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U.S. Department of Energy
Office of Scientific and Technical Information

An engineering model for coal devolatilization

Technical Report ·
OSTI ID:5600543

There are three different modeling projects in this program: (1) an expedient reaction model for coal devolatilization for large scale combustor simulators; (2) a theoretical framework to explain the behavior of different coal types; and (3) an analysis of the chemistry, heat and mass transport in the vicinity of individual coal particles, to begin to describe the initial stages of the combustion of entrained coal particles. The engineering model, called FLASHTWO, was developed before this program began, and has been validated against several wire-grid studies of HVA bituminous coals. Parameters for FLASHTWO for various coal types have been assigned to reproduce the predictions from the full depolymerization model developed in Task 2, and used in the simulations of the initial stages of pulverized coal combustion in Task 3. A depolymerization model has been developed which rationalizes all aspects of coal type effects on rapid coal devolatilization. The theory is called FLASHCHAIN. Task 3, the analysis of the initial stages of pulverized coal combustion, was pursued in two stages. One study omits homogenous chemistry entirely, and focuses on the transport analysis including primary devolatilization, convective heat and mass transport, heterogeneous oxidation at the particle surface. The second study illustrates volatiles combustion in the limit of diffusion-limited combustion rates. This rate analysis if formulated in terms or primary devolatilization, convective heat and mass transport, homogeneous combustion of tar and noncendensibles in a flame sheet, and heterogeneous oxidation at the particle surface.

Research Organization:
Stanford Univ., CA (United States). High Temperature Gasdynamics Lab.
Sponsoring Organization:
DOE; USDOE, Washington, DC (United States)
DOE Contract Number:
FG22-88PC88900
OSTI ID:
5600543
Report Number(s):
DOE/PC/88900-T2; ON: DE91011274
Country of Publication:
United States
Language:
English