WO2025119973A1

WO2025119973A1 - Electrically heated reactor system for endothermic reactions

Info

Publication number: WO2025119973A1
Application number: PCT/EP2024/084668
Authority: WO
Inventors: Martin BAUMGAERTL; Simone GUFFANTI; Gianluca Pauletto
Original assignee: Sypox GmbH
Current assignee: Sypox GmbH
Priority date: 2023-12-05
Filing date: 2024-12-04
Publication date: 2025-06-12
Anticipated expiration: 2026-06-05

Abstract

A reactor system to carry out an endothermic reaction of a reactive mixture stream to be converted to a product gas or product stream characterized in that comprising at least one electrically heated catalytic section (10) where the heat for said endothermic reaction is generated by electricity directly within the electrically heated catalytic section, and at least one adiabatic catalytic section (30), said adiabatic catalytic section positioned downstream of said electrically heated catalytic section (10), so that the outlet stream of the electrically heated catalytic section enters into the inlet stream of said adiabatic catalytic section, and at least one pressure vessel, said pressure vessel comprises at least one reactive stream duct, a stream inlet, a stream outlet, at least one catalytic section provided inside said reactive stream duct between said stream inlet and stream outlet; an insulation filling at least partly encompassing said reactive stream duct, and a catalyst bed accommodated in said catalyst section, where the reactive mixture stream undergoes a catalytic reaction.

Description

DESCRI PTION

ELECTRICALLY HEATED REACTOR SYSTEM FOR ENDOTHERM IC REACTIONS

Technical field

The present invention relates to a reactor system to carry out an endothermic chemical reaction comprising at least one electrically heated catalytic section, and a second adiabatic catalytic section downstream said first electrically heated catalytic section. The present invention also relates to a relevant method using the reactor system for carrying out an endothermic chemical reaction.

Background

Electrically heated chemical reactors offer the possibility to transfer a large amount of power within a confined space, resulting in very compact reactor systems for energy demanding reactions. Due to the small size, the amount of catalytically active material that can be provided within such a reactor is limited, making it more vulnerable to catalyst deactivation compared to traditional fired equipment. This is especially true due to the versatility and low capital costs (CAPEX) of electrically heated systems, which allows their application in environments dealing with catalyst poisons or challenging feedstock as for example biogas plant or at oil wells.

Additionally, electrically heated reactors are often capable of operating at higher temperatures compared to their fire-heated counterparts arising from electric heat generation directly within the pressure vessel. This higher operating temperature can lead to enhanced catalyst deactivation due to sintering of metal particles.

The slip of reactive mixture, meaning the fraction of unconverted gases at the reactor outlet, is a further challenge that electrically heated reactors are facing. In fired reactors, this slip is often fed and utilized for the burners that provide the necessary heat for the chemical reaction. As this heat is provided via electricity in electrically heated equipment, burning unreacted streams is no longer desirable. It is therefore crucial to minimize the slip of unconverted reactive mixture and operate at high conversion levels. As consequence, high operating temperatures are often desirable (Fig. 1).

A third aspect arises from the electrical power supply, which is needed to power the electrically heated reactor. Depending on which voltage and current the electrically heated reactor is operated, the power supply can play a huge factor in the overall CAPEX of the system. Especially the control strategy plays an important factor in the design of the power supply and determines the usable components.

As the power demand for the electrically heated reactor is coupled to the conversion of reactive mixture and therefore to the performance of the catalyst, catalyst deactivation will necessitate a reduction in power input to the reactor to avoid overheating. For a constant power input, a part of the power would be converted into heat (increase in temperature) without contributing to the endothermic reaction, and therefore reducing the efficiency of the process. Additionally, downstream equipment, such as heat exchangers and/or boilers, would need to be able to handle the increased outlet temperature coming from the electrically heated reactor leading to potential metallurgy and/or mechanical problems.

Disclosure of the invention

In view of the above-mentioned technical challenges, one objective of the present invention is to provide a reactor system to carry out an endothermic chemical reaction comprising at least one electrically heated catalytic section, where the heat for the endothermic reaction is provided by electricity, and a second adiabatic catalytic section downstream said first electrically heated catalytic section, without heating system.

