Recuperation systems for fluorinated gases at the CERN LHC Experiments

Abstract

Particle detectors at the LHC experiments are very often characterised by large detector volumes and by the need of using very specific gases, some of which are greenhouse gases (GHGs). Given their high Global Warming Potential (GWP) and the increasingly stringent European regulations regarding the use and trade of these gases, CERN is today strongly committed to reduce GHGs emissions from particle detector operation. Different approaches have been adopted for reducing the GHG emissions. To achieve this objective, the CERN Gas Team has developed gas recuperation plants: i.e. systems designed to extract GHGs from the exhaust of gas recirculation systems allowing further re-use and, therefore, reducing drastically GHGs emissions without changing detectors operation conditions. They are industrial-scale systems, each of which relies on different principles for gas separation and purification. Considering the unique gas mixtures used in particle detectors, these recuperation systems have been specifically developed as no industrial apparatus currently exists to address these requirements. Recent developments are concerning plants for recuperation of CF4, C2H2F4 (also called R134a), SF6 and C4F10, which are used respectively for Cathode Strip Chambers, (CSCs) Resistive Plate Chambers (RPCs) and Ring-Imaging Cherenkov (RICH) detectors. The separation of fluorinated gases is carried out mainly through membranes, absorbers, or distillation. Two state-of-the-art recuperation systems are briefly described in this paper.