STEAM CRACKLING INSTALLATION WITH ELECTRICALLY HEATED COMBINATION AIR SUPPLY TO THE STEAM CRACKLING FURNACE

Abstract

The invention relates to a steam cracking installation (100) comprising at least: - a steam cracking furnace (10) comprising a radiation zone equipped with burners connected to at least one fuel gas supply line and to at least one oxidizing gas supply line (1), - a cooling unit (12, 14), - a compression unit (13).The installation is equipped with at least one heat pump unit (20) comprising a circuit (200) in which a working fluid circulates, and comprising, mounted in series in the direction of flow of the working fluid: - a first heat exchanger (Ech_1) transferring heat to at least one combustion gas supply line, - an expansion device (202), - at least one second heat exchanger (Ech_2) transferring cooling to at least one fluid to be cooled circulating in at least one cooling unit (14) and / or in at least one compression unit (13), - a compressor (204). Figure for the abbreviation: Fig. 1.

Description

Title of the invention: Steam cracking installation with electrically heated combustion air for the steam cracking furnace. Technical field of the invention

[0001] The present invention relates to a hydrocarbon steam cracking installation with electrically heated combustion air supplied to the steam cracking furnace, and the corresponding hydrocarbon 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 thus requires inputs of heat (energy injection to increase the temperature and provide the enthalpy of reaction) and cold (energy extraction to lower the temperature) to fractionate, and significant amounts of energy, much of which is currently supplied by fossil fuels.

[0003] Increasingly important environmental concerns, however, require replacing this fossil energy with decarbonized energy (without CO2 emissions) and in particular renewable energy, and especially renewable electricity produced by wind turbines and / or solar panels.

[0004] Among the heat inputs required for a steam cracking process is the heating of the combustion air for the burners of a steam cracking furnace. To minimize the amount of fuel needed to provide thermal energy to the charge to be cracked, the combustion air must enter the burners at a temperature above 200 °C, typically from 300 to 600 °C. Electrical heating of this combustion air is feasible but expensive, particularly when the cost of electricity is high.

[0005] There is therefore a need to heat the combustion gas of a steam cracking furnace while reducing the economic, energy, and environmental impact. Summary of the invention

[0006] To this end, the invention proposes a steam cracking installation and a steam cracking process implementing one or more heat pump units.

[0007] A first object of the invention relates to a steam cracking installation comprising at least: - a steam cracking furnace, - a cooling unit, - a compression unit, in which the steam cracking furnace includes a radiation zone equipped with burners connected to at least one fuel gas supply line and to at least one oxidizing gas supply line.

[0008] According to the invention, the installation is further equipped with at least one heat pump unit comprising a circuit in which a working fluid circulates, this circuit comprising, mounted in series in the direction of circulation of the working fluid: - a first heat exchanger, the working fluid circulating in the first heat exchanger transferring calories to the combustion gas circulating in the first heat exchanger supplied by at least one combustion gas supply line, - an expansion member, - at least one second heat exchanger, the working fluid circulating in the second heat exchanger transferring cooling to at least one fluid to be cooled circulating in the second heat exchanger and coming from at least one cooling unit and / or at least one compression unit, - a compression member.

[0009] This arrangement makes it possible, on the one hand, to efficiently heat the combustion gas, generally air, while simultaneously cooling a fluid to be cooled circulating in the installation. This notably reduces the amount of energy that the cooling and / or compression unit must supply.

[0010] The working fluid used in at least one heat pump can be air, argon, helium, nitrogen (N2), CO2, etc., preferably argon or nitrogen.

[0011] The installation according to the invention may further include a management system for at least one heat pump, in particular configured to operate the at least one heat pump in a mode producing sufficient heat (calories) to heat the combustion gas to a target temperature and / or sufficiently of cold (frigories) to cool at least one fluid to be cooled, especially to a target temperature.

[0012] Advantageously, at least one heat pump unit may further comprise, mounted in the circuit between at least one second heat exchanger and the compressor, at least one third heat exchanger, the working fluid circulating in the third heat exchanger receiving heat from a hot fluid. Such a hot fluid may be a waste heat from the steam cracking plant, a hot fluid circulating in the steam cracking plant, for example from a cooling unit of the plant, in particular from a cooling unit located immediately downstream of the steam cracking furnace, a hot fluid from the compressor unit, or a hot fluid from another unit, typically different from the steam cracking unit. This third heat exchanger makes it possible to increase the temperature of the working fluid entering the compressor and thus the efficiency of the heat pump.One or more third heat exchangers in series or parallel can be considered, each receiving a hot fluid.

[0013] Advantageously, at least one heat pump unit may further comprise, mounted in the circuit between the first heat exchanger and the expansion valve, a fourth heat exchanger, the working fluid circulating in the fourth heat exchanger receiving cooling from a cold fluid. This allows the working fluid of the heat pump to be cooled before entering the expansion valve, further cooling of the working fluid, and even the production of more cooling at the outlet of the expansion valve. This also improves the efficiency of the heat pump.

[0014] Advantageously, the at least one cooling unit, typically producing a cooling fluid, may comprise several cooling stages, and the working fluid of the heat pump circulating in the at least one second heat exchanger may transfer cooling to at least one cooling stage, or even to each cooling stage, thereby relieving one or more of the chillers and reducing their energy consumption. These chillers may, in particular, be cryogenic chillers. The at least one heat pump may then advantageously comprise at least two second heat exchangers connected in series or parallel to cascade cool at least two fluids to be cooled.

[0015] The at least one compression unit may comprise several compression stages. According to one embodiment of the invention, the working fluid of the heat pump circulating in the at least one second heat exchanger can then transfer cooling to a fluid supplying at least one compression stage, or even each compression stage, which makes it possible to relieve one or several of the compression units and thus reduce their energy consumption. At least one heat pump may then advantageously include at least two secondary heat exchangers connected in series or parallel to cascade-cool at least two fluids supplying or leaving different stages of the compression unit. When at least one third heat exchanger is present, at least one heat pump may advantageously include at least two third heat exchangers connected in series or parallel, each receiving a hot fluid from one stage of the compression unit.

