P:\Mpls\23 MN\69\2369A60\WorkFiles\Job 002 - NOx reductions from EERP\HTC BART NOx Reduction Memo 2007-12-10 FINAL.doc 

Memorandum

To: Andrea Hayden – Hibbing Taconite Company (HTC) 

From: Erik Boleman 

Subject: BART NOx Emission Reduction Analysis 

Date: December 10, 2007 

Project: 23/69-A60-002

c: Beth Havlik – Barr Engineering 

Andrew Skoglund – Barr Engineering

This memo summarizes the analysis which was conducted for the NOx emission reductions which 

occurred due to the energy efficiency projects for the three indurating furnaces at your facility. This 

document presents the following information: 

• Stack test data, 

• Emission reduction calculations, 

• Stack parameters (flow and temperature), 

• Visibility modeling overview, and 

• Summary of visibility modeling results. 

Stack Test Data

Stack tests were conducted on each indurating furnace before and after the energy efficiency projects.

The raw data are presented is tables 1, 2, and 3. 

Emission Reduction Calculations

Barr has calculated the NOx emissions based on the stack test data presented in tables 1, 2, and 3. We 

determined the NOx emission reductions in units of pounds of NOx per dry long ton of pellets produced 

(lb/dlt). It is important to note that the MPCA modeling protocol modeled each furnace as a single stack 

rather than four separate stacks. Therefore, we calculated an average emission reduction for each 

furnace, applied the emission reduction to the maximum emission rate from the baseline conditions as 

presented in the BART report, and calculated new emission rates for the visibility impacts modeling of

the current operation. 

The emission calculations are presented in table 4, 5, and 6. A summary is provided in table 7. 

Stack Parameters (Flow and Temperature)

Air dispersion modeling of the NOx emission reductions from the energy efficiency projects was 

conducted using two separate scenarios for stack parameters. The air dispersion modeling for Scenario A 

was conducted using the same stack parameters as the baseline conditions. 

However, the air dispersion modeling for Scenario B uses new stack parameters which are based on the 

recent stack test results, because the stacks’ temperature and flow appear to have changed due to the 

energy efficiency projects. As previously stated, the MPCA modeling protocol modeled each furnace as 

Barr Engineering Company 

332 West Superior Street, Suite 600 • Duluth, MN 55802 

Phone: 218-727-5218 • Fax: 218-727-6450 • www.barr.com An EEO Employer

Minneapolis, MN • Hibbing, MN • Duluth, MN • Ann Arbor, MI • Jefferson City, MO 
To: Andrea Hayden – HTC 

From: Erik Boleman – Barr Engineering 

Subject BART NOx Emission Reduction Analysis 

Date: December 10, 2007 

Page: 2 of 2

a single stack rather than four separate stacks. Therefore, Barr calculated the Scenario B stack flow rates 

by calculating the average flow rate from the four stacks. The Scenario B stack temperatures were 

calculated as the maximum temperature of the four stacks, which appears to be consistent with the 

baseline temperature as selected by MPCA. 

The stack flow rate and temperature calculations and comparisons are presented in Table 8. 

Visibility Modeling Overview

Two post-BART emissions scenarios were modeled. The additional modeling followed the same 

procedures described in Appendices B and C of the original report. 

 

Predicted Stack Parameters and 24-Hour Maximum Emission Rates 

Pursuant to guidance from MPCA and to be consistent with use of the highest daily emissions for 

pre-BART visibility impacts, the post-BART emissions to be used for the visibility impacts analysis 

reflect a maximum 24-hour average basis. Table 9 presents the post-BART model input parameters. 

Modeled Results 

Visibility impairment was modeled using the meteorological data for the years 2002, 2003 and 2004 

for the predicted post-BART emission scenario(s). Results for the 98th percentile and number of days 

above 0.5 dV at Boundary Waters Canoe Area Wilderness (BWCA) and Voyageurs National Park 

(VNP) are included in Table 10. 

Summary of Visibility Modeling Results

Using the modeling procedure as described above, the energy efficiency projects resulted in visibility

improvement compared to the baseline (pre-BART) operating conditions as follows: 

• Modeled 98th Percentile: Baseline value was 1.609 deciview (dV). Scenario A (baseline 

stack parameters) resulted in a visibility improvement on the 98th percentile day of 

approximately 0.690 dV or 43%. Scenario B (stack parameters based on the latest stack test) 

resulted in a visibility improvement on the 98th percentile day of approximately 1.104 dV or 

69%. 

