MAKING HEAT BALANCE CALCULATIONS OF MARINE STEAM POWER PLANTS--WHY AND HOW?

During the past few years an increasing number of the new merchant ships entering service are being powered by steam turbine units, especially those for which the power output required exceeds 30,000 shp which it normally does for large tankers and fast container ships. Of the ships on order pr. 31.12.1972 totalling 137.9 million tons d.w., according to "Motor Ship", the 380 steam turbine ships represent 60% of the deadweight and 40% of the power. Looking at tankers about 300,000 tons d.w. in service or on order, we find that pr. 31.12.1972 there were 8 in service and 52 on order, all powered by steam turbines. This increasing use of marine steam power plants stresses the importance of providing the shipowners and shipbuilders with adequate tools for selecting an optimum cycle configuration, and for studying the performance of such plants. A computer program for heat balance calculations will be a most important tool in this respect, and the objective of this papers is to explain the reasons for making heat balance calculations and to present a very versatile computer program that is used at Det norske Veritas for such calculations.