Patent Application
20170303555
The presently disclosed subject matter relates to a radiation treatment system, and in particular Dean flow reactor.
Ultraviolet light (UV-C) treatment is one of the nonthermal technologies to kill microorganisms. Photochemical changes in proteins and nucleic acids are responsible for inactivation of microorganisms when UV light is absorbed by the food during the UV treatment process.
Thus, ultraviolet light (UV) holds considerable promise in food processing as an alternative to traditional thermal processing. Its applications include pasteurization of liquid food, such as milk and juices, post lethality treatment for meats, treatment of food contact surfaces and to extend the shelf-life of fresh produce.
The disinfection of high UV transmissible fluids such as water is relatively easy given the high penetration of photons into the matrix. However, with opaque fluids such as milk the penetration of UV photons is limited to the subsurface. Consequently, to facilitate the UV treatment of milk it is necessary to ensure efficient mixing so that each part of the fluid is exposed to UV.
It is generally known to perform UV treatment of milk in reactors including coiled tubes since these provide secondary vortices and can cause superior mixing of fluid flowing through the reactor. One such reactor is disclosed for example in Tucker (U.S. Pat. No. 4,798,702), and it comprises a coil of corrugated pipe wrapped around a germicidal radiation source into the shape of a helix.
Key factors influencing efficiency of UV-C treatment include reactor design, fluid dynamic parameters and UV-C absorbance of liquid food. Turbulent flow of liquid foods in continuous flow UV reactors increases inactivation of microorganisms in fresh juices, wine, liquid egg whites, beer, and milk, process water specialty turbid and unclear water. Reynolds number (Re) is a measure of the ratio of inertial forces to viscous forces for fluid flow in a coiled tube. It is expressed as:
Re=(ρ/μ)×vD (1)
where Re is the Reynolds number, ρ is density of fluid, μ is dynamic viscosity of fluid, D is diameter of tube carrying the fluid, and v is velocity of flow. Laminar flow occurs when Re<2100, whereas Re>4000 indicates turbulent flow. Flow with Re between these numbers is considered transient flow.
The Dean number De is a similarity parameter governing the fluid motion in coiled tube flow configuration:
De=Re√{square root over (D/Dc)} (2)
where D is the tube diameter, Dc is the coil diameter, and Re is the tube Reynolds number. When the flow of a fluid in a coiled tube reactor is accompanied by secondary flow vortices, it is called Dean flow. This occurs when the ratio (D/Dc) in Equation (2) is between 0.03 and 0.1 (Dean, 1927).
As mentioned above, another key factor in fluencing efficiency of UV-C treatment is UV-C absorbance of liquid food, i.e. the effectiveness of UV irradiation, defined by applied intensity and contact time, satisfying:
F=i×t (3)
where i is the intensity of the applied UV light source(s) and t is the time of the exposure of the fluid to the above UV light.
In accordance with one aspect of the presently disclosed subject matter there is provided a radiation treatment unit having an elongated shape and a central longitudinal axis comprising:
The axial length of the spinner may be much less than the length of the pipe (i.e., the length of the fluid path defined thereby). For example, it may be no greater than about 1% of the length of the pipe. According to other examples, it may be no greater than about 1/150th the length of the pipe.
The spinning surfaces may be twisted through substantially 360° between the ends of the spinner.
The spinning surfaces may span between two helical edges.
The helical edges may tightly fit within the inner cylindrical surface of its respective pipe assembly.
The pitch of the spinning surfaces may be substantially constant between the ends of the spinner.
The pitch of the spinning surfaces may decrease along its length.
The spinner may be made of stainless steel.
The parameters of the radiation treatment unit can be such that a radiation doze applied to a first treated fluid during its passage through the first coiled pipe is substantially equal to a radiation doze applied to a second treated fluid during its passage through the second coiled pipe.
The parameters are selected from the group can consist of: intensity of the first radiation source, intensity of the second radiation source, time of exposure to the first radiation source of a fluid passing through the first coiled pipe, time of exposure to the second radiation source of a fluid passing through the second coiled pipe, inner and/or outer diameter of the first coiled pipe, inner and/or outer diameter of the second coiled pipe, outer diameter of a first coil defined by the first coiled pipe, outer diameter of a second coil defined by the second coiled pipe, a flow rate of a fluid passing through the first coiled pipe and a flow rate of a fluid passing through the second coiled pipe.
The radiation treatment unit can further comprise a unit holding assembly configured for supporting the first pipe assembly and the second pipe assembly.
The unit holding assembly can be configured for allowing an axial movement of at least one of the first pipe assembly and the second pipe assembly with respect to the other of the first pipe assembly and the second pipe assembly.
