Embedded fuel emulsification system for large displacement diesel engines
This technique was developed to emulsify diesel fuel and water, without using surfactant. The pump of the engine injector is supplied with the emulsion thus obtained, with a water content of up to 40%, depending on the needs of the user. The emulsion is obtained mechanically by a propeller rotating at high speed (more than 7 500 rpm) in a mixing chamber. Diesel fuel (including marine diesel fuel or heavy fuel oil) is pumped into this chamber from the bunkers. The water is added by means of a proportional solenoid valve, controlled by a microprocessor and the software to operate it. A signal sent to the microprocessor by a flow meter located in the fuel line, determines the amount of water to be added to the fuel by varying the opening of the solenoid valve. Downstream of the point of injection of the water into the fuel, the high speed propeller contacts the two liquids. Mechanical agitation breaks up the water into fine droplets. The dispersion of these in all the fuel constitutes the emulsion. This comes out of the mixing chamber and enters the injection pump from which it is directed to the individual fuel injectors of the combustion chambers.
To go at full speed, a feedback from a speed sensor causes the closing of the solenoid valve that feeds the mixing chamber with water. The injector pump is now supplied with 100% Diesel fuel.
As approximately 90% of the fuel flowing to the injectors returns to the cargo hold, it must be demulsified beforehand. For this purpose, a centrifugal separator is used. The water is returned to the water tank for re-use in the emulsification process, while the fuel is returned to the cargo hold.
This technique will result in the same nitrogen oxide emission reductions as those measured with surfactant emulsions, but has the additional flexibility to give the engine all the power needed in critical situations. With the use of surfactant, there will always be a loss of power, due to the water added to the fuel, because the water is devoid of thermal energy. In addition, in cold weather, the water content of the fuel is a concern for the circulation of the latter. In these applications, there is no question of storing emulsified fuel (diesel fuel + water + surfactant) in order to absorb the exhaust gases.