What type of storage tank should be used for 88% sulfuric acid containing hydrogen chloride?
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88% sulfuric acid used to remove water from chloromethane contains hydrogen chloride. The company currently uses carbon steel storage tanks, which require repair almost annually after 3 years – repairs are needed at the pipe joints and vent openings, and it’s a real hassle. We’re considering using an outer FRP lining with a PP inner layer; I wonder if anyone facing a similar situation can share their experience – how do you handle this? What should be done to deal with the large amount of hydrogen chloride released from 88% sulfuric acid pipes? They are currently connected directly to the exhaust tower; I’m thinking of using an alternative method such as on-site negative pressure absorption, as connecting them to the exhaust tower may lead to pressure buildup. :'(
This post was last edited by Du Xiaoping on 2016-10-29 at 14:50. Use fiberglass tanks; they are cheap and resistant to hydrogen chloride. Add two water seal tanks (forward and reverse water seals) at the vent location.
A flue tower can also be used; by installing a fan, there will be no risk of pressure buildup. Fiberglass can be utilized as it is inexpensive, but it’s important to choose the right type of resin for the anti-corrosion layer – consult the manufacturers who specialize in this area
I use a PP flash tank to separate hydrogen chloride; since I use waste hydrogen chloride as a raw material for producing chloromethane, the recovered hydrogen chloride can be reused. Furthermore, in the dehydration and drying of sulfuric acid using chloromethane, the hydrogen chloride content is extremely low; I’m not sure why it’s so high in your case
Glass fiber reinforced plastic generally is not resistant to sulfuric acid; it is better to use an FRP lining with PP. For HCl, an absorption tower is sufficient. If synthetic chloromethane is being produced, water washing and alkali washing are required beforehand. If the level of HCl remains high, it indicates that there is a problem in the preceding process.