GB956503A - Steam boilers employing combustion under pressure - Google Patents

Abstract

956,503. Water-tube steam boilers; heating air for combustion. STEIN & ROUBAIX. Dec. 19, 1961 [Dec. 28, 1960], No. 45482/61. Headings F4A and F4B. A pressure-fired steam boiler comprises one or a plurality of elements each consisting of a pressure-resistant, vertically-disposed, cylindrical outer casing within which is coaxially located a hollow body bounded by contiguous vaporizing tubes and having a combustion chamber in its lower portion and one or more heat exchangers in the portion thereabove, the annular space between the body and the casing being swept by the air of combustion and containing the distributer and collector headers of the heat exchangers. In the form shown the outer casing 1 has hemispherical end covers 2 and contains an inner body 3 formed of small diameter, contacting steam generating tubes extending between distributers 8 and collectors 9. The lower part 6 of the body 3 is cylindrical and forms a combustion chamber fired by burners 39 whilst the upper part 7 is of square section and forms a convection pass for the combustion gases, banks of horizontally disposed tubes constituting an evaporator 12, low and high temperature superheaters 17, 23 and a reheater 30 being located in the pass. The gases discharge through an outlet 40. Air for combustion enters the easing through an upper inlet, not shown, and passes to the burners through the space between the casing 1 and the body 3. The contiguous tubes forming the body are enclosed in a gas tight sheet metal casing 4 and are supported by stiffening rings 5, the whole unit being supported from the bottom on feet 42 so that the body 3 can expand and contract independently of the casing. In operation water enters the distributers 8 through pipes 10 and flows upwardly in the contiguous tubes and through the evaporator 12 to collectors 9, 16a. The water-steam mixture flows thence to an external steam and water drum, which is common to all the boiler elements where a plurality of these is used. Steam returns from the drum to the superheater 17 and flows thence through a desuperheater 22 and the final superheater 23 to a turbine. Steam to be reheated enters the casing through a header 33, flows through the reheater and returns to the turbine via a header 28.