MX2012005081A

MX2012005081A - Heat exchanger for direct evaporation in organic rankine cycle systems and method.

Info

Publication number: MX2012005081A
Application number: MX2012005081A
Authority: MX
Inventors: Matthew Lehar; Thomas Frey; Gabor Ast; Sebastian Freund; Richard Aumann
Original assignee: Nuovo Pignone Spa
Priority date: 2009-10-30
Filing date: 2010-10-27
Publication date: 2012-10-26
Also published as: RU2012116621A; EP2780558A2; AU2010311522A1; US20110100009A1; CL2012001098A1; CA2779074A1; PE20130026A1; WO2011051353A2; BR112012010150A2; CN103228912A; WO2011051353A3

Abstract

Systems and methods include heat exchangers using Organic Rankine Cycle (ORC) fluids in power generation systems. The system includes a heat exchanger configured to be mounted inside an exhaust stack that guides hot flue gases and having an inlet and an outlet, the heat exchanger being configured to receive a liquid stream of a first fluid through the inlet and to generate a vapor stream of the first fluid and the heat exchanger is configured to include a double walled pipe, where the first fluid is disposed within an inner wall of the double walled pipe and a second fluid is disposed between the inner wall and an outer wall of the double walled pipe.

Description

HEAT EXCHANGER FOR DIRECT EVAPORATION IN ORGANIC RANKINE CYCLE SYSTEMS AND METHOD FIELD OF THE INVENTION The modalities of the subject matter described herein are generally related to power generation systems and more particularly to Organic Rankine Cycle (ORC) systems.

BACKGROUND OF THE INVENTION The Rankine Cycles use a working fluid in a closed cycle to accumulate heat from a heat source or a hot tank generating a hot gaseous stream that expands through a turbine to generate energy. The expanded current is condensed in a condenser transferring the heat to a cold reservoir. The working fluid in a Rankine cycle follows a closed loop and is constantly reused. A system for power generation using a Rankine cycle is shown in Figure 1. These systems for power generation can be described based on the energy generated as primary power generation and secondary power generation systems. Additionally, secondary energy generation systems tend to use heat residual, for example, hot exhaust gases, from the primary power generation system to improve the efficiency of the total system. The generation of energy using the Rankine cycle is traditionally used as a secondary energy generation system.

The power generation system 100 includes a heat exchanger 2, or in some cases a boiler, a turbine 4, a condenser 6 and a pump 8. Transiting through this closed loop system, starting with the heat exchanger 2 , an external heat source 10, for example hot gas pipe gases, heat the heat exchanger 2. This causes the received pressurized liquid medium 12 to become a pressurized steam 14 which flows into the turbine / generator 4. The turbine 4 receives the pressurized steam stream 14 and can generate energy 16, for example, by rotating a mechanical axis (not shown) when the pressurized steam 14 expands into the turbine 4. The lower pressure steam stream expanded 18 then enters a condenser 6 which condenses the expanded lower pressure vapor stream 18 into a lower pressure liquid stream 20. The lower pressure liquid stream 20 then enters a pump 8 which generates the highest pressure liquid stream 12 and keeps the closed loop system flowing. The higher pressure liquid stream 12 is then pumped into the heat exchanger 2 to continue this process.

A working fluid that can be used in a Rankine cycle is an organic working fluid. Such an organic working fluid is referred to as an organic rankine cycle (ORC) fluid. ORC systems have been highlighted as adaptations for small-scale and medium-scale gas turbines to capture waste heat from the gas stream from the hot gas duct generated by a motor. These systems can generate up to an additional 20% of energy in the upper part of the engine's base line output, that is, ORC systems are typically used in secondary power generation systems. This ORRC working fluid is typically a hydrocarbon with a boiling temperature slightly above the baseline of the International Organization for Standardization for atmospheric pressure. Due to the concern that such hydrocarbon fluids may degrade if exposed directly to the discharge stream of the high-temperature gas turbine (approximately 500 degrees Celsius), measurements need to be taken to limit the surface temperature of the surfaces of heat exchange in an evapofador which contains ORC work fluids. A method currently used to limit the surface temperature of the heat exchange surfaces in an evaporator which contains the ORC working fluids is to introduce an intermediate thermo-oil loop into the heat exchange system, ie, to prevent the ORC liquid circulates through the discharge pipe of the gas turbine.

