The tanks store tar oil produced from the gasification process, and can hold 700,000 gallons each.
Basin Electric Power Cooperative
- June 15, 2012
Two tar oil tanks at the Great Plains Synfuels Plant are getting new floating roofs. The tanks store tar oil produced from the gasification process, and can hold 700,000 gallons each. The roof design provides a barrier that will control vapors in the tar oil tanks per Environmental Protection Agency (EPA) regulations.
Vicente Martinez, Synfuels Plant senior environmental engineer, said the EPA regulations for storing tar oils changed when Dakota Gas began selling some of the tar oil. “We were exempt from the storage Maximum Achievable Control Technology (MACT) requirements as long as we burned all the tar oil as fuel in the boilers,” Martinez said. “Once we began selling some of it, the tar oil became a regulated material, and Dakota Gas lost that exemption for good as part of the EPA MACT program, 'Once in always in.'”
The floating roofs on the tanks will reduce the volatile organic carbon and hazardous air pollutants emissions and will comply with the requirement and controls regulated by the EPA Organic Liquid Distribution MACT rule, which was effective in 2007.
One tar oil tank was taken out of service at the beginning of April for cleaning and preparation for installation of the new 50-foot diameter floating roof. BMT Acquisition, LLC, Albuquerque, NM, mobilized April 30 and began installing the new roof.
Field maintenance and weld shop employees assisted in preparing the tank for the new roof during the month of April. “We needed to move some of the inlet lines down from the top of the tank to below the new floating roof line,” said Randy Biffert, field maintenance superintendent.
Field maintenance employees prepared the tank and helped the weld shop with the new lines. Weld shop employees installed the two new nozzles, fabricated two new lines and capped off several nozzles that were no longer needed.
“Everything went according to schedule,” Biffert said. “I want to thank all of the departments involved for their hard work in meeting the schedule.”
Process operations will take the second tank out of service this week to prepare it for the installation of the new floating roof. BMT will be back on plant site July 9 to mobilize for installation of the second roof. The second tank is scheduled to be completed and returned to service mid-August.