Biomass gasifier and gasification plant

摘要

A gasifier (7) comprises a generally upright cylindrical chamber (25) at least a lower part (25b) of which is defined by a body of refractory material (35); an inlet chamber (21) communicating with the top of the chamber (25), the inlet chamber being provided with two spaced-apart valve means (22, 23) which may be closed to inhibit ingress of air and may be opened successively to allow input of biomass. The refractory body (35) defines a throat (56) communicating with the bottom of the chamber (25), the throat comprising a tapered portion (56a) tapering at an angle of at least 50° to the horizontal to a cylindrical portion (56b) of diameter less than that of the chamber (25), and a lower portion (56c) increasing in diameter; the refractory body (35) also defines air inlet ducts (58) communicating with the chamber (25) above the throat (56). A grate (44) below the refractory body (35) comprises movable elements to assist passage of charcoal. Below the grate (44) is an outlet duct (54) for extraction of gas from the gasifier (7). The gasifier suppresses tar formation during gasification, and is suitable for treating waste wood.