CO2 Tail Gas Purification for High-Purity Carbon Dioxide Recovery

Solution Overview

Problem

Biogas upgrading processes are not 100% efficient in separating methane and removing inert gases and contaminants, resulting in a tail gas stream that contains valuable carbon dioxide (CO2) which is not suitable for direct use in high-purity applications due to impurities such as COS, H2S, and siloxanes.

Innovation Solution

A multi-step process involving compression, cooling, dehydration, chemical scrubbing, pressure swing adsorption, vacuum swing adsorption, membrane separation, and cryogenic distillation to purify CO2 from the tail gas stream, achieving high-purity CO2 suitable for food-grade or beverage-grade applications.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If biogas upgrading processes are used to separate methane and remove contaminants, then methane concentration is improved, but carbon dioxide and other valuable components are lost in the tail gas stream

Engineering Contradiction:

Improvemethane concentrationVSAvoidcarbon dioxide recovery

Core Design Contradiction:

Manufacturing precisionVSLoss of substance

Solution Approach 1:

The patent extracts and recovers carbon dioxide from the tail gas stream that would otherwise be discarded. The system specifically targets and separates CO2 from the biogas upgrading process tail gas, converting what was previously waste into a valuable recovered product.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention transforms the discarded tail gas stream containing CO2 into a valuable resource. By implementing recovery systems for CO2 and other components from the tail gas, the process converts waste materials into recoverable products for potential reuse or sale.

Inventive Principle:

Principle #34Discarding and recovering

2Manufacturing precision

If multiple purification steps are implemented to achieve high-purity CO2, then CO2 purity is improved, but process complexity increases

Engineering Contradiction:

ImproveCO2 purityVSAvoidprocess complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The purification process is divided into distinct sequential stages: compression, cooling, dehydration, chemical scrubbing, pressure swing adsorption, vacuum swing adsorption, membrane separation, and cryogenic distillation. Each stage targets specific impurities and builds upon the previous stage to achieve progressively higher purity levels.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The process performs preliminary removal of bulk impurities through compression, cooling, and dehydration before applying more sophisticated purification techniques. This preliminary action reduces the burden on subsequent purification stages and improves overall process efficiency.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If advanced purification methods are used to remove impurities like COS, H2S, and siloxanes, then CO2 purity is improved, but energy consumption increases

Engineering Contradiction:

ImproveCO2 purityVSAvoidenergy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The process utilizes changes in physical parameters including pressure, temperature, and phase states to separate and purify CO2 from impurities. By manipulating these parameters through compression, cooling, and cryogenic distillation, the system achieves high purity separation.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The purification process exploits phase transitions of CO2 and impurities at different temperatures and pressures. Cryogenic distillation specifically utilizes the different boiling points and phase behaviors of CO2 versus contaminants like COS, H2S, and siloxanes to achieve separation.

Inventive Principle:

Principle #36Phase transitions

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

The process effectively removes impurities from the CO2-containing tail gas, enabling its use in high-purity applications such as food-grade CO2 production and industrial processes, while recovering valuable CO2 that would otherwise be wasted.