Device for cooling of fluids and edible foams

Abstract

The invention pertains to a device for the cooling of edible foams, where a cooling or freezing system for pre-freezing of the foam is directly outlet-connected to an aeration system, a motor driven extruder device designed as combined deep freezing and transport device is outlet-connected to the cooling and freezing system, in which the pre-frozen foam can be cooled down to storage temperature, and the aeration device, the cooling or freezing system and the extruder device are connected together by means of pipes. The device of the present invention is characterized in that the extruder device has at least one double screw system with two screws positioned parallel to each other with their rotational axes. The lands of the screws of the double screw system scrape against the inner cylinder mantle surface of the housing surrounding it. The threads of the second screw are centered between the threads of the first screw and an increased spacing of the rotational axes of the screws is created, so that the front side of the screw thread of the other screw facing the surface of the cylinder mantle of each screw, has a radial distance from it. The lands of the screws with the surface of the cylinder mantle of the screws and of the inner surface of the cylinder mantle of the housing bounds bound an extremely flat screw channel.

Description

BACKGROUND OF THE PRESENT INVENTION

In wide areas of the foods industry, foams are used for the production of foods and/or luxury foods. These foams have in the first place, the advantage that they increase the enjoyment value of the particular product, and secondly, the volume will be increased by beating in some air.

Two classical examples of these food foams are whipped cream and ice cream. The volume of both products is increased to about double by the incorporation of air. The fine distribution of the air bubbles is an essential quality criterion both for ice cream as well as for whipped cream. In both the aforementioned products, it is only this incorporation of air which makes the product suitable for consumption:

In whipped cream, the high fat content would essentially prohibit the product's consumption in its original liquid form.

In ice cream, the incorporation of air results in the ice cream attaining a creamy consistency; without the incorporation of air, it is merely a solid-frozen block.

The technologies for continuous aeration (incorporation of air) in whipped cream and ice cream manufacturing are known around the world. The technologies for whipped cream and ice cream do, indeed, differ from one another significantly, but their basic principle is nonetheless the same.

The distribution of deep-frozen products, and thus the sales of such, have more than doubled in recent down59a Cylinder mantle surface, inner 60 Refrigerant 61 Refrigerant channel 62 Coolant 63 Shaft end 64 Rotary mechanical seal, gas-tight 65 Container 66 Screw hollow shaft as refrigerant channel (possibly also heating medium for thawing) Md₁ Torque on shaft 23 Md₂ Torque on shaft 39 Md₃ Torque on shaft 46 n₁ Speed of shaft 23 n₂ Speed of shaft 39 n₃ Speed of shaft 46 P_g Pressure of carrier gas fed in pipe 28 P_L Gas pressure Pm₁ Pressure in pipe nozzle 30 Pm₂ Pressure in nozzle 40 Pm₃ Pressure in nozzle 48 Tm₁ Temperature in tbe infeed line 26 Tm₂ Temperature in the pipe nozzle 30 Tm₃ Temperature in the nozzle 40 Tm₄ Temperature in the nozzle 48 Tm₅ Temperature at the thermocouple 49 Tm₆ Temperature at the thermocouple 50 Tm₇ Temperature at the thermocouple 51 TK₁ Temperature in the refrigerant runoff nozzle 20 TK₂ Temperature in the refrigerant inlet line 19 TK₃ Temperature in the line 37 TK₄ Temperature in the inlet line 35 TK₅ Temperature in the line 45 TK₆ Temperature in the line 44 V_L Volume flow of the fluid at the inlet of line 27 V_g Volume flow of the carrier gas at the inlet of line 28 A Spacing of rotational axis of screws 52 and 53 D Cylinder diameter H Channel height L Axial channel height W Channel width e Land of the screw θ Screw pitch angle p Number of channels (number of slots) P Screw pitch (= p*L) ______________________________________

Claims

1. A device for the cooling of edible foams, comprising:

a cooling system for pre-freezing an edible foam;

an aeration system outlet-connected to said cooling system;

a motor-driven extruder device designed as a combined deep freezing and transport device outlet-connected to said cooling system for cooling pre-frozen edible foam to a storage temperature,

wherein said extruder device has at least one double screw system comprising:

two screws each having a shaft cylinder with a mantle surface on which the threads of the screws are disposed, said screws being positioned parallel to each other with their rotational axes and being further positioned such that the threads of the second screw are centered between the threads of the first screw and an increased spacing of the rotational axes of the screws is created, such that the front side of the screw thread of the other screw facing the surface of the cylinder mantle of each screw has a radial distance from it;

a housing enclosing said screws, said housing having an inner mantle surface proximate to said screws,

wherein the threads of said screws are positioned so as to scrape against the inner mantle surface of said housing; and

wherein the threads of the screws with the surface of the cylinder mantle of the screws and of the inner mantle surface of the housing bounds bound an extremely flat screw channel.

2. The device of claim 1, wherein:

a ratio of the channel height to the channel width for each said screw is approximately 0.1; and

a screw pitch angle for each said screw is between approximately 20° and 30°.

3. The device of either of claims 1 or 2, said housing having a plurality of refrigerant channels positioned parallel to the axes of rotation of said screws and positioned at a distance relative to each other.

4. The device of either of claims 1 or 2, wherein the shafts of said screws are substantially hollow.

5. The device of any of claims 1 or 2, wherein said housing is sealed by a gas-tight, rotating mechanical seal.

6. The device of any of claims 1 or 2, further comprising a control unit for controlling the speed of rotation of said screw system, whereby the consistency of the foam is determined by means of an on-line viscosity measurement in such a manner that the mechanical energy dissipated in the material system--that is, mechanical energy converted into heat energy--does not exceed a critical amount.

