Patent GB-457666-A (GB)
Title: Improvements in and relating to methods of and apparatus for generating steam or other vapours indirectly
IPC: F22B1/12
Filed: 1935-06-28
Abstract: 457,666. Indirectly heated steam boilers. SCHMIDT'SCHE HEISSDAMPFGES., 2, Rolandstrasse, Wilhelmsh÷he, Cassel, Germany. June 28, 1935, No. 18580. Convention date, June 28, 1934. [Classes 64 (iii) and 123 (ii)] [See also Group XXVIII] Steam is generated in a water-tube boiler having a steam and water drum by the transmission of heat from a stream of heat-carrier which is itself heated whilst imparting heat and is then withdrawn for other use, separate paths being provided for the heat-carrier and liquid to be evaporated outside the boiler drum. One form of boiler comprises U-tubes 2 extending across a vertical flue and serving as jackets for Field tubes consisting of inner and outer tubes 9, 10 and arranged in vertical series connected to divided headers 14 communicating with the drum 1 by downcomer nipples 18 and riser pipes 21. Steam from the drum passes through a drum 32 and pipe 33 to the lowest tube 2 of each vertical series whence it proceeds by interconnecting pipes 34 through all the U-tubes and a pipe 35 into a space 36 in the drum and thence to a superheater. The Field tube outer sections 10 may be ribbed and have staggered feet to produce eddying of the heat-carrying steam. The Field tube inner sections 9 carry a washer 22 closing an opening in the header dividing wall 15 and at their end a cover 23 fits into an opening 24 in the header wall through which the section can be. inserted, the cover being held in place by a pressure yoke 25 secured by bolts and nuts 26. The circulation may be forced for starting up or steam from an external source may be supplied therefor or continuously as heat-carrier. The flow of heating steam may be reversed so as to be counter to that of the flue gases in boilers employing relatively low temperatures. One modification dispenses with tubes 34 by providing a third compartment in the header to successive sections of which the U-tube jackets are connected. Another has a row of jacketed tubes extending across the flue and downwardly to form a wall, the inner tubes being connected to the header compartment with which the sections 10 communicate and the outer tubes to the lowest of each series of jacket tubes 2. A circulating pump may be arranged between the drum and the openings of the inner Field tube sections. A marine boiler comprises two groups of Field tubes with a combustion chamber between them, the Field tubes being enclosed by jackets connected at their lower ends by return bends and their upper ends by covers to form in effect a continuous tube or serpentine extending between drums. Another arrangement substitutes simple closures for the return bends at the lower ends of the jacket tubes and straight tubes leading to a lower drum for the Field tubes. The lower drum has inlet and outlet chambers separated from the water space for the heating steam passing through the jacket tubes. The Specification as open to inspection under Sect. 91 describes also a horizontal smoke-tube boiler with tubes surrounding the smoke-tubes traversed by steam generated in the boiler. In another construction, similar to that of Fig. 2, heating steam from a separate source is pumped through a closed circuit comprising drums, piping, and the U-tube jackets. This subjectmatter does not appear in the Specification as accepted.