Hygroscopic Dust Causing Issues in Your Dust Collectors? | Aerodyne
Hygroscopic dust can really grow on your nerves! Crossing my fingers that marketing doesn’t take away my writing privileges after that line (we would never do that to you Dan)! In all seriousness, hygroscopic dust can cause major maintenance issues in your dust collectors. Hygroscopic dust captures water vapor and droplets. This causes the particles to grow in size and weight, thereby making them easier to capture and remove from the airstream. Sugar (sucrose dust) is a great example. If you’re using filters, that’s where the problems start.
Filters capture dust in between the filter fibers and on the filter cake, which can create some issues when the dust is hygroscopic. Dust particles in the filter fibers can grow and plug filters when exposed to water vapor. Plugging prevents air from passing through filters, and that dust may not be released when filters are cleaned. This blocks air pathways and can deform filters, ultimately allowing particles through the filter.
This prevents any dust collection from the needed areas because there is no airflow to pull the dust into the system. And during cleaning cycles, the filter cake is strongly adhering to the filter and won’t fall off.
To prevent these issues, you will need to identify where the water vapor is coming from.
Airlock
If humidity is leaking in from the airlock, then a low leakage airlock is needed. Rotary valves have a small space surrounding the rotor allowing it to rotate without locking up. This area constantly allows air to leak out. A double dump valve, which uses two flaps in series to isolate the hopper, or a rotary valve with wipers can cut down on air/humidity leakage into the hopper.
Housing holes
If there are holes in the housing, high humidity outside air can leak in. Replacing or patching holes will prevent air leakage. However, if corrosion is an issue, changing materials of construction or coating the hopper might help prevent future issues.
High water content in the compressed air used for cleaning
Install water traps and filters to keep the compressed air used for filter cleaning at a low humidity. Oftentimes, this can cause greater issues than leaking airlocks or hoppers because the high pressure air goes through the filter, expands the filter to shake off dust, and delivers humidity to the dust collected in the filter, which can cause greater plugging.
High humidity air coming in with the dust
Installing a pre-filter removes the majority of the larger, heavier particles before they can see the filters. This minimizes the amount of material the filters contact, extending their life. Pre-filters such as cyclones and dropout boxes can often provide additional help on issues above and even extend the life of filters caused by high dust loading.
So if you’re dealing with hygroscopic dust and your filters are plugging up too fast, try to isolate areas where humidity could be coming in and take measures to prevent it.
To improve efficiency and safety, there is no substitute for an on-site inspection by an experienced expert.
To learn more about the right dust collection solutions for your application, please contact our experts here, or call us at 440-543-7400.
