ALC - Aerodyne

We recently posted an article on our LinkedIn commenting on the dangers of combustible dust, and we want to keep the conversation going about dust hazard analysis (DHA).

In many industrial facilities, rotary valves are a critical part of the dust collection system. They help move collected dust and material from hoppers while maintaining proper airlock conditions within the system. Unfortunately, traditional rotary valves can also become a source of frustration.

Selecting the right cyclone dust collector is critical for maintaining airflow efficiency, controlling dust, and protecting equipment performance. However, sizing a cyclone is not simply choosing a standard model based on airflow alone.

When designing a dust collection system, the static pressure required of the system is extremely important.  The reason is because the exhaust fan must be able to pull the design airflow at the design static pressure in order to get the design performance.  Usually the higher the static pressure is the greater power is required by the fan at a constant airflow.  This means, dust collector system designers usually try to keep the total static pressure low, in order to go with a smaller fan that costs less to operate.

When selecting the best cyclone for your process, there are many different factors that affect the sizing and cost of the cyclone.  The cyclone must be sized so that it handles the airflow of the system and components.  The proper design for the required removal efficiency must be used.  The process will also dictate the materials of construction and special requirements.  The location where the cyclone will be installed will influence the cyclone orientation.  Cyclones aren’t a stand-alone piece of equipment; support equipment is required for proper operation.  Therefore, the scope of supply will affect the cyclone costs and design.  The following is a brief description of the different elements that affect cyclone sizing and pricing.

Simple Timers

For many years, pulse-jet baghouses were cleaned by simple timers.  The timers would start the cleaning cycle every so many minutes.  You would be able to change how often your filters are cleaned by changing the time between each cleaning.  This design makes sure that the filters are cleaned regularly, whether they need to be cleaned or not.  The main issue with this is that every time a filter is cleaned, it increases the chances of it failing.  Filters are cleaned by pulsing high pressure air into the filter.  This expands the filter, which causes the top layers of dust to fall off.  But that expansion can also cause holes or rips in the filters.

While not cleaning your baghouse filter is bad, cleaning your filters too much isn’t a very good idea either.  If you don’t clean your filters enough, dust will build up on them faster and they will plug up faster; however, cleaning them too much can cause issues too.

Baghouses and cartridge collectors are usually designed to handle a maximum of 6” Water Column (W.C.) of pressure drop.  This means that when the baghouse pressure drop is 6” W.C., the airflow through the system is enough for proper operation.  When the pressure drop across the bags is greater than 6” W.C., the airflow through the system is less than it should be. The baghouse uses a control system to keep the pressure drop through the system less than 6” W.C.  Most baghouses use compressed air to clean the bags, but shaking and sonic cleaners are also used. 

Dust collections systems are complex entities.  They consist of multiple pieces of equipment, and if one of them is not operating correctly, could cause the failure of the whole system.  All dust collection systems consist of the dust collector (cyclone, baghouse, cartridge collector, wet scrubber), exhaust fan, ductwork and hood/pickup points.  Each of these is extremely important to the operation of the system. 

Baghouses and cartridge collectors are usually designed to handle a maximum of 6” W.C. of pressure drop.  When the baghouse pressure drop is 6” W.C., the airflow through the system is enough for proper operation.  When the pressure drop across the bags is greater than 6” W.C., the airflow through the system is less than it should be. The baghouse uses a control system to keep the pressure drop through the system to less than 6” W.C.  Most baghouses use compressed air to clean the bags, but shaking and sonic cleaners are also used.