EP4105551A1 - Method for supply of electrical energy - Google Patents

Abstract

Method for generating electrical energy, comprising the following steps: a) supplying hydrogen (1), oxygen (2) and liquid water (4) to a combustion chamber (3), b) oxidizing the hydrogen (1) with the oxygen (2 ) in the combustion chamber (3) with the formation of water vapor (5); c) expansion of the water vapor (5) via a steam turbine (6) which drives an electric generator (7).

Description

The present invention relates to a method for generating electrical energy in which hydrogen is oxidized with oxygen in a combustion chamber while liquid water is supplied for cooling and the resulting water vapor is expanded via a steam turbine, thereby driving an electrical generator.

A method for generating electrical energy is assumed to be known, in which natural gas enriched with hydrogen and compressed is fed to a combustion chamber into which compressed air is also fed. In the combustion chamber, the hydrogen is oxidized with the oxygen in the air. The resulting exhaust gas is expanded in a gas turbine to generate electrical energy. Furthermore, corresponding systems are assumed to be known, in which pure hydrogen is converted and the resulting exhaust gas is then fed to a gas turbine to generate electrical energy. The disadvantage of the methods assumed to be known is the limited efficiency.

Proceeding from this, the object of the present invention is to at least partially overcome the disadvantages known from the prior art.

This object is achieved by a method having the features of the independent claim. The dependent claims are directed to advantageous developments.

1. a) Zuführen von Wasserstoff, Sauerstoff und flüssigem Wasser in eine Brennkammer,
2. b) Oxidation des Wasserstoffs mit dem Sauerstoff in der Brennkammer unter Bildung eines Wasserdampfes;
3. c) Entspannen des Wasserdampfes über eine Dampfturbine, die einen elektrischen Generator antreibt.

The method according to the invention for generating electrical energy comprises the following steps:

1. a) feeding hydrogen, oxygen and liquid water into a combustion chamber,
2. b) oxidation of the hydrogen with the oxygen in the combustion chamber to form water vapor;
3. c) Expansion of the water vapor via a steam turbine that drives an electrical generator.

Hydrogen and oxygen are each supplied to the combustion chamber in gaseous form in a pure state, in particular each with a purity of preferably more than 99% by volume. The hydrogen and oxygen are each supplied in compressed form, in particular at pressures of from 30 to 200 bar, particularly preferably from 30 to 40 bar. A stoichiometrically balanced ratio of hydrogen and oxygen is preferably supplied, ie in particular a molar ratio of hydrogen to oxygen of 1.9:1 to 2.1:1.

The liquid water is preferably fed into the combustion chamber in the form of drops, in particular via one or more nozzles, in particular one or more atomizing nozzles, in order to achieve the largest possible surface area of the liquid water. The liquid water cools the gases in the combustion chamber on the one hand by heating it up, but also to a large extent on the other hand by the enthalpy of vaporization released during the evaporation of the liquid water, which makes a major contribution to cooling the gases. This allows the temperature in the combustion chamber to be significantly reduced. If temperatures of 2,000° C. [degrees Celsius] and more are present in the combustion chamber without cooling by liquid water, the supply of liquid water lowers the temperature to 1,500° C. and less, preferably 1,300° C. and less. The supplied water is supplied as demineralized water. Demineralized water usually has an electrical conductivity of less than 0.2 µS/cm [microsiemens per centimeter].

The supply of liquid water as coolant produces water vapor as exhaust gas, which is discharged from the combustion chamber. This is then expanded via the steam turbine. For further cooling, the steam turbine can contain nozzles for the supply of water in the blades of the turbine. A gas turbine that expands only to atmospheric pressure is therefore no longer necessary; instead, a steam turbine, in particular a condensation turbine, can be used that allows expansion down to significantly lower pressures. This enables an increase in efficiency compared to using a gas turbine. It is therefore also possible that the water vapor leaving the steam turbine has a share of liquid water. The steam turbine preferably has several stages (eg high-pressure stage and low-pressure stage).

