Boilers

Claim 1

An improved boiler comprising, in combination: (a) an enclosed housing defined by an upper wall, a lower wall and enclosing side walls; (b) a combustion chamber positioned at the upper wall with a gas inlet in one side wall of the housing to the chamber; (c) a gas outlet in one side wall adjacent the lower wall, said outlet separated from the combustion chamber by a baffle wall and positioned below the combustion chamber; (d) an upper header at the upper wall having a generally rectangular, flat construction and generally extending across the top wall; (e) a lower header at the lower wall having a generally rectangular, flat construction and extending across the bottom wall; (f) a plurality of substantially straight riser tubes extending from the lower header to the upper header, said riser tubes positioned adjacent the inlet and combustion chamber at their upper end and adjacent the outlet at the lower end, said tubes providing means for heating fluid flowing upwardly in the tubes by natural convection and for heat exchange with the flowing gas inflow through the inlet chamber of the boiler and thence through the boiler and the outlet by natural convection; (g) a plurality of downcomer tubes adjacent the side wall of the boiler opposite from the gas inlet chamber, said downcomer tubes connecting the upper header with the lower header and circulating fluid therebetween by natural convection; and (h) a steam drum attached to the upper header adjacent the intersection of the upper and sidewalls including a steam outlet for discharge of steam.