METHOD FOR MEASURING A DEGREE OF HYDROGENATION

Abstract

A method for detecting a degree of hydrogenation of a liquid comprises one or more liquid hydrogen carriers, which can be hydrogenated, comprising: detecting a material property of the liquid and determining the degree of hydrogenation of the liquid on the basis of the detected material property of the liquid.

Claims

1-15. (canceled)

16. A method for detecting a degree of hydrogenation of a liquid, which comprises one or more liquid hydrogen carriers which can be hydrogenated, having the following steps: detecting a material property of the liquid; and determining the degree of hydrogenation of the liquid on the basis of the detected material property of the liquid.

17. The method as claimed in claim 16, wherein in the step of detecting the material property, at least one of the following material properties is detected: density, optical index of refraction, relative permittivity, speed of sound, viscosity, adsorption, absorption, or at least one material property which is derivable from material data such as density of the liquid.

18. The method as claimed in claim 16, wherein the material property is an optical index of refraction, and wherein the optical index of refraction is determined by means of a refractometer, a goniometer, or a Michelson interferometer.

19. The method as claimed in claim 16, furthermore having the steps of detecting the density of the liquid and determining the degree of hydrogenation based on the density of the liquid.

20. The method as claimed in claim 16, wherein the liquid comprises a mixture of an unsaturated cyclic hydrocarbon compound and an at least partially hydrogenated unsaturated cyclic hydrocarbon compound, and preferably a mixture of N-ethyl carbazole and at least partially hydrogenated N-ethyl carbazole, or a mixture of dibenzyl toluene and at least partially hydrogenated dibenzyl toluene, or a mixture of benzyl toluene and at least partially hydrogenated benzyl toluene, or a mixture of benzyl toluene, dibenzyl toluene, at least partially hydrogenated dibenzyl toluene, and at least partially hydrogenated benzyl toluene.

21. The method as claimed in claim 16, wherein the degree of hydrogenation of the liquid is determined on the basis of a linear relationship of the degree of hydrogenation and the detected material property.

22. The method as claimed in claim 16, wherein the material property, in particular density, is determined by means of a hydrometer, a pycnometer, a hydrostatic weighing, or an oscillation measurement.

23. A measuring device for detecting a degree of hydrogenation of a liquid, which comprises one or more liquid hydrogen carriers which can be hydrogenated, having: a detection device for detecting a material property of the liquid; and a determination device for determining the degree of hydrogenation on the basis of the detected material property of the liquid.

24. The measuring device as claimed in claim 23, wherein the detection device is configured to detect at least one of the following material properties: density, optical index of refraction, relative permittivity, speed of sound, viscosity, adsorption, absorption, or at least one material property which is derivable from material data such as density of the liquid.

25. The measuring device as claimed in claim 23, wherein the material property is an optical index of refraction, and wherein the detection device comprises a refractometer, a goniometer, or a Michelson interferometer.

26. The measuring device as claimed in claim 23, wherein the measuring device comprises a detection device for detecting data of the liquid in a tank, in particular weight or volume.

27. The measuring device as claimed in claim 26, wherein the measuring device comprises a calculation device for calculating a stored or storable quantity of energy in the tank on the basis of the degree of hydrogenation and the quantity of liquid.

28. The measuring device as claimed in claim 27, wherein the measuring device comprises a fuel gauge for displaying the stored or storable quantity of energy in the tank.

29. The measuring device as claimed in claim 26, wherein the detection device comprises a hydrometer, a pycnometer, a hydrostatic scale, or a device for oscillation measurement.

30. A vehicle having a tank for a liquid, which comprises one or more liquid hydrogen carriers which can be hydrogenated, having the measuring device as claimed in claim 23.

Description

[0043] In the figures:

[0044] FIG. 1 shows partially hydrogenated isomers of N-ethyl carbazole;

[0045] FIG. 2 shows isomers of dibenzyl toluene; and

[0046] FIG. 3 shows a schematic view of a measuring device for detecting a degree of hydrogenation of a liquid.

