Optimization of a wood-waste-fuelled, indirectly fired gas turbine cogeneration plant

Abstract Cogeneration of electricity and heat for drying lumber has been proposed, utilizing the wood-waste fuel generated as a byproduct of the sawmilling process. In older sawmills this has been achieved using conventional boilers and steam turbines to produce both electricity and process heat. The current use of steam systems on the small-scale of most sawmills is not usually economic, however. This paper presents the results of a study which examined the optimization of a gas-turbine-based cogeneration system, which eliminates the need for steam generation and distribution. Several systems which utilize an indirectly fired gas turbine have been analyzed to determine the optimum arrangement from an economic and technical point of view. Linear programming was used to determine the most attractive option economically. The overall conclusion drawn is that cogeneration is an economically attractive option for disposing of wood wastes for those sawmills which require large amounts of process heat, typically of the order of 20 MW, or more. In general it was found that cash flow was maximized when the cogeneration system was sized to meet the thermal requirements of the sawmill.