STEAM AND ELECTRICITY GENERATION SYSTEM, PARTICULARLY FOR AN ELECTRIFIED STEAM CRACKER REACTION ZONE

Abstract

The invention relates to a method and system for generating steam and electricity, comprising a first electrical heat production system (20) and a second heat and electricity production system (30) comprising: (a) a heat exchanger (32) connected to a water-supplied conduit (2), (b) a thermodynamic machine (33) producing hot gases circulating inside the heat exchanger (32) to transfer heat to the water circulating in the exchanger, (c) a thermal storage system (34) coupled to the circuit (330) of the thermodynamic machine (33), (d) a heating device (340) for the thermal storage system, and (e) an electrical generator (36) driven by a turbine of the thermodynamic machine. The heat required for the thermodynamic machine to operate and produce hot gases is supplied by the thermal storage system during its discharge phase. Figure 1.

Description

Title of the invention: STEAM AND ELECTRICITY GENERATION SYSTEM, PARTICULARLY FOR AN ELECTRIFIED STEAM CRACKER REACTION ZONE Technical field of the invention

[0001] The present invention relates to a steam and electricity generation system, particularly for an electrified steam cracking reaction zone, as well as a steam cracking plant equipped with such a system. The invention also relates to a steam production process and a steam cracking process. Technological background

[0002] The hydrocarbon steam cracking process makes it possible to produce light olefins, and more particularly ethylene and propylene. It consists of thermally cracking a mixture of hydrocarbons and steam in one or more reactors at high temperatures of around 800 to 850 °C and under low pressures (1 to 3 bar) to break the carbon-hydrogen and / or carbon-carbon bonds and produce unsaturated hydrocarbons in the reactor(s). The effluents exiting the reactor(s) are then quenched in one or more heat exchangers, generally designated by the acronyms TLX or TLE ("Transfer Line Exchanger"), in order to limit secondary reactions such as the polymerization of olefins, dienes, and acetylenes. The cooled effluents are then fractionated.A steam cracking process requires both heat input (energy injection to raise the temperature and provide the enthalpy of reaction) and cooling input (energy extraction to lower the temperature) for fractionation, as well as significant amounts of energy, much of which is currently supplied by fossil fuels. The steam cracking reaction also requires steam for hydrocarbon cracking. Steam cracking plants powered by fossil fuels have the advantage of producing sufficient steam to carry out the reaction.

[0003] Increasingly important environmental concerns, however, require replacing the fossil fuel traditionally used to provide the heat needed for steam cracking with decarbonized energy (without CO2 emissions) and in particular renewable energy, and especially renewable electricity produced by wind turbines and / or solar panels.

[0004] This is how electrified steam cracking furnaces were developed. However, the quantities of steam produced by installations using electrified furnaces are lower than the quantities of steam produced by installations using combustion furnaces. It is therefore necessary to generate additional steam, and in particular at a lower cost.

[0005] The invention aims to provide a steam and electricity generation system, not using fossil energy, allowing the generation of steam and electricity at a lower environmental cost and under viable economic conditions. Summary of the invention

[0006] To this end, the invention proposes a system for generating electric steam and electricity implementing a thermal storage system.

[0007] A first object of the invention relates to a steam and electricity generation system, in particular for an electrified steam cracking reaction zone, comprising at least: - a water-supplied pipe, - a first electrical heat production system connected to the pipe so as to transfer heat to the water circulating in the pipe, - a second heat and electricity production system comprising: (a) a heat exchanger connected to the pipe, the water supplied by the pipe circulating inside the heat exchanger, (b) a thermodynamic machine comprising a circuit in which a gas circulates, this circuit comprising, mounted in series in the direction of gas flow: at least one rotating machine capable of compressing the gas or heating it by shock waves, a turbine connected to at least one rotating machine to drive it, the gases exiting the turbine circulating inside the heat exchanger in order to transfer the calories from the gas to the water circulating in the exchanger, (c) a thermal storage system, coupled to the thermodynamic machine circuit upstream of the turbine, (d) a heating device for the thermal storage system, (e) an electric generator driven by the turbine of the thermodynamic machine, - a management system for the first heat production system and the second heat and electricity production system, configured, in particular programmed, to: (i) during a charging phase of the thermal storage system, operate the heating device of the thermal storage system so that the latter accumulates heat, the turbine, the electric generator, and optionally at least one rotating machine, of the second heat and electricity production system being stopped, and operate the first heat production system to produce steam, (ii) in a discharge phase of the thermal storage system, operate at least one rotating machine and the turbine of the second heat and power generation system to produce steam and electricity, the gases entering the turbine being heated by the thermal storage system and the electric generator being driven by the turbine, the first heat generation system being either stopped or providing less thermal power than that supplied in the charging phase.

[0008] The use of a heat and power generation system coupled with a thermal storage system makes it possible to use electricity during the charging phase, which is cheaper and / or from renewable sources, to accumulate thermal energy that can be used during the discharge phase to generate both steam and electricity. Such an arrangement is therefore particularly advantageous economically and / or environmentally. In particular, the generator can produce electricity during the discharge phase, which can be reused in the steam cracking plant, for the operation of an electrified steam cracking reaction zone, or for other equipment in a steam cracking plant, or for any equipment in a plant comprising the steam and power generation system of the invention.

[0009] In particular, the management system may be configured, in particular programmed, to command a charging phase when electricity is cheaper and / or comes from renewable and / or non-fossil energy sources, and to command a discharging phase when electricity is more expensive and / or comes from renewable and / or non-fossil energy sources.

[0010] The first and second heat production systems can be sized to provide sufficient thermal energy in the form of calories, individually or together, to the water supplied by the water-fed pipe in order to vaporize it. They can thus be connected in parallel or in series depending on their capacity.

[0011] By "rotating machine" is meant a machine comprising a rotating shaft, and typically equipped with one or more blades transferring energy to a fluid. Generally, if the energy transfer occurs from the rotor to the fluid, it is either a pump or a fan / compressor. Conversely, if the energy transfer occurs from the fluid to the rotor, then the machine is called a turbine.

[0012] In a first preferred embodiment, at least one rotating machine of the thermodynamic machine is a compressor capable of compressing the gas. The heating device of the thermal storage system is then separate from and independent of the rotating machine (i.e., the compressor). The at least one rotating machine is also then at rest during the charging phase.

