ITAN20090023A1 - HEAT RECOVERY SYSTEM - Google Patents

Description

â € œHEAT RECOVERY APPARATUSâ €

SUMMARY

Object of the present invention is a heat generator (3) for the production of thermal energy connected by means of a conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) to one or more sources of heat (2). Said conveyor (4) receives the hot gasses (FI, F2) emitted by said one or more heat sources (2) sent to said heat generator (3) for the recovery of their enthalpy content.

DESCRIPTION OF THE INVENTION

The present invention refers to a solution for the recovery of the thermal energy possessed by the fumes and exhaust gases of thermal machines and by the cooling and ventilation air of the same and / or of their organs and auxiliary circuits or of other machinery .

More particularly, the present invention relates to heat generators adapted to act as heat recuperators.

More particularly, these heat generators are smoke tube. The present invention is particularly useful for the construction of electrical and thermal energy cogeneration plants, in particular in the field of micro-cogeneration.

The principle of cogeneration (also called â € œcombined productionâ €) is essentially based on the exploitation of the residual heat that occurs in thermoelectric generators at the end of the phase in which electricity is produced; this â € œresiduousâ € energy content can therefore be used as a heat source for space heating or for productive and industrial uses.

Micro-cogeneration is of great interest in the civil-tertiary sector and small industry, which requires relatively low power to achieve an extremely widespread local production of electricity.

However, micro-cogeneration has not yet found a wide diffusion because it is more difficult for small-sized machinery to meet the minimum requirements of cost per unit of power, yield, reliability and efficiency.

Consequently, the cogeneration systems commonly used up to now have sizes that basically start from 100 - 300 kW to reach several MW.

For micro-cogeneration, the market essentially proposes two different solutions, based on the same concept of energy generation, but which however involve the use of a different prime mover.

In particular, to cover the size from 50 to 100 kW they can be used as prime mover gas micro-turbines, while for smaller sizes the cogeneration apparatus provides for the use of reciprocating internal combustion engines, both with Diesel cycle configuration. which, preferably, in the Otto cycle.

The thermal energy due to the operation of a prime mover (internal combustion engine or gas microturbine) is partly dispersed in the external environment by radiation (in quantity, however, effectively contained) but most of it is transferred to combustion gases (whose temperatures can vary, in fact, from 350 to 600 ° C) discharged to the chimney and to the cooling air of various components of the engine and its auxiliary circuits.

Generally, heat is not recovered from the cooling air substantially due to its low enthalpy content and convective heat exchange coefficient which would in fact entail the need to use exchangers with large exchanging superims; said exchangers would therefore be particularly expensive with reference to the overall cost of the cogenerator and the benefits that can be obtained. Only rarely and generally in alternative endothermic engines, said cooling air is advantageously recovered to produce hot water,

On the other hand, devices are already provided for recovering heat from the exhaust fumes of the prime mover despite their not particularly high enthalpy content and, above all, the risk of acid condensation during their cooling.

Said devices, as known, are generally located downstream of the prime mover and can be exchangers (also known as recuperators) which exploit the heat of the combustion fumes discharged to preheat, for example, the combustion air, or alternatively the recovery boilers for their further combustion or for simple cooling through heat exchangers used, preferably for the production of hot water or steam or superheated water.

By way of example, please refer to document GB 2 271 171 where the exhausted hot gases, generated by one or more alternative heat sources, are cooled over the entire exchanging surface of a heat exchanger of a heat generator (in this case, a flue gas boiler) or to US 4 313 399 where, if sufficiently rich in oxygen, they are used as a comburent inside the combustion chamber of a heat generator.

Said devices for recovering the enthalpy content from the combustion gases and fumes discharged from the prime mover, however, have the main drawback of being strongly integrated with the same.

Consequently, therefore, it is obvious how the malfunction of either the prime mover or the recovery device can compromise the overall efficiency of the cogeneration system set up. At the same time, separate maintenance either on the engine or on the recovery device is very difficult and generally requires the shutdown of the one that is still functioning correctly.

Regulating organs are then necessary so that the recovered thermal energy is distributed at the temperature required by the user.

Ultimately, these recovery devices are relatively expensive compared to the benefit provided (recovery of the thermal losses of the prime mover).

