WO2000026162A1

WO2000026162A1 - Treatment of fluids with electromagnetic radiation

Info

Publication number: WO2000026162A1
Application number: PCT/US1999/025867
Authority: WO
Inventors: Todd L. Foret
Original assignee: Foret Todd L
Priority date: 1998-11-02
Filing date: 1999-11-02
Publication date: 2000-05-11
Also published as: WO2000026162A9; AU1711900A

Abstract

A method for irradiating a fluent material within a conduit (2) is provided, comprising directing electromagnetic radiation (EMR) from a first EMR source (18) into the fluent material (3) along at least one longitudinal axis (5) of the conduit; and directing EMR from a second EMR source (40) such that the EMR from the second EMR source (40) is caused to intersect the fluent material (3) and the EMR from the first EMR source (18). Preferably, the method further includes focusing the EMR from the first EMR source (18) such that an EMR apex (42) is created within the fluent material (3), wherein the EMR apex (42) is intersected by the EMR from the second EMR source (40). Also preferably, the method further includes collimating the EMR from the first EMR source (18), and wherein the EMR from the first EMR source (18) is intersected by the EMR from the second EMR source (40) such that an EMR high density energy zone (43) is created within the fluent material (3).

Description

TREATMENT OF FLUIDS WITH ELECTROMAGNETIC RADIATION

BACKGROUND OF THE INVENTION

I. Technical Field

This invention relates generally to devices and methods used to treat fluids with

electromagnetic radiation, and more particularly to the treatment of chlorine with electromagnetic radiation to remove hydrogen and nitrogen trichloride, and to the treatment of water, wastewater and

air with electromagnetic radiation to remove contaminants.

LI. Prior Art

Irradiating fluids with electromagnetic radiation (EMR), particularly within the 4 nanometer (nm) to 400 nm wavelength (or ultraviolet) (UV) range is well known and well documented. For

instance, disinfection of water and wastewater to remove pathogenic microorganisms is commonly

achieved using a UV radiation source which has a strong emission line at 253.7 nm. An example

of this type of UV radiation source is a linear, long arc, low-pressure mercury vapor lamp. Many commercial and industrial applications for UV disinfection are increasing due to their effectiveness

in destroying pathogenic microorganisms and emerging pathogens like caliciviruses, microsploridia,

hepatitis A virus, Legionella and Cryptosporidium, as well as in deozonization processes. In

addition, processes using EMR within the 4 nm to 200 nm wavelength or vacuum UV radiation (VUV) are developing which are capable of removing organic and inorganic contaminants (such as ammonium perchlorate, pesticides, arsenic, nitrate, sulfate, radon, MTBE) as well as other particulates. VUV or a combination of UV and ozone or hydrogen peroxide processes are now commonly termed Advanced Oxidation Processes (AOP). An AOP is primarily intended to generate

free hydroxyl radicals in situ which are capable of oxidizing the contaminants to CO₂ and H₂O or

into less harmful biodegradable by-products. Although many other applications of electromagnetic

irradiation to which this invention may pertain could be enumerated, the primary applications of the

present invention are in the production of chlorine or chlorinated products, as will be further explained below, and in the removal of pathogenic microorganisms, organic and inorganic contaminants from water, wastewater, and air.

A. Application to chlorine and similar streams

In the case of the treatment of chlorine streams, chlorine is produced by the electrolysis of

melted sodium chloride or an aqueous solution containing sodium chloride (referred to as "brine") within a chlorine cell. A chlorine cell is basically a container containing two compartments, an anode compartment and a cathode compartment. The two compartments are separated by a

diaphragm which (depending on the type of cell) can be made of asbestos fibers, a combination of

asbestos and Teflon (PTFE) fibers, or an ion exchange membrane material. Brine (NaCl) solution is allowed to flow into the anolyte chamber where it passes through the diaphragm and out of the

cell. When direct current is applied to the anode and cathode, the salt is electroiyzed and breaks

apart into sodium (Na^") and chlorine (Cl^") ions. At the anode the chlorine ions combine to form

chlorine gas (Clj) which is collected in a header and removed for further processing into a product.

The sodium ions pass into the cathode chamber with the depleted brine solution where the water is electroiyzed to form hydrogen gas (H,) and hydroxide ions (OH^"). The sodium ions and hydroxide ions combine to form sodium hydroxide (NaOH), or "caustic soda," which is also removed and

processed into a product. The hydrogen gas is also collected in a header and further processed by cooling and compressing. The hydrogen is then normally burned as fuel to reduce the required

amount of natural gas in steam boilers or it is used as a chemical feed stock in chemical process

industries and refineries.

Chlorine and hydrogen streams are similar streams in that both are being produced through electrolysis. However, the streams are processed separately for production of commercial products.

"Similar" is defined herein as a stream, in particular a gaseous stream, which contains molecules

which can be affected by EMR, such as by photolysis. By way of example only, such streams may

include a hydrogen stream contaminated with chlorinated molecules, a sulfuric acid plant stream in which the stream consists of sulfur dioxide, sulfur trioxide, oxygen and nitrogen (air), a flue gas

stream from an electrical generation plant consisting of nitrogen oxides, sulfur oxides, oxygen,

nitrogen, carbon and particulate matter, and also a semi-conductor plant gaseous stream which may

include flourinated, chlorinated and brorninated molecules.

With respect to a chlor-alkali plant, a residual amount of hydrogen typically remains within the chlorine wet gas stream. Likewise, a residual amount of chlorine and chlorinated compounds

typically remains in the hydrogen stream. Since the electrolysis reaction is exothermic, the

temperature of the wet chlorine gas leaving each electrolysis cell can be as high as 90°C. If hydrogen

concentration approaches about 3%, a potentially explosive environment is created where chlorine is the oxidant, hydrogen is the fuel and the reaction temperatures cause a spontaneous, self-sustaining chain reaction.