[0013] In a second embodiment, at least one rotating machine of the thermodynamic machine is capable of heating the gas by shock waves. The heating device of the thermal storage system is then constituted by the rotating machine. This rotating machine operates during the charging phase, while the turbine and the electric generator are at rest. During this charging phase, the rotating machine is driven by its own electric motor and disconnected from the turbine. The turbine can thus be connected to the rotating machine by coupling means suitable for coupling the rotating machine to the turbine during the discharge phase and decoupling it during the charging phase.

[0014] In both embodiments, during the discharge phase, the turbine drives the rotating machine in rotation. Thus, in the first embodiment, the turbine can be permanently coupled to the rotating machine.

[0015] Advantageously, the first electrical heat production system may comprise one or more of the following components mounted in series and / or in parallel on at least one water-supplied pipe:

[0016] - a heat pump connected on the one hand to the water-supplied pipe of in order to transmit calories to it and on the other hand to a pipe in which a hot fluid circulates so as to receive calories from the latter,

[0017] - a mechanical vapor recompression system, comprising at least one stage of mechanical compression of water vapor, at least a first heat exchanger receiving water vapor produced by at least one mechanical compression stage and connected to the water-supplied line so as to transfer heat to it, a second heat exchanger receiving heat from a hot fluid and producing water vapor supplying at least one mechanical compression stage,

[0018] - an electric heating device.

[0019] The electric heating device may be a Joule effect, induction, microwave, plasma, shock wave heating device, or a combination of these devices, preferably a Joule effect and / or induction heating device.

[0020] Preferably, the first electrical heat production system may include at least one heat pump, advantageously coupled to a mechanical vapor recompression system.

[0021] Advantageously, the thermal storage system may comprise an enclosure, in particular insulated, containing a solid thermal storage medium and equipped with the heating device of the thermal storage system. This heating device is, for example, an electric heating device, in particular a Joule effect and / or induction heating device.

[0022] Advantageously, the second heat and power generation system may include a second heat exchanger mounted on the circuit of the second heat and power generation system, at the turbine outlet, in series with the aforementioned first heat exchanger, specifically downstream of the latter with respect to the gas flow in the circuit. This second heat exchanger is thus also mounted in series with the aforementioned first heat exchanger located on the water-supplied pipe, upstream of the latter with respect to the water flow in the pipe. This embodiment is particularly advantageous when the second heat generation system further includes a thermodynamic engine, for example, an organic Rankine cycle engine, receiving a portion of the gas flow drawn from between the two exchangers, thereby improving the efficiency of this thermodynamic engine.

[0023] Advantageously, the second heat and electricity production system may include, mounted on the circuit downstream of the first heat exchanger mentioned, a thermodynamic engine adapted for converting low-temperature thermal energy into electricity, for example, of the organic Rankine cycle type. Such a thermodynamic engine makes it possible to produce electricity during the discharge phase, this electricity being used, for example, for the operation of an electrified steam cracking reaction zone or for other equipment in a steam cracking plant or for equipment in any plant equipped with the steam and electricity generation system of the invention.

[0024] The circuit of the thermodynamic machine of the second heat and electricity production system can form an open or closed loop. When it forms a closed loop, it is possible to use a gas other than air, such as CO2, helium, etc. In this case, it is not preferable for the second heat and electricity production system to include a thermodynamic engine, for example a Rankine cycle, and / or a second heat exchanger.

[0025] Another object of the invention relates to a hydrocarbon steam cracking installation comprising at least one electrified steam cracking reaction zone connected to a hydrocarbon supply line, characterized in that it further comprises a steam and electricity generation system according to the invention, a portion of the water-supplied line located downstream of the first heat exchanger mentioned is connected to the hydrocarbon supply line.

[0026] The invention also relates to a method for producing steam and electricity, in particular for a steam cracking plant, implementing the steam and electricity generation system according to the invention, comprising: - the introduction of water, including at least partially liquid water (for example, at room temperature), into the water supply pipe, and (i) during a charging phase of the thermal storage system, the heating device of the thermal storage system is switched on to accumulate heat, with the turbine, the electric generator, and optionally at least one rotating machine of the second heat and electricity production system switched off, and the first heat production system is switched on to produce steam; (ii) during a discharging phase of the thermal storage system, the turbine and at least one rotating machine of the second heat and electricity production system are switched on to produce steam and electricity, with the gases entering the turbine being heated by the thermal storage system and the electric generator being driven by the turbine.the first heat production system being either shut down or providing less thermal power than that supplied during the load phase.

[0027] The invention also relates to a process for steam cracking hydrocarbons implemented in a steam cracking plant according to the invention, comprising: - a step for producing dilution steam,

[0028] - a step of vaporizing hydrocarbons, - a step of mixing the vaporized hydrocarbons to be steam cracked with the dilution steam produced, - a cracking step of the mixture of hydrocarbons and dilution vapor in the steam cracking reaction zone at a cracking temperature obtained by electrical heating.

[0029] According to the invention, the step of producing dilution steam is implemented by a steam and electricity generation system according to the invention and comprises: - the introduction of water, including at least partially liquid water (for example, at room temperature), into the water supply pipe, and

[0030] (i) in a charging phase of the thermal storage system, the activation operation of the heating device of the thermal storage system so that the latter accumulates heat, the turbine, the electric generator, and optionally at least one rotating machine, of the second heat and electricity production system being stopped, and the commissioning of the first heat production system to produce steam, (ii) in a discharge phase of the thermal storage system, the commissioning of the turbine and at least one rotating machine of the second heat and electricity production system to produce steam and electricity, the gases entering the turbine being heated by the thermal storage system and the electric generator being driven by the turbine, the first heat production system being stopped or providing less thermal power than that supplied in the charging phase.

[0031] In particular, during the discharge phase, the management system can be configured to supply electricity produced by the electric generator to an electrical network and / or at least one piece of electrical equipment in the steam cracking plant, such as a compressor, pump, solenoid valve, etc. This electrical network can be a public network or internal to a plant using the steam and electricity generation system of the invention.

