A mechanistic model for axisymmetric UCG (underground coal gasification) cavity growth

Conference · Tue Jul 01 04:00:00 EDT 1986

OSTI ID:6457570

Thorsness, C B; Britten, J A

A three-dimensional, axisymmetric model to describe cavity growth during underground coal gasification (UCG) has been developed. The model makes use of a few basic assumptions concerning dominant heat and mass transfer processes in various zones of the cavity, and employs no arbitrary parameters of significant impact. Other features of the model include the capability to follow the evolution of the cavity from near start-up to exhaustion, and explicit coupling of wall and roof surface growth mechanisms. The model assumes that the cavity consists of up to three distinct rubble regions and a void space. Resistance to injected gas flow from a point low in the coal seam is assumed to be concentrated in the ash pile surrounding this point. A zone of relatively higher permeability is assumed to exist at the ash/coal wall interface, and rock and char rubble flow resistances are assumed negligible. Flow of injected gas through the ash is coupled by material and energy balances to cavity growth at the rubble/coal, void/coal and void/rock interfaces using previously developed submodels. The model is capable of simulating a wide range of coal and overburden compositions and stratigraphy, as well as water influx. In this paper, the model is described, the method of solution of the model equations is outlined, and the results of preliminary simulations are discussed. 9 refs.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6457570
• Report Number(s): UCRL-94419; CONF-860822-3; ON: DE87011570
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
CAVITIES
CHEMICAL COMPOSITION
CHEMICAL REACTIONS
COAL DEPOSITS
COAL GASIFICATION
COAL SEAMS
ENERGY TRANSFER
GASIFICATION
GEOLOGIC DEPOSITS
GEOLOGY
GROWTH
HEAT TRANSFER
IN-SITU GASIFICATION
IN-SITU PROCESSING
MASS TRANSFER
MATHEMATICAL MODELS
MINERAL RESOURCES
OVERBURDEN
PROCESSING
RESOURCES
STRATIGRAPHY
THERMOCHEMICAL PROCESSES
WATER INFLUX