Another potential concern with ORC systems, when exposed directly to hot gases, is their potential flammability. If a leak occurs in a system using the ORC fluids, and the ORC fluid leaks into the hot exhaust gas stream, for example, gas from the hot gas duct, combustion and / or explosion could occur which could be potentially of a catastrophic nature for the power generation system and / or power plant. A method currently used to limit the surface temperature of the heat exchange surfaces in an evaporator which contains the ORC working fluids and reduce the risk of explosion is to introduce the intermediate thermo-oil loop within the heat exchange system, which separates the ORC fluid from the discharge conduit as discussed below.

The intermediate thermo-oil loop can be used between the hot gas duct gas and the vaporizable ORC fluid. In this case, the intermediate thermo-oil loop is used as an intermediate heat exchanger, i.e., heat is transferred from the hot gas duct gas to the oil, which is in its own closed loop system, and then from the oil to the ORC fluid using a separate heat exchanger. Separating the ORC fluid from direct exposure to the hot gas duct gas can protect the ORC fluid from degradation and decomposition. Additionally, while the oil used in the intermediate thermo-oil loop is flammable, this oil is generally less flammable than ORC working fluids. However, this thermal oil system takes up additional physical space and can account for up to a quarter of the cost of an ORC system.

Consequently, systems and methods to reduce cost and improve the safety of systems using ORC in power generation systems are desirable.

BRIEF DESCRIPTION OF THE INVENTION In accordance with an exemplary embodiment, there is a system for generating energy using an Organic Rankine Cycle (ORC, for its acronym in English). The system includes: a heat exchanger configured to be mounted within a discharge conduit that guides the gases of the hot gas conduit and having an inlet and an outlet, the heat exchanger being configured to receive a stream of liquid from a first fluid through the inlet and to generate a vapor stream of the first fluid and the heat exchanger is configured to include a double-walled tube, wherein the first fluid is disposed within an inner wall of the double-walled tube and a second fluid is disposed within the inner wall and an outer wall of the double-walled tube; an expander fluidly connected to the outlet of the heat exchanger and configured to expand the steam flow of the first fluid to generate energy; a condenser fluidly connected to an expander outlet and configured to receive and condense an expanded vapor stream; and a pump fluidly connected to an outlet of the condenser and configured to receive the liquid stream of the first fluid, to pressurize the liquid stream of the first fluid and to circulate the liquid stream of the first fluid to the inlet of the heat exchanger.

In accordance with another exemplary embodiment there is a method for vaporizing a Organic Rankine Cycle (ORC) fluid! in a power generation system. The method includes: transferring heat from a gas conduit gas in a discharge conduit through a first wall of a heat exchanger to a heating tube means which changes a first phase of the heating tube means from a liquid phase to a gaseous phase inside! of a compartment of the heat exchanger; and vaporizing the ORC fluid when heat is transferred from the heating tube medium in the gas phase through a second wall to the ORC fluid which is contained within the heat exchanger within the exhaust duct which changes a second pass of the heating tube means from the gas phase to the liquid phase, wherein the second wall is provided within the first wall.

In accordance with yet another exemplary embodiment, there is a heat exchanger in a discharge conduit directly exposed to gases from the hot gas conduit. The heat exchanger includes: a first tube configured to receive a heating tube fluid and further includes a second tube, wherein a volume between the first tube and the second tube is hermetically sealed and divided into compartments which are joined by an inner wall of the first tube, one! wall external of the second tube and walls of separation between the compartments; the second tube configured to receive a Organic Rankine Cycle (ORC) fluid; and the separation walls configured to join the first tube to the second tube, the heat exchanger configured to receive heat from the gases of the hot gas conduit and configured to receive a liquid stream of the ORC fluid through an inlet and to generate a vapor stream of the ORC fluid through an outlet.

