The plant I'm working at has a small H2SO4-plant, consisting of:
- Fluid bed roasters to convert Cu-sulphide into CuO, to be fed to a Cu-L-EW circuit.
- SO2 offgas from the roasters are treated in hot cyclones followed by wet gas cleaning in quencher, spray-tower, high pressure venturi, cooling tower and wet ESP's
- H2SO4-plant with drying tower, blower, 3-pass converter (2+1), double absorption.
The shell & tube cooler bring the hot acid (98.7%) from c. 115 to 84°C
The scaling problem is on the acid/shell side of the cooler.
During 12 years of operation, the shell side has never been washed, and the cooler has lost ~40% of it's heat transfer coeff.
I'm wondering what the scaling could consist of, and the best way to clean it?
Thanks in advance for any proposal.
since you work with minerals in your process, ypu probably have calcium in the system. This way you probably have CaSO4 or one of its hydrates. You may collect a small sample of the solid and make a X-ray diffraction or other analytical method to identify it.
I am supporting to SILAS DERENZO sir. It may be due to CaSO4. if you can remove the shell part, the scaling can easily remove by continuous sonication in DI or mild acidic media.
Please note that, in principle; as a rule of thumb, the most corrosive fluid, and/or the most propense to originate scaling, should preferably pass by the tube side, rather than by the shell side, for shell and tube heat exchangers.
Maybe you want to check the following discussion, addressing the selection of metallic materials for contacting highly corrosive H2SO4 oleum by around 140 ºC: https://www.researchgate.net/post/Oleum_corrosion_what_steel_or_nickel_alloy
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