The Florida Department of Environmental Protection on May 18 approved an application from Lakeland Electric for an air permitting exemption related to an emissions project on a coal unit at the C.D. McIntosh Jr. power plant.
On April 24, Lakeland Electric submitted a request to use dibasic acid (DBA) or other organic acids in the wet flue gas desulfurization (FGD) system for Unit 3 at the C.D. McIntosh Jr. Power plant. The purpose of this project is to reduce emissions of SO2 to meet the applicable Mercury and Air Toxics Standards (MATS) compliance standards. It asked for and has been granted an exemption from needing an air construction permit for this project.
The wet FGD system is a process that removes SO2 from flue gas during combustion in fossil fuel power plants such as coal and oil fired combustion units. When coal or oil is burned to produce energy, about 95% of the sulfur is converted into SO2 under standard temperature conditions. The scrubbing liquid used in the wet FGD system at C.D. McIntosh Jr. contains limestone to enhance the absorption of SO2 and other acid gases. Limestone FGD systems are capable of removing SO2 with efficiencies up to 90%.
The SO2 emission reduction technology proposed by Lakeland Electric includes the use of DBA or other organic acids into Unit 3’s wet FGD system. Currently, limestone is ground and mixed with water, and the resultant slurry is pumped to the absorber and sprayed into the flue gas stream. The slurry droplets absorb SO2 from the flue gas and fall to the base of the absorber. The function of DBA acid or other organic acids added to the process would enhance the SO2 removal efficiency by improving limestone dissolution and SO2 neutralization in the liquid/slurry phase. DBA or other organic acid solutions are not consumed in the absorption reaction, but in the intermediate reactions to remove SO2 from the flue gas. After the intermediate reaction takes place, DBA or other organic acid is regenerated and remains in the scrubber solution. Limestone with DBA or other organic acids added to the FGD systems are capable of SO2-removal efficiencies up to 98%.
Unit 3 is a dry-bottom, wall-fired steam generator with a nominal design capacity of 364 MW that fires coal, residual oil, natural gas and petroleum coke.