UNIVERSITY OF PORT HARCOURT
FACULTY OF ENGINEERING
DEPARTMENT OF MECHANICAL ENGINEERING
A TERM PAPER
POWER STATIONS IN NIGERIA
(GAS, STEAM AND WATER TURBINES)
OGBONDA WINSTON K.
FLUID MECHANICS 3
MR. UDEH GODFREY
The word turbine was coined in 1828 by Claude Burdin (1788-1873) to describe the subject of an 1826 engineering competition for a water power source. It comes from Latin turbo, turbinis, meaning a "whirling" or a "vortex," and by extension a child's top or a spindle. Defining a turbine as a rotating machine for deriving power from water is not quite exact. The precise definition is a machine in which steam or water moves relatively to the surfaces of the machine, as distinguished from machines in which such motion is secondary, as with a cylinder and piston. The common overshot water wheel is a rotating machine, but not a turbine, while an undershot wheel is an impulse turbine, but not generally considered as one. We shall discuss many types of water-driven prime movers in this article, but mainly turbines, for which we will explain the fundamental theory. A Turbine has three (3) main sections the Compressor sections, Combustor sections and Turbine sections. The gas turbine power plant has to work continuously for long period of time without output and performance decline. Apart from the main sections there are other important Auxiliaries systems which are required for operating a Gas Turbine Power Plant on a long term basis.
In this section, air is taken into the compressor where in which the temperature pressure and density of the air is increased. At this section, the impurities and dust in the air deposits on the compressor blades. This reduces the efficiency and output of the plant. The Air Filter in the Air Intake system prevents this. A blade cleaning system comprising of a high pressure pump provides on line cleaning facility for the compressor blades. The flow of the large amount of air into the compressor creates high noise levels. A Silencer in the intake duct reduces the noise to acceptable levels. Exhaust system discharges the hot gases to a level which is safe for the people and the environment. The exhaust gas that leaves the turbine is around 550 °C. This includes an outlet stack high enough for the safe discharge of the gases. Silencer in the outlet stack reduces the noise to acceptable levels.
The combustor prepares a clean fuel for burning in the section. A burner system and ignition system with the necessary safety interlocks are the most important items. For liquid fuels high pressure pumps pump fuel to the pressure required for fine atomization of the fuel for burning. A control valve regulates the amount of fuel burned. A filter prevents entry of any particles that may clog the burners. Natural gas directly from the wells is scrubbed and cleaned prior to admission into the turbine. External heaters heat the gas for better combustion.
The turbine in a power plant runs at 3000 RPM (for the 50 Hz grid - 3600 RPM for the 60 Hz grid). Starting system provides the initial momentum for the Gas Turbine to reach the operating speed. This is similar to the starter motor of your car. During starting the speed has to reach at least 60 % for the turbine to work on its on inertia. The latest trend is to use the generator itself as the starter motor with suitable electrics. In situations where there is no other start up power available, like a ship or an off-shore platform or a remote location, a small diesel or gas engine is used. The simple method is to have a starter motor with a torque converter to bring the heavy mass of the turbine to the required speed. For large turbines this means a big capacity motor.
Plant stations in Nigeria include but not...
Please join StudyMode to read the full document