WO2024115325A1

WO2024115325A1 - Dry ice snow-generating device and method for producing dry ice snow

Info

Publication number: WO2024115325A1
Application number: PCT/EP2023/083035
Authority: WO
Inventors: Mario Principe
Original assignee: Mario Principe
Priority date: 2022-12-02
Filing date: 2023-11-24
Publication date: 2024-06-06
Also published as: DE102022132086A1

Abstract

The invention relates to a dry ice snow-generating device (70a), in particular for producing CO2 snow (58a), comprising an expansion unit (10a; 10c) which has a liquid inlet (12a), at least one dry ice snow outlet (14a), at least one gas outlet (20a; 20c), and an expansion chamber (16a; 16c) which is arranged between the liquid inlet (12a) and the dry ice snow outlet (14a) and which has a cross-section (18a) that changes between the liquid inlet (12a) and the dry ice snow outlet (14a), wherein the gas outlet (20a; 20c) is formed separately from the dry ice snow outlet (14a).

Description

Dry ice snow producing device and method for producing dry ice snow

State of the art

The invention relates to a dry ice snow producing device according to the preamble of claim 1 and a method for producing dry ice snow according to claim 16.

Systems have already been proposed that expand liquid CO2 to produce CO2 snow and then pelletize the CO2 snow.

The object of the invention is in particular to provide a generic device with advantageous properties with regard to dry ice snow production, in particular with regard to an advantageous phase separation of a solid and a gaseous phase. The object is achieved according to the invention by the features of patent claims 1 and 16, while advantageous embodiments and further developments of the invention can be taken from the subclaims.

Advantages of the invention

A dry ice snow production device is proposed, in particular for producing CO2 snow, with an expansion unit which has a liquid inlet, at least one dry ice snow outlet, at least one gas outlet and an expansion space which is arranged between the liquid inlet and the dry ice snow outlet and which is arranged between the liquid inlet and the dry ice snow outlet has a changing cross-section, wherein the gas outlet is formed separately from the dry ice snow outlet.

Such a design makes it possible to provide a particularly efficient device for producing dry ice snow with a particularly efficient phase separation. In particular, a gaseous phase produced in the expansion space can be separated particularly efficiently from a solid phase produced in an operating state. In addition, a simple structural arrangement can be provided. Furthermore, a particularly early phase separation can be achieved in a pelletizing process for producing dry ice pellets. In particular, an efficient phase separation can take place in an uncomplicated manner before a compaction process. Furthermore, dry ice snow with a particularly low residual CO2 gas content can be produced. This can simplify further processing of the dry ice snow produced, in particular compaction and/or processing into dry ice pellets. In particular, an advantageous pressure distribution can be achieved through the variable cross-section.

The dry ice snow generating device is a device for generating dry ice snow by expanding a liquid, in particular liquid CO2. The dry ice snow generating device preferably has at least one connection to a source of liquid CO2. Alternatively, it is conceivable that a dry ice production and processing system which comprises at least the dry ice snow generating device has at least one connection of the dry ice snow generating device to a source of liquid CO2. For example, a pipe connection to an existing, in particular stationary, storage facility for liquid CO2 would be conceivable. Alternatively, it is conceivable that the dry ice production and processing system and/or the dry ice snow generating device comprises a storage unit, in particular at least one storage and/or transport container for liquid CO2. In particular, the liquid CO2 is CO2 liquefied under pressure. Furthermore, the dry ice production and processing system preferably has at least one dry ice snow processing device in which the dry ice snow produced in the dry ice snow production device is further processed, in particular into dry ice pellets. The dry ice snow processing device preferably has at least one extrusion device, which is preferably designed as a screw conveyor, for example as a single or double screw conveyor, for compacting the dry ice snow and at the end of which in particular a matrix for extruding dry ice pellets is arranged.

The expansion unit is a unit which is intended to relax a liquid phase, in particular liquid CO2, by expansion into a mixture of a gaseous phase, in particular gaseous CO2, and a solid phase, in particular CO2 snow, wherein the gaseous and solid phases of the mixture produced are separated in particular in the expansion unit.

The dry ice snow generating device preferably comprises at least one nozzle for injecting a liquefied gas, in particular liquid CO2, into the expansion space of the expansion unit. The liquid inlet is preferably directly adjacent to the nozzle of the dry ice snow generating device, with a minimum distance between the two being in particular a maximum of 10 mm, preferably a maximum of 5 mm and particularly preferably a maximum of 2 mm. Alternatively, it would also be conceivable for there to be a larger distance between the liquid inlet and the nozzle, in particular more than 10 mm, but preferably a maximum of 50 mm. Furthermore, the liquid inlet is preferably designed as an opening with a circular cross-section in the expansion unit, in particular in the form of a bore and/or milling.

The expansion space is preferably at least partially, in particular in a first section, at least substantially truncated cone-shaped. Preferably, a shape of the expansion space differs in a The expansion space is preferably at least substantially cylindrical in shape, at least in sections, in particular in a second section. The shape of the expansion space in a corresponding section preferably deviates from a pure cylindrical shape by a volume proportion of at most 30%, preferably at most 20%, and preferably at most 10%.

