Heavy Residue Phase Separation in Propylene Oxide-Styrene Process
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Solution Overview
Problem
The co-production of propylene oxide and styrene monomer generates a heavy residue stream with high sodium content, which, when treated using existing phase separation processes, often forms a rag layer that hinders complete separation and reduces efficiency.
Innovation Solution
Adding a hydrocarbon and aqueous acid to the heavy residue stream, specifically a C5-C12 hydrocarbon like ethyl benzene or hexane, and an aqueous mineral acid like sulfuric acid, to facilitate phase separation into an aqueous sodium salt phase and an organic phase with reduced sodium content, thereby minimizing rag layer formation and enhancing sodium removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If aqueous acid is added to the heavy residue stream for phase separation, then sodium removal is improved, but a rag layer forms that hinders complete separation
Solution Approach 1:
A salt precursor compound is introduced as an intermediary substance that reacts with the aqueous acid to form a soluble salt. This intermediary approach prevents the direct formation of insoluble sodium salts that would create the rag layer, while still achieving effective sodium removal through the soluble salt formation that remains in the aqueous phase during separation.
Solution Approach 2:
The invention changes the chemical state of the sodium removal process by using a salt precursor compound that alters the solubility characteristics of the resulting salt. By selecting a precursor that forms a soluble salt rather than an insoluble one, the physical-chemical parameters of the separation process are optimized to prevent rag layer formation while maintaining sodium removal efficiency.
2Quantity of substance
If conventional phase separation is used to treat heavy residue, then some sodium is removed, but separation completeness is reduced due to rag layer
Solution Approach 1:
The salt precursor compound serves as a mediator that transforms the separation process outcome. By converting sodium into a soluble salt form through the precursor reaction, the intermediary enables complete phase separation without the rag layer barrier, thereby improving both the quantity of sodium removed and the productivity of the separation process.
3Loss of substance
If acid treatment is applied to heavy residue stream, then valuable products can be recovered, but rag layer formation reduces process efficiency
Solution Approach 1:
By changing the chemical parameters of the acid treatment process—specifically using a salt precursor compound instead of direct acid addition—the invention achieves product recovery while eliminating the rag layer formation that complicates the separation process. This parameter change simplifies the overall device complexity while maintaining product recovery value.
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 effectively reduces or eliminates the rag layer, improves sodium removal from the organic phase, and allows for the recovery of valuable products such as styrene monomer, increasing the value of the heavy residue stream by converting it into a usable fuel with low sodium content.
Implementation Method 1
treating the low value stream with aqueous acid, then phase separating the resulting mixture into an aqueous phase containing most of the sodium previously associated with the low value stream
Implementation Method 2
phase separating the resulting mixture into an aqueous phase containing most of the sodium previously associated with the low value stream and an organic stream phase having reduced sodium content
Data Source
AI summary
In the co-production of propylene oxide and styrene monomer, there is produced a sodium-containing heavy residue stream previously suitable only as a low grade fuel. In accordance with the invention, the heavy residue stream is mixed with a hydrocarbon and an aqueous acid, and the resulting mixture is separated into an aqueous sodium salt-containing slurry phase and an organic phase reduced in sodium.