Atomizing Method And Apparatus

Abstract

A method and apparatus for finely atomizing a fluid such as oil or the like includes producing an emulsion of the oil with a secondary fluid pressurizing and heating the emulsion to a level below the vaporizing point of the secondary fluid and the constituents of the primary fluid, and releasing the resulting heated and pressurized emulsion to a lower pressure to vaporize the secondary fluid and the light ends of the primary fluid thereby subdividing the primary fluid or all into fine or small drops. When used to atomize fuel oils for combustions, the subdivided oil may be premixed with air or a mixture of air, CO.sub.2 and other gases permitting a substantial reduction in the emission of particulate matter and noxious products.

Description

BACKGROUND OF THE INVENTION

It is known that the addition of water in a fine dispersion throughout hydrocarbon liquid fuels, such as residual oil, prior to combustion aids the combustion process in that smoke or fine particles of carbonaceous materials normally emitted with the stack effluent in contemporary combustion systems are reduced both in size and quantity. All other factors being equal, such as furnace configuration, firing rate, and other system parameters, the addition of water has also been found to reduce certain pollutants formed in the combustion process such as the oxides of nitrogen. For example, water has been employed in gas turbines combustion systems as a carrier fluid in which corrosion inhibiting chemicals were dissolved and dispersed throughout the fuel by forming an oil/water emulsion. Generally, the degree of fineness or the size and dispersion of the water in the fuel influenced the effectiveness of the inhibiting chemicals in alleviating high temperature corrosion of the gas turbine components. Water is also used to depress peak combustion temperatures in gas turbines to alleviate the formation of oxides of nitrogen caused by the fixation of atmospheric nitrogen. In some instances, the water is premixed with the fuel and sufficiently well dispersed to reduce the carbonaceous particulate discharged by the combustor, and in other cases the water is introduced separately in which event there would be little effect on the production of such particulates.

In certain prior art apparatus, such as gas turbine combustion systems employing fuel-water emulsions, the energy of vaporization of the water is obtained directly from the combustion process by exposing the fuel droplets containing the water, and atomized by conventional means, to the heat of combustion in the furnace. In such cases the furnace heat penetrates the fuel droplets and vaporizes the water contained therein before the droplets are consumed in combustion thus shattering the fuel droplets into smaller droplets thereby aiding the combustion process. The secondary atomizing or shattering effect is adequate to obtain some benefit from a phase change (fluid to vapor) of the auxiliary secondary fluid or water. In some applications where fine atomization of a liquid is desired, combustion is not involved and, therefore, combustion heat is not available for atomization. Also, in combustion applications where ultra fine atomization and premixing of the atomized fuel with a gas other than combustion air or a mixture of a gas and combustion air to obtain a premixed fuel and gas mixture is desirable, the normally employed sources of auxiliary fluid vaporizing energy, such as the boiler furnace heat, as not suitable. An example of the latter type of combustion application is a staged combustion or partial oxidation process where it is desirable to premix the atomized, partially vaporized fuel with combustion air or oxygen and CO.sub.2 and other gases to optimize combustion and thereby minimize the formation of carbonaceous particulate and undesirable noxious gases, such as oxides of nitrogen. Some fuels, such as distillate oils, of which No. 2 fuel oil is an example, can be totally vaporized by heating the oil to a sufficiently high temperature prior to combustion. In the vaporized form, such fuels can easily be premixed with gases or other vapors. The addition of an auxiliary fluid, such as water, to create a secondary atomization is not essential, since premixing can be easily accomplished with vaporized fuels. However, heavier fuels, such as No. 6 fuel oil or residual fuels, cannot readily be vaporized prior to combustion simply by heating at the conditions prevailing in a conventional combustion system.

SUMMARY OF THE INVENTION

An object of the invention is to provide a method and apparatus for finely atomizing liquids by employing energy stored within the liquid in the form of an emulsion.

A further object of the invention is to finely atomize heavy fluids to facilitate certain chemical processes or subsequent physical processes such as mixing, suspending, dispersing with or in other fluids or gases.

