Patent Application
20240150257
The present disclosure relates to an energetic family of monopropellant fuel compositions that, when burned, can produce safer, cleaner energy for propulsion, heat, or power generation. The exhaust products which are benign and non-toxic, can be filtered or recycled for use in human survival and well being in the form of environmental heat and drinking water. These compositions are specifically useful for manned or unmanned undersea and outer space vehicles, or for heat and power generation in environments that are void of atmospheric oxygen (oxygen free), and anywhere it is desired to use a fuel that reduces or eliminates pollution hazards. Preferred compositions are completely water soluble, and thereby “wakeless,” and are specifically useful for manned or unmanned undersea vehicles.
Hydrogen peroxide has been used in many applications for propulsion and power generation for many years. The general history of hydrogen peroxide and its evolution as a propellant are discussed in an internet publication “Past and Present Uses of Rocket Grade Hydrogen Peroxide” by E. Wernimont, M. Ventura, G. Garboden and P. Mullins, General Kinetics, LLC, Aliso Viego, CA 92656.
Hydrogen peroxide was first manufactured at a 3% concentration. An electrolytic process for producing high quality 35% hydrogen peroxide was developed shortly after WWII. The industrial production of hydrogen peroxide was founded on its use as an industrial chemical, primarily by the paper pulp and textile industries.
The first major use of hydrogen peroxide for propellant application was circa 1935 where 80% hydrogen peroxide was used for submarine turbine drive systems and take-off units (ATO's, also known as JATO's or RATO's). A 400 hp turbine driven by hydrogen peroxide with liquid injection of permanganate salt solution catalyst was developed for submarine propulsion.
The Germans used concentrated hydrogen peroxide, 80 to 85 percent H2O2 by weight, as oxidizers in rocket motors and for steam generation in turbine pump drives, launching ramps, and the like (“Hydrogen Peroxide as a Propellant” Ralph Bloom, Jr., Noah S. Davis, Jr., and Samuel D. Levine, J. American Rocket Society, No. 80, March 1950; Published Online: 31 May 2012— https://doi.org/10.2514/8.4301).
Industrial and Engineering Chemistry, April 1956, disclosed:
The U.S. Navy used 70% hydrogen peroxide in their MK 16 torpedo in 1955 (Wolf, S., “Hydrogen Peroxide as a Torpedo Propellant,” U. S. Naval Underwater Ordnance Station Rept.-360, March 1963). The peroxide used in the Bofors' torpedo (Tp 61 and Tp 62) is HTP with a concentration around 89 percent. Their system is based on the fact that mixtures of HTP and kerosene are hypergolic (react to produce instant flame and hot expanding gases). Decomposition of HTP alone can produce temperatures above 1100° F. Instead, the lower concentration of stabilized peroxide is used in this preferred monopropellant is less than 55% which results in a low adiabatic decomposition temperature (212° F., with residual water) which renders the monopropellant unable to produce the hypergolic reaction that HTP fuels are capable of. This lower concentration provides an energetic yet safe source of propulsion which eliminates many of the risks and past tragedies associated with HTP, or high costs and hazards of lithium ion, and other highly toxic fuels.
Post WWII space programs produced hydrogen peroxide combustion devices and systems based on hydrogen peroxide. Hydrogen peroxide was basically the first monopropellant and was used on many of the early spacecraft and high-altitude X-vehicles. It later was replaced by hydrazine when technical issues for that monopropellant were resolved. The X-15 used hydrogen peroxide for attitude control with 90% hydrogen peroxide monopropellant rocket engines.
Hydrogen peroxide was used as an oxidizer with kerosene in 1950's British rockets. One propellant formulation included hydrogen peroxide—98%/RP-1 with the optimum oxidizer to fuel ratio of 7.07. Another formulation included hydrogen peroxide—95%/RP-1 with the optimum oxidizer to fuel ratio of 7.35 (www.astronautix.com/h/h2o2kerosene.html #top).
Hydrogen peroxide has been used in many vehicles to produce steam or expanding gasses as a working fluid to drive turbines. A less well known but very useful application of hydrogen peroxide is to generate large volumes of steam in a very short time to aspirate large vacuums.