To reduce the possibility of an explosion due to the increasing hydrogen concentration, prior

methods usually involved purging the fluid stream with dilution air. As a result, the hydrogen concentration is diluted to within acceptable limits as prescribed by plant operating procedures. However, the air purge has an adverse effect on plant production, because it necessarily reduces the

volume of chlorine recovered during liquefaction. Moreover, although chlorine recovery is decreased, the plant must still operate at full capacity even though the process is less efficient.

Given the past inadequacies of air purging, modem methods of reducing hydrogen commonly

involve irradiation of the liquid chlorine with UV or other levels of radiation. This process takes

advantage of the fact that chemical chain reactions usually involve the formation of free radicals as

intermediates. An example is the reaction of chlorine with hydrogen initiated by EMR. A chlorine molecule is first split into its constituent atoms:

Cl₂ > Cl- + Cl-

These chlorine radicals react with hydrogen and with each other as follows:

Cl. + H₂ > HC1 + H-

H. + Cl₂ > HC1 + Cl-

Cl- + Cl- > Cl₂

Thus, the hydrogen may be completely removed from the chlorine stream, in theory, by the

application of suitable EMR which will maintain these chain reactions at the sacrifice of a relatively

small amount of chlorine production.

Another deleterious by-product formed in the production of chlorine and hydrogen is

chloramine. The presence of one cWoramine, in particular nitrogen trichloride, within the chlorine

stream is very dangerous at low concentrations and it explodes violently at temperatures above 90°C.

Likewise, the present of chloramine in the hydrogen stream produced at the cathode also will have a deleterious effect. Extensive studies have been conducted by members of The Chlorine Institute,

Inc., in an effort to precisely determine the amount of nitrogen trichloride that can be considered unsafe. However, accurate and reliable information on the nature of this compound have been difficult to obtain. Thus, any means of decreasing nitrogen trichloride to the lowest possible level

during the production of chlorine would be an extremely desirable safety measure. Toward this goal,

a number of devices and processes have been developed over the years which involve subjecting the

chlorine stream to UV radiation, which has proved more or less effective in reducing nitrogen trichloride.

In the early 1950's and 1960's many tests were conducted with UV radiation in an attempt

to solve the hydrogen and nitrogen trichloride problems associated with chlorine production. For example, on November 8, 1962, a paper was presented by C. R. Dilmore of PPG Industries, Inc., to

the Chlorine Institute which discussed the success of ultraviolet lights in the reduction of nitrogen trichloride. U.S. Patent No. 2,705,219 issued to Heiskell, et al., also discloses a process involving

UV radiation to reduce nitrogen trichloride levels in which an elongated UV source is enclosed

within a thimble and inserted into the chlorine stream. With respect to the reduction of hydrogen,

A. G. Follows of Allied Chemical submitted a paper to The Chlorine Institute, Inc., on February 2, 1966, regarding a case history which solved much of the hydrogen problem with an actual plant

trial. This work was based in part on the disclosure of U.S. Patent No. 3,201,337, issued to

Eichelburger, et al., which also focused on the removal of hydrogen from chlorine gas by UV

irradiation.

U.S. Patent No. 4,948,980, issued to Wedekamp, discloses a system for UV irradiation of fluids, wherein aring of external UV-radiation sources is directed toward the center of a tubular body constructed from a UV-permeable material. The claimed advantage of this type of arrangement is

that the radiation is focused into the fluid traveling through the tubular body, thus increasing the radiation density in the treated fluid. Despite this perceived advantage, a major problem exists in

that the flow line cannot be cleaned without shutting off that portion of the treatment system.

Through prolonged exposure to chlorine, the internal surface of the tubular body will become cloudy

and coated with a thin film of chlorine, sodium chloride and other contaminants, which impedes the transmission of UV light. The only alternative to shutting down the system is either: ( 1 ) installation

of an internal wiper system, which is very expensive in terms of both labor and materials to install

and maintain; or (2) the construction of one or more bypass lines, which carries the same disadvantages.

U.S. Patent No. 5,200,156, also issued to Wedekamp, discloses a UV device which has been used effectively in several chlorine plant applications. That reference discloses a system comprising

one or more UV-radiation sources which are protectively housed within a quartz conduit or other

UV-permeable enclosure. The UV sources are placed directly in the path of the fluid and perpendicular to fluid flow with the intention of maximizing the irradiation of the fluid with minimal

radiation loss. Unfortunately, this system carries the same cleaning and shut-down disadvantages as seen in the '980 patent, because the radiation sources are directly in the flow path. Moreover, if

the protective quartz tubing should ever break, the electrical UV-radiation source is exposed to the

surrounding chemicals, creating a potentially explosive environment. In such an accident, quartz

fragments will necessarily travel downstream within the fluid flow, possibly damaging expensive equipment as well.

Although the prior devices and methods provide reduction of both hydrogen and nitrogen

trichloride in modem plant operations, there are many EMR applications which do not require full

irradiation of the fluid, i.e. exposure of all elements of the fluid flow to high intensity radiation. The production of chlorine is a case in point. Due to the extreme susceptibility of chlorine (Cy to form

free radicals in the presence of certain levels of EMR, coupled with the fact that an extensive and

sustainable chain reaction between chlorine and hydrogen takes place under relatively slight EMR exposure conditions, the inventor has discovered that there is no need to subject the entire fluid to

radiation. Instead, it is only necessary to irradiate a small region of the fluid sufficient to initiate and

sustain the chain reaction. Such insight has made it possible to consider designs which easily satisfy

the first criterion of the "ideal" EMR system, with resultant success in meeting the remaining criteria as well.

On the other hand, while full irradiation of the entire fluid volume may not be required, it is

essential that the intensity of the EMR be such that the maximum number of chain reactions be

initiated and sustained. For example, while the UV radiation produced by the prior art devices is of

a wavelength sufficient to cause photolytic fission of the diatomic chlorine and the nitrogen trichloride, a relatively small level of radiation is imparted to the fluid due to the geometry of the

EMR source and its power rating. Thus, an improved EMR system is needed which is capable of

employing inexpensive, easily available EMR sources which emit the required EMR at a wavelength,

focus and intensity effective in minimizing undesirable contaminants.

