Chemplast Sanmar’s caustic soda/ chlorine plant based on membrane cell technology at Plant III, Mettur Dam, has installed state-of-the-art safety measures in the chlorine absorption system, with built-in safety features. Taking into account the imperative need to ensure continuous power supply to the chlorine absorption system, an uninterrupted power supply (UPS) system with a capacity of 250 kVA costing about Rs 45 lakh has been installed. The power fed through the UPS ensures continuous and uninterrupted flow in the plant in the event of any sudden power outage.
An incident to test the efficacy and efficiency of the system installed occurred on 1 December 2009. The caustic chlor plant was being operated at 184 TPD caustic production level when one of the LSHS-based generators, generating around 5 MW of power, catering to the auxiliary power requirements of the plant, tripped quite suddenly at 5.36 pm consequent to a technical snag that had developed in its excitation system.
As the chlorine absorption system was fed through the UPS, even after the failure of power supply, no interruption occurred.
Significantly, the readings of the chlorine monitors provided all around the plant recorded zero ppm of chlorine in the vicinity at the time of the power failure.
Under pre-existing conditions, without the benefit of UPS, the pressure seal provided in the chlorine absorption system would blow off leading to localised emission of chlorine to around 2 to 3 ppm (permissible limit is 5 ppm) within the precincts of the electrolyser plant. It would take 40 seconds for the back-up power from the 320 kVA generator.