Variable Port Area Burner for Turndown Ratio
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Solution Overview
Problem
Conventional fuel burners are limited in their ability to operate effectively over a wide range of Btu inputs, leading to issues such as flame lifting and overheating due to the fixed relationship between port velocity and flame speed, which affects combustion quality and efficiency.
Innovation Solution
A fuel burner design that includes a movable blocking member within a fluid directing structure, allowing the adjustment of the port area through which the air-fuel mixture flows, enabling control of the flow area to optimize combustion based on varying Btu demands by selectively blocking portions of the fluid directing structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the port area is increased to handle higher Btu inputs, then the combustion capacity increases, but the flame speed increases causing flame lifting and poor combustion
Solution Approach 1:
The burner employs a movable blocking member that can dynamically adjust the port area in response to varying combustion conditions. This allows the system to adapt the effective flow area to match the required combustion capacity, preventing flame lifting while maintaining proper combustion quality across different Btu inputs.
Solution Approach 2:
The invention changes the geometric parameter of the port area by moving the blocking member to different positions. This parameter adjustment allows the port area to be varied continuously, enabling the burner to operate reliably across a wide range of Btu inputs while maintaining optimal combustion characteristics.
2Power
If the port area is decreased to handle lower Btu inputs, then the combustion capacity is reduced, but the flame speed decreases causing overheating of the burner
Solution Approach 1:
The movable blocking member enables dynamic adjustment of the port area to match the required combustion capacity. When operating at lower Btu inputs, the blocking member can be positioned to reduce the port area, which increases the velocity of the gas/air mixture and prevents flame lifting, while also controlling the temperature to prevent overheating.
Solution Approach 2:
By changing the port area parameter through blocking member movement, the system can optimize the velocity of the gas/air mixture for different combustion capacities. This parameter change allows the burner to maintain proper combustion characteristics across a wide range of Btu inputs while preventing overheating at lower power levels.
3Device complexity
If a fixed port area is used, then the burner structure is simple, but the burner cannot operate properly over a wide range of Btu inputs
Solution Approach 1:
The burner incorporates a movable blocking member that can adjust the port area in response to varying Btu inputs. This dynamic adjustment capability allows the simple burner structure to adapt to a wide range of combustion capacities, achieving high turndown ratio without requiring a complex multi-port or adjustable multiple nozzles system.
Solution Approach 2:
The invention uses a single blocking member that can be positioned to change the effective port area parameter. This simple parameter change mechanism enables the burner to operate properly over a wide range of Btu inputs, achieving versatility without adding significant structural complexity.
Data Source
AI summary
A fuel burner includes a tube extending from a first end to a second end and including a central passage and fluid directing structure for directing a mixture of air and combustible fuel radially through the tube. The fluid directing structure collectively defines a total flow area. A blocking member is axially movable within the central passage between a first condition blocking a first percentage of the total flow area and a second condition blocking a second percentage of the total flow area different from the first percentage to control the flow of the mixture of air and combustible fuel through the fluid directing structure from the first end to the second end of the tube to be ignited.