03 Gaseous fuels (transport, storage)

03 GASEO U S FUELS

Sources, properties, recovery, treatment

02/01880 Best practices for enhanced gob gas recovery and purity Harpalani, S. J. Mines, Met. Fuels, 2000, 48, (8), 222-229, 236. There are three primary methods of gob degasification used world- wide with variations of these to suit specific mining conditions cross- measure boreholes, superjacent methods, and vertical gob wells. This paper describes these three techniques, and presents factors that affect gas purity and capture efficiency with gob degasification systems, including geological and reservoir conditions, and borehole or well siting, spacing, integrity, suction, and control. The paper includes a discussion of 'best practices' for each method that may increase methane capture and purity along with a quality discussion of each practice's incremental costs and benefits. An important practice with significant impact is monitoring of gas flow rates, gas quality, system pressures, and underground conditions (airflows and gas concen- trations) to optimize gob degasification and mine ventilation systems.

02/01881 Carboniferous natural gas of Paskov coal mine of Dul Paskov, Czechska, optimal recovery increase in relation to natural and technical operational recovery conditions Dragon, V. Sb. Ved. Pr. Vys. Sk. Banske-Tech. Univ. Ostrava, Rada Horn.-Geol., 1999, 45, (2), 45-48. (In Czech) In the present paper a method of optimized increase of Carboniferous gas output is discussed with potential application for any mine of Ostrava Karvina coalfield during current period of restructuring and winding up of coal production activities of mines.

02/01882 Dehydration of natural gas using solid desiccants Gandhidasan, P. et al. Energy, 2001, 26, (9), 855-868. Natural gas is an important source of primary energy that, under normal production conditions, is saturated with water vapour. Water vapour increases natural gases' corrosivity, especially when acid gases are present. Several methods can be used to dry natural gas and, in this paper, a solid desiccant dehydrator using silica gel is considered due to its ability to provide extremely low dew points. The design analysis of a two-tower, silica gel dehydration unit to dry one million standard m 3 of natural gas per day is presented in this paper and the effects of various operating parameters on the design of the unit are discussed. The study also covers the analysis of energy requirements for the regeneration of the weak desiccant bed based on some simplified assumptions and it is found that the higher the regeneration temperature, the smaller are the required quantities of regeneration gas.

02/01883 Dense phase coal conveying for ARCH process Asaoka, Y. et al. Proc. - Annu. Int. Pittsburgh Coal Conf., 2000, (17), 870-876. The Development of Coal Hydrogasification Technology to secure a stable supply of substitute natural gas (SNG) from coal at low cost was performed from FY 1996 as a part of the Japanese governmental new energy program called the New Sunshine Project. The process is called ARCH (Advanced Rapid Coal Gasification) process. Within the first step which is approved as the Development of Elemental Technology, there are three researches; experimental research, supporting research and research on social adaptability. Experimental research consists of two developments; development of new coal gasifier and development of peripheral technology for the gasifier. A dense phase coal conveying method is one of the peripheral technologies, required for the ARCH process to carry coal with the minimum amount of gas into gasifier. An experimental rig was prepared to survey the coal conveying method under the pressure up to 7 MPa and succeeded in conveying coal at a dense phase with hydrogen in the range of feeding rate from 5 to 50 t/d under the pressure of 7 MPa. Experimental results and an analysis from engineering viewpoint are presented.

02/01884 Energy production and emission reduction by utilization of pit and seam gas Radgen, P. GWF, Gas/Erdgas, 2000, 141, (9), 596-602. (In German) A large share of CH4 emissions in Germany is related to coal mining activities. The increased use of mine gas as a fuel, which is already economic in many cases, may play an important role in energy supply and emission reduction in the future. Besides the use of mine gas, the production and use of coal bed CH4 has emerged as an option with considerable technical and economic potential. In the future CO2 could be sequestered in coal seams, provided that no later coal mining is

planned. Tests are made to sequester COz into coal seams. The type of CO2-sequestration increases the production of coal bed CH4, therefore reducing the net cost for sequestration.

02/01885 Major and minor structural features of a bedding shear zone along a coal seam and related gas outburst, Pingdingshan coalfield, northern China Li, H. International Journal o f Coal Geology, 2001, 47, (2), 101- I 13. A fractured coal band, traditionally called a soft-coal band, or structurally referred to as a bedding shear zone, within the Wu coal seam in the Pingdingshan coalfield, northern China, was structurally studied. Based on field examination and observations by reflectance microscopy and SEM, the bedding shear zone is not consistent with a simple bedding fault defined by pioneering geologists, but rather a complexly deformed band locally overprinted by ductile shearing fabrics. Dominant small-scale structures within the bedding shear zone are thrusts, folds, cleavage duplexes and related structures, but local, refolded folds, kink bands, and S-C band structures also indicate ductile shear deformation, typically developed in areas of steep dip such as within the limb of a subordinate fold. Bed-parallel shearing within the coal seam has been considered a serious influence on gas outburst in underground mining production in addition to thickening the seam and reducing the quality of coal. Locally, abnormal thickening of a shear zone and extensive compressive structures where ductile fabrics frequently occur are closely related with the site of an outburst. Thickening of a shear zone increases the capacity of methane storage, and compressive structures within a shear zone may act as a tectonic screen, blocking methane migration, which can result in a pocket of high methane pressure. A potential risk of outburst is indicated as a working face approaches an area of high methane pressure. Three abnormal phenomena encountered during a mining operation presage methane outburst for seams with a bedding shear zone.

02/01886 Possibility analysis of simultaneous extraction of coal and coalbed methane in China Li, S. and Xu, J. Proc. - Annu. Int. Pittsburgh Coal Con£, 2000, (17), 2100-2104. The paper analysed the storage characteristics of coalbed methane, and then studied the behaviour of coalbed methane by using the key stratum theory of strata control. According to the features related to coalbed methane accumulations and delivery, the technique for safely simultaneous extension of coal and combed methane is proposed, and benefit analysis is made too.

Transport, storage

02/01887 Scenario with inert matrix fuel: a specific study Doriath, J. Y. et al. Progress in Nuclear Energy, 2001, 38, (3 4), 4t9 422. In this paper, we described a strategy study concerning the future of the French nuclear energy infrastructure, with a scenario involving reactors loaded with inert matrix fuel. We select the problem of the inventory control of minor actinides by target introduction into fast reactors. Added to pressurized water reactors in the French nuclear infrastructure, this scenario permits one to balance plutonium and minor actinide production and consumption and to obtain a substantial reduction of the radiological impact compared to a non-reprocessing fuel scenario on a one million year scale.

02/01888 Transient gas-liquid two-phase flow in pipes with radial influx or efflux Quyang, L. and Aziz, K. Journal Of Petroleum Science and Engineering, 2001, 30, (3-4), 167-179. A simplified model for transient gas-liquid flow in pipes with radial influx or efflux has been developed in this paper. The resulting governing equations are essentially hyperbolic with Utp + c~ and Utp - cs as their eigenvalues. A finite-difference scheme based on the split coefficient matrix (SCM) approach is applied to solve the mass and momentum balance equations. Sample numerical simulation runs are performed. Simulation results agree with experimental observations and clearly show the features of variation in pressure drop, liquid holdup, and two-phase velocity during transient and steady state flow periods.

246 Fuel and Energy Abstracts July 2002