 h ours, with transition periods generally**  **required between operating conditions in order to a chieve furnace stability. The transition**  **periods are noted in the submitted spreadsheet.**

**HTC’s experience has demonstrated that the time req uired for furnace stabilization between**  **operating condition changes is insignificant with r espect to HTC’s actual operation during** **Page 6 of 33**

**normal production. However, because the changes be tween conditions occurred frequently**  **during the test, the data from these transition per iods became a very significant portion in the**  **calculations, and it is believed that these periods would bias the results.** 

**Because the transition periods are insignificant du ring normal operating conditions, the transition**  **periods have been eliminated from all RVI calculati ons to better represent normal, stable furnace**  **operations that would typically occur. It should b e noted that some of the tested furnace**  **operating conditions negatively impacted pellet phy sical quality, resulting in situations where**  **HTC’s required fired pellet specifications could no t be obtained. As previously stated, the** 
**overall intent was to test furnace conditions in or der to induce NOx emissions variability, in**  **order to develop a more valid predictive equation. Page 7 of 33**  Table 1: Relative Variability Index for Conditions 1 through 7



## Appendix C Relative Variability Index (RVI) Determination

**As stated in Appendix B, HTC removed the transition periods from the RVI determination**  **calculations, because these transition periods repr esent an insignificant portion of normal**  **operating conditions. If testing were conducted un der normal operating conditions only, over a**  **longer time period, the effect of the transition pe riods would become even more insignificant,**  **allowing HTC’s furnace NOx emission results to meet the MPCA’s RVI threshold of 0.20,**  **indicating low variability. However, because the t est duration was 7 days, only 150 hours of**  **valid data, representing multiple furnace operating conditions, was available to determine the** 
**sources of variation within the NOx emissions. Aver age NOx concentrations for each stack vent**  **were determined, with one operating condition not m eeting the RVI low variability requirement**  **of 0.20. Average NOx emission rates are displayed i n parts per million.** 



### SV029 SV030 SV031 SV032**Page 8 of 33** 

## Appendix D Predictive Equation Supporting Data and Calculation s

**Using the validated operating data detailed in Appe ndix B, HTC produced a predictive equation**  **using** Minitab **®. To determine the significant parameters related to NOx formation, HTC**  **developed a series of furnace operating test condit ions in an effort to induce NOx emission**  **variability. These operating conditions were contr olled by HTC’s DCS and selected to simulate**  **potential furnace operating conditions. The test operating conditions were as follows:** 

• **Indexing the furnace (reduced temperatures, tonnage , and airflow) to imitate**  **reduced tonnage situations**

• **Non-realistic situations in which HTC would not cho ose to operate because of**  **reduced quality and/or tonnage**

• **Maximum tonnage (approximately 470 tons per hour), airflow, and temperatures**  **to simulate a standard compression pellet run when the furnaces are running at**  **optimum capacity.**

**Even though the operating conditions were changed n umerous times during this seven-day test, it**  **is more typical that HTC maintains similar furnace operating conditions for several days or**  **longer. When low tonnage situations occur, HTC may index for up to several weeks at a time.**  **Therefore, the transition periods that were experie nced during the seven-day test would actually**  **have a very minimal effect on the NOx emissions over an extended period of time, a situation**  **which is more representative of how HTC typically o perates. When testing each condition for**  **11-30 hour time periods, the transition periods wil l have a much larger impact during the test**  **than typical transition periods would during period s of normal furnace operation.** 

**Therefore, a predictive equation without the transi tion periods included has been developed. To**  **begin with, a best subset regression analysis was d eveloped, taking into account the best model**  **using 1 to 10 variables (due to the experience gain ed in the analysis of Indurating Furnace Lines**  **1 and 2, it is evident that the use of more than 10 variables does not result in further**  **improvements to the R-squared value). Shown below are the best subsets regression analyses for**  **Stacks 1 (SV029), 2 (SV030), 3 (SV031), and 4 (SV03 2).** **Page 9 of 33 Page 10 of 33** **Page 11 of 33 Page 12 of 33** **Page 13 of 33**

