Types of turbines

Steam turbines are used for the generation of electricity in thermal power plants, such as plants using coal or fuel oil or nuclear power. They were once used to directly drive mechanical devices such as ship's propellers, but most such applications now use reduction gears or an intermediate electrical step, where the turbine is used to generate electricity, which then powers an electric motor connected to the mechanical load.
Gas turbines are sometimes referred to as turbine engines. Such engines usually feature an inlet, fan, compressor, combustor and nozzle (possibly other assemblies) in addition to one or more turbines.

A water turbine is a rotary engine that takes energy from moving water. Water turbines were developed in the 19th century and were widely used for industrial power prior to electrical grids. Now they are mostly used for electric power generation.

Wind turbine. These normally operate as a single stage without nozzle and interstage guide vanes. An exception is the Éolienne Bollée, which has a stator and a rotor, thus being a true turbine.

Thermal power generation plant or thermal power station is the most conventional source of electric power. Thermal power plant is also referred as coal thermal power plant and steam turbine power plant.

The theory of thermal power station is very simple. A power generation plant mainly consists of alternator runs with help of steam turbine. The steam is obtained from high pressure boilers. Generally in India, bituminous coal, brown coal and peat are used as fuel of boiler. The bituminous coal is used as boiler fuel has volatile matter from 8 to 33 % and ash content 5 to16 %.To increase the thermal efficiency the coal is used in the boiler in powder form.

In coal thermal power plant the steam is produced in high pressure in the boiler due to burning of fuel (pulverized coal) in boiler furnaces. This steam is further super heated in a super heater. This super heated steam then enters into the turbine and rotates the turbine blades. The turbine is mechanically so coupled with alternator that its rotor will rotate with the rotation of turbine blades. After entering in turbine the steam pressure suddenly falls and corresponding volume of the steam increases. After imparting energy to the turbine rotator the steam passes out of the turbine blades into the condenser. In the condenser the cold water is circulated with the help of pump which condenses the low pressure wet steam. This condensed water is further supplied to low pressure water heater where the low pressure steam increases the temperature of this feed water; it is again heated in high pressure.

For better understanding we furnish every step of function of a thermal power station as follows:

1) First the pulverized coal is burnt into the furnace of boiler.

2) High pressure steam is produced in the boiler.
3) This steam is then passed through the super heater, where it further heated up.
4) This super heated steam is then entered into a turbine at high speed.

5) In turbine this steam force rotates the turbine blades that means here in the turbine the stored potential energy of the high pressured steam is converted into mechanical energy.

6) After rotating the turbine blades, the steam has lost its high pressure, passes out of turbine blades and enters into a condenser.

7) In the condenser the cold water is circulated with help of pump which condenses the low pressure wet steam.

8) This condensed water is then further supplied to low pressure water heater where the low pressure steam increases the temperature of this feed water; it is then again heated in a high pressure heater where the high pressure of steam is used for heating.

9) The turbine in thermal power station acts as a prime mover of the alternator.

After text activity

I. Reading Exercises:

Exercise 1. Read and memorize using a dictionary:

vortex, rotor assembly, axial compressor, base loads, coach lighting, ship's propellers, reduction gears, inlet, combustor and nozzle, electrical grids, interstage guide vanes, alternator, bituminous coal, volatile matter; water heater; lube oil

Exercise 2. Answer the questions:

1) What is a turbo generator?

2) What do large steam powered turbo generatorsprovide?

3) How are smaller turbo-generators with gas turbines often used?

4) How can the efficiency of larger gas turbine plants be enhanced?

Exercise 3. Match the left part with the right:

1. Turbo generators were also used on steam locomotives	a) that contains and controls the working fluid.
2. Gas, steam, and water turbines have a casing around the blades	b) as a power source for coach lighting and heating systems.
3. A water turbine is a rotary engine	c) the coal is used in the boiler in powder form.
4. To increase the thermal efficiency	d) communication, station alarms and turbo generator lube oil.

Exercise 4. Open brackets choosing the right words:

The efficiency of (larger/smaller) gas turbine plants can be (enhanced/ increased), if the hot exhaust gases are used to (generate/ create) steam which drives another turbo generator. Turbo generators were also used on steam locomotives as a power (source/ spring) for coach lighting and heating systems.

II. Speaking Exercises:

Exercise 1. Learn the definitions turbo generator; turbine; locomotive; pressure; voltage.

A turbo generator-is a turbine directly connected to an electric generator for the generation of electric power.  

Turbine - any of various machines in which the kinetic energy of a moving fluid, such as water, steam, or gas, is converted to rotary motion.    

Locomotive -a wheeled vehicle consisting of a self-propelled engine that is used to draw trains along railway tracks.  

Pressure -the force applied to a unit area of surface; measured in pascals (SI unit International System unit)) or in dynes (cgs unit); "the compressed gas exerts an increased pressure".  

Voltage-the difference in electrical charge between two points in a circuit expressed in volts.    

Exercise 2. Ask questions to the given answers:

1) Question: ___________________________________?

Answer: This super heated steam then enters into the turbine and rotates the turbine blades.

2) Question: ___________________________________?

Answer: Turbo generators were also used on steam locomotives as a power source for coach lighting and heating systems.

3) Question: ___________________________________?

Answer: This condensed water is further supplied to low pressure water heater

4) Question: ___________________________________?

Answer: Water turbines were developed in the 19th century and were widely used for industrial power

III. Writing exercises:

Exercise 1. Complete the sentences with the suggested words: combination; generator; provide; used; auxiliary

A turbo generator is the 1 of a turbine directly connected to an electric 2 for the generation of electric power. Large steam powered turbo generators 3 the majority of the world's electricity and are also 4 by steam powered turbo-electric ships. Smaller turbo-generators with gas turbines are often used as 5 power units.

Exercise 3. Compose a story on one of the topics (up to 100 words):

“A turbo generator for the generation of electric power”

“Types of turbines”

“ Thermal power generation plant ”

Дата добавления: 2015-08-03