Position: A novel cartridge powder feeder is developed by applying ‘subliminal fluidization’in the present work, , which is defined as partial aeration to the bed below minimum fluidization, but only for a limited region above the distributor, and by discharging solids together with the air through the tube located at the centre of the distributor. The distinct advantage of cartridge type feeder developed in this work lies in its simplicity of construction and operation giving quite an advantage for particulate material weighing or batching control, transportation and metric feeding.
Temporal solid efflux rates were measured for charcoal of mean sizes 220, 290 and 430μm, glass beads of 265, 535 and 930μm and spherical activated alumina (Neo beads) of 145 and 595μm and density in the range of 1250 to 2500kg/m3. Temporal flow rates of solids indicated that the solids efflux was independent of time and amount of material inside the bed and was only determined by the air supply from the distributor plate. Solids efflux rate was found to decrease with increased particle size and internal friction and reduced fluidization air flow rate. Solids efflux was found to vary slightly with the change in air humidity. A dimensionless correlation for solids efflux was developed as a function of fluidization number and the internal friction angle.
Graphical abstract of the powder feeder
In the present work, a novel cartridge type powder feeder is developed by applying ‘subliminal fluidization’, which is defined as partial aeration to the bed below minimum fluidization, but only for a limited region above the distributor, and by discharging solids together with the air through the tube located at the centre of the distributor. Temporal flow rates of solids indicated that the solids efflux was independent of material inside the bed and was only determined by the air supply from the distributor plate. Solids efflux rate was found to decrease with increased particle size and internal friction and reduced fluidization air flow rate. A dimensionless correlation for solids efflux was developed as a function of fluidization number and the internal friction angle represented by the following figure:
Powder Feeders to Satisfy the Most Sophisticated Requirements - Fine Arts
The CPF powder feeder achieves an evenness of up to 2% for a number of powders, exceeding the requirements for class A installations according to DIN 32 521. It is dust-protected and there are different models available for plasma, laser and HVOF coating.
The CPF powder feeder wheel operates independently of the powder column and measures the powder according to a volumetric feeding principle. The powder containers are easy to change and clean and may be equipped with a standard plus two optional feeder wheels.
Thermico’s CPF powder feeder is the result of our consistent R&D efforts to overcome the poor flow properties of micro-fine powders of <10μm, for which we have developed a vibration system that fluidizes the powder.
A weighing feeder wheel measures the powder into a carrier gas flow with a high precision rate, operating on a volumetric feeding principle. The construction principle allows powder measuring independent of the carrier gas flow via the rotary frequency of the feeder wheel. The carrier gas flow is mass flow-controlled with an accuracy of ±2% from the chosen flow values.
aDepartment of Chemical Engineering, Tokyo University of Agriculture & Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 1848588, Japan
