On 3 december 2018, the two-year interruption of the Large Hadron Collider LHC began at CERN in Geneva. During this time, the LHC will be shut down to revise or replace components and raise its energy level.
The newest accelerator ring at CERN, the LHC, is 27km in circumference, has 1.9K operating temperature and lies at a depth of 100m. The High Luminosity LHC (HL-LHC) is a LHC performance enhancement project designed to sustain scientific progress. As part of the HL-LHC project, the LHC refrigeration systems will experience an increase in heat loads and need to be expanded or rebuilt accordingly.
The above-mentioned conversions from 2019 till 2021 will take place in this overall context. The Linde Kryotechnik contribution is required primarily at point 4. The refrigeration system installed there in 1993 is a bottleneck due to its dual task. It cools the LHC ring section between points 3 and 4 as well as the superconducting RF cavities at point 4. The refrigeration system has already been upgraded for the LEP200 and the LHC, however a third upgrade is possible to meet the growing needs of the HL-LHC. That impresses. The upcoming conversion will increase the capacity of the refrigeration system by another 2 kW from 16.5 kW to 18.5 kW @ 4.2 K equivalent refrigerating capacity. Responsible for the increase in performance will be new, more efficient turbines whose larger dimensions require corresponding modifications to the cold boxes and adjacent accessories.
A refrigeration system, which served to cool down the Crab Cavities during operation, takes on another task for the LHC conversion time and had to be transported to point 4 accordingly. The mobile version of this refrigeration system was developed and built by Linde Kryotechnik at the request of CERN in 2016 to test the RF cavities at point 4 during the upcoming two-year conversion phase.
In Meyrin, the headquarters of CERN, another new refrigeration plants will be commissioned in 2019 for 35 g / s @ 4.2 K. Here, tests are to be carried out with new magnets, cavities and modules intended for future, stronger radiation bundles. Only then will HL-LHC be able to meet the scientific requirements by 2033.
Guildford, UK, 1 March 2019 – Today, Linde plc (NYSE:LIN; FWB:LIN) announced the restrictions under the hold separate order issued by the US Federal Trade Commission have been lifted following the completion of certain required divestitures in the US.
The company will now fully integrate its business globally.
About Linde plc
Linde plc is a leading industrial gases and engineering company with 2018 pro forma sales of USD 28 billion (EUR 24 billion). The company employs approximately 80,000 people globally and serves customers in more than 100 countries worldwide. Linde plc delivers innovative and sustainable solutions to its customers and creates long-term value for all stakeholders. The company is making our world more productive by providing products, technologies and services that help customers improve their economic and environmental performance in a connected world.
For more information about the company, please visit www.linde.com
Phone: +1 203 837 2213
Phone: +44 20 3755 1621
Cooling the giant neutron microscope
- In the southern Swedish city of Lund, a pan-European consortium is building one of today’s largest research facilities, the European Spallation Source (ESS).
- Based on the world’s most powerful neutron source, the facility will serve as a massive laboratory for scientists working on research projects covering areas such as materials sciences, energy, health and the environment.
- This spallation source would not be possible without sophisticated and extremely capable cooling systems. Linde Kryotechnik supplied the most import cryogenic parts, including two coldboxes, each being a one of a kind.
Two mobile cranes with long telescope arms are already waiting as the heavy low-bed trailer arrives at the giant building site in Lund. Its valuable cargo, a coldbox, has the shape of a white zeppelin, measuring 10 metres in length and 3.5 metres in diameter. While this shell may look unimposing, it actually contains sophisticated technical equipment, a one-of-a-kind coldbox that will cool parts of the the world’s most powerful neutron source down to temperatures around 16 kelvins, or -257 degrees Celsius. In September 2018, after a long journey through Europe, the 40-ton coldbox reached its destiny, the site of the European Spallation Source (ESS).
