Basic process and component description

 

Industrial Steam turbine Based power plants

 

1)  These are thermal power plants.

2)  Fuel used in these power stations is Coal, Oil or Natural gas. (Fossil fuels)

3)   In many countries steam turbine power plants produce bulk of the energy.

4)  In these plants Boilers convert chemical energy of the fuel into heat energy and iturbines use this energy in steam coming from Boiler to rotate the generator and produce electricity. 5)  In refineries oil is abundantly available as bi product hence oil will be uded as fuel, otherwise coal or natural gas are used based on cost and availability.

First step :Conversion of chemical energy to heat

 

In the Boiler furnace, Fuel and air mixture is burnt and enormous heat energy is released.

Second Step :Conversion of heat into mechanical energy

In steam turbine the energy in the steam is employed to rotate the turbine. Which in turn operates the generator to produce power.

 Associated processes in Steam Turbine based Power plants

Feedwater heating and deaeration

The feedwater used in the boiler is a means of transferring heat energy from the burning fuel to the mechanical energy of the spinning steam turbine. The total feedwater consists of recirculated condensate water and purified makeup water. Because the metallic materials it contacts are subject to corrosion at high temperatures and pressures, the makeup water is highly purified before use. A system of ion exchange.

Deaeator primarily helps to remove dissolved oxygen from feedwater in addition it also helps to condition the water by dosing various chemicals.

In deaerator water is sprayed and maintained at high temperature to help  the oxygen to escape from the system. Remaining oxygen is eliminated by dosing oxygen removing chemical hydrazine, Ph controlling chemicals are also dosed in Deaerator..

Boiler operation

The boiler is a rectangular furnace of around 40 feet height and 20 feet length and width.

Oil is fired from four burners located in front side. Air required for effective combustion is fired through a fan.

Steam turbine generator

The turbine generator consists of 13 stages of blades. Steam starts to flow from first stage at 103 Kg/Cm2. At fourth stage it reaches 42 Kg/Cm2. At the final stage pressure is maintained at vacuum.

 

 

 Steam condenser

The condenser condenses the steam from the exhaust of the turbine into liquid to allow it to be pumped. If the condenser can be made cooler, the pressure of the exhaust steam is reduced and efficiency of the cycle increases.

The condenser is usually a shell and tube type heat exchanger.

Cooling water circulates through the tubes in the condenser's shell and the low pressure exhaust steam is condensed by flowing over the tubes as shown in the adjacent diagram.

The condenser, in effect, creates the low pressure required to drag steam through and increase the efficiency of the turbines. The limiting factor is the temperature of the cooling water and that, in turn, is limited by the prevailing average climatic conditions at the power plant's location

From the bottom of the condenser, powerful condenstae pumps recycle the condensed steam (water) back to the water/steam cycle through deaerator.