Turbine waterwheels. Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for invention of the steam turbine is given both to Anglo-Irish engineer Sir Charles Parsons (1854–1931) for invention of the reaction turbine, and to Swedish engineer Gustaf de Laval (1845–1913) for invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery. The word "turbine" was coined in 1822 by the French mining engineer Claude Burdin from the
Mercury vapour turbine is used to raise steam for the steam turbine. The Hartford Electric Light Co. (U.S.A.) has a 10,000kW turbo-generator driven by mercury vapour, which reaches the turbine at 70 lb. per sq. in. (gauge), 880°F. The mercury vapour is condensed at 445°F and raises 129,000 lb. steam per hr. at 280 lb. per sq. in. pressure. The latter is superheated to 735°F and passed to the steam turbines. During 4 months continuous operation, this plant averaged about 0.715 lb. of coal per kWh of net output, about 43% of the output being from the mercury turbine generator and 57% from