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Steam coil material for Acidulation tank

adv.   

2007

I would like to design for steam coil for sulfuric acid tank at concentration of about 70% at about 70degC.

I understand that H2SO4 is very corrosive to stainless steel, so it might not be a good option for Steam coil material. Can I get an advise from you?

As for the tank, I will do fiber glass lining of about 10mm, but I can not line the fiber glass on steam coil, because fiber glass is a good insulator.

Jo Lee
Engineer - Malaysia

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2007

Sir:
When sulfuric acid (at 8% to 15% and 70C) is used to pickle steel in hot dip galvanizing the usual heating coil materials are: zirconium, graphite filled teflon, and graphite (carbon as a hollow block). Another way to heat sulfuric acid is with a teflon "spaghetti" coil. Still another way is with a "carbon stick" atmospheric heater in which the products of combustion are expelled directly into the acid. A newer version which contains a real burner is available from a company advertising in the hot dip galvanizing section (GTI located in Texas the trade name is Thermaflow). This last device evaporates about twice as much acid as the coils so efficiency compares to a boiler and coil; it is good for counter-current rinsing. Your acid concentration is very high so I am not sure which heaters may work for you.
Regards,

Dr. Thomas H. Cook
Galvanizing Consultant - Hot Springs, South Dakota, USA