Effectiveness of using Steam Coil Air Heater 1

[powering2002]

I would like to ask question. In Steam power Plant, is it effective to operate Steam Coil Air Preheater when we used natural gas as the fuel?..which do you think is better, Operating or not operating steam coil air preheater when we use natural gas as the fuel?
Thanks for your attention

 

[TD2K]

Preheating the combustion air reduces the amount of natural gas required for the same steam production.

What does your steam balance look like? If the steam used in the air preheaters is in surplus then it's essentially 'free' and using it makes sense. If you have to let down steam you are generating to condense it in the air preheaters then it makes no sense to do so because of the boiler inefficiency.

Another factor is that if you are combustion air limited then you'll likely reduce steam production capacity running the air preheaters because you have to flow hot air rather than cooler air to the boiler firebox.

 

[MJCronin]

Steam Coil Air Preheaters have several advantages aside from cycle efficiency

They are particularly important in trash-to-energy plants or where a oad of biomass fuel may be delivered wet....

http://www.powermag.com/coal/Design...rs-for-reliability-and-effectiveness_567.html

There are cold-end corrosion benefits as well..........you should know how all components function and operate on your specific plant !!

 

[powering2002]

I absolutely agree the we must operate the steam coil air preheater when we used Fuel Oil (residual oil) to prevent the sulphur from condensing. But, now the case is we use Natural Gas. Should we operate the steam coil air preheater (the sulphur content in natural gas is very low)?

 

[rmw]

You state that this is a steam power plant. Are there any other forms of air preheater? Often times SCAH's are used to keep the cold end buckets of a rotary APH from corroding. Nat gas is said to not contain sulphur, but it is rare that I have seen gas without some sulphur, so keep that in mind. Also, if you alternate between fuel oil with sulphur and gas with little sulphur, the back end of your boiler will have lots of deposits from the oil firing that have sulphur in them and if you don't keep the temps up above the dew point, moisture will condense, combine with the free sulphur present and form sufluric acid and eat the back end alive.

rmw