METHOD AND SYSTEM FOR WATER-FUEL EMULSIONS PRODUCTION

Abstract

Water-fuel emulsions can be used in engines, predominantly in diesel engines, to achieve considerable fuel economy and reduce emissions of noxious exhaust components, NOx, CO2 and soot. However, the emulsion combustion technology for engines of power units has not been applied widely since the main two components are immiscible; water separates and causes corrosion in pumps, injectors, regulators and so on. In order to improve mixing, special emulsifiers are applied, but in this option emulsion does not sustain long. Proposed new emulsion making technology uses simultaneous dissolution of highly soluble gases CO2 and CH4 in immiscible components fuel and water. Tests demonstrate that water-fuel emulsion produced using the new technology retains stability when exposed to temperature and at long-term storage in the open air.

Description

RELATED APPLICATION

This application claims priority to Provisional Application No. 61643,311 filed on May 6, 2012, the contents of this provisional application are expressly incorporated herein by reference thereto.

FIELD OF THE INVENTION

The invention is related to the field of engine development, particularly to the engine fuel supply systems and improvement of the engine efficiency.

BACKGROUND OF THE INVENTION

Water-fuel emulsions (WFE) as an alternative high efficiency oil or synthetic fuel have been studied over the past years, especially heavy petroleum oil fuel with the high water content, up to 45% for heating applications. Manufacturers such as Caterpillar and MAN have researched WFE in internal combustion engines, especially in powerful energy-producing plants and marine engines. VOLVO also conducted similar research applications of WFE in diesel engines.

The main danger in applying WFE is that water is quickly separated from the WFE that results in corrosion of system components, such as fuel supply (especially pumps, injectors, valves, etc.), particularly when the engine is shut down.

The wide application of WFE has only been in the field of agricultural machinery with short life spans; when one or several fuel fillings a day are needed. Under these circumstances of the local operation, it is profitable to fill up the tank with the emulsion which is easily made of cheap components: emulsifiers and stabilizers that give stable emulsion for storing up to 5-7 days including vibration and shaking during the working process.

The applying of additives such as emulsifiers and stabilizers is also not a favorable factor because the engine exhaust becomes worse and pump and injector life times is decreased. But for non-expensive engines, e.g. for farming machines, this will effect a saving of the expensive diesel fuel.

There are research papers and published patents relating to WFE technology without emulsifiers and stabilizers. For example, in the patent RU No. 2381826, 2006 “The system to prepare WFE for the internal combustion engines” was published where it was disclosed that the problem of WFE physical/chemical stability can be solved without any emulsifying additives. This solution was due to the original design of the mixing device and the device of aqueous phase dispersion in basic fuel as well as due to multiple circulation—intensive mixing of heated emulsion, the returned surplus of fuel emulsion from the engine after the injection before the re-feeding of the emulsion to the high pressure pump of the main fuel supply system. The inventors of this patent state that the originality of diesel fuel mixing and water dispersion devices consists in the applying of an ultrasonic wave disperser, which provides an intensive turbulence of the emulsion recycling flow.

In a similar patent RU No. 2381 826, 2012 for the emulsifier-free (without using extra emulsifiers and/or stabilizers) WFE a jet apparatus was used for water supply into the fuel flow, thereafter the water and fuel mixture is fed into the meter-mixer, where the hot backflow of unused returned emulsion is fed. The suggested system is very complex: it comprises a reducing controller in the fuel supply line and in the parallel water supply line for mixing, a complex hydraulic actuator which proportions/meters the water supply into the jet mixer. It is obvious that it is very complex to operate such an hydraulic actuator and the whole system, especially at fluctuating engine loads, because it is necessary to supply emulsion having special composition and provide optimal proportions when mixing three components in the metering unit: a) basic fuel; b) return flow of unused emulsion and c) freshly made mixture from jet pump.

