Abstract:
There is described an excimer radiation lamp assembly. The lamp assembly comprises: an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; an electrode element in electrical connection with at least a portion of the elongate passageway; and a cooling element disposed in the elongate passageway, the cooling element being electrically isolated with respect to the electrode element.

Description:
FIELD OF THE INVENTION 
       [0001]    In one of its aspects, the present invention relates to an excimer radiation lamp assembly. In another of its aspects, the present invention relates to a radiation source module comprising the excimer radiation lamp assembly. In another of its aspects, the present invention relates to a fluid treatment system comprising the excimer radiation lamp assembly. 
       DESCRIPTION OF THE PRIOR ART 
       [0002]    Fluid treatment systems are known generally in the art. 
         [0003]    For example, U.S. Pat. Nos. 4,482,809, 4,872,980, 5,006,244, 5,418,370, 5,539,210 and Re:36,896 (all in the name of Maarschalkerweerd and all assigned to the assignee of the present invention) all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation. 
         [0004]    Generally, such prior fluid treatment systems employ an ultraviolet radiation lamp to emit radiation of a particular wavelength or range of wavelengths (usually between 185 and 400 nm) to effect bacterial kill or other treatment of the fluid being treated. Many conventional ultraviolet radiation lamps are known as “low pressure” mercury lamps. 
         [0005]    In recent years, the art in low pressure mercury lamps has evolved with the development of the so-called Low Pressure, High Output (LPHO) and amalgam UV radiation lamps. These lamps have found widespread use in UV radiation water treatment systems, particularly those used for treatment of municipal drinking water and wastewater. As used herein, the term “low pressure” UV radiation lamp is intended to encompass conventional UV radiation lamps, LPHO UV radiation lamps and amalgam UV radiation lamps. 
         [0006]    Low pressure UV radiation lamps and medium pressure UV radiation lamps are the current standard used for UV radiation treatment of municipal drinking water and wastewater. 
         [0007]    In recent years, there has been development in the area of so-called excimer radiation lamps. These lamps have the potential to be used in a variety of applications. One such application is UV radiation treatment of water—e.g., municipal drinking water and wastewater. 
         [0008]    To date, there has been little or no development of excimer radiation lamps for use in the UV radiation treatment of water—e.g., municipal drinking water and wastewater. Further, it is known that excimer radiation lamps require cooling for optimal operation. 
         [0009]    Accordingly, there is a real need in the art for an excimer radiation lamp that is well suited for use in the UV radiation treatment of water—e.g., municipal drinking water and wastewater. More particularly, there is a real need in the art for an excimer radiation lamp that is well suited for use in the UV radiation treatment of water on the one hand and incorporates the required cooling function on the other hand. 
         [0010]    In a similar vein, there is a need in the art for a radiation source module and a fluid treatment system incorporating such an excimer radiation lamp. 
       SUMMARY OF THE INVENTION 
       [0011]    It is an object of the present invention to provide a novel excimer radiation lamp assembly. 
         [0012]    It is a further object of the invention to provide a novel radiation source module. 
         [0013]    It is yet a further object of the present invention to provide a novel fluid treatment system. 
         [0014]    Accordingly, in one of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0015]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0016]    an electrode element in electrical connection with at least a portion of the elongate passageway; and 
         [0017]    a cooling element disposed in the elongate passageway, the cooling element being electrically isolated with respect to the electrode element. 
         [0018]    In another of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0019]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0020]    an electrode element in electrical connection with at least a portion of the elongate passageway; and 
         [0021]    a cooling circuit disposed in the elongate passageway and configured to receive a coolant, the cooling circuit having: (i) a coolant inlet, (ii) a coolant outlet and (iii) a length such that an applied voltage at the electrical connection is reduced by a factor of at least 0.10 at the coolant inlet. 
         [0022]    In another of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0023]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0024]    an electrode element in electrical connection with at least a portion of the elongate passageway; and 
         [0025]    a cooling circuit disposed in the elongate passageway and configured to receive a coolant, the cooling circuit having: (i) a coolant inlet, (ii) a coolant outlet and (iii) a cooling loop configured to be in heat exchange contact with fluid from a fluid treatment system in which the radiation assembly is disposed. 
