Abstract:
A device for processing gases includes a cylindrical housing in which an electrically grounded, metal injection/extraction gas supply tube is disposed. A dielectric tube surrounds the injection/extraction gas supply tube to establish a gas modification passage therearound. Additionally, a metal high voltage electrode circumscribes the dielectric tube. The high voltage electrode is energizable to create nonthermal electrical microdischarges between the high voltage electrode and the injection/extraction gas supply tube across the dielectric tube within the gas modification passage. An injection/extraction gas and a process gas flow through the nonthermal electrical microdischarges within the gas modification passage and a modified process gas results. Using the device contaminants that are entrained in the process gas can be destroyed to yield a cleaner, modified process gas. Also, a modified process gas or gas/vapor mixture can be generated and can be combusted more efficiently and with the emission of less pollution.

Description:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0001] This invention was made with Government support under Contract No. W-7405-ENG-36, awarded by the Department of Energy. The Government has certain rights in this invention. 
     
    
     
       CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0002]    Not Applicable  
         INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC  
         [0003]    Not Applicable  
         BACKGROUND OF THE INVENTION  
         [0004]    1. Field of the Invention  
           [0005]    This invention pertains generally to devices for processing contaminated/polluted gases or gases to be used as feedstocks for chemical synthesis/modification, and more particularly to non-thermal plasma reactors.  
           [0006]    2. Description of Related Art  
           [0007]    The emission and discharge of volatile organic compounds (VOCs) are strictly regulated by the U.S. Conservation and Recovery Act (RCRA), the National Pollutant Discharge Elimination System (NPDES), and the National Emissions Standards for Hazardous Air Pollution regulations (NESHAPS). Technical and regulatory difficulties associated with current VOC and HAP treatment methods such as air-stripping (dilution), activated-carbon absorption, incineration, and thermal-catalytic treatment have prompted the search for alternatives. The drawbacks of present methods result in ineffective treatment, the generation of large secondary waste streams, and increased costs. It is also recognized that, for example, to operate fossil-fueled motor vehicles and other combustion-related engines or machinery under higher efficiency and reduced pollution output conditions in the future, it is desirable to have clean-burning, energy-efficient, hydrocarbon liquid fuels. This invention can also be used to synthesize such fuels from gaseous feedstocks.  
           [0008]    The present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.  
         BRIEF SUMMARY OF THE INVENTION  
         [0009]    This invention overcomes many of these drawbacks and enables the end user to effectively treat VOCs and HAPs while meeting regulations in a timely and economical fashion. In addition to VOCs/HAPs, this invention shows promise for treating other air pollutants and hazardous/toxic chemicals in gases (e.g., acid rain precursors NOx and SOx, odor causing chemicals, chemical/biological warfare agents, and industrial emissions). Additionally, higher-order hydrocarbons (e.g., for motor vehicle fuels) can be synthesized using a nonthermal plasma (NTP) device according to the present invention.  
           [0010]    By way of example, and not of limitation, the present invention is a device that employs electrical discharges/nonthermal plasmas in a gaseous medium to destroy air pollutants or undesirable chemicals/chemical or biological agents; process chemicals, or synthesize chemical compounds. In nonthermal plasmas, the electrons are “hot”, while the ions and neutral species are “cold” which results in little waste enthalpy being deposited in a process gas stream. This is in contrast to thermal plasmas, where the electron, ion, and neutral-species energies are in thermal equilibrium (or “hot”) and considerable waste heat is deposited in the process gas. The present invention utilizes a method for injecting additive gases/chemical compounds into the process gas stream to increase the efficiency and/or selectivity of the plasma processing. In prior-art dielectric-barrier (DB) reactors, an additive, e.g., an injection/extraction gas, has not been applied. Doing so allows for a greater variety of active species to be produced with associated increases in effective active species yields. Also, some chemical injectants (e.g., those with low photoionization cross sections) can be used to “seed” the discharge so a more homogeneous bulk-volume plasma results. This can provide advantages in terms of spreading the active species over the plasma reactor volume and, thereby, decreasing deleterious active species consumption mechanisms (e.g., radical-radical recombination).  
