SYSTEMS AND MEANS FOR ELECTRICALLY HEATING TANKS ESPECIALLY THOSE CARRIED BY MOTOR VEHICLES, HEAT BEING DIFFUSED BY RADIATION

Abstract: System and means for electrically heating a tank (11) especially one carried on a vehicle (10) by cladding the tank (11) with concave panels (12), formed of a copper band whose thickness is measured in microns, held, with interposition of an insulating layer, between two metal sheets, said copper band being connected at its two ends by wires (25-28 and 32) to a drive unit (30) and to a generator (31) of electric current which, during its passage, is transformed into diffused heat that is transmitted to the mass of product contained in the tank (11).

Description: Systems and means for electrically heating tanks especially those carried by motor vehicles, heat being diffused by radiation The invention concerns systems and means for transporting liquids. In common use are vehicles such as tank trucks, tankers and tank wagons consisting respectively of road trucks or rail wagons that carry a tank for transporting liquids. A motor vehicle for this purpose generally consists of a truck, without a body, carrying a tank and its accessories that occupy the place of the truck's body. The tank and accessories comprise the tank itself, of an oval cross section with its longer axis laid horizontally, and of a base structure. The whole is fixed to the lateral frame members of the truck. A manhole permits access to the inside and is also used for loading. Tank trailers consist of a chassis complete with axles and of a tank with accessories as described above. In the case of rail wagons the tank may be fixed to the chassis or be moveable. In all cases it is nearly always necessary to keep the liquid in the tank at a substantially constant temperature, ranging between 20° and 250°, not¬ withstanding heat losses and irregularity caused by the greatly varying speeds at which the vehicle travels and any sudden changes in atmosphe- ric temperatures. Systems at present in use involve considerable problems of installation since their cost is high if they are to be really efficient and capable of temperature regulation requiring sophisticated, complex and delicate devices. Just because of these necessary characteristics, reliability over a period of time cannot always be guaranteed; this sometimes means serious damage and, if the product carried deteriorates, financial loss since the quantity is large and the product often expensive. The invention here described solves these serious drawbacks both as regards precise levels of temperature regulation and as regards installation and running costs. With this invention heat is provided by radiation with all the specific advantages such a system can offer. The phenomenon of radiation is one of the best known since it is the only means by which the sun transfers part of its thermal energy to our planet. The thermal energy thus accumulated in the ground is then used in various ways. Nearly ail the heating systems at present operated on a world scale, for which there must be universally compatible economic implementation, are based on gas, steam, solid and liquid fuels, with heat generators being mostly situated at a low level and the heat produced being transferred to the environment by convection. Use of electricity has mainly been restricted to lighting, electronics and telematics, it being generally considered too costly for heating purposes, even bearing in mind all the advantages of versatility and of a practical kind offered by electric heat generators. This is mainly due to the thermal delta between electric heating elements and the environment. According to the process used in this invention, electrical energy is transformed directly into diffused heat, transmitted in turn to the environment or to some mass to be heated. Subject of the invention are systems and means for electrically heating tanks, especially those carried on vehicles, by heat diffusion. The tank is clad with concave metal panels associated to a continuous two-dimensional electricity-conducting body whose thickness is measured in microns, of a constant section and having a very high ratio between extension and thickness, said body matching up against said metal panels. The ends of the continuous conductor are connected to a generator of electricity which, during its passage, is transformed into diffused heat this then being transmitted to the product contained in the tank. The continuous conducting body is laid on one metal sheet over which a second metal sheet is laid and fixed in place. The surfaces of said sheets matching with the conducting body are lined with a layer of electrically insulating material. The metal sheets are preferably of aluminium and the surfaces matching with the conducting body are anodized. The conducting body may be a band of copper. Electric current is supplied to the panels by a motor driven generator connected to an electronic control unit, in turn electrically connected to one and another of the panels. Each panel is fitted with a probe for measuring the temperature in the area around the liquid product where said probe is placed. At a drive unit where a suitable program has been put in, a microprocessor switches the various panels on and off separately one from another, or regulates the electric power in accordance with data supplied, from one moment to the next, by the probes concerned, according to the temperature that has been set for the product in the tank, making checks and taking specific action in various parts of the product, In one advantageous form of execution there are five panels, electric current for the panels is at 24 Volt while installed power is 5-8 kW. The tank concerned is carried on a tank truck, on a tanker, on a railway wagon or on a tank trailer or on any other transport vehicle as the case may be. The invention offers evident advantages. In all process concerning transfer of heat, the lower the thermal delta between the heating element and the required temperature for that particular heating purpose (environment, warm air etc.) the greater will efficiency be. Compared with conventional electric generators of heat (electric elements at extremely high temperatures with very small heat exchanging surfaces) where concentrated heat has to produce diffused heat, the invented system here described operates by transforming electric current directly into diffused heat, efficiency of the installation being extremely high. By means of the electric drive unit mounted on the vehicle the quanity of energy needed is calculated to one tenth of a degree, from one area to another in the tank containing the liquid product so as to keep the desired temperature constant, and this can be done throughout a possible range of temperature from 20° to 300°C. This is done by instant adaption to environmental temperature changes caused by climatic conditions and by movement of the vehicle. In addition installation and running costs are minimum, while reliability and versatility are maximum as is the guarantee against breakdowns and misfunctioning, due to simplicity of the installation, while maintenance costs are negligible. Characteristics and purposes of the invention will be made still clearer by the following examples of its execution illustrated by diagrammatically drawn figures. Fig. 1 Tank truck with the electric panels subject of the invention. Fig. 2 The same as Fig.1 with external insulation cladding. Fig. 3 Diagram to show electrical connections. Fig. 4 Detail of a panel. The tank truck 10 with tank 1 1 exhibits five concave electric panels 12 substantially the same; these clad the lower wall of the tank, semi-oval in section, with a short space between one panel and the next. The panels (Fig.3) are formed of a first concave sheet of aluminium 20 clad with an anodized layer 21 , on which is laid a thin intermediate copper body 22, whose thickness is measured in microns, and on which is laid a second concave sheet 24 of aluminium on whose matching surface is an anodized layer 23. Two opposite ends of the intermediate copper bodies 22 on the various panels are connected by a branch connection 25 and electric wire 26 to the electronic drive unit 30. Each panel carries a temperature probe 27 connected by an electric wire 28 to the drive unit 30. Therefore, the entire volume of liquid product contained in the tank is divided substantially into five zones each of which is kept under control by one of the above probes. Temperature values of the volume of liquid checked by each probe are sent from one moment to the next to the drive unit 30. In accordance with its program and to the temperature values sent to it, the drive unit switches single panels on and off, electrically connecting them to the motor driven generator of electric current 31 through the electric wiring 32 restoring the set optimum temperature values should such values be found to have varied or be about to vary due to dispersion which may take place at various points in the tank as a consequence of the speed at which the vehicle travels or to external climatic conditions. The drive unit is operated by a microprocessor able to calculate to one tenth of a degree the amount of energy needed, zone by zone, to maintain the temperature at the desired level. Fig. 2 shows a tank truck 15, substantially the same as that in Fig. 1 , the only difference being that it has a coating of insulation 40 on the outside.

