Dear All, In our geothermal power plant we used a diluted sulfuric acid in the geothermal water pH modification system. We "manufacture" the diluted sulfuric acid (about 0.8 -0.9 % w) by means of the dilution of the 98% sulfuric acid with the slip stream of the untreated geothermal water. The dilution ratio is about 1: 100. The concentrated acid flow is 92 kg/hr and water flow is 10,000 kg/hr. The dilution water temperature is about 170 deg. C. We are experiencing quite a few problems with the dilution system when the biggest problem is that we are getting extremely high corrosion rates (about 0.1" in two weeks) in the Hastelloy C276 piping, especially around the 98% acid injection point in the water slip stream and through the 2" Static Mixer (Hastelloy C276) which located 2 meter downstream of the concentrated acid injection "T". Do you have an idea how I could find the cause of this problem? Thanks in advance, Mike

alloy B-2 can be a choice. pl. take help of ur corrosion expert. regards >Mike > >if you look on isocorrosion graph for C276 in Sulfuric Acid, >you'll see that the Corrosion Rate is above 200 mpy, approx >5 mm/y, at conc 80-100% and temp 170%C2°C. > > >hope this help > >vict > >http://www.corrosionist.com

Your slip stream water feed temp. is 170C and you are diluting 98% acid to 0.9% acid and here due to exothermicity post mixing temperature will be more higher. Here w.r.t. various isocorrosion curves it seems that Hastealloy D-205 can have the least corrosion rate ( approx. 0.3 - 0.4 mm / year) w.r.t. your condition. Pl. also consult your designer/ Process Control Engineer f you can reduce the slip stream temp. or flow rate or multistage step dilution system. You can also think about any suitable internal linining or external sleeve reinforcement as a temporary fix if it permits. with regards