Background of the invention The invention is associated with an emulsion system/procedure that is dosing water and an emulsifying agent into the fuel oil system of diesel engines. steam boiler plants and other combustion plants. The water-in-oil emulsion is produced and sustained inside the fuel oil system pipes and utilised as fuel.

The making of water-in-fuel oil emulsion is well known. Emulsion for utilisation as a fuel has been produced mechanically in one of the following procedures: A mixture of oil and water is led through a narrow passage where relative movements of the components making up the passage create shear forces resulting in an emulsion between the fluids in the passage.

A mixture of oil and water is pressurised and led through a restriction where the pressure is allowed to drop. Because of shear forces created in the fluids during the restricted flow water-in-fuel oil emulsion is made.

In both of these cases the emulsion is made inside the apparatus before being led into the fuel system. Due to reasons mentioned later running engines on distillates needs a special approach in order to prevent the emulsion from being too hot before it is delivered to the engine. It is therefore necessary to install a fuel oil cooler and a connected temperature regulating system.

The formation of emulsion during fluid flow through a narrow passage adds energy to the fluids. In addition energy is transferred to the return fuel bv the extreme pressurising and subsequent pressure drop which it is exposed to in the injection pumps. As a result of this the fuel temperature in the fuel pipe system is raised. The temperature raise may be so great that when operating on distillate fuel the emulsion may not be supplied to the engine as fuel without special measures. High fuel temperature may produce gases inside the fuel system and ruin the fuel injection pumps (scuffing of surface material because high temperature and presens of gases reduces the lubricating ability of the fuel). This is the case when the fuel cannot be heated before it is supplied to the engine. as is the case for distillates like marine gas oil (MGO). marine diesel oil (MDO). etc. I such cases the emulsion must be cooled before it can be delivered to the engine.

Water-in-oil emulsion that is produced by restricted flow is separated into water and oil after a short time. The emulsion therefore must be used only a few seconds after it has been produced. This requirement calls for a location of the apparatus producing the emulsion close to the injection system of the engine. It also necessitates that the return fuel, in this case the emulsion, is not returned to the service tank but led through the emulsion producing apparatus. The combination of these two requirements prevents the fuel system pipes to function as a heat exchanger removing surplus heat from the fuel being delivered to the engine.

By producing water-in-oil emulsion in accordance with the invention the problems mentioned above are avoided. and the following is achieved: Water-in-oil is generated in the fuel oil system and not in the dosing apparatus.

* There is no fuel oil flow through the dosing apparatus.

Water-in-oil is generated without any temperature increase by the fluids it is composed of.

* Water may be introduced at any point of the fuel oil circulating system of the engine.

* The emulsifying agent may be introduced to the fuel oil anywhere. I. e. the emulsifying agent may be supplied to the fuel in the bunker tanks, at any point of the fuel oil circulating system of the engine or in a pipe anywhere between these locations.

Problems that the invention is to solve The emulsion system areas of utilisation are diesel engines, steam boilers and combustion plants operating on liquid fuel when it is desired to reduce engine thermal load and the production and emission of NOX, CO and C (carbon/soot) of engines and the other installations mentioned.

Operating an engine on water-in-oil emulsion reduces the thermal load of the engine because the water heating, evaporation and superheating in the combustion zones require energy.

When this energy is taken from the combustion gases, their maximum temperature is reduced.

By reducing the combustion process maximum temperature the emission of NOX is reduced.

In addition the emission of CO and soot is also reduced because the volume expansion of the water inside the oil droplets improves their atomisation and distribution and enhances their contact with the oxygen available in the combustion chamber. At high process temperatures the water is somewhat dissociated thus liberating hydroxide ions and atomic oxygen that combines with carbon. Thus the emission of soot is diminished.

NOX creates acid rain and ozone near the ground. CO is toxic, and soot contaminates the environment visually. Besides the aspiration of soot degenerate the function of the lungs and the quality of the blood in addition to increasing the danger of getting cancer because carbon in crystalloid form may be a carrier of cancer developing unburned hydrocarbons (UHC).

Description of the invention Schematic diagrams of the apparatus and its connection to a diesel engine fuel system are shown in the appendix. Fig. 1 applies to a system where the engine is operated on distillate fuel, while Fig. 2 applies to heavy fuel operation.

Two metering pumps, no. 1 for water and no. 2 for an emulsifying agent, are dosing their fluids directly into the fuel oil circulating system. Water-in-oil emulsion is produced and maintained inside the fuel oil system pipes due to the turbulence that is created when the circulating pump transports the fluids inside the system.