Finally, it is not so easy to convey the thermal energy thus recovered to the possible users of the same.

If it is difficult, as mentioned, to reuse the enthalpy content of the cooling air of a prime mover and its auxiliary circuits, it is even more difficult to recover it from the most varied heat sources of an industrial plant such as the cooling systems of a fleet of machines for molding plastic material or hot air coming out of industrial painting plants, or combustion films generated and discharged by old-concept and inefficient industrial furnaces and boilers.

It is obvious that, even in these cases, the main obstacle to energy recovery are the costs, which are relatively high compared to the benefit of the recovery, since special exchangers and energy transport systems are required for each source. thermal.

A first object of the present invention is to indicate methods of heat recovery which are simple and economical to implement in relation to the thermal and electrical powers involved.

A second purpose of the present invention is to indicate methods of heat recovery with reduced polluting emissions and with reduced environmental impact.

Another object of the present invention is to indicate highly flexible heat recovery methods in terms of thermal power to be recovered.

Another object of the present invention is to indicate highly flexible heat recovery methods in terms of quantity and type of machines from which heat is recovered.

Another object of the present invention is to indicate ways of integrating heat recovery and production systems with machines for the production of electrical and / or mechanical energy.

Another object of the present invention is to indicate suitable means and methods for the integration of a prime mover to a flue gas boiler with great flexibility in terms of electrical power to be integrated.

Further objects and results of the present invention will be better highlighted by the following description of a preferred embodiment, according to the patent claims and illustrated, purely by way of non-limiting example, in the attached drawing tables, in which:

figure 1 shows a schematic view of a heat generator according to the prior art;

Figure 2 shows a block diagram of a heat recovery apparatus according to the invention;

- figures 4a, 4b, 4c show three lateral and front sectional views of the apparatus schematized in figure 2, with particular reference to the heat generator, according to a first variant of the invention, figures 5a and 5b show two views in side and front section of the apparatus schematized in figure 2, with particular reference to the heat generator, according to a further variant of the invention; figure 5c shows a detail of the variant of figs. 5a and 5b. With reference to fig. 2, 1 indicates, as a whole, the heat recovery apparatus, object of the invention, which includes one or more generic heat sources 2 and a heat generator 3.

Such generic heat sources 2, as mentioned, can consist of mechanical or electrical energy generators such as internal combustion engines, gas microturbines, steam turbines, fuel cells or more simple heat sources such as, for example, heat generators of low efficiency, from whose fumes it is still possible to extract thermal energy, or even simpler devices such as cooling batteries of machinery such as machines for molding or extrusion of plastic materials.

During their operation, said heat sources 2 emit heat substantially only through hot gasses consisting of combustion gas F1 and / or cooling air and ventilation F2 heated by the cooling of various equipment.

Example of heat sources 2 can be:

internal combustion engines, gas micro-turbines, which emit heat both through combustion gas FI and cooling air and ventilation F2 of the auxiliary organs,

- low-efficiency heat generators that emit heat via FI flue gas,

cooling coils that emit heat via cooling air and ventilation F2.

The hot gasses FI and F2 emitted by each of said heat sources 2 are often too small and / or too low in temperature so that it is possible and / or economical to recover their thermal energy by means of individual recovery devices.

Figures 1 and 2 of the heat generator 3 schematically indicate the combustion chamber (or hearth) 31, the heat exchanger 32 and the chimney 36.

According to the invention, the enthalpy content of the hot gasses FI and F2 leaving the heat source 2 is recovered in said generator 3.

More precisely, the combustion gases FI, which have a sufficiently high temperature, are sent to release heat in the exchanger 32 while the cooling air F2 is used in the same generator 3 as combustion air to the furnace 31.

Special situations are not excluded in which there is cooling air F2 similar to the combustion gas FI because it is hot enough to be sent to the exchangers 32 or vice versa, combustion gas FI to be assimilated to the cooling air F2 because it is so cold (or rich in oxygen) to be introduced into the firebox 31 together with the combustion air, if they do not disturb the oxygen combustion.

The heat generator 3 is preferably a generator for the production of steam and / or hot water and / or diathermic oil, and, in particular, it is a film tube boiler (see Figure 1).