           [0011]    In the present invention, the NTP reactor is applied to gas streams containing hazardous/toxic, or other undesirable pollutants or contaminants and to gas streams that are to be processed (i.e., changed in chemical form or transformed into other useful products).  
           [0012]    In one aspect of the present invention, a device for processing contaminated gases includes a high voltage electrode and a ground electrode that is slightly spaced from the high voltage electrode. A dielectric layer is disposed in close contact with the high voltage electrode between the high voltage electrode and the ground electrode. Moreover, a gas modification passage is established within the housing between the dielectric layer and the ground electrode. A process gas supply provides a process gas to the gas modification passage and an injection/extraction gas supply provides an injection/extraction gas to the gas modification passage. The high voltage electrode is energizable to create nonthermal electrical microdischarges between the high voltage electrode and the ground electrode, distributed over the dielectric layer area within the gas modification passage. As the process gas and the injection/extraction gas flow through the gas modification passage, the process gas is modified to yield a modified process gas in which entrained pollutants have been destroyed. Or, the process gas can be modified to yield a fuel that can be more easily and efficiently combusted with less resultant pollution.  
           [0013]    In another aspect of the present invention, a device for processing gases includes a gas modification passage that defines a length. The device further includes a means for supplying a process gas to the gas modification passage and a means for supplying an injection/extraction gas to the gas modification passage. Further, the device includes means for creating non-thermal electrical microdischarges along the length of the gas modification passage.  
           [0014]    In yet another aspect of the present invention, a device for processing gases includes a cylindrical housing. A metal injection/extraction gas supply tube is disposed within the housing and is electrically grounded. A first dielectric tube surrounds the injection/extraction gas supply tube. Moreover, a gas modification passage is established between the injection/extraction gas supply tube and the first dielectric tube. In this aspect, a metal high voltage electrode circumscribes the first dielectric tube. The high voltage electrode is energizable to create nonthermal electrical microdischarges between the high voltage electrode and the injection/extraction gas supply tube along the length of the gas modification passage.  
           [0015]    In still another aspect of the present invention, a device for processing gases includes a rectangular box-shaped housing. A metal, rectangular, plate-shaped injection/extraction gas manifold is disposed within the housing. The injection/extraction gas manifold is formed with injection/extraction gas passages and is electrically grounded. Further, a rectangular, dielectric plate is installed in the housing such that it is slightly spaced from the injection/extraction gas manifold. A gas modification passage is established between the ground electrode and the dielectric layer. This aspect of the present invention further includes a metal, rectangular, plate-shaped high voltage electrode that is adjacent to the dielectric layer. The high voltage electrode is energizable to create nonthermal electrical microdischarges between the high voltage electrode and the injection/extraction gas manifold along the length of the gas modification passage.  
           [0016]    In yet still another aspect of the present invention, a device for processing gases includes a rectangular box-shaped housing. A metal, rectangular, plate-shaped high voltage electrode is installed within the housing. Moreover, a rectangular, first dielectric plate is installed within the housing adjacent to the high voltage electrode. Further, the device includes a rectangular, second dielectric plate that is slightly spaced from the first dielectric plate. A metal, rectangular, plate-shaped ground electrode is adjacent to the second dielectric plate. In this aspect, a gas modification passage is established between the first dielectric plate and the second dielectric plate. Additionally, an injection/extraction gas manifold flanks the first dielectric plate and the second dielectric plate. The injection/extraction gas manifold is formed with an injection/extraction gas passage that is in fluid communication with the gas modification passage. Also, the high voltage electrode is energizable to create nonthermal electrical microdischarges between the high voltage electrode and the ground electrode along the length of the gas modification passage.  