B. Application to water, wastewater and air

Although an important application of the present invention to chlorine production has been

explained above, the field of water and wastewater treatment are particularly in need of devices and

processes which can improve the quality of water used for human consumption. For example, the

Safe Drinking Water Act requires that public water supplies be disinfected and authorizes the U.S.

Environmental Protection Agency (EPA) to set standards and establish processes for treatment and distribution of disinfected water to ensure that no significant risks to human health occur. The EPA

Science Advisory Board has ranked pollutants in drinking water as one of the highest health risks

meriting EPA's attention due to the exposure of large populations to contaminants such as arsenic,

lead, disinfectant by-products (DBPs), and disease-causing organisms. Disinfectants are used by

virtually all surface water systems in the U.S. and many systems that rely on ground water. Chlorine has been the most widely used and most cost-effective disinfectant. However, disinfection

treatments can produce a wide variety of by-products, many of which have been shown to cause

cancer and other toxic effects. Recently, there has been concern that water quality can deteriorate

dramatically during distribution unless systems are properly designed and operated. While

disinfection is an integral part of water treatment, filtration is necessary in surface water systems to reduce pathogen levels and make disinfection more reliable by removing turbidity and other

interfering constituents.

Given the past inadequacies of treating water, wastewater and air with conventional

technologies to remove contaminants, modern methods of removing contaminants commonly involve irradiation of the fluid with UV or other levels of radiation. In the EPA Municipal

Wastewater Disinfection Design Manual (EPA/625/1-86/021), Chapter Seven is dedicated to

Ultraviolet Radiation Disinfection Systems. Likewise, many engineers follow the "Recommended

Standards for Wastewater Facilities" more commonly known as "The Ten State Standards" when

designing a disinfection system for a wastewater facility. Both the EPA Disinfection Design Manual and The Ten State Standards Manual mention using a UV system in which the UV bulbs are housed in a quartz sleeve which is immersed in an

open channel. One specific design which follows the criteria set forth by both entities is manufactured by Trojan Technologies, Inc., under US Patent No. 5,006,244. The inherent design

of this system is also its major disadvantage. The use of a low power density mercury vapor housed

in a quartz sleeve. The problem of this design as stated by the EPA Disinfection Design Manual is

that "since the low pressure mercury arc lamps are excellent absorbers of light at the 253.7 nm wavelength, the model calculations presume that any energy at this wavelength entering a lamp from

a neighboring lamp will be completely absorbed by that lamp." Two other factors are directly related

to the design of this system which are also drawbacks. The First Order Kinetics for the UV Process

(EPA page 184 para 7.3.1.1) for disinfection is based upon UV intensity with respect to time. Herein after the term "Power Density" will be used to describe UV intensity. The power density is the rate at which the energy is being delivered to the fluid; in context of this invention, power density has

the unit microwatts per square centimeter ( W/cm²). When multiplied by the time to which a

molecule is exposed to this rate, the quantity of energy, or dose, is determined:

Dose (microwatts-sec/cm²) = Power Density (microwatts/cm²) x Time (seconds)

In designing an EMR system, either the Power Density or residence time must increase to increase the dose. Thus, designs such as Trojans UV3000 System, take advantage of adding many

lights into a large open channel which increases residence time, and as a result, increasing dose.

However, since it is known that microorganisms repair and reverse the lethal effects of UV, which

this phenomenon has been broadly termed "Photoreactivation," then a properly designed system would be enclosed within an EMR blocking conduit and not in an open channel which allows

sunlight to photoreactivate the damaged DNA and RNA in microorganisms.

It can be clearly seen that using long or medium arc mercury vapor lamps housed within quartz sleeves and immersed within the fluid in vicinity of one another is self defeating. Likewise, irradiating the fluid in an omnidirectional fashion increases the surface area. As a result, power

density decreases.

U.S. Patent No. 2,705,219 issued to Heiskell; U.S. Patent No. 3,201,337 issued to Eichelberger, U.S. Patent No. 4,048,490 issued to Troue; U.S. Patent No. 4,948,980 issued to

Weidekamp; U.S. Patent No.5,200,156 issued to Weidekamp; and U.S. Patent No. 5,348,665 issued

to Schulte teach the irradiation of fluids in an omnidirectional fashion with a large surface area.

However, U.S. Patent No. 4,397,823 issued to Dimpfl; U.S. Patent No. 4,622,115 issued to O'Neill; and U.S. Patent No. 4,803,365 issued to Krause, et al., are EMR devices which utilize collimated radiation. The advantage of using collimated radiation is that the increased power density

allows for a decrease in residence time, thus decreasing the conduit size. However, these devices

have a major drawback. When the optical member within the fluid becomes dirty, the flow of the

fluid must be stopped in order to clean the optical member.

Thus, all of the aforementioned prior art systems with exception of the Trojan system must stop the fluid flow in order to clean the quartz sleeves or windows. However, the Trojan system

takes advantage of not stopping the fluid flow by utilizing an open channel, but is flawed because

this design allows for photoreactivation. Finally, all of the systems utilize either low power density radiation emitters such as long-arc mercury vapor lamps or high power density radiation emitters

such as CO₂ lasers. The inherent drawback of these designs is that neither device can replace the

other for its specific application.

From a review of the above mentioned references, it can be seen that the ideal EMR system should combine the following features: ( 1 ) effective irradiation of the fluid, (2) inexpensive and non- disruptive operation of the process flow by the installation and operation of the radiation sources, (3) minimization of safety hazards during operation of the system, (4) low-cost maintenance of

EMR-permeable materials, and (5) simple installation and retrofitting procedures for existing treatment equipment. However, experience has shown that satisfaction of the first criterion usually means sacrificing one or more of the rernaining design factors.

Therefore, the present invention, which will be described in detail below, provides superior

EMR delivery to the fluid to be treated, safely isolates the EMR source from the fluid without interrupting the fluid flow, reduces costs associated with installing and maintaining the EMR

sources, and installs easily into existing structures by using standard flanges and hardware already

present within the piping system.

