Enhancing gas-phase reaction in a plasma using high intensity and high power ultrasonic acoustic waves

Abstract

This invention relates to enhancing a gas-phase reaction in a plasma comprising: creating plasma ( 104 ) by at least one plasma source ( 106 ), and wherein that the method further comprises: generating ultrasonic high intensity and high power acoustic waves ( 102 ) having a predetermined amount of acoustic energy by at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ), where said ultrasonic high intensity and high power acoustic waves are directed to propagate towards said plasma ( 104 ) so that at least a part of said predetermined amount of acoustic energy is absorbed into said plasma ( 104 ), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is at least substantially 100 W. In this way, a high sound intensity and power are obtained that efficiently enhances a gas-phase reaction in the plasma, which enhances the plasma process, e.g. enabling more efficient ozone or hydrogen generation using plasma in relation to reaction speed and/or obtained concentration of the generated compound. Other processes including plasma like exhaust gas cleaning, pollution control, odor removal, fuel conversion, sterilization, and oxidation can also be enhanced.

1 . A method of enhancing a gas-phase reaction in a plasma comprising:
 creating plasma ( 104 ) by at least one plasma source ( 106 ), and characterized in that the method further comprises:   generating ultrasonic high intensity and high power acoustic waves ( 102 ) having a predetermined amount of acoustic energy by at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ), where said ultrasonic high intensity and high power acoustic waves are directed to propagate towards said plasma ( 104 ) so that at least a part of said predetermined amount of acoustic energy is absorbed into said plasma ( 104 ), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is at least substantially 100 W.   
     
     
         2 . A method according to  claim 1 , wherein said sound pressure level of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is
 at least substantially 150 dB,   at least substantially 160 dB,   at least substantially 170 dB,   at least substantially 180 dB,   at least substantially 190 dB, or   at least substantially 200 dB.   
     
     
         3 . A method according to  claim 1 , wherein said acoustic power of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is
 at least substantially 200 W,   at least substantially 300 W,   at least substantially 400 W,   about 400 W,   greater than substantially 400 W,   at least substantially 500 W,   at least substantially 1 kW, or   selected from about 1-2 kW.   
     
     
         4 . A method according to  claim 1 , wherein said plasma source ( 106 ) comprises at least one source selected from a group of: a dielectric barrier discharge (DBD) plasma source, a surface discharge (SD) plasma source, a volume discharge (VD) plasma source, a plasma torch source, an arc plasma torch, a gliding arc plasma torch, a cold plasma torch, a pencil-like torch, a direct current plasma source, a capacitively coupled plasma source, a pulsed plasma source, a magnetron plasma source, an electron cyclotron resonance plasma source, an inductively coupled plasma source, a helicon plasma source, a helical resonator plasma source, a microwave plasma source, an atmospheric pressure plasma jet (APPJ) source, a barrier torch, an arc microwave torch, a corona discharge plasma source, a micro-plasma source, a low pressure plasma source, and a high pressure plasma source. 
     
     
         5 . A method according to  claim 1 , wherein a working gas pressure at an inlet of said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is between approximately 1.9 and approximately 5 bar. 
     
     
         6 . A method according to  claim 1 , wherein said plasma ( 104 ) is created at atmospheric pressure. 
     
     
         7 . A method according to  claim 1 , wherein said plasma source ( 106 ) comprises at least one electrode ( 103 ;  103 ′) and wherein one electrode ( 103 ′) of said at least one electrode ( 103 ;  103 ′) is a mesh type of electrode. 
     
     
         8 . A method according to  claim 1 , wherein the generated ultrasonic high intensity and high power acoustic waves are propagated towards a membrane ( 401 ) so that any gases used by the at least one ultrasonic high intensity and high power acoustic wave generator ( 101 ) is not mixed with one or more gases ( 111 ) used by said plasma source ( 106 ) to create said plasma ( 104 ). 
     
     
         9 . A method according to  claim 1 , wherein the generated ultrasonic high intensity and high power acoustic waves ( 102 ) are generated using a gaseous medium ( 121 ) and where the acoustic waves ( 102 ) are directed towards said plasma ( 104 ) and wherein said gaseous medium ( 121 ) after exit of said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is directed away from said plasma ( 104 ). 
     
