Pressure-compensated temperature control of Kaibel divided-wall column

doi:10.11949/j.issn.0438-1157.20180024

Abstract

Abstract:

Kaibel divided-wall column (KDWC) could separate four-component mixture into high-purity products in a single column. It is an intensified arrangement of three-component divided-wall column (DWC). Developing effective control structure is one of the main challenges of the application of KDWC. This work investigated a KDWC for the separation of a mixture of benzene, toluene, o-xylene and 1, 3, 5-trimethylbenzene. A temperature control (TC) structure and a new pressure-compensated temperature control (PTC) structure were developed in this work. Dynamic responses of the two control structures are compared. Disturbances in feed rate or feed composition were used to evaluate the effectiveness of the two control structures. The results showed that TC could regain stable control in facing of ±15% disturbances of feed rate or feed composition with the maximal residual error as about -0.007. One product purity failed to meet the specification. PTC shows a better control result in facing of ±20% disturbances. All the purity of the four products could meet the specification with the maximal residual error as about -0.003 and the setting time as 5-8 h. The new control method for the KDWC could give a dynamic set-point for the lower side-stream control loop, and thus presenting a better control performance.

Key words: Kaibel divided-wall column, dynamic simulation, temperature control, pressure compensated, aromatics

摘要：

Kaibel分壁精馏塔（Kaibel divided-wall column，KDWC）是分离三组分混合物DWC的进一步强化形式，可在一个塔内实现四组分混合物的高纯度分离。建立有效的控制结构是KDWC的研究关键，研究了KDWC分离苯、甲苯、邻二甲苯和均三甲苯四组分体系的动态过程，首次将压力补偿机制引入KDWC的控制，建立了压力补偿-温度控制结构（PTC），并考察了该结构与温度控制结构（TC）的控制效果。研究结果表明：TC可实现进料流量或组分发生±15%扰动后的平稳控制，少部分产品纯度不合格，最大余差为-0.007；PTC可实现进料流量或组分发生±20%扰动后的平稳控制，产品纯度均合格，最大余差约为-0.003，且调节时间缩短为5~8 h。压力补偿-温度控制结构通过对下侧线温度控制回路设定值的修正，有效地改善了控制效果。

关键词: Kaibel分壁精馏塔, 动态模拟, 温度控制, 压力补偿, 芳烃

CLC Number:

TQ202

QIU Jie, HUA Tao, HE Guichun, WU Xiang, SHEN Haitao, LING Hao. Pressure-compensated temperature control of Kaibel divided-wall column[J]. CIESC Journal, 2018, 69(11): 4798-4813.

邱洁, 华涛, 何桂春, 伍祥, 沈海涛, 凌昊. Kaibel分壁精馏塔的压力补偿-温度控制[J]. 化工学报, 2018, 69(11): 4798-4813.

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