The invention relates to the field of the recovery of heat energy from tubular beam furnaces and its conversion into electricity by means of an expansion turbine cycle using a fluid other than water vapor.

The invention relates in particular to steel reheating furnaces for reheating products, including slabs, blooms, billets, blanks or operating at a suitable temperature for their hot rolling, especially the walking beam furnaces. A heating furnace allows to bring the material to elevated temperatures, for example at a temperature of about 1200 ° C for a carbon steel. Heating of the furnace is commonly achieved by burners fed with preheated air and fuel and operative in slight excess of air.

EP0971 192 describes an example of furnace side members equipped with the fixed beams and walking beams. The products are deposited on the longitudinal members and are heated by burners arranged above and below the product. The spars are made of andirons and bowling cooled. The walking beams allow the transport of products in the oven according to a cycle comprising a first phase of rise by the walking beams, from an initial position, which enables to lift the products. The first phase is followed by a second horizontal transport phase by the walking beams and a third phase of depositing the products on the fixed beams. The products are thus moved from step on the fixed beams before the fourth stage turning back of the walking beams to their initial position. The fender of the fixed beams are supported by pins integral with the oven. The fender of the walking beams are supported by pins passing through the oven and attached under the oven, on a translating chassis. The translating chassis is based on a mechanism that ensures a rectangular ring by the horizontal and vertical displacement of the frame, pins and andirons of the walking beams.

The structure of the rails is carried by tubes or hollow profiles which are cooled by a coolant circulating fluid which is typically water at low temperature and low pressure, for example 30 to 55 ° C and 5 bar. The amount of energy discharged per unit time by the coolant is important to limit the temperature and have sufficient mechanical strength of the structure of the side members. The power is evacuated for example 10 MW th for an oven

capacity of 450 t / h. Hot water recovered at the outlet of the side rails can then be used in the plant, for example for sanitary, heating buildings or processes for which relatively low temperatures are necessary. It is known that one can replace the water at low temperature and low pressure cooling spars by the high-pressure superheated water, which partially transformed into saturated steam in the fender. The steam obtained can be used in the plant for different needs. Cooling the structure of the side members by a saturated water and steam mixture is advantageous, in particular because it allows the operation of the structure of the side members at a stable temperature. Indeed, the change of state of the liquid phase to the vapor phase being at a substantially constant temperature, the outlet temperature of the rails of coolant is constant, regardless of the operating conditions of the furnace, only the quantity of water passing in the vapor phase evolving. coolant outlet temperature is, for example, 215 ° C for a fluid pressure of 21 bar absolute.

A heat recovery unit is typically disposed in a flue of the furnace flue gases. It allows energy recovery on these fumes by preheating combustion air burners and sometimes fuel. Downstream of the regenerator, the flue gas temperature is still relatively high, eg 300 ° C. It is known to add additional heat exchangers, or a recovery boiler, in the flues to further exhaust fumes. In the case where the cooling of the structure of the side members is formed by superheated water with steam generation, it may for example be a superheated water economizer or superheater.

The steel reheat furnaces operate continuously and have significant production capacity, for example 450 t / h. Their operating speed varies frequently, according to the nature and temperature of put in the oven and the timing of oven products. As a result, the volume of flue gases also varies frequently, the latter being substantially proportional to the hourly tonnage of the products heated in the furnace. Changes in the flow of fumes are also accompanied by a change in temperature of said fumes. These fluctuations of the flue gas temperature lead to a significant change in performance exchangers arranged in flues or recovery boilers. Reduced tonnage smoke temperature can no longer promote the

The products to be reheated in the furnace must always be heated to the rolling temperature, and the latter being relatively constant, the temperature of the furnace walls varies little. Heat loss through the side members fluctuates little, the steam generation by one of the spar structure cooling system is less dependent on the hourly tonnage of the furnace.

The thermal energy contained in the flue gases and the cooling fluid beams each represent approximately 10 MW th on a furnace

450 t / h, respectively of the order of 300 ° C temperature and 200 ° C. The use of a water-steam cycle for producing electricity from these energies is difficult to implement and n is not economically feasible with these levels of temperature and thermal power, and these amplitudes power variations.

