Abstract:

Industrial energy conservation is the primary measure for carbon emission reduction. The heat of reaction released during the production of furnace-process phosphoric acid is as high as 26289 MJ per ton of yellow phosphorus, which accounts for 25% of the total energy consumption of yellow phosphorus. In this paper, based on the available energy analysis, the different heat recovery methods of the thermal phosphoric acid production process are studied by employing Aspen Plus software. The results show that, based on the heat recovery process in the production of existing furnace-process phosphoric acid, the steam pressure of phosphoric acid tower is increased from 1.0 MPa to 2.5 MPa, the heat recovery efficiency raised from 46.29% to 62.42%, and the available energy of the system is boosted from 26.22% to 34.95%. Further, when the pressurized water before entering phosphoric acid tower is heated by circulating acid from the hydration tower, the heat recovery efficiency and the available energy of the system is enhanced to 87.08% and 46.59%, respectively. As a result, the heat energy generated from the production of furnace-process phosphoric acid can be completely recycled. The sensitivity analysis of the excess air coefficient shows that under the premise of ensuring the full oxidation reaction of yellow phosphorus, appropriately reducing the excess air coefficient is beneficial to the improvement of heat recovery efficiency and exergy efficiency.

Key words: furnace-process phosphoric acid, Aspen Plus, energy conservation, available energy, potential of saving energy

摘要：

工业节能是碳减排的首要措施，热法磷酸生产过程每燃烧1 t黄磷释放出的反应热高达26289 MJ，占黄磷总能耗的25%。本文应用Aspen Plus软件，基于有效能的分析方法，对热法磷酸生产过程不同的热能回收方式进行研究。结果表明：以现有热法磷酸热能回收工艺为基础，燃磷塔副产蒸汽压力由1.0 MPa提升至2.5 MPa，热量回收效率由46.29%提升至62.42%，系统的效率由26.22%提升至34.95%；进一步通过用水化塔循环酸加热进入燃磷塔的加压水，系统的热回收效率提升至87.08%，效率提升至46.59%，实现了热法磷酸热能的全回收利用。空气过剩系数的灵敏度分析表明，在保证黄磷充分氧化反应的前提下，适当降低空气过剩系数有利于热回收效率和效率的提升。

关键词: 热法磷酸, Aspen Plus, 节能, 节能潜力