WO1998011982A1 - Preparation and use of independently generated highly reactive chemical species - Google Patents

Abstract

This invention concerns a method and apparatus for delivery of exogenous non-thermal plasma activated species to a subject fluid comprising: (a) creating activated species in an energizing means; and, (b) introducing said activated species into a subject fluid by high speed injection means.

Description

PREPARATION AND USE OF INDEPENDENTLY GENERATED HIGHLY REACTIVE CHEMICAL SPECIES

Related Applications

This application claims priority from Provisional Application

60/026, 123 filed September 20, 1996.

Field of the Invention

This invention concerns a method and apparatus for delivery of

exogenous non-thermal plasma activated species to a subject fluid

comprising

(a) creating activated species in an energizing means; and,

(b) introducing said activated species into a subject fluid by high

speed injection means.

Background

This invention addresses air pollution control as well as an

apparatus and method of performing large scale chemistry for bleaching,

enhancing chemical reactions, and pollution removal. Extensive research

is being done worldwide to develop new, commercially viable methods for

removing undesirable chemical species from air or from exhaust gases

such as combustion exhausts, contaminated liquids, such as industrial

process effluents, or biologically contaminated water, and contaminated surfaces. Among the approaches to addressing these needs are

technologies employing electrical excitation of a gas phase. The principal

technologies include excitation by thermal, reactive chemical/catalytic,

and non-thermal electric discharge and electron beam techniques.

Commercial applications in some of these technologies have been

developed, but there is considerable room for advancement. The same

excitation techniques used in pollution remediation or control may also be

applied to chemical processing or synthesis.

Among the technical disadvantages of existing approaches the

following are noted. Thermal approaches alone are non-selective, and

require large amounts of energy. Reactive chemical/catalytic approaches

require purchased chemical reagents. For example, if ammonia is used as

a reagent for the reduction of NO_x in combustion exhaust, its use must

carefully monitored to avoid ammonia release, which could result in a

secondary pollution problem. In catalytic methods, pollutants themselves

or other chemical species or particulates contaminate and inactivate

catalysts. Solid catalysts in particular become fouled and require

replacement or regeneration. Non-thermal electric discharge/electron

beam technologies directly excite all exposed species and, under particular

conditions, are not adequately selective to modify the target contaminants

in a useful manner. For example, in the single step removal of NO_x from

flue gas, nitric oxide in flue gas is rapidly converted into nitrogen and oxygen (desirable products) by nitrogen atoms generated in an electric

discharge. However it is also rapidly converted into nitrogen dioxide or

nitric acid and other oxidized species (undesirable products) by hydroxyl

radicals in the same discharge. The nitric acid then requires additional

treatment {e.g. , chemical scrubbing) to remove it from the exhaust

stream. In this example, achieving a single step NO removal process

requires more control of the flue gas chemistry than is available by direct

excitation of the flue gas. In some applications of coronal discharge

technology, flue gases foul electrodes, which then require electrode

cleaning or replacement. Further, the dielectric properties of materials

used in barrier-type discharges are temperature dependent and thus add

complexity to the design of such reactors used with the temperatures

present in flue gas.

S mary of the invention The present invention entails a method of delivery of exogenous

non-thermal plasma activated species to a subject fluid comprising

(a) creating activated species in an energizing means; and,

(b) introducing said activated species into a subject fluid by high

speed injection means. In some embodiments the introducing of activated

species is in less than about 10 milliseconds, and particularly in less than about 5 milliseconds or less, and more particularly in less than about 1

millisecond, and less than about 0.1 milliseconds. In some embodiments

at least about 50% of activated species created in step (a) is delivered to

said subject fluid, and in certain embodiments at least about 1 0% of

activated species created is delivered in less than about 10 milliseconds to

said subject fluid. It is particularly noted that introducing of activated

species to the subject fluid is within about 10 mm or less, 5mm or less,

3mm or less and 2 mm or less from the point of creating said activated

species represent useful configurations.

Optionally, the method also comprises the step of engaging at least

about 10% of said activated species in target reactions in the subject

fluid. Furthermore, introducing of activated species at an operating

pressure differential above the subject fluid of from about 5 to about 50

psid (pounds per square inch differential) is noted, with specific reference

to an operating pressure differential is at least about 1 5 psid. While a

number of temperature ranges are disclosed introducing activated species

at temperatures up to about 600° C, and particularly less than about

450°C, less than about 250°C and less than about 100°C are noted.

Introduction of activated species at rates from rom about 10 to about 400

meters/second are disclosed with particular reference to at least about

100 meters/second as well as at least about 50 ft/second. The claimed method also includes introducing of activated species

as being unidirectional introducing and absent retrograde introducing of

subject fluid into said high speed injection means, particularly in situations

where back flow or retrograde flow is a consideration such as when the

jet is immersed in liquid.

The claimed method further includes creating of activated species is

by subjecting a flowing gas to passage between two electrodes which, in

combination, comprise a self switching high-voltage electrode.

In other embodiments the invention includes an apparatus for

delivery of exogenous non-thermal plasma activated species to a subject

fluid comprising energizing means in high speed fluid connection with the

subject fluid via high speed injection means, and particularly unidirectional

high speed injection. In particular unidirectional embodiments, the

directional aspect is enabled by a check valve, or by removal of said high

speed injection means from contact with subject fluid. In some apparatus

the energizing means provides up to about 750 joules/liter, or up to about

1000 joules/liter, to an exogenous fluid to be activated to said exogenous

non-thermal plasma activated species, and in particular embodiments the

injection means is a slot or circular jet aperture (e.g. , about 0.2 to about 5

mm in width, and particularly about 0.2 to about 1 mm).

In a particular apparatus wherein the high speed injection means

comprises a body, and that body comprises a high dielectric insulating tube having a front end nearer to a reaction chamber and a rear end away

from the reaction chamber, and the high speed injection means has a front

exit port in fluid connection with said reaction chamber, and wherein

within the high dielectric insulating tube is a high voltage electrode

extending toward, but not fully to, the exit port of the high speed injection

means the apparatus further comprises a ground return shield and

electrode at the front of the high dielectric insulating tube, and the space

between the end of the high voltage electrode and the front of the jet

comprising an electric discharge volume in fluid connection with the

reaction chamber wherein said electric discharge to reaction chamber

distance is 10 mm or less. In such embodiment, optionally, the high

speed fluid connection with the subject fluid via high speed injection

means further comprises a closure means.

Brief Description of the Drawings

Fig. 1 is an enlarged cross-sectional view of particular high speed

injection means, here a needle style jet, for activated species injection,

including side and jet output end views.

Fig 1 a is the variation on the design in Fig.1 including a wire or

point high voltage electrode instead of a tubular electrode.

Fig. 2 is an enlarged cross-sectional side view of a slit style

apparatus for high speed injection of activated species. Fig. 2a is an external, jet output end view of the apparatus of Fig 2.

Fig. 3 is an end view of an array of curved slit style jets for high speed injection.

Fig. 4 is a side view of a stacked array of curved slit style jets for high speed injection.

Fig. 5 is a diagrammatic representation of an apparatus for

activated species injection for treatment of fluids (liquid or gas) carrying particulates or droplets of liquid.

Fig. 6 is a diagrammatic representation of an apparatus for

activated species injection for treatment of fluids (liquid or gas) carrying

particulates or droplets of liquid, wherein after-treatment is provided.

Fig. 7 is a diagrammatic representation of an apparatus for multiple

activated species injection through independent jets for treatment of

fluids.

Fig. 8 is a diagrammatic representation of an apparatus for

activated species injection for catalysis enhancement and surface

treatment.

Fig. 9 is a diagrammatic representation of an apparatus for

activated species injection for treatment of liquids, suspensions, slurries or

solids in liquids. Fig. 10 is another diagrammatic representation of an apparatus for

activated species injection for treatment of liquids, suspensions, slurries or

solids in liquids.

Fig. 1 1 is another diagrammatic representation of an apparatus for

activated species injection for treatment of liquids, suspensions, slurries or

solids in liquids.

Detailed Description of the Invention

This invention is best understood with reference to the following

definitions:

A. "Activated species" are chemical entities not naturally occurring in

useful concentrations in a gas at a given working temperature in the

absence of an activation mechanism such as an electric discharge or an

electron beam. Active species are designated by "•" as in N« for active

nitrogen (atomic nitrogen in this case). By "not naturally occurring in

useful concentrations" it is meant that, absent a specific means for

generation of activated species, insufficient activated species is present to

perform a significant number of "desired reactions" (see below) to reduce

pollutants by more than about 1 % of the concentration of such pollutants

absent such generation.

