NOVELTY - Producing liquid hydro carbonaceous product (1) such as bio fuel from solid biomass (2), involves a gasifying step for gasifying solid biomass in a gasifier (6) to produce raw synthesis gas (3); conditioning of the raw synthesis gas to purify the raw synthesis gas to obtain purified synthesis gas having a molar ratio of hydrogen to carbon monoxide of 2.5 to 1 and 0.5 to 1, preferably 2.1 to 1 and 1.8 to 1,especially 2 to 1; and subjecting purified synthesis gas (4) to a Fischer-Tropsch synthesis in a Fischer- Tropsch reactor to produce liquid hydro carbonaceous product.    USE - For producing liquid hydro carbonaceous product such as liquid biofuel.    ADVANTAGE - In the method several gasifiers are used for producing raw synthesis gas, which increases the uptime of the process because this makes possible an ongoing Fischer-Tropsch synthesis even if one of the gasifiers is not producing raw synthesis gas; increases the capacity of the process; and also combining gasifiers gasifying liquid and solid biomass helps in controlling the incoming biomass material flow.    DETAILED DESCRIPTION - Producing liquid hydro carbonaceous product (1) such as bio fuel from solid biomass (2), involves a gasifying step for gasifying solid biomass in a gasifier (6) to produce raw synthesis gas (3); conditioning of the raw synthesis gas to purify the raw synthesis gas to obtain purified synthesis gas having a molar ratio of hydrogen to carbon monoxide of 2.5 to 1 and 0.5 to 1, preferably 2.1 to 1 and 1.8 to 1,especially 2 to 1; and subjecting purified synthesis gas (4) to a Fischer-Tropsch synthesis in a Fischer- Tropsch reactor to produce liquid hydro carbonaceous product. The gasification includes gasifying of solid biomass in a gasifier involves a fluidized bed reactor, and in that oxygen and steam are used as fluidizing medium in the fluidized bed reactor; addition tail gas from the Fischer-Tropsch reactor as gasification and fluidizing medium in the fluidized bed reactor; using a lock hopper for feeding solid biomass to the gasifier; feeding the raw synthesis gas into a first particle separator for performing a particle separation for separating particles such as ash, char and bed material from the raw synthesis gas; conditioning of the raw synthesis gas including catalytic treatment of the raw synthesis gas in a reformer for converting tar and methane present in the raw synthesis gas into carbon monoxide and hydrogen. An INDEPENDENT CLAIM is included for apparatus comprising a gasifier for gasifying solid biomass to produce raw synthesis gas, means for conditioning of the raw synthesis gas to obtain purified synthesis gas; and a Fischer-Tropsch reactor to produce liquid hydro carbonaceous product of the purified synthesis gas.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of apparatus.    Liquid hydro carbonaceous product (1)    Solid biomass (2)    Raw synthesis gas (3)    Purified synthesis gas (4)    Gasifier (6)