NOVELTY - The method comprises dividing the sewage gas (raw gas) into two partial flows (T1, T2) of different quantities, placing the smaller partial flow (T2) under vacuum, drawing water from a drier (A1 or A2) to enrich the smaller partial flow, feeding the two partial flows or the larger partial flow (T1) into a first washing stage (K1), precipitating solid materials present in the raw gas, such as polar silane and siloxane compounds, ammoniac, and other compounds, and carrying out a subsequent second washing stage (K2) to remove carbon dioxide, hydrogen sulfide and nonpolar siloxanes.    USE - Method for converting sewage gas, such as occurs in the digestion tower or a sewage treatment plant, into fuel gas by the separation of carbon dioxide, silicon compounds and impurities.    ADVANTAGE - The method is capable of energy-efficiently obtaining a fuel gas with a high fuel value in an economical manner, without significant losses of methane using a device having low manufacturing and installation costs.    DETAILED DESCRIPTION - The method comprises dividing the sewage gas (raw gas) into two partial flows (T1, T2) of different quantities, placing the smaller partial flow (T2) under vacuum, drawing water from a drier (A1 or A2) used for removing moisture from the purified raw gas to enrich the smaller partial flow, feeding the two partial flows or the larger partial flow (T1) into a first washing stage (K1), precipitating solid materials present in the raw gas, such as polar silane and siloxane compounds, ammoniac, and other compounds, carrying out a subsequent second washing stage (K2) to remove carbon dioxide, hydrogen sulfide, nonpolar siloxanes and further impurities from the pre-purified raw gas by a washing solution heated to 80 degrees C and comprising amines (10%), dehumidifying the purified raw gas to a dew point of below -10 degrees C in a final drying stage (A), and absorbing any high-molecular hydrocarbons still present. The partial flows are divided in a ratio of 5:1 to 100:1. The smaller partial flow is condensed and a vacuum of 0.1-500 mbar is produced. The two partial flows are brought together before the introduction into the first washing stage. The washing waters of the first washing stage is driven in the cycle and is cooled by heat exchanger so that the pre-purified raw gas is discharged with a temperature of 10-30 degrees C. The control parameters, electrical conductivity and pH value of the water are monitored and adjusted in the first washing stage via the pumping pressure and the temperature of the washing water. The amine-containing washing solution is fed with an increased temperature of 30 degrees C and is heated by the heat reaction resulting during the washing process. The pre-purified raw gas in the second washing stage flows through a packing bed with a surface of 200-1200 m2/m3. The polluted washing solution is renewably regenerated, where an adsorption filtering medium flows through with increased temperatures of 115-160 degrees C. An INDEPENDENT CLAIM is included for a device for converting sewage gas into fuel gas.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a device for converting sewage gas into fuel gas (Drawing includes non-English language text).    Final drying stage (A)    Drier (A1, A2)    First washing stage (K1)    Second washing stage (K2)    Larger partial flow (T1)    Smaller partial flow. (T2)