U.S. patent application number 13/167424 was filed with the patent office on 2012-06-28 for method and apparatus for treating materials using electrodeless lamps.
Invention is credited to David Richard NeCamp.
Application Number | 20120161031 13/167424 |
Document ID | / |
Family ID | 39885717 |
Filed Date | 2012-06-28 |
United States Patent
Application |
20120161031 |
Kind Code |
A1 |
NeCamp; David Richard |
June 28, 2012 |
METHOD AND APPARATUS FOR TREATING MATERIALS USING ELECTRODELESS
LAMPS
Abstract
The output wavelengths of an electrodeless lamp are controlled
by passing a fluid over the surface of the lamp to control its
temperature. The stabilized temperature prevents thermal runaway of
the lamp and stabilizes the output wavelengths of the lamp. When
the fluid passing over the lamp is water, the lamp can be used for
sanitary treatment of the water. The treatment can be enhanced by
shaping the electrodeless lamp to provide maximally effective water
treatment.
Inventors: |
NeCamp; David Richard;
(Loveland, OH) |
Family ID: |
39885717 |
Appl. No.: |
13/167424 |
Filed: |
June 23, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11789587 |
Apr 25, 2007 |
7993528 |
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13167424 |
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Current U.S.
Class: |
250/429 ;
250/436 |
Current CPC
Class: |
C02F 2201/3223 20130101;
C02F 2201/326 20130101; C02F 1/325 20130101 |
Class at
Publication: |
250/429 ;
250/436 |
International
Class: |
C02F 1/32 20060101
C02F001/32; A61L 2/10 20060101 A61L002/10 |
Claims
1. A water purification system for making potable water comprising:
an electrodeless lamp excited by an energy source outside the lamp;
a layer of water that is to be treated flowing over the surface of
the lamp to expose the water to the output radiation of the lamp;
and temperature control of the lamp using the flowing water to
maintain the temperature of the lamp for controlling the wavelength
of the lamp output to germicidally treat the water flowing over the
lamp.
2. The water purification system of claim 1 wherein the energy
source transmits energy to the electrodeless lamp passing through
the layer of water that is streaming over the surface of the
lamp.
3. A water purification apparatus for actinically treating water
for potability comprising: a tubular manifold having a closed end
and an open end; an electrodeless lamp having an annular shape with
a central channel for passing water through the channel, the lamp
mounted inside the manifold to allow water to pass over the outside
of the lamp and through the channel of the lamp; a header attached
to the open end of the manifold having a water inlet, a water
outlet and a seal at the end of the lamp adjacent the header to
prevent water passing through the channel from mixing with water
passing over the outside of the lamp, the apparatus allowing water
to pass through the manifold such that it flows through both a
space between the outside of the lamp and the inside of the
manifold and through the channel of the lamp; and an energizing
source external to the lamp for exciting the lamp to radiate
ultraviolet light.
4. The apparatus of claim 3 comprising using the apparatus for
treating fluids other than water for purposes other than water
purification.
5. The apparatus of claim 3 further comprising apparatus for
controlling the temperature of the water and the flow rate of the
water through the manifold to control the output wavelengths of
radiation from the lamp.
6. The apparatus of claim 3 wherein the electrodeless lamp is
filled with a mixture of gases comprising argon and mercury.
7. The apparatus of claim 3 wherein a controller is used to control
the temperature of the fluid passing over the lamp in combination
with the power input to the lamp to keep the lamp output at
germicidal wavelengths.
8. The apparatus of claim 3 wherein the electrodeless lamp is
regulated to provide output radiation at from about 240 nanometers
wavelength to about 265 nanometers wavelength.
9. The apparatus of claim 3 maintaining the thickness of the space
between the outside of the lamp and the inside of the manifold to
less than about 0.25 inch.
Description
[0001] This is a divisional application of co-pending
non-provisional application Ser. No. 11/789,587 filed Apr. 25,
2007.
BACKGROUND OF THE INVENTION
[0002] Electrodeless lamps can provide advantages over electrode
lamps. The electrodeless lamps require no electrical connections,
can be energized without direct mechanical contact to the lamps,
and can be energized by the field action of remote radio frequency
optical stimulation, or even magnetic fields. Instead of using
electrical current passing through electrodes to excite an
electrodeless lamp for producing light, in most cases radio
frequency energy is induced through a quartz glass envelope to
excite the gas in the lamp and cause it to emit photonic radiation.
