Question

Figure out the INCORRECT reason from the below points for which 'ash' needs to be quenched before handling in steam power plant? 
1. Quenching maintains corrosion action of the ash.
2. It reduces the dust accompanying the ash.
3. It reduces temperature of the ash.
4. Ash forms clinkers by fusing in large lumps and by quenching clinkers will disintegrate.

Answer 1

Correct Answer - Option 1 : Quenching maintains corrosion action of the ash.

Concept:

A large quantity of ash is produced in steam power plants using coal.

Ash produced is about 10 to 20% of the total coal burnt in the furnace.

Handling of ash is a problem because ash coming out of the furnace is too hot, it is dusty and irritating to handle, and is accompanied by some poisonous gases.

It is desirable to quench the ash before handling due to the following reasons:

• Quenching reduces the temperature of ash
• It reduces the corrosive action if ash
• Ash forms clinkers by fusing in large lumps and by quenching clinkers will disintegrate
• Quenching reduces the dust accompanying the ash

Ash handling is a major problem due to the following difficulties in the handling and disposal:

• It is hot when comes out of the boiler furnaces
• It is abrasive and wears out the conveyors, containers, and Other handling equipment
• It produces dust nuisance.
• It produces poisonous gases.
• It has corrosive action.
• It forms clinkers by fusing together in lumps,
• It is dusty hence irritating and annoying to handle.
   

Conclusion:

So, ash quenching is not maintained but reduces the corrosive effect.