BRIEF DESCRIPTION OF THE DRAWINGS The attached drawings illustrate the exemplary modalities, where: Figure 1 illustrates a Conventional Rankine Cycle; Figure 2 illustrates a heat exchanger which uses an organic fluid disposed within a discharge conduit in accordance with the exemplary embodiments; Figure 3 shows a double walled tube in accordance with the exemplary embodiments; Figure 4 illustrates a partial cross-section of the double-walled tube of Figure 3 with compartments in accordance with the exemplary embodiments; Figure 5 shows a view of the double-walled tube with toroid compartments in accordance with the modalities exemplars; Figure 6 is a flow chart of a method for exchanging heat in accordance with the exemplary embodiments; : Figure 7 illustrates discharge paths in accordance with the exemplary embodiments; Y Figure 8 shows a flow chart of a method for vaporizing an ORC fluid in accordance with the exemplary embodiments.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in the different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims.

Reference through the specification to "one modality" or "modality" means that a particular feature, structure or characteristic described in combination with a modality is included in at least one embodiment of the subject matter described. Thus, the appearance of the phrases "in one modality" or "in the modality" in several places through the specification does not necessarily refer to the same modality. In addition, particular properties, structures or characteristics may be combined in any appropriate manner in one or more embodiments.

As described in the Background of the Invention, and shown in Figure 1, a Rankine cycle can be used in secondary energy generation systems to use some of the residual energy from the hot exhaust gases of the power generation systems primary. A primary system produces most of the energy while also wasting energy. A secondary system can be used to capture a portion of the residual energy of the primary system. An Organic Rankine Cycle (ORC) can be used in these power generation systems depending on the system temperatures and other specific power generation systems. In accordance with the exemplary modalities, the ORC can be used for gas turbine power generation systems of medium to small size to capture additional heat / energy from the hot gas duct gas which can be released directly into the atmosphere .

As described in the generic Rankine Cycle of Figure 1, heat can be introduced into the cycle through a heat exchanger 2 or some similar process, for example, an evaporator or boiler. Previous ORC systems have used an intermediate thermo-oil loop system to transfer heat from the gases of the hot gas duct to the ORC working fluid. In these cases, the ORC system is out of the path of the gases from the hot gas duct and located outside the duct. In accordance with the exemplary embodiments, a more direct approach to heat exchange can be used which removes the need for a thermo-oil loop and locates the heat exchanger for the ORC system in the discharge conduit in contact with the gases of the hot gas duct, for example, temperatures between 350 degrees Celsius and 600 degrees Celsius, which can be found in electric power generation systems. However, in accordance with other exemplary embodiments other temperatures and temperature ranges may be used.

In accordance with the exemplary embodiments, heat exchange coils 202 can be wound in a serpentine fashion through a conduit 204, or equivalent waste heat discharge structure, as shown in Figure 2. Initially, the ORC fluid of pressurized liquid 12 enters from an inlet side into the heat exchanger 200. This working fluid can enter into the colder side of the heat exchanger 200 and travels through the coils of the heat exchanger 202 and exits from the exchanger of heat 200 from the hotter side, for example, closer to the heat source, such as a pressurized steam ORC fluid 14 on the outlet side. In this view, the coils shown closest to the arrow 206 are closest to the heat source (not shown). The arrow 206 represents the direction of travel for the gases from the hot gas duct leaving the duct, and "g" indicates the severity in this exemplifying Figure (however, other configurations of the heat exchanger may be in different orientations with respect to the severity ). Heat sources for ORCs include, but are not limited to, exhaust gases from combustion systems (power plants or industrial processes), hot liquid or gaseous streams from industrial processes, geothermal and solar thermal sources.

In accordance with the exemplary embodiments, a double-walled tube (which can also be considered as a tube within a tube) can be used as the heat exchange coils 202 in the heat exchanger 200 of the ORC system to protect the ORC workflow of decomposition and degradation. ORC fluid can degrade and / or decompose at local temperatures of 300 ° C or possibly at average temperatures of 240 ° C in larger volumes of ORC fluid. This operating range is generally applicable to any hydrocarbon that is used as the ORC fluid except for aromatic hydrocarbons, for example, thiophene, which may be capable of operating at higher temperatures.

