低温低压下氨碳化过程的模拟与控制

氨碳化产物控制是固废硫酸钙低温转化实现硫资源综合利用的关键。采用Aspen plus软件对氨碳化过程进行模拟与分析发现,温度在273.15～338.15 K范围内,温度升高,碳酸根向碳酸氢根转化;0.01～0.13 MPa压力范围内,压力增大,碳酸氢根向碳酸根转化,压力高于0.13 MPa,压力对氨碳化过程无影响;氨摩尔分数小于0.04时,碳酸氢根含量接近1;氨摩尔分数为0.1～0.15,溶液中阴离子主要为碳酸根;氨摩尔分数大于0.15,氨浓度增大对溶液体系碳酸根和碳酸氢根组分无影响;氨碳比为2.2～2.8,溶液中阴离子主要为碳酸根;氨碳比大于2.8,溶液中90%(mol)以上为碳酸氢铵。在此基础上,分别给出了温度-氨浓度、温度-氨碳比条件控制下生产高含量碳酸氢铵和碳酸铵的工艺条件。

Simulation and control on ammonia carbonation under low temperature and pressure

Ammonia carbonation product control is the key of calcium sulfate conversion at low temperature for utilization of sulfur resources.Aspen plus software was used to simulate ammonia carbonation process.The results indicate that carbonate converts gradually into bicarbonate with increasing temperature from 273.15 K to 338.15 K. The conversion from bicarbonate to carbonate occurs at 0.01-0.13 MPa,but ammonia carbonation has no affect when pressure is above 0.13 MPa. If ammonia mole fraction is less than 0.04,bicarbonate mole fraction in products will be close to 1. When ammonia mole fraction is 0.1-0.15 or ratio of reaction ammonia to carbon oxide 2.2-2.8,carbonate is the major product of carbonation.If ammonia mole fraction is above 0.15,effect of ammonia concentration on ammonia carbonization is little.When ratio of reaction ammonia to carbon oxide is higher than 2.8,There will be more than 90% of ammonium bicarbonate in solution.On the basis above,control conditions of temperature-ammonia concentration,temperature-ratio of reactive ammonia to carbon dioxide were pointed out for preparing high contents of ammonium bicarbonate or ammonium carbonate.