Optimising the Heating of Industrial Kilns

Innovative energy efficient kiln-based heat treatment (HT) techniques are urgently needed for manufacturers of timber products to comply with new international legislation aimed at the eradication of pests and pathogens. International Standard on Phytosanitary Measures (ISPM) 15 specifies that all packaging timber must be heat treated to a known core temperature.  To meet this demand industry is likely to increase their energy use (and CO2 emissions). BHR Group and Forest Research with funding from the Carbon Trust have developed a tool that predicts the optimum heating conditions for a heat treatment chamber (kiln) and the timber materials being heat treated.

Project Goals

The aim of the project was to develop a modelling tool which can be used to optimise the operation of industrial kilns in real time. To do this the tool was required to calculate the rate of heat transfer through timber of different sizes.  This needed to be based on a thorough understanding of the thermal diffusivity of timber (a function of tree species, dimensions, moisture content, densities, initial timber temperatures, etc) gained through data collected from extensive laboratory and industrial experiments.  The work resulted in a software based design tool called TimberTherm™.

Applications

Armed with this tool, and knowledge of the heat flow within a kiln, kiln operators in future will be able to optimise their operations, reducing energy costs and CO2 emissions by 25%. To achieve this wider goal TimberTherm™ will need to be integrated within the control technologies of kilns.

When used in conjunction with expert operators enables confident prediction, without the use of expensive and sometimes unreliable core temperature probes, of the heat requirements for different types and quantities of timber and kiln thermal footprints and inertia.  As well as reducing energy cost the quicker turnaround of heat treatments can also improve productivity.  The design tool can also be customised to suit other processes involving heating kilns, such as cement.