A still further object of the invention is to atomize fluids which are normally not easily vaporized to such a fine particle or droplet size so as to facilitate thorough mixing with a premixing gas or carrier gases.

Another object of the invention is to provide a method of atomizing liquid fuels in a combustion process and apparatus which minimizes pollutant discharge.

A further object of the invention is to provide a combustion method and apparatus employing relatively heavy or residual liquid fuels wherein the level of pollutant discharge is relatively low.

Another object of the invention is to provide a combustion method and apparatus for more effectively atomizing relatively heavy or residual liquid fuels.

Yet a further object of the invention is to provide a combustion method and apparatus wherein secondary atomization of a fuel is accomplished essentially simultaneously with a pressure atomizing stage.

Another object of the invention is to provide a combustion method and apparatus which develops fuel droplets of a size small enough so as to reduce the combustion time of the droplet to less than the usual time associated with the residence time within a flame zone so that the flame can behave essentially as if the fuel were prevaporized thereby reducing the combustion volume of furnace.

Still another object of the invention is to provide a combustion method and apparatus for controlling the introduction of fuel into a combustion zone so as to stratify the incoming premixed fuel and carrier gas from the remainder of the gases in the furnace zone.

An additional object of the invention is to provide a combustion method and apparatus wherein atomization of the fuel is accomplished without a separate auxiliary atomizing fluid or gas such as steam or air.

A further object of the invention is to atomize a heavy liquid by producing a water emulsion wherein the amount of water employed for secondary atomization is minimized.

These and other objects and advantages of the invention will become more apparent from the detailed description thereof taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically illustrates an embodiment of the present invention;

FIG. 2 illustrates the operation of the apparatus shown in FIG. 1; and

FIG. 3 schematically illustrates an alternate embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 schematically illustrates a fuel supply system 10 for delivering a fuel and water emulsion to the burner nozzle 11 of a boiler furnace 12. In general, system 10 includes a fuel delivery circuit 14 and a water delivery circuit 15 coupled to an emulsifier 16 which is operative to produce a fine dispersion of water in the fuel. A high pressure pump 18 couples the emulsifier 16 to the nozzle 11 through a fuel heater 20.

The fuel delivery circuit 14 includes a delivery or fuel transfer pump 24 and a strainer 25 which are disposed in a conduit 27 which couples the emulsifier 16 to a fuel source 28. A heater (not shown) may be disposed in the line 27 or in the tank 28 to heat the fuel to a temperature of 150.degree. to 250.degree. F. In addition, a filter circuit 30 consisting of parallel connected filter elements 32 and 33 are connected in conduit 27 through three-way valves 35 and 36 so that the filter elements 32 or 33 may be alternately disconnected from the system 10 and changed without interrupting fuel flow to nozzle 11.

The water delivery circuit 15 includes a proportioning pump 40 and a strainer 42 disposed in conduit 44 which connects the emulsifier 16 to a water source 45. A check valve 46 is located between the emulsifier 16 and the proportioning pump 40 to prevent backflow into the pump 40 when the latter is not operating. The output of pump 40 is regulated to maintain the desired relationship between water and fuel oil flow by means of a flow meter 47 connected in fuel supply conduit 27 and a proportioning control circuit 50. The flow meter 47 may be of any well-known type which is operative to produce an electrical output signal functionally related to the flow of fluid in conduit 27. Proportioning control circuit 50 may also be of any well-known type which is operative to receive the signals from flow meter 47 and to provide a control signal functionally related to the flow rate in conduit 27 to a variable speed motor 51 or a pump displacement varying means in pump 40. When a variable speed motor is used the motor 51 varies in speed and hence the output of pump 40 will thus be functionally related to the flow of fuel in conduit 27. In this manner the delivery of water to the emulsifier 16 can be maintained at a predetermined flow volume relative to the delivery rate of fuel through conduit 27.