It is a further objective to provide an electrically heated reactor system that minimizes slip of unconverted reactive mixture, meaning operation close to the thermodynamic equilibrium.

It is a further objective to provide an electrically heated reactor system that is more robust towards catalyst deactivation and therefore offers an increased lifetime, reliability, and safety.

It is a further objective to provide an electrically heated reactor system that offers a simplified control strategy with constant power input to the reactor system, even in the case of catalyst deactivation of the electrically heated catalytic section.

It is a further objective to provide an electrically heated reactor system that offers a constant conversion and outlet temperature, even in the case of catalyst deactivation in the electrically heated catalytic section.

In order to achieve the above-mentioned objects or those disclosed or to be deducted from the detailed description, the present invention relates to an electrically heated reactor system to carry out an endothermic chemical reaction that comprises:

I) at least one electrically heated catalytic section where the heat for the endothermic reaction is provided via electricity

II) at least one adiabatic catalytic section downstream said electrically heated catalytic section, so that the outlet stream of the electrically heated catalytic section is entering to the inlet of the adiabatic catalytic section.

It should be understood, that said electrically heated catalytic section and downstream adiabatic catalytic section can be a part of the same reactor housing, or housed by individual pressure vessels. At the same time the electrically heated catalytic section is not limited to a specific configuration, but can be any kind of solution that provides heat for the endothermic reaction via electricity within a catalytic bed. It is also possible that multiple electrically heated catalytic beds within one pressure shell or multiple pressure shells - in series or parallel - hosting at least one electrically heated catalytic bed are forming an electrically heated catalytic section. The same is also true for the adiabatic catalytic section, which can also consist of multiple individual reactors.

It is a further object of the present invention to provide a method for utilizing the described electrically heated reactor system to carry out an endothermic chemical reaction in which a reactive mixture stream is converted into a product stream within said reactor system.

The method comprises the following steps:

I) A reactive mixture stream enters through the reactor inlet of the electrically heated catalytic section. While the reactive mixture stream is passing through the electrically heated catalytic section, it is converted into a product stream 1. The product stream 1 is exiting the electrically heated catalytic section.

II) Under normal operation, the power input to the electrically heated catalytic section is only depending on the flowrate, chemical composition, and physical properties of the reactive mixture stream. The power input to the electrically heated catalytic section is independent of the composition and temperature of the product stream 1.

III) The product stream 1 subsequently enters the adiabatic catalytic section. Here, excess heat, which is coming from the electrically heated catalytic section, is utilized to further convert the reactive gas contained in the product stream 1 into product gas, so that the resulting product stream 2 composition reaches thermodynamic equilibrium. Subsequently, the product stream 2 exits the adiabatic catalytic section from the reactor outlet.

Brief description of the drawings

The present invention will be disclosed herein below for illustrative, but non limitative purposes, according to preferred embodiments, with reference in particular to the figures of the enclosed drawing, wherein:

Fig. 1 shows a methane conversion and temperature profiles of steam methane reforming as function of the power input, in particular methane conversion at thermodynamic equilibrium (orange = upper line) and reactor outlet temperature (blue = lower line) as function of the power input to the reactor. niet = 600°C, P = 30 bar, S/C =2.8.

Fig. 2 shows a layout of the system object of the present invention as arrangement of an electrically heated catalytic section and a downstream adiabatic catalytic section for converting a stream of a reactive mixture into a product stream.

Fig. 3 shows a layout of the system object of the present invention, in particular a schematic representation of an electrically heated reactor system comprising of one electrically heated reactor and one downstream positioned adiabatic reactor.

Fig. 4 shows a preferred layout of the system object of the present invention including an overheating protection, in particular a schematic representation of an electrically heated reactor system comprising of one electrically heated reactor and one downstream positioned adiabatic reactor including an overheating protection at the outlet of the electrically heated reactor.

Fig. 5A shows an example of methane conversion at the outlet of the electrically heated reactor (blue) and the adiabatic reactor (orange = horizontal line) in case of catalyst deactivation at constant power input to the electrically heated reactor.

Fig. 5B shows an example of temperature at the outlet of the electrically heated reactor (blue) and the adiabatic reactor (orange = horizontal line) in case of catalyst deactivation at constant power input to the electrically heated reactor.

