Pumpless Metal Atomization And Combustion Using Vacuum Generation And Suitable Material Flow Control

Abstract

A method is provided for combustion of an electropositive metal using a combustion gas. The electropositive metal, in the form of a fluid or powder having particles with a particle size of less than 100 μm, is drawn out of a container by atomizing a carrier gas in a first nozzle, which tapers in relation to the cross-section in the flow direction of the carrier gas. The electropositive metal is drawn out of the container into the first nozzle, atomized out of said nozzle and combusted using the combustion gas.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application of International Application No. PCT/EP2015/059850 filed May 5, 2015, which designates the United States of America, and claims priority to DE Application No. 10 2014 210 402.5 filed Jun. 3, 2014, the contents of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a method for the combustion of an electropositive metal with a combustion gas, the electropositive metal in the form of a liquid or powder comprising particles with a particle size of less than 100 μm being sucked out of a container by atomizing a carrier gas in a first nozzle, which in cross section initially tapers in the direction of flow of the carrier gas, from the container into the first nozzle, atomized out of the latter and burned with the combustion gas, and also relates to a device for carrying out the method.

BACKGROUND

Fossil fuels deliver tens of thousands of terawatt hours of electrical, thermal and mechanical energy per year. However, the end product of the combustion, carbon dioxide (CO2), is increasingly becoming an environmental and climatic problem.

In DE 10 2008 031 437.4, DE 10 2010 041 033.0 and DE 10 2013 224 709.5, it is demonstrated how a complete energy cycle can be formed with electropositive metals and how operating a power plant by means of lithium as a metal substitute for coal can be realized. Specifically lithium served as a case study here, both as an energy carrier and as an energy storage means, it also being possible to use other electropositive metals such as sodium, potassium or magnesium, calcium, barium or aluminum and zinc.

Basic investigations into the reaction of liquid lithium with various gases and gas mixtures are known in the literature (Bernett, D. S.; Gil, T. K.; Kazimi, M. S.; Fusion Technology, 1989, 15, 2, pp. 967-972; A. Subramani, S. Jayanti, Combustion and Flame 158 (2011), 1000-1007). The process used for this comprises a reaction chamber, into which lithium is filled and reacted by being liquefied at 400° C.

Gas mixtures of oxygen, nitrogen and water vapor were introduced into the chamber by way of a gas inlet through which the liquid lithium was directed (Gil, T. K.; Kazimi, M. S.: The kinetics of liquid lithium reaction with oxygen-nitrogen mixture, pages 20, 21 and 46, Plasma Fusion Center and the Department of Nuclear Engineering, MIT, Cambridge, Mass., 1986, USA).

In order that the combustion processes for providing thermal energy can be used for producing electricity, the lithium should be introduced into the oxidizing agent in the same way as in the case of coal or natural oil burners in the form of a powder or spray with a large surface area to maintain a sufficient energy flow.

A method for producing lithium particles is described in DE 10 2011 052 947 A1. Disclosed therein is the production of products such as metal oxides, metal hydrides or metal nitrides by reacting lithium—in particle form—with a reactive gas (oxygen, water or nitrogen).

In DE 102 04 680 A1 there is a description of a method for producing alkyl lithium compounds by means of atomization of lithium metal, in which metallic lithium in the form of particles is reacted with an alkyl halide.

In DE 102013224709.5 it is described how a process plant for the continuous combustion of lithium including a delivery unit may look.

For the use of lithium as an energy storage means in a power plant process for converting the stored chemical energy into thermal energy and subsequently supplying electricity, the possibility of continuously feeding and atomizing the lithium into a combustion chamber is a pre-requisite. On account of the necessary high temperatures during a liquefaction of electropositive metals and the media aggressivity of for example lithium and sodium, problems may arise if conventional pumps and flow controllers are used.

For the atomization and combustion of electropositive metals such as lithium, sodium, potassium, magnesium, calcium, barium, aluminum and zinc, in principle the following setup is advantageous. The material to be atomized is delivered by means of a pump from a container through a nozzle and possibly ignited, depending on the self-ignitability of the material. The pressure through the nozzle and the rate of delivery may in this case be set by way of a controller upstream of the nozzle. When atomizing aggressive media, in particular alkali metals, but also other electropositive metals, such a setup is however problematic, since the metal flows through the pump and the controller and thereby comes into contact with parts which, owing to the type of construction, are not media-resistant. Furthermore, for delivery or atomization and combustion, electropositive metals are preferably liquefied or heated, and therefore have a temperature of up to several hundred ° C., which can be achieved for example by electromagnetic pumps, it being possible here however for problems with the pressure to occur. However, many pumps and controllers are not designed for such high temperatures. Moreover, there may be deposits of electropositive metal in the pumps and/or controllers, conveyor belts, etc., which cannot be easily removed. In order to avoid contact of the electropositive metals with pumps and/or controllers, etc., a method that allows atomization and combustion of electropositive metals without direct contact with pumps and/or controllers is consequently required.

SUMMARY

One embodiment provides a method for the combustion of an electropositive metal, which is selected from alkali metals, alkaline earth metals, aluminum and zinc and/or alloys and/or mixtures of the same, with a combustion gas, the electropositive metal in the form of a liquid or powder comprising particles with a particle size of less than 100 μm being sucked out of a container by atomizing a carrier gas in a first nozzle, which in cross section initially tapers in the direction of flow of the carrier gas, from the container into the first nozzle, atomized out of the latter and burned with the combustion gas.

