Theoretica and expermental studies of cross conelation techniqJes appliea io non-resrrictive velocity measuement of pneumatically conveyed solids using ringshaped electrodynamic flow sensors are presentea. In-deptn studies of the electrodynamic sensing mechanism, and also of the spat al sensitivity and spatial filtering propenies of the sensor are incldded, together with heir relationships to measurement accuracy and the effects of solids' velocity prof:les. The experimental evaluation of a 53 mm bore sensing head is descr bed, ncluding tnals us.ng a calibrated pneumatic conveyor circLlat ng pulverized fuel and cement. Comparisons of test results with the mathematcal moaels of the sensor are used to identify important aspects of the instrLment design. OH-line test results obtained using gravity-fed solids flow show that the system repeatab lily :s w.thin -LO.S% over the velocity range of 2-4 m s-' for volumetric concentrations of solids no greater than 0.2%. Results obiained in the pilot-plant tr.als demonstrate that t h e system is capable 01 achieving repeatab.lity better than &2% and linearity wi1h.n 12% over the veloc.ty range 20-40 m s-' for volJmetric concentrations of solids in the range 0.01-0.44%.
Pneumatic conveying systems are widely used to convey powdered and granular solid materials in industry. However, as with all transport methods, there are advantages and disadvantages to this technique. Product degradation can occur when using pneumatic transport. It is desirable to be able to predict product degradation in real pneumatic conveying systems at the design stage. At the moment this is very difficult to do from a fundamental viewpoint, due to the large number of variables involved, many of which are difficult to quantify for most systems. An empirical approach has therefore been adopted involving the development of a pilot-sized test facility. The test programme incorporated a series of tests using malted barley, granulated sugar and rice. This enabled the measurement of product degradation over a range of superficial air velocities (9-38 m/s), suspension densities and pipe bend geometries to be made for each material. This paper will present experimental results obtained from the pilot-sized rig, indicating and discussing the effects of a number of variables on degradation.
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