A novel capacitive system for the concentration measurement of pneumatically conveyed pulverized fuel at power stations

Review of techniques for the mass flow rate measurement of pneumatically conveyed solids

“…1) with correlated double sample technique and a lock-in detector, was applied to offer the high and homogeneous capacitance sensitivity over the pipe cross section, as a result, making the concentration measurement of solids less affected by variations in flow regime. Simulation result showed that a homogeneous capacitance sensitivity over the pipe cross-section of as much as ±5% could be obtained using the electrode configuration mentioned above [6].…”

“…A number of researchers previously reported their work in this area [4][5]. Hu et al [6] proposed a novel capacitive system for the concentration measurement of gas-solid flow in pneumatically conveyed pulverized fuel at power stations. In his work, a specific configuration of the array capacitive sensor, called source-grid sensing electrodes (see Fig.…”

Concentration measurement with thermal probe for pulverized coal in the pneumatic pipeline of power plant

“…The other is the mass-dependent category in which the signals output from concentration sensors are primarily dependent on the change of solid/gas mass flow ratio. The capacitive method [3][4][5][6], electrostatic method [7], electromagnetic method [8], optical method [9], acoustic method [10,11] and radiometric method [6,12] are volume-dependent ones. The Coriolis method [13], pressure drop method [6,14], gravimetric method [15,16], and thermal method [17][18][19] belong to the mass-dependent category.…”

“…For example, the sensitivity of capacitance sensor is barely adequate for the dilute phase flows [1]. The low volume fraction of pulverized coal leads to minute capacitance changes in the case with very low solid/air mass flow ratio [4]. The major difficulty in concentration measurement with the capacitance measuring circuit is that the base line drift of the measuring circuit cannot be eliminated completely under dynamic conditions [5].…”

Fundamental research on the size and velocity measurements of coal powder by trajectory imaging

“…However, the major disadvantage of the probe is its disturbance to flow field. Non-contact sensor techniques have been used for measuring pulverized coal concentration, such as capacitor (Hu et al, 2006) and γ-ray attenuation methods (Yan et al, 1994). Among the techniques for particle velocity measurement, particle image velocimetry (PIV) (Raffel et al, 2001;Adrian and Westerweel, 2010) is capable of measuring the velocity distribution of a particle flow field in planar (2D) fields instantaneously and noninvasively, but the high price and complexity of the system restrict its application in online industry monitoring and measurement.…”