If you’ve worked with rotary airlock valves before, you know how dust and other fine particulates can accumulate, often presenting a serious environmental hazard. This stems from suboptimal valve leakage management. Due to rotary airlock valve design, some leakage is inevitable. But it’s your job to keep it to a minimum.
Below are six solutions for handling this issue.
Solution 1: Directly attach a rotary airlock to the container.
The simplest solution is a closed system in which the holding container is connected directly to the rotary airlock. Usually, the container will be connected to a bin vent filter that exhausts excess air after separating it from the dust. Be aware that this system requires a relatively porous substance, and an operating pressure below 8 psig. It’s best to only use it with pellets or fluidized powders.
Solution 2: Install a vented surge hopper.
When installed correctly, a surge hopper is the most effective way to deal with an air leakage. By intermediating between the storage vessel, and the conveying system, the surge hopper forces the excess air through a vent filter. A surge hopper can be implemented with a secondary rotary airlock, feeding material from the storage container into the hopper; a flood feed from a larger storage vessel directly connected to the hopper; or a metered feed with an intake fan installed in the vent.
Solution 3: Add a vent pipe atop the vessel.
If you’re worried about leaked air moving through your material, install a vent pipe that leads to the top of the vessel. This is done with a vented surge hopper, using either a secondary rotary airlock valve, or a flood feed, to transfer material from the storage vessel to the hopper. With the former, leakage air can be circulated back up to the top of the vessel, where it can be dealt with by the bin vent filter. With the latter, a fan must be installed with the bin vent filter to create suction.
Solution 4: Create a central dust collection.
If you want to centralize your dust collection, hooking up all the vented surge hoppers to a central dust collection system may be the most effective solution for you. Using soft connections will let in sufficient ambient air to maintain proper suction.
Solution 5: Install an eductor
In some cases, you may require a dedicated device that moves all intake to a destination of your choice. If this is so, an eductor can prove useful. The eductor uses pressurized gas to create a vacuum that sucks up dust, and leakage air. It then forces the dust and leakage air, through vent piping, to another location. This new location can either be the top of the storage vessel, so the particles can run through the system again, or the conveying system via direct injection, if the system is operating at less than 5 psig.
Solution 6: Add an airlock body/boss vent.
The body vent, or boss vent, is a feature of some rotary airlock vents that assists in efficient air management. In high pressure differentials, the resulting air volume significantly restricts material intake. To compensate, a boss vent lets air escape the rotor pockets through vents in the rotor housing. This is especially helpful in systems with a fast rotor speed (18 rpm or higher).
So which solution is best? The professionals at Streamline Industries can work with you to find the optimal solution for your businessneeds. With the help of Streamline Industries’ experts, you can rest assured knowing things are running as efficiently, and cleanly, as possible.
To learn more about any of the services Streamline Industries offers, give us a call today.