FR2863042A1 - High temperature heat extractor, especially for nuclear reactor, uses direct contact between two fluids such as a liquid and a gas that are separated by centrifuging - Google Patents

Abstract

The heat extractor, designed to transfer heat between a boiler and a circuit able to transform or utilize the energy, uses direct contact between two fluids (8, 9) by the diffusion of gas bubbles from one fluid in the liquid of the other, and then separating the two fluids by centrifuging once the heat transfer has taken place. The bubble diffuser consists of profiled bars (11) with an aperture in a depression zone, enabling the gas (9), e.g. helium, CO2 or nitrogen, to be drawn in by the circulation of the other fluid (8), such as a molten metal, without causing a substantial load loss in the latter.

Description

Field of the Invention

  The present invention makes it possible to extract heat from a boiler at high temperature.

  The present invention is applicable to all types of boilers. It adapts with advantages to the evacuation of the heat produced by a nuclear reactor.

  The invention is applicable to all types of reactors whether pressurized, boiling, gaseous coolant, molten metal, molten salt, or even heavy water.

  It is, for boilers or high temperature reactors, a device optimizing the heat exchange and avoiding corrosion.

  The invention is constituted both by the device, by the various schemes of principles and by the methods which implement this device.

  State of the Prior Art and Problems posed To exchange the heat from any boiler, tube or plate heat exchangers are used.

  To achieve this exchange, there is a capacity in which circulates one of the fluids through the pipes arranged in the capacity. In this capacity circulates the other fluid.

  The fluid to be heated can circulate indifferently in the capacity or in the tubes. The direction of the fluids can be opposite or parallel.

  The tubes are generally connected to a plenum by a spacer plate.

  In the current technique, a fluid flowing in a tube causes a vibration on the one hand, and mechanical wear on the other hand which can cause cutting or piercing of the tube. In a nuclear reactor, the evacuation of temperature has a crucial role on which the safety of the reactor depends.

  Plate heat exchangers can not be used for high temperatures. 30 35

  DESCRIPTION OF THE INVENTION Detailed explanation of the operation of the heat exchanger device 10.

  Figures N 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23 show the preferred configuration of the device according to the invention.

  The explanation of the operation will be easily understood on reading the description of these parts and their role in the device.

  The device (10) is shown in FIGS. 1, 2, 4, 5, 7, 8, 9, 10, 11, 12, in its various possible uses for the case of nuclear reactors and in FIGS. 13 to 23 for its principle and its different variants.

  At the inlet of the device (10), a liquid fluid (8) penetrates, it passes through a part (11), shown in plan view in FIG. 14.

  This part (11) consists of gas diffuser bars which can be profiled to reduce the pressure drops in the device (10).

  FIG. 14 represents a distribution of these diffusers in the form of a grid. The addition of other diffusers, or other types of diffusers will be possible variants according to the invention.

  Figure N shows one of the possible shapes of these diffuser bars.

  One could also consider other types of diffusers, or other places to diffuse the gas (9) within the liquid (8).

  Figure N 18 proposes two other possible examples among the various possible solutions, wherein the gas diffuses through the central diffuser core (9a) and the walls (9b) of the restriction (44) around the central core (45).

  In the preferred application according to the invention, all of these gas diffusers are used to obtain the most homogeneous mixture possible.

  The gas (9) can be, for example, selected from gases such as helium, carbon dioxide, nitrogen, or a mixture of several gases. It may also be constituted by a liquid, for example water, chosen to be in the form of steam at the operating temperature of the exchanger (10).

  The liquid (8) may be, for example, constituted by a liquid metal such as sodium, gallium, cadmium, indium, lead, tin, potassium, by metal alloys, or by salts melted, for example sodium chloride. Fluids (8) and (9) must be chemically compatible.

  At a judiciously chosen distance, there is provided, as shown in FIGS. 18 or 19, a diffuser core (45) which can also serve as a gas diffuser.

  This core is preferably positioned in the vertical axis of the device (10) and can be completed with a necking (44). It makes it possible to generate a more homogeneous mixture between the liquid and the gas.

  When extended, as shown in Figure N 18, by a propeller (48), it rotates the mixture.