• Number of Days Over 0.5 dV: Baseline value was 189 days. Scenario A (baseline stack 

parameters) resulted in a decrease the number of days over 0.5 dV of 106 days or 56%. 

Scenario B (stack parameters based on the latest stack test) resulted in a decrease in the 

number of days over 0.5 dV of 168 days or 89%. 
Table 1: HTC Stack Test Data - Line 1 (EU 020)

GE Report M22A0346B

Vent IDRun Num 1 2 3 Ave 1 2 3 Ave 1 2 3 Ave 1 

Date 5/1/2007 5/1/2007 5/1/2007 5/1/2007 5/1/2007 5/1/2007 5/1/2007 5/1/2007 5/1/2007 5/Temp (°F) 93 93 95 93.7 95 93 94 94.0 102 102 102 102.0 Moisture (Bws) 0.04 0.04 0.04 0.040 0.04 0.04 0.05 0.043 0.09 0.08 0.09 0.087 Volume Flow Rate (ACFM) 194,581 194,762 194,855 194,733 193,671 187,146 190,177 190,331 217,628 217,001 218,241 217,623 18

Nox Conc (ppmd) 32.6 31.2 35.8 33.2 58.2 57.5 65.8 60.5 92.4 96.3 93.4 94.0 Nox Emission (lb/hr) 41.37 39.54 45.41 42.1 73 69.9 80.18 74.4 85.17 88.9 86.21 86.8 

Production (dlt/hr) 370 373 371 371.3 371 372 372 371.7 371 371 365 369.0 

MMBtu/hr 78 73 88 79.7 78 72 100 83.3 82 86 104 90.7 

Barr Project 2369951TAK

Vent IDRun Num 1 2 3 Ave 1 2 3 Ave 1 2 3 Ave 1 

Date 6/14/2005 6/14/2005 6/14/2005 6/15/2005 6/15/2005 6/15/2005 6/15/2005 6/16/2005 6/16/2005 6/16Temp (°F) 96 96 96 96.0 99 99 101 99.7 106 105 106 105.7 Moisture (Bws) 0.061 0.061 0.061 0.061 0.063 0.065 0.069 0.066 0.082 0.079 0.079 0.080 Volume Flow Rate (ACFM) 202,000 202,000 204,000 202,667 201,000 201,000 201,000 201,000 189,000 187,000 181,000 185,667 18

Nox Conc (ppmd) 71 69 66 68.7 98 95 101 98.0 159 148 156 154.3 Nox Emission (lb/hr) 85 83 81 83.0 118 114 120 117.3 173 162 165 166.7 Production (dlt/hr) 347 344 341 344.0 348 350 352 350.0 350 351 351 350.7 

MMBtu/hr 127 127 124 126.0 127 127 128 127.3 128 127 127 127.3 

SV 021 SV 022 SV 023 

SV 021 SV 022 SV 023 

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Tab 1 - Line 1 DATA 
Table 2: HTC Stack Test Data - Line 2 (EU 021)

GE Report M22A0346B

Vent IDRun Num 1 2 3 Ave 1 2 3 Ave 1 2 3 Ave 1 Date 5/2/2007 5/2/2007 5/2/2007 5/2/2007 5/2/2007 5/2/2007 5/2/2007 5/2/2007 5/2/2007 5/2Temp (°F) 106 107 110 107.7 103 101 102 102.0 96 96 97 96.3 Moisture (Bws) 0.07 0.07 0.08 0.073 0.06 0.07 0.06 0.063 0.07 0.07 0.07 0.070 Volume Flow Rate (ACFM) 172,058 170,048 169,343 170,483 180,846 178,533 189,663 183,014 184,879 183,993 182,729 183,867 19

Nox Conc (ppmd) 104.2 109.4 114.3 109.3 105.3 104.7 100.5 103.5 67.8 67.8 68.7 68.1 Nox Emission (lb/hr) 110.77 115.31 118.4 114.8 119.84 117.57 120.58 119.3 79.44 79.18 79.43 79.4 