Energies of activation per atom or molecule producing the activated

species typically are in the range of approximately 0.1 electron volt (eV) to approximately 10 eV. For clarity, unless otherwise stated, eV

references electron volts per activation or per molecule activated.

Activation occurs through a variety of mechanisms including mechanisms

involving direct electron collisions, or secondary or later collisions, light

absorption, and via molecular processes involving ionization or internal

excitation. Excitation to create an activated chemical species typically

requires 0.3 to 10 eV.

Particular reference is made to monatomic nitrogen (N«) and

monatomic oxygen (O») as activated species. Other activated species may

include but are not restricted to the following and their charged (ionic)

analogs: OH •, H₂O •, SH •, CH₃ ^•», other hydrocarbon species. O₃ is

noted as constituting a less reactive activated species.

In the practice of the present invention, the practice of introducing

activated species into the reactor by a piping or channeling means is

severely restricted by a limiting time factor of up to about 50, or

preferably about 20, or more preferably about 10 milliseconds. As noted

below, at a flow rate of about 300m/second, a flow path of longer than

about 3m substantially compromises the ration of activated species

delivered. Thus, high speed injection as defined below is required.

Furthermore, if subsonic speeds of injection are to be maintained, injection

by multi-orifice pipe (from a single source of excitation) is largely

precluded. In such situation, the loss of activated species prior to injection outweighs any increase in mixing obtained by multi-orifice

injection. Structurally, it is a corollary of this physical limitation that the

requirement of generation of activated species for sub-50, and particularly

sub-20, and sub- 10 millisecond delivery to the gas stream precludes

interpolation of a multichannel flow directing system. In particular

embodiments the distance between the electric discharge zone and the

reaction chamber is 1 0 mm or less, and particularly 5 mm or less and

most particularly 2 mm or less.

In the case of NO_x chemical reduction, ozone is less acutely active

as a reactant. Ozone, of course, is generally considered a pollutant if it

constitutes a portion of a process effluent. The half-life of ozone is about

1 second at 400°F, and about 1 minute at 200° F. In particular

embodiments of the present invention, "acutely reactive" activated

species are employed. Such "acutely reactive" activated species will be

understood to be those with a half-life of about 80% or shorter of the

half-life of ozone.

The example of atomic nitrogen upon jet injection illustrates

elements of both activated species and acutely reactive activated species.

The characteristic deactivation (recombination) of atomic nitrogen (N^*») to

molecular nitrogen (N₂) in near ambient temperature air (about 65 °-75 °F)

is approximately 1 to 5 milliseconds beginning at concentrations of about

1 000 ppm N). In a particular embodiment wherein the N» is generated 1 mm upstream of a jet exit aperture, and the injection velocity is 100

meters/sec, less than 1 % of the N* is deactivated before injection. After

injection, contacting of the N^» bearing jet stream with the subject fluid

(including, e.g. NO) within 1 to 5 milliseconds from the creation of the

activated species maintains efficient chemical reduction within the subject

fluid, here, with particular reference to NO reduction. The reaction of N»

with NO in combustion exhaust is typically from about 10 to about 1000

times faster than the recombination of N^** and N» to N₂. This ratio is,

however, influenced by temperature and relative concentrations.

Nevertheless, efficient mixing of activated species with subject fluid is an

important factor in process efficacy. In the process and apparatus of the

instant invention, mixing withing a travel of about 10cm from jet opening

to the point of entry into subject fluid is optimizing.

In particular embodiments of the present invention, such as

bleaching, the presence of ozone is of substantially greater import than in

other applications in which ozone will comprise a component of lesser

significance - ozone-insensitive applications -- wherein vibrationally and/or

electronically excited molecular oxygen, atomic oxygen, (and some

ultraviolet light) as active species from the jet, will be of primary concern.

A conventional ozone generator does not provide these other short lived

species. It is noted that the present invention will produce activated oxygen that reacts with molecular oxygen to, secondarily, produce

ozone.

In other specific embodiments, particular activated species and

combinations of activated species can be sequentially introduced into the

subject fluid. This can be accomplished by a variety of methods. One

such method is to change the composition of gas flowing into a jet to

skew the composition of activated species. Another, and not exclusive,

methodology is to place jets injecting the desired species increasingly

"down stream" in a flowing subject fluid.

B. "Desired Reactions" (as distinguished from "target reactions"

below) are reactions accomplishing the purpose for which activated

species are introduced into a specific fluid. In some NO_x removal

applications this is a chemical reduction reaction, based largely on

generation of reducing activated species such as N», In bleaching

applications, for example, oxidation is the desired reaction, based largely

on the generation of oxidizing activated species such as Ov

C. "Energizing" shall mean imparting to a molecular moiety at least

about 0.1 eV above the normal energy state (i.e. , "ground state") to

create activated species.

D. "Energizing means" shall be the source of energy for energizing

molecular moieties, and shall include coronal discharge, arcs, radio

discharges such as microwaves, non-thermal plasma discharges, radioactive sources, and light (including lasers). Typically energizing

means will impart from about a few electron volts, often on average about

5-1 OeV (such as a coronal discharge apparatus), up to hundreds of kilo

electron volts (such as by electron beam excitation or e-beam) which

provides electron energies in the range from about 10 keV (kilo electron

volt) to about 1 MeV (mega electron volt). A delivered energy of from

about 0.1 to about 10 eV is generally required to create an activated

specie.

E. "Exogenous" shall reference a source of molecules and moieties to

become activated species other than the specific molecules and moieties

of the subject fluid being treated by activated species. By way of

example, a combustion exhaust stream is treated by activated species

generated from an exogenous source wherein the source is ambient air,

compressed nitrogen or compressed oxygen which is then subjected to an

energizing means.

It is to be understood, however, that the subject fluid can, upon

treatment, provide a source of "exogenous" molecules and moieties. One

primary activated species is atomic nitrogen, and subject fluid can be a

source of nitrogen. In one embodiment of such treatment, the subject

fluid - a gas - is mixed with additional fuel and burned to remove

remaining oxygen. Then the gas is dried to remove water. The remaining

constituents are primarily nitrogen and carbon dioxide, which are excited to produce the active species. In particular applications, the economics of

this process are better than purchasing nitrogen or separating it from air.

As a general description, this treatment of subject fluid to provide

exogenous species for activation is the chemical modification of subject

fluid before excitation for injection. In one example, a portion of the flue

gas is used as chemical feedstock for a process which generates the

appropriate reagent mixture for excitation and injection.

F. "Fluid-external system" refers to a system not in fluid

communication with a subject fluid except by injection means. This means

that only external air (or other fluid) is being activated for injection. In

defining the fluid-external system it is understood that while the injection

means comprises a port into the exhaust system, the system will be

termed external.

G. "High Dielectric" refers to a dielectric constant approximately of

about 4 up to TiO₂ or ZrO₂ of 80 or beyond. It is noted that alumina,

zirconia, magnesia or a titanate (e.g. calcium, zinc or barium), and

optionally including TiO₂ are high dielectrics.

H. "High speed injection" shall be understood to be a relative term

predicated on the life span of an activated species from its creation. High

speed injection will be understood to mean a speed of injection sufficient

to transport the activated species beyond the injection means and into

potential contact within subject fluid where the target reaction(s) is to occur, and before a substantially total retrograde reaction(s) occurs. In

particular embodiments of the present invention, the quantity of activated

species brought into potential contact with the desired reactants in the

subject fluid are from about one to about five times the stoichiometrically

required amount for complete reaction. In one embodiment, at least 5%

of the activated species is brought into "potential contact" with the

subject fluid where the target reactions are planned, and in particular

embodiments at least about 1 0%, 20%, 30%, 40%, and 50%. By way

of example, it is noted that N» has a half-life is less than about 10

milliseconds at atmospheric pressure in air at normal room ambient

temperature (about 65 °-75 °F). When flow through an injection means is

about 300m/sec, activated species are injected into subject fluid when the

point of generation is within less than about 3m feet from the end of the

injection means where it is inserted into the fluid. In preferred

embodiments, the transport of activated species will not exceed one foot,

or as otherwise limited by the physics of gas jet formation in the subject

fluid with particular reference to the half-lives of activated species.

