Ammonia Combustor Three-Zone NOx Reduction
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Solution Overview
Problem
Traditional gas turbine combustors struggle to efficiently operate with alternate fuels like ammonia (NH3) due to issues such as slow or fast flame speed, inappropriate flame temperature, and unwanted combustion byproducts, which lead to high NOx emissions.
Innovation Solution
The method involves a combustor with a combustion chamber divided into three zones. In the first zone, a rich mixture of ammonia and oxidant is burned to produce NOx-containing combustion gases. In the second zone, additional oxidant is introduced to break down unburned ammonia into intermediates, consuming NOx. In the third zone, excess oxidant is used to burn hydrogen byproducts, minimizing NOx formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional combustor operating methods are used with ammonia fuel, then the combustor can operate on alternate fuel, but NOx emissions increase due to high flame temperature and slow flame speed
Solution Approach 1:
The combustion chamber is divided into three distinct zones: a first zone for initial combustion, a second zone for NOx consumption via ammonia intermediates, and a third zone for burning hydrogen byproducts. This spatial segmentation allows each zone to perform a specific function, collectively reducing NOx emissions while enabling ammonia fuel operation.
Solution Approach 2:
Ammonia intermediates serve as an intermediary substance that consumes NOx in the second zone. The unburned ammonia reacts with NOx to form nitrogen and water, effectively removing harmful NOx from the combustion products while allowing controlled combustion in the first zone.
2Object-generated harmful factors
If rich mixture is burned in the first zone to reduce NOx, then NOx production decreases, but complete combustion is not achieved and unburned ammonia remains
Solution Approach 1:
The combustion process is segmented across three zones: the first zone performs initial combustion with controlled richness to limit NOx formation, the second zone consumes remaining NOx and unburned ammonia, and the third zone completes combustion of hydrogen byproducts. This segmentation allows incomplete combustion in the first zone to be compensated by subsequent zones.
Solution Approach 2:
The combustion process continues sequentially through all three zones without interruption. Unburned ammonia and hydrogen from the first zone are carried to the second and third zones where the combustion and chemical reactions continue, ensuring complete utilization of the fuel while maintaining low NOx emissions throughout the process.
3Object-generated harmful factors
If additional oxidant is introduced in the second zone to consume NOx, then NOx reduction increases, but the mixture becomes lean and combustion temperature decreases
Solution Approach 1:
The combustion chamber is segmented into three zones with different oxidant-to-fuel ratios: the first zone uses a rich mixture for initial combustion, the second zone introduces additional oxidant specifically for NOx consumption, and the third zone provides excess oxidant for hydrogen burning. This segmentation allows the second zone to be lean without compromising overall combustion temperature.
Solution Approach 2:
Different local conditions are created in each zone: the first zone has a rich mixture for efficient combustion, the second zone has a lean mixture optimized for NOx consumption, and the third zone has excess oxidant for complete hydrogen oxidation. Each zone's local quality is optimized for its specific function while contributing to overall system performance.
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 effectively reduces NOx emissions by consuming them in the second zone and minimizing their formation in the third zone, while allowing the use of ammonia as a fuel in gas turbines.
Implementation Method 1
burning the rich mixture in the first zone. As a result, combustion gases containing nitrogen oxides (NOx) are produced
Implementation Method 2
delivering a second portion of oxidant into the second zone to break down unburned ammonia into ammonia intermediates in the second zone
Implementation Method 3
the nitrogen oxides (NOx) are consumed by reacting with the ammonia intermediates in the second zone
Implementation Method 4
burning the byproduct hydrogen in the third zone
Data Source
AI summary
A method includes delivering fuel and a first portion of oxidant as a rich mixture to the first zone of the combustion chamber. The fuel includes ammonia (NH3). The method further includes burning the rich mixture in the first zone. Combustion gases containing nitrogen oxides (NOx) are produced. The method further includes delivering a second portion of oxidant into the second zone to break down unburned ammonia into ammonia intermediates in the second zone. The nitrogen oxides (NOx) are consumed by reacting with the ammonia intermediates in the second zone. Byproduct hydrogen is produced as a result of breaking down the unburned ammonia into the ammonia intermediates. The method further includes delivering a third portion of oxidant into the third zone. The byproduct hydrogen is burned in the third zone. The third portion of oxidant is greater than the first portion of oxidant and the second portion of oxidant.