The gas outlet is preferably designed as a channel, in particular as a tube. The gas outlet preferably has a length of at least 1 mm, preferably of at least 3 mm and particularly preferably of at least 6 mm. In particular, the length of the gas outlet is at most 50 mm, preferably a maximum of 25 mm and particularly preferably a maximum of 15 mm. The gas outlet serves to discharge a gaseous phase, in particular gaseous CO2, from the expansion space. In particular, the gas outlet runs from the expansion space to an outer surface of the expansion unit. The gas outlet preferably has a circular cross-section and is particularly preferably designed as a bore and/or milling. The gas outlet preferably has a diameter of at least 0.5 mm, preferably of at least 0.75 mm and preferably of at least 1 mm. The diameter is preferably a maximum of 12 mm, preferably a maximum of 6 mm and preferably a maximum of 3 mm. In this context, a “diameter” of the gas outlet, particularly in the case of a non-circular cross-section of the gas outlet, is to be understood as a diameter of the smallest imaginary circle which just completely encloses the cross-section of the gas outlet. This can achieve an advantageous pressure distribution in the gas outlet. In particular, the escape of dry ice snow from the gas outlet can be reduced. Preferably, the gaseous phase of CO2 is at least largely discharged from the expansion chamber only through the gas outlet, whereby dry ice snow with a particularly low proportion of a gaseous phase can be generated. The gas outlet is designed separately from the liquid inlet. Furthermore, the gas outlet is designed separately from the expansion space. The expression "at least to a large extent" is to be understood in particular as at least 55%, advantageously at least 65%, preferably at least 75%, particularly preferably at least 85% and particularly advantageously at least 95% of a volume and/or mass proportion.

The dry ice snow outlet serves to remove dry ice snow from the expansion chamber and is preferably designed as an opening in the expansion unit. Preferably, dry ice snow is only removed from the expansion chamber through the dry ice snow outlet. The dry ice snow outlet is preferably arranged at a second end of the expansion chamber opposite a first end of the expansion chamber at which the liquid inlet is formed. Preferably, the dry ice snow outlet and the liquid inlet are formed at opposite ends of the expansion chamber. Preferably, the dry ice snow outlet is arranged in an installation position and/or an operating state with respect to a direction of gravity below the liquid inlet, whereby the dry ice snow can be transported from its place of production in the expansion chamber, in particular from a region in the expansion chamber near the liquid inlet, to the dry ice snow outlet in a simple manner by means of gravity. The dry ice snow outlet is preferably elongated and particularly preferably bent, curved and/or kinked. Alternatively, it is conceivable that the dry egg white outlet has a different shape that appears to be sensible to the expert. Preferably, the expansion unit has further dry egg white outlets, which are particularly preferably designed identically to one another. Alternatively, it is conceivable that the dry egg white outlets have different shapes from one another.

The expansion unit preferably has an axial direction, which in particular starts from the liquid inlet in the direction of the Dry ice snow outlet. With respect to the axial direction of the expansion unit, the expansion unit preferably has a symmetry, in particular a rotational symmetry. Preferably, components of the expansion unit, in particular the expansion space and/or the liquid inlet and/or the liquid outlet, with respect to the axial direction of the expansion unit, in particular a rotational symmetry. With respect to the axial direction of the expansion unit, the nozzle preferably has a symmetry, in particular a rotational symmetry. Preferably, the axial direction of the expansion unit in an installation position and/or an operating state is parallel to a direction of gravity. The cross section of the expansion space is a surface which is preferably formed perpendicular to the axial direction of the expansion unit.

The term "intended" should be understood as designed and/or equipped. The fact that an object is intended for a specific function should be understood as meaning that the object fulfills and/or carries out this specific function in at least one application and/or operating state.

It is further proposed that the gas outlet is directed from the expansion space in the direction of the liquid inlet. This allows a particularly efficient phase separation to be achieved. In particular, an advantageous spatial separation of the generated gaseous and generated solid phase can be achieved in a simple manner. In particular, leakage of the generated solid phase through the gas outlet can be easily avoided. Preferably, an axial alignment of the gas outlet and/or an average direction of movement of the generated gaseous phase in the gas outlet in an operating state are at least partially opposite to a direction along the axial direction of the expansion unit from the liquid inlet to the dry ice snow outlet and/or an average direction of movement of the dry ice snow in the operating state. Preferably, the axial direction of the gas outlet along the gas outlet from the expansion space points in a direction to an outer surface of the expansion unit. Preferably, the axial direction of the gas outlet coincides with the mean direction of movement of the gaseous phase generated in the gas outlet in the operating state. Preferably, the axial direction of the expansion unit corresponds to the mean direction of movement of the dry ice snow in the operating state. Preferably, an angle between the axial direction of the gas outlet and the axial direction of the expansion unit has a value of more than 90°, preferably of at least 120° and preferably of at least 130°. In particular, the angle between the axial direction of the gas outlet and the axial direction of the expansion unit has a value of less than 180°, preferably of a maximum of 160° and preferably of a maximum of 140°. The angle is particularly preferably 135°. Preferably, the direction of a gas flow in the expansion space in an operating state is deflected by an angle of more than 90°, preferably of at least 120° and preferably of at least 130° in the gas outlet. In particular, the direction of the gas flow in the expansion chamber in the operating state is deflected by an angle of less than 180°, preferably of a maximum of 160° and preferably a maximum of 140° in the gas outlet. The angle is particularly preferably 135°. An average direction of movement of the dry ice snow in the expansion chamber preferably corresponds to an average direction of movement of the entire dry ice snow in the expansion chamber. An average direction of movement of the dry ice snow is preferably parallel to a direction of gravity. Alternatively, it would also be conceivable for the gas outlet to be directed from the expansion chamber in the direction of the dry ice snow outlet, in which case a deflection within the gas outlet would be particularly preferred.

