Optimization of Solid Circulation Rate in Compartmented Fluidized Bed Gasifier for Power Generation

Abstract

Abstract:The present paper reports the optimization of solid circulation rate (SCR) in Compartmented Fluidized Bed Gasifier (CFBG), an indirectly heated fluidized bed that incorporates two sets of v-valves and risers to control the solid circulation across the two compartments, i.e. combustor and gasifier of a pilot plant scale (the height and ID are 1.8m and 0.66m respectively). Sand was used as inert fluidized by air. Four operating variables were studied i.e. bed height, riser, v-valve and main bed flowrate. Based on 2 4 full factorial design of experiment in Yates' algorithm, at confidence level ≥ 95%, ANOVA analysis has revealed six important effects. The steepest ascent method was applied on linear regression generated from these effects to design the subsequent optimization experiments. The optimum values of SCR have been estimated for both low and high bed level at specific operating parameters.

Minimum and Complete Fluidization Velocity for Sand-Palm Shell Mixtures, Part II: Characteristic Velocity Profiles, Critical Loading and Binary Correlations

“…(Chok et al, 2009a) Figure 3 shows the U mf and U cf profiles in the combustor at various palm shell sizes and weight percent with finest sand of 196 µm. For the smallest size palm shell of +1.18-2.36 mm, both the U mf and U cf values remain unchanged from the values of pure sand as in (Chok et al, 2009a). Similarly, for medium size palm shell of +2.36-4.75 mm, these values remain constant except at 15 wt%.…”

“…As the apparatus for this study is the same as described in (Chok et al, 2009a), only a brief description is included here. A schematic of the experimental setup is illustrated in Fig.…”

“…combustor and gasifier by a vertical wall in 2:1 cross-sectional area ratio. The effective diameters, D e are computed as 25.7 and 41.3 cm for gasifier and combustor respectively (Chok et al, 2009a).…”

“…As described later, it is recognized that there are some instances where the mixtures U mf and U cf values remain nearly unchanged from its pure sand values. (3) pressure regulator; (4) rotameter; 5: plenum; (6) perforated distributor; (7) combustor; (8) gasifier; (9) manometer (Chok et al, 2009a) This regime of constant U mf and U cf values can be observed in both compartments and can be established depending on the bed properties. It is desirable to establish this regime for each compartment since the mixture characteristic velocities can be pre-determined using the bed material properties made up from entirely pure sand (inert) values.…”

“…However, the addition of a second fluidizable material (sand) in palm shell can facilitate proper fluidization. In Part I of this research (Chok et al, 2009a), the main features of the fluidization behaviour and characteristic velocities using sand-palm shell mixtures were examined with respect to different bed properties. Their distinct patterns and further analysis on the various characteristic velocity relationships provide insights on the fluidization mechanism and the mixing/segregation tendency.…”