The technology and operation at the base of the smoke tube boilers 3 (hereinafter referred to as boiler for simplicity) has been known for some time and a brief description is sufficient.

With reference to the exemplary figure 1 and to figs. from 4a to 5c, of the smoke tube boiler 3 there are represented a furnace 31, generally cylindrical in shape, in which combustion takes place, and a series of tubes 33 (which as a whole constitute the exchanger 32 through which the burnt gases pass through . Said pipes 33 are grouped in various bundles (also called smoke loops) through which the gases pass through the boiler one or more times 3. Both the hearth 31 and the pipes 33 are surrounded by water A (in the liquid state and steam) contained in a cylindrical casing 38; at the end of this, front and rear tube plates 3801 are provided for coupling the furnace 31 and the tubes 33.

More specifically (see for example Figure 4a), the burnt gases, exiting the hearth 31, which coincides with the first flue gas pass 3101, pass into a first inversion chamber 34 and enter from this, confined at the top by a diaphragm 3401, in the pipes 33 of the second flue gas pass 3302. These fumes are then discharged into a second inversion chamber 35, usually located on the front of the boiler 3 (for this purpose, refer to the direction of the arrows F shown on the various pipes 33 of figure 1), and finally, through the third, and last, round of smoke 3303, now sufficiently cold, carried to the chimney 36.

Figures 4a to 5c schematically show an inspection door 37 which the boiler 3 normally provides at its front for inspection and any maintenance operations.

The boiler 3 further comprises at least one burner upstream of the furnace 31 and the relative fan (or blower) for supplying the combustion air (in any case not shown in the attached figures).

All known boiler components have been mentioned so far 3.

Reference 4 indicates a conveyor which, according to the invention, is intended to convey said combustion gases FI for their energy recovery in at least a part of the exchanger 32.

The inspection door 37 is suitably modified, with respect to the known art, so as to allow the housing and passage of the conveyor 4 in it.

Said conveyor 4 has an external part 41 connected, directly or indirectly through ducts, to one or more heat sources 2 to receive the combustion gases FI and an internal part 42 intended to be coupled with one or more tubes 33 of the heat exchanger 32 of the smoke tube boiler 3, in particular with one or more tubes 33 of at least the third smoke pass 3303, pressing on the front tube plates 3801 with its outlet 4201.

In order to be able to selectively vary the one or more pipes 33 with which the conveyor 4 is coupled, according to the flow rate and temperature of the combustion gases FI, or to prevent the conveyor 4 itself from interfering with said pipes 33 when there are no combustion FI from which to recover energy, the internal part 42 should be able to rotate and translate axially with respect to the external part 41, in which it is partially inserted.

Therefore, preferably and with reference to Figures 4a to 4c, said conveyor 4 is a telescopic duct which comprises an external part 41 hermetically bound to the inspection door 37 and an internal part 42, capable of rotating and translating axially with respect to the external part 41, in which it is partially inserted, by means of a telescopic coupling joint 5 (schematically represented in the attached figures). In particular, said rotation is allowed by the sections 4101 and 4205, both circular, of said joint 5 in correspondence of which the coupling between the external 41 and internal part 42 of the duct 4 is realized (see in particular figure 5c ).

By way of non-limiting example, the internal movable part 42 preferably has a mouth 4201 with an elliptical and / or circular section.

The axial translation of the internal part 42 with respect to the external fixed part 41, allows the mouth 4201 to approach, inside the inversion chamber 35, the tube plate 3801, so as to intercept said one or more smoke tubes 33, while the its rotation determines which smoke pipes 33 of said plate 3801 must be dedicated to the combustion gases F1 of the heat source 2, and therefore the number of passages in the boiler 3 of the same.

With reference to figures 4a to 4c, 5a and 5c, said smoke pipes 33 intercepted by said mouth 4201 therefore define the part 3201 of the heat exchanger 32 of the boiler 3 dedicated to cooling only the combustion gases FI from one or more sources heat 2.

For example, with reference to figure 4a, the duct 4 is able to intercept an appropriate number of tubes 33 belonging only to the third flue gas pass 3303 while, with reference to figures 4b and / or 4c, it is easy to observe how for effect of the rotation, the internal part 42 of the duct 4 can simultaneously intercept several smoke pipes 33 of the third smoke lap 3303 and at least one pipe 33 of the second lap 3302.