[0032] The installation and process according to the invention can be implemented for the steam cracking of various hydrocarbon feedstocks such as ethane, liquefied petroleum gases (propane, butane), naphtha, diesel fuel, and vacuum distillates. Other possible hydrocarbon feedstocks include hydrocarbons of biological origin, such as ethane, propane, butanes, naphtha, and distillates produced during the hydrotreating / hydrocracking of fatty acid esters (e.g., triglycerides), biomass pyrolysis oils, or biomass hydrothermal liquefaction oils. Other possible hydrocarbon feedstocks include hydrocarbons obtained by pyrolysis, hydrothermal liquefaction, or hydrocracking of plastic waste. Detailed description of the invention Description of the figures

[0033] The invention is now described with reference to the accompanying, non-limiting drawings, in which:

[0034] [Fig-1] Fig. 1 schematically represents a steam generation system and of electricity comprising an open cycle thermodynamic machine according to an embodiment of the invention.

[0035] [Fig.2] Fig.2 schematically represents a steam and electricity generation system comprising an open cycle thermodynamic machine according to another embodiment of the invention.

[0036] [Fig.3] Fig.3 schematically represents a steam and electricity generation system comprising an open cycle thermodynamic machine according to another embodiment of the invention.

[0037] [Fig.4] Fig.4 schematically represents a steam and electricity generation system comprising a closed-cycle thermodynamic machine according to an embodiment of the invention, in a charging phase of the thermal storage system.

[0038] [Fig.5] The [Fig.5] schematically represents the steam and electricity generation system of the [Fig.4] in a discharge phase of the thermal storage system.

[0039] [Fig.6] The [Fig.6] schematically represents the steam and electricity generation system of the [Fig.4] in another discharge phase of the thermal storage system.

[0040] [Fig.7] Fig.7 schematically represents a steam generation system and of electricity comprising an open-cycle thermodynamic machine according to another embodiment of the invention

[0041] [Fig.8] The [Fig.8] schematically represents a steam cracking installation 100 equipped with a steam generation system 1 according to an embodiment of the invention.

[0042] In the figures, the same elements are designated by the same references.

[0043] The terms "upstream" and "downstream" are used in relation to the flow of fluids, symbolized by arrows on the figures.

[0044] Figure 1 represents an electric steam production system 1 according to an embodiment of the invention. This comprises:

[0045] - a water-supplied pipe 2,

[0046] - a first electrical heat production system 20,

[0047] - a second heat and electricity production system 30.

[0048] By electrical heat production system, we mean a system that allows to produce heat directly or indirectly from electricity.

[0049] The first electrical heat production system 20 is connected to the water-supplied pipe so as to transfer heat to the water circulating in the pipe 2. For this purpose, it may include an inlet 22 and an outlet 23 connected to the water-supplied pipe 2 and the water can thus circulate and be vaporized inside the electrical heat production system 20.

[0050] In the example shown, this electrical heat production system 20 comprises a PACH heat pump. A heat pump uses energy to transfer heat from a lower temperature (source) to a higher temperature demand (sink) using additional energy, typically electricity. This heat pump comprises a circuit 21 through which circulates a working fluid, preferably a gas (for example, CO2, a hydrocarbon, in particular an alkane such as pentane, water, ammonia, a refrigerant such as a hydrofluoroolefin or HFO, or a hydrochlorofluoroolefin or HCFO), and equipped with two heat exchangers Ech_1 and Ech_2. The heat pump also typically comprises a compressor and an expansion device (calibrated orifice, electronic expansion valve, turbine, semi-closed valve, etc.), which are not shown. The working fluid circulating in the first heat exchanger Ech_1 transfers heat by at least partial condensation to the water circulating in the first heat exchanger and supplied by the water-supplied line 2, while the working fluid circulating in the second heat exchanger Ech_2 receives heat to be vaporized from at least one hot fluid circulating in the second heat exchanger and originating from a heat-generating installation (waste heat), for example from a steam cracking plant or any other installation using the steam generation system 1. This hot fluid circulating in a line 3 can, for example, come from the water quenching tower of the steam cracking plant, or from a fluid taken downstream of a compressor, or from ambient air, a geothermal source, the sea, or a return water from a cooling unit.The vaporized working fluid is then compressed using the compressor and reaches a higher pressure and temperature. The vaporized working fluid at a higher temperature transfers heat through at least partial condensation in Ech_1 to the circulating water supplied by pipe 2. Next, the working fluid is expanded to a lower pressure and cooled to a lower temperature and then returns to Ech_2 to again receive heat from the hot fluid circulating in pipe 3.

[0051] This PACH heat pump is sized to transfer sufficient heat to at least partially convert water into steam when powered by electricity. It may be possible to use more than one heat pump and / or steam recompression systems connected in series and / or parallel to provide the water with the heat necessary for its vaporization. Mechanical steam recompression (MVR) is an open heat pump system in which the pressure and temperature of the steam are increased by means of compression, typically using electricity.

[0052] The invention is not limited by this embodiment, however, and the heat pump may be replaced by one or more electric heating devices, for example, Joule effect (e.g., electric resistance type), induction, or other of the type already described, or one or more heat pumps may be combined with an electric heating device. However, in order to limit electricity consumption, it is preferable to use only heat pumps.

[0053] In particular, as a replacement for the PACH and / or the electric heating device, or in combination with it and / or with the electric heating device, the first heat production system 20 may include a mechanical vapor recompression (MVR) system, comprising one or more mechanical steam compression stages, one or more first heat exchangers receiving steam produced by one or more of the mechanical compression stages, for example downstream of each stage, and connected to pipe 2 supplied with water in such a way as to transmit calories to it, a second heat exchanger receiving calories from a hot fluid and producing water vapor (low pressure or vacuum steam) supplying the mechanical compression stage(s).

[0054] The second heat and electricity production system 30 comprises: - a heat exchanger 32 connected to the water-supplied pipe 2, via a pipe 5 in the example shown, the water in liquid or vapor form supplied by the pipe 2 circulating inside the heat exchanger, this heat exchanger may for example have an inlet 321 and an outlet 323 connected to the water-supplied pipe 2, here via the pipe 5,

[0055] - a thermodynamic machine 33 whose exhaust gases circulate at the interior of the heat exchanger 32,

[0056] - a thermal storage system 34 equipped with a heating device 340, this thermal storage system 34 being coupled to the circuit of the thermodynamic machine upstream of its turbine as described in more detail below.

[0057] When in operation, the hot gases produced by the thermodynamic machine 33 thus transfer their heat to the water circulating in the heat exchanger 32, causing it to vaporize. The thermodynamic machine 33 is therefore advantageously sized to be able to transform water into steam when it is in operation and producing electricity (the power consumed by the compressor(s) is less than that produced by the turbine and the alternator).

