WO2009024155A1

WO2009024155A1 - A fluid treatment unit comprising a treatment source

Info

Publication number: WO2009024155A1
Application number: PCT/DK2008/050206
Authority: WO
Inventors: Finn Beldring; Christian Rasmussen
Original assignee: Grundfos Management A/S
Priority date: 2007-08-17
Filing date: 2008-08-15
Publication date: 2009-02-26

Abstract

The present invention relates to a fluid treatment unit through which fluid may flow while being exposed to treatment. The unit comprises a flow passage comprising one or more treatment zones, one or more treatment sources or is adapted to receive one or more treatment sources, one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the fluid processing unit, and a casing encapsulating the one or more treatment zones and the one or more total pressure increasing means. The invention further relates to a cassette comprising one or more treatment sources or being adapted to receive one or more treatment sources, one or more total pressure increasing means or being adapted to receive one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the cassette.

Description

A FLUID TREATMENT UNIT COMPRISING A TREATMENT SOURCE

The present invention relates to a unit and method for exposing fluid, typically being a liquid, to treatment. The invention relates in particular to a fluid treatment unit through which fluid may flow while being exposed to treatment. The unit preferably comprises a flow passage comprising at least one treatment zone. The flow passage is connected to inlets and outlets of the fluid treatment unit through which the fluid flows into and out of the fluid treatment unit. The unit further comprises or is adapted to receive one or more treatment sources, one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the fluid processing unit, and a casing encapsulating the one or more treatment zone and the one or more total pressure increasing means. In preferred embodiment the treatment is performed is by electromagnetic radiation, preferably in the form of ultra-violet light. BACKGROUND OF THE INVENTION

Although the present invention finds use in many applications not involving exposing fluid to UV radiation (ultra violet radiation), the background of the invention may advantageously be presented with reference to UV radiation treatment of a fluid. Fluids, and in particular water, are often treated with UV radiation in order to destroy micro-organisms such as bacteria. In many industrial applications, such water treatment is often a preliminary, intermediate, or final step of a process involving many other processes wherein the fluid is used for e.g. cleaning, cooling or heating. The fluid is exposed to UV radiation in a unit where the fluid typically flows past a radiation source, and this flow causes a pressure drop in the water treatment process. The pressure drop must be balanced by pressurisation means, such as a pump. Today this pressure drop is balanced by a pump arranged upstream or downstream of the treatment unit, as the combination of UV radiation and pump is provided by stand-alone units connected with each other by piping which piping often results in a complex construction being vulnerable to e.g. leakage. Furthermore, pipes and other connections often results in pressure loss. Some attempts have been made to provide an integration between a treatment unit and a pump as disclosed in US 6,648, 030 and GB 2 387 330. However, the overall concepts disclosed therein follow the conventional concept of serially arranging a number of stand alone units (e.g. pump, filter, UV-chamber) connected to each other by piping.

Furthermore, water to be treated often flows in a tube in a regular flow pattern, such as parallel flow in a tube, before it is led to the radiation source. In connection with the present invention, it has been found that this regular flow pattern often needs to be changed to bring the fluid close to the radiation source to ensure that the fluid is sufficiently exposed to the UV radiation. Whether or not a change is necessary typically depends on the condition of the fluid, such as how penetrable it is to rays of UV radiation.

When the fluid is less transparent, e.g. muddy, cloudy, turbid, or the like, damping of the radiation occurs in the fluid resulting in that fluid flowing at a distance from the source of UV radiation will not be sufficiently exposed to radiation. This problem is particularly difficult to handle when the transparency of the fluid varies over time.

One particular problem occurring when exposing fluid to UV radiation is that it must often be guaranteed that the fluid is exposed to a minimum dose of UV radiation when the fluid passes through a fluid treatment unit. This dose may depend on the actual condition of the fluid, and this condition is often varying. Additionally, fouling occurs at surfaces for instance on a shield shielding the source of UV radiation from the fluid which fouling may result in the fluid not being sufficiently exposed to radiation. A particular problem may occur when the radiation source becomes warm during use and the flow of fluid past the source is insufficient to cool the radiation source. In such cases, the radiation source may easily become so warm that it breaks down.

A further problem occurs in situations where the radiation source needs some warm-up time in order for it to radiate, this being particular severe if the source during such warm-up period needs cooling as the flow used for cooling the source will not be exposed to the radiation during the warm-up period. Thus, an aim of the present invention is to solve or at least mitigate one or more of the above disclosed problems or disadvantages of fluid treatment systems known today.

DISCLOSURE OF THE INVENTION Thus, in a first aspect the present invention relates to a fluid treatment unit through which fluid may flow while being exposed to treatment, the unit preferably comprising a flow passage comprising one or more treatment zones, the flow passage being connected to an inlet and an outlet of the fluid treatment unit through which the fluid flows into and out of the fluid treatment unit, one or more treatment sources or being adapted to receive one or more treatment sources, one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the fluid processing unit, and a casing encapsulating the one or more treatment zones and the one or more total pressure increasing means.

A fluid treatment unit according to the present invention may preferably comprise more than one treatment stage each comprising a flow passage comprising a treatment zone and forming part of the flow passage through the unit, and the treatment stages being arranged so that fluid flowing through the unit passes each of the treatment stages serially. Furthermore, at least two of the treatment stages may preferably comprise total pressure increasing means.

As will be disclosed in details in the following, the one or more treatment sources is/are preferably arranged so that it/they emit radiation into to the treatment zone(s). Thus, by use of fluid treatment units according to the present invention, the fluid leaving the unit via outlets has been exposed to treatment, and inside the fluid treatment unit the total pressure of fluid being treated is increased at least locally by total pressure increasing means. While the description of the invention presented herein focus on treating one fluid, the invention is well suited for treating more than one fluid.

