Isopropyl Alcohol Separation via Absorption and Flash Drums

Solution Overview

Problem

Conventional isopropyl alcohol preparation processes face inefficiencies in separating isopropyl alcohol and unreacted propylene monomer, leading to reduced propylene conversion rates and selectivity, as well as accumulation of inert gases, which necessitate the use of high-purity propylene and result in propylene loss.

Innovation Solution

A method involving the use of an absorption column, a gas purification column, and an inert gas removal column to separate and recover unreacted propylene monomer while preventing isopropyl alcohol inclusion, promoting forward reactions and reducing inert gas accumulation by controlling stream supplies and using flash drums for pre-separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional separation processes are used to separate isopropyl alcohol and unreacted propylene monomer, then isopropyl alcohol can be recovered, but isopropyl alcohol is included in the recovered propylene monomer stream causing reverse reactions and reduced conversion rate

Engineering Contradiction:

Improvepropylene conversion rateVSAvoidpurity of recovered propylene monomer

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The separation process is divided into multiple sequential stages: absorption column for initial separation, flash drum for rapid equilibrium separation, and distillation column for final purification. Each stage targets specific components at different concentration levels, achieving progressive purification of propylene monomer while preventing isopropyl alcohol contamination that would cause reverse reactions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A solvent system is introduced as an intermediary medium in the absorption column to selectively absorb isopropyl alcohol from the reaction mixture. The solvent acts as a mediator that transfers isopropyl alcohol from the gas phase to liquid phase, enabling efficient separation without direct contact between propylene monomer and isopropyl alcohol, thus preventing contamination of the recovered propylene stream

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of substance

If conventional separation processes are used, then isopropyl alcohol can be recovered, but propylene monomer is lost in the stream supplied to purification section

Engineering Contradiction:

Improvepropylene monomer lossVSAvoidcomplexity of separation system

Core Design Contradiction:

Loss of substanceVSDevice complexity

Solution Approach 1:

The flash drum performs preliminary separation by rapidly establishing vapor-liquid equilibrium to remove the majority of isopropyl alcohol before the stream enters the distillation column. This preliminary action prevents propylene monomer from being carried over to the purification section, reducing propylene loss while minimizing the burden on subsequent separation equipment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Different sections of the separation system operate with locally optimized conditions: the absorption column uses specific solvent composition and temperature, the flash drum operates at controlled pressure and temperature for rapid separation, and the distillation column maintains specific reflux ratios. These localized optimizations ensure propylene monomer is recovered with high purity at each stage, minimizing overall loss

Inventive Principle:

Principle #3Local quality

3Reliability

If high-purity propylene monomer is used to prevent inert gas accumulation, then inert gas accumulation is prevented, but process cost increases and separation efficiency decreases

Engineering Contradiction:

Improveinert gas accumulation controlVSAvoidprocess cost and separation efficiency

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The inert gas removal system actively extracts and removes inert gases from the propylene monomer stream using a dedicated removal column. Instead of requiring high-purity propylene feed, the system takes out accumulated inert gases that would otherwise interfere with the reaction equilibrium, maintaining reliable operation with standard purity propylene feed and reducing overall process cost

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system discards accumulated inert gases that have no value in the reaction process and would otherwise cause accumulation problems. By removing and venting these inert components, the system maintains reliable reaction conditions without requiring expensive high-purity propylene feed, thereby improving ease of manufacture while maintaining reliability

Inventive Principle:

Principle #34Discarding and recovering

4Manufacturing precision

If absorption column is used to separate reaction product, then isopropyl alcohol and propylene monomer can be separated, but separation efficiency is insufficient and isopropyl alcohol is included in recovered propylene stream

Engineering Contradiction:

Improveseparation efficiencyVSAvoidamount of isopropyl alcohol contamination in propylene stream

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The separation process is divided into multiple sequential stages: absorption column for initial separation, flash drum for rapid equilibrium separation, and distillation column for final purification. Each stage targets specific components at different concentration levels, achieving progressive purification of propylene monomer while preventing isopropyl alcohol contamination that would cause reverse reactions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A solvent system is introduced as an intermediary medium in the absorption column to selectively absorb isopropyl alcohol from the reaction mixture. The solvent acts as a mediator that transfers isopropyl alcohol from the gas phase to liquid phase, enabling efficient separation without direct contact between propylene monomer and isopropyl alcohol, thus preventing contamination of the recovered propylene stream

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method enhances separation efficiency, prevents isopropyl alcohol inclusion in propylene monomer circulation, increases isopropyl alcohol production, reduces propylene loss, and eliminates inert gas accumulation, thereby improving overall process efficiency and reducing the need for high-purity propylene.

Implementation Method 1

supplying a reaction product stream formed by reacting a propylene monomer and water in a reactor to an absorption column

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

using flash drums for pre-separation

Methodology Applied

Scientific EffectFlash evaporation: Flash Evaporation

Implementation Method 3

supplying a lower discharge stream including isopropyl alcohol from the gas purification column to an isopropyl alcohol purification section

Methodology Applied

Scientific EffectDistillation: Distillation

Data Source

PatentUS20240174586A1Method for preparing isopropyl alcohol

Publication Date: 2024.05.30 LG CHEM LTD

AI summary

A method of preparing isopropyl alcohol that allows separation of a reaction product stream formed by reacting a propylene monomer and water in a reactor into an unreacted propylene monomer and isopropyl alcohol with high purity using an absorption column, a gas purification column, and an inert gas removal column.