KR20140036363 describes an energy recovery solution on a steel reheat furnace to enhance the energy losses of the furnace contained in the fumes and the spars cooling system, exploiting them in a common electricity generating plant while overcoming the variability of these issues. It implements a power generation facility by a thermodynamic Rankine cycle using an organic fluid as the working fluid. An organic Rankine cycle machine, called "ORC" to the acronym for the English words Organic Rankine Cycle, converts the average heat or electricity in low temperature, with the use of a higher density organic working fluid than water. ORC in the machine, the working fluid in the liquid state is compressed and then vaporized. The organic fluid vapor is then expanded before being condensed. The machine includes an evaporator, an expansion turbine, a condenser and a booster pump. The expansion turbine is for example radial or axial type, with one or two floors, the rotation of which drives a generator that produces electricity.

The organic fluid has a low boiling temperature, for example below 50 ° C at atmospheric pressure, and is wetting type, that is to say it is not necessary to overheat the steam that fluid after evaporation to avoid the creation of droplets in the turbine during expansion. This type of fluid can thus allow, despite a low temperature heat source, extract maximum work in the turbine and thus perform better than a steam cycle of water at low temperatures, such as below 350 ° C.

Thus the choice of the ORC technology from the various thermodynamic cycles for producing electricity, provides better performance thermodynamic machine, that is to say the ratio of available thermal energy and electricity net.

The heat necessary for vaporization of the organic fluid ORC machine are provided by the energy recovered from the soaking furnace, partly on the coolant of the side members and partly in the flue gases.

In the solution disclosed by KR20140036363, the andirons pins and coolant is a mixture of molten salts. This mixture is composed, for example, by weight, 52% of KN0 3 , 18% of NaN0 3 and 30% LIN0 3. To maintain these molten salts in the temperature range required for proper operation of the oven, and in particular to maintain them in liquid phase, the installation comprises a recirculation loop 40 with additional equipment which makes it more costly installation and relatively complex to operate compared to a solution in which the cooling fluid is water or a water / steam mixture. Calories molten salts are transmitted to the body fluid of the ORC by means of an exchanger 21. In case of damage of this exchanger, the molten salt may come in contact with the body fluid of the ORC representing a risk for the installation. Moreover, this solution does not allow to modulate the heat input of the molten salt to the organic fluid from the ORC. When stopping the ORC, continuous calorie intake by the molten salt can lead to a very significant rise in the organic fluid temperature from which a risk for the installation.

Furthermore, KR20140036363 describes a solution wherein part of the fumes directly exchange heat with the body fluid of the ORC by means of an exchanger 51. In case of deterioration of this exchanger, there is a risk of fire if the organic fluid of CRO comes in contact with the fumes.

The state of the art does not allow dual energy recovery on fumes from heating furnace and on the andirons and bowling coolant under conditions allowing optimal energy performance, a regulatory flexibility of the operation of ORC and safe operating conditions.

This object is achieved, according to a first aspect of the invention, an energy recovery process by a device for recovering energy, adapted to be connected to at least one walking beam reheating furnace equipped with burners, said furnace reheating comprising a cooling circuit of said side rails, wherein water circulates, the latter being in the liquid state at the inlet of the longitudinal members and in the liquid mixture state / steam leaving the longitudinal members, said mixture being separated downstream from the rails into the liquid water on one side and steam from each other, the steam directly or indirectly yielding calories at a first recirculation loop intermediate, and further a system for the recovery of allowing energy toabsorb some of the heat from the flue gas circuit evacuated by the furnace, said calories being transferred to a second loop via recirculation, said first and second intermediate recirculation loops transferor directly or indirectly calories to an organic fluid loop arranged to power a turbine that produces electricity by the implementation of an organic Rankine cycle.

In a configuration in which the cooling andirons and pins is carried out by water and a water / steam mixture, the condensation of the vapors in the exchanger allows for significant transfers of heat between the steam and the organic fluid ORC .

According to the invention, the heat from the steam and those from the flue gas circuit are transferred indirectly to the organic fluid ORC, via a first intermediate recirculation loop disposed between a circuit including the steam and the organic fluid, respectively via a second loop recirculation of intermediate disposed between the circuit of the fumes and the organic fluid.

The steam circuit is isolated from the body fluid by at least two devices, for example two exchangers.

The smoke circuit is isolated from the body fluid by at least two devices, for example two exchangers.