In accordance with the present invention, a fluid treatment unit has a casing which preferably may be considered as a container-like structure inside which the one or more treatment sources and one or more total pressure increasing means are arranged. Thereby the need for connecting standalone units by pipes to provide a fluid treatment device may be avoided, and a compact unit providing a good possibility to meet a given treatment demand may be provided.

The fluid treatment will typically result in a pressure loss e.g. due to a flow path including bends and the like and the total pressure increasing means is/are preferably used to overcome at least the pressure loss resulting from the fluid flowing through the fluid treatment unit. Thus, while the known fluid treatment units are assembled by connecting a number of stand-alone units via pipes, the present invention is designed so that it preferably comprises a pressure carrying casing inside which the treatment source(s) and total pressure increasing means are arranged, whereby the unit may be made more compact and efficient. It should be mentioned that the treatment source may comprise one or more connections (electrical, fluid connections or the like), one or more handles or the like extending outside the unit - however, the interaction between the treatment source and the fluid treatment source take preferably place inside the unit.

The efficiency of the unit may furthermore be increased as the number of treatment stages - or cassettes - may be chosen so that a given demand may be matched more accurately than by building a fluid treatment unit from a number of stand-alone units.

In the present context a number of terms are used. Although these terms are used in a manner ordinary to a person skilled in the art, a brief explanation will be presented below on some of these terms.

Treatment stage is preferably used to designate a segment of the unit. A treatment stage may preferably be in the form of a cassette (see below). Treatment zone is preferably used to designate a three-dimensional region of the flow passage wherein the treatment resulting from the fluid interacting with one or more treatment sources is initiated. A treatment zone is typically the region which receives the radiation emitted from the treatment source.

Treatment channel is preferably used to designate a part of the flow passage where a treatment source emits radiation and/or a part of the flow passage designed to guide the fluid towards a treatment source.

Treatment source is preferably used to designate an element emitting radiation, such as electromagnetic radiation, e.g. UV radiation, laser radiation, microwave radiation, radioactive radiation, sound waves. It should be mentioned that waves are preferably considered to be radiation.

Casing is preferably used to designate the wall of the fluid treatment unit which wall confines fluid in the fluid treatment unit so that fluid may flow out of / into the processing unit through one or more inlets and outlets provided in the casing. Thus, the casing thereby forms a sealed encapsulation of the fluid treatment unit. The casing may preferably comprise a number of wall elements. At least a part of the casing preferably constitutes a part of the flow passage of the fluid treatment unit. Cassette is preferably used to designate a treatment stage which either contains one or more treatment sources and/or is adapted to receive one or more treatment sources. A cassette typically comprises an outer housing, or in short housing, arranged so as to form at least part of the casing, one or more inlets and one or more outlets. The outer housing may preferably be pressure carrying in the sense that no further casing is needed to withstand the pressure difference between the interior and exterior of the cassette. Furthermore, the outer housing typically and preferably contributes in defining the flow passage through the unit. A cassette is shaped so that it comprises one or more flow passages through the cassette from its inlet to its outlet - which one or more flow passages form part of the flow passage through the unit. The inlet(s) and outlet(s) of cassettes are are openings in the cassettes in which fluid may flow into and out of the cassettes and are preferable provided so that when two cassettes are combined, the outlet(s) of one cassette are directly connected to the inlet(s) of the other cassette and vice versa. "Directly connected" is preferably used to designate a situation where the velocity and pressure of the fluid flowing out of the outlet is the same as the velocity and pressure of the fluid flowing into the inlet, which e.g. may be provided by connecting the outlet and inlet with each other with no intermediate piping in between. Furthermore, when two or more cassettes are combined, the outer casings of the cassettes are preferably combined to form at least part of the pressuring carrying casing of the processing unit. Furthermore, as a cassette often comprises total pressure increasing means overcoming the pressure loss due to fluid flowing though the cassette, the assembled unit may often be pressure neutral to the process in which it is to operate. Additionally, a cassette is preferably designed, when total pressure increasing means is present, so that flow of fluid flowing through the unit is pressure neutral or the pressure is even increased of the fluid flowing through the cassette. Total pressure increasing means is preferably used to designate an element increasing the total pressure (stagnation pressure) of a fluid. A total pressure increasing means is preferably or comprise a velocity inducer, such as an impeller.

Velocity inducer / fluid velocity inducer is preferably used to designate an element inducing velocity to the fluid so that its direction and/or total pressure is changed. A velocity inducer is preferably an impeller.

Fluid is used to designate at least liquid, gas, a fluidized medium or combinations thereof.

Inlet/outlet is preferably used to designate a cross section or a region where fluid flow into or out of an element or unit. The inlet/out may preferably be an end cross section or a region of a pipe, channel or the like. Inlet and outlet may preferably also be considered as the sections of a control volume through which fluid flow into the element/out of the element which control volume encircling the element or unit in question. Although the description of the present invention focuses on exposing fluid to UV radiation, it should be mentioned that the invention is not limited to electromagnetic radiation. In many of the preferred embodiments of the fluid treatment unit, the casing may advantageously furthermore encapsulate one, more or all of the one or more treatment sources.

Additionally, at least one of the one or more treatment zones preferably comprises or is preferably comprised in a treatment channel through which the fluid flows, and the one or more treatment channels form part of the flow passage through the unit.

Furthermore, the unit may preferably comprise one or more treatment stages each comprising a flow passage forming part of the flow passage through the unit. Preferably, some or all of the flow passages of one or more of the treatment stages may comprise two cavities being in fluid communication with each other via the treatment channel.

