7th INTERNATIONAL CONFERENCE ON FERRITES

J. Phys. IV France 07 (1997) C1-531-C1-532
DOI: 10.1051/jp4:19971217

Ferric Substance Formed in Water Circulating in Boilers and Steam Piping, and an Apparatus for Magnetic Treating it

S. Ishibashi¹, T. Sato¹, M. Yokoyama², K. Haneda³ and Y. Kato<sup>4

1</sup>  Faculty of Engineering, Tokyo Engineering University, 1404-1 Katakura, Hachioji, Tokyo 192, Japan
²  Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama, Kanagawa 223, Japan
³  School of Science and Technology, Ishinomaki Senshu University, 1 Minamisakai Sinmito, Ishinomaki, Miyagi 986, Japan
⁴  NTT advanced Technology, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-01, Japan

Abstract
Substances in side the boilers and pipes become attached as scale or precipitate, and these badly effect the thermal efficiency of the steam. We made a detailed investigation, particularly on the ferrie substances which are present in boilers for heating buildings, generating steam at 100°C and boilers which supply 180°C steam to multistory buildings. In the case of heating buildings, 20% of these substances are made up of Fe₃O₄. The average particle size of Fe₃O₄ is 17~27 nm, and the saturation magnetization σs is 65~85 emu/g, by correcting the content of calcite and non-magnetic surface layer. The substances in boilers which supply multistory buildings contain ~98% of Fe₃O₄ and α-Fe₃O₄, whose average particle size is 105 and 160 nm, respectively. The σs of Fe₃O₄ was 79~92 emu/g, if we correct the content of the non-magnetic layer, and this value is almost the same as for the bulk material. In our present research we tried to attach a bypass in the pipe and set a magnet from outside, and the substances can be removed fiom the system while the boiler in still in operation.

© EDP Sciences 1997