         [0026]    In another of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0027]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0028]    an electrode element in electrical connection with at least a portion of the elongate passageway; and 
         [0029]    a cooling circuit disposed in the elongate passageway and configured to receive a coolant, the cooling circuit having: (i) a coolant inlet in fluid communication with fluid from a fluid treatment system in which the radiation assembly is disposed, (ii) a coolant outlet in fluid communication with fluid from a fluid treatment system in which the radiation assembly is disposed and (iii) motive means to cycle the coolant from the cooling circuit to the fluid treatment system. 
         [0030]    In another of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0031]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0032]    an elongate electrode element disposed in the elongate passageway to define an annular passageway configured to receive an electrically conductive fluid; and 
         [0033]    a cooling element disposed in the elongate electrode, the cooling element comprising a substantially electrically non-conductive heat transfer element configured to convey heat from the elongate electrode. 
         [0034]    In another of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0035]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0036]    an electrode element in electrical connection with at least a portion of the elongate passageway; and 
         [0037]    the elongate passageway comprising a heat pipe element, the heat pipe element configured to transfer heat from the electrode element. 
         [0038]    In another of its aspects, the present invention provides an excimer radiation lamp assembly comprising: 
         [0039]    an elongate member having an annular cross-section to define an elongate passageway aligned with a longitudinal axis of the lamp assembly; 
         [0040]    an elongate electrode element disposed in the elongate passageway to define a gap therebetween, the elongate electrode element being in electrical connection with at least a portion of the elongate passageway; and 
         [0041]    a resilient member disposed in the gap to prevent direct contact between the elongate electrode element and a wall of the elongate passageway at a location of the gap. 
         [0042]    In yet another of its aspects, the present invention relates to a radiation source module comprising the present excimer radiation lamp assembly. 
         [0043]    In yet another of its aspects, the present invention relates to a fluid treatment system comprising the present excimer radiation lamp assembly. 
         [0044]    In a highly preferred embodiment the present excimer radiation lamp assembly is configured so as to emit ultraviolet radiation. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0045]    Embodiments of the present invention will be described with reference to the accompanying drawings, wherein like reference numerals denote like parts, and in which: 
           [0046]      FIG. 1  illustrates a perspective view of the portion of an embodiment of the present excimer radiation lamp assembly; 
           [0047]      FIG. 2  illustrates a schematic of the use of open and closed circuits for cooling the present excimer radiation lamp assembly; 
           [0048]      FIG. 3  illustrates a sectional view of a first embodiment of the present excimer radiation source assembly; 
           [0049]      FIG. 4  illustrates a sectional view of a second embodiment of the present excimer radiation source assembly; 
           [0050]      FIG. 5  illustrates a sectional view of a third embodiment of the present excimer radiation source assembly; 
           [0051]      FIG. 6  illustrates a sectional view of a fourth embodiment of the present excimer radiation source assembly; 
           [0052]      FIG. 7  illustrates a sectional view of a fifth embodiment of the present excimer radiation source assembly; 
           [0053]      FIG. 8  is an enlarged sectional view of a portion of the embodiment illustrated in  FIG. 7 ; 
           [0054]      FIG. 9  illustrates a sectional view of a sixth embodiment of the present excimer radiation source assembly; 
           [0055]      FIG. 10  is an enlarged cross sectional view of a portion of  FIG. 9 ; and 
           [0056]      FIGS. 11-13  illustrates various views of a seventh embodiment of the present excimer radiation source assembly. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0057]    With reference  FIG. 1 , there is illustrated an excimer radiation source assembly  10  comprising a center electrode  15  connected to a flanged cover element  20 . Disposed in the central portion of flanged cover element  20  is a connector  25  for electrical connection to the so-called hot electrode. Also disposed in the central portion of flanged cover element  20  is a connector  30  for connection to a supply of coolant. 
