Modern fuel injection systems need to be protected from particles and water, causing wear on the system. Whilst particles cause abrasion inside the injector and high-pressure pump, water can lead to abrasion due to cavitation and to corrosion. Therefore the particles and water needs to be removed from the fuel.
A state-of-the-art fuel-water separator can reliably ensure a high purification by using multiple stages. The separated water is temporarily stored in collection space that could be a transparent bowl on a spin-on filter cartridge or a volume inside a fuel filter module.
The most commonly used method to remove the water from the collection space is the manual drain, operated by the driver of the vehicle. A drain screw is opened and the water removed. A step towards automatization is the semi-automatic drain, in which the driver is informed about the necessity to drain the water. Once the vehicle is at standstill and the engine switched off, the drain is activated by pressing a button in the vehicle. Both methods, the manual and semi-automatic drain have a disadvantage: The water needs to be collected and safely disposed because it is contaminated with hydrocarbons (HC), coming from die Diesel fuel.
A fully automatic drain system removes the water when the sensor detects a certain level in the water collection chamber. Since the drained water is usually not collected automatically (e.g. in an extra tank), it should be cleaned prior to the release into the environment. A suitable adsorber removes the HC from the water phase.
The water that is separated by the fuel-water separator can be either clear or turbid. The reason lays within the used fuel: Whilst low additivated fuels usually lead to a clear water phase, an ultra-low sulfur diesel (ULSD) contains a high amount of additives and the water will be turbid due to the formation of a diesel in water emulsion, containing highly stabilized and small diesel droplets. Why is this important? The solubility limit of diesel in water is reasonably low, approximately < 10 mg/l acc. EN ISO 9377-2 H53 but an emulsion contains in average > 200 mg/l HC with levels up to > 2500 mg/l.
Activated carbon (AC) is the commonly used material in either systems that are already running on the street or are in a concept status. Since several years, various developments regarding automatic drain systems describe that material as adsorber, but without the proof of function. Only little evidence is found in the literature, that activated carbon is actually suitable for this application. The presentation shows details about a novel adsorber material in comparison to activated carbons used to clean up the water prior to disposal....
Session: L19 - Liquid/Liquid Separation
Day: 24 October 2019
Time: 14:45 - 16:00 h