  At the outlet of the mixing core (45), the mixture of the fluids (8) and (9) is accelerated and then rotated by a propeller (12) positioned on the edges of the device and by the propeller (48), which optionally extends the mixer core. Once the fluid mixture has been rotated, the difference in density between the two fluids makes it possible to separate the gas, now heated, from the liquid by centrifugation.

  This separation will be all the more effective as the liquid will be dense. This principle therefore works particularly well with metals or liquid metal alloys.

  The propeller (12) can be chosen with a recess, decreasing progressively with the path of the fluid, to reach the dimensions of the inlet cone constituted by the piece (22). This piece (22) also serves as a collector for the degassed fluid (8) which directs the degassed liquid to the circuit concerned.

  One can, for example, consider the multiplication of these propellers or a configuration in which they would occupy no longer the inner wall of the exchanger device (10), but would be distributed on the surface of this same device.

  The gas (9) is collected by the cone of the workpiece (22) and then passes through the workpiece (13). This piece (13) is shown in Figures 35 N 20 in plan view and N 21 in section AA.

  These two figures represent a possible configuration of this part (13) whose purpose is to retain the droplets of liquid that could have been carried by the gas flow.

  The number of pieces (13) is a function of the speed of the gas (9). Their arrangement between them is judiciously distributed. They may for example have their gate slightly offset angularly so that the superposition of their hole covers the entire section of the exchanger (10).

  At the upper outlets of the device (10), there is therefore, on the one hand, a gas, and on the other hand a liquid.

  The device (10) can be used, as described later with several types of reactors and even for other applications where heat transfer with high efficiency is important.

  Three different operations of this device can therefore be described: Either the device is used in a process where a gas is heated by a heat source and the device (10) makes it possible to transfer this heat to a liquid.

  Either the device is used in a process where a liquid is heated by a heat source and the device (10) transfers this heat to a gas.

  Either the device is used in a process where a gas is heated by a heat source and a first device (10) transfers this heat to a liquid which serves as heat transport to a second device (10) which itself it transfers this energy to a gas, thus making it possible to heat a gas indirectly and without possible mixing with the aid of another gas.

  Thus, through the device (10), a heat exchange between a liquid and a gas, or a liquid and a liquid in the vapor phase, without exchange tubes or plates. This principle allows to remove the tubes or plates that create a loss of load, and are subject to corrosion.

  Application Case According to the Invention, Description of the Figures The case of FIG. 1 represents the preferred application case according to the invention. The heat source is a nuclear reactor whose heat transfer fluid is a gas, for example helium.

  The gaseous fluid (9) is circulated by the pump (16). It passes through the nuclear core (1).

  The fluid (9) may be a gas or a liquid having a vaporization point lower than the fluid temperature (8) at the inlet of the device (10).

  The gas (9), or the vaporized liquid, enters the room (11).

  The gaseous fluid (9) circulates under the action of a pump (16), is heated by passing through the heat source (1) constituted by the nuclear reactor core positioned in the tank (2) by the piece (4). ). It emerges from the tank (2) and enters the room (11) and the holes made for this purpose in the rooms (44) and (45), a subassembly of the device (10). the liquid (8) and warms up.

  The various parts constituting the device mix the fluids 15 (8) and (9).

  In the preferred case according to the invention, represented in FIG. 1, the fluid (9) circulating in the reactor is, for example, a gas such as helium, carbon dioxide or nitrogen.

  The fluid (8) flowing in the circuit (25) is an electrically conductive liquid at the operating temperature. It may be, for example constituted by a liquid metal such as sodium, gallium, cadmium, indium, lead, tin, potassium, or by molten salts, for example sodium chloride.

  At the outlet of the device (10), the fluids (8) and (9) are separated. The fluid (8) is thus heated by the fluid (9).

  The fluid (8) thus passes with less energy loss and less loss of speed through the heat exchanger (10). The speed of the fluid (8) is generated both by the entrainment of the fluid (8), by the gas (9) flowing in the circuit (24), by the decrease in the density of the mixture obtained which push the bubbles towards the top by making them grow according to the buoyancy and the temperature difference between the place where the piece (11) and the place where the piece (22) is located. Between these two points, the difference in temperature generates a thermosiphon which, by density effect, contributes to the movement of the fluid (8).