The emulsifier 16 may comprise any well-known device capable of producing an emulsion of oil and water. For example, the emulsifier 16 may comprise a dispersator which is a device having a generally cylindrical metallic tank 56 provided with a plurality of axially oriented baffles 57 which extend radially inward from the outer wall and which are spaced from the axis of chamber 56. The oil and water conduits 27 and 44 are both connected to one end of tank 56 and the emulsion delivery conduit 59 is connected to the outer. An impeller 60 is disposed in tank 56 and within the inner margins of the baffles 57 and is supported on the shaft 62 of a drive motor 63. The rotation of impeller 60 within the oil and water and the interaction with the baffles 57, blends the water and oil so as to obtain a fine dispersion of water and oil wherein the water droplets are uniformly distributed throughout the oil. An example of a dispersator which may be employed in the preferred embodiment of the invention is a motor driven mixer sold by the Gaulin Corporation. While a specific emulsifier has been shown and described, it will be appreciated that any well-known type of device, such as a homogenizing valve, may be employed.

The high pressure pump 18 is connected in a delivery conduit 59 which is connected at one end to dispersator tank 56 and at its other to the nozzle 11. A pressure accumulator 63 may be connected to conduit 59 for dampening pulsations from the high pressure pump 18. In addition, a check valve 64 may also be disposed in conduit 59 to prevent the back flow of fuel from the nozzle 11 and an on/off valve 65 may be disposed adjacent the heater 20 so that fuel delivery may be discontinued in the event of an emergency, a flame failure, or normal shutdown. A drain conduit 67 is connected at one end to conduit 59 between valve 65 and heater 20 and at its other end to the fuel source 28 and includes a normally closed dump valve 68 which may be opened to drain heater 20 and nozzle 11 when valve 65 is closed. In addition, a pressure relief valve 70 is connected to conduit 59 downstream of pump 18 and the drain conduit 67 to vent conduit 59 in the event of an over pressure in the line 59 to protect the conduit and the high pressure pump.

The nozzle 11 may be of any well-known type for delivering fuel to a furnace such as, for example, a variable aperture nozzle whose discharge opening varies in relation to fuel pressure. The boiler furnace 12 is schematically illustrated as comprising a furnace chamber 74 having an opening 75 in one end for receiving the nozzle 11. A hollow throat section 77 extends from opening 75 in surrounding relation to nozzle 11 and has an opening 76 in its remote end through which combustion supporting gases, symbolized by arrows 78, are introduced into the furnace chamber 74. For example, the gases 78 delivered through the opening 76 may comprise air or a mixture of air and stack gases, containing carbon dioxide. The recirculation of stack gases is desirable because when fuel is consumed in a carbon dioxide rich environment, the emission of carbonaceous particles is reduced by the combination of carbon dioxide from the stack gas and the carbon in the gaseous combustion products to produce carbon monoxide which is further oxidized downstream to carbon dioxide. In this manner, carbon, which would otherwise result in visible smoke emitting from the stack, is substantially oxidized to carbon dioxide. For a more complete description of a furnace in which stack gases are recirculated, reference is made to co-pending application Ser. No. 432,623 filed Jan. 11, 1974 and which is assigned to the assignee of the present invention.

The heater 20 may be any conventional heat exchanger which is capable of drawing heat from the boiler or furnace 12 and transferring the same to the fuel. Preferably, the heater 20 will be constructed and arranged such that the water/oil emulsion does not pass through the furnace 12. For example, heater 20 may include a heat exchanger 80 connected in conduit 59 and which is disposed externally of the furnace chamber 74. Heat from the furnace 12 may be transferred to the oil passing through heat exchanger 80 by means of a heat loop 82 disposed in heat exchange relation with the hot gases within the furnace chamber 74 and which is connected to heat exchanger 80.

