Two-Phase Cycle Expander Design to Capture Low-Quality Steam Energy
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Solution Overview
Problem
Conventional power plants face efficiency losses due to the erosion of turbine blades from water droplets and heat loss during condensation of low-quality steam, which requires reheating and results in increased fuel consumption.
Innovation Solution
Implementing a modified two-phase cycle that extracts energy from both high-quality and low-quality steam using an expander and compressor, respectively, to capture remaining enthalpy before condensation, thereby reducing energy loss and preventing blade erosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If steam is condensed in the condenser, then the steam is cooled to liquid state for reuse, but heat is lost to surrounding environments reducing overall efficiency
Solution Approach 1:
The patent captures the waste heat from condensing low-quality steam using a heat exchanger to preheat the feedwater entering the boiler. This converts the previously lost thermal energy into a useful function, reducing the fuel energy required in the boiler and improving overall cycle efficiency.
Solution Approach 2:
The patent recovers the remaining enthalpy energy from low-quality steam that would otherwise be discarded during condensation. By using the heat exchanger to extract thermal energy from the condensing steam, the system recovers valuable energy that would normally be lost to the environment.
2Reliability
If steam is reheated after passing through the turbine, then the steam quality is maintained, but fuel consumption increases
Solution Approach 1:
The patent uses the heat exchanger to preheat the feedwater before it enters the boiler, utilizing waste heat from the condensing steam. This preliminary heating action reduces the amount of additional fuel energy required to generate high-quality steam, thereby reducing overall fuel consumption while maintaining steam quality.
3Power
If water droplets impinge on turbine blades, then energy is extracted from steam, but blade erosion occurs causing damage
Solution Approach 1:
The patent extracts low-quality steam containing water droplets from the main steam flow after it passes through the turbine. By separating this two-phase flow and directing it to the heat exchanger for condensation and energy recovery, the system removes the harmful water droplets that would otherwise cause erosion if they recirculated to the turbine.
Solution Approach 2:
The heat exchanger acts as an intermediary device that receives low-quality steam from the turbine outlet, condenses the water droplets, and recovers thermal energy. This intermediary process prevents water-laden steam from returning to the turbine, thereby protecting the blades from erosion while still extracting energy through the condensation process.
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 enhances the efficiency of steam cycles by capturing energy from low-quality steam and conserving energy that would otherwise be lost during condensation, improving overall system efficiency by 5-20% compared to conventional systems.
Implementation Method 1
an expander and compressor, respectively, to capture remaining enthalpy before condensation
Implementation Method 2
an expander and compressor, respectively, to capture remaining enthalpy before condensation
Implementation Method 3
the steam is cooled to a liquid state within the condenser
Data Source
AI summary
A system including a pump, a boiler coupled to the pump, a turbine coupled to the boiler, a two-phase expander coupled to the turbine, and a condenser coupled to the two-phase expander and the pump.