Selection of Dichloromethane Recovery Equipment
The recovery of dichloromethane (DCM) is primarily challenged by its high vapor pressure, low boiling point (39.8°C), and corrosive nature due to chlorine content.
Mainstream Process Equipment Details
Condensation-Adsorption Combined System: This is currently the dominant solution, with processing capacity customizable based on parameters such as airflow volume and concentration. A typical product is the energy-saving recovery equipment from Wuhan Xurihua Environmental Protection, which integrates a "low-temperature condensation module" and an "adsorption recovery module," utilizing heat exchangers to recover thermal energy from exhaust gases for improved energy efficiency.
Resin Adsorption-Vapor Desorption System: This is a more advanced adsorption technology. The system employs resin adsorbents (such as HDV-type polymer nano-adsorbents from Jiangsu HAIPEI), which offer higher adsorption efficiency (over 99%) compared to activated carbon, along with greater durability and easier regeneration. The system typically uses steam for desorption, eliminating the need for complex vacuum equipment.
Compressor refrigeration unit: As the core pre-treatment equipment in integrated processes, it provides powerful driving force for the "compression and condensation" stage. For example, Nanjing Dule's customized BLS200 refrigeration unit for specific projects employs a three-stage cascaded temperature reduction technology, precisely matching condensation processes by lowering exhaust gas temperature to -35°C, meeting pre-treatment requirements under high-concentration conditions.
Absorption-Distillation Combined System: This method uses a high-boiling-point solvent (such as white oil) to absorb dichloromethane from exhaust gas, followed by separation and purification through equipment such as double-effect evaporators and distillation columns. It is particularly suitable for treating large volumes of dichloromethane-containing white oil mixtures generated in processes like lithium battery separator extraction, offering a high level of resource recovery.
Key Practical Considerations for Equipment Selection
Dichloromethane recovery systems involve multiple technologies and customized designs; key factors to consider during selection include:
Define key performance indicators:
Overall recovery rate and emission concentration: Focus on meeting stringent emission standards, such as a non-methane total hydrocarbon removal efficiency of ≥97% and a dichloromethane emission limit of ≤100 mg/m³.
Energy consumption metric: Requires suppliers to provide key data, such as steam consumption per ton of dichloromethane recycled. This value can vary by 0.8 to 1.5 tons among different manufacturers, directly determining long-term operating costs.
Material Corrosion Resistance: The main equipment body should be made of corrosion-resistant materials, such as 316L stainless steel or Teflon coating, which is fundamental to ensuring the system's long-term stable operation.
Beware of selection pitfalls:
Don't focus solely on the initial investment; low-cost equipment may lead to high operating costs later due to outdated technology or poor materials.
Low-end assembled equipment that simply uses generic carbon tanks and simple condensers should be avoided, as they typically fail to maintain stable compliance over the long term.