ESS is a pan-European science project and one of the world’s largest research infrastructures in construction today. Thousands of scientists from a broad range of disciplines will run experiments investigating actual and upcoming matters on an atomic or molecular scale in research fields such as material sciences, energy industry, medicine and environmental research. Linde Kryotechnik, the leading provider of cryogenic systems for world scale research facilities such as CERN and Fermilab, has provided both big cryogenic systems for the complex cooling system at ESS. “In total, we have three different helium coldboxes,” says Philipp Arnold, Section Leader Cryogenics at ESS. “Two for the operation of the ESS machine, one for the testing of equipment and providing liquid helium to the neutron instruments.” The cooling systems for operation, including compressors, oil removal system (ORS), the gas management panel and more, have been designed and delivered by Linde Kryotechnik. Because every coldbox has its own function, they are built to their individual purpose. One cryoplant is needed for the acceleration of protons, one for moderating neutrons. Accordingly, they are called ACCP (Accelerator Cryogenic Plant) and TMCP (Target Moderator Cryogenic Plant).
It starts with protons
Reliable cooling systems are essential for experimental infrastructure of particle accelerators. The reason lies within the acceleration process. “In order to get neutron beams for science, we first have to create a powerful beam of electrically charged particles” says Julia Öberg, Press Officer at ESS, “this is, in our case, protons.” Particles with an electrical charge can be accelerated using electro-magnetic fields. Contrarily, neutrons, as their name implies, are electrically neutral. Electro-magnetic fields do not have any effects on them. “So, the main purpose of the ESS accelerator is to accelerate a powerful beam of protons and to shoot them against a rotating Target wheel containing bricks made of tungsten, which is a neutron rich heavy metal,” Öberg says. “When the protons hit the target, the tungsten releases neutrons in a process called spallation”. Those neutron beams are extremely useful for scientists, since they allow investigation of materials providing different information than experiments based on electron or synchrotron radiation.
Accelerating the protons to the speed needed in the spallation process – approximately 96 per cent of the speed of light – requires radio-frequency cavities. ESS uses superconducting cavities to lower the resistive losses. Since the cavities only become superconducting at extremely low temperatures, they have to be cooled with superfluid helium kept at temperatures of 2 kelvins, which is minus 271 degrees Celsius. This is exactly what the first coldbox designed by Linde Kryotechnik does: The Accelerator Cryogenic Plant (ACCP) was delivered in early August 2017.
A giant passes the chokepoint
Now, one year later, the second vessel is being lifted by two cranes in front of the gate at the side of the oblong klystron gallery that runs along the accelerator tunnel. Since it is too big to be driven in on the back of a trailer, it has to be offloaded and placed on small rolls. The crane operators are deepening the 40-ton cylinder slowly and carefully laying it down. Success is a matter of centimetres, but the experienced workers manage to place the vessel safely on the rolls. Supported by a forklift truck, they pull the coldbox inside the hall, passing a jungle of pipelines, machines, measuring apparatuses and more. Now, however, the task is a matter of millimetres. The workers need a whole day to manoeuvre it to its place, next to its big brother, the ACCP.
Although they look similar at first sight, these are completely different machines. The ACCP cools down the accelerator to boost protons which hit the target wheel. Those crashes force the tungsten in the target to release neutrons. “To make these neutrons usable for science, they are slowed down by passing ESS’ innovative hydrogen moderators. These moderators are cooled by the second coldbox, the Target Moderator Cryogenic Plant (TMCP),“ Öberg explains.
Close partnering and exchange of expertise
Even for a highly specialised technology company like the Linde Group, designing a cooling system for such a complex project is not a daily routine. “You cannot simply order a coldbox like this,” says Philipp Arnold. Thus, Linde Kryotechnik was already involved at an early stage during the conception phase. Lars Blum, Head of Sales & Business Development at Linde Kryotechnik, describes the collaboration with engineers and scientists from ESS as “a close partnership with an on-going exchange of information and expertise.”