         [0058]    The supply of coolant to connector  30  will be discussed below with reference to preferred embodiments of the present excimer radiation lamp assembly. It will be appreciated by those of skill in the art that excimer radiation source assembly  10  includes an annular radiation emitting element that is not shown for clarity in  FIG. 1  but will be shown herein below with reference to preferred embodiments. 
         [0059]    With reference to  FIG. 2 , there are illustrated preferred embodiments of implementation of the present excimer radiation lamp assembly. 
         [0060]    Specifically, a fluid treatment system  100  is provided and includes a closed fluid treatment zone  105  through which fluid flows as illustrated. 
         [0061]    Disposed in fluid treatment zone  105  is a excimer radiation lamp assembly  10 . As shown, excimer radiation lamp assembly  10  comprises center electrode  15  and flanged cover element  20 . Center electrode  15  is disposed coaxially with respect to an annular radiation emitting element  25  having an annular chamber  30 . A phosphor material (not shown) may be applied to one or both, preferably both, of surfaces  35  and  40  of annular chamber  30 . 
         [0062]    As shown, excimer radiation lamp assembly  10  is connected to a coolant input line  110  and a coolant output line  115 . 
         [0063]    In  FIG. 2 , there are illustrated two general approaches to effecting cooling of excimer radiation lamp assembly  10 . 
         [0064]    First, there is illustrated a so-called closed circuit. In a first embodiment of the closed circuit, coolant output line  115  is passed through a heat exchange element  120  disposed in water passing through fluid treatment zone  105 . In a second embodiment, coolant output line  115  is connected to a heat exchange coil  125  disposed in water passing through fluid treatment zone  105 . In each of these embodiments, coolant at a relatively high temperature in coolant output line  115  is subjected to heat exchange with relatively cool water passing through fluid treatment zone  105  such that relatively cool coolant is circulated back to excimer radiation lamp assembly  10  via coolant input line  110 . 
         [0065]    In the open circuit, water is taken from fluid treatment zone  105  and fed to excimer radiation source assembly  10  via coolant input line  110 . Spent coolant from excimer radiation lamp assembly  10  is fed into fluid treatment zone  105  by coolant output line  115 . This process is repeated in a circuitous manner. 
         [0066]    With reference to  FIG. 3 , there is illustrated an excimer radiation lamp assembly  200  disposed between a pair of walls  201  of a fluid treatment system. 
         [0067]    Excimer radiation lamp assembly  200  comprises an annular radiation emitting element  205  that is generally similar in construction to radiation emitting element  25  discussed above with reference to  FIG. 2 . 
         [0068]    Disposed coaxially within annular radiation emitting element  205  is a center electrode  210 . Center electrode  210  comprises a first passageway  215  and a second passageway  220 . First passageway  215  and second passageway  220  are separated by a baffle element  225 . Disposed between annular radiation emitting element  205  and center electrode  210  is a conductive or dielectric fluid  230 . 
         [0069]    Disposed near a proximal portion of center electrode  210  is a electrically isolating element  235 . The portion of center electrode  210  located distally of electrically isolating element  235  is connected to a voltage source as shown. Reactor wall  201  near the distal portion of center electrode  210  is connected to a pressure relief valve  240 . 
         [0070]    Excimer radiation lamp assembly  200  may be used in the following matter. Voltage is applied to center electrode  210 . This voltage is applied to radiation emitting element  205  via conductive fluid  230  resulting in emission of radiation, preferably ultraviolet radiation. Concurrent with this is an increase in temperature of excimer radiation lamp assembly  200 . 
         [0071]    It is important to control the temperature of excimer radiation lamp assembly  200  to optimize the prescribed radiation being emitted therefrom. To achieve this, a non-conductive coolant is passed through first passageway  215  and second passageway  220  in the direction of arrows A. As shown in  FIG. 3 , the non-conductive coolant is connected to excimer radiation lamp assembly via coolant intake line  110  and coolant output line  115 . Lines  110  and  115  can be connected to a closed or open circuit as discussed above with reference to  FIG. 2 . 