Reference numbers given in the figure

10 electrically heated catalytic section

20 electrically heated reactor

21 inlet

22 outlet

23 electrically heated catalytic bed

24 overheating protection unit

25 power control unit

26 power supply unit

27 thermocouples

30 adiabatic catalytic section

40 adiabatic reactor

41 inlet

42 outlet

43 adiabatic catalytic bed Detailed description of the embodiments of the invention

Turning to the present invention in more detail, a reactor system to carry out an endothermic chemical reaction comprising at least one electrically heated catalytic section, where the heat for the endothermic reaction is provided by electricity, and a second adiabatic catalytic section downstream said first electrically heated catalytic section without heating system. The reactor system comprises, in particular consists of:

II) at least one adiabatic catalytic section downstream said electrically heated catalytic section so that the outlet stream of the electrically heated catalytic section is entering to the inlet of the adiabatic catalytic section.

Furthermore, a method for utilizing the described electric reactor system for converting a reactive mixture stream into a product stream is provided. The method comprises the following steps:

II) The product stream 1 subsequently enters the adiabatic catalytic section. Here, the excess heat coming from the electrically heated catalytic section, which lead only to an increase of the temperature, is utilized to further convert the reactive gas contained in the product stream 1 into product gas, so that the resulting product stream 2 composition reaches thermodynamic equilibrium. Subsequently, the product stream 2 exits the adiabatic catalytic section from the reactor outlet.

Electrically heated reactors have the potential of transferring a large amount of power within a limited spatial environment, thereby leading to highly compact reactor systems. However, due to their reduced dimensions, these reactors face constraints in accommodating catalytically active materials, leaving them more susceptible to catalyst deactivation compared to conventional fired equipment.

Placing an adiabatic catalytic section downstream an electrically heated catalytic section solves this problem by providing a reservoir of catalytically active material downstream the electrically heated catalytic bed. In the case of catalyst deactivation of the electrically heated catalytic section, the conversion of the reactive mixture is completed within the adiabatic catalytic section, while the necessary heat input to fuel the conversion is still fully provided by the electrically heated catalytic section.

Due to this mechanism, the performance of the reactor system in terms of conversion and slip of reactive mixture is less dependent on the catalyst activity of the electrically heated catalytic section. As excess heat coming from the electrically heated catalytic section is at the end also converted into products within the adiabatic catalytic section, the efficiency of the reactor system is improved compared to involving only an electrically heated catalytic section.

Additionally, any other system malfunction that increases the slip of reactive mixture coming from the electrically heated catalytic section is mitigated as it can be converted within the downstream adiabatic catalytic section. Minimizing the reactive mixture slip is especially important in electrically heated reactor systems, as unconverted reactive mixture cannot be utilized for heating the reactor system. This is the case for example for steam methane reformers with fired heating solutions.

As sufficient amount of catalytically active material is hosted in the reactor system, the product stream from the outlet of the adiabatic catalytic bed is always at thermodynamic equilibrium.

This means that the power input to the electrically heated catalytic section is controlling the conversion of reactive mixture at the outlet of the adiabatic catalytic section. An example of this is reported for the steam methane reforming process in Fig. 1.

As long as the power input to the electrically heated catalytic section can be kept constant for a given reactive stream and within the design parameters of the reactor system, the product stream composition at the outlet of the adiabatic catalytic section is constant.

This on one side increases reliability and lifetime of the reactor system itself and, at the same time also reduces the complexity of the power supply of the electrically heated catalytic section, as the reactor system is operated under constant electrical power input. It is therefore not needed to have a temperature controller with temperature measurement at the reactor outlet in the system, which is one of the main failure mechanisms for these systems.

At the same time, this also means, that the outlet temperature after the adiabatic catalytic bed is constant for a constant power input of the electrically heated catalytic bed. This reduces risks of temperatures above design condition reaching downstream equipment and therefore increases the safety.

