Engineered Transfer Chute Technology - Air Flow Analysis & Dust Mitigation

At a PRB region coal mine near Gillette, Wyoming, a controlled flow hood and spoon transfer chute system is in service. An inspection was conducted to analyze why excessive amounts of coal dust had been exiting the skirting end of the coal transfer to the point that the mine continuously failed its opacity test. During this inspection, static pressure taps and dirty air probes were installed into the system. Once the equipment was brought on line, static pressures and velocity pressures were measured. When the coal belt was stopped, fine coal particulate could be seen coming out of the entrance of the transfer chute where strong winds were observed. The study concluded that there is no change in air pressure or air flow once coal material travels through a transfer point. Air was found traveling with the stream and remained static above the coal flow inside the chute, and there was zero pressure variance inside the transfer from the hood section through to the spoon discharge. Because of this, research and calculations were conducted and a solution was applied to deal with the induced wind effect at the discharge of the chute system that ultimately caused the failed opacity tests. The research concluded that the controlled flow transfer chute maintained the induced air flow at the same rate of the coal flow and thus do not generate dust. This paper will discuss the study that was conducted in depth regarding how air flows through the controlled flow transfer system and the methods used to mitigate the external effects of wind and air flow beyond the confines of the transfer point.