In situ coal gasification cavities - used for waste dump, gas, oil storage or waste heat recovery from carbonaceous ash

摘要

The cavities are filled from the surface by materials which either remain in them permanently or are temporarily stored and extracted from them later. The former use refers to dumps for nuclear waste, ash, refuse etc. The latter refers to materials which are injected by gaseous or liquid reagents and can undergo physical or chemical reactions in the cavities, or to the storage of gas, oil or water. This eliminates difficulties caused by surface subsidence if large cavities are left unsupported. It also saves any stowing operations with inert filling material introduced from the surface. In many cases, useful byproducts can be obtained (heat by passing air through carbon-containing ashes).