The unit holding assembly can comprise a sliding mechanism allowing the first pipe assembly to slide along the longitudinal axis with respect to the second pipe assembly, allowing thereby an access to the second pipe assembly.
The first support assembly can comprise a couple of first end supports disposed adjacent ends of the radiation treatment unit and a plurality of first rods extending between the first end supports and configured for holding the first coiled pipe.
The first radiation source can be configured to be fixed to the first end supports.
The second support assembly can comprise a couple of second end supports disposed adjacent ends of the radiation treatment unit and a plurality of second rods extending between the second end supports and configured for holding the second coiled pipe.
The second radiation source can be configured to be fixed to the second end supports.
The first and the second radiation sources can be equally spaced from the second coiled pipe.
A single support assembly can serve as both the first support assembly and the second support assembly.
The first and the second coiled pipes can be equally spaced from the first radiation source.
The first coiled pipe can comprise a first smooth inner surface of a diameter DI and a first coil outer cylindrical surface of a diameter Dc1, satisfying the condition 0.03≦DI/Dc1≦0.1.
The first coiled pipe can satisfy the condition DI/Dc1=0.0.3.
The second coiled pipe can comprise a second smooth inner surface of a diameter D2 and a second coil outer cylindrical surface of a diameter Dc2, satisfying the condition 0.03≦D2/Dc2≦0.1.
The second coiled pipe can satisfy the condition D2/Dc2=0.0.5.
The first and the second radiation sources can comprise a plurality of UV lamps.
Each of the lamps can be mounted separately to at least one of the first support assembly and the second support assembly.
The radiation treatment unit can further comprise a separating element configured for receiving electrical cables of the first and the second radiation sources.
In accordance with another aspect of the presently disclosed subject matter there is provided a radiation treatment unit having an elongated shape and a central longitudinal axis, comprising:
In accordance with another aspect of the presently disclosed subject matter there is provided a radiation treatment unit having an elongated shape, the unit comprising:
The pipe may satisfy the condition 0.03≦D/Dc≦0.1, and more particularly D/Dc=0.05 or D/Dc=0.04.
The pipe's inner diameter can be in the range 10.5-12.5 mm, more particularly, in the range of 10.8-11.5 mm, more particularly, in the range of 11-11.2 for 1000 L/H system.
The pipe's inner diameter can be in the range 15.5-19.5 mm, more particularly, in the range of 16.5-17.5 mm, more particularly, in the range of 17-17.2 for 3000 L/H system.
The pipe's inner diameter can be in the range 20.5-23.5 mm, more particularly, in the range of 20.8-21.5 mm, more particularly, in the range of 21-21.2 for 5000 L/H system.
The wall thickness of the pipe can be in the range 0.7-1 mm, more particularly, in the range of 0.8-0.82 mm.
The pipe can be made of Fluoropolymers, and more particularly, from Fluorinated Ethylene Propylene (FEP).
The inner and the outer radiation sources can be spaced from the coil.
The spacing between the coil and the corresponding radiation source can be between 0.5 and 4 cm, more particularly, in the range of 0.8-3 cm, and more particularly, in the range of 1 to 2 cm.
The inner and the outer radiation sources can be equally spaced from the coil.
The inner and the outer radiation sources can comprise a plurality of UV lamps.
Each of the lamps can be mounted separately at the ends of the unit.
At least some of the lamps can have a length in the range of 200-1,700 mm, more specifically in the range of 800-1,600 mm, and more specifically in the range of 1,500-1,600 mm.
At least some of the lamps can have an intensity in the range of 500-1,300 μW/cm2, according to some examples in the range of 720 to 780 μW/cm2, and according to other examples in the range of 1,100 to 1,200 μW/cm2.
The radiation treatment unit can have a central axis extending between two opposite ends of the unit, wherein the sub-systems of the radiation treatment unit are coaxially disposed with respect to the central axis.
The radiation treatment unit can further comprise a unit holding assembly configured for fixedly mounting thereon the sub-systems of the unit.
The unit holding assembly can comprise two end supports and a plurality of outer fixation rods fixedly connected thereto and extending along a longitudinal axis of the system, at a radial distance therefrom greater than that of the radiation sources and the coiled pipe.
The unit holding assembly further can comprise a central fixation rod extending between the end supports and coaxial with the longitudinal axis.
The end supports can receive therein ends of the radiation sources of both the inner and the outer radiation sub-systems.
The unit holding assembly further can comprise an intermediate support disposed between the end supports, the radiation sources passing through corresponding openings in the intermediate support.
The intermediate support can comprise an intermediate lateral support and an intermediate central support, wherein the at least one radiation source of the inner radiation sub-system passes through corresponding to at least one opening in the central support, the at least one outer radiation source passes through corresponding to at least one opening in the intermediate outer support.