           [0017]    In still another aspect of the present invention, a method for processing gases includes establishing a gas modification passage. Nonthermal electrical microdischarges are created along the length of the gas modification passage. A process gas is provided to the gas modification passage such that the process gas flows through the nonthermal electrical microdischarge. Also, an injection/extraction gas is provided to the gas modification passage such that the injection/extraction gas flows through the nonthermal electrical microdischarges with the process gas.  
           [0018]    An object of the invention is to provide a relatively high degree of contaminant removal.  
           [0019]    Another object of the invention is to decrease contaminant-removal costs.  
           [0020]    Another object of the invention is to provide more efficient and/or selective chemical processing/synthesis.  
           [0021]    Another object of the invention is to provide nonthermal treatment of contaminated gases.  
           [0022]    Another object of the invention is to provide simultaneous destruction and removal of multiple pollutants.  
           [0023]    Another object of the invention is to eliminate the need for fuels or catalysts.  
           [0024]    Another object of the invention is the potential for self catalysis in the gas phase due to chain-reaction propagators resulting from the additive gas.  
           [0025]    Another object of the invention is to provide a broad dynamic range for treating both rich and lean streams.  
           [0026]    Another object of the invention is the ability to construct in both cylindrical and rectangular geometries.  
           [0027]    Further aspects of the invention will be brought out in the following portions of the specification, wherein the detailed description is for the purpose of fully disclosing preferred embodiments of the invention without placing limitations thereon. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)  
       [0028]    The invention will be more fully understood by reference to the following drawings which are for illustrative purposes only:  
         [0029]    [0029]FIG. 1 is a side plan view of a first embodiment of a silent discharge plasma/dielectric barrier discharge (SDP/DBD) reactor.  
         [0030]    [0030]FIG. 2 is a cross-section view of the first embodiment of the SDP/DBD reactor taken along line  2 - 2  in FIG. 1.  
         [0031]    [0031]FIG. 3 is a cross-section view of a second embodiment of the SDP/DBD reactor.  
         [0032]    [0032]FIG. 4 is a side plan view of a third embodiment of a SDP/DBD reactor.  
         [0033]    [0033]FIG. 5 is a cross-section view of the third embodiment of the SDP/DBD reactor taken along line  5 - 5  in FIG. 4.  
         [0034]    [0034]FIG. 6 is a perspective view of an injection/extraction gas manifold/ground electrode.  
         [0035]    [0035]FIG. 7 is a side plan view of a fourth embodiment of a SDP/DBD reactor.  
         [0036]    [0036]FIG. 8 is a cross-section view of the fourth embodiment of the SDP/DBD reactor taken along line  8 - 8  in FIG. 7.  
         [0037]    [0037]FIG. 9 is a cross-section view of the fourth embodiment of the SDP/DBD reactor taken along line  9 - 9  in FIG. 7.  
         [0038]    [0038]FIG. 10 is a block diagram of a non-limiting, exemplary combustion system. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0039]    Referring more specifically to the drawings, for illustrative purposes the present invention is embodied in the apparatus generally shown in FIG. 1 through FIG. 10. It will be appreciated that each apparatus may vary as to configuration and as to details of the parts, and that the method may vary as to the specific steps and sequence, without departing from the basic concepts as disclosed herein.  
         [0040]    [0040]FIGS. 1 and 2 show a first embodiment of a silent discharge plasma/dielectric-barrier discharge (SDP/DBD) reactor according to the present invention, generally designated  10 . As shown in FIGS. 1 and 2, the reactor  10  includes a generally cylindrical housing  12  disposed between a generally disk-shaped inlet end cap  14  and a generally disk-shaped outlet end cap  16 . FIGS. 1 and 2 show that the end caps  14 ,  16  can be removably engaged with the housing  10  using plural nuts  18  and plural bolts  20 , but it can be appreciated that any other fastening means well known in the art can be used.  
