Method and plant for production of a fuel gas from waste

A method for thermal treatment and chemical transformation of waste comprising natural and synthetic carbonaceous materials for generation of a fuel gas for further use, the method comprising the following steps:

• a. adjusting the humidity of the carbonaceous materials to a predetermined level by drying or introduction of water or steam into the carbonaceous material,
• b. introduction of the humidified carbonaceous material into thermolysis and pyrolysis reactor(s), in which the materials are thermally treated to produce a raw pyrolysis and thermolysis gas and a carbonaceous solid rest,
• c. introduction of the carbonaceous solid rest from step b) and steam into a conversion unit to cause partial gasification of solid carbonaceous material therein to produce a synthesis gas comprising hydrogen, CO and CO2 that is withdrawn and introduced into a second scrubbing section and a solid rest that is withdrawn for further treatment or disposal,
• d. introducing the raw thermolysis and pyrolysis gas from step b) into a first gas cleaning unit where the gas is separated into a first light oil fraction having a boiling range from 170 to 350° C. at atmospheric pressure, and a scrubbed raw gas fraction mainly comprising H, CO, CO2 and hydrocarbons having a boiling range below 170° C.,
• e. introducing the scrubbed raw gas fraction into a first gas separation unit where the raw gas is separated into a hydrogen enriched gas fraction and a and a low hydrogen fraction,
• f. introduction of the low hydrogen fraction into the conversion unit to be converted together with the solids therein,
• g. introducing the hydrogen enriched fraction into the second separation unit, wherein the hydrogen enriched fraction and the synthesis gas of step c) are separated in a second light oils fraction, having a boiling range of 100 to 200° C. at atmospheric pressure, and a synthesis gas fraction that is withdrawn through a synthesis gas line
• wherein the method further comprises
• h. recycling of the first light oils fraction from step d) into the thermolysis and pyrolysis reactor(s).