**For each respective stack vent’s analysis, the R 2**  **from a 1 variable model to a 10 variable model was calculated. After completing multiple calculat**  **ions, it was determined that the model’s accuracy does not improve significantly when taking**  **into account greater than 5 variables. Therefore, it has been determined that 5 significan**  **t variables exist for each stack vent, with the remaining variables classified as insignificant.** 

**Shown below are the regression analyses for stacks 1 (SV029), 2 (SV030), 3 (SV031), and 4**  **(SV032), using a 5-variable model. Page 14 of 33** **Page 15 of 33 Page 16 of 33** 

**The Administrative Order by Consent states the foll owing:**  **“The MPCA will accept a multiple regression-based predictive equation for each stack**  **for NOx emission calculation, if: 1) the Page 17 of 33** 

**residual standard deviation of the random differenc es between the actual measured concentration**  **and the regression equation predicted value divided by the average NOx concentration is less**  **than or equal to 0.09 at the midpoint of the predic ted concentration.”.** 

**For the regression analyses,** Minitab **® stored the residuals for each data point employed by the**  **model. Along with storage of the residuals, the st andard deviation of the residuals and the**  **average of the actual NOx concentrations have also been calculated. This data allowed**  **determinations to be made regarding adherence to th e requirement of 0.09. Below is the** 
Minitab **® output for this calculation:**

**Stack 1 (SV029) 1.686 / 36.853 = .0457 Stack 2 (SV030) 1.519 / 49.737 = .0305**  **Stack 3 (SV031) 1.695 / 82.539 = .0205 Stack 4 (SV032) 2.201 / 101.96 = .0216** **Page 18 of 33 Page 19 of 33** **Page 20 of 33** 

## Appendix E Quality Assurance and Control

**1.** Applicability

a. Identify source name, location, and emission unit n umber(s)

**Hibbing Taconite Company Highway 5 North** 

**P.O. Box 589 Hibbing, MN 55746-0589** 

Pellet Indurating Furnace Line 3 (EU 022) Control Equipment (CE) Stack Vent (SV)

**032 029**

**033 030**

**034 031**

**035 032**

b. Identify the type of industry;

**SIC Code: 1011 NAISC Code: 212210 (Iron Ore Mining)** 

c. Identify the process of interest;

**Pellet Indurating Furnace Line 3**

d. Identify the regulations that apply (e.g.; NSPS, NE SHAP, SIP);

**Several regulations apply to Pellet Indurating Furn ace Line 3. However, only the**  **Regional Haze Rule applies to the predictive emissi on monitoring requirements**  **outlined in this protocol.**

e. Identify the pollutant(s) subject to monitoring (in formation on major/area source determination).

**NOx concentrations in parts per million (ppm) are ca lculated and converted to**  **either pounds per hour or pounds per ton using gas flow rates measurements**  **recorded by installed stack gas flow monitors.**

f. Provide expected dates of monitor compliance demons tration testing

**Installation, calibration, and certification of sta ck gas flow monitors will occur by**  **November 30, 2008, as per the requirements detailed in the**  Administrative Order by Consent

**dated March 3, 2008.**

**2.** Source Description

a. Provide a simplified block flow diagram with parame ter monitoring**Page 21 of 33** points and emission sampling points identified (e.g .; sampling ports in the stack);



### [1]

FURNACE

FEED RATE (LONG

TONS PER HOUR)

UDD

Zone DDD

Zone PREHEAT

Zone FIRING

Zone

HEARTH

LAYER

DEPTH (INCHES) 

### [9]



### [8] UPDRAFT
DRYING

HEADER

PRESSURE 

### [6]

**To**
**Scrubbers** 

### [7] 2 nd

COOLING

HOOD

PRESSURE

**Windbox**

**Exhaust fan Fresh Air** 

**Intake** WIND BOX

EXHAUST

HEADER

PRESSURE

**Cooling Air**

**Fan** UDD

Zone DDD

Zone PREHEAT

Zone FIRING

Zone A. F.