High concentrations of hydrogen peroxide will form spontaneous igniting mixtures with fuels.
In the 1970's and 80's, the superior performance of hydrazine displaced hydrogen peroxide from many applications.
U.S. Pat. No. 3,197,348 discloses a thixotropic propellant which is obtained by adding finely divided particles (1 to 20 millimicrons) in a concentration of 1 to 5 percent by weight of the liquid propellant. A mixture containing nitroglycerin and triacetin was prepared and millimicron silica was added to obtain a gel. Ammonium nitrate was added to the gel. A number of monopropellants, which include both fuel and oxidant in the same molecule, and which may be used in lieu of nitroglycerin, were disclosed including hydrogen peroxide. It also was disclosed that monopropellants can comprise a mixture of fuel and oxidant including a list of various hydrocarbons as fuel and hydrogen peroxide as an oxidizer.
U.S. Pat. No. 4,294,586 discloses a gasoline and diesel fuel additive comprising a mixture of alcohol, toluene and hydrogen peroxide. The preferred ratio of substances in the additive mixture was disclosed as 16/8/1, respectively. The substances are vigorously blended and immediately put into suitable containers, and tightly sealed, to prevent deterioration of the mixture.
U.S. Pat. No. 7,503,944 discloses a method for improving the combustion of a fuel by adding a catalyst or combustion enhancement in extremely low concentration, preferably in the range of 1 part catalyst per 200 million parts fuel to 1 part catalyst per 6 trillion parts fuel. In an example, the first step of preparing the catalyst for addition to fuel involves dissolving 4-10% soluble catalyst by weight into 96-90% water. It is disclosed that hydrogen peroxide also may be used. One gram of the mixture from step 1 is added to 19 grams of isopropyl alcohol and/or MTBE. The resulting 20 grams of liquid is diluted with 980 grams of isopropyl alcohol, MTBE or water. This liquid may be further diluted by a factor of 1000. The final additive mixture is added to fuel at a ratio of about 10 parts per million to 80 parts per million of fuel, by weight.
DERWENT-ACC-NO: 2014-C11252 DERWENT-WEEK: 201410 disclosed a synthetic fuel that comprises methanol, isopropyl alcohol, triethanolamine, hydrogen peroxide, water, iron naphthenate and essence (CN 103421549 A, Dec. 4, 2013). The synthetic fuel comprises 92-93% methanol, 0:12-0:15% isopropyl alcohol and triethanolamine, 0:6%-0:8% hydrogen peroxide, 3-4% water, 0:03-0:05% iron naphthenate and essence. Preparation of the synthetic fuel comprises dissolving triethanolamine in container with hydrogen peroxide and water, adequately mixing and dissolving mixed solvent in different container with methyl alcohol, isopropyl alcohol and iron naphthenate; adding little essence; mixing and stirring uniformly, sampling and checking, and filling.
A monopropellant used by the U.S. Navy, as described in the Otto Fuel Handbook, IHSP 70-50 10 Apr. 1970, comprises three components: a nitrate ester (propylene glycol dinitrate) as the energy component accounting for the largest percentage of the composition by weight, a diluent or desensitizer that accounts for the second largest ingredient by weight, and a stabilizer that comprises the smallest percentage by weight of the Otto Fuel II formulation. The specific materials used are not identified. The desensitizer was chosen for its chemical and physical similarities to the energy component. The two materials are mutually soluble, but neither is soluble in water. The stabilizer keeps the decomposition rate of the nitrate ester at a minimum, providing better shelf life. Otto Fuel II can be harsh on hardware and produces very toxic waste stream. Its combustion products are known to contain over 40% Carbon Monoxide (CO) (Otto Fuel II Monopropellant handbook IHSP 70-50 10 Apr. 1970 page 7-2.2.6) and 0.91% Hydrogen Cyanide (HCN) among other undesirable and toxic hazardous substances (Otto Fuel II Monopropellant handbook IHSP 70-50 10 Apr. 1970 page 48—Table 2-V—Otto Fuel II Gas Analysis Results).