It is further proposed that a cross-sectional area of a cross section of the gas outlet changes from the expansion space to an outer surface of the expansion unit, in particular the above-mentioned outer surface. Preferably, the cross-sectional area increases from the expansion space to an outer surface of the expansion unit. This allows the dry snow generating device to be further optimized. The cross section of the gas outlet is an area which is in particular perpendicular to the axial direction of the Gas outlet is designed. It would be conceivable that the increase occurs continuously at least in sections along the gas outlet. Preferably, however, the increase is staggered. This can advantageously simplify production. Preferably, the gas outlet has a degassing opening and a degassing outlet, which are divided by a staggered, in particular essentially discrete, increase in the cross-sectional area. A "substantially discrete increase" is to be understood in particular as an increase which is completely within a section with a length of a maximum of 20%, preferably at most 10%, particularly preferably a maximum of 5% and particularly advantageously a maximum of 2% of the length of the gas outlet. The degassing opening and the degassing outlet preferably each have a circular cross-section and are particularly preferably designed as a bore and/or milling. Alternatively, it would be conceivable for the cross-section of the degassing opening and/or the degassing outlet to have a different surface shape that appears sensible to the person skilled in the art. The degassing opening and/or the degassing outlet preferably each have a constant cross-sectional area. The degassing opening preferably borders on the expansion space. The degassing outlet preferably borders on the outer surface of the expansion unit and in particular has a larger cross-sectional area than the degassing opening. The degassing opening preferably has a diameter of at least 0.5 mm, preferably of at least 0.75 mm and particularly preferably of at least 1 mm. The diameter is preferably a maximum of 3 mm, preferably a maximum of 2 mm and particularly preferably a maximum of 1.2 mm. The degassing outlet preferably has a diameter which is larger than the diameter of the degassing opening by a factor of one and preferably at most four, in particular exactly two. The degassing opening preferably has a length which at least substantially corresponds to the diameter of the degassing opening, in particular with a deviation of less than 25%, preferably less than 10% and particularly preferably less than 5% from the diameter of the degassing opening. Alternatively, other dimensions would be conceivable, which appear reasonable to the person skilled in the art. It would also be conceivable for the gas outlet to have further, in particular at least essentially discrete, increases. Alternatively, it would be conceivable for the cross section of the gas outlet to have a constant surface size and/or shape along the gas outlet.

It is also proposed that the expansion unit has a plurality of further gas outlets which are distributed over an outer surface of the expansion unit, in particular the above-mentioned outer surface of the expansion unit, and are directed from the expansion space in the direction of the liquid inlet. This advantageously allows a large amount of the gaseous phase formed to be removed from the expansion space of the expansion unit. The further gas outlets can preferably have the same properties mentioned here for the gas outlet. The gas outlets are preferably distributed over the outer surface of the expansion unit in such a way that they each originate from a region in the expansion space near the liquid inlet, from a region in the expansion space near the dry ice snow outlet, and from regions in between. This advantageously allows a large amount of the gaseous phase to be eliminated particularly efficiently from the expansion space of the expansion unit, since the gaseous phase formed from an area of the expansion space near the liquid inlet, as well as the gaseous phase formed from an area of the expansion space near the dry ice snow outlet, as well as any areas in between can be effectively removed from the expansion space by a gas outlet being in close proximity. In particular, the homogeneity of the phase separation can be increased. Preferably, the gas outlets are arranged symmetrically, in particular with respect to the axial direction of the expansion unit, whereby the homogeneity of the phase separation can be further increased. Preferably, a group of gas outlets is arranged one above the other with respect to a direction of gravity, with a first group of gas outlets being connected to a further group of gas outlets with respect to the axial direction of the expansion unit. Preferably, several, in particular four, groups of gas outlets lying one above the other are arranged on a ring around the axial direction of the expansion unit, preferably at a constant distance from one another. This can provide a more efficient and homogeneous elimination of gas from the expansion space, as well as a high structural stability and a simple structural design of the expansion device. Alternatively, it is conceivable that the gas outlets arranged distributed on the outer surface of the expansion unit have further patterns and/or symmetries.

Preferably, the gas outlets are each aligned at the same angle in the direction of the liquid inlet. Alternatively, it is conceivable that the gas outlets are each aligned at a different angle in the direction of the liquid inlet. It is particularly conceivable that a first group of gas outlets is aligned at the same angle in the direction of the liquid inlet, while at least one further group of gas outlets is aligned at a different angle to the first group of gas outlets in the direction of the liquid inlet, wherein the gas outlets in the at least one further group of gas outlets are aligned at the same angle in the direction of the liquid inlet. In particular, it is conceivable that a group of gas outlets which are aligned at the same angle in the direction of the liquid inlet have the same distance from the liquid inlet. Preferably, a different choice of the angles at which the gas outlets are aligned in the direction of the liquid inlet is optimized for the most effective phase separation possible. It could be conceivable that the angle at which the gas outlets are aligned in the direction of the liquid inlet always decreases or always increases with an increasing distance of the respective gas outlet from the liquid inlet or shows a regular or irregular increase and/or decrease.

Furthermore, it is proposed that a total cross-sectional area of the gas outlets from the liquid inlet to the dry ice snow outlet increases. In particular, it is conceivable that a number of the respective gas outlets on the outer surface of the expansion unit and/or a respective cross-sectional area of the individual gas outlets on the outer surface of the expansion unit increase in a direction starting from the liquid inlet to the dry ice snow outlet. This can advantageously provide a particularly efficient and/or more homogeneous elimination of a gaseous phase from the expansion space. In particular, an increase in the volume of the expansion space can be compensated with an increasing total cross-sectional area of the gas outlets starting from the liquid inlet to the dry ice snow outlet. A “total cross-sectional area” is to be understood in particular as a sum of the cross-sectional areas of gas outlets which have a similar distance, in particular an equal distance, to the liquid inlet.

