Questions on Thermal Power Plant

Thermal Power plant interview questions and answer

What are boiler mountings?

boiler mounting are mounted on the boiler itself and mandatory required for safe and proper operation of boiler

1.water level indicator
2.pressure Gauge valve
4. Blowdown valve
5.Feed Check valve
6.Main steam Stop valve

what are boiler accessories?

Boiler accessories are components that are attached to boiler and used for working of boiler and increasing its efficiency

1.Feed pump
2. Economizer
3. Air preheater
5. super heater
6.Ash handling system

what type of boiler does not need steam drum?

Super critical Boiler

Why it is unsafe to have high water condition in drum?

High Drum Level does not allow efficient steam water separation and makes water to carry over with steam to turbine.

What are the causes for boiler tube failure?

Due to long term overheating due to scales and deposits formed on the outer surface of tubes

Short term overheating , occurs due to flow restriction in the tube

Thermal stress and shock , occurs due to frequent start and stops

Erosion, occurs due to coal , oil, ash corrosion

Creep occurs due to constant stress of material at high temperature

Why boiler is purged every time before starting?

To remove any left over fuel in boiler which leads to explosion

What are the uses of oil firing?

1.warming up of boiler due to cold start up
2.increase the furnace core temperature to switch to coal firing
3. Stabilizing flame when interruption occurs to coal firing
4.Useful during low load operation

What is the pressure and temperature of super critical boiler?

Boiler operating pressure is more than critical pressure (221.2 bar and 375 deg temp) is called super critical boiler. At this point both steam and water have same density.

how to find incomplete combustion in boiler

high carbon oxide content at flue gas at exit

The efficiency of Rankine cycle is in the range of

35-45 %

On which factor does calorific valve of coal depend upon?

Ash content

What is Thermal Energy?

The ratio of heat energy to the turbine to heat of coal combustion