U.S. Pat. No. 4,388,893 “Diesel Engine Incorporating Emulsified fuel supply system”, 1983, discloses a complex approach of water-fuel emulsion preparation with a preset concentration of 2 components using no emulsifying additives. The system has three recirculation contours; each contour has an independent recirculating pump that pumps correspondent component (fuel, water, and water-fuel emulsion) to an injection pump through a mixing chamber. The water used to prepare the water-fuel emulsion is obtained by condensing water from the exhaust gases and then fed to the mixing chamber. The amount of water fed to the mixing chamber is controlled by a special controller using position sensors on an accelerator pedal and speedometer. The second stage of preparing the water-fuel emulsion is performed immediately before supplying the water-fuel emulsion to the injection pump and is controlled by the controller.

U.S. Pat. No. 6,530,963, 2003 “Continuous Process for Making an Aqueous Hydrocarbon Fuel” describes a process for making an emulsion stable in long-term storage and having aqueous droplets with a mean diameter of less than 10 microns. The last object is achieved by using at least two emulsifying agents.

U.S. Pat. No. 7,645,305, 2010 “High Stability Fuel Composition” discloses that to prepare an aqueous fuel emulsion with water continuous phase an additive package that includes an surfactant and at least one additional component provides a mean diameter of water

phase less than 10 microns. The following formulation is shown as an example: a) diesel fuel of 67% (balance); b) highly purified water of 30%; c) methanol of 2%; d) 2-EHN of 0.37%; and six more components. The patent discloses that such a composition allows decreasing particulate emissions of 40-55% and NO_x+Hydrocarbon (HC) emissions of 45%.

PCT/EP2006008496 describes a device to make an emulsion (diesel fuel+water) comprises a static mixing system, an homogenizing valve having an outlet port of small size and first, second and third high pressure cylinders with working pressure of 2000 bar. Diesel fuel and water are pre-mixed in the static mixing chamber to obtain a raw emulsion and are directed to a device comprising three high-pressure cylinder chambers. The inlets of the first high-pressure cylinder and the second high-pressure cylinder are connected to the water/diesel fuel raw emulsion mixing chamber, the outlets of the first high-pressure cylinder and the second high-pressure cylinder are connected to the homogenizing valve, the inlet of the third high-pressure cylinder is connected to the outlet of the homogenizing valve, and the outlet of the third high-pressure cylinder is connected to the diesel engine. The three pistons of the three high-pressure cylinders are part of a pressure booster which is connected to a hydraulic drive unit. The significant drawbacks of this system are high energy requirements and the necessity of the rigid kinematic connection with the crankshaft of the engine which results in inefficient operation at variable revolutions of the crankshaft and engine loads.

SUMMARY OF THE INVENTION

In the present application, an advance in engine engineering, in particular—in diesel engine technology, is made in a new direction: transfer of fuel delivery systems running at operating load to fuel-gas mixture supply to injection. Fuel solution, e.g. diesel fuel/air, fuel/natural gas or fuel/CO2 is made on-board the vehicle. To do so a special vessel where gas is dissolved in liquid fuel at increased pressure should be installed, as well as a system of switching valves. Such a fuel supply system can operate on the base (standard) fuel, e.g. when the engine starts, or on fuel solutions when the engine runs at operating load. When the fuel solution is injected at a high rate to the combustion chamber, active release of absorbed gas takes place in each infinitely small volume of the injected fuel due to hydrodynamic discontinuity and simultaneous stepwise change of the fuel parameters. The process of gas desorption from the fuel solution exhibits typical features of chain dispersion process. This results in ultrafine separation and distribution of the injection dose, rapid phase transition (evaporation) and highly efficient combustion producing reduced content of all exhaust components, above all—NO_x and CO₂. Obtained results of for combustion of fuel-gas solutions suggest that it can be beneficial to add deionized water, in particular—in the form of a gasified solution, to the efficient combustion process. Analysis and experiments confirmed that introduction of gasified water component to the combustion process produced favorable effect. Subsequent experiments run on a Volkswagen turbo-diesel engine demonstrated that the most advisable method for application in vehicles is delivery of 3-component emulsion composed of diesel fuel/deionized water/dissolved gas (gases) to injection.

It was shown that simultaneous dispersion of two immiscible liquids, water and liquid fuel, in the absorber at excess pressure ensures formation of highly homogenous emulsion with ultrafine distribution of water phase particles in the base fuel. Water component inclusions that make up 3.1-5.5% of the total mass of the produced emulsion are particles smaller than 1 micron. The color of emulsion fuel/water/gases changed as compared to the base fuel is opaque, slightly white, turbid and uniform throughout the entire volume.