In the case of figure 4a, therefore, the combustion gases F1 of the heat source 2 make a single passage in the boiler 3, through the third flue gas pass 3303, while in the case of figure 4b and / or 4c, a part of said gas FI combustion perform a triple passage in the boiler 3.

With reference to figures 4b and 4c, in fact, part of said fumes FI crosses, in a front-back direction, the boiler 3 through one or more pipes 33 of the second smoke pass 3302, reverses its direction in the inversion chamber 34, passes in the pipes 33 of the second flue pass 3302 not intercepted by the mouth 4201 of the duct 4, and therefore crosses the third and last pass 3303 before discharging to the chimney 36.

Obviously, the film tubes 33 of any turn not intercepted by the mouth 4201 continue to be crossed (according to the lines of the arrows F and their vectorial representation shown in the attached figures, where the `` x '' means the front-back direction and with â € œâ € the opposite rear-front) from the products of internal combustion to the boiler 3, or from a mixture thereof with said combustion gases FI (as happens, for example, with reference to fig. 4b, in the pipes 33 of the second round 3302 not exclusively dedicated to the combustion gases FI themselves).

Similar arguments are also valid for the variant of figures from 5a to 5c which differs from what has been described up to now for the circular section (rather than more generally elliptical) of the mouth 4201 of the duct 4.

In this case, in order for the rotation of the internal part 42 of the duct 4 to be functional to the purposes described above, it is necessary that the center of the mouth 4201 be offset with respect to that of the fixed external part 41.

With reference to figures 5c, the internal part 42 comprises a first section 4202, coaxial to the fixed part 41, and a second section 4203 (the one intended to be coupled with its mouth 4201 to the tube plate 3801) with axis parallel to the first and to it connected via a 4204 connection branch.

The duct 4 is completed by an interception member 43, e.g. a butterfly valve 43 located in the fixed part 41 and intended to exclude the heat source 2 from the boiler 3, in the event of its malfunction, maintenance or if it is desired to operate the heat recovery apparatus 1 of the invention like a traditional flue gas boiler 3.

In this last case, it is therefore necessary to close the valve 43 while the internal part 42, mobile, of the duct 4 is retracted inside the fixed part 41, so that all the smoke pipes 33 of the boiler 3 are crossed exclusively by the products. internal combustion of the same.

Although not shown, one or more magnets can also be provided near the mouth 4201 of the duct 4 to ensure a better coupling between the duct 4 and the tube plate 3801 and therefore a perfect seal of the same. Alternatively, any known means of pressing the port 4201 against the tubesheet 3801 can be used.

According to possible variants of the invention, a further suction fan (not shown) can be placed at the chimney 36 so as to allow a correct circulation of the fumes FI through the smoke tube boiler 3 by forcing them to pass through the aforementioned tubes 33 of its exchanger. 32.

From what has been described so far, it is easy to see how the number of pipes 33 that should be intercepted by the duct 4 and the number of combustion gas passages FI in the boiler 3 depends on a series of factors such as, for example, the their temperature at the outlet from one or more heat sources 2, their flow rate and, more generally, the heat output available to the fumes.

The configurations of figures 4a and 5a (a single passage of the exhaust fumes FI into the boiler 3) are preferable in the case of low thermal powers dispersed by the combustion gases FI (and / or their reduced temperatures), while on the contrary, the configurations figure 4b and 4c or figure 5b, or any other configuration that ensures three passages of the fumes FI into the boiler, are to be preferred with higher values of the thermal power dispersed.In any case, however, the number of pipes 33 intercepted by the duct 4 and consequently, the number of passages of the fumes FI in the boiler 3 is chosen in order to obtain, at the output of the same, fumes FI at the minimum possible temperature.

If it is expected that the physical parameters that characterize the combustion gases FI (their temperature and flow rate) are substantially constant over time, the choice of one of these configurations (and therefore in particular the angle of rotation of the mobile internal part 42 of duct 4) can be determined manually.

More generally, however, it is preferable that an electronic control unit determines the most appropriate rearrangement of the duct 4 when the said physical parameters vary, of which it receives information through suitable sensors.

