FLUID STERILIZING PROCESS AND DEVICE

Abstract: A process and device whereby a fluid, even one impervious to ultraviolet rays, is fed along a narrow passage de­ fined by two walls, at least one of which is formed from material transparent to ultraviolet rays, and at least one of which is formed from unwettable material designed to produce, in the fluid flowing along the passage, micro­ vortices substantially equal in diameter to the width of the passage. The particles flowing along the passage are sterilized, as they swirl into substantial contact with the aforementioned transparent wall, by a superficial bom­ bardment of ultraviolet rays produced by at least one source located outside the passage and in front of the aforementioned transparent wall.

Description: The present invention relates to a process for sterilizing fluids. The effective sterilizing action of ultraviolet rays on fluids penetrated by the same is by now a well established fact. As yet, however, this property of ultraviolet rays has generally been employed for sterilizing water or other alimentary fluids. In particular, devices are known for purifying and sterilizing drinks, such as water or similar fluids transparent to ultraviolet rays, on which the drink is fed through at least one vessel or tubular duct. The said duct is defined by a wall at least partly transparent to ultraviolet rays, and is set up in front of at least one source of the same. The ultraviolet rays produced by the said source thus pass through the said transparent wall and the drink, which is also transparent, so as to enable in-depth bombardment and effective sterilization of the drink particles. A major drawback of known purifying-sterilizing devices of the aforementioned type is that they are limited to drinks transparent to ultraviolet rays, and cannot be em­ ployed for fluids, such as syrups, lubricating oils or emulsions, that are impervious to ultraviolet rays and, therefore, usually require a much more expensive steriliz­ ing process. The aim of the present invention is to provide a fluid sterilizing process designed to overcome the aformention­ ed drawback. With this aim in view, according to the present invention, there is provided a fluid sterilizing process, character­ ised by the fact that it comprises stages consisting in: - feeding the particles of a fluid, even one impervious to ultraviolet rays, along a narrow passage defined by two walls, at least one of which is formed from material transparent to ultraviolet rays, and at least one of which is formed from unwettable material designed to produce, in the fluid flowing along the said passage, microvortices substantially equal in diameter to the width of the said passage; - superficially bombarding the said particles with ultra­ violet rays, as the said particles traveling along the said passage swirl into substantial contact with the said transparent wall; the said ultraviolet rays being produced by at least one source located outside the said passage and in front of the said transparent wall. According to the above process, sterilization is achieved, not by the said ultraviolet rays penetrating the fluid, but by means of superficial bombardment, thus substantial­ ly overcoming the functional limitation posed by non-­ transparent fluids. According to the present invention, there is also provided a fluid sterilizing device, even for fluids impervious to ultraviolet rays, characterised by the fact that it comprises duct means for a stream of unsterilized fluid particles, said duct means, in turn, comprising two oppo­ site walls defining a relatively narrow passage, at least one of the said walls being formed, at least partially, from material transparent to ultraviolet rays, and at least one of the said walls being formed from unwettable material; and at least one source of ultraviolet rays, located facing the said transparent wall of the said pass­ age; the width of the said passage being approximately the same size as the diameter of vortices induced in the said stream, in use, by the said unwettable wall. A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawings, in which : Fig.1 shows a section of a preferred embodiment of a fluid sterilizing device in accordance with the teachings of the present invention; Fig.2 shows a section along line II-II in Fig.1. Number 1 in Fig.1 indicates a fluid purifying-sterilizing device, even for fluids impervious to ultraviolet rays, comprising an outer casing 2 preferably formed form metal and in the form of a rectangular parallelepipedon. The said casing 2 comprises a top wall 3, a bottom wall 4, a first pair of parallel side walls 5, and a second pair of parallel side walls 6 (only one of which is shown) perpendicular to walls 5. Inside a chamber 7 defined by the said walls 3, 4, 5 and 6, there is housed a duct 8 for the said unsterilized fluid, which duct 8 may be of any shape, but, in the example shown, is substantially U-shaped with its concave side facing upwards. In more detail, the said duct 8 com­ prises a downward duct 10 and an upward duct 11 parallel with each other, formed from unwettable material transpa­ rent to ultraviolet rays, and connected at their respec­ tive bottom ends by a horizontal duct 12. The top ends of ducts 10 and 11 are engaged inside respective tubular ends of an outlet pipe 13 and inlet pipe 14 respectively, which pipes 13 and 14 extend through respective holes 15 and 16 formed through wall 3, and are connected to the said wall 3 via respective flanges 17 and 18. Each of ducts 10 and 11 houses a tubular element 19 pre­ ferably formed from metal and closed at its opposite ends by plugs 20, each of which is secured to the inner sur­ face of respective duct 10 or 11 by means of radial fins 21. The said tubular elements 19 extend along substantially the entire length of respective ducts 10 and 11 and de­ fine, with the same, respective toroidal passages 22 and 23 along which the unsterilized fluid flows. In the example shown, three fluorescent infrared lamps, 24, 24, 26, are mounted inside the said chamber 7. Lamps 24 and 25 are connected by means of respective end brack­ ets 27 to respective walls 5, in a position adjacent to ducts 10 and 11 respectively, and present respective re­ flecting paraboloids 28 for concentrating the emitted rays on to ducts 10 and 11. Lamp 26, on the other hand, is located midway between ducts 10 and 11, and is support­ ed by end brackets 29 connected to one of walls 6. In actual use, the unsterilized fluid is fed into inlet pipe 14 by a supply network (not shown) and flows along duct 8 by successively flowing along passage 23, duct 12 and passage 22, as far as outlet pipe 13. As it flows along toroidal passages 22 and 23, the un­ sterilized fluid assumes a swirling motion due to the fact that, as ducts 10 and 11 are formed from unwettable mate­ rial, such as TEFLON, the fluid particles substantially contacting the inner surfaces of ducts 10 and 11 encounter substantially no frictional resistance and, therefore, tend to travel faster than the other particles. The size of the vortices formed inside passages 22 and 23 remains substantially constant for a given flow rate. Consequent­ ly, by selecting, for passages 22 and 23, a width approxi­ mately equal to the diameter of the vortices produced at the required flow rate, all the unsterilized fluid par­ ticles may be brought successively into contact with the inner surfaces of ducts 10 and 11, that is, into a posi­ tion enabling the said particles to be sterilized by a superficial bombardment of ultraviolet rays emitted by lamps 24, 25 and 26. To those skilled in the art it will be clear that changes may be made to device 1 as described herein without, how­ ever, departing from the scope of the present invention. For example, according to a first variation (not shown), duct 8 may consist of a coil, or be of any appropriate shape other than the one described herein. Similarly, according to a further variation (not shown), passages 22 and 23 may be flat, instead of toroidal as in the example shown. According to a further variation (not shown), tubular ele­ ments 19 may be formed from material designed to reflect ultraviolet rays, or, they too, from unwettable material transparent to ultraviolet rays. According to a further variation (not shown), the ultravio­ let lamps employed may differ in number and/or be posi­ tioned differently from those described herein. Finally, according to a further variation (not shown), device 1 as described herein may constitute only one ste­ rilizing unit on a system comprising a number of such units connected in various ways and housed either in re­ spective casings 2 or in a single common casing.

