초록 ▼

The sorbent capacity of calcium oxide with respect to sulfur dioxide is increased by calcining limestone or dolomite in an atmosphere where the partial pressure of carbon dioxide is greater than 40 percent of the equilibrium partial pressure of carbon dioxide over calcium carbonate at the reaction t

The sorbent capacity of calcium oxide with respect to sulfur dioxide is increased by calcining limestone or dolomite in an atmosphere where the partial pressure of carbon dioxide is greater than 40 percent of the equilibrium partial pressure of carbon dioxide over calcium carbonate at the reaction temperature. Where dolomite is the starting material, it may be calcined in a two-step heating process in which the atmosphere during the first heating stage contains carbon dioxide and the temperature is maintained in the dissociation range of magnesium carbonate (MgCO3); the atmosphere of the second heating stage also contains carbon dioxide, but the temperature is maintained in the calcium carbonate (CaCO3) dissociation range. Calcium oxide so produced in such an atmosphere of carbon dioxide sufficient to delay calcination is found to have relatively large mouthed pores capable of sorbing increased amounts of sulfur.

대표청구항 ▼

A method for producing calcium oxide of increased sorbent capacity with respect to sulfur dioxide which comprises: heating stones of particle size 400-1000 microns containing calcium carbonate, at about 900°C. for a time sufficient to effect decomposition of the CaCO3 to CaO, in a calcination delayi

A method for producing calcium oxide of increased sorbent capacity with respect to sulfur dioxide which comprises: heating stones of particle size 400-1000 microns containing calcium carbonate, at about 900°C. for a time sufficient to effect decomposition of the CaCO3 to CaO, in a calcination delaying atmosphere containing carbon dioxide where the partial pressure of the carbon dioxide is greater than 40 percent and up to 85 percent the equilibrium partial pressure of carbon dioxide over calcium carbonate at the reaction temperature, to cause a back pressure of CO2 sufficient to convert initially formed fine pores of CaO to coalesce into larger pores. A method of producing calcium oxide of increased sorbent capacity with respect to sulfur dioxide from stones of 400-2000 microns particle size containing calcium carbonate and magnesium carbonate, which comprises: a. heating said stones at 700°up to 900°C. in an atmosphere in which the partial pressure of carbon dioxide is greater than the equilibrium partial pressure of CO2 over CaCO3 at the reaction temperature to calcine the magnesium fraction of the stones; and, b. additionally heating said stones in an atmosphere containing an amount sufficient of carbon dioxide to delay calcination and for a time sufficient to cause sufficient CO2 back pressure to produce large mouthed pores, at a temperature greater than that in step (a) in the range 900°-950°C. for a time sufficient to effect decomposition of the CaCO3 to CaO, the CO2 partial pressure being greater than 40% but not exceeding 85% of the equilibrium partial pressure of CO2 over CaCO3 at the reaction temperature.