An exemplary diagram illustrating this concept is shown in Figure 3. The heat exchange coil 202 of Figure 2 'may include a double-walled tube 300 with an outer wall 302 and an inner wall 306. A heating tube fluid it can be placed in the outer section 304 between the two walls and the working means QRC is located in the inner section 308, ie the volume limited by the inner wall 306. This exemplifying arrangement can allow a gas from the gas conduit of high temperature 206, for example, in the range of 350-600 degrees Celsius, transfers heat to the heating tube fluid in the outer section 304 through the outer wall 302. The fluid of the heating pipe then transfers heat to the fluid ORC in the horizontal section 308 through the inner wall 306. In accordance with the exemplary embodiments, this heat exchange between the heating tube fluid to the ORC fluid can be performed in such a way that the temperature used, and the potential temperature fluctuations, can be controlled in such a way that the temperature of the ORC fluid remains below a degradation temperature while still allowing the ORC fluid to vaporize before leaving the heat exchanger 200. In support of this, the fluid of the selected heating tube needs, at the desired pressure, to be able to use the thermal energy of the hot gas duct to change its liquid phase to steam. The steam from the heating tube tube fluid flows to the inner wall 306, where the vapor from the heating tube fluid is cooled, for example, releases thermal energy, and condenses in a fluid of heating tube tube and circulates from return to outer wall 302. In this manner the temperature of the heating tube fluid remains relatively constant when the heating tube fluid is able to absorb large quantities of heat from the gases of the hot gas duct without increasing its temperature, due to the phase change from liquid to gas.

To control this exemplary heat exchange, several factors can be modified to achieve this effect. These factors may include, but are not limited to, discharge gas temperature, tube dimensions, heat exchanger size, duct size, heating tube fluid, ORC fluid, internal tube construction and pressure (s). For example, if the temperature of the exhaust gas is 200 degrees Celsius versus 500 degrees Celsius, different combinations of the above mentioned factors can be used to achieve the desired cost effective heat exchanger 200. More details regarding these various factors are described in the exemplary embodiments below.

In accordance with the exemplary embodiments, the fluid of the heating tube can be hermetically sealed within the section 304. The fluid of the heating tube can be selected from several means which have some, or possibly all of the following characteristics: being less flammable that the ORC fluid, capable of undergoing a phase change to transfer heat to the desired temperature / pressure ratio, and be able to self-circulate within the 304 section. Examples of a heating tube fluid may include water, sodium, thermal oil and thermal oil based on silicon. Additionally, in accordance with the exemplary embodiments, the ORC fluid may be a hydrocarbon, such as, pentane, propane, cyclohexane, cycloperitan, and butane, or a fluorohydrocarbon such as R-245fa a ketone such as acetone or an aromatic such as toluene or thiophene .

In accordance with the exemplary embodiments, various implementations can be used to implement the double-walled tube in the portion of the heat exchanger of the ORC system one of which is shown in Figures 4 and 5. Figure 4 shows a partial cross-section of the double-walled tube 300 between outer wall 302 and inner wall 306. Figure 5 shows a view of double-walled tube 300 with a plurality of toroid-shaped compartments 406. In accordance with exemplary embodiments, outer section 304 ( extending the length of the outer tube) located between the outer wall 302 and the inner wall 306 may further be divided into compartments with a plurality of compartments 406. These compartments 406 contain the heating tube fluid, eg, water or sodium, in liquid and gas phases. The heating tube fluid may be under a higher pressure than the ORC working fluid in the inner area 308. The pressures used in the pipe section containing the ORC fluid and the pipe section containing the heating tube fluid, which may be at different pressures may be set to fix the desired boiling amount of the respective fluid. Additionally, spacers 404 can be used to help create the air compartments 406 as provide structural support for the heat exchange coil 202. These compartments 406 can be, for example, shaped toroids, ie, the spacers 404 can be spacers. Circulars between: the internal and external tube.