SUMMARY OF THE INVENTION

Therefore, it is an object of the present invention to provide a device for irradiating fluids

which is capable of subjecting the fluid to EMR at a wavelength, focus and intensity that is superior

to prior methods.

An additional object of the present invention is to provide a device for irradiating fluids which does not interrupt fluid flow.

Another object of the present invention is to provide a device for irradiating fluids which

permits the isolation of the EMR source for maintenance without interrupting fluid flow.

Still another object of the present invention is to provide a device for irradiating fluids which

can be easily installed via standard flanges which are typically used in fluid applications.

Likewise, it is an object of the present invention to provide a device for irradiating fluids

which is capable of changing the power density of EMR at specific wavelengths in situ.

Additionally, it is an object of the present invention to provide a device which uses clean

technology for manufacturing and eliminates the use of the toxic metal Mercury. Still another object of the present invention is to provide a device for irradiating fluids which can be easily installed via standard valves and quick connects which are typically used in fluid

applications.

employs the retrofit of "off-the-shelf EMR sources and materials to existing structures within plants.

employs redundant EMR sources to increase the absorbed dose to the fluent material. These and other objects and advantages of the present invention will no doubt become

apparent to those skilled in the art after having read the following description of the preferred embodiments.

Therefore, a device for irradiating a fluid containing molecules subject to photolytic fission within a conduit, wherein the conduit includes a first opening and a longitudinal axis, the device

comprising a valve fluidically connected to the first opening, the valve having a passageway leading

to a second opening; a first optical member sealing the second opening; and an electromagnetic radiation (EMR) source positioned relative to the first optical member such that the EMR is directed,

preferably along the longitudinal axis, through the first optical member and the passageway and into the conduit when the valve is in an open position; wherein the first optical member is constructed

from a material which is permeable to the EMR. The EMR source is preferably adapted to emit

EMR at a wavelength sufficient to cause photolytic fission of the selected molecules in the fluid, and more preferably adapted to emit EMR at a wavelength sufficient to cause photolytic fission of nitrogen trichloride, diatomic chlorine, or both. Also, an air purging device is optionally provided

near the valve so that fluid may be purged from the vicinity of the first optical member when the

valve is being closed. Additional optical members, such as a filter, may be optionally disposed

between the first optical member and the EMR source.

Also, a device is disclosed for irradiating a fluid containing molecules subject to photochemical reactions within a conduit, wherein the conduit includes a first opening and a

longitudinal axis, the device comprising a valve fluidically connected to the first opening, the valve

having a passageway leading to a compression fitting with a second opening; a first optical member

sealing a light tube attached to an EMR source such that the light tube EMR source is insertable through the second opening of the compression fitting and through the first opening of the valve

when the valve is in the open position. The first optical member is constructed from a material

which is permeable to the EMR. The EMR source is preferable adapted to emit EMR at a wavelength sufficient to cause photolysis of the selected molecules in the fluid, and more preferably

adapted to emit EMR at a wavelength which is absorbed by contaminants such as pathogenic

microorganisms, organic molecules, inorganic molecules, ozone and water. Also, valves are

optionally provided on the light tube and the EMR source so that the gases may be changed to allow emission of EMR at different wavelengths and intensities. Finally, an air purging device is optionally provided between the valve and compression fitting so that fluid may be purged from the

vicinity of the area between the valve and compression fitting when the valve is being closed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1A is a cross-sectional exploded view of a first embodiment of the present

invention.

FIGURE IB is a cross-sectional exploded view of an alternate embodiment of the invention.

FIGURE 2A is a cross-sectional exploded view of a preferred embodiment of the invention.

FIGURE 2B is a cross-sectional exploded view of a more preferred embodiment of the invention.

FIGURE 3 is a cross-sectional exploded view of two identical embodiments of the invention

used simultaneously. FIGURE 3 A is a cross-sectional view of a conduit having two EMR sources directing EMR into the conduit in overlapping fashion, wherein EMR is focused into a predetermined region. FIGURE 3B is a cross-sectional view of a conduit having two EMR sources directing EMR into the conduit in overlapping fashion, wherein EMR is collimated along the conduit.

FIGURE 4 is a cross-sectional view of an insertable EMR source just prior to being placed

into an operating configuration.

FIGURE 5 is a cross-sectional view of the embodiment of Figure 4 with the insertion valve

in an open position.

FIGURE 6 is a cross-sectional view of the embodiment of Figure 4 in an operating configuration.

FIGURE 7 depicts the gas containers and related conduits which can be used to change the

operating gas for either or both the EMR source and the light tube, as well as the air purging device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Turning now to Figure 1A, a first embodiment 1 of the present invention is shown in an

exploded view as being connectable to a conduit 2 which may contain a fluid. For the purposes

herein, this invention will likely find its greatest utility in chlorine production environments, wherein

the fluid 3 is chlorine wet gas (chlorine having 150 ppm by weight or greater of water). In such

environments, three of the various components of the chlorine stream of primary concern will be

diatomic chlorine (CL), diatomic hydrogen (H,), and nitrogen trichloride (NC1₃), each of which may

be subjected to photolytic fission. Use of the term "photolytic fission" is meant to include either

homolytic fission (in the case of like atoms, such as in CL) or heterolytic fission (in the case of dissimilar atoms, such as in NC1₃), as applicable. It will be appreciated to those of ordinary skill that the invention may be applied to any number of other environments where the fluid to be treated is something other than chlorine, and that the operational parameters of the invention may be altered

to suit the particular needs of the fluid being treated. For instance, in a sulfuric acid plant, in a semi¬

conductor plant or in an electrical generation plant's flue gas. However, for the sake of simplicity,

the remainder of this disclosure will provide a detailed explanation of the invention as applied to the treatment of chlorine.

