Fluctuations in dense phase pneumatic conveying of pulverised coal measured using electrical capacitance tomography

A twin-plane electrical capacitance tomography (ECT) system has been employed to monitor the flow rate of fine coal transported by air in a 36.8 mm diameter pipe at mass fluxes of 1680 kg/m2 s. The mean mass flow rate was obtained to be within <1%<1% of the value determined from load cells. The ECT output indicated that there were two types of systematic fluctuations in the time series of mass flow rate and concentration. The frequencies of these have been obtained from power spectral density analyses. For the higher frequency fluctuations, the Strouhal number (fDt/ugs)(fDt/ugs) was found to depend on the square root of the solids/gas momentum flux ratio. An examination of the cross-sectional distribution of solids showed that the coal was concentrated around the wall of the pipe and that the concentration fluctuated as noted above.

[1]  Tomasz Dyakowski,et al.  Application of electrical capacitance tomography for measurement of gas-solids flow characteristics in a pneumatic conveying system , 2001 .

[2]  Derek Geldart,et al.  Dense phase conveying of fine coal at high total pressures , 1990 .

[3]  Stephen Pickering,et al.  Absolute measurement of pneumatically conveyed powder using a single long throat venturi , 2007 .

[4]  Sankaran Sundaresan,et al.  Electrical capacitance tomography measurements on vertical and inclined pneumatic conveying of granular solids , 2003 .

[5]  D. Geldart.  Types of gas fluidization , 1973 .

[6]  Tomasz Dyakowski,et al.  On-line monitoring of dense phase flow using real time dielectric imaging 1 The authors are members , 1999 .

[7]  Madhumita B. Ray,et al.  Pneumatic transport of granular materials through a 90° bend , 2004 .

[8]  H. V. Maanen.  Retrieval of turbulence and turbulence properties from randomly sampled laser-Doppler anemometry data with noise , 1999 .

[9]  Hubert Zangl,et al.  Signal modelling and algorithms for parameter estimation in pneumatic conveying , 2007 .

[10]  A Arko,et al.  Development of Electrical Capacitance Tomography for Solids Mass Flow Measurement and Control of Pneumatic Conveying Systems , 1999 .

[11]  Barry J. Azzopardi,et al.  Imaging stratifying liquid–liquid flow by capacitance tomography , 2007 .

[12]  K. Konrad,et al.  The gas—liquid analogy in horizontal dense-phase pneumatic conveying , 1984 .

[13]  H. V. D. Akker,et al.  Measurements on wave propagation and bubble and slug velocities in cocurrent upward two-phase flow , 1997 .

[14]  Shigeru Matsumoto,et al.  Statistical analysis of the transition of the flow pattern in vertical pneumatic conveying , 1987 .