Recuperated Gas Turbine Catalytic Combustor Start-Up
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Solution Overview
Problem
Catalytic combustion systems in gas turbines face challenges during start-up, producing higher emissions due to temperature dependence, and existing solutions are complex and inefficient, especially in recuperated gas turbines which require pre-burners to maintain catalyst temperature, compromising emissions performance.
Innovation Solution
An integrated catalytic combustor system with an upstream electrical resistance heater and downstream catalyst section, optimized for low-flow start-up and high-flow running conditions, respectively, allowing for efficient catalytic combustion initiation and sustained operation without additional ignition sources, reducing emissions and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a pre-burner is used to maintain catalyst temperature, then the catalyst can operate above light-off temperature, but emissions performance is compromised during start-up
Solution Approach 1:
The electrical heater performs preliminary heating of the catalyst during start-up to reach light-off temperature before full-load operation begins. This allows the catalyst to be prepared in advance for effective catalytic combustion, eliminating the need for continuous pre-burner operation and reducing emissions during the critical start-up phase.
Solution Approach 2:
The system uses the heat generated by the electrical heater during start-up to warm the catalyst, and once at operating temperature, the catalytic combustion process itself maintains the temperature. The electrical heater is only active during start-up, not during steady-state operation, making the system self-sustaining without continuous external heating.
2Reliability
If multiple ignition sources are used, then catalytic combustion can be initiated, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates unnecessary ignition sources from the system, retaining only the essential electrical heater for catalytic combustion initiation. By removing redundant ignition components, the system achieves reliable combustion startup while significantly reducing device complexity and maintenance requirements.
Solution Approach 2:
The electrical heater serves multiple functions: it heats the catalyst during start-up, maintains catalyst temperature during low-load operation, and can be used to warm the exhaust system. This multi-functionality reduces the need for separate ignition sources and heating devices, simplifying the overall system.
3Object-generated harmful factors
If the catalyst is heated electrically during start-up, then emissions are reduced, but energy consumption increases
Solution Approach 1:
The electrical heater operates periodically rather than continuously - only during start-up and low-load conditions when the catalyst temperature drops below the light-off threshold. During steady-state high-load operation, the catalytic combustion process maintains its own temperature without external heating, eliminating continuous energy consumption.
Solution Approach 2:
The system changes the operational parameters of the electrical heater based on load conditions and catalyst temperature. The heater is activated only when temperature falls below a threshold and deactivated when the threshold is reached, optimizing energy consumption while maintaining emissions control. This dynamic parameter adjustment ensures energy is used only when necessary for emissions reduction.
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
The system achieves near-zero NOx emissions and simplified design, reducing capital and maintenance costs by using electrical heating only during start-up and maintaining self-sustaining combustion, with the downstream catalyst section achieving ignition temperatures without external heating, thus lowering emissions and operational complexity.
Implementation Method 1
an upstream section and a downstream catalyst section, each containing pores or channels which allow for the passage of a gas or a vapor through both of the upstream section and the downstream catalyst section
Implementation Method 2
catalytic combustion systems in gas turbines face challenges during start-up, producing higher emissions due to temperature dependence
Data Source
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AI summary
The present disclosure is directed to a system comprising a recuperated gas turbine engine with a catalytic combustor, and methods of operating the same, the catalytic combustor comprising: (a) an upstream section comprising an electrical heater and (b) a downstream catalyst section, wherein the upstream section and the downstream catalyst section are disposed adjacent to and in fluid communication with one another.