Blockage Of Chlorine Injection Lines on Sea water Lift Pump 2

[K. Adam]

Good day Gents,
We are suffering from frequent blockage in the chlorine injection lines to our seawater lift pumps in offshore and the main challenge for us is deblocking of injection lines at the subservice area which is quite difficult as we have to pull the pump out of the casing in order to do so and practically not visible. Kindly requesting to share your experience and give some proposal for permanent solution as we are suffering from marine growth which is reaching to service and clogging our filters / exchangers.

 

[SJones]

What is the mechanism of blockage formation?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[georgeverghese]

Blockage of injection lines may be due to one or both of the following, both of which are related to insoluble calcium hypochlorite which is co generated with sodium hypochlorite:
a)Line velocity may be too low. It has to be kept above 0.5m/sec to prevent solids from settling
b)Pockets in the injection lines may be where these solids are settling. Piping runs with pockets must be demolished and redone with no pockets.

From memory, I've read that pretreatment of the feedwater to the hypo generator to remove hardness ( Ca/Mg bicarbonates ) leads to better quality hypochlorite and longer life of hypo generator. This will also help to eliminate insoluble Ca/ Mg hypo from settling in these small bore injection lines.

Presume you are injecting hypo continuously, and also shock dosing at higher flowrate once a month or so also. Addition of some other biocide, such as glutaraldehyde, also helps to improve effectiveness of sodium hypo. Talk to water treatment specialist for details.

 

[EdStainless]

Using pre-treated water is a necessity.
As are the rest of the George's comments.


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P.E. Metallurgy, consulting work welcomed

 

[SJones]

The OP is offshore. Feedwater for the generator will be seawater.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[EdStainless]

Is it filtered? Do they adjust the pH? Do they do anything to it?
It doesn't need to be softened fresh water, but raw seawater is asking for trouble.
There are specialty chemical mixes meant to be used this way, but they cost more.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[SJones]

@Ed

If the OP is using an electrolytic hypochlorite generator it will be a packaged unit that should have all of that good stuff built in.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[pierreick]

Hi,
Similarly that happens when you treat raw brine with Sodium Carbonate and Caustic soda , salts of Magnesium and Calcium are precipitating .
Regular cleaning with Hydrochloric solution (5%) should be considered .
My 2 cents
Pierre

 

[georgeverghese]

Some 10years ago when I worked on an offshore seawater de aeration project, the ancillary hypo generator had no demineraliser unit for removing hardness. It was some months after this project when I learned Mg(OH)2 is virtually insoluble in water. And this would drop out in the high pH environment of sodium hypo solutions.

 

[LittleInch]

K Qindeel.

As you can see there is a lot of experience here, but we need your feedback to identify what your system is.

You say Chlorine injection, but we don't know in what form - Chlorine gas? Sodium hypo chloride? Something else?
Is it continuous?
How are you making the injection fluid?
Are you doing any fluid / water treatment before making Sodium hypo Chloride.
What is the velocity in the injection piping?

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

 

[K. Adam]

Dear all, I do respect and appreciate all your feed back. I do apologize as I'm in an emergency situation and I shall continue the discussion with you gentlemen next week as I'm out of the office in an emergency trip.
Thanks and again I well appreciate all your answers.

 

[LittleInch]

Thanks for letting us know. We all appreciate events on the ground take precedence. Now we know to wait for a while.

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