The outer rods can pass through corresponding openings in the lateral support and the central rod passes through a corresponding opening in the intermediate support.
The unit holding assembly can further comprise coil pipe supporting brackets projecting radially from the intermediate central support, the brackets having ends optionally received in the end supports.
The coiled pipe can pass through an area between the central and the lateral intermediate supports so that its inner cylindrical surface is in contact with the supporting brackets and its outer cylindrical surface is in contact with the intermediate lateral support.
In accordance with another aspect of the presently disclosed subject matter there is provided a radiation treatment unit having an elongated shape, the unit comprising:
the pipe being provided with a spinner therein, the spinner comprising smoothly twisting spinning surfaces spanning between ends thereof. The spinner may be as described above, mutatis mutandis.
The parameter f can be calculated in accordance with the following equation:
wherein e is absolute roughness of the pipe.
The above calculation of the friction factor f is suitable for coiled pipes, such as the pipe of the presently disclosed subject matter.
In accordance with another aspect of the presently disclosed subject matter there is provided a method for using one or more of the above radiation treatment units, comprising passing through the pipe the fluid to be treated thereby exposing it to the radiation for 20 to 30 seconds.
The exposure time can be in the range of 24-26 seconds, and more specifically 25 seconds.
In accordance with another aspect of the presently disclosed subject matter, there is provided a radiation treatment unit comprising a pipe for passing therethrough a fluid to be treated and disposed so as to be exposed to a radiation source, the pipe comprising a spinner therein, the spinner comprising smoothly twisting spinning surfaces spanning between ends thereof.
The spinning surfaces may be twisted through substantially 360° between the ends of the spinner.
The spinning surfaces may span between two helical edges.
The helical edges may tightly fit within the inner cylindrical surface of its respective pipe assembly.
The pitch of the spinning surfaces may be substantially constant between the ends of the spinner.
The pitch of the spinning surfaces may decrease along its length.
The spinner may be made of stainless steel.
The pipe may be constructed so as to satisfy the Dean ratio.
The radiation source may comprise an ultraviolet light source.
In accordance with another aspect of the presently disclosed subject matter there is provided a radiation treatment system comprising at least one or more of the above radiation treatment units.
In accordance with another aspect of the presently disclosed subject matter there is provided a method for using one or more of the above radiation treatment unit, comprising passing through the pipe the fluid to be treated while exposing it to the radiation intensity within the range of 25-35 mJ/cm2.
In accordance with another aspect of the presently disclosed subject matter there is provided a radiation treatment unit including:
All the above mentioned systems can comprise at least one pipe allowing a flow rate of 1000 liter/hour, and has the following parameters: D/DC=0.05, D=11.1 mm.
All the above mentioned systems can comprise at least one pipe allowing a flow rate of 5000 L liter/hour, and has the following parameters: D/DC=0.04, D=22 mm.
All the above mentioned systems can comprise at least one pipe allowing a flow rate of 15,000 liter/hour, and has the following parameters: D/DC=0.04, D=36 mm.
In accordance with another aspect of the presently disclosed subject matter, there is provided a radiation treatment unit comprising:
The spinning surfaces may be twisted through substantially at least 360° between the ends of the spinner.
The spinning surfaces may span between two helical edges.
The helical edges may tightly fit within the inner cylindrical surface of pipe.
The pitch of the spinning surfaces may be substantially constant between the ends of the spinner.
The pitch of the spinning surfaces may decrease along its length.
The spinner may be made of stainless steel.
The pipe may have a smooth inner surface of a diameter D, the coiled pipe having a coil inner cylindrical surface defining a cylindrical cavity and a coil outer cylindrical surface of a diameter DC, wherein 0.03≦D/DC≦0.1.
The pipe may satisfy the condition D/DC=0.05.
D may be between about 10 mm and about 35 mm.
The pipe may have a linear of between about 1,200 mm and about 1,700 mm.
The pipe may have a wall thickness of between about 0.63 mm and about 1.27 mm.
The pipe may be made of a Fluoropolymer.
The radiation sub-system may comprise at least one radiation source selected from the group including an inner radiation source disposed within the cylindrical cavity and an outer radiation source disposed outside the coil.
The radiation sub-system may comprise the inner radiation source and the outer radiation source.
Each radiation source may extend along the length of the coil.
Each radiation source may comprise one or more ultraviolet lamps.
In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
With reference to
The system 1 comprises a plurality of UV treatment units 10 each mounted within a housing 17, a control board 2, which is in fluid communication with the units 10 by means of a faucet 6, and a mounting stage 4, to which the units 10 and the control board are fixedly mounted.
