AT523920A4 - Gas generating device for converting electrical energy into storable usable gas - Google Patents

Abstract

The present invention relates to a gas generating device (10) for converting electrical energy into storable useful gas (NG), having a fuel cell system (100) with at least one fuel cell stack (110) for converting feed gas (ZG) into useful gas (NG) and at least one electrical Heating device (200) for generating supply heat for direct and/or indirect supply to the fuel cell system (100) for heating the fuel cell system (100), further comprising a distribution device (20) with an input connection (22) for electrical connection to at least one power generator ( 300) and a fuel cell connection (24) for the electrical connection to the fuel cell system (100) and at least one heating connection (26) for the electrical connection to the at least one electrical heating device (200), the distribution device (20) having a control module ( 21) for a controlled distribution of the electrical energy ie from the input connection (22) to the fuel cell connection (24) and the at least one heating connection (26).

Description

storable useful gas

The present invention relates to a gas generating device for converting electrical energy into storable usable gas and a method for distributing fluctuating electrical energy in a gas generating system according to the invention.

contraption.

It is known that gas generating devices are to be used in order to convert electrical energy into a usable gas that can be stored. Conversely, this useful gas can be converted back into electrical energy. This is becoming more important, especially as it is becoming more and more important to decarbonize energy systems. Regenerative energy producers have in common that the energy is often generated with strongly fluctuating generation capacities. This can be clearly seen using the example of a wind turbine. At high wind speeds, this means that a correspondingly large amount of electrical energy is produced with a high generation capacity. If the wind speed drops, the generation capacity and the correspondingly produced electrical energy are also reduced. When connecting to networks for distributing the electrical power, this means that protection must be provided accordingly for network stability. In addition, the electrical energy generated often does not match the current consumption situation, so that caching the

generated electrical energy is desired.

Known solutions allow the electrically generated energy to be temporarily stored, for example in battery devices. However, since these must have correspondingly large storage capacities and a correspondingly high design and financial effort must be made, it is also known to use so-called power-to-gas processes, i.e. to produce storable useful gas from the electrical energy generated, which can later be used again in electrical energy can be converted back. One possibility of such well-known power-to-gas processes is the use of fuel cell systems, which, through the application of the electrolysis principle, convert the generated electrical energy into storable useful gas, in particular in the form of hydrogen-containing gas, and this gas in reverse operation according to the fuel cell principle

convert electrical energy.

To control or regulate useful gas.

In known solutions, this means that a strongly fluctuating current generated in the form of generating capacity can actually only be partially converted into usable gas due to the sluggish operation of the fuel cell. If, for example, the generation capacity rises sharply due to a gust of wind, only a small part of this sharp increase in the electricity generated can be converted into useful gas in the fuel cell, since the fuel cell only reacts very sluggishly and accordingly does not correspond to the rapid increase in generation capacity rapid increase in operating power of the fuel cell system. In the same way, the fuel cell can only follow this drop to a certain extent if there is a sharp drop in the generation output, so that the fuel cell system can also be operated with reduced efficiency

consequence is.

It is the object of the present invention to achieve the above-described

parts to fix at least partially. In particular, it is the task of the present

Invention, in a cost-effective and simple manner, the efficiency in manufacturing

of useful gas to improve.

The above object is achieved by a gas generating device having the features of claim 1 and a method having the features of claim 9. Further features and details of the invention result from the dependent claims, the description and the drawings. Features and details that are described in connection with the gas generating device according to the invention also apply, of course, in connection with the method according to the invention and vice versa, so that reference is always made to each other with regard to the disclosure of the individual aspects of the invention.

can be drawn.

According to the invention, a gas generating device is used to convert electrical energy into usable gas that can be stored. For this purpose, the gas generating device has a fuel cell system with at least one fuel cell stack for converting feed gas into useful gas. Furthermore, at least one electrical heating device is provided for generating electrical supply heat for direct and/or indirect supply to the fuel cell system for heating up the fuel cell system. Furthermore, the gas generating device has a distribution device with an input connection for the electrical connection to at least one power generator. The distribution device is also equipped with a fuel cell connection for the electrical connection to the fuel cell system and at least one heating connection for the electrical connection to the at least one electrical heating device. In addition, the distribution device has a control module for a controlled distribution of the electrical energy from the input connection to the fuel cell connection

and the at least one heating connection.

