Package heating apparatus

Claim 1

A PACKAGE BOILER HAVING A RECTANGULAR BASE AND A TUBING HEADER ASSEMBLY EXTENDING VERTICALLY UPWARD FROM ONE END OF SAID BASE, AN UNDERPINNING STRUCTURE DISPOSED TO EXTEND LATERALLY AND LONGITUDINALLY ON SAID BASE, SAID STRUCTURE INCLUDING A PLURALITY OF CHANNELS EACH DISPOSED WITH ITS WEB DOWNWARD AND ITS FLANGES UPWARD, A NUMBER OF FIRE BRICKS DISPOSED IN SAID CHANNELS IN SIDE-BY-SIDE RELATION AND EXTENDING UPWARD THEREFROM THEREBY FORMING THE LOWER WALLS OF THE COMBUSTION CHAMBER, A CASING ASSEMBLY DISPOSED UPON THE SAID FIRE BRICK AND DEFINING THE UPPER SIDE AND TOP WALLS OF THE COMBUSTION CHAMBER, SAID CASING ASSEMBLY HAVING AN OFFSET FLANGE PORTION ALONG ITS LOWER EDGE WHICH ENGAGES THE OUTSIDE UPPER EDGE OF SAID FIRE BRICKS, A PLURALITY OF TUBES CONNECTED TO SAID HEADER AND EXTENDING LONGITUDINALLY INTO SAID CASING ASSEMBLY, AT LEAST ONE OF SAID TUBES BEING IN ABUTTING RELATION TO THE TOP SURFACE OF THE LONGITUDINALLY EXTENDING FIRE BRICKS AND AT LEAST ANOTHER OF SAID TUBES BEING HORIZONTALLY OFFSET FROM AND VERTICALLY BELOW THE LAST-SAID ONE TUBE AND IN ABUTTING RELATION TO THE INSIDE UPPER FACE OF THE LONGITUDINALLY EXTENDING FIRE BRICKS.