  The movement of this fluid (8) is directly transformed into electricity by an electromagnetic device (17). This device may consist of a linear electromagnetic generator. This generator is made using a winding of conductors around the pipe but electrically insulated; two electrodes (6) and (7), distant from each other by a sufficient length, polarize the fluid (8). When the fluid (8) thus polarized passes inside the coil, it generates a current. This device operates according to Faraday's law which governs the movement of a conductor in a magnetic field.

  The entire system, nuclear reactor, pump, exchanger, electromagnetic device, therefore constitutes an assembly capable of minimizing the pressure losses created, in conventional systems of exchangers by the presence of the tubes and the friction or loss of energy related the rotation of a turbine or the inability to convert all the heat produced into electricity.

  FIG. 2 represents the application of the invention to another type of reactor in which the fluid heated by the reactor is an electrically conductive liquid (8). The fluid (9) may be a gas or a liquid having a vaporization point lower than the fluid temperature (8) at the inlet of the device (10). The fluid (8) may be, for example, constituted by a liquid metal such as sodium, gallium, cadmium, indium, lead, tin, potassium, or by molten salts, for example sodium chloride. Fluids (8) and (9) must be chemically compatible.

  The fluid (8) is circulated by the pump (5). In this case, an electromagnetic pump has been chosen. The fluid (8) passes into the heat source (1). Here a nuclear reactor core. It heats up and then enters the device (10) according to the invention where it drives with its speed a gas (9) diffused from the diffuser (11), the diffuser core (45), and the necking (44) then as before the two fluids are mixed, exchange their heat, then are separated to return, once this exchange made in their respective circuit.

  The heated gas rotates a turbine (14) and possibly a turbine (15). These two turbines can be replaced, without the process being changed, by any other element able to transform the kinetic and thermal energy of the gas into another usable energy.

  After the turbine 15, the gas reaches the room 11 for a new cycle.

  Figure 2 is particularly applicable to nuclear breeder reactors and solves the problems of heat extraction.

  It makes it possible to safely use sodium as fluid (8), and for example nitrogen or helium as gas (9) to extract heat.

  This breeder reactor has the advantage of being compact.

  FIG. 3 represents the same operating principle as FIG. (2), but in this case the fluid (9) used is a condensable gas. For example, water can advantageously be used as a condensable fluid.

  It is advantageously possible to add to the preceding device heater (20) able to bring the water to a temperature close to that of its vaporization point, and optionally a condenser (19) and a circulation pump (16).

  FIG. 4 represents another variant of the application according to the invention for which a gas reactor equipped with a heat exchanger according to the invention is used, as explained for FIG. 1, associated with a secondary circuit containing a fluid (8). The fluid (8) may be, for example, constituted by a liquid metal such as sodium, gallium, cadmium, indium, lead, tin, potassium, or by molten salts, for example sodium chloride. The fluid (37) of the circuit (36) may be, for example, helium or carbon dioxide, but it may also be a liquid. Fluids (8) and (9) and (37) must be chemically compatible. The circuit containing the fluid (8) operates on the same principle as FIG. 2. The combination of the operation explained for FIG. 1 and that used in FIG. 2 makes it possible, when they are associated, to produce a gas reactor. , for example a high temperature helium reactor, and to rotate a hot air turbine or a turbine operating with carbon dioxide or any other gas and this with optimum thermal efficiency.

  The circuit (36) can even be opened and suck and reject the outside air.

  In another variant according to the invention shown in FIG. 5, the current generator is associated with a device (30), a tank (31), electrodes (32) and (33), in order to produce a high temperature electrolysis. by passing the pipe (25) into the tank (31) where it heats the fluid (29) and thus improves the efficiency of the electrolysis of the product (29).

  This product (29) may optionally be water, the electrolysis then generating hydrogen and oxygen.

  This principle allows alternating or mixing the production of electricity to an electrical network and that to the electrolysis bin.