Zone PRI COOLING

Zone S COOL

Zone

COOLING

AIR FAN

HEADER
PRESSURE 

### [4]**Page 22 of 33 Natural Gas Flow (Million Cubic Feet) to** 
**South Chamber**

Hood Temp (Wind Box 18)
**Lower**

**Burner** Typical South Firing Chamber

Bed 

### [5] Natural Gas

Flow to both
South and North Firing

Chambers 

### [2] UPDRAFT DRYING

DISCHARGE TEMP (TO SCRUBBERS) 

### [3]

HOOD TEMP

(WIND BOX 18) 

### [5]

**To DDD**
**Hood zone**

**Windbox Recoup Fan**  **Fresh Air**
**Intake Cooling Air Fan**  UDD

Zone DDD

Zone PREHEAT

Zone FIRING

Zone A. F.

Zone PRI COOLING

Zone S COOL

Zone**Page 23 of 33**

b. Provide a discussion of process or equipment operat ions that are known to significantly affect emissions or monitori ng procedures (e.g., batch operations, plant schedules, product c hanges).

**HTC produces two types of pellets (standard and hig h compression). The typical**  **split annually is 75 percent standard pellets and 2 5 percent high compression**  **pellets. Limestone is added to each type of pellet to improve the pellet physical**  **strength, in particular, the compression strength. For both, less than one percent**  **by weight limestone is added to the green (unfired) pellets, with high compression**  **addition rates double in comparison to standard pel lets. When producing high**  **compression pellets, the natural gas burner tempera ture set points are increased to**  **calcinate the increased limestone quantities that a re added during a high**  **compression production run.**

**HTC has developed a process control strategy to opt imize process air flow at less**  **than 100 percent production rates. This optimizatio n matches process air flow**  **with production rate and minimizes excess process a ir that is not needed. Finally,**  **two shutdowns per furnace line occur each calendar year. The length of a**  **shutdown is usually between 10 and 21 days and is d ependant on the amount of**  **scheduled maintenance performed. Page 24 of 33** 

**3.** Control Equipment Description

a. Provide a simplified block flow diagram with parame ter monitoring points and emission sampling points identified (e.g .; sampling ports in the stack);

**Hood Exhaust Fan (Primary)** 
**to Scrubber #1** Process Scrubber Header (Common to both Fans)

**Venturi**
**Differential**

**Pressure**

Scrubber #4 (Typical Scrubber) **Process Air Flow from**
**Scrubber Header to**

**Scrubber #4 Wind box Exhaust**  **Fan (Primary)**

**to Scrubber #4**

**Four Header Outlet Ducts**
**One for Each Scrubber Wind box** 
**Exhaust**
**Multi-Tube**

**House**

**Windbox**

**Exhaust**

**Fan Hood** 
**Exhaust**

**Fan Furnace** 

**Process Air From Updraft**  **Drying Zone Multi-Tube** 
**Differential Pressure**

**Future Air Flow Monitoring**  **Wind Box Exhaust Fan (Secondary)** 
**to Scrubber #3 Hood Exhaust**  **Fan (Secondary)**
**to Scrubber #2 Page 25 of 33** 

b. List monitored operating parameters and normal oper ating ranges;

Pellet Indurating Furnace Line 3 (EU 022)

CE SV Venturi Differential

Pressure (inches of water) Demist Differential Pressure (inches of water) Water Flow (gallons per minute)

**032 029 > 4.0 > 0.3**  **> 445**

**033 030 > 3.2 > 0.2**  **> 419**

**034 031 > 1.9 > 0.3**  **> 431**

**035 032 > 3.3 > 0.2**  **> 436**

c. Provide a discussion of operating procedures that a re known to significantly affect emissions (e.g., catalytic bed replacement schedules, ESP rapping cycles, fabric filter cleani ng cycles).

