Combined-Cycle Plant Steam Extraction Decoupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Combined-cycle power plants face challenges in decoupling electricity production from heat generation, particularly in seawater desalination processes, where steam extraction requirements fluctuate, leading to inefficient energy use and increased hazardous-substance emissions during partial load operations.
Innovation Solution
The method involves selectively switching between low-pressure and intermediate-pressure steam extraction from the steam turbine, coupled with supplementary firing in the heat recovery steam generator, and using thermal vapor compression devices to manage steam and electricity production independently, reducing fuel consumption and emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If steam extraction is increased to meet high heat requirements during low electricity demand, then heat supply capability is improved, but electricity production capability deteriorates
Solution Approach 1:
The system dynamically switches between different steam extraction configurations (low-pressure vs intermediate-pressure) based on real-time demand conditions. The steam turbine operates in different modes: extracting steam at low pressure for maximum electricity generation, or at intermediate pressure for optimized heat supply, allowing adaptive response to varying electricity and heat demand ratios
Solution Approach 2:
The invention changes the operating parameters of the steam turbine by switching extraction pressure levels. By adjusting the extraction pressure from low to intermediate and changing the extraction timing in the turbine cycle, the system optimizes the balance between electricity generation and heat supply according to demand conditions
2Power
If gas turbine load is reduced to match low electricity demand, then electricity production is adjusted, but steam generation capability deteriorates
Solution Approach 1:
The steam generation system is segmented into multiple independent sources: steam from the heat recovery steam generator (HRSG) and steam from the steam turbine extraction. This segmentation allows steam supply to be maintained through turbine extraction even when gas turbine load is reduced for low electricity demand periods
Solution Approach 2:
The steam turbine serves multiple functions: it generates electricity through the generator and simultaneously provides steam for heat supply through extraction. This multi-functionality ensures that steam generation capability is maintained even when electricity demand is low, as the turbine can operate in extraction mode rather than full power mode
3Productivity
If steam extraction pressure is increased for thermal vapor compression, then water production efficiency is improved, but electricity production capability deteriorates
Solution Approach 1:
The system dynamically selects the steam extraction pressure level based on the operational mode of the desalination plant. When thermal vapor compression is required for efficient water production, the system switches to intermediate-pressure extraction. When maximum electricity generation is prioritized, it uses low-pressure extraction, allowing flexible adaptation to different productivity requirements
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 allows for decoupled electricity and water production, minimizing supplementary firing and fuel consumption, while maintaining water production levels and reducing hazardous-substance emissions, even during low electricity demand periods.
Implementation Method 1
combustion air is inducted in at least one gas turbine, is compressed and is fed to at least one combustion chamber
Implementation Method 2
the exhaust gas which emerges from the at least one turbine is fed through a heat recovery steam generator in order to generate steam
Implementation Method 3
heat is provided by extraction of steam from the at least one steam turbine
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a method for operating a combined-cycle power plant (10) with cogeneration, in which method combustion air is inducted in at least one gas turbine (11), is compressed and is fed to at least one combustion chamber (19) for combustion of a fuel, and the resultant exhaust gas is expanded in at least one turbine (20) producing work, and in which method the exhaust gas which emerges from the at least one turbine (20) is fed through a heat recovery steam generator (13) in order to generate steam, which heat recovery steam generator (13) is part of a water-steam circuit (12) with at least one steam turbine (14), a condenser (32), a feedwater tank (28) and a feedwater pump (P2), wherein heat is produced by extraction of steam from the at least one steam turbine (14). In a method such as this, simple decoupling of heat and electricity production, which is advantageous for operation, is achieved in that the steam can be selectively extracted from the at least one steam turbine (14) as low-pressure steam or intermediate-pressure steam, and in that the steam extraction is switched from low-pressure steam to intermediate-pressure steam in order to restrict the electricity production.