Abstract:
A method and apparatus for producing hydrogen and oxygen gas includes a tank for capturing the gas and holding anodes and cathodes submersed in water. An electrical supply is attached to the anodes and cathodes, providing direct current modulated at a duty cycle that is varied depending on the measured pressure of the produced gas.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to the field of generating a hydrogen and oxygen gasses using electricity and more particularly to an apparatus and method that produces the gasses in an efficient manner while permitting continuous control of gas production.  
         [0003]     2. Description of the Related Art  
         [0004]     Using electricity to decompose water into hydrogen and oxygen gas was discovered by William Nicholson in 1800. The process uses two electrodes, a cathode and an anode, immersed in water (not pure water). The electrodes are coupled to a direct current power source, the cathode to the negative power source and the anode to the positive power source. As current passes through the water, hydrogen is produced around the cathode and oxygen around the anode. The gasses may be left separate or allowed to mix, the mixed gasses often known as “Brown&#39;s gas,” hereby referred to as “brown gas.” Burning the brown gas produces an intense heat that can be used in welding, to heat buildings, or heat water. pollution and no negative health effects. During the burning of brown gas, heat and water are produced and virtually no pollutants, thereby allowing burning within occupied spaces without consuming air during the burning process and without the need for an exhaust. There are no known health issues with brown gas, in that handling the gas, a gas leak or exhausts from the burning process don&#39;t include CO or CO 2  or any other gas that will cause suffocation. Furthermore, because brown gas is lighter than air, any leakage will dissipate into the air, whereas other commonly used gasses such as propane are heavier than air, collect at ground level and can be inadvertently ignited. On the negative side, Hydrogen gas and brown gas are volatile and proper precautions must be taken to prevent explosion.  
         [0005]     Current electrolysis techniques use a low-voltage, direct current passing through electrodes immersed in water (a mild acid may be added to increase current flow). Currently, tens to hundreds of ampere are required to produce brown gas in significant volume, requiring around 4 kWh of power to produce 1000 L of hydrogen. It has been measured that 1L of water produces 1234 L of hydrogen and 605 L of oxygen. Being that ⅔s of the earth&#39;s surface is covered with water; an almost limitless supply of brown gas (or hydrogen) is available given sufficient electrical input. It can be seen that the production of brown gas through electrolysis creates a greater volume of brown gas than the water used in the conversion process, hence, the as the process continues in a confined space, the brown gas becomes pressurized.  
         [0006]     There is a need for using brown gas in a commercial embodiment. U.S. Pat No. 2,098,629, “Production of Gas and Combustion Thereof,” to Knowlton, describes a method of generating brown gas and burning the gas to heat water and is hereby incorporated by reference. This patent uses DC power derived by rectifying AC power using a full-wave bridge rectifier. In this, production of gas is regulated by mechanically monitoring the gas pressure and halting electrolysis by disconnecting the DC power source when the pressure exceeds a predetermined threshold set by a spring.  
         [0007]     Unfortunately, the amount of electricity required for generating brown gas and the ability to discretely control the production of the gas in response to demands limits the efficiency of prior systems.  
         [0008]     What is needed is a method and apparatus that will efficiently produce Brown gas with a robust control to modulate production to match consumption.  
       SUMMARY OF THE INVENTION  
       [0009]     In one embodiment, an apparatus for producing brown gas is disclosed including a sealed tank with an exit for extracting the brown gas and a source of modulated direct current with a positive and a negative output; the source can vary the duty cycle of the outputs. At least one anode within the sealed tank is connected through an opening to the positive output and at least one cathode within the sealed tank is connected through a second opening to the negative output and both are at least partially immersed in water. A pressure sensor is coupled to the sealed tank for measuring a pressure of the brown gas and is connected to the source of modulated direct current. The source of modulated direct current changes the duty cycle of the outputs in response to changes in the pressure.  
         [0010]     In another embodiment, a method of producing brown gas is disclosed including providing a sealed tank with an exit for extracting the brown gas and a source of modulated direct current with a positive and a negative output; the source is able to vary a duty cycle of its outputs. At least one anode is provided within the sealed tank and is connected through an opening in the sealed tank to the positive output of the source of modulated direct current. At least one cathode is provided within the sealed tank and is connected through a second opening in the sealed tank to the negative output of the source of modulated direct current. The at least one anode and at least one cathode are immersed in water. The pressure of the brown gas is measured and the duty cycle of the outputs are changed in response to changes in pressure.  
