Combustion in crater beds

Energy efficiency and environmental impact of biogas utilization in landfills

“…In these cases, new techniques involving heatrecirculating particulate beds such as fluidized bed, spouted bed and crater bed have been introduced in order to overcome the limitations (Malik et al, 1987). The LFG conversion in electric power is implemented by engine/generator system (mostly 1 to 5 MW) that needs supply of a dried gas, with pressure capacity at least 50 mbar (Augenstein and Pacey, 1992).…”

Heat transfer in a crater bed

“…With the heat recirculation feature of the crater bed, low calorific value gaseous fuel or ultra-lean fuel mixtures could be effectively burnt without supplementing fuel to sustain the flame. This is because the preheating effect, mentioned above, offers a reaction temperature much higher than that correspond to the normal adiabatic flame temperature of premixed reactants, which results in an increase of reaction rate [3]. Residual fuel oil, as reported by Malik et al [3] for a laboratory scale crater bed, was introduced into the bed by either dropping from a funnel in annulus region or by using a climbing film in a separate tube supplying a small supplementary air stream from below.…”

“…The study of hydrodynamics, combustion and heat transfer characteristics of the crater bed have been reported elsewhere [1][2][3][4][5]. Malik et al [3] presented that the patterns of fountain and the form of the crater also depend on change in gas flow rate, dimension and location of a nozzle and characteristics of the particles.…”

“…Malik et al [3] presented that the patterns of fountain and the form of the crater also depend on change in gas flow rate, dimension and location of a nozzle and characteristics of the particles. Based on visual observation, Tia et al [4] reported that the size and depth of crater formed and the height of ascending fountain increased with gas flow rate or its momentum flux, but decreases as sand size increases due to its gravity effect.…”

“…Applied as a combustor, the crater bed can be used both with gaseous fuel entering through the nozzle and with only oxidant introduced in that way, solid or liquid fuel being fed into the bed by using a separated pipe [3]. The gaseous fuel-air mixture was fed through a vertical tube, whose outlet end nozzle points downward to the surface of an inert particle bed.…”