Thus, according to the invention, the heat from the steam are first transferred to a first intermediate recirculation loop before being transferred to the organic fluid used in the Rankine cycle. Also, although the steam has a very high pressure relative to that of the organic fluid, there is no significant risk of explosion if the exchanger is pierced, although the organic fluid from the ORC is often a hydrocarbon or a flammable refrigerant, because the steam can not come into contact with said organic fluid.

Moreover, according to the invention, the calories from flue gases are first transferred to a second intermediate loop recirculation before being transferred to the organic fluid used in the Rankine cycle. Also, there is no possible exchange between the organic fluid used in the Rankine cycle and fumes, eliminating a fire hazard that is present in the prior art.

The method of the invention thus provides greater safety than in the prior art.

Combining the two sources of energy from the fumes and cooling system allows one hand to be able to increase the production of annual global electricity and also be able to limit investment. Indeed, this combination provides a greater amount of usable energy in a single ORC machine capacity (with better performance and less

expensive) if both heat sources were operated separately by two ORC machines smaller capacity (lower yielding and proportionately more expensive).

In addition, the combination of two sources of energy from the fumes and cooling system can help stabilize energy intake provided the ORC machine. Combining the two sources of energy from the fumes and cooling system can afford to run more often ORC machine in its optimum operating range.

The design of the machine allows CROs to limit the amount of investment, and therefore the time to return on investment, increasing the economic interest of its implementation. At its design, a heating furnace is designed for a nominal capacity corresponding to the heating of a number of tons per hour of a reference product from an initial temperature to a coke pushing temperature. From experience, in operation, the oven works on average about 70% of its rated capacity.

Furthermore, an ORC machine works correctly over a wide range of variation of the heat source, the incoming thermal power generally varies between 30% and 100%. The maximum yield of the ORC machine is obtained for the maximum design power and decreases with the incoming thermal power. ORC machine must be stopped when the calorie intake to the organic fluid ORC machine is lower than a minimum threshold generally between 20 and 30% of the maximum capacity allowed by the ORC machine.

By combining the two sources of thermal energy, the invention allows, thanks to the stability and capacity of the heat source from the spars cooling system, never be less than 30% of the heat load. Thus the ORC machine is still in operation, except in case of shutdown of the plant, and does not require complex regulation.

According to another aspect of the invention there is provided an energy recovery system adapted to be connected to at least one walking beam reheating furnace equipped with burners, said heating furnace comprising a cooling circuit of said side rails, wherein water circulates, the latter being in the liquid state at the inlet of the longitudinal members and in the liquid mixture state / steam leaving the longitudinal members, said mixture being separated downstream from the rails into liquid water on one side and steam from each other, said installation comprising a turbine arranged to generate electricity by the implementation of a Rankine cycle is an organic fluid, said installation further comprising at least one of the exchangers heat operably arranged

so as to transfer to said organic fluid, at least some of the heat contained in the combustion fumes of the burner, via a heat transfer fluid, and at least part of the calories contained in the steam, via a coolant.

According to one possibility of the installation, at least a heating furnace may comprise a heat exchanger which is disposed in an exhaust flue flue gases of said at least one reheat furnace to collect calories from said combustion gases and transmitting the heat transfer fluid circulating in said heat exchanger.

The heat exchanger placed in the flue discharge fumes according to the invention may optionally be disposed downstream in the flow direction of the other energy recovery equipment on smoke fumes. Other energy recovery equipment may be, for example, preheating recovery of the combustion air of the burners.

According to one aspect of the invention, the installation comprises a first heat exchanger operatively arranged so as to directly or indirectly transfer the energy of the steam to a heat transfer fluid medium and a second heat exchanger arranged so as to transfer thermal energy from said intermediate heat transfer fluid to the body fluid of the ORC machine.

According to the invention, the heat transfer fluid medium may be an organic fluid in liquid state under the conditions of its use, for example a thermal oil. Advantageously, the intermediate heat transfer fluid is non-flammable to the temperature at which it is used, its ignition temperature substantially greater than that of body fluid of the ORC.

