Method and apparatus for the preparation and usage of a cryogenic propellant or explosive system

Abstract

The inventions describes a method and apparatus for remotely forming a mixture of liquid oxygen (“LOX”) and liquid methane (“LNG”), with the mixture commonly referred to as MOX, such that the LOX and LNG never contact each other until inside the container in which the mixture will be used. The method disallows contact between the LOX and the LNG in order to prevent the premature or inadvertent explosive combustion that can occur in a variety of ways. The method provides a way to deactivate the MOX mixture, even after the MOX mixture has been formed. The invention also contemplates various apparatuses that will allow the method to be practiced.

Description

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 60/252,349, entitled “A Method and Apparatus for the Preparation and Usage of a Cryogenic Propellant or Explosive System”, filed Nov. 20, 2000, the entirety of which is incorporated by reference herein.

FIELD OF THE INVENTION

[0002] The present invention relates generally to a method and means for remotely forming a combustible liquid in a container using non-explosive components. The invention is applicable to the rocket propulsion, excavation, and munitions industries.

BACKGROUND OF THE INVENTION

[0003] There have been several attempts to develop a cryogenic rocket propulsion system and a rock blasting system using a mixture of liquid oxygen (“LOX”) and liquid methane (“LNG”). LOX and LNG can be mixed together to form a cryogenic combustible liquid sometimes referred to as MOX (an acronym derived from methane-oxygen). When mixed, LOX and LNG form a fully miscible and homogeneous fluid over the full range of mixtures from pure LOX to pure LNG. For example, the stoichiometric mixture, CH4+2O2, is in the liquid phase between about 63 degrees Kelvin, below which methane starts to freeze out, and 92 degrees Kelvin, above which oxygen begins to boil off. MOX will detonate at a range of mixtures around the stoichiometric ratio and will deflagrate for mixtures that are very fuel rich or oxygen rich. Fuel rich mixtures, those mixtures which have more methane than the stoichiometric ratio, are typically of interest in the rocket propulsion industry while both detonating and deflagrating mixtures or oxygen rich, those mixtures which have more oxygen that called for in the stoichiometric ratio, are of interest for the rock blasting, excavation, and explosive manufacturing industries.

[0004] British Patent Number 855,200 and U.S. Pat. No. 2,939,778 describe methods for preparing a LOX/LNG or MOX mixture that can be safely prepared, stored and handled in a large factory environment. These methods are too complicated and not practical for use in the field since the MOX mixtures must be transported, stored and handled as explosive materials between the factory where the mixture is prepared and the field where the mixture is required. Colgate describes the use of cryogenic hydrocarbon mixtures, including a LOX/LNG or MOX mixture, as an explosive blasting system in U.S. Pat. No. 4,074,629 but does not disclose how such mixtures would be formed safely and practically. Flynn describes a method for making and storing a cryogenic monopropellant based on the LOX/LNG or MOX system in U.S. Pat. No. 5,804,760. Flynn's invention is a significant improvement over the prior art but it is still a method of preparing a LOX/LNG mixture that is too complicated and not practical for use in field applications such as, for example, small rocket experiments or commercial blasting operations. British Patent Number 855,200; and U.S. Pat. Nos. 2,939,778; 4,074,629; and 5,804,760 are incorporated by reference in their entireties herein.

[0005] As discussed above, the principal problem in developing a safe and economical system for preparing and using MOX in some field applications is the requirement to form MOX prior to transporting and loading it into the container in which it will ultimately be used. Once formed, MOX is subject to initiation, for example, by mechanical shock or electrical spark. This means that MOX must be classified as an explosive material and is therefore subject to many costly regulations for transportation and storage. MOX is also known to have an elevated sensitivity to mechanical import for mixtures in the approximate range of 0.20 to 0.27 mole fraction of LNG.

[0006] The sensitivity of MOX to mechanical shock and electrical spark also means that MOX has the potential for unintentional initiation when it is being pumped or otherwise transported through a conveyance system of piping and valves such as might be used in rocket propulsion system or a system for charging blast holes.

[0007] It is further noted that MOX mixtures can be very sensitive to mechanical or electrical spark initiation when there is a gaseous mixture of oxygen and methane formed above the liquid phase. This phenomenon can occur when the mixture is near or at its boiling point, i.e., when a valve in a fill-line is not properly pre-chilled thereby allowing a small amount of MOX vapor to form. Opening or closing a valve under such conditions can cause the vapor to flash-bum which can then cause the MOX to combust or, if the mixture is near stoichiometric proportions, to detonate. MOX is known to have an extremely small critical diameter and thus a detonation, once initiated, can propagate through the parts of the system even if only connected by small amounts of MOX. Because of the extremely small critical diameter of detonable MOX mixtures, a practical detonation arrester device has never been successfully developed. These and other problems are addressed by the present invention as will be described and illustrated in the following sections.

SUMMARY OF THE INVENTION

[0008] A fuel tank of a rocket motor or a blast hole cartridge in a blast hole are examples of field applications requiring a container for a mixture of LOX/LNG (hereafter referred to as MOX). In one embodiment of the present invention, the component materials required to prepare MOX in the field are separately transported, separately stored, and separately handled at the field site. Further, once MOX is required for its intended application, it is formed from a remote and safe location in the container required by the application. MOX is generally not required to pass through valves or other devices that could cause premature initiation by, for example, mechanical shock or electrical spark, except under remote control. For example, MOX would be formed in a fuel tank of a rocket in orbit or in a cartridge in a blast hole.

[0009] LOX and/or LNG can be transported to the field site in their liquid phase. Alternately, the oxygen and/or the methane required to form LOX or LNG can be transported to the field site in the gaseous phase. If brought to the field site in the gaseous phase, either or both the oxygen and methane are normally liquefied at the field site by using liquid nitrogen (“LN2”) to cool the gas to its liquid phase. This is possible because liquid nitrogen has a lower freezing point than either liquid oxygen or liquid methane. The liquid nitrogen could also be used to pre-chill all piping, valves and other components required to transfer LOX and LNG to the remote container and to pre-chill the container itself, if necessary. The means to utilize LN2 to form either LOX or LNG from their respective gaseous phases are described, for example, in U.S. Pat. No. 5,804,760.