While it will be appreciated that the invention may be employed with any liquid fuel, it has particular application to relatively heavy residual fuels, such as No. 6 fuel oil, which are not normally burned in conventional oil burners because they tend to produce high levels of pullutants such as unburned hydrocarbons, particulate matter and nitrogen oxides in the discharge gases. Typically, No. 6 residual oil contains 0.3 percent by weight nitrogen and otherwise may have the following analysis:

Flash Point, deg. F No flash point; (Pensky-Mardens Closed Cup) vapors support combustion Pour Point, deg. F 30 Water and Sediment, %v. 1.2 Viscosity at 100 Deg. F, SUS 2,522 API Gravity at 60 deg. F 8.6 Carbon, % 86.87 Hydrogen, % 9.80 Sulfur, % 2.40 Nitrogen, % 0.3 Ash, % 0.061 BTU, Gross per lb. 17,706 per gal. 148,842 BTU, Net per lb. 16,811 per gal. 146,414

In operation of the system illustrated in FIG. 1, the fuel will be drawn from source 28 and through strainer 25 by transfer pump 24 for delivery to the dispersator tank 56 through one of the filter cartridges 32 or 33, depending upon the setting of valves 35 and 36. It will be appreciated that the fuel pump 18 will include conventional means, not shown, for controlling the fuel flow rate in accordance with the combustion condition in furnace 12. One such means would be a variable speed drive on the pump 18. Simultaneous with the delivery of fuel, the proportioning pump 40 will draw water from tank 45 and through strainer 44 for delivery to dispersator tank 56. Flow meter 47 will sense the flow rate of oil through conduit 27 and will adjust the displacement of the proportioning pump 40 through control circuit 50 so that the proportion of oil and water delivered to the dispersator tank 56 will follow a pre-established schedule. In addition, the dispersator motor 63 will be energized to rotate impeller 60 and thereby produce a dispersion of water droplets within the oil. Typically, this dispersion may be as follows:

Range Mid Range Percent Diameter Diameter Percent Frequecny of Microns Microns By Volume Occurrence ______________________________________ 0 to 4 2 10.0 53 4 to 8 6 75.0 45 8 to 12 10 15.0 2 ______________________________________

Upon exiting the dispersator tank 56 through conduit 59, the emulsion is pressurized to a level from 2,500 to 10,000 psig but preferably in the order of 4,000 psig, by the high pressure pump 18. The emulsion is then passed through heat exchanger 85 where it is heated prior to delivery to the nozzle 11.

Thermodynamically, the fuel injection cycle is illustrated in FIG. 2. The high pressure pump 18 is adjusted to deliver fuel at the desired flow to the nozzle 11 at the pre-determined by design pressure for example, about 3,500 psig. The difference between the actual pump 18 discharge pressure and the pressure at the nozzle 11 represents the pressure losses in the conduit 59 and the heater 20, which would not normally exceed about 500 psi so that the pump discharge would not normally exceed about 4,000 psig. The predetermined pressure at the fuel nozzle is selected to avoid flashing of high pressure water into steam or the light hydrocarbon components of the fuel into vapor at any point in the system prior to the nozzle. This is accomplished by pressurizing well above the critical point of water. The high operating temperature limits of the emulsion are establihsed by the characteristics of the fluid being atomized and the dwell time in the system after heating. The volume of the hot portion of the system is held to a minimum to minimize the dwell time thereby avoiding deposits in the conduits. With No. 6 oil, temperatures of about 450.degree. to 700.degree.F were found to work well in that no appreciable quantity of deposits were found in the high pressure lines providing the pressure on the system is maintained at a sufficiently high level to prevent vaporization of the water and flashing of the lighter fuel components into vapor; i.e., a phase change from liquid to vapor or gas. It is known that if Benzene were used as a secondary fluid the temperature levels of 1,000.degree. to 1,200.degree. F would be possible if the Benzene did not contain contaminants in any appreciable quantity.

The lower temperature limit is established by the following considerations: The equipment available as previously indicated provides a mean water droplet distribution of from 2 to 4 microns. The amount of expansion of the water droplet in the oil subjected to a fixed pressure drop is determined by the initial pressure and the temperature of the emulsion for a given nozzle and furnace design. Pressure in most installations is obtained from shaft power such as an electric motor which is a high grade of energy whereas heat energy or temperature can frequently be obtained from exhaust or waste heat sources. It is, therefore, of economic advantage to minimize pressure rise and to operate with the emulsion at the highest possible temperature. That portion of the water which is converted to stem in passing through the nozzle, all other factors including pressure being equal, is a function of the emulsion temperature. The lower the temperature, the lower the conversion rate and the poorer the atomization efficiency. To obtain the desired results, the system is preferably designed so that the water in the emulsion will be present in sufficient quantity in each drop of fuel so as to expand and shatter the "oversize" drop to smaller acceptable drop sizes. While increasing the quantity of water in the emulsion is a substitute for higher temperatures and pressures, increased water will increase the vapor in the exhaust effluent increasing the cycle losses and reducing the overall combustion efficiency of the system.

