Gas Turbine Draft Control via Pressure Equalization
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Solution Overview
Problem
Gas turbines and heat recovery steam generators face challenges in quick restart due to natural convection and pressure differences, leading to cooling and potential corrosion, which existing solutions like closing variable inlet guide vanes and shutters do not adequately address.
Innovation Solution
The method involves using draft interceptors and a reversible sucker to equalize pressure within the gas turbine and heat recovery steam generator, preventing draft by controlling air flow and pressure differences when the system is stopped.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If variable inlet guide vanes are closed and shutters/dampers are closed to counteract draft, then natural draft is reduced, but substantial draft still occurs due to leakages
Solution Approach 1:
A reversible sucker (vacuum pump) is introduced as an intermediary device to actively manage pressure differences within the gas turbine system. The sucker connects to the combustion chamber and equalizes pressure between the combustion chamber and atmosphere, preventing draft-induced cooling and corrosion by compensating for leakage paths that traditional mechanical closures cannot seal.
Solution Approach 2:
The passive mechanical system of closed vanes and shutters is supplemented by an active pneumatic system (reversible sucker) that dynamically controls pressure equalization. This replaces reliance on mechanical sealing with a pressure-controlled system that actively counteracts draft forces through vacuum generation and pressure regulation.
2Duration of action of stationary object
If the gas turbine is stopped for a long time, then conservation is achieved, but corrosion occurs due to air circulation through humid environments
Solution Approach 1:
The reversible sucker acts as a pressure equalization intermediary between the combustion chamber and atmosphere, eliminating pressure-driven air circulation that carries humid air through the system during extended stops. By maintaining pressure equilibrium, it prevents the draft mechanism that delivers corrosive humid air to internal surfaces.
Solution Approach 2:
The system creates a relatively inert environment within the combustion chamber by preventing continuous air circulation. The pressure equalization reduces exposure to external atmospheric conditions (humidity, oxygen), effectively creating a protected environment during extended stop periods and reducing corrosion rates.
3Productivity
If the gas turbine is restarted quickly, then productivity is improved, but the temperature may be too low causing steam pressure to drop below atmospheric pressure
Solution Approach 1:
The reversible sucker performs preliminary pressure equalization action during the stop period, maintaining pressure balance before restart. This preliminary action prevents excessive cooling by eliminating draft-induced heat loss, ensuring the system is thermally prepared for quick restart without requiring extended warm-up periods.
Solution Approach 2:
The system provides beforehand cushioning against temperature drop by using the reversible sucker to maintain pressure equilibrium and prevent draft during the stop period. This cushioning effect preserves residual heat and prevents temperature from falling below critical thresholds, enabling faster restart while maintaining safe operational parameters.
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 effectively reduces cooling and prevents corrosion, allowing for quicker restarts and minimizing draft through the system, even in the presence of leakages.
Implementation Method 1
equalizing the pressure at least through the gas turbine (2) by means of a reversible sucker (25)
Implementation Method 2
due to natural convection caused by the hot gas contained in the gas turbine and/or heat recovery steam generator and/or in the flue gas stack
Data Source
Figure 1~3
Figure 4~5
Figure 6~8
AI summary
The method for counteracting draft through an arrangement (1) including a gas turbine (2) during a stop comprises stopping the gas turbine (2) and then equalizing the pressure at least through the gas turbine (2).