Abstract:
A method for enhancing combustion efficiency and reducing harmful emissions of any furnace fueled by coal or other carbonaceous fuels includes the steps of providing a high-output electrolyzer assembly which includes spaced-apart stainless steel plates submerged in an electrolytic bath. A voltage is applied between the plates and sufficient electrical power is supplied to generate a desired production of hydrogen and oxygen gases. Those gases are captured and directed directly into the combustion air intake of the furnace. Gas flow is controlled, primarily, by varying current flow and electrolyte concentration in the electrolyzer unit. The method differs from those of the prior art in its simplicity in that the oxyhydrogen gas is captured and directed directly into the combustion air intake of the furnace without the use of gas storage tanks, pressure regulators, mass flow controllers, or any other costly control equipment.

Description:
[0001]    This application has a priority date based on the filing of Provisional Patent Application No. 61/331,022 by the same inventor on May 4, 2010. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention is related to an apparatus and method for improving the efficiency of combustion in furnaces fueled with coal, oil, and other carbonaceous fuels by injecting oxyhydrogen (HHO) gas directly into the combustion air intake of the furnace. 
         [0004]    2. History of the Prior Art 
         [0005]    Although coal is the most abundant energy source in most parts of the world, it has received a bad rap from liberal politicians who have identified the mining of coal as a primary cause of environmental despoilation of the environment and the burning of coal as the primary cause of global warming and environmental pollution. Although there is no question that coal mining performed in an irresponsible manner has caused great environmental damage in the past, great strides have been made in minimizing the environmental damage caused by coal mining and coal burning. Just as large scale surface mining of coal has revolutionized the mining of shallow coal deposits, longwall mining has revolutionized the underground mining of coal. Longwall mining now accounts for about 31% of underground coal production. Large scale surface mining and longwall mining are largely responsible for the decreasing costs of mined coal and a dramatic decrease in deaths related to coal mining. The fact remains that if the United States intends to decrease its dependence on energy sources controlled by nations who are, at best, unfriendly to our national interests, coal will need to play an increasing role not only as a fuel for the generation of electricity, but as a precursor for both polymers, fuel oils and gasoline. 
         [0006]    and plastics. 
         [0007]    Coal-fired electric power plants today produce more than 50 percent of the electricity in the U.S. at relatively low cost. Inexpensive electricity is essential to maintaining a dynamic competitive U.S. economy and our standard of living. All coal-fired power plants operate in conformance with stringent federal and state regulatory requirements. Most of these plants are capable of base-load (24/7) operation with high reliability. The coal mining, fuel transportation and transmission infrastructure investment, supporting existing plants and some future plants, is in place. New coal-fired power plants are essential to the future of the U.S. base-load power supply. 
         [0008]    In 2002, ninety-eight percent of all electrical power generated in the U.S. came from four sources: fifty percent of the U.S. electric system power generation came from coal-fired plants, twenty percent came from nuclear plants, twenty-one percent came from oil and natural gas-fired plants, and seven percent came from hydroelectric plants. Base-load electricity, measured in kilowatt hours (kWh), is generated from these four energy resources (plus some geothermal electricity). Off-peak electric generation from these sources costs: hydroelectric (0-1 cents/kWh), nuclear (1-2 cents/kWh), coal-fired (1-2 cents/kWh), oil and natural gas-fired (variable, 3.5-10 cents per kWh). 
         [0009]    Most of the U.S. coal-fired plants are 30-40 years old and have been upgraded to meet emissions regulations. However, only about 25 percent of these older plants have been retrofitted with scrubbers, and only a few plants are equipped with the most effective flue gas cleanup systems technology now available for new power plants. While the average net energy conversion efficiency of existing coal-fired plants is about 32 percent, the next generation of plants can increase this net efficiency to 40 percent or higher with improved technology, thereby reducing coal consumption and emissions in proportion. This benefit will significantly increase the kWh produced per pound of coal burned, with fewer emissions. 
         [0010]    A number of methods have been suggested for improving the efficiency of combustion of coal in the interest of increasing the thermal output and reducing airborne pollution. Although combustion of coal in the presence of high-purity oxygen (purity in excess of 85 percent) has shown promise in reducing emissions, the high cost of producing large amounts of high-purity oxygen dooms the commercial application of such a combustion process. Another method that has shown positive results in reducing harmful emissions is the conversion of coal to combustible gasses, which generally consist of hydrogen and carbon monoxide. Sulfur compounds are easily removed during the gasification process, thereby eliminating sulfur oxide emissions. The problem with the process is that less heat is generated by combusting the gasses than by combusting the feedstock coal. Another method involves hydrogenation of coal by reacting it with hydrogen or methane gas in order to create gaseous or liquid fuels. Unfortunately, the process requires energy to generate the hydrogen or methane gas. The net result is that overall efficiency of the process is reduced. 