In one embodiment, the first nozzle as a Venturi nozzle consisting of a piece initially tapering in the direction of flow of the carrier gas, a piece of a constant diameter and a piece with a widening cross section, the feeding of the electropositive metal preferably taking place through at least one second feeding device to the first nozzle in the constant piece.

In one embodiment, the first nozzle being formed as a Laval nozzle from a piece tapering in the direction of flow of the carrier gas and a piece diverging in the direction of flow.

In one embodiment, the feeding of the electropositive metal taking place in the region of the smallest cross section of the Laval nozzle.

In one embodiment, the feeding of the electropositive metal taking place through a second feeding device, the outlet opening of which is arranged, preferably coaxially, within the first nozzle in the region of the tapering part of the first nozzle.

In one embodiment, the first nozzle being arranged, preferably coaxially, within a second feeding device in the region of a, preferably converging, part of the second feeding device, the feeding of the carrier gas taking place through the first nozzle, and the feeding of the electropositive metal taking place through the second feeding device.

In one embodiment, the carrier gas is the combustion gas.

In one embodiment, the amount of atomized electropositive metal being controlled by way of the filling in the container, and/or the amount of atomized electropositive metal being controlled by way of the pressure of the carrier gas, by the feed for the carrier gas being connected to the container upstream of the first nozzle in the direction of flow, and/or the feeding of atomized electropositive metal being controlled by way of a feeding of inert gas with controlled pressure to the container.

Another embodiment provides a device for burning an electropositive metal, which is selected from alkali metals, alkaline earth metals, aluminum and zinc and/or alloys and/or mixtures of the same, with a combustion gas, comprising a first nozzle, which in cross section initially tapers, to which a carrier gas is fed and which is designed to atomize electropositive metal with the carrier gas; a first feeding device for carrier gas to the first nozzle, which is designed to feed carrier gas to the first nozzle; a container, which is designed to provide the electropositive metal in the form of a liquid or in the form of a powder comprising particles with a particle size of less than 100 μm; a second feeding device for electropositive metal to the first nozzle, which is designed to direct the electropositive metal out of the container to the first nozzle, and a burner, which is designed to burn the electropositive metal with the combustion gas.

In one embodiment, the first nozzle as a Venturi nozzle consisting of a piece initially tapering in the direction of flow of the carrier gas, a piece of a constant diameter and a piece with a widening diameter, the second feeding device for electropositive metal preferably being fitted on the constant piece of the Venturi nozzle.

In one embodiment, the first nozzle being formed as a Laval nozzle from a piece tapering in the direction of flow of the carrier gas and a piece diverging in the direction of flow.

In one embodiment, the second feeding device for electropositive metal being fitted in the region of the smallest diameter of the Laval nozzle.

In one embodiment, the second feeding device for electropositive metal being arranged, preferably coaxially, within the first feeding device for carrier gas in such a way that the outlet opening of the second feeding device for electropositive metal is arranged, preferably coaxially, within the first nozzle in the region of the converging part of the first nozzle.

In one embodiment, the first feeding device for carrier gas being arranged in such a way that the carrier gas is fed to the first nozzle, preferably coaxially, within the second feeding device for the electropositive metal in the region of a, preferably converging, part of the second feeding device.

In one embodiment, the device also comprises a third feeding device for electropositive metal to the container, which is designed to feed electropositive metal to the container, and a controlling device for the amount of electropositive metal in the container, which is designed to control the amount of electropositive metal fed to the container, and/or a line, which connects the first feeding device for carrier gas to the container upstream of the first nozzle in the direction of flow in such a way that the pressure of the carrier gas controls the amount of electropositive metal fed to the first nozzle, and/or a fourth feeding device for inert gas to the container, which is designed to feed inert gas to the container, and a controlling device for the pressure of the fed inert gas, which controls the pressure of the inert gas fed to the container.

BRIEF DESCRIPTION OF THE DRAWINGS

Example aspects and embodiments of the invention are discussed below with reference to the figures, in which:

FIG. 1 schematically shows the setup of a Venturi nozzle.

FIG. 2 schematically shows the pressure relationships in a device according to the invention for atomizing electropositive metal with a Venturi nozzle.

FIG. 3 shows the device from FIG. 2 in the operating state.

FIG. 4 schematically shows a further embodiment according to the invention of a device for atomizing electropositive metal with a Venturi nozzle and internal mixing of the carrier gas and electropositive metal and also the assignment of the pressures and components.

FIG. 5 shows the device from FIG. 4 in the operating state with the atomization of the electropositive metal.

FIG. 6 schematically represents a further embodiment of a device according to the invention for the atomization of an electropositive metal with a Laval nozzle and internal mixing of the carrier gas and electropositive metal and shows the assignment of the pressures and components.

FIG. 7 shows the device from FIG. 6 in the operating state with the atomization of the electropositive metal.

FIG. 8 schematically represents the use of the hydrostatic pressure of the electropositive metal during the atomization.

FIG. 9 schematically represents a further embodiment of a device according to the invention for the atomization of electropositive metal with external mixing of the carrier gas and electropositive metal and shows the assignment of the pressures and components.

FIG. 10 shows the device from FIG. 9 in the operating state with the atomization of the electropositive metal.

FIG. 11 schematically represents a further embodiment of a device according to the invention for the atomization of electropositive metal by means of a jet pump and shows the assignment of the pressures and components.