  FIG. 6 represents a similar application for a reactor whose heat transfer fluid is a gas, equipped with a conventional liquid gas heat exchanger and a secondary circuit in the liquid phase. In this case, the exchanger heating the ancillary application, such as electrolysis, is located on the primary circuit of the reactor, ie on the fluid heated directly by the heat source constituted by the nuclear reactor.

  FIG. 7 represents an application similar to the applications described in FIGS. 5 and 6 for a reactor whose heat transfer fluid is a gas, provided with a liquid gas heat exchanger according to the invention. The circuit responsible for heating the electrolytic bath, or possibly an auxiliary application requiring a heat transfer, is constituted in this case by a conventional exchanger.

  FIG. 8 represents an application similar to the applications described in FIGS. 5, 6 and 7 for a reactor whose heat transfer fluid is a liquid, equipped with a liquid gas heat exchanger according to the invention and a secondary gas circuit. . In this case, the exchanger heating the ancillary application, such as electrolysis, is located on the primary circuit of the reactor which conveys the fluid in the liquid phase.

  This arrangement improves the heat exchange.

  In FIG. 9, a device (10) is used for transferring heat from the reactor to the liquid circuit (8) requiring the supply of heat. In this application, there is described an installation for electrolysis at high temperature to increase the efficiency.

  After heating this auxiliary circuit, there is still enough heat to operate a second heat exchanger. This last circuit works in thermosiphon and produces electricity according to the principles described for scheme N 1.

  The use of a device (10) makes it possible to increase the efficiency of the heat transfer and thus ultimately the efficiency of the electrolysis.

  FIG. 10 represents the same type of device as the preceding figures, but in this case, the gas (9) heats inside an exchanger (10a), according to the invention, directly the liquid (8) to be the subject of a chemical or electrochemical transformation, for example an electrolysis. Any fluid supply (8) is made via the valve (43).

  The gas (9) then passes into a second exchanger (10b) according to the invention, where it transfers energy to another circuit, for example charged with generating electricity.

  One can, of course, multiply the number of heat exchangers in the process.

  In the case of Figure 10, the circuit (46) contains a conductive liquid (37). The energy is recovered by a magnetic device (17).

  FIG. 11 represents an application similar to FIG. 10, in which the circuit (49) equipped with a condenser (19b) and a pump contains a condensable fluid (37). The energy is recovered by a turbine (14) possibly associated with a turbine (15).

  FIG. 12 represents a liquid phase heat transfer fluid reactor (8) which directly heats the fluid (9), which is a condensable liquid, for example water.

  This liquid is vaporized in the exchanger 10 and heated. The turbines (14) and optionally (15) generate electricity, a condenser (19) returns the fluid (9) in the liquid phase. It then undergoes its process of chemical or electrochemical transformation at high temperature and then circulates in the circuit after a possible input via the valve (43).

  Figure 13 shows the heat exchanger device in section. Figure 14 shows part II, constituting one of the gas diffusers. Figure 15 shows one of the possible forms of the diffuser element. i0

  Figures 16 and 17 show the part (12).

  Figure 18 shows the necking (44), the helix (12), a diffuser core (45) extended a helix (48).

  Figure 19 shows another necking (50), the propeller (12), another diffuser (45) extended by a central core shaped drop of water (40). Figures 20 and 21 show the part 13 in plan view and in section.

  Figures 22 and 23 show the part 22 in plan view and in section.

  Advantages of the invention The invention is advantageously applicable for all types of nuclear reactors or to all applications requiring heat transfer or having to operate at very high temperatures.

  The invention allows the transfer of heat by simplifying the circuits, minimizing corrosion, minimizing losses and risks.

  It is advantageously applied to high temperature gas nuclear reactors (VHTR), fast breeder nuclear reactors.

  It allows the increase of the yield of the chemical or electrochemical processes by simply heating these circuits.

