Theoretical and experimental studies of the spatial sensitivity of an electrostatic pulverised fuel meter

TLDR: In this paper, the authors present a theoretical analysis of the spatial sensitivity of the electrostatic meter with ring-shaped electrodes in the time and frequency domains, and the experimental data presented in this paper support the overall mathematic modeling, based on electrostatic field theory.

About: This article is published in Journal of Electrostatics.The article was published on 2005-10-01 and is currently open access. It has received 56 citations till now. The article focuses on the topics: Thermal mass flow meter & Flow measurement.

Figures

Fig. 7 Meter‟s Spatial Sensitivity in the Time Domain

Fig. 4 A “roping” Flow and Its Ring-Shaped Equivalent Stream stream

Fig. 2 Schematic of a Ring Shaped Electrode Fitted into Pneumatic Conveyor

Fig. 11 Meter‟s Power Spectral Characteristics Based on Theoretic Analysis

Frequently asked questions

Q1. What have the authors contributed in "Theoretical and experimental studies of the spatial sensitivity of an electrostatic pulverised fuel meter " ?

This paper presents a theoretical analysis of the spatial sensitivity of the electrostatic meter with ring-shaped electrodes in the time and frequency domains. One goal of the study is to improve its performance and to achieve uniform sensitivity. The experimental data presented in this paper support the overall mathematic modeling, based on electrostatic field theory, using the finite element method ( FEM ). Although the FEM analysis provides useful results, a more rigorous investigation is recommended for future work. 

Q2. What is the response of the ring-shaped electrode to a pulverised flow?

The response of the ring-shaped electrode to „roping‟ flow When pulverised flow, rather than a single point charge, is considered, the particle size and surface area must be taken into account. 

Q3. What is the hrd of the ring-shaped electrode?

The variable hrd(t) also represents the impulse response of the ring-shaped electrode to the mass flow rate of the solids, since it was assumed that the solids concentration is proportional to the net charge carried by solids at a given velocity. 

Q4. What is the purpose of the electrostatic pulverised fuel meter?

The electrostatic pulverised fuel meter described in this paper was designed to measure this fluctuation to indicate solids concentration and solids mass flow rate. 

Q5. What is the value of the random variations in the charges induced on the electrode?

The root mean square (rms) value of the random variations in the charges induced on the electrode is proportional to the variation in the net charges carried by flowing particles and is used as the indication of the solids concentration. 

Q6. What is the definition of a roping flow regime?

The so-called “roping” flow regime is an extreme example of inhomogeneous distribution where inside the “rope”, the highly concentrated solids flow is formed, as illustrated in Fig. 

Q7. What is the ring-shaped electrode's response to the net charge?

Assuming that the electronics are designed to detect charge variations on the electrode that correspond only to fluctuations in the net particle charge, the power spectral function of the meter output is as follows222 )()()( PNETrro QTU(18)222 )()()( PNETrro qTU(19)where )(PNETrQ is the frequency transfer function of the net charge of the roping stream of particles at radial position r , and )( P NETrq is the fluctuation in the net charge. 

Q8. What is the value of tvwrkrd r?

NETro r(17)The values of Rn and Cn of a given electrode depend on its geometry and the insulation between the pipe wall and the electrode. 

Q9. What is the ac coupled to the amplifier?

The electrode is insulated from the conducting conveyor wall but exposed to the flowing air-solid mixture and is ac coupled to an amplifier. 

Q10. What is the difference between the experimental results and the theoretical results?

The experimental results can therefore be compared to those predicted from Eqs. 19 and 21, because the net charge carried by the particles and its fluctuation level are assumed to be proportional to the solids concentration. 

Q11. What is the induced charge due to a ring-shaped flow?

They thus are expressed in the following equations as A(r,W) and k(r,W).Based on the principle of superposition of electrostatic fields and Eq. 10, the inducedcharge Qmic due to a hypothetical ring r* x of a micro volume within the sensing volume, shown at position (r,x) in Fig. 4, can be expressed as follows.