Heterogeneous Kinetics of Coal Char Gasification and Combustion

A brief description is given of devolatilization of raw coal and combustion of the residualchar. Major achievements in the study of devolatilization and important areas for further experimentation are noted; however, attention is focussed on the rate processes involved in char combustion. Means of calculating reaction rates are shown which account for temperatures of particles, mass transfer and diffusion of oxygen into the particle's pore structure, and reaction on the pore walls. Theoretical consideration is then given to the changes in the size, density, and pore structure of chars as they burn. Experimental data are shown for observed reactivities of coal chars corrected for external mass transfer effects, and intrinsic reactivities are reported for various coal chars and other carbons corrected for pore diffusion effects. Measured data on mass-transfer rates and changes in particle structure during combustion are given. Recommendations are made for further research on char reactivity and the manner in which pore structure develops during combustion. The need for combustion-oriented kinetics studies of coal develatilization is outlined.

The combustion rates of coal chars: A review

Soot formation in combustion

Combustion reactivity and morphological change in coal chars: Effect of pyrolysis temperature, heating rate and pressure

The review deals with a special kind of gas-filled polymeric materials: the syntactic polymer foams, or spheroplastics, consisting of a polymer matrix and a hollow spherical filler. The survey covers the following aspects: preparation and properties of polymeric hollow micro- and macrospheres; physical principles of syntactic foam formation: rheology, regulation of apparent density, space factor and packing of syntactic compositions; chemical and technological principles of formation; preparation of syntactic foams based on epoxy, polyester, phenol, polyimide, and other resins, as well as the newest types of foams — prepregs, poly-phase structures, elastomeric and reinforced foams. The specificity of physical properties and methods of calculation of strength parameters are discussed. Attempts are made to evaluate the effect and contribution of size and packing of spheres on the principal physical properties. The main applications and trends of syntactic foams are outlined.

I.W. Smith

Papers

The kinetics of combustion of pulverized semi-anthracite in the temperature range 1400–2200°K

Measured and calculated burning histories of large carbon spheres in oxygen