Apparatus and process for cooling hot gas

An apparatus for cooling hot gas from a partial oxidation reactor comprising:

• (i) a vessel fluidly connected to said partial oxidation reactor by means of a horizontal duct, said vessel and horizontal duct being provided with a cooling medium compartment, an inlet to supply fresh cooling medium and a outlet for discharge of used cooling medium, said vessel and horizontal duct further provided with an inlet for hot gas and an outlet for cooled gas, at least one heat exchange tube fluidly connecting the inlet for hot gas and the outlet for cooled gas positioned in the cooling medium compartment, wherein the downstream end of said heat exchange tube is positioned in said vessel and arranged vertically therein, and wherein the upstream end of said heat exchange tube is positioned in said horizontal duct and is arranged horizontally therein, said upstream tubular part being sealingly attached to a tube sheet that is also positioned in said horizontal duct and is arranged vertically therein,
• (ii) a means for extracting a volume of the cooling medium from the cooling medium compartment, and wherein
• (iii) the upstream end of said heat exchange tube in said horizontal duct is provided with a cooling means comprising means to supply a mixture of the extracted liquid cooling medium and part or all of the fresh liquid cooling medium along the exterior of the upstream end of said heat exchange tube and a side of said tube sheet in said horizontal duct.