         [0041]    [0041]FIG. 2 shows that the reactor  10  includes a metal, generally cylindrical high-voltage (HV) electrode  22  that is disposed within the housing  12  between the end caps  14 ,  16 . In a preferred embodiment, the HV electrode  22  is connected to an alternating current (AC) source or a pulsed direct current (DC) source. Moreover, a generally cylindrical, dielectric tube  24  is disposed within the HV electrode  22  such that the HV electrode  22  closely surrounds the dielectric tube  24 . Preferably, the dielectric tube  24  is made from a dielectric material, e.g., glass, ceramic, etc.  
         [0042]    As shown in FIG. 2, a metal, generally cylindrical injection/extraction gas supply tube  26  is disposed within the dielectric tube  24 . The injection/extraction gas supply tube  26  is electrically grounded and can be considered a ground electrode. It is to be understood that the HV electrode  22  and the tubes  24 ,  26  are concentric to each other and are centered on a central axis  28  established by the reactor  10 . Moreover, it is to be understood that the dielectric tube  24  establishes a dielectric barrier or layer between the HV electrode  22  and the grounded injection/extraction gas supply tube  26 .  
         [0043]    [0043]FIG. 2 shows that a gas modification passage  30  is established between the injection/extraction gas supply tube  26  and the dielectric tube  24 . Also, an injection/extraction gas passage  32  is established within the injection/extraction gas supply tube  26 . Plural injection/extraction gas holes  34  are established laterally within the injection/extraction gas supply tube  26  and connect the injection/extraction gas passage  32  to the gas modification passage  30 .  
         [0044]    As shown in FIG. 2, one end of the injection/extraction gas supply tube  26  establishes an injection/extraction gas inlet  36 . A plug  38  is disposed within the other end of the injection/extraction gas supply tube  26 . FIG. 2 further shows that the reactor  10  also includes a process gas inlet  40  established by the inlet end cap  14 . The process gas inlet  40  leads to the gas modification passage  30 . Also, a modified process gas outlet  42  is established by the outlet end cap  16  and leads from the gas modification passage  30 .  
         [0045]    It is to be understood that when the HV electrode  22  is energized, nonthermal electrical microdischarges occur between the HV electrode  22  and the grounded injection/extraction gas supply tube  26  across the dielectric barrier established by the dielectric tube  24 . The nonthermal electrical microdischarges occur within the gas modification passage  30  and the width of the gas modification passage  30  defines a discharge gap  44 . Preferably, the discharge gap  44  is between one and several millimeters (e.g., 1-10 mm).  
         [0046]    It is to be understood that an injection/extraction gas is supplied to the injection/extraction gas inlet  36  and flows through the injection/extraction gas passage  32 , through the injection/extraction gas holes  34 , and into the gas modification passage  30 . A process gas is supplied to the process gas inlet  40  and flows through the gas modification passage  30 . It is to be understood that the process gas can be ambient air, a noble gas, natural gas, a gas mixture, etc.  
         [0047]    When the HV electrode  22  is energized, nonthermal electrical microdischarges occur between the dielectric tube  24  and the grounded injection/extraction gas supply tube  26 . As the process gas flows through the gas modification passage  30  and the injection/extraction gas flows through the injection/extraction gas passage  32 , the SDP/DBD reactor  10  can be used to generate highly reactive chemical species, such as free radicals. These reactive species, e.g., O-atoms, OH-radicals, N-radicals, excited N 2  and O 2  molecules, HO 2 -radicals, NH-radicals, CH-radicals, etc., readily decompose organic chemicals (e.g., VOCs), oxides of sulfur and nitrogen (SO 2  and NOx), and odor agents (e.g., aldehydes, H 2 S and many others) by breaking their chemical bonds. The result is the production of nonhazardous or easily-managed products. The free radicals and other active species, described above, can also play a key role in chemical synthesis, producing desirable products, e.g., creating higher-order hydrocarbon fuels from methane/natural gas. Moreover, nonthermal plasmas can be created by several types of electric discharge configurations.  