According to an advantageous embodiment, the oxygen is supplied to the combustion chamber via a compressor, possibly a pressure accumulator. This enables a further increase in efficiency through the use of pure oxygen instead of air, which requires the compression of a significantly smaller mass flow. In addition, the formation of by-products, which could occur due to the high temperatures in the combustion chamber, can be avoided. Alternatively or additionally, the hydrogen is fed to the combustion chamber via a second compressor, possibly a pressure accumulator. This improves the options for carrying out the process, since the pressure in the combustion chamber is variable. In particular, a pressure of the hydrogen can then be achieved before it is fed to the combustion chamber, which allows optimal inflow into the combustion chamber. This increases the flexibility of the process control.

According to an advantageous embodiment, the water vapor, after flowing through the steam turbine, is supplied to a heat exchanger for dissipating heat to a heat transfer medium. As a result, the heat content of the steam can be used downstream of the steam turbine in an advantageous manner for heating a heat transfer medium, for example water, which is used as process water or process steam in other processes. This further increases the overall efficiency. Alternatively or additionally, this can also be achieved in that the steam, after flowing through the steam turbine, is fed to an intermediate stage of the steam turbine for cooling.

According to an advantageous embodiment, the steam, after flowing through the steam turbine, is fed to a condenser and is completely condensed there to form liquid water. As a result, the resulting condensate can advantageously be reused, for example for feeding into the combustion chamber as a cooling medium or also as a reactant in a water electrolysis. In this case, the condensed water is preferably fed to a reservoir via a first pump. Through this the water can be taken from the storage tank with an additional pump if required.

The liquid water for supply to the combustion chamber is preferably taken from the reservoir. This allows the liquid water to circulate, which advantageously avoids the supply of further water.

Alternatively or additionally, the water from the reservoir is preferably subjected to water electrolysis. In water electrolysis, water is split into hydrogen and oxygen using electrical energy.

At least one of the following gases is preferably generated by water electrolysis before being fed to the combustion chamber; in particular, water from the reservoir is used. This enables a further cycle in which the gases hydrogen and/or oxygen are generated from the water before being fed into the combustion chamber, which water has been formed by condensation from the water vapor which is removed from the combustion chamber.

According to an advantageous embodiment, at least one of the following gases produced in the water electrolysis: hydrogen and oxygen is stored in an intermediate store and removed from this for supply to the combustion chamber.

This enables a method for alternately storing and delivering electrical energy, in which, in the event of an energy requirement, electrical energy is generated as described above and, in the event of an energy oversupply, electrical energy is used to operate a water electrolyzer, with the hydrogen and oxygen produced therein being used later Supply to the combustion chamber are saved.

In particular, this enables alternating storage and delivery of electrical energy if it is provided irregularly, in particular if significant electrical energy from renewable sources, in particular from photovoltaics or wind energy, is fed into an electrical energy network, which depend heavily on the weather conditions. The necessary measures for frequency stabilization of the electrical energy network can be as described above be performed. In particular, converting the hydrogen into electricity via the steam turbine allows a large amount of electrical power to be provided quickly. Furthermore, the rotating masses of the steam turbine have an additional stabilizing effect on the grid frequency.

As a precaution, it should be noted that the numerals used here ("first", "second", ...) primarily (only) serve to distinguish between several similar objects, sizes or processes, i.e. in particular no dependency and/or sequence of these objects, sizes or make processes mandatory for each other. Should a dependency and/or order be necessary, this is explicitly stated here or it is obvious to the person skilled in the art when studying the specifically described embodiment.

Fig. 1

ein Fließbild eines ersten Beispiels eine Verfahrens zur Erzeugung von Energie; und

Fig. 2

ein Fließbild eines zweiten Beispiels eine Verfahrens zur Erzeugung von Energie.

The invention and the technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention should not be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description and/or figures. In particular, it should be pointed out that the figures and in particular the proportions shown are only schematic. The same reference symbols designate the same objects, so that explanations from other figures can be used as a supplement if necessary. Show it:

1

a flow chart of a first example of a method for generating energy; and

2

a flow chart of a second example of a method for generating energy.

