GB841800A - Improvements in vapour generating units for the recovery of heat from hot fluid under pressure - Google Patents

Abstract

841,800. Forced-flow vapour generators. BABCOCK & WILCOX Ltd. Sept. 17. 1958 [Sept. 18, 1957], No. 29817/58 Classes 123(2) and 123(3) In a vapour generating unit for recovering heat from hot fluid under pressure, hot gases at superatmospheric pressure are delivered through an inlet duct 39 to two superheaters 30, 31 arranged in parallel and then through a cylindrical pressure vessel 3 which is divided by a cylindrical partition 14 into a central vapour generating section 1 and a surrounding annular economizer section 2, the gases being exhausted from the vessel through a duct 25. Steam generated in a cylindrical nest of upright tubes 6 in the section 1 and extending between the wet vapour space 7 of a spherical drum 4 closing the upper end of the vessel 3 and a spherical water distributer drum 8, passes over liquid separators 5 in the drum 4 and through a duct 26 to a distributer 27 having an outlet 27<SP>1</SP>. Steam for superheating passes from the distributer 27 and through ducts 28, 29 respectively to the superheaters 30, 31. Each of the latter comprises an inverted U-shaped casing 33 which encloses a nest of U-shaped tubes 34 connected at one end by a distributer 35 to the adjacent end of the respective duct 28 or 29 and at the other end to a collector 36 leading to the point of use. A water feed pipe 23, passing in a gas-tight manner through an aperture in the vessel 3, leads to an arcuate distributer 22 which supplies water to a two layer coil of spaced economizer tubes 18 helically wound around the partition 14. The latter surrounding the nest of steam generating tubes 6, extends substantially throughout the height of the partition. The upper ends of the tubes 18 communicate with a part spherical water trough 20 mounted centrally within the drum 4 to define the steam space 7. The lower end of the partition 14 is connected, by an extension 16, to a semi-spherical cap 17 an opening in the bottom of which communicates with a gas duct 12 connected to a gas duct leading from the superheater 30, 31. Gases entering the cap 17 pass upwardly over the steam generating tubes 6 in the section 1 and downwardly, through the annular section 3 accommodating the economizer tubes 18, to the exhaust duct 25. A large downcomer pipe 9 in the centre of the vessel 3 connects the trough 20 with the drum 8.