         [0048]    In this exemplary, non-limiting embodiment of the invention, the reactor  10  utilizes a dielectric-barrier discharge arrangement, i.e., the HV electrode  22 , the dielectric tube  24 , and the grounded injection/extraction gas supply tube  26 . The two conducting electrodes, i.e., the HV electrode  22  and the grounded injection/extraction gas supply tube  26 , are separated by a relatively thin gas-containing space, i.e., the gas modification passage  30 . The HV electrode  22  is covered by a dielectric material, i.e., the dielectric tube  24 . As described in detail below, it can be appreciated that the grounded injection/extraction gas supply tube  26  can also be covered by a dielectric layer.  
         [0049]    A high-voltage signal, e.g., alternating current with a frequency in a range of ten Hertz to twenty kiloHertz (10 Hz-20 kHz) is applied to the HV electrode  22  and the grounded injection/extraction gas supply tube  26  (which also serves as an electrode) thereby creating electrical-discharge streamers (microdischarges) in the gas modification passage  30 . It is to be understood that the discharges are the source of the active nonthermal plasma.  
         [0050]    It can be appreciated that the reactor  10  of the present invention can reduce hazardous compound concentrations in off-gases to very low levels by free-radical “cold combustion.” Or, the reactor  10  can synthesize desirable chemical products using gaseous feedstocks. Because this invention provides for the injection of additive chemical compounds, e.g., ammonia, hydrocarbons, etc., into the gas modification passage  30 , additional reactive species can be created.  
         [0051]    [0051]FIG. 3 shows a second embodiment of a SDP/DBD reactor according to the present invention, generally designated  50 . As shown in FIG. 3, the reactor  50  is similar in every aspect to the reactor shown in FIGS. 1 and 2 except for the addition of a second dielectric tube  52  that circumscribes an injection/extraction gas supply tube  26 . Accordingly, as intended by this embodiment of the present invention, a gas modification passage  54  is established between the first dielectric tube  24  and the second dielectric tube  52 . Moreover, nonthermal electrical microdischarges can occur between the HV electrode  22  and the injection/extraction gas supply tube  26  across both dielectric tubes  24 ,  52 .  
         [0052]    [0052]FIGS. 4 and 5 show a third embodiment of a SDP/DBD reactor according to the present invention, generally designated  100 . As shown in FIGS. 4 and 5, the reactor  100  includes a generally rectangular housing  102  disposed between a generally flat, rectangular, plate-shaped inlet end cap  104  and a generally flat, rectangular, plate-shaped outlet end cap  106 . FIGS. 4 and 5 show that the end caps  104 ,  106  can be removably engaged with the housing  100  using plural nuts  108  and plural bolts  110 , but it can be appreciated that any other fastening means well known in the art can be used.  
         [0053]    [0053]FIG. 5 shows that the reactor  100  includes a metal, generally flat, rectangular, plate-shaped high-voltage (HV) electrode  112  that is disposed within the housing  102  between the end caps  104 ,  106 . Preferably, the HV electrode  112  is connected to an alternating current (AC) source or a pulsed direct current (DC) source. Moreover, a generally flat, rectangular dielectric plate  114  is disposed within the reactor  100  adjacent to the HV electrode  112 . Preferably, the dielectric plate  114  is made from a material such as glass, ceramic, etc. As shown in FIG. 5, a metal, generally flat, rectangular injection/extraction gas manifold  116  is disposed within the reactor  100  such that it is slightly spaced from the dielectric plate  114 . It is to be understood that the injection/extraction gas manifold  116  is electrically grounded and can be formed with one or more injection/extraction gas passages  118 —each passage  118  can further have plural injection/extraction gas holes  120  leading therefrom (see, e.g., FIG. 6).  