Production (dlt/hr) 344 362 359 355.0 363 363 358 361.3 364 366 375 368.3 

MMBtu/hr 96 101 103 100.0 104 104 104 104.0 104 104 106 104.7 

Barr Project 2369870TAK

Vent IDRun Num 1 2 3 Ave 1 2 3 Ave 1 2 3 Ave 1 Date 6/23/2004 6/23/2004 6/23/2004 6/23/2004 6/23/2004 6/23/2004 6/22/2004 6/23/2004 6/23/2004 6/22Temp (°F) 117 116 116 116.3 109 110 111 110.0 100 99 99 99.3 

Moisture (Bws) 0.096 0.089 0.094 0.093 0.079 0.078 0.078 0.078 0.068 0.052 0.054 0.058 

Volume Flow Rate (ACFM) 191,000 190,000 194,000 191,667 192,000 194,000 193,000 193,000 204,000 205,000 206,000 205,000 20

Nox Conc (ppmd) 139 134 136 136.3 123 117 117 119.0 84 83 85 84.0 

Nox Emission (lb/hr) 148 143 148 146.3 136 133 130 133.0 102 103 106 103.7 

Production (dlt/hr) 367 370 368 368.3 368 369 365 367.3 366 363 364 364.3 

MMBtu/hr 106 111 108 108.3 106 106 105 105.7 110 108 108 108.7 

SV 025 SV 026 SV 027 SV 025 SV 026 SV 027 

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Tab 2 - Line 2 DATA 
Table 3: HTC Stack Test Data - Line 3 (EU 022)

GE Report M22A0346B

Vent IDRun Num 1 2 3 Ave 1 2 3 Ave 1 2 3 Ave 1 Date 5/8/2007 5/8/2007 5/8/2007 5/8/2007 5/8/2007 5/8/2007 5/7/2008 5/8/2007 5/8/2007 5/7Temp (°F) 97 98 97 97.3 101 102 103 102.0 115 111 113 113.0 Moisture (Bws) 0.08 0.1 0.07 0.083 0.08 0.08 0.09 0.083 0.07 0.06 0.08 0.070 Volume Flow Rate (ACFM) 202,928 207,393 208,374 206,232 207,291 207,604 201,264 205,386 194,503 199,996 188,072 194,190 20

Nox Conc (ppmd) 33.8 32.4 30.8 32.3 46.8 47 48.7 47.5 69.4 68.5 68.6 68.8 Nox Emission (lb/hr) 42.47 40.63 39.85 41.0 59.31 59.49 59.48 59.4 82.08 83.93 83.1 83.0 Production (dlt/hr) 373 378 370 373.7 373 360 375 369.3 377 372 361 370.0 

MMBtu/hr 104 104 104 104.0 104 104 104 104.0 102 108 108 106.0 

Barr Project 2369951TAK

Vent IDRun Num 1 2 3 Ave 1 2 3 Ave 1 2 3 Ave 1 Date 6/22/2005 6/23/2005 6/23/2005 6/21/2005 6/21/2005 6/21/2005 6/21/2005 6/21/2005 6/21/2005 6/20Temp (°F) 97 101 103 100.3 103 103 104 103.3 115 114 116 115.0 

Moisture (Bws) 0.062 0.064 0.069 0.065 0.07 0.074 0.065 0.070 0.09 0.078 0.104 0.091 

Volume Flow Rate (ACFM) 206,000 209,000 208,000 207,667 207,000 212,000 211,000 210,000 209,000 209,000 217,000 211,667 19

Nox Conc (ppmd) 68 67 61 65.3 86 87 88 87.0 138 137 141 138.7 

Nox Emission (lb/hr) 85 83 75 81.0 105 109 111 108.3 164 165 171 166.7 

Production (dlt/hr) 383 381 377 380.3 380 381 381 380.7 378 373 381 377.3 

MMBtu/hr 119 121 119 119.7 116 117 115 116.0 116 115 115 115.3 

SV 029 SV 030 SV 031 SV 029 SV 030 SV 031 

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Tab 3 - Line 3 DATA 
Table 4: HTC NOx Emission Reduction Calculations - Line 1 (EU 020)

