Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD OF CLEANING FOULING MATERIALS FROM
A RADIATION MODULE
In one of its aspects, the present invention relates to a method of
cleaning fouling materials from a radiation module.
In another of its aspects, the present invention relates to a
radiation module for use in a fluid treatment system, more particularly
a self-cleaning radiation source module.
In yet another of its aspects, the present invention relates to a
fluid treatment system, more particularly to a self-cleaning fluid
treatment system.
In another of its aspects, the present invention relates to method
of treating a fluid in a fluid treatment system comprising a radiation
source module, more particularly to a method for treating a fluid in
manner which obviates formation of fouling materials on the radiation
source module during treatment of the fluid.
Fluid treatment devices and systems are known. For example,
United States patents 4,482,809, 4,872,980, 5,006,244 and 5,418,370
(all assigned to the assignee of the present invention)
all describe gravity
fed fluid treatment syster:_s wlhich employ ultraviolet (UV) radiation to
inactiv4tV microora: nisms present in t.he fluid.
The devices and systems described in the '809, '980 and '244
patents generally include several UV lamps each of which are mounted
within sleeves extending between two support arms of the frames. The
frames are immersed into the fluid to be treated which is then irradiated
as required. The amount of radiation to which the fluid is exposed is
determined by the proximity of the fluid to the lamps. One or more UV
sensors may be employed to monitor the UV output of the lamps and the
fluid level is typically controlled, to some extent, downstream of the
treatment device by means of level gates or the like.
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However, disadvantages exist with the above-described systems.
Depending on the quality of the fluid which is being treated, the sleeves
surrounding the UV lamps periodically become fouled with foreign
materials, inhibiting their ability to transmit UV radiation to the fluid.
When fouled, at intervals which may be determined from historical
operating data or by the measurements from the UV sensors, the sleeves
must be manually cleaned to remove the fouling materials. Regardless
of whether the UV lamp frames are employed in an open, channel-like
system or a closed system, cleaning of the sleeves is impractical.
In open, channel-like systems, the modules comprising the sleeves
are usually removed from the channel and immersed in a separate tank
containing a suitable cleaning fluid. In closed systems, the device must
be shut down and the sleeves are thereafter cleaned by charging with a
suitable cleaning fluid or by removal of the lamps and sleeves in the
manner described for the open, channel-like systems. In either type of
systems the operator must accept significant downtime of the system
and/or invest significant additional capital to have in place sufficient
redundant systems with appropriate control systems to divert the flow of
fluid from the systems being cleaned.
The system described in the '370 patent is a significant advance
in the art in that it obviates a number of disadvantages deriving from the
'809, '980 and '244 patents. More specifically, in one of its
embodiments, the system described in the '370 patent includes the
provision of a cleaning apparatus for a radiation source assembly in the
fluid treatment system. The cleaning apparatus comprises a cleaning
sleeve engaging a portion of the exterior of the radiation source
assembly and movable between a retracted position and an extended
position. In the retracted position, a first portion of the radiation source
assembly is exposed to a flow of fluid to be treated. In the extended
, position, the first portion of the radiation source assembly is covered by
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the cleaning sleeve. The cleaning sleeve includes a chamber in contact
with the first portion of said radiation source assembly and is supplied
with a cleaning solution suitable to remove undesired materials from the
first portion of the radiation source assembly.
While the cleaning apparatus described in the '370 patent
represents an advance in the art, it is relatively complicated and
expensive to construct necessitating investment of more capital to build
a fluid treatment plant. Further, in certain installations, the apparatus
creates more hydraulic headloss in the flow of fluid being treated.
Accordingly, it would be desirable to have a cleaning apparatus which
is relatively simple and inexpensive to construct while maintaining the
performance characteristics of the cleaning device described in the '370
patent.
It is an object of the present invention to provide a novel method
of cleaning fouling materials from a radiation module.
It is another object of the present invention to provide a novel
radiation module.
It is yet another object of the present invention to provide a novel
fluid treatment device which obviates or mitigates at least one of the
disadvantages of the prior art.
It is yet another object of the present invention to provide a novel
method for treating a fluid which obviates or mitigates at least one of the
disadvantages of the prior art.
Accordingly, in one of its aspects, the present invention provides
a method of cleaning fouling materials from a radiation module, the
method comprising the steps of:
(i) immersing at least a portion of the radiation module in a fluid;
and
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(ii) subjecting the radiation module to vibration at a frequency
sufficient to substantially inhibit fouling materials adhering to the
radiation module.