     
         10 . A method according to  claim 1 , wherein a gas mixture ( 111 ) used for creating the plasma ( 104 ) is supplied to at least one electrode ( 103 ;  103 ′) of the plasma source ( 106 ) substantially in a direction that said ultrasonic acoustic waves propagate towards said plasma ( 104 ). 
     
     
         11 . A method according to any  claim 1 , wherein said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is selected from the group of:
 a Hartmann type gas-jet generator,   a Levavasseur type gas-jet generator,   a generator comprising an outer part ( 305 ) and an inner part ( 306 ) defining a passage ( 303 ), an opening ( 302 ), and a cavity ( 304 ) provided in the inner part ( 306 ), where said ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is adapted to receive a pressurized gas and pass the pressurized gas to said opening ( 302 ), from which the pressurized gas is discharged in a jet towards the cavity ( 304 ),   a generator of any of the above mentioned types, which includes any type of concentrators or reflectors of acoustic waves   
     
     
         12 . A method according to  claim 1 , wherein a food item is subjected to the plasma ( 104 ) where the creation of the plasma ( 104 ) generates chemical radicals and sterilizes the food item. 
     
     
         13 . A method according to  claim 1 , wherein said generating ultrasonic high intensity and high power acoustic waves ( 102 ) comprises:
 generating high intensity and high power acoustic waves ( 102 ) by a first acoustic wave generator ( 101 ) using a gaseous medium ( 121 ) where the gaseous medium ( 121 ), after exit from the first acoustic wave generator ( 101 ), has a first principal direction (A) that is different from a second principal direction (B) of the high intensity and high power acoustic waves ( 102 ) generated by the first acoustic wave generator ( 101 ),   generating high intensity and high power acoustic waves ( 102 ) by a second acoustic wave generator ( 101 ′),   where the first ( 101 ) and second acoustic wave generators ( 101 ′) are located in relation to each other so that at least a part of the generated high intensity acoustic waves ( 102 ), being generated by said second acoustic wave generator ( 101 ′), is directed towards at least a part of the gaseous medium ( 121 ) after exit from said first acoustic wave generator ( 101 ).   
     
     
         14 . A method according to  claim 1 , wherein said plasma ( 104 ) is used in a process selected from the group of:
 ozone generation,   hydrogen production,   exhaust gas cleaning,   pollution control,   odor removal,   fuel conversion,   sterilization, and   oxidation.   
     
     
         15 . A system for enhancing a gas-phase reaction in a plasma comprising:
 at least one plasma source ( 106 ) adapted to create plasma ( 104 ), characterized in that the system further comprises:   at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) adapted to generate ultrasonic high intensity and high power acoustic waves ( 102 ) having a predetermined amount of acoustic energy and being directed to propagate towards said plasma ( 104 ) so that at least a part of said predetermined amount of acoustic energy is absorbed into said plasma ( 104 ), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is at least 100 W.   
     
     
         16 . A system according to  claim 15 , wherein the sound pressure level of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is
 at least substantially 150 dB,   at least substantially 160 dB,   at least substantially 170 dB,   at least substantially 180 dB,   at least substantially 190 dB, or   at least substantially 200 dB.   
     
     
         17 . A system according to  claim 15 , wherein said acoustic power of said generated ultrasonic high intensity and high power acoustic waves ( 102 ) is
 at least substantially 200 W,   at least substantially 300 W,   at least substantially 400 W,   about 400 W,   greater than substantially 400 W,   at least substantially 500 W,   at least substantially 1 kW, or   selected from about 1-2 kW.   
     
     
         18 . A system according to  claim 15 , wherein said plasma source ( 106 ) comprises at least one source selected from a group of: a dielectric barrier discharge (DBD) plasma source, a surface discharge (SD) plasma source, a volume discharge (VD) plasma source, a plasma torch source, an arc plasma torch, a gliding arc plasma torch, a cold plasma torch, a pencil-like torch, a direct current plasma source, a capacitively coupled plasma source, a pulsed plasma source, a magnetron plasma source, an electron cyclotron resonance plasma source, an inductively coupled plasma source, a helicon plasma source, a helical resonator plasma source, a microwave plasma source, an atmospheric pressure plasma jet (APPJ) source, a barrier torch, an arc microwave torch, a corona discharge plasma source, a micro-plasma source, a low pressure plasma source, and a high pressure plasma source. 
     