         [0054]    As shown in FIG. 5, a gas modification passage  122  is established between the injection/extraction gas manifold  116  and the dielectric plate  114 . The injection/extraction gas holes  120  provide fluid communication between the injection/extraction gas passages  118  and the gas modification passage  122 . FIG. 5 further shows that the inlet end cap  104  is formed with a process gas inlet  124  that leads to the gas modification passage  122  and an injection/extraction gas inlet  126  that leads to the injection/extraction gas passages  118 . Also, a modified process gas outlet  128  is established by the outlet end cap  106  and leads from the gas modification passage  122 .  
         [0055]    It is to be understood that when the HV electrode  112  is energized, nonthermal electrical microdischarges occur between the dielectric plate  114  and the grounded injection/extraction gas manifold  116 . The nonthermal electrical microdischarges occur within the gas modification passage  122  and the width of the gas modification passage  122  defines a discharge gap  130 . Preferably, the discharge gap  130  is between one and several millimeters (e.g., 1-10 mm). It can be appreciated that as a process gas and an injection/extraction gas flow through the gas modification passage  122 , the process gas is modified by the nonthermal electrical microdischarges within the gas modification passage  122 , as described in detail above.  
         [0056]    Referring now to FIGS. 7, 8, and  9 , a fourth embodiment of a SDP/DBD reactor according to the present invention is shown and is generally designated  200 . As shown in FIGS. 7, 8, and  9 , the reactor  200  includes a generally rectangular housing  202  disposed between a generally flat, rectangular, plate-shaped inlet end cap  204  and a generally flat, rectangular, plate-shaped outlet end cap  206 . FIGS. 7, 8, and  9  show that the end caps  204 ,  206  can be removably engaged with the housing  200  using plural nuts  208  and plural bolts  210 , but it can be appreciated that any other fastening means well known in the art can be used.  
         [0057]    [0057]FIG. 8 shows that the reactor  200  includes a metal, generally flat, rectangular, plate-shaped high-voltage (HV) electrode  212  disposed within the housing  202  between the end caps  204 ,  206 . Also, a metal, generally flat, rectangular, plate-shaped ground electrode  214  is disposed within the housing  202  and is slightly spaced from the HV electrode  212 . Preferably, the HV electrode  212  is connected to an alternating current (AC) source or a pulsed direct current (DC) source and the ground electrode  214  is electrically grounded.  
         [0058]    As shown, a generally flat, rectangular first dielectric plate  216  is disposed within the reactor  200  immediately adjacent to the HV electrode  212  between the HV electrode  212  and the ground electrode  214 . Moreover, a generally flat, rectangular second dielectric plate  218  is disposed within the reactor  200  immediately adjacent to the ground electrode  214  between the HV electrode  212  and the ground electrode  214 . Preferably, the dielectric plates  216 ,  218  are made from a material such as glass, ceramic, etc.  
         [0059]    As shown in FIG. 9, a generally “C” shaped first injection/extraction gas manifold  220  is disposed within the reactor  200  such that it partially surrounds the dielectric plates  216 ,  218 . A generally “C” shaped second injection/extraction gas manifold  222  is disposed within the reactor  200  opposite the first injection/extraction gas manifold  220  such that the second injection/extraction gas manifold  222  partially surrounds the dielectric plates  216 ,  218  opposite the first injection/extraction gas manifold  220 . FIGS. 8 and 9 show that each injection/extraction gas manifold  222  is formed with an injection/extraction passage  224  having plural injection/extraction gas holes  226  leading therefrom. The plural injection/extraction gas holes  226  lead to a gas modification passage  228  that is established between the dielectric plates  216 ,  218 .  
