## Predictive Emission Monitoring System for Nitrogen Oxides December 9, 2009

1.0 Scope and Application

1.1 Hibbing Taconite Company (HTC), an unincorporate d joint venture, is the owner and operator of a taconite (magnetite) ore mining and beneficiation facility located in Hibbing, Minnesota. According to the terms and conditions of HTC’s March 3, 2008 Admi nistrative Order by Consent with the Minnesota Pollution Control Agency (MPCA), a predictive em ission monitoring system (PEMS) is used to calculate emissions of nitrogen oxides (NO x 

### ) for each of HTC’s three pell et indurating furnaces. The PEMS complies with the requirements of 40 Code of Federal Regulations (CFR) Part 60, Appendix B ( Performance Specification 16 – Specifications and Te st Procedures for Predictive Emission Monitoring Systems in Stationary Sources)

. 1.2 Following installation of the PEMS, HTC will complete an initial certification test to classify the PEMS as acceptable for use, and ongoing quality assurance tests will also be conducted to ensure the PEMS is operating properly. In addition, HTC has established an ongoing sensor evaluation procedure prior to PEMS certification. The PEMS initial certification test wi ll be performed before reporting any PEMS data as quality assured.


## 2.0 Summary of Performance Specifications

2.1 For initial PEMS certification, HTC will perform a minimum 27-run, 3-level (9 runs at each level) relative accuracy test using U.S. Environm ental Protection Agency (EPA) Method 7E (Determination of Nitrogen Oxides Emissions from Stationary Sources) , which is detailed in 40 CFR Part 60, Appendix A

. Additionally, the PEMS data will be evaluated for bias and by F-test and correlation analysis. Relative to periodic quality assurance, HTC will also cond uct quarterly relative accuracy audits (RAAs) and annual relative accuracy test audi ts (RATAs) to assess ongoing PEMS operation. The frequency of the RAAs and RATAs may be shortened by successful operation of the PEMS during a prior year.



## 3.0 Definitions

3.1 Data Recorder means the equipment that provides a perman ent record of the PEMS output. The data recorder may include automatic data reduction capabi lities and may include el ectronic data records, paper records, or a combination of electronic data and paper records.

3.2 Defective sensor means a sensor that is responsible for PE MS malfunction or that operates outside the approved operating envelope. A de fective sensor may be functioni ng properly, but because it is operating outside the approved operating envelope, th e resulting predicted em ission is not validated.Page 2 of 36 

### 3.3 Operating envelope means the defined range of a parameter input that is established during PEMS development. Emission data generated from parame ter inputs that are beyond the operating envelope are not considered quality assured and are therefore unacceptable.

3.4 PEMS means all of the equipment required to predict an emission concentrati on or emission rate. The system may consist of any of the following major subsystems: sensors and sensor interfaces, emission model, algorithm, or equation that uses process data to generate an output that is proportional to the emission concentration or emission rate, data recorder, and sensor evaluation system.

3.5 PEMS training means the process of developing or conf irming the operation of the PEMS against a reference method under specified conditions.

3.6 Quarter means a quarter of a calendar year in which th ere are at least 168 emi ssion unit operating hours.

3.7 Reconciled Process Data means substitute data that are generated by a sensor evaluation system to replace that of a failed sensor. Reconciled process data may not be used without approval from the Administrator.

3.8 Relative Accuracy means the accuracy of the PEMS when comp ared to a reference method (RM) at the source. The RA is the average difference between the pollutant PEMS and RM data for a specified number of comparison runs plus a 2.5 percent confidence coefficient, divided by the average of the RM
tests.

3.9 Relative Accuracy Audit means a quarterly audit of the PEMS against a portable analyzer meeting the requirements of ASTM D6522–00 or a RM for a specifi ed number of runs. A RM may be used in place of the portable analyzer for the RAA.

3.10 Relative Accuracy Test Audit means a RA test that is performed at least once every four calendar quarters after the initial certifi cation test while the PEMS is opera ting at the normal operating level.

3.11 Reference Value means a PEMS baseline value that may be established by RM testing under conditions when all sensors are functioning properly. This re ference value may then be used in the sensor evaluation system or in adjusting new sensors.