The system 1 can be connected to a control system for controlling the system operation, and other systems and/or elements generally known in the art, such as pump balance tank, which are not shown and will not be described in the present application.
With reference to
All these sub-systems extend between two opposite ends 11 and 13 (
The elements of each sub-system are described below in detail.
The pipe sub-system 30 comprises a helically coiled pipe 31 (
The pipe is made of a material that is highly resistible to UV radiation, has sufficient UV transmission properties, is resistant to high pressures, is qualified for use in contact with food, has a low coefficient of friction with liquids, is bendable, and is resistible to breakage or flattening. One example for such material is Fluorinated Ethylene Propylene (FEP).
The pipe has inner and outer diameters Din and Dout, and the wall thickness tw. The wall thickness tw of the pipe 31 (
Experiments show that, for example, the wall thickness of 0.81 mm allows the pipe to bear the pressure differences of up to 12 bar, and the inner diameter of the pipe of 11.1 mm allows the flow velocity of 2.8 m/sec.
As shown in
The coil length L (
The number of turns 21 (
In the described example of the system, the coil outer diameter Dc can be in the range of 100-150 mm, and specifically 133 mm, and the inner diameter of the pipe Din and the diameter DC of the coil can be chosen so as to satisfy Dean ratio, as explained above, i.e. 0.03≦Din/DC≦0.1, and specifically 0.04 or 0.05.
A spinner, which is generally indicated at 21 in
It will be appreciated that the term “helical” when used herein the specification and claims in connection with the spinner 21 is not to be limited to shape which meets the strict mathematical definition of a helix. Rather, it is to include any shape which spirals (e.g., corkscrews) about the axis X.
The spinning surfaces 25 are considered to be “smooth” in that they are continuous, i.e., without abrupt changes in direction or angle with respect to the axis X. For example, the spinner 21 may be constructed such that any segment thereof along the axis X is substantially similar to the segments adjacent thereto. Accordingly, fluids which flow about the spinner 21 are imparted with a rotation about axis X, without being subject to unnecessary mixing owing to the geometry of the spinning surfaces 25.
The spinner 21 may be provided such that it is twisted through 360° (i.e., the edges 23 rotate through 360° about axis X) as illustrated in
The spinner 21 may be made of any suitable rigid material. The material may be highly resistible to UV radiation, be qualified for use in contact with food, and have a low coefficient of friction with liquids. It may have high UV transmission properties, but this is not critical as the spinner 21 is only disposed along a small portion of the length of the pipe 31. According to some examples, it is made of the same material as the pipe 31. According to other examples, it is made from stainless steel.
It has been found experimentally that UV treatment of fluids, e.g., such as in a radiation treatment system 1 as described herein comprising spinners 21 as described above is accelerated compared with UV treatment in such a system in which static mixers (having surfaces which are not smooth thereby introducing mixing along their lengths, e.g., abruptly switching direction, comprising two or more helical sections whose ends are adjacent and not aligned with one another) are used, and compared with UV treatment in such a system in which no spinner or mixers are used. It will be appreciated that in this context, an accelerated treatment is one in which fewer colony-forming units of pathogenic and/or spoilage microorganisms remain compared to a baseline treatment (here, those in which a static mixer or no spinner/mixer is used) when all other parameters are held constant.
It will be appreciated that while the spinner 21 is described herein as constituting a part of the disclosed radiation treatment systems, it may be used within a pipe of a radiation treatment system which does not otherwise fall within the scope of the presently disclosed subject matter, mutatis mutandis.
The UV radiation sub-systems 50 and 70 comprise a plurality of UV tube-shaped inner lamps 51 (
All the lamps in accordance with one example of the presently disclosed system have a length in the range of 1,200-1,700 mm, and specifically 1,554 mm (total length) and 1475 (the emitting section) and intensity in the range of 500-1,200 μW/cm2.
The lamps 51 of the inner radiation sub-system 50 are disposed within the coil cylindrical cavity 32 (
The lamps 51 and 71 are fitted within respective supporting sockets 54 (
As further described in detail, each lamp of the sub-systems 50 and 70 is mounted separately to the unit holding assembly 15.
It should be appreciated the inner and outer radiation sub-systems can each have a single radiation source, for example, an elongated cylindrical radiation source having dimensions suitable for being inserted within the coil cylindrical cavity 32 or an elongated tubular source for surrounding the pipe sub-system.
It should also be appreciated that the inner and outer radiation sub-systems can have identical or different properties, such as light intensity, dimensions, etc.
