Valves in action ─
Pressure reducer DM 762 ATEX
Tank blanketing in car accumulator production
Electromobility is an important cornerstone of the energy transition. Electric and hybrid vehicles now shape the everyday image of the mobile society. Lithium-ion batteries are the very core of these modern means of transportation. They have had the highest growth rates in the global battery market for years. To strengthen intra-European supply chains in the automotive industry, a Japanese chemical company has built a modern plant in the Czech Republic to produce electrolytes for lithium-ion car batteries. The annual production capacity is 20,000 t.
Due to its low atomic mass and low density, lithium is currently considered the most suitable metal for modern energy storage technology. In the battery system, the electrolyte has the task of acting as a medium to maintain ionic current transport between the polarized electrodes. By ensuring physical properties such as temperature resistance and high voltage loadability, it determines the safety and service life of the battery. Lithium-ion battery cell electrolytes consist of a solvent supplemented with a salt, for ex. lithium hexafluorophosphate, a lithium salt of the unstable hexafluorophosphoric acid. Other additives can be mixed in, for ex. redox shuttle additives (RSA), which use redox reactions to remove excess charge from the cell in a controlled process. Electrolyte liquids are flammable.
TASK // Inertisation of the electrolyte tanks
In the Czech factory, the electrolytes are temporarily stored in a tank before further transport. Here, the flammability of the electrolyte liquid requires tank blanketing. In this process, the empty volume in the head space of the tank is pressurized with inert nitrogen in order to maintain a low permanent overpressure, even in the case of varying gas pressures, such as those caused by temperature changes or fluctuating filling levels. The DM 762 ATEX self-acting pressure reducing valve ensures that the inert state is continuously maintained.
SOLUTION // Millibar control valve DM 762 ATEX
The DM 762 ATEX pressure reducing valve is a diaphragm-controlled, spring-loaded proportional control valve for very low back pressures at medium flow rates. It captures the fluctuating pressures in the headspace of the electrolyte tank and keeps the pressure of the inert gas constant. The valve controls the nitrogen inlet pressure from 1.5 barg to 0.03 barg outlet pressure. Its construction of deep-drawn AISI 304 stainless steel with PTFE cone seal and protective film and EPDM diaphragm provides excellent corrosion resistance in the critical atmosphere of the chemical tank. The customer required a silicone-free as well as oil and grease-free design. With equipotential bonding between the valve components, fused body connections and a grounding lug, the valve is ATEX-compliant in accordance with the product directive 2014/34/EU and ensures safe storage of the chemicals in the customer's facility.