A portion of residual oils consists of high molecular parafinic and aeromatic materials. These components go through a phase change above normal ambient temperatures causing a substantial change in the viscosity of residual fuel. Depending on the characteristics of the fuel the change occurs for typical residual or No. 6 fuel oil at temperatures above 400.degree. F. In some instances it was found that excellent atomization of the fuel could be obtained simply by pressurizing and heating without adding water providing the oil was heated above the transition temperature of the bulk of the long chain molecules or high molecular weight materials and pressurized sufficiently to avoid vaporization of the lighter constituents prior to passing through the atomization nozzle. The lower temperature limit is, therefore, established by:

1. The water distribution in the emulsion (size of water droplets and dispersion);

2. The quantity of water used;

3. The furnace pressure;

4. The characteristics of the nozzle;

5. The characteristics of the fuel (transition or phase change temperatures of the long chain molecules); and

6. The delivery pressure of the emulsion to the fuel nozzle. In practice, temperatures of 500.degree.F and above have been found to work well with 5 percent to 10 percent water and a furnace at atmospheric pressure, burning No. 6 residual oil having the analysis set forth above. It is believed that at temperatures in the order of 550.degree.F and above, a phase change from liquid to vapor occurs not only in the water but also in the lighter constituents of the fuel. This facilitates the atomization process and indicates that under appropriate temperature and pressure conditions, at least some atomization probably could be achieved without the use of water.

Atomization, in varying degrees, can be achieved over a range of parameters such as, for example, a temperature range of about 450.degree. - 700.degree. F, a pressure range of about 2,000-10,000 psi and a fuel to water ratio of about 5:1 to 25:1.

Again referring to FIG. 2, which is the partial enthalpy entropy diagram of water/steam, reference numeral 100 represents the pump discharge conditions shown at a pressure somewhat above the heater inlet conditions represented by reference numeral 101, to account for the pressure drop in the system between the pump 40 and the heater 20. Heat is added in the heater 20 essentially at constant pressure. The emulsion, containing the water, is then delivered to the nozzle at the selected temperature point represented by reference numeral 102 and the water-fuel mixture expands to the choking point of nozzle 11 and the water approaches the isentropic curve or constant entropy. Assuming a temperature of 700.degree. F and a pressure of 3,500 psi water, the pressure at the choking point in the nozzle would be approximately 2,000 psi with about 50 percent of the water converted to steam at the point represented by reference numeral 103. As the expanding oil droplets leave the nozzle 11, the action is not fully understood, however, it is believed that initially the process will be polytropic with some heat being rejected to the surroundings, dropping the temperature to a point represented by reference numeral 104 in FIG. 2. As the process continues and the steam continues to expand, heat will be absorbed from the surroundings in the case of a furnace until point 105 is reached wherein the process becomes essentially constant pressure at the partial pressure of the water vapor in the furnace, which is approximately 2 psia for the conditions previously described. The temperature of the vapor will continue to rise reaching the combustion temperature of the furnace 106. The bulk of the secondary atomizing is believed to occur between points 103 and 104 in FIG. 2 where a rapid expansion of the steam shatters the oil droplets.