In many preferred embodiments of the fluid treatment unit, the total pressure increasing means may comprise one or more velocity inducers. Preferably, at least one of the one or more total pressure increasing means may comprise one or more impellers. In preferred embodiments, some or all the impellers are arranged on a common shaft connected to a motor. Preferably, each treatment stage may comprise at least one total pressure increasing means. In preferred embodiments of fluid treatment units, at least one of the at least one treatment sources may preferably be arranged behind a shield being transparent to radiation emitted from the treatment source into the treatment channel. Additionally, such units may preferably be adapted to transport fluid through the treatment channel. In many preferred embodiments, the treatment source may preferably be an UV source and the fluid transported through the channel is atmospheric air or water. Additionally, the fluid transported into the flow passage may preferably be transported in to the flow passage upstream of one of the at least one or more treatment source. In general, the at least one treatment source may preferably be one or more emitting sources emitting radiation, such as one or more electromagnetic radiation sources emitting electromagnetic radiation into the at least one treatment zone. In preferred embodiments, the one or more electromagnetic radiation source(s) may be UV radiation source(s), laser light emitting source(s), light emitting diode(s) and/or microwave emitting source(s). Preferably, one or more of the UV radiation sources is/are placed inside shield, such as a protecting tube. In embodiments, where UV radiation is emitted in particular to provide a sterilization / or disinfection effect such as a bacteria killing effect, the wave length of the UV light emitted may preferably be in the range of lOOnm to 280 nm. In a particular preferred embodiment, a mercury light source is used emitting UV light with a wave length of 254nm. Other particularly preferred wave lengths are 185 and 265 nm.

The shield inside which the treatment source(s) is placed is preferably made from quartz. This is especially preferred when the treatment source(s) is/are emitting UV radiation.

In preferred embodiments, the one or more of the one or more emitting sources may preferably be source(s) emitting radioactive radiation.

Alternatively or in combination therewith, the one or more the one or more emitting sources may preferably be source(s) emitting sound waves, such as ultra sound waves.

Preferably, one or more of the at least one emitting sources may be elongated and have a length axis.

The unit may preferably comprise a plurality of treatment sources of at least two different types.

In preferred embodiments, the unit may comprise radiation guide means for directing radiation emitted from one or more of the least one treatment source. Preferably, the radiation guide means may be adapted to direct radiation emitted from a radiation source into a direction being different from the direction it was emitted from the radiation source. Such radiation guide means may preferably comprise one or more lenses. Alternatively or in combination therewith, the radiation guide means comprise(s) one or more mirrors. It is preferred that the radiation guide means focus(es) radiation emitted from a radiation source.

Fluid treatment units according to present invention may preferably comprise a pressure sensor, a temperature sensor, a fluid velocity sensor, a mass flow sensor, a volumetric flow sensor, a pH-sensor, a conductivity sensor, an organic content sensor, a capacitance sensor, a turbidity sensor, a radiation sensor, a spectrometric sensor or combinations thereof.

Means for recirculating fluid that has flown through one or more treatment zones to flow through one or more treatment zones again may preferably be comprised in fluid treatment units according to the present invention. Preferably, the recirculation is performed inside the casing. Alternatively or in combination therewith, the recirculation may be performed by transporting fluid from the outlet to the inlet of the fluid treatment unit. Fluid treatment units according to the present invention may preferably comprise one or more cassettes. An outer housing of one or more of the cassettes may preferably form at least a part of an outer surface of the casing. Alternatively or in combination therewith, an outer housing of one or more of the cassettes may preferably form at least a part of the casing abuts an interior surface of the casing.

Preferably, one or more of the cassettes comprise(s) total pressure increasing means. Alternatively or in combination therewith, one or more of the cassettes may preferably be adapted to receive or comprise a velocity inducer, preferably being an impeller, and the velocity inducer constituting at least a part of one or both flow passages.

Preferably, one some or all of the cassettes may comprise a treatment stage of fluid treatment units according to preferred embodiment of the present invention.

Another aspect of the present invention relates to a cassette preferably comprising one or more treatment sources or being adapted to receive one or more treatment sources, one or more total pressure increasing means or being adapted to receive one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the cassette. Preferably, cassettes according to the present invention may comprise one or more of the features disclosed above in connection with fluid treatment units according to the present invention.

The total pressure increasing means may in preferred embodiments be adapted to increase the total pressure of the fluid flowing through the unit, so that fluid leaving the unit has a higher total pressure than when the fluid flows into the unit.

A further aspect of the present invention relates to a method of treating fluid, the method comprising feeding fluid to a fluid treatment unit according to the present invention. Furthermore, the invention preferably relates to use of fluid treatment units according to the present invention. Typically and preferably, the fluid is water or air. However, the invention is not limited to these fluids.

The present invention and in particular preferred embodiments thereof will now be disclosed in connection with the accompanying drawings in which:

Fig. Ia and b each shows a three dimensional view of a part of a fluid treatment unit according to the present invention; fig. Ia shows the inlet side and fig. Ib shows the outlet side of the unit (inlet and outlet parts are removed for clarity).

Fig. 2 shows schematically a longitudinal cross sectional view along line A-A of the fluid treatment unit disclosed in fig. 1,

Fig. 3 shows a horizontal cross sectional view taken along line B-B of the embodiment shown in fig. 2, Fig. 4 shows schematically a further preferred embodiment of a stage of a fluid treatment unit according to the present invention wherein the radiation source is arranged radially,

Fig. 5 shows schematically two further preferred embodiments of a stage according to the present invention wherein the treatment channel is a penetration provided in the wall element,

Fig. 6 shows schematically a treatment stage of a fluid treatment device according to a preferred embodiment of the invention; fig. 6a shows the treatment stage in a partly exploded view and fig. 6b shows a segment of a cross sectional view taken along a radius of the stage.