3.12 Sensor Evaluation System means the equipment or procedure used to periodically assess the quality of sensor input data. This system may be a sub-mode l that periodically cross- checks sensor inputs among themselves or any other procedure that checks sensor inte grity at least daily (w hen operated for more than one hour in any calendar day).

3.13 Sensors and Sensor Interface means the equipment that measures the process input signals and transports them to the emission prediction system.


## 4.0 Equipment and Supplies

4.1 Number of Input Parameters

NOx emission rates are calculated as follows:



### [1] 3 ,2 ,1 ; 4

1 

###   

# 

 

### jQE

i ji jPage 3 of 36 

### Where E j 

### is NO x 

### emissions from the entire furnace of Line j, lb NO x 

### /hr; Q ij 

### is the predicted mass emission rate for NO x 

### in the gas stream of Stack i at Line j, lb/hr, the algebraic detail of which can be found in [2] through [4]; Stacks 1 through 4 de note SV 021 through SV 024 for Line 1; SV 028 downward through SV 025 for Line 2; SV 029 through SV 032 for Line 3. The following multiple linear regressi on equations are used to calculate Q ij


### . )FeTotal(171.66)22Hood(19721.0)Cool2(5925.5)Depth HL(399.18)SWF(064458.07.4607 Q nd 1 11   

  )FeWet(737.12)CaO(85.77Fe)Total(59.101)22Hood(17568.0)T Udd(06520.03.6732 Q 21 

     )FeWet(122.12)FeTotal(24.5322)Hood(32661.0T) Udd(24631.0)Mspeed(874.133.3846 Q 31 

  

  )FeTotal(831.8022)od 0.17165(Ho P) .5475(Wex 4)SVen(540.38Gas) S(4258.16.5776 Q 4

41  

   

### [2]


##        )FeSat(751.1318 Hood 37644.0T Udd 0.10259 Mspeed 372.16Depth HL5.06713.0801Q

12   

   

##        )FeSat(493.4CAF770.218 Hood 247114.0SVen840.24Feed17920.092.856Q 2 22  

    

##         18 Hood 29527.0Thru B038051.0PWex 3126.3SWF 0.10228 Gas S0533.176.175Q 3

32 

##  

 

  

###         18 Hood 28753.0Mspeed 926.41S WF08543.0SVen 004.32Gas N5379.325.618Q 4 4 42  

   

### [3]


##   

#       )FeWet(495.6Silica258.6118 Hood 071846.0Cool24145.1Mspeed 6105.896.29Q nd

13 

     

##        )18 Hood(077930.0PWex 5507.2S WF014698.0Gas S1165.1Feed 0.139487 382.190Q 2

23 

    

##        GB(6.072T) MD10263.018Hood 208412.0Mspeed 762.41Depth HL9202.617.934Q

33 

    

##         CAF9963.418Hood 14823.0P Udd013.30Gas S3162.1Feed 0.28596 04.752Q

43      

### [4]

Where,

WF S 1 

### is the water flow rate of the wet sc rubber at Stack 1 (g allons per minute); HL Depth is the furnace hear th layer depth (inches); 2 nd 

### Cool is the second cooling hood pre ssure (inches of water column); Hood 22 is the hood temperature measured at Windbox 22 (degrees Fahrenheit); Total Fe is analyzed for fired pellets (percent); Udd T is the updraft drying (zone) discharg e temperature (degrees Fahrenheit); CaO is analyzed for fired pellets (percent); Wet Fe ++ 

### is wet Fe ++ 

### of concentrate (percent); Mspeed is the linear moving speed of the traveling grate of the i ndurating machine (feet per minute); S Gas is the total natural gas usage of the south firing chamber (thousand cubic feet per hour); Ven S 4 

### is the Venturi differential pressure for the we t scrubber at Stack 4 (inches of water column); Wex P is the pressure measured at the windbox exhaust header (inche s of water column); Hood 18 is the hood temperature measured at Windbox 18 (degrees Fahrenheit); Sat Fe ++ 

