A compound turbine is a

steam turbine A steam turbine is a machine that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft. Its modern manifestation was invented by Charles Parsons in 1884. Fabrication of a modern steam turbin ...

in which there are two casings, a high-

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country and e ...

casing and a low-pressure casing, operating in concert to extract work from a single source of steam. The steam is partially expanded in the high-pressure casing, then exhausted to the low-pressure casing.

Tandem compound or cross compound

The rotor arrangement can be either tandem-compound in which the two

axle An axle or axletree is a central shaft for a rotating wheel or gear. On wheeled vehicles, the axle may be fixed to the wheels, rotating with them, or fixed to the vehicle, with the wheels rotating around the axle. In the former case, bearing ...

s are joined end to end, or cross-compound in which the two turbines have separate axles. In the cross-compound case two separate generators are usually supplied, although a gearbox can reduce this to one.

Advantages

The principal advantages of compound turbines are the reduction in size of any one casing, the confinement of the highest pressure to the smaller casing (which may be made of stronger and more expensive materials) and the possibility of divided flow in the low-pressure casing for the purpose of equalizing end thrusts.

References

Steam turbines {{mech-engineering-stub

Tandem compound or cross compound

Advantages

See also

References