F23B—METHODS OR APPARATUS FOR COMBUSTION USING ONLY SOLID FUEL
F23B50/00—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone
F23B50/02—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel forming a column, stack or thick layer with the combustion zone at its bottom
F23B50/06—Combustion apparatus in which the fuel is fed into or through the combustion zone by gravity, e.g. from a fuel storage situated above the combustion zone the fuel forming a column, stack or thick layer with the combustion zone at its bottom the flue gases being removed downwards through one or more openings in the fuel-supporting surface