The expansion space advantageously has, at least in sections, an at least substantially circular cross-section. This advantageously makes it possible to provide a particularly efficient and homogeneous elimination of a gaseous phase formed from the expansion space, since, for example, in contrast to a circular cross-section in which part of the gaseous phase is arranged in a region around the center of the circular cross-section and thus has to travel a long distance to the surface of the circle in order to leave the expansion space, the gaseous phase formed has to travel a comparatively short distance to a gas outlet at every point in an expansion space with a circular cross-section, which directly borders a surface of the expansion space. A circular ring of the substantially circular cross-section is delimited in particular by two concentric circles. This advantageously makes it possible to achieve a particularly homogeneous phase separation, in particular a particularly homogeneous elimination of a gaseous phase formed. In particular, the cross-section of the expansion space can be at least substantially circular in a first section and differently shaped in a second section. in particular at least substantially circular. Preferably, the first section with an at least substantially circular cross-section forms at least 60%, preferably at least 70% and preferably at least 80% of the volume of the expansion space. Preferably, the first section is arranged below the second section with respect to a direction of gravity. Preferably, the first section borders on the dry ice snow outlet. Preferably, the second section borders on the nozzle and/or the liquid inlet. Preferably, the at least substantially circular cross-section of the expansion space has a maximum deviation of 20%, preferably of 10% and preferably of 5% from a pure circular ring shape in terms of area proportion. In particular, the circumference of an inner ring and/or an outer ring of the substantially circular ring-shaped cross-section can be uneven, for example due to a structuring on the surface of the expansion space, whereby the substantially circular ring-shaped cross-section deviates from a pure circular ring shape.

In a further embodiment of the invention, it is proposed that a cross-sectional area of the expansion space increases from the liquid inlet to the dry ice snow outlet. This makes it possible to achieve a particularly efficient pressure distribution for the phase separation. For example, the cross-sectional area could increase at least in sections at least substantially linearly. Preferably, the increase has a rate of at least 2 mm ² /mm, in particular of at least 3 mm ² /mm and preferably of at least 4 mm ² /mm. Furthermore, the increase preferably has a rate of at most 15 mm ² /mm, in particular of a maximum of 10 mm ² /mm and preferably of at most 5 mm ² /mm. In this context, “at least substantially” is to be understood in particular as meaning that a deviation from an average rate deviates in particular less than 25%, preferably less than 10% and particularly preferably less than 5% of the average rate. Alternatively and/or additionally, a non-linear increase is possible at least in sections. conceivable. Preferably, the non-linear increase describes a continuously increasing function, which is preferably designed as an exponential function and particularly preferably as a logarithmic function.

It is further proposed that both an outer radius and an inner radius of the annular cross-section of the expansion space increase from the liquid inlet to the dry ice snow outlet, with a difference between the outer radius and the inner radius remaining at least substantially constant, at least in sections. This can advantageously provide efficient elimination of a gaseous phase from the expansion space. In particular, an expansion of a width of the annular cross-section of the expansion space can be avoided, whereby the gaseous phase at every point in the expansion space has to travel a comparatively short distance to a gas outlet which directly borders a surface of the expansion space. Preferably, the difference between the outer radius and the inner radius is at least substantially constant in a first section and assumes a further constant or changing value in a second section. Preferably, the second section is formed above the first section with respect to the direction of gravity. In particular, the circumference of an inner ring and/or an outer ring of the essentially circular cross-section can be uneven, for example due to a structure on the surface of the expansion space, whereby the difference between the outer radius and the inner radius can only be essentially constant. In this context, "at least essentially" is to be understood in particular as meaning that a deviation from an average difference deviates in particular by less than 25%, preferably less than 10% and particularly preferably less than 5% of the average difference.

In a further embodiment of the invention, it is proposed that the expansion unit has an outer body and an inner body formed separately from the outer body, which is at least partially located within the Outer body is arranged, wherein the expansion space is formed between the outer body and the inner body. This advantageously makes it possible to provide a specific shape of the expansion space in a simple structural manner. In particular, a high level of structural flexibility can also be provided. Furthermore, maintenance of the device can advantageously be improved by, for example, simplifying cleaning of the expansion space and/or replacing an inner or outer body in the event of damage. The outer body and the inner body are connected to one another as separately formed components, preferably via a screw connection. This advantageously makes it possible to provide a high level of structural flexibility and a high level of structural stability in a simple manner. Alternatively or additionally, it is conceivable that the connection between the outer body and the inner body is a connection other than a screw connection, for example a positive connection, for example a plug connection or a material connection, in particular a welded and/or soldered connection. Preferably, an axial direction of the inner body and/or an axial direction of the outer body coincide with the axial direction of the expansion unit, whereby a simple construction with a high degree of symmetry can be achieved, which in turn can increase the homogeneity of the phase separation.

It would be conceivable in principle for the gas outlets to be formed only in the inner body. It would also be conceivable for the gas outlets to be formed in the outer body and the inner body. Preferably, however, the gas outlets are formed only in the outer body, whereby a construction can be further simplified. Furthermore, an arrangement of gas outlets can be flexibly changed in a simple manner by exchanging the outer body and/or the inner body.

It is also proposed that the inner body is at least partially conical. This makes it possible to provide a simple construction and advantageous properties with regard to phase separation. Preferably, the at least partially conical region of the inner body has a volume fraction that deviates from a pure conical shape by a maximum of 20%, preferably by a maximum of 15%, and preferably by a maximum of 10%. In particular, the at least partially conical part of the inner body has a cone with a rounded cone tip. Furthermore, the surface of the cone can be uneven, for example due to a structure on the surface of the inner body. Preferably, the cone is designed as a straight circular cone. Preferably, the cone tip is directed in the direction of the liquid inlet. Furthermore, the base of the cone is preferably directed in the direction of the dry ice snow outlet. In this way, an advantageous widening of the expansion space starting from the liquid inlet in a direction toward the dry ice snow outlet can be achieved by a simple construction. In particular, a more advantageous residence time of the dry ice snow on the inner body can be achieved by the dry ice snow resting on the inner body due to friction. Preferably, an axial direction of the cone, in particular of the at least partially conical inner body, corresponds to the axial direction of the expansion unit. This makes it possible to achieve a simple construction with a high degree of symmetry, which in turn can increase the homogeneity of the phase separation.