     
         19 . A system according to  claim 15 , wherein a working gas pressure at an inlet of said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is between approximately 1.9 and approximately 5 bar. 
     
     
         20 . A system according to  claim 15 , wherein said plasma ( 104 ) is created at atmospheric pressure. 
     
     
         21 . A system according to  claim 15 , wherein said plasma source ( 106 ) comprises at least one electrode ( 103 ;  103 ′) and wherein one electrode ( 103 ′) of said at least one electrode ( 103 ;  103 ′) is a mesh type of electrode. 
     
     
         22 . A system according to  claim 15 , wherein said system further comprises a membrane ( 401 ) and where the system is adapted to propagate the generated ultrasonic high intensity and high power acoustic waves towards the membrane ( 401 ) so that any gases used by the at least one ultrasonic high intensity and high power acoustic wave generator ( 101 ) is not mixed with one or more gases ( 111 ) used by said plasma source ( 106 ) to create said plasma ( 104 ). 
     
     
         23 . A system according to  claim 15 , wherein the generated ultrasonic high intensity and high power acoustic waves ( 102 ) are generated using a gaseous medium ( 121 ) and where the acoustic waves ( 102 ) are directed towards said plasma ( 104 ) and wherein said gaseous medium ( 121 ) after exit of said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is directed away from said plasma ( 104 ). 
     
     
         24 . A system according to  claim 15 , said plasma source ( 106 ) comprises at lease one electrode ( 103 ;  103 ′) and wherein a gas mixture ( 111 ) used for creating the plasma ( 104 ) is supplied to the at least one electrode ( 103 ;  103 ′) substantially in a direction that said ultrasonic acoustic waves propagates towards said plasma ( 104 ). 
     
     
         25 . A system according to  claim 15 , wherein said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is selected from the group of:
 a Hartmann type gas-jet generator,   a Levavasseur type gas-jet generator,   a generator comprising an outer part ( 305 ) and an inner part ( 306 ) defining a passage ( 303 ), an opening ( 302 ), and a cavity ( 304 ) provided in the inner part ( 306 ), where said ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) is adapted to receive a pressurized gas and pass the pressurized gas to said opening ( 302 ), from which the pressurized gas is discharged in a jet towards the cavity ( 304 ),   a generator of any of the above mentioned types, which includes any type of concentrators or reflectors of acoustic waves.   
     
     
         26 . A system according to  claim 15 , wherein a food item is subjected to the plasma ( 104 ) where the creation of the plasma ( 104 ) generates chemical radicals and sterilizes the food item. 
     
     
         27 . A system according to  claim 15 , wherein said at least one ultrasonic high intensity and high power gas-jet acoustic wave generator ( 101 ) comprises
 a first acoustic wave generator ( 101 ) for generating high intensity acoustic waves ( 102 ) using a gaseous medium ( 101 ) where the gaseous medium ( 101 ) after exit from said first acoustic wave generator ( 101 ) has a first principal direction (A) that is different from a second principal direction (B) of generated high intensity acoustic waves ( 102 ) being generated by said first acoustic wave generator ( 101 ), and   at least a second acoustic wave generator ( 101 ′) for generating high intensity acoustic waves ( 102 ),   
       where said first ( 101 ) and second acoustic wave generators ( 101 ′) are located in relation to each other so that at least a part of the generated high intensity acoustic waves ( 102 ), being generated by one of said first ( 101 ) and second ( 101 ′) acoustic wave generator, is directed towards at least a part of the gaseous medium ( 101 ) after exit from the other of said first ( 101 ) and said second ( 101 ′) acoustic wave generator. 
     
     
         28 . A system according to  claim 14 , wherein said plasma ( 104 ) is used in a process selected from the group of:
 ozone generation,   hydrogen production,   exhaust gas cleaning,   pollution control,   odor removal,   fuel conversion,   sterilization, and   oxidation.