[0010] By using knowledge of the various known properties of LOX, LNG and MOX mixtures, various embodiments of the present invention also includes methods to remotely and safely control (1) the composition of the MOX mixtures, (2) the holding time for stable MOX mixtures and (3) the non-explosive termination of the MOX mixture. The present invention further includes means for remotely and safely forming a controllable mixture of MOX in a container at the final location of its desired application.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] FIG. 1 shows a schematic of a prior art apparatus for using liquid nitrogen to liquify gaseous oxygen or gaseous methane;

[0012] FIG. 2 shows a phase diagram illustrating possible mixture paths for forming an oxygen rich detonable composition of MOX;

[0013] FIG. 3 shows a phase diagram illustrating possible mixture paths for forming a fuel rich deflagrating composition of MOX;

[0014] FIG. 4 shows a schematic of a field site layout for remotely mixing MOX from non-explosive components;

[0015] FIG. 5 shows a schematic side view of a possible container for the remote mixing of MOX;

[0016] FIG. 6 shows a schematic diagram for a simple system for remotely forming MOX in a container;

[0017] FIG. 7 shows a schematic diagram for a system for remotely forming MOX in a container which allows for purging using gaseous nitrogen and pre-chilling using LN2;

[0018] FIG. 8 shows a schematic diagram for a system for remotely forming MOX in a container which allows for purging and pre-chilling using LOX and LNG; and

[0019] FIG. 9 shows a schematic side view of a possible container for the remote mixing of MOX which has a means for aborting the mixture.

DETAILED DESCRIPTION OF THE DRAWINGS

[0020] Typical Embodiment of the Method

[0021] In the following description, a typical embodiment of the method is described for forming MOX remotely in a container such as a fuel tank of a rocket or a cartridge in a blast hole. These are examples of the final application embodied in the present invention. However, it should be noted that the present invention can be used in any number of containers or applications. The other containers or applications appropriate for use with the present invention will be apparent to one of skill in the art.

[0022] The following non-explosive components are transported to the field site where they maybe stored until required for the final application:

[0023] gaseous or liquid oxygen

[0024] gaseous or liquid methane

[0025] if necessary, liquid nitrogen

[0026] if necessary, an apparatus to form LOX and/or LNG from their respective gaseous phases

[0027] a container or containers that are part of the final application

[0028] a means of electrical spark or pyrotechnic or other suitable initiation for MOX

[0029] various piping, control valves, check valves, flow regulators, cryogenic dewars, and instrumentation and other non-explosive components required to set up a system to remotely mix LOX and LNG in the container

[0030] Prior to the final application, the gaseous oxygen and/or gaseous methane may be cooled to their liquid phase by means of an apparatus such as that shown in FIG. 1 and stored in separate cryogenic dewars. The embodiment of FIG. 1 would form LOX or LNG from their gaseous phases by using liquid nitrogen. It is also possible to form LNG by using LOX to liquify gaseous methane. Even though the LOX is totally separate from the methane, there exists a possibility that, for example, a defective or worn component in the system can lead to a breach in the wall of separation thus allowing oxygen and methane to come in contact even in minute amounts, with the potential to form an explosive mixture. It is for this reason that the use of LN2 to form LNG from gaseous methane is most preferred. LN2 is an inert substance and even if a breach, as described above, occurred, no explosive mixture would be formed.

[0031] The components to remotely form MOX are now all stored and available at the field site for use in the final application. The container is positioned in its final location which is the location where MOX is to be mixed and initiated. The means of initiation of MOX may be installed in the container (for example, if used in a cartridge for blasting) or the means of initiation may be elsewhere (for example, if used in a fuel tank that feeds MOX to a rocket motor). The means of conveying gaseous nitrogen, liquid nitrogen (“LN2”), LOX and LNG to the container, if necessary, are also installed. The means of conveying or transferring the various components to the container are comprised of various fill lines, valves and flow regulators. Any instrumentation desired for monitoring the process are also installed. At this point the system is in place for the final step—to remotely form and utilize an explosive mixture of MOX.

[0032] The means of forming MOX remotely in the container are described below with reference to FIGS. 2 and 3. FIGS. 2 and 3 show the path of the composition of the mixture in the container on a gas-liquid-solid phase diagram for MOX. Two possible paths are shown as examples. FIG. 2 depicts a loading path that might be used for charging blast holes with a detonable composition of MOX. FIG. 3 depicts a loading path that might be used for charging a rocket motor with a fuel rich deflagrating composition of MOX. It will be noted by one of skill in the art that the loading paths will vary, dependent on the intended use and desired mixture composition of the MOX mixture.

[0033] If desired, gaseous nitrogen may be flowed through the charging system and, if desired, the container in order to purge any air in the charging system and, if desired, the container. Such a purge will remove any risk of premature or inadvertent detonation. If desired, LN2 maybe flowed through the charging system and, if desired, the container to chill the components of the charging system and, if desired, the container in order to minimize the temperature rise of the LOX and LNG when they are conveyed from their respective long term storage dewars to the container.

[0034] Referring to either FIG. 2 or 3, first, the desired amount of LNG is introduced into the container at a temperature just above its freezing point, approximately 90 degrees Kelvin (mole fraction of methane equal to 1). Thereafter, LOX is added to the LNG in the container at a temperature that is low enough to maintain the MOX mixture as a liquid near its local freezing point, approximately 63 degrees Kelvin, when the mixture composition is within the range required by its application. As the mole fraction of the LNG is decreased by the addition of LOX towards the mixture composition range, dependent on its application, a portion of the liquid methane may temporarily freeze out as shown, for example, by one of the possible paths in the phase diagrams of FIGS. 2 and 3. As stated above, if a fuel rich composition is desired, the composition will have more methane in the composition than that required by the stoichiometric ratio. If an oxygen rich composition is desired, the composition will have more oxygen in the composition than that required by the stoichiometric ratio. For example, if a fuel rich mixture is required by the application, the mixture could be 2CH4+2O2.