According to the invention, a coupling option is made available in order to convert electrical power generated by power generators into a usable gas for intermediate storage. This gas generating device system is based on the principle of electrolysis and uses a fuel cell system for this purpose. This burning

fuel cell system has at least one fuel cell stack, which

a range of about 500 degrees Celsius to about 1000 degrees Celsius.

In steady-state operation, electric power is generated as generating power via a power generator, which is, for example, a regenerative power generator, in particular in the form of a wind turbine and/or a photovoltaic system. This electric current is supplied via the input connection of the distribution device of the gas generating device according to the invention. There you can now decide how the generation capacity behaves in relation to the current operating situation of the fuel cell system. In the simplest case, the generation capacity essentially corresponds to the current operating situation, so that the generation capacity generated is supplied to the fuel cell stack via the fuel cell connection and is made available there completely or essentially completely for the conversion of the feed gas into the useful gas. If, for example, there is a significant increase, for example due to a strong gust of wind on a wind turbine, the generation power at the input connection of the distribution device also increases accordingly. Due to the already explained inertia of the fuel cell system, this rapid increase cannot be followed by a correspondingly rapid increase in the operating power of the fuel cell system. In other words, an overproduction of electrical energy is available which, in the known solutions, could not be made available for conversion into usable gas, but rather was limited

would.

However, in the configuration of the gas generating device according to the invention, the distribution device is equipped with at least one heating connection. It is possible via this heating connection in a case such as that described above

has been clarified not to regulate the excess generation capacity, but

rather to supply at least one electric heater. This one electric

ric heating device now generates on the basis of this excess electrical energy

heat energy, which is directly or indirectly fed to the fuel cell

system is supplied.

As has already been explained, the operating situation and thus also the operating point of the fuel cell system depends, among other things, on the temperature of the fuel cell stack or of the individual fuel cells. The higher the temperature, the greater the possibility of conversion and thus the efficiency in the production of useful gas. This means that, in the form of a power-to-heat solution, excess energy cannot be regulated off as with the known solutions in the event of a rapid increase in generation capacity, but rather converted into heat, which in turn is fed directly to the fuel cell stack via contact (e.g. via heat exchanger) or Fluids or can be supplied indirectly via other systems. Increasing the temperature raises the operating point, making it easier to increase the operating power of the fuel cell system faster than would be the case without this separate heating option. In other words, it is now possible to supplement the existing power-to-gas functionality of the fuel cell system with the help of an additional power-to-heat functionality and thus to optimize the possibility of converting electrical power even with excess generation capacity.

to maximize.

There can be advantages if, in a gas generating device according to the invention, the at least one electrical heating device is designed as a steam generator for generating water vapor as the feed gas for the fuel cell stack. In the simplest case, such a steam generator is an electric steam generator which, for example in the form of a resistance heater, heats liquid water to over 100 degrees Celsius and in this way causes it to evaporate. The steam can be used directly or indirectly as feed gas for conversion into useful gas. A mixture with other feed gas components is also conceivable within the meaning of the present invention. Due to the fact that water vapor is necessary as the supply gas for the conversion into hydrogen as useful gas even in normal operating situations, it can bring advantages if this steam generator is used in normal operation, i.e. without excess generation capacity, with

NEM separate power, for example from a power grid, is operated. Over-

management system via the medium of steam generation.

It is also advantageous if, in a gas generating device according to the invention, the steam generator has a steam reservoir for intermediate storage of generated water vapor. The amount of steam made available by the steam generator also depends on the current operating point of the fuel cell system. However, it is possible that the excess generation capacity is so large that it only partially correlates with the currently required amount of water vapor, which matches the current operating point of the fuel cell system. In order to ensure that as large a proportion of the excess generation capacity as possible, in particular the entire surplus, can also be stored or used, a steam accumulator can also enable disproportionate steam generation, so that if the surplus generation capacity is removed later, the steam already generated at an earlier point in time can be used Operation of the fuel cell system is available. In other words, the steam accumulator forms an intermediate heat accumulator, which can absorb short-term peaks in excess of the generation capacity and release it again later. In particular, this means that a high water vapor flow can still be generated when the generation output falls sharply, in particular below the current operating output of the fuel cell system, since this is now made available from the previously filled vapor accumulator. This steam accumulator may, for example, have one or more outlet valve devices and/or one or more fresh water supplies to feed the heating device. The steam accumulator itself is preferably carried out in two phases, so that there is always a certain proportion of

Water vapor phase and some liquid water phase are present.