Primarily used in ultraviolet curing applications where power and
speed are requirements, this lamp technology offers significant
benefits in other applications as well.
[0003] Electrodeless lamps can be run at much higher power levels
than electrode lamps allowing them to produce much greater amounts
of ultraviolet light than their electrode counterparts.
Electrodeless lamps exhibit long life spans on the order of 20,000
hours and, theoretically, can last much longer than that. They are
very sturdy and withstand both mechanical and thermal shock and
vibration very well.
[0004] Electrodeless lamps provide engineering flexibility. Lamp
geometries are not fixed in size and shape, and can easily be
adjusted to conform to the needs of difficult applications. Among
these are applications such as treatment with ultraviolet light in
polymer curing operations and in water treatment. Though in the
past electrodeless lamps have not generally been used in water
purification systems, they can be much better than electrode lamps
for this purpose.
[0005] In some respects, industry is heavily invested and dependent
on using electrode lamps. Because of this, electrodeless lamps have
not been used as extensively as they would otherwise have been. The
key reasons for this are technical. Electrodeless ultraviolet
applications require more sophistication and finesse to engineer
than do electrode models. Among the most difficult challenges in
using electrodeless lamps is engineering a method for exciting and
controlling the output of the lamps. In most cases radio frequency
power and coupling systems are used to power the lamps. Lamp
geometries, and fill mixes, which are the combination of elements
that are excited by an energy source to make ultraviolet light, are
engineered to couple with the lamps. In many applications the
coupling is achieved, but control of the lamp becomes difficult due
to dependence of the coupling on the temperature of the lamps, and
the lamps are prone to thermal runaway.
[0006] Another problem is that, without special envelope material,
in many applications electrodeless lamps produce large amounts of
ozone. Ozone can be hazardous to man and machine and should be
tightly managed.
[0007] Among these problems the chief reason that electrodeless
lamps are not used more is that they are extremely difficult to
manage and control. In radio frequency applications as an
electrodeless lamp continues to operate, it couples more and more
strongly with and draws more and more energy from the available
radio frequency field, which in turn makes it increase its
operating temperature. Subsequently, that causes it to couple more
strongly, and it draws more of the available energy. Although this
runaway results in more relative ultraviolet output, it also causes
the peak wavelength output of the lamp to change because the peak
wavelength output of the lamp is dependent on the operating
temperature of the lamp. This causes the lamp to be less useful for
some applications.
[0008] For example, lamps filled with a gas mixture comprising
mercury gas and argon gas, the most common fill mix, have not been
widely used for water purification because the germicidal bandwidth
needed for water purification occurs at about 240 nm (nanometers or
10.sup.-9 meters) to 265 nm wavelength. The problem is that
emission of photons at this wavelength range occurs best when the
lamp is kept in a temperature range of from about 90 F (degrees
Fahrenheit) to 110 F. Thermal runaway causes the lamp to
undesirably exceed this temperature, causing the desired
wavelengths to fall off, while other wavelengths, such as those
used in some kinds of curing rise dramatically. The peak emission
wavelength usually rises to about 360 nm. Such a wavelength is good
for curing some kinds of polymer compositions but is not good for
killing water borne bacteria. This lack of lamp output stability at
the germicidal wavelengths has prevented this technology from being
developed for various uses requiring specific output wavelengths.
This is true for uses such as water purification, and a method for
controlling the characteristic thermal runaway is needed.
BRIEF DESCRIPTION OF THE INVENTION
[0009] A method is provided for controlling the photonic output of
an electrodeless lamp excited by an energy source outside the lamp.
The method comprises passing a fluid over the surface of the
electrodeless lamp and controlling the temperature of the fluid to
regulate the operating temperature of the lamp. When the
temperature of the electrodeless lamp is controlled, the photonic
output of the lamp is maintained within a desired range of
wavelengths that are dependent on the operating temperature of the
lamp.
[0010] A water purification system for making potable water is
provided comprising an electrodeless lamp excited by an energy
source outside the lamp. A layer of water that is to be treated is
allowed to flow over the surface of the lamp to expose the water to
the output radiation of the lamp. Temperature control of the lamp
is accomplished using the flowing water to maintain the temperature
of the lamp. By controlling the temperature of the electrodeless
lamp the wavelength of the lamp output can be held to germicidal
wavelengths to germicidally treat the water flowing over the
lamp.