Fig. 7 shows schematically a fluid treatment unit according to the present invention; the unit comprises six stages, an inlet element, an outlet element and a motor for rotating impellers arranged in the fluid treatment unit,

Fig. 8 shows schematically a longitudinal cross section of a fluid treatment unit according to the present invention. The unit comprises seven stages, an inlet element, an outlet element and a motor for rotating impellers arranged in the fluid treatment unit. Fig. 8 shows in particular an embodiment of assembling the unit shown in fig. 7; radiation sources as well as the flow passages are not shown in the figure,

Fig. 9 shows schematically a longitudinal cross section of three stages according to the present invention assembled by threads being provided on a part of the stages' housing rings, Fig. 10 shows schematically a longitudinal cross section of a fluid treatment unit according to the present invention comprising six stages, an inlet element, an outlet element, a motor for rotating impellers (not shown) arranged in the fluid treatment unit; radiation sources as well as the flow passages are not shown in the figure. Fig. 11 shows schematically a cross sectional view of a segment of an embodiment in which radiation guide means in the form of a lens for focusing the radiation into the treatment channel is arranged.

Fig. 12 shows schematically a cross sectional view of a segment of an embodiment in which radiation guide means in the form of a mirror for focusing radiation into the treatment channel is arranged.

Fig. 13 shows schematically a cross sectional view of preferred embodiment of a fluid treatment unit according to the present invention, and

Fig. 14 shows a further cross sectional view of the embodiment shown in fig. 13. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE PRESENT INVENTION

Fig. Ia and b each shows a three dimensional view of a part of a fluid treatment unit 1 according to a preferred embodiment of the present invention. Fig. Ia shows side where the fluid flows into the part of the fluid treatment unit 1 with an inlet element 23 (see fig. 7) removed to unveil the inter alia the impeller 3c and the inlet to a treatment channel 7. Similarly fig. Ib shows the outlet side of the part of the unit 1 with an outlet element 27 (see fig. 7) removed to unveil at least an element 17 with a passage forming an outlet 4a.

The part shown in fig. 1 may applied to a unit as shown in fig. 7 or 8 where the part 1 takes the place of the cassettes/stages 2 - or is combined with the cassettes/stages 2.

Fluid to be treated flows via an inlet to the impeller 3c in which the pressure of the fluid is increased. The fluid flows out of the impeller 3c in a spiraling motion towards and into the treatment channel 7c. After the fluid has been exposed to the radiation, it flows out through the outlet 4a shown in fig. Ib.

The unit 1 may further comprise sockets 20 adapted to receive or comprising a radiation source. Although the socket 20 may comprise a fixture (not shown) for fixating the radiation source, such fixation may be provided by other means not necessarily being a part of the socket 20. The socket 20 is preferably fluid-tightly sealed off from the treatment channel 7.

With reference to fig. 2 showing a cross sectional view of the preferred embodiment of a fluid treatment unit 1 shown in fig. 1, further details will be given. Fig. 2 shows a part of the unit 1 with three treatment stages 2a, 2b, 2c which in the embodiment shown in fig. 2 are similar to each other; however the actual number of stages may be varied and the stages may not always be similar to each other, a, b and c in the following refer to these three stages. Each treatment stage 2, comprises a fluid velocity inducer 3, a stage connecting passage 4, and a treatment zone comprising a treatment channel 7. In the embodiment shown in fig. 2, the fluid velocity inducers 3 are in the form of rotating impellers receiving fluid in an axial direction through a stage connecting passage 4 (or through the inlet for stage c) and delivering fluid at a higher velocity in radial direction as indicated by arrows in fig. 2. In the embodiment of fig. 2, the extension of the treatment channel is indicated in fig. 2' Each treatment stage further comprises two cavities 8, 9 divided from each other by a wall element 10 and being in fluid communication with each other through the treatment channel 7. The treatment channel 7 is formed as a passage leading fluid from cavity 8 to 9.

A part of the wall of the treatment channel 7 is formed by a shield 12 behind which a treatment source - which in this embodiment is a radiation source 11 emitting radiation - is arranged. In the preferred embodiment shown in fig. 1 and 2, the radiation source 11 is an UV radiation source, such as an UV lamp. The shield is transparent for the radiation to allow the fluid to be exposed to the radiation emitted from the source. When the radiation source is an UV lamp, the shield is typically a protecting tube made from quartz.

An impeller shaft 13 is provided for rotating all impellers in common, and the impeller shaft 13 is connected to a motor (not shown). Thus, when activating the motor, the impellers 3 are rotating whereby fluid is drawn into the treatment unit 1 through the inlet 28. Starting from above (with reference to the orientation of the figure) fluid flows through the impeller 3c into the cavity 8c and through the treatment channel 7c where the fluid is exposed to radiation from the radiation source lie, where after the fluid flows into the cavity 9c and the pattern is repeated as the fluid flows towards the next impeller 3b. As illustrated in figs. 1 and 2, the treatment unit 1 may be modular e.g. by each stage being a cassette so that a number of treatment stages 2 can be stacked. As the treatment stages 2 can be stacked, a particular treatment unit 1 may easily be configured to meet a specific demand or reconfigured to meet an altered demand. The assembly of the unit may be accomplished by assembling rings 14 arranged in grooves provided in housing rings 15 of the treatment unit 1. The housing rings 15 and similar housing detail are also referred to as "outer housing" as they forms part of the casing. The assembling rings 14 furthermore provide sealing of the unit by the O-rings 16 - see also fig. 7, 8 and 9 for ways of assembling. The treatment channel 7 defines a treatment zone or a part of a treatment zone in which the fluid is exposed to the radiation emitted from the source 11. It should be noted that the treatment zone preferably is considered to comprise the zone in the treatment unit that is exposed to the radiation emitted from the source 11. The treatment zone may therefore extend outside the treatment channel, or it may occupy only a part of the treatment channel 7.

Fig. 3 shows a horizontal cross sectional view taken along line B-B in fig. 2. Fig. 3 shows in particular, the radiation source 11, the shield 12 and a cross section of the treatment channel 7. All the fluid passing through the unit 1 is passing through the treatment channel 7, and as indicated in fig. 2, the dimensioning of the treatment channel 7 is so that the fluid gets in close contact with the source of radiation.