In addition, it is advantageous if the at least one electric heating device is designed as a heat accumulator with a thermal fluid in a gas generating device according to the invention. Such a thermal fluid has in particular

a melting point and/or a boiling point greater than about 100 degrees Celsius

71728

There are also advantages if, in a gas generating device according to the invention, the at least one electric heating device is designed as a component heater for direct heating of at least one component of the fuel cell system. This is in particular a resistance heater which transfers the heat to the fuel cell system via heat transport, in particular via heat conduction, for example by contacting the corresponding component of the fuel cell system. This is a particularly simple way of providing a direct heating option for the fuel cell system using the electric heating device

put.

It is also advantageous if, in a gas generation process according to the invention

direction the at least one electric heater is designed as a fluid heater for heating a guided fluid in the fuel cell system. This means that fluids, for example the feed gas or coolant or temperature control medium, can be heated in a temperature control device of the fuel cell system with the heating device and by the flow of the fluid in and/or through

the fuel cell system individual areas of the fuel cell system with the

transferred heat can be heated.

It is also advantageous if, in a gas generating device according to the invention, the distribution device has a battery output to which an electrical battery unit for storing electrical energy is connected, with the control module also distributing the electrical energy to the battery output. This is also the possibility in addition to the power-to-heat functionality according to the core idea of the present invention

store electrical energy in a battery. It can be about

father.

Further advantages can result if the distribution device in a gas generating device according to the invention has a network connection for an electrical connection to a power distribution network, with the control module also distributing the electrical energy to the network connection. A power distribution network can be the public power grid, so that power generators supply the public power grid with a base current via the network connection. The fuel cell system can be operated in addition to the basic current and in this way the useful gas production can also take place parallel to the supply of the public electricity grid. As an alternative to this, it is also possible that the distribution device is designed without such a network connection and is therefore designed for isolated operation. In such a case, the gas generating device is used exclusively or essentially exclusively for the production of useful gas. Especially for off-shore systems

this can bring great benefits.

It is also advantageous if the gas generating device is designed to be operated in a reversible manner. The gas generating device is thus designed in such a way that it generates a specific gas, in particular hydrogen, in one operating mode and, on the other hand, consumes this gas again in accordance with energy conversion in a further operating mode. In particular, the gas is converted back into electrical energy by the gas generating device according to the invention. This then corresponds to fuel cell operation. The electrical energy can then be assigned to a power grid or a stationary reactor, for example.

be led.

to increase le of the gas generating device.

Also subject matter of the present invention is a method for distributing fluctuating electrical energy in a gas generating system according to the invention.

device, comprising the following steps:

- Determining the generation capacity of electrical energy from at least one power generator at the input terminal,

- Determining a current operating performance of a current operating

point of the fuel cell system, - comparing the generation output with the current operating output,

- Distribute the generation power to the heating port and the fuel cell port based on the result of the comparison.

The distribution step can be carried out both quantitatively and qualitatively. Quantitative distribution is to be understood as meaning that a percentage is distributed to the fuel cell system and a further percentage to the at least one heating connection. Qualitative switching can be understood to mean that either the heating connection or the fuel cell connection is supplied with the corresponding generation power. By using a gas generating device according to the invention, a method according to the invention brings with it the same advantages as have been explained in detail with reference to a gas generating device according to the invention. The division can take place on the basis of an algorithm, in particular with feedback on the efficiency results achieved. The use of artificial intelligence in the form of neural networks is also conceivable here when considering the distribution in the form of a distribution strategy within the meaning of the present invention.

