Overheating device

Abstract

The invention relates to a superheating device comprising a combustion chamber (10) including a fuel inlet, an oxidizer inlet, and a heat inlet for receiving heat at an average temperature (Tm) between 150°C and 500°C, the combustion chamber being adapted to burn the fuel to heat and produce heat (Th) at a high temperature exceeding 600°C. Application to the construction of industrial installations requiring high-temperature thermal energy. Figure 1

Description

Title of the invention: Overheating device Technical field of the invention

[0001] The technical field of the invention relates to industrial installations where heat above 600°C is required for the large-scale production of gaseous products, for example dihydrogen H2 or ammonia NH3. State of the art

[0002] Many industrial processes require the large-scale use of heat and fluids at high temperatures, above 600°C. Examples include the production of dihydrogen (H2) by steam reforming of methane (CH4), the main process used today for dihydrogen production, or the production of dihydrogen by high-temperature water electrolysis, a process with a much higher yield than low-temperature water electrolysis using membrane devices, at temperatures in the range of 80°C to 100°C. The production of ammonia from dihydrogen and dinitrogen can also be mentioned.

[0003] In such processes, heat is conventionally supplied by the combustion of methane (CH4) and more generally by the combustion of products derived from fossil fuels. Such heating processes have the disadvantage of consuming non-renewable energy; they also have the disadvantage of producing CO2. Description of the invention

[0004] The invention proposes a technical solution to overcome all or part of the disadvantages described above.

[0005] To this end, the invention proposes a superheating device comprising a combustion chamber including a fuel inlet, an oxidizer inlet and a heat inlet to receive heat at an average temperature (Tm) between 150°C and 500°C, the combustion chamber being adapted to burn the fuel to heat and produce heat (Th) at a high temperature above 600°C.

[0006] The combustion reaction is initiated by the heat received by the combustion chamber. The invention thus proposes, from a heat source (i.e., thermal energy) at an average temperature below 500°C, to produce heat at a higher temperature above 600°C; coupled with a heat source at an average temperature, the device according to the invention thus forms a high-efficiency cogeneration unit. The invention therefore provides a heat source at a temperature sufficient to implement high-efficiency industrial processes temperature, from recovered energy or, more generally, from a greener energy source than the heating processes currently used in industry.

[0007] The invention also relates to an industrial installation comprising a superheating device as described above and a dihydrogen production device, one inlet of which is connected to the heat outlet of the superheating device and one outlet of which is connected to the fuel inlet of the superheating device. The high-temperature heat exiting the superheating device is thus used to produce dihydrogen, some of which is reintroduced as fuel into the combustion chamber to maintain the production of high-temperature heat. Figures

[0008] The invention will be better understood, and other features and advantages of the invention will become apparent from the following description of an example of an implementation of the invention. This example is given by way of non-limiting example. The description is to be read in conjunction with the accompanying drawings in which: • Figure [1] is a view of the essential device of the invention, • [Fig.2] is a view of an installation using the device of [Fig.1]

[0009] In the different figures, the identical elements, in their function or their structure, are referenced with the same reference points.

[0010] Traditionally, for physicists, heat is a form of thermal energy. By convention, within the framework of this invention, the term "heat" will be used to refer to a heat transfer fluid carrying thermal energy that is a function of the fluid's temperature and specific heat capacity, and the term "temperature of heat" will be used to refer to the temperature of the heat transfer fluid carrying the associated thermal energy. The following terms are also defined: an "average" temperature is a temperature between 150°C and 500°C, and a "high" temperature is a temperature above 600°C. Detailed description

[0011] As stated previously, the invention relates to a superheating device 10 comprising a combustion chamber 11 including a fuel inlet, an oxidizer inlet, and a heat inlet for receiving heat at an average temperature Tm between 150°C and 500°C, the combustion chamber being adapted to burn the fuel and the oxidizer to heat and produce heat at a high temperature Th exceeding 600°C. The heat (or heat transfer fluid) may be steam or any other suitable heat transfer fluid.

