Document O3NB2eGxk173LeVBRgm1Le71

Minnkota Power Cooperative, Inc Milton R Young Station Unit 2 A14559 010 Rev No Final June 23. 2023 1.INTRODUCTION 1.1. PURPOSE Sargent & Lundy (S&L) was retained by Minnkota Power Cooperative, Inc. (Minnkota) to evaluate potential filterable particulate matter (PM) and mercury (Hg) emissions reductions in response to the proposed rule to amend the National Emission Standards for Hazardous Air Pollutants (NESHAP) for Coal-and Oil-Fired Electric Utility Steam Generating Units (EGUs), commonly known as Mercury and Air Toxics Standards (MATS) published on April 24, 2023 that would require additional filterable PM and Hg emissions reductiis on the Milton R. Young (MRY) Station Unit 2. These proposed revisions are the result of EPA's review of the residual risk and technology review (RTR) from May 22, 2020. Based on the proposed rule, EPA is planning to revise the filterable PM standards from 0.030 lb/MMBtu to 0.010 lb/MMBtu and is soliciting comments to consider even more stringent standard of 0.006 lb/MMBtu or lower. For lignitred units, EPA is also proposing to revise and tighten mercury emission standard from 4.0 lb/TBtu to 1.2 lb/TBtu to make it same as other units firing bituminous and subbituminous coal. S&L reviewed the existing MRY Unit 2 PM and Hg control technologiesto determine potential optimizations that could achieve incremental emission reductions as well as consider new PM and Hg control technologies S&L prepared an evaluation of available control technologies including technical feasibility and effectiveness, and costs based on the current emissions from the unit S&L's evaluation was completed based on past experience on similar projects, as well as input from established original equipment manufacturers (OEMs) regarding predicted performance for the lignite application at MRY Unit 2. 1.2. FACILITY BACKGROUND The MRY station is located approximately seven (7) miles southeast of Center, North Dakota or forty (40) miles northwest of Bismarck, North Dakota on ND Highway 25 at 3401 24th Street SW, Center, North Dakota 58530. MRY station provides energy to the Midcontinent Independent System Operator (MISO) system MRY station consists of two (2) units.Both MRY units are lignite-fired Babcock and Wilcox (B&W) cyclone boilers. The Unit 1 single wall cyclone boilerwas placed into service in 1970 and has a typical output capacity rating of 257 MWg (gross). The Unit 2 opposed wall cyclone boiler (Carolina type, radiant pump assisted natural circulation) was placed into service in 1977 and has a typical output capacity rating of470 MWg (gross). Both boilers fire North Dakota lignite coal supplied from BNI Coal, Ltd.'s Center Mine located in dose proximity to the plant. Both units utilize selective non-catalytic reduction (SNCR) and separated overtire air (SOFA) systems for NOx control, fuel additive (halide injection) system and no-halogenated powdered activated carbon (PAC) for Hg control,dry electrostatic precipitators (ESP) for PM emissions control, and wet flue gas desulfurization (WFGD) systems for sulfur dioxide (S02) control. 1.3. DIFFERENCES IN MRY UNIT 1 AND 2 DESIGN & OPERATION MRY Unit 1 and 2 have the same air pollution control equipment in series; however,the design of the equipment differ in ways other than unit MWg size. Of particular note, the Unit 2 ESP design attributes are superior to Unit 1, with use of a wider plate spacing (12 vs. 9 inches), and a higher specific collection area (375 ft211000 actual cubic feet per minute hcfm) vs. 288 ft2/1000 acfm). However, the Unit 2 ESP design consists of the first 2 fields' specific corona power = 160 VV/1000 acfm and the last 2 fields = 240 W/1000 actm Particulate & Mercury Control Technology Evaluation & Risk Assessment for Proposed MATS Rule .S._ Lurzdy 1 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000327-00031 SC_EVERSPLIT0006340