[0035] Once the desired MOX mixture composition is achieved, the mixture is ready to be initiated for its desired final application. It is observed that loading the LNG first means that the MOX mixture never reaches the range of enhanced impact sensitivity (between the approximate range of about 0.20 to 0.27 mole fraction of LNG per mole fraction of LOX) except if a very oxygen rich final mixture were desired.

[0036] From known data on the temperature and other characteristics of LOX, LNG, LN2 and MOX, instrumentation such as thermocouples, flow meters and weighing devices can be used to monitor the progress of the mixing the LOX and LNG in the container and follow the path of the mixture on a MOX phase diagram such as shown in FIGS. 2 and 3. Alternately, the MOX conditions in the container can be determined by reference to prior, off-site testing and measurement of the flow of components to a container via a conveyance system identical to the container and conveyance system to be used in the final application.

[0037] When the container is suitably insulated, the mixture can be held for a desired length of time, dictated by the quality of the insulation of the container. As the mixture in the container warms, the composition remains relatively constant until the boiling temperature, approximately 92 degrees Kelvin, is approached. As the boiling temperature is approached, oxygen will boil off preferentially, since the oxygen has a lower boiling point of approximately 90 degrees Kelvin as compared to the methane which has a boiling point of approximately 111 degrees Kelvin, to the methane and the composition of the MOX mixture will begin to change towards a higher mole fraction of methane as depicted in FIGS. 2 and 3.

[0038] When a MOX mixture is totally in the liquid phase, the measured temperature (for example using thermocouples) can not be used alone to determine mixture composition. Once the mixture begins to boil, then a temperature sensor or sensors immersed in the liquid phase can be used to uniquely determine mixture composition. Thus, it would be preferred to have a means of determining the onset of boiling so that simple temperature sensors would be able to monitor mixture composition. This could be accomplished by any number of means, including but not limited to, acoustic sensors which would measure the sounds associated with the boiling of the MOX mixture, pressure sensors which would measure the relative pressure throughout the addition of the liquid oxygen, visual sensors which would visually detect the color of the liquid and the relative miscibility of the liquids, or any combination of these. In addition, a feedback loop utilizing a processor is contemplated wherein the sensors would provide feedback to the processor, which could consult preset reference numerals and change the control conditions (such as temperature, mole fraction or ratio or resident time) automatically or which could prompt an operator for additional input before changing the control conditions.

[0039] The desired MOX mixture can be initiated or otherwise utilized at any time that the mixture composition remains in the range acceptable to the application. The container is provided with a means of venting vapors formed in the event that the MOX mixture approaches its local boiling temperature.

[0040] If it is desired to non-explosively terminate the MOX mixture rapidly, the temperature of the mixture can be raised by any of a number of means such that the mixture boils controllably and the resultant vapors are vented, for example to the atmosphere, until no liquid phase remains. The oxygen would, as explained above, preferentially boil away first and, as the remaining liquid is heated, the methane will return to its gaseous state. Both molecular oxygen, in a gaseous state, and methane, in a gaseous state, are relatively harmless gases that can be vented to the atmosphere. As an example, a metal object at approximately atmospheric temperature can be introduced slowly into the mixture to absorb heat energy and cause the temperature of the mixture to rise rapidly but controllably until all the liquid is boiled off and the resultant vapors vented. For example, a metal object at an atmospheric temperature of 50 degrees Celsius is at approximately 323 degrees Kelvin, or approximately 250 degrees higher than the temperature of the liquid. Such an insertion will cause the temperature of the mixture to rise rapidly, given the temperature differential between the metal object and the temperature of the mixture.

[0041] Overview of the Means

[0042] The apparatuses necessary for the present invention can include but are not limited to:

[0043] a vented container for the final application in which the MOX is to be mixed

[0044] one or more cryogenic dewars for transportation and long term storage of LOX at the site of the final application

[0045] one or more cryogenic dewars for transportation and long term storage of LNG at the site of the final application

[0046] pipe, valves, regulators and other components necessary to form a system of conveyance of LOX and LNG from their storage dewars to the container

[0047] a means for determining the amounts of LOX and LNG introduced into the container a means of remote initiation for the MOX mixture

[0048] The following additional apparatuses may be desirable to facilitate implementation of the present invention:

[0049] one or more cryogenic dewars for transportation and long term storage of LN2 at the site of the final application

[0050] instrumentation for monitoring the amounts and conditions of the LOX and LNG as well as the MOX formed in the container

[0051] an apparatus such as shown for example in FIG. 1 for forming LOX and LNG from their gaseous phases

[0052] one or more bottles of gaseous nitrogen for purging air from the LOX and LNG conveyance systems

[0053] a means of thermal insulation for the container

[0054] a means of non-explosively terminating the MOX mixture in the container

[0055] Typical Embodiment of the Means

[0056] An example of a simple embodiment of a field system for applying the method of the present invention is shown in FIG. 4. Here, all the necessary components and additional optional components required to assemble a system to remotely prepare a mixture of MOX in a container are gathered behind a protective structure. The protective structure is capable of protecting personnel, component materials and other valuable property from an accidental or intentional explosion of a MOX mixture that is prepared in the remote container. All of the components described above are non-explosive materials and are not subject to explosive materials transportation, storage or handling regulations. The container used in the final application is placed at a safe distance from the protective structure. The fill lines, electrical, signal, pre-chill, purge and other control lines that connect the control area to the remote application area are installed. Once this is accomplished, all further operations are conducted from behind the protective structure. If necessary, the means to refrigerate gaseous oxygen and methane to LOX and LNG respectively are stored behind the protective structure. All of the apparatus in front of the protective structure is considered expendable in the event that the MOX in the container accidentally or intentionally initiates. Another general feature of the present invention is illustrated in FIG. 4. One should note that the oxygen or LOX is always kept separate from the methane or LNG, except in the container used in the final application. This physical separation guarantees that an explosive mixture of MOX can never be formed except in the container where an unintentional initiation can never cause unintended damage to personnel or valuable components.

