This invention lies in the field of electrode humidifiers or “electrode boilers”, at the heart of which is the “boiler”, “bottle” or “steam tank”, the purpose of which is to supply steam to a space and which find many applications. For example, application to computer rooms (to control static electricity build up), operating theatres, offices, shops, product processing plant, holding containers, storage facilities, and other environments and for humans where health considerations apply. The invention also applies to any other equipment where scale is deposited on a process surface, for example industrial electrode boilers.
Electrode humidifiers may be both single phase and three phase with electrodes immersed in water and generally operate by controlling the level of water into which electrodes are partially or fully immersed in order to control the rate of steam production. A problem inherent in humidifiers is scale build up and other deposits of solids due to the boiling away as steam and a purging cycle is commonly resorted to. Periodic shut down and scraping and cleaning off of scale is generally required despite purging. Attempts at solving these problems have included chemical treatment, e.g. to convert sodium chloride ions to sodium sulphate, magnetic treatments of the water and electronic pulsing at selected frequencies. However, all of these efforts have not fully solved the problems mentioned above with resulting cost and inefficiency consequences.
The present invention provides an electrode humidifier characterized in that the electrodes are engaged by wiper means and a relative motion between the electrodes and the wiper means is continuously or continually applied during operation of the humidifier. The continuous action continues without interruption and the continual action is very frequent without cessation.
With the electrodes stationary and the wiper means moved, this simplifies the electrical connections to the electrodes which are located in the steam tank in which water is contained for production of steam.
The wiper means may further operate on other scale collecting surfaces.
The wiper means, which may be in the form of blades, are preferably moved in a rotational movement, as this allows them to be mounted on a shaft which can easily be driven rotationally. The electrodes are preferably in a form of a circular disc so that the wiper blades move rotationally over the whole electrode surface with a suitable rotational speed.
If it is the electrodes that are moved, they would again preferably be in a form of circular discs with the stationary wiper blades acting against them. The wiper blades are fixed on an insulating mounting between the electrodes.
A preferred general construction of a humidifier according to this preferred embodiment of the invention is a rectangular tank with electrodes depending from the roof of the tank, a horizontal shaft extending across the tank and carrying wiper blades arranged to wipe the operative surfaces of the electrodes, the shaft passing through the tank wall at one end to be driven by a suitable means, for example a suitably geared electric motor. A side water inlet, upper steam outlet and a bottom drain are provided. Two, three or four electrodes are provided for single phase electrical supply and four electrodes for three phase supply. A humidifier made with provision of four electrodes can conveniently be powered as a single phase device or a three phase device by arranging the electrical connections to the electrodes accordingly. It is found convenient to make at least part of the tank with transparent walls and/or roof to allow observing the operation and the conditions in the humidifier, as an optional feature.
The relative motion between the electrodes and the wiper means may in accordance with an alternative embodiment of the invention be continuously applied during operation of the humidifier by a linear actuator means. The linear actuator means must preferably provide an axial movement that oscillates back and forth.
The embodiment of the invention that uses reciprocating linear movement allows application to a steamer bottle which has a generally hollow upright cylindrical shape with linear electrodes depending from the top of the bottle.
The water level may be controlled to rise no higher than just below the shaft in order to avoid scale and other deposits building up on the shaft, however, although this was adopted in a prototype it will not be followed in further models.
It is found that continuously wiping the electrode surfaces removes deposits before they become hardened and strongly attached to the electrode surfaces, as occurs with present humidifiers.
An inlet, outlet and a bottom water drain are provided. Means to prevent back siphoning are preferably added and are mandatory in some jurisdictions. Three electrodes are provided for three phase electrical supply.
In accordance with another embodiment of the invention the electrodes are in a form of discs describing an arc of a circle and the wiper blades reciprocate angularly over the electrodes, in a motion much like a motor car windscreen wiper. This could be provided in a humidifier having the further characteristics described above with reference to the continuously rotating wiper blades.
The invention is more fully described byway of example with reference to the drawings, in which:—
As shown in
Having the electrodes stationary and the wiper means rotated simplifies the electrical connections to the electrodes as shown, the steam tank contains the water for production of steam and the water level 18 controlled, for example kept above the water inlet and below the shaft. A triac can be used to vary the voltage applied to the electrodes, the water level may be kept constant and may be a lot higher than shown in this example.
The wiper blades are made of selected material, for example silicon rubber, which endures the temperature in the tank and wipe the deposits continuously off the electrodes, which may be made of stainless steel, for example.
The humidifier has a rectangular tank having a base 19, sides 20, 21, 22 and 23 and a roof or lid 24, with the electrodes depending from the roof of the tank. The horizontal shaft extends across the tank carrying the wiper blades, the shaft passing through a sealed hole 25 that incorporates seals in the tank wall at one end to be driven by the suitably geared electric motor, the other end of the shaft may be journalled in a bracket inside the tank (not shown). The boiler tank can be made of transparent material, for example at least the roof of the tank is made with transparent material, e.g. polycarbonate to allow observing the operation and conditions in the humidifier.
These are the main features of the humidifier, shown in this simplified isometric drawing, it will be apparent to those skilled in this art that various dimensional and other modifications can be made within the scope of the invention.
As shown in
The tank has an outlet for steam, an inlet for water and a drain and other connections. The electrodes are connected to a three phase supply.
Having the electrodes stationary and the wiper means oscillated simplifies the electrical connections to the electrodes, the steam tank contains the water for production of steam.
The wiper blades are made of selected material, for example silicon rubber or a rather more abrasive material, which endures the temperature in the tank and wipes the deposits continuously off the electrodes, which may be made of stainless steel, for example.
Number | Date | Country | Kind |
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P2007/4597 | Jun 2007 | ZA | national |
P2007/7632 | Sep 2007 | ZA | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/ZA2008/000045 | 6/5/2008 | WO | 00 | 6/3/2010 |