The outer body advantageously has a truncated cone-shaped recess at least in sections for receiving at least a part of the inner body. This allows a particularly advantageous shape of the expansion space to be achieved in a simple structural manner. The outer body preferably has a truncated cone-shaped recess in a first section and a differently shaped, in particular cylindrical, recess in a second section. The further cylindrical section is preferably formed above the truncated cone-shaped recess of the first section with respect to a direction of gravity and has a radius which corresponds to a radius of an uppermost surface of the truncated cone-shaped recess. The truncated cone-shaped recess preferably corresponds to a shape of a Truncated cone of a right circular cone, the cone tip of which is directed towards the liquid inlet and the base of which is directed towards the dry ice snow outlet. This allows an advantageous widening of the expansion space from the liquid inlet in a direction towards the dry ice snow outlet to be achieved by a simple construction.

In a further embodiment of the invention, it is proposed that a surface of the expansion unit delimiting the expansion space has a structure at least in sections. This makes it possible to achieve particularly advantageous properties with regard to phase separation. In particular, the residence time of the dry ice snow within the expansion space can be increased. Preferably, a surface of the expansion unit delimiting the expansion space comprises at least part of a surface of the inner body, in particular the at least partially conical inner body and/or at least part of an inner surface of the outer body, in particular the at least partially frustoconical recess of the outer body, which delimit the expansion space.

It is conceivable that the structuring only has a microstructure or is designed as a microstructure, for example in the form of a roughness. Such a microstructure can be provided in particular by means of simple and cost-effective manufacturing processes, for example by sandblasting. Alternatively, it is conceivable that the structuring only has a macrostructure and is designed in particular as a macrostructure. This can advantageously increase an interaction between the dry ice snow and the structuring and thus in particular the residence time of the dry ice snow on the surface of the expansion unit.

Advantageously, the structuring has a macrostructuring and is in particular designed as one which is at least partially spiral-shaped, whereby an improved phase separation can be achieved by means of an advantageously simple construction. It is further proposed that the structuring has a macrostructuring which is at least partially helical. As a result, the dry ice snow formed in the expansion space can advantageously collect at the helical macrostructuring and advantageously move in a helical movement following the macrostructuring to the dry ice snow outlet. In particular, the helical macrostructuring can advantageously be constructed in a simple structural manner. Particularly preferably, the macrostructuring is both spiral-shaped and helical. As a result, the dry ice snow formed in the expansion space can advantageously collect at the helical macrostructuring and advantageously move in a particularly advantageous expanding helical movement following the macrostructuring to the dry ice snow outlet. As a result, a capacity for dry ice snow which collects at the macrostructuring advantageously increases starting from the liquid inlet in a direction towards the dry ice snow outlet.

It is also proposed that the structuring be arranged on the inner body. This can improve the position, in particular in relation to the dry ice snow outlet, of dry ice snow collecting in the expansion body. In the case in which the structuring has a macrostructuring, in particular a movement of the dry ice snow collected on the macrostructuring predetermined by the structuring can advantageously lead to the dry ice snow outlet. In particular, in the case in which the gas outlets are only located in the outer body, an accumulation of dry ice snow in the vicinity of a gas outlet, as well as a chance of a gas outlet being blocked by dry ice snow, can be advantageously reduced. Preferably, the structuring is only arranged on the inner body. Preferably, the structuring has a macrostructuring which is designed as a conical spiral on an at least partially conical inner body. Alternatively, it is conceivable that the spiral projected on the conical inner body has a logarithmic, Fermat or has a different floor plan that appears reasonable to the expert. Alternatively, it would be conceivable in principle that the macrostructuring on the inner body has a different shape that appears reasonable to the expert and does not correspond to a spiral floor plan. Alternatively, it would also be conceivable in principle that the structuring on the inner body only has a microstructuring.

Furthermore, a method for producing dry ice snow with the dry ice snow generating device is proposed. This makes it possible to provide a particularly efficient production of dry ice snow with a particularly efficient phase separation. In particular, a gaseous phase that has formed can be particularly advantageously separated from a solid phase that has formed. Preferably, in the method for producing dry ice snow, a liquid, in particular CO2 liquefied under pressure, is first provided, which is introduced into the expansion chamber by means of the liquid inlet. The liquid, in particular the liquid CO2, is then expanded into a solid and a gaseous phase, in particular CO2, preferably by a sudden reduction in pressure in the expansion chamber when injected through the nozzle. In a further method step, the solid and gaseous phases that have formed are preferably separated by removing the gaseous phase from the expansion chamber through the gas outlet. Preferably, the solid phase passes through the expansion chamber and then leaves it in the form of dry ice snow, in particular CO2 snow, through the dry ice snow outlet.

The dry ice snow generating device according to the invention and the method for producing dry ice snow should not be limited to the application and embodiment described above. In particular, the dry ice snow generating device according to the invention and the method for producing dry ice snow can have a number of individual elements, components and units that differs from the number mentioned herein in order to fulfill a function described herein. drawings

Further advantages emerge from the following description of the drawings. The drawings show three embodiments of the invention. The drawings, the description and the claims contain numerous features in combination. The person skilled in the art will also expediently consider the features individually and combine them into further useful combinations.

