Power plants FG WILSON
Fuel supply
To facilitate starting and maintain engine operation, the power system must reliably provide fuel supply. This requires, at a minimum, a small daily volume tank (usually located at the base of the generating set and called built-in) located near the unit. Since this tank is rated for 8 hours of operation, it is often equipped with an additional remote fueling system, which includes the main tank, as well as the corresponding pumps and piping system. Usually, to increase the duration of work, main tanks of increased capacity are mainly used.
This is especially important for generator sets operating in standby mode in order to ensure their independence from regular topping up. In a situation where the use of a backup generator is required, the fuel supply process may be interrupted.
Location of the tank
To simplify the fuel supply system, the fuel tank should be located as close as possible to the engine. It is usually safe to store diesel fuel in the same room as the engine, because diesel fuel is not as flammable and volatile as gasoline. Therefore, if the fire safety rules of the building allow such fuel storage, the fuel tank can be located along or at the base of the generator set, as well as in an adjacent room. If this is not possible, the main fuel tank should be located outside the building. If the tank is located outdoors, it must be protected from freezing, as this increases the viscosity of the fuel. The location should allow refueling, cleaning and inspection of the tank. The tank can be located both above and below ground level.
Remote fuel supply systems
The manufacturer recommends using one of five types of remote fuel supply systems:
- System 1: A system in which the main fuel tank is located below the daily volume tank.
- System 2: A system in which the main fuel tank is located above the daily volume tank.
- System 3: A system where the generating set is requested from a main tank set at a fairly high level.
- System 4: A system in which fuel is pumped from a separate main tank to a daily volume tank.
- System 5: A system where a separate daily volume tank is fed through a pumped system from the main tank.
System 1:
The main tank is located below the daily volume tank. In this system, fuel is supplied by means of a pump from the main tank to the daily volume tank, which is built into the base (Figure 10.1.)
Figure 10.1. Typical scheme of the fuel system 1
This fuel supply system consists of the main tank (position 1), which is below the level of the built-in tank, remote fuel system controls (position 2), located on the control panel of the generator set, electric AC fuel pump (position 3), level indicators of fuel in the built-in tank (position 4), the extended ventilation outlet of the built-in tank (position 5), the fuel supply line (position 6), the return line (position 7) and the fuel filter (position 8) at the pump inlet.
The operation in automatic mode is as follows: the low level of fuel in the built-in tank is registered by the corresponding sensor. The pump starts pumping fuel from the main tank into the built-in fuel supply line. To ensure that the engine is supplied with clean fuel from the main tank, it is filtered before being fed to the electric fuel pump. When the main tank is full, this event is registered by the corresponding level sensor and the pump is turned off. If the tank overflows, the excess fuel is drained into the main tank through the return pipe.
When using this system, the main tank must have the possibility of draining excess fuel in case of overflow (through the return pipeline), an extended ventilation outlet 1.4 m long to prevent overflow through this outlet, fuel level gauges on the built-in tank. The possibility of manual filling should not be available. All other connections on top of the tank must be sealed to prevent leakage. Fuel system 1 is not designed to work with standard polyethylene tanks installed on small generator sets of the F.G. Wilson. In this case, an additional metal tank and control system series 2001 (or higher) are required.
When locating the main tank, consider that the pump must provide a maximum suction lift of approximately 3 meters, and that the maximum resistance due to friction losses in the return line must not exceed 2 ft/sq. inch.
System 2:
The main tank is located higher than the built-in tank. In this system, fuel under the influence of gravity flows from the main tank to the built-in (Figure 10.2.)
Figure 10.2. Typical scheme of the fuel system 2
The main elements of this system are the main tank (position 1), which is located above the built-in tank, remote fuel system controls (position 2), located on the control panel of the generator set, a valve with a direct current drive (position 3), fuel level indicators for the built-in tank (item 4), the extended return line and vent line (with constant rise) of the built-in tank (item 5), the fuel supply line (item 6), the fuel filter (item 7) and the isolation valve of the main tank (item 8).
The operation in automatic mode is as follows: the low level of fuel in the built-in tank is registered by the corresponding sensor. The DC valve is open and fuel flows from the above main tank into the inline tank by gravity. To ensure that the engine is fed with clean fuel from the main tank, it is filtered before being fed to the DC valve. When the main tank is full, this event is registered by the corresponding level sensor and the valve closes. In case of overflow of the tank or excess pressure, excess fuel flows into the main tank through an extended ventilation pipeline.
