Expain the use of a turbo generator and how it can be used t

Expain the use of a turbo generator and how it can be used to recover spent energey in a generator, give an example showing equations and diagrams

Solution

USES:

A turbo generator is the combination of a turbine directly connected to an electric generator for the generation of electric power. Large steam-powered turbo generators provide the majority of the world\'s electricity and are also used by steam-powered turbo-electric ships.^[1]

Smaller turbo-generators with gas turbines are often used as auxiliary power units. For base loads diesel generators are usually preferred, since they offer better fuel efficiency

Turbo Generators are engine driven alternators (engine generators)typically using diesel fuel to run the engine right on site. They are typically used where emergency and standby power is needed in case of utility power failure. Places like hospital require on site standby power in case of normal power failure and you will see them used there and any other place that can\'t afford power loss

A turbogenerator is an electric generator which runs synchronously with the power supply to which it is connected and has a speed of rotation = either 3600 or 1800 rpm (USA/ Canada) or 3000 or 1500 rpm (Europe) with Asian countries using one or other of these. They normally have relatively long, slender, cylindrical rotors

Turbogenerators are normally employed to generate our electricity and are driven most commonly by either steam or gas turbines in municipal or private power plants. Generators which run slower (as used e.g. in hydro plants) are not normally called turbogenerators.

The ratings of turbogenerators vary from a few MVA up to about 2000MVA with most of our power being generated by units of around 300 to 600 MVA. The biggest ones are in nuclear plants and often run at so called half speed (1800 or 1500 rpm). Above about 400 MVA they are normally filled with hydrogen gas under pressure, to improve cooling and minimise windage losses.

The power plants supplying most of our power are either:

1. coal fired, where burning coal generates steam which drives a steam turbine

2. gas fired, where gas is burned first in a gas turbine with the hot exhaust going to generate steam (in a waste heat boiler) which drives a steam turbine. This latter type of \"combined cycle\" plant provides by far the best overall thermal efficiency. Both gas and steam turbines drive turbogenerators.

3. nuclear, where the heat from a nuclear fission reaction produces steam.

Gas turbine plants, particularly operating in combined cycle, therefore contribute a major part of our base load supply. They are not small, having outputs typically in the same range as coal plants at (as already said) much higher efficiency.

Whilst diesel plants (often with reciprocating engines, although diesel can be fired in gas turbines) are used, it is very seldom for base load. They are relatively small (around 30MW), inefficient, high in maintenance per MWh and most important, diesel fuel is, in comparison, extremely expensive. They are therefore mostly used for short term peak or emergency power, or where other fuel supply is not viable and they supply only a very small fraction of our electrical energy.