[0057] An example of a container for remote mixing of MOX is shown in FIG. 5. The container includes but is not limited to fill ports for the LOX and LNG and a vent for releasing vapors that form above the MOX in the event the MOX begins to boil as a result of standing for a long period of time or as a result of intentionally heating the MOX to non-explosively eliminate the explosive MOX mixture. The vent should be located at or near the top of the container or such that the vent is higher than the level of the MOX mixture. It is preferred to locate the fill lines at the top of the container to enhance mixing of the LOX with the LNG. The LNG is loaded into the container first.

[0058] The heavier LOX (density II 3 4 kg/m′) will fall through the lighter LNG (density 425 kg/m3) and tend to mix more readily by this action.

[0059] An example of a schematic for a simple system for mixing MOX remotely is shown in FIG. 6. The system shown assumes that both LOX and LNG have been created previously and both are readily available from storage dewars. It is assumed that all cryogenic storage dewars include pressure relief valves as part of their structure, which are not shown in FIG. 6. In this simple system, a dewar containing LNG is connected to its fill line through a simple shut-off valve mounted on or near its dewar. The dewar is self-pressurizing for gas-pressure transfer of the liquid contents through the fill line and into the container. A second dewar containing LOX is also connected to its fill line through a simple shut-off valve mounted on or near on its dewar and is also self-pressurizing for gas-pressure transfer of the liquid contents through the fill line and into the container. An electrical spark discharge unit is shown as an example of a simple MOX initiation system. This system represents a very simple embodiment of the present invention that could be used, for example, to carry out uncomplicated blasting operations when the general MOX mixture characteristics are known from prior experience and measurement.

[0060] An example of a schematic of a more complex system for mixing MOX remotely is shown in FIG. 7. The system shown assumes that both LOX and LNG have been created previously and both are readily available from storage dewars. This system additionally depicts examples of how additional apparatuses can be connected to add air purge and component pre-chill functions for the remote MOX mixing operations. This system also shows a means to isolate the LOX dewar from any LOX back-but event that might be caused, for example, by hot debris created when the MOX is initiated. The system always includes pressure relief valves between any two flow regulating valves because of the possibility of trapped liquid between the two flow regulating valves. This system uses transfer dewars for both the LOX and LNG to provide a possible means for accurate determination of the mass and/or volume of LOX and LNG transferred to the container. Check valves are included to prevent any LOX from accidentally mixing with LNG during purge or pre-chill operations. It is again assumed that all cryogenic storage and transfer dewars include pressure relief valves as part of their structure, which are not shown in FIG. 7.

[0061] The general sequence of operations of this system is:

[0062] Nitrogen gas is flushed sequentially or simultaneously through the LOX, LNG and LN2 lines, the transfer dewars and the container to remove most of the air in the system.

[0063] LN2 is flushed sequentially or simultaneously through the LOX and LNG lines the transfer dewars and the container to pre-chill these components to minimize temperature change when the LOX and LNG are conveyed to the container. The lines can be chilled to a range of temperatures from around the freezing point of methane which is 63 degrees Kelvin to around the boiling point of oxygen which is approximately 93 degrees Kelvin. It is believed that an appropriate range of temperatures could be a range of temperatures from about 48 degrees Kelvin to approximately 100 degrees Kelvin.

[0064] The LNG transfer dewar is charged with the desired amount of LNG from its storage dewar.

[0065] The LOX transfer dewar is charged with the desired amount of LOX from its storage dewar.

[0066] The LNG from the LNG transfer dewar is conveyed to the container used in the final application.

[0067] Only after the LNG has been loaded into the container is the LOX from the LOX transfer dewar conveyed to the container where it is mixed to form the desired MOX mixture.

[0068] The initiation system is armed and the MOX is initiated when desired.

[0069] This system represents a practical embodiment of the present invention that could be used, for example, to carry out rocket launching experiments or controlled blasting operations when a relatively accurate knowledge of the MOX mixture composition and temperature just prior to initiation are required.

[0070] Other Embodiments

[0071] Based on the teachings of the present invention as discussed above, there maybe numerous alternate embodiments of the present invention that would be obvious to one skilled in the art.

[0072] The system shown schematically in FIG. 8 is an example of a simplification of the system shown in FIG. 7. In this system, the gaseous nitrogen and LN2 are eliminated and LOX and LNG are used to purge and pre-chill their respective lines. This system may be preferred when LOX and LNG are plentiful.

[0073] FIG. 1 illustrates a simple method for forming LNG from gaseous methane as disclosed in U.S. Pat. No. 5,804,760. Gaseous methane is contained in a commercially available or otherwise suitable bottle 1 which has a flow regulator 2 and a shut-off valve 3. A vessel 4 is filled with LN2 5. The methane flow path is via line 6, through a refrigeration coil 7 and into a LNG storage dewar 8. The methane from bottle 1 is allowed to flow through line 6 as a gas and into the portion of line 6 and coil 7 which are immersed in LN2 5 contained in the vessel 4. The LN2 5 can be maintained at or just below its boiling temperature of 77 K. Methane liquefies at 112 K and freezes at 89K. Therefore the flow rate of methane through refrigeration coil 7 must be regulated to allow the methane to liquify but not to freeze and therefore block the portion of line 6 and coil 7 which are immersed in LN2 5. This process is discussed in further detail in U.S. Pat. No. 5,804,760 which is incorporated by reference into the present invention.

