subject: Humidity Generating System And Method And Use In Wood Drying Kiln [print this page] An apparatus and method for generating water vapor or humidity, useful in a variety of applications, including wood drying kilns. The apparatus may contain a hydrophilic disk, a water supply structure that supplies water so that the water is deposited on the hydrophilic disk, and a motor for rotating the disk at a speed sufficiently high so that water which is deposited on the disk is caused to leave the disk in the form of a mist of particles or droplets which are sufficiently small to evaporate rapidly to generate the water vapor. The disk may be made hydrophilic by covering with a fabric.
A conventional approach for maintaining higher humidity is to use hot steam in wood drying kilns. However, the use of steam often raises the dry bulb temperature of the kiln at too high a rate. Further many plants do not have sufficient steam capacity to provide the required amount of steam. Typically a plant has a given boiler, and over the course of many years has added several wood drying kilns. There is enough steam available to dry the wood, but not enough to condition it by controlling the humidity level.
The benefits of controlling humidity in the wood drying kilns include maintaining a given drying schedule and obtaining surfaces with no checking, cracking, crazing or warping, or shortening the processing or drying time. The higher temperatures allow shorter drying periods for reaching the desired 6 to 8% moisture levels of dried wood by maintaining the humidity at a higher level when higher temperatures are used.
In general, the normal approach used in wood drying kilns are to gradually increase the temperature, while controlling the moisture levels in the kiln using the differential between wet bulb and dry bulb temperature sensors.
