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Explain ash disposal and dust collection in a thermal power plant.
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Ash disposal:- 

Various methods of disposal of ash are: 

Mechanical handling system. 

Pneumatic system. Hydraulic system 

Steam jet system 

Commonly used ash handling equipments are:- 

Belt conveyer 

Pneumatic conveyer 

Bucket conveyer 

Bucket elevator 

Screw conveyer 

Hydraulic sluicing equipment 

Trollies or rail etc. 

Dust collection: - 

1. Removal of ash from:- In furnace, this is collected in ash hopper installed at the bottom of furnace. Economizer dust(Ash) handling System: - In economizer ash is trapped; it is evacuated continuously, which is collected in ash hopper.

Air Pre Heater dust(Ash) handling system: - In air-preheater ash is trapped; it is evacuated once in a shift, which is collected in ash hopper. 

 Fly dust(Ash) Handling System: - In ESP fly ash is collected; Fly ash in ESP is collected in ESP Hoppers. 

2. Load on conveyer belt. 

3. Deliver to the space where it can be disposed off. OR Working Of Dust Collector(ESP):- 

ESP is located in the path of flue gasses near chimney. 

The first electrode is charged to a very high negative voltage. 

As the flue gasses with fly ash (dirt) particles move over it, they pick up a negative charge. 

There’s a second electrode consisting of metal plates charged to a high positive voltage (30kV to 60kV D.C. depending upon the electrodes spacing). 

The negatively charged fly ash particles are attracted to the positively charged plates and stick there. 

In this way only flue gasses without fly ash are passed towards chimney so air pollution reduces. From time to time, the collecting plates have to be cleaned by mechanical vibrations created by rapping the collecting plate & use a rotating brush to remove the collected dust. That can be done either manually or automatically. 

This removed fly ash is collected in separate container

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