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%.

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This paper describes the design and experimental evaluation of a radiometric instrumentation system that has recently been developed for the measurement of volumetric concentration, velocity and mass flow rate of pneumatically conveyed solids. The system employs `micro' beam collimation of gamma radiation to generate multiple, parallel interrogation beams of small cross-sectional area. This configuration is shown to almost eliminate the geometrical errors associated with more conventional divergent-beam interrogation. Experimental results obtained off-line using idealized flow models, and also on-line using a pneumatic conveyor, demonstrate the performance of the system and highlight where further development is needed.

Following investigations into the characteristics of radiation attenuation of pulverised fuel in pneumatic conveying systems, practical considerations in designing a radiometric meter for the measurement of solids volumetric concentration are presented. Measurement errors due to variations in moisture content and chemical composition are discussed.

The application of gamma -ray attenuation methods to non-intrusive measurement of the solids content in pneumatic flow lines is discussed. An instrument employing a broad single-beam interrogation geometry and a single-element detector with uniform sensitivity profile is described. It is designed primarily for metering pulverized coal, where the solids concentration is typically very low, and also often highly inhomogeneous. A detailed analysis of the factors affecting measurement accuracy is presented, together with results obtained from laboratory tests.