[0016] Advantageously, the installation may further include: - at least one thermal storage system comprising:

[0017] - a secondary combustion gas circulation line connected to at least a combustion gas supply line, on either side of the first heat exchanger of at least one heat pump unit,

[0018] - a thermal storage device connected to the secondary line and capable of to receive or release calories to the oxidizing gas passing through it,

[0019] - optionally an electric heating device mounted on the pipe secondary upstream of the thermal storage device with respect to a direction of combustion gas flow during a charging phase, or integrated into the thermal storage device,

[0020] - a thermal storage system management system and at least one heat pump unit, and optionally an electric heating device, configured, in particular programmed, for:

[0021] (i) in a charging phase in which at least one storage system The body accumulates calories: circulate through the first heat exchanger of at least one heat pump unit the entire flow of combustion gas circulating in at least one combustion gas supply line, and operate at least one heat pump unit to heat the combustion gas to a target temperature, circulate through at least one thermal storage system a fraction of the combustion gas flow circulating in at least one combustion gas supply line, this fraction being taken from the outlet of the first heat exchanger of at least one heat pump unit, optionally controlling the electric heating device to further heat said extracted fraction,

[0022] (ii) in a discharge phase in which the at least one storage system Thermal energy provides calories: circulate through at least one thermal storage system all or a fraction of the combustion gas flow circulating in at least one combustion gas supply line to heat it to the target temperature or to a first temperature, this combustion gas flow being taken upstream of the first heat exchanger of at least one heat pump unit, optionally shutting down the electric heating device; and stop at least one heat pump unit, or circulate through the first heat exchanger of at least one heat pump unit the remainder of the combustion gas flow circulating in at least one combustion gas supply line and operate at least one heat pump unit to heat to a second temperature this remaining fraction of combustion gas flow which, in mixing with the fraction of combustion gas flow at the first target temperature, reaches the target temperature.

[0023] The first and second temperatures can be determined based on the flow rates to be heated so that the mixture of the two fractions of combustion gas flow (at the outlet of the heat pump and the storage device) reaches the desired target temperature. The second temperature can, for example, be lower than the target temperature, so that the heat pump operates at partial load and is thus relieved of load. The first temperature can, for example, be greater than or equal to the target temperature.

[0024] Thus, during the charging phase, a portion of the combustion gas, heated by at least one heat pump unit and optionally further heated by an electric heating device, circulates through the storage device, allowing the latter to accumulate heat. The charging phase can be sufficiently long to allow for optimal heat accumulation in the storage device. During the discharging phase, at least a portion of the combustion gas is heated by the thermal storage device, with the remainder of the combustion gas being heated by at least one heat pump unit. This allows the at least one heat pump unit to be relieved of some of its workload, particularly because the flow rate of combustion gas it must heat is lower than the flow rate of combustion gas it must heat during the charging phase, thereby reducing its electrical consumption.In one embodiment, the entire combustion gas flow can be heated to the target temperature by the thermal storage device, at least one heat pump unit being then switched off.

[0025] Advantageously, the installation may include at least two heat pump units, the first heat exchangers of the heat pump units being mounted in parallel on at least one combustion gas supply line. This arrangement may allow the use of lower-capacity heat pump units, and / or provide for the continuous operation of one or two heat pumps, with the remaining units serving as backup units, and / or specific control of the heat pumps.

[0026] For example, the installation may then include a management system for at least two heat pump units configured, in particular programmed, to:

[0027] - order at least one heat pump unit to heat to a target temperature at least a fraction of the combustion gas flow rate circulating in at least one combustion gas supply line, and / or

[0028] - in a charging phase of at least one thermal storage system: circulate through the first heat exchanger of at least one heat pump unit the entire flow of combustion gas circulating in at least one combustion gas supply line, and operate at least one heat pump unit to heat this flow of combustion gas to a target temperature; circulate through at least one thermal storage system a fraction of the flow of combustion gas circulating in at least one combustion gas supply line, and control at least one other heat pump unit, and optionally control the electric heating device, to heat this fraction taken from the outlet of the first heat exchanger of said at least one other heat pump unit; and - during a discharge phase of at least one thermal storage system: circulate through at least one thermal storage system all or a fraction of the combustion gas flow circulating in at least one combustion gas supply line to heat it to the target temperature or to a first temperature, this combustion gas flow being taken upstream of at least one heat pump unit, optionally shut down the electric heating device, and stop at least one heat pump unit used in the charging phase to heat the combustion gas entering at least one thermal storage system, stop at least one other heat pump unit used in the charging phase to heat the combustion gas to the target temperature or command it to heat to a second temperature a fraction of the combustion gas flow which, in mixing with the fraction of combustion gas flow at the first target temperature, reaches the target temperature.

[0029] The invention also relates to a steam cracking process implemented in a steam cracking plant according to the invention, characterized in that it comprises: - a cracking step of a hydrocarbon feedstock in the cracking furnace at a cracking temperature, this cracking temperature being obtained by the combustion in the burners of the steam cracking furnace of a mixture of combustion gas and hot oxidizing gas, in which the heating of the oxidizing gas before its entry into the burners is carried out by at least one heat pump unit and comprises: (a) supply the first heat exchanger of at least one heat pump unit with combustion gas to be heated, (b) supply the second heat exchanger of at least one heat pump unit with a cold fluid; (c) recover from the outlet of the first heat exchanger of at least one heat pump unit a combustion gas at a target temperature.

[0030] The oxidizing gas to be heated can, before heating, be at an initial temperature ranging from ambient temperature to 150 °C, and be heated to a target temperature higher than this initial temperature, the target temperature being able to range from 200 to 700 °C, preferably from 300 to 600 °C.

[0031] Advantageously, when the installation includes at least one thermal storage system, the heating of the combustion gas of the process according to the invention may then further include:

[0032] (i) a charging phase in which at least one thermal storage system accumulates calories, during which: The entire flow of combustion gas circulating in at least one combustion gas supply line is circulated through the first heat exchanger of at least one heat pump unit, and at least one heat pump unit is operated to heat this flow of combustion gas to a target temperature. A fraction of the flow of combustion gas circulating in at least one combustion gas supply line is circulated through at least one thermal storage system, this fraction being taken from the outlet of the first heat exchanger of at least one heat pump unit. Optionally, the electric heating device is activated to further heat the said extracted fraction.

[0033] (ii) a discharge phase in which at least one thermal storage system provides heat, during which: All or a fraction of the combustion gas flow circulating in at least one combustion gas supply line is circulated through at least one thermal storage system to heat it to the target temperature or a first temperature, this gas flow being taken upstream of the first heat exchanger of at least one heat pump unit; optionally, the electric heating device is switched off; and At least one heat pump unit is stopped, or the remaining combustion gas flow circulating in at least one combustion gas supply line is circulated through the first heat exchanger of at least one heat pump unit, and at least one heat pump unit is operated to heat this remaining fraction of combustion gas flow to a second temperature. which, when mixed with the fraction of oxidizing gas flow at the first target temperature, reaches the target temperature.

[0034] When the installation includes at least two heat pump units, at least one heat pump unit can be ordered to heat to a target temperature at least a fraction of the combustion gas flow circulating in at least one gas supply line.

