INDRAPRASTHA POWER GENERATION CO. LTD. (IPGCL):Under IPGCL two power stations are in operation:Rajghat Power Station:-

TOTAL CAPACITY: 135 MWUNITS: 2x67.5 MWWATER USED: YAMUNA WATER

COAL POWER PLANTCoal from the coal wagons is unloaded with the help of wagon tipplers in the C.H.P. this coal is taken to the raw coal bunkers with the help of conveyor belts. Coal is then transported to bowl mills by coal feeders where it is pulverized and ground in the powered form. .

This crushed coal is taken away to the furnace through coal pipes with the help of hot and cold mixture P.A fan. .

Water from boiler feed pump passes through economizer and reaches the boiler drum. Water from the drum passes through the down comers and goes to the bottom ring header. Water from the bottom ring header is divided to all the four sides of the furnace. Due to heat density difference the water rises up in the water wall tubes. This steam and water mixture is again taken to the boiler drum where the steam is sent to super heaters for super heating. The super heaters are located inside the furnace and the steam is super heated (540 degree Celsius) and finally it goes to the turbine. .

Fuel gases from the furnace are extracted from the induced draft fan, which maintains balance draft in the furnace with F.D fan. These fuel gases heat energy to the various super heaters and finally through air pre heaters and goes to electrostatic precipitators where the ash particles are extracted. This ash is mixed with the water to from slurry is pumped to ash period.

The steam from boiler is conveyed to turbine through the steam pipes and through stop valve and control valve that automatically regulate the supply of steam to the turbine.

Steam from controlled valves enter high pressure cylinder of turbines, where it passes through the ring of blades fixed to the cylinder wall. These act as nozzles and direct the steam into a second ring of moving blades mounted on the disc secured in the turbine shaft. The second ring turns the shaft as a result of force of steam. The stationary and moving blades together.

Gas Turbine Power Station:-

TOTAL CAPACITY: 270 MWUNITS: 6x30 MW (GTs)3x30MW (STGs)WATER USED: YAMUNA WATER

ELECTRICITY FROM GAS TURBINE POWER STATION:

A gas turbine power plant, also known as a Combined Cycle Gas Turbine Power Plant combines the strengths of two thermal processes in ideal fashion Electricity production using a gas turbine together with a steam turbine. .Around two thirds of the electrical power generated is produced by the gas turbine. The hot gases that this process creates drive the turbine and, with it, the generator That is coupled to it. The rest of the electrical power generated, roughly a third, is produced by the steam Turbine using the hot exhausts gases leaving the gas turbine. In the heat recovery steam generator (HRSG) the exhaust gases transfer their heat to the circulating water: thepressurised water vaporises, causing the temperature in the system to rise. The steam drives the steam turbine and, with it, the generator that is coupled to it.Gas-fired combined-cycle power plants are technologically advanced and used throughout the world. Compared with other types of power plant, they are highly efficient:the state-of-the-art EGL plants in Italy achieve a percentage in the region of 56,meaning that the energy supplied in the form of fuel is converted into electricity as efficiently as technically possible. Investment costs are comparatively low because the main components are largely standardised. The extremely powerful gas turbine allows for a compact power plant,which minimises construction time to around two and a half years.Gas-fired combined-cycle power plants are built modular, consisting of several Blocks. Each block is practically a self-contained power plant that can be operated independently.The standardised EGL power plants all have two blocks with a combined yield of around 760 megawatts. Compared with all other conventional thermal plants, such as coal-fired power plants, carbon dioxide and nitric oxide emissions are lowest when plants are fired with natural gas.

PRAGATI POWER CORPORATION LTD. (PPCL):Under PPCL two power stations are in operation:Pragati-I combined cycle gas power station:

TOTAL CAPACITY: 330 MWUNITS: 2x104 MW (GTs)1x122MW (STGs)WATER USED: TREATED WATER FROM SEN NURSING HOME AND DELHI GATE STPs

Pragati-III combined cycle gas power project, bawana:

PPCL settled up 1500 MW Gas Based Combined Cycle Power Project in New Delhi. Power generated by this project had utilised during Common Wealth Games.

CAPACITY-4 x 250MW GAS TURBINES2 x 250MW STEAM TURBINESTOTAL CAPACITY-1500MW

Steam Turbine (Prime Mover)Working PrinciplesHigh pressure steam is fed to the turbine and passes along the machine axis through multiple rows of alternately fixed and moving blades. From the steam inlet port of the turbine towards the exhaust point, the blades and the turbine cavity are progressively larger to allow for the expansion of the steam.

The stationary blades act as nozzles in which the steam expands and emerges at an increased speed but lower pressure. (Bernoulli's conservation of energy principle - Kinetic energy increases as pressure energy falls). As the steam impacts on the moving blades it imparts some of its kinetic energy to the moving blades.

There are two basic steam turbine types, impulse turbines and reaction turbines, whose blades are, designed control the speed, direction and pressure of the steam as is passes through the turbine.

Gas TurbineWorking principleGas turbine engines derive their power from burning fuel in a combustion chamber and using the fast flowing combustion gases to drive a turbine in much the same way as the high pressure steam drives a steam turbine.One major difference however is that the gas turbine has a second turbine acting as an air compressor mounted on the same shaft. The air turbine (compressor) draws in air, compresses it and feeds it at high pressure into the combustion chamber increasing the intensity of the burning flame.It is a positive feedback mechanism. As the gas turbine speeds up, it also causes the compressor to speed up forcing more air through the combustion chamber which in turn increases the burn rate of the fuel sending more high pressure hot gases into the gas turbine increasing its speed even more. Uncontrolled runaway is prevented by controls on the fuel supply line which limit the amount of fuel fed to the turbine thus limiting its speed.

The gas turbine is comprised of three main components: a compressor, a combustor, and a turbine. The working fluid, air, is compressed in the compressor (adiabatic compression - no heat gain or loss), then mixed with fuel and burned by the combustor under constant pressure conditions in the combustion chamber (constant pressure heat addition). The resulting hot gas expands through the turbine to perform work (adiabatic expansion). Much of the power produced in the turbine is used to run the compressor and the rest is available to run auxiliary equipment and do useful work. The system is an open system because the air is not reused so that the fourth step in the cycle, cooling the working fluid, is omitted.