The rate of delivery from pump no 2 is controlled by a signal transmitted from an amplifier (3). The rate of delivery from pump no. 1 is controlled by a signal transmitted from a converter (4) following the amplifier. The amplifier receives a signal transmitted from a flowmeter located in the fuel supply pipe between the service tank and the fuel oil circulation system. This arrangement enables the system to produce an emulsion with a water percentage depending on engine load while maintaining a constant emulsifying agent percentage in the emulsion If the emulsifying agent were added to the oil at the bunkering, installation of pump no 2 in the apparatus is not necessary since the fuel entering the circulation system in this case already contains the necessary emulsifying agent concentration for the making of water-in-oil emulsion.

The converter may be set to transmit a control signal to pump no. 1 producing a water-in-oil emulsion with the largest water concentration that the engine can accept when operating at 100% power. In addition the signal converter control of this pump enables prevention of the water-in-oil emulsion reaching such a high water content that ignition failure is caused at low power.

The fuel (water-in-oil emulsion) that is returned from the engine fuel delivery system contains water and emulsifying agent. If the water-in-oil were returned to the service tank, the amount of water in the emulsion coming from this tank would be added to the measured rate of fuel flow. The water-in-oil emulsion therefore should be led to the circulation system instead. This is brought about, as demonstrated in Fig. 1, by installing a stop valve in the service tank return pipe and a crossover (5) between the inlet to this valve and a location between the service tank fuel outlet and the suction side of the circulating pump.

Normally, engine plants operating on heavy fuel have a fuel circulation system that includes a mixing tank. This tank acts as a crossover. In such plants the fuel is circulating in the pipe system, returning only fuel vapours to the service tank. For such plants the user has an option whether to install the flowmeter on the suction or delivery side of the service pump.

For steam boiler and other combustion plants the diagrams in the appendix applies if"engine" is replaced by"combustion chamber".

The water addition may be distilled or potable. The emulsifying agent may be of any kind that emulsifies water in oil due to the turbulent action only upon the emulsifying agent, water and oil mixture inside the fuel lines and without need of substantial mechanical energy supply in order to create shear forces in the fluids.

Effects of the invention When running the engine at high load, operating on a high water content emulsion may be preferred, since this ensures a great reduction of harmful emissions like NOX, CO and soot. In this instance the engine tolerates large amounts of water added to the fuel because the process temperature inside the cylinder unit is high.

When running the engine at low load, too extensive water addition may cause ignition failure and soot production. There is, however, an advantage that the engine also in this mode of operation is run on water-in-oil emulsion, but with a small concentration of water, because the water-in-oil emulsion contributes to the reduction of soot formation during the combustion.

The signal converter integrated in the system makes is possible to fulfil both wishes. The engine may be run on low water concentration emulsion when operating at low load and have an emulsion supplied with a water concentration that increases with raising engine load, until a maximum water concentration is reached. The fuel injection pumps set this limit.

The apparatus does not produce water-in-oil emulsion by providing a lot of mechanical energy that can be used to create shear forces in the fluids. Further, the production process does not require that water-in-oil emulsion is created in a small loop close to the engine so that problems with cooling of return fuel from the injection pumps arise. On the contrary the production process allows the loop to be very large with such long pipes that they can function as a heat exchanger and transfer heat from the fuel inside the pipes and to the surrounding air. This feature enables the emulsion system to operate without any extra heat exchanger in the fuel circuit.

Summary of the invention The water pump (1) and the emulsifying agent pump (2) are dosing their fluids directly into the fuel system where water-in-oil emulsion is produced and sustained in the fuel pipes due to the turbulence created by the flow.

The rate of delivery from the emulsifying agent pump (2) is controlled by a signal transmitted from an amplifier (3). The rate of delivery from the water pump (1) is controlled by a signal transmitted from a converter (4) following the amplifier. The amplifier receives a signal transmitted from a flowmeter located in the fuel supply line between the service tank and the fuel oil circulation system.

If the emulsifying agent were added to the oil at the bunkering, installation of the emulsifying agent pump (2) in the apparatus is not necessary since the fuel entering the circulation system in this case already contains the necessary emulsifying agent concentration for the making of water-in-oil emulsion.

The engine may be run on low water concentration emulsion when operating at low load and having an emulsion supply with a water concentration that increases with raising engine load, until a maximum water concentration is reached. The fuel injection pumps set this limit.

The fuel (water-in-oil emulsion) that is returned from the engine fuel delivery system is led to the circulation system through a crossover (5) as demonstrated in Fig. 1.

Engines operating on heavy fuel have a mixing tank in the fuel system. This tank acts as a crossover.

For steam boiler and other combustion plants the diagrams in the appendix applies if"engine" is replaced by"combustion chamber".

The water addition may be distilled or potable. The emulsifying agent may be of any kind that emulsifies water in oil due to the turbulent action only upon the mixture of emulsifying agent, water and oil inside the fuel lines and without need of substantial mechanical energy supply in order to create shear forces in the fluids.