Using hydrated lime and dolomite for sulfur dioxide removal from flue gases

Sulfation properties of six hydrated lime and three hydrated dolomite sorbents were investigated and compared a thermobalance was used to record the weight increase of the sorbents during the sulfation reaction which is carried out at 338 K. To distinguish between the weight gain by water adsorption and by sulfation, the samples were first exposed to a gaseous mixture consisting of 5% O₂, 10% CO₂, and the balance nitrogen with 55 % relative humidity. After this pre-conditioning, SO₂ was added to the gaseous mixture for sulfation with a concentration of 5000 ppm. The total sulfation capacities and Ca(OH)₂ conversion values of hydrated lime sorbents varied between 70.19-123.36 (mg SO₂/g sorbent) and 15.08-23.50 %, respectively. The total sulfation capacities and Ca(OH)₂+Mg(OH) ₂conversion values of hydrated dolomite sorbents varied between 146.55-226.77 (mg SO₂/g sorbent) and 22.54-30.94 %, respectively. It was found that the total sulfation capacity and conversion values of sorbents were changed depending on the physical properties of sorbents. Regression analysis was applied to relate the total sulfation capacity and conversion values to the physical properties of sorbents and linear empirical equations were developed.