[0035] Alternatively or in combination, when the installation includes at least two heat pump units and at least one thermal storage system, the process may then include:

[0036] - in a charging phase of at least one thermal storage system: The entire flow of combustion gas circulating in at least one combustion gas supply line is circulated through the first heat exchanger of at least one heat pump unit, and at least one heat pump unit is operated to heat this flow of combustion gas to a target temperature. A fraction of the flow of combustion gas circulating in at least one combustion gas supply line is circulated through at least one thermal storage system, and at least one other heat pump unit, and optionally an electric heating device, is controlled to heat this fraction taken from the outlet of the first heat exchanger of this at least one other heat pump unit. - in a discharge phase of at least one thermal storage system: all or a fraction of the combustion gas flow circulating in at least one combustion gas supply line is circulated through at least one thermal storage system to heat it to the target temperature or to a first temperature, this combustion gas flow being taken upstream of at least one heat pump unit; optionally, the electric heating device is switched off, and at least one heat pump unit used in the charging phase to heat the combustion gas entering at least one thermal storage system is stopped. at least one other heat pump unit used in the charging phase to heat the combustion gas to the target temperature is stopped or it is controlled to heat to a second temperature a fraction of the combustion gas flow which, in mixing with the fraction of combustion gas flow at the first target temperature, reaches the target temperature.

[0037] The installation and process according to the invention are particularly suitable for steam cracking of ethane but can also be implemented for steam cracking of other hydrocarbon feedstocks such as petroleum gas. Liquefied petroleum gases (propane, butane), naphtha, diesel fuel, and vacuum distillates are among the possible hydrocarbon feedstocks. Other potential hydrocarbon feedstocks include bio-derived hydrocarbons such as ethane, propane, butanes, naphtha, and distillates produced during the hydrotreating / hydrocracking of fatty acid esters (e.g., triglycerides), biomass pyrolysis oils, or hydrothermal biomass liquefaction oils. Other possible hydrocarbon feedstocks include hydrocarbons obtained through pyrolysis, hydrothermal liquefaction, or hydrocracking of plastic waste. Detailed description of the invention Description of the figures

[0038] The invention is now described with reference to the accompanying, non-limiting drawings, in which:

[0039] [Fig-1] Fig.1 schematically represents a steam cracking installation comprising at least one heat pump unit according to an embodiment of the invention.

[0040] [Fig.2] Fig.2 schematically represents a steam cracking installation comprising at least one heat pump unit according to another embodiment of the invention.

[0041] [Fig.3] Fig.3 schematically represents a steam cracking installation comprising three heat pump units and a thermal storage system in different operating modes (a), (b), (c).

[0042] [Fig.4] Fig.4 schematically represents an example of an installation of complete steam cracking according to the invention.

[0043] [Fig.5] Fig.5 schematically represents an example of a compression unit of a steam cracking plant.

[0044] [Fig.6] Fig.6 schematically represents an example of a cryogenic cooling unit of a steam cracking plant.

[0045] In the figures, the same elements are designated by the same references.

[0046] The terms "upstream" and "downstream" are used in relation to the flow of fluids, symbolized by arrows on the figures.

[0047] The various units of a steam cracking plant include many components requiring either an electrical power supply, or a thermal power supply, or both.

[0048] In particular, the steam cracking furnace, also called a steam cracking reactor, includes supply lines for the fluids entering the steam cracking reactor(s) and sections for heating the fluids and / or producing steam entering the reactor(s).

[0049] The thermal energy required for the steam cracking reaction is supplied by the combustion of a fuel gas with an oxidizing gas (air, etc.). Approximately 40 to 50% of the heat of combustion is absorbed in a radiant zone of the steam cracking furnace, the remainder passing to a convection zone where the majority of the sensible heat of the combustion gases is exchanged to preheat the hydrocarbons and / or water and / or steam via at least one heat exchanger.

[0050] In the present invention, the oxidizing gas, typically air, supplying the burners of the steam cracking furnace is heated to a target temperature by means of one or more heat pumps.

[0051] Figure 1 schematically represents a steam cracking plant 100 comprising a steam cracking furnace 10, two cooling units 12, 14, and a heat pump unit 20, also called a "heat pump" and denoted as TFP in the following description. The burners of the steam cracking furnace (not shown) are supplied with combustion gas via the supply line 1.

[0052] As shown, the TFP 20 comprises a circuit 200 in which a working fluid, preferably a gas (argon, helium, N2, CO2, air, ...), circulates. This circuit 200 comprises, mounted in series in the direction of flow of the working fluid: - a first heat exchanger Ech_1, the working fluid circulating in the latter transferring heat to the combustion gas circulating in the first heat exchanger supplied by the combustion gas supply line 1, - an expansion device 202, - a second heat exchanger Ech_2, the working fluid circulating in the second heat exchanger transferring cooling to at least one fluid to be cooled circulating in the second heat exchanger and coming from one of the cooling units, - a compression device 204.

[0053] Typically, the combustion gas circulating in the supply line 1 enters the exchanger Ech_l at a temperature ranging from ambient temperature to 150 °C and exits at a higher target temperature, generally from 200 to 700 °C, most often from 300 to 600 °C.

[0054] The working fluid circulating in the second heat exchanger Ech_2 can thus transfer cooling to a process fluid to be cooled, which in this case comes from the cooling unit 14 supplied by a line 3. This cooling unit 14 can advantageously be a cryogenic cooling unit from the steam cracking plant, typically comprising several cooling units as described below. Alternatively, the fluid to be cooled could come from the compression unit, as described below.

[0055] These components are sufficient to allow the combustion gas to be heated to the target temperature. To this end, the various components of the TFP can be sized to produce the desired thermal energy (calories).

[0056] The expansion element can be an expansion valve (electronic expansion valve, calibrated orifice, etc.) or a turbine. The compression element, referred to hereafter as the compressor, is typically driven by an electric motor. In some cases, it can also be driven, at least partially, by the turbine when one is present.

[0057] The TFP cycle is a classic heat pump cycle: heat is extracted from a hot source to be cooled (the fluid to be cooled circulating in pipe 3 and entering the heat exchanger Ech_2). The compressor 204 increases the pressure / temperature of the working fluid at the inlet of the heat exchanger Ech_1, thus preheating the combustion gas. The cooled working fluid exiting the heat exchanger Ech_1 is then expanded in the expansion chamber to be reheated in the heat exchanger Ech_2. To optimize the cycle efficiency, the expansion chamber can advantageously be a turbine. The work done by the compressor 204 depends on the electrical power supplied to the compressor, typically via an electric motor driving the compressor. The electrical consumption of the TFP can therefore vary depending on the target temperature to which the TFP must heat the combustion gas.

[0058] Given the temperatures to be reached (200-700 °C), this is typically a "reverse" Brayton cycle preferably using a working fluid remaining in the gaseous phase.

