Producing ALS form H2SO4 and Alhydrate 1

[pt1000]

Is there any (affordable) metall available which can widthstand a slurry of Aluminumhydrate, Sulphuric acid 98% and water at temp. of 120ºC and 3 - 4 bar?
Im thinking of a reactor of 20 - 25 m3. I know the alternatives like rubber- or glasslined but these have there own problems. I would prefer to skip the lining and do it in a full metall reactor.

 

[bchoate]

bchoate
I am assuming, from the sketchy post, that the reaction is to make Al[sub]2[/sub](SO[sub]4[/sub])[sub]3[/sub] or alum from "alumina hydrate" (aluminum hydroxide) and sulfuric acid. The corrosivity of the reaction mix arises not so much from the alumina hydrate or the aluminum sulfate but from the sulfuric acid at whatever concentration it will be in the reactor. Perhaps it can range from 10% to 90%. At the process temperature (120 C), sulfuric acid attacks most stainless steels that might be used for the vessel. Super Austenitic stainless steels are the only products that may be of use. C-276 has a corrosion rate of 20-25 mpy over a 10-90% sulfuric acid acid at the conditions stated. Inconel alloy 686 has a corrosion rate of <10 mpy for the best rate at these conditions. Corrosion rates should be <<1 mpy. If a few ppm chloride from the water or the alumina hydrate are in the system, corrosion rates increase to > 300 mpy in either alloy. Both these alloys are weldable but the cost of either is about 3X 316 SS or more. Fabrication costs will be higher also. Special Metals Corp. can speak more to the cost and fabrication needs.

The cost solution is a glass lined vessel. I'm not sure about rubber lined vessels. I do have several years experience with glass lined vessels in services far more corrosive than the one you described. One service even was corrosive to tantalum. The vessel is large but it is not outside the range of commercial vessels. DeDietrich (

http://www.dedietrich.com)

is a leader in glass lined vessels. They have done a vessel 12.5 m high X 4.1 m D (about 50 m[sup]3[/sup].
Bill Choate