FI70299B - BRAENSLESYSTEM FOER MARINA DEISELMOTORER - Google Patents

Description

1 70299

Fuel system for marine diesel engines

The present invention relates to a fuel system for marine diesel engines comprising at least one fuel tank, a mixing vessel for mixing fuel from the fuel tank with heated, non-engine fuel, and at least one feed pump for supplying mixed fuel to the engine.

For economic reasons, low-quality fuel oil blends containing both heavier and lighter hydrocarbons have recently been used to run marine diesel engines. In order for these blends to be used as fuel in diesel engines, they must be heated to about 150 ° C to achieve a suitable viscosity for injection into the engine. Since the amount of fuel recycled through the feed pump and the mixing vessel is 2-3 times greater than the engine consumption, fuel returned from the engine is fed to the mixing vessel at a temperature that exceeds the boiling point of the lighter fractions of fuel. Therefore, gases are formed in the mixing vessel connected to the atmosphere, which separate and escape into the air. These gases contain a large amount of combustible hydrocarbons with a high calorific value.

In addition to the loss of large amounts of energy in this way and the pollution of the environment, deposits containing heavier fractions are formed in the mixing vessel. In addition, the high temperature in the mixing vessel (above 100 ° C) results in the feed pump having to operate under difficult suction conditions because the static pressure between the mixing vessel and the feed pump is lower than the fuel vapor pressure. If flow meters, strainers and the like are placed before the feed pump, the pressure drop will further increase, causing cavitation in the feed pump. In the worst case, the free gases in the system lines can interfere with the 70299 engine's injection pumps and significantly degrade the combustion process in the engine.

It is an object of the present invention to obviate the disadvantages of the previously known fuel system and to provide a fuel system in which virtually all combustible fractions of fuel are recovered, in which the feed and injection pumps operate without interference and wear, and in which the mixing vessel can be placed in a relatively low position on board. when its dimensions can be considered small.

To achieve this object, the invention is characterized by what is stated in the claims.

The accompanying figure schematically shows a fuel system according to the invention.

Tank 1, which contains fuel oil consisting of a mixture of both lighter and heavier fractions, is installed on a vessel whose diesel engine is run on said fuel oil after it has been heated. An oil of about 80 ° is fed under its own pressure to a pumping device comprising two pumps 3 and 4, one of which (4) is a backup pump which is switched on in the event that the other stops operating. The pump 3, the capacity of which many times exceeds the maximum oil consumption of the engine 2, supplies oil under pressure through a flow meter 5 to a hermetically sealed pressure tank 6, where it is mixed with oil not consumed in the engine and therefore fed from the engine to the pressure tank.

Due to the fact that the oil contains gaseous components in the pressure tank 6 at the prevailing temperature (about 130 ° C), gases accumulate in the upper part of the pressure tank. However, since the pressure in the pressure vessel is kept relatively high and exceeds the vapor generation pressure of the pressure vessel, engine 2 and the pressure circuit comprising the feed pump device described below, only a small amount of these fractions are gasified 3 70299. When the amount of gas in the pressure tank 6 has increased so that the oil in it is below a predetermined level, the level sensor 8 is actuated, which then opens the valve 9 in the line 10 between the pressure tank 6 and the tank 1 so that the gases in the pressure tank can be discharged without polluting the environment. back to the tank 1.

The overpressure of the pressure vessel 6 is kept essentially constant by means of an automatically acting pressure control valve 11 connected over the pumps 3 and 4. The pressure tank is supplied with exactly the amount of oil corresponding to the current consumption of the engine 2, despite the fact that the capacity of the pump 3 is substantially higher. The oil which is not fed into the pressure tank is therefore returned to the suction side of the pump 3 via the valve 11 and circulated several times through the pump.

In order to ensure good mixing of the oil supplied from the pressure vessel 6 and to keep the gases therein in liquid form, a static mixer 12 is connected to the outlet of the pressure vessel 6.

The suction side of the pump device consisting of two supply pumps 14 and 15 (one of which is a backup pump 15) is connected to the outlet of the mixer 12, and the pressure side of the pump device is connected to the injection device 18 of the motor 2 via a heating device 16 and a viscometer 17 (and is about 3 times larger than this), which means that a relatively large amount of oil not consumed in the engine is returned to the pressure vessel 6 via line 7. In device 6, the oil is heated to about 150 ° C, which is its maximum temperature when introduced into the engine.

If both pumps 3 and 4 would stop functioning, can be a valve 13 which is connected to a conduit between the pump inlet side of the gauge 5 the output, and the valve 9 is manually opened, the feed pump 14 (or 15) can suck the oil pressure 4 70299 tank, which must oil at its own pressure directly from the tank 1 higher on board and which is at atmospheric pressure due to the open valve 9.

Parts 3-6, 8, 9, 11-13 with their associated wires can be more conveniently connected to the control and monitoring panel (not shown) and connected as a replacement unit (module) 19 to the tank 1, the engine 2 and a separate unit (module) 20 consisting of parts 14-16. between.

Although only one embodiment of the invention has been described above and shown in the drawing, it should be understood that the invention is not limited to this embodiment, but is limited only by the claims.

Claims (5)

5,70299 A fuel system for marine diesel engines comprising at least one fuel tank (1) and a mixing vessel (6) for mixing fuel from the fuel tank with heated fuel not consumed in the engine (2) and at least one feed pump (14, 15) for supplying mixed fuel to the engine , characterized in that the mixing vessel consists of a pressure vessel (6) connected to at least one pump (3, 4) for supplying fuel to the relatively warmer fuel in the pressure vessel under pressure and which, together with the motor (2) and the supply pump (14, 15) a system for maintaining a pressure in excess of the vapor generation pressure of the system to keep the flammable gases in liquid form. Fuel system according to Claim 1, characterized in that the capacity of the feed pump (14, 15) is substantially greater than the fuel consumption of the engine. Fuel system according to Claim 1 or 2, characterized by a pressure relief valve (11) connected over the supply pump (3, 4). Fuel system according to one of Claims 1 to 3, characterized by a static mixer (12) connected between the pressure tank (6) and the supply pump (14, 15). Fuel system according to one of the preceding claims, characterized by a sensor (8) which senses the fuel level in the pressure tank (6) and acts on a predetermined low level on the valve (9) to remove gas trapped above the fuel in the pressure tank, preferably back into the fuel tank (1).