Progressive and Compartment Kiln Drying/Seasoning, Compared

Progressive VS Compartment Kiln Seasoning of Timber

All dry Kilns now on the market are either progressive or compartment kilns. In the progressive type the drying condition increases in severity from one end of the kiln to the other, the material being moved into severer conditions as it dries. In the compartment type the same temperature and humidity prevail through out the kiln at any one time, beginning with mild conditions and increasing severity as the material becomes dry.

The kiln-drying data and experience of the Forest Produces Laboratory indicate that each type has particular advantages on certain points, as follows:

Figure 1. Process of Progressive Kiln Seasoning.

 The progressive type kiln requires less skill in the operation. It consumes less heat per pound of water evaporated from the wood, but the saving of steam possible should not be considered so important as the best result. the progressive kiln reaches its greatest heat efficiency in drying from the green state and is most useful in circumstances which permit of its being supplied continuously with green lumber of one thickness and class. It is, however, impracticable with this type of kiln to give individual attention to special loads of lumber.

Figure 2. Process of Compartmental Kiln Seasoning.

The compartment type of kiln is more flexible and affords greater control over drying conditions, permitting less change in temperature, humidity, and circulation in the kiln with variation in the wind and weather. It is better adapted to meet the varying requirement of different types of materials and is most useful exact and careful drying is required, as in the handling of refractory woods.






Information retrieved from lecture notes from the University of Technology, Jamaica.