Large Volume Inorganic Chemicals - Ammonia ... - ammk-rks.net

Chapter 4Finally, sulphuric acid is obtained from the absorption of SO 3 and water into H 2 SO 4 (with aconcentration of at least 98 %). For an example of a final absorber, see Figure 4.5. Theefficiency of the absorption step is related to:• the H 2 SO 4 concentration of the absorbing liquid (98.5 – 99.5 %)• the temperature range of the liquid (normally 70 – 120 ºC)• the technique of acid distribution• the raw gas humidity (mist passes the absorption equipment)• the mist filter• the temperature of incoming gas• the co-current or countercurrent character of the gas stream in the absorbing liquid.For the correlation between SO 2 levels, specific SO 2 loads in tail gases and conversion rates, seeSection 4.3.Tail gasCandle filtersH 2SO 4Gas inInterlock saddlesH 2OH 2SO 4Figure 4.5: Example for a final absorberThis figure is based on [68, Outukumpu, 2006]SO 3 emissions depend on:• the temperature of gas leaving the absorption• the construction and operation of the final absorber• the equipment for separating H 2 SO 4 aerosols• the acid mist formed upstream of the absorber through the presence of water vapour• the overall efficiency of the absorption step.Large Volume Inorganic Chemicals – Ammonia, Acids and Fertilisers 153