Toro Andersen at 14:44, 23 March 2026

2026-03-23T14:44:16Z

Toro Andersen: /* Heavy Fuel Oporation */

2026-03-22T19:40:54Z

Heavy Fuel Oporation

← Older revision		Revision as of 19:40, 22 March 2026
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	The first problem was to heat the heavy fuel in the double bottom storage tanks, so that it could be pumped to the daily service tanks, then to heat again in these tanks so that the fuel would not cool and later to heat further so that the fuel could be cleaned and non-combustible products removed and then, to heat the fuel at the engine to reduce its viscosity, so that it could be pumped by the main engine fuel pump and injected into the engine cylinders, through the fuel spray valves in fine jets suitable for rapid and efficient burning.		The first problem was to heat the heavy fuel in the double bottom storage tanks, so that it could be pumped to the daily service tanks, then to heat again in these tanks so that the fuel would not cool and later to heat further so that the fuel could be cleaned and non-combustible products removed and then, to heat the fuel at the engine to reduce its viscosity, so that it could be pumped by the main engine fuel pump and injected into the engine cylinders, through the fuel spray valves in fine jets suitable for rapid and efficient burning.

	Secondly, non-combustible matter such as water, sand and noncombustible sludge had to be removed from the fuel. Centrifuges were developed and improved for this purpose; water and some of the heavier substances were removed by a preliminary centrifuge known as a purifier and then the fuel was reheated and passed through a second centrifuge, known as a clarifier, which removed some of the heavier asphaltines. A fuel system embodying these features is shown		Secondly, non-combustible matter such as water, sand and noncombustible sludge had to be removed from the fuel. Centrifuges were developed and improved for this purpose; water and some of the heavier substances were removed by a preliminary centrifuge known as a purifier and then the fuel was reheated and passed through a second centrifuge, known as a clarifier, which removed some of the heavier asphaltines. A fuel system embodying these features is shown in Fig. 1. With such a system the modern slow speed marine Diesel engine can burn fuel oils up to 3,000 seconds viscosity with reliability, although there are some drawbacks. In general, for an engine burning more than 30 tons of fuel per day, an extra junior engineer is carried to maintain the centrifuges and clean them as necessary. The fuel oil has to be heated to a temperature of between 185 deg. F. and 210 deg. F. to obtain a sufficiently low viscosity for the satisfactory spraying of the fuel and the injector nozzles have to be water cooled in order to prevent the formation of carbon trumpets around the small holes of the injector. On the Doxford engine, the author’s company uses a C.A.V. injector which is of the differential-spindle spring-loaded type of high precision, made by a company specializing in the manufacture of fuel pumping and injection components. The arrangement of this injector and of its water cooling is shown in Fig. 2. The fuel pump is of conventional design, the plunger having a helix on its forward end which is rotated by a rack and pinion to regulate the fuel quantity required, according to the speed and power of the engine. When using high viscosity fuels the fit or clearance of the fuel pump plungers in their barrels must be somewhat slacker than that necessary for light Diesel fuels, which can penetrate past tighter fuel pump plungers to lubricate them. Heavier fuels do not penetrate so readily and so do not lubricate tight plungers which may seize in consequence.

	in Fig. 1. With such a system the modern slow speed marine Diesel engine can burn fuel oils up to 3,000 seconds viscosity

	with reliability, although there are some drawbacks. In general, for an engine burning more than 30 tons of fuel per day, an extra junior engineer is carried to maintain the centrifuges and clean them as necessary. The fuel oil has to be heated to a temperature of between 185 deg. F. and 210 deg. F. to obtain a sufficiently low viscosity for the satisfactory spraying of the fuel and the injector nozzles have to be water cooled in order to prevent the formation of carbon trumpets around the small holes of the injector. On the Doxford engine, the author’s company uses a C.A.V. injector which is of the differential-spindle spring-loaded type of high precision, made by a company specializing in the manufacture of fuel pumping and injection components. The arrangement of this injector and of its water cooling is shown in Fig. 2. The fuel pump is of conventional design, the plunger having a helix on its forward end which is rotated by a rack and pinion to regulate the fuel quantity required, according to the speed and power of the engine. When using high viscosity fuels the fit or clearance of the fuel pump plungers in their barrels must be somewhat slacker than that necessary for light Diesel fuels, which can penetrate past tighter fuel pump plungers to lubricate them. Heavier fuels do not penetrate so readily and so do not lubricate tight plungers which may seize in consequence.

	As is well known, the Doxford engine uses a fuel system where a multi-ram pump pumps the fuel at high pressure into fuel bottles or accumulators, usually one for each cylinder and, when a small valve is lifted by a cam on the camshaft, the fuel in these high pressure bottles flows rapidly to the fuel injectors and lifts the differential needles to spray the fuel into the cylinder. Steam tracer pipes are used alongside the fuel piping to maintain or increase the temperature of the fuel in the piping between the fuel pump, accumulator bottles, and fuel injectors. This common rail system is very quiet and simple in operation and although having had considerable experience with jerk type fuel pumps in the past, the author		As is well known, the Doxford engine uses a fuel system where a multi-ram pump pumps the fuel at high pressure into fuel bottles or accumulators, usually one for each cylinder and, when a small valve is lifted by a cam on the camshaft, the fuel in these high pressure bottles flows rapidly to the fuel injectors and lifts the differential needles to spray the fuel into the cylinder. Steam tracer pipes are used alongside the fuel piping to maintain or increase the temperature of the fuel in the piping between the fuel pump, accumulator bottles, and fuel injectors. This common rail system is very quiet and simple in operation and although having had considerable experience with jerk type fuel pumps in the past, the author

Toro Andersen: Created page with "P. JACKSON, M.Sc., M.I.Mech.E. (Member of Council) * The paper describes the development of the large marine Diesel engine over the past decade with respect to: 1) The burning of high viscosity fuels. 2) The supercharging of the two-cycle engine by turboblowers. 3) The development of very large engines. The paper is concerned particularly with the development of the Doxford engine in these various respects and particularly with regard to the experiences of the P typ..."

2026-03-22T19:40:14Z

Created page with "P. JACKSON, M.Sc., M.I.Mech.E. (Member of Council) * The paper describes the development of the large marine Diesel engine over the past decade with respect to: 1) The burning of high viscosity fuels. 2) The supercharging of the two-cycle engine by turboblowers. 3) The development of very large engines. The paper is concerned particularly with the development of the Doxford engine in these various respects and particularly with regard to the experiences of the P typ..."

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The Doxford Direct Drive Diesel Engine - Revision history

Toro Andersen at 14:44, 23 March 2026

Toro Andersen: /* Heavy Fuel Oporation */