[0059] To improve the efficiency of the heat pump 20, the circuit 200 may include a third heat exchanger Ech_3, located between the second heat exchanger Ech_2 and the compressor 204. The working fluid circulating in this third heat exchanger receives heat from a hot fluid to be cooled (waste heat) originating from the installation, for example, from a cooling unit 12 or a compression unit. This hot fluid may also come from ambient air or from an installation other than the steam cracking plant. This hot fluid may, for example, be water circulating in a pipe 5 and originating from a cooling unit 12. The latter is typically located immediately after the steam cracking furnace 10 and serves to rapidly cool, by quenching, the cracked gases exiting the TLX behind the steam cracking furnace.The water circulating in pipe 5 can thus enter the heat exchanger Ech_3 at a temperature of 75-85 °C and exit at a lower temperature of 65-75 °C. This hot fluid can also come from the compression unit, and for example be taken from the outlet of one of the compressor stages of this unit.

[0060] In the example shown in [Fig. 2], the TFP includes a fourth heat exchanger Ech_4 between the first heat exchanger Ech_1 and the expansion device 202, in order to cool the working fluid before it enters the expansion device 202. The working fluid circulating in the fourth heat exchanger receives cooling from a cold fluid supplied by a pipe 205, as shown in [Fig. 2]. This cold fluid can be water, for example at a temperature of 10 to 25 °C, or ambient air. This exchanger allows, in particular, for subcooling of the fluid circulating in the circuit 200 before it enters the expansion device 202, especially when the combustion gas entering the exchanger Ech_1 is at a temperature higher than the ambient temperature. This then makes it possible to further reduce the negative temperature at the outlet of the expansion device and thus produce cooling at a lower temperature.

[0061] Thus, in one embodiment, the TFP 20 comprises only the first and second heat exchangers Ech_1, Ech_2, and in a preferred embodiment, the TFP 20 comprises the first, second, and third heat exchangers Ech_1, Ech_2, Ech_3, while in another preferred embodiment, the TFP 20 comprises the first, second, third, and fourth heat exchangers Ech_1, Ech_2, Ech_3, Ech_4. In each of these embodiments, heat exchanger Ech_2 can be replaced by two or more Ech_2s connected in series or parallel; each Ech_2 can then be used to cool a specific fluid. Heat exchanger Ech_3 can also be replaced by two or more Ech_3s connected in series or parallel.

[0062] In general, the installation 100 may include a management system 22 for controlling the TFP. This management system 22 may, in particular, regulate the target temperature of the combustion gas at the outlet of the heat exchanger Ech_len, regulating the electrical power supplied to the TFP, and in particular to its compressor, and regulate the target temperature of the fluid to be cooled exiting a heat exchanger Ech_2.

[0063] In order to reduce the electrical consumption of the TFP, particularly when the cost of electricity is high, in an embodiment schematically represented [Fig.2], the installation 100 may include a thermal storage system 24. The embodiment of [Fig.2] differs from that represented [Fig.1] only by the presence of a thermal storage system 24, the TFP 20 comprising four exchangers Ech_1, Ech_2, Ech_3, Ech_4.

[0064] This thermal storage system 24 comprises:

[0065] - a secondary air circulation duct 240 connected to the duct combustion gas supply 1, on either side of the first heat exchanger Ech_l of the TFP 20, - a thermal storage device 242 connected to the secondary line 240 and capable of receiving or releasing heat to the combustion gas passing through it, - optionally an electric heating device 244 mounted on the secondary pipe 240 upstream of the thermal storage device 242.

[0066] The electric heating device may be a Joule (resistive), induction, microwave, shock wave, plasma, or a combination of these devices, preferably a Joule and / or induction heating device. It is located upstream of the thermal storage device 242, particularly with respect to the gas flow when the thermal storage system is in a charging phase. Alternatively, this electric heating device may be integrated into the thermal storage device.

[0067] The secondary line 240 can be connected to the supply line 1 by one or more valves and include one or more fans to draw the combustion gas flowing in the supply line 1 upstream or downstream of the heat exchanger Ech_l and circulate it in the secondary line 240 in one direction or the other, depending on the operating mode of the thermal storage system, as described below. In [Fig. 2], the secondary line 240 is equipped with a valve 245 and a fan 246, and is connected to the supply line 1 by a valve 247. The invention is, of course, not limited by the number of valve(s) and / or fan(s) or by their position.

[0068] Preferably, sensible heat storage devices 242 will be used, employing a solid thermal storage medium (generally in the form of powders, particles, or solid blocks with open cavities and / or channels) having suitable thermal storage capacities and / or capable of achieving heat transfer rates suitable for the intended use. This solid medium may, for example, be contained in an insulated tank. Suitable solid media include metals, volcanic rocks, or refractory materials such as alumina, etc. Thermal storage devices containing volcanic rocks produced by Brenmiller Energy may thus be used.Stacked refractory materials can also be used; the storage device could, for example, be similar to a glass furnace regenerator and contain a stack of refractory materials, which could be cruciform, brick-shaped, bushel-shaped, or pot-shaped. Electrically conductive refractory bricks can also be used, which can be heated by circulating gas and / or by an electric current passing through the bricks during the charging of the thermal storage (for example, refractory bricks from a Joule Hive Thermal Battery).

[0069] This thermal storage system 24 is controlled by the management system 22 configured to operate the thermal storage system 24 cyclically in a charging phase in which it accumulates heat and in a discharge phase in which it releases the accumulated heat. The management system 22 will also control the TFP(s) 20 of the installation according to the operating mode of the thermal storage system 24, and one or more valves regulating the flow rates of combustion gas circulating in the pipes 1 and 240.

[0070] In particular, the management system 22 can be configured, in particular programmed, to:

[0071] (i) in a charging phase of the thermal storage system, circulate to through the thermal storage device 242 a fraction of the combustion gas flow circulating in the supply line 1, this fraction being taken from the outlet of the first heat exchanger Ech_l of the TFP, optionally further heated by the electric heating device 244; to circulate through the first heat exchanger Ech_l of the TFP the entire combustion gas flow circulating in at least one combustion gas supply line upstream of the TFP; and to operate the TFP 20 to heat the combustion gas to a target temperature, typically at least 200°C, generally from 300 to 600°C,

[0072] (ii) In a discharge phase of the thermal storage system, circulate through the thermal storage device 242 all or a fraction of the combustion gas flow rate circulating in the combustion gas supply line 1 upstream of the TFP to heat it to the target temperature or to a first temperature, for example close to that of the thermal storage device 242, this fraction being taken upstream of the first heat exchanger Ech_l of the TFP; and stop the TFP 20 or operate the TFP 20 to heat to a second temperature a remaining fraction of the combustion gas flow rate to reach the target temperature at point 243 where the two combustion gas flows are mixed. In this phase, the electric heating device is also stopped.

[0073] When the thermal storage system operates in discharge mode, it is therefore possible to completely stop the TFP or to reduce its electrical consumption by about 25% compared to its operation in charge mode.

[0074] In particular, it is possible to configure the management system to operate the thermal storage system in load mode when electricity is cheaper and / or comes from decarbonized sources (wind, solar, nuclear power plant, hydroelectric, ...), which makes it possible to decarbonize the electrical consumption of the installation and / or reduce operating costs.