This configuration improves the robustness of the equipment by limiting sudden changes of temperature exchange with the body fluid of the ORC when stopping the furnace through the mass of the energy storage capacity intermediate fluid. It also improves the security of the exchange system with the calories exchanger from the steam by locally controlling the behavior of this exchange without disturbing the loop feeding the ORC exchanger. The steam being at a substantially higher pressure than that of the intermediate fluid (about 20 steam side bars for about 4 to 7 intermediate fluid side bars) in the event of puncture of the exchanger, the

Furthermore, the presence of an intermediate circuit between the steam circuit and the circuit of the ORC, prevents the vapor from coming into contact with the body fluid of the ORC, said contact being source 'explosion.

This solution also allows the use of a robust technology exchanger for exchange between the intermediate fluid and the body fluid of the ORC, both fluids having similar properties. It thus strengthens the operational safety of the ORC machine in case of problem on the cooling steam circuit rails.

To further enhance the security of the installation, an additional intermediate loop may be added between the vapor and the intermediate fluid described above.

A use of an intermediate organic fluid to recover calories from flue gases remaining in the liquid state, regardless of temperature fluctuations and volume of flue gases in the flue, has the advantage of greatly facilitate operation of the installation in relation to the implementation of a recovery boiler in which a phase change in the heat exchanger operates at a higher pressure.

Advantageously according to the invention, a regulation of the heat input to the ORC machine can be performed on the flue gas circuit by means of a partial bypass of the heat exchanger flue gas exhaustion placed in the flue or dilution of smoke with cold air to lower the temperature. Because sizing the ORC for furnace operation at 70% of rated capacity if the heat input to the ORC machine becomes too large, part of the fumes bypasses the exchanger the smoke exhaustion circuit combustion or fumes will be diluted without it interferes with the functioning of the oven.

The heat transfer fluid used to collect calories from flue gases and indirectly that used to collect calories from andirons and bowling can be similar, but this method also allows the use of heat transfer fluids with different properties. This can help optimize energy recovery with fluids at different temperature levels and enhance plant safety by choosing fluids minimizing the risk of fire or explosion on contact between fumes or vapor and these fluids.

In an alternative embodiment, the addition of an energy storage to the intermediate circuit improves the efficiency of assembly without disturbing the main exchange circuit to the ORC.

Advantageously, the operation spars cooling circuit may not be modified by the presence of ORC machine. The steering installation can thus be simplified.

The heating power transmitted to a thermal fluid used in the exhausted flue gas circuit can be directly determined by the temperature rise of said fluid in a heat exchanger of the combustion fumes exhausted circuit.

If judgment of the ORC machine circumvention of fumes arranged on the smoke circuit can prevent heating of the thermal fluid used in the exhausted flue gas circuit. Another method is to use a heat transfer fluid operating at a higher temperature on the DC bus and / or to reduce the flue gas temperature in the diluents, for example with an upstream air inlet of the recuperator placed on the smoke flue. Cooling towers may also be disposed on the circuit Hot water / steam so evacuating calories from rails.

Advantageously according to the invention, the ORC machine is dimensioned according to the average operating speed of the heating furnace and not in the nominal capacity of the furnace. This has two advantages: the ORC machine being smaller, the investment amount may be reduced, and the ORC machine can operate a maximum time on an optimum point (maximum performance) therefore producing electricity for a maximum faster return on investment.

The installation according to the invention may further comprise other operably disposed heat exchanger so as to transfer thermal energy from at least one other source in the organic fluid.

According to another aspect of the invention there is provided a walking beam reheating furnace equipped with burners, characterized in that it is equipped with an energy recovery system according to the invention, said power plant being connected to said furnace.

Other features and advantages will be apparent from the description of preferred embodiments of the invention accompanied by figures in which:

. Figure 1 schematically an installation according to a first embodiment wherein the body fluid of the ORC machine is preheated in series energy recovery on the two sources, steam and fumes,

. 2 schematically represents an installation according to a second embodiment similar to that of Figure 1 but wherein the body fluid of the ORC machine is preheated in a single step, after addition upstream of the two vapor sources and fumes ,

. Figure 3 shows diagrammatically a plant according to a third embodiment similar to that of Figure 2 wherein an additional intermediate circuit is added steam side, and,

. Figure 4 schematically shows an installation according to a fourth embodiment wherein organic fluids collecting calories from longitudinal and flue gas are mixed upstream of the ORC machine and energy is recovered in parallel.