**Please refer to 2b.**

**4.** Monitoring System Design

a. Install, calibrate, operate, and maintain a continu ous PEMS;

**The monitoring system will be installed, calibrated , and operational by November**  **30, 2008.**

b. Provide a general description of the software and h ardware components of the PEMS including manufacturer, type of computer, name(s) of software product(s), monitoring technique (e.g., method of e mission correlation).

Manufacturer literature and other similar informati on shall also be submitted, as appropriate;

**Sick/Maihak FLOWSIC 100 Ultrasonic Flow Meters will be installed on each of**  **Pellet Indurating Furnace Line 3 Stack Vents (SV029 – SV032). These flow**  **meters calculate stack gas volume flow measurements , with the calculated data** 
**transmitted to the Fisher Rosemount Distributed Con trol System (DCS). In**  **addition to stack gas flow rates, other process ope rating parameters relevant to**  **NOx formation are collected by the DCS at the interv als specified in 4f. DCS**  **readings are transmitted to the OSI Soft PI histori an database, which facilitates**  **storage and retrieval of historical data.**

**NOx predictive models have been developed for each r espective stack vent, with**  **each model utilizing specific parameters to calcula te NOx concentrations in parts**  **per million (ppm). Stack gas flow rates are used t o convert NOx concentrations**  **in ppm to NOx emission rates in pounds per hour. P I historian is configured to**  **collect and process all predictive model parameters , with NOx concentrations**  **displayed visually in PI ProcessBook. Page 26 of 33** 

**c. List all elements used in the PEMS to be measured (**  **e.g., pollutant(s), other exhaust constituent(s) such as O for correction pur**  **poses, process parameter(s), and/or emission control device parameter(s));** 

Pellet Indurating Furnace Line 3 (EU022)

CE SV Description Predictive Model Variables PI Tag ID **Furnace Feed Rate [1] ADBI5160 Hearth Layer Depth [9] ADBI5491** 

**Total Natural Gas Usage [2] ADBI5108** 

**ADBI5109 Updraft Drying Discharge**  **Temperature [3] ADBI5195**  **032 029**  **Hood Exhaust (Primary)**

**Cooling Air Fan Header Pressure [4]**  **ADBI5122**

**Furnace Feed Rate [1] ADBI5160**

**Total Natural Gas Usage [2] ADBI5108** 

**ADBI5109 Updraft Drying Discharge**  **Temperature [3] ADBI5195** 

**Hood 18 Temperature [5] ADBI5199 033**  **030 Hood Exhaust (Secondary)** 

**Cooling Air Fan Header Pressure [4]**  **ADBI5122**

**Furnace Feed Rate [1] ADBI5160 Updraft Drying Hood Pressure** 

**[8] ADBI5245** 

**2 nd**  **Cooling Hood Pressure [6] ADBI5193 Hood 18 Temperature [5] ADBI5199**  **034 031**  **Wind Box Exhaust (Secondary)**

**Cooling Air Fan Header Pressure [4]**  **ADBI5122**

**Furnace Feed Rate [1] ADBI5160 Updraft Drying Hood Pressure** 

**[8] ADBI5245** 

**Wind Box Exhaust Pressure [7] ADBI5246 Hood 18 Temperature [5] ADBI5199**  **035 032**  **Wind Box Exhaust (Primary)**

**Cooling Air Fan Header Pressure [4]**  **ADBI5122**

**[*] denotes location in diagrams contained in 2a an** **d 3a**

d. List all measurement or sampling locations (e.g., v ent or stack location, process parameter measurement location, fuel sampli ng location, work stations);

**Please refer to Figure 1.**

e. Provide a simplified block flow diagram of the moni toring system overlaying process or control device diagram (could be include d in Source Description and Control Equipment Description);