[0058] More specifically, the sizing of the thermodynamic machine (in particular the sizing of at least one rotating machine and the machine's turbine) and the thermal storage system can be chosen according to the amount of electricity that is to be avoided during the discharge phase of the storage system. This amount depends on the thermal energy co-generated by the thermodynamic machine 33 in the heat exchanger 32. This amount of electricity saved also depends on the power of the first electrical heat production system, the coefficient of performance (COP) of the PACH, and the electricity generated by the thermodynamic machine 33.

[0059] In the embodiment of [Fig.1], the thermodynamic machine 33 is of the gas turbine type, namely of design close to a gas turbine, with external heat input (as opposed to gas turbines with a combustion chamber).

[0060] This thermodynamic machine 33 of the gas turbine type comprises a circuit 330 in which a gas circulates, this circuit 330 comprising, mounted in series in the direction of gas flow: - one or more rotating machines 331, here only one, - a turbine 333 driving at least one rotating machine 331.

[0061] In this embodiment, the rotating machine is a compressor 331 capable of compressing the gas circulating in the circuit 330.

[0062] The part of the circuit 330 receiving the exhaust gases exiting the turbine 333 is furthermore connected to the heat exchanger 32 so that the gases exiting the turbine circulate inside the heat exchanger 32 in order to transfer their calories to the water circulating in the exchanger 32 and thus to vaporize it.

[0063] The thermal storage system 34 is coupled to the circuit 330 in order to be able to transfer calories to the gas circulating in the circuit 330, either directly, the gas passing for example through the thermal storage system 34, or indirectly, via a heat exchanger not shown here.

[0064] The use of a thermal storage system 34 makes it possible to accumulate heat during periods when electricity is cheaper and / or renewable and thus to reduce the overall economic and / or environmental cost.

[0065] This thermal storage system 34 typically comprises a typically isothermal enclosure 342 containing a solid thermal storage medium and equipped with a heating device 340. This heating device 340 may be a Joule effect, induction, infrared radiation, microwave, plasma, shock wave, or a combination thereof heating device. For example, a heating device of the type described in US patent 11,631,992 may be used. This heating device 340 may be integrated into the enclosure 342 or be separate. In the latter case, it must be positioned on the circuit 330 upstream of the thermal storage system 34 and its enclosure 342.

[0066] The solid thermal storage medium, generally in the form of powders, particles, or solid blocks having open cavities and / or channels, advantageously exhibits suitable thermal storage capacities and / or is capable of achieving heat transfer rates suitable for the intended use. Suitable solid media include sand, volcanic rock, or refractory materials such as alumina, etc. For example, a thermal storage system containing volcanic rock produced by Brenmiller Energy could be used. Stacked refractory materials could also be used; the storage system could, for example, be similar to a glass furnace regenerator and contain a stack of refractory materials, which could be cruciform, brick, bushel, or pot shapes. Preferably, the solid medium is in the form of powder or particles, for example, sand.Electrically conductive refractory bricks can also be used, which can be heated by the circulation of gas and / or by an electric current passing through the bricks. during the charging of the thermal storage (e.g. Joule Hive Thermal Battery refractory bricks).

[0067] In particular, a thermal storage system capable of reaching a temperature of 1000 to 1300 °C may be chosen.

[0068] The second heat production system 30 further includes an electric generator 36 connected to the turbine 333 so as to produce electricity when driven by the turbine 333. This electricity can thus be reinjected into any installation, and in particular a steam cracking installation, using the steam generation system 1 according to the invention.

[0069] The steam and electricity generation system 1 finally includes a management system 40 for the first electrical heat production system 20 and the second heat and electricity production system 30.

[0070] This management system 40 is configured, in particular programmed, to:

[0071] (i) in a charging phase of the thermal storage system 34, operate the heating device 340 of the thermal storage system 34 so that the latter, in particular here the thermal storage enclosure 342, and more specifically the thermal storage medium of the enclosure, accumulates (stores) calories, the turbine 333, the compressor 331 and the electric generator 36 of the second heat production system 30 being stopped, and to operate the first heat production system 20 to produce steam,

[0072] (ii) in a discharge phase of the thermal storage system 34, operate the turbine 333 and the compressor 331 of the second heat production system 30 to produce steam and electricity, the gases entering the turbine 333 being heated by the thermal storage system 34 and transferring their calories to the water to vaporize it via the heat exchanger 32, the first heat production system 20 being stopped or providing less thermal power than the thermal power supplied in the charging phase.

[0073] During the charging phase, the first heat production system 20 is thus operated to produce sufficient thermal energy (calories) to vaporize the water circulating in the pipe 2. During the discharging phase, this system is stopped or produces less thermal energy, since the thermal energy required for vaporization is partly or totally supplied by the second heat production system 30.

[0074] During the discharge phase, electricity is also produced by the electric generator 36. For example, a turbine inlet temperature of around 1000 to 1200 °C, or for example 1100 °C, will be preferred, with the gas exiting the turbine at 500-600 °C before entering the heat exchanger 32. The The temperature of the gas at the outlet of the heat exchanger 32 will vary depending on the efficiency of the latter.

[0075] The management system 40 is thus configured to operate the thermal storage system 34 cyclically in a charging phase in which it accumulates heat and in a discharging phase in which it releases the accumulated heat, and to control the other components of the steam and electricity production system according to these phases.

[0076] Regardless of the embodiment, generally the thermodynamic machine 33 of the gas turbine type used in the present invention does not receive combustion gases to operate, and therefore does not use fuel. The heat it needs to operate comes solely from the thermal storage system 34.

[0077] In the embodiment shown [Fig. 1], the thermodynamic machine 33 of the gas turbine type is open cycle (open circuit 330). The gases exiting the turbine are discharged into the air after passing through the heat exchanger 32. The gas used in the circuit is typically air.

[0078] In Figures 1 to 3, the second heat production system 30 is mounted in parallel with the first heat production system 20 on a bypass line 5 connected to the water-supplied line 2 via one or more valves 6. Alternatively, they could be mounted in series. In this case, it may be preferable to also mount the second heat production system on a bypass line to facilitate its isolation when the storage device is being charged.

[0079] After passing through the heat exchanger 32, the gas still contains calories which are lost in the embodiment of [Fig.1].