An alternate embodiment of the invention is shown in FIG. 3 wherein the water and fuel emulsion is delivered to the fuel nozzles 130 of a gas turbine, not shown. While the gas turbine may include ten or more such nozzles, only three are illustrated for the sake of simplicity. The fuel and water delivery circuits 14 and 15, of FIG. 3, are substantially the same as that shown in FIG. 1. A heater 131 may be disposed in fuel delivery conduit 27 of the dispersator 16. The heater 131, which may be electrical, for example, elevates the temperature of the oil from fuel source 28 to approximately 150.degree. - 250.degree.F. In addition, a pressure relief valve 132 may be provided downstream of the heater 131 so that in the event of deposits or a failure, for example, the valve 132 will dump the oil flow into the return conduit 67. A pressure regulating valve 134 may also be provided downstream of the heater 131 to prevent excess pressure from damaging the dispersator 16 and the suction seals of the high pressure pump 18. Normally, fuel flows from the discharge of heater 132 through the pressure regulating valve 134 and the flow meter 47 to the dispersator 16. The emulsion is pressurized and metered by pump 18 and passes through heater 20 in the manner described with respect to the embodiment of FIG. 1, prior to passage to a flow divider 136 where the flow is divided equally between the combustion chamber fuel nozzles 130 of the gas turbine. The flow divider 136 may be any well-known type, such as the electric motor driven flow divider manufactured by General Electric Company for stationary gas turbines.

While the apparatus of FIGS. 1 and 3 have been discussed in relation to variable metering pumps and orifices, it will be appreciated that the system is also operative with fixed flows and settings.

It will be appreciated that the process and apparatus discussed with respect to FIGS. 1-3 facilitates the atomization of liquids, such as residual fuels, that cannot readily be vaporized for the purpose of accelerating chemical reactions or carrying such reactions closer to completion in a shorter time interval. The fluid is finely atomized to a sufficiently small droplet size so as to insure thorough mixing with a gas, or in the case of a combustion process, a mixture of air and carbon dioxide or simply air. In a combustion process such as a mixture of gases, vapor and finely atomized fuel will burn in a manner which is substantially equivalent to a completely vaporized fuel with combustion supporting gases. Such mixing of the atomized fuel with air and perhaps carbon dioxide as well as other products of hydrocarbon combustion and air may occur prior to the introduction of the mixture into the furnace zone. That portion of the fuel which is not vaporized is so finely atomized as to be easily suspended in the premixing gas. By providing relatively smaller droplets which are further subdivided by the water vaporization, the combustion reaction volume of the furnace is reduced by allowing the combustion process of finely divided fluid droplets to be so rapid that a flame can behave as if the fuel was prevaporized allowing a substantial reduction in furnace volume. Further, by reducing the droplet size, the size of long chain carbon particles formed in liquid reactions are minimized thus reducing the dwell time necessary for the resulting particles to be oxidized. In addition, the use of a water emulsion in the early stages of combustion promotes the further reduction of carbon particulate in the effluent from the combustion process by the well-known reaction of carbon and water which provides carbon monoxide and hydrogen. It will additionally be appreciated that the need for a separate auxiliary atomizing fluid such as air or steam as employed in conventional fluid atomizers is eliminated since the pressurized emulsion contains sufficient energy for atomization when the fluid is released from the nozzle 11.

While the atomization method and apparatus have been discussed in relation to a combustion process, it will be appreciated that it also has application to other processes wherein fine atomization of liquids is required. For example, in the production of manufactured gas from heavy liquid fuel, such as No. 6 oil, fuel, steam and oxygen are initially passed through a reactor which may contain a suitable catalyst to form CO, H.sub.2, CH.sub.4, other hydrocarbons, residual carbon particles and other gases. Such processes are accelerated and the quantity of carbon particulate produced is reduced if the oil is finely atomized in the manner described with respect to the combustion process depicted by FIGS. 1-3. Also, while the invention is described in relation to the use of an emulsion of water and oil for the purpose of atomizing the oil, it will be appreciated that many fluids could be substituted for water and oil to achieve these results.

While only a few embodiments of the invention have been illustrated and described, it is not intended to be limited thereby but only by the scope of the appended claims.