Fig. 3 also indicates that the shield 12 is sealed to the unit 1 by seals 18 and secured to the unit 1 by a screwed cap 19 so that fluid cannot flow to the interior of the shield 12. Thereby the radiation source 11 can be replaceably arranged within the shield 12 so that replacement of the radiation source can be provided without dismantling the whole unit 1.

Cooling of the radiation source 11 - and a treatment source in general - may be accomplished by transporting a cooling fluid through the inside of the shield.

Fig. 4 shows schematically a further embodiment of a stage 2 of a fluid treatment unit according to the present invention. In this embodiment the treatment channel 7 is arranged parallel to a radius of the wall element 1. Similar to the embodiment shown in fig. 1, the stage 1 comprises a socket 20 (not shown) for receiving a radiation source; the source is not shown in the figure.

Fig. 5a and 5b shows further embodiments of stages of fluid treatment units according to the present invention. The treatment channel 7 is in these embodiments defined by a penetration 21 provided in the wall element 10 wherein the stream wise extension of the treatment channel is the thickness of the wall element 10. The figures show configurations where a shield 12 in the form of a tube is provided for housing e.g. a UV source similar to the shield shown in fig 2.

In fig. 5b an impeller shield 50 is arranged in which an impeller 8 is to be arranged as disclosed in connected with fig. 6. It should be mentioned that although the embodiments shown in fig.s 1-5 are shown to comprise one treatment channel 7, more than one treatment channel 7 may be provided in the stages 2. Furthermore, the mutual orientation of the treatment channels 7 may be varied, e.g. two or more treatment channels may be orientated similar to each other or different to each other.

In some embodiments, the radiation source 11 - or one or more treatment sources in general - of a stage 2 is an integral part of the stage 2 in the sense that it is non-removable, and in other embodiments the stages 2 are provided with a socket 20 that enables removal of the radiation source 11. The latter embodiments are particularly useful in situations where for instance the radiation source deteriorate during use, and/or in cases where the type of processing of the fluid is to be changed. This may then be performed by only changing the radiation source.

Fig. 6 shows schematically a treatment stage 2 of a fluid treatment device according to a preferred embodiment of the invention wherein the treatment source is an ultra sound generator; fig. 6a shows the treatment stage 2 in a partly exploded view and fig. 6b shows a segment of a cross sectional view taken along a radius of the treatment stage 2 with the shaft 13 removed. Arrows labeled F in the figure indicates the flow of the fluid through the stage 2.

As shown in fig 6a, the treatment stage 2 is similar to one of the treatment stages 2 shown in fig. 1 and 2 although the treatment stage 2 in fig. 6 do not comprise the shield 12 and the radiation source 11. Instead, an ultra sound generator 46 with an ultra sound horn 47 is arranged to emit ultra sound to the treatment channel 7. A flow guide 48 is also arranged within the treatment channel. The flow guide 48 leaves a passage open between the ultra sound horn 47 and the end of the flow guide 48 whereby the flow guide assists in guiding the fluid towards the ultra sound horn 47. The flow guide 48 may furthermore be excited by the sound waves emitted from the ultra sound horn 47.

Also in this case a number of treatment stages 2 may be stacked similarly to what is shown in fig. 2, and the stack may be incorporated in the embodiments shown in fig. 7 and 8 Furthermore, such a stack of treatment stages may comprise different treatment sources to provide different treatment technologies, for instance a combination of the UV treatment and the ultra sound treatment.

An impeller 8 is arranged within the impeller shield 50 which shield 50 guides the fluid through the impeller 8.

Fig. 7 shows schematically a fluid treatment unit 1 according to the present invention. The unit shown in fig. 7 is formed as an elongated unit having cylindrical outer shape and comprising six stages 2, an inlet element 23, an outlet element 22 and a motor 24. The motor 24 is arranged on a fixture 25. The sockets 20 are also indicated in the figure.

Within the stages 2 a number of impellers 3 (see fig. 2) are arranged which impellers 3 are arranged on a common shaft 13 extending from the motor 24 to a bearing 26 (see fig. 8) arranged in the inlet element 22 so that when the motor 24 rotates, it rotates all the impellers 3. Fluid enters into the fluid treatment unit 1 through the inlet 27 provided in the inlet element 22, flows through the fluid treatment unit 1 and leaves the fluid treatment unit 1 through the outlet 28 provided in the outlet element 23.

A pressure increasing step may be provided in the outlet element 23 or the inlet element 22 by arranging a number of impellers 3 to form a pressure increasing stack of impellers 3 which impellers are arranged on the common shaft 13. The pressure increase provided by the stack of impellers 3 may be larger than the pressure drop resulting from the flow and processing of the fluid in the stages 2, and the fluid thereby leaves the fluid treatment unit 1 at an increased pressure level relatively to the pressure of the fluid at the inlet 27.

The number of stages 2 may be selected according to a specific need for treatment. For instance, the three stages 2 shown in fig. 2 may be three of the stages 2 shown in fig. 7 and the remaining three stages being omitted (please note the flow direction in fig. 7 is shown upside-down in relation to the flow direction shown in fig. 2). Alternatively, only one of the stages 2 shown in fig. 2 may be one of the stages shown in fig. 7 and the remaining five stages 2 be omitted.

Fig. 8 shows schematically a longitudinal cross section of a fluid treatment unit 1 according to the present invention, and shows in particular one way of assembling the unit shown in fig. 7. The unit is formed as an elongated unit having a cylindrical casing 40 and comprises seven stages 2, an inlet element 22, an outlet element 23 and a motor 24 arranged on a fixture 25 with a shaft 13 for rotating impellers (not shown) arranged in the fluid treatment unit 1. Radiation sources as well as the flow passages are not shown in the figure. The stages 2 may be in the form shown in the previous figures with corresponding descriptions. The inlet element 22 and the outflow element 23 are considered as part of the casing.