The pipe used in the heat exchanger may be of variable shapes and sizes to promote the desired heat exchange and to allow / assist in the desired self-circulation of the tube fluid heating, however the diameter of the external wall 302 is greater than I the diameter of the inner wall 306. For example, in some exemplary embodiments, the diameter of the innermost tube may be in the range of approximately 12.77 mm - 25.4 mm, the diameter of the outer tube! can be in the range of 25.4 mm - 50.8 mm. Separators 404 which connecting / supporting the inner wall 306 to the outer wall 302 may have a length in the range of 5 mm - 25.4 mm with a potential separation up to 152.4 mm between each separator. However, depending on the Heat exchanger design and use environment, can be used and other dimensions. Additionally, in accordance with the modalities I exemplifying, a capillary structure, for example, a capillary structure of wire mesh, it can cover (or partially cover) the 404 spacers and other heat exchange surfaces to allow the return flow of the Fluid heating tube fluid. The capillary tubes are configured to increase the heating tube fluid in its phase liquid carried in contact with the heated surface. In accordance with the exemplary modalities, compartment 406 is joined by spacers 404, inner wall 306 and outer wall 302.

Additionally, some of the 404 separators can be configured to allow fluid communication between selected adjacent compartments.

The heat exchange of the hot discharge gas to the ORC fluid can be done through a series of exemplary steps as shown in the flow chart of Figure 6. Initially convection from the hot discharge gas to the external wall of the heat exchanger 302 occurs in step 602. After a phase change, e.g., vaporization, of the heating tube fluid occurs on the inner surface of the outer wall 302 in step 604. The vaporized heating tube fluid flows towards the internal wall 306 in step 606. Condensation of the heating tube fluid occurs on the external surface of the inner wall 306 in step 608. On the ORC fluid side, convection (if preheating or superheating) or a phase change (if boiling) of the ORC fluid occurs on or near the inner wall 306 in step 610. Continuous return flow of the liquid heating tube fluid occurs toward the inner surface of outer wall 302 then occurs in compartment 404 (partly via capillaries on heat exchange surfaces and spacers 404) in step 612. In accordance with an exemplary alternative embodiment, evaporation and condensation of the fluid Heating tube does not need to occur, instead auto flotation-driven circulation can occur without evaporation and condensation drive mechanisms, as thermal differences within the compartment can trigger auto circulation which still results in the desired heat exchange occurring with the ORC fluid.

In accordance with other exemplary embodiments, the double wall tube configuration can improve safety in power generation systems. In an exemplary embodiment, the heating tube fluid in the outer section is at a higher pressure than the ORC fluid in the inner section. In this case, if a leak occurred between the inner and outer sections of the double-walled fluid tube ORC might not reach into the discharge conduit to become a fire hazard. Sensors can be used to monitor a heating tube fluid pressure such that if a leak occurs it could be detected and allow the system to be turned off. Similarly, should a leak occur that would allow the flow of the heating tube to enter the discharge conduit, the pressure loss could be detected and again allow a shutdown of the system. Additionally, heating tube fluids may be chosen which are flammable or significantly less flammable than the ORC fluid.

As described above, several exemplary configurations for the double-walled tube in the heat exchanger can be used. In accordance with other exemplary embodiments, this double-walled tube can be used in various heat exchanger designs, such as, for example, frame, tube and plate heat exchangers. Additionally, multiple double wall tubes can be used in parallel configurations.

In accordance with another exemplary embodiment, in lower temperature applications, an ORC system may be placed in the path of the exhaust gases without the use of a double-walled tube. In this case care must be taken to prevent the ORC fluid from leaking into the exhaust gas path. However, it is contemplated that low level leakage may occur which is difficult to detect. This low level leakage (very low speed leak of ORC fluid) can be a concern when the system is not in operation for extended periods of time. When the system is not in operation for extended periods of time, if a low level leak occurs allowing the ORC fluid to leak into the gas line system, an accumulation of ORC fluid in the general area of the heat exchanger may occur gases from the gas pipeline are not vented out after the heat exchanger. When this occurs, it is possible that enough ORC fluid accumulates in such a way that when the system is turned on again, the gases from the hot gas duct come into contact with the leaked ORC fluid, and burn or explode. In accordance with the exemplary embodiments, ventilation systems can be put in place to reduce and / or remove this risk as shown in Figure 7.

