IDAHO FALLS, Idaho - Work underway at a Colorado research facility to resolve technical challenges at the Idaho Site ’s Integrated Waste Treatment Unit (IWTU) is paying substantial dividends, with more to come.
“Hazen Research has been great to work with so far," said Craig Porter, a chemical engineer for the startup project for IWTU, which is intended to treat the site’s remaining 900,000 gallons of tank waste. “We’ve got a tremendous amount of data so far in our tests using simulated, non-radioactive waste. It’s been very positive."
Hazen, of Golden, Colo., constructed three testbeds to help resolve the issues with IWTU’s Denitration Mineralization Reformer (DMR). The DMR is the primary reaction vessel containing 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. Past waste simulant runs at IWTU revealed difficulties in controlling this process, and a wall-scale resembling bark formed on the DMR’s interior walls.
Using a 2-inch-diameter fluidized bed constructed of quartz glass, Hazen researchers installed a camera outside the treatment vessel to record the change in fluidization as gas flow rates, mixtures and other parameters changed. Hazen fabricated a 2-inch-diameter stainless steel vessel for the testbed to provide data on the chemical processes that take place inside the treatment vessel. Idaho National Laboratory will use this same testbed at Hazen to determine the kinetics, or the speed of the primary chemical reactions inside the vessel.
In April, Hazen will focus on IWTU’s wall-scale formation challenges using the 2-inch diameter fluidized bed unit. Probes installed inside the pilot plant allow real-time monitoring of the wall-scale formation and possible mitigation techniques. Porter said the 2-inch units will help determine improvements to minimize the wall-scale formation.
Hazen also fabricated a much larger model of the DMR for testing. An 18-inch-diameter pilot plant will be used to demonstrate measures to control the particle size to ensure proper media fluidization inside the DMR.
At the Idaho Site, EM expects to conduct a simulant run in IWTU to test a redesigned auger-grinder, which is crucial equipment to size and transfer treated waste material from the DMR to other IWTU treatment processes. During this run, EM will monitor and control the DMR’s operating parameters, including the simulant feed rate, introduction of gases to ensure proper fluidization of the bed material and the reaction vessel’s temperature.
As early as this summer, IWTU engineers expect to apply the prior simulant run information and Hazen test results as they begin another simulant run to refine operating parameters to support IWTU’s long-term operation. The Hazen tests and confirmatory IWTU runs use non-radioactive, simulated waste. EM will prepare IWTU to treat waste following testing and resolution of the facility’s issues.
Source: U.S. Dept. of Energy, Office of Environmental Management
