Dependence of fixed-bed reaction processes on bed void distribution

Conference · Wed Jan 01 04:00:00 EST 1992

OSTI ID:5670295

Hobbs, M L ^[1]; Radulovic, P T; Smooot, D L ^[2]

---

1. Sandia National Labs., Albuquerque, NM (United States)
2. Brigham Young Univ., Provo, UT (United States)

Variations of bed void fraction in a full-scale, reacting, fixed-bed coal gasifier have been deduced from measured axial pressure profiles obtained during gasification of seven coal types ranging from lignite to bituminous. Packed-bed pressure correlations were used to calculate the void fractions based on monotonic polynomial fits of measured pressure profiles. Insights into the fixed-bed combustion processes affected by the void distribution were obtained by a one-dimensional, steady-state, fixed-bed combustion model. Predicted temperature profiles from this model compare reasonably well to experimental data. The bed void distributions are not linear but are perturbed by vigorous reactions in the devolatilization and oxidation zones. Results indicate that a dramatic increase in temperature and associated gas release causes the bed to expand and the gas void space to increase. Increased void space localized in the combustion zone causes the steep temperature gradient to decrease and the location of the maximum temperature to shift. Also, large feed gas flow rates cause the void fraction in the ash zone to increase.

• Research Organization: Sandia National Labs., Albuquerque, NM (United States)
• Sponsoring Organization: DOE; USDOE, Washington, DC (United States)
• DOE Contract Number: AC04-76DP00789; AC21-86MC23075
• OSTI ID: 5670295
• Report Number(s): SAND-91-2695C; CONF-920707--16; ON: DE92006678
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
20 FOSSIL-FUELED POWER PLANTS
200104 -- Fossil-Fueled Power Plants-- Components
99 GENERAL AND MISCELLANEOUS
990200 -- Mathematics & Computers
COAL GASIFICATION
COAL RANK
GASIFICATION
MATHEMATICAL MODELS
ONE-DIMENSIONAL CALCULATIONS
PACKED BEDS
PRESSURE MEASUREMENT
THERMOCHEMICAL PROCESSES
VOIDS