[0074] FIG. 2 is a gas-liquid-solid phase diagram for MOX. The ordinate 11 of the diagram is the MOX mixture temperature in kelvins (K). The abscissa 12 of the diagram is the mole fraction of methane. The dotted line 13 represents the stoichiometric mixture, CH4+2O2. The range arrow 14 represents the range of methane mole fractions over which MOX can detonate and its products of combustion have an approximately constant work potential or heaving power. The range arrow 15 represents the range of methane mole fractions over which MOX has an enhanced impact sensitivity. The boiling point of MOX for various mole fractions of methane is shown by solid line 16 while the freezing point of MOX for various mole fractions of methane is shown by solid line 17. A possible loading path that might be used for charging blast holes with a detonable composition of MOX is illustrated by the dotted line 18. First, the desired amount of LNG is loaded into the MOX container at a point above its freezing temperature of 89 K as shown by point 19. Then, LOX is added at a temperature lower than 89K such that the mixture follows path 18. The mixture temperature maybe low enough for some methane to freeze out as would be the case during the portion 20 of the loading path 18 which shows a mixture temperature less than the freezing point. In general, it is desirable to maintain the mixture temperature always just above the freezing point curve 17. Once the desired amount of LOX has been added, the mixture is represented by point 21, which is shown here, for example, as slightly oxygen rich. At this point, the mixture may be initiated for its intended use or it may be allowed to sit in the container. If it sits in the container, the mixture temperature will begin to rise with little change in mixture along portion 22 of the path 18. As the mixture nears the boiling point, more oxygen will begin to boil off than methane and the mixture will begin to increase in methane mole fraction along portion 23 of the path 18. Once the methane mole fraction exceeds the limit of the desired application indicated by range arrow 14, it may be desirable to abort the application or add more LOX. It is noted that the example path illustrated never takes the mixture into the region 15 of enhanced impact sensitivity.

[0075] FIG. 3 is a the same gas-liquid-solid phase diagram for MOX as shown in FIG. 2. The ordinate 31 of the diagram is the MOX mixture temperature in kelvins (K). The abscissa 32 of the diagram is the mole fraction of methane. The dotted line 33 represents the stoichiometric mixture, CH4+2O2. The range arrow 34 represents the range of methane mole fractions over which MOX can detonate and its products of combustion have an approximately constant work potential or heaving power. The range arrow 35 represents the range of methane mole fractions over which MOX has an enhanced impact sensitivity. The boiling point of MOX for various mole fractions of methane is shown by solid line 36 while the freezing point of MOX for various mole fractions of methane is shown by solid line 37. A possible loading path that might be used for forming a fuel rich deflagrating composition of MOX is illustrated by the dotted line 38. First, the desired amount of LNG is loaded into the MOX container at a point above its freezing temperature of 89 K as shown by point 39. Then, LOX is added at a temperature lower than 89K such that the mixture follows path 38. The mixture temperature may be low enough for some methane to freeze out as would be the case during the portion 40 of the loading path 38 which shows a mixture temperature less than the freezing point. In general, it is desirable to maintain the mixture temperature always just above the freezing point curve 37. Once the desired amount of LOX has been added, the mixture is represented by point 41. At this point, the mixture may be initiated for its intended use or it may be allowed to sit in the container. If it sits in the container, the mixture temperature will begin to rise with little change in mixture along portion 42 of the path 38. As the mixture nears the boiling point, more oxygen will begin to boil off than methane and the mixture will begin to increase in methane mole fraction along portion 43 of the path 38. Once the methane mole fraction exceeds the limit of the desired mixture indicated by point 44, it may be desirable to abort the application or add more LOX. It is noted that the example path illustrated never takes the mixture into the region 35 of enhanced impact sensitivity or the region of detonable mixtures 34.

[0076] FIG. 4 shows a schematic of a possible field site layout for remotely mixing MOX from non-explosive components. The site is divided into a safe side 51 and a test side 52, separated by a blast and debris barrier 53. There is a work and storage area 54 on the safe side 51 where non-explosive materials, tools, instrumentation and other equipment are stored. LOX, LNG and, if used, LN2 may be stored in this work and storage area 54. LNG may be prepared from gaseous methane in area 54 as well. A container 55 for the final application is shown positioned at a safe distance from the barrier 53. The container 55 which includes a vent 64. A LOX dewar 56 and an LNG dewar 57 are shown on the safe side 51 of the barrier 53. The LOX dewar 56 is connected to the container 55 by a conveyance means 58 which maybe an insulated tubing for example. Similarly, the LNG dewar 57 is connected to the container 55 by a conveyance means 59 which may also be an insulated tubing for example. A firing box 60 is located on the safe side 51 and connected to the container 55 by a firing line 61 which may be, for example a pair of electrical wires. An example of a MOX initiation device 62 is shown inside the container 55 and connected to the firing line 61. Once the apparatuses on the test side 52 are installed and ready for operation, all personnel return to the safe side 51 for the subsequent operations of preparing the MOX mixture in the container 55 and initiating the MOX mixture for the final application. As discussed in the detailed descriptions of FIG. 2 and 3, LNG 57 is first loaded into the container 55 and then LOX 56 is added to form the final desired mixture of MOX 63. The MOX 63 is now ready to be initiated by operating the firing box 60. The MOX mixture maybe adjusted or aborted instead of being initiated as described in the sections on Typical Embodiments of the Method and Means and in the Detailed Descriptions of FIGS. 2, 3 and 9.

[0077] A schematic side view of a possible container for the remote mixing of MOX is illustrated in FIG. 5. The cartridge 71 consists of a bottom section which may have walls formed from one of any number of thermally insulating materials. The container is shown with a top section 72 which also contains provision for a LOX fill line 73, an LNG fill line 74, an LN2 purge and pre-chill line 75 and a vent 76. A MOX initiator device 77 is also shown entering the container 71 through the top section 72. The MOX mixture is formed within the container volume 78. The container may also be made as a single structure with fill holes, vent holes and other holes drilled through the structure wall.

