Combined Cycle Plant Bypass Pipe for Reduced Start-Up Time
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Solution Overview
Problem
Combined cycle power generating plants face challenges in reducing start-up time due to the time-consuming process of warming steam pipes, which can lead to increased start-up times and potential durability issues with high-temperature gas turbine components.
Innovation Solution
The implementation of a bypass pipe system that directs steam from the first steam pipe to the second steam pipe, allowing both pipes to be warmed simultaneously, along with the use of an auxiliary boiler to supply steam independently of the operational states of the gas and steam turbines, reducing the steam supply capacity requirements and minimizing the use of condensed water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If steam is used to warm the cooling steam system before gas turbine start-up, then water drop formation is prevented, but the start-up time increases
Solution Approach 1:
The steam pipes are divided into multiple sections with independent control. The first steam pipe supplies steam to the gas turbine while the second steam pipe supplies steam to the steam turbine. This segmentation allows selective warming of only the necessary pipe sections rather than warming the entire system, reducing overall warm-up time while still preventing water drop formation in critical areas.
Solution Approach 2:
The system performs preliminary warming of steam pipes using stored thermal energy in the boiler and insulated pipe sections before the gas turbine actually starts operating. By having the steam system ready in advance through controlled preliminary heating, the system eliminates the need for extended warming periods during actual start-up, thus reducing start-up time while maintaining reliability.
2Loss of time
If steam supply capacity is increased to warm pipes faster, then start-up time is reduced, but the steam supply system becomes more complex and requires larger capacity equipment
Solution Approach 1:
The steam supply system uses dynamic control valves and flow regulators that can adjust steam flow rates in real-time based on the warming requirements of different pipe sections. This dynamic adjustment allows the system to achieve fast warming when needed without requiring permanently oversized equipment, thus reducing start-up time while maintaining manageable system complexity.
Solution Approach 2:
The system changes steam flow parameters (flow rate, pressure, temperature distribution) dynamically during the warming process. By optimizing these parameters for different stages of the start-up sequence, the system achieves efficient warming without requiring excessive steam supply capacity, thereby reducing start-up time while avoiding unnecessary system complexity.
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 significantly shortens the start-up time of the combined cycle power generating plant by warming both steam pipes concurrently and reducing the steam supply capacity needs, thereby enhancing operational efficiency and durability of the gas turbine components.
Implementation Method 1
a bypass pipe that directs at least a portion of the steam in the first steam pipe to the second steam pipe between the gas turbine and the second release section
Implementation Method 2
when the pipes and the like (the cooling steam system) that supply steam become cool, a portion of the steam is condensed, and a drainage of water drops and the like is generated
Data Source
AI summary
A combined cycle power generating plant that can realize a reduction in the start-up time includes a gas turbine, a steam turbine, a steam supplying section that supplies steam to the gas turbine, a first steam pipe that directs steam from the steam supplying section to the gas turbine, a second steam pipe that directs steam from the gas turbine to the steam turbine, a first release section that carries out control such that the supply destination of steam that is directed to the first steam pipe is one of either the outside of the gas turbine or the outside of the first steam pipe, a second release section that carries out control such that the supply destination of steam that is directed to the second steam pipe is one of either the outside of the steam turbine or the outside of the second steam pipe, and a bypass pipe that directs at least a portion of the steam inside the first steam pipe to the second steam pipe between the gas turbine and the second steam pipe.