脱氢氰酸塔的动态分析

Analysis of Dynamic Behaviors of Dehydrocyanic Acid Column

作为乙腈连续回收工艺的重要组成部分,脱氢氰酸塔进出物流较多,出料组成受上游丙烯腈装置影响较大。实际生产中需要多次调节控制器参数,得到理想的控制结果。采用NRTL热力学模型,通过Aspen Dynamics软件搭建了脱氢氰酸塔的动态控制结构。考察了塔顶冷凝器温度和灵敏板温度对侧线采出组成的影响,分析了进料组成扰动对脱氢氰酸塔主要操作参数的影响。针对侧线采出控制方案的不足,加入流量比例控制结构,在进料流量阶跃干扰下,考察精馏塔的动态特性。研究结果表明:动态模型能够准确预测脱氢氰酸塔的动态响应,并能针对产品组成问题给出合理的优化建议。

The dehydrocyanic acid column is an important part of the continuous recovery process of acetonitrile which has two inlet streams and three outlet streams. The composition of the outlet streams of the dehydrocyanic acid column is greatly influenced by the disturbance of the upstream acrylonitrile plant. In practical operation, it is necessary to adjust the controller parameters many times in order to obtain optimal controlling results. In this paper, the NRTL thermodynamic model was used to build the dynamic controlling structure of the dehydrocyanic acid column in terms of Aspen Dynamics software. The influence of the temperature of the top condenser as well as the sensitive plate on the side streams composition was investigated, and the influence of feed composition disturbance on the main operating parameters of the dehydrocyanic acid column was analyzed. In view of the shortcomings of the control scheme of the side stream flow rates, a flow rate proportional controlling structure was adopted and the dynamic characteristics of the distillation column under the step disturbance of the feed flow was analyzed. The results showed that the dynamic model can accurately predict the dynamic response of the dehydrocyanic acid column and provide reasonable optimization suggestions for improving product quality.