         [0011]    U.S. Patent Application Publication 2009/0188449 A1 suggests that thermal efficiency of coal combustion can be increased by injecting stoichiometric amounts of hydrogen and oxygen gases derived from the electrolysis of water at one or more predetermined points into the combustion air intake of a furnace or directly into the flame of the furnace. The process specifies the use of carefully controlled flow rates provided by mass flow controllers and pressure regulators. 
         [0012]    Electrolysis of water is the decomposition of water into oxygen (O 2 ) and hydrogen gas (H 2 ) as a consequence of an electric current being passed through the water. An electrical power source is connected to two electrodes, or two plates (typically made from some inert metal such as platinum or stainless steel) which are placed in the water. In a properly designed cell, hydrogen will appear at the cathode (the negatively charged electrode, where electrons are pumped into the water), and oxygen will appear at the anode (the positively charged electrode). Assuming ideal faradaic efficiency the generated amount (moles) of hydrogen is twice that of oxygen, and both are proportional to the total electrical charge that was sent through the solution. However, in many electrolytic cells, competing side reactions occur, resulting in different products and less than ideal faradaic efficiency. 
         [0013]    Electrolysis of pure water requires excess energy in the form of overpotential to overcome various activation barriers. Without the excess energy the electrolysis of pure water occurs very slowly if at all. This is in part due to the limited self-ionization of water. Pure water has an electrical conductivity about one millionth that of seawater. Many electrolytic cells may also lack the requisite electrocatalysts. The efficacy of electrolysis is increased through the addition of an electrolyte (such as a salt, an acid or a base) and the use of electrocatalysts. Electrolytic process is rarely used in industrial applications since hydrogen can be produced more affordably from fossil fuels. 
         [0014]    Although the primary focus of the present invention is improving the efficiency and reducing emissions from coal-fired furnaces, the invention may also be used effectively to improve the efficiency and reduce emissions from furnaces fueled by any number of carbonaceous compounds and materials. As coal is typically considered to be one of the dirtiest fuels, the invention has much to offer in the interest of improving combustion and reducing emissions from combustion of that fuel. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention overcomes the problems associated with the prior art by providing a simplified process for enhancing combustion efficiency, increasing energy output, and reducing harmful emissions of furnaces fired by coal, oil, solid fuels such as wood products waste, discarded tires, and any other fuel containing complex carbon compounds that are difficult to combust completely using conventional furnaces. In addition, the process can be used with conventional clean-burning fuels such as natural gas and propane. The process includes the steps of providing a high-output electrolyzer assembly which includes spaced-apart anode and cathode plates submerged in an electrolytic bath. A voltage is applied between the plates and sufficient electrical power is supplied to generate a desired flow of hydrogen and oxygen gases. Unlike the processes of the cited prior art, those gases are captured and directed directly into the combustion air intake of the furnace without the use of gas storage tanks, pressure regulators, mass flow controllers, or any other costly control equipment. Compared to prior art processes, the process of the present invention reduces both complexity and cost. Oxyhydrogen gas flow is controlled by varying the size of the anodic and cathodic plates, the current flow between the plates, the concentration of electrolyte and the temperature of the electrolytic solution. Gas flow is generally increased by using larger anodic and cathodic plates, by increasing the current flow between the plates, and by increasing the concentration of electrolyte of the solution. The equilibrium temperature of the electrolytic solution is a function of the electrolyte concentration and the current flow between the plates. A preferred temperature range for the electrolytic solution is deemed to be 52-77° C. (about 125-170° F.). Oxyhydrogen production drops off rapidly at temperatures below this range, and as temperatures approach the boiling point, the generation of steam reduces furnace combustion temperatures. For one embodiment of the invention, 50 VDC was applied between the plates of the electrolyzer unit current was varied between 30 and 140 amps. Concentrations of oxyhydrogen gas are provided to the air intake of the furnace at concentrations which are sufficiently low that flashbacks will not occur. For a preferred embodiment of the process, the hydrogen generated by the electrolyzer unit contributes between 10 to 50 percent of the thermal output of the furnace. Other than a fill valve used to maintain proper electrolyte levels in the electrolyzer unit, the apparatus and method require no moving mechanical components. As such, it is capable of continuous operation for extended periods of time with little or no maintenance. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a block diagram of the apparatus used to implement the disclosed process in the context of a coal-fired furnace; 
           [0017]      FIG. 2  is a block diagram of an oil or gas fired furnace coupled to the output of an oxyhydrogen generator; 
           [0018]      FIG. 3  is a graph of tons of coal burned per hour vs. time for a first test; 
           [0019]      FIG. 4  is a graph of tons of coal burned per hour vs. time for a second test; 
           [0020]      FIG. 5  is a graph of tons of coal burned per hour vs. time for a third test; 
           [0021]      FIG. 6  is a graph of tons of coal burned per hour vs. time for a fourth test; and 
           [0022]      FIG. 7  is a graph of tons of coal burned per hour vs. time for a fifth test. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The invention will now be described in detail with reference to the attached drawing figure. It should be understood that the coal furnace arrangement is only exemplary and that the oxyhydrogen injection system can be used full time in combination with a variety of different furnaces, including those fueled by oil, natural gas, propane and other solid organic materials, such as wood industry byproducts, discarded and shredded tires, and even garbage having a high carbonaceous content. 