         [0072]    With reference to  FIG. 4 , there is illustrated an excimer radiation lamp assembly  300 . In  FIG. 4 , elements with the same last two digits as those used in  FIG. 3 , are intended to denote similar structure. The principal modification in  FIG. 4  compared with  FIG. 3 , is the use of a longer cooling circuit within central electrode  310 . Specifically, a series electrically insulated flow piping  350  is arranged to provide a series of passageways  315 ,  320 ,  317  and  322 . These passageways are separated by a series of baffle plates  325 ,  326  and  327 . 
         [0073]    Center electrode  310  is connected to a source of electricity (not shown) via a connector  355 . 
         [0074]    Walls  305  of the fluid treatment system are electrically isolated from excimer radiation lamp assembly  300  via insulating element  360 . 
         [0075]    Excimer radiation lamp assembly  300  may be operated in a manner similar to that discussed above with reference to  FIG. 3 . An advantage of this approach is that it permits the use of a partially conductive fluid (e.g., tap water). As the length of the circuit is increase the resistance to current is also increased. 
         [0076]    With reference to  FIG. 5 , there is illustrated an excimer radiation lamp assembly  400 . Excimer radiation lamp assembly  400  is attached to a wall  401  of a fluid treatment system. 
         [0077]    Excimer radiation lamp assembly  400  comprises an annular radiation emitting element  405  having disposed coaxially therein a center electrode/heat pipe  410 . Center electrode/heat pipe  410  is connected to a heat transfer element  412 . 
         [0078]    Center electrode/heat pipe  410  is connected to a source of electricity (not shown) via an electrical connector  455 . 
         [0079]    The general operation of heat pipes is known in the art. Thus, a heat pipe operates by transferring heat from an element connected to a distal portion of the heat pipe. The heat transferred to the distal portion of the heat pipe causes evaporation of a fluid (e.g., water, mercury and the like) in an enclosure in the heat pipe to form a vapour. This vapour is then transported to a proximal portion of the heat pipe after which the fluid is condensed to form a liquid in the proximal portion of the heat pipe. During condensation of the liquid, heat is liberated from the proximal portion of the heat pipe. The condensed liquid is then transported back to the distal portion of the heat pipe via a wick or capillary structure in the heat pipe. In some cases, it is possible to eliminate the wick, particularly if the heat pipe is oriented in a substantially vertical manner thereby allowing gravity to facilitate transport of the condensed liquid back to the distal portion of the heat pipe. 
         [0080]    The heat pipe includes a container (or enclosure) to isolate the working fluid (and create a partial internal vacuum) from the outside environment. The selection of the container material depends on factors such as: compatibility with the working fluid and external environment, strength to weight ratio, thermal conductivity, ease of fabrication, porosity and the like. 
         [0081]    The selection of the working fluid is conventional. The factors involved in selecting the working fluid include: compatibility with wick and enclosure materials, good thermal stability, wettability of wick and enclosure materials, vapour pressure not too high or low over the operating temperature range, high latent heat, high thermal conductivities, low liquid and vapour viscosities, high surface tension, the operating temperature range and acceptable freezing or pour point. 
         [0082]    The wick or capillary structure is a porous structure and can be made of a material such as steel, aluminum, nickel or copper. It is also possible to use so-called metal foams and felts. As stated above, in certain cases, the use of a wick or capillary structure is optional. 
         [0083]    In the present excimer radiation lamp assembly, a heat pipe may be used advantageously to transport or transfer heat away from the central area of the radiation emitting portion of the lamp assembly to an area remote therefrom. In some embodiments, it is desirable to dissipate the transferred heat from the remote area, for example, by using a reactor wall, air cool fins, active cooling (e.g., water loops around the distal end of the heat pipe) and the like. 
