Abstract:
There is disclosed an optical radiation sensor system. The system includes a sensor device and a cleaning device. The sensor device detects and responds to radiation from a radiation field and includes a surface that is movable with respect to the radiation field between a first position in which the surface is in the radiation field and a second position in which at least a portion of the surface is out of the radiation field. The cleaning device operates to remove fouling materials from at least a portion of the surface in the second position. The cleaning device may be a chemical cleaning device, a mechanical cleaning device or a combined chemical/mechanical device.

Description:
This application claims benefit of U.S. patent application Ser. No. 60/157,010, filed Oct. 1, 1999, incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Generally, the present invention relates to an optical radiation sensor system. 
     2. Description of the Prior Art 
     Optical radiation sensors are known and find widespread use in a number of applications. One of the principal applications of optical radiation sensors is in the field of ultraviolet radiation fluid disinfection systems. 
     It is known that the irradiation of water with ultraviolet light will disinfect the water by inactivation of microorganisms in the water, provided the irradiance and exposure duration are above a minimum “dose” level (often measured in units of microWatt seconds per square centimetre). Ultraviolet water disinfection units such as those commercially available from Trojan Technologies Inc. under the tradenames UV700 and UV8000, employ this principle to disinfect water for human consumption. Generally, water to be disinfected passes through a pressurized stainless steel cylinder which is flooded with ultraviolet radiation. Large scale municipal waste water treatment equipment such as that commercially available from Trojan Technologies Inc. under the trade-names UV3000 and UV4000, employ the same principal to disinfect waste water. Generally, the practical applications of these treatment systems relates to submersion of treatment module or system in an open channel wherein the wastewater is exposed to radiation as it flows past the lamps. For further discussion of fluid disinfection systems employing ultraviolet radiation, see any one of the following: 
     U.S. Pat. No. 4,482,809, 
     U.S. Pat. No. 4,872,980, 
     U.S. Pat. No. 5,006,244, 
     U.S. Pat. No. 5,418,370, 
     U.S. Pat. No. 5,539,210, and 
     U.S. Pat. No. 5,590,390. 
     In many applications, it is desirable to monitor the level of ultraviolet radiation present within the water under treatment. In this way, it is possible to assess, on a continuous or semi-continuous basis, the level of ultraviolet radiation, and thus the overall effectiveness and efficiency of the disinfection process. 
     It is known in the art to monitor the ultraviolet radiation level by deploying one or more passive sensor devices near the operating lamps in specific locations and orientations which are remote from the operating lamps. These passive sensor devices may be photodiodes, photoresistors or other devices that respond to the impingent of the particular radiation wavelength or range of radiation wavelengths of interest by producing a repeatable signal level (in volts or amperes) on output leads. 
     Conventional ultraviolet disinfection systems often incorporate arrays of lamps immersed in a fluid to be treated. Such an arrangement poses difficulties for mounting sensors to monitor lamp output. The surrounding structure is usually a pressurized vessel or other construction not well suited for insertion of instrumentation. Simply attaching an ultraviolet radiation sensor to the lamp module can impede flow of fluid and act as attachment point for fouling and/or blockage of the ultraviolet radiation use to treat the water. Further, there is an increasing desire to utilize ultra-violet disinfection systems to treat relatively low quality water—e.g., low quality waste water from municipal waste water treatment plants. This creates a problem in that those components of the disinfection system which are in continued contact with the waste water will accumulate fouling materials. The accumulation of fouling materials on an ultra-violet radiation sensor can lead to the conveyance of misleading information to the operator about the status of the ultra-violet radiation sources. In other words, as the sensor accumulates fouling materials, its ability to sense ultra-violet radiation will be reduced. A corresponding signal would be sent to the operator who might mistake the signal for an indication that one or more of the radiation sources is not operating. Further, placing a cleaning mechanism for the sensor surface in the flow of fluid is problematic since this can impede the flow of fluid and act as an attachment point as described hereinabove. 
     Accordingly, it would be desirable to have an optical radiation sensor system having a surface which could be periodically cleaned while the fluid treatment system is in operation. It would be particularly advantageous if the surface of the sensor device could be cleaned in a manner which minimized or avoided impeding of the flow of fluid through the fluid treatment system. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a novel radiation source module which obviates or mitigates at least one of the above-mentioned disadvantages of the prior art. 
     It is another object of the present invention to provide a novel radiation source assembly which obviates or mitigates at least one of the above-mentioned disadvantages of the prior art. 
     Accordingly, in one of its aspects, the present invention provides an optical radiation sensor system for detecting radiation from a radiation field, the device comprising: 
     a sensor device for detecting and responding to radiation from the radiation field, the sensor device comprising a surface, the surface being movable with respect to the radiation field between a first position in which the surface is within the radiation field and a second position in which at least a portion of the surface is without the radiation field; and 
     a cleaning device for removing fouling materials from at least a portion of the surface in the second position. 
