Wood powder feeding, difficulties and solutions

A pneumatic fuel feeding system for wood powder fired gas turbines was incorporated at the Vienna University of Technology. One of the most important requirements of fuel feeding is a very homogeneous mass flow of wood powder. Therefore, the performance of the mechanical conveying part of the feeding system has been studied experimentally at flow rates corresponding to the operation range. Beside screw feeding, a vibrator is used to homogenize the flow rate. While the screw feeder shows large fluctuations, the vibrator conveyer reduces them considerably. The tests also show that for each flow rate a certain optimum amplitude of the vibrator exists at which the fluctuations reach a minimum. Furthermore, a linear function is observed between optimum oscillation amplitude and feeding rate.