iCenta and Metri Pro-Lite and the Hybrid Passenger Ferry – Ultrasonic Diagnosis
We were called to consult on several flow applications on board a multi-million-pound new generation of catamaran hybrid passenger ferry. These fabulous low emission ferries will operate on the River Thames and be future proofed incase an ultra-low emission zone is introduced for river traffic.
The vessels designer identified a requirement for three flow measurements to be made. The first was on the diesel fuel consumption on the common rail engine. The second was for the battery cooling circuit and the third was the diesel engine cooling circuit. These ferries have a hybrid motor in each of the two hulls, so that was four measurement points per hull, eight in total. The battery cooling fluid was a water / glycol mix cooled indirectly via a heat exchanger, whilst the diesel engine cooling was raw sea water, drawn up and passed through a strainer. The pipework was all Nickel Copper alloy, DN25 (fuel lines) DN50 and DN100 line sizes for the two cooling circuits.
For the diesel flow measurement, a gear flow meter was already installed, but iCenta realised that it was sized incorrectly and was causing a significant pressure loss. A precision OVAL FlowPet 5G gear meter was selected for the task of flow measurement from the diesel flow.
Then the cooling circuits were surveyed, and the ultrasonic sensors were installed within the bilge, access was tight, the space was about 60 cm at its largest point and a person could not turn around. After a risk assessment and gas safety check, the ultrasonic meters were set-up and the sensors installed. It is in such space critical applications a quick setup and small meter, in a rugged bumper case is a definite advantage!
Both the Metri Pro-Lite and the Precision Flow PD190 measured the flow well, particularly on the water glycol mix for the battery cooling. However, it was found that as the engine approached full power, a great deal of entrained air was mixed into the engine cooling fluid which is not ideal for ultrasonic meters, or many other flow measurement technologies, for that matter. Entrained air is not a good conductor of heat and would therefore also affect the performance of the cooling circuit.
The ultrasonic flowmeters proved unsuitable (due to entrained air) on the diesel engine cooling circuit, so a different flow technology was required. This remains a natural strength of iCenta, we have all the flowmeter technologies, so we can honestly recommend the best flowmeter technology choice for a particular application, and we represent the best flow instrumentation from around the World.
In terms of diagnostics, the ultrasonics did give us valuable insight into the flow conditions. A combined Doppler – Transit time flow meter is available via iCenta, and this would have been a good application for that device, automatically switching between Doppler and transit-time techniques.
Metri Pro-Lite was fast to set up and easy to operate, having a backlit graphics display for use in low light conditions. Signal diagnostics are available so you can see the acoustic signals in real time. The meter, after the signal amplification is fully digitised, using correlation detection, has effectively become an industry standard signal processing technique for transit-time flowmeters. All these features really help when working with a range of fluids in demanding situations. The Metri Ultra Pro-Lite also sits in a powerful position in the market. Due to intelligent modern design, it is perfectly engineered to provide a capable clamp-on flowmeter, at a realistic cost to the user. iCenta recommend clamp-on ultrasonic flow meters on site, especially useful for verifying other meters, and for general spot flow readings. The meter also has a fully configurable datalogger for post testing analysis.
Initially we thought that it was a good application for ultrasonics, but due to entrained air on the diesel cooling water it was felt that a magnetic flowmeter was a better choice. Post trial, the new meters were correctly specified sized and delivered, so the overall solution involved Oval geared meters and C-Mag Comac Cal 316L Magnetic flowmeters.