[0080] In order to recover these calories, a thermodynamic engine 38, adapted for the conversion of low temperature thermal energy into electricity, for example an organic Rankine cycle (ORC) thermodynamic machine 38, can be mounted on the circuit 330 of the second electrical heat production system 30, downstream of the heat exchanger 32. Alternatively, Brayton cycle thermodynamic machines, trilateral flash cycle (in English: "trilateral Flash Cycle"), e.g. using the technologies of the companies PwrCor®, Climeon®, Entent®, ExtractEnergy®, can be used.

[0081] This thermodynamic machine 38 will thus produce electricity during the discharge phase of the thermal storage system by using the calories from the gas exiting the heat exchanger 32, as represented in the embodiment of [Fig.2].

[0082] In order to improve the efficiency of the thermodynamic machine 38 while transferring the same thermal power to the water circulating in the bypass pipe 5. The second heat and electricity production system 30 may further include a second heat exchanger 39 connected in series with the heat exchanger 32 on the circuit 330 and on the bypass pipe 5. This embodiment is shown in [Fig. 3]. In this embodiment, the first heat exchanger 32 operates at a reduced power output compared to the embodiments of Figures 1 and 2. At the outlet of this heat exchanger 32, the gases are sent partly to the second heat exchanger 39 and partly to the thermodynamic machine 38. This arrangement increases the inlet temperature of the thermodynamic machine 38 during the discharge phase, thus improving its efficiency. The consequence of improved efficiency is the production of more electricity without impacting the heat output.The water circulating in the pipe 5 is first preheated by passing through the second heat exchanger 39, then vaporized when it passes through the heat exchanger 32.

[0083] The working fluid used in an ORC thermodynamic machine 38 can be chosen from among the organic compounds usually used, namely: . - refrigerants (of the type HFC, HFO, HFCO, HFE) and CO2, suitable for temperatures <200 °C at the machine inlet, - Alkanes (pentane, butane, cyclopentane) and CO2, which are adapted to a wider temperature range (typically up to 250 °C), - siloxanes and CO2, suitable for high temperature sources (typically 250 °C to 300 °C).

[0084] The gas turbine-type thermodynamic machine 33 can be open-cycle, as shown in the embodiments of Figures 1 to 3, or closed-cycle, as shown in the embodiment of Figures 4 to 6. In this case, the circuit 330 of the thermodynamic machine forms a closed loop: what exits the heat exchanger 32 re-enters the compressor 331. The gas circulating in the circuit 330 can then be helium, nitrogen, CO2, etc.

[0085] In the embodiment of figures 4-6, the first and second heat production systems 20, 30 are mounted in series, here the second heat production system being mounted on a bypass pipe 7 connected to the pipe 2, at a part 4 located downstream of the first heat production system 20 via a valve 8.

[0086] Fig. 7 represents another embodiment which differs from that of Fig. 1 only in the nature of the rotating machine 331. In this embodiment, the rotating machine 331 of the thermodynamic machine 33 is capable of heating the gas by shock waves and is used to heat the gas circulating in the circuit 330 during the charging phase of the thermal storage system 34.

[0087] This type of rotating machine comprises a rotating shaft on which blades are mounted. The rotation of the shaft accelerates the gas to supersonic speed, followed by a diffuser that reduces the gas speed to subsonic speed, creating a shock wave that causes the gas temperature to rise.

[0088] Such a rotating machine is described for example in documents WO 2020 / 060919 Al and WO 2019 / 221726 Al.

[0089] In this case, during the charging phase of the thermal storage system 34, it may be advantageous to recirculate the hot gas from the outlet of the thermal storage vessel 342 to the inlet of the rotating machine 331 via a conduit 332, as shown. During the charging phase, the turbine 333 is then decoupled from the rotating machine 331. Conversely, the turbine is coupled to the rotating machine during the discharging phase. It may be advantageous to provide coupling means (not shown) for the rotating machine and the turbine capable of performing this coupling / decoupling and controllable by the management system 40.

[0090] During the discharge phase, the hot gas exiting the thermal storage system 34 is sent entirely to the turbine 333.

[0091] During the charging phase, this embodiment can be combined with the variants described with reference to figures 2 to 6.

[0092] Regardless of the embodiment, the management system 40 used in the present invention typically comprises one or more processors, for example a microprocessor, a microcontroller, or the like. It can be configured (in particular, programmed) to control the heat production systems used in the present invention. It can thus be connected to the components of these systems, and optionally to one or more valves, pumps, or other elements used for fluid circulation, and / or powering the components, and / or controlling these components.

[0093] The management system 40 can also receive various pieces of information from one or more appropriately arranged sensors relating to:

[0094] - to the power supply (electrical and / or thermal) of each system of heat production (quantity of current received and consumed, temperature and / or flow rate of fluids whose temperature is controlled),

[0095] - in the charging and discharging state of the thermal storage system (temperature),

[0096] - to the phase in which the thermal storage system is located (charge, dump),

[0097] - to the amount of electrical and / or thermal energy received / produced by each heat production system (quantity of current, flow rate and / or temperature of fluids).

[0098] The management system 40 typically includes output or input / output interfaces. These may be wireless communication interfaces (Bluetooth, Wi-Fi, or other) or connectors (network port, USB port, serial port, FireWire® port, SCSI port, or other). These input and / or output interfaces can form means of communication, optionally bidirectional, between the management system and the components of the heat production systems and the energy storage system.

[0099] The management system 40 may also include storage means, which may be random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), flash memory, external memory, or other. These storage means may, among other things, store received data, measured values, calculated values, and one or more computer programs.

[0100] The steam and electricity generation system according to the invention can be used in any installation requiring steam and electricity production. It is particularly suitable for integration into a steam cracking plant 100 comprising at least one electrified steam cracking reaction zone 10, such as, for example, schematically represented [Fig. 8]. For this purpose, a portion 4 of the water-supplied line 2, located downstream of the heat exchanger of the second steam and electricity production system 30, at which point the water is in the form of steam, can be connected to a supply line 102 supplying hydrocarbons to the electrified steam cracking reaction zone 10, as schematically represented in the figures.

