Do you use emissions reduction equipment to reduce VOC's from your kilns?
What type of system do you use?

Hi Mike,

The best way to reduce VOCs is to have a proper heat recovery system on your vents together with a smart software. This will reduce the VOC but it will of course create kiln condensate.

Does that make sense to you?

The nature of the VOCs certainly stays the same. I am just saying you have less VOCs with heat recovery because the recovered heat will be transferred into kiln condensate. 

Hi Craig,

The water that we have to evaporate out of the lumber will always stay the same and it has to go somewhere. So when I am saying less VOC I am just referring to less steam coming out of the vents. There will be condensate instead. So I am saying that the overall plant emissions will be down and the VOCs will be down but not the kiln emissions since they are a result of evaporating the water in the wood.

Makes sense? 

If you reduce steam use, I agree that plant emissions will be reduced because less fuel is burned.  I'm not sure that a heat recovery device reduces overall kiln emissions.

In my earlier post, I said the heat recovery device does not remove emissions.  If one pound of VOC enteres the device in the gas phase, the about one pound leaves in the gas phase.  A tiny amount goes into the condensed water based on Henry's law.  Same for HAPs.  The water is too warm to absorb volitile organic componds. 

I simply cannot agree that VOCs are reduced by a heat exchange device that condenses some of the vent steam to water.  Most VOCs will stay in the gas phase.  A tiny amount will go into the water, but not enough to change a permit. 

If you need evidence of this just look at how emissions testing is done (it is an NCASI method and I don't remember the number, maybe 98 or 99).  Kiln gas is bubbled through impingers with the water  to close to 32F, then the VOCS are collected as a gas in summa cans after the impingers.  If the VOCS  were water soluble, they would go into the 32F water.  Very little does.  I have run the method.  The water in a heat exchanger is far warmer and even less of the VOCS enter the liquid phase.  Keep in mind - the pinenes, fatty acids, etc (the high molecular weight stuff) are hydrophobic to begin with and don't mix with water.
Now consider the low molecular weight stuff.  In NCASI method 105, we again use impingers to get the aldehydes (formaldehyde, acetaldehyde etc) into the water at 32F and react them with benzyl hydroxyl amine to form a high molecular weight, hydrophilic compound to keep them in the water at 32F.  Everything is keep on ice or refrigerated until lab analysis.  We can capture methanol pretty well in 32F water without a reaction, but all these low MW compounds are too volatile to ever stay in water at the temperature in a heat exchanger. 

I hope that makes it clear where I coming from on this.  Besides all that I have measured VOC before and after a heat exchanger.  The heat exchanger did not remove VOCS or methanol or formaldehyde even though water was condensed ("less steam coming out the vents").

Hi Ingo,

it sounds like you are starting to believe your own marketing around vent heat exchangers.

they are and always have as much use as cat-flaps on elephant houses, just my opinion!
Keith Haigh

Congratulations on the sale Ingo, I will come and visit the kiln, but you have to buy the beer !!!