Tips for determining the best dust filtration method for your application.
Which is better—a Baghouse or a Cartridge Dust Collector? There are many strong opinions and compelling arguments, largely driven by the success or failure of installed projects. As one would expect, the answer boils down to good applied application knowledge as both technologies have pros and cons. While every application can have its own list of unique or special challenges, we recommend the following guidelines be considered:
Know your application
Knowledge of your application is paramount to providing an optimal filtration system. If the collected particulate is sticky, tacky or has any agglomeration characteristics which allows it to adhere to itself, a cartridge collector will operate very poorly. When the pulse cleaning mechanism engages a cartridge, the pleated “peaks & valleys” do not expand like a filter bag. Instead, they collapse in on themselves. When this occurs with a very sticky application, the collected particulate will be pressed into the internal valley of the cartridge pleat. If this material does not release and drop out, that portion of the filter area is effectively blinded over which puts more demand on the remaining effective filter area. Under these conditions, the differential pressure of the system will increase, resulting in either higher power consumption of the system fan or fan overload and failure.
Should the unit incorporate an inlet located in the hopper or elevated near the top of the dirty air plenum as a high entry inlet? Surprisingly, the location of dirty inlet on a cartridge collector does have an impact on the effective operation of the unit. Consider the following:
A cartridge collector will incorporate a smaller vessel. This is a trademark advantage of this style of unit; optimal filtration in a smaller and more compact package. However, the internal velocities play a significant role in the effective operation of the filtration process. There are two terms for the measured velocity inside a baghouse: Can velocity is the upward air velocity below the bottom of the filters. Interstitial velocity is the upward air velocity between the filters. If the interstitial velocity is too high, the dust will stay in suspension and not drop into the hopper. If the dust stays in suspension, it will gravitate to the filters and ultimately penetrate and blind them over, causing a high differential upset condition which can only be corrected by changing the filters.
There are several solutions which can offset this upset condition:
- Increase the spacing of the filters will lower the interstitial velocity. However, this will increase the vessel size, effectively negating the most important advantage of this design approach.
- A better solution is to offer a high entry inlet. If designed properly, the airflow will enter the dirty air plenum and disburse with a downward flow pattern. This greatly reduces the interstitial velocity and protects against re-entrainment of the particulate.