FIG. 12 shows the device from FIG. 11 in the operating state with the atomization of the electropositive metal.

DETAILED DESCRIPTION

Sone embodiments of the present invention provide a method and a device that make it possible to atomize electropositive metals such as lithium in a continuous process without direct media contact with pumps and/or flow controllers.

Other embodiments provide a method and a device that make it possible to burn electropositive metals such as lithium in a continuous process without a delivery device such as a pump, extruder or other delivery unit being necessary.

Other embodiments provide a method and a device in which efficient delivery and mixing of an electropositive metal with a combustion gas can be achieved.

It has now been found that it is possible by using a tapering nozzle in a carrier gas flow, onto which a feed for an electropositive metal is fitted, to introduce the electropositive metal through the suction effect of the nozzle into the carrier gas flow and atomize it therein without a delivery device such as a pump being required. Moreover, the conversion of the chemical energy stored in the electropositive metal into thermal energy is made possible according to the invention by a specifically selective atomization, possibly ignition, and possibly complete combustion in a continuous combustion process that is relevant to the power plant.

One embodiment provides a method for the combustion of an electropositive metal, which is selected from alkali metals, alkaline earth metals, aluminum and zinc and/or alloys and/or mixtures of the same, with a combustion gas, the electropositive metal in the form of a liquid or powder comprising particles with a particle size of less than 100 μm being sucked out of a container by atomizing a carrier gas in a first nozzle, which in cross section initially tapers in the direction of flow of the carrier gas, from the container into the first nozzle, atomized out of the latter and burned with the combustion gas.

Another embodiment provides a device for burning an electropositive metal, which is selected from alkali metals, alkaline earth metals, aluminum and zinc and/or alloys and/or mixtures of the same, with a combustion gas, comprising a first nozzle, which in cross section initially tapers, to which a carrier gas is fed and which is designed to atomize electropositive metal with the carrier gas, a first feeding device for carrier gas to the first nozzle, which is designed to feed carrier gas to the first nozzle, a container, which is designed to provide the electropositive metal in the form of a liquid or in the form of a powder comprising particles with a particle size of less than 100 μm, a second feeding device for electropositive metal to the first nozzle, which is designed to direct the electropositive metal out of the container to the first nozzle, and a burner, which is designed to burn the electropositive metal with the combustion gas.

One embodiment provides a method for the combustion of an electropositive metal, which is selected from alkali metals, alkaline earth metals, aluminum and zinc and/or alloys and/or mixtures of the same, with a combustion gas, the electropositive metal in the form of a liquid or powder comprising particles with a particle size of less than 100 μm being sucked out of a container by atomizing a carrier gas in a first nozzle, which in cross section initially tapers in the direction of flow of the carrier gas, from the container into the first nozzle, atomized out of the latter and burned with the combustion gas.

The atomization may take place here in such a way that the mixing of the carrier gas and electropositive metal takes place in the first nozzle as internal mixing or not until after the first nozzle as external mixing, it being possible here for the first nozzle also to consist only of the tapering portion.

The electropositive metal is a metal which, according to certain embodiments, is selected from alkali metals, preferably Li, Na, K, Rb and Cs, alkaline earth metals, preferably Mg, Ca, Sr and Ba, Al and Zn, and also mixtures and/or alloys of the same. In preferred embodiments, the electropositive metal is selected from Li, Na, K, Mg, Ca, Al and Zn, more preferably Li and Mg, and particularly preferably the electropositive metal is lithium.

According to certain embodiments, the electropositive metal is liquid. In the case of such embodiments, easy handling and atomization of the electropositive metal is possible. Moreover, more efficient atomization and delivery can be obtained in comparison with a powder with a particle size of less than 100 μm. Easier cleaning of the device may also be possible in comparison with the powder particles, which possibly can settle in cracks, gaps, etc. of the apparatus. According to certain embodiments, use of the electropositive metal in the form of a liquid is preferred.

According to certain embodiments, the electropositive metal may also be used in the form of a powder comprising particles with a particle size of less than 100 μm. This gives rise to the advantage that liquefaction of the metal is not required and the energy for melting the metal can consequently be saved. Due to the lower temperature, however, it may possibly also be necessary, depending on the electropositive metal and the combustion gas, for the reaction with the combustion gas to be started, while it could be the case that this is not necessary in the liquid state. The particle size in the powder can be set in a suitable way and the powder can be provided in a suitable way, possibly commercially. The particle size may be determined according to customary methods, such as for example microscopically or by laser diffraction in a customary way.

According to certain embodiments, gasses that come into consideration as the combustion gas are those which can react with the electropositive metal mentioned or mixtures and/or alloys of the electropositive metals in an exothermic reaction, these not being particularly restricted. By way of example, the combustion gas may comprise air, oxygen, carbon dioxide, hydrogen, water vapor, nitrogen oxides NOx such as nitrous oxide, nitrogen, sulfur dioxide, or mixtures of the same. The method can therefore also be used for desulfurization or NOx removal. Depending on the combustion gas, various products can be obtained thereby with the various electropositive metals and may occur in the form of a solid or liquid and also in a gaseous form.

