There are two types of startup's in a thermal power plant. They are
1) Cold startup
2) Warm startup.
The procedure for the both the process is same but the time taken will be more for a cold startup and less for a a warm startup. First let us see the general procedure and then differentiate between the two.
1) The oil guns are fired in lowest elevation and the oil used is light oil as there the heavy oil cannot catch up fire directly, initially the light oil is fired.
2) Once sufficient temperature is reached then the heavy oil will also be fired.
3) Steadily the oil firing is done at different elevations i.e., heights. This process will go on until sufficient temperature is reached to introduce the coal. The oil required will be maintained in the pump house called the fuel oil pump house. Sufficent level of oil stocks should be mainained as per the necessity and proper maintenance of the Oil guns to be done
4) As sufficent temperature is reached the along with the oil coal is also introduced into boiler through different corners.
5) During the whole process the BFP( Boiler feedpump) will be providing the water to boiler and the generated steam is bypassed from entering the turbine through the HPBYPASS and LPBYPASS. once sufficent criteria is maintained the ESV( Emergency stop valves) of the HP Turbine is opened. Then the turbine is rolled to 360 RPM.
6) After meeting all the criteria to allow the steam to enter the turbine the turbine is rolled to rated speed and the the unit is synchronised and the steam enters into the turbine by opening the control valves.
7) Once unit is synchronised the load in raised consistently until the requirement or rated capacity as needed.( Requirement < Rated capacity)
The main difference between cold and warm startup is the oil firing and the coal firing will take more time and process will be done slowly in cold start up to ensure the proper heating is done at all levels and equipments as all the equipments will be having less temperatures.
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