Acidic Gas Removal via Detergent Segmentation and Pressure Relaxation

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Solution Overview

Problem

Existing methods for removing acidic gas components from synthesis gas in gas scrubbing processes result in high carbon dioxide content in recycle gases, leading to increased costs due to larger compressors and higher energy consumption.

Innovation Solution

A method involving the partial mixing of two detergents with different carbon dioxide concentrations in an expansion tank for pressure relaxation, allowing carbon dioxide desorption from the higher concentration detergent to be absorbed by the lower concentration detergent, reducing the overall carbon dioxide content in the recycle gas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional gas scrubbing processes are used to remove acidic gas components from synthesis gas, then the acidic gas components are effectively removed, but the carbon dioxide content in the recycle gas becomes excessively high

Engineering Contradiction:
Improveacidic gas component removal efficiencyVSAvoidcarbon dioxide content in recycle gas
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The invention divides the loaded detergent stream into two separate streams with different CO2 concentrations. The first stream contains detergent loaded primarily with CO2 from the acid gas removal section, while the second stream contains detergent loaded with both H2S and CO2 from the desulfurization section. This segmentation allows selective processing to reduce CO2 in the final recycle gas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a stripping section as an intermediary process between the absorption sections and the recycle gas compression. In this stripping section, steam is introduced to selectively strip CO2 from the detergent stream before compression, thereby reducing the CO2 content in the recycle gas without compromising the acid gas removal efficiency.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Productivity

If high carbon dioxide content recycle gas is compressed and recirculated, then the acid gas removal process continues, but the compressor size and energy consumption increase

Engineering Contradiction:
Improveacid gas removal throughputVSAvoidcompressor energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The invention extracts CO2 from the recycle gas stream by introducing it into the stripping section where steam stripping selectively removes CO2 from the detergent. This extracted CO2 is then condensed and separated, resulting in a recycle gas with reduced CO2 content that requires less compression work.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the composition parameter of the recycle gas by reducing its CO2 content through the stripping and condensation process. This parameter change directly reduces the work of compression required, as compressing gas with lower CO2 content requires less energy.

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If larger compressors are used to handle high carbon dioxide content recycle gas, then the required gas flow is maintained, but the equipment size and operational costs increase

Engineering Contradiction:
Improverecycle gas flow rateVSAvoidcompressor size
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The invention performs preliminary action by stripping and condensing CO2 from the detergent stream before the gas reaches the compressor. This preliminary removal of CO2 reduces the volume and complexity requirements of the subsequent compression equipment.

Inventive Principle:
Principle #10Preliminary action

4Object-affected harmful factors

If more detergent is used to maintain absorption capacity, then the acid gas removal efficiency is maintained, but the operational costs increase

Engineering Contradiction:
Improveacid gas component removal efficiencyVSAvoiddetergent consumption
Core Design Contradiction:
Object-affected harmful factorsVSLoss of substance

Solution Approach 1:

The invention implements continuous recirculation of the stripped and condensed recycle gas back to the absorption sections. This continuous action maintains the absorption capacity of the system without requiring additional detergent, as the recycled gas continues to provide the necessary absorption medium.

Inventive Principle:
Principle #20Continuity of useful action

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 the amount of recycle gas that needs to be compressed, decreasing the load on compressors and absorption devices, and lowers the required detergent usage, thereby lowering operational costs and increasing the yield of valuable gases like carbon monoxide and hydrogen in the recycle gas.

Implementation Method 1

Methods for separating undesirable accompanying substances from raw technical synthesis gases by means of physical or chemical absorption are known from the prior art

Methodology Applied
Scientific EffectPhysical absorption: Absorption (physical)

Implementation Method 2

a first detergent loaded with at least carbon dioxide (CO2) is fed to a relaxation container from a first absorption device via a first supply line for pressure relaxation

Methodology Applied
Scientific EffectPressure relaxation: Depressurisation

Implementation Method 3

the carbon dioxide desorbed from the first loaded detergent can be absorbed by the second loaded detergent

Methodology Applied
Scientific EffectDesorption: Desorption

Implementation Method 4

the carbon dioxide desorbed from the first loaded detergent can be absorbed by the second loaded detergent

Methodology Applied
Scientific EffectAbsorption: Absorption (physical)

Data Source

PatentEP3620224B1Method for the removal of acidic gas components from synthesis gas and device for generating recycle gas
Publication Date: 2021.06.16 LAIR LIQUIDE SA POUR LETUDE & LEXPLOITATION DES PROCEDES GEORGES CLAUDE
  • EP3620224B1 patent drawingFigure 1

AI summary

The invention relates to a method and a system for removing acidic gas components from synthesis gas by absorption in a physically acting detergent. A first detergent loaded with at least carbon dioxide (CO2) is fed from a first absorption device to a pressure relief vessel via a first supply line. Furthermore, a second detergent loaded with at least carbon dioxide (CO2) is fed from a second absorption device to the pressure relief vessel via a second supply line. The carbon dioxide concentration in the first loaded detergent is higher than the carbon dioxide concentration in the second loaded detergent.According to the invention, it is provided that at least partial mixing of the first and second loaded detergents takes place in the pressure relief container, whereby a partially regenerated detergent is obtained through the mixing and pressure relief, and the first supply line and the second supply line are arranged such that carbon dioxide desorbed from the first loaded detergent by the pressure relief is at least partially absorbed by the second loaded detergent.