Divided-Wall Column Styrene Purification

Solution Overview

Problem

Existing methods for purifying styrene from crude hydrocarbon streams, particularly those derived from pyrolysis or catalytic depolymerization of waste polystyrene, are energy intensive and fail to efficiently remove close boiling impurities, leading to high capital expenditures and impurities in the final product.

Innovation Solution

A method involving a divided-wall column for distillation followed by at least one crystallization step to produce a purified styrene composition, effectively removing impurities such as color-inducing species, sulfur, oxygenates, and close boiling hydrocarbons, while reducing energy consumption and capital expenditures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional two or three column distillation methods are used to purify styrene, then styrene purification can be achieved, but energy consumption increases and capital expenditure increases

Engineering Contradiction:

Improvestyrene purificationVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The distillation process is segmented into multiple sections within a single column by introducing side draws at different heights. The column is divided into an upper section for separating lighter impurities and a lower section for separating heavier impurities, allowing simultaneous purification functions in one unit rather than requiring multiple separate columns

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple distillation functions that would traditionally require separate columns are merged into a single integrated column with side draws. The column combines the functions of removing light impurities, removing heavy impurities, and producing purified styrene in one unified structure, reducing both capital expenditure and energy consumption

Inventive Principle:

Principle #5Merging (Combining)

2Manufacturing precision

If conventional two or three column distillation methods are used to purify styrene, then styrene purification can be achieved, but capital expenditure increases

Engineering Contradiction:

Improvestyrene purificationVSAvoidcapital expenditure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The distillation process is segmented into multiple sections within a single column by introducing side draws at different heights. The column is divided into an upper section for separating lighter impurities and a lower section for separating heavier impurities, allowing simultaneous purification functions in one unit rather than requiring multiple separate columns

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multiple distillation functions that would traditionally require separate columns are merged into a single integrated column with side draws. The column combines the functions of removing light impurities, removing heavy impurities, and producing purified styrene in one unified structure, reducing both capital expenditure and energy consumption

Inventive Principle:

Principle #5Merging (Combining)

3Manufacturing precision

If normal distillation is used to remove close boiling molecules from styrene, then some separation can be achieved, but energy intensity increases

Engineering Contradiction:

Improveremoval of close boiling impuritiesVSAvoidenergy intensity

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The separation process transitions from relying solely on temperature differences (one dimension) to utilizing both temperature differences and pressure differences (two dimensions). By introducing side draws at different heights and operating at varying pressures in different sections, the process achieves enhanced separation of close boiling impurities without proportionally increasing energy consumption

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 achieves a highly purified styrene composition with a styrene content of at least 99.8% by weight, efficiently removing impurities and reducing energy and capital costs compared to conventional two or three column distillation methods.

Implementation Method 1

subjecting the crude hydrocarbon composition provided in step a) to a distillation in a divided-wall column so as to produce an overhead hydrocarbon stream, a bottom hydrocarbon stream and a side hydrocarbon stream

Methodology Applied

Scientific EffectDistillation: Distillation

Implementation Method 2

subjecting the side hydrocarbon stream obtained in step b) to at least one crystallization step so as to obtain a purified styrene composition

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS12338215B2Process and apparatus for preparing purified styrene composition using divided-wall column and crystallization unit

Publication Date: 2025.06.24 SULZER MANAGEMENT AG

AI summary

A method for preparing a purified styrene composition includes providing a crude hydrocarbon composition containing styrene, subjecting the crude hydrocarbon composition to a distillation in a divided-wall column to produce an overhead hydrocarbon stream, a bottom hydrocarbon stream and a side hydrocarbon stream and subjecting the side hydrocarbon stream to at least one crystallization step to obtain a purified styrene composition.