Sulphuric acid prepn. by catalytic sulphur dioxide conversion - dissolving sulphur dioxide in sulphuric acid and purifying off-gases

摘要

Sulphuric acid is prepd. by (a) catalytically converting the SO2 in a gas to SO3 in a contact appts., (b) cooling the SO3-contg. gas in an intermediate stage of the contact appts., (c) cooling the SO0-contg. gas after the last contact stage, (d) absorbing the SO3 in sulphuric acid, (e) leading the off gasses through a part of molecular sieve units connected in series so that the units become loaded with SO2, (f) simultaneously desorbing already loaded molecular sieve units by use of dry air that has been heated by heat exchange with cases from the contact appts., (g) recycling the SO2-contg. air to the contact appts., (h) simultaneously cooling already desorbed molecular sieve units with dry air, and (i) recycling the resulting heated air to the contact appts. Economically provides a final gas with a very low SO2 content.