[0011] An electrodeless lamp for treating fluids with radiation
from the lamp is constructed. The lamp has a first end and a second
end and is comprised of an inner tube and an outer tube. The inner
tube and the outer tube are joined at the first end and at the
second end to form an annular envelope with a continuous outer
surface for containing a gas excitable from outside the envelope.
The envelope so formed provides an axial channel for passing a
fluid through the inner tube exposing the fluid to radiation from
the lamp. The lamp also permits fluid to be passed over the outer
tube exposing the fluid to radiation from the lamp.
[0012] A water purification apparatus for actinically treating
water for potability is provided. It comprises a tubular manifold
having a closed end and an open end and an electrodeless lamp
having an annular shape with a central channel for passing water
through the channel. The lamp is mounted inside the manifold to
allow water to pass over the outside of the lamp and through the
channel of the lamp. On the open end of the manifold a header is
attached. The header has a water inlet, a water outlet, and a seal
at the end of the lamp adjacent the header to prevent water passing
through the channel from mixing with water passing over the outside
of the lamp. The apparatus allows water to flow through the
manifold such that it passes through both a space between the
outside of the lamp and the inside of the manifold and through the
channel of the lamp. An energizing source external to the lamp
excites the lamp to radiate ultraviolet light.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is an electrodeless lamp control apparatus.
[0014] FIG. 2 is a fluid treatment apparatus.
[0015] FIG. 3A is an apparatus for irradiating an external
target.
[0016] FIG. 3B is an apparatus for irradiating an external
target.
[0017] FIG. 4A is an apparatus for conforming to the shape of a
target.
[0018] FIG. 4B is an apparatus for conforming to the shape of a
target.
[0019] FIG. 5A is an apparatus for enhancing radiation
delivery.
[0020] FIG. 5B is an apparatus for enhancing radiation
delivery.
[0021] FIG. 6 is a treatment apparatus.
[0022] FIG. 7 is an apparatus for treating fluids.
[0023] FIG. 8 is an apparatus for treating fluids.
DETAILED DESCRIPTION OF THE INVENTION
[0024] A method for controlling the peak output wavelengths of
electrodeless lamps and maintaining them at desired wavelengths
indefinitely is described. The method extends across the spectrum
of electrodeless lamp output wavelengths.
[0025] A significant discovery for water purification, the
invention also permits uses of electrodeless lamps in curing and
hazardous material remediation applications where they previously
were not viable. For example, many polymer systems are engineered
to cure with light centered at a wavelength of about 254 nm
(nanometers) and spanning a wavelength of from about 240 nm to
about 265 nm, which also happens to be the best germicidal
frequency for treating water. In many industrial applications
ordinary electrode lamps are used for the ultraviolet curing source
because they are more easily controlled than are electrodeless
lamps and do not runaway thermally as do electrodeless lamps. Using
the invention an electrodeless lamp can now reach and maintain the
254 nm wavelength range without runaway. Because of the additional
power possible with electrodeless lamps over electrode lamps,
curing operations can be sped up by as much as a factor of 4.
[0026] An additional benefit is that the invention provides a
method for controlling and even preventing the production of ozone
by an electrodeless lamp. This eliminates ozone control by such
procedures as doping the quartz comprising the envelope that forms
the lamp. Controlling ozone generation can also eliminate
ventilation requirements. However, in certain applications it is
desirable to create ozone for treating water or for other
processing purposes.
[0027] Electrodeless lamps are usually, but not always, comprised
of a quartz envelope filled with a gaseous fluid. Often mixes of
gasses are used in the envelope. Commonly, mercury gas is used and
is mixed with argon gas and sometimes small amounts of other gases.
In operation the gases are usually radiationally excited, often by
a nearby radio frequency field, which can be created by various
methods such as by a magnetron often similar to that used in a
microwave oven. The excited gas in the envelope, experiencing
elevated electronic states, emits photonic energy at specific
wavelengths as it tries to return to its unexcited state. The
specific frequencies emitted are generally dependent on the
particular gas or gas mixture used in the envelope, the level of
excitation, and the temperature.