Thus, for example, in the case of a reaction of electropositive metal, for example lithium, with nitrogen, there may be produced inter alia metal nitride, such as lithium nitride, which can then later be allowed to react further to form ammonia, whereas in the case of a reaction of electropositive metal, e.g. lithium, with carbon dioxide, there may be produced for example metal carbonate, e.g. lithium carbonate, carbon monoxide, metal oxide, e.g. lithium oxide, or else metal carbide, e.g. lithium carbide, and also mixtures thereof, it being possible to obtain from the carbon monoxide higher-value carbon-containing products such as methane, ethane, methanol, etc., for example in a Fischer-Tropsch process, while it is possible to obtain from metal carbide, e.g. lithium carbide, for example acetylene. It is also possible, for example with nitrous oxide as the combustion gas, to produce e.g. metal nitride.

Analogous reactions may also be obtained for the other metals mentioned.

In some embodiments, the carrier gas is not particularly restricted, and may correspond to the combustion gas or comprise it, but may also be different from it. Air, carbon monoxide, carbon dioxide, oxygen, methane, hydrogen, water vapor, nitrogen, nitrous oxide, mixtures of two or more of these gases, etc. may be used for example as the carrier gas. Various gases, such as for example methane—which according to certain embodiments does not burn—may serve here for transporting the heat and for removing from the reactor the reaction heat of the reaction of the electropositive metal with the combustion gas. The various carrier gases may for example be suitably adapted to the reaction of the combustion gas with the electropositive metal, in order thereby possibly to achieve synergy effects. According to certain embodiments, the carrier gas is the combustion gas.

Embodiments of the invention are based on the principle of the Venturi nozzle. This is based on the notion that the flow rate of a medium flowing through a pipe behaves in inverse proportion to a changing pipe cross section. That is to say that the velocity is at the greatest where the cross section of the pipe is at the smallest. According to Bernoulli's law, in a flowing fluid (gas or liquid) an increase in velocity is also accompanied by a drop in pressure. Accordingly, for a nozzle as shown in FIG. 1 it is true that p₁>p₂, where p₁ is the pressure of the carrier gas upstream of the first nozzle in the direction of flow and p₂ is the pressure of the carrier gas at the smallest cross section of the first nozzle and the second feeding device and also v₁ is the velocity of the carrier gas upstream of the first nozzle in the direction of flow and v₂ is the velocity of the carrier gas at the smallest cross section of the first nozzle. This relationship can be exploited for the atomization and combustion of liquid electropositive metals.

The first nozzle, initially tapering in cross section, is not particularly restricted in its form, as long as the cross section of the nozzle initially decreases in the direction of flow of the carrier gas. After the decrease in the cross section and the feed for the electropositive metal, the nozzle may then decrease further in cross section, stay constant in cross section or increase in cross section. The form of the cross section may also change, while however according to certain embodiments it stays the same. The form of the cross section is not particularly restricted and may be round, elliptical, square, rectangular, triangular, etc., but according to certain embodiments is round in order to allow a uniform distribution of the electropositive metal and the carrier gas. A symmetrical nozzle form is also preferred.

In addition, the first nozzle is also not restricted any further in its configuration, as long as a region in which the cross section of the nozzle initially decreases in the direction of flow of the carrier gas is comprised. Thus, the first nozzle may be formed as a Venturi nozzle, as a Laval nozzle, in the form of a (water) jet pump, etc., and may comprise a feed for the electropositive metal in the interior, around the nozzle or on the nozzle itself. The feeding of the electropositive metal may in this case similarly take place by way of a feeding device, which has a nozzle, for example at the end of the feeding device in the direction of flow of the electropositive metal.

Further nozzles are also not particularly restricted and may comprise the above forms and configurations.

According to certain embodiments, the first nozzle as a Venturi nozzle consists of a piece initially tapering in the direction of flow of the carrier gas, a piece of a constant diameter and a piece with a widening cross section. The feeding of the electropositive metal may be arranged for example (a) within the Venturi nozzle itself, preferably through a second feeding device in a tapering piece of the Venturi nozzle, (b) in a second feeding device, which is arranged around the Venturi nozzle, preferably in the form of a tapering nozzle around the tapering part of the Venturi nozzle, or (c) through a feed line/second feeding device to the Venturi nozzle, which may be fitted in the tapering part of the Venturi nozzle or in the constant piece of the Venturi nozzle. According to certain embodiments, the feeding of the electropositive metal takes place through at least one feed line/feeding device to the first nozzle in the constant piece. It is however also possible for more than one feeding device to be fitted on the Venturi nozzle, or for combinations of types of feed line/feeding devices, for example on the Venturi nozzle and in the interior of the Venturi nozzle to be provided, according to certain embodiments only one feeding device directing the electropositive metal to the Venturi nozzle, in order to control the feeding of the electropositive metal more easily.

According to certain embodiments, the first nozzle may be formed as a Laval nozzle from a piece tapering in the direction of flow of the carrier gas and a piece diverging in the direction of flow, that is to say increasing in cross section. Here, too, the feeding of the electropositive metal may take place for example (a) within the Laval nozzle itself, preferably through a second feeding device in a tapering piece of the Laval nozzle, (b) in a second feeding device, which is arranged around the Laval nozzle, preferably in the form of a tapering nozzle around the tapering part of the Laval nozzle, or (c) through a feed line/second feeding device to the Laval nozzle, which may be fitted in the tapering part of the Laval nozzle or at the transition from the tapering piece to the diverging piece. It is however also possible for more than one feeding device to be fitted on the Laval nozzle, or for combinations of types of feed line/feeding devices, for example on the Laval nozzle and in the interior of the Laval nozzle to be provided, according to certain embodiments only one feeding device directing the electropositive metal to the Laval nozzle, in order to control the feeding of the electropositive metal more easily. According to certain embodiments, the feeding of the electropositive metal takes place in the region of the smallest cross section of the Laval nozzle, for example through a feeding device on the nozzle or in the interior of the nozzle.

