GB1140036A - Improvements in vapour generating and superheating units in ship propulsion power plant - Google Patents

Abstract

1,140,036. Controlling steam temperature in boilers. BABCOCK & WILCOX Ltd. 15 March, 1966 [15 March, 1965], No. 10925/65. Heading F4A. An oil fired marine steam boiler comprises a furnace chamber (1, Fig. 1, not shown) lined with evaporating tubes, and parallel upright evaporating tube lined convection passes 3, 4, the gas flows through which are controlled by dampers 48, 49 respectively. The pass 3 houses an intermediate superheater section 51, a final superheating section 61 and an economizer section 64, whilst the pass 4 houses an initial superheating section 66 and a reheat section 67. A steam conduit 73 containing an attemperator 74, which is in the form of an indirect heat exchanger located in the boiler drum (Fig. 3, not shown) or in a vessel in contact therewith, connects the intermediate and final superheating sections. A further indirect contact or a regulatable spray type attemperator may be located after the final superheater section to control the final degree of superheat. Alternatively (Fig. 4, not shown) a third parallel upflow damper controlled by pass (101) containing economizer or evaporator tubes (103) may be used to automatically regulate the degree of superheat. In other modifications the intermediate superheater section may be positioned in the first gas pass downstream of the final superheater section (Fig. 5, not shown) or the positions of the initial and the intermediate superheater sections may be interchanged, with or without the initial superheater section being situated downstream of the final superheater section. In all modifications having the initial superheater section in the pass 3 the attemperator 74 may be located between the initial and the intermediate superheater sections or between the intermediate and the final superheating sections. Additional economizer, or reheater surfaces may be located in a common pass downstream of the parallel gas passes. The steam flow through the superheating sections may be co-current or counter-current to the flow of gases from the furnace chamber. The location of the initial or intermediate section of the superheater upstream in the same gas pass as the reheater section protects the tubes of the latter from overheating when with the ship going astern and no reheat being required, the dampers 49 are closed to prevent gas flow through the pass 4.