1. 2013 AEP BRO Forum 7-30-13 1 INCREASING MILL CAPACITY AND PERFORMANCE Wide Track Grinding Elements Classifier Upgrades AEP BRO FORUM July 30, 2013

2. 2013 AEP BRO Forum 7-30-13 2 NEED FOR INCREASED MILL CAPACITY MEETING THIS NEED PERFORMANCE Presentation Objectives

3. 2013 AEP BRO Forum 7-30-13 3 Where It Started International Customer(2009) -B&W89 mills were “just sufficient” to operate at peak unit output. -No spare mill capacity – for planned or unplanned maintenance. -No fuel flexibility – could not expand to use a broader range of coal. THE PROBLEM - LIMITED CAPACITY

4. 2013 AEP BRO Forum 7-30-13 4 Mill Evaluation This customer requested a list of mill upgrades for: Reduction of unburned carbon in fly ash. Higher capacity (throughput) for lower quality coals. Increased wear life between overhauls.

5. 2013 AEP BRO Forum 7-30-13 5 The Solution 1.Upgrade grinding elements with new, larger and modified-profile parts. 2.Increase the grinding track diameter. 3.Addition of DSVS® rotating classifier. 4.Addition of auto-spring loading system. 5.Addition of low pressure drop rotating throat assemblies.

6. 2013 AEP BRO Forum 7-30-13 6 Physical Features Maintains B&W- designed asymmetrical low profile theory. Larger diameter and larger width. Fits within existing ring seat – minor to no modifications to the pulverizer grinding zone. Extending the Capabilities of Existing Equipment B&W 65” WEARESISTOR® LOW PROFILE B&W 67” ASYMMETRIC LOW PROFILE

7. 2013 AEP BRO Forum 7-30-13 7 Benefits Greater Grinding Surface Area Increases Capacity (projected ~ 5%) More Material in Wear Areas Approximately 30% Low Profile Design Power Savings ~ 10% With Minimal Mill Changes Fits within existing ring seat and pressure frame Reuse of existing wheels B&W 65” WEARESISTOR® LOW PROFILE B&W 67” ASYMMETRIC LOW PROFILE

8. 2013 AEP BRO Forum 7-30-13 8 Outcome From Initial Installation Table 1. Coal Fineness Analysis at Mill 1A (Before upgrade) Parameters Value Coal flow (lb/hr)103,600 Mill pressure drop (in. wc)15.5 Mill outlet temperature (°F)144 Primary air flow (lb/hr)273,860 Analytical values - ASTM D197 <50 mesh/300 um (%)<100 mesh/150 um (%) <200 mesh/74 um (%) Coal pipe No. 184.659.637 Coal pipe No. 279.854.435 Coal pipe No. 378.25234 Coal pipe No. 485.268.450 Coal pipe No. 586.468.646.6 Coal pipe No. 687.873.852 Coal pipe No. 78768.444.2 Coal pipe No. 8 84.6 64 39.8 Table 2. Mill Performance Summary for 12 July (Contract guarantee tests) Guarantee12 July AM 12 July PM Raw coal total moisture (%)810.319.18 Raw coal surface moisture (%)2.83.83.2 Raw coal HGI404648 Guaranteed capacity at 40 HGI (lb/hr)95,890 Corrected capacity for 46 HGI and feeder calibration110,259 Actual test coal flow (lb/hr) 110,471 Guaranteed 200/50 mesh fineness at 95,890 lb/hr and 40 HGI70/99 Actual 200/50 mesh fineness (%) 70.24/99.98 72.38/99.98 B&W’s original assessment was that the upgrades would increase pulverizer capacity by approximately 10%. Other benefits included lower power consumption, lower unburned carbon and greater fuel flexibility.

9. 2013 AEP BRO Forum 7-30-13 9 Outcome For Initial Installation

10. 2013 AEP BRO Forum 7-30-13 10 Classifier Upgrades 105/112 Louver Conversion (Stationary High-Spin Classifier) Applicable to: Amos Cardinal (have done one mill) Gavin Rockport Mountaineer Muskingum River, Flint Creek and Welsh already have the 112 classifier but not the new discharge section. Original ClassifierClassifier Conversion Coal Flow, lbs/hr122,500122,800 Mill Differential, in.w.c.15.512.1 50 Mesh Fineness, %99.9 100 Mesh Fineness, %89.792.7 200 Mesh Fineness, %61.767.5 Results at Zimmer – Mills equipped with LPD rotating throats and B&W current discharge section.

