Design and Control of Reactive Distillation for n-Butyl Propionate System with Split Feed
Date Issued
2006
Date
2006
Author(s)
Jan, Cheng-Hsun
DOI
zh-TW
Abstract
A Reactive distillation column that combines reaction and distillation processes into one single unit is known to have significant advantages on reducing capital and operating costs of a process. Different esterification processes using RD columns have been studied and published in literature lately.
Subsequent to Lin’s previous work (2004), “design and control of reactive distillation system for n-butyl propionate”, it is the purpose of this research to study if splitting the feed inputs to the RD column can improve the economics and operation of the process. It is found that, after splitting, the TAC decreases for 10% and reboiler duty decreases for 20% in this particular case. By this splitting of the feed, the specific reaction rate is found to increase at the same time. The resulting optimal design shows that the heavier reactant feed is splitted into two portions. The bigger portion of feed goes along with the lighter reactant to the same tray, and the remaining portion is fed to some tray in above. It is found that, by applying this result to other esterification processes, significant reduction of TAC and reboiler duty may be procured. Three of esterification processes ( Metyl-acetate, butyl-acetate, amyl-acetate) were studied. It was found that the spilt of feed favors the RD processes where reaction equilibrium constant is larger. For example, for butyl-acetate process, TAC can decrease as much as to 30% and the reboiler duty to 50%.
The control strategies for optimal n-butyl propionate processes (single feed and split feed) are also studied. Two control strategies for either case that has single or split propionate acid feed are considered. For temperature control, the non-square relative gain (NRG) and singular value decomposition (SVD) together with sensitivity analysis are used to locate the right trays where temperatures are to be controlled. Relative gain array (RGA) is used to select pairing and characterize the interaction of the control loops, ATV is used to tune the controller parameters. Flow rate disturbance and feed purity disturbance are introduced to test the disturbance rejection abilities of these systems. Since offsets in product composition are found, a feed forward control strategy to keep the composition close to its set-point is also considered. It is found that the split of feed does not have essential effect on the control of such processes.
Subjects
分支進料
丙酸丁酯
反應蒸餾
乙酸丁酯
乙酸甲酯
乙酸戊酯
split feed
butyl propionate
reactive distillation
buty acetate
metyl acetate
amyl acetate
Type
thesis
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