Clearly, an energizing means located within millimeters of the end

of the injection means, which then offers a short time for delivery of

activated species to the subject fluid, is advantageous. Additionally,

increasing the rate of transport of activated species through an injection

means will also be advantageous to deliver of more activated species to a subject fluid and increase potential contact. However, specific speeds

contemplated as "high speed" include jet exit gas velocities of about

1 0m/second up to about 400m/second are contemplated.

I. "Injection means" shall mean an apparatus for generation of highly

reactive or activated species, as well as the conduit or means by which

such activated species are introduced into a subject fluid, such as into a

subject fluid stream. The injection port through which the activated

species ultimately flows into the subject fluid can be of a variety of

shapes including nozzles or elongate slits bearing straight or curved

apertures.

The angle of entry of injection relative to the flow of subject fluid in

a subject fluid stream is particularly noted. While injection at right angles

is noted, other angies of entry and types of nozzles are specifically

contemplated. It is understood that factors such as viscosity, flow rate,

temperature, pressure, turbulence, Newtonian fluid considerations, and

other factors will effect the optimizing of introduction of activated

species into a subject fluid.

The process of optimizing the production and injection of activated

species into a subject fluid typically will consist of both numerical

modeling and experimental parameterization. The numerical modeling

includes calculated production of activated species as a function of

excitation conditions, temperature and chemical composition of the subject fluid, gas pressures, injection velocities and geometry, mixing

dynamics, and chemical kinetics calculations of the desired and competing

reactions. The experimental optimization includes measured chemical

reaction (desirable and undesirable) as a function of position downstream

of injection, excitation conditions in the jets, temperature and chemical

composition of the subject fluid, gas pressures, injection velocities and

geometry. It is to be understood that gas jets may further include the

electrical properties and electrical means of a diode. In the case of a

continuously flowing process subject fluid, optimization will include

measurement of the extent of chemical reactions as a function of position

(time) downstream of the injection point(s).

Analysis of post-reaction subject fluid such as by gas spectroscopy

is useful in determining residual pollutant composition, and the efficacy of

reaction condition adjustments.

In particular applications, it is important that injection be

unidirectional and absent retrograde introducing of subject fluid into said

high speed injection means. This is particularly important in methods

directed to injection into liquids such as paper pulp slurry. Maintenance of

unidirectional flow and the exclusion of retrograde flow is accomplished

by a variety of means. In one embodiment the injection means is simply

maintained at a positive pressure differential as to the subject fluid - even

if no activated species are being generated. In another, the injection means port is closed or covered over. In particular embodiments, the

injection means is separated from the subject fluid. Separation is

accomplished variously by such means as removing the injection means

from the subject fluid, by the step of withdrawing the apparatus for

creating activated species from the subject fluid, or ~ in the case of a

liquid subject fluid, by withdrawing, repositioning, or reducing the level of

subject fluid from the conduit or chamber in which the subject fluid is

contained or flowing.

J. "Non-thermal plasma" shall mean low temperature or non-

equilibrium concentrations of activated species as determined relative to

their concentrations at ambient temperature. Plasma shall mean a partly

or completely ionized gas.

A gas as a whole is partially ionized if a fraction of the gas

molecules in it are ionized. Partly ionized is used in reference to a

particular molecule or atom if the discussion concerns, for example, how

many electrons have been removed from that molecule or atom. By way

of example, helium has a total of 2 electrons when electrically neutral. If

one looks at doubly ionized helium He^{+ +} , then at He⁺ is termed partly

ionized. (He^{+ +} is also called an alpha particle).

By way of example, at 50°C, free nitrogen is virtually totally in the

ground electronic and vibrational state of N₂ and not in the N^*> monatomic

state. A plasma in which N» exists at about 450°C or less is a non- thermal plasma. Energizing N₂ to cause an increased N«:N₂ ratio is an

example of the creation of a non-thermal plasma. Thermal dissociation of

N₂ to N^« is insignificant except at temperatures above about 4000K.

The following is an estimate of the energy efficiency of a non-

thermal plasma generated active species injection process. In this

example the process is directed to NO removal by chemical reduction of

NO with N« in combustion exhaust gas. Other processes are similarly

analyzed. This is intended as one example, and not the only process to be

addressed by the jet injection technique.

It is estimated that the practical efficiency of converting energy

delivered to a nitrogen (non-thermal) plasma into nitrogen dissociation or

other useful active species to be approximately 70%. Thus for 100 watts

electrical power dissipated by the non-thermal plasma source,

approximately 70 watts contribute to breaking the chemical bonds in

diatomic nitrogen gas to form N«. In some applications, a practical

activation processes has a higher or much lower efficiency than shown in

this example, with a probable range of between about 10% to 90%

conversion of energy delivered to the plasma into useful excitation.

One advantage of a particular activation process is its economics in

view of the presence or absence of commercially competitive processes.

A practical efficiency of delivering N« to the combustion exhaust

before it undergoes recombination or other undesirable reactions is estimated to be 60%, so approximately 6 of every ten N» formed reaches

the flue gas for reaction. The efficiency of delivering other activated

species to the combustion exhaust will depend on the lifetime of the

activated species under the operating conditions of the system, and the

delivery speed and geometry.

It is estimated from kinetic modeling calculations that to react

completely with a given concentration of NO in exhaust gas, the optimum

injected, volume averaged concentration of N^» is approximately 1 .5 to 3

times the initial NO concentration. Thus, for an exhaust NO concentration

of 100 ppm, N» should be delivered to and mixed with the exhaust gas to

provide an effective concentration of approximately 1 50 ppm to 300 ppm.

One nitrogen dissociation can yield two N^», so between 0.75 and 1 .5

times the amount of NO is needed of nitrogen molecular dissociations. In

addition to the operating range in this example, it is in some situations

useful to react with only a fraction of the target reactant in the subject

fluid. If, for example, the NO_x concentration need only be reduced by

20% (e.g. to reach regulatory compliance for the exhaust stream), N« in

the amount of 0.1 5 to 0.3 times the amount of NO in the exhaust stream

is required.

A commonly used energy reference for calculating the efficiency of

removing NO is the energy required to dissociate NO into N» and O» (- 7.5 eV). Based on this criterion, the input of 7.5 eV per NO molecule

removed would constitute 1 00% efficiency.

From the above estimates, the overall energy efficiency of process

is on the order of 46%, requiring approximately 1 7 eV per NO molecule

removed by chemical reduction. Although higher overall efficiencies are

generally desirable, it is estimated that efficiencies as low as less than

approximately 1 % may be useful for some processes. Laboratory

measurements to date have demonstrated efficiencies of this process to

up to approximately 10%.

Based on 46% overall efficiency, an exhaust gas flow of 1000

scfm (standard cubic feet/minute) containing 1 00 ppm NO would require

approximately 3 kW of electrical power delivered to the jets to completely

react the NO.

It will be particularly understood that N*», or O^» between about 5 °C

and 450°C, and particularly below about 300°C, and particularly in the

range of about 250°C to about 5°C, and more particularly about 1 00° to

about 30°C are low temperatures as regarding a non-thermal plasma.

K. "NO_x" shall mean any oxide of nitrogen, including, but not limited

to, NO, N₂O, NO₂, N₂O₅, N₂O₃, NO₃.

L. Potential contact shall mean that the activated species is in a

reactive proximity with the subject fluid. By reactive proximity is meant that activated species are present in the subject fluid such that, in some

instances, target reactions can occur.

M. "Reduction Promoting" and "Oxidation Promoting" are reciprocal

concepts. N^« - absent other activated species - favors reduction. OH»

and O» favor oxidation. In the example of removing NO from combustion

exhaust, we refer to the overall reaction to form O₂ + N₂ as chemical

reduction, and to form NO₂ (or acid) as oxidation.

Depending on the application, Reduction Promoting or Oxidation

Promoting will be the more useful reaction. It is contemplated that the

composition of the exogenous gas is adjusted to provide a bias in the

proportion of activated species which favor oxidation or reduction. For

example, in some embodiments the exogenous gas consists of

substantially pure nitrogen, or in another embodiment, water saturated O₂.

Conditions arising from the use of substantially pure diatomic nitrogen will

favor reduction while those with water saturated O₂ will favor oxidation.