According to certain embodiments, the Laval nozzle is in this case a flow member with an initially converging and subsequently diverging cross section, it being possible for the transition from one part to the other to take place gradually. In certain embodiments, the cross sectional area at each point may be circular, whereby a fluid flowing through can be accelerated to supersonic speed without excessive compression shocks occurring. The sonic speed can then be achieved more precisely in the narrowest cross section of the nozzle.

Furthermore, according to certain embodiments, the feeding of the electropositive metal for the various types of first nozzle may also take place through a second feeding device, the outlet opening of which is arranged, preferably coaxially, within the first nozzle in the region of the tapering part of the first nozzle, as already explained above for certain nozzles.

Also, according to certain embodiments, the first nozzle may be arranged, preferably coaxially, within a second feeding device in the region of a, preferably converging, that is to say tapering, part of the second feeding device, the feeding of the carrier gas taking place through the first nozzle, and the feeding of the electropositive metal taking place through the second feeding device. Such embodiments have also already been explained above for certain nozzles.

Moreover, according to certain embodiments, the amount of atomized electropositive metal can be controlled by way of the filling in the container, and/or the amount of atomized electropositive metal can be controlled by way of the pressure of the carrier gas, by the feed for the carrier gas being connected to the container upstream of the first nozzle in the direction of flow, and/or the feeding of atomized electropositive metal being controlled by way of a feeding of inert gas with controlled pressure to the container.

In the case of control by way of the filling in the container, a feeding device for electropositive metal may be provided, possibly with a control device such as a valve, by way of which electropositive metal is fed to the container continuously or discontinuously, depending on the desired filling level in the container and/or the carrier gas flow.

In the case of control of the amount of atomized electropositive metal by way of the pressure of the carrier gas, the feed for the carrier gas may be connected to the container upstream of the first nozzle in the direction of flow, connected in any way desired, it being possible for example for pipes, tubes, etc. to be used for the connection to the container and the feeding of the carrier gas into the container to be set for example also by way of the cross section of this connection and under certain circumstances also to be varied in the case of corresponding connections. There may also be such a possibility of variation for the second feeding device for the electropositive metal to the first nozzle.

In addition, in the case of control of the feeding of atomized electropositive metal by way of a feeding of inert gas with a controlled pressure to the container, the feeding of the inert gas may be suitably provided and set and is not particularly restricted, and nor are the two other possibilities of controlling the amount of atomized electropositive metal. The feeding of inert gas may also take place by way of a suitable tube, a pipe, etc., which may be provided with a control device such as a valve.

It is not ruled out that all three types of control, or any two types of control, for the amount of atomized electropositive metal are combined.

Other embodiments provide a device for burning an electropositive metal, which is selected from alkali metals, alkaline earth metals, aluminum and zinc and/or alloys and/or mixtures of the same, with a combustion gas, comprising

a first nozzle, which in cross section initially tapers, to which a carrier gas is fed and which is designed to atomize the electropositive metal with the carrier gas,

a first feeding device for carrier gas to the first nozzle, which is designed to feed the carrier gas to the first nozzle,

a container, which is designed to provide the electropositive metal in the form of a liquid or in the form of a powder comprising particles with a particle size of less than 100 μm,

a second feeding device for electropositive metal to the first nozzle, which is designed to direct the electropositive metal out of the container to the first nozzle, and

a burner, which is designed to burn the electropositive metal with the combustion gas.

The first feeding device for carrier gas is not particularly restricted here and comprises for example pipes, tubes, etc., it being possible for the feeding device for carrier gas to be suitably determined on the basis of the state of the carrier gas, which may possibly also be under pressure.

Similarly, the second feeding device for electropositive metal is not particularly restricted and likewise comprises for example pipes, tubes, etc., which suitably allow transport of the electropositive metal. The inner surface of the second feeding device is preferably smooth, in order to avoid deposits of electropositive metal. Furthermore, according to certain embodiments, the cross section of the second feeding device is constant over the entire length of the second feeding device, in order to ensure a good and steady delivery of the electropositive metal by the atomization in the first nozzle.

The nozzle may be configured here as described above, that is to say for example as a Venturi nozzle or as a Laval nozzle.

Similarly, the burner is not particularly restricted according to the invention and may for example be configured as a nozzle, in which the combustion gas is mixed with the electropositive metal and after that is possibly ignited by an ignition device. The burner may also be provided in or on the reactor. In addition, the burner may also be formed as a porous burner without internal mixing, which may be formed as a porous pipe to which the electropositive metal can be fed at at least one opening. The electropositive metal may for example be fed only through one opening of the pipe, it then being possible for the other end of the pipe to be closed or to consist of the material of the porous pipe. In such a case, the electropositive metal may then for example be pressed into the porous burner, whereupon the combustion gas can then be directed onto the outer side of the porous burner, so that it then reacts there with the electropositive metal in order to avoid clogging of the pores. According to certain embodiments in which the carrier gas is the combustion gas, the first nozzle may also be used for the atomizing, whereupon the combustion follows the nozzle outlet, by for example the combustion being ignited there or proceeding continuously after ignition.

