The distillation process is the core link in solvent separation and purification in fine chemical production. A large amount of non condensable tail gas is continuously discharged from the top of the distillation tower, and the tail gas is enriched with various high-value organic solvents such as dichloromethane, ethyl acetate, acetone, and alcohol ketones. The distillation tail gas has the characteristics of continuous emission but large load fluctuation with tower and kettle operating conditions, high organic matter concentration, and carrying a large number of solvent droplets. If the distillation tail gas is directly vented, it will not only cause a large amount of continuous solvent loss, but also directly increase the cost of raw material consumption for enterprises. The accumulation of combustible steam in the distillation area will also pose safety hazards to workshop production, and cannot meet the relevant requirements for VOCs emission control.
There are many shortcomings in traditional treatment methods for distillation tail gas conditions. The incineration process directly burns and destroys recyclable organic solvents, resulting in significant material losses. The combustion of halogenated components also generates corrosive and harmful substances, leading to high equipment energy consumption and significant investment in later operation and maintenance.activated charcoalAdsorption belongs to pollutant transfer treatment and cannot complete solvent liquefaction recovery. Fluctuations in the concentration of distillation tail gas can easily cause rapid saturation of adsorption materials, posing a risk of heat accumulation and fire. The operation process continues to produce hazardous solid waste, requiring frequent replacement of adsorption consumables. Single condensing equipment is limited by steam partial pressure conditions. When the distillation conditions fluctuate and the inlet concentration fluctuates, the solvent liquefaction recovery efficiency changes accordingly. It is difficult to achieve stable compliance with residual tail gas standards and meet the long-term continuous operation needs of the distillation unit.
The organic solvent liquefaction and recovery equipment adopts a fully physical process of compression condensation membrane coupling. The entire process does not involve combustion or chemical reactions, and does not produce secondary pollutants. It is specifically developed for non condensing tail gas conditions at the top of the distillation tower. The tail gas discharged from the top of the distillation tower is introduced into the equipment through a closed pipeline and transported to the buffering and stabilizing unit to eliminate the fluctuations in gas volume and pressure caused by the start stop and load adjustment of the distillation tower, stabilize the inlet conditions of the main engine, and avoid the impact damage of pulse airflow on core components such as compressors and heat exchangers. The exhaust enters the multi-stage pretreatment module to remove solvent droplets, aerosol impurities, and free water carried by the airflow, reduce component corrosion, scaling, and blockage failures, and extend the service life of the entire equipment.
After pre-treatment, the distillation tail gas is compressed and pressurized to increase the partial pressure of organic vapor and create favorable conditions for solvent liquefaction. It is then sent to a multi-stage gradient condensation unit and combined with different boiling points of the mixed solvent to achieve staged cooling and cooling. Most of the organic components are directly liquefied and precipitated, completing the main liquefaction and recovery of the solvent. After condensation treatment, the remaining low concentration exhaust gas enters the polymer membrane separation unit, and the organic components are enriched by the permeability selectivity of the membrane material. The purified exhaust gas meets the emission requirements, and the concentrated high concentration organic gas flow is refluxed to the front end of the equipment for further recycling, further improving the comprehensive liquefaction recovery rate of the mixed solvent. After water separation and precision filtration purification treatment, the liquid solvent obtained from recycling meets the quality standards for process use and can be sent back to the distillation system for re production, reducing the amount of fresh solvent added, lowering hazardous waste output, and balancing tail gas treatment and solvent resource utilization.
The equipment supports integrated configuration of pry and installation, and the whole machine is shipped out after internal assembly, pressure testing, and explosion-proof verification in the factory. On site, only the tail gas pipeline at the top of the distillation tower and the public engineering interface need to be connected. The construction workload is small, the renovation period is short, and it will not cause too much interference to the continuous production of the distillation unit. It is suitable for supporting new distillation units and can also be used for upgrading the tail gas technology of existing distillation systems. The whole machine is designed and selected according to the Class A explosion-proof standards for chemical engineering. All electrical components meet the explosion-proof level, and components that come into contact with corrosive media are made of suitable anti-corrosion materials. The system is equipped with over temperature, over pressure, combustible gas detection interlock protection, and emergency vent bypass to deal with various abnormalities caused by sudden changes in distillation conditions and avoid on-site safety risks. Equipped with an intelligent frequency conversion self-control system, it can adaptively adjust the operating load of the equipment according to changes in the air volume and concentration of the distillation tail gas, reduce ineffective energy consumption, and support long-term unmanned stable operation. It can customize process configurations based on the exhaust gas components, maximum processing gas volume, and on-site land occupation conditions of distillation units, and is widely used in various distillation process exhaust solvent recovery projects in pharmaceuticals and fine chemicals.
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