### is Satmagan Fe ++ 

### , analyzed for concentrate (percent); Feed is the furnace green ball feed rate (wet long tons per hour); Ven S 2 

### is the Venturi differential pressure for the we t scrubber at Stack 2 (inches of water column); CAF is the pressure measured at the cooli ng air fan header (inches of water column); WF S 3 

### is the water flow rate of the wet sc rubber at Stack 3 (g allons per minute); WF S 4 

### is the water flow rate of the wet sc rubber at Stack 4 (g allons per minute); B Thru is the temperature beneath the pellet bed in the firing zone (degrees Fahrenheit); N Gas is the total natural gas usage of the nor th firing chamber (thousa nd cubic feet per hour); Silica is analyzed for fired pellets (percent); WF S 2 

### is the water flow rate of the wet sc rubber at Stack 2 (g allons per minute); MD Temp is the machine discharge temperature (degrees Fahrenheit); GB is the moisture content of green balls (percent wet basis); Udd P is the pressure measured at the updr aft drying zone (inches of water column);Page 4 of 36


### (Note that some variables in the righ t-hand side of [2] may app ear to be identical to that of [3] and [4]. However, the variables found in [2], [3], and [4] are associated w ith Line 1, Line 2, and Line 3, respectively. With this understanding, the use of subscripts is minimized among the vari ables in the right- hand side of [2] through [4].)

4.2 Parameter Operating Envelopes PEMS input parameter operating envelope specifica tions for Furnace Lines 1, 2, and 3 are defined in Tables 1, 2, and 3, respectively. Minimum and ma ximum values for input parameters were developed from historical process and quality data, which are supported by Figures 1-12 (for Furnace Line 1), 13- 27 (for Furnace Line 2), and 28-41 (for Furnace Line 3).

Furnace Line 1 PEMS Input Parameters

Parameter Description Minimum Value Maximum Value Stack 1 Scrubber Water Flow Rate 28 1020 Hearth Layer Depth 2.5 9.0 2nd Cooling Hood Pressure -7.0 -1.5 Windbox 22 Hood Temperature 2150 2500 Fired Pellet Total Fe 65.70 66.40 Updraft Drying Discharge Temperature 400 700 Fired Pellet CaO 0.25 0.85 Concentrate Wet Fe++ 21.5 24.1 Machine Grate Speed 3.5 12.0 South Firing Chamber Natural Gas Usage 25 70 Stack 4 Scrubber Venturi Diffe rential Pressure 0.1 4.5 Windbox Exhaust Header Pressure 10.0 25.0 Table 1 . Furnace Line 1 Input Parameter Minimum / Maximum Values