**Please refer to Figure 1. Page 27 of 33** 

f. Provide a description of sensors and analytical dev ices (e.g., thermocouple for temperature, pressure diaphragm for flow rate);

g. Provide a description of the data acquisition and h andling system operation including sample calculations (e.g., parameters to be recorded, frequency of measurement, data averaging time, reporting units, recording process);

**The data acquisition and handling system is describ ed in 4b, and sensors used to**  **measure predictive model variables, along with data collection intervals, are listed** 
**in 4f.**

**The following sample equations are used to calculat e NOx emissions from Pellet**  **Indurating Furnace Line 1. The equations reference predictive model variables**  **and associated PI Tag IDs listed in 4c. It should be noted that the predictive**  **equations calculate NOx concentrations in parts per million, which will be**  **converted to NOx emission rates (in pounds per hour ) using stack gas flow** 

**measurements.**

**NOx Predictive Equation for EU022, CE032, SV029 (PI Tag ID ADBI5950)** 

**(IF TAGVAL('ADBI5160') > 400 THEN – 39.9 + 0.0746 *** **(TAGVAL('ADBI5160') + 1.50 * (TAGVAL('ADBI5491') +** **0.528** Predictive

Model
Variable Description Manufacturer Part

Number HTC Stock

Code Data

Collection

Interval
**Furnace Feed**

**Rate Belt Scale Ramsey 10-17-2 Direct Order 5 seconds** 

**Total Natural Gas Usage**  **Smart**

**Transmitter Honeywell SMV3000 Direct Order 0.5 seconds** 

**Updraft Drying Discharge**  **Temperature Type R** 

**Thermocouple Dynametrics**  **24R**

**SCPT2CN7**
**11MH2X3/4**

**BR35 1108208 5 seconds** 

**Cooling Air**
**Fan Header**

**Pressure Pressure** 

**Transmitter ABB 621DB2H 20067989**  **200**
**milliseconds**

**Hood 18 Temperature**  **Type R**

**Thermocouple Dynametrics**  **24R**

**SCPT2CN7**
**11MH2X3/4**

**BR35 1108208 5 seconds** 

**2 nd**  **Cooling**
**Hood Pressure Pressure** 

**Transmitter ABB 621DB2H 20067989 5 seconds** 

**Wind Box**
**Exhaust**

**Pressure Pressure** 

**Transmitter ABB 621DB2H 20067989 5 seconds** 

**Updraft Drying**
**Hood Pressure Pressure** 

**Transmitter ABB 621DB2H 20067989 5 seconds** 

**Hearth Layer Depth** **Page 28 of 33 (TAGVAL('ADBI5108') + TAGVAL('ADBI5109')) + 0.0773**  ***** **TAGVAL('ADBI5195') – 2.76 * TAGVAL('ADBI5122') ELSE** **0.0)**

**NOx Predictive Equation for EU022, CE033, SV030 (PI Tag ID ADBI5951)** 

**(IF TAGVAL('ADBI5160') > 400 THEN – 125 + 0.109 *** **(TAGVAL('ADBI5160') + 0.436 * (TAGVAL('ADBI5108') +** **TAGVAL('ADBI5109')) + 0.0648 * TAGVAL('ADBI5195') +** **0.0414 *** **TAGVAL('ADBI5199') – 2.33 * TAGVAL('ADBI5122') ELSE** **0.0)**

**NOx Predictive Equation for EU022, CE034, SV031 (PI Tag ID ADBI5952)** 

**(IF TAGVAL('ADBI5160') > 400 THEN – 232 + 0.181 *** **(TAGVAL('ADBI5160') + 24.2 * TAGVAL('ADBI5245') + 4** **.38 *** **TAGVAL('ADBI5193') + 0.155 * TAGVAL('ADBI5199') – 2** **.80 *** **TAGVAL('ADBI5122') ELSE 0.0)**

