CCPP Fuel Heating System Reducing Parasitic Pumping Losses
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing combined cycle power plant (CCPP) fuel heating systems experience significant parasitic pumping losses due to the need for high water pressure to prevent flashing, which increases energy consumption and reduces efficiency as the target temperature for heated fuel increases.
Innovation Solution
The implementation of a fuel heating system with a high temperature heat exchanger integrated into the CCPP, where water from the economizer is used to preheat fuel, and a recirculation line with a hydro turbine to reduce parasitic pumping losses by closely matching the pressure required for water circulation to the friction loss in the circuit, thereby minimizing energy expenditure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If water pressure is increased to prevent flashing in the fuel heating circuit, then the water remains in liquid phase at high temperatures, but the parasitic pumping power loss increases significantly
Solution Approach 1:
The invention changes the operating parameters of the fuel heating circuit by reducing the water flow rate and optimizing the pressure profile. By using a restricted orifice or valve to control water flow into the fuel heater, the system maintains sufficient pressure to prevent flashing while minimizing the pumping power required. The pressure is maintained just high enough to keep water liquid at the heater outlet, rather than using excessively high pressures throughout the circuit.
Solution Approach 2:
The fuel heating circuit is designed to be self-regulating, where the water flow and pressure are automatically balanced by the system's thermal and hydraulic characteristics. The water pressure and flow rate self-adjust based on the fuel heating demand and thermal conditions, eliminating the need for complex active pressure control systems and reducing parasitic losses.
2Temperature
If the target temperature for heated fuel is increased to improve combustion efficiency, then the fuel heating benefit increases, but the water pressure and parasitic pumping losses increase exponentially
Solution Approach 1:
The invention optimizes the water flow rate parameter to achieve high fuel temperatures without exponential increases in pumping power. By carefully controlling the water flow rate through restriction devices and optimizing the heat exchanger design, the system achieves effective fuel preheating at moderate water pressures, breaking the exponential relationship between temperature and pumping loss.
Solution Approach 2:
The system maintains continuous fuel heating at optimized temperature levels, ensuring that the water flow and heat transfer processes operate continuously at efficient points. This continuous optimized operation prevents the need for periodic high-pressure surges that would increase parasitic losses.
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 allows for efficient fuel preheating while significantly reducing parasitic pumping losses, maintaining high fuel temperatures at the combustion section inlet with lower energy consumption compared to prior designs.
Implementation Method 1
a high temperature heat exchanger disposed in thermal communication on the fuel supply line
Implementation Method 2
a hydro turbine disposed on the recirculation line
Data Source
AI summary
A combined cycle power plant (CCPP) includes a heat recovery steam generator (HRSG) that includes a first economizer and a condensate supply line. The HRSG receives a flow of exhaust gas from the turbine section. The CCPP further includes a fuel heating system that has a fuel supply line and a high temperature heat exchanger. The fuel supply line is fluidly coupled to the combustion section. The high temperature heat exchanger is disposed in thermal communication on the fuel supply line. A high temperature input line fluidly couples the high temperature heat exchanger to the first economizer of the HRSG such that the high temperature heat exchanger receives water from the first economizer. A recirculation line fluidly coupling the high temperature heat exchanger to the condensate supply. A hydro turbine is disposed on the recirculation line.