N. "Retrograde reaction" shall mean those reducing or destroying

activated species prior to the entry of such species into the subject fluid.

For example, if N» is the active species, two N* species recombining into a

single N₂ molecule prior to the entry of the activated species into the fluid

stream is a retrograde reaction. Similarly, if OH is the active specie, an

OH" reacting with an H» to form H₂O is a retrograde reaction. Dampening

of a vibrationally energized moiety prior to its entry into a subject fluid is a retrograde reaction. Such reaction is termed substantially total if about

99% or more of the activated species revert to non-activated species

prior to entry into the subject fluid. It is understood that such reactions

can and will occur after injection into the subject fluid, but this is

understood as not negating the opportunity for a target reaction in the

subject fluid.

O. "SO_x" refers to oxides of sulfur including, SO₂, H₂SO₄, H₂S, CH₃SH,

and CH₃S₂CH₃.

P. "Subject fluid" shall be expansively understood to mean a liquid or

gas. It is understood that such subject fluid or gas will, in certain

embodiments, contain volatilized compounds such as chlorocarbons,

sulfur dioxide, nitrogen compounds, and hydrocarbons, and will, in some

embodiments, contain particulates, and biological organisms, or transport

activated species to solids such as catalytic surfaces where the target

reactions are to occur. Examples of such particulates, catalytic surfaces,

and organisms are, without limitation, soot, paper pulp fibers such as

wood and cotton, vanadium pentoxide, zeolite, and bacteria. The

foregoing is contained variously in internal combustion engine exhausts,

flue gas, climate control air streams, water droplets within such air

streams, reaction chambers, and liquid slurries. Subject fluid in motion is

termed a subject fluid stream, but will not, unless explicitly stated, refer

to the fluid carrying activated species from the point of generation to the subject fluid wherein the target reactions are to occur. It is to be

understood that the target reactions need not be reactions on the treated

fluid but, in fact, usually will occur as to materials entrained therein or on

solid surfaces exposed to the subject fluid.

Q. "Substantially" in referring to the post-reaction form of NO_x shall

mean at least about 50%, and preferably at least about 80% of all NO_x is

converted to either N₂ or acid.

R. "Target reaction(s)" shall mean reactions between activated species

and elements of the subject fluid, including particulates or compounds

within said subject fluid, or entrained in a subject fluid stream. The term

target reactions is expansively used and - while it encompasses "desired

reactions" - it stands in contrast to the term "retrograde reactions. " By

way of amplification, reaction of activated species with NO_x compounds

altering the distribution of NO_x compounds or reducing the presence of

nitrogen oxides in an exhaust gas stream, or reaction of activated species

with bacteria in a bactericidal process would be target reactions, and, in

particular applications, the "desired" reaction. However, "side reactions"

that are not necessarily the desired reactions, but are nevertheless

reactions between elements within the subject fluid and not retrograde

reactions are also to be understood to be target reactions. Thus two N-^*

atoms as delivered into the subject fluid, and therein recombining to N₂

represent a target reaction. This is an important consideration because the fact of delivery of activated species to the subject fluid represents the

potential for desired reactions.

S. "Vibrationally activated" shall mean a species with at least about

0.1 eV of vibrational activation as exemplified by vibrationally activated

diatomic nitrogen (N₂*>) or oxygen (O₂»).

Energy Considerations

In the practice of this invention, attention is brought to the energy

efficiency of a non-thermal plasma generated, activated species injection

process. Consider the case of NO_x removal wherein NO is the NO_x

species and N» is the agent of chemical reduction. The use of non-

thermal plasma offers a particular advantage in the energy efficiency of

the present invention. Temperatures below about 600°C, or preferably

below about 450°C and preferably below 250°C and particularly in the

range of about 100°C to 1 5°C are useful in the present invention.

It is to be understood that the non-thermal plasma generation

temperature is independent of the presenting flue gas temperature.

Energy is further saved in that high temperature gases are not required to

maintain activity of the activated species until delivery to permit delivery

of the activated species to a point where a target reaction can occur.

The practical efficiency of converting energy (e.g. electric

discharge) to a nitrogen (non-thermal) plasma or other useful active

species is approximately 70%. Thus, for 100 watts electrical power dissipated by a non-thermal plasma source, approximately 70 watts

contribute to breaking the chemical bonds in diatomic nitrogen gas to

form N^**. The practical efficiency of delivering this N^*> to the combustion

exhaust before it undergoes retrograde reaction such as recombination or

other undesirable reactions is, in one embodiment, about 60%, so

approximately six of every ten N« formed reaches the flue gas for

reaction. In some embodiments it is more convenient to express energy

input as measured by input to the gas jet. In such instances, energy input

up to about 750 joules/liter is effective.

Kinetic modeling reveals that to react completely with a given

concentration of NO in exhaust gas, the optimum injected volume

averaged concentration of N^« is approximately 1 .5 to 3 times the initial

NO concentration. Thus, for an exhaust gas NO concentration of 100

ppm, N^*> is delivered to, and mixed with, the exhaust gas to provide an

effective concentration of approximately 1 50 ppm to 300 ppm. One

diatomic nitrogen dissociation yields two N» atoms. Therefore, N₂ , via

molecular dissociation to N^*> of between 0.75 and 1 .5 times the amount

of NO is preferred.

A useful energy reference for calculating the efficiency of removing

NO is the energy required to dissociate NO into N» and O«, which is

approximately 7.5 eV. Based on this criterion, the input of 7.5 eV per NO

molecule removed would constitute 1 00% efficiency. From the above calculations, the overall energy efficiency of process is, in some

embodiment, on the order of 46% relative to the dissociation energy of

NO, and requiring approximately 1 7 eV per NO molecule removed by

chemical reduction.

Laboratory measurements to date have demonstrated efficiencies of

this process up to approximately 10%, but it is anticipated that about

46% is obtainable.

Based on 46% overall efficiency, an exhaust gas flow of 1000

scfm containing 100 ppm NO requires approximately 3 kW of electrical

power delivered to the jets. In laboratory testing of NO_x removal by

oxidation or by chemical reduction, high voltage power was generated

from 1 20 vac, 60 Hz line power using a 24000 volt, 5 kVA transformer.

For tests at power frequencies other than 60 Hz, the line power was

conditioned before the transformer using a Powertron 3000s or 350s

power amplifier manufactured by the Industrial Test Equipment

Company(Port Washington, NY), and a Circuitmate function generator

FG2 (Beckman Industrial Corp., San Diego, CA) was used as a frequency

source. Voltages were monitored using a Tektronix P601 5 high voltage

probe and Tektronix model 7633 oscilloscope (Beaverton, OR). Many

other well known electric discharge power sources are useful. It is

anticipated that electron beam sources, especially sealed electron beam tubes such as those manufactured by AIT Corporation (Los Angeles, CA),

are also useful as dissociation sources.

Chemical Specificity

Among the operating parameters which can affect the specificity of

the excitation and subsequent chemical reaction processes are the

chemical nature of the activated species, the temperature(s) at which

injection and reaction occur, the timing of the introduction of the active

species to the subject fluid, and the means of excitation producing the

activated species. By way of example, removing NO from flue gas

exemplifies several such points.

Chemical nature of the active species

Consider the activation of oxygen vs nitrogen gas for injection into

flue gas containing NO. In the case of activation of oxygen to produce

O^», the principal chemical reaction with NO in the subject gas produces

NO₂. In the case of activation of nitrogen, the principal chemical reaction

of N with NO in the subject gas produces N₂ + O^*>.

Temperature

Consider the injection of N^« into flue gas containing 100 ppm NO

and also containing 1 0% O2. Both of these component concentrations

are in the normal range for internal combustion engines. In this chemical

environment at 25° C, the rate of the reaction of the injected N» with NO to produce N₂ + O^« is approximately 300 times greater than the rate of

reaction of the same N^» with O₂ to produce NO + Ov The first reaction

represents a chemical reduction path, while the second reaction

represents a chemical oxidation path, so chemical reduction is

overwhelmingly the dominant process.

However, given the same gas composition at 630° C, the rate of

the reaction of the injected N» with NO to produce N₂ + O» is

approximately 1 /7 the rate of reaction of N« with O₂ to produce NO + Ov

At this higher temperature, the oxidation path is the dominant process. In

some embodiments, by controlling the temperature and composition of

the subject fluid and the injected gas provides critical control of the

chemical path.