[0075] Preferably, the inlet temperature of the thermal storage device during the charging phase is higher than the target temperature of the combustion gas to be achieved, for example, at least 20 to 40 °C higher. This temperature can be reached either solely by the heat supplied by the TFP, or by the heat supplied by the TFP and the auxiliary heating device 244. This The latest implementation may be preferable in order to avoid having to oversize a TFP.

[0076] For greater availability or system flexibility, the installation may include one or more TFPs connected in parallel. For example, 2, 3, or 4 TFPs, or even more, may be connected in parallel, preferably in combination with a thermal storage system.

[0077] This allows, in particular, the use of TFPs of the same power that can operate simultaneously or not to provide the heat necessary for heating the combustion gas. This can, in particular, allow the use of commercially available TFPs without having to design a TFP specifically sized for the present application.

[0078] Figure 3 schematically represents an installation comprising three TFPs, labeled TFP1, TFP2, and TFP3, connected in parallel. Each TFP can be as described with reference to Figure 1 or 2, with or without heat exchangers Ech_3 and / or Ech_4. The first heat exchanger Ech_1 of each TFP is then connected in parallel to the combustion gas supply line 1, on branches 1a, 1b, and 1e of this line, as shown in Figure 3. The combustion gas flow rates circulating in each of the branch lines 1a, 1b, and 1e and in the circuit 240 of the thermal storage system can be controlled by one or more valves labeled V, Via, Vlb, Vie, and V240 in Figure 3. For the sake of simplicity, certain elements of the thermal storage system 24 are not shown in [Fig.3] when not in use.

[0079] In nominal mode, shown in [Fig. 3](a), two TFPs (TFP1 and TFP2) operate to provide the heat necessary to heat each a fraction of the combustion gas flow circulating in bypass lines 1a and 1b respectively from 25 °C to 540 °C. The third TFP, TFP3, does not operate, nor does the thermal storage system 24.

[0080] In a charging mode of the thermal storage system 24 shown in [Fig. 3](b), two of the TFPs (TFP1 and TFP2) operate to supply the heat necessary to heat each a fraction of the combustion gas flow circulating in the bypass lines 1a and 1b respectively from 25 °C to 540 °C, while the third TFP, TFP3, operates to "charge" the thermal storage system 24: a fraction of the combustion gas flow heated by the third TFP, TFP3, possibly further heated by the auxiliary electric heating device 244, passes through the thermal heating device 242, allowing it to accumulate heat. When the accumulation is sufficient, and in particular when the cost of electricity is high, the thermal storage system 24 can then switch to discharge mode, as shown in [Fig. 3](c), or to nominal mode. as shown in [Fig. 3](a). In discharge mode, the third TFP (TFP3) is then off, as is the auxiliary electric heating device 244, while only one of the other two TFPs (here, TFP1) is operating. The heat produced by the single operating TFP and by the thermal heating system 24 then allows the combustion gas to be heated from 25 °C to 540 °C. The gas flow rate in the supply line 1 is thus divided between the secondary line 240 and the bypass line 1a. With only one of the TFPs operating, the overall electrical consumption is reduced compared to the other two operating modes (a) and (b). The gas flow rate in the bypass line 1a can also be chosen to be lower than the flow rate in the secondary line 240 in order to further reduce the electrical power required by TFP1.

[0081] In the event of a malfunction of one of the three TFPs, the thermal storage system 24 can be deactivated so as to use the other two TFPs in nominal mode to heat the combustion gas.

[0082] The invention is not limited to this use of the three TFPs: in particular, in nominal mode or in charging phase, the three TFPs can operate simultaneously, at least one of the TFPs being stopped or operating at reduced load in discharging phase.

[0083] Of course, the present invention is not limited by the number of TFPs, which can be chosen according to the power of the available TFPs. Two or four TFPs, or more, could be provided, operating alternately or together in different configurations, preferably in combination with a thermal storage system to reduce the electrical consumption of the TFPs.

[0084] It would also be possible to provide two, three or four TFPs, or more, mounted in parallel, but without a thermal storage system, although this is not preferred.

[0085] When several TFPs are mounted in parallel, it may be advantageous to use identical TFPs.

[0086] The management system 22 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 TFP(s) used in the present invention, as well as the electric heating device of the thermal storage system when present, and the thermal storage system when present. It can thus be connected to these components, and in particular to the components of each TFP used, and optionally to one or more valve(s), fan(s), pump(s), or other element used for fluid circulation and flow regulation, and / or to the power supply of the components and / or to the control of these components.

[0087] The management system 22 can further receive various information from one or more appropriately arranged sensors relating to:

[0088] - to the power supply (electrical and / or thermal) of each TFP (quantity of current received and consumed, temperature and / or flow rate of fluids whose temperature is controlled),

[0089] - in the charging and discharging state of each thermal storage system (temperature of thermal storage devices),

[0090] - to the phase in which each thermal storage system is located (charge, dump),

[0091] - to the quantity of electrical and / or thermal energy received / produced by each TFP and / or electric heating device (quantity of current, flow rate and / or temperature of fluids).

[0092] The management system 22 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 may form means of communication, optionally bidirectional, between the management system and the components of the TFP(s), the energy storage system, and / or the heating elements.

[0093] The management system 22 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.

[0094] The process and steam cracking installation are described in more detail with reference to [Fig.4] which schematically represents a complete steam cracking installation 100, comprising a steam cracking furnace 10, cooling units, a compression unit and fractionation units.

[0095] The hydrocarbon feedstock cracking step is carried out in the steam cracking furnace 10 at a cracking temperature, this cracking temperature being obtained by the combustion in the burners of the steam cracking furnace of a mixture of combustion gas and hot oxidizing gas. For this purpose, the hydrocarbon feedstock to be treated is introduced into heat exchangers, located in the convection zone of the steam cracking furnace 10 via a pipe 102, typically at a temperature of 60°C, optionally by means of a pump 1031 when the feedstock is liquid, and the dilution steam is introduced into heat exchangers, located in the convection zone of the steam cracking furnace via the pipe 104.

[0096] Typically, the steam cracking furnace 10 comprises a lower radiant section 10a and an upper convection section 10b. The heat to the radiant section 10a is supplied by the combustion of a fuel (generally gas). fuel, such as methane or H2) in the presence of an oxidizer (air, etc.) in at least one burner. The steam cracking furnace 10 thus comprises one or more fuel supply lines 105 and one or more oxidizer supply lines 1 to one or more burners. Combustion takes place in one or more burners located in the base, the ceiling, and / or the side walls of the lower part of the furnace enclosure 10. The TFP 20 used according to the invention is thus located on the line 1

[0097] The hydrocarbon feedstock and dilution steam are injected into at least one heat exchanger tube bundle (not shown) located in the convection zone 10b. The two streams can be preheated separately and then mixed and further preheated in at least one heat exchanger tube bundle, typically to a temperature between 600 and 680°C. This mixture is then distributed into one or more tube reactors (not shown) located in the radiation zone 10a. By means of the burners in the radiation zone, the tube reactors are further heated to initiate thermal cracking. The effluent temperature at the outlet of the tube reactors is typically between 800 and 900°C.

