Gas Turbine Combustor Nozzle Air Injection
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Solution Overview
Problem
Carbonaceous deposits form on the surrounding surfaces of liquid fuel nozzles in gas turbine combustors due to thermal elongation of components, leading to airflow obstruction and degraded combustion performance.
Innovation Solution
The air supply nozzle is oriented to inject air towards the axis of the liquid fuel nozzle, creating a space around the outlet of the liquid fuel nozzle upstream of the injection direction, preventing carbon deposition by minimizing flow stagnation zones and promoting atomization of fuel droplets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the air supply nozzle is disposed to inject air toward the outlet of the liquid fuel nozzle, then the atomization spray of liquid fuel is improved, but thermal elongation of components causes carbonaceous deposits to form on surrounding surfaces of the nozzle outlet
Solution Approach 1:
The patent inverts the conventional air injection approach by directing air from the opposite direction (from downstream toward upstream) and by creating a space configuration that reverses the flow pattern. This inversion prevents the formation of flow stagnation zones where carbon deposits would otherwise accumulate, while still achieving effective atomization of the liquid fuel.
Solution Approach 2:
The patent introduces a spatial dimension by creating a specific space configuration around the nozzle outlet. By defining a space that extends in the upstream direction from the outlet, the patent adds a dimensional element to the flow control, allowing air to be injected in a direction that prevents deposit formation without compromising atomization quality.
2Device complexity
If components are disposed close together to maintain compact structure, then device complexity is reduced, but thermal elongation causes positional relationship changes leading to circulation flow and carbon deposition
Solution Approach 1:
The patent accounts for dynamic thermal elongation by designing a space configuration that remains effective despite dimensional changes. The space is defined in a way that accommodates thermal expansion and contraction, maintaining its functional relationship with the nozzle outlet across varying operating conditions and preventing carbon deposit formation regardless of component dimensional changes.
Solution Approach 2:
The patent addresses thermal parameter changes by designing a space whose dimensions and configuration are specifically related to the nozzle outlet in a way that compensates for thermal elongation. The space is configured to maintain its protective function across a range of temperatures and operating conditions, ensuring reliable prevention of carbon deposition.
3Object-affected harmful factors
If air injection direction is changed to prevent carbon deposits, then harmful factors are reduced, but fuel atomization and mixing may be affected
Solution Approach 1:
The patent segments the space into specific regions with different functions. The space is configured to provide a first region for preventing carbon deposit formation on the nozzle outlet surfaces, while simultaneously providing a second region that facilitates effective fuel-air mixing and atomization. This segmentation allows the air injection to achieve both protective and mixing functions.
Solution Approach 2:
The patent applies different flow characteristics to different local regions. The space configuration creates a protective flow pattern in the region near the nozzle outlet surfaces to prevent deposits, while maintaining appropriate flow conditions in the combustion region for effective atomization and mixing. Each region receives the appropriate flow quality for its specific function.
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 configuration effectively suppresses carbonaceous deposits on the liquid fuel nozzle surfaces, maintaining stable combustion performance across varying operating conditions and improving fuel atomization and ignition characteristics.
Implementation Method 1
air is injected from an air supply nozzle in a direction toward an axis of a liquid fuel nozzle... the airflow injected from the air supply nozzle has an effect of preventing droplets of the fuel injected through the outlet of the liquid fuel nozzle from being deposited on a nozzle end face
Implementation Method 2
because components of the liquid fuel nozzle and the air supply nozzle are susceptible to thermal elongations depending on operating conditions of the combustor, the positional relationship between the outlet of the liquid fuel nozzle and an injection hole of the air supply nozzle is not constant
Implementation Method 3
The liquid fuel having collided and deposited on the surrounding surfaces of the outlet of the liquid fuel nozzle while being carried with the circulation flow is carbonized and deposited as carbon (carbonaceous deposits)
Data Source
AI summary
A combustor comprises a liquid fuel nozzle for injecting liquid fuel to a combustion chamber, and an air supply nozzle disposed around the liquid fuel nozzle and injecting air. The air supply nozzle is disposed such that air is injected from the air supply nozzle in a direction toward an axis of the liquid fuel nozzle. A space is formed around an outlet of the liquid fuel nozzle, through which the liquid fuel is injected from the liquid fuel nozzle to the combustion chamber, upstream of a distal end of the outlet in a direction in which the liquid fuel is injected. Carbonaceous deposits on surrounding surfaces of the outlet of the liquid fuel nozzle can be suppressed regardless of the operating conditions of a combustor.