These embodiments are in no way limiting, it may in particular make variants of the invention comprising only a selection of features described later, as described or generalized, isolated from the other features described, if the selected characteristics is sufficient to confer a technical advantage or to differentiate the invention compared to the prior art.

In Figure 1, schematically represented can be seen an installation according to a first exemplary embodiment of the invention. To simplify the description, are shown in this figure that the equipment necessary for the understanding of the invention. Equipment essential to the operation of the facility, such as pumps, valves, feedwater tank, expansion tank, etc., are not represented in this figure and the following, or described in this description, the skilled person knowing define, implement and design the best on the installation.

Product 1 are heated continuously in a heating furnace 2 of tubular side members. Moving and holding the products in the furnace is provided by the fixed beams and walking beams. The longitudinal members comprise pins andirons 3a and 3b through which a cooling fluid. 5 burners provide heat the oven 2 and 1 products. Of the flue gases from the burners 5 are discharged from the furnace by a smoke flue 6.

At the entrance of the side members, the coolant is, for example, superheated water at a temperature of 215 ° C and a pressure of 21 bars absolute. As it flows in the longitudinal members, the superheated water is partially transformed into saturated steam 4. At the outlet of the side members, the cooling fluid consists of a mixture of superheated steam and saturated steam 4. A ball 7 allows the separation of water in the liquid state and saturated steam 4.

The installation comprises an ORC machine implementing a Rankine cycle is an organic fluid 21 circulating in a circuit 13.

The installation comprises an intermediate recirculating loop 16 disposed between the steam circuit and the circuit 13 of the ORC machine. An intermediate fluid

coolant 17 circulates in the intermediate recirculating loop 16, preferably organic, maintained in the liquid state.

The intermediate recirculating loop 16 includes two heat exchangers 8 and 18 and an unillustrated circulation pump. And saturated steam 4 yields heat to the coolant fluid medium 17 by means of the heat exchanger 18 wherein it condenses, and then the coolant fluid intermediate 17 yields in turn heat to organic fluid 21 of the ORC machine by means of exchanger 8.

The addition of the intermediate recirculating loop 16 can strengthen the safety of the installation and use of the thermal fluids of different properties. Thus the heat transfer fluid medium 17 may have a greater compatibility with the steam the organic fluid 21 of the ORC thus limiting the risk of fire or explosion.

A heat exchanger 9 may be arranged in the smoke flue 6, optionally downstream in the flow direction of flue gas, compared to other energy recovery equipment in the flue gases, for example a preheating recuperator of the combustion air of the burners.

The heat exchanger 9 may be supplied with a coolant 10, preferably organic in the liquid state circulating in a recirculation loop 1 1. The heat transfer fluid 10 may be of the same nature as the heat transfer fluid 17 through the steam side, but it may also be of different nature. The fumes give up part of their calories to the heat transfer fluid 10 in the heat exchanger 9. A second heat exchanger 12 is arranged on the recirculation loop 1 1. The second exchanger 12 allows the transfer of calories taken up by the heat transfer fluid 10 to fluid 21 of the organic ORC machine.

The body fluid 21 flows in the ORC machine in the recirculation loop 13 including, preferences successively in the direction of fluid flow, the heat exchangers 8 and 12, an expansion turbine 14, a heat exchanger 15 of condensation organic fluid 21 of the ORC machine and a booster pump 24. the thermal energy given to the body fluid of the ORC 21 machine in heat exchangers 8 and 12 allows to bring the latter in the vapor phase. The expansion of the vapor causes expansion of the turbine rotation 14 which is coupled to a generator that produces electricity. On leaving the expansion turbine 14, the exchanger 15 allows condensing the organic fluid 21 before it is returned to the heat exchangers 8 and 12 to undergo a new cycle Rankine.

A set of 23 registers makes it possible to bypass the heat exchanger 9, for all or part of the combustion fumes.

A heat exchanger 25 captures the calories of a fluid 26 provided on the site and to transmit them to organic fluid 21 of the ORC machine. The installation according to the invention thus also enhancing one or more other heat sources for increased overall performance of the industrial site in which it is installed.