[0098] The effluent exiting the steam cracking furnace is then rapidly cooled (quenched) in one or more cooling units 11, 12, 17, then purified and separated in compression units 13 and fractionation units 15.

[0099] 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.

[0100] Typically, at the outlet of the steam cracking furnace reactor(s) 10, the cracked gases are discharged via a pipe 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.

[0101] In some 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.

[0102] At the outlet of the fractionation column 17, the fractionated overhead gases are conveyed via a line 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 line 113. In the 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 part of it, can be circulated in the line 5 of the third heat exchanger Ech_3 of a TFP as a heat source.

[0103] The heaviest hydrocarbons recovered at the bottom of the quenching tower 12 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.

[0104] 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.

[0105] The compression unit 13 typically comprises a series of compression stages, generally 3 to 6, each stage including a compressor, a cooling means (e.g., 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 gasoline are removed.

[0106] An example of such a compression unit, well known to those skilled in the art, is schematically represented in [Fig. 5], in which four compression stages are provided. The compressors are designated by reference numerals 1301, 1302, 1303, 1304; the cooling means, for example heat exchangers, are designated by reference numerals 1311, 1312, 1313, 1314; and the separation devices are designated by reference numerals 1321, 1322, 1323, 1324. At the inlet of the first stage, the cracked gases are conveyed via a pipe into a separation device 1325 in order to to separate the condensed hydrocarbons. At each stage, the gases are compressed in the compressor and then cooled by the cooling systems before entering the separation devices. The gases exiting the separation device are sent to the inlet of the compressor of the next stage. At the outlet of the penultimate stage, the gases are sent to a purification section 1340 to remove acidic gases, typically by scrubbing with a caustic solution or an amine solution, or both. At the outlet of the last compression stage, the gases are finally sent to a drying section 1350 to remove residual water. The mechanical energy required to rotate the compressors of the different stages is supplied by a steam turbine or an electric motor 1300.

[0107] 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.

[0108] 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.

[0109] The third cooling unit 14 includes, for example, refrigeration cycles typically 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 through a compressor, then cooled in a heat exchanger, and then further cooled by expansion. Typically, in this refrigeration cycle, the temperature of the ethylene is in the range of -100 to -40 °C, and the temperature of the propylene is in the range of -40 to 15 °C. Other refrigeration cycles are, however, possible.

[0110] Figure 6 schematically represents an example of a refrigeration cycle 30 comprising an ethylene refrigeration cycle 31 and a propylene refrigeration cycle 32 for process fluids to be cooled circulating in pipes 33 and 34. In the ethylene refrigeration cycle 31, ethylene is compressed in a compressor 310, then sent to a heat exchanger 311 where it is cooled by the propylene circulating in the propylene refrigeration cycle 32 and becomes liquid. The high-pressure liquid ethylene is then collected in a vessel 312, then depressurized by passing through a pressure-reducing valve 313, and introduced into a gas-liquid separation vessel 314 where the liquid ethylene is In the propylene refrigeration cycle 32, propylene is sent to a heat exchanger 315 to cool a process fluid circulating in line 33. At the outlet of this exchanger 315, the gaseous ethylene is returned to the separator 314 and then to the compressor 310. In the propylene refrigeration cycle 32, propylene is compressed in a compressor 320, then sent to a heat exchanger 321 where it is cooled by water or air and becomes liquid. The liquid propylene is then collected in a tank 322, then depressurized by passing through a pressure-reducing valve 323, and introduced into a gas-liquid separation vessel 324. In this vessel, the liquid propylene is sent to the heat exchanger 311 to condense the ethylene and / or sent to a heat exchanger 325 to cool a process fluid circulating in line 34. At the outlet of this exchanger 311, the gaseous propylene is returned to the separator 324 then into compressor 320.

[0111] 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) of the latter (de-methanizer), typically in several stages using ethylene, propylene and methane / hydrogen as refrigerant: (1) cooling of the cracked gases to about -70 to -100°C using propylene and / or ethylene in several stages, followed each time by a separation of the condensed hydrocarbons which are injected into the de-methanizer, (2) cooling of the remaining gases to about -125°C using methane / hydrogen, followed by a separation of the condensed hydrocarbons and (3) cooling of the remaining gases to about -165°C using methane / hydrogen, followed by a separation of the condensed methane and producing a hydrogen stream of more than 90 vol% purity.This type of configuration corresponds to a "de-methanizer first" fractionation unit sequence. However, the invention is not limited to this configuration and can be adapted to other fractionation unit configurations, particularly "de-ethanizer first" or "de-propanizer first" configurations.

[0112] 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.

[0113] 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.

[0114] The hot fractionation section of the fractionation unit 15 includes reboilers and heat exchangers.

[0115] 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 or thermal energy to operate.

[0116] [Fig.5], the cold thermal energy from the second heat exchanger Ech_2 of a TFP 20 can be applied upstream of compressors 1301-1304, typically upstream of tanks 1321-1325, and downstream of heat exchangers 1311-1314, to further cool the fluid to a temperature not lower than 15 °C, and reduce their energy consumption. For this purpose, the fluid to be cooled circulates in line 3 of the second heat exchanger Ech_2 of a TFP.

[0117] Alternatively or in combination, the hot fluid exiting compressors 1301-1304 or heat exchangers 1311-1314 of the compression unit shown [Fig. 5] can also be used as the hot fluid inlet to a third heat exchanger Ech_3 of the TFP 20. This hot fluid then circulates in the line 5 of the third heat exchanger Ech_3. For example, the fluids exiting heat exchangers 1311-1314, typically at a temperature of 80-95°C, can be used as the hot fluid supplying a third heat exchanger Ech_3 before entering a third heat exchanger Ech_2 as a cold fluid for further cooling, without lowering them below 15°C to avoid the formation of hydrates.

[0118] [Fig.6], in particular, cold thermal energy can be supplied at the level Heat exchangers 316 and 326 are located upstream or downstream of the compressors to subcool the fluids circulating in cycles 31 and 32. These heat exchangers 316 and 326 are situated respectively between tank 312 and valve 313, and between tank 322 and valve 323. This reduces the compression work required by compressors 310 and 320 to generate the same amount of cooling in heat exchangers 315 and 325. The fluids upstream of compressors 310 and 320 can be cooled, for example, fluids 33 and 34. Generally, cold thermal energy (around +15°C) can be applied to the discharge outlet of compressor 320 to reduce the discharge pressure (and the power required). on exchanger 326, at a fraction of the flow 34 (temperatures + 15 °C to -40 °C), on exchanger 316, at a fraction of the flow 33 (temperatures from -40 °C to -100 °C).

