Measurement of S and Na distribution in impregnated wood chips / fibers by X- ray fluorescence (XRF) to improve process efficiency of Pulp & Paper Industry
As there are increasing demands to replace plastics especially packaging material, there is an increasing demand also to improve the fundamental scientific understanding of pulp manufacturing. High yield pulping (HYP) processes, such as CTMP, are increasingly interesting for packaging material and hygiene paper. The yield from wood chips to final fiber is about 90%-98% and there lignin plays a key role. A key unit operation producing CTMP is the pre-treatment of wood chips before defibration. In order to separate the wood to individual fibers, minimum amount of electricity is necessary to soften the lignin by means of a combination of sulphonation at high pH and elevated temperatures. As the size of wood chips are varied in length, thickness and fiber size, it is challenging to create process technology that gives an even distribution across the wood chips of sodium sulphite containing liquid. In order to improve impregnation technology, it is valuable to measure the sulphonation degree on a detailed level. Our X-ray fluorescence imaging system using collimated X-Ray source and spectroscopic detector can make an image of sulphur and sodium across wood chips or in individual fibers. The procedure is that samples (chips and fiber material) with different properties can be taken at different times and controlled with micro X-ray technology while the sample is scanned to make an image of the content of the substances of interest. However, this methodology should possible to utilize in full-scale industrial systems to improve process efficiency and to find solutions of process problems.