It entails further advantages if, in a method according to the invention

at least one of the following parameters when distributing the generation power

is taken into account:

- Maximum operating power of the fuel cell system,

- Minimum operating power of the fuel cell system,

- Maximum production amount of useful gas,

- Efficiency of the operating point of the fuel cell system.

The above list is a non-exhaustive list. It is of course also possible for two or more of these parameters to be taken into account in the distribution. Taking maximum and minimum operating power into account allows the fuel cell system to be protected from damage due to operating power that is too high or too low. Also, it becomes possible to increase the efficiency of the fuel cell system and/or the efficiency of production output. Of course, this distribution strategy can also be based on other goals. A possible core idea of the distribution strategy is to achieve the greatest possible conversion of the generation capacity into stored energy in the form of useful gas produced.

There are also advantages if, in a method according to the invention, the generation power is distributed in such a way that the operating power of the fuel cell system remains constant and/or the change in the operating power does not exceed a maximum change gradient. This means that in the operation of the fuel cell system, this takes into account the inertia in the control option. In particular, an attempt is made to keep the operation of the fuel cell system as constant as possible. It is also possible to take into account change gradients, in particular different for the increase and decrease in the operating power, in order to avoid damage to the system and at the same time to optimize the yield of useful gas produced.

It is also advantageous if, in a method according to the invention, the temperature of the fuel cell system is also taken into account when distributing the generation power. This means that the correlation between the temperature and the operating point or

way of the cell voltage in the fuel cell system when distributing the generation

performance is taken into account. This allows the method of the invention

should be designed with even greater efficiency in terms of the production of the

carry out useful gas.

It can also bring advantages if, in a method according to the invention, part of the generation capacity is additionally distributed to a compression device and/or a storage device for compressing and/or storing the useful gas when distributing the generation capacity. Depending on the current production situation, excess generation capacity can therefore be used not to make the useful gas available to a subsequent useful gas consumer, but to compress the useful gas in a useful gas storage facility via a mechanical compressor. Ideally, the resulting waste heat as an electrical heater in the manner of the invention

Fuel cell system are supplied.

It is also advantageous if, in a method according to the invention, the generation power is distributed over at least two, in particular different, electrical heating devices. In this case, for example, a direct and an indirect heating device can be combined with one another. The use of two or more electrical heaters and the appropriate distribution among them also leads to complex heating and storage strategies in the use and conversion of excess generation power. This leads to an increased degree of flexibility, especially in the case of energy sinks in the generation capacity,

which can be compensated by stored heat.

It is also advantageous if, in a method according to the invention, when using a heating device with a steam accumulator and/or when using an electric battery unit, the fill level of the steam accumulator and/or the electric battery unit is taken into account when distributing the generation power. It can thus be ensured that when the battery unit is full, it is no longer supplied with electrical energy. It can also be taken into account that a minimum amount always remains in the battery unit and/or in the steam accumulator in order to achieve a desired buffer time or buffer on the basis of empirical values.

to provide capacity for the operation of the fuel cell system.

In addition, it is advantageous that in the event of a shortage of electrical energy

the gas generating device and/or the fuel cell system, if reversible

executed, it is switched over to the operating mode in which useful gas is returned

is converted into electricity, i.e. electrical energy is generated and z. B. the power grid or other

ren consumers is supplied.

Further advantages, features and details of the invention result from the following description, in which exemplary embodiments of the invention are described in detail with reference to the drawings. It show schematic

table:

1 shows an embodiment of a gas generating device according to the invention,

2 shows a further embodiment of a gas generating device according to the invention,

3 shows a further embodiment of a gas generating device according to the invention,

4 shows a further embodiment of a gas generating device according to the invention,

5 shows a further embodiment of a gas generating device according to the invention,

6 shows a possible course of a generation output,

FIG. 7 shows the curve of FIG. 6 in comparison to an operating performance,

8 shows a possibility of distributing the generating capacity,

9 shows the embodiment of FIG. 8 with modified operating performance.

1 to 5 show schematic examples of gas generating devices 10. In the embodiment of FIG. 1, as in the other figures, power generators 300 are shown here as regenerative power generators 300, for example in the form of a wind turbine and in the form of a photovoltaic system. about one

Input port 22 can use the fluctuating electrical energy as a generation

NG to generate.

