Thermal Integration of CO2 Capture with Steam Cycle
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Solution Overview
Problem
Conventional fossil fuel-burning power plants face inefficiencies in electricity generation due to energy-intensive CO2 separation processes, which increase costs and hinder the adoption of carbon capture and compression systems, leading to reduced overall power plant efficiency and high CO2 separation costs.
Innovation Solution
Integrating a carbon dioxide capture and compression system with an external heat cycle system, utilizing additional heat exchangers to transfer surplus heat from the CO2 capture and compression process to the external heat cycle, reducing steam extraction from the power plant and enhancing overall efficiency by using excess heat for external heating purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If CO2 separation process is implemented using conventional MEA-based absorption, then CO2 capture is achieved, but steam extraction increases and electricity output decreases
Solution Approach 1:
The patent merges the CO2 capture process with the power plant's existing steam cycle by integrating the amine reboiler with the steam turbine exhaust system. The CO2-rich amine solution is heated in the reboiler using low-pressure steam from the turbine exhaust, allowing simultaneous CO2 capture and electricity generation without additional steam extraction from the main cycle.
Solution Approach 2:
The steam turbine exhaust steam serves multiple functions: it drives the power generation cycle and simultaneously provides thermal energy for the CO2 capture reboiler process. This multi-functionality allows the same steam to contribute to both electricity production and CO2 separation, eliminating the trade-off between the two processes.
2Quantity of substance
If steam extraction is increased to provide heat for CO2 separation, then CO2 capture efficiency improves, but power plant overall efficiency decreases
Solution Approach 1:
The patent combines the CO2 capture thermal process with the power plant's waste heat recovery system. The reboiler is integrated into the steam cycle, using exhaust steam that would otherwise be condensed and discarded, to provide the necessary heat for CO2 separation without extracting additional steam from the power-generating portion of the cycle.
Solution Approach 2:
The patent converts the harmful waste heat from steam turbine exhaust into a beneficial resource for driving the CO2 capture process. By using the low-pressure exhaust steam to heat the amine solution in the reboiler, the system transforms what was previously a waste product into a useful thermal energy source for CO2 separation.
3Quantity of substance
If CO2 compression unit is added to the system, then CO2 sequestration capability improves, but system complexity and cooling requirements increase
Solution Approach 1:
The patent integrates the CO2 compression unit with the existing steam cycle by using the same low-pressure steam to drive both the power generation turbine and the CO2 compression process through thermal coupling. The compression unit is thermally integrated with the reboiler system, sharing the same heat source and reducing the need for separate cooling infrastructure.
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 steam extraction from the steam turbine, increases power plant efficiency, and optimizes the use of heat from the CO2 capture plant, allowing for more efficient operation of the heat recovery steam generator and external heat cycle systems.
Implementation Method 1
carbon dioxide gas is released from the absorbing solution by increasing the temperature of the absorber solution by directing it through a reboiler
Implementation Method 2
The cooling concept increases the efficiency of the CO2 compression unit due to low inlet temperatures to the compressors
Implementation Method 3
heat from the carbon dioxide capture and compression system is transferred to the flow medium of an external heat cycle system by at least one additional heat exchanger
Data Source
AI summary
A power plant system including a fossil fuel fired power plant (6) for the generation of electricity, a carbon dioxide capture and compression system (5, 13), and an external heat cycle system has at least one heat exchanger (1,2,3) for the heating of the flow medium of the external heat cycle system. The heat exchanger (1,2,3) is connected to a heat flow from the CO2 capture plant (5) or a CO2 compression unit (13). A return flow from the heat exchanger (1,2,3) is led to the CO2 capture and compression system (5,13) or to the power plant (6). The power plant system allows an increase in overall efficiency of the system.