Acoustic Comb Filter Particle Trapping at High Flow Rates
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Solution Overview
Problem
Existing acoustic agglomeration techniques for particle trapping in flow streams are ineffective at high flow rates, as drag forces overcome retention forces, leading to incomplete filtering and low trapping efficiency for high-particulate slurry flows, and lack effective methods for particle size or distribution detection.
Innovation Solution
The use of a swept acoustic comb filter and sub-carrier modulated acoustic comb filter modules, which create quasi-standing waves by exciting the flow stream with two different frequencies, allowing for adjustable comb spacing and particle capture, and enabling particle size or distribution determination through off-stream analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single frequency acoustic standing wave is used to trap particles, then particles can be captured at nodes of the standing wave, but at high flow rates drag forces overcome retention forces and trapping efficiency decreases
Solution Approach 1:
The patent applies dynamics by transitioning from a static single-frequency standing wave to a dynamic swept-frequency acoustic field. The frequency is continuously varied over time, causing the acoustic comb nodes to move and sweep through the flow stream. This dynamic approach allows particles to be captured regardless of their position in the flow, maintaining trapping efficiency at high flow rates where static methods fail.
Solution Approach 2:
The patent changes the frequency parameter of the acoustic excitation over time. By sweeping the frequency across a range rather than maintaining a fixed frequency, the acoustic comb spacing and node positions change dynamically. This parameter change enables the system to adapt to different flow conditions and maintain effective particle capture across varying flow rates.
2Productivity
If flow rate is increased to improve productivity, then processing capacity increases, but drag forces increase and particles are swept forward without effective filtering
Solution Approach 1:
The dynamic swept-frequency approach creates moving acoustic comb nodes that actively sweep through the flow stream. This dynamic action allows the system to maintain filtering effectiveness at high processing capacities by continuously engaging particles regardless of their downstream position, preventing particles from being swept past the trapping zone without capture.
Solution Approach 2:
The frequency sweeping creates a continuous useful action where the acoustic comb nodes continuously move through the entire flow stream. This continuous sweeping action ensures that particles are captured throughout the duration of the sweep cycle, maintaining filtering effectiveness even as processing capacity increases and flow rates rise.
3Reliability
If acoustic standing wave is used for particle trapping, then particles can be captured and agglomerated, but there is no effective method for particle size or distribution detection
Solution Approach 1:
The patent applies universality by designing the acoustic system to perform multiple functions: both particle trapping/capture and particle size detection. The same acoustic comb filter structure that captures particles also serves as the detection mechanism by analyzing the radiated acoustic signals, eliminating the need for separate detection equipment and enabling size distribution analysis alongside filtering.
Solution Approach 2:
The system uses feedback by detecting acoustic signals radiated from captured particles and using this information to determine particle size and distribution. The acoustic signals provide feedback about the captured particles' characteristics, allowing the system to analyze size distribution while simultaneously performing the trapping function.
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
These techniques effectively capture and filter particles across a range of sizes, allowing for efficient particulate matter removal and accurate particle size distribution analysis, even at high flow rates, by adjusting the comb periodicity and detecting radiated acoustic signals.
Implementation Method 1
The retention forces depend on the peak acoustic pressure, the particle size, and the periodicity D
Implementation Method 2
a standing wave may be formed in the flow stream by ultrasonic excitation frequencies
Implementation Method 3
the other off the acoustic reflector
Implementation Method 4
drag forces will ultimately overcome the retention forces, and the particles will be released into the flow
Implementation Method 5
the agglomeration of particles will result in them either lifting out of the flow (buoyant), or dropping in the flow due to gravity
Implementation Method 6
dropping in the flow due to gravity
Implementation Method 7
create quasi-standing waves by exciting the flow stream with two different frequencies
Implementation Method 8
The periodicity, or comb spacing, D, of the nodes of the standing wave is a function of the frequency F
Data Source
AI summary
Apparatus features an acoustic comb filter module configured to receive signaling containing information about different frequencies F1 and F2 to create a selected comb spacing D to capture certain particles having a selected size X in a flow stream in a flow pipe, and to provide an acoustic standing wave via ultrasonic excitation based at least partly on the two different frequencies F1 and F2 to create the selected comb spacing D to capture the certain particles having the selected size X in the flow stream in the flow pipe. The apparatus may also include a particle size or distribution determination module configured to receive the certain particles for off-stream analysis via a detection port that forms part of the flow pipe and determine the particle size or distribution of the certain particles in the flow stream in the flow pipe.