[0028] In the case of electrodeless lamps when operated in open
air, the radio frequency field often couples with the gas in the
lamp, and as the temperature rises due to the absorption of radio
frequency energy by the gas, the gas reaches a continuously more
easily excited state causing the temperature of the lamp to rise in
an uncontrollable manner. It is difficult to control this runaway
temperature by controlling the energy output of the exciting field
since the field couples more and more strongly to the gas with
temperature and in a nonlinear fashion. Various methods have been
tried to control the thermal characteristics of electrodeless lamps
such as rotating the bulb or blowing air on it. These methods work
where light output is the only requirement from the lamp, but they
do not work well where a specific range of wavelengths is desired
that is variable according to temperature.
[0029] As shown in FIG. 1, a better method for controlling the
photonic output of an electrodeless lamp assembly 100 excited by an
outside energy source 103 is to pass water or some other
temperature stabilizing fluid 102 over the surface of the lamp 104
causing the temperature of the lamp 101 to be limited by the fluid
102. Stabilizing the temperature of the lamp 101 by passing the
fluid 102 over its surface 104 allows more flexibility in managing
power input to the lamp from the energizing field 103. The
stabilization allows greater amounts of energy from the field 103
to be applied to the lamp 101 without causing thermal runaway, and
the energizing source can be used in combination with the flowing
fluid 102 to control the performance of the lamp 101.
[0030] Water makes a suitable fluid 102 for such a purpose because
it is a simple matter to control the lamp 101 temperature by
adjusting the temperature and flow rate of the water as it is
exposed to the lamp surface 104. When the temperature of the water
is adequately controlled, the lamp 101 can be made to operate at a
specific output range of wavelengths. For example, with an
electrodeless lamp 101 filled with a gas 105 mix comprising argon
and mercury, and regulated to hold at about 90 F (degrees
Fahrenheit) to about 110 F during excitation, the lamp 101 peak
output will be centered on about 253.7 nm (nanometers) wavelength
and will maintain this ultraviolet wavelength peak so long as the
temperature of the lamp 101 is held steady. As it turns out, the
wavelength range centered on about 253.7 nm is particularly
effective in the germicidal treatment of water, and radiation
centered on wavelengths surrounding 253.7 nm are known as the
germicidal wavelengths. This particular wavelength is also
particularly effective in the curing of certain polymer
compounds.
[0031] In one embodiment a difficulty with this approach, when
radio frequency energy is used, is the problem of passing the radio
frequency energy through the fluid 102, water in this embodiment,
to the gas 105 since the lamp surface 104 is covered with water and
the water tends to reduce the energy delivered to the lamp 101. To
improve energy delivery to the gas 105, the depth of the water
passing over the lamp 101 is controlled. It is noted that
increasing the power output of the outside energy source 103, in
this embodiment a magnetron, can allow the use of greater depths of
water according to the power requirements needed to start and run a
particular lamp 101.
[0032] In another embodiment it is possible to better regulate the
energy coupling between the gas 105 and the energy source 103 since
the water flowing over the lamp 101 acts as a buffering load on
the, in this embodiment, radio frequency energy and makes the gas
105 response to changes in the excitation energy provided to the
lamp 101 less sensitive to changes in radio frequency energy
output. The flowing fluid 102 can absorb some of the energy from
the radio frequency field effectively damping the radio frequency
energy as it couples with the gas 105 in the electrodeless lamp
101. In this sense the flowing fluid 102 buffers the load on the
radio frequency field. Since in some applications variations in
output from an excitation source are possible only in discrete
steps, the flowing fluid 102 can be used to help with control of
the excitation energy reaching the gas 105 in the lamp 101.
[0033] In another embodiment it is possible to control the
temperature of the fluid 102 using the lamp 101 and the external
excitation source 103, also referred to as the energizing source
103, individually or in combination. In this embodiment a radio
frequency source can be used. When fluid 102 is not flowing past
the lamp 101, it is not always desirable to energize the lamp 101
for various reasons including, but not limited to, energy
conservation. A problem can arise in restarting the lamp 101.
