Burner With Segmented Oxidant Inlets For Uniform Temperature
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Solution Overview
Problem
Burners for secondary reformers in ammonia plants face challenges in maintaining uniform gas temperatures and minimizing catalyst bed pressure drop due to high temperatures and material loss from refractory tiles, leading to increased pressure drop and potential plant shutdowns.
Innovation Solution
A burner design featuring multiple straight oxidant gas pipes with non-circular nozzles and two perforated plates to achieve plug flow and uniform temperature distribution, reducing pressure drop and material loss by optimizing gas mixing and flow path geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional burners are used in secondary reformers, then combustion of process gas can be achieved, but high temperatures cause material loss from refractory tiles and increased catalyst bed pressure drop
Solution Approach 1:
The oxidant gas inlet is divided into multiple separate inlet ends distributed around the burner tube, allowing oxidant gas to be introduced at multiple locations rather than a single point. This segmentation creates multiple combustion zones that are better distributed and mixed with process gas, reducing localized high temperatures and material loss from refractory tiles.
Solution Approach 2:
The burner design provides different flow characteristics at different locations around the burner tube. Each oxidant gas inlet end creates a localized flow pattern that contributes to overall uniform mixing. The swirler blades at each inlet end create localized swirling flows that enhance mixing in specific regions, ensuring uniform temperature distribution across the catalyst bed.
2Productivity
If high combustion intensity is achieved through swirling oxidant flow, then ammonia production increases, but temperature distribution becomes uneven causing higher material loss
Solution Approach 1:
Multiple oxidant gas inlet ends are distributed around the burner tube, creating multiple combustion zones instead of a single intense flame. This segmentation distributes the heat release more uniformly in space, improving temperature distribution uniformity while maintaining overall combustion intensity for high ammonia production.
Solution Approach 2:
The oxidant gas inlets are arranged in a circumferential pattern around the burner tube, adding a spatial dimension to the combustion process. This three-dimensional arrangement of multiple inlet ends creates a more uniform radial temperature distribution compared to a single central inlet, while maintaining high overall combustion intensity.
3Productivity
If oxidant gas flow rate is increased to maintain ammonia production, then compression energy costs increase, but reducing flow rate decreases productivity
Solution Approach 1:
The total oxidant gas flow is divided into multiple separate flows through the distributed inlet ends. This segmentation allows better distribution and mixing of oxidant with process gas, improving combustion efficiency. As a result, ammonia production is maintained or enhanced at lower total oxidant flow rates, reducing compression energy requirements.
Solution Approach 2:
The design replaces reliance on high mechanical pressure (achieved through high compression energy) with improved flow dynamics and mixing characteristics. The swirler blades and distributed inlet configuration create effective mixing and combustion at lower pressures, substituting mechanical energy input with hydrodynamic design features.
4Manufacturing precision
If multiple oxidant gas inlet ends are used, then temperature distribution uniformity improves, but device complexity increases
Solution Approach 1:
Each oxidant gas inlet end assembly serves multiple functions: it introduces oxidant gas, creates swirling flow through integrated swirler blades, and distributes flow radially. This multi-functionality allows the burner to achieve uniform temperature distribution without proportionally increasing complexity, as each component performs several roles simultaneously.
Solution Approach 2:
The swirler blades are nested within the oxidant gas inlet structure, with the blades positioned inside the inlet end housing. This nested arrangement integrates multiple flow control functions into a compact configuration, achieving uniform temperature distribution without adding significant external complexity to the burner structure.
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 design significantly reduces oxidant and process gas pressure drops, achieving uniform temperatures and minimizing material loss from refractory tiles, thereby increasing ammonia production and reducing compression energy costs.
Implementation Method 1
passing the oxidiser through a swirler installed at the burner face on the central tube. The stream of oxidiser is, thereby, given a swirling-flow, which provides a high degree of internal and external recirculation of combustion products and a high combustion intensity.
Implementation Method 2
The stream of oxidiser is, thereby, given a swirling-flow, which provides a high degree of internal and external recirculation of combustion products
Implementation Method 3
Burners for combustion of a reactant are mainly used for firing gas-fuelled industrial furnaces and process heaters, which require a stable flame with high combustion intensities.
Implementation Method 4
The very high temperatures in the secondary reformer cause the refractory tiles to slowly loose material by evaporation, and this material is later deposited by condensation in the catalyst bed below
Implementation Method 5
where the temperature is dropping due to the heat consuming steam reforming reaction taking place here
Data Source
Figure 1
Figure 2
AI summary
A burner with a plurality of oxidant gas pipes distributed throughout the cross section of the burner and process gas in plug flow provides even mixing of the oxidant and the process gas.