Show it:

Fig. 1 is a schematic view of a dry ice production and processing system with a dry ice snow production device and a dry ice snow processing device,

Fig. 2 is a sectional view of the dry ice snow generating device with an expansion unit and with a nozzle,

Fig. 3 is a highly simplified 3D exploded view of the expansion unit with separate inner and outer bodies,

Fig. 4 is a sectional view of the expansion unit along a line A-A in Figure 2,

Fig. 5 is a flow chart of a process for producing dry ice snow,

Fig. 6 shows an alternative embodiment of a dry ice snow generating device and

Fig. 7 shows another alternative embodiment of a dry ice snow generating device. Description of the embodiments

Fig. 1 a shows a dry ice production and processing system 50a for producing dry ice pellets in a schematic representation. The dry ice production and processing system 50a comprises a dry ice snow production device 70a for producing CO2 snow 58a (see Fig. 2). The dry ice production and processing system 50a has a dry ice snow further processing device in the form of an extrusion device 60a. In an operating state, the CO2 snow 58a produced in the dry ice snow production device 70a is compressed by the extrusion device 60a and formed into dry ice pellets by extrusion through a matrix (not shown). Fig. 1 b shows that the extrusion device 60a has a twin-screw conveyor. The twin-screw conveyor has a conveyor screw 62a and another conveyor screw 64a. Alternatively, it would be conceivable for the extrusion device 60a to have a single screw conveyor with only one conveyor screw 62a.

Fig. 2 shows a side sectional view of the dry ice snow generating device 70a. An axial direction 42a of an expansion unit 10a of the dry ice snow generating device 70a lies in the plane of the drawing. The dry ice snow generating device 70a comprises a nozzle 52a and the expansion unit 10a. The expansion unit 10a has a liquid inlet 12a, a dry ice snow outlet 14a and an expansion space 16a. The axial direction 42a corresponds to a mean direction of movement of the CO2 snow 58a in the expansion space 16a and runs along a direction starting from the liquid inlet 12a to the dry snow outlet 14a. The expansion space 16a is arranged between the liquid inlet 12a and the dry ice snow outlet 14a. The expansion chamber 16a is adjacent to the dry ice snow outlet 14a. The CO2 snow 58a produced in the expansion chamber 16a is transported out of the expansion chamber 16a through the dry ice snow outlet 14a. The liquid inlet 12a is directly adjacent to the nozzle 52a. In the operating state, liquid CÜ2 54a is provided in the expansion chamber 16a, which is injected into the expansion chamber 16a through the nozzle 52a. The dry ice snow outlet 14a is arranged below the liquid inlet 12a with respect to a direction of gravity 68a.

The expansion unit 10a has a gas outlet 20a, which is designed separately from the dry ice snow outlet 14a. In the operating state, CO2 gas 56a is conveyed from the expansion space 16a through the gas outlet 20a. The gas outlet 20a is directed from the expansion space 16a in the direction of the liquid inlet 12a. An axial direction 48a of the gas outlet 20a and the axial direction 42a of the expansion unit 10a enclose an angle B of 135°. The axial direction 48a of the gas outlet 20a corresponds to a mean direction of movement of the CO2 gas 56a in the gas outlet 20a and runs along a direction starting from the expansion space 16a to an outer surface 22a of the expansion unit 10a.

The dry ice snow generating device 70a has further gas outlets 30a, which are designed separately from the dry ice snow outlet 14a. In the present case, the dry ice snow generating device has exactly 16 gas outlets 20a, 30a, although any number is conceivable in alternative embodiments. The further gas outlets 30a are also directed from the expansion space 16a in the direction of the liquid inlet 12a. In the present case, each axial direction of the respective gas outlets 20a, 30a and the axial direction 42a of the expansion unit 10a encloses an angle B of 135°. Alternatively, the gas outlets 20a, 30a can also assume different angles. The gas outlets 20a, 30a border the expansion space 16a and run from there to a surface area on an outer surface 22a of the expansion unit 10a. In the present case, four gas outlets 20a, 30a of the 16 gas outlets 20a, 30a are arranged one above the other with respect to the direction of gravity 68a. The four gas outlets 20a, 30a arranged one above the other are arranged at an angle of 90° to a nearest group of four superimposed gas outlets on a ring around the axial direction 42a of the expansion unit 10a.

Furthermore, a total cross-sectional area of the gas outlets 20a, 30a increases from the liquid inlet 12a to the dry ice snow outlet 14a. In the present case, a diameter of the gas outlets 20a, 30a increases from the liquid inlet 12a to the dry ice snow outlet 14a. Alternatively or additionally, a number of gas outlets 20a, 30a can also increase from the liquid inlet 12a to the dry ice snow outlet 14a, whereby the gas outlets 20a, 30a can also have the same diameter as one another.

The expansion space 16a has a changing cross-section 18a between the liquid inlet 12a and the dry ice snow outlet 14a. The cross-sectional area of the cross-section 18a increases from the liquid inlet 12a to the dry ice snow outlet 14a. In a section 72a close to the liquid inlet 12a, the cross-section 18a of the expansion space 16a is circular. The cross-section 18a is at least partially annular in a section 74a (see Figure 4). The section 74a is formed below the section 72a with respect to a direction of gravity 68a.

Fig. 3 shows a highly simplified three-dimensional exploded view of the expansion unit 10a, in which in particular the gas outlets 20a, 30a are not shown for the sake of clarity. Figure 4 shows a section of the expansion space 16a along a line A-A in Figure 2.