In the experiments described herein, one stage of dissolution of gases in liquid components was used and emulsion was made without the use of emulsifiers, surfactants or other chemicals. Operating gas pressure in the absorber was 115 psi (≈7.8 bar) and 180 psi (≈12.2 bar), the dissolved gas was represented by air, CO₂ or CH₄. Fuel solution temperature was 65-80° F. Deionized water content was 5.1±0.6% when dissolving CH₄ and CO₂ and 3.5±0.4% when dissolving air.

Emulsion homogeneity sustained when the gas pressure was reduced to the atmospheric pressure with the gas blanket retained (as it had been in the process of dissolution of, e.g. CO₂ and CH₄) followed by storing the emulsion for 1 year at 120° F.; no changes in the color density when observing it with directed light in the entire stored volume; no sediments, visible local discontinuities or stratification were observed. The initial composition of the emulsion did not change after it had been subjected to heat to 200° F. (≈95° C.) for 3 hours.

After the emulsion had been stored for one year two modifications were subjected to tests: emulsions obtained using air and those made with CO₂. Tests were run on 1.9 L4-cylinder Volkswagen engine with turbocharger. 115 miles drive tests and DynoTests demonstrated diesel fuel economy of 12.45±2.8% while the exhaust reduced up to 17%.

Further experiments included tests aimed at exploring the possibility for emulsion storage in open air at the atmospheric pressure, similar to conditions for diesel fuel storage. Emulsion temperature in the course of long-term storage (3 months) changed in the range of 95° F. (35° C.) 5° F. (−15° C.). No changes in the emulsion composition resulting from open storage in the air were observed. No water separation took place. Subsequent tests run on an operating engine where emulsion was supplied after its storage in ambient conditions also confirmed the features of highly efficient combustion, similar to experiments run on the initial emulsion. Fuel economy was from 8.3% to 12.5%, accompanied with reduction of CO2 and Nox to 15.3%. In order to study combustion at increased water content emulsions were made using the new technology. A 2-stage process of emulsion making was tested. In this process, emulsion was containing 4.5% of water and 2.5% of isopropyl alcohol (by mass) was fed to the second stage; this emulsion had been obtained at the first stage at CO₂ pressure of 90 psi (≈6 bar) and temperature 80° F.

At the second stage emulsion from the absorber was delivered without reduction of pressure P₁, to a second absorber for dispersion. Along with that water with added isopropyl alcohol also was dispersed in the second absorber. In the course of dispersion of liquid components a mixture of gases was fed to the second absorber; the mix was composed of 50% of CO₂ and 50% of CH₄ at full pressure the second in absorber, P₂=400 psi (28 bar). The amount of the added water-alcohol components varied from 4.5% to 18.5% while all other parameters of the process were kept unchanged. Three hours after completion of each test with increased supply of water-alcohol mixture, the bottom part of the absorber was examined for free water released in the process. It was observed that water separation in the second absorber emulsion took place after the introduction of 15% water-alcohol mixture to the process. In the reference tests emulsion remained stable after addition of 13.5% water-alcohol mixture and no separated water phase emerged in 24 hours. After that the emulsion was released from excess pressure and kept for three days in a controlled environment at atmospheric pressure without contact with air. No water separation took place. In the next test emulsion was kept in an auxiliary storage tank and was in contact with air at the temperature of 72° F. (≈22° C.). This test was run for 30 days and no water phase separation was observed. After the emulsion produced at the stage 2 had been held for 30 days, Dyno Tests and Drive Test were run. The outcome of the tests indicated diesel fuel economy of 18.3%±3.3% accompanied by exhaust reduction up to 25%.

