(380av) CFD Simulations of Integrated Waste Treatment Unit

In a cost-saving computer modeling effort, the National Energy Technology Laboratory (NETL) assisted in solving a critical technical issue at the U.S. Department of Energy (DOE) Office of Environmental Management (EM) Integrated Waste Treatment Unit (IWTU), preventing a long-term delay of start-up operations. IWTU is an Energy Department facility designed to treat 900,000 gallons of radioactive liquid waste by heating and essentially drying it into a solid granular material for long-term storage. The heat required in this process is created by a piece of equipment called a denitration mineralization reformer (DMR), in which coal, steam, air and oxygen interact. Because this mixture contains multiple phases of matter (i.e., solids and gases), an understanding of multiphase flow is critical for design and troubleshooting. CFD simulations using the NETL’s Multiphase Flow with Interphase eXchanges (MFiX) software suite, demonstrated that the problem — solids accumulating or agglomerating in the lower regions of the DMR — was inherent to the DMR’s design and could not be overcome under normal operating conditions. NETL researchers then began a highly successful collaboration with EM support contractor Flour Idaho and the Idaho National Laboratory to create MFiX simulations that screened three alternative reactor designs under a range of conditions. This partnership was an exceptional example of teamwork in which a DOE contractor leveraged a variety of powerful resources, including cutting-edge modeling tools, the expertise of two national labs and thousands of computational cores, to efficiently solve a difficult technical issue. The simulations were pivotal in the design selection and guided both sub-scale and full-scale experiments. This computational approach eliminated the need to test each design under a range of operating conditions at full scale. IWTU made the selected design change to the DMR, which was successfully tested with no evidence of further accumulation of solids.