subject: A Method Of Monitoring Wood Drying Kiln [print this page] A method for monitoring the wood drying kilns of wood in a kiln is described herein. The method uses a set of known good samples of moisture content data for wood dried in a kiln to estimate a Lognormal statistical distribution which approximates the known good set of data. The method estimates three parameters of a Lognormal distribution: the threshold parameter, the shape parameter, and the scale parameter. Then one or more new sample of moisture content data is obtained from a subsequent wood drying equipment in the kiln. The method develops one or more control charts containing center lines and control limits which monitor at least one of the estimated parameters. Next, data from the new sample or samples of moisture content data is transformed to represent the parameters on the control charts. Finally, a determination is made about whether the kiln is operating in an in-control or out-of-control state.
The method utilizes a known good set of moisture content data for wood dry equipments and wood dried in a kiln under set conditions to estimate parameters for a Lognormal distribution which approximates the moisture content data for those conditions. The method creates control charts which monitor some of these parameters. The method also takes data from subsequent kiln charges and transforms it to be represented on the control charts. The method uses this representation to determine if the kiln is operating under out-of-control conditions.
Wood naturally contains moisture. However, for wood lumber to be useful for building, the moisture content must fall within certain constraints. Too much or too little water in the lumber can cause serious problems in the subsequent processing and use of the lumber, including warping or difficulties with painting or gluing. In order to provide a useful product, most lumber mills dry their lumber under controlled processes, such as in a kiln, prior to sale. It is difficult, however, to ensure that every board in a given charge will have exactly the same moisture content after wood drying kilns.
