Multipoint Gas Turbine Injectors for Low Calorific Fuel Stability
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Solution Overview
Problem
Gas turbine engines face challenges with low calorific value fuels due to unpredictable flameout limits, high flow rates requiring large numbers of small injectors leading to pressure drops, and difficulties in start-up and flame stabilization, which affect thermal efficiency and ease of use.
Innovation Solution
A multipoint combustion system with a master injector and slave injectors, a primary manifold for distributing low-calorific value fuel, and an auxiliary manifold for separate fuel flow, including floating seals for thermal expansion accommodation and flexible installation, allowing for improved fuel staging and thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If large numbers of small injectors are used to handle high flow rates of LCV fuel, then the fuel can be distributed adequately, but pressure drop increases significantly
Solution Approach 1:
The fuel injection system is divided into multiple stages: a primary injection stage using a main injector for bulk fuel delivery, and a secondary injection stage using multiple auxiliary injectors for supplemental fuel delivery. This segmentation allows the system to handle high flow rates while distributing pressure more effectively across multiple injection points, reducing the pressure drop penalty associated with using only small injectors for the entire flow.
Solution Approach 2:
The system dynamically switches between primary and auxiliary injection modes based on operational requirements. The control system activates the auxiliary injectors only when additional fuel delivery is needed, allowing the system to optimize pressure characteristics for different operating conditions rather than being constrained by a fixed injection architecture.
2Quantity of substance
If high flow rates of LCV fuel are used, then adequate fuel supply is achieved, but flame stabilization becomes difficult
Solution Approach 1:
The fuel injection is segmented into a primary injection plume and multiple auxiliary injection plumes. The primary injector delivers the bulk of the fuel flow, while auxiliary injectors provide supplemental fuel at strategic locations. This segmentation creates multiple flame zones that are easier to stabilize individually while collectively handling high flow rates, as each zone can be optimized for flame attachment and combustion stability.
Solution Approach 2:
Air injection is introduced as an intermediary substance to facilitate flame stabilization. The system includes air injection nozzles that deliver oxidizer to the fuel plumes, creating a controlled combustion environment that stabilizes flames even at high fuel flow rates. This intermediary air flow acts as a mediator between the high-energy fuel injection and the combustion process, enabling stable operation.
3Ease of manufacture
If LCV fuel is supplied directly from gasification system at high temperature, then fuel delivery is simplified, but thermal management concerns arise
Solution Approach 1:
The thermal management system is segmented into multiple zones: a primary combustion zone, auxiliary combustion zones, and a heat recovery zone. The high-temperature fuel from gasification is introduced into the primary zone, while auxiliary zones provide controlled combustion at lower temperatures. This segmentation allows the system to handle the thermal load in manageable portions, reducing thermal shock and improving overall thermal efficiency.
Solution Approach 2:
The system changes the temperature parameter through staged combustion and heat recovery. By introducing fuel and air in multiple stages rather than a single high-temperature event, the combustion process generates heat more gradually. Additionally, heat recovery systems capture thermal energy from exhaust and return it to the combustion air or fuel preheating, effectively managing the thermal load and reducing peak temperatures that would otherwise cause thermal management problems.
4Adaptability or versatility
If conventional fuel injection systems are used with LCV fuel, then system compatibility is maintained, but start-up and flame stabilization are problematic
Solution Approach 1:
The injection system is segmented into a primary injector that handles bulk fuel delivery and multiple auxiliary injectors that provide supplemental fuel for start-up and flame stabilization. This segmentation allows the system to maintain compatibility with conventional LCV fuel delivery infrastructure while providing specialized functionality for difficult start-up conditions through the auxiliary injection stages.
Solution Approach 2:
The auxiliary injectors perform preliminary fuel delivery during start-up before the main combustion process is fully established. By pre-positioning fuel and creating initial flame zones through the auxiliary injectors, the system prepares the combustion environment for successful ignition and stabilization, overcoming the start-up difficulties inherent in LCV fuel combustion.
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 enhances start-up, flame stability, and thermal efficiency by providing a flexible and thermally isolated fuel distribution system that accommodates high flow rates and thermal differentials, improving overall performance with low-calorific value fuels.
Implementation Method 1
The auxiliary nozzles of the slave injectors can be mounted to the pressure vessel with floating seals to accommodate thermal expansion differentials between the pressure vessel and the auxiliary manifold
Data Source
AI summary
A multipoint combustion system for a gas turbine engine includes a housing defining a pressure vessel. A master injector is mounted to the housing for injecting fuel along a central axis. A plurality of slave injectors are each disposed outward of the master injector for injecting fuel and air in an ignition plume radially outward of fuel injected through the master injector. The master injector and slave injectors are configured and adapted so the injection plume of the master injector intersects with the ignition plumes of the slave injectors. A primary manifold is included within the pressure vessel for distributing fuel to the slave injectors. An auxiliary manifold is in fluid communication with the auxiliary nozzles of the slave injectors for issuing an auxiliary flow of fuel from the auxiliary nozzles that is separate from the fuel flow of the primary manifold.