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.

For more articles, tips and information on industrial filtration products and solutions visit our blog at eatonfiltration.wordpress.com or simply follow @AskFilterman on Twitter

Eaton Filtration Success Story for United States Tissue Manufacturer

Tissue Manufacturer Replaced TWO Basket Strainers with ONE Self-Cleaning Filter

This Resulted in Greater Profits!

A United States Tissue Manufacturer was using two mesh basket strainerswithin their Paper Processing line. The strainers preceded their glue application nozzles, and their main responsibility was to filter out the large glue particles before they migrated into the spray nozzle path. If the particles were not removed, the spray nozzles integrity would be compromised which was very expensive to fix. The basket strainers limitations required constant operator attention (24/7) due to the need to manually clean the unit. This took precious time out of the employee’s day to exclusively monitor the basket strainers, and then clean them whenever necessary.  In addition, the chances of large glue particles migrating into the product stream were increased due to the inability of the screen to automatically detect the unwanted material, and then make internal adjustments to remove them. This many times required the raw material to be filtered several times to ensure the large particles would not migrate into the spray nozzles. The combination of all factors resulted in lower profits for the entire facility.

The Tissue manufacturer discovered that one Eaton brand self-cleaning filter could replace their costly, maintenance intensive basket strainers. They found that the filter eliminated the need for an employee to monitor and clean the basket screens, which increased the length of their run time. In addition, due to the implementation of the self-cleaning filter, the raw materials only needed to be filtered once, rather than multiple times. This permitted them to increase their profitability!

SITUATION

To begin, a Tissue Manufacturer had been having problems with their spray nozzles clogging due to large glue particles migrating through the production line. In addition, due to the clogging of the spray nozzles, lesser quality end product was sneaking through which mandated the need to filter the raw materials time and time again. At first they thought the answer was the use of two basket strainers positioned within the manufacturing line to reduce glue particle migration. However, once the strainers were placed they noticed shorter run times, lesser end product, as well as another escalating cost — employee overhead!

Unfortunately, the company had only succeeded in transitioning the issue of the glue particles clogging from the spray nozzles to the clogging of the basket strainers. Worse yet, the strainers had to be constantly monitored 24/7, as well as require a dedicated employee to manually clean each screen when it became clogged. They also had to filter the raw material several times to ensure a well-filtered (clean) stream. Therefore, they were out the cost of the employee, valuable raw materials, as well as the fact that overall production time was lengthened.

Run time: The run time of the production line was decreased due to the need to clean the screen each time the filter screen was clogged. This resulted in lengthening of overall production time, which flew in the face of their lean manufacturing process goals

Costs: The need to designate one employee to monitor — and subsequently clean — the screens increased the cost of production.  And, they had to re-filter materials several times to catch the unwanted glue particles. If this is not bad enough, if some larger particles slipped thru the system the spray nozzles would clog which triggered additional costs.

Profits: The Company had to continuously monitor the basket strainers; which was taking away much needed resources from other areas of production. It was necessary to clean the basket screens several times per day, and consequently employees had to establish whether the raw materials that were just filtered, required additional filtering. When all the issues were analyzed together they identified a significant decrease in their profitability. Subsequently, it was determined that they needed the advice of a filtration expert.

SOLUTION

Eaton’s Filtration business,  analyzed their situation, and determined that one DCF-800 self cleaning filter could replace their two basket strainers.

The Eaton brand DCF self-cleaning filter is a closed system that is not open to the atmosphere, relying on pump pressure (not gravity) to filter liquids. This filter would tackle their shortened run time, monitoring issues, and escalating employee/raw materials costs that resulted in lower profits. Their headaches could be handled with one self cleaning filtration unit!

The DCF self-cleaning filter is based on a simple concept: cylindrical stainless steel housing contains a filterscreen; unfiltered liquids enter the inlet; solids are deposited on the interior surface of the filtration media; and filtered fluid exits at the outlet. This enables the filter to be completely enclosed, and run automatically with minimal operator intervention.