SV 021 SV 022 SV 023 SV 024 Total

Temperature (*F)

Baseline 96.0 99.7 105.7 110.3 ---

Post EERP 93.7 94.0 102.0 114.3 ---

Change -2.3 -5.7 -3.7 4.0 NA

-2.4% -5.7% -3.5% 3.6% NA

Stack Flow Rate (acfm)

Baseline 202,666.7 201,000.0 185,666.7 182,333.3 ---

Post EERP 194,732.7 190,331.3 217,623.3 184,707.0 ---

Change -7,934.0 -10,668.7 31,956.6 2,373.7 NA

-3.9% -5.3% 17.2% 1.3% NA

Production (dlt/hr)

Baseline 344.0 350.0 350.7 351.3 ---

Post EERP 371.3 371.7 369.0 362.7 ---

Change 27.3 21.7 18.3 11.4 NA

7.9% 6.2% 5.2% 3.2% NA

Natural Gas (MMBtu/hr)

Baseline 126.0 127.3 127.3 125.3 ---

Post EERP 79.7 83.3 90.7 94.3 ---

Change NA NA NA NA NA

NA NA NA NA NA

NOx (lb/hr)

Baseline 83.0 117.3 166.7 191.3 ---

Post EERP 42.1 74.4 86.8 113.0 ---

Change NA NA NA NA NA

NA NA NA NA NA

Natural Gas (MMBtu/dlt)

Baseline 0.366 0.364 0.363 0.357 1.450

Post EERP 0.215 0.224 0.246 0.260 0.945

Change -0.151 -0.140 -0.117 -0.097 -0.505

-41.3% -38.5% -32.2% -27.2% -34.8%

NOx (lb/dlt)

Baseline 0.241 0.335 0.475 0.545 1.596

Post EERP 0.113 0.200 0.235 0.312 0.860

Change -0.128 -0.135 -0.240 -0.233 -0.736

-53.1% -40.3% -50.5% -42.8% -46.1%

Reductions for Regional Haze Modeling

NOx Emission Reduction (%) -46.1%

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Tab 4 - Line 1 CALCS 12/11/2007
Table 5: HTC NOx Emission Reduction Calculations - Line 2 (EU 021)

SV 025 SV 026 SV 027 SV 028 Total

Temperature (*F)

Baseline 116.3 110.0 99.3 96.7 ---

Post EERP 107.7 102.0 96.3 90.3 ---

Change -8.6 -8.0 -3.0 -6.4 NA

-7.4% -7.3% -3.0% -6.6% NA

Stack Flow Rate (acfm)

Baseline 191,666.7 193,000.0 205,000.0 205,333.3 ---

Post EERP 170,483.0 183,014.0 183,867.0 194,489.0 ---

Change -21,183.7 -9,986.0 -21,133.0 -10,844.3 NA

-11.1% -5.2% -10.3% -5.3% NA

Production (dlt/hr)

Baseline 368.3 367.3 364.3 365.0 ---

Post EERP 355.0 361.3 368.3 368.0 ---

Change -13.3 -6.0 4.0 3.0 NA

-3.6% -1.6% 1.1% 0.8% NA

Natural Gas (MMBtu/hr)

Baseline 108.3 105.7 108.7 109.0 ---

Post EERP 100.0 104.0 104.7 103.3 ---

Change NA NA NA NA NA

NA NA NA NA NA

NOx (lb/hr)

Baseline 146.3 133.0 103.7 80.0 ---

Post EERP 114.8 119.3 79.4 66.3 ---

Change NA NA NA NA NA

NA NA NA NA NA

Natural Gas (MMBtu/dlt)

Baseline 0.294 0.288 0.298 0.299 1.179

Post EERP 0.282 0.288 0.284 0.281 1.135

Change -0.012 0.000 -0.014 -0.018 -0.044

-4.1% 0.0% -4.7% -6.0% -3.7%

NOx (lb/dlt)

Baseline 0.397 0.362 0.285 0.219 1.263

Post EERP 0.323 0.330 0.216 0.180 1.049

Change -0.074 -0.032 -0.069 -0.039 -0.214

-18.6% -8.8% -24.2% -17.8% -16.9%

Reductions for Regional Haze Modeling

NOx Emission Reduction (%) -16.9%

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Tab 5 - Line 2 CALCS 12/11/2007
Table 6: HTC NOx Emission Reduction Calculations - Line 3 (EU 022)