When using this system, the built-in tank must have the ability to drain excess fuel when overflowing (via a return pipe) and fuel level gauges on the built-in tank. The possibility of manual filling should not be available. All other connections on top of the tank must be sealed to prevent leakage. Fuel system 2 is not worth working with standard polyethylene tanks installed on small generator sets of the F.G. Wilson. In this case, an additional metal tank and control system series 2001 (or higher) are required.
Distance “A” in Figure 10.2 is limited to 1400 mm for all generator sets with metal built-in tanks, except for models P550 – P880E, where this distance can be increased to 1600 mm and models DDC135 – DDC330E, where this distance is limited to 800.
System 3:
This system allows the use of a motor fed directly from the main tank located at a certain level, bypassing the built-in tank (Figure 10.3).
Figure 10.3. Typical scheme of the fuel system 3
The main elements of this system include the main fuel tank (position 1), the fuel supply pipeline (position 2), the return fuel pipeline (position 3) and the isolation valve of the main tank (position 4).
The system works as follows: With the isolation valve open, fuel is fed into the engine under the influence of gravity. Excess fuel is returned to the main tank through the return pipe.
The distance “A” in Figure 10.3 is limited by the following values:
| Model | Height |
| Р22 — Р275Е | 3300 mm |
| GEP30 — GEP200 | 3300 mm |
| РЗОО — Р880Е | 6000 mm |
| Р850 — Р2200Е | 2500 mm |
| DDC400 — DDC1740Е | 1200 mm |
| ВВС135 — ВВС330У | 800 mm |
| Cummins (series К) | 2500 mm |
| Сaterpillar (series 3500) | 3000 mm |
| Paxman | 3600 mm |
Note: Above are maximum height values. These values may be reduced depending on limitations imposed by pipe size, length and return pipe clogging.
System 4:
Some installation conditions may require a system where the fuel is pumped from a free-standing main tank (Figure 10.4). This system with forced fuel supply should be used if it is not possible to ensure the supply of fuel from the main tank to the built-in one.
Figure 10.4. Typical scheme of the fuel system 4
The main elements of this system are the main tank (position 1), which is located above ground level, the remote fuel system controls (position 2), located on the control panel of the generator set, the AC fuel pump (position 3), the valve with a direct current drive ( position 4), fuel level indicators in the built-in tank (position 5), fuel supply line (position 6), extended return pipe and ventilation pipe (with constant rise) of the built-in tank (position 7), fuel filter (position 8) and isolation valve of the main tank (position 9).
The operation in automatic mode is as follows: the low level of fuel in the built-in tank is registered by the corresponding sensor. The DC valve is open and the pump begins to pump fuel through the pipeline from the main tank to the built-in. To ensure that the engine is fed with clean fuel from the main tank, it is filtered before being fed to the DC valve. When the main tank is full, this event is registered by the corresponding level sensor, the pump is turned off and the valve is closed. In case of overflow of the tank or excess pressure, excess fuel flows into the main tank through an extended ventilation pipe.
When using this system, the built-in tank must have the ability to drain excess fuel when overflowing (via a return pipe) and fuel level gauges on the built-in tank. The possibility of manual filling should not be available. All other connections on top of the tank must be sealed to prevent leakage. Fuel system 4 is not designed to work with standard polyethylene tanks installed on small generator sets of the F.G. Wilson. In this case, an additional metal tank and control system series 2001 (or higher) are required.
Note that the distance “A” in Figure 10.4 is limited to 1400 mm for all generating sets with metal built-in tanks, except for models P550 – P880E, where this distance can be increased to 3700 mm, and models DDC135 – DDC330E, where this distance is limited to 800. , that the maximum resistance due to friction losses and the height of the return pipe should not exceed 2 ft/sq. inch.
System 5:
In some cases, it is necessary to use a separate daily volume tank that is forcibly filled from the main tank (Figure 10.5).
Figure 10.5. Typical scheme of the fuel system 5
The main elements of this system include the main fuel tank (position 1), the daily volume tank (position 2), remote fuel supply system controls (position 4), located on a separate user panel, the AC fuel pump (position 4), fuel valve with direct current drive (position 5), fuel level indicators in the daily volume tank (position 6), fuel supply pipe to the daily volume tank (position 7), fuel supply pipe to the engine (position 8), return displacement tank line (item 9), displacement tank extended vent and return pipe (constant rise) (pos. 10), displacement tank isolation valve (pos. 11), fuel filter (pos. 12) and main tank isolation valve (item 13).
