Heat loss estimate for plume rise of flue gas

[bimba_88]

Hi,

I hope you can help me with the following problem.

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A large natural gas fired power plant producing 300 GW of power releases sulfur dioxide(S02) during its operation. The S02 is released from a 40 m stack at a rate of 20 g/min. The average wind speed is 12 m/s, with strong solar radiation. What is the distance downwind of the plume centerline emission point at which the predicted 502 ground-level concentration falls to about 2 ug/m3?
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I have the equations for Gaussian modeling of the concentration plume distribution and the stability class parameters. My question is how to estimate the plume rise and finally calculate the effective stack height. With no information about flue gas temperature or other, I think I should use the power produced by the plant to estimate the heat loss in dry flue gas and therefore the plume rise, but couldn't find any satisfactory relation.

Any ideas on how to work with the given data?


Thanks so much!

 

[georgeverghese]

Slow release non turbulent Gaussian and turbulent jet release plume pollutant release profiles are modelled on commercial simulators like PHAST. Shell uses its own simulator FRED. It may be possible to get a short term user license for these simulators, else ask a local engineering contractor company which has an active technical / process safety department.

 

[bimba_88]

Thanks, georgeverghese.

This is actually an exercise as part of an engineering test, so the use of simulators is not an option. The iteration is supposed to be by hand and I have the equations and constants for that, but not much data (other than what I posted) to estimate the plume rise.

 

[georgeverghese]

To get the mass rate or the temp of the flue gas, you could approximate this flue gas to largely air. If you know the mass rate, you could work out the flue gas exit temp, given the specific heat of air.

 

[chicopee]

I am perplexed about your problem as you heading states heat loss estimate and inyour OP you state concentration level at certain distance from source, so what is it?

 

[georgeverghese]

To get the waste heat exhausted, you'll need the design case value for the net thermal eff (NTE) of this power plant at the design case power generation of 300GW ( btw, I find this power gen rate to be somewhat incredible). If NTE is say 80% for a combined cycle power gen plant (it may be around 30% for an open cycle), then waste heat rejected to the stack would be (300/0.8)*0.2 = 75GW. If you then know the mass rate of the flue gas from all the gas turbines, you can then work out the exit flue gas temp as suggested earlier.