Fuel supply system for combustion engines

Fuel supply system for main and auxiliary engines

The fuel is pumped to the HFO settling tank from the store tanks by a transport pup and transferred to the daily service tank with HFO separators, which remove the remaining water and solid particles from the fuel. During normal operation, auxiliary and composite boilers take fuel from the HFO settling tank, although they can also pump fuel from the daily service tank if necessary. However, the fuel returned from the boiler burner units is only to the settling tank.
Low Sulfur Fuel Oil (LSFO) sedimentation and daily tanks are adjacent to the fuel oil tanks and are connected in parallel to the fuel supply system via normally closed valves. In both LSFO tanks, the return fuel pipe has blinds and isolation valves.
Main and auxiliary generator engines, and an auxiliary boiler designed to burn fuel oil as the primary fuel. In normal operation, one or more HFO separators are used whose performance slightly exceeds the fuel consumption of the installations in operation. Excess fuel, from the daily tank, is transferred back to the settling tank.
All outlets of fuel settling, and daily service tanks are equipped with remote quick-closing valves that are pneumatically controlled remotely from a panel in the fire control station. Once the quick-closing valves are actuated, each such valve will need to be reopened in each tank manually after separation.
All fuel settling and daily settling tanks are equipped with self-closing drainage / check valves for checking and draining the water at the bottom of the tank, which is routed through pipes to the fuel drainage tank.
NOTE: Fuel settling, and daily settling tanks must be inspected daily for water and the hopper tank must be inspected before it is put into service. Any water in the tanks must be drained through self-closing drainage / control valves to the drained fuel tank.
Steam heating coils are installed in all fuel oil tanks and all pipelines leading from them are equipped with steam tracing pipes.
Fuel is supplied to the main and generator engines via a FO supply and booster unit consisting of operating / backup fuel oil supply pumps, operating / backup fuel booster pumps, filters, heaters, supply flow meters, return flow meters and a viscosity control unit. The module also includes two diesel feed pumps.
The fuel inlet to the fuel preparation unit is located through a three-way valve which, depending on its position, will supply HFO or DO. The fuel is then supplied through a suction filter to a pair of supply pumps, one of which is on standby. The rebooster line of the supply pump has a pressure control valve and a cooler.
Fuel is discharged from the supply pumps through an automatic backwash filter into the mixing tank. The automatic backflush fuel filter is an electrically operated self-cleaning device. This filter can be bypassed by routing it through a basket-type filter. Fuel service is discharged from the automatic cleaning filter into the drained fuel tank.
From the filter, the fuel enters the mixing tank through a flow meter. The fuel returned from the main and generator engines through the dedicated flow meters, depending on the position of the three-way valve, can be mixed with fresh fuel in the mixing or returned to the HFO daily service tank.
In the mixing tank, all the formed gas is discharged into the drainage fuel tank. The mixing tank is also equipped with a safety valve, through which gas can be discharged into the HFO daily service tank.
The fuel is then taken from the mixing tank by circulating booster pumps, one of which is operated by the other and fed to a pipeline with a safety valve, to the fuel heaters, one of which is operated by the other, which is kept in reserve. Here, the fuel is heated using steam as a heating medium to a temperature corresponding to a viscosity of around 12 cSt. The fuel side of the heaters shall be fitted with safety valves set to operate at 1.5 MPa which discharge the fuel into the mixing tank discharge line.
The heated fuel oil then passes through a viscosity meter that controls the fuel temperature by regulating the steam supply valve through which steam is supplied to the heaters. If diesel fuel is used, then the fuel can be routed through the cooler as needed. Fuel is fed from the viscosity meter through the duplex filter to the main engine and through the flow meter to the generator engines.
Fuel is supplied to the main engine through a quick-closing valve on the engine intake manifold. The pressure control valve maintains the proper fuel pressure at the engine inlet, allowing excess fuel to bypass the engine and return to the fuel booster pumps.
Fuel consumption of generator engines is calculated by subtracting the flow meter reading of the generator engine fuel supply system. The main engine consumption is determined from the total flow through the main fuel flow meter (located behind the supply booster pumps) minus the generator's calculated fuel consumption.
The high-pressure fuel pipes of the main engine are encased in a protective hose with a steel braid. Any leakage in the high-pressure pipeline to the collection tank mounted on the side of each high-pressure pump. Each collection tank is equipped with a liquid level alarm that activates the alarm and monitoring system alarm and activates the puncture valve at the top of the respective injection pump.
CAUTION: When the puncture valve is running, the supply of high-pressure fuel from the pump is stopped immediately, so that fuel is not injected into the cylinder and engine power is reduced. Therefore, the engine speed must be reduced immediately.