[0047] FIG. 1 shows partially hydrogenated isomers of N-ethyl carbazole and FIG. 2 shows possible isomers of dibenzyl toluene. Both substances are examples of a liquid hydrogen carrier (LOHC—Liquid Organic Hydrogen Carrier), which comprises aromatic compounds.

[0048] A low-energy form of the liquid hydrogen carrier is reversibly converted by means of catalyzed hydrogenation by hydrogen into a high-energy form. In a back reaction, which is differently catalyzed, for example, by temperature increase and/or reduction of the hydrogen pressure, hydrogen is reclaimed again from the hydrogenated high-energy form while forming the low-energy form. The reaction is reversible, so that the liquid hydrogen carrier can be guided from a low-energy to a high-energy location in the circuit, without consuming itself. The liquid hydrogen carrier is the transporter for energy in the form of hydrogen.

[0049] Particularly advantageously usable liquid hydrogen carriers enable this reversible conversion under technically relevant conditions, for example, at pressures and temperatures which are easily technically feasible. The hydrogen storage in liquid hydrogen carriers has the advantage that the liquid hydrogen carriers are liquid under the process conditions used, are unpressurized in the storage, and have a high similarity to conventional liquid fuels in the physicochemical properties thereof. Therefore, pumps for the transport and containers for the storage from the field of fuel and combustible material logistics can be used. The hydrogen storage in chemically bound form in an organic liquid enables unpressurized storage at normal conditions over long periods of time without significant hydrogen loss. Liquid hydrogen carriers are based, for example, on the materials N-ethyl carbazole, benzyl toluene, or dibenzyl toluene.

[0050] Due to the different isomers, more than two materials can arise during the hydrogenation or dehydrogenation procedure and can be present simultaneously in a complex mixture. The liquid which is formed by the liquid hydrogen carrier therefore comprises a number of partially hydrogenated, fully hydrogenated, or non-hydrogenated components in different concentrations.

[0051] Because a liquid hydrogen carrier is not consumed during the use as a hydrogen energy supplier, the liquid formed by the hydrogen carrier is not removed from a tank, but rather only changes the energy content thereof due to the changing concentrations of the individual components. A material pair of a hydrogen-charged and hydrogen-discharged form of the liquid hydrogen carrier is therefore always located in the tank.

[0052] A determination of the degree of hydrogenation h in this multicomponent mixture could be performed in that the respective individual concentrations are measured. However, this method is complex. In a simpler manner, the thermophysical variables such as density ρ and index of refraction n of the liquid may be used to determine a degree of hydrogenation h.

[0053] The index of refraction n is a dimensionless physical variable. The index of refraction n specifies the ratio of the speed of light in vacuum to the propagation speed of light in the liquid. Therefore, the index of refraction in vacuum is equal to 1 and increases with increasing density. In the specification, the wavelength of the measuring light should be noted. The density p of the liquid is the mass of the liquid divided by its volume, for example, in kilograms per cubic meter. In general, these variables are correlated with one another.

[0054] The permittivity or dielectric conductivity describes the permeability of a material or material mixture to electric fields. The relative permittivity □.sub.r is defined as the dimensionless ratio of the permittivity in material and in vacuum. The latter is referred to as the field constant. Instead of the field constant, the permittivity of air is often also used as the reference variable.

[0055] The relative permittivity of a material or material mixture, for example, a liquid, can be determined with the aid of a capacitor. The capacitance of the capacitor, filled using the material or the material mixture having unknown permittivity, is determined using an LCR meter. The capacitance of the same capacitor filled using a substance of known permittivity, generally air, is used as a reference. The ratio of the two capacitances is referred to as the relative permittivity.

[0056] The dynamic viscosity is a measure of the viscosity of a liquid or a gas. The fluidity of a material decreases with increasing dynamic viscosity.

[0057] The use of the index of refraction n and/or the density p to determine the degree of hydrogenation h is advantageous in particular with liquid hydrogen carriers if non-hydrogenated, partially hydrogenated, and fully hydrogenated forms of the hydrogen carrier are stored in a mixture together in a tank.