Referring now to
The unit holding assembly 15 is in the form of a structure comprising a number of vertically oriented supports for supporting the coiled pipe and the UV lamps, and a plurality of horizontally oriented fixation rods connecting the supports, one rod—extending coaxially with the assembly central axis A, and others—extending at a radial distance therefrom, for providing the unit holding assembly 15 with a structural integrity. In particular, the unit holding assembly 15 comprises:
The left and right flange supports 40 and 42 are disposed at the ends 11 and 13 of the radiation treatment unit 10 and the intermediate lateral support 44 with the intermediate central support 43 being disposed therebetween, and the two intermediate supports 44 and 43 being aligned with each other along a plane perpendicular to the central axis A.
The supports 40, 42 and 44 are fixedly mounted to the mounting stage 4, as shown in
(
The body 41 of the left flange support 40 is assembled of three body portions: a lateral portion 40a, a central portion 40c, and a complementary portion 40b.
With reference to
The outer portion 40a can be further formed with mounting holes 76 disposed at locations radially and/or angularly spaced from the rod and lamp openings, for attachment thereto of external elements such as spacers 111 (
In the present example, the lateral portion 40a has a generally annular disk shape with a number of loop-like protrusions 75 incorporating the lamp openings 73.
The central portion 40c is formed with inner lamp openings 53 circumferentially distributed about the axis A, for receiving therein left ends 51′ of the inner lamps 51, and a central opening 72 configured to receive therein the left end of the central fixation rod 48.
The complementary portion 40b is detachably mounted between the lateral portion 40a and the central portion 40c, and is formed with an opening 49 for allowing passage therethrough of an outlet nozzle 115 in such a manner that it can project outwardly from the system and thereby provide fluid communication between the outlet 31b of the coiled pipe 20 and an accumulation system or other system at the exterior of the system, where treated fluid can be accumulated/received.
In the present example, the central portion 40c has a round disk shape and the complementary portion 40b is in the form of a shaped disc with a central aperture 80 configured to receive therein the central portion 40c and a number of fin-like protrusions 82 configured to occupy all the space between the loop-like protractions 75.
With reference to
With reference to
The intermediate central support 43 comprises inner lamp holes 93 for receiving therethrough the inner lamps 51, a central hole 99 for receiving therethough the central supporting rod 48, and slots 92 for receiving therein the coil supporting brackets 45 (
The intermediate lateral support 44 further comprises a rim 98 fixed to the circumference thereof, as shown in
Reverting to
The intermediate central support 43 and the intermediate lateral support 44 provide an additional support to the lamps and the rods of the unit 10, without adding the complexity of the unit.
The system further comprises temperature sensors 130 (
The reference is now being made of
It should be appreciated that the assembly of the unit 10 is such that it allows easy access, removal and replacement of different elements thereof. For example, the lamps 51 and 71 are mounted directly to the flange supports 40 and 42, which allows an easy access to each of the lamps without disassembling the whole unit.
As detailed above, there are several factors that influence the efficiency of the treatment process that have to be taken into consideration, namely: the intensity of the radiation, the time of the exposure of the fluid to the radiation and turbulence conditions, specifically the conditions that influence the uniformity of the fluid mixing.
A system with the parameters described above, was built and optimal time of exposure when using it was determined experimentally. Thus, the experiments yielded that the exposure time of 17 sec is sufficient for effective treatment of raw milk.
Total intensity of the system was then determined based on the exposure time and the intensity of the lamps. Surprisingly, the total intensity was found to be in the range of 9-15 mJ/cm2, and more specifically 12.7 mJ/cm2.
As to improving the uniformity of the fluid mixing, as indicated above, the diameters of the coil and the tube were chosen so as to satisfy Dean condition 0.03<D/Dc<0.1. Specifically it was experimentally determined that the most efficient mixing occurs when the ratio D/Dc is equal to 0.04 or 0.05.
A process of designing the system of the presently disclosed subject matter can be summarized by means of the following steps:
To determine the pressure difference of step (e) above, the following equations were used, in which V is a fluid velocity, ρ is a fluid density, f is a friction factor, and e is absolute roughness of the pipe.
It should be appreciated that the equations used for the calculation of the friction factor are specifically suitable for coiled pipes, such as the pipe of the presently disclosed subject matter.
In accordance with one specific example, the system was used for passing a fluid with the following parameters: Flow velocity (V)=2.8 m/sec; ρ=1,029 kg/m3; and Re=12,021, while the system had the following parameters:
The system having the above parameters provided the exposure time of 25 sec, total intensity of 12.7 mJ/cm2 and pressure difference of about 12 bar.