For Spills and clean up, the OTTO Fuel must first be removed, then the area must be cleaned with a strong detergent water before the final clean up with a decontaminant known as “NG-killer” which is a combination of Sodium Sulfide and Denatured Ethyl Alcohol that must be specially mixed not more than 60 days in advance. Personnel must use self-contained breathing apparatus when handling Otto Fuel, or to execute this cleanup process with NG-Killer. It must be noted that NG-killer MUST NOT COME IN DIRECT CONTACT with quantities of Otto Fuel because it would cause rapid decomposition and burning of fuel resulting in brown, toxic fumes. (Otto Fuel II Monopropellant handbook IHSP 70-50 10 Apr. 1970 page 31-4.6)
In view of problems associated with many prior art propellant compositions, it is desirable to provide a water-soluble, non-toxic, energetic, safe and stable monopropellant at a low cost. An important distinction should be made between monopropellant compositions of the present invention and other past fuels which typically used a much higher concentration of Hydrogen Peroxide known as High Test Peroxide. Monopropellant compositions of the present invention do not incorporate the use of High Test Peroxide (HTP). Although H2O2 concentrations at approximately 70% have been used for rocket and aerospace propulsion, HTP is categorized by more typically at 85% or higher, and up to 98%. At these high concentrations of H2O2 significant risks are present. The British lost the Sidon in 1955 and the Russians lost the Kursk in 2000 due largely to the very dangerous use of HTP (High Test Peroxide).
The present invention provides a monopropellant fuel comprises an approximately stoichiometric amount of a water-soluble hydrocarbon fuel and hydrogen peroxide in water, wherein the water is present in an amount of at least about 30%, preferably at least about 35% of the total weight of the fuel. The quantities of water-soluble hydrocarbon fuel and hydrogen peroxide are stoichiometrically calculated as to produce a product consisting essentially of carbon dioxide and water.
In a preferred embodiment, the mono propellant fuel consists essentially of an approximately stoichiometric amount of a water-soluble hydrocarbon fuel and hydrogen peroxide in water. Typically, the fuel and hydrogen peroxide are present within normal manufacturing tolerances of the stoichiometric amount as calculated to produce carbon dioxide and water. Exact stoichiometric concentrations of hydrogen peroxide and hydrocarbon fuel are preferred. However, deviations from the stoichiometric calculated quantities of hydrocarbon and hydrogen peroxide up to about 10% by weight may be tolerated for particular applications, however, such deviations are not preferred.
In preferred embodiments of the invention, the amount of water is present in an amount of about 30% to about 50%, more preferably from about 35% to about 45%, of the total weight of the fuel. Preferably, the fuel is a lower alcohol such as, for example, methanol, ethanol, propanol, isopropanol, t-butanol. However, any water-soluble hydrocarbon compound consisting of hydrogen and from 1 to about 4 carbon atoms wherein the combustion products are primarily carbon dioxide and water can be useful in the practice of this invention. The most preferred hydrocarbon is isopropanol.
The monopropellant fuel of the present invention contains an oxidizer, a hydrocarbon fuel, and water each of which are mutually soluble in the other ingredients resulting in a water soluble monopropellant. The oxidizer and the fuel are preferably present in stoichiometric concentrations. However, some deviation from stoichiometric concentrations can be acceptable for some applications, providing some additional, normally unwanted by-products can be tolerated. The diluent, water, is present at such a concentration that it serves two purposes. First, the amount of water can be calculated to reduce the adiabatic flame temperature; for example, in some cases a flame temperature of about 2300° F. to about 3000° F. is desirable. The other major purpose of the water is to dilute the oxidizer and fuel to a point where they can be safely mixed and so they will be insensitive to impact and other abusive stimuli. This is a deliberate safety characteristic built into the preferred versions of this fuel. The oxidizer and the diluent are non-flammable. The concentration of the hydrocarbon fuel is about 8 wt % to about 12 wt %, preferably at about 9.5 wt % to about 10.5 wt %, more preferably about 10 wt % and, as such, presents only a small hazard. The fuel can be selected from various water-soluble materials depending on acceptable by-products for the specific use.