WFS1

-200 0 200 400 600 800 1000 1200

Daily Average (2008)Gallons per Minute

Figure 1 . Furnace Line 1 Stack 1 Scrubber Water Flow RatePage 5 of 36


### HL Depth

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Daily Average (2008)Inches

Figure 2 . Furnace Line 1 Hearth Layer Depth



### 2nd Cool

-7.0 -6.0 -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0

Daily Average (2008)Inches of WaterColumn

Figure 3 . Furnace Line 1 2 nd Cooling Hood Pressure



### Hood 22

0 500 1000 1500 2000 2500 3000

Daily Average (2008)Degrees Fahrenheit

Figure 4 . Furnace Line 1 Windbox 22 Hood TemperaturePage 6 of 36

Total Fe

-20.00

0.00 20.00 40.00 60.00 80.00

Daily Average (2008)Percent

Figure 5 . Furnace Line 1 Fired Pellet Total Fe

Udd Temp

0 100 200 300 400 500 600 700

Daily Average (2008)Degrees Fahrenheit

Figure 6 . Furnace Line 1 Updraft Drying Discharge Temperature

CaO

-0.20 0.00 0.20 0.40 0.60 0.80 1.00

Daily Average (2008)Percent

Figure 7 . Furnace Line 1 Fired Pellet CaOPage 7 of 36

Wet Fe++

0.0 5.0 10.0 15.0 20.0 25.0 30.0

Daily Average (2008)Percent

Figure 8 . Furnace Line 1 Concentrate Wet Fe++

Mspeed

0.0 2.0 4.0 6.0 8.0 10.0

Daily Average (2008)Feet per Minute

Figure 9 . Furnace Line 1 Machine Grate Speed

S Gas

-20

0 20 40 60 80 100

Daily Average (2008)Thousand Cubic Feetper Hour

Figure 10 . Furnace Line 1 South Firing Chamber Natural Gas UsagePage 8 of 36

Ven S4

0.0 1.0 2.0 3.0 4.0 5.0

Daily Average (2008)Inches of WaterColumn

Figure 11 . Furnace Line 1 Stack 4 Scrubber Venturi Differential Pressure

Wex P

-5.0 0.0 5.0 10.0 15.0 20.0 25.0

Daily Average (2008)Inches of WaterColumn

Figure 12 . Furnace Line 1 Windbox Exhaust Header Pressure

Furnace Line 2 PEMS Input Parameters

Parameter Description Minimum Value Maximum Value Hearth Layer Depth 2.5 9.0 Machine Grate Speed 3.5 12.0 Updraft Drying Discharge Temperature 400 700 Windbox 18 Hood Temperature 2150 2500

Concentrate Satmagan Fe++ 21.0 22.6 Green Ball Feed Rate 200 550 Stack 2 Scrubber Venturi Di fferential Pressure 0.5 4.9 Cooling Air Fan Header Pressure 10.0 25.0 South Firing Chamber Natural Gas Usage 25 70 Stack 3 Scrubber Water Flow Rate 325 827 Windbox Exhaust Header Pressure 10.0 25.0 Burn Thru Temperature 400 900 North Firing Chamber Natural Gas Usage 25 70 Stack 4 Scrubber Venturi Di fferential Pressure 0.4 4.2 Stack 4 Scrubber Water Flow Rate 284 635 Table 2 . Furnace Line 2 Input Parameter Minimum / Maximum ValuesPage 9 of 36
HL Depth

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Daily Average (2008)Inches

Figure 13 . Furnace Line 2 Hearth Layer Depth

Mspeed

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Daily Average (2008)Feet per Minute