In another of its aspects, the present invention provides a
radiation module for use in a fluid treatment system comprising:
a support member for mounting the module in the fluid treatment
system;
at least one radiation assembly extending from the support
member; and
vibration generation means associated with the at least one
radiation assembly.
In yet another of its aspects, the present invention provides a fluid
treatment system comprising a fluid inlet, a fluid outlet and a fluid
treatment zone disposed between the fluid inlet and the fluid outlet, and
at least one radiation module comprising a support member, at least one
radiation assembly extending from the support member into the fluid
treatment zone, and vibration generation means associated with the at
least one radiation assembly.
In yet another of its aspects, the present invention provides a
method of treating a fluid in a fluid treatment system comprising a fluid
inlet, a fluid outlet and a fluid treatment zone disposed between the fluid
inlet and the fluid outlet, and at least one radiation module comprising
a support member, at least one radiation assembly extending from the
support member into the fluid treatment zone, and vibration generation
means associated with the at least one radiation assembly, the method
comprising the steps of:
(i) providing a flow of fluid to the fluid inlet;
(ii) feeding the flow of fluid from the fluid inlet to the fluid
treatment zone;
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(iii) exposing the flow of fluid to radiation in the fluid treatment
zone;
(iv) operating the vibration generation means at a frequency
sufficient to clean the at least one radiation assembly; and
(v) feeding the flow of fluid to the fluid outlet.
Thus, in one of its aspects, the present invention relates to a
radiation module for use in a fluid treatment system. As used
throughout this specification, the term "radiation module" is intended to
cover modules which emit or sense radiation. Thus, in a preferred
embodiment, the present radiation module is a radiation source module
which emits radiation in a fluid treatment system. In another
embodiment, the present radiation module is a radiation sensor module
which detects radiation being emitted from another source.
Embodiments of the present invention will be described with
reference to the accompanying drawings, in which:
Figure 1 illustrates an elevation, partially cut away of a first
embodiment of a radiation source module in accordance with the present
invention;
Figure 2 illustrates a top view of the radiation source module
illustrated in Figure 1;
Figure 3 illustrates an end view of the radiation source module
illustrated in Figure 1; and
Figure 4 illustrates an expanded view of the area indicated at A
in Figure 1.
In the Figures, like reference numerals from one Figure to
another are intended to designated like parts.
Preferably, the present radiation module is a radiation source
module which is essentially self-cleaning. As used throughout this
specification, the terms "self-cleaning" and "cleaning" are intended to
have a broad defniition and encompass either or both of the removal of
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fouling materials from the radiation source assembly in the module and
inhibition of fouling materials adhering to the radiation source assembly
in the module. In most cases, the latter will be occurring if the
vibration generation means is operated during the entire period of fluid
treatment (i.e. continuous mode). However, it is clearly contemplated
that the radiation source module can be operated in a manner wherein
the vibration generation means is operated periodically during fluid
treatment (i.e. semi-continuous mode). In this scenario, the fouling
materials which became adhered to the radiation source assembly while
the vibration generation means was not operated are quickly removed
when the vibration generations means is activated.
The vibration generation means is associated with the radiation
source assembly in the module and provides a minute, mechanical
vibration of the radiation source assembly. Ideally, a surface of the
vibration generation means abuts an end of the surface of the radiation
source assembly which is exposed to (and thus likely to become fouled
in) fluid and opposed surface of the vibration generation means abuts a
rigid surface of the radiation source module. This will serve maximize
translation of the vibration energy from the vibration generation means
toward a free end of the radiation source assembly. The abutment can
be direct or indirect. Preferably, a rigid insulating member, which is
not a vibration generation means itself, is disposed between the vibration
generation means and the rigid surface of the radiation source module
and the radiation source assembly, respectively. This will provide an
electrical insulation between the radiation source assembly and the rigid
surface of the radiation source module. As will be apparent to those of
skill in the art, vibration occurs in a reciprocal manner. Preferably,
vibration is effected axially with respect to the radiation source
assembly. Such vibration may be effected by utilizing a piezo-electric
transducer, preferably a piezo-electric ceramic transducer. Piezo-electric
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ceramic transducers have been conventionally used in sonar applications.
A suitable piezo-electric ceramic transducer useful in the present
radiation source module is commercially available from EDO
Corporation (Salt Lake City, Utah) and consists essentially of a ceramic
component which meets the specifications of U. S. Navy Type 1(I) or
U.S. Navy Type 3(III). As will be apparent to those of skill in the art,
a ceramic meeting the specifications of U.S. Navy Type 1 is a hard lead
zirconate titanate with a Curie point greater than about 310 C and a
ceramic meeting the specifications of U.S. Navy Type 3 is a very hard
lead zirconate titanate with a Curie point greater than about 290 C.
