Liquid level optimal-setting for alumina multi-effect evaporation process based on exergy analysis

doi:10.11949/j.issn.0438-1157.20161689

Abstract

Abstract:

In the multi-effect evaporation process in Bayer process for alumina production, liquid level of each effect is an important parameter that influences other parameters and important for optimization of evaporator operation. But in the actual production, the liquid level is usually set empirically in a large rang, so that the process cannot run in optimal situation. This paper proposed a liquid level optimization method based on exergy analysis. By deeply analyzing the liquid level's effect on other evaporation parameters and using the actual running data, the relationships between liquid level and other parameters are obtained. Combining the material balance of the evaporator and the exergy analysis method, optimization model for energy consumption based on the maximum exergy efficiency is established. The optimization model is then solved by STA using two different constraint handling technology under a certain condition to get better solutions. Finally the optimal level under three different pickling cycle is calculated and evaporation liquid level curve for each effect is obtained.

Key words: alumina, evaporation, optimization, exergy, equation of state

摘要：

在拜耳法生产氧化铝多效蒸发过程中，各蒸发器液位是影响流程各个参数的重要变量，对整个蒸发过程的优化操作十分重要。但实际生产中各效蒸发器液位的设定值通常是一个较大的范围，难以优化运用。针对此问题提出了一种基于(火用)分析的多效蒸发流程液位优化设定方法。在对液位作用机理分析的基础上，基于整个流程的实际生产数据，拟合得到了每效包含液位随其他参数变化的关系模型。结合蒸发流程物料平衡关系以及(火用)分析方法，建立了综合(火用)效率评价指标的能耗优化模型。最后，采用两种不同约束处理技术和状态转移算法，计算了不同酸洗周期下的各效蒸发器最优液位，得到了优化目标随各个效液位高度变化的关系曲线。

关键词: 氧化铝, 蒸发, 优化, (火用), 状态方程

CLC Number:

TF821

ZUO Jian, XIE Yongfang, WANG Xiaoli, WANG Feng, YANG Chunhua. Liquid level optimal-setting for alumina multi-effect evaporation process based on exergy analysis[J]. CIESC Journal, 2017, 68(3): 1005-1013.

左健, 谢永芳, 王晓丽, 王峰, 阳春华. 基于(火用)分析的氧化铝多效蒸发过程液位优化设定方法[J]. 化工学报, 2017, 68(3): 1005-1013.

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