Modeling solid–liquid equilibrium of NH4Cl‐MgCl2‐H2O system and its application to recovery of NH4Cl in MgO production
Modeling solid–liquid equilibrium of NH4Cl‐MgCl2‐H2O system and its application to recovery of NH4Cl in MgO production
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DOI：
10.1002/aic.12357
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发表时间：
2011-06
期刊：
影响因子：
3.7
通讯作者：
Daoguang Wang;Zhibao Li
中科院分区：
文献类型：
--
作者：
Daoguang Wang;Zhibao Li
在白杨Plus（TM）软件平台上，采用Pitzer模型对NH 4Cl-MgCl 2-H2O体系进行固液平衡模拟，研究了从氧化镁生产过程中产生的富NH 4Cl水溶液中回收NH 4Cl的新方法。在278.15 ~ 348.15K范围内测定了该三元系的SLE值。通过计算，得到了NH_4Cl和MgCl_2中心点6 H（2）O的新标准态化学势。由此产生的平衡常数被用来确定新的相互作用参数NH 4Cl-H2O和MgCl 2-H2O系统。这些新的参数，以及通过关联实验值确定的混合参数，被用来关联NH 4 MgCl 3中心点6 H（2）O的平衡常数，这在NH 4Cl回收中起着关键作用。结果可将NH 4Cl-MgCl 2-H2O体系的SLE计算从278.15 K扩展到388.15 K，满足回收过程的过程辨识和模拟要求。通过模拟生成的相平衡图，确定了回收氯化铵的工艺方案。最后证明了采用三次分步结晶回收氯化铵的方法是可行的。(C)2010美国化学工程师学会AIChE J，57：1595-1606，2011
A new method to recover NH4Cl from NH4Cl-rich aqueous solutions generated in the magnesia (MgO) production is developed on the basis of modeling the solid-liquid equilibrium (SLE) for the NH4Cl-MgCl2-H2O system with the Pitzer model embedded in Aspen Plus (TM) platform. The SLE values for the ternary system were determined from 278.15 to 348.15 K. The new standard-state chemical potentials of NH4Cl and MgCl2 center dot 6H(2)O were judicially obtained. The resulting equilibrium constants were used to determine new interaction parameters for the NH4Cl-H2O and MgCl2-H2O systems. These new parameters, together with the mixing parameters determined from correlating the experimental values, were used to correlate the equilibrium constant for NH4MgCl3 center dot 6H(2)O, which plays a key role in NH4Cl recovery. The results could extend SLE calculation for the NH4Cl-MgCl2-H2O system from 278.15 to 388.15 K, satisfying the process identification and simulation requirement involved in the recovery process. The phase-equilibrium diagram generated by modeling was illustrated to identify the process alternatives for recovering NH4Cl. The resulting course to recover NH4Cl by three fractional crystallization operations was finally proved feasible. (C) 2010 American Institute of Chemical Engineers AIChE J, 57: 1595-1606, 2011