Timing

Continuing with the example of N» injection, N» recombines rapidly

to form N₂ at gas pressures exceeding a small fraction of a standard

atmosphere, and at temperatures at least up to 700 °C. At near

atmospheric pressure, typical N^« recombination times (assuming other

chemical reactions have not depleted the supply of N) are on the order of

1 to 1 0 milliseconds in the collisional environment. For efficient use of

atomic nitrogen as a reagent for a chemical reaction, delivery for reaction

within less than approximately 10 milliseconds from its time of creation

by an energizing source is indicated. As a general statement on timing, the effective lifetime of the more

useful activated species is from about 0.1 to about 10 milliseconds.

Thus, useful injection times are from about 0.1 to about 1 0 milliseconds

as measured from excitation to injection. Particular note is made of

injections of less than 1 millisecond, and less than 0.1 milliseconds.

Factors affecting flow through the gas jet is a process consideration

substantially intertwined with timing. Jet speeds of about 1 0 to

400 meters/second are useful with particular note of speeds of greater

than about 50 meters/sec, as well as speeds of greater than about 1 50

meters/second. Operating pressure differentials for the flow emitted from

the jet into the subject fluid wherein the pressure in the jet is greater by

about 5 to about 50 psid are useful with note of a differential of at least

about 1 5 psid. Expressed another way, a pressure differential wherein jet

pressure is at least about twice the pressure of the subject fluid is noted.

The foregoing factors are largely accommodated if the jet has a working

pressure of between about 1 and 5 bar.

Means of excitation

Different means of excitation can result in different processes

dominating the activation of species in the jet, and thereby the nature of

the excitation. For example, a high energy electron beam contributes a

larger fraction of its energy into nitrogen dissociation than will a corona

discharge, whereas the corona discharge will contribute more of its energy to the vibrational excitation of molecular nitrogen than will the electron

beam. The choice of corona discharge or electron beam can select for a

dominant mode of activation, and thereby the reactions in the subject

fluid.

It is also noted that electric discharges produce light, including

ultraviolet light, in about the ultraviolet range ( <400 nm). Ultraviolet light

in particular instances induces chemical reactions. Depending on the

requirements of the process, choosing the position of the excitation

relative to the injection (and therefore the injection speed) will select

whether the subject fluid is exposed to this light and therefore whether

the associated chemical reactions will take place in the subject fluid. It is

a characteristic of UV light that UV photons have energy sufficient to

drive photochemical reactions, including dissociating water, and bleaching

reactions. In particular embodiments wherein UV is generated, not by a

conventional UV "lamp, " but as a concomitant of the energy applied to

the fluid of the fluid-external system, UV will both impinge upon the gas

to be activated, as well as penetrate into the subject fluid through the

opening which the gas jet comprises. Penetration into the subject fluid is

enhanced by the absence of an intervening lamp housing which acts to

filter out some or all UV light. In summary, the combination of activated species, temperature

control, injection speed, and means of excitation contribute to the

selectivity of the chemical processes in the subject fluid.

It is an important aspect of this invention that activated species are

delivered as activated species to the subject fluid subsequent to their

exogenous generation from non-thermal plasma. In contrast, generation

of activated species within the subject fluid compromises the chemical

specificity of the present invention.

Process Considerations

In the case of chemical reduction of NO_x by N^**, care must be taken

such that the non-thermal plasma does not generate significant quantities

of NO_x. The activated species jet exits the jet mechanism, driven by the

pressure differential between the discharge volume inside the jet and the

subject fluid.

Note that typically the volumetric flow of jet gas for treating

combustion exhaust (the subject fluid) is expected to be smaller than 5%

of the volumetric flow of the exhaust. In the case of the chemical

reduction of 100 ppm NO in exhaust gas, the theoretical minimum

consumption of nitrogen gas will be 50 ppm, since each nitrogen molecule

can yield two nitrogen atoms. Practical considerations of jet mechanics

and delivery temperature are expected to yield a minimum practical gaseous nitrogen consumption of approximately 1 00 times this figure, or

0.5% of the subject fluid flow.

Any source of gaseous nitrogen may be considered for this

chemical reduction application. This could include air, exhaust gas, or

other nitrogen bearing gas. These gases may be supplied directly to the

jets for some applications. If nitrogen (or other gas) separation is

required for a particular application, commercially available membrane,

differential sorption, or chemical technologies may be applied to

accomplish this.

As to oxygen species, particular attention is directed to control of

the jet chemistry as achieved, in part, through control of the jet operating

parameters. Using the production of O^** for the oxidation of NO to NO₂ or

for bleaching applications, it is noted that at a working pressure of 1 bar

and a jet injection temperature of 230°C, the 50% recombination time of

atomic oxygen in a jet containing nitrogen and 1 % oxygen is

approximately 1 millisecond, for O^» produced at a concentration of 0.5%

in the jet. If the elapsed time from excitation to injection into the reaction

volume is 0.01 milliseconds, then approximately 99% of the generated O«

is available for mixing and reaction with the subject fluid. In this he

principal chemical path for loss of O» is recombination to form O₂, with

less than 5% of the O^» chemically reacting with O₂ to form O₃ on the one

millisecond time scale. If the production of O₃ is desired, 100% O₂ may be used as the jet gas, producing O₃ as a principal reaction product from

O^» + O₂ collisions before exiting the jet. Other transitional species present

include electronically and/or vibrationally activated oxygen and ozone

species.

The Apparatus

Two basic physical configurations of jets are presented. Other

configurations will be apparent to those skilled in the art. One

configuration is jets with holes such as those with injector needles (Fig.

6), and another configuration is slit construction in either a straight or

curved configuration (Fig. 7 and Fig. 8). Typical operating conditions for a

single needle jet is about 5 to 40 scfh flow of the working gas, about 3 to

30 watts of electric power dissipated in the jet, pressure head for the jet

about 5 to 30 psig, outlet aperture of the jet 0.01 to 0.04 inches in

diameter. The upper limit in diameter is determined by the mechanism of

activation, and the transport time of the activated species from activation

to reaction with the subject fluid. Larger diameter jets can generate

greater amounts of activated species, but also in general increase the

average time from activation to reaction, which reduces the efficiency of

the process. Smaller diameter jets can provide locally better mixing in the

subject fluid, but with decreased physical extent of penetration into the

subject fluid of the jet. In the case of arrays of multiple closely spaced jets, it is estimated that aperture diameters as small as about 0.001 inch

may be used, and for large installations, jets with exit apertures up to

approximately 1 inch in diameter may be used.

Narrow slit aperture jets, in one embodiment, are formed by the

close approach of parallel high dielectric tubes with internal electrodes.

The internal electrodes of slit type jets were either centered or off-center

(eccentric) within the high dielectric tubes (or partial tubes), depending on

the experiment. Jets arrays were formed by an assembly of the slit type

jets described above, with alternating polarity electrodes arranged into an

annulus with the central contained volume forming a plenum for the gas

being delivered to the jets. Six

high dielectric tubes were assembled into a hexagonal cross section array

of

radially outward directed slit-type jets.

In another embodiment, the electrodes directly form the slit jet

aperture, without dielectric tubes. In a third embodiment, the slit jet is

curved rather than straight, forming an outward directed jet, an annular

jet, or an inwardly directed jet, depending on details of the physical

design.

Electric power for the jets is provided by any number of sources.

Both low or high frequency AC high voltage (60 Hz to 6000 Hz) with

open circuit voltages up to 30 kV are useful. Among possible discharge sources are high voltage (typically > 5 kV) DC or AC (e.g. 60Hz to radio

frequency), microwave radiation (particularly for slit jets incorporating high

dielectric barriers), electron beam sources (e.g. modular units in about the

20-100 keV range), as well as combinations of these approaches,

including low power high voltage discharge circuits combined with lower

voltage power supplies.

Apparatus Example 1 Jet Construction. Holes

Single or multiple jets with exit holes were typically 0.02-0.04

inches in

diameter. Each jet exits from a small hole in the end of a tubular

assembly which includes an electrical gap near the hole.

Needle jet construction:

Fig. 1 is a diagrammatic representation of high speed injection

means (1 ) inserted into a reaction chamber ( 1 6). As shown in Fig. 1 and

Fig 1 a, a high dielectric insulating tube (2) comprises the body of the jet.

