DEVICE AND METHOD FOR PASTEURIZING AND/OR STERILIZING PARTICULATE MATERIAL

Abstract

A device (10) for pasteurizing and/or sterilizing particulate material. The device (10) includes: an outer housing (40); a material inlet (43); a material outlet (44); a material guide channel (41) for guiding the material through the device (10) to the material outlet (44); at least one electron source (20) for generating an electron beam; and a treatment zone (19), located in the material guide channel (41), for pasteurizing and/or sterilizing while the material is free falling. The device (10) has at least one inner shielding section (51, 52) disposed within the outer housing (40) and enclosing the material guide channel (41) for shielding off radiation produced during treatment. A method for pasteurizing and/or sterilizing particulate material using such a device (10) is also disclosed which includes: a) generating an electron beam, and b) pasteurizing and/or sterilizing the material, while the material is free falling in the treatment zone (19).

Claims

1-15. (canceled)

16. An apparatus for pasteurizing and/or sterilizing particulate material, the apparatus comprising: an outer casing, a material inlet, a material outlet, a material guide channel in which the material can be guided from the material inlet along a material guide direction through the apparatus to the material outlet, at least one electron source arranged within the housing for generating an electron beam, and a treatment zone arranged in the material guide channel in which the material can be pasteurized and/or sterilized by means of the electron beam, wherein the apparatus has at least one inner shielding arranged inside the outer housing and enclosing the material guide channel, and the inner shielding has at least one shielding element for shielding radiation produced during the treatment; wherein the housing has at least one opening which can be closed by at least one closure element associated therewith, and the closure element contains at least one of the shielding elements on an inner side.

17. The apparatus according to claim 16, wherein the material guiding channel has at least one channel section in which the inner shielding encloses in a labyrinth-like manner.

18. The apparatus according to claim 17, wherein the material guide channel contains a material inlet channel in which the material can be guided from the material inlet to the treatment zone, and at least one inner shielding encloses the material inlet channel in a labyrinth-like manner.

19. The apparatus according to claim 17, wherein the material guide channel contains a material outlet channel in which the material can be guided from the treatment zone to the material outlet, and at least one inner shielding encloses the material outlet channel in a labyrinth-like manner.

20. (canceled)

21. The apparatus according to claim 16, wherein at least one shielding includes a static first shielding element and the shielding element of the closure member forms a second shielding element, and the first shielding element and the second shielding element, in a closed position of the closure element in which the closure element closes the opening associated therewith, together enclose the material guide channel.

22. The apparatus according to claim 21, wherein the first shielding element and the second shielding together enclose the material guide channel in a labyrinth-like manner.

23. The apparatus according to claim 16, wherein the shielding elements have a multi-layer structure with at least one inner layer of lead and two outer layers of another material.

24. The apparatus according to claim 16, wherein the material guide channel is delimited by wall elements of which at least one is connected or movably connectable to the housing.

25. The apparatus as claimed in claim 24, wherein the at least one wall element is releasably connected or connectable to the housing.

26. The apparatus as claimed in claim 16, wherein the treatment zone is arranged such that the material can be pasteurized and/or sterilized in a free-falling manner.

27. The apparatus as claimed in claim 16, wherein the inner shielding encloses the material guide along the material guide direction.

28. A method for pasteurizing and/or sterilizing particulate material with an apparatus according to claim 16, in which the method comprises the following steps: a) generating an electron beam by the at least one electron source, and b) pasteurizing and/or sterilizing the material by the electron beam in the treatment zone.

29. The method according to claim 28, wherein the material moves through the treatment zone at a velocity which is in a range from 1 ms to 5 ms.

30. The method according to claim 28, wherein the electrons of the electron beam have an energy which is in a range from 80 keV to 300 keV.

31. The method according to claim 28, wherein the material is exposed to the electron beam for a treatment time ranging from 5 ms to 25 ms.

32. The method according to claim 28, wherein the material is exposed by the electron beam to a radiation dose which is in the range from 1 kGy to 45 kGy.

33. The method according to claim 28, wherein the electron beam in the treatment zone has an average current density which is in the range from 10.sup.15 s.sup.1.Math.cm.sup.2 to 2.77 10.sup.15 s.sup.1.Math.cm.sup.2.

34. The method according to claim 28, wherein the material, in step b), is pasteurized and/or sterilized in a free-falling manner.

35. The method according to claim 28, where the material is selected from the group consisting of: foods, pet food, feed for ruminants, poultry, aquatic animals or pets, or compound feed, or plastic.

Description

[0087] In the following, the invention is explained in more detail by means of an example and several drawings.

[0088] FIG. 1 shows a perspective view of an apparatus according to the invention;

[0089] FIG. 2 shows a front view of the apparatus with the doors open;

[0090] FIG. 3 shows a rear view of the apparatus with the doors open.

