Acetic Acid Decanter Phase Separation Control
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Solution Overview
Problem
The existing methods for controlling decanter phase separation in acetic acid production by methanol carbonylation are ineffective due to delayed measurement and feedback, leading to inefficiencies in recycling methyl iodide, a costly catalyst promoter.
Innovation Solution
Measuring the methyl acetate concentration in the reactor mixture, calculating the density of the decanter's heavy organic phase, and adjusting reactor or decanter conditions in real-time to ensure optimal phase separation, utilizing techniques like FTIR with ATR probes for online analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If density measurement in decanter heavy phase is used to control phase separation, then phase separation control is achieved, but response time is delayed due to three steps downstream location
Solution Approach 1:
The patent measures methyl acetate concentration in the reactor mixture upstream before the process flows to the decanter. This preliminary measurement allows prediction of heavy phase density before it actually occurs, enabling proactive adjustment of reactor conditions to prevent phase separation problems rather than reacting to them after they occur downstream.
Solution Approach 2:
The patent uses methyl acetate concentration as an intermediary parameter to predict heavy phase density. Instead of directly measuring density in the decanter (which is delayed), the system measures methyl acetate concentration in the reactor mixture, which serves as a leading indicator that correlates with future heavy phase density and phase separation behavior.
2Reliability
If reactor conditions are adjusted based on delayed decanter density measurement, then phase separation can be addressed, but the adjustment is too late to effectively remedy the problem
Solution Approach 1:
The system performs preliminary measurement of methyl acetate concentration in the reactor mixture, which directly reflects current reactor conditions that will soon manifest as heavy phase density issues. By acting on this preliminary information, the system adjusts reactor conditions proactively before phase separation problems develop in the decanter, eliminating the remediation delay.
3Loss of time
If methyl acetate concentration measurement is used to predict heavy phase density, then timely phase separation control is achieved, but additional measurement and calculation steps are required
Solution Approach 1:
The patent introduces methyl acetate concentration measurement as an intermediary that simplifies the overall control system. Instead of implementing complex direct density measurement and control in the decanter, the system uses methyl acetate concentration (which is already present in the reactor mixture) as a proxy indicator, requiring only standard spectroscopic measurement and simple correlation calculations.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides timely adjustments to maintain efficient phase separation, ensuring effective recycling of methyl iodide and improving the overall acetic acid production process by linking decanter phase separation directly to reactor conditions.
Implementation Method 1
utilizing techniques like FTIR with ATR probes for online analysis
Implementation Method 2
The overhead stream is condensed in a decanter to produce a light, aqueous phase comprising water, acetic acid, and methyl acetate, and a heavy, organic phase comprising methyl iodide and methyl acetate
Data Source
AI summary
Disclosed is a method for controlling the decanter phase separation of an acetic acid production by methanol carbonylation. The method comprises measuring the methyl acetate concentration of the reactor mixture, calculating the density of the decanter heavy, organic phase according to the measured methyl acetate concentration, and adjusting the conditions in the reactor or in the decanter to ensure phase separation of the decanter.