Preferably, the fuel is selected to have a low enough vapor pressure so as not to boil at the 70° C. environmental test temperatures, but high enough vapor pressure so as to be the first component to boil off if a container of the monopropellant fuel is exposed to excessive heat as would be encountered in a fire. Once the small amount of fuel boils off, the energetics of the oxidizer-water mixture can be substantially reduced. Because the preferred monopropellants in accord with the present invention contain substantial amounts of water, if all of the peroxide were to decompose adiabatically, the maximum temperature would be the boiling point of water, i.e. 100° C. (212° F.). This provides a deliberate safety feature designed into preferred monopropellants of the invention.
The monopropellant fuel is prepared generally by mixing the proper amount of hydrogen peroxide with the proper amount of water and, then, mixing in the hydrocarbon fuel. A mixer is inserted, and the mixture is stirred until a vortex forms, i.e. about 1-2 minutes for 500 lbs of mixture. A highly stabilized commercial grade of hydrogen peroxide is preferred and is used in the preferred versions of the monopropellant fuel for the best desirable characteristics. Commercial sources of hydrogen peroxide can be purchased from, for example, Evonik Industries (U.S. office: Philadelphia, PA) and Arkema S. A. (U.S. office: King of Prussia, PA).
Preferred monopropellant fuels in accord with the present invention are low cost, environmentally benign, high energy density monopropellant fuels that provide a thermal energy source tested to be safe as shown in abuse and hazardous classification tests from Stresau Lab Laboratory Inc in Spooner Wisconsin, as described herein.
Preferred monopropellant fuels in accord with this invention “burn” through an oxidation reduction process producing exhaust products and waste heat which are essentially environmentally benign and can be filtered, recycled, and repurposed for human survival and wellbeing in the form of drinking water and environmental or cabin heat. Thus certain preferred monopropellant fuels can be made with various energy densities and flame temperatures providing a thermal energy source which is well-tested, mature, energetic, environmentally benign, and is considerably safe to produce and use. As such, preferred fuels can be ideal for use in propulsion of manned or unmanned underwater vehicles, thermal generation systems, and power sources in environments where there is an absence of oxygen.
A feature of preferred monopropellant fuels of the present invention is that spills, human exposure, and handling are much easier and safer when mitigation is necessary. Contact or exposure to any surface including human tissue is easily mitigated with water and combustion products are non-toxic to the environment when burned. This can result in a potential cost savings at every level of manufacturing, usage, engine turn-around and cleanup.
Preferably, monopropellant fuels of the present invention have an initial freezing temperature of at least about −50° F., more preferably at least −80° F., and do not separate into components when frozen, which permits safe use and storage in cold environments.
Monopropellant fuels in accord with the present invention preferably can be ignited at atmospheric pressure using black grain powder, heater-band assemblies, automotive glow plugs, and nichrome wire, and the like, thereby providing start, stop and restart capability, in addition to “gas and go” capabilities when fuel replenishment is necessary during particular applications.
The present invention provides a relatively safe, non-toxic monopropellant fuel that, when combusted, produces superheated steam and thereby forms substantially only carbon dioxide and water as by-products. Preferred embodiments consist essentially of a water-soluble hydrocarbon fuel and hydrogen peroxide mixed in water. The hydrocarbon fuel and hydrogen peroxide are present preferably in substantially stoichiometric amounts as calculated by an equation combining the hydrocarbon with hydrogen peroxide to form carbon dioxide and water. For example, for isopropanol:
9H2O2+C3H7OH→3CO2+13H2O
Preferred monopropellant fuels are water-soluble hydrocarbons that combust stoichiometrically with hydrogen peroxide to form only carbon dioxide and water. Preferred hydrocarbons are lower carbon alcohols having 1-4 carbon atoms. More preferred is isopropanol in view of its commercial availability, high energy density and stability. However, if some nitrogen containing by-products can be tolerated, then, a water-soluble lower carbon nitrogen containing hydrocarbon preferably having 1-4 carbon atoms can be used in the practice of this invention.
The amount of hydrocarbon in a resulting preferred monopropellant composition is from about 8% to about 12% by weight (wt %), preferably about 9% to about 11%, of the total weight of the monopropellant fuel.
The hydrogen peroxide typically is a commercial grade that has been highly stabilized. As aforesaid, such commercial grade hydrogen peroxide is available from such suppliers as, for example, Evonik Industries (U.S. office: Philadelphia, PA) and Arkema S. A. (U.S. office: King of Prussia, PA).
