Dimethyl Ether Separation via Pressure-Based Absorption

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Solution Overview

Problem

Current methods for separating dimethyl ether (DME) from synthesis gas product streams are inefficient in terms of energy usage, particularly due to the need for significant cooling and the presence of harmful carbon dioxide, which can damage catalysts and reduce catalyst lifetimes.

Innovation Solution

A method involving the partial recycling of unreacted synthesis gas, adjusted to minimize carbon dioxide content, using a combination of absorption and distillation columns to separate and purify DME, allowing for operation with a lower portion of shifted synthesis gas and reducing energy-intensive processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional cooling methods are used to separate DME from product stream, then DME can be obtained, but energy consumption increases significantly

Engineering Contradiction:

ImproveDME separation purityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the separation parameter from temperature-based cooling to pressure-based separation. By maintaining the product stream at reaction pressure (20-100 bar) and utilizing the pressure-dependent solubility differences in the absorption medium, DME is separated without significant cooling, thus reducing energy consumption while achieving required purity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an absorption medium as an intermediary substance to facilitate DME separation. This medium selectively absorbs DME from the product stream at reaction pressure, enabling separation without direct cooling and reducing the energy required for the separation process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If carbon dioxide is not removed from recycling stream, then process is simpler, but catalyst lifetime decreases due to catalyst damage

Engineering Contradiction:

Improveprocess complexityVSAvoidcatalyst lifetime

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The patent combines the CO2 removal function with the existing absorption separation process. The same absorption medium and column used for DME separation also remove CO2 from the recycling stream, merging two separation functions into one process unit and avoiding additional complex equipment while protecting the catalyst

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements continuous CO2 removal from the recycling stream through the absorption column. The absorption medium continuously contacts the recycling gas, steadily removing CO2 before the gas is recycled to the reactor, ensuring continuous catalyst protection without interrupting the production process

Inventive Principle:

Principle #20Continuity of useful action

3Object-affected harmful factors

If more shifted synthesis gas is used to reduce carbon dioxide, then carbon dioxide content decreases, but production cost increases

Engineering Contradiction:

Improvecarbon dioxide contentVSAvoidproduction cost

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The patent converts the harmful effect of CO2 in the recycling stream into a benefit by using CO2 as part of the absorption process. The absorption medium utilizes CO2 solubility differences to achieve both DME separation and CO2 removal, turning the harmful CO2 into a useful separation mechanism and eliminating the need for expensive shifted synthesis gas

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 enhances the economic viability and efficiency of DME production by reducing energy consumption, extending catalyst lifetimes, and achieving higher purity DME with reduced carbon dioxide levels in the recycling stream.

Implementation Method 1

a gas mixture which contains at least dimethyl ether, carbon dioxide and at least one further component which boils more easily than carbon dioxide is separation processed

Methodology Applied

Scientific EffectAbsorption: Absorption (physical)

Implementation Method 2

using a combination of absorption and distillation columns to separate and purify DME

Methodology Applied

Scientific EffectDistillation: Distillation

Data Source

PatentUS20230331650A1Method and plant for preparing dimethyl ether

Publication Date: 2023.10.19 LINDE AG

AI summary

A method for preparing dimethyl ether (DME) from synthesis gas, wherein an input, which is formed using shifted and/or non-shifted synthesis gas, undergoes a catalytic conversion, thereby forming a product stream. The product stream undergoes a first separation, wherein a gas mixture is formed by at least partial separation of methanol and/or water from the product stream, and the gas mixture is partially condensed at a first pressure level by means of cooling from a first to a second temperature level. A portion of the gas mixture remaining in gaseous form at the second temperature level is washed in an absorption column with a return predominantly containing dimethyl ether, wherein a dimethyl ether product is formed using the portion of the gas mixture condensed during cooling.