Combined Cycle Power Plant Heat Recovery and Fuel Preheating
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Solution Overview
Problem
Combined cycle power plants face inefficiencies due to high NOx emissions and operational inflexibility, particularly in achieving high turbine inlet temperatures, and the wasteful use of heat in steam management.
Innovation Solution
A power plant configuration where the cooling medium from the steam turbine is reused as a heating medium in the gas turbine's heating device, pre-heating the fuel, and the gas turbine's cooling medium is used to enhance the efficiency of the combined cycle by integrating a counter-flow heat exchanger system, allowing for the efficient use of heat in both the gas and steam turbine assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high turbine inlet temperature is used to achieve high efficiency, then energy efficiency is improved, but NOx emissions increase
Solution Approach 1:
The fuel is pre-heated before entering the combustor assembly, which improves combustion efficiency and allows for reduced turbine inlet temperatures while maintaining energy efficiency. The pre-heating action prepares the fuel in advance to burn more completely at lower temperatures
Solution Approach 2:
The invention changes the temperature parameter of the fuel by pre-heating it before combustion. This parameter change in fuel temperature improves the combustion process efficiency without requiring high turbine inlet temperatures, thereby reducing NOx emissions while maintaining energy efficiency
2Temperature
If cooling medium is used in steam turbine, then turbine cooling is achieved, but heat energy is wasted
Solution Approach 1:
The cooling medium that would normally be wasted after cooling the steam turbine is redirected to the fuel pre-heating heat exchanger. The thermal energy in the cooling medium is recovered and used to pre-heat the fuel, converting what was previously a waste stream into a useful energy source
Solution Approach 2:
Instead of discarding the cooling medium after it exits the steam turbine, the invention recovers its thermal energy by routing it through the fuel pre-heating heat exchanger. This recovery process extracts useful heat energy before the cooling medium is ultimately discharged or condensed
3Adaptability or versatility
If sequential combustion stages are implemented, then operational flexibility is improved, but device complexity increases
Solution Approach 1:
The combustor assembly is divided into multiple combustion stages with separate fuel injection systems. This segmentation allows independent control of each stage, providing operational flexibility to adjust combustion characteristics while keeping each individual stage relatively simple
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 improves energy efficiency and operational flexibility by reducing NOx emissions and utilizing heat more effectively, enhancing the overall performance of the combined cycle power plant.
Implementation Method 1
A power plant configuration where the cooling medium from the steam turbine is reused as a heating medium in the gas turbine's heating device, pre-heating the fuel, and the gas turbine's cooling medium is used to enhance the efficiency of the combined cycle by integrating a counter-flow heat exchanger system
Implementation Method 2
integrating a counter-flow heat exchanger system, allowing for the efficient use of heat in both the gas and steam turbine assemblies
Data Source
Figure 1~2
Figure 3~4
AI summary
Power plant comprising a gas turbine assembly provided with: a compressor compressing incoming air and feeding compressed air to a plenum; a combustor assembly configured for feeding at least a fuel coming from a fuel source in the compressed air and generating by combustion a hot gas flow; a turbine driven by the hot gas performing work on a rotor connected to a generator; a heating assembly comprising a heating device for pre-heating the fuel, an inlet fuel duct connecting the fuel source to the heating device, an outer fuel duct connecting the heating device to the combustor assembly, an inlet heating medium duct for feeding a heating medium to the heating device and an outlet heating medium duct for delivery the heating medium from the heating device; a cooling assembly comprising a cooling device for cooling spilled high pressure air, an inlet air duct connecting the plenum to the cooling device, an outlet air duct connecting the cooling device to the turbine and/or the rotor for cooling reason, an inlet cooling medium duct for feeding a cooling medium to the cooling device and an outlet cooling medium duct for delivering the cooling medium from the cooling device.