Journal of Electrostatics, 28 (1992) 47-59 Elsevier 47 Golay coded electrostatic sensor arrays for cross- correlation flow measurement W. Balachandran,D.C. Heale and W.J. Szajnowski Department ofElectronic& Electrical Engineering,University ofSurrey,GuildfordGU2 5XH, Surrey, UK (Received September 30, 1991;accepted December 14, 1991 ) Summary Simulations have been carried out to determine suitable sensor arrangements for use in cross- correlation flow measurement of pulverized coal using electrostatic sensors. A system using com- plementary Golay codes allows the sidelobes on the correlation function to be cancelled out while leaving the shape of the cross-correlation function the same as for an uncoded sensor with the same electrode size while increasing the signal level and hence the signal to noise ratio. Limited experiments have been carried out in this arrangement which indicate that it is suitable for veloc- ity measurement and can probably identify the presence of ropes. 1. Introduction In the electricity industry the optimization of boiler performance for reduced emission, reduced furnace slagging and corrosion and maximized combustion efficiency is dependent on the equal distribution of pulverized coal and air flow to each burner of a multi-burner unit. One of the most important parameters is the mass flow rate of pulverized coal (PC). Flow variation between burner lines may be severe and also less consistent than is typically assumed. The measurement of flow variation is a necessary first step in order to develop on- line control of flow. It is, therefore desirable to develop a reliable PC flow con- trol device to achieve the required control. The advantages of a two-phase flow meter can be expressed in both engineering and economic terms. The current practice of limiting excess air for PC-fired units is set to compensate for any imbalance in the fuel distribution to the burners and the resulting need to correct for the variations in the fuel/air ratios. A more balanced fuel/air dis- tribution to the burners would allow a reduction in the current excess air level while still resulting in improved combustion efficiency, reduced unburned combustibles, reduced slagging and wall tube wastage and potentially reduced pollutant emissions. Cross- correlation measurement appears to be an attractive means of meas- 0304-3886/92/$05.00 © 1992 Elsevier Science Publishers B.V. All rights reserved.