A capacitance-based solids concentration transducer with high immunity to interference from the electrostatic charge generated in solids/air two-component flows

Abstract

Electrostatic charge generated in solids/air two-component flows can cause significant errors in solids-concentration measurement systems based on capacitance techniques, and, in the worst case, can overload or even damage the measuring circuits. A transformer ratio-arm bridge capacitance transducer, incorporating synchronous demodulation and a noise attenuating input amplifier, has been developed for this type of application. The transducer has been tested on several solids-flow plants. It shows a very high immunity to charge interference and it is capable of withstanding large magnitudes of electrostatic interference without being overloaded.

Keywords

Solids flow capacitance measurement.

Get full access to this article

View all access options for this article.

References

Beck, M.S. and Hobson, J.H. 1970. 'Electrostatic charge measurement of particulate materials being transported at high velocities - explosion risk meter for pneumatic conveyors', IEE CP(67), 38-41.

Beck, M.S. and Plaskowski, A.B. 1987. Cross-correlation flow meters - their design and application, Adam Hilger, Bristol.

Blair, D.P. and Sydenham, P.H. 1975. 'Phase sensitive detection as a means to recover signals buried in noise', J Phys E Sci Instrum, 8, 621 - 627.

Hammer, E.A. and Green, R.G. 1983. The spatial filtering effect of the capacitance transducer electrodes', J Phys E Sci Instrum, 16, 438-443.

Huang, S.M. 1986. Capacitance transducers for concentration measurement in multicomponent flow processes, PhD Thesis, Manchester University, England.

Irons, G.A. and Chang, J.S. 1983. 'Particle fraction and velocity measurement in gas-powder streams by capacitance transducers', Int J Multiphase Flow , 9 (3), 289-297.

Schneider, G. , Bernard, W. and Mesch, F. 1982. 'Capacitance sensors for solids flow measurement by correlation methods', ACTA IMEKO, 2, 187-193.