Cleaning and liquid contact with solids – Processes – Hollow work – internal surface treatment
Patent
1992-05-27
1994-01-18
Morris, Theodore
Cleaning and liquid contact with solids
Processes
Hollow work, internal surface treatment
134 2218, 134 24, 134 32, 134167R, 134168R, B08B 9093, B05B 306
Patent
active
052796752
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
This invention relates to a method of cleaning a storage or transport tank or similar receptacle by spraying a cleaning agent against the interior wall using at least one spray nozzle, said nozzle making a periodic rotating movement in a plane while said plane is simultaneously revolved around an axis which makes an angle with the axis of rotation of the nozzle, the point of impingement of the jet of cleaning agent delivered by the nozzle or each nozzle describing a track over the interior wall of the tank, said track passing a plurality of times an imaginary continuous circumferential line on the wall of the tank, which line is chosen as a reference.
Such a method, as for example disclosed in GB-A-1,241,547, has long been used and the invention aims to improve the known method in the sense that in a shorter time a greater fraction of the contaminations is removed from the tank wall.
BACKGROUND ART
Before the invention is described, some relevant technical concepts will be defined.
The movements of the nozzles of a tank washing machine can generally be described as a periodic rotating movement in a plane while that plane itself is revolved around an axis which makes an angle with the axis of rotation of the nozzle. As far as is known, in all known machines the two axes of rotation are mutually perpendicular. The machines in which the two rotating movements are uniform and rotate completely, are known as so-called "Butterworth" machines In other machines the rotating movement of the spray nozzles in the plane is not uniform and completely rotating but covers only a portion of the circle and can be described as a backward and forward movement. Examples thereof are the so-called "bottom washers" and some "single nozzle machines".
Although the aforementioned axes of rotation which define the movements of the nozzle can be disposed in any desired position in the space and the movements can be such that, if desired, any portion of the space or the entire space can be covered by the jets of cleaning agent, for the sake of simplicity reference will be made to a horizontal axis which nozzles rotate about uniformly and completely, and a vertical axis which the vertical plane of rotation of the nozzles revolves around uniformly. The respective rates of rotation are designated .OMEGA..sub.h and .OMEGA..sub.v.
Although, further, any drive of rotation can be used for rotating one or more nozzles around two or more axes, hereinafter reference will be made only to a (fixed) bevel gear with a vertical axis (number of teeth=N.sub.f), over which rolls, as a planet gear, a (moving) bevel gear with a horizontal axis (number of teeth N.sub.m). In the case where the transmission ratio between the two gear nozzle rotations is in actual fact effected by means of gears, the relation between "horizontal" and "vertical" rotation can be described as: time of revolution) of the movements for the vertical and the horizontal axis of rotation, respectively.
The trajectory of jet impingement of one nozzle in one revolution about the horizontal axis is called a track. The width of the area cleaned by the nozzle jet is dependent upon many factors, such as distance, angle of incidence, nature and adhesion of the material to be removed to the tank wall, etc.
Due to the simultaneous rotation of the nozzle around two axes, the beginning and the end of each track, to be defined as intersections of a closed circumferential line on the tank wall, chosen as a reference, will have shifted relatively to each other. The extent of the shift depends on T.sub.v / T.sub.h.
Depending on the number of nozzles N.sub.noz, after a number of shifts the washing pattern will have made one complete round along the closed reference line and the first subsequent intersection of a nozzle jet track will occur beyond the intersection that was the first to be defined. Then one subcycle has been completed. A full cycle has been completed when after a number of rounds N.sub.track the last intersection coincides with the first. When the
REFERENCES:
patent: 2681250 (1954-06-01), Metcalf et al.
patent: 3741808 (1973-06-01), Stalker
patent: 3874594 (1975-04-01), Hatley
patent: 3878857 (1975-04-01), Heibo
patent: 4859249 (1989-08-01), Valentini
Chaudhry Saeed T.
Michaelson Peter L.
Morris Theodore
Moser, Jr. Raymond R.
Technische Universiteit Delft
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