It is evident that the greater the part 3201 of the heat exchanger 32 dedicated to the combustion gases FI, the less will be the thermal power that can be delivered to the furnace 31 but the modulation of this power takes place automatically by the organs control units with which the heat generator 3 is normally equipped. In fact, the power to the furnace is modulated according to the demand for thermal energy by the user which, in the event of the presence of combustion gases FI, is satisfied with lower loads to the furnace 31.

As already partially anticipated, in one or more heat sources 2, in addition to the combustion gases FI, there is the possibility of recovering the thermal energy of the cooling and / or ventilation air F2 in the boiler 3, for example, of the auxiliary organs and circuits of the source 2 itself, otherwise dispersed in the environment.

According to a preferred and advantageous form, the cooling and / or ventilation air F2 that is warmer than the ambient air (temperatures from 60 to 90 ° C) is sent, by known means, directly into the furnace 31 of the boiler 3 and used as combustion air. From this point of view, the heat source 2 therefore acts as a preheater of the combustion air for the internal combustion of the boiler 3.

As a result of said further energy recovery in boiler 3 and of that operated on the fumes FI there is therefore a consistent improvement in the overall efficiency of the heat recovery apparatus 1 of the invention.

In fact, it is known that in a boiler 3 for the production of hot water and / or steam the efficiency is a function of the temperature of the air sucked into the burner of the hearth 31 and of the exhaust fumes: the more the temperature said air approaches that of the fumes at the chimney 36 the better is the thermal efficiency of the boiler 3 and therefore of the heat recovery apparatus 1 as a whole.

It is clear that numerous other variants to the heat recovery apparatus 1 object of the invention are possible for the man of the art, without thereby departing from the areas of innovation inherent in the inventive idea, just as it is clear that in the practical implementation of the invention, the various components previously described may be replaced by technically equivalent elements.

Preferably, the heat source 2 can be a prime mover used substantially for the production of electrical energy.

Even more preferably, said prime mover 2 is, as already anticipated, an internal combustion engine or a gas microturbine, technologies by now consolidated and reliable, on which it is therefore not necessary to dwell for long. According to this preferred form, the heat recovery apparatus 1 is therefore a cogeneration apparatus for the combined production of electrical and thermal energy for which all the considerations previously made are valid.

In this case and with respect to the known art, the prime mover 2 can be without its traditional integrated recuperator, being connected (by means of the said conveyor 4) to the boiler 3 in which, undoubtedly, a more efficient heat recovery takes place. otherwise dispersed therefrom in the form of combustion gas FI and cooling and / or ventilation air F2.

According to other forms, the prime mover 2 (or more generally the heat source 2) can be connected, by means of the telescopic duct 4, to the rear of the flue gas boiler 3, instead of, as seen, in correspondence with its hatch (suitably modified to allow the passage of said conduit 4).

A very simplified variant of the cogeneration apparatus 1 (or, in general, of the heat recovery apparatus 1), and in particular of the said conveyor 4, can also be envisaged; according to this simplified variant, its internal movable part 42 can simply translate axially with respect to the fixed one 41 without necessarily rotating. This configuration is particularly suitable, as already mentioned, when the physical parameters that characterize the combustion gases FI are substantially constant over time and the choice of the part 3201 of the heat exchanger 32 dedicated to said gases FI can be determined manually.

For this purpose, a further simplified variant is also possible in which the conveyor 4 comprises only the external part 41 (for descriptive simplicity from here on said conduit 41) hermetically coupled to the inspection door 37 but capable of translating to intercept the pipes 33 of the exchanger 32 of the boiler 3 dedicated to the aforementioned combustion gases FI.

It is therefore evident that with the heat recovery apparatus 1 just described above in its preferred form and in its variants, the set aims are achieved, in particular the possibility of recovering heat simply and economically from different types of machines.

For example, in the specific case in which the heat source 2 is a prime mover (but the same reasoning can also be extended to the more general case of any alternative heat source 2) the possibility of dedicating part of the heat exchanger 32 of the boiler 3 for cooling only the combustion gases FI of said motor 2 and the recovery of the cooling and / or ventilation air F2 allows a significant increase in the overall efficiency of the cogeneration apparatus 1 and an almost total recovery of its thermal losses.

