Registering valuable liquids with precision at up to 10km/h
Weighing liquids dynamically is a challenge. Material flows in the chemical and petrochemical industries are high-value commodities where every litre is worth its weight in gold. But liquids are now transported by rail, and they need time to settle and become still before they can be accurately weighed. Errors in monitoring can result in heavy losses, as the following example illustrates. Let’s assume that every day, in one of 12 tank wagons each containing 50to of refined hydrocarbon, 10% is missed. Over 200 working days a year that amounts to 12 000to or 20 whole train loads. This could mean losses of millions of euros. Random sampling is no solution. The material flow needs to be continuously recorded.
The MULTIRAIL® solution: dynamic weighing. Accurate and time-saving
MULTIRAIL® LiquidWeight from Schenck Process eliminates known disturbing factors from the process of weighing liquid goods and operates with precision at speeds of up to 10 km/h. If not being weighed, wagons can travel at the permissible speed for the track. The user saves time and benefits from a high degree of automation, considerably lower error rates and increased scale performance. A worthwhile investment that has already proven itself for customers such as OMV, Basell and Dynea.
How does MULTIRAIL® LiquidWeight achieve such accurate results?
Elimination of cost factors and disturbing factors
Cost factor – time: Static train scales can be used to weigh tank wagons with a high level of precision. But this takes time, because the scales are often located on a side track owing to speed restrictions. Diverting and uncoupling the wagon from the train set, shunting, stopping – all of these operations set the valuable liquid in motion. It starts ‘sloshing’ about. It can take 20 minutes or more for the liquid to reach the state of stillness required by the Office of Weights and Measures. Even if you are only weighing 12 wagons a day, you need around four hours to weigh the whole train.
Cost factor – staff: To carry out all the operations described above you need not just a locomotive but a train driver, a shunter, a weighing operator and a flagman.
Disturbing factor – vertical forces: The liquids in the train set are subject to various dynamic influences. On the bogie, the load is distributed differently to the four wheels depending on the height of the track. Additional vertical forces in the area of the couplings are influenced by the position of the track and vertical movement of the wagon. Vertical vibrations of the wagon make the liquid move faster. Combined weighbridges cannot solve this problem, because independent of their design, they can represent an additional disturbing factor. The design of the weighbridge is completely different from the structure of the track. In addition to the variations in rigidity there is another source of disturbance at the point where the two meet – the gap between the rails.
Schenck Process has managed to reduce these disturbing factors and cost factors year on year with the development of its MULTIRAIL® technology. The weighbridges have been eliminated. The track has been modified as little as possible. The gap between the rails has also been eliminated. Wagons are weighed on the main track. The train is driven slowly and evenly across the scales, which are now long enough for all the wagon’s wheels to be weighed simultaneously for an extended period. The system provides efficient, accurate monitoring, which is largely automated, and a considerably reduced error rate. MULTIRAIL® LiquidWeight is capable of calibration in accordance with OIML R 106-1 and has calibration approvals for DE, FR, AT and CH, including approvals for EBA, DB and ÖBB.