[0034] When the temperature of the fluid 102 surrounding the lamp
101 falls below the needed operating temperature of the lamp 101,
the gas 105 in the lamp 101 is warmed to some minimum ignition
temperature before the lamp 101 can be lit. Further, if the system
providing the temperature regulating fluid 102 is cold, it can take
time to bring the whole system 100 up to operating temperature and
ignite the lamp 101. In this context the word ignition refers only
to achieving conditions for and lighting the lamp and not to any
kind of combustion, since the lamp operates based on the excitation
and de-excitation of the gases contained therein.
[0035] In systems 100 where the output of the lamp 101 is
immediately needed at some specific temperature related wavelength,
the warm-up time can be a problem. For example, in one embodiment
where the fluid 102 flowing past the lamp needs to be treated by
the lamp 101 output, the lamp 101 should be on as soon as the fluid
flow starts, or the initial fluid 102 flowing past the lamp 101
will not receive the needed treatment.
[0036] To solve this problem, if the fluid 102 surrounding the lamp
101 is kept at the needed ignition temperature for the lamp 101,
even though the fluid 102 flow stream external to the lamp system
100 is at a low temperature, the lamp 101 can be instantaneously
lit because it is at operating temperature. One feature of
electrodeless lamps 101 is that although they need to be at
operating temperature for ignition, they will remain in a lit state
even though the temperature of the surrounding fluid 102 drops
temporarily. Further, they are slow to respond in terms of
wavelength output change when they encounter temporary drops in
flowing fluid 102 temperatures.
[0037] Because of the above, rapid ignition capability can be
achieved in electrodeless lamps 101 by regulating the fluid
temperature surrounding the lamp 101 to the needed operating
temperature, which depends on the gas 105 used in the lamp 101 and
the wavelength output desired from the lamp 101.
[0038] Fluid based temperature control can allow power input to the
lamp 101 from the energizing field 103 to be more easily regulated
without causing thermal runaway permitting lamp 101 output to be
controlled by the combination of power input to the lamp 101 from
the energizing field 103 and temperature control by the fluid 102
surrounding the lamp 101.
[0039] In the embodiment where the lamp gas 105 is primarily
comprised of argon and mercury, and the fluid 102 surrounding the
lamp 101 is water with a desired lamp 101 output centered on about
253.7 nm, maintaining the water surrounding the lamp 101 at a
temperature of from about 85 F to about 100 F provides rapid
ignition of the lamp 101 with the desired output wavelengths.
[0040] In another embodiment the lamp 101 and system 100 can be
turned off and allowed to come to ambient temperature. When this
occurs, treatment of the fluid 102 surrounding the lamp 101 can
only be accomplished if the fluid 102 flow is stopped and blocked
from passing the lamp 101 while the lamp 101 is off; the energizing
source 103 warms the fluid 102 and the lamp 101 up to ignition
temperature; the lamp 101 is lit; and fluid 102 flow is then
established.
[0041] From another aspect one of the negatives of using
electrodeless lamps 101 is that they produce ozone from the
interaction of the outside surface of the lamp 101 with the
atmosphere. When water is used as the fluid 102, the water flowing
over the surface of the lamp 101 inhibits the reaction of the lamp
surface 104 with the oxygen in the atmosphere substantially
eliminating the lamp 101 as a significant source of ozone and
removing any ozone created by the interaction with the water as the
water flows past the lamp surface 104. Commonly, when the lamp
surface 104 is comprised of quartz as is often the case,
specialized treatment of the quartz envelope surrounding the lamp
101 is required to limit ozone production. The flowing water can
eliminate this requirement.
[0042] In another embodiment FIG. 2 shows how a system 200 can be
used to provide treatment of the fluid 202 flowing over the lamp
201 with the photonic radiation produced by the lamp 201. In the
case where the fluid 202 is water, the system is useful in creating
potable drinking water. FIG. 2 shows a treatment system 200 that
can be used for treating fluids wherein a fluid inlet 204 provides
fluid 202 for treatment, the fluid 202 is exposed to the radiation
from the lamp 201, which is excited by the energy source 203. As it
passes through the system 200, the fluid is exposed to the lamp 201
radiation and the treated fluid exits the system through outlet
205.
[0043] FIG. 3A shows another embodiment comprising an electrodeless
lamp system 300 employing a photo-transparent shell 306 containing
a fluid 305 and a lamp 304 surrounded by an energizing field 307.