         [0011]     In another embodiment, a means for producing brown gas is disclosed including a tank with an exit for extracting the brown gas and a direct current modulator having a positive output and a negative output. The modulator has a way to vary the duty cycle of the outputs. There is at least one anode within the tank connected through an opening to the positive output of the direct current modulator and at least one cathode within the tank connected through a second opening in the tank to the negative output of the direct current modulator. The anodes and cathodes are at least partially immersed in water. There is a pressure sensor coupled through an opening in the tank and connected to the direct current modulator for measuring the pressure of the brown gas. The direct current modulator changes the duty cycle of the outputs in response to the pressure. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]     The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which:  
         [0013]      FIG. 1  illustrates a schematic view of the apparatus of the present invention.  
         [0014]      FIG. 2  illustrates a plan view of the present invention.  
         [0015]      FIG. 3   a - FIG. 3   c  illustrates power delivery waveforms of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. Throughout this specification, the term “brown gas” is used to describe the mixture of hydrogen (H 2 ) and oxygen (O 2 ) generated through the electrolysis of water. Brown gas is not limited to only hydrogen and oxygen, in that other impurities may exist in the gas without veering from the present invention. Furthermore, the same process and same system works equally well to generate oxygen (O 2 ) and hydrogen (H 2 ) and each may be stored separately and combined later as needed. Throughout this specification, the term water refers to water (H 2 O) with minerals and/or salts such as ordinary tap water, which is a conductor of electricity. Pure water cannot be used because it is an insulator and electricity would not flow and electrolysis would not occur.  
         [0017]     Referring to  FIG. 1 , a schematic of the apparatus of the present invention is shown. Although showing an alternating current power source  10 , the present invention works equally well with a direct current (DC) power source. The source power  10  is rectified by a rectifier  12 . Shown is a full-wave bridge rectifier  12 , though any suitable rectifier configuration works equally as well. The DC output  14  of the rectifier  12  is connected to a duty cycle and frequency modulator and high current driver  16  that modulates the DC voltage, and hence output current. The duty cycle and frequency modulator and high current driver  16  has an input from  22  from the pressure sensor  36  that is used to adjust the duty cycle in response to pressure changes as will be explained later. High current drivers  16  are known in the industry an example of which is a high-current power MOSFETs, silicon controlled rectifiers (SCRs), Triacs or other transistor or multiples of such configured in a parallel fashion, or any other type of high current amplifier including a fast-acting relay. Although, as shown, the AC power is converted to DC power by the rectifier  12 , then the DC power is modulated, there are other ways to modulate the duty cycle that work equally as well. Because of the high current and low voltage required, a step-down transformer (not shown) is often required. In an alternate embodiment, the duty cycle of the AC input to the step-down transformer is controlled using an SCR or Triac, in much the same way as a light dimmer operates. The low-voltage output of the transformer is rectified, resulting in a low-voltage, high-current variable pulse-width DC current.  
         [0018]     The positive output  24  of the high current driver  16  is connected to a series of anodes  32  that are submerged in a tank  31  of water (not pure water). The negative output  26  of the high current driver  16  is connected to a series of cathodes  34 , also submerged in water within the tank  31  and alternately intermixed within the tank  31 , so as to provide a high amount of surface area to provide lower impedance to the flow of electricity between the cathodes  34  and the anodes  32 .  
         [0019]     The area above the water level  30  allows for the collection of brown gas as current flows between the cathodes  34  and the anodes  32 . A valve  40  controls the flow of brown gas out of the tank  31  through a pipe or tube  42 . Not shown are various protection devices to prevent back flashes from reaching the tank  31 , potentially causing an explosion. A pressure sensor  36  monitors the pressure in the tank  31  and is coupled to the duty cycle and frequency modulator and high current driver  16  through signal path  22 . The duty cycle and frequency modulator and high current driver  16  reduces the duty cycle as the pressure increases, thereby limiting the gas pressure. Alternately, the duty cycle and frequency modulator and high current driver  16  increases the duty cycle as the pressure decreases, thereby supplying the needed gas pressure.  