SV 029 SV 030 SV 031 SV 032 Total

Temperature (*F)

Baseline 100.3 103.3 115.0 120.0 ---

Post EERP 97.3 102.0 113.0 122.0 ---

Change -3.0 -1.3 -2.0 2.0 NA

-3.0% -1.3% -1.7% 1.7% NA

Stack Flow Rate (acfm)

Baseline 207,666.7 210,000.0 211,666.7 197,000.0 ---

Post EERP 206,231.7 205,386.3 194,190.3 201,474.7 ---

Change -1,435.0 -4,613.7 -17,476.4 4,474.7 NA

-0.7% -2.2% -8.3% 2.3% NA

Production (dlt/hr)

Baseline 380.3 380.7 377.3 374.3 ---

Post EERP 373.7 369.3 370.0 376.0 ---

Change -6.6 -11.4 -7.3 1.7 NA

-1.7% -3.0% -1.9% 0.5% NA

Natural Gas (MMBtu/hr)

Baseline 119.7 116.0 115.3 116.3 ---

Post EERP 104.0 104.0 106.0 103.0 ---

Change NA NA NA NA NA

NA NA NA NA NA

NOx (lb/hr)

Baseline 81.0 108.3 166.7 170.0 ---

Post EERP 41.0 59.4 83.0 121.0 ---

Change NA NA NA NA NA

NA NA NA NA NA

Natural Gas (MMBtu/dlt)

Baseline 0.315 0.305 0.306 0.311 1.237

Post EERP 0.278 0.282 0.286 0.274 1.120

Change -0.037 -0.023 -0.020 -0.037 -0.117

-11.7% -7.5% -6.5% -11.9% -9.5%

NOx (lb/dlt)

Baseline 0.213 0.284 0.442 0.454 1.393

Post EERP 0.110 0.161 0.224 0.322 0.817

Change -0.103 -0.123 -0.218 -0.132 -0.576

-48.4% -43.3% -49.3% -29.1% -41.3%

Reductions for Regional Haze Modeling

NOx Emission Reduction (%) -41.3%

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Tab 6 - Line 3 CALCS 12/11/2007
Table 7: HTC NOx Emission Reduction Summary

Line 1

EU 020

Line 2

EU 021

Line 3

EU 021

NOx (lb/dlt)

Baseline 1.596 1.263 1.393

Post EERP 0.860 1.049 0.817

Change -0.736 -0.214 -0.576

-46.1% -16.9% -41.3%

Reductions for Regional Haze Modeling

NOx Emission Reduction (%) -46.1% -16.9% -41.3%

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FINAL

Tab 7 - NOx Summary 12/11/2007
Table 8: HTC Stack Flow Rate and Temperature Comparisons

Line 1 - EU 020

Post EERP Flow SV 021 SV 022 SV 023 SV 024 Scenario B* 

Stack Flow (acfm) 194,732.7 190,331.3 217,623.3 184,707.0

Stack Diameter (inches) 104.5 104.5 104.5 104.5

Stack Area (ft^2) 59.5 59.5 59.5 59.5

Stack Velocity (ft/min) 3,271.1 3,197.2 3,655.7 3,102.7

Stack Velocity (m/s) 16.6 16.2 18.6 15.8 16.8 

Stack Temp (*F)

Post EERP 93.7 94.0 102.0 114.3 114 

Line 2 - EU 021

Post EERP Flow SV 025 SV 026 SV 027 SV 028 Scenario B* 

Stack Flow (acfm) 170,483.0 183,014.0 183,867.0 194,489.0

Stack Diameter (inches) 104.5 104.5 104.5 104.5

Stack Area (ft^2) 59.5 59.5 59.5 59.5

Stack Velocity (ft/min) 2,863.8 3,074.3 3,088.6 3,267.0

Stack Velocity (m/s) 14.5 15.6 15.7 16.6 15.6 

Stack Temp (*F)