[0078] FIG. 6 shows a schematic diagram for a near minimal number of components that could form a simple system for remotely forming MOX in a container. It is assumed that all cryogenic storage dewars include pressure relief valves as part of their structure, which are not shown. The system is comprised of a LOX dewar 81 connected to a conveyance means 82 which may be an insulated tubing for example, which is used to transfer LOX to a container 83. The flow of LOX is controlled by a shut-off valve 84. An LNG dewar 85 is also connected to a conveyance means 86 which may be an insulated tubing for example, which is used to transfer LNG to the container 83. The flow of LNG is controlled by a shut-off valve 87. The container 83 has a vent 88 to relieve any pressure buildup from boiling LNG or MOX mixtures. The system also includes a firing box 89 connected to the container 83 by a firing line 90 which may be, for example, a pair of electrical wires. A MOX initiation device 91 is shown inside the container 83 and connected to the firing line 90. Initially valves 84 and 87 are closed. The LNG valve 87 is opened to allow some LNG to flow down line 86 and into the container 83 in order to purge the line 86 of air and to pre-chill valve 87, line 86 and the container 83. Valve 87 is closed and the LNG in the line 86 and the container 83 is then allowed to boil away. Now, the LOX valve 84 is opened to allow some LOX to flow down line 82 and into the container 83 in order to purge the line 82 of air and to pre-chill valve 84, line 82 and, if necessary, the container 83. Now valve 84 is closed and the LOX in the line 82 and the container 83 is then allowed to boil away. Now the system is ready to be charged with the desired MOX mixture. The LNG valve 87 is again opened to allow the required amount of LNG to flow down line 86 and into the container 83. Valve 87 is closed. Now, the LOX valve 84 is opened to allow the desired amount of LOX to flow down line 82 and into the container 83 in order to form the desired mixture of MOX 92. Valves 84 and 87 are closed. Now the MOX 92 in the container 83 is ready to be initiated. The MOX 92 is initiated by activating the firing box 89 and initiating the MOX 92 with the initiation device 91.

[0079] FIG. 7 shows a schematic diagram for a preferred embodiment of a system for remotely forming MOX in a container which allows for purging using gaseous nitrogen and pre-chilling using LN2. The system is comprised of a LOX dewar 201 and its shut-off valve 202; an LNG dewar 203 and its shut-off valve 204; an LN2 dewar 205 and its shut-off valve 206. A bottle of nitrogen gas 207 with its flow regulator 208 and shut-off valve 209 is connected into the LN2 line. There is a LOX transfer dewar 210 and its shut-off valve 211, and an LNG transfer dewar 212 and its shut-off valve 213, which are both connected to a container 250 where the MOX mixture 251 is to be formed. It is assumed that all cryogenic storage and transfer dewars include pressure relief valves as part of their structure, which are not shown. There are additional shut-off valves 214, 216, 217, 219 and 220 which are used to control the purging, pre-chilling, venting and loading operations. Further, there are pressure relief valves 221, 223 and 224 which are positioned between any two adjacent shut-off valves so that trapped cryogenic fluids can -boil and automatically vent prior to over-pressuring the line. There are also check valves 225 and 226 to isolate the flow of either LOX into the LNG lines, or LNG into the LOX lines. These check valves prevent any explosive mixture from being formed in the system other than in the container 250. There is a portion 240 of the LOX line between the LOX transfer dewar 210 and the container 250 which is formed from a high nickel steel tubing which serves to help prevent oxygen combustion from traveling back up the oxygen line in the event that an oxygen fire is unintentionally started in the LOX line proximate to the container 250. The system also includes a firing box 230 connected to the container 250 by a firing line 231 which may be, for example a pair of electrical wires. A MOX initiation device 232 is shown inside the container 250 and connected to the firing line 231. The container 250 also has a vent line 235 to allow the vapors above the cryogenic fluids 251 in the container 250 to continuously vent to the atmosphere. To begin the process of forming a MOX mixture 251 in the container 250, all the shut-off valves in the system are initially closed. The following operations are performed:

[0080] Purge with Gaseous Nitrogen—Open valves 209, 214, 216 and 211 to purge the LOX lines to LOX transfer dewar 210 and the LOX lines to the container 250. Close valves 216 and 211. Open valves 219 and 213 to purge the LNG lines to LNG transfer dewar 212 and the LNG lines to the container 250. Close valves 219, 213, 209 and 214 so that all valves are closed again to complete the purging operations. The order of purging the lines is not important.

[0081] Pre-Chilling Transfer Dewars with LN2—Open valves 206, 214, 216 and 211 to pre-chill the LOX lines to LOX transfer dewar 210 and the LOX lines to the container 250. Close valves 216 and 211. Open valves 219 and 213 to pre-chill the LNG lines to LNG transfer dewar 212 and the LNG lines to the container 250. Close valves 219, 213, 214 and 206 so that all valves are closed again to complete the line, valve and transfer dewar pre-chilling operations. The order of pre-chilling the lines, valves and transfer dewars is not important.

[0082] Filling Transfer Dewars—Open valves 204 and 219 to fill LNG transfer dewar 212. When the desired amount of LNG has been transferred to the transfer dewar 212, close valves 204 and 219. Open valves 202 and 216 to fill LOX transfer dewar 210. When the desired amount of LOX has been transferred to the transfer dewar 210, close valves 202 and 216. All valves are now closed again to complete the transfer of LNG and LOX to their respective transfer dewars. The order of filling the transfer dewars is not important.

[0083] Preparing the MOX Mixture—Open valve 213 and transfer all the LNG in LNG transfer dewar 212 to the container 250. Close valve 213. Open valve 211 and transfer all the LOX in LOX transfer dewar 210 to the container 250. Close valve 211.

