The invention related to heat energy device by using coal, garbage, and biomass as fuel. The firing system is composed of fuel supply system, water vapor input unit, gasification firebox, hearth, water-cooling type or wind-cooling type fire grate in up layer, fixed grate or moving grate in low layer, primary and secondary air supply arrangement etc. Gasification firebox is in quasi-closed position. Water vapor input unit includes water vapor nozzle or plasma generator. In gasification firebox, solid fuel carries out following procedures: preheating, drying, gasifying, desulfurizing, dechloridizing, burning by exsilient volatile, and burning from fuel bed. Passing through full hot fuel bed on fire grate in up layer, flue gas in high temperature enters into hearth to carry out second time of burning so as to eliminating coal smoke. Being fed to gasification firebox, water vapor is in use for restraining generation of coal smoke to implement clean burning and value added burning.