Claims

We claim:

1. The combination including first means for producing an emulsion of a liquid fuel and a second liquid, second means coupled to said first means for pressurizing and heating said liquid to an energy level such that said emulsion will atomize upon being discharged into a lower pressure atmosphere, third means defining a combustion zone, nozzle means disposed within said combustion zone and coupled to said second means for receiving said pressurized fluid and for releasing the same into the lower pressure atmosphere of said combustion zone whereby said emulsion will atomize, said second means including heating means and pressurizing means, said heating means including first heat exchange means external of said combustion zone for receiving said emulsion, and second heat exchange means exposed to heat generated in said combustion zone and for transferring the same to said first heat exchange means.

2. The combination set forth in claim 1 wherein said second means comprises a high pressure pump.

3. The combination set forth in claim 2 and including a first flow circuit for said fuel and a second flow circuit for said second fluid, and fourth means coupled to each of said circuits for maintaining a predetermined ratio of said fluids flowing to said first means.

4. The combination set forth in claim 3 wherein said first means includes a vessel for receiving said fuel and said second liquid, and impeller means within said vessel for mixing said liquids to produce an emulsion thereof.

5. The combination comprising first means including a vessel for receiving a liquid fuel and a second liquid, and impeller means within said vessel for mixing said liquids to produce an emulsion thereof, second means coupled to said first means for pressurizing and heating said emulsion to an energy level such that said emulsion will atomize upon being discharged into a lower pressure atmosphere, discharge means coupled to said second means for receiving said pressurized fluid and for releasing the same to the lower pressure atmosphere whereby said emulsion will atomize.

6. A combination process comprising the steps of:

emulsifying a liquid fuel and a second liquid which is immiscible in said fuel,

providing a combustion zone,

said second liquid having a lower flash temperature relative to the pressure of said combustion zone than said fuel,

heating said emulsion to an elevated temperature in excess of said flash temperature of said second liquid and lower than the flash temperature of said fuel relative to the pressure of said zone,

containing said heated emulsion in a flow system,

pressurizing said emulsion in said flow system to a pressure in excess of the pressure that said second fluid flashes at said elevated temperature, whereby said second fluid is prevented from flashing in said flow system,

discharging said pressurized and heated emulsion in said combustion zone whereby at least a substantial portion of said second liquid flashes to atomize said fuel,

and igniting said atomized fuel.

7. The process set forth in claim 6 wherein said second liquid is water.

8. The process set forth in claim 7 wherein said emulsion is pressurized to a pressure of about 2,000-10,000 psig.

9. The process set forth in claim 8 wherein said emulsion is pressurized to a pressure of about 4,000 psig.

10. The process set forth in claim 8 wherein said emulsion is relatively heavy fuel oil, and heating said emulsion to a temperature of about 450.degree. - 700.degree. F prior to discharge into said combustion zone.

11. The process set forth in claim 10 wherein said ratio of fuel to water is about 5:1 to 25:1.

12. The process set forth in claim 11 and including the step of providing a combustion supporting gas to said combustion zone.

13. The method set forth in claim 12 wherein said combustion supporting gas is air.

14. The method set forth in claim 12 wherein said combustion supporting gas contains CO.sub.2.

15. The process set forth in claim 7 wherein said emulsion is pressurized to a pressure of about 4,000 psig.

16. The process set forth in claim 7 wherein said fuel is relatively heavy fuel oil, and heating said emulsion to a temperature of about 450.degree.-700.degree. F prior to discharge from said nozzle.

17. The process set forth in claim 7 wherein said ratio of fuel to water is about 5:1 to 25:1.

18. The process set forth in claim 7 and including the step of providing a combustion supporting gas to said combustion zone.

19. The process set forth in claim 18 wherein said combustion supporting gas includes air and CO.sub.2.

20. A process of atomizing fuel comprising the steps of:

emulsifying a liquid fuel and a second liquid which is immiscible in said fuel,

providing a receiving zone,

said second liquid having a lower flash temperature relative to the pressure of said receiving zone than said fuel,

heating said emulsion to an elevated temperature in excess of said flash temperature of said second liquid and lower than the flash temperature of said fuel relative to the pressure of said zone,

containing said heated emulsion in a flow system,

pressurizing said emulsion in said flow system to a pressure in excess of the pressure that said second fluid flashes at said elevated temperature,

discharging said pressurized and heated emulsion in said receiving zone whereby at least a substantial portion of said second liquid flashes to atomize said fuel.