1 shows a flow chart of a first example of a method for generating energy, in which pure hydrogen 1 and pure oxygen 2 are supplied to a combustion chamber 3 . In the combustion chamber 3, the hydrogen 1 oxidizes with the oxygen 2 to form water. Since the temperatures in a pure oxidation of the hydrogen 1 with the oxygen 2 in the combustion chamber 3 lead to very high temperatures in the combustion chamber 3, in particular of 2,000° C. [degrees Celsius] and more, liquid water 4 is supplied to the combustion chamber 3 at the same time. This leads to the cooling of the gases (hydrogen 1, oxygen 2 and water vapor) in the combustion chamber 3. In particular, the vaporization enthalpy of the supplied water 4 is also available for cooling. The water 4 is preferably injected into the combustion chamber 3 via one or more spray nozzles. Water vapor 5 is discharged from the combustion chamber 3 and is composed on the one hand of the water formed from the reaction of the hydrogen 1 with the oxygen 2 and on the other hand of the vaporized and heated liquid water 4 supplied.

The resulting water vapor 5 is fed to a steam turbine 6 for relaxation, which drives an electric generator 7 to generate electricity. The electricity generated in this way is preferably supplied to an electrical energy network. At the same time, the steam turbine 6 drives, at least temporarily, a first compressor 8 by means of which the oxygen 2 can be compressed before it is fed to the combustion chamber 3 .

After flowing through the steam turbine 6, the steam 5, which may carry water in the form of drops (wet steam), is fed to a heat exchanger 9, in which the heat of the steam 5 is given off to a first heat transfer medium 10, which flows through the heat exchanger 9. The first heat transfer medium 10 can also be water, for example, which is used in another process and which is heated while flowing through the heat exchanger 9 and possibly even evaporated. Alternatively or optionally in addition, this first cooling stage can also be implemented by intermediate cooling in an intermediate stage of the steam turbine (in 1 not shown).

Downstream of the heat exchanger 9 , the water vapor 5 flows through a condenser 11 , in which the water vapor 5 condenses to form liquid water 12 and at the same time gives off heat to a second heat transfer medium 13 . The liquid water 12 is supplied to a reservoir 15 via a first pump 14 .

Before being fed to the combustion chamber 3, the liquid water 4 is removed from the reservoir 15, which can have a water supply (not shown) for topping up with water from outside the system. If the pressure level in the reservoir 15 is not high enough, a second pump 23 can optionally be provided, which pumps the water 4 into the combustion chamber 3 at a corresponding pressure. At the same time, at least if required, liquid water 16 can be removed from the reservoir 15 and fed to a water electrolyzer 17 in which hydrogen 18 and oxygen 19 are generated from the water 16 fed using electrical energy. The hydrogen 18 is stored under pressure in a first intermediate store 20 and the oxygen 19 in a second intermediate store 21 . If required, the hydrogen 1 is then removed from the first intermediate store 20 and fed to the combustion chamber 3 . Optionally, a second compressor 22 can be formed, which enables the pressure of the hydrogen 1 to be increased before it is fed to the combustion chamber 3 . This can be driven via the same shaft as the first compressor 8. For this purpose, an electric motor--not shown--is used as a drive. If necessary, the oxygen 2 that is supplied to the combustion chamber 3 is removed from the second intermediate store 21 . Both the first buffer store 20 and the second buffer store 21 preferably include external supplies, not shown here, via which the buffer stores 20, 21 can be filled with hydrogen or oxygen independently of the operation of the water electrolyzer 17.

The combination of the combustion chamber 3 with the water electrolyzer 17 advantageously allows electrical energy to be stored and released alternately. If there is an oversupply of electrical energy, for example in an electrical energy network, this oversupply can be used to operate the water electrolyzer 17 and the resulting hydrogen 18 and oxygen 19 can be stored in the intermediate stores 20, 21. If there is an insufficient supply of electrical energy, hydrogen 1 and oxygen 2 can then be produced from the intermediate stores 20, 21 to generate electrical energy by combustion in the combustion chamber 3 with expansion of the resulting water vapor 5 in the steam turbine 6, driving the electric generator 7 and the electric be supplied to the power grid. In this way, electrical energy can be stored and released alternately. This is advantageous in particular for storing electrical energy from renewable sources such as photovoltaics or wind energy, since these are not available evenly but depend on the weather conditions.