Figure 14 . Furnace Line 2 Machine Grate Speed

Udd T

0 100 200 300 400 500 600 700

Daily Average (2008)Degrees Fahrenheit

Figure 15 . Furnace Line 2 Updraft Drying Discharge TemperaturePage 10 of 36

Hood 18

0 500 1000 1500 2000 2500 3000

Daily Average (2008)Degrees Fahrenheit

Figure 16 . Furnace Line 2 Windbox 18 Hood Temperature

Sat Fe++

-5.0 0.0 5.0 10.0 15.0 20.0 25.0

Daily Average (2008)Percent

Figure 17 . Furnace Line 2 Concentrate Satmagan Fe++

Feed

-100 0 100 200 300 400 500 600

Daily Average (2008)Wet Long Tons perHour

Figure 18 . Furnace Line 2 Green Ball Feed RatePage 11 of 36

Ven S2

0 1 2 3 4 5 6

Daily Average (2008)Inches of WaterColumn

Figure 19 . Furnace Line 2 Stack 2 Scrubber Venturi Differential Pressure

CAF

0.0 5.0 10.0 15.0 20.0 25.0

Daily Average (2008)Inches of WaterColumn

Figure 20 . Furnace Line 2 Cooling Air Fan Header Pressure

S Gas

0 10 20 30 40 50 60 70

Daily Average (2008)Thousand Cubic Feetper Hour

Figure 21 . Furnace Line 2 South Firing Chamber Natural Gas UsagePage 12 of 36



### WFS3

0 200 400 600 800 1000

Daily Average (2008)Gallons per Minute

Figure 22 . Furnace Line 2 Stack 3 Scrubber Water Flow Rate



### Wex P

0.0 5.0 10.0 15.0 20.0 25.0

Daily Average (2008)Inches of WaterColumn

Figure 23 . Furnace Line 2 Windbox Exhaust Header Pressure

B Thru

0 200 400 600 800 1000

Daily Average (2008)Degrees Fahrenheit

Figure 24 . Furnace Line 2 Burn Thru TemperaturePage 13 of 36



### N Gas

0 10 20 30 40 50 60 70

Daily Average (2008)Thousand Cubic Feetper Hour

Figure 25 . Furnace Line 2 North Firing Chamber Natural Gas Usage

Ven S4

0 1 2 3 4 5

Daily Average (2008)Inches of WaterColumn

Figure 26 . Furnace Line 2 Stack 4 Scrubber Venturi Differential Pressure



### WFS4

0 100 200 300 400 500 600 700

Daily Average (2008)Gallons per Minute

Figure 27 . Furnace Line 2 Stack 4 Scrubber Water Flow RatePage 14 of 36 Furnace Line 3 PEMS Input Parameters

Parameter Description Minimum Value Maximum Value Machine Grate Speed 3.5 12.0 2nd Cooling Hood Pressure -7.0 -1.5 Windbox 18 Hood Temperature 2150 2500 Fired Pellet Silica 4.16 4.80 Concentrate Wet Fe++ 21.5 24.1 Green Ball Feed Rate 200 550 South Firing Chamber Natural Gas Usage 25 70 Stack 2 Scrubber Water Flow Rate 0 711 Windbox Exhaust Header Pressure 10.0 25.0 Hearth Layer Depth 2.5 9.0 Machine Discharge Temperature 250 900 Green Ball Moisture 8.8 9.9 Updraft Drying Zone Pressure -6.0 -1.0 Cooling Air Fan Header Pressure 10.0 25.0 Table 3 . Furnace Line 3 Input Parameter Minimum / Maximum Values



