Apparatus and Method for Generating Nitric Oxide in Controlled and Accurate Amounts

Abstract

A nitric oxide generator generates nitric oxide from a mixture of nitrogen and oxygen such as air treated by a pulsating electrical discharge. The desired concentration of nitric oxide is obtained by controlling at least one of a frequency of the pulsating electrical discharge and duration of each electrical discharge pulse.

We claim: 
     
         1 . An apparatus for generating nitric oxide comprising:
 a reaction chamber enclosing two electrodes separated by a gap,   a gas inlet port for introducing a gas mixture containing oxygen and nitrogen into said reaction chamber,   an electronic control circuit for delivering a pulsed DC electric discharge between the two said electrodes to generate nitric oxide;   a magnetic field generator proximate to said gap between the electrodes; and   a gas outlet port for delivering the gas mixture from said reaction chamber.   
     
     
         2 . The apparatus of  claim 1  wherein the magnetic field generator is a permanent magnet. 
     
     
         3 . The apparatus of  claim 1  wherein the magnetic field generator is two permanent magnets, one on each side of the gap. 
     
     
         4 . The apparatus of  claim 1  wherein the magnetic field generator is an electric coil, which is energized by an electric current to provide the magnetic field. 
     
     
         5 . The apparatus of  claim 1  wherein the magnetic field generator is four permanent magnets, two on each side of the gap. 
     
     
         6 . The apparatus of  claim 1  wherein the electronic control circuit is configured to control a pulse frequency of the pulsed DC electric discharge and to control a pulse duration of the pulsed DC electric discharge independent of the pulse frequency to produce a desired concentration of nitric oxide. 
     
     
         7 . The apparatus of  claim 6  wherein the electronic control circuit is configured to provide a substantially constant current during the electrical discharge. 
     
     
         8 . The apparatus of  claim 1  further including a user input control communicating with the electronic control circuit configured to set a desired concentration of nitric oxide by a user. 
     
     
         9 . The apparatus of  claim 1  further including a flow device communicating with the electronic control circuit to provide a known gas flow through the reaction chamber. 
     
     
         10 . The apparatus of  claim 9  wherein the flow device is selected from the group consisting of: a flow sensor measuring gas flow from an external regulated source to produce the known gas flow, a pump system operating to produce the known gas flow without flow sensing, and a pump system with a flow sensor system providing feedback control of the pump system to produce the known gas flow. 
     
     
         11 . The apparatus of  claim 9  wherein the electronic control circuit is configured to determine and control the pulse frequency and pulse duration of the pulsed DC electric discharge according to a nitric oxide concentration setting and a known gas flow provided by the flow device to produce a desired nitric oxide concentration. 
     
     
         12 . The apparatus of  claim 1  further including a nitrogen dioxide filter attached to the gas outlet port for receiving the gas flow therefrom and removing nitrogen dioxide. 
     
     
         13 . The apparatus of  claim 1  where the electronic control circuit is configured to control at least one of the pulse frequency of the pulsed DC electric discharge to within a range of 0.1 and 100 Hz, the pulse duration of the pulsed DC electric discharge within a range of 20 microseconds and 500 milliseconds and an average current during the electrical discharge within a range of 20 to 3000 milliamps. 
     
     
         14 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 0 and 45 Hz, and the pulse duration of the electric discharge within a range of 0 milliseconds and 5 milliseconds. 
     
     
         15 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0 milliseconds and 4 milliseconds. 
     
     
         16 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0 milliseconds and 2 milliseconds. 
     
     
         17 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0 milliseconds and 1 millisecond. 
     
     
         18 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0 milliseconds and 0.5 milliseconds. 
     
     
         19 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0 milliseconds and 0.2 milliseconds. 
     
     
         20 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.2 milliseconds and 4 milliseconds. 
     
     
         21 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.2 milliseconds and 2 milliseconds. 
     
     
         22 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.2 milliseconds and 1 millisecond. 
     
     
         23 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.2 milliseconds and 0.5 milliseconds. 
     
     
         24 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.5 milliseconds and 4 milliseconds. 
     
     
         25 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.5 milliseconds and 2 milliseconds. 
     
     
         26 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.5 milliseconds and 1 millisecond. 
     
     
         27 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 1 millisecond and 4 milliseconds. 
     
     
         28 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 1 millisecond and 2 milliseconds. 
     
     
         29 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 40 Hz, and the pulse duration of the electric discharge within a range of 2 milliseconds and 4 milliseconds. 
     
     
         30 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 1 and 5 Hz, and the pulse duration of the electric discharge within a range of 0.5 milliseconds and 4 milliseconds. 
     
     
         31 . The apparatus of  claim 13  where the electronic control circuit is configured to control at least one of the pulse frequency of the electric discharge to within a range of 5 and 40 Hz, and the pulse duration of the electric discharge within a range of 0.2 milliseconds and 4 milliseconds. 
     
     
         32 . The apparatus of  claim 1  where the electronic control circuit includes a capacitor discharge circuit supplying a transient current to a transformer to supply an initial voltage across the electrodes sufficient to cause an electrical breakdown across said electrode gap and a pulse duration control circuit with a transistor to control the pulse duration of the electric discharge and wherein the electronic control circuit includes an interface circuit between said transformer and said transistor which includes a high voltage diode to protect the transistor from high voltage from said transformer and wherein said pulse duration control circuit controls the transistor in a pulse width modulation mode to control an average current during pulse duration phase of the electric discharge and wherein the electronic control circuit includes an inductor to smooth a pulse width modulated current from said transistor prior to the electrode. 
     
     
         33 . The apparatus of  claim 1  further including a discharge sensor for sensing the pulse duration. 
     
     
         34 . The apparatus of  claim 1  further including a lookup table providing a desired concentration of nitric oxide as a function of both pulse frequency and pulse duration.