Detailed specifications of these ceramic specifications can be found in
published Department of Defense Military Standard DOD-STD
1376A(SH), dated February 28, 1984, the contents of which are hereby
incorporated by reference.
Preferably, the radiation source assembly comprises, as the
radiation source, an ultraviolet lamp. More preferably, the radiation
source assembly further comprises a sleeve, most preferably a quartz
sleeve, about the ultraviolet lamp which defines an insulating gap
between the ultraviolet lamp and fluid being treated. A preferred sleeve
has a closed end distal the support member and an open end sealably
engaged to the support member. When this arrangement is used, it is
preferred to use, as the vibration generation means, an annular piezo-
electric transducer disposed between an abutment surface in the support
member and the open end of the sleeve.
Generally, the vibration generation means, preferably a piezo-
electric transducer, most preferably an annular piezo-electric transducer,
is one which can be operated at a frequency in the range of from about
1 kHz to about 100 kHz, preferably from about 10 kHz to about 20
kHz, more preferably about 10 kHz to about 15 kHz.
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The present radiation source module is ideally suited to be used
in a fluid treatment system comprising a fluid inlet, a fluid outlet and a
fluid treatment zone disposed between the fluid inlet and the fluid outlet.
The fluid treatment system can be an open system or a closed system.
As used throughout this specification, the term "closed system",
in relation to treatment (i.e. irradiation) of a fluid, is intended to
encompass a system characterized by a treatment zone (i.e. the zone in
which the fluid is irradiated) in which the flow of fluid is pressurized
and substantially completely contained in an enclosure throughout
treatment. The source of pressurization of the flow of fluid is not
particularly restricted. For example, the pressurize can be generated by
a pump and/or by the action of gravity. Examples of such a closed
system can be found in incorporated United States patent number
5,418,370 (NB. this system is designated as a closed system by virtue
of the treatment/irradiation zone), and copending Canadian patent
application serial number 2,160,729, in the name of the present
inventor and applicant.
Further, as used throughout this specification, the term "open
system", in relation to treatment (i.e. irradiation) of a fluid, is intended
to encompass a system characterized by a treatment zone in which the
flow of fluid is contained and treated (i.e. irradiated) in an open vessel
(e.g. a channel) which is not completely filled by the fluid. Examples
of such an open system can be found in incorporated United States
patents 4,482,809, 4,872,980 and 5,006,244.
The present radiation source module is ideally used in a closed
system for fluid treatment since such systems present the greatest
challenge to clean will minimize downtime and the need for redundant
systems.
In one preferred embodiment, the closed fluid treatment system
has a fluid treatment zone which comprises a housing and at least one
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radiation source module comprising a radiation source sealably
connected to the support member, the support member sealably mounted
to the housing. Preferably (but not necessarily), the radiation source is
disposed substantially parallel to the flow of fluid. More preferably, the
fluid inlet, the fluid outlet and the fluid treatment zone have substantially
the same cross-section and are arranged in a substantially collinear
manner. Ideally, the housing is a substantially elongate cylinder having
a substantially circular cross-section. In this embodiment, the end of the
support member distal the radiation source may comprise a mounting
plate sealably connected to the housing. Preferably, the closed fluid
treatment system comprises a plurality of radiation source modules
mounted circumferentially, more preferably equidistant from one
another, about the housing to define a radiation source ring. If desirable
the housing may comprise a plurality of such radiation source rings.
The number of radiation source rings and the number of modules in each
ring varies from installation to installation and may be selected by a
person skilled in the art on the basis of a consideration of one or more
of the following factors: the cross-sectional area of the housing, the
volume of fluid passing through the housing, the radiation output from
each module, the total amount of radiation required in the system and
the like. This embodiment of the closed fluid treatment system may be
used "in-line" in conventional fluid (e.g. water) piping. Depending on
the particular application, the piping can be up to about 4 in. diameter
for domestic applications, or 1 ft. to 3 ft. diameter or more for
municipal applications.
In another preferred embodiment, the closed fluid treatment
system is gravity fed has a fluid treatment zone which comprises a
closed cross-section to confine fluid to be treated within a predefined
maximum distance from the radiation source assembly. As used herein,
the term "gravity fed" encompasses systems wherein the hydraulic head
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of the fluid is obtained from changes in the altitude of the fluid. It will
be understood that such systems comprise both systems which are
naturally gravity fed and systems wherein the altitude of the fluid is
altered via pumps or other mechanical means to provide a gravity feed.
