Combined Cycle Plant Control Device Operation Modes
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Solution Overview
Problem
Combined cycle plants face inefficiencies in output and energy management due to variations in steam flow and gas turbine operations, leading to suboptimal plant efficiency when auxiliary combustion is used.
Innovation Solution
The implementation of a control device and operation method that allows for selective operation between standard and auxiliary combustion modes, enabling the use of multiple gas turbine units and steam turbines to optimize output and efficiency by adjusting fuel flow rates and combustion modes based on required outputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If auxiliary combustion device is driven to increase steam output, then steam turbine output is increased, but plant efficiency decreases due to fuel not contributing to gas turbine driving
Solution Approach 1:
The system dynamically selects between three operation sections based on required output: first operation section (single gas turbine without auxiliary combustion), second operation section (single gas turbine with auxiliary combustion for maximum output), and third operation section (dual gas turbines without auxiliary combustion). This dynamic switching resolves the contradiction by avoiding auxiliary combustion when dual gas turbine operation can meet the output requirement, thereby maintaining plant efficiency while achieving required power output.
Solution Approach 2:
The control device changes operational parameters (which gas turbine units are driven, whether auxiliary combustion is activated) based on the required output level. By adjusting these parameters, the system optimizes the balance between steam turbine output and plant efficiency, selecting the most efficient configuration for each operating condition.
2Power
If dual gas turbine units are driven without auxiliary combustion to meet high output requirements, then output is increased, but plant efficiency significantly decreases compared to using auxiliary combustion
Solution Approach 1:
The system implements dynamic operation mode selection where the control device determines the optimal operation section based on required output. For certain output ranges, the system prefers third operation section (dual gas turbines without auxiliary combustion) over second operation section (single gas turbine with auxiliary combustion), even though both can achieve the same output, because it avoids the efficiency penalty of auxiliary combustion when dual turbine operation is feasible.
Solution Approach 2:
The operation range is segmented into three distinct sections with different optimal configurations. The control device divides the decision space based on required output levels, assigning different operation strategies to different segments: low output uses first section, medium output uses second section, and high output uses third section. This segmentation allows the system to optimize efficiency for each operating regime.
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 plant efficiency by allowing for higher output and reduced energy consumption, providing operators with the ability to select optimal operation modes based on efficiency and output requirements, thereby improving overall plant performance.
Implementation Method 1
a first heat recovery steam generator which is configured to generate steam using heat of an exhaust gas of the first gas turbine
Implementation Method 2
a second heat recovery steam generator which is configured to generate steam using heat of an exhaust gas of the second gas turbine
Implementation Method 3
The auxiliary combustion device is configured to burn fuel in a steam generator frame of the first heat recovery steam generator to increase an amount of generated steam
Data Source
AI summary
A control device causes a combined cycle plant to perform a first operation section, a second operation section, and a third operation section. In the first operation section, a first gas turbine unit and a steam turbine are driven without driving an auxiliary combustion device. The control device causes the plant to perform the second operation section in which the first gas turbine unit, the auxiliary combustion device, and the steam turbine are driven when a required output equal to or greater than a maximum output in the first operation section is received. The control device causes the plant to perform the third operation section in which the first gas turbine unit, the second gas turbine unit, and the steam turbine are driven without driving an auxiliary combustion device when a required output equal to or greater than a maximum output in the second operation section is received.