How does Backwash Efficiency Affect Your Catalyst Bed Protection Filtration System?

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.

Backwash Flow:
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.

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The higher the velocity, the higher the potential for shock loading.

Velocity plays an important role when recommending a Strainer for a piping system. The higher the velocity, the higher the potential for shock loading (water hammer). Typically for metal piping systems the most desirable range is between 6 to 1 0 feet per second. For plastic piping systems the maximum recommended flow rate is 8 feet per second.

Most end users won’t know the flow velocity in their systems, but they will know the flow in gallons per minute. To convert gallons per minute to velocity Ft./Sec. take the GPM  0.4085 divided by the inside diameter of pipe squared.

(GPM x 0.4085) ÷ (ID² in Inches) 

Note: The above calculation is for water only.  

Using Your Cooling Tower Loop to Cut Waste and Costs by Eaton Filtration

Using Your Cooling Tower Loop to Cut Waste and Costs

A manufacturer of plastic grooming products approached Eaton’s filtration business about difficulties they were having while recycling mold cooling water through a cooling tower. Specifically, the cooling water was picking up airborne particulate matter in the process — requiring frequent blowdowns, maintenance and adding costly downtime on the molding machines. Traditionally, engineers have opted for disposable media filters because of their lower initial cost.

While initial cost may be lower for small batch operations, the same is not necessarily true for continuous operations. The reason for this is that a completely redundant filtration system is needed to maintain production — including piping, valves, supports, and service connections. Obviously, this is not an insignificant expense by any means. To remove this particulate, the company installed an Eaton AFR Tubular Backwashing Pressure Filter. With this type of filter system, the media is cleaned and regenerated while the unit remains on-line. This means a simple single-piping arrangement, minimal valving, and fewer connections – for a lower total system cost and reduced waste.

Since this installation, the company has eliminated costly downtime and reduced their waste.  What’s more, controlling suspended solids by filtration rather than blowdown substantially reduced their water use. And because the filter cleans itself only when necessary, treatment chemicals and waste disposal costs are minimized. 

For more information on the Tubular Backwash filter or other filtration solutions please contact an Eaton filtration sales represenative today.

Learn how to figure the ratio of free area to pipe area from Eaton Filtration

We are often asked how to figure the ratio of free area to pipe area when a customer changes/requires different perforations or  mesh sizes  in a industrial strainerHere is a simple calculation to do this.

A. With perforated basket( s ), take the gross · screen area of the model and size strainer times the percent open area of the perforation required and divide by 100. This gives the new free area. Divide the new free area by nominal area to get the new ratio of free area to pipe. Ex.: 2″ #72 with 7/64 perf- gross area 50.9 X 46.0 the (% open area of 7/64″) divided by 100 =
23.4. 23.4 divided by 3.35 (nominal area) = ratio free area to pipe of 6.9:1.

B. With mesh basket(s)- the same calculation as for perforated baskets above but use 5/32 perf (standard with mesh lined baskets) having 63.0% open area. After
you get the free area of the perf, multiply it by the open area % of the mesh divided by 1 00 to obtain the free area of perf/mesh combined. Divide this answer by the nominal area of the pipe to get the new  ratio of free area to pipe. Ex.: 2″ #50 with 100 mesh- gross area 64.0 X 63.0 (the % open area of 5/32″ perf) divided by 1 00 = 40.3. 40.3 X 30.3 (% open area of 100
mesh) divided by 100 = 12.2. 12.2 divided by 3.35 (nominal area) = ratio free area to pipe of3.6:1.

After you try it a few times, you will see how really simple it is!

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