[0101] The hydrocarbon feed and dilution steam are injected into at least one reaction zone 10. This reaction zone can be a reactor, for example a multi-tube reactor in the case where the heat required for cracking is produced outside the reaction zone (radiative heating, resistive tube heating, plasma heating) or a single-tube reactor in the case where the heat is produced in-situ (by shock wave, resistive heating elements placed in the single-tube reactor).

[0102] The hydrocarbon feedstock and water can be preheated separately and then mixed and further preheated in at least one heat exchange tube bundle or in an electric heat exchanger, typically to a temperature between 600 and 680 °C. In particular, this preheating can be partially carried out using the heat to be extracted in the cooling units 11 and 12. This mixture is then, for example, distributed inside one or more tubular reactors (not shown) forming part of the reaction zone 10. The tubular reactors are further heated electrically to initiate thermal cracking. The effluent temperature at the outlet of the tubular reactors is typically between 800 and 900 °C.

[0103] The effluent exiting the steam cracking reaction zone is then rapidly cooled (quenched) in one or more cooling units 11, 12, 14, then purified and separated in compression units 13 and fractionation units 15.

[0104] This effluent contains unreacted raw materials and reaction products that vary depending on the nature of the feedstock to be cracked. For example, if the hydrocarbon feedstock to be cracked is naphtha, the effluent contains the desired olefins (mainly ethylene and propylene), hydrogen, methane, a mixture of C4 hydrocarbons (mainly isobutylene and butadiene), gasoline (aromatics in the C6 to C8 range), ethane, propane, acetylenes (acetylene, methylacetylene, propadiene), and heavier hydrocarbons with boiling points in the fuel oil temperature range. These cracked gases are rapidly cooled, typically to 338–510°C, to stop pyrolysis reactions and minimize secondary polymerization reactions.Depending on the average molecular mass of the filler, the relative quantities of the different products vary: for light fillers, such as ethane, there are few hydrocarbons with more than 4 carbons.

[0105] Typically, at the outlet of the steam cracking reaction zone 10, the cracked gases are discharged via a line 107 into a rapid cooling unit 11 comprising one or more heat exchangers (often designated by the acronyms TLE or TLX for "Transfer Line Exchanger"), in which the cracked gases are cooled, typically from 820-850°C to 300-510°C.

[0106] In certain installations, such as in the example described here, at the outlet of the rapid cooling unit 11, the cracked gases are brought via a line 108 to an optional fractionation column 17 (also called primary fractionation) to condense and separate the fuel oil fraction from the cracking gas.

[0107] At the outlet of the fractionation column 17, the fractionated overhead gases are conveyed via a pipe 112 to a second cooling unit 12, here a water-quench tower, which condenses most of the dilution vapor and heavy fuels present in the gases. The gases are cooled by means of water circulating in the pipe 113. In this example, this water is extracted from the lower part of the quench tower 12 and returned by means of a pump 114 to the top of the quench tower after being cooled in a heat exchanger 115 and 116 before being reintroduced into the quench tower 12. This water, or a portion of it, can be circulated in the pipe 3 of the heat exchanger Ech_2 of the heat pump of the steam generation system 10 according to the invention.

[0108] The heaviest hydrocarbons recovered at the bottom of the quenching tower 18 can be returned via a pump 117 and a pipe 118 to the fractionation column 17 and / or via a pump 119 and a pipe 120 to a stripper 121.

[0109] At the outlet of the second cooling unit 12, the cracked gases enter via a pipe 122 into a compression unit 13, then via a pipe 123 into a third cooling unit 14 and are finally brought via a pipe 124 to a fractionation unit 15, the products of the steam cracking installation being recovered via at least one pipe 125.

[0110] The compression unit 13 typically comprises a series of compression stages, generally 3 to 6, each stage including a compressor, a cooling means (for example, a heat exchanger), and a liquid-gas separation device. The compressors of the various stages are generally powered by a steam turbine or an electric motor (or several of these). This compression unit further includes a purification section to remove acidic gases (CO2, H2S, SO2) and a drying section to remove residual water. Between the compression stages, condensed water and light fuels are removed. A hot fluid, taken downstream of one of the compressors of the compression unit, can also be circulated in the line 3 of the heat exchanger Ech_2 of the heat pump of the steam generation system 10 according to the invention.

[0111] At the outlet of the compression unit 13, the gases are then sent to the third cooling unit 14 in which they are cooled to cryogenic temperatures before being sent to the fractionation unit 15.

[0112] The third cryogenic cooling unit 14 requires a cooling supply provided by circuits comprising numerous components such as a compressor, heat exchanger, and pressure-reducing valve. The cooling supply is generally provided by cryogenic fluids such as liquid ethylene and propylene. Liquid ethylene and propylene are produced by successive compression steps followed by cooling to condense the majority of the ethylene or propylene.

[0113] The third cooling unit 14 thus comprises refrigeration cycles using some of the propylene and ethylene produced as refrigerants to perform the fractionation. The gases undergo several refrigeration cycles during which the refrigerants are produced by liquefaction by passing through a compressor, then cooled in a heat exchanger, and then further cooled by expansion.

[0114] The third cooling unit 14 thus makes it possible to cool the cracked gases entering the fractionation unit 15 and more particularly the cold fractionation section (often referred to as the cold box) thereof (de-methanizer), typically in several stages using ethylene, propylene and methane / hydrogen as refrigerants: (1) cooling the cracked gases to approximately (1) Cooling the gas to -70 to -100°C using propylene and / or ethylene in several stages, followed each time by separation of the condensed hydrocarbons, which are injected into the de-methanizer; (2) cooling the remaining gases to approximately -125°C using methane / hydrogen, followed by separation of the condensed hydrocarbons; and (3) cooling the remaining gases to approximately -165°C using methane / hydrogen, followed by separation of the condensed methane, producing a hydrogen stream with a purity of more than 90 vol%. This type of configuration corresponds to a sequence of the "de-methanizer first" fractionation unit. However, the invention is not limited to this configuration and can be adapted to other configurations of the fractionation unit, particularly "de-ethanizer first" or "de-propanizer first" configurations.

[0115] The fractionation unit 15 typically comprises a cold fractionation section operating at low temperature for separating C1 / C2 hydrocarbons, followed by a hot fractionation section operating at higher temperature for separating C3 / C4 hydrocarbons. The fractionation unit may, for example, include a methanizer, a propaneizer, and / or an ethane converter. The sequence of these fractionation units—methanizer, ethane converter, and propane converter—may vary depending on the thermal integration envisaged and determines the design of the cryogenic cooling unit. The fractionation unit typically includes fractionation columns, heat exchangers, and pumps and valves for fluid circulation.

