In the fine chemical production process, multiple stations such as reactor pressure relief, distillation non-condensable gas, vacuum desolvation, crystallization centrifugation, material transfer, tank size respiration, etc. will continue to produce VOCs waste gas with complex components. The waste gas mostly contains high-value organic solvents such as dichloromethane, ethyl acetate, acetone, alcohols and ketones. Most of these exhaust gases are intermittent emissions, with large fluctuations in air volume and concentration, air entrainment of solvent droplets and aerosols, and some media with halogenated corrosion characteristics. If the waste gas is not effectively disposed of and directly discharged, on the one hand, it will cause a large amount of solvent material loss and increase the purchase cost of raw materials for enterprises. On the other hand, the accumulation of combustible steam in the workshop will bring hidden dangers to safe production, and it is difficult to meet the requirements of VOCs environmental protection emission control.
The traditional waste gas disposal scheme has obvious shortcomings in the complex production conditions of fine chemical industry. The incineration process directly incinerates organic solvents with recycling value, resulting in serious resource loss. The combustion of halogen-containing media will generate corrosive by-products, high energy consumption of equipment, and high operation and maintenance costs in the later period.activated charcoalAdsorption only realizes the transfer of pollutants, can not complete the solvent recovery and reuse, pulse-type exhaust gas impact is easy to cause the adsorption material to quickly saturate the plate, there is a risk of heat accumulation and fire, the operation process continues to produce dangerous solid waste, consumables replacement frequency is high. The single condensation process is limited by the partial pressure of organic vapor, and the recovery efficiency fluctuates in the face of mixed waste gas with frequent changes in concentration, making it difficult to balance the effect of waste gas disposal with the benefits of solvent recovery.
Solvent recovery skid-mounted complete unit adopts compression-condensation-film coupling full physical process, the whole process without combustion, no chemical reaction intervention, will not generate secondary pollutants. The main engine, pipeline valves, explosion-proof instruments and automatic control modules of the whole unit are all integrated on the unified skid-mounted base. The assembly, pressure test and explosion-proof calibration are completed in the factory, and the whole unit is delivered to the site after delivery. The organic waste gas scattered at each production point is collected centrally through a closed negative pressure pipe network and sent to a buffer pressure stabilizing unit to eliminate the pressure and gas volume pulse impact caused by intermittent exhaust, stabilize the intake condition of the main engine, and reduce the damage of fluctuating airflow to core components. The exhaust gas enters the multi-stage pretreatment module to remove the solvent droplets, fine aerosols and free moisture inside the airflow layer by layer, protect the compressor, heat exchanger, membrane module and other precision components, reduce corrosion, scaling, blockage failure, and extend the overall service life of the equipment.
The pre-treated exhaust gas is compressed and pressurized, the organic vapor partial pressure is lifted, the solvent liquefaction phase change conditions are optimized, and the solvent is transported to the multi-stage gradient condensation unit, relying on the different solvent boiling point differences to cool down, most of the organic components are directly liquefied and separated, and the main body of the solvent is recovered. The low-concentration organic tail gas remaining after condensation is sent to the polymer membrane separation unit, relying on the permeability of the membrane material to selectively enrich the organic components, the purified tail gas reaches the emission target, and the concentrated high-concentration organic gas flow is recycled back to the front end of the equipment to further improve the comprehensive recovery efficiency of the mixed solvent. The recovered liquid solvent is separated into water and purified by precision filtration, and the quality meets the production reuse standard. It can be returned to the workshop production process for recycling, reducing the cost of solvent procurement, reducing the amount of hazardous waste disposal, and simultaneously realizing the compliance disposal of waste gas and the income of material resource utilization.
The skid-mounted integration mode greatly reduces the on-site construction workload. The site only needs to interface with the exhaust gas pipeline and the public works. The installation and commissioning period is short. It supports the transformation of the old factory area without stopping production and minimizes the impact on the continuous operation of the production line. It is not only suitable for new fine chemical projects, but also suitable for the technological transformation and upgrading of the old factory area with limited sites. The whole machine is designed and selected according to Class A explosion-proof standard of chemical industry. All electrical components meet the explosion-proof grade. Components in contact with corrosive media are equipped with suitable anti-corrosion materials. The system is equipped with over-temperature, over-pressure, combustible gas detection interlock protection and emergency venting bypass to calmly deal with all kinds of sudden abnormal conditions and avoid on-site safety risks. Supporting intelligent frequency conversion automatic control system, can follow the exhaust air volume, concentration dynamic adaptive adjustment of operating load, reduce ineffective energy consumption, support long-term unattended stable operation. The skid-mounted size and process layout can be customized according to the enterprise waste gas composition, treatment air volume and on-site floor space, and are widely used in various VOCs waste gas disposal and solvent recovery projects in medicine and fine chemicals.
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