Determination of the kinetics of hydrogasification of char using a thermobalance

Conference · Sun Sep 10 04:00:00 EDT 1978 · Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States)

OSTI ID:6155788

Chauhan, S P; Longanbach, J R

Kinetic data were obtained on a thermobalance for hydrogasification of chars produced in a dilute phase hydrogasifier, for designing a scaled-up, direct, fluid-bed hydrogasification reactor for the Hydrane process. Two distinct kinetic regimes were observed at any set of conditions. The first regime corresponded to rapid hydrogasification of volatile matter as well as some base carbon and was over in less than 2.5 minutes. For this regime the yield of base carbon conversion was practically independent of gas velocity, particle size, and char type. The yield increased continuously with p/sub H2/ which was the most important variable. The yield was independent of PCH. Apparently the rate of the forward reaction between coal carbon and H/sub 2/ was much higher than the rate of cracking of CH/sub 4/ at all conditions. Increasing the temperature resulted in an increase in yield until about 800 C, after which it did not change. The second kinetic regime corresponded to slow hydrogasification of base carbon. A kinetic model properly accounted for the continuous deactivation of char with increasing fractional conversion. The rate of deactivation was lower at higher temperature and p/sub H2/. Again, the char preparation temperature did not affect the reactivity. But, there were two unexpected results: first, the initial rate of hydrogasification, k/sub 2/, increased with particle size; and second, the Pittsburgh No. 8 chars were more reactive than Illinois No. 6 chars. It is possible that these unexpected results can be explained on the basis of differences in surface properties, such as surface area, average pore size, etc. Although the surface properties of Hydrane char may be different from those of preoxidized chars, the initial activation energy and rate of deactivation with level of conversion are not. Also, it cannot be conclusively shown that the initial rate of gasification of Hydrane chars is higher than that of preoxidized coal chars.

• Research Organization: Battelle's Columbus Labs., OH
• OSTI ID: 6155788
• Report Number(s): CONF-780902-P1
• Conference Information: Journal Name: Am. Chem. Soc., Div. Fuel Chem., Prepr.; (United States) Journal Volume: 23:3
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
010404* -- Coal
Lignite
& Peat-- Gasification
ACTIVATION ENERGY
ALKANES
CHARS
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMICAL REACTORS
COAL GASIFICATION
CRYOGENIC FLUIDS
DESIGN
ELEMENTS
ENERGY
FLUIDS
GASIFICATION
GRAVIMETRIC ANALYSIS
HYDRANE PROCESS
HYDROCARBONS
HYDROGEN
HYDROGENATION
KINETICS
METHANE
NONMETALS
ORGANIC COMPOUNDS
PARTICLE SIZE
QUANTITATIVE CHEMICAL ANALYSIS
REACTION KINETICS
SIZE
SNG PROCESSES
TEMPERATURE DEPENDENCE
THERMAL ANALYSIS
THERMAL GRAVIMETRIC ANALYSIS
THERMOCHEMICAL PROCESSES
VELOCITY
YIELDS