Preferably, the radiation source assembly is elongate and has a
longitudinal axis substantially parallel to the direction of the fluid flow
through the fluid through the fluid treatment zone. The cross-sectional
area of the fluid treatment zone is preferably less than that of the fluid
inlet and the fluid outlet. In most cases, will result in a flow of fluid
have a first velocity in the fluid inlet, a second velocity in the fluid
treatment zone and a third velocity in the fluid outlet. Ideally, the
second velocity (i.e. in the fluid treatment zone) is greater than at least
one, and preferably both, of the first velocity and the third velocity.
Preferably, the third velocity is substantially equal to the first velocity.
More preferably, the cross-sectional area of the fluid treatment zone is
less than the cross-sectional area of the fluid inlet and the fluid treatment
zone is disposed in a treatment zone including a first transition region
connecting the fluid inlet to the fluid treatment zone, the transition
region reducing pressure loss in the fluid between the inlet and the fluid
treatment zone, and serving to increase the velocity of the fluid. More
preferably, the cross-sectional area of the fluid treatment zone is less
than the cross-sectional area of the fluid outlet and the fluid treatment
zone is disposed in a treatment zone including a second transition region
connecting the fluid outlet to the fluid treatment zone, the transition
region reducing pressure loss in the fluid between the outlet and the fluid
treatment zone, and serving to decrease the velocity of the fluid. Most
preferably, the fluid treatment zone includes first and second transition
regions.
With reference to the Figures, there is illustrated a radiation
source module 10 comprising a support member 15, a radiation source
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assembly 20 extending from support member 15 and a mounting plate
25 for affixing radiation source module 10 in the fluid treatment system.
Radiation source assembly 20 includes a concentric reducer 30
which can be welded to or made integral with support member 15.
Affixed to concentric reducer 30 is a ring 35 to which is affixed a
mounting sleeve 40. The end of mounting sleeve 40 distal concentric
reducer 30 has a threaded portion 45. Disposed within mounting sleeve
40 is an inner sleeve 50 having a threaded portion 55 to which is
engaged a cap nut 60. Inner sleeve 50 comprises suitable notches to
receive a pair of resilient 0-rings 65,70. The end of inner sleeve 50
distal concentric reducer 30 abuts a resilient, tapered sealing ring 75.
A threaded mounting nut 80 engages threaded portion 55 of mounting
sleeve 40 and abuts tapered sealing ring 75. Threaded mounting nut 80
is provided with torquing receptacles 85 which receive a suitable tool
useful for torquing mounting nut 80 into sealing engagement with
mounting sleeve 40.
Disposed within inner sleeve 50 is an annular piezo-electric
ceramic transducer 90 which is a laminate structure. made up of a
plurality of individual annular piezo-electric ceramic transducers (not
shown) adhered together. One end of transducer 90 abuts inner sleeve
50 and the other end of transducer 90 abuts the open end of a quartz
sleeve 95. As illustrated, the opposite end of quartz sleeve 95 is closed.
It will be appreciated by those of skill in the art that a double open-
ended quartz sleeve could be used. Disposed within quartz sleeve 95 is
a radiation source 100. Ideally, the radiation source is an ultraviolet
lamp. The ultraviolet lamp is not particularly restricted and the choice
thereof is within the purview of a person skill in the art. A pair of
spacers 105,110 are disposed within quartz sleeve 95 and serve to centre
and hold in place radiation source 100 within quartz sleeve 95.
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A pair of electrical leads 115,120 emanate from radiation source
100 and are fed to a first connector 135. Another pair of electrical leads
125,130 emanate from transducer 90 and are also fed to first connector
135. First connector 135 is connected to a second connector 140.
Emanating from second connector 140 is an electrical conduit 145 which
is fed through concentric reducer 30, support member 15 and mounting
plate 25. Electrical conduit 145 is connected to a suitable power supply
and control system (not shown) which are conventional in the art.
Partially surrounding each first connector 135 and second
connector 150 is an insulating ring 150. Insulating ring 150 is made of
an electrically non-conductive material and serves to minimize or
elimination the occurrence of arcing across the electrical connection
made by engagement of first connector 135 and second connector 140.
Preferably, insulating ring 150 is non-resilient and made from hard
rubber or plastic (e.g. DelrinTM).