[0084] Initiating the MOX mixture 251 or aborting the MOX mixture 251 for the above system of FIG. 7 is described, for example, in the Detailed Descriptions of FIGS. 4 and 9.

[0085] The LOX and LNG lines may be formed from coaxial tubing such that the LOX or LNG flows through the inner portion of the coaxial tubing. LN2 used to pre-chill the LOX and LNG lines is flowed down the outer portion of the coaxial tubing.

[0086] FIG. 8 shows a schematic diagram for another embodiment of a system for remotely forming MOX in a container which allows for purging and pre-chilling using LOX and LNG. The system is comprised of a LOX dewar 501 and its shut-off valve 502 and an LNG dewar 511 and its shut-off valve 512. There is a LOX transfer dewar 506 and its shut-off valve 507, and an LNG transfer dewar 516 and its shut-off valve 517, which are both connected to a container 520 where the MOX mixture 521 is to be formed. It is assumed that all cryogenic storage and transfer dewars include pressure relief valves as part of their structure, which are not shown. There are additional shut-off valves 504, 505, 514 and 515 which are used to control the purging, pre-chilling, venting and loading operations. Further, there are pressure relief valves 503 and 513 which are positioned between any two adjacent shut-off valves so that trapped cryogenic fluids can boil and automatically vent prior to over-pressuring the line. The system also includes a firing box 530 connected to the container 520 by a firing line 531 which may be, for example a pair of electrical wires. A MOX initiation device 532 is shown inside the container 520 and connected to the firing line 531. The container 520 also has a vent line 522 to allow the vapors above the cryogenic fluids 521 in the container 520 to continuously vent to the atmosphere. To begin the process of forming a MOX mixture 521 in the container 520, all the shut-off valves in the system are initially closed. The following operations are performed:

[0087] Purge and Pre-chill—Open valves 502, 505 and 507 to purge the LOX lines to LOX transfer dewar 506 and the LOX lines to the container 520. Close valves 502, 505 and 507. Allow the LOX in the container 520 to boil away. Open valves 512, 515 and 517 to purge the LNG lines to LNG transfer dewar 516 and the LNG lines to the container 520. Close valves 512, 515 and 517. Allow the LNG in the container 520 to boil away. All valves are closed again to complete the purging and pre-chilling operations. The order of purging and pre-chilling the lines is not important although it is preferred to purge and pre-chill with LNG after purging and pre-chilling with LOX.

[0088] Filling Transfer Dewars—Open valves 512 and 515 to fill LNG transfer dewar 516. When the desired amount of LNG has been transferred to the transfer dewar 516, close valves 512 and 515. Open valves 502 and 505 to fill LOX transfer dewar 506. When the desired amount of LOX has been transferred to the transfer dewar 506, close valves 502 and 505. All valves are now closed again to complete the transfer of LNG and LOX to their respective transfer dewars. The order of filling the transfer dewars is not important.

[0089] Preparing the MOX Mixture—Open valve 517 and transfer all the LNG in LNG transfer dewar 516 to the container 520. Close valve 517. Open valve 507 and transfer all the LOX in LOX transfer dewar 506 to the container 520. Close valve 507.

[0090] Initiating the MOX mixture 521 or aborting the MOX mixture 521 for the above system of FIG. 8 is described, for example, in the detailed descriptions of FIGS. 4 and 9.

[0091] FIG. 9 shows a schematic side view of a possible container for the remote mixing of MOX which has a means for aborting the mixture. The cartridge 121 consists of a bottom section which may have walls formed from one of any number of thermally insulating materials. The container is shown with atop section 122 which also contains provision for a LOX fill line 123, an LNG fill line 124, a vent 125, and a means of aborting the mixture 126. A MOX initiator device 127 is also shown entering the container 121 through the top section 122. The MOX mixture is formed within the container volume 128. The means for aborting the mixture 126 is comprised of a metallic portion 129 normally not exposed to the inside volume 128 of the container 121, and a thermally insulating portion 130 normally exposed to the inside volume 128 of the container 121. When it is desired to terminate or abort the mixture of MOX, the means for aborting the mixture 126 is caused to fall into the mixture so that the mixture is exposed to the surfaces of the metallic portion 129. The metallic portion 129 is at or near ambient atmospheric temperature and has sufficient heat capacity such that it will absorb sufficient heat from the MOX so as to cause the MOX to boil off more rapidly than it would by heat conduction through the container walls 121 and the top 122.

Claims

1. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

transferring, through transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature; and,

transferring, through transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature.

2. The method according to claim 1 comprising the additional step of transferring the liquid oxygen to a first intermediate container prior to transfer to the container.

3. The method according to claim 1 comprising the additional step of transferring the liquid methane to a second intermediate container prior to transfer of the container.

4. The method according to claim 1 comprising the additional step of purging oxygen from the container and transfer equipment by transferring gaseous nitrogen to the container.

5. The method according to claim 1 comprising the additional step of forming liquid methane by reducing the temperature of an amount of gaseous methane.

6. The method according to claim 5 wherein the reduction in temperature of the gaseous methane is achieved by cooling the gaseous methane through the use of nitrogen.

7. The method according to claim 1 comprising the additional step of pre-chilling the container and transfer equipment by transferring liquid nitrogen to the container.

8. The method according to claim 2 comprising the additional step of pre-chilling the intermediate container by transferring liquid nitrogen to the intermediate container.

9. The method according to claim 3 comprising the additional step of pre-chilling the intermediate container by transferring liquid nitrogen to the intermediate container.

10. The method according to claim 1 wherein the methane-oxygen mixture can be boiled away without initiating the mixture.

11. The method according to claim 1 wherein the methane-oxygen mixture can be boiled away through the use of a heat conducting device without initiating the mixture.