[0116] In this fractionation unit 15, the cracked, cooled gases can thus be distilled in a de-methanizer where methane and dihydrogen are extracted, then in a de-ethanizer to recover acetylene, ethane and ethylene, then in a de-propanizer in which propylene, propadiene, methylacetylene and propane are recovered, and finally in a de-butanizer to recover butanes, butadiene and butenes.

[0117] The hot fractionation section of the fractionation unit 15 includes reboilers and heat exchangers.

[0118] The various units of a steam cracking plant thus include many components such as pump, motor, compressor, heat exchanger, condenser, valves, etc., which require an input of electrical energy to operate, and which can thus be supplied with electricity by the second heat production system according to the invention when its thermal storage system is in a discharge phase. Examples Example 1 - Closed-cycle gas turbine

[0119] In this example, the steam production system is similar to that shown in Figures 4 to 6. In this example, the storage system 34 uses sand as the heat transfer material and is capable of storing 290 MWh, with a storage temperature of 1200 °C. The quantity of sand is 1800 tonnes for 1100 m³.

[0120] The power ratings are calculated for a charging time of 4 hours and a discharging time of 4 hours.

[0121] Figures 4 to 6 show the thermal powers (in MWth) and the electrical powers (in MWe) of the different components as well as the temperatures of the circulating fluids.

[0122] Fig. 4 corresponds to a load mode of the thermal storage system, during which the gas turbine is stopped, the heating device heats the storage system and the heat pump operates to produce steam.

[0123] Figure 5 illustrates a discharge mode in which the heat pump is off while the gas turbine is running, and the thermal storage system supplies heat to the gas circulating in the gas turbine circuit. In this embodiment, the efficiency of the engine cycle (of the gas turbine) is approximately 34%.

[0124] Figure 6 illustrates a discharge mode in which the heat pump operates at idle while the gas turbine is running, and the thermal storage system supplies heat to the gas circulating in the gas turbine circuit. In this embodiment, the efficiency of the engine cycle (of the gas turbine) is approximately 44%.

[0125] Example 2 - Gains from open-cycle or closed-cycle gas turbines

[0126] Figures 1 to 3 show the thermal powers (in MWth) and electrical powers (in MWe) of the different components in discharge mode of the thermal storage system 34, as well as the temperatures of the circulating fluids.

[0127] The energy performance coefficient of the heat pump is 2.8.

[0128] In discharge mode, the embodiment of [Fig. 1] can produce 32.9 MWe of electrical power, for a motor cycle efficiency of the thermodynamic machine 33d' of approximately 33.2%. The gases from the turbine exiting the heat exchanger 32 are still at a temperature of 160 °C. The thermal storage system 34 produces a thermal power of 99 MWth in discharge mode.

[0129] In discharge mode, the embodiment of [Fig. 2] can produce 31.7 MWe of electrical power, for a motor cycle efficiency h of the thermodynamic machine 33 of approximately 33.2%. The organic Rankine cycle thermodynamic machine 38, on the other hand, produces 1.2 MWe of electrical power for an efficiency h of 9%. Furthermore, the required thermal power (95.5 MWth) supplied by the thermal storage system 34 is less than that of the first embodiment, so it is possible to reduce its size. The presence of Organic Rankine cycle thermodynamics 38 thus makes it possible to reduce the power of the heat engine forming a gas turbine and to reduce the size of the thermal storage 34 and thus to improve the overall efficiency.

[0130] In discharge mode, the embodiment of [Fig. 3] can produce 32.9 MWe of electrical power, for a motor cycle efficiency h of the thermodynamic machine 33d' of approximately 33.2%. The ORC thermodynamic machine 38, on the other hand, produces 1.7 MWe of electrical power for an efficiency h of 12%. It receives a thermal power of 14 MWth. The thermal power delivered by the heat exchanger 32 is less than that delivered in the other embodiments, but is greater than the thermal power delivered by the heat exchanger 39. Furthermore, the required thermal power (94 MWth) supplied by the thermal storage system 34 is less than that of the embodiments of Figures 1 and 2, so it is possible to reduce its size.The presence of the ORC thermodynamics unit 38 and the two heat exchangers 32 and 39 allows for a further reduction in the power of the heat engine forming a gas turbine and the size of the thermal storage, thus further improving the overall efficiency. It should be noted that, in this embodiment, the heat exchanger 32 has an efficiency of 80%. If this efficiency is reduced to 73%, it may then be necessary to operate the heat pump at a lower power to achieve the amount of heat required to vaporize the water at the desired temperature.

[0131] In the charging mode, the heating device 342 of the thermal storage system 34 should thus produce thermal powers of 99, 95.5 and 94 MWth respectively for the embodiments of Figures 1, 2 and 3. In addition, in charging mode, the PACH heat pump then operates to produce a thermal power substantially equivalent to that supplied by the heat exchanger(s) 32, 39 in the discharge mode, and sufficient to produce steam, namely here a thermal power of approximately 47 to 48.8 MWth thermal, which corresponds, depending on the sizing of the heat pump, and receiving a hot fluid at a temperature of 90 °C, to an electrical power consumption of approximately 16 to 18 MWe.

[0132] Table 1 below presents the estimated data for systems corresponding to the embodiments shown in Figures 1, 2 and 4 respectively, considering a charging time of 4 hours and a discharging time of 12 hours. For the system corresponding to the embodiment in [Fig. 4], three different gas turbine efficiencies were studied: 34, 40.6 and 44%.

[0133] In Table 1: - The electrical gain during discharge is expressed as the electricity production of the gas turbine plus the gain in consumption due to not using the heat pump, - the equivalent efficiency is expressed as the ratio of the electrical gain in discharge to the electrical overconsumption in the charging phase.