In the illustrated embodiment, mounting plate 25 is curved and
comprises a plurality of apertures 155. This embodiment of radiation
source module 10 may be used advantageously in a pressurized, closed
system such as the one described in incorporated copending United
States patent application S.N. 08/323,808 , filed on October 17, 1994
in the name of the present inventor, now patent number *. In this
embodiment, radiation source assembly 20 is inserted in a housing
through an aperture of smaller size than but similar shape to mounting
plate 25. Bolts emerge from the housing in a pattern similar to the
pattern of apertures on mounting plate 25. Radiation source module is
then affixed in place by torquing nuts on each bolt in a manner which
provides a hermetic seal by means of an 0-ring (or other sealing ring,
not shown) between mounting plate 25 and the housing.
Radiation source module may be constructed in the following
manner. Initially, insulating ring 150 is placed in the end of inner
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sleeve 50 and held in place by engagement of cap nut 60 to threaded
portion 55 of inner sleeve 50. First connector 135 is partially inserted
into insulating ring 150 and transducer 90 is placed in abutment with
inner sleeve 50. 0-ring 70 is placed the notch in inner sleeve 50 and
quartz sleeve 95 (containing radiation source 100) is inserted in inner
sleeve 50 such that it abuts transducer 90. 0-ring 65 and tapered sealing
ring 75 are position in place with respect to inner sleeve 50 which is
then inserted in mounting sleeve 40. Prior to complete insertion into
mounting sleeve 40, first connector 135 and second connector 140 are
engaged. Mounting nut 80 is then threaded into engagement with
threaded portion 45 of mounting sleeve 40. Using an appropriate tool
(not shown) mounting nut 80 is torqued with a force to achieve two
objectives. First, force should be sufficient to compress 0-rings 65,70
and tapered sealing ring 75 to provided a hermetic seal between the fluid
exterior radiation source assembly 20 and the electrical leads
115,120,125,130 interior radiation source assembly 20. Second, the
force should be sufficient to ensure an abutting connection between
quartz sleeve 95 and transducer 90, and transducer 90 and inner sleeve
50, respectively.
In use, radiation source module 10 is placed in a fluid (such as
water) to be treated such that radiation source 100 is substantially
completely immersed. Electrical conduit 145 is connected to a suitable
power supply which serves to drive radiation source 100 and transducer
90. During operation, the flow of fluid is irradiated by radiation source
100. Concurrently, transducer 90 vibrates quartz sleeve 95 in a
reciprocating manner as depicted by arrow B in Figure 4. This
reciprocating motion serves remove fouling materials (e.g. minerals,
bacteria, etc.) which may be adhered to the quartz sleeve. Further, the
reciprocating motion serves to prevent adherence of fluid borne fouling
materials to quartz sleeve. As will be apparent to those of skill in the
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art, the reciprocating action serves to subject an fouling material on
quartz.sleeve 95 to a significant shearing force which either removes
adhered fouling material from or inhibits formation of fouling material
on quartz sleeve 95.
Of course it will be appreciated by those of skill in the art that the
illustrated embodiments of the radiation source module may be varied to
suit the particular fluid treatment system without departing from the
spirit of the invention. For example, mounting plate 25 can be omitted
and support member 15 can be extended to form a leg which has a
length equal to or greater than the length of radiation source assembly
20. This type of radiation source module would be useful in a fluid
treatment system such as the ones described in the '809, '980, '244 and
'370 patents. Further, the number, type and
arrangement of sealing rings (i.e. 0-rings, tapered rings, etc.) can be
varied while maintaining a hermetic seal. Still further, while the present
radiation source module is advantageously used to concurrently irradiate
fluid and keep the radiation source assembly free of fouling materials in
situ, it is possible to remove the radiation source module from the fluid
treatment device, place in a fluid (e.g. a cleaning fluid in an external
container), and activate the vibration generation means only (i.e. no
irradiation of fluid) - this variation relates to a protocol for cleaning the
radiation source assembly of the module without concurrently treating
or purifying the fluid.
While the foregoing description teaches a radiation source
module, as discussed hereinabove, an embodiment of the invention
relates to a radiation sensor module. Such a module may be constructed
by substituting radiation source 100 and electrical leads 115,120,125,130
with a photodiode (or the like) capable of sensing the intensity of the a
radiation being emitted at a particular wavelength of interest. The
choice of photodiode (or the like) is not particularly restricted and can
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be a material conventionally used in current radiation sensors. Further,
the electrical connection and control of the photodiode is conventional
and would be apparent to a person skilled in the art.
Thus, it should be readily apparent that, while exemplary
embodiments of the present invention have been described herein, the
present invention is not limited to these exemplary embodiments and that
variations and other alternatives may occur to those of skill in the art
without departing from the intended spirit and scope of the invention as
defined by the attached claims.
