Steam Turbine

Verified Timeline

Lore & Background

The development of the steam turbine in 1884 provided larger and more efficient machine designs for central generating stations. By 1892, the turbine was considered a better alternative to reciprocating engines, offering higher speeds, more compact machinery, and stable speed regulation allowing for parallel synchronous operation of generators on a common bus. After about 1905, turbines entirely replaced reciprocating engines in almost all large central power stations. The largest reciprocating engine-generator sets ever built were completed in 1901 for the Manhattan Elevated Railway, each weighing about 500 tons and rated 6000 kilowatts; a contemporary turbine set of similar rating would have weighed about 20% as much. The reciprocating steam engine had been used to produce mechanical power since the 18th century, with notable improvements being made by James Watt, and the first commercially developed central electrical power stations established in 1882 at Pearl Street Station in New York and Holborn Viaduct power station in London used reciprocating steam engines.

In Their Own Story

The pipes hummed, a low vibration traveling up his arms through the wrench. Downstream, the Steam Turbine whirred to life, its blades catching the invisible weight of the superheated vapor. Lights in the habitat flickered once, then steadied into a warm, constant glow. He watched the exhaust pipe venting cool water back toward the condenser loop. Another hour of darkness survived without burning fuel.

Reader's Guide

The energy efficiency of a conventional thermal power station is defined as saleable energy produced as a percent of the heating value of the fuel consumed. A simple cycle gas turbine achieves energy conversion efficiencies from 20 to 35%. Typical coal-based power plants operating at steam pressures of 170 bar and 570 °C run at efficiency of 35 to 38%, with state-of-the-art fossil fuel plants at 46% efficiency. Combined-cycle systems can reach higher values. As with all heat engines, their efficiency is limited and governed by the laws of thermodynamics. The Carnot efficiency dictates that higher efficiencies can be attained by increasing the temperature of the steam. Sub-critical pressure fossil fuel power stations can achieve 36–40% efficiency. Supercritical designs have efficiencies in the low to mid 40% range, with new "ultra critical" designs using pressures above 4,400 psi (30 MPa) and multiple stage reheat reaching 45–48% efficiency. Above the critical point for water of 705 °F (374 °C) and 3,212 psi (22.15 MPa), there is no phase transition from water to steam, but only a gradual decrease in density. The waste heat from a gas turbine, in the form of hot exhaust gas, can be used to raise steam by passing this gas through a heat recovery steam generator (HRSG). The steam is then used to drive a steam turbine in a combined cycle plant that improves overall efficiency. Cogeneration plants, often called combined heat and power (CHP) facilities, produce both electric power and heat for process heat or space heating, such as steam and hot water.

Did You Know?

• The first commercially developed central electrical power stations were established in 1882 at Pearl Street Station in New York and Holborn Viaduct power station in London, using reciprocating steam engines.
• The development of the steam turbine in 1884 provided larger and more efficient machine designs for central generating stations.
• By 1892, the turbine was considered a better alternative to reciprocating engines, offering higher speeds and stable speed regulation.
• The largest reciprocating engine-generator sets ever built were completed in 1901 for the Manhattan Elevated Railway, each weighing about 500 tons and rated 6000 kilowatts.
• Above the critical point for water of 705 °F (374 °C) and 3,212 psi (22.15 MPa), there is no phase transition from water to steam, but only a gradual decrease in density.