Referring now to
The system 201 comprises a pre/post-treatment system 260 (shown in dotted lines in
The pre/post-treatment system 260 comprises an inlet connected by means of a faucet 261 to a buffer tank 263, a pump 265 which is in fluid communication with the UV treatment unit 210 by means of a pre-treatment pipe 267, the latter being fitted with an inlet flow rate regulating valve 269, outlet flow control sensor 271, and a control board 202, which is in communication with all the elements of the pre/post-treatment system 260 and the UV treatment unit 210.
The pre/post-treatment system 260 further comprises a couple of faucets 273 and 275 disposed between the outlet flow control faucet 271 and the buffer tank 263, responsible for directing the fluid exiting the UV treatment unit 210 to either repeating the treatment, continuing to post-treatment processes or sewage.
The UV treatment unit 210 comprises a coiled pipe sub-system 230, an inner UV radiation sub-system 250, an outer UV radiation sub-system 270, all similar to the corresponding assemblies of the UV treatment unit 10, and a unit holding assembly 215 (
The unit holding assembly 215 is in the form of a structure comprising vertically oriented supports for supporting the coiled pipe and the UV lamps, and a plurality of horizontally oriented fixation rods extending between the supports.
In particular, the unit holding assembly 215 comprises a first flange support 240, a second flange support 242 and a plurality of fixation rods 246 extending therebetween.
The first and second flange supports 240 and 242 are disposed at the ends 211 and 213 of the radiation treatment unit 210 and are fixedly mounted to the mounting stage 204 by means of mounting portions 260, thereby fixing the UV treatment unit 210 to the stage 204.
The flange support 242 is substantially similar to the flange support 42 of the unit 10, for supporting the rods 246 and inner and outer lamps 251 (not shown) and 253.
The flange support 240 comprises an inner flange 230 and an outer flange 232 slightly spaced apart therefrom.
The arrangement is such that the inner flange 230 supports the supporting sockets 254 (not seen) of the lamps 251 and 253 which pass through the corresponding openings thereof and also supports end portions of the fixation rods 246 which pass through the corresponding openings thereof.
The outer flange 232 comprises openings 282 shaped so as to anchor the electrical plugs 256 (
The UV treatment unit 210 further comprises a cable flange 290, spaced from the outer flange 232 and supported by a couple of flange support rods 291.
The cable flange 290 comprises a plurality of openings 292 (
The above structure allows a convenient and organized cable arrangement and prevents a close access to the area of the electrical plugs.
Referring now to
The system 301 comprises a pre/post-treatment system 302 (shown in dotted line in
The pre/post-treatment system 302 comprises an inlet 300 (
The pre/post-treatment system 302 further comprises several elements disposed within the housing 317 (
The inlet distributor valve 311 is configured for dividing the incoming liquid between an inner coiled pipe 381 and an outer coiled pipe 331 (both shown in
The pre/post-treatment system 302 further comprises a couple of faucets 314 and 315 (
Turning now to
In particular, the unit support assembly 316 comprises three end supports 319, 320 and 350 (
The end support 350 is fixedly attached to a flange assembly 406, referred to below in detail. The UV treatment unit 310 is of an elongated shape and it comprises two main assemblies (best seen in
Each of the coiled pipes 330, 380 may be provided with a spinner 21 as described above with reference to
The above assemblies extend between the inlet and the outlet 310a and 310b of the UV treatment unit 310 and are disposed concentrically about the unit central axis C, wherein the inner pipe assembly 380 is coaxially inserted within the outer pipe assembly 330. The arrangement being such that an outer coiled pipe 331 surrounds the first radiation lamps 341, which surrounds the inner coiled pipe 381, and which in turn surrounds the second radiation lamps 391 (
The above arrangement allows the fluids which pass through the outer coiled pipe 331 to be exposed to radiation from the inside by the first radiation lamps 341, and to the fluids which pass through the inner coiled pipe 381 to be exposed to the radiation from the outside by the first radiation lamps 341 and from the inside by the second radiation lamps 391.
The inner pipe 381 and the outer pipe 331 are helically coiled pipes of a kind described above with reference to the unit 10.
The outer coiled pipe 331 has inner and outer diameters D′in and D′out, and the wall thickness t′w. The wall thickness t′w of the pipe 331 can be in the range 0.6-1.3, more particularly 0.63-1.27 mm. The inner diameter D′in of the pipe 331 can be in the range of 10-25 mm, and specifically 11 mm, allowing a flow velocity to be in the range of 2-4.5 m/sec.
The coiled pipe 331 has a form of a sleeve with an outer cylindrical surface 334 and an inner cylindrical surface 324 defining a cavity 332, all extending between pipe inlet and outlet 331a and 331b.