In the event that excessive generation power EL is present at input connection 22 , control module 22 can now route this excess generation power EL past fuel cell system 100 and distribute it to one heating connection 26 . This excess now makes it possible to supply electrical energy to electrical heating device 200 in the form of a component heater 230 in FIG. According to FIG. 1, this electrical energy is used in the component heater 32 to heat individual components through direct contact or through heating of flowing fluid, in particular temperature control fluid, on the fuel cell stack 110. The functionality of the warming will

later explained in more detail.

Figure 2 is based on the embodiment of Figure 1. However, a steam generator 210 is shown here as an electrical heating device 200, which is able to at least partially evaporate liquid water from a fresh water connection, not shown, and in this way to produce supply gas ZG containing water vapor. In the event that there is no surplus of generating capacity EL of the electricity generator 300, this steam generator 210 can also be supplied with electricity for steam generation by a network connection, which is not shown in detail. In the manner already described, the electrical generation power EL is divided via the control module 21 of the distribution device 20.

Figure 3 shows a development of the embodiments of Figures 1 and 2. The

Steam generator 210 is additionally equipped with a steam accumulator 212 here,

which serves as an intermediate buffer for the generated steam. Thus, even with ge-

lower required amount of steam in the fuel cell system 100 a large surplus

shot of generating capacity EL converted into steam via the steam generator 210

be, since this is temporarily stored in the steam memory 212 and later

can be fed back to the fuel cell stack 110 as feed gas ZG.

FIG. 3 also shows a possibility of how a compressor 40 can store produced useful gas NG in a storage device 50 in compressed form. The power required for the compression can also have the control module 21 and a here

Compressor connection 27 to the compressor 40 are supplied.

FIG. 4 shows that, in comparison to the isolated solutions in FIGS. 1, 2, 3 and 5, a connection to a power distribution network 400 via a network connection 29 is also possible. In addition, in the embodiment of FIG. 4, the electrical heating device 200 is designed as a heat accumulator 220 with a thermal fluid, which thermal fluid is then made available again for steam generation or for other temperature control of the fuel cell stack 110.

can be provided.

FIG. 5 also shows the embodiment of FIG. 1 with an additional battery unit 30 which is electrically connected to the distribution device 20 via a battery output 28 controlled by the control module 21 . The coupling of the battery unit 30 is bidirectional, so here a temporary outsourcing

Excess generation capacity EL is possible.

Figures 6 to 9 show schematically how a method according to the invention works with a gas generating device 10 according to the invention.

ment conditions of the power generator 300 is based.

FIG. 7 shows the inertia of the operating power BL of a fuel cell system 100. The operating power BL can only slowly follow the strong increase in the generation power EL. The generation power EL then falls sharply, with the operating power BL being able to allow a faster fall of an increase and in this way following the falling generation power EL. At the following

rapid increase in generation capacity EL, in turn, only a small degree can

ent run in the increase for the operating power BL, so the area

between the generation capacity EL and the operating capacity BL in the case of the known ones

solutions is to be regarded as lost energy.

FIG. 8 now shows that the excess between the operating power BL and the generation power EL is distributed to the heating connection 26. In other words, the excess energy of the generation capacity EL to be regulated in the known solutions is used here essentially completely to supply an electrical heating device 200 with this electrical energy and in this way heat the fuel cell system 100 from the electrical energy

to supply

FIG. 9 now shows that the gradients in the increase in the operating power BL can be increased with the heat supplied. While the old operating capacity BL is drawn in as a dashed line, the operating capacity BL can now increase more sharply over the same period of time due to the supply of additional heat energy and, according to the comparisons in FIGS NG to be implemented. So it remains to summarize that a method according to the invention not only avoids the destruction or curtailment of excess generation power EL, but also the production quantity of useful

gas NG increases.

The above explanation of the embodiments describes the present invention exclusively in the context of examples. Individual features of the embodiments can, of course, be combined freely with one another, insofar as this makes technical sense

be combined without departing from the scope of the present invention.

