Engineering topics

Garn, Troy Gerry

Publications and source records attributed to Garn, Troy Gerry.

4 records

DOE OSTI2016

Multi-Column Xe/Kr Separation with AgZ-PAN and HZ-PAN

Previous multi-column xenon/krypton separation tests have demonstrated the capability of separating xenon from krypton in a mixed gas feed stream. The results of this initial testing with AgZ-PAN and HZ-PAN indicated that an excellent separation of xenon from krypton could be achieved. Building upon these initial results, a series of additional multi-column testing were performed in FY-16. The purpose of this testing was to scale up the sorbent beds, test a different composition of feed gas and attempt to improve the accuracy of the analysis of the individual capture columns’ compositions. Two Stirling coolers were installed in series to perform this testing. The use of the coolers instead of the cryostat provided two desired improvements, 1) removal of the large dilution due to the internal volume of the cryostat adsorption chamber, and 2) ability to increase the sorbent bed size for scale-up. The AgZ-PAN sorbent, due to its xenon selectivity, was loaded in the first column to capture the xenon while allowing the krypton to flow through and be routed to a second column containing the HZ-PAN for capture and analysis. The gases captured on both columns were sampled with evacuated sample bombs and subsequently analyzed via GC-MS for both krypton and xenon. The results of these tests can be used to develop the scope of future testing and analysis using this test bed for demonstrating the capture and separation of xenon and krypton using sorbents, for demonstrating desorption and regeneration of the sorbents, and for determining compositions of the desorbed gases. They indicate a need for future desorption studies in order to better quantify co-adsorbed species and final krypton purity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Superficial Velocity Effects on HZ-PAN and AgZ-PAN for Kr/Xe Capture

Nearly all previous testing of HZ-PAN and AgZ-PAN was conducted at the same flow rate in order to maintain consistency among tests. This testing was sufficient for sorbent capacity determinations, but did not ensure that sorbents were capable of functioning under a range of flow regimes. Tests were conducted on both HZ-PAN and AgZ-PAN at superficial velocities between 20 and 700 cm/min. For HZ-PAN, Kr capacity increased from 60 mmol/kg to 110 mmol/kg as superficial velocity increased from 21 to 679 cm/min. Results for AgZ-PAN were similar, with capacity ranging from 72 to 124 mmol/kg over the same range of superficial. These results are promising for scaling up to process flows, demonstrating flexibility to operate in a broad range of superficial velocities while maintaining sorbent capacity. While preparing for superficial velocity testing it was also discovered that AgZ-PAN Xe capacity, previously observed to diminish over time, could be recovered with increased desorption temperature. Further, a substantial Xe capacity increase was observed. Previous room temperature capacities in the range of 22-25 mmol Xe/kg AgZ-PAN were increased to over 60 mmol Xe/kg AgZ-PAN. While this finding has not yet been fully explored to optimize activation and desorption temperatures, it is encouraging.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2016

Multi-Column Experimental Test Bed Using CaSDB MOF for Xe/Kr Separation

Processing of spent nuclear fuel produces off-gas from which several volatile radioactive components must be separated for further treatment or storage. As part of the Off-gas Sigma Team, parallel research at INL and PNNL has produced several promising sorbents for the selective capture of xenon and krypton from these off-gas streams. In order to design full-scale treatment systems, sorbents that are promising on a laboratory scale must be proven under process conditions to be considered for pilot and then full-scale use. To that end, a bench-scale multi-column system with capability to test multiple sorbents was designed and constructed at INL. This report details bench-scale testing of CaSDB MOF, produced at PNNL, and compares the results to those reported last year using INL engineered sorbents. Two multi-column tests were performed with the CaSDB MOF installed in the first column, followed with HZ-PAN installed in the second column. The CaSDB MOF column was placed in a Stirling cryocooler while the cryostat was employed for the HZ-PAN column. Test temperatures of 253 K and 191 K were selected for the first column while the second column was held at 191 K for both tests. Calibrated volume sample bombs were utilized for gas stream analyses. At the conclusion of each test, samples were collected from each column and analyzed for gas composition. While CaSDB MOF does appear to have good capacity for Xe, the short time to initial breakthrough would make design of a continuous adsorption/desorption cycle difficult, requiring either very large columns or a large number of smaller columns. Because of the tenacity with which Xe and Kr adhere to the material once adsorbed, this CaSDB MOF may be more suitable for use as a long-term storage solution. Further testing is recommended to determine if CaSDB MOF is suitable for this purpose.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2015

Multi-Column Experimental Test Bed for Xe/Kr Separation

Previous research studies have shown that INL-developed engineered form sorbents are capable of capturing both Kr and Xe from various composite gas streams. The previous experimental test bed provided single column testing for capacity evaluations over a broad temperature range. To advance research capabilities, the employment of an additional column to study selective capture of target species to provide a defined final gas composition for waste storage was warranted. The second column addition also allows for compositional analyses of the final gas product to provide for final storage determinations. The INL krypton capture system was modified by adding an additional adsorption column in order to create a multi-column test bed. The purpose of this modification was to investigate the separation of xenon from krypton supplied as a mixed gas feed. The extra column was placed in a Stirling Ultra-low Temperature Cooler, capable of controlling temperatures between 190 and 253K. Additional piping and valves were incorporated into the system to allow for a variety of flow path configurations. The new column was filled with the AgZ-PAN sorbent which was utilized as the capture medium for xenon while allowing the krypton to pass through. The xenon-free gas stream was then routed to the cryostat filled with the HZ-PAN sorbent to capture the krypton at 191K. Selectivities of xenon over krypton were determined using the new column to verify the system performance and to establish the operating conditions required for multi-column testing. Results of these evaluations verified that the system was operating as designed and also demonstrated that AgZ-PAN exhibits excellent selectivity for xenon over krypton in air at or near room temperature. Two separation tests were performed utilizing a feed gas consisting of 1000 ppmv xenon and 150 ppmv krypton with the balance being made up of air. The AgZ-PAN temperature was held at 295 or 253K while the HZ-PAN was held at 191K for both tests. The effluent from the AgZ-PAN column was monitored via GC-TCD during the tests with no xenon being observed exiting the column during either test. Samples from each column were taken via evacuated sample bombs and were analyzed by GC-MS analysis. The results demonstrated the ability to separate xenon from krypton from a mixed gas feed utilizing the new multi-column system.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