Three-Zone Combustion Air Supply for Solid Fuel Heater Adaptability
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Solution Overview
Problem
Existing solid fuel heaters, particularly firewood gasification boilers, face inefficiencies in combustion air supply adjustments for fuels with varying properties, such as moistened or large pieces, leading to suboptimal combustion quality and efficiency due to fixed air supply ratios.
Innovation Solution
A three-zone combustion air supply system with independent vents for lower and upper primary air and secondary air, featuring a single electric drive to control the air supply ratios through a moving orifice mechanism, allowing for flexible adjustment of air flow ratios to optimize combustion for different fuels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a common vent with fixed orifice ratio is used for lower and upper primary air supply, then the structure is simple, but the adaptability to different fuel types is poor
Solution Approach 1:
The common vent is divided into separate lower primary air vent and upper primary air vent, each with independently adjustable orifices. This segmentation allows the air supply ratio to be optimized for different fuel types (e.g., dry chips vs. wet logs) without changing the overall system structure, thus improving adaptability while maintaining reasonable complexity.
Solution Approach 2:
The orifices in both lower and upper primary air vents are made adjustable rather than fixed. This dynamic capability allows the air supply ratios to be changed according to different fuel properties, enabling the system to adapt to various fuel types including dry chips, wet logs, and standard firewood.
2Adaptability or versatility
If the upper primary air orifice ratio is increased for wet or large fuel pieces, then combustion quality improves, but the system becomes less suitable for dry and small fuel pieces
Solution Approach 1:
The upper primary air orifice is made adjustable, allowing the operator to increase the orifice ratio when burning wet or large fuel pieces to improve combustion quality, and decrease it when burning dry or small fuel pieces to maintain appropriate burning rates. This dynamic adjustment resolves the contradiction between combustion quality and productivity for different fuel types.
3Productivity
If the lower primary air supply is increased for high burning rate fuels, then output is improved, but combustion quality deteriorates
Solution Approach 1:
Both lower and upper primary air orifices are made independently adjustable, allowing the operator to optimize the air supply ratio for high burning rate fuels by increasing lower primary air while maintaining appropriate upper primary air supply. This ensures both high output and good combustion quality for fuels like dry chips and branches.
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 design enables efficient combustion of various fuels by allowing for optimal adjustment of air supply ratios, improving combustion quality and efficiency while reducing complexity and cost by using a single electric drive instead of two.
Implementation Method 1
Secondary air accomplishes combustion of inflammable gaseous elements of the flame - i.e., secondary combustion. Lower primary air accomplishes transformation of solid fuel into gaseous elements - i.e., primary combustion (or gasification) in the lower fuel layer.
Data Source
Figure 1~3
Figure 4~6
AI summary
The solid fuel heater with three-zone combustion air supply, containing the lower outlet orifice (16) of the lower primary air, the upper outlet orifice (11) of the upper primary air, the outlet orifice (12) and the inlet orifice (14.3) of the secondary air, whereas the secondary air between the inlet orifice (14.3) and the outlet orifice (12) runs in the independent vent (9); in addition, contains the first inlet orifice (14.1) of the lower primary and the second inlet orifice (14.2) of the upper primary air, whereas the lower primary air between the first inlet orifice (14.1) and the lower outlet orifice (16) runs in the independent vent (10) and the upper primary air between the second inlet orifice (14.2) and the upper outlet orifice (11) runs in the independent vent (3). The damper (13), attached to the arm (7), is assigned to each inlet orifice (14.1, 14.2 and 14.3), whereas the arm (7) is connected to the shaft (8), whereas the inlet orifices (14.1, 14.2 and 14.3) are equipped with their common moving orifice (5). The inlet orifices (14.1, 14.2 and 14.3) are located on the distributor (4), fixed to the external side of the heater (100), whereas the shaft (8) is located outside said distributor (4).