Figure 2 shows schematically an embodiment of the invention variant in which the calories fumes are made to intermediate fluid 17 and not directly to the fluid 21 of the ORC. Similarly, supplementation of calorie fluid 26 is in intermediate fluid 17 and not directly to the fluid 21 of the ORC. This configuration allows a simplified control of the ORC and strengthens its safety, with a single exchanger is constructed wherein all of the heat input to the fluid 21 and its vaporization.

Figure 3 shows schematically a further alternative embodiment of the invention wherein an intermediate loop 30 is added steam side in which circulates a heat transfer fluid 31. The vapor 4 yields heat to the heat transfer fluid 31 by condensing in the heat exchanger 18 and the coolant 31 in turn transfers the heat to the heat transfer fluid 17 by means of a heat exchanger 32. This configuration allows to strengthen security installation, and the flexibility of its regulation, technology exchangers 8, 18, 31 and the nature of heat transfer fluids 31, 17, 21 are selected so to have proven technology interchanges and mitigate risk fire or explosion on contact between the fluids following the drilling of the exchangers.

Figure 4 schematically illustrates another alternative embodiment of the invention wherein a mixture is formed between a portion of the coolant 10 circulating in the recirculation 1 1 There loop and part of the coolant through fluid 17, preferably organic, passing through the recirculation loop 16, the fluids 10 and 17 being of the same nature. This mixture, for example realized by means of three-way valves 20, is then led to a heat exchanger 19 wherein it transfers heat to organic fluid 21 of the ORC machine. On leaving the exchanger 19, the fluid mixture is again divided between the two recirculation loops 1 1 and 16, for example by means of three way valves.

The amount of energy available in the flue gases and the spars of the cooling fluid is generally of the same order of magnitude, for example, 10 MW th in the flue gases and the longitudinal members to a furnace with a capacity of 450 t / h.

On the heat exchanger 18, the temperature of saturated steam 4 is substantially constant, e.g., 215 ° C for a pressure of 21 absolute bars, the heat exchange with the coolant fluid 17 through the recirculation loop 16 is always optimum.

On the heat exchanger 9, the smoke temperature may vary, e.g., 300 ° C, for a maximum capacity of the furnace, at 280 ° C for 70% of its capacity. Thus, heat exchange with the heat transfer fluid 10 to the recirculation loop 1 1 is variable and the operating conditions of the common fluid loop 20 entering the ORC machines may vary, in the case of a thermal oil, 225 ° C to 215 ° C in temperature and 70 kg / s to 50 kg / s flow rate respectively in both cases of operation described above. For such temperatures, the organic fluid 21 of the machine ORC best suited is pentane, the latter being supported upstream of the expansion turbine 14 at a temperature for example between 135 ° C and 160 ° C respectively as two operating cases,

According to an exemplary embodiment of the invention, the energy recovery system used to collect calories from at least two ovens. A heat exchanger 9 may be arranged in the smoke flue of each oven or a single oven. Similarly, calories can be recovered from the steam from the side rails of the two furnaces or single.

As we have seen, the invention enables efficient energy recovery of heat losses from the furnace by the combustion fumes and stringers, with a design of the ORC machines well suited to the furnace operating conditions and stable operation of it resulting from the combination of two heat sources.

Of course, the invention is not limited to the examples just described and numerous adjustments can be made to these examples without exceeding the scope of the invention. Moreover, the different characteristics, shapes, and variants of the invention embodiments may be combined with each other in various combinations to the extent that they are not incompatible or mutually exclusive of the other.

