Biological refrigerant for ice rink in Liège

The refrigerant has recently been replaced on the Liège ice rink. The alkali, which has been used since it was introduced in 2012, no longer matches the sustainability goals of the Belgian city. Because of these goals, a biological variant was chosen. To ensure safety, the replacement of 13 tons of alkali with 11,000 liters of biological agent was a laborious operation.

Text: Climalife

The Olympic ice rink in Liège, Belgium, is part of the Médiacité complex. It is a sports arena of 1,800 m², which was built in 2012. There are changing rooms and 1,100 pairs of skates can be rented on heated racks. The grandstands have heated seats for up to 1,250 spectators. The ice rink consists of three layers: the pipes, a layer of concrete and the ice. The technical installation is located in the basement of the building.

Careful temperature control
Throughout the year, the ice rink hosts national and international ice hockey competitions, events, theme nights and sound and light shows. But there are also plenty of free skates. Careful temperature control is required to ensure the desired ice quality for each of these activities. An indirect system for this will be installed during the construction of the ice rink. The plant’s primary circuit is filled with 180 kg of ammonia, and the secondary circuit contains 13 tonnes of alkali, an aqueous solution based on ammonia.

Table 1. Ice temperature by activity.

Preservation of existing refrigeration installation
The owner of the ice rink is the city of Liège. In connection with the sustainability goals, the local government has also made plans for the ice rink. The city did not want to change the design of the existing refrigeration installation, but only to replace the alkali with another refrigerant. It should be compatible with the existing system and environmentally friendly. The company VMA Refrigeration, responsible for maintaining the installation of the ice rink, began looking for such an alternative.

The freezer is located in the basement of the building,

Organic alternative to alkali
VMA, a subsidiary of the engineering company CFE, has been active in Belgium for 120 years. The company has been active in industrial refrigeration for more than 30 years and focuses on the entire process from design to maintenance. With 1,000 employees, it is a major player in our southern neighbors. Abdel Lourhmati, expert in industrial refrigeration at VMA Refrigeration: “For the ice rink, we advised to replace the current energy carrier with a biological alternative that fits well with Liège’s sustainability goals.”

Plant-based products
The VMA approached Climalife for the biological energy carrier. That company recommended two plant-based products, Thermera and Greenway Neo N. Of the two, Greenway Neo N has a better density and is more suitable for this application. This energy carrier, formulated and produced by Climalife, was also selected because of its more favorable CO2footprint and safety. Greenway Neo N is bacteriostatic and composed of effective hybrid inhibitors. The vegetable raw material 1,3-propanediol has a lower viscosity than an MPG (monopropylene glycol). Another property is the biodegradability. In the event of a leak, there is therefore less risk of soil contamination.

Properties of the refrigerant.

An additional valve was added to the system to facilitate operation.

Pumping out of 13 tons of alkali
To drain the base and fill the system with the biological agent, three crucial steps were taken in sequence one Sunday when the sports center was closed. Prior to the pumping out of the 13 tonnes of alkali, a safety analysis had already been carried out together with the main contractor and the services involved. An additional valve was added to the system to facilitate operation. A special tanker was reserved for the disposal of the alkali. This car is equipped with a large air filter, combined with a ventilated water tank to ease the overpressure and facilitate pumping.

Neutralization of ammonia vapors
To fill the tanker, long pipes were needed to bridge the distance to the installation. Two large tanks with 1,000 liters of water were used to neutralize the ammonia vapors during pumping. The necessary precautions have been taken to exclude any risk of degassing in the center of the city of Liège. According to the contractors, the job required great expertise in handling ammonia and perfect control of the hydraulic circuits. The alkali was taken to a specialist company, where it was destroyed. The truck was cleaned with water.

Fill with 11,000 liters of new refrigerant
In the second step, the system and pipes were flushed. No less than 15,000 liters of water were used for this and then destroyed. In the third step, the circuit was filled with 11,000 liters of Greenway Neo N, with frost protection down to -25 ° C. “This last phase went well. It took a whole day to fill the system, three days to distribute the product correctly and about two weeks to reach the desired temperature,” says Pascal Michot, Industrial After Sales Project Engineer at VMA Refrigeration.

Compatible with existing cooling system
A few months after the replacement of the refrigerant, the results appear to be excellent, according to the VMA: Greenway Neo N appears to be compatible with the original refrigeration system. A small increase in the energy consumption of the pumps was noted, but according to VMN it is very minimal.

Properties of the ice rink’s cooling system.

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