The jet itself has a front hole or port (10) where the jet enters the reaction

chamber (1 6) (or is in fluid contact with the reaction chamber). Within

the high dielectric insulating tube (2) is a high voltage electrode. In Fig 1

this high voltage electrode is (6) and is in tubular form, but in Fig 1 a the

electrode is (22) in the shape of a wire. In both Figs. 1 and 1 a the high voltage electrode extends toward, but not fully to, the front of the jet,

that is the end closer to the reaction chamber. Flow path (14) comprises

the interior of tubular electrode (6) or the surrounding of wire electrode

22. At the front of the dielectric insulating tube and extending back over

said tube is a ground return shield and electrode (4). The flow path (1 4)

leads into an aperture (8) termed the "electric discharge volume" which

leads in turn through port 10 into the reaction chamber. The internal

electrode (6) or (22) is in fluid connection between the jet gas inlet (1 2)

and the reaction chamber (1 6) which contains the subject fluid. High

speed gas velocity is provided by blower (13). The space between the

end of the high voltage electrode (6) or (22) and the front of the jet

comprises the electric discharge volume (8). Emerging from port (10) into

reaction chamber (1 6) is a stream of activated species which (1 7) which,

in particular embodiments, is accompanied by UV light. .

In the depicted embodiment of Fig. 1 , high dielectric insulating tube

(2) is glass with a 6 mm OD, 2 mm ID and is 15 cm long. Tube (2) was

contained within a electrode (4), a close fitting stainless steel jacket. The

stainless steel jacket (4) was closed at the front end except for a central

jet exit aperture port (10), 1 mm in diameter. A stainless steel tubular

electrode (6) was located inside the bore of the ceramic, leaving a 2 mm

gap at forming electric discharge volume (8) between the end of the

electrode (6) and the jet exit hole in the jacket (10). The internal volume of the jet structure containing the discharge volume was constructed to

minimize the possibility of electric discharge along the internal surface of

the apparatus rather than through the gas. The structure also augments

exposure of the flowing gas to the discharge immediately before exiting

the jet. The working gas inlet for the jet entered the jet ( 1 4) at the end

( 1 2) away from the reaction chamber ( 1 6) . Electrical connections ( 1 8 and

20) were powered from an electrical energy source ( 1 9) and were made

to the stainless steel jacket (4) and to the central electrode (6) where it

emerged from the central bore (14).

The apparatus of Figs. 1 and 1 a is operated at a variety f power

levels including 60Hz AC. Under such conditions, the jets shown in

Figures 1 and 1 a exhibit self-switching discharge. Self-switching

discharge arises by the application to the jet of high voltage, here AC at

60 Hz. High voltage will be understood to mean voltages from about

1 0Hz to about 30kHz. The resulting electric discharge between (8)

and( 1 0) in Fig 1 or between (22) and (10) in Fig. 1 a self-switches on and

off at typically 1 5-30 kHz, with the actual switching frequency dependent

on the applied voltage, electric circuit parameters, gas temperature, flow

conditions, and gas composition. The 60 Hz applied voltage approximates

DC relative to the self switching frequency, and applied DC high voltage is

expected to result in similar switching behavior. Self-switching discharge behavior has been observed to date at applied frequencies of high voltage

power between 10 Hz and 30 kHz. The self switching behavior is not

present in the absence of jet gas flow. A practitioner in the art will

understand that the presence or absence of self switching is determinable

by measuring the current wave at the high voltage electrode, with an on-

off reading being determinative of self switching.

Example 2

Jet Injection: N»

The characteristic deactivation (recombination) time of atomic

nitrogen to molecular nitrogen in near ambient temperature air is

approximately 1 ϊo 5 milliseconds (starting with 1000 ppm N). If the

atomic nitrogen is generated 1 mm up stream of a jet exit aperture and

the velocity is 100 m/second, less than 1 % of the atomic nitrogen will be

deactivated before injection. After injection, mixing of the atomic nitrogen

bearing jet and the subject fluid (including NO) must take place within

about 1 to 5 milliseconds to efficiently achieve chemical reduction of NO

in the subject fluid. The reaction of atomic nitrogen with NO in

combustion exhaust is typically from 10 to 1 ,000 times faster than the

recombination of atomic nitrogen to molecular nitrogen (depending on the

temperature and relative concentrations), so efficient mixing is a strong determinant of process efficacy. Thus, a useful N chemical reduction

reactor is designed for jet penetration and mixing of approximately 1 0 cm

into the subject fluid from the jet exit aperture.

Example 2 Jet Injection Construction

An examples of slit jet construction is shown in Figs. 2 and 2a.

Fig. 2 is a cutaway side view of an injection, and Fig. 2a is an outside

view looking at the gas jet output aperture. Gas enters a plenum (64)

through an entry port (62) leading from a high speed blower (not shown).

The activated species jet (70) exits through a slot-shaped aperture (60)

into the subject fluid environment (66) . The electric discharge volume

(58) of the jet, that is the space where activated species is created, is

located between two electrodes (54 and 56) are separated from this

aperture by high dielectric barriers such as walls or tubes (52) and

constitute the slot-shaped jet aperture (60). In other embodiments these

electrodes directly bound and constitute the slot-shaped jet aperture (60) .

Of particular note in the slot-type jet design is that in addition to the

activated species jet (70) itself, ultraviolet light (72) from the excitation

plasma is unobstructedly impinging upon the subject fluid. In Fig. 2a the

ends of the electrodes (54 and 56) are in electrical connection with a power source (53). There is no fundamental restriction on the length of

the electrodes.

Example 3 Jet Injection Construction. Arrays

Figure 3 is a cutaway end on view of one design approach to

building arrays of the slot type jets depicted in Figs 2 and 2a. In Fig. 3 an

assembly of four electrodes ( 1 1 8a and b and 1 20a and b) are arranged

with alternating polarities. In this embodiment, the electrodes are

contained within high dielectric shells (1 14). There are four equivalent

electric discharge volumes (1 1 2), and the dielectric shells themselves form

a central plenum (1 1 6) for the inlet gas supply. The inlet gas connection

is not shown. Assemblies of numerous slot-jets are also useful using this

alternating electrode form.

Example 4 Jet Injection Construction. Curved Slot-Type Jet Arrays

Fig. 4 shows a variation of the slot-type jets depicted in Figs. 2 and

2a, but employing curved slots rather than straight slots. In Fig. 4, the

slots (109) are circumferential with jets (106) emerging outwardly in a

ring. Variations on this design include a cylindrical structure with jets emerging inward radially in a ring, mixing with the subject fluid in a tube

or pipe.

Fig. 1 1 shows jets emerging inward radially in a ring, mixing with

the subject fluid in a tube or pipe. The subject fluid (502) enters the

apparatus at the top and flows through an inner pipe (514) to an exit

(51 2). Jets of activated species (506)enter an pressurize an annulus

(51 6) between the inner enclosure composed of alternate polarity

electrodes (508 and 510) and an outer enclosure piper (504). Annular jets

are also be constructed in a similar manner. In Fig. 4, gas enters the

plenum (104) through a port (102) at one end of the assembly. The jet

slots (109) separate electrodes of alternating polarity ( 1 08 and 1 10),

allowing multiple jets to be built into a single cylindrical structure.

Apparatus Example 5

Fig. 5 is a schematic representation of an apparatus for the

treatment of subject fluid jet injection of activated species. Jet injector

(204) is supplied with high speed gas for activation (206) and energizing

power from power source (202). Suitable power sources include an

electric discharge or electron beam source. Activated species jets are

enter into the subject fluid (21 2) in a reactor (208) which is filled with

subject fluid (static or flowing). In a flowing embodiment, flow is from an

entrance (21 0) to an exit (214) through a reaction zone (21 2). Subject fluid is variously gaseous, liquid, or suspensions, and include solid

particulates. Fig. 5 is representative of the apparatus used to study NO_x

chemical reduction and oxidation, and used with a static charge of subject

fluid. Fig. 5 also represents the apparatus used to establish the ability of

the injectors to perform bleaching of dyes and of paper pulp.

