A standard high-solids vessel (SHSV) concept design approach using pulse jet mixers (PJM) has been proposed by the US Department of Energy (DOE) for the Hanford Tank Waste Treatment and Immobilization Plant (WTP) as a potential replacement for several vessels that will be used to process highly radioactive waste. To assist with the evaluation of the SHSV concept, at DOE’s direction, the WTP Project recently completed qualification testing of the SHSV PJM mixing system to verify the design. Testing of the SHSV design, conducted at full scale, was split into two phases. The first phase of testing developed PJM controls that supported all operational modes under a set of most adverse fluid conditions. The second phase of testing used the PJM operating strategy, established during the first phase, to perform qualification testing to verify that the mixing system design supports the transfer, de-inventory, throughput, and sampling functional requirements of the SHSV. The different control methods that were used to operate PJMs in simulants exhibiting Newtonian and non-Newtonian rheological properties with high solids loading are presented.
The PJM system of the SHSV uses six pulse tubes distributed in a circular array. Each pulse tube (3000 liters nominal volume) is connected to a jet pump pair (JPP) by means of an air link line. The JPP powers the PJM operation by applying a vacuum to refill the PJM (suction phase), pressurizing the PJM to discharge the pulse tube content at a target velocity (drive phase), and releasing the compressed air to allow the PJM to depressurize into a ventilation system (vent phase) designed for contaminated air. A PJM control system was developed to maximize the PJM operation and minimize potential impact to the structural integrity of the vessel. The experimental results showed effective control of the system parameters. The system response demonstrated reliable control of the drive set pressure, the drive time, and synchronization. The PJM control system design also proved robust in mobilizing settled solids.