The coil length L′ (
The number of turns 321 forming the coil of the pipe 331 influences the time of exposure of the fluid to the UV radiation and thus the efficiency of the treatment process, and therefore it is desired to increase it as much as possible, taking into consideration other parameters such as the pipe length, spacing between the turns, pressure drop, organoleptic properties of the product, etc. The number of turns of the coil 331 in the described example of the system can be in the range of 100-130, and specifically 116.
The coil outer diameter D′c can be in the range of 350-400 mm, and specifically 386 mm, and the inner diameter of the pipe D′in and the diameter D′C of the coil can be chosen so as to satisfy Dean ratio, as explained above, i.e. 0.03≦D′in/D′C≦0.1, and specifically 0.03.
The inner coiled pipe 381 has inner and outer diameters D″in and D″out, and the wall thickness t″w. The wall thickness t″w of the pipe 381 can be in the range 0.6-1.3, more particularly 0.63-1.27 mm. The inner diameter D″in of the pipe 381 can be in the range of 10-15 mm, and specifically 11 mm, allowing a flow velocity to be in the range of 2-3.5 m/sec.
The inner coiled pipe 381 has a form of a sleeve with an outer cylindrical surface 383 and an inner cylindrical surface 385 defining a cavity 387, all extending between pipe inlet and outlet 331a and 331b.
The coil length L″ and the number of turns 389 are equal to the corresponding values of the outer pipe 331.
The coil outer diameter D″c can be in the range of 180-250 mm, and specifically 228 mm, and the inner diameter of the pipe D″in and the diameter D″C of the coil can be chosen so as to satisfy Dean ratio, as explained above, i.e. 0.03≦D″in/D″C≦0.1, and specifically 0.05.
The lamps 341 and 391 are UV tube-shaped inner lamps, similar to the lamps 51 and 71 described above, and they extend between the inlet and the outlet 310a and 310b of the UV treatment unit 310. The lamps 341 are identical to the lamps 391, or can differ therefrom by some of their properties.
The lamps 341 and 391 have a length in the range of 1,200-1,700 mm, and specifically 1,554 mm (total length) and 1475 (the emitting section) and intensity in the range of 500-1,200 μW/cm2.
The lamps 391 of the inner pipe assembly 380 are disposed within the coil cylindrical cavity 387 of the inner pipe 381 and are uniformly distributed around the axis C and spaced from the coil inner cylindrical surface 385 by a distance of s′1.
The lamps 341 of the outer pipe assembly 330 are disposed within the coil cylindrical cavity 332 of the outer pipe 331 being uniformly distributed around the axis C and spaced from the coil outer cylindrical surface 383 of the inner pipe 381 by a distance s″1 and from the inner cylindrical surface 324 of the outer pipe 331 by a distance s′2 (
In accordance with one example of the presently disclosed subject matter the number of the lamps 341 of the outer pipe assembly 330 can be [in the range of 3-10 and specifically 6 and the number of the lamps 391 of the inner pipe assembly 380 can be in the range of 10-20 and specifically 13].
The lamps 341 and 391 are fitted with respective supporting sockets 342 and 392, which are provided with electrical plugs 344 and 394 (
As further described in detail, each lamp is mounted separately to the corresponding supporting assembly.
It should be appreciated that the lamps of the inner and outer assemblies 330 and 380 can each have a single radiation source, for example, an elongated cylindrical radiation source having dimensions suitable for being inserted within the corresponding coil cylindrical cavity or an elongated tubular source for surrounding the pipe sub-system.
It should also be appreciated that the inner and outer radiation sub-systems can have identical or different properties, such as light intensity, dimensions, etc.
Referring now to
The outer supporting assembly 351 is a structure comprising a number of vertically oriented supports for fixedly supporting the outer pipe supporting rods 353 and the lamps 341, and a plurality of horizontally oriented fixation rods 355 connecting the supports, extending coaxially with the assembly central axis C.
In particular, the outer supporting assembly 351 comprises: a first support frame 351′ disposed at the inlet 310a of the UV treatment unit 310 and composed of a first flange 357 and a support ring 361, being fixedly attached thereto, a second flange 359, disposed at the outlet 310b of the UV treatment unit 310, a second support frame 351″ being disposed between the first support frame 351′ and the second flange 359, comprising a couple of support rings 361 and 361″ being fixedly attached to each other, a plurality of fixation rods 355 extending between the first flange 357 and the second flange 359 through the rings 361, 351′ and 361″.
The first flange 357 comprises a plurality of lamp openings 356 for receiving therein the sockets 342 of the lamps 341, which are fixed therein by means of corresponding nuts 354, a plurality of supporting rod openings 359 (not seen), for receiving therein ends 353′ (
The second flange 359 (best seen in
The toggle mechanism 360 comprises a plurality of rib couples 363 (
Referring now to
The inner supporting assembly 401 is a structure comprising two flange assemblies 405 and 406 disposed at the inlet and the outlet 310a and 310b respectively, of the UV treatment unit 310, and a plurality of inner pipe supporting rods 403 horizontally oriented and extending coaxially with the assembly central axis C.