**NOx Predictive Equation for EU022, CE035, SV032 (PI Tag ID ADBI5953)** 

**(IF TAGVAL('ADBI5160') > 400 THEN – 347 + 0.301 * TA** **GVAL('ADBI5160')** **+ 18.8 * (TAGVAL('ADBI5245') + 1.95 * TAGVAL('ADBI5** **246') + 0.189 *** **TAGVAL('ADBI5199') – 6.37 * TAGVAL('ADBI5122') ELSE** **0.0)**

**Total NOx Emissions for EU022 (PI Tag ID ADBI5954)**

**TAGVAL('ADBI5160')+TAGVAL('ADBI5951')+TAGVAL('ADBI5 952')+TAG**  **VAL('ADBI5953')**

h. Provide checklists, data sheets, and report format as necessary for compliance determination (e.g., forms for record ke eping).

**As indicated in 4b, PI historian is used for storag e and retrieval of predictive**  **model data. Ellipse functions as HTC’s maintenance information management**  **system. Preventive maintenance, repair, and calibr ation of monitoring equipment**  **is planned, scheduled, and maintained using Ellipse . Quarterly reports consisting**  **of emissions and operating parameter data will be s ubmitted to the MPCA 30**  **days following the end of each calendar quarter.**

**5.** Support Testing and Data for Protocol Design

a. Provide a description of field and/or laboratory te sting conducted in developing the correlation (e.g., measurement inter ference check, parameter/emission correlation test plan, instrumen t range calibrations):

**Please refer to Appendices A – D.**

b. Provide graphs showing the correlation, and support ing data (e.g., correlation test results, predicted versus measured plots, sensitivity plots, computer modeling.

**Please refer to Appendices A – D. Page 29 of 33** 

**6.** Initial Verification Test Procedures

a. Perform an initial relative accuracy test (RA test) to verify the performance of the PEMS over the permitted operating range. The PEMS must meet the relative accuracy requirement of the applicable Per formance Specification in 40 CFR Part 60, Appendix B. The test shall utilize the test methods of 40 CFR Part 60, Appendix A.

**Following the installation and certification of sta ck gas flow meters, currently**  **scheduled for completion by November 30, 2008, HTC will conduct stack testing**  **in conformance with the initial verification test p rocedures.** 

b. Identify the most significant independently modifia ble parameter affecting the emissions. Within the limits of safe unit opera tion, and typical of the anticipated range of operation, test the selected p arameter for three RA test data sets at the low range, three at the normal ope rating range and three at the high operating range of that parameter, for a t otal of nine RA test data

sets. Each RA test data set should be between 21 an d 60 minutes in duration:

**Hood 18 temperature will be used as the most signif icant independently**  **modifiable parameter affecting NOx emissions. Low, normal, and high operating**  **ranges for this parameter will be selected based up on temperature ranges that** 
**allow HTC to meet and/or exceed its customers’ fire d pellet quality specifications**  **for both standard and high compression pellet produ ction operating conditions.** 

c. Maintain a log or sampling report for each required stack test listing the emission rate in accordance with the applicable emi ssion limitations:

**HTC will adhere to all pre- and post-stack testing notification and recordkeeping**  **requirements contained in HTC’s Title V (Part 70) A ir Emissions Permit. Each**  **subsequent stack testing campaign will be summarize d and reported to the MPCA**  **using a final stack test report.**

d. Demonstrate the ability of the PEMS to detect exces sive sensor failure modes that would adversely affect PEMS emission determina tion. These failure modes include gross sensor failure or sensor drift.

i. The owner or operator shall demonstrate the ability to detect sensor
failures that would cause the PEMS emissions determ ination to drift significantly from the original PEMS value.

**The identified predictive emission parameters are a lso critical parameters**  **used to maintain HTC’s fired pellet quality specifi cations. As a result,**  **instances of sensor failure and/or drift are prompt ly detected and resolved.**  **In addition, analytical laboratory analyses allow c onfirmation of**  **conformance to fired pellet quality specifications, thereby ensuring that** 
**sensor failure or drift has not occurred.**

ii. The owner or operator may use calculated sensor val ues based upon the mathematical relationships established with the other sensors used in the PEMS. The owner or operator shall establish and demonstrate
the number and combination of calculated sensor val ues which would**Page 30 of 33** cause PEMS emission determination to drift signific antly from the original PEMS value.