2 shows a second example of a method for generating energy. Only the differences from the first example will be discussed here; otherwise, to avoid repetition, reference is made to the description of the first example. In the second example, the second compressor 22 and/or the first compressor 8 are driven by an electric motor 24 .

With regard to the direction of flow of the hydrogen 1 and the oxygen 2 , the first buffer store 20 is formed downstream of the second compressor 22 and the second buffer store 21 is formed downstream of the first compressor 8 . As a result, the pressure in the intermediate stores 20, 21 can be adjusted so that the pressure at which the hydrogen 1 and oxygen 2 are provided for the combustion chamber 3 can be regulated via the pressure in the intermediate stores 20, 21. Such an embodiment can also be implemented with the compressors 8, 22 and the buffer stores 20, 21 of the first example. As shown, one or both intermediate stores 20, 21 can be bypassed via bypass lines 30, so that hydrogen 1 and/or oxygen 2 is conveyed directly into the combustion chamber 3 by the respective compressor 22, 8.

In the second example, the steam turbine 6 is designed in two stages, ie it has a first stage 25 and a second stage 26 through which steam 5 flows in succession. In this case, an intermediate cooler 27 is formed between the first stage 25 and the second stage 26, via which the steam 5 can be intermediately cooled between the first stage 25 and the second stage 26.

Furthermore, the supply lines between the compressors 8, 22 and the intermediate stores 20, 21 also have gas coolers 28, via which heat can be extracted from the compressed gas flows. Between the memory 15 and the water electrolyzer 17, a third pump 29 is formed, via which the pressure of the water 16 at Supply to the water electrolyzer 17 can be increased. First pump 14, second pump 23 and third pump 29 are preferably each driven by an electric motor 24.

Reference List

1

hydrogen

2

oxygen

3

combustion chamber

4

liquid water

5

Steam

6

steam turbine

7

electric generator

8th

first compressor

9

heat exchanger

10

first heat transfer medium

11

capacitor

12

liquid water

13

second heat transfer medium

14

first pump

15

Storage

16

water

17

water electrolyser

18

hydrogen

19

oxygen

20

first cache

21

second cache

22

second compressor

23

second pump

24

electric motor

25

first stage of the steam turbine

26

second stage of the steam turbine

27

intercooler

28

gas cooler

29

third pump

30

bypass line

Claims (11)

Method for generating electrical energy, comprising the following steps: a) supplying hydrogen (1), oxygen (2) and liquid water (4) into a combustion chamber (3), b) oxidation of the hydrogen (1) with the oxygen (2) in the combustion chamber (3) to form water vapor (5); c) expansion of the water vapor (5) via a steam turbine (6) which drives an electric generator (7). Method according to Claim 1, in which the oxygen (2) is supplied to the combustion chamber (3) via a first compressor (8). Method according to one of the preceding claims, in which the hydrogen is supplied to the combustion chamber via a second compressor. Method according to one of the preceding claims, in which the water vapor (5), after flowing through the steam turbine (6), is fed to a heat exchanger (9) for dissipating heat to a heat transfer medium (10). Method according to one of the preceding claims, in which the steam (5), after flowing through the steam turbine (6), is fed to a condenser (11) and is condensed there completely to form liquid water (12). Method according to Claim 5, in which the condensed water (12) is supplied to a reservoir (15) via a first pump (14). Method according to Claim 6, in which the liquid water (4) for supply to the combustion chamber (3) is taken from the reservoir (15). Method according to Claim 6 or 7, in which water (16) from the reservoir (15) is subjected to water electrolysis. Method according to one of the preceding claims, in which at least one of the following gases: hydrogen (1) and oxygen (2) is produced by water electrolysis before being fed to the combustion chamber (3). Method according to Claim 9, in which at least one of the following gases produced in the water electrolysis: hydrogen (18) and oxygen (19) is stored in an intermediate store (20, 21) and removed from this for supply to the combustion chamber (3). Method for alternately storing and delivering electrical energy, in which, in the event of an energy requirement, electrical energy is generated according to the method according to one of the preceding claims and in the event of an energy oversupply, electrical energy is used to operate a water electrolyzer (17), the hydrogen produced therein (18) and oxygen (19) are stored for later supply to the combustion chamber (3).

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