[0012] The superheating device can thus be seen as a device that produces heat, that is, thermal energy, at a high temperature. Ideally, The superheating device according to the invention is inserted into an industrial installation; it receives so-called "waste" heat from the operation of an industrial process or a power generation unit and provides heat at a higher temperature to enable the operation of another industrial process. In some applications, the difference between the high temperature and the average temperature may be small. Nevertheless, some thermochemical industrial processes require a minimum temperature, in addition to a certain amount of energy.

[0013] The fuel is preferably gaseous dihydrogen (H2) and the oxidizer is a gas comprising gaseous dioxygen (O2); the combustion chamber is arranged to carry out a combustion reaction of dihydrogen (2H2 + O2 → H2O), a reaction known for its significant exothermic properties and calorific value. The heat from combustion is used to heat and produce high-temperature heat. The combustion reaction is initiated by the heat received by the combustion chamber.

[0014] The oxidizer can be air containing approximately 21% dioxygen, which is necessary for the combustion of dihydrogen. The drawback is the undesirable co-production of nitrogen oxides (commonly called NOx) due to the presence of nitrogen in the air. Advantageously, the oxidizer can be gaseous dioxygen (O2) to implement oxycombustion. By excluding nitrogen from the combustion, the flame temperature increases, which raises the temperature of the second heat transfer fluid and increases the efficiency of the device (in terms of the amount of heat produced). Also, the amount of fumes generated is limited, and the production of nitrogen oxides is avoided.

[0015] The superheating device also includes a control means configured to control the operation of the combustion chamber. In particular, the control means adjusts the fuel flow rate and the oxidizer flow rate to optimize combustion efficiency. The control means takes into account the temperature and the amount of heat entering the combustion chamber, and the desired temperature and amount of heat exiting the combustion chamber. Specifically, the control means adjusts the fuel flow rate and the oxidizer flow rate to achieve stoichiometric combustion by supplying, in the combustion chamber, one mole of O2 for every two moles of H2.

[0016] The superheating device shown [Fig. 1] also includes an outlet heat exchanger 12 comprising a primary circuit, one inlet of which is connected to a heat outlet of the combustion chamber 11. The "cold" outlet of the primary circuit (not shown [Fig. 1]) is conventionally connected to an inlet of the combustion chamber. The heat exchanger 12 also conventionally includes a circuit The secondary circuit is thermally coupled to the primary circuit to ensure heat transfer from the primary to the secondary circuit. The secondary circuit comprises a heat output coupled to a heat input of a heat-consuming device (not shown [Fig. 1]) at a high temperature Th, and a "cold" input connected to an output of the heat-consuming device. As is typical, in both the primary and secondary circuits, heat energy is transported by a suitable heat transfer fluid.

[0017] In an alternative (not shown), the outlet exchanger comprises only a secondary circuit placed at the outlet of the combustion chamber and whose heat output is coupled to a heat input of the high-temperature heat-consuming device.

[0018] Finally, the pure water produced in the combustion chamber in the form of vapor can be condensed and reused in processes where demineralized water is required, such as the electrolysis of water for the purpose of producing dihydrogen.

[0019] The device according to the invention may further include a heat source 20 supplying heat at the average temperature, and an inlet exchanger 30 comprising a primary circuit having an inlet connected (solid arrow) to a heat outlet of the heat source and a secondary circuit having an outlet connected (solid arrow) to a heat inlet of the combustion chamber to supply heat at average temperature Tm to the combustion chamber.

[0020] The heat source can be of any type capable of heating a heat transfer fluid to an average temperature of 150°C to 500°C. For example, the heat source can be a waste heat recovery device from an industrial plant. The heat source can also be a fourth-generation nuclear reactor such as a lead-cooled fast reactor (LFR) or a sodium-cooled fast reactor (SFR). The device according to the invention is thus used in a cogeneration plant for reusing the heat co-produced by the source, which primarily produces another form of energy (for example, electrical energy) or another product.

