Recently, thermodynamic modeling has demonstrated that reduction of nonstoichiometric oxides in a counterflow gas current with a single inlet and exit must result in an equilibrium temperature gradient that deviates from the typically assumed isothermal operation at every single point but one, under assumed mass balance constraints. This necessity for a temperature gradient results in real processes that are near isothermal to deviate from the ideal reversible process, except for the single point where the Gibbs free energy change is zero. In this paper, new configurations with additional inlets and exits that can better approximate reversible and isothermal countercurrent flow reactors are considered and thermodynamically modeled. We show that it is possible to decrease irreversibilities while operating under the same maximum temperature, gas flowrates and initial nonstoichiometry simply by employing two or more exits and/or inlets. Under the most optimal conditions where the normalized irreversibilities are lowest, utilizing either an extra exit or extra inlet and exit show improved results in terms of minimizing the Gibbs free energy and lowering the needed separation work for the gases. Generally, as more irreversibilities are generated within the reactor, the more significant the usage of extra inlets/exits becomes.

中文翻译：

---

影响非化学计量逆流热还原反应器可逆性的构型因素分析

最近，热力学模型表明，在具有单个入口和出口的逆流气流中非化学计量氧化物的还原必定会导致平衡温度梯度，该平衡温度梯度在假设的质量平衡约束下，在除了一个点之外的每个点上通常假设的等温操作。这种温度梯度的必要性导致实际过程接近等温，偏离理想的可逆过程，除了吉布斯自由能变化为零的单点之外。在本文中，考虑了具有额外入口和出口的新配置，可以更好地模拟可逆和等温逆流反应器，并进行热力学建模。我们表明，在相同的最高温度、气体流速和初始非化学计量下运行时，只需采用两个或多个出口和/或入口，就可以降低不可逆性。在归一化不可逆性最低的最佳条件下，利用额外的出口或额外的入口和出口在最小化吉布斯自由能和降低气体所需的分离功方面显示出改进的结果。一般来说，随着反应器内产生的不可逆性越多，额外入口/出口的使用就变得越重要。