[0119] For this purpose, the fluid to be cooled circulates in the line 3 of the second heat exchanger Ech_2 of a TFP. When several fluids are to be cooled, each fluid to be cooled can circulate in a line 3 of a dedicated heat exchanger Ech_2, which is part of several heat exchangers Ech_2 of the same TFP connected in series.

[0120] When several TFPs are used, each TFP may include a second heat exchanger Ech_2, or several Ech_2s connected in series or parallel. The Ech_2 heat exchanger(s) of one TFP are, for example, used to cool a fluid or fluids from different stages of the compression unit. The Ech_2 heat exchanger(s) of the other TFP are used to cool a fluid or fluids from different stages of the cryogenic cooling unit.

[0121] The invention is not limited by the number of stages of the cryogenic cooling unit and the compression unit: the number of stages of these units may be different from the number of stages of the units shown in Figures 5 and 6. Example

[0122] In the case of a thermal heat pump (THP) with four heat exchangers as shown in [Fig. 2] and a thermal storage system as described with reference to [Fig. 2] (without auxiliary heating), Table 1 summarizes the calculated power outputs of each element in nominal mode (storage system at rest), in thermal storage system charging mode, and in thermal system discharging mode. The storage device used comprises 550 m³ of bricks as the heat transfer material. It can be seen that, even in nominal mode, the present invention reduces the overall electrical consumption of the installation by reducing the electrical power normally required by the cooling unit (here, a cryogenic cooling unit).

[0123] [Table 1] Table 1 Nominal mode Load mode Exhaust mode Combustion air inlet temperature from 1 to TFP 25 °C 25 °C 25 °C Combustion air outlet temperature from 1 to TFP 534 °C 534 °C 534 °C Temperature of fluid circulating in duct 3 entering Ech_2 80 °C 80 °C 80 °C Temperature of the fluid circulating in pipe 3 exiting Ech_2: 75 °C 70 °C 78 °C Thermal power produced by Ech_1: 51 MWth 80 MWth 22 MWth Thermal power produced by Ech_2: 16 MWth 25 MWth 7.1 MWth Thermal power produced by Ech_3: 7.7 MWth 12 MWth 3.3 MWth Thermal power produced by Ech_4: 10.9 MWth 17 MWth 4.7 MWth Thermal power received / supplied by the thermal storage system: 29 MWth 29 MWth Electrical power consumed by the compressor: 38.2 MWe 60 MWe 16.3 MWe Electrical power not consumed by the cooling unit (*): -11.2 MWe -16.6 MWe -5 MWe

[0124] (*) compared to operation without TFP and without thermal storage.

Claims

Demands

1. Steam cracking installation (100) comprising at least: - a steam cracking furnace (10), - a cooling unit (12, 14), - a compression unit (13), in which the steam cracking furnace comprises a radiant zone equipped with burners connected to at least one fuel gas supply line and to at least one oxidizing gas supply line (1), characterized in that the installation is further equipped with at least one heat pump unit (20, TFP1, TFP2, TPF3) comprising a circuit (200) in which a working fluid circulates, this circuit (200) comprising, mounted in series in the direction of flow of the working fluid: - a first heat exchanger (Ech_l), the working fluid circulating in the first heat exchanger transferring heat to the oxidizing gas circulating in the first heat exchanger supplied by at least one oxidizing gas supply line, - a relaxation device (202),- at least one second heat exchanger (Ech_2), the working fluid circulating in the second heat exchanger transferring cooling to at least one fluid to be cooled circulating in the second heat exchanger and originating from at least one cooling unit (14) and / or at least one compression unit (13), - a compression element (204).

2. Steam cracking installation (100) according to claim 1, characterized in that at least one heat pump unit (20, TFP1, TFP2, TPF3) further comprises, mounted on the circuit (200) between at least one second heat exchanger (Ech_2) and the compression unit (204), at least one third heat exchanger (Ech_3), the working fluid circulating in the third heat exchanger receiving heat from a hot fluid.

3. Steam cracking installation according to claim 1 or 2, characterized in that at least one heat pump unit (20, TFP1, TFP2, TPF3) further comprises, mounted on the circuit (200) between the first heat exchanger (Ech_l) and the expansion element (202), a fourth heat exchanger (Ech_4), the working fluid circulating in the fourth heat exchanger receiving cooling from a cold fluid.

4. Steam cracking installation (100) according to any one of claims 1 to 3, characterized in that at least one cooling unit (14) comprises several cooling production stages and in that the working fluid of the heat pump circulating in at least one second heat exchanger (Ech_2) transmits cooling to at least one cooling production stage.

5. Steam cracking installation (100) according to any one of claims 1 to 4, characterized in that the compression unit (13) comprises several compression stages and the working fluid of the heat pump circulating in at least one second heat exchanger (Ech_2) can transfer cooling to a fluid supplying at least one compression stage.

6. Steam cracking plant (100) according to any one of claims 1 to 5, characterized in that it further comprises: - at least one thermal storage system (24) comprising: - a secondary combustion gas circulation line (240) connected to at least one combustion gas supply line (1), on either side of the first heat exchanger (Ech_l) of at least one heat pump unit (20, TFP1, TFP2, TPF3), - a thermal storage device (242) connected to the secondary line (240) and capable of receiving or releasing heat to the combustion gas passing through it, - optionally an electric heating device (244) mounted on the secondary line upstream of the thermal storage device (242) with respect to a direction of combustion gas flow during a charging phase, or integrated into the thermal storage device (242),- a management system (22) for the thermal storage system (24) and at least one heat pump unit, and optionally for the electric heating device, configured to: (i) in a charging phase in which at least one thermal storage system accumulates heat: circulate through the first heat exchanger (Ech_l) of at least one heat pump unit the entire flow rate of,

7. combustion gas circulating in at least one combustion gas supply line (1), and operating at least one heat pump unit to heat this combustion gas flow to a target temperature, circulating through at least one thermal storage system (24) a fraction of the combustion gas flow circulating in at least one combustion gas supply line (1), this fraction being taken from the outlet of the first heat exchanger (Ech_l) of at least one heat pump unit, optionally controlling the electric heating device (244) to further heat said taken fraction,(ii) in a discharge phase in which at least one thermal storage system (24) supplies heat: circulate through at least one thermal storage system (24) all or a fraction of the combustion gas flow rate circulating in at least one combustion gas supply line (1) to heat it to the target temperature or to a first temperature, this gas flow rate being taken upstream of the first heat exchanger (Ech_l) of at least one heat pump unit (20, TFP1, TFP2, TPF3), optionally shutting down the electric heating device (244); and, stop at least one heat pump unit (20, TFP1, TFP2, TPF3) or circulate through the first heat exchanger (Ech_l) of at least one heat pump unit (20, TFP1, TFP2, TPF3) the remainder of the combustion gas flow circulating in at least one combustion gas supply line (1) and operate at least one heat pump unit (20, TFP1, TFP2, TPF3) to heat to a second temperature this remaining fraction of combustion gas flow which, in mixing with the fraction of combustion gas flow at the first target temperature, reaches the target temperature. Steam cracking installation (100) according to any one of claims 1 to 6, characterized in that it comprises at least two heat pump units (TFP1, TFP2, TPF3), the first heat exchangers (Ech_l) of the heat pump units being mounted in parallel on at least one oxidizing gas supply line (1).