In the embodiment illustrated in fig. 8, the stages 2 and elements 22, 23 are assembled by a fluid treatment unit assembling fixture 29 comprising a number of stay bolts 30 extending along the longitudinal direction of fluid treatment unit 1 and penetrating clamps 31. Nuts 32 are provided on the ends of the stay bolts 30 so that when the nuts 32 are tightened, the clamps 31 will provide a longitudinal force to the fluid treatment unit 1 so that the elements 22,23 and stages 2 are held together in the longitudinal direction.

Securing of the elements 22, 23 and stages 2 in a direction perpendicular to the longitudinal direction of the fluid treatment unit 1 is shown as being provided by ring shaped guides 33 into which the elements 22, 23 and stages 2 fit snugly. Sealing of the fluid treatment unit is provided by applying o-rings (not shown) e.g. in grooves (not shown) provided in the ring shaped guides 33. Alternatively, or in combination thereto, the ring shaped guides 33 may be formed as assembling rings 14 arranged inside the fluid treatment unit as shown in fig. 2.

Fig. 9 shows schematically a longitudinal cross section of three stages 2 according to the present invention assembled in an alternative manner. The stages 2 may e.g. be three of the stages shown in fig. 7, but the method of assembling the stages may be used in other embodiments. Again, flow passages and radiation sources are not shown in the figure. The housing rings 15 of the stages 2 are provided with a recess 34 at one end and a projection 35 at the opposite end. In the recess 34 and on the projection 35 threads are provided, which projection and recess with threads are corresponding so that stages can be assembled by turning the stages relatively to each other. It should be mentioned that this way of assembling may also be applied to the assembling of the inlet and outlet elements 22, 23 with the stages 2 shown in figs. 7 and 8.

Fig. 10 shows schematically a longitudinal cross section of a fluid treatment unit 1 according to the present invention. The fluid treatment unit 1 is formed as an elongated unit having a cylindrical shape and comprises six stages 2, an inlet element 22, an outlet element 23 and a motor 24 with a shaft 13 for rotating impellers (not shown) arranged in the fluid treatment unit 1; radiation sources as well as the flow passages are not shown in the figure.

The part of the unit's casing extending along the stages 2 is a composite casing composed by a tubular part 36 and the housing rings 15 of the stages 2. Other structures may be included in the composite casing, such as sealing elements, further tubular elements, securing elements guides etc. The internal diameter of the tubular part 36 is chosen in respect to the outer diameter of the stages 2, so that a snug fit between the wall of the tubular part 36 and the housing rings 15 of the stages 2 is provided. Thus, as the housing rings 15 abuts the tubular part 36 and thereby provides a composite casing, the housing rings 15 of the stages 2 form a part of casing. It should be mentioned that although the housing rings 15 of the stages 2 are shown as abutting the tubular part 36 along the entire longitudinal extension of stages 2 this may not always be the situation. For instance, the some or all of the housing rings 15 may be recessed along the side of the housing rings 15 facing towards the interior surface of the tubular part 36 so that only a part of the housing rings 15 abuts the tubular part 36.

Assembly of the fluid treatment unit disclosed in connection with fig. 10 may be provided in the manner disclosed in connection with figs. 8 and 9. However, the fluid treatment units 1 according to fig. 10 may preferably be assembled by providing threads in a recess 34 of the inlet element 22, the outlet elements 23 and on the outer wall of the tubular part 36 so that the fluid treatment unit 1 is assembled by turning the inlet and outlet elements 22, 23 relatively to the tubular part 36.

Although the description of the present invention presented herein focus on impellers for driving the fluid through the fluid treatment unit, other types of pressurisation means may be used. However, in connection with the present invention it has been found that impellers are advantageous, as the impellers provide a flow which includes a swirling velocity component in the fluid flowing through the one or more of the stages or the whole fluid treatment unit. Such a swirling velocity component may be used to increase the interaction with the radiation source in the unit which may be utilised to process the fluid more intensively while keeping the overall outer dimensions of the fluid treatment unit low and the velocity in the unit high.

Fig. 11 shows schematically a cross sectional view of a segment of an embodiment in which radiation guide means in the form of a lens for focusing the radiation into the treatment channel is arranged. Fig. 11 shows in particular, a shield 12 in the form of an elongated tube similar to the shield disclosed in connection with e.g. fig. 3. Inside the shield 12 a radiation source 11 preferably being an UV radiation source is arranged together with a lens 40. Arrow 41 indicates the flow of the fluid flowing through the treatment channel 7 or the treatment zone in general. The lens 40 focuses the radiation emitted from the source 11 preferably on a wall part 42 of the treatment channel as indicated by the lines. The wall part 42 may also be made as a radiation direction part, typically embodied by making the wall part 42 reflective to reflect radiation back into the treatment channel.

Fig. 12 shows schematically a cross sectional view of a segment of an embodiment in which radiation guide means in the form of a mirror for focusing radiation into the treatment channel is arranged. Fig. 12 shows an embodiment similar to the embodiment shown in fig. 11 although the radiation guide means is in the form a mirror re-directing radiation emitted in a direction facing away from the treatment channel 7 into the channel as indicated by the lines in the figure. Also in this embodiment, the wall part 42 may be made as a radiation direction part, typically embodied by making the wall part 42 reflective to reflect radiation back into the treatment channel.

It should be noted that combinations of the radiation guide means may be used, e.g. a combination of the mirror 43 and the lens 40, which combination may be combined with the reflective wall part 42.

By employing such guide means, the intensity of the radiation may be increased by focusing radiation locally whereby a more efficient exposure may be applied to the fluid.

