Typical controllers

While the technology backing the fabric filter is important, an equally important factor is the way in which the filter system is controlled. Today's fabric filter controllers normally only adjust to the differential pressure (dP) across the entire filter. This means  that the filter system maintains a certain dP. without consideration for filer bag conditions and actual dust load from the cement mill. This is not ideal, as the main fan will have to maintain one pressure at all times despite fluctuating work conditions and loads. Under such conditions, the main fan consumes an undesirable amount of energy.


As filter bags age, the amount of dP required to flow through them is often higher. However, traditional controllers do not recognise changes in filter bag condition and will not adjust accordingly. The results the requirement of constantly cleaning the filter system, compromising the length of filter bag life and energy consumption levels.

graph showing typical baghouse controller

Smarter control

FLSmidth recognize this challenge and has developed a next generation of air filter controllers. The SmartPulse EVO II controller continuously analyses specific filter operating conditions, based on the rate of change of differential pressure across the filter, which is driven by the load from the cement mill.


The SmartPulse EVO II adjusts filter cleaning parameters to cater for fluctuating plant operating conditions. This ensures that only the minimal required cleaning is carried out at any given time. This smarter way of cleaning reduces costly compressed air usage and extends filter bag life.

Figure 2 shows the SmartPulse EVO II following the actual load from the cement mill. The dP settings in the filter controller will always follow the actual dP, as indicated by the red line.

Graph showing auto-adjusting baghouse dP based on process conditions

“We have noted performance improvements in the mill’s inlet pressure, as a result of the new smart bags’ increased filtration area,”

Irfan ButtMaintenance Manager of the plant

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