### Mspeed

-2.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0

Daily Average (2008)Feet per Minute

Figure 28 . Furnace Line 3 Machine Grate Speed



### 2nd Cool

-8.0 -6.0 -4.0 -2.0 0.0 2.0

Daily Average (2008)Inches of WaterColumn

Figure 29 . Furnace Line 3 2 nd Cooling Hood PressurePage 15 of 36



### Hood 18

0 500 1000 1500 2000 2500 3000

Daily Average (2008)Degrees Fahrenheit

Figure 30 . Furnace Line 3 Windbox 18 Hood Temperature



### Silica

-1.00 0.00 1.00 2.00 3.00 4.00 5.00 6.00

Daily Average (2008)Percent

Figure 31 . Furnace Line 3 Fired Pellet Silica



### Wet Fe++

0.0 5.0 10.0 15.0 20.0 25.0 30.0

Daily Average (2008)Percent

Figure 32 . Furnace Line 3 Concentrate Wet Fe++Page 16 of 36



### Feed

-100 0 100 200 300 400 500 600

Daily Average (2008)Wet Long Tons perHour

Figure 33 . Furnace Line 3 Green Ball Feed Rate



### S Gas

-20

0 20 40 60 80

Daily Average (2008)Thousand Cubic Feetper Hour

Figure 34 . Furnace Line 3 South Firing Chamber Natural Gas Usage



### WFS2

-200 0 200 400 600 800

Daily Average (2008)Gallons per Minute

Figure 35 . Furnace Line 3 Stack 2 Scrubber Water Flow RatePage 17 of 36



### Wex P

0.0 5.0 10.0 15.0 20.0 25.0

Daily Average (2008)Inches of WaterColumn

Figure 36 . Furnace Line 3 Windbox Exhaust Header Pressure



### HL Depth

0.0 2.0 4.0 6.0 8.0 10.0 12.0

Daily Average (2008)Inches

Figure 37 . Furnace Line 3 Hearth Layer Depth



### MD T

0 200 400 600 800 1000

Daily Average (2008)Degrees Fahrenheit

Figure 38 . Furnace Line 3 Machine Discharge TemperaturePage 18 of 36



### GB

-2.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0

Daily Average (2008)Percent

Figure 39 . Furnace Line 3 Green Ball Moisture



### Udd P

-3.0 -2.5 -2.0 -1.5 -1.0 -0.5 0.0

Daily Average (2008)Inches of WaterColumn

Figure 40 . Furnace Line 3 Updraft Drying Zone Pressure



### CAF

0.0 5.0 10.0 15.0 20.0 25.0

Daily Average (2008)Inches of WaterColumn

Figure 41 . Furnace Line 3 Cooling Air Fan Header Pressure



### 4.3 Source-Specific Operating Conditions

HTC produces two types of pellets: standard and high compression. Th e typical split annually is 75 percent standard pellets and 25 percent high compressi on pellets. Limestone is added to each type of pellet to improve the pellet physi cal strength, and in particular, the compression strength. For both pellet types, less than one percent by weight limestone is added to th e green (unfired) pellets, with high compression addition rates double in comparison to th at of standard pellets. When producing highPage 19 of 36 

### compression pellets, the natural gas burner temperat ure set points are incr eased to calcinate the increased limestone quantities that are a dded during a high comp ression production run.

HTC has developed a process contro l strategy to optimize process ai r flow at less than 100 percent production rates. This optimization matches process air flow with production ra te and minimizes excess process air that is not needed. An average of two maintenance shutdowns per furnace line occur each calendar year. The length of a shutdown is typica lly between 10 and 21 days and is dependant on the amount of scheduled maintenance performed. It s hould be noted that no specific operating conditions have been identified that will affect output of the PEMS.

4.4 Ambient Conditions

Ambient conditions and seasonal cha nges will not affect the PEMS, so extrapolation to account for these conditions is not necessary.

4.5 PEMS Principle of Operation

Best subsets regression analysis was performed for each stack with NO x 

### (lb/hr) as the dependent variable and 25 process operating va riables as independent variable s (PEMS input parameters). NO x 

### (lb/hr) for each stack was fitted with 5 selected PEMS input parameters.

In order to further evaluate whet her the identified PEMS input parameters can be used to predict NOx emissions (lb/hr) for each stack, th e residual standard deviation of th e random differences between the actual measured NOx emissions and the regression e quations’ predicted valu es were divided by the mean NOx emissions, with results summarized in Table 4.

Stack Standard Deviation of

Residuals Mean NOx (lb/hr) Quotient (SDR / Mean) Stack Standard Deviation of

Residuals Mean NOx (lb/hr) Quotient (SDR / Mean) Stack Standard Deviation of

Residuals Mean NOx (lb/hr) Quotient (SDR / Mean)
Stack 1 ( SV 021 ) 4.3110 79.2800 0.0544 Stack 1 ( SV 028 ) 7.9400 143.8200 0.0552 Stack 1 ( SV 029 ) 3.0170 43.2590 0.0697

Stack 2 ( SV 022 ) 3.9670 90.8810 0.0437 Stack 2 ( SV 027 ) 5.2260 105.2000 0.0497 Stack 2 ( SV 030 ) 1.9520 59.6990 0.0327

Stack 3 ( SV 023 ) 4.3980 111.3100 0.0395 Stack 3 ( SV 026 ) 4.8300 82.2190 0.0587 Stack 3 ( SV 031 ) 3.2680 96.1930 0.0340

Stack 4 ( SV 024 ) 4.8620 124.0200 0.0392 Stack 4 ( SV 025 ) 6.3250 62.9550 0.1005 Stack 4 ( SV 032 ) 2.9130 118.7300 0.0245 Furnace Line 3 Furnace Line 2 Furnace Line 1