In many practical implementations it has been found of value to measure the intensity of the radiation emitted into the fluid flowing through the treatment channel 7 - typically in order establish whether the fluid has been sufficiently exposed to radiation to e.g. destroy bacteria or the like. In preferred embodiment, a radiation sensor is arranged in the wall of the treatment channel e.g. at the position indicated by numeral 44 in fig. 11 and 12.

The use of sensors is not restricted to application of a treatment source emitting UV radiation and other type of sensors may be implemented in the unit. Such other sensor may be used for measuring e.g. the radiation emitted from the treatment and/or the effect of emitting radiation to the fluid.

Fig. 13 shows schematically a cross sectional view of preferred embodiment of a fluid treatment unit according to the present invention. Fig. 13 shows in particular a fluid treatment unit from which the segments shown in fig. 11 and 12 are taken. The radiation guide means 40, 43 are not shown in fig. 13. Reference is furthermore made to fig. 2 which shows a similar configuration although fig. 13 comprises an inlet element 45 being different from the inlet element 23 (see fig. 7) applied in connection with the embodiment of fig. 2 and although the layout of the treatment is different.

In situations where the radiation is UV radiation, the UV radiation may be used to generate ozone which may be led into the fluid present in the fluid treatment unit. In one particular preferred embodiment, generation of ozone is provide by air flowing past the radiation source 11 arranged in the shield 12 (see e.g. fig. 3) whereby ozone is generated inside the shield 12 in the air. Such a flow past the treatment source has furthermore the effect of cooling the treatment source. This mixture of ozone and air is fed into fluid treatment unit preferably at location upstream of the radiation source for instance by a nozzle arranged downstream of the treatment channel - or in general the treatment zone. This is in particularly useful in connection with destruction of legionella bacteria as the ozone punctures host cells for the legionella bacteria so that the host cells becomes ready for radiation. Destruction of e.g. legionella may be further assisted by exposing the fluid to ultra sound - in which case ozone may be omitted in some cases. In some situations recirculation of fluid may be advantageous. For instance, some radiation sources need some warm-up time before the radiation level of the source reaches an appropriate level when considering the amount of radiation needed for a given purpose. In such an many other situations in general, fluid having flown through one or more treatment channels - or treatment zones in general - has not been sufficiently exposed to the radiation and in order to treat this fluid further, the fluid is recirculated to flow through one or more treatment channels or treatment zones again. The recirculation may be performed internally in the unit by e.g. arranging a closeable connection in the wall element 10 of the embodiment shown in fig. 2 and/or fluid may be re-directed from the outlet 27 to the inlet 28 by a suitable valve system.

Furthermore, fouling of the unit and in particular of the shield may be removed by increasing the velocity of the medium past the surfaces. This result in an exposure time being relatively smaller than if the velocity was lower, and it may therefore be necessary to re-circulate the fluid through the unit.

The above description has focussed on radiation of electromagnetic radiation in form of UV radiation. However, the invention is also applicable in connection with other radiation sources, such as radioactive radiation, ultrasound, mechanical wave radiation, and pressure wave radiation (e.g. ultra sound). Implementation of these other types of radiation may e.g. be accomplished arranging a desired source inside the shield 12 similarly to the source 11 in fig. 3 or arranging the desired source in the treatment zone in general - if no shielding is needed or preferred, the shield may of course be omitted.

As indicated above, the embodiments of the present invention may be made modular e.g. by a stack comprising a number of treatment stages. One or more of the treatment stages are preferably a cassette which comprises one or more treatment sources, impellers and the like - or is adapted to receive such feature - so that a cassette is preferably a ready to use element which can be arranged in a stack to form a complete treatment unit such as the unit shown in fig. 7. In other embodiments, one or more cassettes of the cassettes disclosed herein are combined with cassettes comprising other means for interacting with the fluid.

In this sense, each treatment stage shown in e.g. fig. 2, and fig. 6 may be considered as constituting cassettes.

Utilisation of cassettes is very convenient where treatment units need to be tailored to a specific need. For instance various treatment technologies may be combined by combining cassettes with the various treatment technologies, and a given treatment capacity may be matched by stacking a number of cassettes.

Although the present invention has been described in connection with the specified embodiments, it should not be construed as being in any way limited to the presented examples. The scope of the present invention is set out by the accompanying claim set. In the context of the claims, the terms "comprising" or "comprises" do not exclude other possible elements or steps. Also, the mentioning of references such as "a" or "an" etc. should not be construed as excluding a plurality. The use of reference signs in the claims with respect to elements indicated in the figures shall also not be construed as limiting the scope of the invention. Furthermore, individual features mentioned in different claims, may possibly be advantageously combined, and the mentioning of these features in different claims does not exclude that a combination of features is not possible and advantageous.

Claims

1. A fluid treatment unit through which fluid may flow while being exposed to treatment, the unit comprising - a flow passage comprising one or more treatment zones, the flow passage being connected to an inlet and an outlet of the fluid treatment unit through which the fluid flows into and out of the fluid treatment unit, one or more treatment sources or being adapted to receive one or more treatment sources, one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the fluid processing unit, and a casing encapsulating the one or more treatment zones and the one or more total pressure increasing means.

2. A fluid treatment unit according to claim 1, wherein the unit comprises more than one treatment stages each comprising a flow passage comprising a treatment zone and forming part of the flow passage through the unit, said treatment stages being arranged so that fluid flowing through the unit passes each of the treatment stages serially.

3. A fluid treatment unit according to claim 2, wherein more than one of the treatment stages comprise total pressure increasing means.

4. A fluid treatment unit according to any of the preceding claims, wherein the casing furthermore encapsulates one, more or all of the one or more treatment sources.

5. A fluid treatment unit according to any of the preceding claims, wherein at least one of the one or more treatment zones comprises or is comprised in a treatment channel through which the fluid flows, the one or more treatment channels forming part of the flow passage through the unit.

