Tampa Electric nears air permit approvals for Big Bend coal plant

The Florida Department of Environmental Protection on Jan. 15 went out for comment on an air permit change that establishes a new SO2 limit for the coal-fired Big Bend power plant of Tampa Electric (TEC).

“The purpose of the project is to reduce SO2 emissions and ambient impacts from the facility,” said a DEP permit document. “Specifically, the draft permit establishes an SO2 emissions cap of 3,162 pounds per hour (lb/hour) based on a 30-day rolling average over existing fossil fuel fired electrical generating units (Units 1-4, combined). Over the years, TEC has made substantial upgrades to the controls to reduce SO2 emissions including: the installation of wet FGD scrubbers; splitting Units 3 and 4 ducts to exhaust through individual stacks and to remove FGD bypass capabilities; and removing FGD bypass capabilities for Units 1 and 2 prior to exhausting through a shared stack.”

Recently, Tampa Electric made the following improvements to enhance the performance of the FGD systems to increase removal efficiency and further reduce SO2 emissions:

Units 1 and 2 FGD System

  • Add FGD tower wall ring to deflect the flue gas away from the walls of the towers.
  • Replace slurry nozzles in FGD tower absorber with new double-headed nozzles to increase the number of spray nozzles and enhance gas-liquid contact within the towers.

Units 3 and 4 FGD System

  • Replace slurry nozzles in FGD Absorber Towers A and B with new double-headed nozzles to increase the number of spray nozzles and enhance gas-liquid contact within the towers for better SO2 removal efficiency.
  • In FGD Absorber Towers C and D: replace slurry nozzles with new redesigned spray headers to increase the number of spray nozzles and enhance gas-liquid contact within the towers; install larger motors on the recycle pumps for the spray headers to boost head pressure and improve the spray pattern; and relocate the dual-flow trays in each tower to a lower elevation to increase effectiveness.
  • Replace the flue gas inlet ductwork to FGD Absorber Tower C to reduce pressure loss and balance the uneven gas flow distribution between Absorber Towers C and D.

The new standard applies at all times including periods of startup and shutdown. Although Tampa Electric requested an effective date of Aug. 31, 2017, the wet FGD system is fully functional with recent upgrades installed to ensure compliance with the new Mercury and Air Toxics Standards (MATS). Also, existing SO2 emissions data shows that the combined emissions from Units 1–4 previously met the proposed cap more than 96% of the time – without an operational target and before the scrubber upgrades. The department established an effective date for the SO2 emissions cap of within 180 days of completing construction of the last natural gas igniter authorized under a prior permit, but no later than June 1, 2016.

Big Bend Units 1 through 3 each have a design capacity of 445 MW. Unit 4 has a design capacity of 486 MW. The fuel fired in all four units consists of coal, or a coal/petroleum coke blend containing a maximum of 20% petroleum coke by weight, or coal blended with coal residual generated from the Polk Power Station, or a coal/petroleum coke blend further blended with coal residual generated from the Polk Power Station, and on-site generated fly ash.

Tampa Electric also nears gypsum pelletizing permit

The department on Jan. 14 also went out for comment on a draft approval for a gypsum pelletizing project at Big Bend. Gypsum is a by-product created by the limestone-fed FGDs. At Big Bend, Tampa Electric currently markets its gypsum for the production of wall board as well as agricultural applications. A much larger percentage of the gypsum sold goes towards wall board production than agriculture.

By pelletizing gypsum, Big Bend will see an increased marketability for the synthesized gypsum as fertilizer for agricultural applications, as well as other new possibilities. The pelletizing process will be able to utilize all grades of onsite gypsum production to create a high quality, transportable product. The project will consist of a new building which will house a gypsum dumping area, a gypsum and clay binder mixing area, a pelletizer production line (pellet dryer, cooler and bagging operations), and  storage areas for both bagged and bulk pellets. The project will include several baghouses for collecting gypsum dust from the various activities related to the pelletizing process primarily for recovering sellable product, but also for reducing potential emissions of particulate matter as a secondary benefit.

The gypsum pelletizer process is currently in development by Kercher Industries and will work to mechanically transport raw gypsum through several pieces of equipment to achieve a pellet material composed of gypsum and binder.

About Barry Cassell 20414 Articles
Barry Cassell is Chief Analyst for GenerationHub covering coal and emission controls issues, projects and policy. He has covered the coal and power generation industry for more than 24 years, beginning in November 2011 at GenerationHub and prior to that as editor of SNL Energy’s Coal Report. He was formerly with Coal Outlook for 15 years as the publication’s editor and contributing writer, and prior to that he was editor of Coal & Synfuels Technology and associate editor of The Energy Report. He has a bachelor’s degree from Central Michigan University.