Friction Tube Feed Rate Controller for Granulated Materials
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Solution Overview
Problem
Feed rate control of granulated materials in suction grit blast applications is plagued by variability due to changing hopper loading and dust collector vacuum, leading to inconsistent flow rates and the need for frequent, arbitrary adjustments of orifice and suction settings, making it difficult to maintain process parameters and accommodate changes in pressure and flow rates.
Innovation Solution
A system comprising a material feed friction tube with a length-to-diameter ratio of at least four, an orifice for discharging material, and a pickup tube with a carrier gas source, which eliminates head pressure effects and allows for controlled flow rate adjustments without physical changes to the orifice, using a vibrator to assist powder fluidization and entry into the tube.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional orifice plate or suction pickup device is used for feed rate control, then the structure is simple, but the flow rate varies due to changing hopper loading and dust collector vacuum
Solution Approach 1:
A friction tube is introduced as an intermediary component between the hopper and the discharge point. This tube uses wall friction to dissipate head pressure variations, acting as a buffer that stabilizes the flow rate. The friction tube mediates between the variable hopper conditions and the required constant flow rate, eliminating the need for frequent adjustments of orifice and suction settings.
Solution Approach 2:
The system changes the physical parameters of the friction tube, specifically its length and diameter, to achieve the desired flow stabilization. By selecting appropriate dimensions (with length-to-diameter ratio L/D ≥ 4), the friction forces within the tube are optimized to dissipate head pressure variations, thereby maintaining consistent flow rate without modifying the orifice or suction device structure.
2Reliability
If the operator frequently adjusts orifice and suction settings to maintain constant flow rate, then the flow rate consistency improves, but the operation complexity and time consumption increase
Solution Approach 1:
The friction tube provides self-regulating flow control by automatically dissipating head pressure variations through wall friction. The system serves itself by using the inherent friction properties of the tube material and geometry to maintain constant flow rate, eliminating the need for operator intervention and frequent adjustments of orifice and suction settings.
3Quantity of substance
If the hopper is frequently stopped for reloading, then the material supply is maintained, but the productivity decreases
Solution Approach 1:
The friction tube is designed with sufficient length and appropriate diameter to maintain stable flow conditions even during transitions in hopper loading. This preliminary design consideration ensures that the system can accommodate reloading operations without significant disruption to flow rate, reducing the impact on productivity while maintaining material supply.
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 system ensures consistent feed rate control of granulated materials by dissipating hopper head pressure through friction and adjusting carrier gas pressure, maintaining flow stability even with varying hopper conditions, enabling smooth operation and efficient grit blasting.
Implementation Method 1
the head pressure on the material in the friction tube is dissipated by friction between particles and the walls of the friction tube
Implementation Method 2
a pickup tube positioned to receive material from the orifice and move the material using a source of carrier gas
Implementation Method 3
A vibrator near the bottom of the hopper can be used to help fluidize the powder and assist the powder in entry into the friction tube
Data Source
Figure 1
Figure 2
AI summary
The flow of granulated materials from a supply hopper (11) to a transport tube (12) is controlled. A material feed friction tube (13) is positioned to receive material from the hopper. The friction tube receives material independent from hopper pressure and the material moves to an orifice (18). The orifice discharges material to a pickup tube (33) from the orifice. The pickup tube has a source of carrier gas sufficient to move the material for further use.