1 reply to this topic

[StevenP]

New friends, as this is my first post,

Hopefully this is a simple question for someone. I am working on removing certain contaminants from a hot gaseous exhaust stream.  The exhaust comes from a kiln that is regenerating wet activated carbon granules.  The gas temperatures in the hot end (product discharge end) of the kiln are approx. 1200-1300F.   I measured the temperature of the gas exhaust stream from the kiln, after it is diluted some with plant air, as being approx. 750F, and the gas pressure at that point is approximately negative 5" WG currently.  The volumetric gas flow rate for this exhaust was previously measured as 1100 SCFM, but we are not sure whether we can trust this number. 

 

I want to cool this gas stream using ambient plant air (at 50-90 F and ambient pressures) to the 350-400F range prior to the emission control equipment.  My planned emission control equipment will not deal very well with free water (droplets) or condensation, so I want to ensure that this cooled gas, at 350-400F is not saturated with water.

 

The combined, diluted hot kiln exhaust will be at slightly negative pressure...within the negative 10"WG to negative 3"WG range.

 

So, the question(s):  This exhaust gas stream, which will be cooled from 750 F (at around atmospheric pressure) to the 350-400 F range using ambient air and is, when combined, at (basically) atmospheric pressure, cannot be saturated with water vapor at the 350-400 F temperature range, correct?  

 

I intuit that if I keep the exhaust gas temperature above 300 F at all times, and the wetted parts of the emission control system components at 300F or above, there will be no chance for condensation in the system (or only a chance for a very very low amount of condensation, anyway). But, I am having trouble "proving" this to myself. Is there a way to prove this assertion? I've crawled through many psychrometric charts, which I am generally quite comfortable with, and still cannot prove it 100% to myself at this point. So I am reaching out to folks more knowledgeable than I. Thank you for any comments.

 

[thorium90]

I'm not sure if it will be helpful, but you can try reading the US EPA regulations for methods on these. If I remember correctly, I think it is in Title 40 Part 60.