Cryogenic warehouse in Sofia

Cryogenic storage - Frigotehnica Sofia 2023

Together with our partners Teledoor Melle Isoliertechnik GmbH and Frigotehnica Bulgaria, a cryogenic warehouse was completed in October 2023. As the lead company in project management and planning, Refolution made the storage room for temperature-sensitive products possible. This storage room was designed to meet the customer's needs. It consists of special industrial panels with PU foam filling, which are mechanically stable enough for extreme temperatures and achieve an outstanding insulating effect. The inner surfaces consist of a fully welded stainless steel surface. The storage area and storage volume are 51 m² and 119 m³ respectively.

Storage room and airlock with open cold air chillers

Refrigeration technology of the storage room

Thanks to the cold air refrigeration technology used by Mirai Intex, the temperature in the storage room can be infinitely adjusted between -80 °C and -20 °C. The two Mirai Intex MC10 O/W machines with air as the refrigerant ensure N+1 redundancy. The control quality is +/- 0.5 K with a temperature homogeneity of 2 K in the empty room. This requirement is met at all times thanks to mechanical defrosting. At the same time, the air is dried by the dew point reduction of approx. 15 K, which ensures a high storage quality. The speed control enables particularly efficient partial load operation of the systems at any temperature requirement.

For energy optimisation and ice fog reduction, a corresponding airlock system with a self-sufficient CO2 (R744) cooling unit has been integrated, which ensures temperature control to -20 °C. The airlock reduces the heat input into the chamber.

The storage room from the inside

Supply engineering

The cooling water system is realised via two redundant R290 chillers (propane chillers) from the company Secon of the HELIOS type. This means that all system-relevant components are redundant. In addition, the entire installation is protected against power failure with an emergency diesel generator, thus ensuring safe storage at all times.

A safety concept was implemented that includes personal safety when entering the cryogenic storage room by means of a dead man's alarm and cryogenic clothing (PPE) as well as safety against CO2 leakage.

The machine control system was implemented with a Siemens S7 and our developed safety concepts and equipped with remote maintenance access and various customer interfaces. The equipment in the storage rooms includes temperature monitoring, economical LED lighting with high luminous efficiency and low heat input, stainless steel interior walls and a heavy-duty floor (20 kN/m²).