Conduit 2 includes a longitudinal axis 5 and an opening 4 which would normally be closed

by a blind flange (not shown). Installation of the first embodiment 1 involves an initial shut-down

of the fluid flowing through conduit 2 (with subsequent air purging) so that removal of the blind

flange can be accomplished with no safety hazard due to chlorine leaks. After removal of the blind

flange from opening 4, an optical member 6 is sealably secured over opening 4 by an annular flange

7 having an aperture 8.

Optical member 6 may simply comprise a flat plate constructed from a material which is

permeable to the EMR emitted by the EMR source, which will be described further herein.

However, optical member 6 must also be strong enough to withstand the operating pressures of the

system, such as the vacuum conditions within the conduit 2. For example, in the case of a chlorine

production environment used in testing the invention, the optical member 6 was an annular edge

sight glass constructed of Pyrex®, which is a registered trademark of Corning Glass Works (Glass

Code 7740), having a thickness of %". The transmittance of the optical member 6 as used in testing was approximately 60%.

The diameter of aperture 8 should preferably be at least as large as the diameter of opening 4,

but smaller than the diameter of optical member 6. Annular flange 7 is preferably constructed of

plastic or other material resistant to chemical degradation and is tightened against optical member 6 using a plurality of bolts 9 engageable with conduit flange 10. First and second gaskets 11,12 are

preferably constructed of tetrafluoroethylene (TFE), polytetrafluoroethylene (PTFE), or equivalent

material and are installed on each side of optical member 6 in order to ensure a leak-proof seal and

provide a cushioned surface when optical member 6 is held between conduit flange 10 and annular

flange 7.

An EMR source 15 is positioned relative to the opening 4 such that the EMR emitted by the

EMR source 15 is directed into the conduit 2. EMR source 15 is electrically connected to an external

power supply 16, and may be supported by any external rack or support device 17. In order to

achieve the maximum amount of exposure of the fluid 3 to the EMR, EMR source 15 should be

positioned such that the EMR is directed primarily along the longitudinal axis 5 of the conduit 2.

Generally, EMR source 15 may be any device, such as a lamp 18, adapted to emit EMR capable of

causing photolytic fission of selected molecules. In a chlorine production environment, and in testing conducted by the inventor, a 100 Watt, Sylvania PAR 38 mercury vapor lamp, Model No. H44GS-100/M, was used. This particular lamp employs a parabolic aluminized reflector (PAR) and

emits EMR at primary wavelengths (in nanometers, nm) of 334.2, 365.0, 404.7, 435.8, 546.1, and

578.0. Since it is known that the wavelength required to break the diatomic chlorine bond is

approximately 495 nm, and that the wavelength required to break the nitrogen trichloride bond is

approximately 598 nm, the EMR source 15 used in the experiments was clearly sufficient to reduce

the levels of hydrogen and nitrogen trichloride in the tests, as summarized below.

The results of three testing runs are summarized in Table 1, wherein the temperature of the

chlorine wet gas was approximately 80-90°C and flowing through a conduit at approximately 934 liters per minute (33 SCFM). Note that one EMR source was used for Test Runs #1 and #2, but that two EMR sources were used for Test Run #3. Figure 3 is a close representation of the conduit used

for testing. The 6-inch internal diameter by 24 inch length conduit was constructed of a Fiberglass Reinforced Plastic (FRP). This equates to an internal volume of 0.392 cubic feet. At a flowrate of

33 SCFM this gives a residence time of 0.714 seconds. A 6-inch pipe has a cross sectional area of

47.88 cm² (1.57295 ft²). However, keeping in mind the definition of power density and dose, it is

measured in irradiated area (cm²) and not in volume (cm³). Thus, the "surface power density" would correlate to a conduit's cross sectional surface area when the EMR is projected down the longitudinal

axis of the conduit. In turn, the EMR passing through this imaginary circle (conduit cross section) is now given in units of Watts per square centimeter. In cases where there is an extremely low

surface power density the units are given in milli(m) or micro(μ) Watts/cm². Since the energy

(EMR) is given in units of watts or joules/second, a dose can be calculated based solely on the cross sectional area of the conduit and the wattage of the EMR source. Correspondingly, this "dose"

remains constant for a given diameter and a given EMR source. The "absorbed dose" by the fluid is based upon mass of the fluid. Consequently, knowing the fluid's parameters such as velocity,

temperature, pressure and molar weight allow for determining the mass flow through a given point

per unit time. On a molecular level, this allows for comparing the amount of photons emitted by the

EMR source per unit time to the amount of molecules capable of interacting with the photons per

unit time. This gives a ratio of molecules to photons. In an application of the present invention

involving the irradiation of chlorine, the chlorine molecule may cleave to form a chain reaction with

a chain length approaching 100,000 chains. Thus, for every photon emitted, one hundred thousand chlorine molecules may be affected. Likewise, for a given wavelength only a certain number of photons can be emitted for a given EMR wattage. Thus, to maximize efficiency, an EMR source should be chosen to emit photons at or below the wavelength necessary to cleave the molecule. Using photons of higher energy (smaller wavelength) reduces the number of photons which can be emitted by the EMR source. For example, chlorine molecules will cleave at 495 nm. This is visible

light. Choosing an EMR source such as a long linear mercury lamp which emits most of its EMR

at 253.7 nm is not efficient. In fact, using EMR sources such as xenon or sulfur lamps are more

efficient because the EMR peaks close to 500 nm. In addition, these lamps produce a continuous spectrum. Thus, all the photons below 495 nm can be included in a calculation for determining the

wattage of the EMR source for a given pipe diameter and fluid velocity. The energy difference

between a 253.7 nm and 495 nm photon is on an order of magnitude of 1.95. However, many prior

art EMR devices and processes define residence time as the time the fluid and contaminants remain within an irradiated conduit. They do not make a distinction between emitted dose and absorbed dose. The prior art calculations are based on the volume of the conduit. In addition, many prior art

devices assume that 100% of the emitted EMR will be absorbed. Once again, referring back to long

linear lamps, the EMR decreases by the square of the distance from the lamp. Thus, the probability

of absorption by a molecule also decreases by the square of the distance from a long linear lamp.

