Steam Unit Heat Maintaining Assembly for Rapid Power Plant Restart
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Solution Overview
Problem
Combined cycle power plants face challenges in maintaining high internal temperatures of the steam unit during shutdown, leading to prolonged start-up times due to natural cooling, which existing solutions do not adequately address.
Innovation Solution
A combined cycle power plant equipped with a heat maintaining assembly that controls temperature in the steam unit by using heating and cooling arrangements to maintain temperature during shutdown, utilizing sensors and control devices to regulate airflow and heating to maintain optimal temperatures in high-pressure and intermediate-pressure steam turbines and cool air entering the low-pressure steam turbine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power plant is shut down for a few hours, then the steam unit cools down naturally, but the start-up time increases and reliability decreases
Solution Approach 1:
The patent applies preliminary action by maintaining the steam unit temperature during shutdown through a dedicated temperature maintenance system. Before shutdown, the system pre-heats the steam unit using extracted steam from the turbine, and during shutdown, it continues to supply heat to prevent cooling. This preliminary and continuous heating action ensures that when restart is needed, the steam unit is already at or near operating temperature, eliminating the need for lengthy warm-up periods and enabling rapid restart within 10 minutes.
2Speed
If the steam unit temperature is maintained at high levels during shutdown, then the run-up rate increases, but energy consumption increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the temperature maintenance level based on the anticipated restart time and grid conditions. The system uses a control unit that monitors various parameters (shutdown duration, ambient temperature, steam unit temperature) and adjusts the heating intensity accordingly. When restart is imminent, the system maintains high temperature; when restart is delayed or grid conditions are unfavorable, the system reduces heating intensity, thereby optimizing the balance between run-up rate and energy consumption.
Solution Approach 2:
The patent implements periodic action through intermittent heating cycles during shutdown. Instead of continuous high-intensity heating, the system employs periodic heating pulses or cycles, where the heating is activated during specific intervals and reduced or stopped during others. This periodic heating pattern maintains the steam unit temperature within an acceptable range while significantly reducing overall energy consumption compared to continuous heating, enabling the system to achieve rapid restart when needed without excessive energy waste during extended shutdowns.
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 solution enables faster run-up rates and shorter start-up times by effectively maintaining steam unit temperatures during shutdown, improving the reliability and efficiency of the power plant.
Implementation Method 1
supplying a hot air flow into a steam turbine
Implementation Method 2
use the heat of the hot fumes coming from the gas turbine unit to generate steam in the steam circuit
Data Source
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AI summary
A power plant comprises: at least one steam unit (3) provided with at least one first steam turbine (7a; 7b) rotating about a shaft and provided with an casing (9a; 9b) comprising a first lower casing and a first upper casing coupled together; a heat maintaining assembly (5) for controlling the temperature in the steam unit (3) during the shut-off of the plant (1); the heat maintaining assembly (5) comprising: □ a first supply line (23; 38) configured to supply a first flow rate (Q1; Q2) of heated air into the at least one first steam turbine (7a;7b) ; the first air supply line (23; 38) comprising a first blower (30; 44) and at least one first heater (31; 45); □ a first upper casing temperature sensor (26; 41) arranged outside the first upper casing and configured to detect a first upper casing temperature (TU1; TU2); □ a first lower casing temperature sensor (25; 40) arranged outside the first lower casing and configured to detect a first lower casing temperature (TL1;TL2); □ a control device (22) configured to regulate at least the first blower (30; 44) on the basis of the difference between the first upper casing temperature (TU1; TU2) and the first lower casing temperature (TL1; TL2).