Controlled Particle Size Distribution for Pneumatic Conveyance of Sorbents
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Solution Overview
Problem
Pneumatic conveyance of small-sized particulate carbonaceous sorbent compositions, such as powdered activated carbon (PAC), experiences flow interruptions and pressure fluctuations, leading to potential mercury emission issues due to high concentrations of very fine particles.
Innovation Solution
A particulate sorbent composition with a controlled particle size distribution, where not more than 10 vol% of particles have a size of 5 μm or less, and a median particle size of 20 μm or less, is developed to enhance pneumatic conveyance properties by reducing the concentration of very fine particles through sizing or classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the average particle size of PAC is reduced to enhance contaminant capture efficiency, then the sorbent composition can remove smaller amounts of contaminants more effectively, but the pneumatic conveyance system experiences flow interruptions and pressure fluctuations
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters of PAC. Specifically, it limits the volume percentage of particles in certain size ranges (e.g., not more than 10 vol% with diameter ≤5 μm, not more than 20 vol% with diameter ≤10 μm) while maintaining a median particle size (D50) of 20 μm or less. This optimized parameter range resolves the contradiction by achieving both high contaminant capture efficiency and stable pneumatic conveyance.
2Measurement precision
If high concentration of very fine particles is present in small-sized PAC, then contaminant capture capability is enhanced, but flow interruptions and pressure spikes occur during pneumatic conveyance
Solution Approach 1:
The patent applies local quality by creating non-uniform particle size distribution with controlled concentrations of different particle sizes. Instead of using uniformly fine particles, it optimizes the distribution so that very fine particles (≤5 μm) constitute not more than 10 vol%, fine particles (≤10 μm) constitute not more than 20 vol%, while maintaining adequate fine particle content for contaminant capture. This localized optimization of particle size quality resolves the contradiction between contaminant removal effectiveness and reduction of flow interruptions.
3Measurement precision
If PAC with median particle size of 20 μm or less is used for improved contaminant capture, then the sorbent performance increases, but pneumatic conveyance requires precise particle size distribution control
Solution Approach 1:
The patent defines specific parameter ranges for particle size distribution that balance sorbent performance and manufacturability. The median particle size (D50) is set at 20 μm or less, with controlled volume percentages for different size ranges (≤5 μm: not more than 10 vol%, ≤10 μm: not more than 20 vol%). These parameter specifications provide clear manufacturing targets that achieve high sorbent performance while being feasible to control during production.
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 controlled particle size distribution improves pneumatic flow characteristics, including Basic Flow Energy, Specific Energy, and pressure drop, resulting in stable and efficient conveyance of the sorbent composition, reducing the likelihood of flow interruptions and mercury emissions.
Implementation Method 1
PAC is able to bind (e.g., adsorb) many contaminant species from another substance, thereby purifying (e.g., decontaminating) the other substance
Implementation Method 2
Pneumatic conveyance of PAC involves conveying the PAC through an enclosed pipeline using a pressure differential and the flow of a gas (e.g., air) to suspend and move the PAC along the pipeline
Data Source
AI summary
Sorbent compositions including sorbent particles of a small particle sized sorbent with increased pneumatic conveyance properties. The sorbent compositions have relatively small median particle size and have a controlled particle size distribution (PSD). Specifically, the sorbent compositions include a relatively small percentage of very fine particles, such as a small percentage of particles having a particle size of not greater than about 5 μm. The sorbent compositions are particularly useful for the treatment of a flue gas stream to remove mercury from the flue gas stream.