Evaluation of Gas Retention in Waste Simulants: Tall Column Experiments

Schonewill, Philip P.; Gauglitz, Phillip A.; Shimskey, Rick W.; Denslow, Kayte M.; Powell, Michael R.; Boeringa, Gregory K.; Bontha, Jagannadha R.; Karri, Naveen K.; Fifield, Leonard S.; Tran, Diana; Sande, Susan; Heldebrant, David J.; Meacham, J.E.; Smet, D.B.; Bryan, Wesley E.; Calmus, R.B.

doi:10.2172/1136239

Cited by 3 publications

(7 citation statements)

References 48 publications

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“…The effect of increasing the hydrostatic head, presumably due to liquid in piping above the column, is included in the analysis of the maximum retained gas. Bubble retention in settled beds of particles has been studied previously, and Gauglitz et al (2012) and Schonewill et al (2014) provide reviews of these studies. One key observation was that different mechanisms of gas retention will occur depending on the size of the settled particles, the bed height, and fluid and particle densities.…”

Section: Gas Retention Scenarios In the IX Columnmentioning

confidence: 99%

Maximum Potential Hydrogen Gas Retention in the sRF Resin Ion Exchange Column for the LAWPS Process

Gauglitz

Wells

Bottenus

et al. 2018

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Section: Gas Retention Scenarios In the IX Columnmentioning

confidence: 99%

Maximum Potential Hydrogen Gas Retention in the sRF Resin Ion Exchange Column for the LAWPS Process

Gauglitz

Wells

Bottenus

et al. 2018

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“…1.5 Gauglitz et al (2009) and Schonewill et al (2014) summarize previous studies of gas retention and release, including discussions of different bubble retention mechanisms that were originally described by Gauglitz et al (1994). The principal mechanisms of bubble retention can be grouped into three categories:…”

Section: 4mentioning

confidence: 99%

“…One example of a slow and steady release is individual bubbles becoming sufficiently large such that their buoyant force causes them to rise and be released (Stewart et al 1996). A second example of a slow and steady release is bubbles that interconnect and form continuous channels for gas to percolate through the bed Stewart et al 1996;Schonewill et al 2014). For example, in a follow-up evaluation of the gas retention test data with spherical glass beads noted above, Gauglitz et al (1996) reported a maximum retained gas fraction of 8.3 vol% for the 1.0-mm beads.…”

Section: Figure 12mentioning

confidence: 99%

“…Addition of reactive metal powder that corrodes to form hydrogen gas (see, for example, Gauglitz et al 2012, Schonewill et al 2014 for iron powder) -Iron powder does not react to generate hydrogen gas until the pH is acidic, so this metal not suitable for alkaline water or LAW simulant solutions. Aluminum powder was also evaluated, because it is reactive in alkaline solutions; however, it was determined that the reaction rate was too fast if the pH was greater than about 10, which is too low for Na + form sRF resin conditions.…”

Section: )mentioning

confidence: 99%

“…To assess gas generation in periods of no or minimal apparent changes in retained gas volume, e.g., in continuous gas release tests, the volume of generated gas was measured independently by capturing the gas leaving the otherwise sealed test vessel. The collection and quantification method was similar to that used in previous GR&R experimental projects (e.g., Gauglitz et al 1996 andPowell et al 2014). As depicted schematically in Figure 6.1 in Section 6.1, a tube connected to the top of the vessel (headspace) is routed to an inverted graduated cylinder that is partially submerged in and prefilled with water from a larger reservoir by applying a vacuum to the headspace of the cylinder.…”

Section: 15mentioning

confidence: 99%

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Gas Retention, Gas Release, and Fluidization of Spherical Resorcinol-Formaldehyde (sRF) Ion Exchange Resin

