Chlorinated Water from Chlorination Unit content White deposite.

[memo94]

Hi,

Please anyone has any information about this problem:
In an offshore oilfield we are using sea water to feed Chlorination Unit to Produce Sodium Hypochlorit to inject to suction of Sea Water Intake Pumps (SWIP).

We have found a white deposite in the produced Hypochlorit that is highly soluable in diluted HCL solution, and I believe it is CACO3. The concentration of Cl2 is OK but we have to make Acid Wash with an Inhibited Solution of 3-5% HCL very often.


Anyone has been facing this problem before?
Why do we have this deposite? What is This deposite?
And how can we prevent the formation of this deposite?!

Many thanks for your help!

Mehran

 

[Muggle]

I suspect your using electrolysis to create the sodium hyperchlorate - if so, then the fracturing of calcium carbonate and other calcium containing chemical compositions in the water will create precipitates of calcium - normally on the electrode surface, but also free in the water.

You need to filter the water following electrolysis to remove the precipitate - and probably need to clean the electrode failry often to prevent large build up on the plates, which then falls off from agitation of the water within the cell.

This can be difficult to filter, as the acidity of the solution makes the calcium soluble - then when you dilute, the precipitate forms due to change in the pH. So the solution will probably be to create the dilution and filter it as opposed to the direct sodium hyperchlorit solution.

 

[memo94]

Hi Muggle,

Many thanks for your reply.
It is exactly correct, we are using electrolysis.

Do you have any idea how can we prevent fracturing of Calcium Carbonate and other calcium containing chemical composition?

This is abnormal, because I have been in another oilfield that was using the same process to produce Sodium Hypochlorite by electrolysis, but I never faced with such a problem there!

Thank you very much for your help.


Mehran

 

[Muggle]

The fracturing depends on several factors - but primarily - it's the amount of applied current. If your running too high a current - then you need to reduce it to stop the fracturing of the carbonates - sodium hyperchlorit does not take more then about 20amps to get a good production - if running higher - this may be main problem.