A steam turbine is a mechanical device that extracts thermal energy from pressurized steam, and converts it into rotary motion. Its modern manifestation was invented by Sir Charles Parsons in 1884.
How Does A Steam Turbine Work?
A steam turbine, as we see from its name, uses steam to rotate its
blades. The rotary motion of the blades is used to rotate the armature of the
generator, and the movement of the armature in a magnetic field results in the
production of a current (electricity) in the armature! The steam turbine has
come a long way from its initial design: there is the single flow steam
turbine, the multiple flow steam turbines, the reaction steam turbine, the
impulse-reaction steam turbine, and the impulse turbine. It has been the object
of research and interest of many engineers and scientists like De Laval,
Parson, and Curtis. Heat energy from a coal thermal power plant or a nuclear
power plant is used to boil waiter, and convert it into steam at high pressure.
This high pressure steam is directed to the turbine blade thus causing the
blade to rotate!
What Goes Into The Construction Of Steam
Turbines?
A steam turbine basically has a mechanical side, and an electrical
side to it. The mechanical components include the moving parts (mechanical),
such as the rotor, the moving blades, the fixed blades, and stop valves, while
the electrical side consists of the generator and other electrical components.
Blades:
For starters, a simple turbine works just like a windmill. Only,
in the steam turbines of today, rather than striking the blades directly, the
blades are designed in such a way as to produce maximum rotational energy by
directing the flow of the steam along its surface. So the primary component
that goes into a steam turbine is its blades. The blades of a steam turbine are
designed to behave like nozzles, thus effectively tapping both the impulse and
reaction force of the steam for higher efficiency. Nozzle design itself is a
complex process, and the nozzle shaped blade of the turbine is probably one of
the most important parts in its construction. The blades are made at specific
angles in order to incorporate the net flow of steam over it in its favor. The
blades may be of stationary or fixed and rotary or moving or types.
Shafts:
The shaft is a power
transmitting device and is used to transmit the rotational movement of the
blades connected to it at one end via the rotor to the coupling, speed reducer
or gear at the other end.
Outer Casing:
The steam turbine is surrounded by housing or an outer casing
which contains the turbine and protects the device components from external influence
and damage. It may also support the bearings on which the shafts rest to
provide rigidity to the shaft. Usually split at the center horizontally, the
casing parts are often bolted together for easy opening, checking and steam
turbine maintenance, and are extremely sturdy and strong.
Governor:
The governor is a device used to regulate and control or govern
the output of the steam turbine. This is done by means of control valves which
control the steam flow into the turbine in the first place.
Oil System:
A steam turbine has thousands of moving parts and all these parts
not only have to move in high velocities, but also need to be protected from
wear and tear over the years. This is done by effective lubrication by the oil
system, which governs the pressure, flow and temperature of the turbine oil,
the bearing oil and lubrication of other moving parts.
Pipes:
The pipe is an all important steam turbine component that brings
the steam from the boiler to the turbine. This has to be done without an appreciable
loss in pressure, and at the same time, must be able to withstand all these
pressures safely. The pipes should be easy to clean and are prone to deposits
on their inner surfaces. Deposits on the inner surface of the steam pipe reduce
the net steam flow area, throwing forth a negative effect on the efficiency.
How Can A Steam Turbine Be Improved?
Steam Turbine Applications