The amount of hydrogen peroxide in the resulting monopropellant fuel is stoichiometrically calculated based on the amount of hydrocarbon in the fuel. For example, when using isopropanol for the water-soluble hydrocarbon, the amount of hydrogen peroxide is about 5.1 times the amount by weight of isopropanol.
Water is added in a suitable amount to provide desired safety features. The amount of water in the resulting monopropellant fuel is generally from about 30% to about 50% by weight, preferably about 35% to about 45%, by weight of the total weight of the monopropellant fuel.
The monopropellant fuels of the present invention can be made simply by mixing the components in a suitable container. Preferably, the calculated amount of hydrogen peroxide and water are mixed first, and then, the fuel is added while stirring the mixture. The final mixture may be stirred with a mechanical mixer until a vortex is formed for about 1-2 minutes.
Although considered to be very safe, the relative safety depends on the hydrocarbon being used for combustion and the quantity of water in the fuel. Isopropanol is most preferred for safety characteristics while remaining energetic. It should be noted that hydrogen peroxide can be considered to be a “strong oxidizer that causes burns to eyes or skin” where treatments for exposure are to “immediately flush with copious amounts of water for at least 15 minutes. With respect to clean up, because it's non-toxic, spills are easily mitigated by flushing with copious amounts of water and with a waste disposal method of diluting with water, preferably about 50:1.
Toxicological testing on MFI was performed by the Marshfield Medical Research Foundation, Marshfield WI. Their findings indicate that there is little difference between MFI and the same percentage (less than 50%) of hydrogen peroxide alone in water with regards to dermal, respiratory, or ocular effects. With both MFI and the hydrogen peroxide, the effects on the subject animals were minor and transitory. Moreover, rinsing with water soon after exposure to MFI minimized even these minor and transitory effects. As with peroxide at the same concentration, a spontaneous combustion hazard exists when in contact with organic materials. Regarding explosion hazard data, the WI mixture is nearly self-extinguishing using copious amounts of water where no explosion hazard exists and, although the oxidized contacting combustibles may cause or intensify fire, a non-toxic gas is released (which can cause overpressure if confined).
500 pounds of a monopropellant fuel consisting of 10.4 weight percent (wt %) isopropanol, 45.4 wt % hydrogen peroxide and 44.2 wt % water was prepared. In a 55 gallon drum, 447.75 lbs of 59% commercial grade, stabilized hydrogen peroxide (PEROXAL 59%) is charged. To the hydrogen peroxide is added 52.25 lbs of isopropanol (99% isopropyl alcohol). A mixer is inserted and the liquid mixed for 1-2 minutes until a vortex is formed. A test sample shows a specific gravity of about 1.18.
Three isopropanol/hydrogen peroxide monopropellant fuels designated as MFI, MFII, and MFIII were prepared having various concentrations of water dilution. MFIII is the most energetic member of the family that meets a safety criterion of passing a closed cup impact test at 158° F. (70° C.) impacted with 150 kilogram-centimeters (Kg-cm) of energy. As seen in Table 1 below, the energy content and flame temperature vary with the water content (MFI—42.8 wt %; MFII—41.3 wt %; MFIII—36.6 wt %). Each of these fuels tested provide decomposition yields having a gravimetric energy density of more than about 1100 BTUs per pound (more than 10,000 BTUs per gallon) at a flame temperature greater than approximately 2350° F. It should be noted that the volumetric energy density of fuels can be more important than the gravimetric energy density for particular applications.
MFIII can be safely preheated to 198° F. using waste engine heat to produce an additional 100 Btu's per pound. This waste heat recuperation provides a 7.4 percent increase in useful energy not shown in Table 1.
