NOVELTY - The system comprises a partial oxidation unit (110) and a heat exchanger unit. The partial oxidation unit is: configured to receive raw syngas (104) and oxygen, configured to produce a processed syngas depleted of the heavy hydrocarbons, configured to receive steam and configured to process raw syngas using thermal partial oxidation and catalytic partial oxidation; and fluidly coupled to a well head of a production well of an underground coal gasifier, coupled to an oxidant supply unit that provides oxygen to the underground coal gasifier and coupled to an air separation unit.    USE - The system is useful for removing heavy hydrocarbons from raw syngas produced by underground coal gasification, where the heavy hydrocarbons are tar, phenol and creosotes.    ADVANTAGE - The system easily removes the heavy hydrocarbons from raw syngas.    DETAILED DESCRIPTION - The system comprises a partial oxidation unit (110) and a heat exchanger unit. The partial oxidation unit is: configured to receive raw syngas (104) and oxygen, configured to produce a processed syngas depleted of the heavy hydrocarbons, configured to receive steam and configured to process raw syngas using thermal partial oxidation and catalytic partial oxidation; and fluidly coupled to a well head of a production well of an underground coal gasifier, coupled to an oxidant supply unit that provides oxygen to the underground coal gasifier and coupled to an air separation unit. The heat exchanger unit is configured to allow heat exchange between the processed syngas and water to produce steam. The partial oxidation unit: is further fluidly coupled to an acid gas removal unit (150) that is configured to receive a portion of the processed syngas and to produce a Fischer Tropsch fluid, synthetic natural gas, town gas, reducing gas, oxo synthesis fluid, dimethyl ether, hydrogen, methanol, mixed alcohols, ammonia and/or fuel gas for power generation; and is further configured to receive a portion of the steam, configured to convert the heavy hydrocarbons to additional syngas and configured to receive a co-feed hydrocarbon or other fluid other than raw syngas. The processed syngas is depleted of methane, and comprises the additional syngas and less than 1 vol.% of heavy hydrocarbons. INDEPENDENT CLAIMS are included for:    (1) a system for conditioning an underground gasification syngas stream; and    (2) a method of removing heavy hydrocarbons from raw syngas produced by underground coal gasification.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a system for conditioning an underground gasification syngas stream.    Raw syngas (104)    Partial oxidation unit (110)    Resulting steam (122)    Waste fluid (134)    Acid gas removal unit. (150)