Under normal operations, the hot exhaust gas follows a path from the heat source through the coils of the heat exchanger 702 and out of an exhaust duct 714 as shown by the directional arrow 704. According to an exemplary embodiment, in this case, a diverter 706 is placed in a closed position A such that only the flow path available is the flow path shown by the directional arrow 704. However, there are times when the ORC system will not be operational. In this case, the escape follows the path designated by the directional arrow 708, and flows directly out of the atmosphere. To make this happen, the diverter 706 is placed in an open position B such that the only available flow path is the flow path shown by the directional arrow 708. As described above, if the power generation system is turned off for an extended period of time, and an ORC fluid leak has occurred that was too small to be detected while the unit was running; a flammable concentration of ORC fluid vapor may slowly build up over time within the discharge conduit.

In accordance with the exemplary embodiments, to avoid this, the diverter 710 is opened which allows air to enter the duct at this point and empty the area around the coils of the heat exchanger 702 in such a way that no appreciable amount of ORC fluids of fuel can remain in the area. The emptying air path is shown by the directional arrow path 712. Note that during normal operation the diverter 710 is in a closed position C. When is drained, several circulation methods can be used to introduce this air into the duct, for example, fans. Also, the controls for opening and closing the deviators 706 and 710 can be interconnected or not as desired. According to an exemplary embodiment, the coils of the heat exchanger 702 may be of the double-walled tube design described above.

Using the exemplary systems described above in accordance with the exemplary embodiments, a method for vaporizing an ORC fluid is shown in the flow chart of Figure 8. Initially a method for vaporizing an ORC fluid in a power generation system includes: transferring heat from a gas line gas in a discharge conduit through a first wall of a heat exchanger to a medium heating tube in step 802, changing a first phase of the medium heating tube from a liquid phase to a gaseous phase inside a compartment of the heat exchanger in step 804; transferring heat from the medium heating tube in the gas phase through a second wall to the ORC fluid which is contained within the heat exchanger 'within the discharge conduit in step 806, changing a second pass of the heating tube medium from the gas phase to the liquid phase in step 808; and vaporizing the ORC fluid in step 8 0.

The exemplary embodiments described above are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus the present invention is capable of many variations in the detailed implementation that can be derived from the description contained herein by a person skilled in the art. All variants and modifications are considered to be within the scope and spirit of the present invention as defined by the following claims. No element, act or instruction used in the description of the present application should be considered as critical or essential to the invention unless explicitly described as such. Also, as used herein, article "a" is intended to include one or more objects.

The written description uses examples to describe the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any embodied methods. The scope of the patentable invention is defined by the claims, and may include other examples that occur to one skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements within the literal language of the claims.

Claims

NOVELTY OF THE INVENTION CLAIMS

1 - . 1 - A system for power generation using a Cycle Organic Rankine (ORC), the system comprising: an exchange of I heat configured to be mounted inside a discharge duct that guide gases from the hot gas duct and having an inlet; and one output, the heat exchanger being configured to receive a current of liquid from a first fluid through the inlet and to generate a steam flow of the first fluid and the heat exchanger is configured to include a double wall tube, where the first fluid is arranged inside an inner wall of the double-walled tube and a second fluid is arranged inside the inner wall and an external wall of the double tube wall; an expander connected fluidly to the exchanger's outlet heat and configured to expand the vapor flow of the first fluid, to generate energy; a capacitor connected fluidly to an output of the expander and configured to receive and condense a vapor current i i expanded; and a pump connected fluidly to a condenser outlet and configured to receive the liquid stream of the first fluid :, for pressurize the fluid flow of the first fluid and to circulate the comment of liquid from the first fluid to the inlet of the heat exchanger.

2. - The system according to claim 1, further characterized in that the second fluid is selected from a group comprising water, sodium, thermal oil and thermal oil based on silicon.

3. - The system according to claim 1 or 2, further characterized in that it comprises a plurality of compartments having a volume between the inner wall and the outer wall, some of the plurality of compartments being adjacent and isolated from each other; and spacers configured to join the inner wall to the outer wall, wherein each compartment within the plurality of compartments is joined by the inner wall, the outer wall and one or more of the spacers.

4. - The system according to claim 3, further characterized in that the separators are configured to allow fluid communication between the selected compartments.