7. The device of any of claims 1 or 2, further comprising a control unit for controlling the speed of rotation of said screw system specifically according to the formula under consideration of the temperature-related, critical shear stresses for the structural changes for optimum tailoring of mechanical energy input, homogeneous stress on the particular foam, super-critical shear, cooling gradient and freezing process, by means of acquisition of the foam consistency as target parameter, whereby the product consistency is determined by means of an on-line viscosity measurement in such a manner that the mechanical energy dissipated in the material system--that is, mechanical energy converted into heat energy--does not exceed a critical amount.

8. Motor-driven extruder device for freezing and transporting an edible food product comprising in combination: two screws each having a shaft cylinder with a mantle surface on which the threads of the screws are disposed, said screws being positioned parallel to each other with their rotational axes and being further positioned such that the threads of the second screw are located between the threads of the first screw; a housing enclosing said screws, said housing having an inner mantle surface proximate to said screws, wherein the threads of said screws are positioned so as to scrape against the inner mantle surface of said housing, wherein the threads of the screws with the mantle surfaces of the screws and of the inner mantle surface of the housing bound an extremely flat screw channel; and means for cooling the housing to a temperature for freezing the food product that is mixed and conveyed by the screws.9. The device of claim 8 wherein the shafts are provided with additional, inner cooling.10. The device of either of claim 8 or 9 wherein the cooling means comprises a plurality of refrigerant channels positioned parallel to the axes of rotation of said screws and positioned at a distance relative to each other, with a suitable refrigerant fluid flowing through the refrigerant channels.11. The device of claim 9 wherein the shafts of said screws are substantially hollow.12. The device of claim 8 wherein the threads of the second screw are centered between the threads of the first screw and an increased spacing of the rotational axes of the screws is created, such that the front side of the screw thread of the other screw facing the surface of the cylinder mantle of each screw has a radial distance from it.13. The device of claim 8 wherein a screw channel for each screw between the threads of the screw, the inner mantle surface of the housing, and the mantle surface of the screw is extremely flat.14. The device of claim 13 wherein a ratio of the height to the width of the screw channel for each screw is

approximately 0.1.15. The device of claim 14 wherein a screw pitch angle for each screw is between 20° and 30°.16. The device of claim 8 wherein the cooling means comprises a tubular container partly filled with a refrigerant fluid, with the housing located within the tubular container, with the refrigerant fluid flushing the housing.17. The device of claim 8 wherein each of the screws include a shaft end protruding from the housing; and wherein the device further comprises, in combination: a gas-tight rotary mechanical seal for sealing the shaft end to the housing to assure gas preservation in the housing during freezing and transporting

of the edible food product.18. Method for producing a frozen edible food product comprising the steps of: providing an extruder device including two screws each having a shaft cylinder with a mantle surface on which the threads of the screws are disposed, said screws being disposed parallel to each other with their rotational axes, said screws being further positioned such that the threads of the second screw are located between the threads of the first screw, with the extruder device further including a housing enclosing said screws, said housing having an inner mantle surface proximate to said screws, wherein the threads of said screws are positioned so as to scrape against the inner mantle surface of said housing, wherein the threads of the screws with the mantle surfaces of the screws and of the inner mantle surface of the housing bound an extremely flat screw channel; cooling the housing to a temperature for freezing the food product; supplying an edible food product into the housing; and rotating the two screws within the housing while the edible food product is being supplied into the housing for freezing, mixing, and conveying the edible food product.19. The method of claim 18 wherein the supplying step comprises the step of supplying the edible food product in the form of an edible foam into the housing.20. The method of claim 19 wherein the supplying step further comprises the step of cooling the edible foam before supplying to the housing.21. The method of claim 18 further comprising the step of inner cooling the shaft cylinders of the two screws.22. The method of claim 21 wherein the inner cooling step comprises the steps of: providing refrigerant channels in the shaft cylinders of the two screws; and flowing a refrigerant fluid through the refrigerant channels.23. The method of claim 18 wherein the cooling step comprises the steps of: providing a plurality of refrigerant channels in the housing positioned parallel to the axes of rotation of said screws and positioned at a distance relative to each other; and flowing suitable refrigerant fluid through the refrigerant channels.24. The method of claim 18 wherein the providing step comprises the step of providing the extruder device wherein the threads of the second screw are centered between the threads of the first screw and an increased spacing of the rotational axes of the screws is created, such that the front side of the screw thread of the other screw facing the surface of the cylinder mantle of each screw has a radial distance from it.25. The method of claim 18 wherein the providing step comprises the step of providing the extruder device wherein a screw channel for each screw between the threads of the screw, the inner mantle surface of the housing, and the mantle surface of the screw is extremely flat.26. The method of claim 18 wherein the providing step comprises the step of providing the extruder device wherein a ratio of the height to the width of the screw channel for each screw is approximately 0.1.27. The method of claim 18 wherein the providing step comprises the step of providing the extruder device wherein a screw pitch angle for each screw is between 20° and 30°.28. The method of claim 18 wherein the providing step comprises the step of providing the extruder device wherein each of the screws includes a shaft end protruding from the housing; and wherein the extruder device further includes a gas-tight rotary mechanical seal for sealing the shaft end to the housing to assure gas preservation in the housing during rotation of the two screws.29. The method of claim 18 wherein the cooling step comprises the steps of: providing a tubular container, with the housing located within the tubular container; and filling the tubular container with a refrigerant fluid for flushing the housing.