Steam Turbine Preheating via Combustion Gas Extraction
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Solution Overview
Problem
Steam turbine start-up in combined cycle power generation systems is slow due to thermal stresses from temperature gradients, limiting gas turbine output and increasing emissions and fuel waste.
Innovation Solution
A steam turbine preheating system that uses extractions of hot combustion gases from a gas turbine to warm the steam turbine during start-up, employing a controller to manage the flow and temperature of these gases through a filter system and heat exchange, potentially with attemperation and ejector systems to optimize temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam turbine is heated using traditional steam conditions, then thermal stresses are reduced, but start-up time is extended
Solution Approach 1:
The system performs preliminary heating action by introducing hot combustion gases from the gas turbine into the steam turbine before traditional steam conditions are established. This preheating reduces the temperature gradient and thermal stresses in advance, allowing the steam turbine to be ready for steam introduction sooner, thus reducing overall start-up time while maintaining thermal stress control.
Solution Approach 2:
Hot combustion gases serve as an intermediary heating medium between the gas turbine and steam turbine. Instead of directly using steam for heating from the beginning, the system uses combustion gases as a intermediate substance to transfer heat to the steam turbine components, enabling faster preheating without exceeding thermal stress limits.
2Productivity
If gas turbine output is increased during steam turbine start-up, then power generation is improved, but thermal stresses increase due to insufficient steam turbine heating
Solution Approach 1:
The system implements feedback control by continuously monitoring the temperature of the steam turbine components and the output of the gas turbine. Based on this feedback, the control system adjusts the gas turbine output and the flow rate of hot combustion gases to the steam turbine, ensuring that power generation is maximized while thermal stress limits are never exceeded. This closed-loop control allows the gas turbine to operate at higher outputs during start-up without compromising steam turbine integrity.
3Object-generated harmful factors
If steam turbine start-up is accelerated, then emissions are reduced, but thermal stress control becomes difficult
Solution Approach 1:
The system performs preliminary heating action by introducing hot combustion gases from the gas turbine into the steam turbine before traditional steam conditions are established. This preheating reduces the temperature gradient and thermal stresses in advance, allowing the steam turbine to be ready for steam introduction sooner, thus reducing overall start-up time while maintaining thermal stress control.
Solution Approach 2:
The system implements feedback control by continuously monitoring the temperature of the steam turbine components and the output of the gas turbine. Based on this feedback, the control system adjusts the gas turbine output and the flow rate of hot combustion gases to the steam turbine, ensuring that power generation is maximized while thermal stress limits are never exceeded. This closed-loop control allows the gas turbine to operate at higher outputs during start-up without compromising steam turbine integrity.
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 start-up time, lowers emissions, improves fuel efficiency, and enhances operational flexibility and performance by allowing earlier introduction of steam to the turbine, thus reducing the need for traditional steam conditions.
Implementation Method 1
uses extractions of hot combustion gases from a gas turbine to warm the steam turbine during start-up
Implementation Method 2
hot combustion gases from the gas turbine engine may be introduced into the heat recovery steam generator to generate a flow of steam
Data Source
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AI summary
The present application provides a power generation system (100). The power generation system (100) may include a gas turbine engine (110) to create a flow of combustion gases (160), a steam turbine (210), and a steam turbine preheating system (230). The steam turbine preheating system (230) may receive an extraction (240) of the flow of combustion gases (160) and delivers the extraction (240) to the steam turbine (210) to preheat the steam turbine (210).