Electric heating – Microwave heating – Waveguide applicator
Patent
1999-07-28
2000-12-05
Leung, Philip H.
Electric heating
Microwave heating
Waveguide applicator
219695, 219748, 219762, 219746, 219679, 588900, 422186, H05B 672, H05B 680
Patent
active
061570133
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
The invention pertains to a micro-wave applicator and method for the surface scarification of contaminated concrete.
The dismantling of used nuclear installations involves the destruction of the contaminated equipment and in particular its breaking up into pieces which are then put into drums of bitumen that are stored in specialized installations. Concrete walls that must be subjected to this breaking up treatment pose a particular problem however because of their thickness: since the contamination is absorbed into the surface layers of the concrete, the heart of the concrete remains clean and no special treatment can be justified for it.
The interest in not excessively increasing the volume of material to be stored has lead the industry to separate the contaminated layer from the remainder of the concrete walls by techniques called "crust removal" techniques and which consist of carrying out surface scarification of the concrete walls which leaves the clean heart of the concrete in place but detaches the contaminated layer. A number of purely mechanical tools have been used to do this such as bush hammers, pneumatic picks and pressurized water jets as well as the application of micro-waves. This new technique makes use of the presence of water in the concrete, which is heated by the micro-waves so that it boils and explodes within the solid material. This produces the desired scarification.
The correct implementation of the method rests however on suitably choosing certain parameters such as the power of the micro-waves, their frequency their area of application and their direction. In an apparatus described in the article "Microwave system for the removal of concrete surface layers" by P. Corleto and co-workers and published by the Italian Agency for New Technologies for Energy and the Environment (ENEA), several high power magnetrons were used to emit micro-waves spread out over a large surface area. Hence a large volume of concrete was heated all the more since the micro-waves, whose frequency was relatively low at 2450 MHz in the equipment proposed, penetrated more deeply into the concrete. This apparatus appears to be effective, but one may suppose that other ways of proceeding would also be suitable, ways which allow one to remove the crust from the same area of concrete while using much less power so as to prevent the divergence of the microwaves which leads to a reduction in the power per unit volume deposited in the concrete and eventually to decreased efficiency of the method. This invention has been designed to take account of these considerations and its essential characteristic consists in that the microwaves are focused onto a more or less limited or more or less slender area, within which the heating is concentrated, and which determines the depth of the crust removed once the focusing area has been stabilized.
The known equipment for removing the concrete crust have an appliance that includes a head through which the microwaves leave a waveguide. This application head, placed on the concrete wall or positioned at a small distance from it, must therefore be designed to create the desired focus. Although the focusing of waves does not appear to have been proposed in the technique we are concerned with, it is known that appliances have been developed for medical purposes to focus microwaves and to create localized hyperthermia in the body of a patient, for example to destroy a tumor at the focal point. Three different pieces of equipment are described in the articles "A Direct Contact Microwave Lens Applicator with a Microcomputer Controlled Heating System for Local Hyperthermia" by Nikawa and others (IEEE Transactions on Microwave Theory and Techniques, Vol. MTT-34, No. 5, May 1986), "An Electric Field Converging Applicator with Heating Pattern Controller for Microwave Hyperthermia" again by Nikawa and others (same source) and "Microwave Applicator using Two Slots on Sphere" by Krairiksh and others, published by IEEE and presented at the Asia-Pacific Microwave Conference at Ade
REFERENCES:
patent: 3102181 (1963-08-01), Verstraten
patent: 5003144 (1991-03-01), Lindroth et al.
patent: 5283010 (1994-02-01), Waring
patent: 5449889 (1995-09-01), Samardzija
patent: 5877395 (1999-03-01), Emery
patent: 6013330 (2000-01-01), Lutz
Casagrande Benoit
Furtlehner Jean Pierre
Commissariat a l''Energie Atomique
Leung Philip H.
LandOfFree
Microwave applicator and method for the surface scarification of does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Microwave applicator and method for the surface scarification of, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Microwave applicator and method for the surface scarification of will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-963456