GB929682A - Improvements in and relating to steam generators - Google Patents

Abstract

929,682. Vertical steam boilers; superheaters. FOSTER WHEELER Ltd. Jan. 24, 1962 [Jan. 30, 1961], No. 3545/61. Classes 123 (2) and 123 (3). In a steam generator comprising a heatexchanger having a vertical cylindrical shell containing for the circulation of the heating fluid a vertical bundle of U-tubes connected to a pair of headers or a tube plate, the tube bundle is made up of two sections serving for the generators of steam and laying to either side of a central section which serves to superheat the steam and wherein the superheating section is isolated from the other sections and the walls of the shell by a trunking which defines a passage for the steam to be superheated. In the form shown the steam generator has a vertical cylindrical shell 10 having a water inlet 12 and a steam outlet 14. Within the shell there is a vertical handle 16 of U- tubes which are connected to a pair of inlet and outlet headers 18, 20 having connections 22, 24 passing through the shell and through which is circulated the heating fluid which may be the primary coolant from a nuclear reactor. The tube bundle 16 is in three sections, viz. two outer sections 34, 38 and a central section 36. The outer sections serve for the generation of steam and the central section for the superheating of this steam, the latter section being isolated by a trunking 40 which conforms with the shape of the U-tubes and provides a passage extending from the header 18 to the header 20. The tube bundle 16 and trunking 40 is surrounded by a baffle 26 which stops short of the bottom of the shell thus forming a downcomer 28 and a riser 30. The steam-water mixture generated within the shell is led by the baffle to steam-water separators 32 from which the separated water flows to the downcomer. Above the separators 32 steam driers 42 are arranged to discharge dry steam into a space 44 which is connected by a pipe 46 to the trunking 40. The steam then flows through the superheater in a counter-current direction to the heating fluid and leaves the superheater and shell through a pipe 14. The steam inlet end outlet pipes 46, 14 may lay inwardly of the baffle 26 as shown, or they may lay between the said baffle and the shell wall. The shell is protected from local overheating by the fact that the superheater tubes which are at a much higher temperature than the shell are completely isolated from the shell.