Flash Tank Extracts HRSG Cold End Heat for CCPP Efficiency
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Solution Overview
Problem
Combined cycle power plants face inefficiencies due to unused heat at the cold end of the heat recovery steam generator (HRSG), which hinders optimal energy utilization and output.
Innovation Solution
The implementation of a flash tank connected to the cold end of the HRSG to extract hot water, with supply lines interconnecting it to the steam turbine and gas turbine air preheating system, allowing for the injection of flash steam and hot condensate to enhance energy utilization, and optional bypass and recirculation systems to manage heat effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional heat capture techniques are used in the HRSG, then the majority of heat energy is utilized, but heat at the cold end of the HRSG remains unused
Solution Approach 1:
The patent extracts hot water from the cold end of the HRSG using a flash tank, separating this previously unused heat resource from the main steam generation cycle. This extracted hot water is then utilized to generate flash steam that can be directed to steam turbines for additional power generation, thereby converting the previously wasted cold end heat into useful energy.
Solution Approach 2:
The patent changes the state parameters of water by introducing a flash tank that reduces pressure, causing hot water from the HRSG cold end to flash-evaporate and generate steam. This parameter change (pressure reduction) enables the extraction of useful thermal energy from water that would otherwise be discarded or underutilized.
2Loss of energy
If a flash tank is added to extract hot water from the cold end of the HRSG, then heat utilization is improved, but system complexity increases
Solution Approach 1:
The flash tank serves multiple functions: it extracts hot water from the HRSG cold end, generates flash steam for power generation, and provides a simple pressure reduction mechanism. This multi-functionality justifies the addition of the flash tank by delivering multiple benefits from a single component.
Solution Approach 2:
The flash tank acts as an intermediary device between the HRSG cold end and the steam turbine. It mediates the conversion of hot water into flash steam, creating a bridge that enables the utilization of cold end heat without requiring direct integration between the HRSG and steam turbine.
3Productivity
If flash steam is supplied to the steam turbine, then additional power is generated, but the system requires additional supply lines and control mechanisms
Solution Approach 1:
The patent merges the flash steam supply system with the existing steam turbine infrastructure. The flash steam generated from the flash tank is combined with the main steam flow or directed to auxiliary steam turbines, integrating the new power generation path with the existing system rather than creating entirely separate systems.
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 configuration optimally utilizes heat at the cold end of the HRSG, increasing the efficiency and output of the power plant by generating additional power and simplifying the system, making it more economical and cost-effective.
Implementation Method 1
The at least one flash tank fluidically connected at a cold end of the at least one heat recovery steam generator to extract hot water from the cold end
Implementation Method 2
The at least one heat recovery steam generator is thermally connected to the at least one gas turbine to use heat energy extracted from the exhaust gas of the at least one gas turbine to produce steam
Implementation Method 3
The at least one steam turbine is thermally connected to the at least one heat recovery steam generator to utilize the steam produced by the at least one heat recovery steam generator to generate the power
Implementation Method 4
The at least one gas turbine is configured to produce gas to generate power and subsequently releasing the exhaust gas
Data Source
AI summary
A CCPP includes a gas turbine, a HRSG, a steam turbine a flash tank and first and second supply lines. The gas turbine, the HRSG and the steam turbine are interconnected to generate power. The gas turbine may include an air preheating system to preheat the air supplied in the gas turbine to enable expedite combustion therein. The flash tank is fluidically connected at a cold end of the HRSG to extract waste hot water from the cold end. Further, the first supply line is configured to interconnect the flash tank and the steam turbine to supply of flash steam to the steam turbine. Furthermore, the second supply line is configured to interconnect the flash tank and the air preheating system to supply hot flash condensate thereto.