The container is similarly not particularly restricted, as long as it consists of a material that does not react with the electropositive metal, and for example also does not react with the liquid electropositive metal. For example, the container may be formed as a tank or as a powder-holding container.

Correspondingly, according to certain embodiments, the material of the second feeding device for electropositive metal and possibly the first nozzle and/or the first feeding device after the mixing of the carrier gas and electropositive metal and/or the burner may also consist of such a material. A suitable material comprises for example iron, chromium, nickel, niobium, tantalum, molybdenum, tungsten, zircaloy and alloys of these metals, and also steels such as high-grade steel and chromium-nickel steel.

According to certain embodiments, the first nozzle is formed as a Venturi nozzle comprising a piece initially tapering in the direction of flow of the carrier gas, a piece of a constant diameter and a piece with a widening diameter, the second feeding device for electropositive metal preferably being fitted on the constant piece of the Venturi nozzle.

According to certain embodiments, the first nozzle may be formed as a Laval nozzle comprising a piece tapering in the direction of flow of the carrier gas and a piece diverging in the direction of flow. According to certain embodiments, here the second feeding device for electropositive metal is fitted in the region of the smallest diameter of the Laval nozzle.

Furthermore, according to certain embodiments, the second feeding device for electropositive metal may be arranged, preferably coaxially, within the first feeding device for carrier gas in such a way that the outlet opening of the second feeding device for electropositive metal is arranged, preferably coaxially, within the first nozzle in the region of the converging part of the first nozzle. Here, the carrier gas therefore flows around the second feeding device and then sucks the electropositive metal in the first nozzle out of the second feeding device. The suction effect can be intensified here by the coaxial arrangement.

According to further certain embodiments, the first feeding device for carrier gas is arranged in such a way that the carrier gas is fed to the first nozzle, preferably coaxially, within the second feeding device for the electropositive metal in the region of a, preferably converging, part of the second feeding device. Here, the electropositive metal is sucked into the first nozzle around the carrier gas, in a way similar to in the case of a jet pump. An improved suction effect can likewise be achieved here by the coaxial arrangement.

In a jet pump, the pumping effect can generally be produced by a fluid jet (“drive medium”), which by momentum exchange sucks in another medium (“suction medium”), accelerates it and compresses/delivers it, as long as it is under sufficient pressure. Since this type of pump is of a very simple construction and has no moving parts, like Venturi or Laval nozzles or generally nozzles with a tapering portion, it is particularly robust and low-maintenance and versatile in use.

In a typical setup of a jet pump, the delivery may take place for example according to the following steps and, with a few simplifications, can be calculated quite well just by applying laws of energy, momentum and mass conservation:

1. The carrier gas leaves the drive nozzle, which corresponds to the first nozzle, at the highest possible speed. According to Bernoulli's law, this is accompanied by a dynamic drop in pressure, so that the pressure in the flow is lower than normal pressure. The first nozzle may be designed to maximize the speed of the Laval nozzle and the drive jet, that is to say the carrier gas, leaves at supersonic speed.

2. In a mixing chamber that is possibly present within the second feeding device, or in the second feeding device itself, the carrier gas can impinge on the electropositive metal located there, which may be under normal pressure or increased pressure. After leaving the first nozzle, the carrier gas initially behaves like a free jet, and internal friction and turbulences cause a shear stress in the boundary layer between the rapid carrier gas and the much slower electropositive metal. This stress brings about a transfer of momentum, i.e. the electropositive metal is accelerated and entrained. The mixing does not take place here on the principle of conservation of energy, but on the basis of conservation of momentum, that is to say that, because of impact losses, the application of the Bernoulli equation may lead to incorrect results here. Expansion of the carrier gas and the suction intake of the electropositive metal have the effect of slowing down the carrier gas.

3. The acceleration of the electropositive metal also causes a drop in pressure for the electropositive metal on the basis of the Bernoulli principle, so that electropositive metal can be replenished through the second feeding device, a sufficiently high minimum pressure preferably being available for the electropositive metal.

According to certain embodiments, the device according to the invention may also comprise a third feeding device for electropositive metal to the container, which is designed to feed electropositive metal to the container, and a controlling device for the amount of electropositive metal in the container, which is designed to control the amount of electropositive metal fed to the container, and/or comprise a line, which connects the first feeding device for carrier gas to the container upstream of the first nozzle in the direction of flow in such a way that the pressure of the carrier gas controls the amount of electropositive metal fed to the first nozzle, and/or a fourth feeding device for inert gas to the container, which is designed to feed inert gas to the container, and a controlling device for the pressure of the fed inert gas, which controls the pressure of the inert gas fed to the container. The third feeding device for electropositive metal is not restricted according to the invention and may be made in the same way as the second feeding device for electropositive metal, specifically with regard to the material used, but may also be different from it, for example with regard to the form and/or the cross section. The controlling device for the amount of electropositive metal in the container may also consist of the material of the second feeding device for electropositive metal, at least in the region in which it comes into contact with the electropositive metal, but is not particularly restricted. The line that connects the first feeding device for carrier gas to the container, the fourth feeding device for inert gas to the container, and/or the controlling device for the pressure of the fed inert gas are similarly not particularly restricted and can be suitably determined. The line and/or the fourth feeding device may be made here in a way similar to or the same as the first feeding device, it also being possible for it to be different from it, for example with regard to the cross section, etc.