The Paper Processing application details are as follows:
Model: DCF-800
Liquid: Water Based Glue
Retention: 230 micron
Pressure: 10 psi (0.69 bar)
Flow Rate: 5 gpm (18.9 l/min)
Viscosity: 1.4 cps
Contaminant: Paper Fiber

RESULTS

Due to this new self-cleaning filtration system, the need for basket strainers was eliminated, as well as the need for employees to monitor them. And, the secondary filtration of raw materials was unnecessary. This resulted in approximately 10/hours/week labor savings and enabled their run times to be longer.

Most importantly, because the Eaton brand DCF-800 was placed prior to the glue application nozzles it eradicated any large glue particles filtering thru to the next stage, which were the spray nozzles. The costs for extra spray nozzles, employee overhead, and re-filtration of raw materials were eliminated! 

Impressively, the customer ended up purchasing a second DCF-800 because of the success of the first.

 
If you would like to discuss this filtration solution with one of our highly trained Applications Specialists, please contact Eaton today.

If you would like to read more published real-world documented case studies about how our industrial filters have helped customers improve their bottom line, please visit the Eaton filtration website.

How to Avoid Common Industrial Filter Installation Mistakes

Correctly installing your self-cleaning filter is the first step to ensuring the life expectancy of your unit as well as optimal performance. Incorrect installation can affect the filter’s systems, cause it to operate poorly or damage the equipment. The following is a brief collection of easily avoidable installation conditions that may cause problems during filter installation:

Low System Pressure

Since self-cleaning filters and magnetically coupled filters rely on a purge operation to clear captured solids from the filter, having enough pressure is important to successful purging. I recommend a minimum of 30 PSI (2 bar) of system pressure to ensure an adequate purge. This pressure may need to be higher when the process liquid has high viscosity or the solids are sticky. The Stealth Purge option with external water flushing is an alternate solution that is independent of system pressure.

 

Purge Line Plumbing

A common error when installing mechanically-cleaned filters is incorrectly plumbing the purge line. The best situation for a purge line is to make it short in length, placing it on a downhill grade from the filter, and draining it into a collection tank. Since typical purge operations are less than 1 second in duration, there is very little flow in a purge line due to system pressure. If the line runs uphill, solids will collect in the line and never flush away. In addition, a water flush line on the purge header may be needed if the purged materials are especially challenging.

 

Check Valves on the Filter Outlet Plumbing

Running an outlet line into long, high head runs (such as uphill) is an uncommon, yet potentially damaging situation. When the filter purges, a water hammer situation may develop if flow reverses from the outlet side of the filter. In the worst case scenario, this may cause the elements to collapse. However, this situation is easily prevented by placing a flow check valve on the outlet line from the filter.

 

Filter Placement Around The Pumps

Since Eaton filters are pressure filters, they should always be placed on the outlet side of pumps. Placing the filter on the suction side of a pump may result in erratic operation or damage to the filter elements.

 

Back Pressure On Outlet Lines

Eaton filters always work best when there is some back pressure on the filter?s outlet. The worst performance scenario for a filter is when the outlet runs directly to an atmospheric tank. For this reason, we recommend the installation of a flow orifice or control valve on the outlet header of the filter. By providing a slight amount of back pressure, the system will operate much more evenly and avoid pressure blinding.

 

Backwash Filter Media

When your filter?s backwash outlet line runs to an atmospheric tank, we recommend using a flow orifice sized to prevent excessive differential pressure across the filter media during the backwash operation. This will prolong the life of the filter media.

 

External Backwash Liquid

The fluid source used in external backwash filter systems should be clean ? and have particles smaller than the rated retention of the filter elements in the system. If these conditions are not met, the backwashing process can actually plug the elements instead of cleaning them.

 

For more information on resolving these or other filtration challenges visit the AskFilterman on Twitter!