Necessity of Alkalizer and Online Dissolved Oxygen Monitoring System

Thanks, PWSlack.

From your answer, I understand that it is better to provide alkalizer. But regarding dissolved oxygen in water, how is it possible that it will not be in DM cooling water?

Do u have any information reagrding at what levels acidic and oxygen content combination is harmful to stator windings of generator?

This will be great help.

Thanks, again.

Pick a system, from here. These all have O2 monitoring, etc.

The best people to ask about the necessity of an alarm system are the people that designed the system.

Is that to simple?

Thanks for reply, TonyS. That's what I wanted to know from industry veterans. If any body who has worked in such systems earlier can help me out.

Many generators use gas cooling as primary coolant, and the gas is cooled by water flowing through heat exchangers. I am not familiar with the system you describe, so could be a good person, and describe this in a bit more detail? Usually a closed loop cooling system that has no water leaks, there is not much requirement for chemical addition, and I have seen a few of those where no conditioning of the water is needed, other than a small addition of either nitrite solution, molybdate, or silicate. When the pH of these systems is above 9.2 and up to around 9.6 or so, corrosion has nearly vanished.

First of all, thanks all for showing interest in my question.

Dear James, Answering to you query, large machines - in the range of 500MW and more - applies water as well as gas cooling for stator and rotor. So, my question relates to closed loop cooling water system (primary coolent of stator winding), that is DM water chemistry.

Now having understood this, I would again ask to u and other engineers that is it OK if any customer says do not provide alkalizer and oline dissolved oxygen monitoring system for optimized solution of cost saving, life and over all performace?

Thanks.

Stainless steels operate in a different regime of conditions than carbon steels. To simply make a blanket statement that dissolved oxygen would be OK in such a case would be sophomoric. Stainless steels can undergo a stress-crack corrosion mechanism leading to complete failure of the metal when conditions of (1) stress, (2) oxygen, and (3) chloride or sulfate are all present. High stress systems - those where the temperature difference is the highest will experience the higher failure rates. To avoid this, in some instances, the cooling loop needs to have a higher degree of pure water where the surface temperatures are high. These plants will have a primary coolant system (cooling tower circulation), and a secondary loop (purified water goes here), with appropriate chemical additives to minimize anodic corrosion mechanisms.