This close partnership is especially necessary when it comes to challenging details and special requests. “One difficulty was to keep efficiency high at several power levels and stages of expansion,” Blum explains. An additional challenge is caused by the distance between the TMCP and the target. Since they are 300 metres away from each other, the gas molecules take minutes to travel forth and back from the target to the coldbox. In order to react quickly to changes of pressure, flow rate and temperature at the target station, Linde’s and ESS’ engineers have developed a special control concept to cope with the lag of the system response.
Half of the construction work is done
The TMCP has reached its final position. But Linde’s work has not ended. “It will take several months, maybe a year, to install the cooling system completely,” Arnold says. A complex snarl of pipelines and valves has to be attached properly. Therefore, a small group of Linde engineers will stay at the site during installation, commissioning and testing.
Meanwhile, work is going on all over the giant ESS site. “Until now, we have completed 52 per cent of the construction project,” Julia Öberg says. 2019 will be an intensive year with installation and commissioning of technical equipment in various parts of the facility. The user program for scientists is planned to start in 2023. Then, the optimal environment for multi-disciplinary research and scientific breakthroughs will be in place – cooled by Linde.
Higher energy densities, longer discharges
As planned the second experimental campaign of the world’s largest fusion experiment of the stellarator-type, the Wendelstein 7-X, was finished before Christmas 2017. All components functioned correctly and allowed the scientists to run the experiment with up to 75 Mega Joule for 30 seconds.
The third and last part of the experimental series is planned to start in July 2018 and will verify the possibility of a continuous operation of the stellerator.
In November 2017, General Atomics published a paper describing the performance of its ITER test facility and qualifying its suppliers. This paper shows that, once again, Linde Kryotechnik has successfully designed, produced, installed and commissioned a refrigeration system for the ITER project.
K. SCHAUBEL writes about the delivery of the refrigeration system for General Atomics:
“3.4. Cryogenic system
The cryosystem provides a thermal environment for stable operation of the feeder and CSM during final test. It must cool and warm the 120-t cold mass of the CSM and its support structure in a controlled manner to prevent large thermal stresses. The cool down rate from 300 K to 80 K is limited to ≤1 K per hour, and the maximum temperature difference between the CSM inlet and outlet is limited to 50 K. Below 80 K, there is no thermal stress limitation so cooldown is limited only by the refrigeration capacity of the cryosystem. The calculated cooldown time of the cryosystem and CSM is ∼14 days. During steady state operation, the cryosystem provides 4.5 K supercritical helium to the CSM at a flow rate of 320 g/s and a pressure of 0.55 MPa. This flow rate corresponds to the ITER operational flow rate of 8 g/s per CSM layer. The calculated heat loads to 4.5 K include 92 W from the test chamber, 70 W from the Feeder and a 100 W allocation for electrical joint losses. In addition, the cryosystem provides 50 K helium gas to cool the HTSCLs and liquid nitrogen to cool the CSM and feeder thermal shields and cold mass support structures. The cryosystem coldbox and compressor installation is shown Fig. 5.
The system was designed and manufactured by Linde Cryogenics. The design combines a standard refrigerator and supercritical helium recirculator in one coldbox. The refrigerator uses liquid nitrogen precooling and two turbine expanders to produce and maintain liquid helium in an internal 380l subcooler/heatexchanger, which operates at 4.3 K and 1.10 bara. The recirculator produces 350 g/s of supercritical helium flow at a pressure of0.55 MPa to the feeder in a secondary cooling loop. The helium in the recirculator loop is re-cooled to 4.5 K as it passes through the subcooler/heat exchanger.
Liquid nitrogen is supplied from a 23,000 l tank which is batch filled. Helium inventory is managed using two gas buffer tanks with a combined volume of 225 m3. The buffer tanks operate between a pressure of 0.15 MPa and 1.4 MPa depending the system condition.
Installation, commissioning and acceptance testing of the cryosystem is now complete. The system exceeded all performance requirements during extended testing into a dummy load located at the connection point of the feeder. The system produced a super-critical helium mass flow of 340 g/s at 4.5 K across a pressure drop of0.11 MPa. A dummy heat load of 315 W was simultaneously applied at 4.5 K, while HTSCL cooling gas was supplied at a temperature of43 K, a flow of 7 g/s and a pressure of 0.9 MPa.”