[0091] The apparatus 10 shown in FIGS. 1 to 3 is intended for pasteurizing and/or sterilizing particulate material, such as a spice, sesame, almonds or peeled pistachios. The apparatus 10 contains an outer housing 40, a material inlet 43, a material outlet 44 and a material guide channel 41 in which the material can be guided from the material inlet 43 along a material guide direction R through the apparatus 10 to the material outlet 44. Outside the outer housing 40 of the apparatus 10, there is an electric rack 140 with a switch cabinet 141 and two generators 142 for supplying the electron sources 20 described below and a platform 143.

[0092] As shown in FIGS. 2 and 3, the apparatus 10 also contains a dosing apparatus not shown here, with which the material can be dosed onto a first vibration surface 14 which can be excited to oscillate. With the aid of this first vibration surface 14, the throughput of the material can be controlled and a pre-singulation can already take place. Downstream of the first vibration surface 14, the apparatus 10 contains a second vibration surface 11 which can be excited into oscillations, enabling the material to be conveyed further downstream and singulated. Downstream of the vibration surface 11, there is an inclined sliding surface 16. Even further downstream, the apparatus 10 contains a treatment zone 19 where the material is pasteurized and/or sterilized in a free free-falling manner by means of an electron beam generated by two opposite electron sources 20. The apparatus 10 also contains a suction device 25 with which process gas surrounding the material can be extracted downstream of the treatment zone 19. The vibration surfaces 14 and 11 as well as the sliding surface 16 form some of the wall elements that define the material guide channel 41.

[0093] According to the present invention, the apparatus 10 has several internal shieldings 51, 52 arranged inside the outer housing 40 and enclosing the material guide channel 41 along the material guide direction R, with shielding elements 54, 55, 56, 57 which serve to shield the radiation generated during the treatment in the treatment zone 19 and which may consist of lead, for example.

[0094] The material guide channel 41 contains two channel sections 45, 46, in which the inner shieldings 51, 52 enclose it in a labyrinth-like manner, inter alia a material inlet channel 45, in which the material can be guided from the material inlet 43 to the treatment zone 19, and a material outlet channel 46, in which the material can be guided from the treatment zone 19 to the material outlet 44. The inner shielding 51 enclosing the material inlet channel 45 has shielding elements 54 and 55 and the inner shielding 52 enclosing the material outlet channel 46 has shielding elements 56 and 57, as explained in more detail below.

[0095] The outer housing 40 of the apparatus 10 has several openings, namely inter alia a front opening 60 shown in FIG. 2 and a rear opening 61 shown in FIG. 3, the front opening 60 being closable in a closed position by means of a first door 62 and a second door 62 and the rear opening 61 being closable in a closed position by means of a third door 63 and a fourth door 63. At the inner sides 64, the doors 62, 62, 63, 63 contain the shielding elements 55 and 57. The apparatus 10 further contains static shielding elements 54 and 56. In the closed position of the doors 62, 62, 63, 63 shown in FIG. 1, the shielding elements 54, 55, 56, 57 together enclose the material guide channel 41 in a labyrinth-like manner.

[0096] For pasteurizing and/or sterilizing particulate material by means of this apparatus 10 the following steps are carried out:

[0097] By means of the first vibration surface 14, the throughput of the material is controlled and a pre-singulation takes place. On the second vibration surface 11, the material is further conveyed and singulated. An electron beam is generated by the electron sources 20. The freely falling material is then pasteurized and/or sterilized by means of the electron beam in the treatment zone 19.

[0098] In the case of spices, the material moves advantageously at a velocity of 2.5 m/s through the treatment zone 19. This velocity can be adjusted by the length and angle of inclination of the sliding surface 16. The electrons of the electron beam have an energy in the range from 80 keV to 300 keV, for example at 250 keV. In the treatment zone 19, the electron beam has a mean current density which is in the range from 10.sup.15 s.sup.1.Math.cm.sup.2 to 2.77.10.sup.15 s.sup.1.Math.cm.sup.2. The material is exposed to the electron beam for a treatment time which can be in the range from 5 ms to 25 ms, for example 15 ms. the electron beam exposes the material to a radiation dose in the range from 1 kGy to 45 kGy, which may be 12 kGy for example. After pasteurization and/or sterilization in treatment zone 19, the process gas surrounding the material is extracted by means of the extraction apparatus 25 at a preferred extraction velocity of 1 to 1.5 times the velocity of the material during pasteurization and/or sterilization.

[0099] Thanks to the internal shieldings 51, 52, the risks due to the radiation generated during treatment in treatment zone 19 are reduced considerably further than would be possible with only the external housing 40. This means that the materials can also be protected from the potentially harmful radiation inside the apparatus 10, namely away from treatment zone 19. In addition, the surroundings of the apparatus 10, in particular its operator, can be protected even more effectively against possible risks of radiation. With the doors 62, 62, 63, 63 open, many of the components of the apparatus are accessiblein particular a cassette 24 located in the area of treatment zone 19, which holds two protective foils 23 made of titanium through which the electron beam passes.