Syngas CO2 Absorption with Multi-Stage Flash Solvent Recycle

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Solution Overview

Problem

Existing processes for removing carbon dioxide from synthesis gas require high electricity consumption due to the large-scale use of electrical energy for recompressing absorption media and compressing desorbed carbon dioxide, leading to high operating and capital costs.

Innovation Solution

A process that involves recycling partially regenerated absorption medium from flash stages upstream of the last stage, reducing the amount of carbon dioxide to be compressed, and using pressure reduction (flashing) for desorption without hot regeneration, thereby minimizing energy and coolant consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the last flash stage is operated at negative pressure to achieve quantitative carbon dioxide desorption, then carbon dioxide removal efficiency is improved, but electricity consumption for recompressing absorption medium and compressing carbon dioxide increases significantly

Engineering Contradiction:

Improvecarbon dioxide removal efficiencyVSAvoidelectricity consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The invention divides the absorption medium recycling into multiple streams: a first stream from the negative pressure flash stage and a second stream from an upstream flash stage. This segmentation allows partial recycling at different pressure levels, reducing the total compression work required while maintaining effective carbon dioxide removal.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention changes the pressure parameter at which part of the absorption medium is recycled by tapping it from an upstream flash stage rather than the final negative pressure stage. This parameter change reduces the compression energy required for the recycled stream while maintaining the beneficial effects of negative pressure flashing for carbon dioxide desorption.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If large amounts of absorption medium are used to achieve required carbon dioxide separation rates, then carbon dioxide removal efficiency is improved, but electricity consumption of pumps increases

Engineering Contradiction:

Improvecarbon dioxide separation rateVSAvoidelectricity consumption of pumps

Core Design Contradiction:

ProductivityVSUse of energy by moving object

Solution Approach 1:

The invention recovers absorption medium at multiple stages, including upstream flash stages where the medium is still partially loaded with carbon dioxide. This partial recovery and reuse reduces the total amount of fresh absorption medium required and decreases pump electricity consumption while maintaining separation productivity.

Inventive Principle:

Principle #34Discarding and recovering

3Manufacturing precision

If the absorption medium is completely regenerated at negative pressure, then carbon dioxide desorption is improved, but the amount of carbon dioxide requiring compression increases

Engineering Contradiction:

Improvecarbon dioxide desorption completenessVSAvoidamount of carbon dioxide to be compressed

Core Design Contradiction:

Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The invention extracts and recycles absorption medium at an upstream flash stage before complete carbon dioxide desorption occurs in the negative pressure stage. This extraction removes a portion of the absorption medium that still contains some carbon dioxide, reducing the total amount of carbon dioxide that must be compressed and disposed of.

Inventive Principle:

Principle #2Taking out (Extraction)

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

Significant energy savings are achieved, reducing electricity consumption by 16% and operating costs by 9%, with lower capital costs for compressors and improved carbon dioxide separation efficiency.

Implementation Method 1

removing carbon dioxide from the synthesis gas by physical absorption of the carbon dioxide in the absorption medium at absorption pressure in the absorption apparatus

Methodology Applied

Scientific EffectPhysical absorption: Absorption (physical)

Implementation Method 2

removing carbon dioxide from the laden absorption medium withdrawn from the absorption apparatus by desorption of the carbon dioxide in a plurality of serially arranged flash stages by pressure reduction relative to the absorption pressure

Methodology Applied

Scientific EffectDesorption: Desorption

Data Source

PatentUS12502638B2Process and plant for removing carbon dioxide from synthesis gas

Publication Date: 2025.12.23 LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE

AI summary

The present invention relates to a process for removing carbon dioxide from a synthesis gas having at least hydrogen and carbon dioxide in which the synthesis gas is at least partially freed of carbon dioxide in an absorption apparatus by physical absorption at elevated absorption pressure. The carbon dioxide is subsequently desorbed by pressure reduction relative to the absorption pressure in a plurality of serially arranged flash stages and an at least partially regenerated absorption medium is withdrawn from the last of the plurality of serially arranged flash stages, recompressed to absorption pressure and recycled into the absorption apparatus for use as absorption medium. It is also provided according to the invention that a partially regenerated absorption medium from a flash stage upstream of the last of the plurality of serially arranged flash stages is recompressed to absorption pressure and recycled into the absorption apparatus for use as absorption medium.