Reactivity of heat treated chars

Technical Report · Sat Jan 01 04:00:00 EST 1977

DOI:https://doi.org/10.2172/6777572· OSTI ID:6777572

Mahajan, O. P.

Reactivities of a number of chars produced from American coals varying in rank from lignite to anthracite have been measured in air, CO/sub 2/, steam and H/sub 2/. The variables chosen for the study were: rank of the parent coal, inorganic matter content, particle size, reaction temperature and pressure as well as heat treatment conditions used during char preparation. In all gasification atmospheres studied, reactivity plots for different chars are essentially of the same general shape and have three distinct regions. The reaction rate first increases slowly with time. The plot then goes through a maximum in slope, followed by a lengthy region of decreasing slope as burn-off approaches 100 percent. The shape of the burn-off curves can be explained on the basis of what is known about the development of porosity and surface area in microporous chars as they undergo gasification. Using an adjustable time parameter, equations have been developed which successfully correlate the reactivity data. Char reactivity decreases, in general, with increase in rank of the parent coal. Reactivities of chars in air, CO/sub 2/ and steam increase over 150-fold in going from a low volatile bituminous to a lignite parent coal; the spread in char reactivities in H/sub 2/ is only 30-fold. Removal of inorganic matter from coal precursors prior to their charring or from chars produced from the raw coals has a marked effect on char reactivity and surface area. Removal of inorganic matter (by acid washing) decreases, in general, reactivity of chars produced from lower rank coals, whereas reactivities of chars derived from higher rank coals increase.

• Research Organization: Pennsylvania State Univ., University Park (USA). Coal Research Section
• Sponsoring Organization: USDOE
• OSTI ID: 6777572
• Report Number(s): FE-2030-TR8
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010600* -- Coal
Lignite
& Peat-- Properties & Composition
AIR
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBONACEOUS MATERIALS
CHALCOGENIDES
CHARS
CHEMICAL REACTION KINETICS
COAL
COAL RANK
CRYOGENIC FLUIDS
ELEMENTS
ENERGY SOURCES
FLUIDS
FOSSIL FUELS
FUELS
GASES
GASIFICATION
HEAT TREATMENTS
HYDROGEN
KINETICS
MINERALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PRESSURE DEPENDENCE
REACTION KINETICS
SIZE
STEAM
TEMPERATURE DEPENDENCE