[0134] [Table 1] Table 1 Figure 1 Figure 2 Figure 4 34% Efficiency Figure 4 40.6% Efficiency Figure 4 44% Efficiency Sand storage 1180 MWh (7000 T: 4300 m3) 1150 MWh (7000 T: 4300 m3) 870 MWh (4500 T: 2700 m3) 970 MWh (5000 T: 3000 m3) 940 MWh (5000 T: 3000 m3) Electrical power used to heat the storage 295 MWe 290 MWe 220 MWe 245 MWe 235 MWe Electrical power produced during discharge 32.9 MWe 31.5 MWe ( 1.5 MWe (2) 24.8 MWe 32.9 MWe 34.4 MWe Electrical gain in discharge 50 MWe 50 MWe 41.9 MWe 50 MWe 50 MWe Equivalent efficiency 50.7% 51.2% 57.4% 61.7% 63.9% 1. : power produced by the gas turbine type heat engine 2. : power produced by the Rankine organic cycle heat engine (ORC)

Claims

1. Demands Steam and electricity generation system (1), in particular for an electrified steam cracking reaction zone (10), comprising at least: - a pipe (2) supplied with water, - a first electrical heat production system (20) connected to the pipe (2) so as to transmit calories to the water circulating in the pipe (2), - a second heat and electricity production system (30) comprising: (a) a heat exchanger (32) connected to the pipe (2), the water supplied by the pipe circulating inside the heat exchanger (32), (b) a thermodynamic machine (33) comprising a circuit (330) in which a gas circulates, this circuit comprising, mounted in series in the direction of gas flow: at least one rotating machine (331) capable of compressing the gas or heating it by shock waves, a turbine (333) connected to the at least one rotating machine so as to be able to drive it, the gases exiting the turbine circulating inside the heat exchanger (32) in order to transfer the calories from the gas to the water circulating in the exchanger, (c) a thermal storage system (34) coupled to the circuit (330) of the thermodynamic machine (33) upstream of the turbine, (d) a heating device (340, 331) of the thermal storage system (34), (e) an electric generator (36) driven by the turbine of the thermodynamic machine, - a management system (40) for the first heat production system (20) and the second heat and electricity production system (30), configured to: (i) during a charging phase of the thermal storage system, operate the heating device (340, 331) of the thermal storage system (34) so ​​that the latter accumulates heat, the turbine (333), the electric generator (36), and optionally at least one rotating machine (331) of the second heat and electricity production system being stopped, and operate the first heat production system to produce steam, (ii) in a discharge phase of the thermal storage system, operate at least one rotating machine and the turbine of the second heat and power production system to produce steam and electricity, the gases entering the turbine being heated by the thermal storage system and the electric generator being driven by the turbine, the first heat production system (20) being stopped or supplying less thermal power than the power supplied in the charging phase.

2. Steam and electricity generation system (1) according to claim 1, characterized in that the first electrical heat production system (20) comprises one or more of the following components mounted in series and / or in parallel on at least one water-supplied pipe (2): - a heat pump (HPH) connected on the one hand to the water-supplied pipe so as to transmit heat to it and on the other hand to a pipe in which a hot fluid circulates so as to receive heat from the latter, - a mechanical steam recompression system, comprising at least one mechanical steam compression stage, at least one first heat exchanger receiving steam produced by the at least one mechanical compression stage and connected to the water-supplied pipe so as to transmit heat to it,a second heat exchanger receiving heat from a hot fluid and producing steam to supply at least one mechanical compression stage, - an electric heating device.

3. Steam and electricity generation system (1) according to claim 1 or 2, characterized in that the thermal storage system (34) comprises an enclosure (342) containing a solid thermal storage medium and equipped with the heating device (340).

4. Steam and electricity generation system (1) according to any one of claims 1 to 3, characterized in that the second heat and electricity generation system (30) comprises a second heat exchanger (39) mounted on the circuit (330) of the second heat and electricity production system (30), at the outlet of the turbine, in series with the first heat exchanger (32) mentioned.

5. Steam and electricity generation system (1) according to any one of claims 1 to 4, characterized in that the second heat and electricity production system (30) comprises, mounted on the circuit (330), downstream of the first heat exchanger (32) mentioned, a thermodynamic engine (38), adapted for the conversion of low temperature thermal energy into electricity, for example of the organic Rankine cycle type.

6. Steam generation system (1) according to any one of claims 1 to 5, characterized in that the circuit (330) of the thermodynamic machine forms a closed loop.

7. Hydrocarbon steam cracking installation (100) comprising at least one electrified steam cracking reaction zone (10) connected to a hydrocarbon supply line (102), characterized in that it further comprises a steam and electricity generation system (1) according to any one of the preceding claims, of which a portion (4) of the water-supplied line located downstream of the first heat exchanger mentioned (32) is connected to the hydrocarbon supply line (102).

8. A method for producing steam and electricity, in particular for a steam cracking plant, implementing the steam and electricity generation system according to any one of claims 1 to 6, comprising: - introducing water into the water-supplied conduit, and (i) in a charging phase of the thermal storage system (34), starting up the heating device (340, 331) of the thermal storage system so that the latter accumulates heat, the turbine (333), the electric generator (36), and optionally at least one rotating machine (331), of the second heat and electricity production system being stopped, and starting up the first heat production system to produce steam, (ii) in a discharging phase of the thermal storage system (34),the commissioning of the turbine (333) and at least one rotating machine (331) of the second production system,

9. heat and electricity to produce steam and electricity, the gases entering the turbine being heated by the thermal storage system (34) and the electric generator being driven by the turbine, the first heat production system being at rest or providing less thermal power than that supplied in the charging phase. A process for steam cracking hydrocarbons implemented in a steam cracking plant according to claim 7, comprising: - a step for producing dilution steam, - a step for vaporizing the hydrocarbons, - a step for mixing the vaporized hydrocarbons to be steam cracked with the dilution steam produced, - a step for cracking the mixture of hydrocarbons and dilution steam in the steam cracking reaction zone at a cracking temperature obtained by electrical heating, characterized in that the step for producing dilution steam is implemented by a steam and electricity generation system according to any one of claims 1 to 6 and comprises: - the introduction of water into the water-supplied pipe, and (i) during a charging phase of the thermal storage system, the heating device (340, 331) of the thermal storage system is switched on to accumulate heat, the turbine (333), the electric generator (36), and optionally at least one rotating machine (331) of the second heat and electricity production system being stopped, and the first heat production system is switched on to produce steam, (ii) during a discharging phase of the thermal storage system, the turbine (333) and at least one rotating machine (331) of the second heat and electricity production system are switched on to produce steam and electricity, the gases entering the turbine being heated by the thermal storage system and the electric generator driven by the turbine,the first heat production system being either shut down or providing less thermal power than that supplied during the charging phase.

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