LU83072A1 - COMBINED ELECTRIC BOILER - Google Patents

Description

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The invention relates to a combined electric boiler.

It has been observed, as a result of technological and economic developments, that the use of electrical energy for heating or steam production, instead of traditional fuels, justifies more often than before.

On the other hand, if the price of traditional fuels is fixed, regardless of when it is used, the price of electric current often varies according to the hour of use.

Depending on the time of day, one fuel may be more advantageous than the other, and vice versa.

The object of the invention is to be able to use either one or the other energy source on existing boilers.

The problem thus posed is solved according to the invention by the addition, to an existing boiler, with any heat transfer fluid, of an autonomous group, generator of thermal energy from electrical energy. The electric heating elements can, by simply reversing a control member, be put into service in place of the existing burners, and vice versa.

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The invention makes use of an electric boiler with electrodes, known per se, whose particular characteristics avoid the major drawbacks of conventional electrode boilers, namely variations in the conductivity of water, fouling of the electrodes and the cost. power regulation by transistors or others. Indeed, the invention encloses the electrodes in a closed circuit whose water is not renewed and the regulation is done by variation of the surface of embedded electrodes.

The great advantage of the invention is to use an existing boiler with all its equipment, and that it applies to any type of boiler, whatever the heat transfer fluid used.

The invention will be described below on several examples of embodiments, with the aid of the accompanying drawings in which: - Figure 1 is a cross-sectional view of a steam boiler and an autonomous group thermal energy generator; - Figure 2 is a side elevational view ·> of the assembly of Figure 1, with longitudinal section of the autonomous group; - Figure 3 is a view similar to that of Figure 1, comprising a main boiler of different type; - Figure A is a cross section similar to that of Figure 1, of an installation comprising a circulation pump;

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- Figure 5 is a sectional view of an installation comprising a main boiler with forced circulation; and - Figure 6 is an application of the invention to a hot air generator.

In Figure 1, there is shown by 3 a conventional steam boiler to which thermal energy is normally supplied by a liquid fuel burner, 4. This boiler is supplemented, according to the invention, by an autonomous generator group thermal energy from electrical energy. This group includes a steam generator 2, the electrodes of which are designated by 1, and a heat exchanger 5, mounted in a closed circuit. The heat exchanger 5 has a first circuit (10,11) closing on the electrode generator 2, and a second circuit (6,8,9 'in heat exchange relation with the first circuit and which closes on the main boiler 3, the tube 9 being connected to the boiler balloon, and the tu1 8 at a lower point thereof. The steam generator 2 consists of an envelope from the upper part from which the tube leaves 10 and in the lower part of which the tube 11 penetrates, these tubes 10 and 11 being connected on the other hand to the casing of the exchanger 5. The electrodes 1 belong to a circuit of alternating current comprising three phases and one The casing 2 is connected to the ground and a perforated cage 14, which separates the electrodes from the cess of the casing 2, acts as a neutral point. The cage can also be connected to an independent ground. sees that electrical protection can be provided 4.

of the system by placing a leakage current detector between the phases plus neutral and earth. Guant with the liquid which bathes the electrodes, it is made up in principle of industrial distilled water to which one added a suitable additive to obtain the conductivity necessary for the passage of the current, taking into account the tension which one has.

The heat exchanger 5 has a casing

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î terminated by a head 7 divided by a partition 7 ’into] two parts to which the tubes 9 and 8 respectively connect, which connect the autonomous group to the; boiler 3. The two parts of the head 7 are connected ί \ to the respective ends of a bundle of tubes made of ^ hairpin, 6. These tubes 6, the head 7 and the tubes \ I 8.9 constitute the second circuit of the exchanger, while 5.

It is immediately understood that the steam generator 2 supplies thermal energy to the boiler 3 via the exchanger 5.

It is observed that closing the valve 12 does not prevent condensation in the shell of the exchanger; when the valve is closed, there is a pressure drop, which causes the water contained in the steam generator 2 to be drawn into the envelope for 5 days.