     Thus, the present inventors have discovered an optical radiation sensor system which allows for in situ cleaning of the surface of the sensor device which receives radiation. Generally, it is preferred that the present optical radiation sensor system achieves such cleaning of the surface while the surface is being moved or has been moved with respect to the field of radiation. Many advantages accrue from this approach. First, cleaning of the surface may be achieved independently of the flow of fluid thereby avoiding leakage of cleaning agent (if used) into the flow of fluid and minimizing or obviating hydraulic head loss penalties which would result if the structural elements used to clean the surface of the sensor device were placed in the flow of fluid. Second, servicing of the sensor device is facilitated. Third, the present approach facilitates the use of mechanical cleaning, chemical cleaning or a combination of chemical/mechanical cleaning of the surface. Other advantages will become apparent to those of skill in the art. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the present invention will be described with reference to the accompanying drawings, in which: 
     FIG. 1 illustrates a schematic of a top view of a first embodiment of the present optical radiation sensor system in a first position; 
     FIG. 2 illustrates a side elevation, in cross section, of the system illustrated in FIG. 1; 
     FIG. 3 illustrates a top view of the FIG. 1 embodiment in a second position; 
     FIG. 4 illustrates a side elevation, in cross section, of FIG. 3; 
     FIG. 5 illustrates a schematic of a top view of a second embodiment of the present optical radiation sensor system in a first position; 
     FIG. 6 illustrates a side elevation, in cross section, of the system illustrated in FIG. 
     FIG. 7 illustrates a top view of the FIG. 5 embodiment in a second position; and 
     FIG. 8 illustrates a side elevation, in cross-section, of FIG.  7 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIGS. 1-4 illustrate a first embodiment of the present optical radiation sensor system. FIGS. 1 and 2 illustrate the first embodiment of the system in the first or “viewing” position, while FIGS. 3 and 4 illustrate the same embodiment in the second “cleaning” position. 
     Thus, with reference to FIGS. 1-4, there is illustrated an optical radiation sensor system  100  comprising a housing  110 . Disposed in housing  110  is a first chamber  115  and a second chamber  120 . Interposed between first chamber  115  and second chamber  120  is a sensor housing  125 . 
     Sensor housing  125  is connected to a motor  135  via an axle  130 . Disposed in sensor housing  125  is a sensor photo-diode  140 . Sensor photo-diode  140  has connected to it an electrical cable  145 . Preferably, sensor photo-diode is one which detects and responds to ultraviolet radiation, more preferably one which detects and responds to radiation having a wavelength in the range of from about 100 to about 400 nm, most preferably, one which detects and responds to radiation having a wavelength in the range of from about 250 to about 260 nm. Electrical cable  145  emanates out of a conduit  150  emanating from housing  110 . Also disposed in sensor housing  125  is a window  155 . It is preferred that window  155  form a fluid tight seal with respect to sensor housing  125 . This can be achieved in a conventional manner. Further, it is preferred that window  155  be constructed from a radiation transparent material (e.g., quartz and the like). 
     In the illustrated embodiment, second chamber  120  of housing  110  is sealingly attached to an outer wall  160  of a fluid treatment chamber  165 . Disposed within fluid treatment chamber  165  is a radiation source  170 . 
     While not shown, attached to the distal end of first chamber  115  of housing  110  is a pressurized source of cleaning agent (e.g., acetic acid, etc.), mild inorganic acids and the like which serves to fill first chamber  115 . 
     As will be apparent, in FIGS. 1 and 2, window  155  is adjacent to second chamber  120 , whereas in FIGS. 3 and 4, window  155  is adjacent to first chamber  115 . 
     In use, a flow of fluid (preferably water) is treated in fluid treatment chamber  165 . Thus, when radiation source  170  is in use, a field of radiation is created as shown by arrows A. As shown in FIGS. 1 and 2, a portion of the radiation from the field of radiation enters second chamber  120  and impinges on window  155 . This radiation is sensed by sensor photo-diode  140  and an appropriate signal is sent to the operator about the level of radiation. The design of a control system for sensing radiation is conventional in the art as is the use thereof by an operator. 
     After some use, and depending on the type of fluid being treated, window  155  becomes fouled with fouling materials. When it is desired to clean window  155 , motor  135  is actuated to rotate axle  130  thereby rotating sensor housing  125  to a second position as shown in FIGS. 3 and 4. In this second position, window  155  having fouling materials thereon is exposed to cleaning agent in first chamber  115 . The cleaning agent serves to remove the fouling materials from window  155 . The length of time for exposing window  155  to the cleaning agent in first chamber  115  can be readily determined based on historical performance of the system, the type of fluid being treated and the specific nature of the cleaning agent filling first chamber  115 . Once the fouling materials have been substantially removed from window  155 , motor  135  is actuated again to rotate axle  135  thereby returning window  155  to the first position illustrated in FIGS. 1 and 2 thereby putting the sensor online for detection of radiation from the radiation field. 
