If this concentration happens to be on lower side then sulphur trioxide is not properly absorbed and forms a troublesome mist. The sulphur trioxide is hydrated by absorption in a packed tower which is filled with Sulphuric Acid of a specific range. Third step: Production of Sulphuric Acid (H2SO4) After three stages the purity becomes 97-98% and after four stages the purity becomes 99.5-99.8%. ![]() Double Absorption helps in ensuring that more of sulphur dioxide is converted to sulphur trioxide and also overall doing this is beneficial for the process also in terms of purity. It is important that the sulphur dioxide be prevented from leaking in the atmosphere as they not only pollute the air but also are a major constitute in the cause of Acid Rain. When the gas is passed to one catalyst bed it’s temperature rises from the range of 410-430☌ to about 600☌ hence after each stage the gas has to be cooled to the optimum temperature again before passing it to the next stage. Commonly the catalytic reactor is designed as a four stage bed reactor. If the temperature rises above 430☌ then the equilibrium is displaced away from Sulphur Trioxide, hence it is very important that operating temperature should be maintained in this range. The pressure is maintained at 1.2-1.5 atm and temperature at 410-430☌. The oxidation of sulphur dioxide to sulphur trioxide is a reversible process. Before sending the sulphur dioxide to the reactor the gas is pretreated to remove any impurities if present by Wet Scrubbing and if there are any fine particles present then the gas is passed through electrostatic precipitator. The catalyst used for the catalytic oxidation of sulphur dioxide to sulphur trioxide is Vanadium Pentoxide. Sulphuric Acid Manufacturing Process Second step: Production of Sulpur Trioxide Gas (SO3) The steam will expand and the mixture will be splashed everywhere in an exploding fashion.Īlmost all the sulphuric acid around the world is manufactured by Contact Process. This released heat will evaporate a fraction of water near the interface. ![]() At the interface the sulphuric acid will absorb water and release heat. Hence, we will have water in the top layer and sulphuric acid in the bottom layer. In case we add water to sulphuric acid, since the water is lighter than sulphuric acid, it will stay at the top. ![]() Reason being that since sulphuric acid is heavier than water it will move to the bottom due to gravity and the mixing will be much uniform. During the mixing process, sulphuric acid should be added to water. The sulphuric acid can be diluted by water to get acids in various strengths for different purposes. Sulphuric Acid is a colourless liquid which has an appearance similar to that of water.
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