Heat exchanger

Claim 1

IN APPARATUS FOR DRYING CROP MATERIAL, MEANS FOR PRODUCING A CURRENT OF FORCED HOT AIR COMPRISING THE COMBINATION OF A TUBULAR HOUSING HAVING OPEN ENDS, A FAN IN SAID HOUSING FOR MOVING A CURRENT OF AIR INTO ONE OF SAID ENDS, THROUGH SAID HOUSING AND OUT OF THE OTHER OF SAID ENDS, A HEAT EXCHANGER DISPOSED WITHIN SAID HOUSING AND OVER WHICH THE AIR CURRENT MOVES TO BE HEATED, SAID HEAT EXCHANGER COMPRISING AN ELONGATED HOLLOW CYLINDER OF SMALLER DIAMETER THAN SAID HOUSING MOUNTED COAXIALLY INSIDE THE HOUSING, SAID CYLINDER HAVING END WALLS CLOSING THE RESPECTIVE ENDS OF THE CYLINDER, THE END WALL AT THE END OF THE CYLINDER FACING INTO SAID AIR CURRENT BEING A HOLLOW FRUSTRO-CONE TAPERING AXIALLY AWAY FROM SAID CYLINDER AND INTO SAID AIR CURRENT, MEANS AT THE APEX OF SAID FRUSTROCONICAL WALL DEFINING AN AXIAL INLET OPENING INTO SAID HEAT EXCHANGER, A BURNER HEAD DISPOSED WITHIN SAID HOUSING OUTSIDE OF SAID HEAT EXCHANGER AND IN AXIAL ALIGNMENT WITH SAID INLET OPENING MEANS, SAID BURNER HEAD INCLUDING A FUEL NOZZLE SPACED AXIALLY FROM SAID INLET OPENING MEANS AND ADAPTED TO DIRECT A WIDE SPRAY PATTERN OF FUEL AXIALLY INTO SAID INLET OPENING, AN IGNITION DEVICE DISPOSED AXIALLY BETWEEN SAID NOZZLE AND SAID INLET OPENING MEANS WHEREBY SAID WIDE SPRAY PATTERN OF FUEL PASSES OVER SAID IGNITION DEVICE TO FACILITATE IGNITION OF THE FUEL ON ITS WAY INTO SAID INLET OPENING, AND A CYLINDRICAL SHIELD SPACED AXALLY DOWNSTREAM FROM SAID BURNER HEAD AND EXTENDING INTO THE FRUSTRO-CONICAL PORTION OF SAID HEAT EXCHANGER THROUGH SAID INLET OPENING MEANS TO NARROW SAID SPRAY PATTERN OF FUEL AFTER IT PASSES SAID IGNITION DEVICE TO DIRECT THE FLAME AXIALLY INTO SAID COMBUSTION CHAMBER PAST THE INNER SURFACE OF SAID FRUSTRO-CONICAL END WALL.