Compressor Inlet Temperature Control via Eductor Mixing
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Solution Overview
Problem
Gas turbine systems face inefficiencies as the thermal efficiency decreases when the load on the turbine changes, particularly during turndown operations, due to mismatched changes in work output and inlet flow conditions.
Innovation Solution
A system utilizing turbine extraction gas (TEG) is introduced to control the temperature of the inlet flow to the compressor by mixing TEG with other gas flows within an eductor, allowing for precise temperature control of the intake flow, thereby optimizing the compressor inlet conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the turbine load decreases during operation, then the work output changes at a different rate than the inlet flow, but the thermal efficiency decreases
Solution Approach 1:
The system changes the temperature parameter of the inlet flow to the compressor by injecting heated gas (such as turbine extraction gas or exhaust gas) into the inlet stream. This parameter change allows the turbine to operate at lower loads while maintaining optimal inlet conditions for the compressor, thereby improving turndown capability without sacrificing thermal efficiency. The heated inlet flow compensates for the reduced work output by adjusting the density and flow characteristics of the air entering the compressor.
2Productivity
If the inlet flow temperature is not controlled, then the system operates simply, but the compressor inlet conditions are not optimized across varying load conditions
Solution Approach 1:
The system introduces an intermediary substance (heated gas from turbine extraction or exhaust) that acts as a mediator between the turbine output and the compressor inlet. This intermediary heated gas is injected into the inlet stream to adjust the temperature and density of the air entering the compressor, allowing optimization of compressor inlet conditions across varying load conditions without requiring complex active heating or cooling systems.
3Temperature
If turbine extraction gas is used to heat the inlet flow, then the inlet flow temperature is controlled, but additional system components are required
Solution Approach 1:
The system utilizes turbine extraction gas, which is already present in the gas turbine system as a byproduct of turbine operation, to heat the inlet flow. This self-service approach repurposes an existing resource within the system rather than requiring external heating equipment. The turbine extraction gas, which would otherwise be wasted or require separate handling, is redirected to the inlet stream to provide the necessary heating function, thereby achieving temperature control without adding significant external system complexity.
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 the turndown capability of the turbine by effectively controlling the inlet flow temperature, improving thermal efficiency and maintaining performance across varying load conditions.
Implementation Method 1
The first eductor includes a first motive inlet, a first suction inlet, and an outlet. The first motive inlet is configured to receive an extraction portion of combustion products as a turbine extraction gas (TEG) wherein the TEG is received through the turbine casing. The first suction inlet is configured to receive a suction flow with a suction pressure less than an extraction pressure of the TEG.
Implementation Method 2
mixing the TEG with a first suction flow within a first eductor to form a heated flow
Data Source
AI summary
A system includes a controller configured to control a heated flow discharged from an outlet of an eductor to an inlet control system to control a temperature of an intake flow through a compressor inlet of a compressor of a gas turbine system. The controller is configured to control a turbine extraction gas (TEG) flow to a motive inlet of the eductor. The controller is configured to control a suction flow to a suction inlet of the eductor. The TEG flow is extracted through a turbine casing, and the heated flow includes the TEG flow and the suction flow.