When using a line that connects the first feeding device for carrier gas to the container upstream of the first nozzle in the direction of flow in such a way that the pressure of the carrier gas controls the amount of electropositive metal fed to the first nozzle, a flow controller, mass controller or the like may also be provided in the first feeding device and/or the line.

In addition, the device according to the invention may comprise heating devices, for example for melting the electropositive metal, cooling devices, for example for the burner, pumps, for example for the carrier gas and/or the combustion gas, etc.

If it serves a useful purpose, the above embodiments, configurations and developments can be combined with one another in any way desired. Further possible configurations, developments and implementations of the invention also comprise not explicitly mentioned combinations of features of the invention that are described above or below with respect to the exemplary embodiments. In particular, a person skilled in the art will also add individual aspects to the respective basic form of the present invention as improvements or additions.

The invention is now described on the basis of embodiments given by way of example, which in no way restrict the invention.

A first embodiment given by way of example is represented in FIG. 2. In this, at the constriction of a first nozzle 1, to which a carrier gas is fed through a first feeding device 1′, there is a branch, which leads to the outlet of a container 3 with a metal melt of an electropositive metal/with an electropositive metal M, such as for example lithium, as represented in FIG. 2 and FIG. 3. From the container 3, the electropositive metal M is passed through the outlet 2″ of the container to the second feeding device and through the feeding device 2′ to the first nozzle 1. Furthermore, the inlet of the container 3 is connected to the greater diameter of the first nozzle 1, which is configured here as a Venturi nozzle, through a line 6, so that in principle the same pressure prevails in the container 3 as at the nozzle inlet. If then, for example, a carrier gas, such as for example carbon dioxide, at the pressure p₁ flows through the first nozzle 1, and consequently produces a lower pressure p₂ in relation to p₁ at the constriction, a negative pressure is produced at the outlet of the container 3 as a result of the relationship p₁>p₂, and the liquid metal M is sucked out of the container 3 to the constriction. The carrier gas accelerated there entrains the metal M in the direction of flow and finally atomizes it at the outlet of the nozzle 1 toward the burner 4. For the metal combustion, the reaction gas, such as in the present case carbon dioxide, is preferably used directly as the carrier gas. Depending on the temperature and mixture at the nozzle outlet, the metal spray is self-igniting or still requires an external source of ignition. The atomization of the metal M with the carrier gas is represented in FIG. 3.

The pressure ratio of p₁ to p₂ thereby determines the volumetric flow of the metal melt M out of the container 3. If it is intended that this should be independently controllable, the pressure in the container or the inflow of inert gas into the container may be set externally by way of a separate controller, for example in the form of a pressure controller or a mass flow controller.

A second embodiment given by way of example is represented in FIGS. 4 and 5. FIGS. 4 and 5 show a possible setup for the atomization of liquid, electropositive metal M, for example lithium, with the first nozzle 1 as a Venturi nozzle and an internal mixing of the carrier gas, for example carbon dioxide, and liquid metal M, as in the first embodiment given by way of example, the pressure p₃ in the container 3 instead being controlled by the line 6 with a fourth feeding device 7 for inert gas to the container and a controlling device 7′ for the pressure of the fed inert gas. FIG. 4 shows here the assignment of the pressures and components, and FIG. 5 shows the state of the device during the liquid metal atomization and combustion.

A third embodiment given by way of example, with an alternative to the use of a Venturi nozzle, is represented in FIGS. 6 and 7, according to which a Laval nozzle is used as the first nozzle 1. The pressure setting in the container 3 takes place in the same way as in the second embodiment given by way of example. The feeding of the electropositive metal M, for example lithium in the liquid state, from the container 3 takes place through the second feeding device 2′ coaxially within the first nozzle 1, whereby the electropositive metal M is sucked in by the flow of the carrier gas, for example nitrogen. FIG. 6 shows here the assignment of the pressures and components, and FIG. 7 shows the device during the liquid metal atomization and combustion. The combustion once again takes place in the same way as in the first embodiment given by way of example.

FIG. 8 shows in a fourth embodiment given by way of example an alternative for controlling the pressure p₃ in the container 3, the device otherwise corresponding to the second embodiment. For controlling the inflow of the metal melt M through the second feeding device 2′, here too its hydrostatic pressure p₃ at the outlet 2″ of the container 3 can be used. This pressure can be set by way of the filling level h of the metal melt M in the container 3. The container itself 3 is in this case kept at atmospheric pressure p₀.

By way of a third feeding device 5 for electropositive metal M to the container 3 and a controlling device 5′ for the amount of electropositive metal M in the container 3, electropositive metal M can be fed to the container 3 in such a way that the filling level h is constant or is adjusted within desired hystereses.

If the first nozzle 1 is used as a combustion nozzle, the desired combustion gas may be used as the carrier gas, which is introduced into the pipe at the pressure p₁. Depending on whether external mixing or internal mixing is then required during the atomizing, a nozzle setup as for example in FIGS. 2 to 8, for internal mixing, or as in FIGS. 9 and 10, according to a fifth embodiment given by way of example for external mixing, is used.

In the fifth embodiment given by way of example, the mixing of the carrier gas, here by way of example in the form of the combustion gas carbon dioxide, and the electropositive metal M, for example a lithium melt, takes place outside the first nozzle 1 at the burner 4. Apart from the different nozzle form of the first nozzle 1, this embodiment corresponds to the third embodiment given by way of example. FIG. 9 shows the assignment of the pressures and components, and FIG. 10 shows the liquid metal atomization and combustion.