Table 4 . Calculations for Furnace Lines 1, 2, and 3Page 20 of 36 

### Furnace Line 1, Stack 1Page 21 of 36 

### Furnace Line 1, Stack 2Page 22 of 36 

### Furnace Line 1, Stack 3Page 23 of 36 

### Furnace Line 1, Stack 4Page 24 of 36 

### Furnace Line 2, Stack 1Page 25 of 36 

### Furnace Line 2, Stack 2Page 26 of 36 

### Furnace Line 2, Stack 3Page 27 of 36 

### Furnace Line 2, Stack 4Page 28 of 36 

### Furnace Line 3, Stack 1Page 29 of 36 

### Furnace Line 3, Stack 2Page 30 of 36 

### Furnace Line 3, Stack 3Page 31 of 36 

### Furnace Line 3, Stack 4Page 32 of 36 

### Figures 42, 43, and 44 compar e predicted and measured NO x 

### emissions at the furnace level.



## Line 1 NOx (lb/hr): Predicted vs. Measured

R

2 = 0.906

300.00 400.00 500.00

300.00 400.00 500.00

PredictedMeasured

Figure 42 . Furnace 1 NO x Predictions



## Line 2 NOx (lb/hr): Predicted vs. Measured

R

2 

### = 0.8666

300.00 400.00 500.00 600.00

300.00 400.00 500.00 600.00

PredictedMeasured

Figure 43 . Furnace 2 NO x PredictionsPage 33 of 36



## Line 3 NOx (lb/hr): Predicted vs. Measured

R

2 

### = 0.9551

200.00 300.00 400.00

200.00 300.00 400.00

PredictedMeasured

Figure 44 . Furnace 3 NO x Predictions



### 4.6 Data Recorder Scale

Data collected from PEMS input parameters is tran smitted to the Fisher Rosemount Distributed Control System (DCS). DCS readings are transmitted to the OSI Soft PI Historian database, which facilitates storage and retrieval of hist orical data. PI Historian is configured to collect and process all PEMS input parameters, with NOx mass emission rates displayed visually in PI ProcessBook.

4.7 Sensor Location and Repair

All PEMS input sensors are installed in accessible lo cations to facilitate re pairs and replacement when needed. Following replacement of one of more sensor s, a relative accuracy test audit will be conducted. Sensors are calibrated at a freque ncy consistent with manufacturers ’ recommendations or alternatively on an annual basis.

4.8 Sensor Evaluation System

The identified PEMS input parameters are also critic al parameters used to maintain adherence to HTC’s customer-mandated fired pellet quality specifications. Consequently, in stances of sensor failure and/or drift are promptly detected and resolved in order to maintain acceptable pellet quality. In addition, analytical laboratory analyses a llow confirmation of conformance to pellet quality specifications, thereby ensuring that sensor failure or drift has not occurred.

4.9 Parameter Envelope Exceedances

In the event that PEMS input parameter exceedances occur (outside specified operating envelopes), the associated NOx emissions data will not be classified as quality assured.Page 34 of 36


## 5.0 Sample Collection, Preser vation, Storage, and Transport

5.1 Initial Certification / Relative Accuracy Test

As previously mentioned, initial certification of the PEMS will occur using EPA Method 7E. The relative accuracy test for Furnace Lines 1, 2 and 3 will be conducted at low, mid, and high operating levels for the key parameters affecting NOx emissions (please refer to Table 5).

Furnace Line 1 Furnace Line 2 Furnace Line 3 Key PEMS Input Parameter Windbox 22 Hood Temperature Windbox 18 Hood Temperature Windbox 18 Hood Temperature Low Operating Level (Approximate) 2,300 Degrees Fahrenheit 2,300 Degrees Fahrenheit 2,300 Degrees Fahrenheit Mid Operating Level (Approximate) 2,350 Degrees Fahrenheit 2,350 Degrees Fahrenheit 2,350 Degrees Fahrenheit High Operating Level (Approximate) 2,400 Degrees Fahrenheit 2,400 Degrees Fahrenheit 2,400 Degrees Fahrenheit Table 5 . Relative Accuracy Test Operati ng Levels for Key PEMS Input Parameters



### 5.2 Number of Reference Method Tests

Reference method tests will be conducted using a minimu m of nine runs at the low operating level, nine runs at the mid operating level, and nine runs at the high operating level. If more than nine runs are completed at a given operating level, a maximum of three runs may be reject ed as long as the total number of runs at the gi ven operating level is greater than or equal to nine.

5.3 Reference Method Measurement Location

Reference method measurement points are located at least two equivalent stack diameters downstream and one-half an equivalent st ack diameter upstream from th e nearest flow disturbance.

