3 replies to this topic

[Sridhar P]

Dear Sir,

In power plants, boiler blowdown is cooled by quenching with water before sending to ETP/Central Monitoring basin. This quenching water requirement increases the consumption of water.

Is there any other alternative to cool the blowdown water other than quenching or cooling across heat exchangers.

Is there any natural or other means of cooling the boiler blowdown, pratcised in power plants.

Please advice.

Thanks.

[ankur2061]

Sridhar,

Boilers require combustion air and if it is pre-heated before entering the fire box bettter combustion efficiencies can be obtained. You can have a heat exchanger which heats the combustion air by utilizing the hot blowdown water. However, the heat exchanger may be very big due to the poor heat transfer characteristics of air.

Alternatively use a air cooled heat exchanger for cooling the blowdown water. However, the economics of quenching with water and using a air cooled heat exchanger which requires electric power needs to be worked out to determine the optimum quenching medium.

Regards,
Ankur.

[breizh]

Hi,
Preheating the feed water is a good solution ,

Breizh

[kkala]

Blow down is normally less than 1% of feed water. As I have seen in two boilers, an energy efficient practice combines following steps.
1. Reduce pressure of continuous blow down drum (1st drum) to slightly higher pressure than of deaerator, leading flash steam there.
2. Install a coil of cooling water in discontinuous blow down drum (2nd drum) to cool blow down down to 45oC.
If the blow down goes to water treatment, temperature not killing "bugs" is 45 oC in the mentioned cases.
Mentioned BFW preheating by Breizh is realized in this way.
I have not seen air cooling, but it must be feasible in some cases. Air cooled condensers, applied in condensing turbines of Power Plants, make a similar case of air cooling.