April 10, 2012 Leave a comment
Filtration systems are generally regenerated through a backwash cleaning cycle. The primary factors effecting backwash efficiency are • Available pressure differential • Backwash flow • Filter media characteristics
Available Pressure Differential: During backwashing, the backwash differential pressure (between the backwash source and drain) should ideally be three to five times greater than the differential pressure across the dirty media. In a feedstock filter, the maximum dirty differential pressure should not exceed 15 PSID, meaning the backwash liquid should be delivered at 45 – 75 PSID to maximize the cleaning efficiency.
A sufficient flow rate of backwash liquid will also be required to regenerate the filtering media. The required flow rate will be primarily dependent upon the type of media selected. Sufficient backwash flow along with sufficient backwash pressure will lead to hydro-shock cleaning effect and completely regenerate the media to its clean differential pressure.
Filter Media Characteristics:
The final component of filter regeneration is the media characteristics. By their very design, slotted wedge wire and woven wire mesh allow particles to be captured on the surface of the media, providing optimum particle release and media regeneration. Sintered metal is multi-layered and can offer higher per-cake efficiencies, but can be difficult to regenerate. This leads to shorter run times and increased downtime.
In summary, feedstock filtration is an important aspect in efficiently refinery operation. Protecting catalyst beds from particulate contamination prevents bed plugging and increases catalyst life. Several factors affect filtration system efficiency and should be carefully considered when selecting a feedstock filtration system.