Edwin Schuirink, Technical Product Manager, VAF instruments presentation during the 2015 GREEN4SEA Forum
Efficiency of ships is becoming more important, as fuel costs are relative high and the care for the environment is more and more on the agenda of IMO, EU and ship owners. A successful and effective efficiency improvement project requires that vessel efficiency is being monitored after implementation of new technologies and measures. Application of Torque sensors and Thrust & Torque sensors in combination with an efficiency monitoring system and flow meters on board of your vessels will help to make your project a success.
Hull and propeller efficiency monitoring is quite a serious issue, since hull and propeller condition do have a major influence on your fuel consumption. The main subject of this presentation is the flow meters, the torque sensors and our state of the art thrust and torque sensor, which allow you to monitor hull and propeller fouling. First of all I would like to present you the torque sensor, T-Sense which is on the market now for almost 5 years.
It contains an optical sensor that can be installed by the shipyard or by the owner. One of the big advantages of the optical sensor is that you don’t have to recalibrate the system every 6 months. Our system doesn’t need frequent recalibration, its ok when you do it every year or 2 years. More than 600 systems have been sold and about 60% is together with VAF PT2 flow meters which include pulse, sensor and PT100 temperature sensor. The optical sensor, contains a detector cell which is divided to 4 sections A, B, C, D and also a LED, which is illuminating the detector cell. By measuring the illumination of this highly accurate cell we calculate the torque and also the thrust on the shaft.
When it comes to efficiency monitoring, we have a few options to choose from: The first of them is the PEM2 touch screen, which is a quite basic touch screen showing you torque, shaft speed and rpm and also average torque and shaft speed and rpm. So this is how it looks like.
We have the torque sensor, we have a control box and the control box is connected to touch screen.
The next monitoring system is the PEM4-efficiency monitoring system. When using the PEM4 you have access to many additional efficiency monitoring features: first of all you can connect the T-Sense torque sensor again. Subsequently you can connect a maximum of 12 PT2 flow meters, making it able to monitor a maximum of 6 consumers like main engines, like gensets, maybe a boiler or even lube oil consumption. You can also have an input of a speed log, an input of GPS and even there is a shaft generator 4-20 mA power level input.
We put all the signals together in the signal processing unit and we have a nice touch screen showing all the KPIs which will interest you, because a lot of them are dealing with fuel consumption, like for example specific fuel oil consumption (SFOC) of the main engine, fuel consumption per nautical mile, but also an engine load diagram, power ship speed diagram etc. Last but not least there is also a Modbus output to your AMS system, the alarm and monitoring system on board the ship.
The TT-Sense sensor is designed for not only monitoring the torque and the power on the propeller shaft, but also the propeller’s thrust. The big difference is that this sensor is able to accurately measure the thrust on the propeller shaft and that it is the only sensor on the market which is able of doing so.
Below you can see the displacement Δy at the shaft due to torque and the very small displacement Δx due to maximum thrust. We also had to take into account elongation of the shaft due to temperature increase and find an algorithm for it. All together it makes it a very difficult story but we managed to succeed and to have a very accurate Thrust sensor able to do measurements with accuracy far below 1%. Just to imagine we need accuracy of 25 nanometres, which is equal to 5 second of beard growth. Just imagine five seconds of bear growth, which is almost nothing.
Thrust = c1 * Δy – T-Sense
Thrust = c2 * Δχ – ΤΤ-Sense
I would like to start up the movie. Just to show you the principle of the optical sensor. Over here the optical sensors are mounted on, the propeller shafts. For the thrust sensor we have 4 optical sensors installed. Please notice that when the shaft is subject to torque, you will measure the displacement in radial direction and when the shaft is subject to thrust you will measure the compression of the shaft.
When measuring the thrust you almost directly measure the resistance of the ship and you also measure directly your propeller performance. These are two very big advantages of measuring the thrust instead of measuring the power of the propeller shaft.
The thrust output is also a very important value because it is directly related to
- Hull roughness, marine growth, slime, seaweed etc.
- Trim of the vessel (optimization)
- Propeller performance
- Quality of low friction paint, anti-fouling paint
When you just change the trim if the vessel you will see that as a direct result the thrust is changing a little bit and that’s the things you would like to see.
Some real life examples. These are some examples of creating awareness on shore.
Data is sent from the ship to the shore through satellite communication. By trending the available data they made very nice graphs. These are graphs of a very big container vessel which was equipped with our thrust sensor. Noting down that the thrust values in certain conditions are put in this graph, you can see that within 10 months the added resistance of the ship was almost 14%, due to hull fouling. This is a lot of money even if we calculate it with the low heavy fuel oil prices nowadays. The other picture is about propeller efficiency. You can see the same. Propeller performance is going down within 1 year and decrease in performance is about 5% which represents a value of about 200.000 dollars is in this case.
Below, there is another example. This is an example of creating awareness on board.
This is a hopper dredger and a typical sailing profile for a hopper dredger, which is dredging the sea bottom at a coastal area, going full speed to the shore; start rainbowing and then go full speed back again. By performing this kind of trips many times a day (maybe 10 or 20 times), frequent manoeuvring, fast acceleration, reducing pitch very fast again and always sailing full speed you will burn a lot of fuel. It is clear that the vessel is always in a hurry.
In this case the ship-owner decided to sail the vessel in a different way. They decided to just decrease their maximum speed a little bit and also do manoeuvring more smoothly, not like go full pitch ahead and then go abrupt to full pitch astern. Their ship had thrust sensors on board, fuel flow meters on board, by looking at the PEM4 monitoring screen they were able to just decrease fuel consumption with 10%. That’s very nice of course, but the funny thing was actually that at the end of the day, they transported the same amount of sand. It’s like driving your car through Athens full speed, full braking at every traffic light and then accelerate back to full speed again. In the end you will notice that there is no reason for it. Because it takes a lot of time anyway.
In conclusion, thrust monitoring fuel efficiency monitoring is not about getting the tall apples from the top of the tree, it is just like getting the low hanging fruits, because your investment is limited to flow meters and torque meters, it is not a very big or risky investment, while you can earn a lot of money, because the fuel prices are still the major part of the operational costs. In the end our captain Haddock will be very happy with it.
Above article is an edited version of Edwin Schuirink’s presentation during the 2015 GREEN4SEA Forum
You may view his presentation video by clicking here
| Click here to view all the presentations on this GREEN4SEA Forum |
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About Edwin Schuirink
Technical Product Manager, VAF instruments
Edwin Schuirink obtained his bachelor degree in mechanical engineering in 1990 and started his professional career in the propeller and engine manufacturing business. He obtained a lot of experience in this segment of the maritime industry as a project engineer, sales engineer and sales manager. In 2010 he joined VAF Instruments BV (Dordrecht, the Netherlands) as a Technical Product Manager, representing the T- and TT-Sense optical torque & thrust measuring systems and fuel consumption measurement in general.
At VAF Instruments he joined the technical and R&D department in developing the PEM4 Efficiency Monitoring system, the user interface between a wide range of VAF sensors and the crew on board. Moreover he worked on a variety of efficiency monitoring projects worldwide and gained extensive practical experience in fuel consumption, engine efficiency and vessel performance monitoring.
In the beginning, I was open with you propecia before and after has changed my existence. It has become much more fun, and now I have to run. Just as it is incredible to sit.
