The drawing and the bad day

Every baghouse has two operating temperatures. The media only ever experiences one of them, and it is not the one on the drawing.

Media selection tends to get treated as a price decision, which is understandable, because by the time it reaches a tender document that is the only variable left on the page. But it is really a temperature and chemistry decision, and the price follows from that rather than the other way round. Four questions settle most of it.

The first is temperature, and specifically the gap between the continuous operating temperature and the peak the plant actually reaches on a difficult day. Our media range covers a very wide band, but the material that performs at the top of that band is not the material that performs in the middle of it. If the specification is written against the design figure and the plant regularly runs above it, the bag is being asked to do a job it was never chosen for.

The second is what the dust chemistry is doing between cleaning cycles. The average pH of the gas stream tells you very little on its own. The swing tells you almost everything, because it is the swing that the polymer has to survive.

The third is moisture, and whether the gas passes through its dew point during start-up or shutdown. If it does, then cake release becomes the constraint that governs everything else, and filtration efficiency stops being the number that decides the choice.

The fourth is mechanical rather than chemical. What is the can velocity, and does the cage geometry genuinely match the bag? Perfectly specified media sitting on a poorly matched cage will fail early, and when it does, it fails in a way that looks exactly like a media problem to everybody involved.

PPS, P84, aramid or glass is the answer to those four questions. It was never meant to be the starting point.

Talk to our technical team.

#IndustrialFiltration #Baghouse #FilterMedia #CementIndustry #AirPollutionControl