Abstract: Various smoke and combustible gas combustors (200, 300) are disclosed, and also disclosed are systems (100, 200) combining gas combustor with inventive burner. Such a burner (100 or 100′) provides combustion of a particulate fuel such as sawdust, and many types of varying moisture content biomass fuels such as poultry litter. The combustors and burners exhibit a high turndown ratio [‘TDR”].