Claims: Claims 1. System and means for diffused heating by electricity of a tank (1 1) especially one carried by a vehicle (10), characterized in that the tank (1 1) is clad with concave panels (12) of metal sheeting (20, 24) associated to a continuous two-dimensional electric conducting body (22) whose thickness is measured in microns and of a constant section having a very high ratio between extension and thickness, matching with said metal sheeting (20, 24), the ends of the continuous conducting body being connected to a generator (31) of electric current which, during its passage, is transformed into diffused heat transmitted to the mass of the product contained in the tank (11). 2. System and means as in claim 1 , characterized in that the continuous conducting body (22) is a band of copper. 3. System and means as in claim 1 , characterized in that the continuous conducting body (22) is laid on one metal sheet (20) over which a second metal sheet (24) is laid and fixed. 4. System and means as in claim 3, characterized in that the surfaces of the metal sheets (20, 24) matching with the continuous conducting body (22) are lined with a layer (21 , 23) of electrically insulating material. 5. System and means as in claim 3, characterized in that the metal sheets (20, 24) are of aluminium. 6. System and means as in claim 3, characterized in that the surfaces of the metal sheets (20, 24) that match with the conducting body (22) have an anodized layer (21 , 23). 7. System and means as in claim 1 , characterized in that electric current is supplied to the panels (12) from a motor driven generator (31) connected by wiring (32) to an electronic drive unit (30) in turn electrically connected by wiring (25-28) to one and another of the panels (12) and in that for each panel there is a probe (27) that measures the temperature in that part of the liquid product around said probe (27) so that a microprocessor in the drive unit (30) can, in execution of the program set, switch the panels (12) on or off, or adjust electric power separately for one panel or another according to data supplied from one moment to the next by the probes (27) concerned and according to the temperature it is desired to set or maintain in the product contained in the tank (11) making checks and taking specific action in the various zones of said product. 8. System and means as in claim 1 , characterized in that there are five panels (12). 9. System and means as in claim 1 , characterized in that the preferred voltage of electric current for the panels (12) is 24 Volt. 10. System and means as in claim 1 , characterized in that installed power is approximately 5-8 kW. 11. System and means as in claim 1 , characterized in that the tank (11) is that carried by a tank truck (10). 12. System and means as in claim 1 , characterized in that the tank is that carried on a tanker. 13. System and means as in claim 1 , characterized in that the tank is that carried by a rail wagon. 14. System and means as in claim 1 , characterized in that the tank is that carried by a tank trailer. 15. Means for putting into effect the system described in claims 1 to 14.

Inventors: STABILE ALDO, STABILE, ALDO
Applicants: CADIF SRL, STABILE ALDO, CADIF S.R.L., STABILE, ALDO
Application year: 1996
Main classification: B60P3
IPC codes: B60P3, B65D88