Various technologies, including dry sorbent injection, plus the use of low-sulfur Colombian coal, are being looked at for compliance with regional haze rules at Gulf Power’s coal-fired Lansing Smith power plant.
Gulf Power, a unit of Southern Co. (NYSE: SO), on July 16 filed with the Florida Department of Environmental Protection a five-factor analysis of Best Available Retrofit Technology (BART) options for the plant. Lansing Smith, located in Bay County, Fla., includes two coal-fired steam generators (Units 1 and 2) which are BART-eligible.
With respect to the Regional Haze Rule (RHR) BART requirements, the U.S. Environmental Protection Agency (EPA) previously determined that emissions sources subject to the Clean Air Interstate Rule’s (CAIR) SO2 and NOx trading programs would achieve SO2 and NOx emissions reductions that would result in visibility improvement that is better than BART; therefore, these two pollutants would not need to be addressed in BART determinations. Due to legal challenges to CAIR, EPA issued a final rule in July 2011, called the Cross-State Air Pollution Rule (CSAPR).
For Florida electrical generating units (EGUs), CSAPR only addresses ozone season NOx emissions. However, in December 2011, a federal appeals court stayed CSAPR and left CAIR in effect pending judicial review. So, Units 1 and 2 remain subject to CAIR, which, for Florida EGUs, addresses SO2 and NOx (both annual and ozone season), the analysis said.
Although Smith Units 1 and 2 remain subject to CAIR and EPA has determined that both CAIR and CSAPR will result in visibility improvement that is better than BART, due to the regulatory uncertainty with CAIR and CSAPR, the Florida DEP requested the submittal of a five-factor BART analysis for Smith Units 1 and 2 for SO2, NOx, and particulate matter (PM). Gulf Power prepared the BART analysis filed July 16 in response to the FDEP’s request.
Units 1 and 2 are tangentially-fired, dry-bottom boilers that began commercial operation in 1965 (Unit 1), and 1967 (Unit 2). Units 1 and 2 have generation capacities of 175 and 205 MW, respectively.
Gulf Power wants to stick with existing controls for NOx, PM
There are three BART pollutants examined in the report from Environmental Consulting & Technology Inc.; SO2, NOx and PM.
SO2 retrofit control technologies evaluated include: switch to lower sulfur Colombian coal; dry sorbent injection (DSI) with use of lower sulfur Colombian coal; dry flue gas desulfurization (DFGD) lime spray dryer absorber (SDA); and wet flue gas desulfurization (WFGD). All of the identified available retrofit SO2 control technologies are considered technically feasible for Units 1 and 2. However, DFGD lime SDA is considered an inferior technology compared to WFGD and was not evaluated further.
The proposed SO2 BART determination for Smith Units 1 and 2 is an SO2 emissions rate of 0.74 lb/MMBtu on a 30-day rolling average basis, which can be achieved with the use of DSI with trona as the alkaline reagent. The proposed BART SO2 control technology will be installed and in operation no later than the Mercury and Air Toxics Standard (MATS) compliance deadline prior to the end of the first 10-year RHR planning period in 2018.
The DSI (trona) plus Colombian coal option represents the best level of control based on consideration of the statutory factors required by Section 169A(g)(7) of the Clean Air Act. A comprehensive evaluation of the three factors most relevant to the Smith Units 1 and 2 BART SO2 analysis (i.e., cost of compliance, energy and non-air-quality environmental impacts, and degree of improvement in visibility) leads to the conclusion that the DSI (trona) plus Colombian coal option is the best option due to its substantially lower cost, decreased energy cost, non-air-quality impacts, and the minimal additional visibility improvement that would occur with WFGD.
Smith Units 1 and 2 are currently equipped with low-NOx burner tips (LNBt) with high-momentum injection ports, and Unit 2 has low-NOx burners (LNBs) with an overfire air control system. In addition to LNB technology, both units have selective non-catalytic reduction (SNCR) for additional NOx control. These NOx combustion controls were installed in response to CAIR. Since Units 1 and 2 are currently equipped with NOx combustion controls and SNCR, this suite of NOx controls served as the baseline, and the focus of the NOx BART analysis for Units 1 and 2 was confined to the evaluation of selective catalytic reduction (SCR) technology. The proposed NOx BART determination for Plant Smith Units 1 and 2 is no additional control, with continued use of the existing NOx combustion controls and SNCR with emissions limits specified by the current Smith Title V air operation permit.
Smith Units 1 and 2 are equipped with highly efficient hot and cold side electrostatic precipitators (ESPs) that achieve very low PM emissions rates. The existing PM controls served as the baseline and the focus of the PM BART analysis for Units 1 and 2 was confined to the evaluation of fabric filter (i.e., baghouse) technology. The proposed PM BART determination for Smith Units 1 and 2 is no additional control and continued use of the existing hot and cold side ESPs, with the emissions limits specified by the current Smith Title V air permit.