It is also evident that, with reduced investments, any user can integrate a boiler 3, already installed and operational, with an engine 2, suitable for electricity generation, choosing the power that best suits its consumption. Said cogeneration systems 1 are thus able to satisfy also the needs of those users which require high thermal power but low electrical power. In fact, it is sufficient to supply an accessory door with the flue gas boiler 3, to replace the standard one 37 and capable of housing and supporting said conveyor 4.

The integration of gas micro-turbines or internal combustion engines with boilers 3 already installed or on the market also significantly reduces their specific cost, as it is no longer necessary to provide, as in the known art, devices for the recovery of exhaust fumes (and / or cooling air) internal and strongly integrated.

The cogeneration apparatus 1 of the invention also has a longer useful life than the traditional ones, at least thanks to the possibility of maintaining separately or renewing, if necessary, now only the prime mover 2 now only the tube boiler smoke 3; there is also no need to interrupt, even temporarily, the electrical and / or thermal production in the event of failure or replacement of one of these components.

Finally, the heat generator 3 can also be a water tube boiler.

Claims (19)

CLAIMS Rev. 1 Thermal generator (3) for the production of thermal energy comprising: - at least one hearth (31), in which combustion takes place - a heat exchanger (32; 3201, 3101, 3302, 3303) in which the cooling of the combustion products takes place, called heat exchanger (32; 3201, 3101, 3302, 3303) being of the `` smoke pipes '' type which provides one or more smoke turns (3101, 3302, 3303) comprising a plurality of pipes (33) contained in an external casing (38) of said generator (3), each end of said casing (38) providing a tube plate (3801) for the coupling of said tubes (33) and of said at least one hearth (31), and - a chimney (36) for their discharge into the atmosphere, said heat generator (3) being connected by means of a conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) to one or more heat sources (2), said one or more heat sources (2) being external heat sources and distinct from said generator (3) and said conveyor (4) sending the hot gasses (FI, F2) emitted by said one or several heat sources (2) in said heat generator (3) for the recovery of their enthalpy content characterized by the fact that said hot gasses (FI, F2) emitted by said one or more heat sources (2) are combustion gases (FI) and by the fact that said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) is adapted to bring said combustion gases (FI) to release heat in a part (3201) of said exchanger (32; 3201, 3101, 3302, 3303). Rev. 2 Thermal generator (3) according to the preceding claim characterized in that said part (3201) of said exchanger (32; 3201, 3101, 3302, 3303) can be used exclusively for cooling said combustion gases (FI). Rev. 3 Thermal generator (3) according to any preceding claim characterized in that said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) adapted to bring said combustion gases (FI) from said one or more heat sources (2) to said heat generator ( 3) includes: - an external part (41) connected to said one or more heat sources (2) to receive said combustion gases (FI) - an internal part (42) destined to be coupled, in correspondence with its mouth (4201), to said tube plate (3801) so as to intercept one or more of said tubes (33) of said heat exchanger (32; 3201, 3101, 3302, 3303), said one or more tubes (33) defining said part (3201) of the heat exchanger (32; 3201, 3101, 3302, 3303) dedicated to the cooling of said combustion gases (FI) Rev. 4 Thermal generator (3) according to the preceding claim characterized by the fact that said inner part (42) is capable of translating approaching said tube plate (3801) so as to be able to intercept said one or more of said tubes (33), defining said part (3201) of said heat exchanger (32; 3201 , 3101, 3302, 3303) dedicated to the cooling of said combustion gases (FI), or it can move away from said tube plate (3801) so that all the smoke tubes (33) of said heat exchanger ( 32; 3201, 3101, 3302, 3303) are crossed exclusively by the products of internal combustion in said at least one hearth (31) of said generator (3). Rev. 5 Thermal generator (3) according to the preceding claim characterized in that said internal part (42) translates axially with respect to said external part (41) in which it is partially inserted, said internal (42) and external (41) parts being coupled together by means of a telescopic joint (5; 4101, 4205 ). Rev. 6 Thermal generator (3) according to the preceding claim characterized in that said telescopic joint (5; 4101, 4205) has circular sections (4101, 4205), said internal part (42) being therefore capable of rotating with respect to said external part (41) in which it is partially inserted. Rev. 7 Thermal generator (3) according to any preceding claim, in particular 3 characterized by the fact that the center of said