IMPROVING THE QUALITY OF MONITORING OF CIRCULATING AND WASTE WATERS OF PULP AND PAPER PRODUCTION

Abstract

The issue of operation of submersible vortex flowmeters used in the systems of monitoring of circulating and waste waters of pulp and paper production is considered.
 It is shown that in the event of an error in the installation of these instruments, an additional error appears due to the angle between the axis of the flow body (TO) of the flowmeter and the axis of the pipeline. This error is related to the measurement method, which in turn leads to a change in the Strouhal number (Sh). The influence of this error leads to a change in the geometry of the flow part of the submerged flowmeter (the appearance of the angle β), which in turn leads to a change in the vortex formation process.
 Variants of finding this error are considered, from which the method of numerical modeling of hydrodynamic processes with subsequent processing by the method of experiment planning was chosen. For each investigated velocity of the fiber suspension and the angle of deflection of the TO axis, a graph of the frequency spectrum of the vortex formation process was obtained. Which was later used to find the number Sh.
 The dependence of the installation error ΔSh,% is presented. in the form of a response surface. It is revealed that the error in the installation of the TO, which is estimated by the angle β, is relatively small and varies linearly with increasing β. If the angle β = ± 3 ° is accepted as an allowable value, then the error in measuring the flow rate of the suspension will not exceed 0.25% over the entire range of velocities under consideration.