30 He

Claims (16)

  1. Device for ensuring the transfer of heat between a boiler and a circuit capable of transforming or using this energy, or between two circuits, characterized in that the heat exchange is done by direct contact between the two fluids (8) and (9), by the diffusion of gas bubbles corresponding to one of the fluids which diffuses into the other fluid and thus proceeds to the transfer of heat, and then to separate these two fluids once the heat transfer has been effected .   2. Device according to claim 1 characterized in that the bubble diffuser is constituted by profiled bars (11) provided with a hole in a vacuum zone, so that the gas (9) is sucked by the circulation of the other fluid (8), without generating a significant pressure drop in the other fluid.   3. Device according to claim 1 characterized in that the gas bubbles (9) are separated from the other fluid (8) by centrifugation using one or more propellers (12) and (48) drilled with a hole in their center.   4. Device according to claims 1 and 3 characterized in that the space in the center of the propellers (12) is not constant over the height to allow a better separation of the gas bubbles and the liquid.   5. Device according to claim 1 characterized in that the gas bubbles (9) and the liquid fluid (8) are collected after separation by a divergent (13) for the gas and a toroidal collector (22) for the liquid.   6. Device according to claim 1 characterized in that a bulb (45) is positioned in the device to serve as a diffuser core.   7 Device according to claim 1 and claim 6 characterized in that the bulb (45) positioned in the device is extended by one or more propellers (48).   8 Device according to claim 1 and claims 6 and 7 characterized in that the gas (9a) is diffused by the bulb (45) for a diffusion of the gas at the center of the fluid (8).   9 Device according to Claim 1 and Claims 6 to 8, characterized in that the gas (9b) is diffused by the walls of the retreint (44) in which the bulb (45) is positioned for diffusion of the gas at the center of the fluid ( 8).   10. Nuclear reactor using the device according to any one of claims 1 to 9, characterized in that the fluid (9) passing through the boiler is a gas, the thermal energy is extracted from the circuit heated by a heat exchanger. bubbles, the thermal energy is transformed into movement of the liquid fluid (8) by a thermosiphon phenomenon, this movement is converted into current by an electromagnetic device (17).   11. Nuclear reactor using the device according to any one of claims 1 to 9, characterized in that the fluid (8) passing through the boiler is a liquid fluid, the heat energy is extracted from the circuit heated by a heat exchanger with bubbles, the thermal energy is transformed into a movement of the gaseous fluid (9) by a phenomenon of expansion then contraction of the gas (9), this movement is transformed into current by a turbine (14) or turbines (14) and ( 15).   12. Nuclear reactor using the device according to any one of claims 1 to 9, characterized in that the fluid (8) passing through the boiler is a liquid fluid, the heat energy is extracted from the circuit heated by a heat exchanger with bubbles, the thermal energy vaporizes the fluid (9). The energy transmitted to this fluid (9) is transformed into motion. This movement is converted into current by a turbine (14) and possibly another turbine (15). This fluid (9) is condensed in a device (19), then possibly circulated by a pump (16) and possibly heated by an exchanger (20).   13. Nuclear reactor using the device according to any one of claims 1 to 9, characterized in that the fluid (9) passing through the boiler is a gas, the heat energy is extracted from the circuit heated by a first heat exchanger with bubbles (10a), the thermal energy is transferred to the liquid fluid (8) which circulates in an intermediate circuit (25) and then passes into a second bubble heat exchanger device (10b) to exchange with a fluid (37) in gas inside the second exchanger (10b).   14. Nuclear reactor according to claim 12, characterized in that the liquid fluid (8) flowing in the circuit (25) intermediate exchangers (10a) and (10b) passes into a device containing a fluid to heat and improve. the yield of a chemical or electrochemical process such as electrolysis.   15. Nuclear reactor using the device according to any one of claims 1 to 9, characterized in that the fluid (9) passing through the boiler is a gas. It heats directly in a first bubble heat exchanger (10a), the liquid fluid (8) subjected to a chemical or electrochemical process such as an electrolysis which circulates in a circuit (25), then passes into a second exchanger device bubble heat (10b) for exchanging with a fluid (37) to heat it in turn and produce for example electricity.   16. Nuclear reactor using the device according to any one of claims 1 to 9, characterized in that the fluid (8) passing through the boiler is a conductive liquid which vaporizes directly into the bubble heat exchanger (10), the fluid (9) which condenses after passing through one or more turbines and a condenser (19) into a portion of the circuit (25) where a chemical or electrochemical process such as electrolysis is performed.