Water Filtration, 200 Gall/min 75 Micron, Cleaning Both Sides of Strainer Basket Element 1

[Papabyrd]

Hi All,

I've got a fairly unique issue with respect to process water taken directly from a river close to a Glacier and being filtered down to 75 micron.

The water is fairly silty with glacial till, talcum powder like fines. Algae is also present in the water stream. The fine size particles flow through the strainer basket and stick to eachother down stream of the wedge wire strainer basket. Over time this tacky material fouls up on the downstream side. Sort like the T-1000 in Terminator 2....

The system has used an automated strainer where it cleans the inside of the strainer basket. Typically I use the DCS product line from eaton, but cannot find a system that cleans both sides of the strainer element.

The system doesn't have sufficient capacity for pressure and flow to incorporate a HydroCyclone. We've paralleled in some sock filters as backup to this fouling issue have 3+ strainers.

Any ideas would be great as we've been stuck on this matter for over a year?

Thanks,

 

[Papabyrd]

2nd pic

 

[bimr]

Strainers are generally capable of removing 100 micron particles and larger. A strainer will not remove fine silt that may be less than 50 microns. A HydroCyclone would probably not work either.

To recommend a product, one would need to know the flow capacity and pressure requirements.

 

[Papabyrd]

Hi,

Some of the parameters were in the subject but here they are

200 Gall/min @ 75 Micron
Input pressure 30-50 psi.
Differential Pressure 3 PSID Clean max -6 PSID dirty pre deluge cycle.

Thanks,

 

[bimr]

Your options include

(1) A multi-media pressure filter system. Pressure filtration systems are designed for industrial water treatment where the removal of suspended solids such as particulates, iron, manganese, free oils, mill scale, and other precipitates in ground or surface water is require. You are looking at 2 - 3' diameter filters;

Filter

(2) A membrane microfilter or ultrafilter.

Ultrafilter

The pressure filter will probably be more economical.

 

[LittleInch]

Parabyrd,

What are you actually trying to do / your problem?

Is it trying to remove these very fine particles / algae / gunge from the water or
Trying to remove said gunge from the outside of your filter?

I think you really need to have a good discussion with a filter supplier like eaton - that looks a good system and they may be able to adapt their internal scraper to include an outer scraper.

I've seen systems which rotate around the outer skin of the filter also, but then you need some flushing system to use.

Or just pull the filters on a regular basis and jet wash the stuff off.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Papabyrd]

LittleInch,

We are trying to remove solids 75 micron and larger from a water source @150-200 gpm max per strainer.


Eaton were the first individuals contacted. I've purchased a handful of their DCF-1600 series strainers over the years with excellent results. Unfortunately the outside scrapper is not in there portfolio of products nor do I think they are interested in developing a one off unit.

I think we are stuck simply removing the baskets periodically to clean the downstream surface.

See attachment for configuration for better detail.

 

[bimr]

After reviewing this further, my understanding is that this facility is the CFNSC, a shore-based fish collector located at the north shore of the Cowlitz Falls Dam that is intended to capture downstream migrating smolt.

I understand that the specifications called for a 200 micron filter that assumes the 200 micron filter will remove particles larger than 75 microns. Silt that is smaller than 75 microns is passing through the strainer that was purchased for this project and these smaller particles are clogging the strainer.

It appears that the wrong type of strainer was selected for this project. Non-self-cleaning bag filters or strainers are not a good selection for this application.

What is needed is a self-cleaning screen filter. Several manufacturers (Lakos and Forsta Filters) make these self-cleaning high capacity screen filters. Refer to the links and attachment.

Lakos Link

Forsta Filters Link

 

[Papabyrd]

Bimr,

Were you on this project? The spec did have a #200 mesh/75 micron auto screen strainer and a manual screen strainer of identical construction to the Lakos filter. That auto strainer failed in multiple ways. Differential pressure strainers trying to vacuum or spray the debris of the screen element ultimately get fouled up with the algae.

The eaton DCF-1600 is an auto strainer of stainless construction which will likely be installed. The plunger can shear the debris off the elements surface.

 

[bimr]

No, not on the project.

Don't know why the original filter screen failed as only limited information has been provided. But note that the Lakos unit is used on algae applications.

From my experience, the wedge wire screens are more resistant to fouling than the sintered metal screens that you have been using.

Not sure if the Eaton unit will work either, it does not appear to clean inside the screen but wipes the screen, and most of the applications for the screen are chemical based, not water.

Based the experience that you have described, I would recommend a trial run prior to purchase.