Exhaust Gas Analysis was performed by BAE Systems. Quantitative analyses of the exhaust gas samples from Tests 3 through 6 were conducted to determine the completeness of the combustion process. Test runs 1 and 2 were conducted to demonstrate sustained ignition and self-sustained combustion (crossover) of the fuel (analysis not run). The analysis was conducted using a technique based upon gas chromatography. The weight percent of the major constituents of the exhaust gas are shown in Table 2. The results indicate that a very small amount of carbon monoxide is present. The small amount of carbon monoxide (an average of 0.086 percent for the four tests) indicates that the combustion of isopropyl alcohol was 99.914 percent complete. However, the oxygen levels indicate that an average of only about 97.2 percent of the combustion was complete for the four tests. If the oxygen level reading was correct, 2.8 percent of other organic fragments should be found in the analysis. Since no other organic fragments were found, the existence of excess oxygen is questionable, although it could represent a small deviation from stoichiometric quantities when mixing the monopropellant, while the small percent of carbon monoxide is indicative of nearly complete combustion. Also, small leaks in gas sampling tanks may have allowed air to enter.
Fuel flow rate was about 0.85 gallons per minute. Self-sustained combustion was at nominal pressure in range of about 1900 psig to about 2100 psig.
A polypropylene drum filled with about 500 pounds of MFI was placed in a raging bonfire that melted the container spilling MFI. At one point, the barrel melted and spilled a large quantity of MFI into the fire, however, no explosion or ignition was presented by the spilled fuel.
A single package ignition test was conducted at Stresau Laboratory in Spooner Wisconsin. In the test a Number 8 black powder blasting cap was inserted into the drum and detonated with a squib. The 500 pound drum of MFI fuel was lifted by the impact of the blast, and a plume of fuel rose from the drum, but no detonation or ignition of the MFI fuel occurred. This demonstrates the safety features which were specifically designed into this preferred monopropellant.
Aluminum pipes were filled and capped, 50 caliber armor piercing rounds penetrated the aluminum pipes, 3 pipes radially and 3 pipes axially. The armor piercing bullets failed to produce any flame or detonation of the MFI fuel.
The monopropellant fuel compositions of the present invention can be used for manned or unmanned undersea and outer space vehicles, or for heat and power generation in environments that are void of atmospheric oxygen (oxygen free), and anywhere it is desired to use a fuel that reduces or alleviates pollution hazards.
A Combustion Test Stand (CTS) can be designed by those skilled in the art to safely combust various monopropellants utilizing suitable ignition systems such as, e.g., a two-speed reciprocating external combustion engine. Combustion products can be cooled in a spray desuperheater. Cooling water and exhaust gases can be separated in a cyclone separator and disposed of in an environmentally safe manner. The stand can be provided with all necessary valving to control and meter the flow of fuel during combustion. No work is performed by the combustion process using the CTS and Instrumentation is provided to measure and record desired parameters such as combustion temperature, pressure, fuel flowrate, etc. It also provides a means to sample exhaust products for quantitative analysis.
The monopropellant fuels of the present invention can be burned in commercially available Vane motors. Several small-scale tests were run using the superheated steam of the exhaust gases caused by burning the fuel in a 36 hp combustion chamber designed by JRM Inc. to turn a modified Vane motor which powered a calibrated industrial fan as a workload. Modifications to the Vane motor can be made by those skilled in the art to endure high temperatures caused by some fuel compositions. Also, the monopropellant fuels of the present invention can be burned in a “Cyclone MKV” Rankine engine. Other potential applications include steam turbines (as mentioned above) that would make use of the clean exhaust of superheated steam as a working fluid generated by the combustion of a suitable monopropellant fuel.
Heat regenerative engines, as described in U.S. Pat. No. 7,080,512 and available from Cyclone Power Technologies, Inc., Pompano Beach, FL., can be used with the fuels of the present invention.
In another embodiment, for example, an external combustion, swash plate engine having six cylinders can be fueled by the monopropellant which provides its own oxidizer. Linear piston motion can be converted to rotary shaft motion via the swash plate mechanism. Two, counter-rotating shafts can be used to drive loads. Fuel is combusted in an external combustion chamber and the combustion gases are ported to each of the six cylinders by a rotary valve. Ignition can be accomplished by a squib-ignited “grain.” Fuel can be delivered to the combustion chamber by a high pressure, positive displacement pump.
The invention has been described in detail with specific references to certain monopropellant fuel compositions. However, those skilled in the art will recognize that the monopropellant fuel compositions in accord with the present invention can be tailored for various types of applications.
Although the invention has been described in detail, it will be apparent that numerous modifications may be made by those skilled in the art without departing from the spirit and scope of the invention.
