Distillation Column Hydrogen Iodide Removal
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Solution Overview
Problem
Current distillation processes for acetic acid production face challenges in efficiently removing hydrogen iodide due to its azeotrope formation with water, leading to condensation and corrosion issues, and require additional steps like methanol introduction, which increase costs and energy consumption.
Innovation Solution
Distilling a mixture containing hydrogen iodide and water under conditions with a water content of no more than 5% by weight in the distillation column, allowing for effective removal of hydrogen iodide and reducing corrosion, while introducing suitable components like methyl acetate or alkali metal hydroxide to enhance removal efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hydrogen iodide is removed by reaction with methanol or methyl acetate, then the concentration of hydrogen iodide is reduced, but the removal efficiency is insufficient and additional reagents are required
Solution Approach 1:
The invention changes the operating parameters of the distillation column, specifically maintaining the water content at not more than 5% by weight and operating at a pressure of not less than 2.0 MPa. These parameter changes prevent the formation of hydrogen iodide-aqueous solution azeotrope, enabling efficient removal of hydrogen iodide through distillation alone without requiring chemical reaction with additional reagents like methanol or methyl acetate.
Solution Approach 2:
The invention extracts hydrogen iodide from the mixture by distillation under specific conditions (water content ≤5% and pressure ≥2.0 MPa). By removing the harmful azeotrope-forming condition (excessive water), hydrogen iodide can be separated and removed efficiently through the distillation process, taking it out of the system without needing chemical conversion.
2Productivity
If pressure is increased to convert hydrogen iodide into methyl iodide, then conversion efficiency improves, but corrosion of the distillation column is accelerated
Solution Approach 1:
The invention converts the harmful effect of high pressure (which accelerates corrosion) into a beneficial effect by precisely controlling the pressure to be not less than 2.0 MPa. At this specific pressure threshold, the system prevents azeotrope formation and enables efficient hydrogen iodide removal, while avoiding the excessive pressure that would cause severe corrosion. The harm of high pressure is thus converted into benefit through precise parameter control.
Solution Approach 2:
The invention changes the pressure parameter to a specific range (not less than 2.0 MPa) that simultaneously achieves efficient hydrogen iodide removal and minimizes corrosion. This parameter optimization allows the system to operate at conditions where hydrogen iodide can be effectively separated without requiring chemical conversion that would expose the column to corrosive environments.
3Reliability
If water content is high in the distillation column, then hydrogen iodide forms azeotrope and condensation occurs, but reducing water content requires additional processing steps
Solution Approach 1:
The invention performs preliminary action by pre-controlling the water content of the feed to not more than 5% by weight before entering the distillation column. This preliminary control prevents the formation of hydrogen iodide-aqueous solution azeotrope from the outset, eliminating the need for additional processing steps like chemical treatment or multiple distillation stages that would otherwise be required to break the azeotrope.
Solution Approach 2:
The invention changes the water content parameter to a specific threshold (not more than 5% by weight) that fundamentally alters the distillation behavior. Below this threshold, the hydrogen iodide-aqueous solution azeotrope cannot form, allowing simple distillation to effectively separate hydrogen iodide without requiring complex additional processing steps.
4Quantity of substance
If methanol is introduced to convert hydrogen iodide, then removal capability improves, but processing cost and energy consumption increase
Solution Approach 1:
The invention enables the distillation column to serve itself by removing hydrogen iodide through pure distillation under controlled conditions (water content ≤5% and pressure ≥2.0 MPa). The system does not require external chemical reagents like methanol to facilitate removal. The controlled parameters themselves enable the separation process, making the system self-sufficient and reducing energy consumption associated with additional chemical treatment steps.
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 effectively prevents hydrogen iodide condensation, reduces corrosion, stabilizes the quality of acetic acid, and achieves high-purity acetic acid production with reduced energy consumption and processing costs.
Implementation Method 1
distilling a mixture containing hydrogen iodide and water under conditions with a water content of no more than 5% by weight in the distillation column
Implementation Method 2
hydrogen iodide forms an azeotrope with water
Data Source
AI summary
A mixture containing hydrogen iodide and water and having a water content of not more than 5% by weight (particularly not more than 3% by weight) in a distillation system is distilled to prevent condensation of hydrogen iodide in the distillation system. The mixture may comprise hydrogen iodide, water, methanol, methyl iodide, acetic acid, and methyl acetate. Even when the mixture contains hydrogen iodide at a concentration of 1 to 3000 ppm on the basis of weight, an acetic acid product having a concentration of hydrogen iodide of not more than 50 ppm can be obtained by withdrawing a fraction containing hydrogen iodide from the top of the column, and withdrawing acetic acid as a side-cut stream or a stream from the bottom of the column. Such a process (distillation process) effectively inhibits condensation of hydrogen iodide in the distillation system and corrosion in the distillation system.