Thermal isolator

In an arrangement for feeding a feedfluid into a fluid-containing pressure vessel and mixing the feedfluid with the fluid in the vessel wherein the feedfluid is received through an inlet pipe connected to said vessel by a nozzle and is directed through a sparger pipe inserted in said nozzle, a thermal isolator arrangement comprising:

• a first seal means between the upstream end of said sparger pipe and said nozzle, said first seal means being imperfect whereby an amount of said feedfluid leaks past said first seal means;
• an elongated first sleeve positioned substantially concentric with said sparger pipe and spaced therefrom to form a first annular fluid space, said first sleeve being sealed to said sparger pipe at the upstream end thereof, said first annular fluid space being substantially open to said vessel at its downstream end;
• second seal means between said first sleeve and said nozzle downstream of said first seal means whereby an annular cavity is formed bounded by said first and second seal means, an upstream portion of said first sleeve and a portion of said nozzle, said second seal means being imperfect whereby differential pressure thereacross causes leakage of an amount of said fluid past said second seal;
• and a fluid passage in said portion of said first sleeve adjacent said annular cavity communicating with said first annular fluid space whereby fluid leakage flow into said annular cavity is directed through said fluid passage and through said first annular fluid space into said vessel.