San Juan power station
The San Juan Generating Station near the town of Farmington, New Mexico is a mine mouth power station with an installed capacity of 1,800 MW. Its four boilers, two of 350 MW and two of 550 MW each, fire coal with a sulfur content of 0.9%. The power station has operated FGD plants for many years and it will now move to desulfurizing one hundred percent of its exhaust gas flow.
In the mid seventies, the San Juan Station was fitted with FGD plants using the Wellman Lord process. This early FGD system used four separate scrubber vessels per unit. In the late nineties, the FGD system was converted to a wet limestone process, upgrading the sulfur removal efficiency from 75% to 90%. The power station continued to bupass a portion of the gas stream around the FGD system.
Through the years of operating the San Juan chimneys with a mixed, partially desulfurized gas flow, it was found that the free standing brick chimney flues were subject to degradation especially in the mixing zones for treated and non-treated gas flows. In 2002 and 2003 the station installed PennguardTM linings in the lower part of the brick flues of the Unit 1 and Unit 2 chimneys.
With emissions regulations becoming more and more stringent, the San Juan Power Station, which is operated by Public Service of New Mexico but which is owned by nine utilities from five states, decided in 2006 to switch to fully desulfurized operation, eliminating any bypass around
the FGD system.
In order to prepare the chimneys for low temperature wet stack operation, the owners also decided that the brick flues in all four chimneys would be protected by PennguardTM linings over their full height.