Gauglitz

Rassat

Linn

et al. 2018

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Executive SummaryThe Low-Activity Waste Pretreatment System (LAWPS) is being developed to provide treated supernatant liquid from the Hanford tank farms directly to the Low-Activity Waste (LAW) Vitrification Facility at the Hanford Tank Waste Treatment and Immobilization Plant. The design and development of the LAWPS is being conducted by Washington River Protection Solutions, LLC. A key process in LAWPS is the removal of radioactive Cs from LAW liquids using ion exchange (IX) columns filled with spherical resorcinol-formaldehyde (sRF) resin. When loaded with radioactive Cs, radiolysis of water in the LAW liquid will generate hydrogen gas. In normal operations, the generated hydrogen is expected to remain dissolved in the liquid and be continuously removed by liquid flow. One accident scenario being evaluated is the loss of liquid flow through the sRF resin bed after it has been loaded with radioactive Cs and hydrogen gas is being generated by radiolysis. For an accident scenario with a loss of flow, hydrogen gas can be retained within the IX column both in the sRF resin bed and below the bottom screen that supports the resin within the column, which creates a hydrogen flammability hazard. Because there is a potential for a large fraction of the retained hydrogen to be released over a short duration as a gas release event, there is a need to quantify the size and rate of potential gas release events. Due to the potential for a large, rapid gas release event, an evaluation of mitigation methods to eliminate the hydrogen hazard is also needed. One method being considered for mitigating the hydrogen hazard during a loss of flow accident is to have a secondary flow system, with two redundant pumps operating in series, that recirculates liquid upwards through the bed and into a vented break tank where hydrogen gas is released from the liquid and removed by venting the headspace of the break tank. The mechanism for inducing release of gas from the sRF bed is to fluidize the bed, which should allow retained bubbles to rise and be carried to the break tank.Currently, neither the ability of fluidizing a settled sRF bed to release gas nor the quantity of hydrogen gas that can be retained and the corresponding potential for large, rapid gas release events has been tested and evaluated. Accordingly, the purpose of this study was to conduct experiments and develop models that evaluate the ability of a re-circulating flow system to fluidize an sRF resin bed as a method to release retained hydrogen gas and maintain hydrogen gas retention at low levels, thereby avoiding conditions where hydrogen gas poses a flammability hazard. The purpose of the study was also to determine if effective hydrogen gas release would occur using a single constant fluidization velocity, because this is the most simple safety system to implement, for the range of fluid and sRF resin conditions anticipated in the column (because a velocity that is effective for one fluid/resin pair can be ineffective for different resin/fluid pairs). Finally, the study...

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Retained Hydrogen Literature Study for DWPF

Hansen

2019

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SRNL-STI-2019-00394 Revision 0 vi volume, purge rate, and power input, this data cannot be directly applied to the DWPF, but it is important to note that hydrogen is released over a finite time, rather than instantaneously. Previous work by SRNL and PNNL has measured the rheology of Hanford sludge, and shown the rheology (i.e., yield stress or shear strength) to increase as the sludge is allowed to settle. Changes in sludge rheology need to be considered when assessing changes to the DWPF retained hydrogen program. A comparison of buoyancy and inertial forces under SRAT operating conditions (1-10 Pa yield stress, 1.38 g/mL density, 65 or 130 rpm, 9,000 gallons of feed) on the bubbles (approximated as 300 micron diameter) found the inertial forces to be more than 350,000 times larger than the buoyancy forces. With this ratio of forces, the gas bubbles generated will follow the fluid motion in the SRAT, and only release when they reach the slurry-vapor interface. An informal Lattice Boltzmann Computation Fluid Dynamics calculation was performed on a SRAT type vessel. The liquid was assumed to have a density of 1 g/mL and a viscosity of 20 cP. In the simulation, approximately 50% of the bubbles were released to the vapor space over ~80 seconds. The simulation showed the bubbles to follow the liquid flow, and only release when they reached the liquid surface.

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Evaluation of Gas Retention in Waste Simulants: Tall Column Experiments

Cited by 3 publications

References 48 publications

Maximum Potential Hydrogen Gas Retention in the sRF Resin Ion Exchange Column for the LAWPS Process

Maximum Potential Hydrogen Gas Retention in the sRF Resin Ion Exchange Column for the LAWPS Process

Gas Retention, Gas Release, and Fluidization of Spherical Resorcinol-Formaldehyde (sRF) Ion Exchange Resin

Retained Hydrogen Literature Study for DWPF

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