21. The process set forth in claim 20 wherein said second liquid is water and said fuel is oil.

22. The process set forth in claim 21 wherein an oxygen containing gas is introduced into said receiving zone to at least partially oxidize said oil.

23. The process set forth in claim 22 wherein said emulsion is pressurized to a pressure of about 2,000-10,000 psig.

24. A process of atomizing fuel comprising the steps of:

mixing a liquid fuel and a second liquid which is miscible in said fuel,

providing a receiving zone,

said second liquid having a lower flash temperature relative to the pressure of said receiving zone than said fuel,

heating said mixture to a temperature in excess of the phase change temperature of at least some of the components of said second liquid and lower than the flash temperature of said fuel relative to the pressure of said zone,

containing said heated mixture in a flow system,

pressurizing said mixture in said flow system to a pressure in excess of the pressure that said second fluid flashes therein,

discharging said pressurized and heated mixture in said receiving zone whereby at least a substantial portion of said second liquid flashes to atomize said fuel.

25. The method set forth in claim 24 wherein said second liquid is dispersed in said first liquid with the mean size of the droplets of said second liquid being less than about 5 microns in diameter, said mixture being substantially homogeneous.

26. The method set forth in claim 25 wherein said first liquid is fuel oil.

27. The method set forth in claim 25 wherein said first fluid is No. 6 residual oil and the second fluid Benzene.

28. The method set forth in claim 26 wherein said mixture is heated to a temperature above that of parafinic or aeromatic material which may be in said fuel oil.

29. A process for atomizing in a first zone a liquid having a plurality of constituents having different vaporizing temperatures for any given pressure, heating said liquid to a selected temperature that is more than the flash temperature of a first portion of the constituents of said mixture at the pressure of said zone and below the flash temperature of the remaining constitutents of said liquid at said pressure, containing said mixture in a system, pressurizing said liquid to a pressure in excess of the flash point pressure of said first portion of said constituents for said predetermined temperature to prevent vaporization in said system, and releasing said pressurized liquid into a lower pressure atmosphere whereby at least one of the constituents of said liquid will flash to subdivide the other constituents of said liquid into smaller sized droplets.

30. Apparatus for atomizing a first liquid in a pressure medium, first means for forming an emulsion of said first liquid and a second liquid having a lower flash temperature in said pressure medium than said first liquid, second means for containing said emulsion, third means for heating said contained emulsion to a temperature above the flash temperature of said second liquid in said pressure medium and below the flash temperature of said first liquid in said pressure medium, fourth means for pressurizing said contained liquid to a pressure above the pressure at which said second pressure will flash in said second means, and discharge means for releasing said contained emulsion into said first pressure medium whereby a substantial portion of said second liquid flashes to atomize said first liquid.

31. The invention set forth in claim 30 wherein said first liquid comprises a fuel and including means defining a combustion zone, said discharge means comprising a nozzle means for discharging said emulsion into said combustion zone.

32. The combination set forth in claim 31 wherein said fourth means comprises a high pressure pump.

33. The combination set forth in claim 32 and including a first flow circuit for said fuel and a second flow circuit for said second liquid, and fifth means coupled to each of said circuits for maintaining a predetermined ratio of said liquids flowing to said nozzle means.

34. The combination set forth in claim 33 wherein said first means includes a vessel for receiving said fuel and said second liquid, and impeller means within said vessel for mixing said liquids to produce an emulsion thereof.

35. The combination device set forth in claim 31 wherein said fourth means includes a high pressure pump.

36. The combination set forth in claim 31 wherein said first means includes a vessel for receiving said first and second liquids, and impeller means within said vessel for mixing said liquids to produce an emulsion thereof.

37. The combination set forth in claim 31 and including a first flow circuit for said fuel and a second flow circuit for said second liquid, and third means coupled to each of said circuits for maintaining a predetermined ratio of said liquids flowing to said first means.