         [0024]    Referring now to  FIG. 1 , for one embodiment of the invention, a rectifier  101  having a 220 VAC input is employed. Current at 50 VDC is sent to two spaced-apart corrosion-resistant plates  103 A and  103 B within an electrolyzer unit  102  that is filled with electrolyte  104 . For a preferred embodiment of the invention, stainless steel plates are used. Hydrogen and oxygen gases that are generated escape the electrolyzer unit  102  through an escape tube  105  that empties into the combustion air induction manifold  107  of a coal-fired furnace  112 . A high speed fan directs high-speed combustion air mixed with oxyhydrogen gases into the lower end of a rotating drum  113 . Pulverized coal  106  is also fed into high-speed combustion air. The mixture of pulverized coal and hydrogen gas are ignited by the flame igniter  110  in the presence of the combustion air enriched by the oxygen gas from the electrolyzer unit  102 , and flame shoots into the lower end of the rotating drum  113 . It should be evident that other solid, pulverized fuel may be used in place of coal. An aggregate feed chute  114  feeds aggregate  115  at a constant rate into the upper end of the rotating drum  113 . As the drum rotates (the rotating mechanism is not shown, but well known in the art), the aggregate  115  is churned by the rotating drum  113  and gradually moves down the inclined drum. At the lower end of the rotating drum  113 , the aggregate falls out in a stream  115  at the same rate that it is fed in at the upper end of the rotating drum  113 . It can be moved by a conveyor belt (not shown) to a storage location. The incoming oxyhydrogen gas improves the combustion efficiency of the coal. 
         [0025]    The same electrolyzer system can be used to provide oxyhydrogen gas to different types of furnaces which burn carbonaceous fuels, whether that fuel be fuel oil, bunker oil, waste oil, wood industry byproducts, and even dried and shredded combustible garbage. Although stainless steel is deemed to be the most cost-effective material for the anodic and cathodic plates, other plate materials, such as platinum and carbon, may be employed with successful results. 
         [0026]    Referring now to  FIG. 2 , for a generic embodiment of the invention, a rectifier  101  having a 220 VAC input is employed. Current at 50 VDC is sent to two spaced-apart corrosion-resistant plates  103 A and  103 B within an electrolyzer unit  102  that is filled with electrolyte  104 . For a preferred embodiment of the invention, stainless steel plates are used. Hydrogen and oxygen gases that are generated escape the electrolyzer unit  102  through an escape tube  105  that empties into the combustion air induction manifold  201  of a gas or oil-fired furnace. The furnace has a burner assembly  202  which receives gas or oil hydrocarbon fuel through a fuel intake line  203 . The fuel, along with the hydrogen produced by the electrolyzer  102  is burned in the combustion chamber  204 . 
         [0027]    Some data has been obtained relating to improved combustion efficiencies achieved by injecting hydrogen and oxygen gases into the combustion air intake of a coal-fired kiln used to remove moisture from expanded shale aggregates. The aggregates, which are used in a range of applications from structural concrete to geotechnical fill, are produced by Utelite Corporation of Utelite Corporation of Coalville, Utah. The data was generated at Utelite&#39;s plant in Wanship, Utah. It should be understood that the operation of the coal-fired furnace was under the control of Utelite Corporation employees who were far more interested in achieving production quotas than in testing an improved combustion process. Nevertheless, the data obtained indicates that a combustion process using coal, in combination with oxygen and hydrogen gases introduced into the combustion air intake results in more efficient combustion of the coal that simply cannot be explained by the thermal contribution of the combusted hydrogen gas. 
