NOVELTY - A fuel processor comprises a gas stream path along which a mixture of gaseous hydrocarbon compound, water vapor and oxygen is passed for catalytic combustion. A catalytic partial oxidation (CPO) catalyst is included in the path. After the CPO, the mixture is passed through a number of high temperature (HT) shift units arranged in series in the path downstream of the CPO catalyst.    USE - For producing a gas stream containing hydrogen. The processor is suitable for use in microthermal power units in the domestic environment.    ADVANTAGE - The fuel processor generates a gas stream which comprise less carbon monoxide than the conventional fuel processors.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for an apparatus for generating a third and fourth gas stream from a first and second gas stream. The third stream comprises a mixture of the first and second streams provided with a chamber enclosing a space in which a ventilator is included. The chamber is provided with a first and second inflow opening for supplying the first and second gas streams to the first and second inflow and outflow openings respectively. The first and second streams are sucked in by the ventilator and are separated from each other in the chamber to the first and second outflow openings respectively. The first outflow opening discharges into a first outlet and the second outflow opening discharges into the first and the second outlets via a bifurcation controllable valve. The valve adjusts the ratio of the amount of the gas originating from the first and second gas streams in the third gas stream from the first outlet. The fourth gas stream comprises a part of the second gas stream flowing through the second outlet.    DESCRIPTION OF DRAWING(S) - The figure shows a fuel processor.    fuel processor (1)    vessel (2)    inlet (4)    water (6)    mixture (8)    outlet (9)    heating element (10)    catalyst (11)    water outlet (12)    line (14)    high temperature shifts (16.1 - 16.3)    inner wall (18)    space (20)    shift inlet (22)    shift outlet (24)    direction (26)    box-shaped chamber (28)    bottom wall (30)    upright side wall (32)    space (34)    outer wall of the heat exchanger (36)    low temperature shift (38)    inlet (40)    steam generator (42)    insulating outer wall (44)    cooling water (45)    preferential oxidation catalyst (PrOx) (46)    steam (47)    inlet for adding oxygen (48)    lines (49,50,50')    fuel cell (52)    heat exchanger. (54)