Reference List

10 gas generating device 20 distribution device

21 control module

22 input port

24 fuel cell connection 26 heating connection

27 compressor connection

28 battery output

29 network connection

30 electric battery unit 40 compression device 50 storage device

100 fuel cell system 110 fuel cell stack

200 electric heater 210 steam generator

212 Steam Storage

220 heat accumulator

230 component heater

300 power generators

400 power distribution network

NG useful gas

ZG feed gas

EL generating power

BL Operating Power

Claims (1)

patent claims 1. Gas generating device (10) for converting electrical energy into storable useful gas (NG), having a fuel cell system (100) with at least one fuel cell stack (110) for converting feed gas (ZG) into useful gas (NG) and at least one electrical heating device (200 ) for generating supply heat for direct and/or indirect supply to the fuel cell system (100) for heating the fuel cell system (100), further comprising a distribution device (20) with an input connection (22) for electrical connection to at least one power generator (300) and a fuel cell connection (24) for the electrical connection to the fuel cell system (100) and at least one heating connection (26) for the electrical connection to the at least one electrical heating device (200), the distribution device (20) having a control module (21) for a controlled splitting of the electrical energy from the input terminal (22) to the fuel cell connection (24) and the at least at least one heating connection (26). 2. Gas generating device (10) according to claim 1, characterized in that the at least one electrical heating device (200) is designed as a steam generator (210) for generating steam as the feed gas (ZG) to the fuel cell stack (110). 3. Gas generating device (10) according to claim 2, characterized in that the steam generator (210) has a steam accumulator (212) for a Temporary storage of generated water vapor. 4. Gas generating device (10) according to any one of the preceding claims, characterized in that the at least one electrical heating device device (200) is designed as a heat accumulator (220) with a thermal fluid. 5. Gas generating device (10) according to any one of the preceding claims, characterized in that the at least one electric heater (200) as a component heater (230) for direct heating at least a component of the fuel cell system (100) is formed. system (100) guided fluid is formed. 7. Gas generating device (10) according to one of the preceding claims, characterized in that the distribution device (20) has a battery outlet (28) to which an electrical battery unit (30) for storing electrical energy is electrically connected, the control module (21 ) additionally the electrical energy also on the battery Output (28) splits. 8. Gas generating device (10) according to any one of the preceding claims, characterized in that the distribution device (20) has a network connection (29) for an electrical connection to a power distribution network (400), wherein the control module (20) additionally the electrical cal energy also on the network connection (29). 9 gas generating device (10) according to any one of the preceding claims, characterized in that the gas generating device (10) reversible bel is designed to be operated. 10. A method for distributing fluctuating electrical energy in a gas generating device (10) having the features of any one of claims 1 to 9, comprising the following steps: - Determining the generation capacity (EL) of electrical energy from at least one power generator (300) at the input terminal (22), — Determining a current operational performance (BL) of a current determination operating point of the fuel cell system (100), — Comparing the generated power (EL) with the current operating power (BL), 11. The method according to claim 10, characterized in that when distributing the generating capacity (EL) at least one of the following parameters the following is taken into account: — Maximum operating power of the fuel cell system (100) — Minimum operating power of the fuel cell system (100) — Maximum production quantity of useful gas (NG) — Efficiency of the operating point of the fuel cell system (100) 12. The method according to any one of claims 10 or 11, characterized in that the generation power (EL) is distributed so that the operating power (BL) of the fuel cell system (100) remains constant and / or the change in operating power (BL) a maximum change gradient no over- strides. 13. The method according to any one of claims 10 to 12, characterized in that in the distribution of the generating capacity (EL) the temperature structure of the fuel cell system (100) is taken into account. 14. The method according to any one of claims 10 to 13, characterized in that in the distribution of the generating capacity (EL) in addition a part of the generating capacity (EL) to a compression device (40) and / or a storage device (50) for compression and / or Saving the useful gas (NG) is distributed. 15. The method according to any one of claims 10 to 14, characterized in that the distribution of the generating capacity (EL) to at least two, in particular Special different electric heaters (200) takes place. 16. The method according to any one of claims 10 to 15, characterized in that when using a heating device (200) with a Dampfspei- cher (212) and/or when using an electric battery unit (30) the fill level of the steam accumulator (212) and/or the electric battery unit unit (30) is taken into account when distributing the generation capacity (EL).