MONOPROPELLANT HYDROGEN PEROXIDE FUEL COMPOSITIONS SUITABLE FOR USE IN NO OXYGEN ENVIRONMENTS

Abstract

The invention describes a monopropellant fuel that is a mixture in water of a water-soluble hydrocarbon fuel and hydrogen peroxide, where the hydrocarbon fuel and hydrogen peroxide are present in an approximately stoichiometric amount calculated to produce only carbon dioxide and water, wherein water is present in an amount at least 30% of the total weight of the monopropellant fuel.

Claims

1. A monopropellant fuel comprising a mixture in water of a water-soluble hydrocarbon fuel and hydrogen peroxide, where the hydrocarbon fuel and hydrogen peroxide are present in an approximately stoichiometric amount as calculated to produce only carbon dioxide and water, wherein water is present in an amount at least 30% of the total weight of the monopropellant fuel.

2. The monopropellant fuel of claim 1 wherein the water is present in an amount of about 30% to about 50% of the total weight of the fuel.

3. The monopropellant fuel of claim 1 wherein the hydrocarbon fuel is present in an amount of from about 8% to about 12% of the total weight of the fuel.

4. The monopropellant fuel of claim 1 wherein the hydrocarbon fuel and the hydrogen peroxide deviate less than about 10% by weight of amount calculated to provide the stoichiometric by-products of carbon dioxide and water.

5. The monopropellant fuel of claim 1 having a fuel energy density more than 1100 BTUs per pound.

6. The monopropellant fuel of claim 1 having a fuel energy density more than 10,000 BTUs per gallon.

7. The monopropellant fuel of claim 1 having a flame temperature greater than about 2300? F.

8. The monopropellant fuel of claim 1 wherein the hydrocarbon fuel is a 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.

9. The monopropellant fuel of claim 8 having a fuel energy density more than 1100 BTUs per pound.

10. The monopropellant fuel of claim 8 having a fuel energy density more than 10,000 BTUs per gallon.

11. The monopropellant fuel of claim 8 having a flame temperature greater than about 2300? F.

12. The monopropellant fuel of claim 8 wherein the water is present in an amount of about 30% to about 50% of the total weight of the fuel.

13. The monopropellant fuel of claim 8 wherein the hydrocarbon fuel is present in an amount of from about 8% to about 12% of the total weight of the fuel.

14. The monopropellant fuel of claim 8 wherein the hydrocarbon fuel and the hydrogen peroxide deviate less than about 10% by weight of amount calculated to provide the stoichiometric by-products of carbon dioxide and water.

15. A monopropellant fuel consisting essentially of a mixture in water of a water-soluble hydrocarbon fuel and hydrogen peroxide, where the hydrocarbon fuel and hydrogen peroxide are present in an approximately stoichiometric amount as calculated to produce carbon dioxide and water.

16. The monopropellant fuel of claim 15 wherein the water is present in an amount of about 30% to about 50% of the total weight of the fuel.

17. The monopropellant fuel of claim 15 wherein the hydrocarbon fuel is present in an amount of from about 8% to about 12% of the total weight of the fuel.

18. The monopropellant fuel of claim 15 wherein the hydrocarbon fuel and the hydrogen peroxide deviate less than about 10% by weight of amount calculated to provide the stoichiometric by-products of carbon dioxide and water.

19. The monopropellant fuel of claim 15 having a fuel energy density more than 1100 BTUs per pound.

20. The monopropellant fuel of claim 15 wherein the hydrocarbon fuel is a 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.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0032] 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:

9H.sub.2O.sub.2+C.sub.3H.sub.7OH.fwdarw.3CO.sub.2+13H.sub.2O

[0033] 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.

[0034] 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.

[0035] 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).

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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).

Example 1Preparation of MFIII Monopropellant Fuel

[0041] 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.

Example 2Energy Density-Flame Temperature of Fuel

[0042] 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 (MFI42.8 wt %; MFII41.3 wt %; MFIII36.6 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.

TABLE-US-00001 TABLE 1 Energy Content Comparison Three Isopropanol Fuel Formulations Fuel Parameter MFI MFII MFIII Energy Density (Btu/#) 1104 1161 1349 Energy Density (Btu/gal) 10,675 11,271 13,255 Flame Temp. (? F.) 2360 2470 2823 Specific Gravity* 1.15-1.16 1.163-1.164 1.177-1.18 *Varying temperature can cause variation in specific gravity

[0043] 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.

Example 3Exhaust Gas Analysis of MFI

[0044] 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.

TABLE-US-00002 TABLE 2 MFI Gas Analysis - Weight Percent Carbon Excess Carbon Water* Dioxide Oxygen Monoxide Test 3 78.56 20.08 1.19 0.17 Test 4 78.24 19.78 1.93 0.05 Test 5 78.30 19.82 1.85 0.03 Test 6 78.93 20.34 0.64 0.09 Theoretical 79.36 20.64 0.00 0.00 *Water amounts were calculated on the basis of the amounts of other gases.

[0045] 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.

Example 4Bonfire Test

[0046] 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.

Example 5Single Package Ignition Test

[0047] 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.

Example 6Bullet Impact Tests

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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.

[0054] 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.

[0055] 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.