Oil Loading & Discharging with ALTOSONIC V

Innovation in custody transfer measurements
Flow measurement is the basis for oil custody transfer, whereby the parties involved want to know exactly what quantities they are buying or selling. The type of flow meters typically used are turbine meters and pd meters. KROHNE Altometer introduced a serious new alternative to the market, the ultrasonic flow meter system, ALTOSONIC V. The multi-beam flow meter is the first ultrasonic meter accurate enough for custody transfer. As the multi-beam ultrasonic flow meter has some major advantages over the conventional technologies, much is expected from this meter. The ultrasonic flow meter has the important advantage over turbine meters that it operates independent of the medium’s physical characteristics, and thus no longer requires product specific calibrations, and needs low maintenance as it has no moving parts. Compared to PD meters, ultrasonic flow meters are less bulky, can handle higher flow rates, and there is no danger the flow meter will obstruct the flow.

Oil loading & discharging

A good example of an application whereby ALTOSONIC V offers important benefits is the loading and discharging of oil products. After the exploration and after gas and water separation, the crude oil is transferred to an oil terminal. In those cases where more than one user (explorer) is connected to the same transportation pipeline, flow measurement is required for the allocation of crude oil of each participant. At the oil terminal it is stored before pumping into, for example, a crude oil carrier. While loading tankers from the terminal and discharging the crude oil into shore tanks it often concerns custody transfer or fiscal metering. For all these measurements an highly accurate flow meter is required.

Benefits ALTOSONIC V

One important benefit ALTOSONIC V offers, is that it can do bi-directional measurements. This means the same ultrasonic flow meter can be used for both loading and discharging. In addition, the flow meter can be used for multi-product measurements. After a product change no re-calibration is required. Thirdly, with one multi-beam ultrasonic flow meter two or more ships can be loaded and/or discharged with the same product. As it is not necessary to establish a new k-factors after changing products or to calibrate the flow meter at periodic intervals as there is no wear, the flow meter does not require a prover loop installation. An important advantage because of the limited space on a jetty and the less number of valves involved. Finally, ALTOSONIC V has a wide rangeability, required at the beginning of a batch for non splashing and at the end of a batch for ramping down. Therefore no new k-factor has to be established, different from the one of the flow rate during the whole of the batch. These features demonstrate the benefits the multibeam ultrasonic flowmeter has over turbine meters and PD meters.

Application ALTOSONIC V in practice

An example where ALTOSONIC V is used for offloading and discharging cumene concerns a DOW Chemical plant in Terneuzen in The Netherlands. A number of multibeam ultrasonic flow meters are in operation at North Sea oil platforms in Norway and the UK for allocation and fiscal measurements. In Germany a number of 10 ALTOSONIC V is installed on a multi-product transport pipeline. Another example concerns a Dutch refinery where the flowmeter is used for internal measurements for e.g. tax purposes of high viscous fuel oil. For internal measurements the refinery requires there can never be any blockings in the flow, which could obstruct the internal production process.

Key Words: Flow,oil, ultrasonic, charge, custody transfer, turbine, PD, cumene
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