Apparatus Example 6

Fig 6. is a schematic representation of an apparatus for the

treatment of subject fluid using jet injection of activated species, and

including an after treatment scrubber. Jet injector (254) is supplied with

high speed gas (256) and energizing power (252) suitable for an electric

discharge or an electron beam source. Activated species jets are injected

into the subject fluid (262) in a reactor (258) has the subject fluid flowing

from an entrance (210) to an exit (21 4) through a reaction zone (21 2),

followed by an after treatment scrubber (266). The scrubber

encompasses any suitable means to remove products generated in the

reaction zone (21 2), e.g. chemical scrubbing, filtration, condensation.

Apparatus Example 7

Fig 7 is a schematic representation of an apparatus for treatment of

subject fluid using multiple jet injection. In this embodiment, each jet

prepares an independent activated species This embodiment also contemplates the interaction of two or more injected jets. Jet injectors

(303 and 304) are supplied with high speed gas (305 and 306,

respectively) and energizing power (301 and 302, respectively) which is

suitable for electric discharge or an electron beam source. Activated

species jets are injected into the reaction zone which includes a subject

fluid or carrier gas (31 0) entering the reactor (308). The products of the

reactions in the reaction zone (31 2) leave the reactor (308) through an

outlet (314). By positioning the jets in the reactor, sequential reactions

may be controlled. Figure 7 also represents one means of installing

multiple jets of a single type into a reactor.

Apparatus Example 8

Fig. 8 is a schematic representation of an apparatus for the

treatment of solid or liquid surfaces, or for the enhancement or activation

of catalytic surfaces. Jet injector (354) is supplied with high speed gas

(356) and energizing power (352) which is suitable for an electric

discharge or an electron beam source. Activated species are injected into

a reactor (358) which contains subject fluid (static or flowing). Flow is

from an entrance (360) to an exit (364), through a reaction zone (362)

which includes a solid or liquid target surface (366). The activated

species in the jet chemically reacts directly with the target surface to provide a reagent source for catalytic reactions at the surface, or to

activate the surface for catalytic action.

Apparatus Example 9

Fig. 9 is a schematic representation of an apparatus for the

treatment of subject fluid as liquids, suspensions, or slurries. Jet injector

(404) is supplied with high speed gas (406) and energizing power (402)

which is suitable for an electric discharge or an electron beam source.

Activated species jets are injected through an opening (405) into a reactor

(408) which contains subject fluid (static or flowing) (41 2) at a point

below the surface (407) of the liquid. Flow is from an entrance (41 0) to

exit (414). Fig. 9 is representative of laboratory experiments

demonstrating bleaching of dye and dyed paper pulp in water slurry.

In practice, entry of subject fluid into the jet is to be avoided.

Various means are useful to avoid such entry. In one embodiment, a

positive pressure differential sufficient to keep out subject fluid is

maintained at all times across opening (405). In another embodiment, the

surface level (407) of subject fluid is dropped below the level of opening

(405), or alternatively, opening (405) is raised above level (407). In one

embodiment, closure means (409) sealingly occludes opening (405).

Closure means (409) is variously a plug or valve or a closeable diaphragm.

Methodology Biocidal action is obtained in the present invention via electric

discharge jets of activated species (typically, but not exclusively oxygen,

air, or nitrogen) by injection of such activated species into a liquid or gas.

By way of example, biocidal action is useful for ventilation air entering an

operating suite, or for air exhaust from a hospital room or laboratory

where an airborne pathogen (e.g. , mycobacterium, bacterium, virus, prion

etc) is potentially present In addition, as with bleaching, bubbling

activated species through a liquid or slurry reduce or eliminate pathogens

and retard proliferation. Activated species contact and destroy the

pathogen.

In addition to pathogens, this invention is useful in eliminating organisms

such as algae (often a problem in cooling systems) or organisms that are

objectionable for such reasons as their odor production, and which are not

strictly pathogens.

In particular embodiments of this invention, enhancement or

creation of a heterogeneous catalytic surface, or the creation of a more

reactive surface is contemplated. An activated species jet is used to

deliver activated species to a solid or liquid surface, suspension, or

aerosol. By this method the active species enhances the catalytic

properties of the surface, or provides the energy to induce chemical

reactions at or near the surface. This embodiment is particularly useful in

automotive catalytic converters, polymerization initiators, enzyme enhancement, surface cleaning for electronic components and optics, and

semiconductor doping. Another embodiment of the present invention is

directed to gas phase chemistry. One or more jets of activated species

are introduced into a gas phase to cause chemical reactions to occur

5 which otherwise would not occur

or would be unacceptably slow. The non-thermal distribution of active

species allows such highly reactive species to interact at low

temperatures including those below the threshold of activation. In

particular reactions this is near or below about 20° to 25°C (room

I D temperature).

In one example, activated species in the form of hydroxyl radicals

are produced from one or more jets supplied with water vapor. The

hydroxyl radicals are mixed with a gas phase in conjunction with desired

reactants such as hydrocarbon molecules as introduced to the gas phase

is through a second jet. This apparatus and process is particularly useful in

chemical syntheses (particularly at reduced temperatures), destruction of

volatile organic compounds, and control of polymerization reactions.

In a particular embodiment, the present invention is useful as an

electrochemical couple as part of an electrochemical or electrolytic cell.

20 This is similar to use of a hydrogen electrode used as an electrochemical

standard, but with the bubbled gaseous activates species generated in the

present instance by the discharge in the jet. The reactions of the active species at the liquid or solid surface of a cell are measured by standard

electrochemical techniques, new analytical regimes and new chemical

reactions could become accessible in this manner.

As an example of this embodiment, a standard hydrogen or other

reference

half-cell is prepared, and another half-cell of an electrochemical cells

prepared using an electrically shielded jet. The electrode potentials are

then measured to determine the ionic character of the jet species. This process and apparatus is particularly useful in analytical instrumentation, and chemical synthesis.

Example 10 Chemical reduction in an NO spiked airstream using active nitrogen jets

The present invention has the ability to chemically react NO in the

presence of oxygen in air, including chemical reduction of NO to nitrogen. In a reactor substantially as shown in Fig. 5, three nitrogen jets such as

(204) were inserted through and mounted to the walls (207) of a Teflon^®

line flow test reactor (208) of cross section 2.5 x 4 inches. The room air

to be tested flowed vertically through the reactor (208) while the jets

were injected at right angles to the test gas flow (arrow). NO was

injected into the test gas upstream of the test reactor. NO_x

concentrations were measured throughout the testing using chemiluminescence type NO_x analyzers (Series 1 0, ThermoElectron,

Waltham, MA).

The 3 nitrogen jets of this experiment were operated at 44 scfh

nitrogen flow, and 1 .7 scfm total flow in the reaction chamber. The gas

stream tested: 1 2% O₂ (air, diluted with nitrogen gas), and spiked with

NO upstream of the test. The test was run at temperature 80°F. Total

electrical power dissipated in jets when discharge running was 24 watts.

Measured NO_x concentrations:

Electric discharge power OFF: 28 ppm NO, 4 ppm NO2, 1 ppm HNO3

Electric discharge power ON: 0.5 ppm NO, 4 ppm NO2, 9 ppm HNO3

The NO decreased from 28 to 0.5 ppm when power was applied. Thus,

at

least 98% reaction of NO was achieved. The total NO_x (NO + NO2 +

HNO3) decreased from 33 ppm to 1 3.5 ppm demonstrating a 59%

reduction in total NO_x by chemical reduction.

Example 1 1 Chemical reduction in a combustion exhaust using active nitrogen jets

This test demonstrated the ability of the jet injection technique to react

with NO in combustion exhaust gas including the ability to chemically

reduce

NO to nitrogen gas. As in Fig. 5, with the exception that three jets were

inserted through and mounted to the walls of a Teflon^® flow test reactor

(208) of cross section 2.5 x 4 inches.

The combustion gas to be tested was generated in a natural gas

fired burner

and flowed vertically through the reactor in direction of flow (210) while

the jets were injected at right angles to the test gas flow. NO was also

injected into the test gas upstream of the test reactor. NO_x

concentrations were measured throughout the testing using

chemiluminescence type NO_x analyzers. The apparatus comprised 3

nitrogen jets with 44 scfh nitrogen flow, and 1 .5 scfm total flow in the

reaction chamber. The gas stream had 1 .8% 02 bearing combustion

exhaust and was at 400°F. Total electrical power dissipated in jets was

37W when discharge running.

