Energy and Exergy Analyses of Forced Draft Fan for Marine Steam Propulsion System during Load Change

Abstract

A forced draft fan, used for the supply of combustion air into the steam generator of the conventional liquefied natural gas (LNG) carrier was analyzed from the aspect of energy and exergy. The power delivered from the induction motor to the fan was calculated using the manufacturer’s data. The most significant impact on the fan energy power losses is from the air temperature difference between the fan outlet and inlet. The fan energy power losses are inversely proportional to the fan energy efficiency, and the values are between 19.9% and 63.4%, for the entire range of observed steam system loads. The fan exergy destruction depends primarily on the driving power and on the air mass flow rate. At higher loads, an important influence on the fan exergy destruction is from the air pressure at the fan outlet. The exergy efficiency change of the analyzed fan, for the range of observed steam system loads, is directly proportional to the rate of change in the air mass flow, whereas the obtained values of exergy efficiency are between 5.10% and 53.93%. The impact of ambient temperature on the fan exergy destruction and exergy efficiency exhibits is different than in most other steam system components. A change in ambient temperature of 10 °C causes a change in the exergy efficiency of the forced draft fan less than 0.5% in the entire range of observed steam loads.

Energy Loss Analysis at the Gland Seals of a Marine Turbo-Generator Steam Turbine

“…The majority of marine steam power plant components are the same as in land-based steam power plants [18,19], but the operation of a marine steam plant must be much more dynamic. Along with the already mentioned two identical Turbo-Generator Steam Turbines, the marine steam system also consists of two identical steam generators [20] in front of which forced draft fans [21] and air heaters (air is heated with steam) [22] are mounted. The main propulsion turbine is composed of two cylinders (high pressure and low pressure) [23], which drive the main propulsion propeller through a marine gearbox.…”

Analysis of Low-Power Steam Turbine With One Extraction for Marine Applications

“…Thermodynamic analysis (energy and exergy analysis) of any control volume or system is based on the fi rst and the second law of thermodynamics. The fi rst law of thermodynamics defi nes energy analysis [17], which is independent of the environment in which analyzed control volume or a system operates [18]. On the other side, exergy analysis of any control volume or system is based on the second law of thermodynamics [19] and it takes into account the parameters of the ambient in which control volume or a system operates [20].…”

The Leakage of Steam Mass Flow Rate through the Gland Seals – Influence on Turbine Produced Power

“…The analysis in this paper is performed on the basis of energy and energy flow streams, which are based on the first law of thermodynamics [34,35]. In comparison to other similar analysis [36][37][38] energy analysis did not take into consideration pressure and temperature of the ambient in which observed component or system operates [39][40][41].…”