[0021] The inlet heat exchanger 30 and the heat transfer fluids used to transport heat in the primary and secondary circuits of the heat exchanger 30 are chosen, in particular, according to the heat source 20, the quantities of heat to be transferred, and the temperature Tm of the heat to be transferred. The heat exchanger is, for example, a spiral heat exchanger optimized for heat transfer between the primary and secondary circuits at an average temperature between 150 and 500°C. In the case where the heat source is a lead-cooled reactor, the heat transfer fluid used in the primary circuit will be lead, and the heat transfer fluid used in the secondary circuit will be, for example, water.

[0022] The superheating device according to the invention can be used in any industrial installation requiring heat (energy) at a high temperature.

[0023] A first envisaged application is the construction of an installation comprising a superheating device 10 as described above and a dihydrogen production device 40, the heat inlet of which is connected (solid arrow) to the heat outlet of the superheating device 10 to receive the high-temperature heat Th, and the outlet of which is connected (dashed arrow) to the fuel inlet of the superheating device. The high-temperature heat exiting the superheating device is thus used to produce dihydrogen, a portion of which is then reintroduced as fuel into the combustion chamber to maintain the production of high-temperature heat.As an example, 6 to 13 kg of dihydrogen reintroduced into the superheating device can make it possible to obtain, from an input heat of between 150 and 500°C, an output heat of 850°C, while avoiding the cracking of the water, a phenomenon that appears for water vapor at 850°C (in the case where the heat is in the form of water vapor).

[0024] Similarly, if the hydrogen production process used generates oxygen as a co-product, the oxygen can be reintroduced into the combustion chamber. The complete installation is thus self-sufficient in hydrogen and possibly also in oxygen for heat production, while simultaneously producing hydrogen on a large scale.

[0025] Ideally, the dihydrogen production device 40 is configured to implement a dihydrogen production process at a temperature above 600°C; for example, a reforming process or pyrolysis of a petroleum product (methane, ethanol, etc.). These processes are currently the most widely used for producing dihydrogen; the invention makes them more environmentally friendly by using heat from the combustion of dihydrogen rather than heat from the combustion of petroleum products, as is currently the case.

[0026] Alternatively, the dihydrogen production device can implement a high-temperature water electrolysis process, in particular with solid oxides (or SOEC - Solid Oxide Electroliser Cell), which has an interesting yield in terms of heat transformation into chemical energy H2.

[0027] Other applications of the invention can be envisaged. For example, a superheating device can be coupled to an ammonia (NH3) production plant. Since ammonia is produced essentially from dihydrogen (H2) and dinitrogen, some of the dihydrogen produced or introduced into the plant can be reinjected into the combustion chamber.

Claims

Demands

1. Industrial installation comprising - a superheating device (10) comprising a combustion chamber (11) comprising a fuel inlet, an oxidizer inlet and a heat inlet for receiving heat at an average temperature (Tm) between 150°C and 500°C, the combustion chamber being adapted to burn the fuel to heat and produce heat (Th) at a high temperature above 600°C on a heat outlet, and - a dihydrogen production device (40) having an inlet connected to the heat outlet of the superheating device and an outlet connected to the fuel inlet of the superheating device.

2. Installation according to claim 1 wherein the fuel is gaseous dihydrogen (H2), wherein the oxidizer is a gas comprising gaseous dioxygen (O2) and wherein the combustion chamber is arranged to carry out a combustion reaction of dihydrogen 2H2 + O2 —> H2O.

3. An installation according to any one of the preceding claims comprising an adjustment means configured to adjust an oxidant flow rate and a fuel flow rate to achieve stoichiometric combustion.

4. Installation according to any one of the preceding claims also comprising an outlet heat exchanger (12) comprising a primary circuit having an inlet connected to a heat outlet of the combustion chamber (10).

5. Installation according to any one of the preceding claims, also comprising a heat source (20) supplying heat at the average temperature, and a heat inlet exchanger comprising a primary circuit having a hot inlet connected to an outlet of the heat source and a secondary circuit having a hot outlet connected to a heat inlet of the combustion chamber.

6. Installation according to the preceding claim, wherein the dihydrogen production device is configured to implement a process for producing dihydrogen at a temperature above 600°C, of ​​the type of reforming process or pyrolysis process of a petroleum product or high-temperature water electrolysis process.

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