GB1092511A - Improvements in and relating to heat exchange systems - Google Patents

Abstract

1,092,511. Waste heat boilers. B. P. TANKER CO. LTD. and E. H. W. PLATT, A. NORRIS and D. J. GIBBONS. May 14, 1964 [Feb. 27, 1963], Heading F4A. Hot exhaust gases from both a marine diesel engine 24 and a direct fired gas generator 16 are used to generate steam in boiler unit 1. Gases from engine 24 pass via heat exchanger 7, to mixing chamber 15 then past tube banks 5, 6, 4 in unit 1 to generate steam. To supplement these gases, high temperature gases from air jacketed oil fed combustion chamber 2, together with recirculated cooled gases from off-takes 3, may alternatively or in addition flow to mixing chamber 15. Feed water from pump 12, preheated in heat-exchangers 9, 10 by water drawn from steam drum 8 by circulating pump 11, passes through the drum, to banks 4, 5 and then back to the drum as a steam/water mixture before passing to superheaters 6, 7. The steam pressure in drum 8 controls the oil fuel supply to chamber 2 through controller 19 and valve 20. The system may be applied to combinations of engines, combustors and steam generators to allow their alternative or conjoint use (Fig. 2). Back flow of gases from the combustion chamber to the diesel engine may be prevented by positively pumping the engine exhaust gases to the mixing chamber (Fig. 4) or by discharging them into a chamber surrounding the mixing chamber, into which the high velocity gases from the combustion chamber are discharged through a nozzle, so that the engine exhaust gases are drawn into the mixing chamber by a " Venturi " effect. The same effect may be used to draw in the recirculated cool gases from the offtakes (Fig. 5). Gases from either source may be separately or conjointly admitted to the boiler 1 intermediate of the normal entry and exit through temperature-controlled valves (Fig. 6), whilst the oxygen content of the mixed gases may be controlled by burning fuel in the combustion chamber using the engine exhaust gases as secondary air, the combustion being controlled by a gas composition controller (Fig. 7). The boiler may be of the forced circulation, natural circulation or forced flow once through type. The gases from the two sources may pass through the boiler as separate streams separated by baffle plates 28, 29, Fig. 3, the gases being diverted to flow through the middle section by damper 26 controlled by controller 31 which also controls the oil supply feed valve 32 to the steam/water jacketed combustion chamber 2 which is used as a steam and water drum and so prevents the need for gas recirculation.