         [0060]    [0060]FIG. 8 further shows that the inlet end cap  204  is formed with a process gas inlet  230  that leads to the gas modification passage  228 . Also, a modified process gas outlet  232  is established by the outlet end cap  206  and leads from the gas modification passage  228 . It is to be understood that when the HV electrode  212  is energized, nonthermal electrical microdischarges occur between the HV electrode  212  and the ground electrode  214  across the dielectric plates  216 ,  218 . These nonthermal electrical microdischarges occur within the gas modification passage  228  and the width of the gas modification passage  228  defines a discharge gap  234 . Preferably, the discharge gap  234  is between one and several millimeters (e.g., 1-10 mm). It can be appreciated that as a process gas and an injection/extraction gas flow through the gas modification passage  228 , the process gas is modified by the nonthermal electrical microdischarges within the gas modification passage  228 , as described in detail above.  
         [0061]    Referring now to FIG. 10, a non-limiting, exemplary gas-processing system is shown and is generally designated  300 . FIG. 10 shows that the system  300  includes an SDP/DBD reactor, e.g., the reactor  10  shown in FIGS. 1 and 2 and described in detail above. A process gas supply  302  is connected to the SDP/DBD reactor  10  via a process gas fluid line  304 . A process gas flow meter  306  is installed along the process gas fluid line  304  to monitor the flow of process gas to the SDP/DBD reactor  10 . Also, an injection/extraction gas supply  308  is connected to the SDP/DBD reactor  10  via an injection/extraction gas fluid line  310 . An injection/extraction gas flow meter  312  is installed along the injection/extraction gas fluid line  310  to monitor the flow of injection/extraction gas to the reactor  10 . It can be appreciated that the process gas supply  302  is connected to the process gas inlet  40  (FIG. 2) and the injection/extraction gas supply  308  is connected to the injection/extraction gas inlet  36  (FIG. 2).  
         [0062]    As further shown in FIG. 10, a power supply  314 , e.g., an AC power supply, is connected to the SDP/DBD reactor  10  via a high voltage (HV) transformer  316 . Moreover, an oscilloscope  318  is also connected to the SDP/DBD reactor  10  and can be used to monitor the current and voltage of the signal that is applied to the SDP/DBD reactor  10  in order to create the nonthermal electrical microdischarges that are necessary to modify the process gas flowing through the reactor  10 . FIG. 10 also shows that the SDP/DBD reactor  10  can be connected to an outlet manifold  320  by a modified gas fluid line  322  that provides modified gas to the manifold  320 .  
         [0063]    Accordingly, it can be seen that this invention provides a means for effectively destroying air pollutants or undesirable chemicals or biological agents in a process gas, e.g., a polluted or contaminated gas. This invention can also effectively synthesize chemical compounds by adding useful chemical ions to a process gas.  
         [0064]    A greater variety of active species, including various free radicals, can be achieved and accompanied by greater effective active species yields (number per unit energy). Moreover, certain chemical additives can create more homogeneous dielectric barrier discharges. With a more homogeneous discharge, the active species/radicals are spread over a larger volume and have lower peak concentrations, so there is less competition from radical-radical interactions which tend to reduce the concentrations of active species. Therefore, more active species survive to react with entrained pollutants or feed gas species.  
         [0065]    It can be understood that various “active” and “inactive” regions can be established within the reactor using segmented electrodes (some of which can be injectors with variable injection/extraction gas hole sizes). The results include variable pump power, i.e., specific energy deposition, over different reactor spatial regions which further results in better control over the plasma chemistry because some chemical reactions are favored in “inactive” regions or vice-versa. It is also to be understood that the device can be used over a wide range of process gas pressures, e.g., a millitorr to a few atmospheres.  
         [0066]    Although the description above contains many details, these should not be construed as limiting the scope of the invention but as merely providing illustrations of some of the presently preferred embodiments of this invention. Therefore, it will be appreciated that the scope of the present invention fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the present invention is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” All structural, chemical, and functional equivalents to the elements of the above-described preferred embodiment that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the present claims. Moreover, it is not necessary for a device or method to address each and every problem sought to be solved by the present invention, for it to be encompassed by the present claims. Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112, sixth paragraph, unless the element is expressly recited using the phrase “means for.”