“Excerpt from Fusion Engineering and Design, Vol 124/November 2017, K. Schaubel, A. Langhorn, S. Lloyd, Z. Piec, E. Salazar, J. Smith, The ITER Central Solenoid Module final test facility / 3.4. cryogenic system, Page 62, Copyright 2017, with permission from Elsevier.” http://www.elsevier.com
The world’s largest fusion experiment of the stellarator type Wendelstein 7-X is in action for the second time. The stellarator is running again after a 15-month conversion break, which served to equip the machine for longer pulses and higher heating power. The next step in a continuous increase in the energy level and the operating time is thus possible.
Although Wendelstein 7-X is not meant to produce energy, the device is intended to prove that stellarators are suitable for power stations. For the first time, the quality of the plasma confinement in a stellarator is to reach the level of the competing tokamak type devices. Gradually, the duration of discharges will be increased and in a few years’ time the duration will be at 30 minutes. This data could be used to obtain information if the large advantage of the stellarator type is possible: continuous operation.
Read the full press release on the IPP Website.
Scope of supply of Linde Kryotechnik for the Wendelstein 7-X Project.
This video produced by US ITER in collaboration with General Atomics (GA) describes the work underway in the United States to fabricate the ITER central solenoid. The cryogenic plant of Linde Kryotechnik is used for testing at 50 Kiloampère and 4 Kelvin.
On 18 August 2017, Linde Kryotechnik delivered the core component of the refrigeration system for the European Spallation Source (ESS) accelerator. This was one of the biggest transport undertakings yet for the massive ESS project, with an oversize consignment measuring 39 m in length and 4.6 m in width arriving at the ESS grounds.
Moving the coldbox at all was a challenge – it is 14 m long and 4.7 m high with a diameter of 3.5 m and weight of 50 tonnes. Time and again, it pushed the boundaries of feasibility and called for new solutions – whether it be to assemble the inner workings with the outer shell or ready the box for shipping.
For transport by road, obstacles like roundabouts and signage had to be dismantled by an advance team and put back again once the vehicle had passed. Transport by sea was not possible from ports near Lund as they were not equipped to handle cargo with such huge dimensions. Ultimately, the cargo had to travel from Basel via Gent to Gothenburg for shipping. This resulted in a final onshore stage, where the transporter had to navigate an underpass with a guideline clearance of as little as 3 cm.
After 15 days en route, the cargo reached its destination at the ESS site in Lund, Sweden. It took one whole day to manoeuvre the delivery into the unloading hall.
The plant will be installed here in the next few months and the completed system is set to be handed over to ESS in autumn 2018.
The second order from ESS, the TMCP (Target Moderator Cryo Plant), is under construction.
Since 1952, ETH Zurich has been liquefying helium. The university of science and technology turned to its trusted partner, Linde Kryotechnik, to help with plans to revamp an existing helium liquefaction unit and replace another one with a new liquefier.
The physics department of ETH Zurich supplies liquid helium to various R&D teams within ETH and also to the University of Zurich. When using helium, ETH Zurich recovers and reliquefies most of the gas. It does this with two TCF20 helium liquefier systems delivered and installed by Linde Kryotechnik in 1995 and 1999.
Moving forward, ETH Zurich intends to meet rising demand for liquid helium to support research and development projects with a new L140 helium liquefier. The plan is to replace one of the outdated TCF20 units and revamp the second TCF20 unit. The revamp involves upgrading the TCF20 to the control system of the L-Series and replacing various sensors and actuators. This revamped model will be as easy to operate as the modern L-Series plants.
Commissioning of the new L140 helium liquefier is scheduled for May 2018.
On May 4th, 2017 DESY and XFEL reported that the most powerful of five X-ray lasers in the world has sent its first beam into the 3.4 km tunnel. One of our most important customers celebrates a great success.