Post EERP 107.7 102.0 96.3 90.3 108 

Line 3 - EU 022

Post EERP Flow SV 029 SV 030 SV 031 SV 032 Scenario B* 

Stack Flow (acfm) 206,231.7 205,386.3 194,190.3 201,474.7

Stack Diameter (inches) 104.5 104.5 104.5 104.5

Stack Area (ft^2) 59.5 59.5 59.5 59.5

Stack Velocity (ft/min) 3,464.3 3,450.1 3,262.0 3,384.4

Stack Velocity (m/s) 17.6 17.5 16.6 17.2 17.2 

Stack Temp (*F)

Post EERP 97.3 102.0 113.0 122.0 122 

* Scenario B: Stack Flow = average of 4 stacks; Stack Temperature = maximum of 4 stacks (appears to be consistent with baseline temperature selection)

** Scenario 0 + A: Stack Flow and Stack Temperature as modeled as baseline conditions in 2006 BART Report

P:\Mpls\23 MN\69\2369A60\WorkFiles\Job 002 - NOx reductions from EERP\HTC NOx Reduction Calcs 2007-12-06 FINALTab 8 - Stack Flow + Temp 
SO2 NOx % reduct.

Max 24-

lb/day 

0 Base 

(Wet PM Scrubbers)

Base 

(Max = gas)

EU 020 Line 1 16.11 322 --- 720 EU 021 Line 2 16.59 322 --- 912 EU 022 Line 3 17.26 322 --- 1,032 

A Base 

(Wet PM Scrubbers)

Energy Efficiency 

Projects

(no stack changes)

EU 020 Line 1 Current operations -46.1% 16.11 322 --- 720 EU 021 Line 2 Current operations -16.9% 16.59 322 --- 912 EU 022 Line 3 Current operations -41.3% 17.26 322 --- 1,032 

B Base 

(Wet PM Scrubbers)

Energy Efficiency 

Projects

(stack test temp + flow)

EU 020 Line 1 Current operations -46.1% 16.80 319 --- 720 EU 021 Line 2 Current operations -16.9% 15.61 315 --- 912 EU 022 Line 3 Current operations -41.3% 17.22 323 --- 1,032 

EU #

HTC Post-BART Modeling Scenarios Predicticted Stack Parameters and 24-hour Maximum Emission Rates

Table 9:

Scenario

Scenario Control Technology

Production Line

Exit Temp

(Kelvin)

Stack Velocity

(m/s)

Stack Parameters Modeling 

SO2 

P:\Mpls\23 MN\69\2369A60\WorkFiles\Job 002 - NOx reductions from EERP\HTC NOx Reduction Calcs 2007-12-06 FINALTab 9 - Modeling Scenarios 
SO2 NOx 

Class I Area 

with greatest 

impact*

Modeled 98%ile 

∆DV

# days over 

0.5 ∆DV

Modeled 98%ile 

∆DV

# days over 

0.5 ∆DV

Modeled 98%ile 

∆DV

0 Base 

(Wet PM Scrubbers)

Base 

(Max = gas)

BWCA 1.634** 73 1.638 64 1.604 

EU 020 Line 1EU 021 Line 2EU 022 Line 3

A Base 

(Wet PM Scrubbers)

Energy Efficiency 

Projects

(no stack changes)

BWCA 0.926** 32 0.940 31 0.899 

EU 020 Line 1 Current operations -46.1%EU 021 Line 2 Current operations -16.9%EU 022 Line 3 Current operations -41.3%

B Base 

(Wet PM Scrubbers)

Energy Efficiency 

Projects

(stack test temp + flow)

BWCA 0.540** 10 0.533 9 0.425 

EU 020 Line 1 Current operations -46.1%EU 021 Line 2 Current operations -16.9%EU 022 Line 3 Current operations -41.3%

* Modeled values are from BWCA unless noted as Voyageurs in comments** Modeled values are from Voyageurs National Park

HTC Post-BART Modeling Scenarios Visibility Modeling Results

2003 2004

Modeling Results

2002

EU #

Table 10:

Scenario

Scenario Control Technology

Production Line

P:\Mpls\23 MN\69\2369A60\WorkFiles\Job 002 - NOx reductions from EERP\HTC NOx Reduction Calcs 2007-12-06 FINALTab 10 - Modeling Results