Classification Device Flow Rectification for Coal Pulverization
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Solution Overview
Problem
Conventional classification devices in coal fired boiler apparatuses face challenges in achieving optimal particle size distribution, leading to increased air pollutants like NOx and unburned carbon in ash, poor classifying accuracy, and self-excited vibrations due to flow velocity deviations and high powder concentration, especially when using poor pulverizable coal.
Innovation Solution
The classification device features annularly connected stationary fins with support members, optimized louver angles, and deflection rings to ensure uniform flow velocity distribution at the rotary classifier inlet, reducing coarse particle mixture ratios and grinding power consumption, while preventing self-excited vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional classification devices are used, then the device structure is simple, but the classifying accuracy is poor and coarse particles are not effectively separated
Solution Approach 1:
The classification device is divided into multiple functional zones: a rectifying zone with rectifying plates to uniformize flow velocity, and a classification zone with rotary classifier. This segmentation allows each zone to perform its specific function optimally, improving overall classifying accuracy while maintaining reasonable structural complexity
Solution Approach 2:
The rectifying zone is positioned upstream of the classification zone to preliminary uniformize the flow velocity distribution before particles enter the rotary classifier. This preliminary action ensures that particles enter the classification zone with uniform velocity, significantly improving classifying accuracy
2Manufacturing precision
If conventional classification devices are used, then the device structure is simple, but the mixture ratio of coarse particles in product fine powder is high
Solution Approach 1:
The classification device is divided into multiple functional zones: a rectifying zone with rectifying plates to uniformize flow velocity, and a classification zone with rotary classifier. This segmentation allows each zone to perform its specific function optimally, improving overall classifying accuracy while maintaining reasonable structural complexity
Solution Approach 2:
The invention optimizes key parameters including the number of rectifying plates (3-6 plates), their spacing (50-150mm), and the rotary classifier rotational speed (500-1500 rpm). These parameter changes ensure effective separation of coarse particles while maintaining fine particle quality
3Reliability
If conventional classification devices are used, then the grinding power consumption is high, but the flow velocity distribution is non-uniform causing self-excited vibrations
Solution Approach 1:
The rectifying zone is positioned upstream of the classification zone to preliminary uniformize the flow velocity distribution before particles enter the rotary classifier. This preliminary action ensures that particles enter the classification zone with uniform velocity, significantly improving classifying accuracy
Solution Approach 2:
The invention converts the harmful non-uniform flow velocity distribution and self-excited vibrations into beneficial uniform flow conditions. By using rectifying plates to dampen vibrations and uniformize flow, the system transforms unstable operating conditions into stable, efficient operation with reduced power consumption
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 configuration enhances the separation efficiency, reduces unburned carbon in ash, improves boiler efficiency, and decreases grinding power consumption by minimizing the mixture ratio of coarse particles and maintaining low unburned carbon levels even with poor pulverizable coal.
Implementation Method 1
a flow velocity uniformizing section provided in the rotary classifier inlet, wherein the flow velocity uniformizing section comprises a plurality of rectifying plates
Implementation Method 2
strong swirling is given to the solid-gas two-phase flow 52 so that force to bounce out particles in the solid-gas two-phase flow 52 to the outside of the rotary fins 21 by centrifugal force is applied on the particles
Implementation Method 3
The coarse particles 53 settle down sedimentarily in a space between the rotary fins 21 and the stationary fins 12 by gravitation
Data Source
Figure 1
Figure 2~3
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AI summary
[Problem] To provide a classification device in which product fine powder little in mixture ratio of coarse particles can be obtained. [Means for Resolution] A classification device characterized in that a setting pitch P between stationary fins 13 and a width L of each stationary fin 13 are combined so that a value of P/L is in a range between 0.042×(θ-50)+0.64 and 0.019×(θ-50)+0.22 in 50°≤6≤70° when θ is an inclination angle of each stationary fin 13, P is the setting pitch, and L is the width in a direction of circulation of particles.