OVERHEATED STEAM GENERATOR Field of the invention

The present invention relates to a device for generating overheated steam. State of the art Devices adapted to generate overheated steam comprise, in general, two stages: a first stage provides the latent heat for the water to evaporate; a second stage further heats the steam overheating it.

The heat may be transferred to the water by means of various heat generators, e.g. fossil fuel or combustible oils and by-products, including gases. Other heaters use electric energy. A typical electric device for generating overheated steam includes a pipe about which an electric resistor is wound for a length such as to allow to transfer the heat necessary for the purpose. Such a device typology is particularly cumbersome and not very efficient due to the fact that a heat portion is transferred from the resistor to the environment instead of to the fluid.

Another overheated steam generator includes a first pipe through which the fluid flows, about which an electric winding is wound.

Said winding, crossed by the electric current, generates a magnetic field which is interconnected both with the fluid circulating in said first pipe and with the fluid circulating in a further pipe externally and spirally wound thereabout, despite being electrically insulated therefrom. In such a device, the fluid is heated by the energy transferred to the fluid from the interconnected magnetic flux. It is known that the magnetic induction is proportional to the number of turns and to the intensity of the circulating current, therefore in order to generate a sufficiently intense field, a winding made of a copper wire of large section and long length so as to form a great number of turns must be used. It is apparent that such a solution determines a high cost for making the winding and considerable dimensions, in addition to the fact that the performance is theoretically low because the frequency of the grid to which a similar generator is connected is normally 50 Hz, which is a frequency far away from the resonance frequency of the water pole molecule; at which frequency, again theoretically, the performance would be unitary. Summary of the invention

It is the object of the present invention to provide a overheated steam generator which is economically more advantageous to be made, while being characterized by a higher efficiency than the devices offered by the prior art. It is a further object to supply a particularly compact overheated steam generator. The present invention, therefore, intends to reach the afore-discussed objects by making a overheated steam generator, which according to claim 1 , includes:

- a rectilinear pipe segment;

- an electric resistor wound about said segment and supplied by an electric source; - a wound pipe segment, one end of which is connected to said first rectilinear segment, which is wound to form a cylindrical spiral which covers said electric resistor.

Advantageously, the device object of the present invention is much more compact and efficient than the known devices. It is compact because the thickness of the electric resistor is small; furthermore, it is very efficient because said electric resistor transfers heat inside the first segment of the pipe and outside the second segment which is wound thereabout.

Another advantage derives from the cost-effectiveness of the material which forms said electric resistor. According to a further aspect of the invention, said device is easy to be applied when generating overheated steam is needed, despite having a small available space and limited energy resources.

The dependent claims describe preferred embodiments of the invention.

Brief description of the drawings Further features and advantages of the present invention will be apparent in the light of the detailed description of a preferred, but not exclusive, embodiment of a overheated steam generator, illustrated by way of non-limitative example, with reference to the accompanying drawing, in which:

Fig. 1 shows an axial plane section of the steam generator according to the invention.

Detailed description of a preferred embodiment of the invention

A preferred embodiment of a overheated steam generator in accordance with the present invention includes:

- a rectilinear pipe segment 1 ;

- an electric resistor 3 wound about said segment and supplied by an electric source;

- a wound pipe segment 2, one end of which is connected to said first rectilinear segment, which is wound to form a cylindrical spiral which covers said electric resistor.

The fluid flow passes to the gaseous state, becoming wet steam, passing through said rectilinear segment and receiving, from said electric resistor, the heat which spreads inwards the cylindrical surface formed by the resistor. Subsequently, the fluid flow travels along said wound pipe segment which completely covers said electric resistor receiving the heat which is radially spread from the latter towards the external environment so as to become overheated steam. It is thus apparent that, before being able to reach the external environment, the heat must cross at least one further layer made of the pipe winding forming said wound segment, thus degrading.

In another preferred embodiment, the fluid flow is provided for crossing said device in the opposite direction as compared to what shown in the figure, so that the device externally has a temperature limited to the boiling temperature of the fluid itself, further increasing the performance of the device.

In another preferred embodiment, further layers of pipe winding 2 are provided for forming as many concentric tube bundles to further increase the performance of the device. In this manner, the external temperature of the device is almost that of the fluid entering the same, subsequently, as the fluid progressively flows through the increasingly more internal tube bundles of the pipe, the fluid gradually acquires more heat until the overheated steam stage is reached, until it is released from the rectilinear segment.

Preferably, the electric resistor 3 in a section view should take a complementary course with respect to the tube bundle which is overlapping the rectilinear pipe segment, instead of forming a cylindrical layer or a solenoid, so as to fill the gaps between said rectilinear segment and said wound segment. Specifically, said course is sinusoidal. The particular embodiments herein described do not limit the content of this

application which covers all the variants of the invention defined by the claims.