Claims: 1) - A fluid sterilizing process, characterised by the fact that it comprises stages consisting in: - feeding the particles of a fluid, even one impervious to ultraviolet rays, along a narrow passage defined by two walls, at least one of which is formed from material transparent to ultraviolet rays, and at least one of which is formed from unwettable material designed to produce, in the fluid flowing along the said passage, microvorti­ ces substantially equal in diameter to the width of the said passage; - superficially bombarding the said particles with ultra­ violet rays, as the said particles traveling along the said passage swirl into substantial contact with the said transparent wall; the said ultraviolet rays being produced by at least one source located outside the said passage and in front of the said transparent wall. 2) - A fluid sterilizing device, even for fluids imper­ vious to ultraviolet rays, characterised by the fact that it comprises duct means for a stream of unsterilized fluid particles, said duct means, in turn, comprising two oppo­ site walls defining a relatively narrow passage, at least one of the said walls being formed, at least partially, from material transparent to ultraviolet rays, and at least one of the said wall being formed from unwettable material; and at least one source of ultraviolet rays, located facing the said transparent wall of the said pass­ age; the width of the said passage being approximately the same size as the diameter of vortices induced in the said stream, in use, by the said unwettable wall. 3) - A device as claimed in Claim 2, characterised by the fact that the said passage is toroidal in shape; the said two walls being tubular and coaxial with each other. 4) - A device as claimed in Claim 3, characterised by the fact that a first outer wall of the said tubular walls is formed from the said unwettable material transparent to ultraviolet rays; the said source of ultraviolet rays being located outside the said outer wall.

Inventors: STRIGLIA SILVIO
Applicants: ULTRAVIOLET TECHNOLOGY ITALIA S.R.L.
Application year: 1987
Main classification: A23L3
IPC codes: C02F1, A23L3, A61L2