Mass Balance Results for Pricetown I Underground Coal Gasification

A mass balance model was applied to the Pricetown I test data. This model gave the values of various parameters such as water influx, percent devolatilization, percent gasification, amount of coal affected, thermal efficiency, etc., for the various phases of the test. Both hourly and daily values of the test data were used. At certain times, there was air loss to the coal seam or air gain from the coal seam as related to the underground reactor. Mass balances are modified accordingly. Realistic pyrolysis temperatures have been chosen for the different phases of the test based on the thermocouple responses. The nitrogen and argon balances gave similar results. The mass balance results showed that approximately 702 tons of coal was affected during the test. Approximately 232 tons of coal was completely gasified. The reverse combustion linkage through the virgin coal seam was dominated by the devolatilization and accounted for approximately 80% devoltilization whereas the same accounted for only 26% devolatilization during the gasification phase. During the enhanced linkage phase, the percent devolatilization ranged between that observed for the RCL and gasification phase. There was net influx of water and amounted to 0.59 barrels per ton of coal affected. The percent energy recovery for the gasification phase was 72% based on gas chromatographic data, and accounting the sensible heat of the gas and the latent heat of the water vapor in the gas

Application of the Controllable Unit Approach (CUA) to analyzing safeguards measurement systems

CUA is a material control and accountability methodology that takes into account the system logic and statistical characteristics of a plant process through the formulation of closure equations. The study evaluated CUA methodology to meet performance oriented regulations. The criterion is defined as the detection of a material loss of two kilograms of SNM with 97.5% confidence. Specifically investigated were the timeliness of detection, the ability to localize material loss, process coverage, cost/benefits, and compatibility with other safeguards techniques such as diversion path analysis and data filtering. The feasibility of performance-oriented regulations is demonstrated. To fully use the system of closure equations, a procedure was developed to formally integrate the effect of both short-term and long-term closure equations into an overall systems criterion of performance. Both single and multiple diversion strategies are examined in order to show how the CUA method can protect against either strategy. Quantitative results show that combined closure equations improve the detection sensitivity to material loss, and that multiple diversions provide only diminishing returns

Mineralogical and geochemical analysis of Fe-phases in drill-cores from the Triassic Stuttgart Formation at Ketzin CO₂ storage site before CO₂ arrival

Reactive iron (Fe) oxides and sheet silicate-bound Fe in reservoir rocks may affect the subsurface storage of CO2 through several processes by changing the capacity to buffer the acidification by CO2 and the permeability of the reservoir rock: (1) the reduction of three-valent Fe in anoxic environments can lead to an increase in pH, (2) under sulphidic conditions, Fe may drive sulphur cycling and lead to the formation of pyrite, and (3) the leaching of Fe from sheet silicates may affect silicate diagenesis. In order to evaluate the importance of Fe-reduction on the CO2 reservoir, we analysed the Fe geochemistry in drill-cores from the Triassic Stuttgart Formation (Schilfsandstein) recovered from the monitoring well at the CO2 test injection site near Ketzin, Germany. The reservoir rock is a porous, poorly to moderately cohesive fluvial sandstone containing up to 2–4 wt% reactive Fe. Based on a sequential extraction, most Fe falls into the dithionite-extractable Fe-fraction and Fe bound to sheet silicates, whereby some Fe in the dithionite-extractable Fe-fraction may have been leached from illite and smectite. Illite and smectite were detected in core samples by X-ray diffraction and confirmed as the main Fe-containing mineral phases by X-ray absorption spectroscopy. Chlorite is also present, but likely does not contribute much to the high amount of Fe in the silicate-bound fraction. The organic carbon content of the reservoir rock is extremely low (<0.3 wt%), thus likely limiting microbial Fe-reduction or sulphate reduction despite relatively high concentrations of reactive Fe-mineral phases in the reservoir rock and sulphate in the reservoir fluid. Both processes could, however, be fuelled by organic matter that is mobilized by the flow of supercritical CO2 or introduced with the drilling fluid. Over long time periods, a potential way of liberating additional reactive Fe could occur through weathering of silicates due to acidification by CO2

MASS BALANCE RESULTS FOR PRICETOWN 1 UNDERGROUND COAL GASIFICATION

ABSTRACT A mass balance model was applied to the Pricetown I test data. This model gave the values of various parameters such as water influx, percent devolatilization, percent gasification, amount of coal affected, thermal efficiency, etc., for the various phases of the test. Both hourly and daily values of the test data were used. At certain times, there was air loss to the coal seam or air gain from the coal seam as related to the underground reactor. Mass balances are modified accordingly. Realistic pyrolysis temperatures have been chosen for the different phases of the test based on the thermocouple responses. The nitrogen and argon balances gave similar results. The mass balance results showed during the test. Approximately 232 combustion linkage through the virgi and accounted for approximately 80% 26% devolatilization during the gasi the percent devolatilization ranged phase. There was net influx of wate affected. The percent energy recove gas chromatographic data, and accoun heat of the water vapor in the gas. that approximately 702 tons of coal was affected tons of coal was completely gasified. The reverse n coal seam was dominated by the devolatilization devolatilization whereas the same accounted for only fication phase. During the enhanced linkage phase, between that observed for the RCL and gasification r and amounted to 0.59 barrels per ton of coal ry for the gasification phase was 72% based on ting the sensible heat of the gas and the latent INTRODUCTIO

Pricetown I underground coal gasification field test: operations report

An Underground Coal Gasification (UCG) field test in bituminous coal was successfully completed near Pricetown, West Virginia. The primary objective of this field test was to determine the viability of the linked vertical well (LVV) technology to recover the 900 foot deep, 6 foot thick coal seam. A methane rich product gas with an average heating value of approximately 250 Btu/SCF was produced at low air injection flow rates during the reverse combustion linkage phase. Heating value of the gas produced during the linkage enhancement phase was 221 Btu/SCF with air injection. The high methane formation has been attributed to the thermal and hydrocracking of tars and oils along with hydropyrolysis and hydrogasification of coal char. The high heating value of the gas was the combined effect of residence time, flow pattern, injection flow rate, injection pressure, and back pressure. During the gasification phase, a gas with an average heating value of 125 Btu/SCF was produced with only air injection, which resulted in an average energy production of 362 MMBtu/day

Statistical problems arising from simulation of a high-throughput nuclear facility

Shortages in traditional energy sources, such as oil and natural gas, have placed greater emphasis on alternative fuel sources. With an already developed technological base and cost history, nuclear power is an attractive option. However, the public's attitude toward recent terrorism has generated strong demands for improved safeguards measures to deter, detect, and protect against diversion of special nuclear material (SNM). To encourage improved safeguards accountability, the Nuclear Regulatory Commission (NRC) has been considering the use of performance oriented regulations to supplement those currently used. A study, sponsored by NRC/Office of Standards Development, was conducted to evaluate the controllable unit approach (CUA) to meeting performance oriented regulations. The study results are used to provide the NRC with a methodology that systematically and iteratively compares the actual situation to the need before additions or refinements are imposed. And because the existing or proposed system is mathematically modeled, modifications to the process for any reason can be tested quickly for their effect on material control before implementation. A summary flow diagram of the CUA methodology is shown and described