The circular cross-section 18a of the expansion space 16a has an outer radius 24a and an inner radius 26a, both of which increase in a direction from the liquid inlet 12a to the dry ice snow outlet 14a (see Figure 2). A difference between the outer radius 24a and the inner radius 26a remains constant in sections. In the section 74a, the difference between the outer radius 24a and the inner radius 26a decreases in the vicinity of the liquid inlet 12a. In a section below In the section 74a, the difference between the outer radius 24a and the inner radius 26a is constant. This section forms a large part of the volume of the expansion space 16a. In this section, an increase in the outer radius 24a and the inner radius 26a is linear.

The expansion unit 10a has an outer body 32a and an inner body 34a formed separately from the outer body 32a. Fig. 3 clearly shows the outer body 32a and the inner body 34a being brought together during assembly of the expansion unit 10a.

The inner body 34a is arranged inside the outer body 32a. The expansion space 16a is formed between the outer body 32a and the inner body 34a. The outer body 32a and the inner body 34a are firmly connected to one another in an assembled state by a screw connection. Fig. 2 shows an axial direction 44a of the inner body 34a. The axial direction 44a of the inner body 34a corresponds to the direction of gravity 68a. The axial direction 44a of the inner body 34a corresponds to the axial direction 42a of the expansion unit 10a. The axial direction 42a of the inner body 34a corresponds to an axial direction 46a of the outer body 32a. The gas outlets 20a, 30a are formed in the outer body 32a. The liquid inlet 12a is formed in the outer body 32a. The dry ice snow outlet 14a is formed jointly by the outer body 32a and the inner body 34a.

The inner body 34a is partially conical. The inner body 34a has a cone with a rounded cone tip. Furthermore, the cone has a section 76a immediately above a cone base of the cone, in which the cone shell runs in a curved manner and does not increase linearly outwards in a direction of the cone base. In the present case, the cone is designed as a straight circular cone. The cone tip is directed in a direction of the liquid inlet 12a. Furthermore, the cone base is directed in the direction of the dry ice snow outlet 14a. A cross-sectional area of the cross section 66a of the partially conical inner body 34a takes up from the liquid inlet 12a in a direction towards the dry ice snow outlet 14a. Furthermore, the cross-sectional area 66a of the partially conical inner body 34a increases together with a cross-sectional area of the annular cross section 18a.

The outer body 32a has a recess 28a that is partially frustoconical. In the assembled state, the inner body 34a is partially accommodated in this recess 28a. The outer body 32a has a frustoconical recess 80a in the section 74a. In the section 72a, the outer body 32a has a cylindrical recess 78a. The outer body 32a has the section 76a in which a cross section of a further recess 82a has a trapezoidal shape. The second cylindrical section 72a is formed in an operating state with respect to a direction of gravity 68a above the frustoconical recess 80a of the first section 74a. The second cylindrical section 72a has a radius that corresponds to a radius of an uppermost surface of the frustoconical recess 80a. In an operating state, the third section 76a is formed below the frustoconical recess 80a of the first section 74a with respect to a direction of gravity 68a. The frustoconical recess 80a of the first section 74a corresponds to a shape of a frustum of a right circular cone, the cone tip of which is directed in the direction of the liquid inlet 12a and the base of which is directed in the direction of the dry ice snow outlet 14a.

A surface 36a (not shown) of the expansion unit 10a delimiting the expansion space 16a is smooth. The partially conical inner body 34a has a smooth surface. The recess 28a, which is partially frustoconical, has a smooth surface.

Figure 5 shows a flow chart of a method according to the invention for producing dry ice snow with the dry ice snow generating device 70a. In a first method step 100, liquid CO2 54a is provided at the liquid inlet 12a. In a second method step 102, the liquid CO2 54a is introduced into the expansion space 16a. Here, the liquid CO2 54a is injected into the expansion chamber 16a by means of the nozzle 52a, which expands suddenly due to a reduction in pressure in the area surrounding the expansion chamber 16a. As a result, the liquid CO2 54a changes into a mixture with a solid and a gaseous phase. In a further process step 104, the mixture produced moves by gravity in the direction of the dry ice snow outlet 14a. Meanwhile, in process step 104, a phase separation of the solid and gaseous phase produced takes place by means of the gas outlets 20a, 30a. As a result, CO2 snow 58a with a particularly low proportion of CO2 gas 56a can be provided at the dry ice snow outlet 14a.

Two further embodiments of the invention are shown in Figures 6 and 7. The following descriptions and the drawings are essentially limited to the differences between the embodiments, whereby with regard to components with the same designation, in particular with regard to components with the same reference numerals, reference can generally also be made to the drawings and/or the description of the other embodiment, in particular Figures 1 to 5. To distinguish the embodiments, the letter a is placed after the reference numerals of the embodiment in Figures 1 to 5. In the embodiments in Figure 6 and Figure 7, the letter "a" is replaced by the letters "b" and "c".