The photo-transparent shell 306 could be transparent to a broad
range of wavelengths or could be constructed or tuned to filter
specific wavelengths of light produced by the lamp 304. The field
307 is provided by an external energizing source such as a
magnetron. The system 300 has a fluid inlet 302 and a fluid outlet
303 that permits fluid to pass through the system 300. Irradiation
of a target 308 outside the lamp 304 and flowing fluid 305 is
accomplished by controlling the depth of the fluid 305 to allow the
electrodeless lamp 304 output to substantially pass through the
fluid 305 and photonically interact with an external target 308. A
reflective energy shield 301 is used to direct the energy of the
system 300 toward a target 308. The cross section view 309
designated in FIG. 3B is taken through the middle of the apparatus
300 of FIG. 3A as indicated depicting how the photonic output of
the lamp 304 passes through the fluid 305 and the energizing field
307 to illuminate the target 308.
[0044] In this case the flowing fluid 305 stabilizes the output of
the lamp 304 and provides a stable and precise source for
ultraviolet radiation. Such sources are particularly useful in
treating targets 308 that are sensitive to particular photon
energies. One example is in the curing of polymeric compounds which
are often only sensitive to a particular photon energy associated
with the activation of chemical processes that occur in these
materials.
[0045] FIG. 4A and FIG. 4B portray another embodiment showing how a
system 400 can be built to conform to the shape of a target 408 for
irradiating it with ultraviolet radiation. FIG. 4A is a cross
section side view of the system 400 in which the electrodeless lamp
401 is deformed to focus its output radiation. In FIG. 4A the
jacket 402 around the flowing fluid 403 contains the entire lamp
401. However, the lamp 401 is not exposed on every side to the
excitation energy field 404 provided by an outside excitation
source. Fluid still flows around the lamp 401 from inlet 405 to
outlet 406 for regulating the temperature of the lamp 401, and the
exposure of the lamp 401 to the exciting field 404 is sufficient to
ignite the lamp 401 and keep it lit while the flowing fluid 403
regulates its temperature. The advantage of the arrangement shown
400, 409 in FIG. 4A and FIG. 4B is that except for the thin
temperature controlling layer provided by the flowing fluid 403,
the lamp 401 can be exposed directly to the target 408 and can be
conformed to fit the target 408. The cross end view 409 of FIG. 4B
taken as indicated in FIG. 4A shows this.
[0046] In this embodiment the arched nature of the lamp 401 along
its long axis allows the lamp to conform to the target 408 shape
shown. The apparatus 400, 409 can be incased in a reflective energy
shield 407 which contains the energizing field 404 and reflects it
internally to the lamp 401, and the shaped nature of the lamp 401
permits three dimensional treatment of the target 408.
[0047] In FIG. 4B a gap is shown between the target 408 shape and
the inner side of the fluid flow channel for reasons of clarity. In
use this gap can be eliminated and the jacket 402 comprising the
outside of the temperature regulating fluid 403 channel can be
placed in contact with the target 408. Such an arrangement can lead
to added robustness of an operating system 400, 409 adding to
mechanical stability while enhancing the level of radiation
delivered to the target 408 and providing a three dimensional
nature to the treatment of the target 408.
[0048] The purification of water can be accomplished by passing
water over an electrodeless lamp as discussed above. However, to
provide adequately treated water certain minimum amounts of
ultraviolet energy have to be delivered to the water. Further, the
energy has to be delivered in a manner that will insure that the
radiation can interact with the polluting bacteria.
[0049] Ultraviolet wavelength treatment methods sometimes are
defeated by the phenomenon of shadowing. Shadowing occurs when
intervening matter gets between the ultraviolet source and targeted
matter interfering with the photons reaching the targeted matter.
When fluids are being treated, this problem can be addressed by
various methods such as introducing turbulence into the fluid flow
stream. However, the following embodiment has been found to be
effective in delivering the needed radiation permitting the
treatment of solid objects as well as fluids. While the embodiment
can be used to treat fluids, it can also be used to treat other
items such as medical instruments, food, or other articles with
electrodeless lamp produced radiation. The embodiment permits 360
degree radiation exposure over an extended length to a target
region.
[0050] To provide the needed ultraviolet dose delivery FIG. 5A
shows a cross section of an electrodeless lamp 501 system 500
formed in the shape of an elongated annular ring with the lamp
surface 510 continuous and enclosing an excitable gas.
