IDAHO FALLS, Idaho - Engineers recently completed an extended demonstration of the Integrated Waste Treatment Unit’s (IWTU) steam reforming process at a Colorado research facility.
They will apply lessons learned from that testing to an upcoming integrated demonstration at the IWTU at EM’s Idaho Site.
Hazen Research operated the steam reforming fluidized bed pilot plant for 44 days with a simulated waste material that replicates the 900,000 gallons of sodium-bearing liquid waste the IWTU will ultimately treat.
A primary goal of the Hazen test was to demonstrate extended, stable operations under various operating conditions.
“The secondary goal was to define the stable operational bands for parameters like temperature and gas flow rates," said Joe Giebel, chief engineer with EM cleanup contractor Fluor Idaho. “These successful operational parameters will then be utilized in the operational procedures for the next IWTU test run."
Engineers evaluated operations at various particle sizes to assess the response of the treatment process. The pilot plant operated best when the average product particle size was controlled to between 250 and 350 microns. A micron is a unit of length equal to one millionth of a meter.
The extended run also confirmed effective control strategies for wall-scale that has been problematic in previous IWTU and pilot plant runs. Previous IWTU demonstrations using a waste simulant resulted in a wall-scale resembling tree bark forming on the interior walls of the Denitration Mineralization Reformer (DMR), the IWTU’s main reaction vessel. The DMR contains billions of tiny beads kept in a fluidized state with the help of superheated gases. Liquid waste enters the fluidized bed, coating the beads like the formation of pearls. The waste product is transferred to stainless steel canisters and ultimately concrete vaults.
The scale formation does not significantly impact operations but could affect future vessel cleanout operations during any potential planned outages.
“We believe we’ll see better results during the next demonstration run at IWTU in terms of wall-scale due to the control strategy developed in the pilot plant," Giebel said.
Engineers are preparing the IWTU for a 30-day test early this year with simulated waste, focusing on the fluidization conditions inside the DMR. A second demonstration of up to 50 days follows, to evaluate the system’s long-term operational performance.
“In total, we’ll have up to an 80-day demonstration run," said Giebel. “With the changes we have made to the process and the equipment, we’re optimistic that the IWTU will produce the same results we saw with the Hazen pilot plant."
Source: U.S. Dept. of Energy, Office of Environmental Management
