Gas turbines

[ramesbas]

Hi,
I have a question regarding a gas turbine application, where the exhaust gas goes directly to a dryer. The dryer needs certain amount of power to dry the clay, 7,500,000 kcal/h. I need to calculate if the exhaust gases of the gas turbine can produce it.
How can I calculate it? I am preparing a first estimate economic analysis, so I don't need it that detailed.
Dryer: 7,500,000 Kcal/h
Temp required: 600 C
Gas Turbine:
Fuel Consumption:132 mmBtu/hr
Flow rate: 181 ton/hr
Exhaust temperature: 500 C
Can I use the equation: P=mCp(T2-T1)
How can I figure this out?
THank you very much

 

[zdas04]

It is even easier than that. You need 600 C. You have 500 C. Quick answer, your exhaust gases are not hot enough to reach the target temperature so it doesn't matter how much of the gases you put into the dryer.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

 

[MJCronin]

I believe that you should incorporate the gas turbine exhaust into a hot air recirculation with supplemental firing.

The gas turbine should be selected based on electrical power load requirements and available capital cost.

There are many charts available on the internet showing gas turbine exhaust massflow rates and temperature.

What you are trying to do is difficult and has been rarely accomplished. A company in Nevada has done something similar with gypsum

 

[ramesbas]

Thank you very much, and you are completely right about supplemental fire for the exhasut gases. Nevertheless, How can I calculate it? I need to know that I can cover the thermal needs of the dryer.

I would appreciate if somebody could help. It doesnt have to be fancy, a simple aproximation will do.

 

[chicopee]

What type of gas is it?

 

[chicopee]

Since I had a little time in my hands, I decided to tackle your problem. I have attached an analysis of a combustion analysis of propane as a fuel for your gas turbines. This analysis has assumptions based on infomation, some of which is lacking and some of which is provided by you. My pencil notations and calculations are a bit light but you can zoom in if fuzzy. My assumptions are 50% of intake air is to cool down exhaust gases from combustor before such gases enter the turbine and a 200% excess air for combustion to take place in these lean fuel machines. In essence suggestions provided by above responders are true if my assumptions are correct. The exhaust gas has an energy level of 81.66xE06 btu/hr and its water content is 8% so there will be drying effects at 500 dC and supplemental heat would be to boost temperature requirement thru drier.

 

[chicopee]

Another comment is in regard to the dryer requirement of 7.5E06 Kcal/hr which is equivalent to 29.76E06 but/hr. My above example of 81.66E06Btu/hr is about 2.5 times higher but at a lesser temperature and that should satisfy your dryer's performance.

 

[ramesbas]

Hey I really appreciate your help, it actually makes perfect sense, using suplemental fire.
I ll study your calculation for the future.

Thanks again

 

[chicopee]

Remember the assumptions as your gas turbine may be different in design.