The type of turbine in which a jet of steam from a fixed nozzle pushes against the rotor blades and impels them forward. The velocity of the steam is about twice as fast as the velocity of the blades. Only turbines utilizing fixed nozzles are classified as impulse turbines.
Steam expands in the nozzles with a decrease in pressure, but an increase in velocity before it strikes the motor blading.
The first stage on impulse turbine often permitted to take more than equal share of the available pressure drop, thereby its advantages are:

  1. casing ss subjected to lower striking pressure.
  2. rotational losses is lowered due to decreased steam density.
  3. fitted with high pressure seal.
    Speed of impulse blades rated varies as one half of the steam speed. It permit use of partial admission of steam, on steam chest fitted with nozzle to increase efficient operation.
    Impulse blade are generally attached directly to the wheels, made in longer length attached. Impulse blading is heavier and stronger than reaction turbine.

Related Terms

WATER COLUMN

A vertical tubular member connected at its top and bottom to the steam and water space respectively to a boiler, to which the water gage, gage valves, high and low water alarms and fuel cutoff may be connected.

PISTON VALVE

A cylindrical type of steam engine slide valve for admission and exhaust of steam.

PARALLELS

1. Spacers located between steam plate and press platen of the mold to prevent bending of the middle section. 2. Spacers or pressure pods located between steam plates of a mold to regulate height and prevent crushing of mold parts.

NUCLEAR POWER PLANT

A power plant in which nuclear energy is converted into heat for use in producing steam for turbines, which in turn drive generators that produce electric power. Also known as atomic power plant.

MULTIPLE-EFFECT EVAPORATION

Seriesoperation energy economizer system in which heat from the steam generated (evaporated liquid) in the first stage is used to evaporate additional liquid in the second stage (by reducing system pressure), and so on, up to 10 or more effects; commonly used in the pulp and paper industry.

MOIST-HEAT STERILIZATION

Sterilization with steam under pressure, as in an autoclave, pressure cooker, or retort; most bacteriological media are sterilized by autoclaving at 121 C, with 15 pounds (103 kilopascals) of pressure, for 20 minutes or more.

LOW-LEVEL CONDENSER

A direct-contact water-cooled steam condenser that uses a pump to remove liquid from a vacuum space.

LINE OILER

An apparatus inserted in a line conducting air or steam to an airor steamactivated machine that feeds small controllable amounts of lubricating oil into the air or steam. Also known as air-line lubricator; line lubricator.

LANCASHIRE BOILER

A cylindrical steam boiler consisting of two longitudinal furnace tubes which have internal grates at the front.

INTERCONDENSER

A condenser between stages of a multistage steam jet pump.

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