[0051] FIG. 5B is a cross section view 509 of the apparatus 500 as
seen through the indicated plane looking down the length of the
tube to the left showing the inlet 505 at the far end of the
apparatus.
[0052] The system is fitted with an inlet 505 and an outlet 506, is
enclosed in a reflective energy shield 507 and features an
excitation energy field 504 provided by an external excitation
energy source not shown and contained by the reflective energy
shield 507.
[0053] The lamp envelope 510 enclosing the lamp's gas is comprised
of an inner tube 511 and an outer tube 512 joined at the ends to
form the annular ring. Usually, the tubes 511, 512 forming the
annular shaped electrodeless lamp 501 are round, though they need
not be and in some embodiments are not. The interior of the lamp
501, between the tubes 511, 512 of the envelope 510, is filled with
a radiation producing gas and is excited by an external energy
field 504 which is produced by an external energy source.
[0054] The shape of the electrodeless lamp 501 provides an axial
channel 508. The system 500 is configured to allow a temperature
stabilizing fluid to flow over the lamp surface passing a fluid
503, such as water, through the space between the inner
photo-transparent shell 502 and the inner tube 511 and also through
the space between the outer tube 512 and the outer
photo-transparent shell 502. The fluid stabilizes the operation of
the lamp preventing thermal runaway and allowing selection of
output wavelengths from the lamp 501 by controlling the temperature
of the lamp. In this configuration the lamp can deliver enhanced
doses of radiation. As material is moved through the channel 508 it
is bombarded with the radiation from a full 360.degree. and further
benefits from axial scattering effects as the discharging gas in
the lamp radiates through the inner portion of shell 502 delivering
a shadow defeating dose of radiation. As discussed above, the
flowing fluid 503 is maintained at a temperature and flow rate that
insures that the lamp 501 is kept at the temperature needed to
maintain its peak radiation output in the desired range.
[0055] The physical size of the channel 508 can be changed to
accommodate varying needs for dosing the material that is passed
through the channel 508, and the material treated by the apparatus
can comprise solid objects or fluids.
[0056] In one embodiment the shape of the lamp 501 can be flattened
along the axial channel 508 so that the depth or thickness of the
channel 508 is decreased and the effective energy density of
radiation delivered to the material passing down the channel 508 is
increased. The rest of the apparatus is modified to accommodate the
lamp shape when this is done.
[0057] Though ultraviolet wavelengths are the ones generally
desired for actinic water processing using electrodeless lamps,
other gas mixtures than ultraviolet producing gas mixtures and
their associated wavelengths can be used for other processing
purposes. As discussed above, when the radiation desired is
ultraviolet radiation, the ultraviolet producing gas mixture is
often comprised of mercury and argon and is held at a specific
temperature to produce peak output from the lamp at germicidal
wavelengths.
[0058] In yet another embodiment stabilizing by liquids passing
over the lamp solves another problem characteristic of
electrodeless lamps. The presence of the fluid inhibits the
exposure of the lamp envelope to free oxygen in the open atmosphere
and limits the production of ozone from the lamp surface sweeping
away any ozone that is created from the presence of free oxygen in
the fluid. In this way the fluid passed over the surface of the
lamp is used to control ozone production at the surface of the
electrodeless lamp.
[0059] In another embodiment FIGS. 6A, 6B and 6C show how axial
flow down an annular shaped electrodeless lamp can be made into a
treatment apparatus 600 for stabilizing electrodeless lamp
operation to provide desired wavelengths from the lamp and at the
same time provide effective fluid treatment with minimal shadowing.
For radiation transmission purposes various materials can be used
to form the sides of electrodeless lamps depending on the radiation
transmission needs. As mentioned above, where water is being
purified using electrodeless lamps and the gas in the lamp
comprises mercury and argon, the lamps are usually made of quartz.
As shown in FIG. 6A, a lamp 600 comprised of quartz can be
fabricated by using an inner tube 601 and an outer tube 602 joining
them together to form a gas filled envelope 603 to provide the
axial channel 604.
[0060] FIG. 6B shows a cross section 605 through the indicated
plane and looking down the length of the apparatus 600, and FIG. 6C
is a perspective view 606 of the apparatus.
