Flue Gas Duct Silencer Plate Layout for Boiler Tonal Noise
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Solution Overview
Problem
Boilers produce tonal noise in the frequency range of 40 Hz to 100 Hz due to turbulence in the flue gas flow, which existing noise suppression methods, such as metal plates in the flue gas duct, fail to adequately address, and often complicate dust removal.
Innovation Solution
The implementation of noise-absorbing silencer plates placed downstream of heat exchanger pipes in the flue gas duct, oriented at an angle to each other, which effectively suppresses noise by reducing the resonating area and facilitating dust removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If metal plates are provided in the flue gas duct to suppress noise, then noise suppression is achieved, but dust removal becomes more difficult
Solution Approach 1:
The flue gas duct is divided into multiple sections with silencer plates positioned at specific locations downstream of heat exchanger pipes. This segmentation allows noise suppression in specific resonating areas while maintaining open pathways for dust removal in other sections.
Solution Approach 2:
Silencer plates are strategically positioned only in specific locations where resonating noise occurs downstream of heat exchanger pipes, rather than placing plates throughout the entire duct. This localized approach suppresses noise in problem areas while leaving dust removal pathways clear.
2Object-affected harmful factors
If silencer plates are placed upstream of heat exchanger pipes, then noise can be suppressed, but the plates are exposed to high temperatures
Solution Approach 1:
The flue gas flow is cooled by heat exchanger pipes before the silencer plates are encountered. This preliminary cooling action reduces the temperature exposure of the silencer plates while maintaining their noise suppression effectiveness.
Solution Approach 2:
Instead of placing silencer plates upstream before cooling (which would expose them to high temperatures), the plates are positioned downstream after the heat exchanger pipes have cooled the flue gas. This reverses the conventional approach and protects the plates from thermal damage.
3Object-affected harmful factors
If conventional plates are used in the flue gas duct, then noise suppression is attempted, but sufficient noise suppression is not achieved
Solution Approach 1:
The design parameters of silencer plates are optimized including their positioning downstream of heat exchanger pipes, their angular orientation relative to the flue gas flow, and their dimensions. These parameter changes create effective noise suppression by targeting specific resonating frequencies and patterns in the cooled flue gas.
Solution Approach 2:
The silencer plates are designed as composite structures combining noise-absorbing materials with heat-resistant properties. This composite approach ensures effective noise suppression while withstanding the thermal environment of the flue gas duct.
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 solution significantly reduces noise levels by limiting the resonating area, achieving noise suppression of up to 15 dB, while allowing for easier maintenance and dust removal, as the plates are positioned in a way that reduces exposure to high temperatures and does not obstruct the flow.
Implementation Method 1
noise-absorbing silencer plates placed downstream of heat exchanger pipes in the flue gas duct, oriented at an angle to each other, which effectively suppresses noise by reducing the resonating area
Data Source
AI summary
A boiler includes a flue gas duct and heat exchanger pipes in the flue gas duct. The boiler includes a planar silencer plate, which silencer plate includes sound absorbing material, and said first silencer plate being placed downstream of one of said heat exchanger pipes in the flow direction of flue gases in said flue gas duct. Furthermore, a silencer for a flue gas duct with a rectangular cross-section in a boiler, the silencer including at least a first and a second planar silencer plate substantially parallel to the flow direction of flue gases, the silencer plates including sound absorbing material. The first silencer plate is placed at an angle to the second silencer plate, wherein the width of the resonating area of the flue gas duct becomes narrower in two directions transverse to the flow direction of the flue gases.