Kiln Drying Forum
Wood Drying Topics => General Discussion => Topic started by: Dean on May 13, 2019, 08:28:04 AM
-
Anybody use a EMC Mistifyer ( cold water spray ) instead of a steam line to regulate the EMC in your kilns?
-
Dean,
I have no experience with the Mistifyer. I built a spray system for the 2500 bf OSU dry kiln and it worked great for conditioning. The kiln could reach narrow wet-bulb depressions, even with dry lumber in the kiln.
I have heard that water sprays work well, but need regular maintenance. They are more common in the hardwood industry where conditioning is vital to the product.
Mike
-
Yes, I dry a lot of hard maple and try to keep it as white as possible. I try to keep the temp low but during conditioning the temp rises higher than I want. Maybe someone will chime in soon.
-
Are you using a cooldown period? I wrote the procedure at https://wooddrying.org/drying-tips/uncategorized/ . See also Denig's book "Drying Hardwood Lumber". It's available on line.
Denig will recommend 170F wet-bulb for conditioning. He indicates the risk of darkening the wood is low for the short time (6-12 hours) and when the wood is at a low moisture content (6-9%). Using freshly sawn wood from freshly cut logs also minimizes the risk of darkening.
Other things to prevent the rise in Tdry during conditioning
Desuperheat the steam spray
Shut off the steam heat valves manually if the control valves are leaking.
Reduce the fan speed to the minimum that can be used on your system. This will put less heat from the work done by the fans and reduce leakage from the kiln (which means you need less spray). Reduce to 25%, if you can. You don't need much air circulation during conditioning.
Most of the temperature rise comes from the vapor water entering the wood and becoming bound water in the cell wall. About 900 to 950 BTUs are given off for each pound of water vapor entering the wood.