Patent ID: 7381384

Claim:
A nozzle for a process vessel for operation at an elevated process temperature, the vessel having an outer metal shell, an inner insulating lining, and a membrane between the insulating lining and the outer shell, the nozzle having an interior communicating with an interior of the vessel and comprising: (a) a nozzle outer shell sealed to the outer shell of the vessel, the nozzle outer shell having first and second open ends, and a side wall defining a nozzle axis extending between the first and second ends of the nozzle outer shell; (b) a nozzle membrane lining an interior surface of the nozzle outer shell, the nozzle membrane being sealed to the membrane of the vessel; (c) a cover provided on the first end of the nozzle outer shell; and (d) a pre-formed, replaceable insulating sleeve comprised of a thermally insulating polymer material having a maximum allowable service temperature greater than an operating temperature inside the nozzle, wherein the insulating sleeve is resistant to corrosive attack by corrosive process fluids, the insulating sleeve being hollow and having a side wall having an inner surface and an outer surface, the side wall of the sleeve extending along the nozzle axis between the first and second ends of the nozzle outer shell; wherein the side wall of the insulating sleeve is of sufficient thickness and has sufficiently low thermal conductivity such that, when the insulating sleeve is heated by the process temperature during operation of the vessel, the outer surface of the side wall remains at a sufficiently low temperature such that thermal energy transmitted through said insulating sleeve to said nozzle membrane is insufficient to raise the temperature of any part of the nozzle membrane above a target temperature.