Investigation of Sensor for Measurement of Rotation Angle of Sensitive Element in Rotational Paper Pulp Consistometer

Abstract

This paper presents the results of theoretical and experimental testing of an optical rotation angle sensor of rotational paper pulp consistency meter. It is suggested that a specialized device consisting of two discs with the diameter as large as possible should be applied in the rotational consistency meters. There are holes in the disks. One more optocoupler should be applied for registering the beginning of the signal processing of separate measurements in order to reduce the root-mean square error. The measurement cycle of the sensitive element rotation angle is conducted within a predetermined number of full turns of the main shaft. The research results can be applied during development of the paper pulp rotation consistency meters based on the compensation of the viscous friction torque and based on the direct measurement of the viscous friction by defining the rotation angle of the sensitive element.Keywords: paper pulp consistency; measurement; rotation consistency meter; optical sensor; magneto-electric transducer. Definition of the scientific problem studied in the researchMeasurement of the paper pulp consistency on various stages of its preparation in tissue paper or cardboard manufacturing process can significantly influence the quality and the cost of production. Continuous control of the paper pulp consistency is usually performed by means of the mechanic method by defining the pulp viscosity [1,2]. There are two types of consistency meters that are based on this method: the rotational or mixer consistency meter, and the blade consistency meter. The rotational consistency meters can be of different design. However a common element for all of them is the device for measurement of the rotation angle of the sensitive element in relation to the rotation axe. During the improvement of such consistency meters and during development of new designs, it is important to increase the accuracy of measurement of the rotation angle for both rotation directions. This paper suggests a way of processing the signal from the optical sensor for the rotation angle measurement and discusses the obtained analytical ratios for processing of such signal. Analysis of the recent publications and research on the topicThe paper pulp is a non-Newtonian fluid. Its consistency can be measured indirectly based on the viscosity. Commercially produced rotational devices are based on various designs that include a device to determine a rotation angle of a sensitive element.