December 25, 2007

How much you know your Boilers or Steam Generation System?

I am starting this open discussion for the benefit of all the readers / visitors of this site. Many students & even process engineers do not fully understand the concept of efficiency calculation methods especially for steam system and in particular steam generation system.

So let me ask you One simple question.....Will the boiler efficiency increase if I increase combustion air temperature?

If your answer is Yes then probably you need to read & discuss the entire issue again.

If your answer is No then again you need to define the terms & explain them.

So I am not putting much here now...as I am leaving it open ended for discussions among all of you...........& will come back later on this topic.

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4 comments:

Anonymous said...

I think increasing the temp of combustion air will increase the boiler efficiency & this is what we are reading in general.

Roger Craig said...

Well just increasing the combustion inlet temperature will not make your boiler more efficient per say. It will however cause you to over fire your boiler and produce more steam. But it will not make the unit super efficient. Second adding more fire side heating surface area and water side surface area will more than likely help with efficiency giving the fluids more of a chance to transfer their energy to the water. (Yes combustion gas is a fluid) Third if you measure the BTU input of the fuel energy vs. the BTU outlet of the stack as the means of calculating efficiency you will be most efficient during a cold boiler at start up. WHY? Because your outlet stack temp has a chance to be below 100 C when your boiler is producing steam in a fire tube boiler there is no chance for your outlet stack temp to drop below 212F because if your water is boiling that is your T(low) which cannot be surpassed by the law of thermodynamics. And it is wasted energy to heat up you ambient air with your expensive fuel.all

shahzad1166 said...

Dear Craig,
Do you think that the heat used for air heating will be nullify the increase insteam quantity.(as you said..
It will however cause you to over fire your boiler and produce more steam...

i think more steam generation means increase in efficiency.

Roger Craig said...

Where is your energy coming from to increase you combustion air temp? (I answered this a long time ago and its kind of rusty) Over-fireing is kind of like after burners on a jet yes it makes you go faster but its not efficient. If you are just increasing ambient temp of the room yes it makes it more efficient but according to ASME or BMA (Boiler makers of America) there is a set ambient temperature that your ambient inlet air must be to calculate your efficiency.

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