Time resolved measurements of pulse intensity, filter movement and regeneration during cleaning of baghouse filters

The “cleaning intensity” of a filter bag during pressure-pulse regeneration is a determining factor for both the stability of the filtration cycle and the emission level. On the other hand, the relationship between the shape of a pressure pulse signal, the resulting movement of the filter media (i.e. position, velocity, acceleration), and the removal of dust from the surface and/or interstices of the filter media is still not fully understood. An experiment has been designed around a coupon filter testing unit (VDI Type 1), to measure all three components of this puzzle with a high time resolution. Filter movement is measured by triangulation; dust cake removal by high-speed imaging; and the internal dust currently via the residual pressure drop. Measurements on one type of filter media and one type of dust have shown how different phases of the pressure signal correlate with different stages of media motion. In case of sufficient cleaning intensity, it was found that cake detachment occurs for a constant product of deceleration and dust mass, i.e. at a fixed threshold force. In case of low pulse intensities, when the required acceleration is not reached, cake detachment occurs much later, due to back-flushing.