CLAIMS

1. A process for energy recovery by an energy recovery unit adapted to be connected to at least a heating furnace (2) to side members equipped with burners (5), said heating furnace comprising a cooling circuit of said side rails wherein water circulates, the latter being in the liquid state at the inlet of the longitudinal members and in the liquid mixture state / steam leaving the longitudinal members, said mixture being separated downstream of the longitudinal members in the liquid water on one side and steam (4) from each other, said installation comprising a turbine (14) generating electricity by the implementation of a Rankine cycle organic fluid (21) , said method comprising a direct or indirect transfer step ofthermal energy from steam (4) to a heat transfer fluid medium (17), preferably organic in the liquid state, by means of a heat exchanger (18), a thermal energy transfer step said intermediate fluid heat transfer to the organic fluid (21) by means of a heat exchanger (8, 19), and a transfer step direct or indirect thermal energy of at least a portion of the flue gases of the burners (5) to the fluid organic (21) by means of a heat exchanger (12, 19) operatively arranged to be transferred to said organic fluid (21), at least part of the calories contained in the burners of the combustion fumes (5) via a heat transfer fluid (10) and an exchanger (9).a heat exchanger (18), a thermal energy transfer stage of said intermediate heat transfer fluid to the organic fluid (21) by means of a heat exchanger (8, 19), and a step of direct thermal energy transfer or indirectly at least part of the flue gases of the burners (5) to the organic fluid (21) by means of a heat exchanger (12, 19) operatively arranged to be transferred to said organic fluid (21), at least part of the calories contained in the burners of the combustion fumes (5) via a heat transfer fluid (10) and an exchanger (9).a heat exchanger (18), a thermal energy transfer stage of said intermediate heat transfer fluid to the organic fluid (21) by means of a heat exchanger (8, 19), and a step of direct thermal energy transfer or indirectly at least part of the flue gases of the burners (5) to the organic fluid (21) by means of a heat exchanger (12, 19) operatively arranged to be transferred to said organic fluid (21), at least part of the calories contained in the burners of the combustion fumes (5) via a heat transfer fluid (10) and an exchanger (9).Direct or indirect thermal energy of at least a portion of the flue gases of the burners (5) to the organic fluid (21) by means of a heat exchanger (12, 19) operatively arranged to be transferred to said organic fluid (21 ), at least part of the calories contained in the burners of the combustion fumes (5) via a heat transfer fluid (10) and an exchanger (9).Direct or indirect thermal energy of at least a portion of the flue gases of the burners (5) to the organic fluid (21) by means of a heat exchanger (12, 19) operatively arranged to be transferred to said organic fluid (21 ), at least part of the calories contained in the burners of the combustion fumes (5) via a heat transfer fluid (10) and an exchanger (9).

2. The method of claim 1, wherein the coolant (10) for transferring at least part of the calories contained in the burners of the combustion fumes (5) to the organic fluid (21) is an organic fluid state liquid, preferably a thermal oil.

3. The method of claim 1 or 2, wherein the coolant (10) for transferring at least part of the calories contained in flue gases of the burners (5) to the organic fluid (21) and the intermediate heat transfer fluid ( 17) for transferring thermal energy to the organic fluid (21) are of the same nature, the two heat transfer fluids (10, 17) being mixed in upstream of the exchanger (19) in which is formed the heat transfer between these fluid and organic fluid (21).

4. Energy Recovery plant adapted to be connected to at least a heating furnace (2) to side members equipped with burners (5), said heating furnace

comprising a cooling circuit of said side rails, wherein water circulates, the latter being in the liquid state at the inlet of the longitudinal members and in the liquid mixture state / steam leaving the longitudinal members, said mixture being separated downstream in the liquid water side members on one side and steam (4) from each other, said installation comprising a turbine (14) arranged to generate electricity by the implementation of a cycle Rankine on an organic fluid (21), said plant comprising a heat exchanger (18) operatively arranged to directly or indirectly transfer thermal energy of the steam (4) to a heat transfer fluid medium (17) preferably organic in the liquid state, the at least one heat exchanger (8,19) being arranged to transfer thermal energy from said heat transfer fluid through the organic fluid (21), said installation further comprising at least one heat exchanger (12, 19) operatively arranged to be transferred directly or indirectly to said organic fluid (21), at least part of the calories contained in the burners of the combustion fumes (5) via a heat transfer fluid (10) and an exchanger (9).via a heat transfer fluid (10) and an exchanger (9).via a heat transfer fluid (10) and an exchanger (9).

Installation according to claim 4, wherein the at least one heating furnace (2) includes the heat exchanger (9) which is disposed in a flue (6) of combustion fumes evacuation of said at least one furnace heating to collect the calories from said combustion fumes and transmit them to the coolant (10) flowing through said heat exchanger.

Installation according to claims 4 or 5, wherein the coolant (10) and the intermediate heat transfer fluid (17) are of the same nature.

Installation according to any one of claims 4 to 6, further comprising another heat exchanger (25) operatively arranged to directly or indirectly transfer thermal energy of at least one other source (26) to the body fluid (21).