It should be noted, that it is not possible to replace the electrically heated catalytic section with an electric gas heater and afterwards entering with the heated but unconverted reactive stream into the adiabatic catalytic section. Amongst various reasons, this is due to the energy demand of an endothermic reaction that needs to be satisfied by the thermal energy transferred from the electric heating to the catalytically active material. In an electrically heated catalytic section, the major part of the generated heat is directly consumed by the hosted catalytically active material while converting the reactive mixture stream following an endothermic reaction. It is therefore possible to have a much larger power input for the same amount of gas flowing through the bed compared to an electric gas heater, assuming the same outlet temperature. An electric gas heater instead can only transfer thermal energy to the reactive mixture which afterwards enter the adiabatic catalytic section. This is limited by the maximum operating temperature of the electric gas heater and the inlet temperature of the adiabatic catalytic section.

By combining electric heating with a catalytically active material (in situ) within the electrically heated catalytic section, the majority of the heat generated is immediately consumed by the catalytically active material which converts the reactive mixture stream into a product. Separating these two functions will result in a needed gas temperature at the outlet of the electric gas heater, that is technically and economically undesirable or simply not feasible.

For steam methane reforming and a desired outlet temperature from the adiabatic catalytic section of 950°C (equilibrium conversion), an outlet temperature from an electric gas heater (no conversion) of approximately 1850°C would be required to enter into the adiabatic catalytic section. This not only is very hard to realize from a temperature point of view, but also would lead to massive carbon formation at the inlet of the adiabatic catalytic section and presumably within the electric gas heater itself.

The disclosed reactor system operates at temperatures between 400°C and 1200°C outlet temperature after the adiabatic catalytic section, preferably between 800°C and 1000°C outlet temperature.

The reactor system can be used for any endothermic chemical reaction such as steam methane reforming, reverse water gas shift, ammonia cracking, Volatile Organic Compounds (VOCs) reduction and/or any other endothermic reaction not limited to the ones herein reported.

Fig. 3 shows a possible basic layout of the disclosed reactor system where the first reactor hosts an electrically heated catalytic section and the second reactor hosts an adiabatic catalytic section. A reactive mixture stream enters the electrically heated reactor at the gas inlet, and passes through at least one electrically heated catalytic bed. The electricity necessary to generate heat within the reactor is provided by a power supply connected to the electrically heated catalytic section. A product stream 1 is exiting the electrically heated reactor from the reactor outlet and enters into the adiabatic reactor inlet. The product stream 1 passes through the adiabatic catalytic section and residual unconverted reactive mixture is converted until the thermodynamic equilibrium is reached. The advantage of this system layout lies in the fact that a constant conversion is obtained by the system when a constant power is supplied to the electrically heated reactor. As demonstrated in the examples, the adiabatic reactor consumes the additional heat not exploited by the electrically heated reactor due to catalyst deactivation or other reactor malfunctioning.

Fig. 4 shows an alternative preferred layout in which a thermocouple (TT) is positioned at the outlet of the electrically heated reactor. The thermocouple and/or temperature sensor is connected to a power limiter to prevent the outlet temperature of the electrically heated catalytic bed to increase above design conditions. Within a reasonable reactor design, this temperature limiter is only used for severe catalyst malfunction. In a similar way, the thermocouple and/or temperature sensor is located within the electrically heated catalytic section.

An example is reported to show how the system is able to handle different malfunction scenarios. Steam methane reforming is considered as case process for the examples. The operating conditions are the same used for Fig. 1 ( niet = 600°C, P = 30 bar, S/C =2.8) and a constant input power of 3.5 kWh/Nm³cH4 to the electrically heated reactor is considered. These conditions lead to a thermodynamic equilibrium conversion of methane of 95 percent and an outlet temperature of approximately 980°C after the adiabatic bed.

Example: Catalyst deactivation in SMR:

A decreased activity of the catalyst within the electrically heated catalytic section is considered. The loss of activity is quantified as temperature approach for methane reforming at the outlet of the electrically heated reactor. The conversion at the outlet of the electrically heated catalytic section is plotted as function of the temperature approach in the interval between 0°C and 300°C.

Fig. 5A shows the methane conversion at the outlet of the electrically heated catalytic section and the downstream adiabatic catalytic section. The conversion at the outlet of the electrically heated catalytic section decreases with catalyst deactivation. A conversion of 77 percent is reached at 300°C temperature approach.

