The consumption of liquid nitrogen is one of the most relevant supply costs in composite material factories. Therefore, in Aciturri Aerostructures Boecillo we launched an initiative for its reduction, within the 2018 operational efficiency improvement plan.
In the form of gas, it is the most suitable medium for pressurization processes of autoclaves, because it doesn’t affect the polymerization reactions since it is a neutral gas. Also, it reduces the oxygen content in autoclave to levels that eliminate fire risks during the curing process.
In a first phase, we´ve implemented various improvements to reduce its consumption, based on the programming of cycles and loads. Then, we detected a greater opportunity if the pressurization process was completely redesigned, mixing compressed air and nitrogen, instead of using 100% of nitrogen.
To make this new process possible, we made a significant investment in the installation of a compressor plant capable of producing enough compressed air to pressurize the three autoclaves of the plant to 10 bar. Once mixed with the minimum nitrogen content, it guarantees an inert atmosphere inside the autoclave.
This new system will reduce our nitrogen consumption by up to 40%, avoiding the emission of 200 tons of CO2 (derived from the excess energy needed to produce liquid nitrogen instead of air).
Within the process of continuous improvement, we are also evaluating the feasibility of new initiatives based on the recovery of nitrogen used in the cycles, as well as its generation "in situ", to make our process even more efficient.