What device is good for diluting concentrated sulfuric acid?
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Our plant uses pumps to transfer concentrated sulfuric acid into enamel-lined reaction vessels, mixes it with anchor stirrers, then adds water to dilute it; the dilution process releases heat. During maintenance, it was found that the enamel lining of the enamel-lined reactor was severely damaged; the cause was identified as uneven heating. Are there any better devices or methods for diluting concentrated sulfuric acid?
Enameled reaction kettles cannot retain heat or cool down quickly; it’s not clear whether they have a cooling system. The key lies in the method of operation – the concentrated sulfuric acid should be added slowly. Additionally, it’s important to check whether there are any issues with the quality of the enameled reaction kettle.
This problem is also common in the sulfuric acid production industry. Although it is a minor issue too small to be worth mentioning, it persists stubbornly, forcing one to constantly take measures such as maintenance and replacement in order to address local corrosion or equipment damage caused by uneven heating and to maintain normal operation. There are similar patented devices available online; I’m not sure if they work well. I built one myself with a capacity of 180 cubic liters per hour; its total length is 0.8 meters, and the inlet pipe has a diameter of only 80 mm – it can be lifted with just one hand. When combined with an automatic control system, a desired concentration value can be set, allowing for fully automatic regulation. The acid concentration at the outlet can be controlled very accurately, remaining almost constant. Under such precise control conditions, all problems related to local overheating and local corrosion simply do not exist.
The venturi tube made of PTFE is extremely simple
Without a cooling system, the quality of the enamel-lined reactor is fine
Now we are using this approach instead; it’s made of fluoroplastic material, and it’s a bit similar to a jet pump
When water and sulfuric acid enter, they flow downward along the wall of the tank. It is likely due to overheating during dilution and excessive temperature differences. Either use a spraying device such as a venturi as they suggest, or install a drip tube in the reactor to reduce the entry of water and sulfuric acid through the reactor walls
Uneven stirring leads to uneven heating, resulting in damage to the reactor vessel!
It has a cooling system, and there are no quality issues with the reactor
When adding sulfuric acid, an insertion tube is required; this tube is used to introduce the concentrated sulfuric acid as far away from the enamel as possible. Stirring is also employed to ensure even heat distribution, thereby preventing localized heating in the enamel-coated products.