To the large amount of water, small amount of sulfuric acid is continuously added thru a mixing sparger inserted and guided in a pipe, the mixture is then continuously dumped into a liquid body of the dilute acid pump tank. The hot liquid mixture is pumped to the cooler. Usually vertical submerged pumps are used for the circulation of the dilute acid. The cooler continuously removes the heat of dilution. The dilute acid is recirculated to the pump tank via the sparger.
For higher acid concentrations several dilution systems may be required.
But remember that the system should be provided with proper interlocks and needs engineering calculations followed with strict safety evaluations to ensure a safe operation.
I have succesfully used Hastelloy injection quill on a metering pump output. Take a look at the heat of dilution vs concentration curve, you will find heat is re-absorbed as concentration goes below ~29% (from memory)and the reaction is neutral in heat at ~5%
To control heat liberation you always add small quantities of s acid to large quantity of water. Thus if you wanted to prepare 1000 kg of 50% s acid, you start with 500 kg of water at room temperature and add concentrated acid slowly with good mixing keeping an eye (!) on the temperature rise.
Of course I am skipping (essential) details like Material of construction, concentration analysis etc, but hope you get the picture.
Where can I obtain a Heat of dilution vs concentration curve for H2SO4??? We plan to dilute 98% down to 10%. We need to size the cooling system to remove the heat prior to injecting the 10% concentration into our process.
We plan on injecting the 10% H2SO4 into existing pump suction housings that are cast stainless 316. It is essential that we not exceed 104 degF at 10% H2SO4, else the acid will be too aggressive. The water will be 80 degF, and the 98% H2SO4 may be as high as 100 degF.
Before dilute the H2SO4 we can add dry soda ash to decrease it concentration.the soda ash is cheap and can suppress the acid reactivity. Then you can dose the Acid Amount by 3% NaoH solution until neutralizing is completed.
Dear JNgent,
Among many alternative ways to find heat of dilution data, you may try and locate a book titled " Sulphur, Sulphur Di Oxide and Sulphuric Acid " written by UHF Sander, H Fischer, U Rothe and R Kola. This was published by British Sulphur Corporation in 1984 and had ISBN 0-902777-64-5 as reference.
I have the book and from this I can tell you that the heat liberated will be approx 750 kJ/kg of 100% H2SO4.
Good luck!