[0058] In a multicomponent mixture, which consists of materials having identical basic structure, the degree of hydrogenation is a linear function of the index of refraction n and/or the density ρ. A simple and efficient determination of the degree of hydrogenation of the hydrogen-storing liquid can thus be ensured on the basis of a measurement of the index of refraction n and/or the density ρ.

[0059] In a further embodiment, the degree of hydrogenation can be a nonlinear or a logarithmic function of the index of refraction n and/or the density ρ. A nonlinear relationship can comprise, for example, an exponential or a polynomial relationship. Because the degree of hydrogenation can be a nonlinear or a logarithmic function of the index of refraction n and/or the density p, a simple and efficient determination of the degree of hydrogenation is enabled. Due to the advantageous calculation of the degree of hydrogenation, an automated determination of the degree of hydrogenation of the liquid, for example, in a tank, can be achieved.

[0060] FIG. 3 shows a schematic view of a measuring device 100 for detecting a degree of hydrogenation. The measuring device 100 comprises a detection device 101 for detecting a material property of the liquid 107, for example, the optical index of refraction of the liquid 107 or a density detection device 101 for detecting the density of the liquid 107. Furthermore, the detection device 100 comprises a determination device 103 for determining the degree of hydrogenation on the basis of the detected material property of the liquid 107, for example, the optical index of refraction or the density of the liquid 107. Both thermophysical measured variables can be measured in a simple manner. The determination device 103 can be formed, for example, by a processor having a memory, which permits the execution of mathematical operations.

[0061] The measuring device 100 can be used in this case as a fuel gauge, which displays how high the degree of hydrogenation of the liquid 107 in the tank 105 is. The fuel gauge can be attached to the tank 105 itself or installed in supply lines and/or drain lines to the tank 105. The tank contents can be recirculated through these lines for better mixing. The measuring device 100 can be used in stationary or mobile tanks 105 for the liquid hydrogen carriers. The quantity of a liquid hydrogen carrier in kilograms which is located in the tank 105 is known, for example, by weighing upon filling.

[0062] In the stationary case, the measuring device 100 can display how much energy in the form of releasable hydrogen is contained in the tank 105 and can display the energy content of the tank 105. Conclusions can be drawn therefrom about a chronological range of the tank 105. A user of the tank 105 for liquid hydrogen carriers can ascertain in this manner what quantity of energy is storable in the tank 105.

[0063] The measuring device 105 can additionally be used to track the hydrogenation of a liquid hydrogen carrier in a reactor, so that a chemical conversion can be determined. The measuring device 100 can be used to monitor the reaction progress in chemical reactors, which store hydrogen in liquid hydrogen carriers or generate hydrogen from the hydrogen carriers.

[0064] The measuring device 100 can be used to display the range of a vehicle, which comprises a tank 105 for liquid hydrogen carriers, if the energy requirement per kilometer of driving performance is known. The range is directly linked to the energy content, which is based on the quantity of the liquid hydrogen carrier and the degree of hydrogenation h.

[0065] The vehicle uses the released hydrogen for the drive. For this purpose, a change of the high-energy form of the liquid hydrogen carrier into a low-energy form while forming hydrogen is provided. If the vehicle has a single tank 105 for the liquid hydrogen carriers, a mixture of hydrogenated liquid hydrogen carriers is provided in this tank 105. The measuring device 100 can be used by difference calculation to account for the energy supply at a filling station, if a partially hydrogenated or non-hydrogenated liquid hydrogen carrier is discharged at the filling station and subsequently a partially hydrogenated or fully hydrogenated liquid hydrogen carrier is acquired from the filling station.

[0066] All features which are explained and shown in conjunction with individual embodiments of the invention can be provided in different combinations in the subject matter according to the invention, to implement the advantageous effects thereof simultaneously.

[0067] The scope of protection of the present invention is given by the claims and is not restricted by the features which are explained in the description or shown in the figures.

LIST OF REFERENCE SIGNS

[0068] 100 measuring device [0069] 101 detection device/density detection device [0070] 103 determination device [0071] 105 tank [0072] 107 liquid [0073] S101 method step [0074] S102 method step [0075] S201 method step [0076] S202 method step