         [0028]    Referring now to  FIG. 3 , the data for this graph of tons of coal burned per hour vs. time was obtained over a seven hour period on Mar. 17, 2010. A two-plate hydrogen generation unit was powered with a battery charger, which provided a constant 50 amps of current at 48 volts DC. The coal feed (or burn) rate was initially 10.2 tons per hour. Within two minutes of introducing the hydrogen and oxygen gases from the generation unit into the furnace air intake, a feed rate of only 9.8 tons per hour was required to maintain the initial temperature. The lowest coal feed rate required to maintain the initial temperature within the furnace was 8.2 tons per hour. 
         [0029]    Referring now to  FIG. 4 , the data for this graph of tons of coal burned per hour vs. time was obtained over a 3.5 hour period on Mar. 18, 2010. For this test, the two-plate hydrogen generation unit was powered by the transformer of an arc welder, which provided a constant 150 amps of current at 50 volts DC. The coal feed (or burn) rate was initially 8.8 tons per hour. Within an hour of introducing the hydrogen and oxygen gases from the generation unit into the furnace air intake, a feed rate of only 7.8 tons per hour was required to maintain the initial temperature of the furnace. After two hours, the feed rate had fallen to three tons per hour. During the following hour, the feed rate fluctuated somewhat—rising to 4 tons per hour after water was added to the hydrogen generation unit, and then dropping to 3.8 tons per hour thirty minutes later. After the flow of hydrogen and oxygen gases was terminated, the feed rate returned to the initial value of 8.8 tons per hour. 
         [0030]    Referring now to  FIG. 5 , the data for this graph of tons of coal burned per hour vs. time was obtained over a ninety-minute period on Mar. 19, 2010. For this test, the two-plate hydrogen generation unit was, once again, powered by the arc welder transformer, which provided a constant 150 amps of current at 50 volts DC. The coal feed (or burn) rate was initially 9.9 tons per hour. Within thirty minutes of introducing the hydrogen and oxygen gases from the generation unit into the furnace air intake, a feed rate of only 6.2 tons per hour was required to maintain the initial temperature of the furnace. After thirty additional minutes, the feed rate had climbed to 7.2 tons per hour. The flow of hydrogen and oxygen gases was then terminated, whereupon the coal feed rate returned to the initial value of 9.9 tons per hour. 
         [0031]    Referring now to  FIG. 6 , the data for this graph of tons of coal burned per hour vs. time was obtained over a ninety-minute period on Mar. 25, 2010. For this test, the two-plate hydrogen generation unit was, once again, powered by the arc welder transformer, which provided a constant 150 amps of current at 50 volts DC. The coal feed (or burn) rate was initially 8.2 tons per hour. Within fifteen minutes of introducing the hydrogen and oxygen gases from the generation unit into the furnace air intake, a feed rate of only 7.0 tons per hour was required to maintain the initial temperature of the furnace. Sixty minutes into the test, the feed rate had climbed to 7.6 tons per hour. The flow of hydrogen and oxygen gases was then terminated, whereupon the coal feed rate returned to the initial value of 8.2 tons per hour. 
         [0032]    Referring now to  FIG. 7 , the data for this graph of tons of coal burned per hour vs. time was obtained over a ninety-minute period on Mar. 29, 2010. For this test, the two-plate hydrogen generation unit was, once again, powered by the arc welder transformer, which provided a constant 190 amps of current at 52 volts DC. The coal feed (or burn) rate was initially 8.6 tons per hour. Within thirty minutes of introducing the hydrogen and oxygen gases from the generation unit into the furnace air intake, a feed rate of only 8.0 tons per hour was required to maintain the initial temperature of the furnace. After two hours and 45 minutes, the feed rate had dropped to 7.4 tons per hour. The flow of hydrogen and oxygen gases was then terminated, whereupon the coal feed rate rose to 8.0 tons per hour. 
         [0033]    During the past decade, there has been renewed interest in the production of oxyhydrogen gas with the use of electrolyzers. This invention is not limited to a particular type of electrolyzer unit. Multi-plate electrolyzer units may also be used, and both direct and alternating current may be applied between the anodic and cathodic plates. In addition, the voltage applied to the anode and cathode may be varied over a wide range, as can be the current flow through the electrolyte. 
         [0034]    While only a single embodiment of the invention has been illustrated and described, it will be obvious to those having ordinary skill in the art that modifications and changes may be made thereto without departing from the scope of the invention.