Measured NO_x concentrations:

Electric discharge power OFF: 59 ppm NO, 3 ppm NO2, 0 ppm HNO3

Electric discharge power ON: 1 2 ppm NO, 1 5 ppm NO2, 8 ppm HNO3 The NO decrease from 59 to 1 2 ppm when power was applied. This was

an 80% reaction of NO. The total NO_x (NO + NO2 + HNO3) decreased

from 62 ppm to 35 ppm demonstrating a 44% reduction in total NO_x by

chemical reduction, the conversion of NO to NO2 or to HNO3

Example 12

Chemical oxidation in an SO₂ bearing combustion exhaust using active air and nitrogen iets

This test demonstrated the ability of the jet injection technique to

oxidize NO in combustion exhaust gas including the ability to perform this

reaction in the presence of sulfur dioxide. As shown in Fig 5, except that

8 nitrogen jets (204) were inserted through and mounted to the walls of a

Teflon^® (PTFE) flow test reactor (208) of cross section 2.5 x 4 inches.

The combustion gas to be tested was generated in a propane gas fired

burner and flowed vertically

through the reactor (208) while the jets (204) were injected at right

angles to the test gas flow. NO was also injected into the test gas

upstream of the test

reactor. NO_x concentrations were measured throughout the testing using

chemiluminescence type NO_x analyzers (Series 10, ThermoElectron,

Waltham, MA). SO₂ concentrations were measured using an ultraviolet

fluorescence type SO₂ analyzer. The presence or absence of 3000 ppm

S0₂ had no measurable effect on the experimental measurements, and no change was measured in the SO₂ concentration as arising from the

operation of the discharge jets. Test conditions included 8 nitrogen jets

with 107 scfh air or nitrogen flow, 3.2 scfm total flow in the reaction

chamber.

The gas stream tested was 5% O₂ bearing combustion exhaust at 80°F,

with 75 W total electrical power dissipated in jets when discharge

running.

Measured NO_x concentrations (using air in the injection jets):

Electric discharge power OFF: 40 ppm NO, 38 ppm NO2, 2 ppm HNO3

Electric discharge power ON: 0 ppm NO, 26 ppm NO2, 99 ppm HNO3

Measured NO_x concentrations (using nitrogen in the injection jets):

Electric discharge power OFF: 36 ppm NO, 36 ppm NO2, 4 ppm HNO3

Electric discharge power ON: 0 ppm NO, 4 ppm NO2, 36 ppm HNO3.

Complete reaction of NO was achieved in these tests. With air jets most

of

the chemical reaction of NO was oxidation to HNO3. The total NO_x (NO

+ NO2

+ HNO3) increased when air jets were used, likely due to NO_x generation

by the

electric discharge in the air jets. The reduction in total NO_x achieved in

the nitrogen jet test demonstrates that chemical reduction of NO can be

achieved in a gas stream containing up to 3000 ppm SO₂. Example 1 3

Bleaching of dye and of paper pulp suspended in water Activated oxygen jets

In an apparatus as shown in Fig. 10, an array of nine jets (504), was

mounted in a flat plate (506). The plate was mounted atop a vessel (508)

containing approximately 1 liter of an aqueous slurry of paper pulp (510)

dyed black (Number 1 5, RIT Dye/CPC Specialty Products, Indianapolis,

IN)). The jet tips (51 2) were immersed in the slurry so that the emerging

jets of gas (514) provided agitation of the mixture as well as active

species from the discharge of the jets. The jets were operated with

oxygen from an oxygen tank (51 6) at approximately 5scfh/jet, and from a

high voltage power source (518). After two hours of introduction of

activated O* introduction from approximately 8 watts applied to the jet

discharge, the black dyed paper pulp had lightened to a light gray.

Samples of the pulp were dried and the treated and untreated papers

compared to positively confirm the bleaching effect. As a control, an

identical vessel of dyed paper pulp was subjected to bubbled- oxygen from

the same jets for identical time, but without electrical power being applied

to the oxygen stream. This resulted in no apparent bleaching of the paper

pulp.

Example 14 Bleaching of dye solutions Activated oxvαen jets In an apparatus similar to that of Fig. 10, but with only a single jet, the jet

(51 2) was immersed in 100 cc of water made opaque with black cloth

dye (RIT Number 1 5). The jet tip was immersed in the dye solution so that

the emerging jets of gas (514)at a flow rate of δscfh at approximately

80 °F provided agitation of the mixture as well as active species from the

discharge of the jets. The jets were operated with oxygen from an

oxygen tank After 30 minutes of introduction of activated O» introduction

from approximately 10 watts applied to the discharge, the black dyed

lightened to a transparent yellow-brown color.

In other bleaching applications such as those bleaching cloth, activated

species can be introduced into the washing tank of a washing machine.

Claims

1 . A method of delivery of exogenous non-thermal plasma activated

species to a subject fluid comprising

(a) creating activated species in an energizing means; and,

(b) introducing said activated species into a subject fluid by high

speed injection means.

2. The method of Claim 1 further wherein said introducing of activated

species is in less than about 10 milliseconds.

3. The method of Claim 2 wherein said introducing is in less than about 1

millisecond.

4. The method of Claim 1 wherein at least about 50% of activated

species created in step (a) is delivered to said subject fluid.

5. The method of Claim 1 wherein at least about 10% of activated

species created is delivered in less than about 10 milliseconds to said

subject fluid.

6. The method of Claim 1 further wherein said introducing of activated

species to the subject fluid is within about 1 0 mm or less from the point

of creating said activated species.

7. The method of Claim 6 wherein said introducing of activated species

to the subject fluid is within about 2 mm or less from the point of creating

said activated species.

8. The method of Claim 1 further comprising the step of (c) engaging at least about 1 0% of said activated species in target

reactions in the subject fluid.

9. The method of Claim 1 wherein said introducing is at an operating

pressure differential above the subject fluid of from about 5 to about 50

psid.

1 0. The method of Claim 9 wherein said operating pressure differential is

at least about 1 5 psid.

1 1 . The method of Claim 1 wherein said introducing is at a temperature

of up to about 600° C.

1 2. The method of Claim 1 1 wherein said temperature is from about less

than about 100°C .

1 3. The method of Claim 1 wherein said introducing is at from about 10

to about 400 meters/second.

1 4. The method of Claim 1 3 wherein said introducing is at least about

1 00 meters/second.

1 5. The method of Claim 1 wherein said said introducing of step be is

further

(c) unidirectional introducing and absent retrograde introducing of

subject fluid into said high speed injection means.

1 6. The method of Claim 1 wherein the creating of activated species is

by subjecting a flowing gas to passage between two electrodes which, in

combination, comprise a self switching high-voltage electrode.

17. An apparatus for delivery of exogenous non-thermal plasma activated

species to a subject fluid comprising energizing means in high speed fluid

connection with the subject fluid via high speed injection means.

18. The apparatus of Claim 17 wherein said high speed injection means

is unidirectional.

1 9. The apparatus of Claim 18 wherein said unidirectionality is by check

valve, or by removal of said high speed injection means from contact with

subject fluid.

20. The apparatus of Claim 17 wherein said energizing means provides

up to about 1000 joules/liter to an exogenous fluid to be activated to said

exogenous non-thermal plasma activated species.

21 . The apparatus of Claim 17 wherein said injection means is a circular

jet aperture, or slot.

22. The apparatus of Claim 21 wherein said circular jet aperture is about

0.2 to about 5 mm in width.

23. The apparatus of Claim 22 wherein said width is about 0.2 to about

1 mm.

24. The apparatus of claim 17 wherein

the high speed injection means comprises a body, and

wherein said body comprises a high dielectric insulating tube having

a front end nearer to a reaction chamber and a rear end away from said reaction chamber, and said high speed injection means having a front

exit port in fluid connection with said reaction chamber, and

wherein within the high dielectric insulating tube is a high voltage

electrode extending toward, but not fully to, the exit port of the high

speed injection means;

a ground return shield and electrode at the front of the high

dielectric insulating tube,

and the space between the end of the high voltage electrode and

the front of the jet comprising an electric discharge volume in fluid

connection with the reaction chamber wherein said electric discharge to

reaction chamber distance is 10 mm or less.

25. The apparatus of Claim 17 wherein said high speed fluid connection

with the subject fluid via high speed injection means further comprises a

closure means.

26. The apparatus of Claim 17 further comprising an after treatment

scrubber.