Plant for energy recovery from biomass and wastes, supplying e.g. fuel cells or gas engines, dries, pyrolyzes and ashes, whilst cracking and reacting gases to non-condensable forms

摘要

The feedstock (1) is heated at 100-150[deg]C, removing its stoichiometrically-defined water content, which is used subsequently in gasification and cracking processes. In a second zone, the solids are heated to 500[deg]C, producing pyrolysis gas. The residue, largely a soft coke, is transferred down to a further, indirectly-heated zone at 800[deg]C, where it is endothermically gasified with steam. The product gas is extracted co-currently with the solids. In a fourth, lower reaction zone this gas is heated to more than 1000[deg]C. Condensable hydrocarbons (CmHn) are converted in the presence of water vapor, by cracking processes, largely to non-condensibles (CO and H2). In a fifth zone, near-stoichiometric additions of oxygen ash the carbonaceous residues. The cascade reactor employed, is a staged- or grid reactor. The fifth zone is in a subsequent unit; it takes account of the melting behavior of inorganic substances (slagging is recognized). Indirect heating employs steel tubes fired with the recycled process gas as fuel. In addition, some direct heating takes place, by supplying hot process gas directly into the reactor. A heating jacket is used for indirect heating. Processes at up to 500[deg]C are limited to one reactor, cracking and higher temperature process take place in others, outside the cascade reactor. Air or oxygen is supplied. Further details of operation in accordance with the foregoing principles are provided.