4 replies to this topic

[mannan]

dear friends, we are regenerating spent sulphuric acid( less concentration 80 to 85 percentage) after used alkylation process, now the problem is while coming from the product sulphuric acid ( 99 to 99.5%) is colourless and after storage tank( ms tank ) it is changing maroon colour , but this colour is not affecting until now any process . why this colour changing ..? we have 2 tanks for consuming alkylation process one and other one is product acid ...

[abhi_agrawa]

The color is due to corrosion of the tank by sulfuric acid. Check the thickness of the walls of the tank. MS is not ressistant towards corrosion by Sulfuric Acid. I think that for storing 99% pure acid, SS tanks can be used (but this needs a verification from a materials experts)

abhishek

[trilok_sontakke]

is your tank is nitrogen blanketed? it may be due to moisture absorption? check if your % goes down or not
after a long time if it does so then you can say that it absorbs moisture.

[Ming Hooi]

Quoting Specialty Steel Industry of north America (SSINA),

Environment:
Sulfuric Acid

Grade(s):
Type 304 can be used at room temperature for concentrations over 80%. Type 316 can be used in contact with sulfuric acid up to 10% at temperatures up to 120 F (50 C), if the solutions are aerated; the attack is greater in airfree solutions. Type 317 may be used at temperatures as high as 150 F (65 C) with up to 5% concentration. The presence of other materials may markedly change the corrosion rate. As little as 500 to 2000 ppm of cupric ions make it possible to use Type 304 in hot solutions of moderate concentration. Other additives may have the opposite effect.


Reference:
URL: http://www.ssina.com...ons/design.html