Exhaust Damper Backpressure Control for Gas Turbine Output
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Solution Overview
Problem
Gas turbine power plants face output restrictions due to mechanical and vibrational limitations of turbine rotor blades, particularly at high axial exit velocities, leading to reduced generator and thermal energy output.
Innovation Solution
The implementation of an exhaust damper system that increases backpressure at the turbine outlet, reducing axial exit velocity and allowing the gas turbine to operate above design limitations by controlling the exhaust damper's position based on selected operation modes, thereby increasing power and thermal energy production without exceeding mechanical limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gas turbine operates at high output levels, then electrical power generation and thermal energy output increase, but axial exit velocity of exhaust gas exceeds mechanical limits causing turbine rotor blade limitations
Solution Approach 1:
An exhaust damper is introduced as an intermediary component in the exhaust gas path. The damper creates backpressure that reduces axial exit velocity of exhaust gas, allowing the turbine to operate at higher output levels without exceeding rotor blade mechanical and vibrational limits. This mediator enables the system to achieve higher productivity while maintaining reliability.
Solution Approach 2:
The system changes the backpressure parameter in the exhaust gas path by adjusting the exhaust damper position. By increasing backpressure, the axial exit velocity is reduced, which allows the turbine to operate above its original design limitations while preventing rotor blade flutter and mechanical damage.
2Productivity
If the exhaust damper is closed to increase backpressure and reduce axial exit velocity, then turbine output restrictions are avoided, but exhaust backpressure increases
Solution Approach 1:
The exhaust damper is designed to be dynamically adjustable rather than fixed. The control system continuously adjusts the damper position based on operating conditions, allowing the system to optimize the balance between backpressure and axial exit velocity. This dynamic adjustment enables the turbine to operate at maximum output while maintaining acceptable backpressure levels.
Solution Approach 2:
A control system with feedback mechanisms monitors turbine operating parameters and adjusts the exhaust damper position accordingly. This feedback control ensures that backpressure is increased only to the extent necessary to reduce axial exit velocity to acceptable levels, preventing excessive backpressure while maximizing turbine output capacity.
3Productivity
If the gas turbine operates above design limitations to increase power output, then electrical power generation increases, but turbine rotor blade flutter occurs
Solution Approach 1:
The exhaust damper serves as a mediator that modifies exhaust gas flow characteristics. By creating controlled backpressure, it reduces axial exit velocity to levels that prevent rotor blade flutter, allowing the turbine to operate above original design limitations without experiencing harmful vibrations or mechanical damage.
Solution Approach 2:
The system applies preliminary anti-action by increasing backpressure before rotor blade flutter can occur. The control system detects approaching critical conditions and adjusts the exhaust damper to reduce axial exit velocity in advance, preventing flutter rather than responding to it after it begins.
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 increased electrical power generation during peak demands and enhanced steam production in cogeneration operations while preventing turbine rotor blade flutter, thus optimizing output without compromising component life.
Implementation Method 1
The exhaust damper increases backpressure at the turbine outlet and restricts axial exit velocity of the exhaust gas exiting the turbine outlet
Implementation Method 2
Thermal energy from the exhaust gas may be transferred to water flowing through one or more heat exchangers of the HRSG, thereby producing superheated steam
Data Source
AI summary
A system for controlling gas turbine output for a gas turbine power plant is disclosed herein. The power plant includes a gas turbine including a combustor downstream from a compressor, a turbine downstream from the combustor and an exhaust duct downstream from the outlet of the turbine. The exhaust duct receives exhaust gas from the turbine outlet. The system further includes an exhaust damper operably connected to a downstream end of the exhaust duct. The exhaust damper increases backpressure at the turbine outlet and restricts axial exit velocity of the exhaust gas exiting the turbine outlet when the exhaust damper is partially closed. A method for controlling gas turbine output is also provided herein.