8. Steam cracking installation (100) according to claim 7, characterized in that it comprises a management system (22) for the heat pump units (TFP1, TFP2, TPF3) configured to: - control at least one heat pump unit (TFP1, TFP2, TPF3) to heat to a target temperature at least a fraction of the combustion gas flow rate circulating in at least one combustion gas supply line (1), and / or - in a charging phase of at least one thermal storage system (24): circulate through the first heat exchanger (Ech_l) of at least one heat pump unit (TFP1, TFP2) the entire flow of combustion gas circulating in at least one combustion gas supply line, and operate at least one heat pump unit (TFP1, TFP2) to heat this flow of combustion gas to a target temperature, circulate through at least one thermal storage system a fraction of the flow of combustion gas circulating in at least one combustion gas supply line, and control at least one other heat pump unit (TFP3), and optionally control said electric heating device (244), to heat this fraction taken from the outlet of the first heat exchanger (Ech_l) of said at least one other heat pump unit (TFP3); and - in a discharge phase of at least one thermal storage system (24): circulate through at least one thermal storage system (24) all or a fraction of the combustion gas flow rate circulating in at least one combustion gas supply line (1) to heat it to the target temperature or to a first temperature, this combustion gas flow rate being taken upstream of at least one heat pump unit (TFP1, TFP2, TFP3), optionally stop the electric heating device (244), and stop at least one heat pump unit (TFP3) used in the charging phase to heat the combustion gas entering at least one thermal storage system (24), stop at least one other heat pump unit (TFP1, TFP2) used in the charging phase to heat the combustion gas to the target temperature or command it to heat to

9.

10. a second temperature a fraction of the oxidizing gas flow rate which, in mixing with the fraction of oxidizing gas flow rate at the first target temperature, reaches the target temperature. A process for steam cracking hydrocarbons implemented in a steam cracking plant (100) according to any one of the preceding claims, characterized in that it comprises: - a step of cracking a hydrocarbon feedstock in the cracking furnace at a cracking temperature, this cracking temperature being obtained by the combustion in the burners of the steam cracking furnace of a mixture of combustion gas and hot oxidizing gas, in which the heating of the oxidizing gas before its entry into the burners is carried out by at least one heat pump unit and comprises: (a) supply the first heat exchanger (Ech_1) of at least one heat pump unit with oxidizing gas to be heated, (b) supply the second heat exchanger (Ech_2) of at least one heat pump unit with a cold fluid; (c) recover from the outlet of the first heat exchanger (Ech_l) of at least one heat pump unit a combustion gas at a target temperature. A process for steam cracking hydrocarbons according to claim 9, wherein, when the installation (100) includes at least one thermal storage system (24), the heating of the combustion gas further comprises: (i) a charging phase in which at least one storage system (24) accumulates heat, during which: the entire flow rate of combustion gas circulating in at least one combustion gas supply line (1) is circulated through the first heat exchanger (Ech_l) of at least one heat pump unit (20, TFP1, TFP2, TFP3), and at least one heat pump unit (20, TFP1, TFP2, TFP3) is operated to heat this flow rate of combustion gas to a target temperature; a fraction of the flow rate of combustion gas circulating in at least one combustion gas supply line (1) is circulated through at least one thermal storage system (24), this fraction being taken from the outlet of the first heat exchanger. heat (Ech_l) from at least one heat pump unit (20, TFP1, TFP2, TFP3), optionally the electric heating device (244) is activated to further heat said extracted fraction, (ii) a discharge phase in which at least one thermal storage system (24) supplies heat, during which: all or a fraction of the combustion gas flow circulating in at least one combustion gas supply line (1) is circulated through at least one thermal storage system (24) to heat it to the target temperature or to a first temperature, this gas flow being extracted upstream of the first heat exchanger (Ech_l) of at least one heat pump unit, optionally the electric heating device (244) is stopped, and at least one heat pump unit (20, TFP1, TFP2, TFP3) is stopped,or the remainder of the combustion gas flow circulating in at least one combustion gas supply line (1) is circulated through the first heat exchanger (Ech_l) of at least one heat pump unit, and at least one heat pump unit (20, TFP1, TFP2, TFP3) is operated to heat this remaining fraction of combustion gas flow to a second temperature, which, when mixed with the fraction of combustion gas flow at the first target temperature, reaches the target temperature.

11. Hydrocarbon steam cracking process according to claim 9 or 10, wherein, when the installation includes at least two heat pump units (TFP1, TFP2, TFP3), at least one heat pump unit is controlled to heat to a target temperature at least a fraction of the combustion gas flow circulating in at least one gas supply line.

12. A process for steam cracking hydrocarbons according to any one of claims 9 to 11, wherein, when the installation comprises at least two heat pump units (TFP1, TFP2, TFP3) and at least one thermal storage system (24): - during a charging phase of at least one thermal storage system (24): the entire of the combustion gas flow rate circulating in at least one combustion gas supply line, and at least one heat pump unit (TFP1, TFP2) is operated to heat this combustion gas flow rate to a target temperature, a fraction of the combustion gas flow rate circulating in at least one combustion gas supply line (1) is circulated through at least one thermal storage system (24), and at least one other heat pump unit (TFP3), and optionally the electric heating device (244), is controlled to heat this fraction taken from the outlet of the first heat exchanger (Ech_l) of this at least one other heat pump unit (TFP3), and - in a discharge phase of at least one thermal storage system (24): all or a fraction of the combustion gas flow circulating in at least one combustion gas supply line (1) is circulated through at least one thermal storage system (24) to heat it to the target temperature or to a first temperature, this combustion gas flow being taken upstream of at least one heat pump unit (TFP1, TFP2, TFP3), optionally the electric heating device (244) is stopped, and at least one heat pump unit (TFP3) used in the charging phase to heat the combustion gas entering at least one thermal storage system (24) is stopped, at least one other heat pump unit (TFP1, TFP2) used in the charging phase to heat the combustion gas to the target temperature or it is controlled to heat to the target temperature a fraction of the combustion gas flow which, in mixing with the fraction of combustion gas flow at the first target temperature, reaches the conceivable target temperature.

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