seawater electrochlorination 1

[yulinios]

Hi there!

In a coal power plant 135MW, electrochlorination is used to avoid growth organic fouling in sea water intake pipes and turbine steam condenser, there is a control of free chlorine in the outside of that condenser between 0.05 and 0.2 PPM like free chlorine.

Is possible to shutdown electrochlorination plant by 1 week, and working 2 weeks?

Bye there

 

[hacksaw]

kinda depends on the following rate. sounds like you'd better make provision for controlling the growth (Cl injection) while your normal protection is shutdown

 

[yulinios]

Hi
Hacksaw, we spend a lot of energy to get hypoclorite from sea water, stopped our electrochlorination plant for a while could save money, but we are concern about the growth organic fouling during that period of time, I would like to get some ideas to work only in periodic times to save energy.
Thanks, bye.

 

[unclesyd]

I'll echo hacksaw's statements and add that shutting off the Cl isn't a good way to save money. I would look at other ways to save money your electro chlorination system. If you shut the system off and some sort nasties get established you will have to run the system at a higher rate to rid the system of them which can and probably cause other problems.
I don't think it's a good idea except for very short periods for maintenance or inspection.

Your levels of free Cl are quite low compared to some I've seen so I wouldn't mess it up.

 

[MMcLean]

This is analogous to chlorinating a saltwater swimming pool, except yours is a continuos process. If the system goes out of wack too much and the chlorine conc. drops, it can be a pain to get it back into line. Obviously the consequences in your case are far more catastrophic. I would keep the electro-chlorinator running at a level just above the minimum required to keep the system in balance, as I did with my pool. If you are controlling chlorine level in a continuos flow line, I wouldn’t try to run it intermittently. In a pool, obviously you can, but it needs to be run for longer in summer when chlorine losses are higher.

 

[EdStainless]

Many systems use burst chlorination, treating only 4 hours/24 or some schedule like that. In some cases they actually turn it off, in most they turn it down. The most common cases use 0.1ppm residual Cl at discharge during low periods and 2-3ppm during peaks.
If you are running <0.5ppm continous you are probably not supressing all biological growth. And with any burst or cycled system you will get more growth. The idea is that the high treatment phase will kill all existing biofilm and limit the total fouling.
How much fouling can you tolerate?
How well can you measure fouling? (actual B.P. vs a model)
How much do your fouling rates chage with season?
One viable option that may not impact plant preformance much is to adjust Cl cycling based on season/inlet water temp.
If you want to discuss this further contact me.
ed

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Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[yulinios]

Thank you for your answers!

Answering your questions:

Turbine steam condenser can't tolerate big fouling, because some increase of temperature cause less efficiency of steam turbine, beside of chlorine sea water every week we have 2 procedures to avoid fouling like backwash and ball cleaning system which consist of recirculating ball sponges with additional pump and screens in condenser ouleto to recuperate those balls.

We can't measure the biofouling because we don't have the sea water flow exactly which is more or less 15900 cubic meter/hour its variation depends of tide.

10 months/year seawater have 15°C in averge +/-1°C, in our summer this value increase until 20°C, chlorine consume is more in that time as you said.

I'm trying to get more ideas to test the potential of water to develope biofouling.

Thanks guys.

 

[annmariehopkins]

I have a question on this topic that I hope somebody can answer.

In some UK power stations it is common practice to shut down sea water electrochlorination plants in mid winter when the sea water temperature is less than ~ 9 deg.C. The reason given is that in their experiance bio growth is low in winter. However Electrochlorination plants will only produce minimal hypochlorite at low temperatures.

We are commissioning a sea water Electrochlorination plant used to prevent fouling on a power station cooling water circuit. Winter sea water temperatures get down to 6 or 7 deg.C.

Are there any guidelines or standards as to when it is safe to shut down the Electrochlorination plant because bio growth is so low running the plant is not justified?