**Mathematical relationships between various paramete rs will not be used in**  **the predictive emission monitoring system.**

**7.** Quality Assurance Plan

a. Provide a list of the input parameters to the PEMS (e.g., transducers, sensors, gas chromatograph, periodic laboratory ana lysis), and a description of the sensor validation procedure (e.g., manual or automatic check):

**Please refer to 4f.**

b. Provide a description of routine control checks to be performed during operating periods (e.g., preventive maintenance sch edule, daily manual or automatic sensor drift determinations, periodic ins trument calibrations)

**Preventive maintenance, repair, and calibration of monitoring equipment is**  **planned, scheduled, and maintained using Ellipse.**

c. Provide minimum data availability requirements and procedures for supplying missing data (including specifications fo r equipment outages for QA/QC checks):

**Please refer to 6di.**

d. List corrective action triggers [e.g., response tim e deterioration limit on pressure sensor, use of statistical process control (SPC) determinations of problems, sensor validation alarms]:

**Please refer to 6di.**

e. List trouble-shooting procedures and potential corr ective actions:

f. Provide an inventory of replacement and repair supp lies for the sensors:

**Please refer to 4f.**

g. Specify, for each input parameter to the PEMS, the drift criteria for excessive error (e.g.: the drift limit of each inpu t sensor that would cause the PEMS to exceed relative accuracy requirements):

**Drift criteria for predictive emission monitoring s ystem parameters have been**  **established and are maintained using the preexistin g specifications for**  **maintenance of overall fired pellet quality.**

h. Conduct a quarterly electronic data accuracy assess ment test of the PEMS.

**A quarterly electronic data accuracy assessment of the PEMS will be conducted**  **and reported to the MPCA. Page 31 of 33** 

i. Conduct semiannual RA tests of the PEMS. Annual RA tests may be
conducted if the most recent RA test result is less than or equal to 7.5%. Identify the most significant independently modifia ble parameter affecting the emissions. Within the limits of safe unit opera tion and typical of the anticipated range of operation, test the selected p arameter for three RA test data pairs at the low range, three at the normal op erating range, and three at the high operating range of that parameter for a to tal of nine RA test data

sets. Each RA test data set should be between 21 an d 60 minutes in duration:

**HTC will conduct annual method 7E testing to verify continuing accuracy of the**  **PEMS, using the parameter specified in 6b.**

**8.** PEMS Tuning

a. Perform tuning of the PEMS provided that the fundam ental mathematical relationships in the PEMS model are not changed.

**Annual 7E stack testing, in combination with the qu arterly electronic data**  **assessments, will allow for tuning of the PEMS, as necessary.** 

b. Perform tuning of the PEMS in case of sensor recali bration or sensor replacement provided that the fundamental mathemati cal relationships in the PEMS model are not changed.

**Annual 7E stack testing, in combination with the qu arterly electronic data**  **assessments, will allow for tuning of the PEMS, as necessary. In addition,**  **calibration and/or repair procedures for monitoring equipment will ensure that the**  **PEMS output retains RA requirements. Page 32 of 33** **Page 33 of 33** 

## Appendix G Pellet Plant Hourly NOx Emissions Readout Installat ion

**Furnace Line 3 real-time NOx predictions per individ ual stack are now recorded in PI Historian.**  **The NOx predictions are calculated from the models t hat were created from the Furnace Line 3**  **NOx performance test that occurred on March 31-April 8, 2008. These predictions are accessible**  **by staff throughout the property, as well as employ ees in the Pelletizing control room, where the**  **operator can view real-time predicted NOx emissions using PI ProcessBook. The historical data**  **can be retrieved and processed using Microsoft Exce l’s PI Datalink feature.**