Measuring non-dissolved gas content in a pulp flow using real-time 3D tomography

Villesamuli Normi Anssi Lehikoinen Arto Voutilainen Matti Saren Marko Vauhkonen

villesamuli.normi@uef.fi anssi.lehikoinen@numcore.com arto.voutilainen@uef.fi matti.saren@metso.com marko.vauhkonen@uef.fi

ABSTRACT

Measuring gas content of a pulp slurry flow has been a challenging task in pulp and paper industry. An appropriate measurement tool has been sought among various methodologies since 1950’s. In this paper we show that stationary ERT with relatively high frame rate can be deployed in real-time 3D monitoring of a pulp- flow process. The average gas holdup is calculated simultaneously from the 3D conductivity distribution and the variations of feeded air appear to be evident. In comparison to existing gas content meters, this novel technology offers a reliable way to monitor very small changes of the non-dissolved gas content of any regular pulp process. The initial laboratory scale tests indicate the ERT method can track the state of pulp slurry flow in reasonable accuracy, hence seeming to give more realistic control over the gas holdup distribution.

Keywords ERT; stationary inversion methods; imaging; gas holdup; multiphase flow; tomography