Fuel system for diesel engines using carbonaceous aqueous slurry and emulsion fuels

A method for controlling fuel circulation in a diesel type engine using carbonaceous aqueous slurry fuels, carbonaceous emulsion fuels or mixtures thereof, the diesel type engine including a fuel circulation system and a fuel injection system which is fluidly connected to the fuel circulation system, the fuel circulation system comprising:

• at least one fuel feed pump comprising a positive displacement pump located in the fuel circulation system before the fuel injection system, the fuel feed pump configured to supply a controlled amount of carbonaceous aqueous slurry fuel to the fuel injection system;
• and
• at least one volumetric flow controller comprising at least one of a second positive displacement pump configured to operate in reverse as a positive displacement pressure let-down device, or a volumetric flow valve operated as a positive displacement pressure let-down device, the volumetric flow controller located in the fuel circulation system after the fuel injection system, the volumetric flow controller providing a controlled regulation of return flow/fuel system pressure from the fuel injection system from zero to maximum flow/pressure,
• and the fuel injection system further includes an injector bleed or by-pass valve for regulating circulating flow carbonaceous aqueous slurry fuel through the fuel injection system,
• the method includes the step of:
• adjusting the relative speed of the fuel feed pump, the volumetric flow controller and the injector bleed or by-pass valves to control or provide at least one of:
• (i) fuel supply pressure;
• (ii) fuel flow rate;
• (iii) fuel flow rate to prevent sedimentation in the fuel;
• (iv) fuel flow rate to minimise adverse changes to the fuel rheology and destabilisation by over working due to excessive circulation around the fuel system;
• (v) fluid flow for fuel change over;
• or
• (vi) flow of flushing fluid and more efficient and quicker flushing of the fuel system.

A method for controlling fuel circulation in a diesel type engine using carbonaceous aqueous slurry fuels, carbonaceous emulsion fuels or mixtures thereof, the diesel type engine including a fuel circulation system and a fuel injection system which is fluidly connected to the fuel circulation system, the fuel circulation system comprising:

• at least one fuel feed pump comprising a positive displacement pump located in the fuel circulation system before the fuel injection system, the fuel feed pump configured to supply a controlled amount of carbonaceous aqueous slurry fuel to the fuel injection system;
• and
• at least one volumetric flow controller comprising at least one of a second positive displacement pump configured to operate in reverse as a positive displacement pressure let-down device, or a volumetric flow valve operated as a positive displacement pressure let-down device, the volumetric flow controller located in the fuel circulation system after the fuel injection system, the volumetric flow controller providing a controlled regulation of return flow/fuel system pressure from the fuel injection system from zero to maximum flow/pressure,
• the method includes the step of:
• adjusting the relative speed of the fuel feed pump and the volumetric flow controller to control at least one of:
• (i) fuel flow rate to prevent particle sedimentation in the fuel;
• (ii) changes to the fuel rheology and destabilisation by over working due to excessive circulation around the fuel system;
• (iii) fluid flow for fuel change over;
• or
• (iv) flow of flushing fluid and more efficient and quicker flushing of the fuel system.