5.4 Traverse Points

Traverse points are selected to en sure representative samples are co llected, with all reference method tests conducted within 3 centimeters of each selected traverse point but no closer than 3 centimeters to the stack wall. Measurement lines are establishe d across the stack passing through the center in the direction of any expected stratif ication. A minimum of three traverse points are located on the measurement line at 16.7, 50.0, and 83.3 percent of the stack inside di ameter. As an alternative for stacks greater than 2.4 meters, the three traverse poi nts may be located on the measurement line at 0.4, 1.2, and 2.0 meters from the stack wall.

5.5 Relative Accuracy Procedure

Relative accuracy tests are performed with a sample traverse of 21 minutes, sa mpling for 7 minutes at each traverse point.Page 35 of 36 

### 5.6 Correlation of Reference Method and PEMS Data

The exact time of day will be recorded for each refere nce method test run, with correlation of reference method and PEMS data to occur for each test run. The paired reference method and PEMS data will be used to calculate the relativ e accuracy for each operating le vel (low, mid, and high).

5.7 Statistical Tests

Using the relative accuracy data taken at the mid operating level, a calculation will be performed to determine if bias exists between the reference met hod and the PEMS. PEMS data is considered biased and must be adjusted if the arithmetic mean is greater than the absolute value of the confidence coefficient. In such cases, a bias factor must be used to correct the PEMS data.

An F-test will be performed for th e relative accuracy paired data at each operating level (low, mid, and high), to determine if the reference method and PEMS data differ for more than might be expected by chance. Calculated F-values must not be greater th an the critical F-value at the 95-percent confidence level for the PEMS to be acceptable.

Finally, correlation analysis will be performed using the relative accuracy paired data at each operating level (low, mid, and high) combined, to determ ine how well the reference method and PEMS data correlate. Calculated r-values must be greater than or equal to 0. 8 for the PEMS to be acceptable.

5.8 Reporting

Results of the relative accuracy and statistical tests will be summarized in tabular form, to be accompanied by all data sheets, calculations, records of PEMS responses. Reports will also include documentation used to establish PEMS input parameter operating envelopes.

5.9 Reevaluation of PEMS after a Failed Test, Change in Operations, or Change in PEMS Input Parameter

Following initial certification, recer tification of the PEMS will occur if:

1. The PEMS fails a quarterly rela tive accuracy test audit; 2. The PEMS fails a annual re lative accuracy test audit; 3. Process changes are made that could result in a significant increase in NO x 

### emissions;

Recertification tests will demonstrat e that the PEMS provides acceptabl e data when operating in new operating ranges or with new PEMS input parameters. Recertification tests will be completed within 60 emission unit operating days or 180 calendar days of occurrence of any one of the three aforementioned triggering events.


## 6.0 Quality Control

6.1 Daily Sensor Evaluation Check

As previously discussed, the identified PEMS input parameters are also critical parameters used to maintain HTC’s fired pellet quality specifications a nd are therefore subject to continuous monitoring. Consequently, instances of sensor fa ilure and/or drift are promptly det ected and resolved. In addition, daily analytical laboratory analyses allow for conf irmation of conformance to fired pellet quality specifications, thereby ensuring that sens or failure or drif t has not occurred.Page 36 of 36 

### 6.2 Quarterly Relative Accuracy Audits

For the first year of PEMS operati on, relative accuracy audits will be performed on a quarterly basis. Relative accuracy audits will consist of at least three 30-minute NOx portable analyzer or reference method determinations, with the average of the three determinations not to differ from the simultaneous PEMS average value by greater than 10 percent.

Should the PEMS pass all three relativ e accuracy audits in the first year of operation, a single mid-year relative accuracy audit may be perfor med in place of the quarterly events . This option may be repeated in subsequent years, but only until the PEMS fails ei ther a subsequent relative accuracy audit or relative accuracy test audit. When such a failure occurs, qua rterly relative accuracy audits will resume in the quarter following failure and continue until the PE MS successfully passes both a year of relative accuracy audits and a subsequent relativ e accuracy test audit.

6.3 Annual Relative Accuracy Test Audit

A minimum nine-run relative accuracy test audit at the mid operating level will be performed on an annual basis (in the quarter in which a relative accuracy audit is not performed). The PEMS relative accuracy must not exceed 10 percent.