12. The method according to claim 1 wherein the methane-oxygen mixture can be evaporated without initiating the mixture.

13. The method according to claim 1 wherein the transfer equipment is comprised of pipes, valves, and safety devices sufficient to transfer liquids from the container to the blast container.

14. The method according to claim 1 wherein the transfer equipment for the liquid oxygen is separate from the transfer equipment for the liquid methane.

15. The method according to claim 1 wherein the methane-oxygen mixture is fuel rich.

16. The method according to claim 1 wherein the methane-oxygen mixture is oxygen rich.

17. The method according to claim 1 wherein the container for the methane-oxygen mixture is a fuel tank and the methane-oxygen mixture is transferred from the fuel tank to a motor before initiation.

18. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

transferring, through transfer means, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above it freezing temperature; and,

transferring, through transfer means, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature.

19. A method of forming a mixture of liquid oxygen and liquid methane at a field site in a blast container such that the liquid oxygen and the liquid methane do not contact each other until inside the blast container, comprising the steps of:

transporting, in a first container, liquid oxygen to the field site;

transporting, in a second container, liquid methane to the field site;

transferring, through transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature; and,

transferring, through transfer equipment, a desired amount liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature.

20. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

transferring, through transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature;

transferring, through transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature; and,

detonating the methane-oxygen mixture.

21. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

transferring, through transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature;

transferring, through transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature; and,

deflagrating the methane-oxygen mixture.

22. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

transferring, through transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature; and,

transferring, through transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature; and,

evaporating the methane-oxygen mixture without initiating the mixture.

23. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

purging the container and transfer equipment through the use of gaseous nitrogen;

pre-chilling the container and transfer equipment through the use of liquid nitrogen;

transferring, through the transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature; and,

transferring, through the transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature.

24. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

purging the container and transfer equipment through the use of gaseous nitrogen;

pre-chilling the container and transfer equipment through the use of liquid nitrogen;

transferring, through the transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature;

transferring, through the transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature; and,

detonating the methane-oxygen mixture.

25. A method of forming a mixture of liquid oxygen and liquid methane in a container such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

purging the container and transfer equipment through the use of gaseous nitrogen;

pre-chilling the container and transfer equipment through the use of liquid nitrogen;

transferring, through the transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature; and,

transferring, through the transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature; and,

deflagrating the mixture.

26. A method of forming a mixture of liquid oxygen and liquid methane in a contained such that the liquid oxygen and liquid methane do not contact each other until inside the container, comprising the steps of:

purging the container and transfer equipment through the use of gaseous nitrogen;

pre-chilling the container and transfer equipment through the use of liquid nitrogen;

transferring, through the transfer equipment, a desired amount of liquid methane to the container under temperature conditions that keep the liquid methane below its boiling temperature but generally above its freezing temperature;

transferring, through the transfer equipment, a desired amount of liquid oxygen to the container to form a combustible methane-oxygen mixture under temperature conditions that keep the methane-oxygen mixture below its local boiling temperature and above its local freezing temperature; and,

evaporating the methane-oxygen mixture without initiating the mixture.

27. An apparatus for forming a mixture of liquid oxygen and liquid methane in a blast container in which the liquid oxygen and the liquid methane never contact each other until inside the blast container, comprising:

a first container of liquid oxygen;

a second container of liquid methane;

transfer equipment to connect the first and second containers to the blast container, and,

a firing device.

28. The apparatus according to claim 27 wherein the blast container has a vent.

29. The apparatus according to claim 27 wherein the first and second containers are located apart from each other.

30. The apparatus according to claim 27 further comprising:

a first intermediate storage container for the liquid oxygen; and, a second intermediate storage container for the liquid methane.

31. The apparatus according to claim 27 further comprising an apparatus for forming liquid methane from gaseous methane.

32. The apparatus according to claim 27 further comprising a heat conducting device used to heat the mixture of liquid methane and liquid oxygen to its boiling point.

33. The apparatus according to claim 27 further comprising a container of gaseous nitrogen, said container being connected to the transfer equipment and blast container to purge any air from the transfer equipment and blast container.

34. The apparatus according to claim 33 further comprising a container of gaseous nitrogen, said container being connected to the transfer equipment, first and second intermediate storage containers, and the blast container to purge any air from the transfer equipment, first and second intermediate storage containers, and the blast container.

35. The apparatus according to claim 27 further comprising a container of liquid nitrogen connected to the transfer equipment and the blast container to pre-chill the transfer equipment and blast container.

36. The apparatus according to claim 35 further comprising a container of liquid nitrogen connected to the transfer equipment, first and second intermediate storage containers, and the blast container to pre-chill the transfer equipment, first and second intermediate storage containers, and the blast container.

37. An apparatus for forming a mixture of liquid oxygen and liquid methane in a means for holding in which the liquid oxygen and liquid methane do not contact each other until inside the means for holding, comprising:

a first means for containing liquid oxygen;

a second means for containing liquid methane;

means for transferring the liquid oxygen and liquid methane from the first and second means for containing to the means for holding; and,

means for combusting the mixture.

38. An apparatus for forming a mixture of liquid oxygen and liquid methane in a blast container in which the liquid oxygen and the liquid methane do not contact each other until inside the blast container, comprising:

a first container of liquid oxygen;

a second container of liquid methane; and,

transfer equipment to connect the first and second containers to the blast container.

39. An apparatus for forming a mixture of liquid oxygen and liquid methane in a blast container in which the liquid oxygen and the liquid methane never contact each other until inside the blast container, comprising:

a first container of liquid oxygen;

a first intermediate container for the liquid oxygen;

a second container of liquid methane;

a second intermediate container for the liquid methane; transfer equipment to connect the first and second containers and the first and second intermediate containers;

transfer equipment to connect the first and second intermediate containers to the blast container; and,

a firing device.