In addition, since the inside walls of existing conduits are not reflective and many conduits will

absorb radiation, any EMR reaching the walls may be absorbed. As a result of the poor performance

of prior art devices and methods, as well as the confusion resulting therefrom, the inventor has

developed two calculations for designing the ideal process and apparatus for irradiating fluids by subjecting the fluid to EMR at a wavelength, focus and intensity that is superior to prior methods.

Simply, when both calculations are utilized, an existing conduit within a plant can easily be

converted into a photochemical reactor. EMR produced by most lamps has a continuous spectrum that can be approximated as a discrete one. The total number of photons emitted within a given wavelength range can be calculated as follows:

where:

N_p - number of emitted photons per second (between

wavelengths). n_p(λ) - number of emitted photons per second for wavelength λ

P - lamp input power.

p(λ) - output for a given wavelength λ as a percentage of P.

E_p(λ) - Energy of a photon with wavelength λ.

Assuming that λ '_max is small enough so that all emitted photons are capable of breaking the bond for a molecule x:

^E,<K = T?- ≥ £* (-*) → λl _≤ he

Therefore:

Number of photons capable of breaking the bond is:

Then the mass flow that can be processed is

N,' k₉M{x) mm =

where:

m(x) - mass flow of a molecule x

k_a — chain reaction coefficient. M(x) - molar mass of a molecule x.

N_A - Avogadro's number.

Substituting for N_:

Pk_σM(x) m(x) = hcN, M^λ)

If input power P is not known, it can be deterrnined based on the average power surface density,

surface size and wavelength range. P = PsS

P(λ)

where:

Ps - average power surface density. S - surface size.

Substituting for P:

λ/>(λ)

P_sSk_crM(x) m(x) = hcN p(λ)

If surface is a circle (pipe), then:

s=°

Substituting for S:

Required input power is:

Required surface density is:

P

⁵

Now returning to Figures 3, 3A and 3B, redundancy is necessary in processes specifically when it involves a chemical reaction which can determine the quality of a product. For instance, in a process for producing chlorine, contarninants such as cWoramine in particular, nitrogen trichloride, can be removed through a photochemical reaction. Likewise, if hydrogen is present in the stream, removal of hydrogen may be desirable. However, if only one EMR system is utilized and that system fails, this may lead to poor product quality and dangerous conditions. Also, in another process, such as the production of sulfuric acid, sulfur dioxide can be irradiated with EMR in the presence of oxygen for conversion to sulfur trioxide. Currently, a single absorption sulfuric acid plant may have a "tail gas" with a sulfur dioxide emission ranging from 1,800 ppm to 2,000 ppm. A double absorption plant with an interpass absorbing tower may have a stack sulfur dioxide emission ranging from 175 ppm to 250 ppm. Thus, any sulfuric acid plant employing an EMR system for reduction of sulfur dioxide would benefit tremendously from redundancy. Prior art devices suffer in several ways. First, EMR devices which include housings must install two systems for redundancy. This includes additional piping, valves and controls which add to the cost of the system. In addition, if one system fails the other EMR system must be placed online immediately, which requires opening and shutting valves which may interrupt process flow. Likewise, the housings for these prior art systems must be designed according to the plant's process flowrate. The dose necessary to achieve a desired photochemical reaction is based upon the number of photons emitted per unit time. However, most

prior art devices are manufactured for specific flowrate ranges. The housing and EMR sources are designed to emit a calculated dose based upon a certain residence time in which the fluent material remains within the housing. Other prior art EMR systems which allow retrofitting of an existing conduit with redundant EMR sources are inefficient due to several reasons. First, the type of EMR source used may result in self-absorption problems referred to earlier herein. Second, the direction in which the emitted photons travel may result in further inefficiencies because of absorption by the conduit itself. Third, the placement of the EMR sources may be less than ideal for the particular application. TABLE: I.

Test Run #3

Two 100 Watt Bulbs on test skid %H2 %H2 %H2 NCI3 In NCI3 Out %NCI3

DATE feed outlet Reduction ppm ppm Reduction

11/10/95 1.05 0 100 3 01 97

11/11/95 1.05 0 100 29 01 97

11/12/95 1.05 0 100 28 01 96

94

11/13/95 104 0 100 33 02

11/14/95 104 0 100 31 01 97

11/15/95 104 0 100 33 02 94

11/16/95 1.04 0 100 32 02 94

11/17/95 1.04 0 100 29 01 97

11/18/95 103 0 100 27 01 96 As the results from Table 1 illustrate, both hydrogen and nitrogen trichloride were reduced significantly throughout Test Run #1 and throughout most of Test Run #2. However, a leak was

discovered on October 17, 1995, which introduced oxygen, which is a known chain reaction

terminator, into the chlorine stream. After sealing the leak, Test Run #2 was resumed and hydrogen

levels were undetectable, while the reduction of nitrogen trichloride levels remained about the same.

Test Run #3 was run with two identical EMR sources, where the second EMR source was

positioned at opening 20, similar to that shown in Figure 3, and where the distance between the EMR

sources was approximately two feet. During this test run, hydrogen levels were again undetectable,

and the levels of nitrogen trichloride were reduced even further, as explained below.

In Figure 3, two identical EMR sources were placed opposing one another. As a result, the number of photons entering the conduit were doubled, which effectively doubled the photon per unit area. The results are clear, by comparing Test Run #2 and Test Run #3, that doubling the dose

increased removal efficiency of nitrogen trichloride. In Test Run #2 (for those dates where hydrogen

reduction was 100%), there was an 86.4% average removal of nitrogen trichloride. Now, comparing those results to Test Run #3, nitrogen trichloride removal efficiency was 95.7%. This is a removal efficiency increase of 9.3%. In photochemically reactive streams, such as in the present example and

in processes such as in sulfuric acid production, any increase in removal efficiencies of contaminants

in the stream is highly desirable.