In the further embodiment of Figure 6, a section of a surface 36b of an expansion unit 10b that delimits an expansion space 16b has a structure 38b. This structure 38b has a macrostructure 40b that is spiral-shaped. The macrostructure 40b is also helical. The structure 38b is arranged on an inner body 34b. The structure 38b is a macrostructure 40b in the form of a conical spiral on the partially conical inner body 34b. The macrostructure 40b on the inner body 34b is in the present case designed as a milling in the inner body 34b. Figure 7 shows a part of an expansion unit 10c according to a further embodiment, in which a cross-sectional area of a cross section 84c of a gas outlet 20c changes starting from an expansion space 16c to an outer surface 22c of the expansion unit 10c. This embodiment is a further development of the embodiments a and b. In the present case, the cross-sectional area increases starting from the expansion space 16c to the outer surface 22c of the expansion unit 10c. The cross section 84c is circular and perpendicular to an axial direction 48c of the gas outlet 20c. The cross-sectional area of the cross section 84c increases along the axial direction 48c. The gas outlet 20c has a staggered increase in the cross-sectional area. The gas outlet 20c has an at least substantially discrete increase 90c. Furthermore, further discrete increases and/or continuous increases would be conceivable. Between the increase 90c and the expansion space 16c, the gas outlet 20c is designed as a degassing opening 88c. Between the increase 90c and the outer surface 22c of the expansion unit 10c, the gas outlet 20c is designed as a degassing outlet 86c. A cross section 92c of the degassing opening 88c is circular. A cross section 94c of the degassing outlet 86c is circular and has a larger cross-sectional area than the cross section 92c of the degassing opening 88c. The degassing opening 88c is designed as a bore in the present case. The degassing outlet 86c is designed as a counter bore to the degassing opening 88c. Further gas outlets 30c have the same configuration as mentioned above. The gas outlets 20c, 30c each have a thread 96c. The thread 96c is intended for closing the gas outlets 20c, 30c by means of a screw 98c with a counter thread. The outer surface 22c of the expansion unit 10c is staggered in the present case according to the gas outlets. Alternatively, a flat outer surface 22c without a thread would be conceivable. Reference symbols

10 Expansion unit

12 Fluid inlet

14 Dry ice snow exit

16 Expansion space

18 Cross section

20 Gas outlet

22 External surface of the expansion unit

24 Outer radius

26 Inner radius

28 Recess

30 Additional gas outlet

32 Outer body

34 Inner body

36 Surface

38 Structuring

40 Macrostructuring

42 Axial direction

44 Axial direction

46 Axial direction

48 Axial direction

50 Dry ice production and processing system

52 Nozzle

54 Liquid CO2

56 CO2 gas

58 CO2 snow

60 Extrusion device

62 Conveyor screw

64 Additional screw conveyor

66 Cross section Gravity direction

Dry ice snow generating device

Section

Recess

Cross-section

Degassing outlet

Degassing opening

Increase

Cross-section

Thread

Screw

Process step

Claims

Claims Dry ice snow generating device (70a), in particular for producing CO2 snow (58a), with an expansion unit (10a; 10c) which has a liquid inlet (12a), at least one dry ice snow outlet (14a), at least one gas outlet (20a; 20c) and an expansion space (16a; 16c) which is arranged between the liquid inlet (12a) and the dry ice snow outlet (14a) and which has a changing cross-section (18a) between the liquid inlet (12a) and the dry ice snow outlet (14a), wherein the gas outlet (20a; 20c) is formed separately from the dry ice snow outlet (14a). Dry ice snow generating device (70a) according to claim 1, characterized in that the gas outlet (20a; 20c) is directed from the expansion space (16a; 16c) in the direction of the liquid inlet (12a). Dry ice snow generating device (70a) according to claim 1 or 2, characterized in that the expansion unit (10a; 10c) has a plurality of further gas outlets (30a; 30c) which are arranged distributed over an outer surface (22a; 22c) of the expansion unit (10a; 10c) and are directed from the expansion space (16a; 16c) in the direction of the liquid inlet (12a). 4. Dry ice snow generating device (70a) according to claim 3, characterized in that a total cross-sectional area of the gas outlets (20a; 20c; 30a; 30c) increases from the liquid inlet (12a) to the dry ice snow outlet (14a).

5. Dry ice snow generating device (70a) according to one of the preceding claims, characterized in that the expansion space (16a; 16c) has at least in sections an at least substantially circular cross-section (18a).

6. Dry ice snow generating device (70a) according to one of the preceding claims, characterized in that a cross-sectional area of the expansion space (16a; 16c) increases from the liquid inlet (12a) to the dry ice snow outlet (14a).

7. Dry ice snow generating device (70a) according to claims 5 and 6, characterized in that both an outer radius (24a) and an inner radius (26a) of the annular cross-section (18a) of the expansion space (16a; 16c) increases from the liquid inlet (12a) to the dry ice snow outlet (14a), wherein a difference between the outer radius (24a) and the inner radius (26a) remains at least substantially constant at least in sections.

8. Dry ice snow generating device according to one of the preceding claims, characterized in that a cross-sectional area of a cross section (84c) of the gas outlet (20c) starting from the expansion space (16c) to an outer surface (22c) of the expansion unit (10c) changes, in particular increases. 9. Dry ice snow generating device (70a) according to one of the preceding claims, characterized in that the expansion unit (10a; 10c) has an outer body (32a) and an inner body (34a; 34b) which is formed separately from the outer body (32a) and is arranged at least partially within the outer body (32a), wherein the expansion space (16a; 16c) is formed between the outer body (32a) and the inner body (34a; 34b).

10. Dry ice snow generating device (70a) according to claim 9, characterized in that the inner body (34a; 34b) is at least partially conical.

11. Dry ice snow generating device (70a) according to claim 9 or

10, characterized in that the outer body (32a) has a recess (28a) which is at least partially frustoconical in shape for receiving at least a part of the inner body (34a; 34b).

12. Dry ice snow generating device according to one of the preceding claims, characterized in that a surface (36b) of the expansion unit (10b) delimiting the expansion space (16b) has a structuring (38b) at least in sections.

13. Dry ice snow generating device according to claim 12, characterized in that the structuring (38b) has a macrostructuring (40b) which is at least partially spiral-shaped.

14. Dry ice snow generating device according to claim 12 or 13, characterized in that the structuring (38b) has a macrostructuring (40b) which is at least partially helical. Dry ice snow producing device at least according to claims 9 and 12, characterized in that the structuring (38b) is arranged on the inner body (34b). Method for producing dry ice snow with a dry ice snow producing device (70a) according to one of the preceding claims.