Power Generation Process with CO2 Recycle via Membrane Separation

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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 turbine or boiler exhaust streams, recycling a portion back into the power generation process and sending another portion for further processing or sequestration, thereby reducing the carbon dioxide content in exhaust gases and enhancing capture efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If excess air is used as diluent to control combustor temperature, then temperature control is improved, but carbon dioxide concentration in exhaust gas decreases to 4-5%

Engineering Contradiction:

Improvecombustor temperatureVSAvoidcarbon dioxide concentration

Core Design Contradiction:

TemperatureVSQuantity of substance

Solution Approach 1:

A portion of the exhaust gas stream is recycled back to the combustor inlet, creating a feedback loop that concentrates carbon dioxide in the exhaust while maintaining temperature control. The recycled stream containing higher CO2 concentration is mixed with fresh air and fed back to the combustor, allowing temperature management without excessive dilution.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The recycled exhaust gas stream acts as an intermediary between the combustor and environment, carrying concentrated carbon dioxide back to the inlet. This intermediary stream enables CO2 concentration enhancement while the fresh air portion maintains combustion temperature control.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Quantity of substance

If exhaust gas is recycled to increase carbon dioxide concentration to 8-10%, then carbon dioxide concentration is improved, but the volume of gas requiring treatment increases

Engineering Contradiction:

Improvecarbon dioxide concentrationVSAvoidgas volume for treatment

Core Design Contradiction:

Quantity of substanceVSLoss of substance

Solution Approach 1:

Carbon dioxide is extracted from the exhaust gas stream through the recycling process. By separating and concentrating CO2 in the recycled portion, the overall volume requiring full treatment is reduced, as the concentrated stream can be handled more efficiently downstream.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The process recovers carbon dioxide from the exhaust stream by recycling a portion back to the combustor. This recovery concentrates CO2 in the exhaust while the recovered portion is reused, reducing the net volume that must be treated and disposed of.

Inventive Principle:

Principle #34Discarding and recovering

3Object-generated harmful factors

If additional equipment is added for carbon dioxide capture in combined cycle power generation, then carbon dioxide capture capability is improved, but device complexity and cost increase

Engineering Contradiction:

Improvecarbon dioxide capture capabilityVSAvoidequipment complexity

Core Design Contradiction:

Object-generated harmful factorsVSDevice complexity

Solution Approach 1:

The exhaust gas recycling system serves multiple functions: it controls combustor temperature, concentrates carbon dioxide in the exhaust stream, and reduces the volume requiring treatment. This multi-functionality achieves CO2 capture capability without requiring separate dedicated equipment for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The temperature control and CO2 concentration functions are merged into a single exhaust gas recycling system. The same recycling loop that manages combustor temperature also concentrates CO2, eliminating the need for separate equipment and reducing overall system complexity.

Inventive Principle:

Principle #5Merging (Combining)

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 carbon dioxide content in exhaust gases, making downstream separation more economical and environmentally friendly, while minimizing the amount released into the environment, and simplifies transportation and processing of captured carbon dioxide.

Implementation Method 1

routing a third portion of the turbine exhaust stream to a sweep-based membrane separation step... providing a membrane having a feed side and a permeate side, and being selectively permeable to carbon dioxide over nitrogen and to carbon dioxide over oxygen

Methodology Applied

Scientific EffectSelective permeation: Permeation

Data Source

PatentUS8220247B2Power 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.