Sulphuric Acid Dilution Plant

Sulphuric acid is a heavy chemical and finds numerous applications in the industry. It is the product of ‘Contact Process’ and commercially available as 98.5% (ww) H2SO4 or stronger in the form of oleum.
However, many of the processes and applications utilizing sulphuric acid require weaker acid than this. As a result, dilution equipment is often necessary in order to meet the requirement for this weaker acid.
During dilution, considerable heat is generated depending on the extent of dilution desired. The Integral heat of solution of sulphuric acid is plotted in fig.1. The heat liberated sometimes is sufficient to produce boiling of the acid and so, provision is made for the re-circulation of a portion of cooled dilute acid, thus ensuring working at controlled temperature.
From the above it will be clear that intimate mixing and efficient heat transfer form the pre-requisites for sulphuric acid dilution unit to avoid excessive temperature and local heating and uniform product concentration.
Process Description
Metered quantity of sulphuric acid is introduced to a heat exchanger with re-circulation of water through a pump from the tank containing pre-determinant quantity of water. The turbulence created in the heat exchanger ensures both intimate mixing and efficient heat transfer. When desired strength of acid is reached, the contents of the tank are transferred to storage and fresh batch can be started again.