Continuous measurement of particle concentration in gases comprises measuring fluctuations in concentration using two sensors arranged along its direction of flow whose signals are used to calculate cross-correlation function

摘要

The continuous measurement of the particle concentration in gases comprises measuring the fluctuations in concentration in a gas stream using at least two sensors arranged along its direction of flow. The signals x(t) and y(t) from adjacent sensors, between which the stream flows in a time delta t, form a temporally staggered statistic pattern and the particle concentration is calculated from the maximum value of the cross-correlation function: psi xy(tau ) = (1/2T) x(t).y(t - tau )dt, where delta t = tau . The limits of sigma are -T and +T. An independent claim is included for an apparatus for carrying out the above process, comprising at least two sensors (1, 2) positioned along a tube (4), through which the gas (3) flows. The signals from these pass through amplifiers (6, 7), low passes (8, 9) and a multiplex-ADU unit (10) to a microprocessor (11) which calculates the cross-correlation function and its Fourier transformation. The particle concentration and the speed of flow of the gas are calculated from these and are shown on a display (13).