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A compound steam engine unit is a type of steam engine where steam is expanded in two or more stages. [1] [2] A typical arrangement for a compound engine is that the steam is first expanded in a high-pressure (HP) cylinder, then having given up heat and losing pressure, it exhausts directly into one or more larger-volume low-pressure (LP ...
The higher cost of turbines and the associated gears or generator/motor sets is offset by lower maintenance requirements and the smaller size of a turbine in comparison with a reciprocating engine of equal power, although the fuel costs are higher than those of a diesel engine because steam turbines have lower thermal efficiency. To reduce fuel ...
The last major passenger ship built with steam turbines was Fairsky, launched in 1984. Similarly, many steam ships were re-engined to improve fuel efficiency. One high-profile example was the 1968 built Queen Elizabeth 2 which had her steam turbines replaced with a diesel-electric propulsion plant in 1986.
A multi-shaft system usually has only one steam system for up to three gas turbines. Having only one large steam turbine and heat sink has economies of scale and can have lower cost operations and maintenance. A larger steam turbine can also use higher pressures, for a more efficient steam cycle.
In all turbines the blade velocity is directly proportional to the velocity of the steam passing over the blade. Now, if the entire energy of the steam is extracted in one stage, i.e. if the steam is expanded from the boiler pressure to the condenser pressure in a single stage, then its velocity will be very high.
A combined cycle powered locomotive is a patented idea to use two primary movers, a gas turbine with a steam turbine to gain the efficiency of a combined cycle power plant or a combined gas and steam engine. Steam locomotives were tested in the past but were not ideal for low speeds, and gas turbine locomotives were used by Union Pacific until ...
The efficiency of large steam turbines was considerably better than the best compound engines, while also being much simpler, more reliable, smaller and lighter all at the same time. Steam turbines would eventually replace piston engines for most power generation.
A steam turbine consists of one or more rotors (rotating discs) mounted on a drive shaft, alternating with a series of stators (static discs) fixed to the turbine casing. The rotors have a propeller-like arrangement of blades at the outer edge. Steam acts upon these blades, producing rotary motion.