Underground coal gasification (UCG) is a method whereby the mining and conversion of coal are accomplished in a single step. Many field tests of UCG have been operated worldwide since the 1930's with varying degrees of success; based on this experience (especially in the USSR and United States), a field design which is applicable to a wide range of geological conditions and coal properties has evolved. This review discusses the rationale of this design and provides a physicochemical interpretation for the operation of a UCG system. Pertinent field and laboratory results as well as formal mathematical models of an in situ gasifier are evaluated as part of the analysis. SCOPEThere are presentIy many coal reserves in the world which are not economically recoverable using conventional mining techniques. Underground (in situ) coal gasification offers a potentially economic means of extracting the energy content from such coals while, at the same time, eliminating many of the health, safety, and environmental problems of deep mining of coal. A significant amount of field testing of underground coal gasification, especially in the USSR, has occurred in the past 50 yr, and the low Btu gas process is currently in commercial use at several sites in the USSR, UCG is presently of great interest in North America, where seven field tests are in operation. Recent cost estimates for producing low, medium, and high Btu gas by UCG show that it is more economically attractive than conventional mining followed by first generation surface gasification for thick western coal seams between 200 and 2 000 ft deep.The development and utilization of UCG in this country has, however, been hindered by a number of unsuccessful field tests, incomplete knowledge about Russian UCG technology, and a general lack of understanding about field design principles and the physicochemical processes involved. However, recent translations of the Russian technical literature have provided a significant body of information about Russian operating experience for a wide variety of geological conditions and coal properties. In addition, the U.S. Department of Energy has operated extremely successful field tests on Wyoming coal in the last 4 yr. Hence, a nominal field design can be performed using existing technology. Commercialization of UCG in the United States and Canada awaits economic optimization of the process design as well as a clearer picture of the role and economics of alternative energy sources, especially coal, as substitutes for oil and gas.The objective of this review is to present the basic field design for UCG and the logic behind it and to provide an interpretation of the chemistry and physics of UCG. Ultimately, such an analysis is the basis for evaluating the technical and economic feasibility of a candidate site for underground coal gasification. CONCLUSIONS A N D SIGNIFICANCEThe design of an underground coal gasification (UCG) system is a formidable one in view of the performance requirements, since there are very few adjustable paramete...
Greatly improved lasing of flashlamp-excited organic dyes has been achieved by collisionally deexciting the triplet state of dye molecules with newly discovered chemical additives. Experimental results show the quantitative improvement of several principal organic lasing compounds when they are placed in solution with chemical additives. An explanation of the deexcitation mechanism is offered; the criteria for selecting proper chemical additives are listed.
Amazes des Mines de BeZgique 50, I J-68-i 11) I P i g l i s h t r a n s l. : Lawrence Livermore L a b o r a t o r y , UCRL-110951. V. I. Belov " R e g u l a t i o n o f t h e Q u a l i t y o f G a s From Underground G a s i f i c a t i o n (of Coal) by Blowing With P e r i o d i c a l l y Changing V e l o c i t y. "
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The momentum transfer caused by focusing a laser ``giant pulse'' on a surface in a vacuum was studied. A simple pendulum was used for measuring the momentum. Data obtained for Be, C, Al, Zn, Ag, and W show the light intensity which gives maximum momentum transfer per unit of laser energy, and the decrease in momentum transfer as the light intensity is increased. The maximum shock pressures generated in the target materials were estimated to range from 6×105 to 106 bars, depending on the material.
DISCLAIMERThie report wee prepared u an account of work tponeond by an agency of the UsJted SUM Government Netthw the Uaited Sutaa Oonmment swr any aneocy thereof, nor any of their iwHcyin, makae any warranty, txpreM or implied, or ajramei any legal liability or tatsontieiifcy for the aonracy, completeneM, or HHMMI of any infornation, appantw, product, or prooe* djedoeed, or reprmati that iti ma would not infringe privately owned rithu. Refer ence herein to any apeeiffc commercial product, proowi, or aervice by trade name, trademark, BtaMfactarer, or otherwiee doei not aeceewrily eonttitute or imply itt endonement, recommendatioe, or favoriat by the United Sutaa Oovernmaat or any agency thereof. Vx> viewi awl opinion* of authon eupmeed herein do not neceeserily Mate or reflect tboee of the United Statu Gwei-int or any anency thereof. LAWRENCE LIVERMORE NATIONAL LABORATORY Executive tUnder the direction of the Office of Civilian Radioactive Waste Management, the Department of Energy's (DOE) Nevada Nuclear Waste Storage Investigations (NNWSI) project is evaluating a candidate repository site at Yucca Mountain, Ne vada, for permanent disposal of high level nuclear waste. The Lawrence Livermore National Labora tory (LLNL), a participant in the NNWSI project, is developing waste package designs to meet NRC requirements. Included are designs for the refer ence waste form configurations of: (1) spent fuel (SF), which consists of both consolidated and un consolidated spent fuel rods from pressurizedwater-reactor (PWR) and boiling-water-reactor (BWR) assemblies, (2) commercial high level waste (CHLW), as a borosilicate glass containing commercial spent fuel reprocessing wastes, and (3) West Valley/defense high level waste (WV/ DHIW) immobilized in borosilicate glass. Refer ence and alternative package designs have been developed for each waste form for both vertical and horizontal emplacement configurations. All designs are for emplacement in a tuff repository located above the water table (in the vadose zone).Conceptual designs and analyses for waste packages in tuff below the water table were devel oped for the Office of Nuclear Waste Isolation Summary (ONWI) by Westinghouse Electric Corporation in 1981 -82 (Westinghouse, 1983. The candidate hori zon was changed by NNWSI to the vadose zone in late 1982 (Vieth, 1982;Dudley and Erdal, 1982). LLNL has made changes in and additions to the conceptual designs to reflect this change in the re pository location. Analyses have been performed to determine conformance of the selected design ensemble to NRC design requirements in the cur rently understood repository environment. Fig ure 1 shows the reference conceptual designs. The selected designs (Gregg and O'Neal, 1983) include reference and alternative designs that vary in com plexity, performance, and cost.From this ensemble, one set of designs (for SF, CHLW, and WV/DHIW) will be chosen which is expected to meet Nuclear Regulatory Commission (NRC)/Environmental Protection Agency (EPA) requirements when analyzed with accura...
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