4.2 Events in full running operation
Various events (troubles) occurred during the full running using the emulsified fuel, and major two ones are as follows:
4.2.1 Power loss (black out)
The ratio of the fuel oil in the emulsified fuel is 77% (＝100/(100+30)) of the total discharge by the fuel injection pump in the case of the water addition ratio of 30% in the test, and is 23% reduction with respect to the original fuel discharge. Thus, the increase in capacity of the fuel injection pump was considered. Based on the estimation from the affordability of the capacity and the load in the peak power consumption, the capacity was judged to be sufficiently affordable on the operational control under the load limit of 300kW.
However, during the navigation, the influence of the starting current on the electric generator is large when the large motor is started/stopped, and in addition to the air-conditioning timing with much power consumption on board the ship, the power load was unexpectedly and temporarily higher. As a result, the governor of the diesel engine was operated and the fuel injection pump was operated to the limit of the torque limiter to maintain the engine speed of the diesel engine; however, in the actual condition, the fuel became insufficient as described above, the engine speed could not be maintained, the protective system was operated, leading to the power loss (black out).
Fig.5 show a graph to indicate the relationship between the load on the diesel engine measured during the continuous operation using the emulsified fuel in the ocean navigation and the rack scale of the fuel injection pump. The solid line indicates the relationship during the A-oil mono-fuel combustion, while the broken line indicates the plotted data during the operation using the emulsified fuel. The load on the diesel engine shown by the axis of abscissas corresponds to the onboard power load, while the rack scale of the axis of coordinates can be converted into the change in the fuel discharge of the fuel injection pump (the discharge is increased if the scale is increased), and thus, the difference in the rack scale between the solid line and the broken line on the graph at the same load is substantially equivalent to the quantity of water addition, and it is thus shown that the rack scale of 23mm equivalent to the load of 100% can cope with only about 75% of the load (300kW).
The power load at that time was temporarily above 350kW. The spare diesel engine for the electric generator was immediately started without any further trouble. This is attributable to the result that the operation was started without any countermeasures such as the increase in capacity of the fuel injection pump. The manual for countermeasures such as the reinforcement of the monitoring of the operation and the stop of the power supply to the equipment low in importance when the power load is high was additionally prepared, and the operation was continued.
4.2.2 Swelling of oil in waste oil tank
Leakage of oil from the fuel injection valve during the full running using the emulsified fuel was supported to be treated together with the waste oil containing water in the engine room.
In the general treatment method of waste oil onboard ships, the waste oil generated mainly in the engine room is collected in the waste oil tank, and heated with steam, etc., the water is evaporated to increase the oil concentration, and the waste oil is incinerated in the incinerator, etc.
Also, in this case, the waste oil was heated as usual; however, the trouble occurred, in which the oil level in the waste oil tank rose instantaneously and abnormally, the waste oil overflowed the waste oil tank, and flowed into the waste oil incinerator room.
