Data Analysis and Model Validation (2013 CEF Run - Phase 1)

DWPF Melter Off-Gas Flammability Model for the Nitric-Glycolic Acid Flowsheet

“…The non-existent correlation between the calculated air inleakage rate and √∆ for the Phase 1 run was attributed to the potential air infiltration through the pour tube due to intermittent glass pouring during low VS temperature runs. 8 The same situation was also encountered in Phase 2 during the non-bubbled runs at low VS temperatures; however, the calculated air inleakage rates appear less scattered. Efforts made to reduce the air inleakage rate from those of the 2010 run appear to have worked; however, the calculated air inleakage rates in excess of 10 scfm at nominal -5" H 2 O is still large considering that the design basis air inleakage rate of the DWPF melter which has an effective melt surface area 11 times larger than the CEF is only ~20 scfm.…”

“…In doing so, however, it over predicted the TOC-to-H 2 conversion by a factor of 4 or higher at T gas < ~350°C, which was attributed to the conservative antifoam decomposition scheme used in the cold cap model. 8…”

“…It was also shown that the thermal characteristics of the CEF vapor space are prototypic thanks to its prototypic design. 8 It is ensured by the results of the earlier CEF tests that the data taken during the Phase 2 test will be also prototypic and thus suitable to be used as the basis for developing the new DWPF melter flammability technical bases for the NGA flowsheet. This report details the results of the Phase 2 data analysis, highlights some of the characteristic features of melter operation with the NGA flowsheet feeds, and documents the key bases and assumptions of the new DWPF melter off-gas flammability model.…”

DWPF Melter Off-Gas Chemistry Model for the Nitric-Glycolic Acid Flowsheet

“…5 It was used in 2010 to study the impact of glass bubblers on melter off-gas surging (Phase 1), 6 and the frequency and intensity of off-gas surges during bubbled and non-bubbled CEF runs were found to be prototypic of the DWPF melter pressure spike data collected during the 6 months before and 6 months after the bubblers went into operation. 7 The CEF was also shown to be prototypic in terms of predicting the flammability potential of the DWPF melter off-gas; 8 the predicted concentrations of H 2 and CO by the existing DWPF melter off-gas flammability model correctly trended and further bounded the respective measured data in the offgas produced with the NFA flowsheet feed during the Phase 1 CEF run. The seemingly-excessive over-prediction of the Phase 1 H 2 data at the melter vapor space gas temperature (T gas ) below ~350 °C was attributed to the conservative antifoam decomposition scheme used by the model and, therefore, was considered a modeling issue and not a design issue.…”

“…Furthermore, the thermal characteristics of the CEF vapor space were also shown to be prototypic thanks to its prototypic design. 8 Thus, it is ensured that the data taken during the Phase 2 run will be also prototypic and thus suitable to be used as the basis for developing the new DWPF melter flammability technical bases for the NGA flowsheet. This report details the results of the Phase 2 data analysis, highlights some of the characteristic features of melter operation with the NGA flowsheet feeds, and documents the key bases and assumptions of the new DWPF melter off-gas flammability model.…”