3 years ago

Automation Technologies 1/2016

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Automation Technologies 1/2016

Radiometric density

Radiometric density measurement on suction dredger behemoths At home on seven oceans: “Charles Darwin” and “Nina” cross during their port entry in Brazilian coastal city of Itajaí SENSORS AND MEASUREMENT The special ships of Jan De Nul Group displace entire islands or coast lines. As the suction dredgers are deployed for many weeks, the reliability of measurement technology is of extreme significance. The dredgers use the trailing head to remove the sediment from the waterbed and move on board through a suction line. A customised solution for flow and density measurement is used, which has grown along with the immense challenges. Rome was not built in a day. And even the “Palm Islands” in Dubai were not built overnight. Just the landfill alone took more than five years: unbelievable amount of 220 million cubic meters of sand was shifted for creating the 17 “palm branches”, which are protected by a 20 km long wave breaker. In comparison: if we were to load this material in trucks, the column would circle the earth ten times. The Luxembourg Jan De Nul Group is active on rivers, channels and the seven seas: the specialist for land reclamation and coast protection, port maintenance and channel construction has a proud fleet of more than 70 main ships, which belong to some of the most modern, large and powerful ships in the world. 13 of these ships were used for the mega project in Dubai – a summit meeting of suction dredger behemoths. For the mega projects away from the home dockyard, a team (approx. 40 people) is working for six weeks without a break. Thanks to shift operation and highly modern devices, we were able to process up to 100 000 tonnes of sand or stones per day. And we did not leave things to chance: as an unplanned “pit stop” may cause enormous monetary losses, the ships have almost five tonnes of spare parts and approx. 300 tonnes of reserve pipelines. “This technical and logical safeguard as well as preventive maintenance guarantee a smooth operation at sea globally”, says Ruben De Lille, Technical Director of Jan De Nul Group and who is responsible for automation and engineering. On water and on land When compared with a gigantic vacuum cleaner, the suction or hopper dredgers move the sediment from the waterbed by using trailing heads and take them on board through a suction line. The large ships can take more than 60 000 tonnes of material: much more than their own weight. 6 500 kW pumps transport the mixture of sand and water upwards, where water is separated. The solid parts are filled in the storage areas of the ship for further transport About Endress+Hauser As one of the leading international suppliers of measurement devices and services for industrial process technology and automation, Endress+Hauser offers complete solutions for flow, fill status, pressure, analysis, temperature, data collection and digital communication for all industries. The company is headquartered in Reinach, Switzerland. AUTOMATION TECHNOLOGIES 1/2016

and are deposited later at the destination by opening the bottom flaps. If it is not possible, then the material is transported to the destination through a floating pipeline or by using a “Rainbow” method, i.e. in a high arch through air. Jan De Nul designs the mechanical structures and machinery in its own engineering department: approx. 600 engineers take care of construction, operation and maintenance of the fleet. “The deployment reports are continuously evaluated. We are looking systematically for technical optimal and cost-effective solutions”, says Ruben De Lille. Not only are the machines, even the concepts for maintenance and repair continuously improved. “Very often there is great potential for saving in small things”. So we took a decision to do away with previously used measurement devices from a specialist company when we were building two new dredger ships: these are watertight, but are very expensive, because there is hardly any competition in this highly specialised field. Combined measurement of flow and density “As the company has been looking deeper since 1990, we were able to save many millions of Euros by selecting right suppliers”, says Ruben De Lille. When there are no perfect solutions (yet), we are happy to take help from external specialists. “Often this leads to the integration of similar, but less expensive instruments”. The same approach was follower in 2010 for the development of a combined measurement device for flow and density, which was meant to ensure reliable results at the trailing head suction pipe of “Charles Darwin” with an inner diameter of 1.2 m. After exploring the market, Jan De Nul decided to go for Endress+Hauser, wherein their measurement device was classified as winner in an earlier comparative test. The contract was to develop a customised solution for the filling process. “The size of the flange and the position of the assembly holes were specified”, explains “Thanks to our partnership Endress+Hauser, we were able to develop similar, but less expensive instruments.” Ruben De Lille, Technical Director of Automation Jan De Nul Group 01 Maximum suction power: The gigantic suction pipe on “Charles Darwin” with the Endress+Hauser measurement device developed for the customer Radiometric density measurements on suction dredgers The radiometric measurement technology is used, if other measurement principles are ruled out due to extreme process conditions or due to mechanical, geometric or construction issues. The measurement principle is based on the weakening of gamma rays when they penetrate the material. If the pipeline is filled with water, the detector will receive a quantity of gamma ray that is specific for the measurement. The density of the mixture will increase in the pipe once sand and sludge are mixed to water. The gamma ray received at the detector will reduce due to higher density. The density value calculated this way will be identified by Promag 55S flow measurement device. The mass flow can be calculated from this value and the measured flow speed of the medium. Jean-Jacques Renaux, Product Manager Flow Technology in Belgium. The amount of transported sludge will be captured and measured precisely in spite of severe vibrations, which are present continuously on the ship. Furthermore, space to have two measuring devices at the suction line was missing. Thus, a “piggyback” solution was developed, a combination of two devices, which allows calculation of both the values at the same location. “The Gamma project team from Maulburg and the department of special products from Endress+Hauser Flowtec were involved”, says Jacques Kersloot, Sales Engineer of Endress+Hauser Belgium. “The experience of application specialists and the Know-How of the developers led to an innovative solution”. The team was able to present a solution after two years. The result was the largest Promag 55S of all times. “While the electromagnetic flow measurement device Promag 55S measures the flow speed, the Gamma pilot M FMG 60, which works based on the radiometric principle, determines the density of the mixture”. 02 Side by Side: Ruben De Lille, Technical Director of Automation Jan De Nul Group, and Jean-Jacques Renaux of Endress+Hauser Belgium


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