[0061] In use a temperature stabilizing fluid can be passed over
the surfaces of the envelope to control the temperature of the lamp
603 created by joining the end of the outer tube 602 with the inner
tube 601 to form the lamp 603. In this embodiment the fluid passed
over the lamp is treated with the radiation from the lamp at the
same time that it is stabilizing the temperature of the lamp. For
example, the apparatus can be the core of a water treatment
system.
[0062] FIG. 7 is an embodiment using an apparatus similar to that
provided in FIG. 6. In FIG. 7 the assemblage 700 is used to provide
a water purification apparatus 700 for actinically treating water
for potability. A tube shaped manifold or processing chamber 701
open only on one end is used. Inside the manifold 701 is placed an
electrodeless lamp 702 that can be, but need not be, centered in
the manifold 701. The electrodeless lamp 702 has the annular shape
discussed above with a central channel 703 for passing water
through the lamp 702. Head space 704 is allowed at the closed end
of the manifold 701 allowing water to flow around the end of the
electrodeless lamp 702.
[0063] A header 705 is attached to the open end of the manifold
701. The header 705 has a water inlet 706, a water outlet 707 and a
seal 708 at the end of the lamp 702 adjacent the header 705 to
prevent water passing through the channel 703 from mixing with
water passing over the outside of the lamp 702.
[0064] The apparatus 700 allows water to pass through the manifold
701 such that it passes through both a space 709 between the
outside of the lamp 702 and the inside of the manifold 701 and
through the channel 703 of the lamp to receive an effective dose of
lamp 702 radiation and to keep the lamp 702 at the desired
operating temperature to provide germicidally effective
radiation.
[0065] In FIG. 8 an external energizing source 805 is used for
energizing an electrodeless lamp 803. The apparatus 800 of FIG. 8
shows a lamp 803 inserted in a microwave tuned cavity 801 which is
used for exciting the lamp 803 since it is inside a manifold 802.
It should be noted that the excitation energy source 805 does not
have to completely enclose the lamp for the lamp to provide desired
ultraviolet radiation. A small portion of the lamp 803, when
exposed to the exciting energy source, can be effective in lighting
or driving the whole lamp 803 and providing ultraviolet radiation
from the entire lamp surface.
[0066] In operation the water flows into the inlet 808 of the
header assembly 814, through either the channel 807 or the side
space 804, depending on inlet 808 and outlet 809 arrangement,
through the head space 810 and back out through either the channel
807 or the side space 804 depending on inlet 808 and outlet 809
arrangement. As presented in FIG. 8 the water flows in the inlet
808, through the side space 804, then through the channel 807 and
out the outlet 809. As indicated above, the flow direction could be
reversed. The temperature and flow rate of the water are adjusted
externally to maintain the desired peak in electrodeless lamp 803
radiation.
[0067] The thickness of the side space 804 is chosen to insure that
any needed actinic treatment by the lamp emissions in the side
space is effective. However in many but not all instances, the high
intensity treatment of the water flowing through the channel 807 is
sufficient to purify water flowing through the apparatus 800.
[0068] The apparatus 800 described can also be used for treating
fluids other than water and for purposes other than water
purification. For example, a flowing reactionable polymer stream
can be partially reacted by choosing and maintaining the
appropriate output wavelength from the electrodeless lamp 803. Such
treatment could be used to regulate the viscosity of the flowing
polymer stream.
[0069] It is found that the most effective thicknesses for the side
space 804 when using commonly available magnetrons similar to those
used in ordinary microwave ovens are up to about 0.25 inch. Higher
power radio frequency sources allow a thicker side space 804 for
effective fluid treatment according to the output capabilities of
the electrodeless lamp 803 and the requirements of the shadowing
situation.
[0070] In some embodiments it is desirable to use multiple
electrodeless lamps in combination. It should be noted that
electrodeless lamps can be grouped and can be driven by other lamps
in contact with or close by each other. In this case the excitation
source for the electrodeless lamps can be other electrodeless lamps
with initial excitation arising from various energy providing
sources.
[0071] Those skilled in the art will realize that this invention is
capable of embodiments different from those shown and described. It
will be appreciated that the detail of the structure of this
apparatus and methodology can be changed in various ways without
departing from the scope of this invention. Accordingly, the
drawings and detailed description of the preferred embodiments are
to be regarded as including such equivalents as do not depart from
the scope of the invention.
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