This report is the result of the bachelor project: “Registration of fuel oil-consumption - utilization in operation”. The foundation of the project is laid on the Multi Role Emergency Rescue and Response Vessel (MRERRV) Esvagt Observer, which is standby at the Beryl Oil Field in the English sector of the Northsea.
It is important to take in consideration, what the purpose of registration of fuel oil- consumption is. In the case where it is a MRERRV the vessel seldom sails at constant speed, which results in an alternating load of both the diesel generators and the main engines. It makes sense that the registration of fuel oil-consumption is transmitted into a volume flow i.e. in [l/h] on most vessels, which runs on an even load, for a longer period. The crew is then able to compare speed and volume flow and consider if the circumstances are normal. In the case with alternating load however, it is not that simple due to the fact, that the speed of the vessel never is constant for a longer period. In this case it is more relevant to compare the volume flow of fuel oil with the load of each engine; thereby the crew will get a specific fuel oil-consumption. [l/kWh]
On the diesel generators the load is constantly measured, as power delivered to the electrical system [kW]. Therefore it is easy to let the management and control system calculate the specific fuel oil-consumption. For flow measuring on the diesel generators it is possible to purchase a set of turbine flow measurement transmitters that fits directly on to the diesel engines and are constructed to function on exactly these engines.
On the Main engines the load is not measured. In this case it is necessary to install a torsiometer, which measures the twist of the propeller shaft. From this the torque can be calculated [Nm] and compared to the rotation speed of the shaft [s-1]. Then the load on the propeller shaft can be calculated [kW]. For flow measuring on the main engines, it is appropriate to use “clamp-on” equipment, because the fuel oil-pipes that lead to the main engines, are made of solid steel the entire way, and the installation will then be easier with “Clamp-on” equipment. In this case, ultrasound transmitters of the “time transit” principle is the most applicable solution.
Most of the measuring equipment has a measuring fault of less than 2%. This fault is acceptable in this case, but when considering the choice of measuring equipment, it is important to take the equipments “turn-down” in consideration. The turn-down is the ratio between the maximum flow, and the minimum flow where the stated fault is still valid. Therefore the ratio between the maximum and minimum flow of fuel oil, when measured, cannot be greater, than the turn-down of the measuring equipment.