Partial Condensation Oxygenate Mixture Separation
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Solution Overview
Problem
Existing processes for condensing oxygenate mixtures from fragmented carbohydrates face challenges in separating formaldehyde from glycolaldehyde due to their rapid reaction, leading to difficulties in achieving acceptable formaldehyde levels without additional purification steps, especially in pyrolysis of aqueous solutions.
Innovation Solution
A partial condensation process is employed, where a vapour phase oxygenate mixture from carbohydrate fragmentation is partially condensed to achieve a condensate with a mass fraction of water between 0.02 and 0.3, effectively increasing the glycolaldehyde to formaldehyde mass ratio, allowing for the separation of glycolaldehyde while keeping formaldehyde in the vapor phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If complete condensation is performed on the oxygenate mixture, then all products are condensed and no product loss occurs, but formaldehyde reacts with water to form methylene glycol which is difficult to separate from glycolaldehyde
Solution Approach 1:
The patent applies partial condensation instead of complete condensation. The condensation is stopped at an intermediate stage where the condensate contains a controlled amount of water (0.05-0.50 mass fraction), preventing the complete conversion of formaldehyde to methylene glycol while still achieving sufficient product recovery. This partial action avoids the separation difficulties that would arise from complete condensation.
Solution Approach 2:
The patent changes the water content parameter in the condensate from the typical high water content to a controlled range of 0.05-0.50 mass fraction. This parameter change affects the equilibrium between formaldehyde and methylene glycol, reducing methylene glycol formation while maintaining acceptable product recovery. The specific water content range is optimized to balance product loss prevention with separation ease.
2Object-affected harmful factors
If reactive distillation is used to remove formaldehyde, then formaldehyde levels are reduced, but additional process steps are required
Solution Approach 1:
The patent merges the condensation step with the formaldehyde removal function. By controlling the condensation conditions to achieve specific water content (0.05-0.50 mass fraction), the process simultaneously condenses the oxygenate products while leaving formaldehyde in the vapor phase, eliminating the need for separate purification steps.
Solution Approach 2:
The patent extracts formaldehyde from the condensate by controlling the condensation process to keep formaldehyde in the vapor phase. The controlled water content in the condensate prevents formaldehyde from being carried over into the liquid phase, effectively removing it without additional processing steps.
3Productivity
If the condensate contains high water content, then complete condensation is achieved, but separation of formaldehyde becomes difficult due to methylene glycol formation
Solution Approach 1:
The patent optimizes the water content parameter to a specific range (0.05-0.50 mass fraction) that balances condensation efficiency with separation ease. This parameter change ensures sufficient product condensation while limiting water-induced formaldehyde conversion to methylene glycol, maintaining ease of separation.
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 process efficiently increases the glycolaldehyde to formaldehyde mass ratio up to 65, achieving higher purity and yield of glycolaldehyde without the need for separate purification steps, while maintaining low formaldehyde levels in the condensate, thus overcoming the separation challenges faced in traditional condensation methods.
Implementation Method 1
performing on the vapour phase oxygenate mixture a partial condensation to provide a partial condensation condensate and a partial condensation vapour phase
Implementation Method 2
performing on the vapour phase oxygenate mixture a partial condensation
Implementation Method 3
formaldehyde has a boiling point of −19° C., it rapidly reacts with water to form methylene glycol, which has a boiling point of 194° C.
Data Source
AI summary
There is provided a process for the partial condensation of an oxygenate mixture, the process comprising the steps of (a) providing a vapour phase oxygenate mixture obtained from fragmentation of an aqueous solution of carbohydrates; and (b) performing on the vapour phase oxygenate mixture a partial condensation to provide (i) a partial condensation condensate wherein the mass fraction of water in the partial condensation condensate is from 0.02 to 0.3 and wherein the mass ratio of glycolaldehyde to formaldehyde in the partial condensation condensate is increased relative to the mass ratio of glycolaldehyde to formaldehyde in the vapour phase oxygenate mixture; and (ii) a partial condensation vapour phase.