Although Figure 3 demonstrates two EMR sources irradiating toward one another, it should be clearly understood that the invention can be practiced by attaching an EMR source to a conduit in a non-parallel fashion wherein the fluent stream is exposed to intersecting EMR. Such an

embodiment is shown in Figures 3A and 3B. In Figure 3A, an EMR source 18 is attached to a conduit 2 and irradiates a fluent stream through an EMR-permeable optical member 6. A second EMR source 40 is attached to conduit 2 and irradiates the fluent stream through a second EMR- permeable optical member 41. The EMR 45,46 from both EMR source 18 and EMR source 40 are directed into conduit 2 in a focused manner such that an EMR apex 42 is established from the focal

points of both EMR sources 18,40 wherein the EMR energy is greatly increased over that of a single

EMR source. Figure 3B illustrates an arrangement of EMR sources 18,40 similar to that of Figure

3A, but wherein the respective EMR 45,46 is directed in a substantially collimated fashion into the conduit 2. The result of the intersecting EMR in Figure 3B establishes an EMR high density zone 43 wherein the EMR energy is greatly increased over that of a single EMR source. In both Figures 3 A and 3B, additional benefits are realized by increased residence time for the fluent stream, because the fluent stream is exposed to EMR at many more points within the conduit than by using a single EMR source. Thus, it is possible to use the present invention to expose the fluent stream to EMR at all locations within the process flow by placing a plurality of EMR sources at locations along the flow such that the EMR from each EMR source will intersect the EMR from at least one other EMR source to establish a single, interconnecting photochemically reactive zone.

The objective of a preferred embodiment is to emit photons from one EMR source down a longitudinal axis of a conduit in a co-current or counter-current direction of the flow of the stream while employing at least a second EMR source to expose the stream to both EMR sources. This intersecting path of photons and stream is beneficial for three key reasons. First, the redundancy advantages explained earlier herein are achieved. Second, the increased dose from the intersecting

EMR results in increased contaminant removal efficiency due to greater photolytic activity. Third, self-absorption problems are greatly reduced when the EMR sources are oriented in such a manner

that the EMR is intersecting, but where the EMR sources are not facing one another as in Figure 3.

An alternate embodiment 21 of the invention is depicted in Figure IB, comprising a housing

22 which is attached to conduit flange 10 by bolts 9. EMR source 15 resides within housing 22 and

is further bounded by a rear blind flange 23 and optical member 6. Thus, housing 22 may be

construed as a virtual extension of conduit 2. Rear blind flange 23 is removably attachable to

housing 22 by additional bolts 9, and includes means 24 for holding and supporting EMR source 15.

This arrangement allows the EMR source 15 and rear blind flange 23 to be removed together as a

unit so that the EMR lamp 18 may be easily replaced without disturbing the sealed relationship

between conduit 2, optical member 6 and housing 22. Optionally, a second optical member 25, such

as a convex lens, a concave lens, an EMR filter, or other optical element may be disposed between

optical member 6 and EMR source 15 using appropriate fixation means 26 so that the EMR may be

modified in accordance with one or more predetermined characteristics. For example, a filter may

be used to subject the fluid only to EMR having a wavelength of 500 nm or higher, where only the nitrogen trichloride is subject to photolytic fission, as opposed to the diatomic chlorine.

Figure 2A depicts a preferred embodiment 30 of the present invention which is similar in

many respects to the embodiment 1 of Figure 1 A, but wherein a valve 31 is disposed between the

conduit 2 and optical member 6. Valve 31 may be any type of valve, such as a ball valve, butterfly

valve or gate valve, which includes a passageway 32 allowing EMR to be transmitted through the

passageway 32 and ultimately into the conduit 2. Passageway 32 leads into a second opening 33

which is sealed by optical member 6, gaskets 11,12, and annular flange 7 in the same manner as

described earlier herein, except that annular flange 7 is bolted directly to valve 31. Thus, when valve 31 is open, EMR is directed from EMR source 15, through optical member 6 and passageway 32,

and into conduit 2. When valve 31 is closed, no EMR may be transmitted to conduit 2, and optical

member 6 may be removed for cleaning without interrupting the flow of fluid through the conduit

system of the plant, resulting in tremendous savings in terms of labor and production. Preferably,

an air purge valve 34 is fluidically connected between the valve 31 and optical member 6 so that

chlorine or other fluid may be swept away from the passageway 32 and the vicinity of optical

member 6 during the closing of valve 31 for maintenance operations. If desired, suitable automatic

controls may be used in conjunction with valve 31 to enable immediate closure of valve 31 in the

event of a breakage of optical member 6 or other pressure difference in its vicinity.

Figure 2B depicts a more preferred embodiment 40 of the present invention which combines

the valve 31 of Figure 2A with the features of Figure IB. The ability to remove and replace the

EMR source 15 and/or change or add a second optical member 25 are available in this embodiment

without having to interrupt the process flow, as explained earlier herein. Moreover, the valve 31 can

be automated as described for Figure 2A to protect the safety of plant personnel and others.

Figure 3 depicts an arrangement in which two identical embodiments of Figure 1A are employed to effectively double the effectiveness of the irradiation by directing EMR along the same

longitudinal axis, but in opposite directions. As will be understood, any of the embodiments of

Figures 1 A-2B may be used in this configuration, either using identical embodiments or possibly mixing various embodiments, all with substantially identical effectiveness.

Figures 4-7 depict another embodiment 50 of the invention which includes a light tube 51

that is insertable through a valve 52 on the process flow conduits 53. Generally, this embodiment 50

is intended for use with water and wastewater treatment applications, as well as other lighter "fluids" such as air and other gases. However, the operation of this embodiment will be described specifically in reference to wastewater treatment with the understanding that a multitude of other

applications are possible. In a process stream, such as a stream of wastewater 54 flowing through

a conduit 53 in a wastewater treatment plant or other facility, the wastewater 54 may contain a wide

range of organic and inorganic contaminants. In most conduits, access ports or drainage valves 52

are attached at various locations along the conduit 53. In many cases, the valves 52 are of the ball

valve variety, although several types of valves are possible for the same purpose. For the purposes

herein, the invention requires a valve 52 which creates an opening 55 for insertion of an EMR-

emitting light tube 51. Other valves, such as gate valves and butterfly valves are also possible as

long as a sufficiently large opening 55 is created to allow insertion of the light tube 51 as will be

further explained herein. However, operation of this embodiment 50 will be explained with specific

reference to a ball valve without limiting the use of the invention with other valves.

