Chihara, Kazuyuki

Nakagawa, Satoshi

Ogawa, Kuniyasu

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The Open-Access Journal for the Basic Principles of Diffusion Theory, Experiment and Application 2D Projective Imaging of Water Concentration Profiles in Adsorption Columns by MRI Satoshi Nakagawa1, Kazuyuki Chihara2, Kuniyasu Ogawa3 1 Dept. of Development, Ikiken Corporation, Japan 2 Dept. of Applied Chemistry, Meiji University, Japan 3 Dept. of Mechanical Engineering, Keio University, Japan Corresponding author: Kazuyuki Chihara Dept. of Applied Chemistry Meiji University 1-1-1 Higashi-mita, Tama-ku, Kawasaki, Kanagawa, 214-8571 Japan E-Mail: chihara@isc.meiji.ac.jp 1. Introduction Magnetic resonance imaging (MRI) that accepted in the medical field widely is recently applied to various industry uses as well. As for the study of the diffusion, the MRI technique was reported to be able to be used to observe chromatographic profiles of water in an adsorption column [1]. But it is more useful to acquire two-dimensional images to observe the profiles precisely because actual columns have some thickness. So we tried to obtain 2D images of the transient profile of water in the adsorption columns filled with zeolite by using a compact MRI device which has 1 T permanent magnet. 2. Experimental Adsorption columns made of acrylic pipes (2.6 cm inside diam. x 10 cm length) were packed with Li-X zeolite particles. And humidified nitrogen (about 80 %RH) was fed from the bottom end of the columns at the flow rate of 2 L/min or 5 L/min. Each profile was obtained as a projective image to a plane without slicing by spin-echo method [2]. It took 8 min 40 sec to acquire an image in this study, so that the images were obtained while nitrogen feeding was suspended temporarily. 3. Results and Discussion Figure 1 shows the 2D projection images of water concentration profiles in adsorption columns. Each graph shows area of about 4cm square from the bottom end of adsorbent bed in the columns. As shown in the figure 1, the humid area progressed through the bed, and we can see that the progress speed of the humid area near the wall was faster than that of the humid area near the central axis of the beds like a meniscus shape. The tendency was more obvious at the feed rate of 5 L/min than 2 L/min. Such behaviour was thought to be caused by the lower density of filling of adsorbent near the inner wall of the column, and influenced by the balance of the flow rate, the strength of adsorption, and axial and radial diffusion in the adsorption bed. So we are trying to analyze the detailed © 2011, Kazuyuki Chihara diffusion-fundamentals.org 16 (2011) 42, pp 1-21brought to you by COREView metadata, citation and similar papers at core.ac.ukprovided by Qucosa - Publikationsserver der Universität Leipzig Fig. 1: 2D projection images of water concentration profiles in adsorption columns. (a-1), (a-2), (a-3) show the profiles at 10 min, 40 min, 60 min from start of feeding nitrogen at the flow rate of 2 L/min, and graph (b-1), (b-2), (b-3) shows the profiles at 3 min, 23 min, 33 min at the flow rate of 5 L/min respectively. The adsorbent bed of zeolite extends from the end on the upper left of each graph toward the bottom right (between two dotted lines showed in (a-1)). The third axes of these 3D graphs indicate values in proportion to the MRI signal intensity. mechanism by several approaches including simulations of adsorption using Stop & Go method [3]. 4. Conclusion 2D projection images of the transient profile of water in adsorption columns filled with zeolite were obtained by using a compact MRI. And the differences in the progress speed of the humid areas which were caused by the difference in the condition of flow rate or radial location, were observed from the images. These results suggest that MRI is useful for the detailed analysis of the moisture absorption in adsorption columns. References [1] Nils-Karsten Bär, Bruce J. Balcom, and Douglas M. Ruthven, Ind. Eng. Chem. Res., 2002, 41 (9), pp 2320-2329. [2] K. Ogawa, J. Heat Transfer Society of Japan, Vol. 47, No. 200 (2008) 27-39. [3] S. Nakagawa, T. Ouchi, T. Ohara, and K. Chihara, Proc. of the 7th International Conference on Separation Science and Technology, AD123, (2005). © 2011, Kazuyuki Chihara diffusion-fundamentals.org 16 (2011) 42, pp 1-22

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2D Projective imaging of water concentration profiles in adsorption columns by MRI

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2D Projective imaging of water concentration profiles in adsorption columns by MRI

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