Method for high efficiency power generation using a carbon dioxide circulating working fluid
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Solution Overview
Problem
Current power generation methods from fossil fuels face challenges with rising energy costs and increased carbon dioxide emissions, necessitating high efficiency systems for reduced CO2 emissions and improved sequestration, while existing CO2 capture technologies have low thermal efficiencies and high capital costs.
Innovation Solution
A method utilizing a transpiration cooled combustor with a CO2 circulating fluid, where CO2 is introduced with fuel and oxidant for combustion, producing a high-pressure, high-temperature fluid stream that expands through a turbine for power generation, allowing for efficient separation and recycling of CO2 for sequestration, and using a heat exchanger to maintain high pressure and temperature ratios for efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If conventional CO2 capture technology is used, then CO2 emissions are reduced, but thermal efficiency decreases and capital costs increase
Solution Approach 1:
The patent changes the operating parameters of the power generation system by using supercritical CO2 as the working fluid and operating the heat exchanger at high pressure (above CO2 critical pressure of 7.38 MPa). This allows the system to achieve both CO2 capture and high thermal efficiency by utilizing the unique properties of supercritical CO2, which has high density and high heat capacity, enabling efficient heat transfer without the penalties of conventional CO2 capture technologies.
Solution Approach 2:
The heat exchanger serves multiple functions simultaneously: it acts as both a heat transfer device and a CO2 separation device. By operating the heat exchanger at supercritical conditions, the system achieves both power generation and CO2 capture in a single integrated process, eliminating the need for separate capture equipment and thereby maintaining high thermal efficiency while reducing CO2 emissions.
2Object-generated harmful factors
If conventional CO2 capture technology is used, then CO2 emissions are reduced, but capital costs increase
Solution Approach 1:
The heat exchanger serves multiple functions simultaneously: it acts as both a heat transfer device and a CO2 separation device. By operating the heat exchanger at supercritical conditions, the system achieves both power generation and CO2 capture in a single integrated process, eliminating the need for separate capture equipment and thereby reducing capital costs.
Solution Approach 2:
The patent merges the CO2 capture function with the existing heat exchanger in the power generation cycle. Instead of adding separate capture equipment, the system integrates CO2 separation into the heat exchanger by operating at supercritical conditions, thereby reducing device complexity and capital costs while achieving CO2 emissions reduction.
3Productivity
If high pressure is maintained during turbine expansion, then power generation efficiency increases, but CO2 separation becomes more difficult
Solution Approach 1:
The patent changes the pressure parameter during the expansion process by maintaining high pressure (above critical pressure) throughout the turbine expansion. This allows the system to extract maximum work from the expanding gas while the exhaust remains in supercritical state, enabling easy CO2 separation through pressure-controlled phase change or dissolution, thus resolving the contradiction between power generation efficiency and CO2 separation difficulty.
Solution Approach 2:
The system utilizes phase transitions of CO2 by maintaining it in supercritical state during expansion and then facilitating its separation through controlled pressure reduction or temperature change in the heat exchanger. This allows efficient power generation during expansion while enabling straightforward CO2 separation after expansion, as the supercritical CO2 can be easily separated from other combustion products.
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 achieves high efficiency power generation with reduced capital costs, enabling the production of substantially pure CO2 at pipeline pressure for sequestration, exceeding the efficiency of current coal-fired power stations and minimizing atmospheric CO2 release.
Implementation Method 1
using a heat exchanger to maintain high pressure and temperature ratios for efficient energy transfer
Implementation Method 2
producing a high-pressure, high-temperature fluid stream that expands through a turbine for power generation
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The present invention provides methods and system for power generation using a high efficiency combustor in combination with a CO2 circulating fluid. The methods and systems advantageously can make use of a low pressure ratio power turbine and an economizer heat exchanger in specific embodiments. Additional low grade heat from an external source can be used to provide part of an amount of heat needed for heating the recycle CO2 circulating fluid. Fuel derived CO2 can be captured and delivered at pipeline pressure. Other impurities can be captured.