Study the relationship for ...
Published by Waymon Hofheins
Study the relationship for scale precipitation as related to the P and M alkalinities. You will find that lowering the pH to eliminate P ALKALINITY at pH of 8.2 changes dramatically the preciitation of calcium carbonate. In the old times (40's and 50's) sulfuric acid was added to lower the pH to the 7.2 level with chromate and zinc as the corrosion inhibitors. This was done on wooden towers. With metal towers a pH of 7.2 would be a vert questionable practice. Also keep in mind the precipition of gypsum caused by using SO4- .
You mentioned a power plant: Ok, they are probably looking at overall costs. Thus, sulfuric acid can yield higher cycles by knocking down the P alkalinity. Look at the saturation indexes to see what is happening.
With sulfuric acid they probably need some corrosion inhibitors to protect the metals. The probably need an azol for the copper/brass.
This could be a dangerous level running at 7.2, but it depends upon the other chemistry.
Have you done your homework, or are you just trying to sell chemicals. The plant manaer may know more about water chemistry than you when we look at your statement:
I thought each sulfuric acid and scale inhibitor has same performance....
They are different, and do different things.
You need complete water analysis for both the tower, and the makeup water. Ask the question: is the makup water the same year around, how does it differ with the season, does it have different water supplies. How do changes in the makeup water affect the treatment?