NOVELTY - A preheating arrangement has a channel (27) from afterburner (14) to sulfur removal unit (3) for directing exhaust gas to the sulfur removal unit and an outlet channel (27') for removing exhaust gas from the sulfur removal unit; and/or a channel (29) from the afterburner to modifying unit (4) for directing exhaust gas to modifying unit and an outlet channel (29') for removing exhaust gas from the modifying unit. The outlet channel of the sulfur removal unit and/or the outlet channel of the modifying unit are provided with adjustment mechanisms (30) and heat exchangers (31).    USE - For a fuel cell apparatus, such as solid oxide fuel cells (SOFC) or molten carbonate fuel cells (MCFC).    ADVANTAGE - The system can be started at least partly or totally without external electrical heating. Fuel and/or reactor vessels can be preheated without electricity produced by the fuel cells themselves; and the reactor vessels can be heated during operation without need for external electricity or electricity produced by the fuel cells.    DETAILED DESCRIPTION - The preheating arrangement in fuel cell apparatus comprising at least a fuel cell unit (6), fuel inlet and oxygen-containing air inlet, sulfur removal unit, fuel modifying unit and burner for combusting exhaust gases from anode and/or cathode side, includes a channel from afterburner to sulfur removal unit for directing exhaust gas to the sulfur removal unit and an outlet channel for removing exhaust gas from the sulfur removal unit; and/or a channel from the afterburner to modifying unit for directing exhaust gas to modifying unit and an outlet channel for removing exhaust gas from the modifying unit. The outlet channel of the sulfur removal unit and/or the outlet channel of the modifying unit are provided with an adjustment mechanism and a heat exchanger. The afterburner is provided with a separate fuel inlet channel (24) for introducing fuel to the afterburner during the start-up phase of the fuel cell apparatus. An INDEPENDENT CLAIM is included for a method of preheating the fuel cell apparatus.    DESCRIPTION OF DRAWING(S) - The figure shows a simplified and schematic view of a preheating arrangement in a fuel cell apparatus.    Sulfur removal unit (3)    Modifying unit (4)    Fuel cell unit (6)    Afterburner (14)    Fuel inlet channel (24)    Channels (27, 29)    Outlet channels (27', 29')    Adjustment mechanism (30)    Exchanger (31)