Document 2jvMyMgeemxr8Zy8N3Kr5EnnN

Minnkota Power Cooperative, Inc Milton R Young Station Unit 2 A14559 010 Rev No Final June 23. 2023 IbITBtu to 10.9 Ib/TBtu (Hg content varied from 0.05 to O.25 ppm, and averaged O.112 O.O14 ppm on a dry coal basis). As such, units firing lignite coal with lower heating values have to accommodate frequently changing coal quality and require a wide range of flexibility to account for instances of firing hij-lig seams of coal to consistently achieve adequate operating margin below theequired Hg emission limit.3 The variability of the projected lignite coal quality received from the Center Mine from 2O25 through 2O36 is shown in Table 3-1. Table 3-1 -- Center Mine Ultimate Coal Analyses (As -Received) Fuel Parameter Carbon Hydrogen (fuel-based) Nitrogen Sulfur Oxygen (by difference) Moisture Ash Higher Heating Value (HHV) Mercury Content Estimated Hg Emission Units wt.% wt.% wt.% wt.% wt.% wt.% wt.% Btu/lb ppm lb/TBtu Average 40.53 2.78 0.30 0.86 9 97 38.83 6.73 6,625 0 091 8 41 Minimum 39.73 2.71 0.26 0.68 9.47 38.53 6.00 6,489 0 053 4.79 Maximum 41.24 2.82 0.34 1.07 10.83 39.25 7.87 6,739 0 184 17.42 3.1.3.Hg Removal with ESPs For ACI on ESP applications, 80% of Hg capture occurs in the flue gas, and 2O% occurs on the dust within the ESP (as the dust on the collecting plates are consistently removed as part of the process). Therefore, for ESP applications, achieving ideal mixing and residence time to allow for elementalHg to oxidize to ionic Hg and for Hg to be adsorbed on the carbon particles (of the PAC or unburned carbon content in the fly ash) is critical. It should be noted thatthis ratio is the exact opposite for baghouse applications, i.e. 2O% capture induct and 80% capture on the dust of the filter cake accumulated in the baghouse. For this reason, fabric filters can result in extremely highHg capture and can improve the capture with any 1g sorbent. 3.1.4.Existing System Limitations Documented evidence of a lignite unit achieving 1.2 lb/TBtuor below has not been found/reviewed at the time of this report. Minnkota personnel recently completed shor-tterm parametric testing in May 2023 to determine the Hg emissions that could be achieved by maximizing the existing fuel additive and PAC injection. Even when maximizing the fuel additive rate in addition to maximizing the non-halogenated ACI addition, an emission rate of 1.2 IbiTBtu was not able to be achieved. Due to the variability of the coal, a longer period of testing would be required to gauge the Hg emissions that could be achieved just using the capacity within the existing equipment. 3 Based on Response of Minnkota Power Cooperative Clean Air Act Section 114 Request, dated July 29, 2022. Particulate & Mercury Control Technology Evaluation & Risk Assessment for Proposed MATS Rule .S._ Lurzdy 9 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00039 SC_EVERSPLIT0006348