Re: Rotary Dryer Issues - Wood Chip Drying
You mention that your damper valve is 2/3 closed. Is there any air being fed into the dryer or is the composition of the exhaust gas only the water evaporated and any air that leaked into the dryer? My bet is that the answer is the latter. You need to maintain a driving force for evaporation throughout the dryer, that is, the humidity of the gas inside the dryer must be less than that which would be in equilibrium with the wood chips in the dryer. I have some equilibrium data and with some other information, I can come up with a solution. Send me an email (gmehos@jenike.com).
Regards,
Greg ■
Re: Rotary Dryer Issues - Wood Chip Drying
Greg: Thanks for your response. At 1/3 valve opening, the airflow rate is roughly 1.2m/s. We increased the opening to higher position (airflow rate to 2.4m/s), we managed to reduce the moisture to a lwer value, however still not enough... This is a direct heated dryer, and fan located outside the building, sucks the hotair, moisture and combustion gas, through the dryer, cyclones, and to a vent.
One question is that would it help if we reduce the raw material particle size? Currently our material passes through 50mm sieves. We can reduce it to 35-40mm... I am trying to find some correlation between particles size and heat requirements... Thanks. ■
Rotary Dryer Issues - Wood Chip Drying
Hello Everyone:
We are drying 45% moisture woodchips (particle size < 50mmx20mmx10mm) to 15% using a rotary dryer (14m long, 1.6m dia.).
We have a 25000m3/hr suction at the cylone end. We have been getting not so good results with the system, as it drops to moisture to 20% but not below.
We are already using a very slow rotary speed (RPM), and feed rate.
There is one important thing to mention that at the rotary exhaust there is a valve which controls the suction rate. This valve is at 2/3 closed position, thus the suction (or vapour discuarge) may not be very high. Also the temperature at this discharge point is rougly 65degC (550degC inlet temp, 65degC exhaust).
We are puzzled with the findings, thus seeking advise from experts... Any thoughts?
Typical Rotary Dryer for Woodchips
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