To allow interfacing of the EMR invention 50 with the conduit 53, an intermediate tube 56

is threadably or otherwise sealably connected to a mating flange 57 on the ball valve 52.

Importantly, the inside diameter of the intermediate tube 56 must be at least large enough for the

insertion of the light tube 51 through the valve 52 and positioned such that the axis of the light

tube 51 is parallel to the axis of the intermediate tube 56. A packing gland or resilient, compressible

seal 58 is positioned at the terminal end 59 of the intermediate tube 56 so that a seal can be

established around the light tube 51 for reasons to be explained. A packing nut 60 having an inner

diameter larger than the light tube 51 is threadably or otherwise tightenably attached to the

intermediate tube 56 so that the seal 58 can be established or released in response to tightening or

loosening of the packing nut 60. The actual EMR device 50 comprises an EMR source 61, such as a short arc xenon lamp

within a ceramic housing, similar to those manufactured by ORC Lighting Products of Azusa,

California. The purpose of this type of lamp is to provide extremely high radiant intensity and luminance. The EMR source is preferable adapted to emit EMR at a wavelength sufficient to cause photolysis of the selected molecules or contaminants in the fluid, and more preferably adapted to

emit EMR at a wavelength which is absorbed by contaminants such as pathogenic microorganisms,

organic molecules, inorganic molecules, ozone and water. The EMR source is powered by a

conventional external A/C power supply, and it includes an appropriate D/C power supply and

voltage regulating electronics. The EMR source also includes a purge/fill valve 62 which enables

replenishment or replacement of the xenon gas which surrounds the lamp itself. In this manner, the

xenon gas can be replaced by other types of gases so that the intensity and wavelength of the EMR

source can be varied to suit the particular irradiation requirements of the fluids to be treated.

A collimating light tube 51 is fixedly attached to the EMR source so that the radiation

emitted travels entirely through the light tube 51. A lens 63, preferably constructed from industrial

sapphire or other material permeable to EMR, is sealably attached to the terminal end 64 of the light

tube 51 to prevent wastewater 54 from entering the light tube 51. The light tube 51 is filled with a

gas, preferably xenon or some other inert gas, to promote maximum radiance of the EMR to the fluid

to be treated. A second purge/fill valve 65 is located on light tube 51 so that the gas can be replenished or replaced in the same manner and for the same reasons as for the EMR source

discussed above. Finally, a relief valve 66 is positioned on intermediate tube 56 so that residual

wastewater 54 entering intermediate tube 56 during installation and removal of the EMR device 50

can be drained for appropriate disposal. Drain valve 66 further allows for purging of the volume between the packing nut 60 and the valve 52 during removal of the device or for the introduction of

a chemical such as ozone or hydrogen peroxide.

In operation, the intermediate tube 56 is first matably attached to the flange 57 on the

drainage valve 52 with the valve 52 in its closed position. Next, the packing nut 60 is sufficiently

loosened so that the light tube 51 may inserted through the packing nut 60 and the seal 58.

Importantly, packing nut 60 should be loose enough to allow sliding of the light tube 51 into the bore

or opening 55 of the valve 52, but tight enough to prevent excessive amounts of wastewater 54 from

leaking from the seal 58. Preferably, drain valve 66 is then opened to allow any wastewater entering

intermediate tube 56 to exit at atmospheric pressure. Next, valve 52 is fully opened, as depicted in

Figure 5, so that the light tube 51 and EMR source 61 may be slidably pushed forward until the

terminal end 64 of the light tube 51 enters the main process stream 54, as shown in Figure 6. Once

the light tube 51 is properly positioned, the packing nut 60 is tightened to eliminate leakage at

seal 58, and drain valve 66 is also closed. Finally, the EMR source is activated, and irradiation of

the wastewater 54 is begun.

Figure 7 illustrates the manner in which multiple gases 70 may be optionally used to replace

or replenish the gases required in both the EMR source 61 and in the light tube 51. Specifically, a

vacuum pump 71 and appropriately positioned valves 72-76 are used to generate a vacuum to move

the gas within the EMR source 61 and the light tube 51 to the appropriate container. Similarly, the

valves 72-76 can be opened and closed in a known manner to move a desired gas within the

pressurized containers into either or both of the EMR source 61 or the light tube 51.

It can be seen that one of the primary advantages of this embodiment 50 is that the process

stream 54 is not interrupted as the EMR device 50 is installed and removed, resulting in significant benefits to the process operators. Moreover, the use of available quick-connect couplings, commonly available and known to persons of ordinary skill in this field, will serve to further reduce the time required to install and remove the EMR device 50.

Claims

CLAIMSI claim:

1. A method for irradiating a fluent material within a conduit, comprising:

(a) directing electromagnetic radiation (EMR) from a first EMR source into said fluent material along at least one longimdinal axis of said conduit; and

(b) directing EMR from a second EMR source such that said EMR from said second EMR source is caused to intersect said fluent material and said EMR from said first EMR source.

2. The method of claim 1, further comprising focusing the EMR from said first EMR source such that an EMR apex is created within said fluent material, wherein said EMR apex is intersected by the EMR from said second EMR source.

3. The method of claim 1, further comprising collimating the EMR from said first EMR source, and wherein said EMR from said first EMR source is intersected by the EMR from said second EMR source such that an EMR high density energy zone is created within said fluent material.

4. The method of claim 1 , wherein said first EMR source is caused to direct EMR in a direction that is non-parallel to the EMR from said second EMR source.

5. The method of claim 1 , wherein said first EMR source is caused to direct EMR in a direction that is substantially parallel to the EMR from said second EMR source.

6. The method of claim 1 , wherein said EMR from said second EMR source is directed along a second longitudinal axis of said conduit.