NOVELTY - Preparing process system for performing a process for continuously converting carbonaceous material contained in one or more feedstocks into a liquid hydrocarbon product, involves converting at least part of the carbonaceous material by: pressurizing feed mixture to an operational pressure in the range of 221-400 bar; heating the feed mixture to an operational temperature in the range of 300-450 degrees C; cooling the feed mixture; and expanding the feed mixture to a pressure in the range of 1-70 bar; and separating from the converted feed mixture a fraction comprising liquid hydrocarbon product.    USE - The method is useful for preparing process system for performing process for continuously converting carbonaceous material contained in one or more feedstocks into liquid hydrocarbon product (claimed).    ADVANTAGE - Improved process and apparatus are provided for producing liquid hydrocarbons from carbonaceous materials in an efficient, economical and environmentally sustainable way.    DETAILED DESCRIPTION - Preparing a process system for performing a process for continuously converting carbonaceous material contained in one or more feedstocks into a liquid hydrocarbon product, the feedstocks including the carbonaceous material being in a feed mixture including one or more fluids, the fluids including water, involves converting at least part of the carbonaceous material by: pressurizing the feed mixture to an operational pressure in the range of 221-400 bar; heating the feed mixture to an operational temperature in the range of 300-450 degrees C, and maintaining the pressurized and heated feed mixture in the desired pressure and temperature ranges in a reaction zone for a predefined time; cooling the feed mixture to a temperature in the range 25-200 degrees C; and expanding the feed mixture to a pressure in the range of 1-70 bar, thus causing the carbonaceous material to be converted to a liquid hydrocarbon product; and separating from the converted feed mixture a fraction comprising liquid hydrocarbon product; where the preparation method comprises, filling the system with fluid different from the feed mixture while the system being at a temperature and a pressure below the operational temperature and pressure, and subsequently pressurizing the fluid to at least 90% of the operational pressure and further increasing the temperature at a predetermined heating rate in the range of 1 to 10 degrees C/minute, where the pressure is constantly kept at a level above the saturation pressure for the fluid at a given temperature, and where upon reaching the operational temperature and pressure the fluid inflow to the pressurization is terminated and the feed mixture inflow to the pressurization is initiated. An INDEPENDENT CLAIM is included for an apparatus for performing a process for continuous conversion of carbonaceous material contained in one or more feedstocks into a liquid hydrocarbon product, the carbonaceous material being in a feed mixture including the carbonaceous material and one or more fluids, the fluids including water, where the apparatus comprises at least one feed pump for feeding the feed mixture into the processing zone; a pressurization device adapted to pressurize the feed mixture to a pressure of 150-400 bar; a heating device adapted to heat the pressurized feed mixture to a 30 temperature of 300-450 degrees C; a conversion device adapted to hold the pressurized and heated feed mixture for a conversion time of 10-40 minutes; a cooling device adapted to cool the treated feed mixture to a temperature of 25-200 degrees C; an expansion device adapted to reduce the pressure of the treated feed mixture to a pressure of 1-70 bar; and a separation device adapted to separate a liquid hydrocarbon product from the treated and successively cooled and expanded feed mixture; where further in order to perform the method, valves are provided for closing of the inflow of feed mixture to the pressurization device and for opening the inflow of a fluid to the pressurization device, and where a control system is provided, with at least one pressure sensor and at least one temperature sensor for providing input to a central control unit and where the control unit provides control signals for the valves for closing and opening, respectively, and for the pressurization device and the heating device, to comply with the process.