         [0084]    With reference to  FIG. 6 , there is illustrated an excimer radiation lamp assembly  500  which is a modification of excimer radiation lamp assembly  400  shown in  FIG. 5 . Specifically, in excimer radiation lamp assembly  500 , the heat pipe is actually integral with the lamp and there is no gap between the center electrode and annular radiation emitting portion  505 . In  FIG. 6 , the heat pipe is denoted by the reference numeral  506 . Also, a distal portion of excimer radiation lamp assembly  500  comprises a vacuum tight element  507 . 
         [0085]    A proximal portion of excimer radiation lamp assembly  500  comprises a vacuum tight cap and thermal connection element  508 . 
         [0086]    Excimer radiation lamp assembly  500  may be operated as described above. 
         [0087]    With reference to  FIG. 7 , there is illustrated an excimer radiation lamp assembly  600  comprising a center electrode  610  disposed coaxially within an annular radiation emitting portion  605 . As shown in  FIG. 8 , a compressible material  611  is disposed between the surfaces of center electrode  610  and the inner surface of annular radiation emitting portion  605 . The provision of compressible material  611  compensates for expansion/contraction of center electrode and/or annular radiation emitting portion  605  as excimer radiation lamp assembly  600  is heated. 
         [0088]    The precise nature of compressible material  611  is not particularly restricted. Physically, compressible material  611  may be a gel, a foam element or a fluid. 
         [0089]    With reference to  FIGS. 9 and 10 , there is illustrated an excimer radiation lamp assembly  700  comprising an annular radiation emitting portion  705  having disposed coaxially therein a center electrode  710 . 
         [0090]    Excimer radiation lamp assembly  700  is disposed between a pair of flanges  712 . An O-ring  713  (or similar sealing element) is disposed between flanged  712  and annular radiation emitting portion  705 . 
         [0091]    A constant load spring  714  is disposed on an opposed surface of flanged  712  at one end of excimer radiation lamp assembly  700 . 
         [0092]    Constant load spring  714  is used as part of a clamping device for compression of excimer radiation lamp assembly  710  to increase lamp strength under bending stresses, particularly when excimer radiation lamp assembly  700  is disposed in a flow of fluid with significant hydraulic head. 
         [0093]    With reference to  FIGS. 11-13 , there is illustrated an excimer radiation lamp assembly  800  having a first end  810  and a second end  850 . An annular radiation emitting portion  815  is disposed between first end  810  and second end  850 . 
         [0094]    With particular reference to  FIGS. 12 and 13 , first end  810  and second end  850  comprise a dielectric barrier element  820  which extends along the interior of annular radiation emitting portion  815 . A cooling passageway  825  is provided in dielectric barrier element  820  for receiving a cooling element (not shown for clarity) such as those described above—e.g., a cooling circuit, a heat pipe and the like. 
         [0095]    An electrode element  830  is disposed between annular radiation emitting portion  815  and dielectric barrier element  820 . Electrode element  830  is connecting to an electrical connector  830  by a pair of electrical leads  840 . 
         [0096]    Preferably dielectric barrier element  820  is an electrical isolation element that serves to separate the high voltage of the hot electrode from the cooling element. This allows the cooling element to be grounded, which greatly increases the safety of and simplifies the design of the cooling system. This is a significant improvement over the known designs, which typically have a high voltage potential on the cooling element. 
         [0097]    Dielectric barrier element  820  preferably is configured to have appropriate electrical properties to minimize losses from (high voltage) electrode  830  to the grounded cooling element. Such configuration of dielectric barrier element  820  is within the purview of a person skilled in art. 
         [0098]    Dielectric barrier element  820  preferably is also configured to have appropriate thermal properties in order to promote good heat transfer from the annular radiation emitting portion  815  and electrode  830  to the cooling element (not shown for clarity). Such configuration of dielectric barrier element  820  is within the purview of a person skilled in art. 
         [0099]    All publications, patents and patent applications referred to herein are incorporated by reference in their entirety to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated by reference in its entirety. For greater, two copending U.S. provisional patent applications 60/752,024 (Gowlings Ref: T8469433US) and 60/752,026 (Gowlings Ref: T8469434US), both filed on Dec. 21, 2005 in the names of the present inventors, are each incorporated herein by reference.