The research centre DESY is one of the world’s leading accelerator centres and is renowned for researching, developing, building and operating particle accelerators. For a long time the HERA ring accelerator was the institute’s flagship project. Its successors are the European XFEL and FLASH. For these two accelerators, DESY had to refurbish and modernise the entire cooling system. Metso was commissioned as the general contractor for the complete rebuild of the valve controllers and the air pressure supply of the cooling system.
Now intelligent Neles ND9000 valve controllers regulate all field devices and the Metso FieldCare software optimises online monitoring of all functions. With this state-of-the-art technology DESY achieves the extremely high levels of plant safety and availability that are essential for operating accelerators of this type.
The focus at DESY has shifted from particle physics towards research with photons. It is working on a new project: the European X-Ray Free-Electron Laser XFEL is a 3,5 kilometre long accelerator for experiments with X-ray laser light. “In order to run this plant, we need a refrigeration system that works with liquid helium,” says engineer Torsten Böckmann. He is a member of the machine, cryogenics and superconductivity group and is in charge of instrumentation and sensor technology.
Thousands of experiments necessitate extremely high availability
In future the refrigeration plant will serve the superconducting linear accelerator FLASH (Free-Electron Laser Hamburg), whose numerous tasks include serving as a test system for the future European XFEL (X-Ray Free Electron Laser) one of the most powerful sources of X-radiation worldwide. While DESY operates those plants, institutes from all over the world use them for their experiments. Böckmann knows the problems arising from the strong demand only too well. “Thousands of scientists register their experiments and book time slots for measurements. These slots are planned so strictly and tightly that measurements could not be completed in cases of system faults or, worse, failure. Therefore we rely on extremely high levels of availability.”
The refrigeration plant consists of low and high-pressure compressors, cleaner, line drier, oil removal system and cold box. “The modernised plant is designed to cool helium down to 2 Kelvin, so that we attain super-fluid helium 2, whose excellent thermal conductivity is required for the experiments,” explains Böckmann. “We have chosen Metso as our partner for carrying out the necessary modifications. Metso was responsible for refurbishing the entire air supply system and replacing the valve controllers.”
Metso as general contractor for modernising the plant
As general contractor, Metso in turn commissioned a sub-contractor to construct the new air supply system and installed approximately 150 intelligent valve controllers from the Neles ND9000 series on the valves of the refrigeration plant. Even though the linear and rotary valves have been in operation since the construction of the plant around 20 years ago, they are subjected to very little wear and tear since they are used with a gaseous element, there is little vibration and the site is very clean. “These are ideal operating conditions for valves, but with the system having been in operation for such a long time already, we need a monitoring facility to ensure high plant availability,” says Böckmann. “With the valve controllers we can monitor the valves and identify and resolve potential problems at an early stage.”
This is made possible by the ND9000’s adaptive control algorithm, which adapts automatically to changing operating conditions and therefore guarantees optimal control performance, independent of external influences. In addition, all changes regarding device performance and device status are displayed and recorded online. Furthermore, fast response times, excellent dynamic control performance because of very high air capacity as well as high-precision static control performance reduce process variability significantly.
Metso FieldCare software monitors field devices
A further logical step by DESY was the decision to use the device and asset management software Metso FieldCare to monitor all data from the approximately 150 Neles ND9000 in use at the plant. Böckmann calls this combination of intelligent valve controllers and automatic online monitoring system, “A reliable, future-proof investment, especially since we no longer have redundancy built into the system. The system is well designed and we can perform a lot of tasks intuitively. We use this software as a bridge for importing the data from the valve controllers into our own control system. We use this basic system in combination with our own Java-based graphic interface, which enables us to visualise all aspects of the control process.’’
All measurements are stored as trends, so that the respective diagnostic parameters can later be traced back across the entire operational period and the data can be used for very precise forecasts. Thus Metso FieldCare supports condition oriented maintenance: based on the data collection, DESY can devise a precise maintenance schedule, which also allows for sufficient time to source spare parts.
“The biggest advantage is that we can operate the refrigeration plant 24/7 throughout the year without failures,” says Böckmann. “We are also able to identify and resolve potential problems in advance, so that we will not suffer any system downtime. For the future we envisage an operatorless plant and the use of Metso FieldCare not only for the refrigeration, but also for the European XFEL accelerator directly.”
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