| 摘要 |
<p>Sodium carbonate is prepd. using NaCl and NaOH as raw materials by (a) preheating the mother liquor from the Na2CO3 formed in a prodn. column, before it directly contacts the gases flowing through the CO2 column, by indirect contact with these gases, in order to expell CO2, (b) expelling an extra amount of CO2 from the mother liquor from stage (a) by extra heating, and (c) passing the released CO2 to the prodn. column. The amount of CO2 in the gas supplied to the ammonia absorption column is considerably lowered by the extra heating stage (b). Consequently, the amount of mother liquor for recirculation in the process is considerably lowered, and the limit of the caustic soln. brine ratio at which recirculation of mother liquor is necessary is increased.</p> |