mouth (4201) is on the same axis as that of said external part (41), said mouth (4201) having such a section as to define and vary, due to its rotation, said part (3201) of the exchanger of heat (32; 3201, 3101, 3302, 3303) dedicated to the cooling of said combustion gases (FI). Rev. 8 Thermal generator (3) according to any preceding claim except 7, in particular 3 characterized by the fact that the center of said mouth (4201) of said internal part (42) is offset with respect to that of said external part (41), said mouth (4201) defining and varying, due to its rotation, said part (3201) of the heat exchanger (32; 3201, 3101, 3302, 3303) dedicated to the cooling of said combustion gases (FI). Rev. 9 Thermal generator (3) according to any preceding claim, in particular 3 characterized by the fact that the said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) is housed and passes through the inspection door (37) of said heat generator (3), the said external part ( 41) of said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) being hermetically coupled to said inspection door (37). Rev. 10 Thermal generator (3) according to any preceding claim characterized in that said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) further comprises an interception member (43) intended to exclude said one or more heat sources (2) from said heat generator (3), said interception member (43) being, in particular, a butterfly valve located in said external part (41). Rev. 11 Thermal generator (3) according to any preceding claim, in particular 3 characterized by the fact that said part (3201) of the heat exchanger (32; 3201, 3101, 3302, 3303) intercepted and defined by said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) comprises a or more pipes (33) of the second (3302) and / or third (3303) flue gas pass. Rev. 12 Thermal generator (3) according to any preceding claim, in particular 9 characterized by the fact of already installed and operational or already on the market, the said inspection door (37) in which the said conveyor is housed and passing through (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) being an accessory door to replace the standard door of said heat generator (3). Rev. 13 Thermal generator (3) according to any preceding claim characterized in that said hot gasses (FI, F2) emitted by said one or more heat sources (2) further comprise the cooling and / or ventilation air (F2) heated by the cooling of various equipment of said one or more heat sources ( 2), said cooling air (F2) being used as combustion air in said at least one furnace (31). Rev. 14 Thermal generator (3) according to any preceding claim characterized in that said one or more heat sources (2) consist of prime mover and / or low efficiency heat generators and / or cooling coils. Rev. 15 Conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) designed to carry hot gasses (FI, F2) from one or more heat sources (2) to a heat generator (3) for the recovery of their enthalpy content, according to one or more preceding claims from 1 to 12. Rev. 16 Heat recovery apparatus (1) comprising a heat generator (3) and one or more heat sources (2), said generator (3) and said one or more heat sources (2) being connected to each other by means of a conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205), according to one or more of the preceding claims. Rev. 17 Recovery apparatus (1) according to the previous claim characterized by the fact of being a cogeneration apparatus (1), the said one or more heat source (2) being a prime mover (2) used for the production of electrical energy and / or mechanical. Rev. 18 Method of recovering in a heat generator (3) the enthalpy content of hot gasses (FI, F2) emitted by one or more heat sources (2), according to any preceding claim characterized in that said one or more of said tubes (33), which it is desired to have intercepted by said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205), and which define said part (3201) of said heat exchanger (32; 3201, 3101, 3302, 3303) dedicated to the cooling of said combustion gases (FI), are selected manually, said combustion gases (FI) having physical parameters substantially constant over time, said physical parameters being, in particular, their flow rate and / or temperature. Rev. 19 Method of recovering in a heat generator (3) the enthalpy content of hot gasses (FI, F2) emitted by one or more heat sources (2), according to any previous claim except the 18 characterized by the fact that one or more of said pipes (33) which it is desired to have intercepted by said conveyor (4; 41, 4101, 42, 43, 4201, 4202, 4203, 4204, 4205) and which define said part (3201) of said exchanger of heat (32; 3201, 3101, 3302, 3303) dedicated to the cooling of said combustion gases (FI), are suitably selected automatically by an electronic control unit as the physical parameters that characterize said gases vary, instant by instant, combustion (FI) of which it receives information through appropriate sensors called physical parameters being, in particular, their flow rate and / or temperature.