Cooling Water Screen 2

[andrewdia]

I am looking at ways of improving the current method of screening cooling water. We are having problems with fouling of heat exchangers due to the make-up water.

I was wondering if anyone could let me know what they have seen, used or can recommend. Really, any help would be incredibly useful.

Thanks in advance.

 

[ash9144]

In CW service usually there is a screen on the pump suctions for large material. Usually no filters due to flow limitations. If you think you can filter the inlet water that would be a better choice. I would guess that your temperatures are too high in your process causing precipatation in the exchangers. Above 120 F can cause some issues. You should have a company that treats your cooling water, discuss the issues with them.

 

[pmover]

without knowing the details (process conditions, water quality, application, etc.), any possibility of the salts, minerals, etc. being removed from water before entering the exchanger? how about the make-up water? any treatment taking place there?

perhaps looking into the source of fouling and then corrective action can then be taken.

good luck!
-pmover

 

[andrewdia]

Sorry, I probably wasn't specific enough (new to all this).

Most of the problems are resulting from debris in the make-up water taken from a river. It is finding its way through the pumps into the exchangers.

We currently have two screens in series before the pumps, but materials are still passing through when they are lifted out for cleaning.

I'm looking into rotating screens and other self cleaning types which hopefully will redurce operator time input and maintenance costs. I was wondering if anyone knew of specific designs/models that they've seen or have used that work well, are cost effective, low maintenance etc.

pmover, it's for an Ethylene plant so high CW purity is not essential, just need the bits to be removed. Total cooling water flow is ~35000 m3/h. There's all the usual chemical treatment of CW (acids, Chlorine...)

 

[SeanB]

There are filters available specific to cooling water. Some models can actually be automatically back flushed when the dp across the filter reaches a set value. We have the same issue with cooling water here. Our make up cooling water comes from a river - with high suspended solids. This fouls up our heat exchangers pretty quickly.

 

[andrewdia]

Thanks Sean, Automated backflushing is looking good at the moment. We're installing a filter to remover the silt and other fines - seems to be cost effective. Have you considered one?

 

[SeanB]

I have proposed it to refinery management - but as of yet there hasn't been any decision.

 

[pmover]

As SeanB recommend, a filter may likely be the best corrective action to take. Thanks for the clarification as to the water and contamination source - sort of thought river water.

Good luck and welcome to the site. Feel free to continue posting.
-pmover

 

[rmw]

You are looking for a traveling screen I believe. I googled those two words and got a lot of hits. They are a common part of river water cooled power plants. You may want to look on some electric utility supplier websites.

That's my tip.

rmw

 

[JimCasey]

You might take out the chunks but the microsopic larval animals and Algae will require some special attention. Zebra mussels are now in most rivers and they can clog a HX solid. You'll need frequent temperature excursuions and biocide shock treatments to avoid (delay) biological buildup. You might speak to a water treatment specialist such as Betz for specific help in yur particular aplication.

 

[MikeInSWLa]

We do have a self-cleaning strainer that we use successfully on the cooliong water supply to some plate exchangers in our unit. I am sorry that I do not have any details on the construction, but the way that I understand it works is that it has a scraper or wiper that rotates on a periodic basis to clean the surface.
It has been pretty much maintenance free.
We were going to open this thing up earloer this summer, when we had a big problem with biosolids in our cooling water system. we were going to inspect it and replace some parts, kind of on a preventative basis. However, we fixed the biosolids problem and didn't get around to it.

 

[toothless]

Since your make-up water flow rate is probably only a fraction of the total circulation rate, are you considering filtering only the make-up water since that is where you state your problem is coming from?