5. - The system according to claim 3 or 4, further characterized in that the second fluid self circulates due to a heat flow within the compartments when the gas gases of the hot gas boil the second fluid next to the external wall and the first fluid condenses the second fluid next to the inner wall.

6. - The system according to any of claims 3 to 5, further characterized in that the double-walled tube includes a first tube that forms the inner wall and has an internal diameter in the range of 12.77 - 25.4 mm and a second tube that forms the outer wall and has an internal diameter in the range of 25.4-50.8 such that the internal diameter of the second tube is always greater than the internal diameter of the first tube, in addition where a distance between the inner wall and the outer wall is between 12.7 mm and 25.4 mm

7. - The system according to any of the preceding claims, further characterized in that the first fluid is an ORC fluid and selected from a group comprising pentane, propan, cyclohexane, cyclopentane, butane, a fluorohydrocarbon, a ketone, an aromatic, and a combination thereof.

8. - The system according to any of the preceding claims, further characterized in that it comprises the discharge conduit; and a first diverter provided in the discharge conduit and configured to redirect gases from the hot gas conduit in the discharge conduit such that the escape of gases from the hot gas conduit evades the heat exchanger when the exchanger heat is in a non-operational condition.

9 -. 9 - The system according to claim 8, further characterized in that it additionally comprises a second diverter in the discharge conduit and configured to selectively open to allow air within the discharge conduit to empty gas away from the heat exchanger and into the atmosphere when The first diverter is in a closed position.

10. - A method for vaporizing an Organic Ránkine Cycle fluid (ORC) in a power generation system, the method comprising: transferring heat from a gas pipeline gas in a discharge conduit through a first wall of a heat exchanger. heat to a heating tube means which changes a first phase of the heating tube means from a liquid phase to a gas phase within a compartment of the heat exchanger; and vaporizing the ORC fluid when heat is transferred from the heating tube medium in the gas phase through a second wall to the ORC fluid which is contained within the heat exchanger inside the discharge conduit which changes a second phase of the heating tube means from the gas phase to the liquid phase, wherein the second wall is provided within the first wall.

1. The method according to claim 10, further characterized in that the fluid of the heating tube is selected from a group comprising water, sodium, thermal oil, silicon-based thermal oil.

12. The method according to claim 10 or 11, further characterized in that the ORC fluid is selected from a group comprising pentane, propane, cyclohexane, cyclopentane, butane, a fluorohydrocarbon, a ketone, an aromatic and a combination thereof.

13. - The method according to any of claims 0 to 12, further characterized in that a gas temperature of the gas conduit is in a temperature range of 35Q - 600 degrees Celsius.

14. The method according to any of claims 10 to 13, further characterized in that an average temperature of the ORC fluid is at an average temperature less than p equal to 240 degrees Celsius.

15. - The method according to any of claims 10 to 14, further characterized in that the fluid of the heating tube is self-circulating in the compartment.

16. The method according to any of claims 10 to 15, further characterized in that the heating fluid of the heating pipe is under a higher pressure than the ORC fluid.

17. - The method according to any of claims 10 to 16, further characterized in that the fluid of the heating drum is in a hermetically sealed volume.

18. - A heat exchanger in a discharge duct exposed directly to hot gas duct gases, the heat exchanger comprising: a first tube configured to receive a heating tube fluid and further includes a second tube, wherein a volume between the first tube and the second tube is hermetically sealed and divided into compartments which are joined by an internal wall of the first tube, an outer wall of the second tube and separating walls between the compartments; the second tube configured to receive a Organic Rankine Cycle (ORC) fluid; and separate walls configured to join the first tube to the second tube, the heat exchanger configured to receive heat from the gases of the hot gas conduit and configured to receive a liquid stream of the ORC fluid through the inlet and to generate a current of the ÓRC fluid vapor through an outlet.

19. - The heat exchanger according to claim 18, further characterized in that the distance between the internal wall of the first tube and the external wall of the second tube is between 12.7 mm and 25.4 mm.

20. - The heat exchanger according to claim 18 or 19, further characterized in that the first and second tubes enter and exit the discharge conduit multiple times.