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Energy Conservation and Emission Reduction NMP Purification and Waste Heat Recovery Solution 丨 Invitation of 2024 Battery Show Europe

NMP (N-Methyl Pyrrolidone) is a solvent used in the production of lithium batteries. It is used to dissolve various electrode materials such as the cathode binder, active material, and conductive agent together, allowing the binder to fully contact with other substances and evenly distribute, important for the improvement of the energy density and coating quality. NMP accounts for 3%-6% of the manufacturing cost of lithium batteries and has high value. However, NMP is also a toxic organic solvent, and many countries have strict emission limits for factory exhaust containing NMP.

Since NMP used as a solvent is widely used in lithium battery production, most of the NMP in actual production is recycled for cost and environmental requirement. At the same time, the energy consumption of the coating process accounts for about 38%-42% of the total energy consumption of the lithium battery production line. If the waste heat from the high-temperature exhaust gases of the coater can be recovered, it will effectively reduce the manufacturing cost of batteries. Therefore, strengthening the recycling and reuse of NMP and waste heat in the process has significant economic and environmental benefits.

Introduction of NMP and Waste Heat Recovery Device

Megaunity NMP and waste heat recovery device achieve energy conservation and consumption reduction of ventilation system, NMP purification through heat recovery, dehumidification, and filtration, meeting the requirements of temperature, cleanliness, NMP concentration and pressure inside the oven during the coating and drying process in the cathode electrode production of lithium batteries.

Megaunity independently developed modular unit can achieve precise control of the NMP concentration inside the oven by automatically adjusting the exhaust air volume according to the change in NMP concentration inside the oven, reducing the circulating air volume, and saving more than 30% energy compared to existing technologies.

The high-temperature and high-concentration NMP gas emitted from the coating oven has undergone heat recovery and NMP recovery through heat exchangers, cooling and condensers, with approximately 90% of the air returning to the oven. The remaining 10% undergoes adsorption purification using molecular sieve wheels to reach emission standards for NMP concentration before being released into the atmosphere.

Megaunity's double rotary wheel exhaust gas purification device meets the emission standards of Europe and the United States. After the first-stage rotary wheel adsorption purification, it undergoes secondary rotary wheel deep adsorption purification, reducing the NMP content in the exhaust gas to ≤1 mg/Nm³ for standard discharge. The overall purification rate of the system can reach 99.7%.

The NMP recovery system uses Megaunity developed high efficiency heat exchangers, allowing the high temperature gas emitted by the coating machine to undergo heat exchange with the low temperature gas after NMP condensation treatment, maximizing the recovery of emitted heat energy. The heat exchange efficiency can reach up to 90%.