Study of movement and dimension of filter cake patches during pulse jet cleaning by high-speed stereo camera

In industrial plants exhaust gasses are cleaned from solid particles by bag filters. These filters are cleaned from the particles that have been collected at their surface by the pulse jet cleaning, an efficient regeneration method. This kind of filter cleaning takes advantage of a pressure pulse of compressed air to allow the layer of solid particles to be removed. Unfortunately, this pulse detaches the cake in an aggressive way. The cake disintegrates into fragments that are pushed to the filter bags nearby, where most of them reattach, lowering the overall regeneration efficiency. The regeneration efficiency and energy consumption are considered as relevant criteria to assess the cleaning process for optimization. In particular, this work analyse the influence of the tank pressure used during the cleaning phase , the environmental conditions, and the height of the cake, on the dimension and travel distance of the cake fragment. A test rig used is based on the VDI3926 guideline. In particular, a flat filter made of polyimide fibres and limestone as test powder are used. A stereo optical system is installed to take the measurements of size and position of detached cake patches. The height of the cake is studied by evaluating images of the camera system and gravimetrically. The movement of the patches is fitted to parabolic paths as of free fall. Finally, the problem that patches detach and go to the filter nearby cannot be avoided but can be reduced. The results show that the tank pressure plays an important role on the distance that the patches traveled away from the filter, as well as on the energy required to provide the jet of compressed air, and on the regeneration efficiency of the filter. In particular, a low pressure is recommended. The height of the cake has a minor effect on these results and major on the dimensions of the detached patches, while the environmental conditions have not a significant influence in the analysed range.