The present invention comprises a method for on-board production of water-fuel emulsion free of emulsifier and stabilizing additives. The method comprises:

• • providing an absorber;
  • feeding a liquid fuel and other additional incombustible evaporative liquids to absorber, providing high level spraying of both liquid flows;
  • feeding at least one gas to the absorber providing a high level of contact of liquid and gases; and
  • providing an electronic controller for controlling flows of liquids and gases.
    The method comprises at least one stage of emulsion preparation with water phase content of at least 3.5% by weight through dissolution of, at least, one gas at the partial pressure of each component being at least 1.35 bar, where the produced emulsion is delivered to an engine fuel supply pump while a return flow of unused emulsion coming from the engine is cooled and returned to the absorber; the emulsion level is maintained by synchronous and proportional supply of each dispersed liquid component under discrete control of feed pumps operation by a controller that sends commands based on a level sensor signal.

The present invention further comprises a method for production of highly sustainable water-fuel emulsion. The method comprises an at least two stage process of simultaneous or consecutive dissolving of gas/gasses in dispersed liquid components under high pressure including:

• • spraying in a first stage liquid components in a first absorber under gas pressure of P₁;
  • feeding in a second stage water-fuel emulsion from the first absorber is fed to a second absorber where emulsion and additional portion of water/antifreeze agent are sprayed under gas pressure P2;
  • dispersing liquid components and antifreeze additives, preferably, in top areas of the absorbers and collected emulsion evacuate, at least, through one port at the bottom of the second absorber to a storage tank for long time storage under atmospheric pressure;
  • Compressing free gas/gases released from the emulsion in the storage tank and returned to the second absorber for secondary dissolution.
    The ratio of water-fuel emulsion components is no less than 75% by weight of hydrocarbon fuel, up to 18.5% by weight of deionized/desalted water, and up to 2.5% by weight of antifreeze agent. The method comprises return of a part of emulsion taken from the bottom area of the first absorber, e.g.—water that is escaped emulsion, to a first stage water tank through an emulsion quality indicator, while the main part of the emulsion is directed to the storage tank; this is accompanied by feeding the gases emitted in the storage tank to the first absorber where they are mixed with a make-up gas for repeated dissolution.
    Another embodiment of the invention comprises an absorber for making highly sustainable emulsion which is configured to operate at an excessive pressure of at least one gas. The absorber has ports for intake of liquid components and a gas mixture, as well as spraying devices in the top part of the absorber. All component supply ports are preferably equipped with valves to prevent backflows. The absorber has at least 2 ports in a bottom part with the top one (near-bottom) serving as an emulsion discharge opening for feeding emulsion to a quality control fixture and is hydraulically connected through an indicator with a de-ionized water storage tank.

A further embodiment of the present invention comprises a system for production of highly sustainable water-fuel emulsion for diesel engine without the use of emulsifiers and other chemicals. The system comprises an absorber hydraulically connected to a de-ionized water storage tank and a standard liquid hydrocarbon fuel storage tank. The absorber is also connected to a high-pressure gas vessel and the absorber has inlet ports for introduction of the aforementioned components as well as ports for discharge of a prepared emulsion. It is equipped with an external level sensor that sends commands to feed pumps.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of an emulsion making system as part of an engine for immediate use.

FIG. 2 shows a schematic of an emulsion making system for producing long-storable water-fuel emulsion.

DETAILED DESCRIPTION OF THE INVENTION

One embodiment of a system that makes an emulsion intended for a diesel engine is shown on FIG. 1. FIG. 1 depicts general provisions needed to understand the present process, which does not rule out other configurations for integration of the new system with another engine. The system shown on the FIG. 1 represents a first emulsion production stage where no emulsifiers are added and water content is up to 5.7%.

The main components of the new system are: emulsification unit 1 with external level sensor 2, dispersing devices 3 and 3a, inlet and outlet 4 and 5, gas inlet 6, emulsion output ports 7 and bottoms discharge port 8. All inlets 4, 5, 6 are equipped with check valves 4a, 5a, 6a in order to prevent backflows. Fuel is supplied from standard fuel tank 9. Fuel comes through the standard fuel delivery line 9a and check valve 9b to the new system connection point pA1 and further to pump 10. Low pressure gear pump 10 drives fuel through 3-way valve 11 and line 11a to inlet 4 of the emulsification unit 1. Water is driven to the emulsification unit 1 from additional tank 12 by pump 12a. Gas, preferably CO₂, comes from storage vessels 14 through solenoid valves 15 or 16 and downstream pressure regulator 17 to intermediate vessel 18. From this vessel gas is fed to the second pressure control stage 19 and further to the gas inlet 6 of emulsification unit 1.