         [0020]     To understand the closed-loop operation of the system, assume the gas output  42  is connected to a hot-water heater (not shown). When the system is first started, no brown gas is present in the tank  31 ; therefore the pressure measured by the pressure sensor  36  is zero (roughly atmospheric pressure). When power is applied, the duty cycle and frequency modulator and high current driver  16  determines that there is no gas pressure and delivers power as in the waveform in  FIG. 3   c , thereby producing brown gas at a high-volume output. As the pressure increases, the gas pressure sensor  36  relays this to the duty cycle and frequency modulator and high current driver  16  and a waveform with a 50% duty cycle (as in  FIG. 3   b ) is generated, thereby producing a medium amount of brown gas. When the gas pressure reaches a high level, the duty cycle and frequency modulator and high current driver  16  delivers a waveform with a low duty cycle (as in  FIG. 3   a ), thereby producing a very small amount of brown gas without stopping the reaction within the water. When the water heater requires gas, for example when water is being used, the valve  40  opens and gas flows from the tank  31  to the water heater, thereby reducing the gas pressure. As the sensor measures a lower pressure, the duty cycle and frequency modulator and high current driver  16  increases the duty cycle delivered to the anodes  34  and cathodes  32 , thereby increasing the production of brown gas. Therefore, only a small amount of brown gas is stored in the tank  31  and when needed, the duty cycle is increased causing production of brown gas to increase.  
         [0021]     The relative gas production is charted against the duty cycle of the frequency modulator in Chart 1. The measurements in Chart 1 were taken using a 100 SCFH flow meter. The frequency modulator uses a full-wave rectifier producing unfiltered direct current of 120 pulses per second having an approximate period of 8.3 ms. The duty cycle is varied by delaying the application of power to the plates of the electrolyzer during each pulse by ⅛, 2/8, ⅜, 4/8, ⅝, 6/8, ⅞ and  8 / 8 , thereby generating duty cycles of 0, 12.5%, 25%, 37.5%, 50%, 62.5%, 75%, 87.5% and 100%. It can be seen in the chart that the gas production varies proportionately with the duty cycle. It can also be seen that the measured data (solid line) is substantially greater than the linear production (dashed line), showing the gas production is more efficient using pulsed direct current rather than using direct current. For example, at a 75% duty cycle, the measured gas production is 96% of the maximum, in that, reducing power input to the system to 75% yields gas production of 96% instead of 75%, producing much higher efficiencies than a system using direct current only. It should be noted that the first two data points of the measured data (0.125 and 0.25) are estimated because the gas production is too slow to accurately measure. 
         
 
         [0022]     Referring to  FIG. 2 a  plan view of the present invention is shown. The tank  80  is filled with water to a level  86  high enough to at least partially cover the anodes  32  and cathodes  34 . A pipe or tube  43  provides a path for the brown gas to be transported to an appliance such as a heater or water heater. In practice, several safety systems (not shown) are attached to the pipe  43  before reaching the appliance to reduce the chances of a back flash reaching the tank  80  and causing an explosion. The top edge of the tank  80  has a flat surface with holes or threads  84  for attaching to the cover  90  through matching holes  94  (the fasteners are not shown for clarity purposes but can be any known in the industry). On the cover  90 , two holes  96  are provided to pass electricity into the electrolysis process. In embodiments where the cover  90  is made from a conductive material, insulators  97  are deployed between the positive  24  and negative  26  terminals of the electrolysis grid and the cover  90 . Each cathode  34  is connected to the negative terminal by a buss  27  and each anode  32  is connected to the positive terminal  24  by a second buss  25 . At the opposite end of each anode  32  and cathode  34  are insulating spacers  39  that keep the ends from getting too close and shorting against each other. Although two pairs of anodes  32  and cathodes  34  are shown, any number and any size is possible depending upon the brown gas output rate desired. Increasing the surface area of the anodes  32  and cathodes  34 , or spacing them closer or increasing their quantity reduces the impedance of the electrolysis grid, allowing higher current and, hence, higher production of brown gas. A pressure sensor/transducer  104  is connected through a pipe  88  into the tank  80  at a point above the water level  86  so gas pressure can be measured and transferred to the duty cycle and frequency modulator and high current driver  102  through wires  105 . In one embodiment, AC power is supplied to the duty cycle and frequency modulator and high current driver  102  by AC power cable  100 . The modulated DC output from the duty cycle and frequency modulator and high current driver  102  is delivered on a negative conductor  106  that connects to the cathodes  34  through the negative terminal  26  and a positive conductor  108  connecting to the anodes  32  through the positive terminal  24 .  
         [0023]     Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result.  
         [0024]     It is believed that the system and method of the present invention and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.