The flange assemblies 405 and 406 are configured for fixedly supporting the inner pipe supporting rods 403 and the lamps 391.
The flange assembly 405 (
The base portion 411 comprises a plurality of lamp openings 412 for the ends 391a of the lamps 391 to pass therethrough and a plurality of rod openings 414 disposed between the lamp openings 412 to receive therein ends 403a of the inner pipe supporting rods 403, which are fixed to the base portion 411.
The base portion 411 further comprises a pipe receiving passage 418 for receiving therein an inlet 381a of the pipe 381.
Similarly, the flange assembly 406 (best seen in
The base portion 421 comprises a plurality of lamp openings 422 for the ends 391b of the lamps 391 to pass therethrough and a plurality of rod openings 424 disposed between the lamp openings 422 to receive therein ends 403b of the inner pipe supporting rods 403, which are fixed to the base portion 421.
The base portion 421 further comprises a pipe receiving passage 428 (
The flange assembly 406 can further comprise a cover 427 for covering the elevating portion 423.
Turning back to
The arrangement is such that the flange assembly 405 is tightly received within the flange opening 323 so that the elevating portion 413 protrudes outwardly from an outer surface 321′ of the lateral portion 321, and the sockets of 342 of the outer lamps 341 extend through the lamp openings 325.
Spaced from lateral portion 321 of the end support 319 there is the separator 340 (
The arrangement is such that cables of each of the electrical plugs of the lamps 341 and 391 are collected together so as to pass through corresponding openings within the separator 340 so as to extend therefrom to reach the control board 309. Such arrangement allows a direct access to the cables of the electrical plugs and prevents unnecessary movements of the cables.
With reference to
In particular, the horizontal supports 322 and 324 are fitted with guide tracks 441 and 443 respectively, and the first support frame 351′ and the second support frame 351″ are fitted with sliding elements 445, 445′, 447 and 447′, respectively, configured for sliding along the guide tracks 441 and 443 along the axis C of the treatment unit 310, exposing thereby the pipe inner assembly 380 (
The operation of the UV treatment unit 310 is such that a liquid to be treated flows through the inlet distributor valve 311 where it is divided between the inner coiled pipe 381 and the outer coiled pipe 331. The liquid which passes through the outer coiled pipe is treated from the inside by the UV radiation of the lamps 341 and the liquid which passes through the inner coiled pipe 381 is treated from the outside by the UV radiation of the lamps 341 and from the inside by the lamps 391.
The treated liquid then passes through the outlet distributor valve 313 which converges with the treated liquid from both pipes.
In order to make the convergence, the liquid from one pipe has to be treated equally to the liquid from the other pipe. In particular, the absorbance of the treated liquid has to be the same in both pipes, as to satisfy: F1=F2, i.e. i1×t1=i2×t2, wherein F1 is the UV dose of the liquid of the first pipe and F2 is the UV dose of the liquid of the second pipe, i is the intensity of the applied UV light from the corresponding lamps and t is the time of the exposure of the corresponding fluid to the above UV light.
The intensity (i.e. the number and the intensity of the lamps) and the exposure time of the outer pipe assembly 330 and the inner pipe assembly 380 have to be such that the above equation is satisfied.
Assuming that the number and the parameters of the lamps and the internal diameters of the pipes D′in and D″in were already determined in accordance with considerations indicated above with respect to the unit 10, the parameter that has to be determined is the time of the exposure.
The time of the exposure depends on the flow rate of the fluid, the internal diameter of the pipe and the distance which the fluid passes within the pipe, determined by the coil outer diameter, i.e. D′c and D″c.
In a specific case that the coil outer diameter D″c of the inner coiled pipe 381 is determined as described with respect to the unit 10, the coil outer diameter D′c of the outer coiled pipe 331 has to be determined accordingly, so as to satisfy the above absorbance equation F1=F2.
The system can be fitted with an arrangement for flow rate regulation, i.e. responsible for controlling the flow rate in one or both pipes to assure that the flow rate in both pipes is equal.
It should be appreciated that other designing steps are also possible, as long as the absorbance equation is satisfied.
Finally, the process of assembly of the UV treatment unit 310 is generally summarized below:
This application is a continuation-in-part of International Application No. PCT/IL2015/050037, filed Jan. 11, 2015, the full contents of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/IL2015/050037 | Jan 2015 | US |
| Child | 15646642 | US |