Prepared emulsion is discharged from port 7 located in the emulsification unit bottom zone through line 21 to stream driver 22 and further to Y-mixer 23 to be mixed with recycled emulsion that remained unused in the engine and comes through recycle line 25a. Fuel to be recycled initially comes to three-way valve 25 and then to heat exchanger 26 where it is cooled down, then released gases and vapors are separated in gas separator 27 under increased pressure controlled by relief valve 28; fuel flows from the discharge port of the relief valve 28 through line 28a to the Y-mixer 23. After having been mixed with fresh emulsion in Y-mixer 23 the stream flows through line 24 to the suction of recycling pump 29 and further through 3-way valve (preferably—with an electro-pneumatic drive) 30, check valve 31, connection point pA2 and local filter 32 to the intake port of the engine (35).

If needed the emulsion can be transferred for storage to air-tight tank 36 through solenoid valve 37. Pressure in tank 36 is monitored by pressure sensor 38 and when gas is accumulated in the tank then controller 55, upon taking readings from sensor 38, turns on compressor 39, which returns the gas released in the tank through check valve 40 to intermediate vessel 18.

Water that may escape from the emulsion and accumulated at the bottom of the emulsification unit 1 are discharged from port 8 through solenoid valve 42, throttle 44 and line 45 to water tank 12.

Gas released in separator 27 flows through line 46, throttle 47 and solenoid valve 48 to line 49 and further to the engine air supply line, preferably downstream of compressor 50. Standard fuel delivery line includes a supply line running from the connection point A1 to main engine pump 101 through manually controlled 3-way changeover valve 102 and/or heater 103 and further through filter 104 and bypass regulator 105 to the new system connection point A3. Then it flows through three-way valves 106 and 30, preferably of electro-pneumatic type, to the engine intake port.

When the engine operates in the basic mode return fuel from the engine is removed through normally open ports of the three-way valve 25 and comes to the point pA4. If the fuel supply line gets plugged then part of the fuel is removed from point A3 through booster regulator 109 and annunciator 110.

In emulsion feed mode main pump 101 supplies base fuel from tank 9 to cool down the return flow by switching valve 106. The cooling stream of the base fuel comes out from the exchanger via point A4 through relief valve 107 and flow visual inspection device 108. If it is needed to switch from emulsion to a base fuel then a command from controller 55 changes position of three-way valve 11 for a short time (<5 min) and the base fuel comes from pump 10 through valve 11 to line 32a and further to the engine intake port. The return stream of the fuel coming from the engine is recycled flowing in a closed loop, passing through exchanger 26, gas separator 27 and relief valve 28; part of the fuel returned from the engine is diverted through 2-way valve 115 and throttle 116 to point A4 and further to fuel tank 9. All 3-way valves are driven by electro-pneumatic effectors 11, 25, 30, 106. After running the flash mode for 5 minutes (preferably) controller 55 removes control signals and the fuel supply system turns to operation in the base fuel supply mode.

A unit for making long-lasting WFE based on diesel fuel is shown on FIG. 2 and, essentially, is a multistage device having at least two stages; a similar unit was shown earlier on FIG. 1 as one stage system. The first stage of the unit introduces up to 5.7% of water component with up to 2.5% of antifreeze agent (isopropyl alcohol) to WFE. This first stage includes emulsification unit 1 with external level sensors 2 and corresponding inlets for fuel, water and gas, as well as emulsion and bottoms discharge ports. Fuel and water are supplied to the dispersers of emulsification unit 1 from storage tanks 9 and 12 by pumps 10 and 13; their operation is controlled by controller 55 based on signals received from sensor 2 that correspond to the readings of the volume of emulsion made in emulsifier unit 1. Prepared emulsion is discharged to three-way valve 25 and is driven further by pump 210 to disperser 214. At the same time water component is supplied to disperser 213 from water storage tank 211 by pump 212 and dispersed in the upper gas zone of emulsification unit 2. Mixed gases CH₄ and CO₂ come from storage vessels 215 and 216 connected in parallel via solenoid valves 217 and 218 to downstream pressure regulator 219 that sets the gas mixture pressure in intermediate vessel 220. Mixing gases in vessel 220 is achieved through metered supply of gases at alternated activation of valves 217 and 218 upon commands coming from controller 55. After gases are mixed in vessel 220 the gas mixture is fed to 2nd stage downstream pressure regulator 223, then—to check valve 224 and further to the gas inlet of emulsification unit 2. Prepared emulsion is discharged from emulsification unit 2 via discharge port 207 to throttle 227 and then via solenoid valve 228 to WFE storage 2 equipped with pressure sensor 233, which sends a signal corresponding to readings of gas mixture pressure in storage 2 to controller 55. Controller 55 sends a command to activate compressor 235; the compressor returns the gas mixture from storage 2 to intermediate vessel 220.

