NOVELTY - A gas cleaning system has first filter vessel(s) for removing a portion of particulate contained in a feedstock gas and removing a portion of halide(s) using sorbent(s) mixed with the feedstock gas; desulfurization system(s) for removing a portion of sulfur contained in the feedstock gas; and second and third filter vessels for removing contaminants contained in the feedstock gas.    USE - The inventive gas cleaning system is used for the cleaning of gases such as synthesis gas used for synthesis of chemicals (such as methanol, ammonia or hydrogen), fuel cell power generation, or integrated gasification combined cycle power generation.    ADVANTAGE - The inventive gas cleaning system is more efficient for removing contaminants from feedstock gas, e.g. syngas or other gases.    DETAILED DESCRIPTION - A gas cleaning system comprises:    (a) first filter vessel(s) capable of operating at a first temperature and removing a portion of particulates contained in the feedstock gas and capable of removing a portion of halide(s) using sorbent(s) mixed with the feedstock gas;    (b) desulfurization system(s) capable of operating at the first temperature for removing a portion of sulfur contained in the feedstock gas and positioned downstream of first filter vessel(s);    (c) second filter vessel(s) capable of operating at a second temperature that is less than the first temperature for removing a portion of contaminant(s) contained in the feedstock gas and positioned downstream of the desulfurization system(s); and    (d) third filter vessel(s) capable of operating at a third temperature that is less than the second temperature for removing a portion of contaminant(s) contained in the feedstock gas and positioned downstream of the second filter vessel(s).    An INDEPENDENT CLAIM is also included for a process for cleaning feedstock gas comprising:    (1) producing a feedstock gas;    (2) passing the feedstock gas at a first temperature to first filter vessel(s) where a portion of particulates contained in the feedstock gas in the first filter vessel and a portion of halide(s) contained in the feedstock gas in the first filter vessel(s) are removed from the feedstock gas by contacting the feedstock gas with sorbent(s) capable of removing halide(s) from the feedstock gas;    (3) passing the feedstock gas to a bulk desulfurization system where a portion of sulfur contained in the feedstock gas in the bulk desulfurization system is removed by contacting the feedstock gas with sorbent(s) capable of removing sulfur from the feedstock gas;    (4) passing the feedstock gas at a second temperature that is less than the first temperature to second filter vessel(s) where a portion of contaminant(s) contained in the feedstock gas in the second filter vessel(s) is removed by contacting the feedstock gas with at least one sorbent; and    (5) passing the feedstock gas at a third temperature that is less than the second temperature to third filter vessel(s) where a portion of contaminant(s) contained in the feedstock gas in the second filter vessel(s) is removed by contacting the feedstock gas with sorbent(s).    DESCRIPTION OF DRAWING(S) - The figure is a schematic diagram of a gas cleaning system of the invention.