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water level falling, the electrodes are dry and the flow of electric current is stopped. A modulating action of the valve 12 causes a corresponding variation in the consumption of electricity.

The water contained in the closed circuit of the autonomous group does not undergo any change in conductivity. As the conductivity decreases with temperature and that this is inevitably lower during start-up than in service, and that »on the other hand, the regulation is modulating, the starting power is about 25% of maximum power and no other peak consumption is to be feared.

The electrical switching is limited to a simple switch, with no other regulating device than, if desired, a progressive start-up of the $ 25 representing the start-up load.

When using electrical energy, the burner h alone of the boiler 3 is put out of service "all the other parts and accessories of the boiler! continuing to play their normal dream. When using; / sation of the energy of the burner, we put the boiler

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.... _ electric shutdown. The simultaneous use of two. ·; 4 energies can be considered. It will naturally be limited by the characteristics of the boiler.

ij While FIGS. 1 and 2 show the installation according to the invention applied to a boiler with a smoke tube as well, FIG. 3 represents the application of the invention to a boiler with water tubes at a ball.

| The description that has been made so far. ! refers to a steam boiler, but can be-. >. - view the application of the invention to a boiler with any heat transfer fluid such as oil, air, molten salt, etc. In this case, the tubes 6 are traversed 4 * \ by the fluid to be heated and circulation is possible

Iment assisted by a pump 15 placed on the tube 6 between the boiler and the exchanger, as shown in Figure 4.

In this case also, the boiler can be of the type with forced circulation fluid tubes, as shown in FIG. 5 where circulation pumps feel. designated by 15 and 15 '.

; FIG. 6 shows the application of the invention to a hot air generator 16. In this case, one of the possible solutions is to condense the steam produced I in the envelope 2 by means of a heat exchanger 5 ' with finned tubes 17 placed in the air outlet of the hot air generator. The vapor then condenses in the tubes and returns by gravity to the envelope 2.

Claims (7)

1, - Combined electric boiler, characterized in that it comprises, supplying heat to a boiler = main (3) with any heat transfer fluid, an autonomous group (2,5) generating thermal energy from electrical energy . at 2. Combined electric boiler according to | claim 1, characterized in that the group auto-. · | nome thermal energy generator includes a general • •? steam generator (2) with electrodes (1) and a heat exchanger · -; I heat (5) mounted in a closed circuit, the exchanger of *! heat (5) comprising a first circuit (10,11) which closes on the electrode generator (2), and a se- .7 | cond circuit (6,8,9) in relation to heat exchange î î | with the first circuit and yes closes on the boiler 3 3 | main (3). 3. Combined electric boiler according to one S | any one of the preceding claims, characterized in that the first circuit (10,11) of the exchanger of ']; ·' ifr | heat (5) of the autonomous group (2,5) contains a modulating valve (12) regulating the power of the generator (2) of said group, controlled by an operating factor (temperature or pressure) of the main boiler (3). 4.- Combined electric boiler according to any one of the preceding claims, characterized · -..- =. / In that the steam generator (2) of the autonomous group:; ££ i; v (2,5) electrodes which are drowned more or - ·. ·: <? ' , less according to the level of the liquid to be vaporized, this level; - · ** '·. / ‘•“ N 8. varying according to the degree of opening of the roodula-trice valve (12). 5. -Combined electric boiler according to any one of the preceding claims, characterized in that the second circuit (6,8,9) of the exchanger (5) of the autonomous group (2,5) contains a pump (15) . : ... i7¾ 6. Combined electric boiler according to any one of the preceding claims, characterized in that the main boiler is a boiler with forced circulation fluid tubes. 7. -Combined electric boiler according to claim 1, wherein the main boiler is a hot air generator comprising a heat exchanger (5 '), characterized in that it comprises at its outlet tubes (17) inserted directly in the pasture- . mid er circuit (10,11) of the generator (2) of the autonomous group, the air circuit which surrounds the tubes (17) serving as the second circuit of the exchanger (51). ! r