Power Generation Process with Partial CO2 Recycle

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Solution Overview

Problem

Traditional power generation processes face challenges in efficiently recycling carbon dioxide from gaseous fuel combustion due to its dilute concentration in exhaust gases, leading to high treatment costs and environmental impact, particularly in combined cycle power generation where additional equipment increases costs and complexity.

Innovation Solution

The process involves membrane-based gas separation using sweep-based membrane separation steps to concentrate carbon dioxide from exhaust gases, recycling a portion back into the power generation process, and utilizing membranes with high carbon dioxide permeance and selectivity to reduce oxygen permeation, thereby reducing the carbon dioxide content in exhaust streams for more efficient capture and sequestration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If exhaust gas is recycled to increase carbon dioxide concentration, then carbon dioxide recovery efficiency is improved, but the oxygen content in the combustion air stream decreases

Engineering Contradiction:

Improvecarbon dioxide recovery efficiencyVSAvoidoxygen content in combustion air

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The exhaust gas recycling is divided into multiple stages: a first portion is recycled to the combustion chamber to increase carbon dioxide concentration, while a second portion is treated separately through membrane separation or other carbon dioxide removal technologies. This segmentation allows optimization of carbon dioxide recovery without compromising combustion air quality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A membrane separation unit or other carbon dioxide removal system acts as an intermediary between the exhaust gas and the combustion air stream. This intermediary selectively removes carbon dioxide from the recycled exhaust gas before it re-enters the combustion process, ensuring adequate oxygen content is maintained while still achieving carbon dioxide concentration enhancement.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If membrane separation is used to concentrate carbon dioxide, then downstream separation economy is improved, but device complexity and treatment cost increase

Engineering Contradiction:

Improvedownstream separation economyVSAvoidmembrane separation system complexity

Core Design Contradiction:

Ease of manufactureVSDevice complexity

Solution Approach 1:

Instead of using membrane separation for complete carbon dioxide removal, the system applies partial action by treating only a portion of the exhaust gas stream. This partial treatment achieves sufficient carbon dioxide concentration for economical downstream separation without the full complexity and cost of treating the entire stream.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system changes operational parameters by optimizing the split ratio between recycled exhaust gas and fresh air, adjusting membrane module configuration and operating conditions (pressure, temperature, flow rates) to achieve the minimum necessary carbon dioxide concentration enhancement for economical downstream processing.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If large volumes of dilute carbon dioxide exhaust gas are treated, then complete carbon dioxide capture is achieved, but treatment cost and energy consumption increase

Engineering Contradiction:

Improvecarbon dioxide capture completenessVSAvoidtreatment energy consumption

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The system extracts and concentrates carbon dioxide from a portion of the exhaust gas stream using membrane separation, separating the carbon dioxide-rich stream from the remaining exhaust. This extraction approach focuses treatment energy on a smaller, concentrated stream rather than treating the entire large-volume dilute stream.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Membrane separation is applied as a preliminary concentration step before downstream carbon dioxide capture processes. This preliminary action pre-concentrates the carbon dioxide, reducing the volume and energy requirements for subsequent complete capture operations.

Inventive Principle:

Principle #10Preliminary 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 significantly reduces the volume and concentration of carbon dioxide in exhaust streams, making downstream separation more economical, increasing carbon dioxide recovery, and minimizing environmental impact by concentrating carbon dioxide for easier processing and transportation.

Implementation Method 1

membrane-based gas separation using sweep-based membrane separation steps to concentrate carbon dioxide from exhaust gases, recycling a portion back into the power generation process, and utilizing membranes with high carbon dioxide permeance and selectivity

Methodology Applied

Scientific EffectPermeation: Permeation

Data Source

PatentUS8220248B2Power generation process with partial recycle of carbon dioxide

Publication Date: 2012.07.17 MEMBRANE TECHNOLOGY & RESEARCH INC

AI summary

Disclosed herein is a power generation process in which a portion of the carbon dioxide generated by gaseous fuel combustion is recycled back to the power generation process, either pre-combustion, post-combustion, or both. The power generation process of the invention may be a combined cycle process or a traditional power generation process. The process utilizes sweep-based membrane separation.