Acetone Purification via Multi-Stage Caustic Washing
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Solution Overview
Problem
The existing phenol and acetone production process from cumene is inefficient due to high caustic usage, leading to increased wastewater, sulfuric acid consumption, and steam requirements, as well as equipment corrosion and fouling from salt carryover during distillation.
Innovation Solution
A process involving the use of two different concentrations of caustic solutions for washing the bottoms fraction from the acetone distillation column, followed by water washing, to maximize raw material utilization and reduce waste, where the aqueous phase from subsequent steps is reused to dilute caustic and neutralize cleavage products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fresh caustic solution is used for neutralization and washing, then neutralization effectiveness is improved, but caustic consumption and wastewater generation increase
Solution Approach 1:
The patent recovers and reuses caustic solution from the washing of acetone distillation bottoms fraction. The caustic-rich aqueous phase separated from the hydrocarbon wash is returned to the neutralization stage, replacing fresh caustic and reducing both consumption and wastewater generation while maintaining neutralization effectiveness.
Solution Approach 2:
The caustic solution serves multiple functions: it neutralizes acids in the cleavage product mixture, and after separation, the aqueous phase washes the acetone distillation bottoms fraction. This multi-functional use maximizes caustic utilization efficiency and reduces overall consumption.
2Manufacturing precision
If high concentration caustic is used for washing, then impurity removal efficiency is improved, but caustic consumption and equipment corrosion increase
Solution Approach 1:
The washing process is divided into multiple stages with different caustic concentrations. The first wash uses a moderate concentration caustic solution to remove the bulk of impurities, while subsequent washes use progressively lower concentrations. This segmented approach maintains effective impurity removal while reducing peak corrosion exposure to equipment.
3Manufacturing precision
If excessive water is used for dilution and washing, then impurity removal is improved, but water consumption and steam requirements increase
Solution Approach 1:
Water used in washing steps is not discarded but recovered and reused. The aqueous phases from washing operations are separated and returned to the process, reducing the need for fresh water and minimizing the energy required for water treatment and steam generation.
Solution Approach 2:
The process maintains continuous circulation and reuse of water and caustic solutions throughout the system. Rather than discrete batch operations with waste discharge, the system continuously recycles fluids, maintaining purification effectiveness while minimizing water and energy consumption.
4Reliability
If salt precipitation is used for acid removal, then acid neutralization is improved, but salt carryover and distillation fouling occur
Solution Approach 1:
Instead of allowing salts to precipitate and contaminate the distillation system, the process extracts acids into an aqueous caustic phase, separates this phase, and returns it to neutralization. This extraction approach removes acids without generating salt carryover that would foul distillation equipment.
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 reduces caustic and water consumption, decreases sulfuric acid and steam requirements, minimizes waste production, and enhances process efficiency by effectively removing impurities and recycling valuable resources, resulting in significant economic benefits and improved product quality.
Implementation Method 1
Neutralization may be accomplished by treating the acids with a basic material, such as an aqueous alkaline agent, typically NaOH (caustic). During the neutralization reaction, salts are formed.
Implementation Method 2
separating the aqueous phase containing the neutralized acids from the mixture
Implementation Method 3
extracting the acids from the organic phase into an aqueous phase
Implementation Method 4
the cleavage product mixture is conducted to a distillation section, wherein the main products of the cleavage reaction, i.e. phenol and acetone, are first separated
Data Source
AI summary
A process for washing hydrocarbons said process comprising: (I) distilling a crude acetone mixture preferably obtained from the cleavage of cumene hydroperoxide and containing hydrocarbons and water so as to form a bottoms fraction containing said hydrocarbons in an organic phase and an aqueous phase; (II) contacting at least a part of said bottoms fraction with an aqueous metal hydroxide solution so as to provide a concentration of 0.1 to 5 wt % MOH, where M is an alkali metal, in the aqueous phase; (III) separating the aqueous phase and the organic phase; (IV) contacting at least a part the organic phase from step (III) with an aqueous metal hydroxide solution so as to provide a concentration of 6 to 20 wt % MOH in the aqueous phase; (V) separating the organic phase and aqueous phase formed in step (IV); (VI) washing at least a part of the organic phase of step (V) with water.