6. A fluid treatment unit according to any of the preceding claims, wherein the unit comprises one or more treatment stages each comprising a flow passage forming part of the flow passage through the unit.

7. A fluid treatment unit according to claim 5 or claim 6 when dependent on claim 5, wherein some or all of the flow passages of one or more of the treatment stages comprising two cavities being in fluid communication with each other via the treatment channel.

8. A fluid treatment unit according to any of the preceding claims, wherein the total pressure increasing means comprise(s) one or more velocity inducers.

9. A fluid treatment unit according to any of the preceding claims, wherein at least one of the one or more total pressure increasing means comprises one or more impellers.

10. A fluid treatment unit according to claim 9, wherein some or all the impellers are arranged on a common shaft connected to a motor.

11. A fluid treatment unit according to claim 2 or any of claims 3-10 when dependent on claim 2, wherein each treatment stage comprises at least one total pressure increasing means.

12. A fluid treatment unit according to claim 5 or any of claims 6-11 when dependent on claim 5, wherein at least one of the at least one treatment sources is arranged behind a shield being transparent to radiation emitted from the treatment source into the treatment channel, the unit being adapted to transport fluid through the treatment channel.

13. A fluid treatment unit according to any of the preceding claims, wherein one or more of the treatment sources is/are an UV source and the fluid transported through the channel is atmospheric air or water.

14. A fluid treatment unit according to any of the preceding claims, wherein the fluid transported into the flow passage is transported into the flow passage upstream of one of the one or more treatment sources.

15. A fluid treatment unit according to any of the preceding claims, wherein the at least one treatment source is/are one or more emitting sources emitting radiation.

16. A fluid treatment unit according to claim 15, wherein one or more of the emitting source(s) is/are electromagnetic radiation source(s) emitting electromagnetic radiation into the at least one treatment zone.

17. A fluid treatment unit according to claim 16, wherein the one or more 5 electromagnetic radiation sources is/are UV radiation source(s), laser light emitting source(s), light emitting diode(s) and/or microwave emitting source(s).

18. A fluid treatment unit according to claim 17, wherein one or more of the electromagnetic radiation sources is/are UV radiation source(s) placed inside

10 a shield such as a protecting tube.

19. A fluid treatment unit according to claim 18, wherein the shield is made from quartz.

20. A fluid treatment unit according to claim 15, wherein one or more of the one or more emitting sources is/are source(s) emitting radioactive radiation.

15 21. A fluid treatment unit according to claim 15, wherein one or more the one or more emitting sources is/are source(s) emitting sound waves, such as ultra sound waves.

22. A fluid treatment unit according to any of the claims 15-21, wherein one or more of the at least one emitting sources is/are elongated and has a

20 length axis.

23. A fluid treatment unit according to any of the claims 15-22, the unit comprising a plurality of treatment sources of at least two different types.

24. A fluid treatment unit according to any of the preceding claims, the unit further comprising radiation guide means for directing radiation emitted

25 from one or more of the least one treatment source.

25. A fluid treatment unit according claim 24, wherein the radiation guide means is/are adapted to direct radiation emitted from a radiation source into a direction being different from the direction it was emitted from the radiation source.

30 26. A fluid treatment unit according to claim 24 or 25, wherein the radiation guide means comprise(s) one or more lenses.

27. A fluid treatment unit according to any of the claims 24-26, wherein the radiation guide means comprise(s) one or more mirrors.

28. A fluid treatment unit according to any of the claim 24-27, wherein the radiation guide means focus(es) radiation emitted from a radiation source.

29. A fluid treatment unit according to any of the preceding claims, the treatment unit comprising a pressure sensor, a temperature sensor, a fluid velocity sensor, a mass flow sensor, a volumetric flow sensor, a pH-sensor, a conductivity sensor, an organic content sensor, a capacitance sensor, a turbidity sensor, a radiation sensor, a spectrometric sensor or combinations thereof.

30. A fluid treatment unit according to any of the preceding claims, further comprising means for recirculating fluid that has flown through one or more treatment zones to flow through one or more treatment zones again.

31. A fluid treatment unit according to claim 30, wherein the recirculation is performed inside the casing.

32. A fluid treatment unit according to claim 30, wherein the recirculation is performed by transporting fluid from the outlet to the inlet of the fluid treatment unit.

33. A fluid treatment unit according to any of the preceding claims, wherein the total pressure increasing means is/are adapted to increase the total pressure of the fluid flowing through the unit, so that fluid leaving the unit has a larger total pressure than fluid flowing into the unit.

34. A fluid treatment unit according to any of the preceding claims, the unit comprising one or more cassettes.

35. A fluid treatment unit according to 34, wherein an outer housing of one or more of the cassettes forms at least a part of an outer surface of the casing.

36. A fluid treatment unit according to claim 34 or 35, wherein an outer housing of one or more of the cassettes forming at least a part of the casing abuts an interior surface of the casing.

37. A fluid treatment unit according to any of the claims 34-36, wherein one or more of the cassettes comprise(s) total pressure increasing means.

38. A fluid treatment unit according to any of the claims 34-37, wherein one or more of the cassettes is/are adapted to receive or comprise(s)ing a velocity inducer, preferably being an impeller, the velocity inducer constituting at least a part of one or both flow passages.

5 39. A fluid treatment unit according to any of the claims 34-38, wherein one, some or all of the cassettes comprises a treatment stage.

40. A cassette comprising one or more treatment sources or being adapted to receive one or more treatment sources,

10 - one or more total pressure increasing means or being adapted to receive one or more total pressure increasing means for increasing the total pressure of fluid at least locally in the cassette.

41. A cassette comprising one or more of the features according to claim 1-

39.

15 42. A method of treating fluid, the method comprising feeding fluid to a fluid treatment unit according to any of claims 1-39.

43. A method according to claim 42, wherein the fluid is water or air.