Due to the constant power input to the electrically heated catalytic section, the outlet temperature of the electrically heated catalytic section is increasing with decreasing conversion, as less energy is consumed by the reaction. Nevertheless, the conversion and outlet temperature from the downstream connected adiabatic catalytic section remains constant (cf. Fig. 5B).

The present invention was disclosed for illustrative, non-imitating purposes, according to a preferred embodiment thereof, but it has to be understood that any variations and/or modification can be made by the persons skilled in the art without for this reason escaping from the relative scope of protection, as defined in the enclosed claims.

Claims

1 . A reactor system to carry out an endothermic reaction of a reactive mixture stream to be converted to a product gas or product stream characterized in that comprising at least one electrically heated catalytic section (10) where the heat for said endothermic reaction is generated by electricity directly within the electrically heated catalytic section, and at least one adiabatic catalytic section (30), said adiabatic catalytic section positioned downstream of said electrically heated catalytic section (10), so that the outlet stream of the electrically heated catalytic section enters into the inlet stream of said adiabatic catalytic section, and at least one pressure vessel, said pressure vessel comprises at least one reactive stream duct, a stream inlet, a stream outlet, at least one catalytic section provided inside said reactive stream duct between said stream inlet and stream outlet; an insulation filling at least partly encompassing said reactive stream duct, and a catalyst bed accommodated in said catalyst section, where the reactive mixture stream undergoes a catalytic reaction.

2. The reactor system according to claim 1 , wherein the electrically heated catalytic section and the adiabatic catalytic section are hosted within two individual pressure vessels.

3. The reactor system according to claim 1 , wherein the electrically heated catalytic section if formed by multiple electrically heated catalytic beds positioned in series.

4. The reactor system according to at least one of claim 1 to 3, wherein the electric power input to the electrically heated catalytic section is not controlled by a temperature controller.

5. The reactor system according to at least one of claim 1 to 4, wherein the electric power input to the electrically heated catalytic section is determined from calculating the power demand to reach thermodynamic equilibrium for a given inlet composition.

6. The reactor system according to at least one of claim 1 to 5, wherein the adiabatic catalytic section provides enough catalytically active material to reach thermodynamic equilibrium of the product gas mixture at the outlet of the adiabatic catalytic section.

7. The reactor system according to at least one of claims 1 to 6 wherein at least one overheating protection unit (24), in particular at least one overheating temperature switch, is assigned to said electrically heated catalytic section (10), in particular to the outlet (22) of said electrically heated catalytic section (24).

8. The reactor system according to at least one of claims 1 to 7 wherein at least one power supply unit (26) and one power control unit (25) is assigned to said electrically heated reactor (20).

9. The reactor system according to claim 8 wherein at least one power set point is assigned to said power control unit (25).

10. The reactor system according to at least one of claims 1 to 9 wherein said thermocouples (27) are connected to said overheating protection unit (24), said thermocouples (27) limiting the electric power input of said power supply to the electrically heated catalytic section (10) in case a maximum threshold temperature is reached.

11 . The reactor system according to at least one of claims 1 to 10 wherein the outlet temperature from said adiabatic catalytic section (30) is between 400°C and 1300°C.

12. A method for carrying out an endothermic reaction, said method comprising the following steps: a reactive mixture stream entering through the inlet (21) of the electrically heated catalytic section (10) where the heat for said endothermic reaction is provided by electricity, and where said reactive mixture stream passes through an electrically heated catalytic section (10) to be converted to a product gas or product stream; subsequently said product gas or product stream entering through the inlet (41) of the adiabatic catalytic section (30) where said product gas or product stream passes through an adiabatic catalytic bed of said adiabatic catalytic section (30), with excess heat from said electrically heated catalytic section (10) being utilized to further convert residual unconverted reactive mixture until thermodynamic equilibrium is reached.

13. Use of the reactor system according to at least one of claims 1 to 11 and/or of at least one method according to claim 12 for carrying out an endothermic gas phase reaction.

14. Use of the reactor system according to at least one of claims 1 to 11 and/or of a method according to claim 12 for an endothermic reaction selected from the group consisting of steam methane reforming (SMR), naphtha cracking, hydrocarbon cracking, ammonia cracking, reverse water gas shift (rWGS), volatile organic compounds (VOCs) reduction, and dehydrogenation.