     FIGS. 5-8 illustrate a second embodiment of the present optical radiation sensor system. FIGS. 5 and 6 illustrate the second embodiment of the system in the first or “viewing” position, while FIGS. 7 and 8 illustrate the same embodiment in the second or “cleaning” position. 
     Thus, with reference to FIGS. 5-8, there is illustrated an optical radiation sensor system  200  comprising a housing  210 . Disposed in housing  210  is a first chamber  215  and a second chamber  220 . Interposed between first chamber  215  and second chamber  220  is a ball housing  225 . 
     Ball housing  225  is connected to a motor  235  via an axle  230 . Disposed in ball housing  225  is a sensor photo-diode  240 . Sensor photo-diode  240  has connected to it an electrical cable  245 . Electrical cable  245  emanates out of a conduit  250  emanating from housing  210 . Also disposed in ball housing  225  is a window  255 . As shown, window  255  assumes a portion of the spherical shape of sensor housing  225 . It is preferred that window  255  form a fluid tight seal with respect to ball housing  225 . This can be achieved in a conventional manner. Further, it is preferred that window  255  be constructed from a radiation transparent material (e.g. quartz and the like). 
     In the illustrated embodiment, second chamber  220  of housing  210  is sealingly attached to an outer wall  260  of a fluid treatment chamber  265 . Disposed within fluid treatment chamber  265  is a radiation source  270 . 
     As further illustrated, disposed in housing  210  is an O-ring  275  made from a polymer material such as rubber, plastic and the like. O-ring  275  serves to create a fluid tight seal between ball housing  225  and housing  210 . 
     As will be apparent in FIGS. 5 and 6, window  255  is adjacent to second chamber  220  whereas in FIGS. 7 and 8 window  255  is adjacent to first chamber  215 . 
     In use, a flow of fluid (preferably water) is treated in fluid treatment chamber  265 . Thus, when radiation source  270  is in use, a field of radiation is created as shown by arrows A. As shown in FIGS. 5 and 6, a portion of the radiation from the field of radiation enters second chamber  220  and impinges on window  225 . This radiation is sensed by sensor photo-diode  240  and appropriate signal is sent to the operator about the level of radiation. The design of a control system for sensing radiation is conventional in the art as the use thereof by an operator. 
     After some use, and depending on the type of fluid being treated, window  255  becomes fouled with fouling materials. When it is desired to clean window  255 , motor  235  is actuated to rotate axle  230  thereby rotating ball housing  225  to a second position as shown in FIGS. 7 and 8. As illustrated, in the second position, window  255  faces first chamber  215 . During this rotation, window  255  having fouling materials thereon is wiped by O-ring  275 . This interaction between window  255  and O-ring  275  results in mechanical cleaning or wiping of the fouling materials from window  255 . Optionally, it is possible to combine this arrangement with the use of a chemical cleaning system as described herein above with reference to FIGS. 1-4. Once the fouling materials have been substantially removed from window  255 , motor  235  is actuated to rotate axle  235  thereby returning window  255  to the first position illustrated in FIGS. 5 and 6 thereby putting the sensor on line for detection of radiation from the radiation field. 
     While the present invention has been described with reference to preferred and specifically illustrated embodiments, it will of course be understood by those skilled in the arts that various modifications to these preferred and illustrated embodiments may be made without the parting from the spirit and scope of the invention. For example, while the present invention has been illustrated with reference to a fluid treatment system similar in general design to the one specifically taught in U.S. Pat. No. 5,504,335 (all Figures), it is possible to employ the present radiation source assembly in a module such as the one illustrated in U.S. Pat. Nos. 5,418,370 , 5,539,210 and 5,590,390—i.e., in a fluid treatment system having an open irradiation zone in which the fluid being treated is not physically confined as it passes through the irradation zone. Further, it is possible to employ the present optical radiation sensor system in a fluid treatment which such as the one specifically taught in U.S. Pat. Nos. 5,418,370, 5,539,210 and 5,590,390—i.e., in a fluid treatment system which is a hybrid of the open and closed fluid treatment systems described above. Further a variety of cleaning devices may be used in the present optical radiation sensor system, including (without limitation): mechanical brushes, jets, cleaning agents comprising abrasive particles, cellular materials and the like. Other modifications which do not depart from the spirit and scope of the present invention will be apparent to those skilled in the art. 
     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.