11. 2013 AEP BRO Forum 7-30-13 11 FW / BW89 Classifier Replacement (Stationary High-Spin Classifier) Applicable to: Amos 1&2 Big Sandy Mitchell Original Classifier (Avg. 3 tests)Classifier Conversion 50 Mesh Fineness, %96.499.9 100 Mesh Fineness, %90.8699.4 140 Mesh Fineness, %83.7696.4 200 Mesh Fineness, %7687.9 This retrofit was done where fineness was an issue on FW mills and also on conversion mills still running the original FW classifier. (Coal flow constant at 100,000 lbs/hr)

12. 2013 AEP BRO Forum 7-30-13 12 FW / BW89 Classifier Replacement, cont’d Applicable to: Amos 1&2 Big Sandy Mitchell A recent retrofit – where fineness was an issue on FW conversion mills still running the original FW classifier. 50 MESH Avg. DATE:Conduit #1Conduit #2Conduit #3Conduit #4 2/2/2012 94.4 95.496.895.3 2/7/2012 96.897.296.297.697.0 3/5/2012 96.296.897.097.696.9 6/11/2013 100.099.8100.099.899.9 100 MESH DATE:Conduit #1Conduit #2Conduit #3Conduit #4 2/2/2012 87.287.089.891.488.9 2/7/2012 91.292.089.893.891.7 3/5/2012 90.892.291.493.492.0 6/11/2013 99.499.099.699.4 140 MESH DATE:Conduit #1Conduit #2Conduit #3Conduit #4 2/2/2012 78.878.283.283.480.9 2/7/2012 84.285.883.088.485.4 3/5/2012 84.285.083.687.085.0 6/11/2013 96.494.697.2 96.4 200 MESH DATE:Conduit #1Conduit #2Conduit #3Conduit #4 2/2/2012 67.066.873.483.472.7 2/7/2012 73.876.873.688.478.2 3/5/2012 74.274.472.487.077.0 6/11/2013 87.684.490.089.487.9 MOISTURE DATE:Conduit #1Conduit #2Conduit #3Conduit #4 2/2/201219.2%19.3%19.2%19.8% 19.38% 2/7/201220.8%20.2% 20.35% 3/5/201219.4%18.7%18.6%18.4% 18.78% 6/11/201316.9% 16.6%16.7% 16.78% (Coal flow constant at 100,000 lbs/hr)

13. 2013 AEP BRO Forum 7-30-13 13 FW / BW89 Classifier Replacement, cont’d (Coal flow constant at 100,000 lbs/hr)

14. 2013 AEP BRO Forum 7-30-13 14 Sharing Technology – What Has Been Done Within AEP GAVIN Installed wide track prototype grinding elements on Mill 1-7 in October 2009. Low profile conversion completed as well. Limited performance testing has been done. CARDINAL Installation of wide track grinding elements is planned for Fall 2013.

15. 2013 AEP BRO Forum 7-30-13 15 What We Have Found So Far At Gavin: Date4/23/088/15/0911/18/091/21/10 Time8;47 Mill1-7 Coal flow pph90,000 100,00090,000 Pitot dP mano3.22.7 2.5 Pulv dP CR Pulv dP mano16.015.014.0 Mill Outlet Temp150151141147 Motor amps90945960 Lean/Rich34333641 PA damper pos.50262530 Hot air dmpr pos3098100 Temp’g dmpr pos100446540 Calc rec. wt/pipe277g Pipe A samp. Wt.262g255.2g354g278.5g Pipe B samp wt.284g Pipe C samp Wt.379g Pipe D samp Wt.311g Tot Wt./4xCalc120% PC fineness %/5099.8 98.699.4 %/10094.094.484.490.5 %/20067.469.154.462.9 Previous parts Wide tires and segments testerPlant B&WPlant Difference in plant data before and after is not as significant as difference between B&W testing and plant testing results.

16. 2013 AEP BRO Forum 7-30-13 16 What We Have Found So Far At Gavin: Date11/18/09 Time10:1013:0014:40 Mill Coal flow pph100,000120,000150,000 Pitot dP CR Pitot dP mano2.73.53.9 Pulv dP mano14.016.6N/A Mill Outlet Temp141140139 Motor amps596168 Lean/Rich363235 PA damper pos.2535100 Hot air dmpr pos100 Temp’g dmpr pos655544 Calc rec. wt/pipe277332416 Pipe A samp. Wt.354370424 Pipe B samp wt.284270354 Pipe C samp Wt.379322404 Pipe D samp Wt.311359352 Tot Wt./4xCalc120%99.5%92% PC fineness %/5098.698.096.9 %/10084.479.888.0 %/20054.449.149 Wide tires and segments testerB&W Much higher coal flows achieved. Minor degradation of fineness likely by higher air flow and/or lower recovery rate.

17. 2013 AEP BRO Forum 7-30-13 17 Modifications To Improve Mill Performance Grinding Elements – Wear life and power consumption/capacity DSVS Rotating Classifiers – Fineness and capacity Auto-Spring Loading System – Fineness and wear life Low Pressure Drop Rotating Throat – Fineness and erosion

18. 2013 AEP BRO Forum 7-30-13 18 Assessing Plant Needs Many mill upgrades / modifications available in the marketplace. Some have large capital outlay; is return relative to the investment? Some have modest returns for minimal outlay. Cost / benefit analysis is critical to making a decision.

19. 2013 AEP BRO Forum 7-30-13 19 Questions?