Prepared emulsion quality is monitored by repeated discharge of emulsification unit bottoms through two-port valve 238 and throttle 239 with product supply to indicator 240 and further to the water phase storage tank.

Long-term storage emulsion accumulated in storage 2 is used as a new fuel for filling consumers' power units.

Claims

1. A method of on-board production of water-fuel emulsion free of emulsifier and stabilizing additives, wherein the method includes:

providing an absorber;

feeding a liquid fuel and other additional incombustible evaporative liquids to absorber providing high level spraying of both liquid flows;

feeding a gas or a mixture of gases in absorber providing a high level of contact of liquid and gases; and

providing an electronic controller for controlling flows of liquids and gases.

2. A method of production of highly sustainable water-fuel emulsion, wherein the method comprises at least one stage process, and preferably two stage process of simultaneous or consecutive dissolving of gas/gasses in dispersed liquid components under high pressure:

at first stage liquid components are sprayed in absorber #1 under gas pressure of P1;

at second stage water-fuel emulsion from absorber #1 is fed to absorber #2 where emulsion and additional portion of water sprayed under gas pressure P2;

liquid components are dispersed, preferably, in top areas of absorbers and collected emulsion evacuate, at least, through one port at the bottom of absorber #2 to a storage tank for long time storage; and

gas/gases released from emulsion in the storage tank are compressed and returned to the absorber #2 for secondary dissolution.

3. The method according to the claim 2, wherein the ratio of water-fuel emulsion components is no less than 75% by weight of hydrocarbon fuel, up to 18.5% by weight of deionized/desalted water, and up to 2.5% by weight of antifreeze agent.

4. The method according to the claim 1, wherein the method comprises at least one stage of emulsion preparation with water phase content of at least 3.5% by weight through dissolution of gas mixture or at least one gas at the partial pressure of each gaseous component being at least 1.35 bar, where the produced emulsion is delivered to the engine fuel supply pump while the return flow of unused emulsion coming from the engine is cooled down and returned to the absorber; the emulsion level is maintained by synchronous and proportional supply of each dispersed liquid component under discrete control of at least one feed pump operation by a controller that sends commands based on the level sensor signal.

5. The method for making highly sustainable water-fuel emulsion according to the claim 2, wherein the method includes the return of a certain part of emulsion taken from the bottom area of absorber #1, e.g.—water that is escaped emulsion, to the first stage water tank through the emulsion quality indicator, while the principal part of the emulsion is directed to the storage tank; this is accompanied by feeding the gases emitted in the storage tank to the absorber #1 where they are mixed with the make-up gas for repeated dissolution.

6. An absorber for making highly sustainable emulsion, operating at an excessive pressure of gas or a gas mixture, and having ports for intake of liquid components and a gaseous components, as well as spraying devices in the top part of the absorber; all components supply ports are preferably equipped with valves to prevent backflows; the absorber also has at least 2 ports in the bottom part with the top one (near-bottom) serving as an emulsion discharge opening for feeding emulsion to the quality control fixture and is hydraulically connected through an indicator with the water storage tank.

7. A system for production of highly sustainable water-fuel emulsion without the use of emulsifiers and other chemicals wherein the system has an absorber hydraulically connected to a water source and a standard liquid hydrocarbon fuel source; it is also connected to a high-pressure gas; the absorber has inlet ports for introduction of the aforementioned components as well as it has ports for discharge of the prepared emulsion and it is equipped with an external level sensor that sends commands to the feed pumps.