PROBLEM TO BE SOLVED: To provide a combustion device and method for solid fuel having improved combustion efficiency, a gas heating device, a liquid heating device, a power generation system and a cooling system.SOLUTION: A combustion device 100 for solid fuel includes: a combustion furnace 20 for combusting solid fuel; and an exhaust device 42 configured to exhaust flue gas discharged from a discharge port 24 of the combustion furnace 20. The combustion device also includes an exhaust passage provided between the discharge port 24 of the combustion furnace 20 and the exhaust device 42, and configured to exhaust flue gas; an oxygen supply passage 70 connected to the exhaust passage, and configured to supply gas containing oxygen; and an ignition part 54 provided in the exhaust passage. The flue gas is mixed with gas containing oxygen supplied from the oxygen supply passage 70, and combusted by fire induced by the ignition part 54.SELECTED DRAWING: Figure 2