The operation in automatic mode is as follows: the low level of fuel in the daily volume tank is registered by the corresponding sensor. The DC valve is open and the pump starts pumping fuel through the pipeline from the main tank to the daily volume tank. To ensure that the engine is fed with clean fuel from the main tank, it is filtered before being fed to the DC valve. When the daily volume tank is full, this event is registered by the corresponding level sensor, the pump is turned off and the valve is closed. If the daily volume tank is overfilled or there is excess pressure, excess fuel is drained into the main tank through an extended ventilation pipeline. With the fuel tank isolation valve open and the engine running, fuel is fed from the fuel tank to the engine and excess fuel is returned to the fuel tank.
The daily volume tank must be designed taking into account the height of the installation “A” of the main tank and the friction loss in the pipeline, when the tank overflows. Usually, the height of the tank installation is 3 meters. However, it may vary depending on the specific option. In general, the daily volume tank, taking into account the height of the installation, should be designed in accordance with part 5 of BS799. The distance “A” in Figure 10.5 is limited by the following values:
| Model | Height |
| Р22 — Р275Е | 3300 mm |
| РЗОО — Р880Е | 6000 mm |
| Р850 — Р2200Е | 2500 mm |
| DDC400 — DDC1740E | 1200 mm |
| DDC135 — DDC330E | 800 mm |
| Cummins (Series К) | 2500 mm |
| Caterpillar (series 3500) | 3000 mm |
| Paxman | 3600 mm |
In case of overflow of the daily volume tank, the main tank of engines with injectors may overflow fuel in the cylinders. In this case, it is important that excess fuel is removed from the cylinders before starting.
Tank construction
Fuel tanks are usually made of welded sheet steel or reinforced plastic. If an old fuel tank is used, make sure it is made of the correct material. It must be thoroughly cleaned of rust, scale and foreign deposits.
Connections of suction and return pipelines of fuel should be spaced as far as possible to avoid recirculation of hot fuel. It also ensures separation of gases from fuel. The intake lines must have an extension tube below the minimum fuel level in the tank. The lower point of the tank must be equipped with a drain valve or plug and be located in an accessible place for periodic removal of condensate and sediment. You can also insert a hose for suction of water and sediment through the filler neck of the tank.
The filler neck of the main fuel tank must be located in an easily accessible place. A screen with a mesh size of approximately 1.6 mm (1/16 inch) should be inserted into the tank neck to prevent foreign matter from entering. The filler cap or highest point of the tank must communicate with the atmosphere to maintain atmospheric fuel pressure and provide pressure relief in the event of fuel volume expansion during temperature rise. The highest point of the tank should be connected to the neck to reduce the possibility of air retention and fuel splashing when filling the tank with it. The tank can be equipped with a fuel level indicator or a visual arrow indicator, or a remote electric one.
Fuel tank capacity
Fuel supply piping materials must be compatible with any type of fuel, for example, made of steel tubes or flexible hoses that can withstand the effects of the environment.
The fuel supply and return lines must be the same size as the engine fittings, and the excess fuel drain line must be one size larger. For larger values of the length of the pipeline or at low temperatures, the dimensions of these pipelines must be increased to ensure the required flow. Flexible tubing must be used to connect to the motor to avoid damage or leakage due to vibration.
The fuel supply line must provide fuel intake from a level not less than 50 mm (2 inches) from the bottom of the tank at the highest point, away from the drain plug.
The volume of the daily volume of the fuel tank
The capacity of the daily fuel tank is determined from the expected fuel consumption and the duration of operation between filling intervals. In particular, for standby generators, the required duration of operation will determine the availability of a fuel delivery service.
In addition, the volume of the tank must be sufficient for operation in low temperature conditions, since some types of engines return the hot fuel used to cool the injectors. This is especially critical in large generator sets of models P852 – P2200E, where the temperature of the returning fuel can increase significantly. This can cause a decrease in engine parameters, as the fuel tank in this case will not be able to provide sufficient heat removal.
For such generators, in order to absorb excess heat, the daily volume tank size, in addition to the standard fuel volume, should have the following values:
| Model | Excess capacity | |
| With Fuel Cooling | without Fuel Cooling | |
| P852 — P1100E | 1500 liters | 3000 liters |
| P1250 — P1650E | 2250 liters | 4500 liters |
| P1700 — P2200E | 3000 liters | 6000 liters |