A sixth embodiment given by way of example is represented in FIGS. 11 and 12, an embodiment in which, as a variant, the atomization of electropositive metal M, for example lithium, takes place by vacuum generation on the principle of the jet pump. Here, the pumping effect is produced by the flow of the carrier gas (drive medium), which by momentum exchange sucks in the melt of the electropositive metal M/alkali metal melt (suction medium), accelerates it and delivers it. FIG. 11 shows here the assignment of the pressures and components, and FIG. 12 shows the liquid metal atomization and combustion. The feeding of the carrier gas, for example carbon dioxide or nitrogen, takes place through the first feeding device 1′ and the first nozzle 1, which takes place coaxially within the second feeding device 2′ in a second nozzle 2. The further setup of the device once again resembles that of the fifth embodiment given by way of example, the combustion in the burner 4 taking place at the outlet of the second nozzle 2.

In the above embodiments given by way of example, a melt of an electropositive metal is always atomized as an example. It is however also possible in the embodiments given by way of example to use instead of the melt a powder comprising particles of the electropositive metal. An electropositive metal M other than lithium may also be used, and the carrier gas may also be a gas other than nitrogen or carbon dioxide. It is also not ruled out that the burner 4 is fed combustion gas, possibly additional combustion gas (in principle even exhaust gas—entirely or partially combusted—from a plant for the burning of fossil fuels).

In the present notification of invention, a description is given of a method for the atomization and combustion of electropositive metals that can by virtue of the choice of special nozzle geometries, and the resultant suction effect of the carrier gas, work without pumps, for example liquid metal pumps. Furthermore, an easy and precise flow control of the electropositive metal can at the same time be realized, specifically in the case of liquid metal melts, by means of the gas inflow into the container for the electropositive metal.

Claims

1. A method for the combustion of an electropositive metal selected from the group consisting of alkali metals, alkaline earth metals, aluminum, zinc, and alloys or mixtures thereof with a combustion gas, the method comprising:

providing the electropositive metal in a container in the form of a liquid or powder comprising particles with a particle size of less than 100 μm;

flowing a carrier gas through a first nozzle communicatively coupled to the container via a first passage that meets the first nozzle at a first location along a flow direction of the first nozzle, the first nozzle having a tapered nozzle portion having a tapered cross section and located at least partially upstream of the first location at which the first passage meets the first nozzle;

sucking the electropositive metal from the container and into the first nozzle via the first passage;

wherein the electropositive metal sucked into the first nozzle is atomized in the first nozzle and burned with the combustion gas.

2. The method of claim 1, wherein the first nozzle is a Venturi nozzle including, in order along the flow direction of the carrier gas, the tapered portion, a constant diameter portion, and a widening portion having a widening cross section,

wherein the first passage from the container opens into the constant diameter portion of the Venturi nozzle.

3. The method of claim 1, wherein the first nozzle comprises a Laval nozzle including the tapered portion that tapers along the flow direction and a diverging portion that diverges along the flow direction.

4. The method of claim 3, wherein the first passage from the container opens into the Laval nozzle at a location of the Laval nozzle having a smallest cross-section.

5. The method of claim 1, wherein the first passage from the container opens into the first nozzle via an outlet opening arranged coaxially within the first nozzle at a location in or downstream of the tapered portion of the first nozzle.

6. The method of claim 1, wherein the first nozzle is being arranged coaxially within the first passage from the container.

7. The method of claim 1, wherein the carrier gas is the combustion gas.

8. The method of claim 1, comprising controlling an amount of atomized electropositive sucked into the first nozzle by controlling a pressure of the carrier gas upstream of the first nozzle along the flow direction of the carrier gas.

9. A device for burning an electropositive metal selected from the group consisting of alkali metals, alkaline earth metals, aluminum, zinc, and alloys or mixtures thereof with a combustion gas, the device comprising:

a first nozzle having a tapered portion with a tapered cross section, the first nozzle configured to carry a flow of a carrier gas and to atomize electropositive metal with the carrier gas,

a first feeding device configured to feed carrier gas to the first nozzle,

a container configured to provide the electropositive metal in the form of a liquid or in the form of a powder comprising particles with a particle size of less than 100 μm,

a second feeding device configured to direct the electropositive metal out of the container to the first nozzle, and

a burner configured to burn the electropositive metal with the combustion gas.

10. The device of claim 9, wherein the first nozzle comprises a Venturi nozzle including, in order along the flow direction of the carrier gas, the tapered portion, constant diameter portion, and a widening portion having a widening diameter, wherein the first passage from the container opens into the constant diameter portion of the Venturi nozzle.

11. The device of claim 9, wherein the first nozzle comprises a Laval nozzle including the tapered portion and a diverging portion that diverges along the flow direction.

12. The device of claim 11, wherein the second feeding device opens into the Laval nozzle at a location of the Laval nozzle having a smallest cross-section.

13. The device of claim 9, wherein the second feeding device has an outlet opening arranged coaxially.

14. The device of claim 9, wherein the first feeding device is arranged coaxially within the second feeding device.

15. The device of claim 9, further comprising:

a third feeding device configured to feed electropositive metal to the container, and

a controlling device configured to control the amount of electropositive metal fed to the container by controlling a pressure of the carrier gas upstream of the first nozzle along the flow direction of the carrier gas.