Heat exchanger and method

Claim 1

A RECUPERATOR COMPRISING AN INSULATED OUTER WALL DEFINING A FIRST PASSAGE, A HEAT CONDUCTIVE INNER WALL SPACED WITHIN SAID OUTER WALL DEFINING A SECOND PASSAGE SURROUNDED BY SAID FIRST PASSAGE IN HEAT EXCHANGE RELATION THERETO, BOTH SAID PASSAGES HAVING A MINIMUM HORIZONTAL DIMENSION OF ABOUT 4 INCHES, PERFORATE MEMBERS EXTENDING ACROSS EACH OF SAID PASSAGES ADJACENT THE BOTTOMS THEREOF, BEDS OF FINELY DIVIDED THEREMOPHORE OF A UNIFORMLY DISTRIBUTED PARTICLE SIZE APPROXIMATELY BETWEEN 10 MESH AND 100 MESH AND ADAPTED FOR FLUIDIZATION AND VERTICAL BACK MIXING IN EACH OF SAID PASSAGES SUPPORTED ON SAID MEMBERS, SAID BEDS HAVING A MINIMUM DEPTH OF ABOUT 3 FEET, GAS INLETS TO THE BOTTOMS OF SAID PASSAGES BELOW SAID MEMBERS FOR INTRODUCING UPWARDLY FLOWING COCURRENT STREAMS OF GASES TO SAID BEDS TO FLUDIZE THEM AND TO TRANSFER HEAT FROM ONE GAS TO THE OTHER THROUGH SAID INNER WALL, GAS OUTLETS FROM SAID PASSAGES ABOVE SAID BEDS, AND MEANS POSITIVELY CONFINING SAID THERMOPHORE TO THE RESPECTIVE PASSAGES.