Complete equipment for VOCs solvent recovery in various production conditions of fine chemicals, supplied by Luoyang Wohong Petrochemical Co., Ltd

Under the production mode of switching between multiple varieties of fine chemicals, the workshop alternately produces different types of products, and uses various organic solvents such as ketones, esters, alcohols, halogenated alkanes, etc. during the production cycle. The reaction kettle, extraction station, centrifugal device, distillation tower top, and material transfer point continuously release VOCs waste gas. Affected by product batch change, kettle cleaning and flushing, workstation switching, equipment start stop and other operations, the composition of exhaust gas dynamically changes with the production plan, and the organic concentration fluctuates greatly. The concentration rapidly increases during feeding, pressure relief and venting, and drops during equipment cleaning and standby stages. The air volume, composition, and concentration have no fixed pattern, which belongs to a typical complex and variable exhaust gas working condition. The exhaust gas flow often carries material droplets, fine solid particles of intermediates, and saturated water vapor. Some halogenated solvents hydrolyze with water vapor to generate corrosive media, which can cause corrosion damage to collection pipelines and internal components of equipment. Most of the multi variety production workshops belong to Class A and Class B explosion-proof control areas, with high material switching frequency. They have very strict comprehensive requirements for the multi-component compatibility, resistance to random concentration impact, impurity tolerance, anti cross contamination design, explosion-proof safety interlock system, and wide working condition adaptive operation ability of the complete set of equipment.

Traditional waste gas treatment processes face many application shortcomings in the complex waste gas conditions of multi variety switching production. The incineration process can oxidize and decompose organic pollutants, but various organic solvents with recycling value in the exhaust gas are directly burned, resulting in high material loss. When the exhaust gas contains halogenated components, high-temperature combustion can easily generate corrosive and toxic by-products, requiring the construction of complex flue gas post-treatment systems. Equipment investment, fuel consumption, and daily operation and maintenance costs remain high for a long time.activated charcoalAdsorption is a pollutant transfer treatment method that cannot complete solvent recovery. Faced with frequent component changes and random switching of high and low concentrations in exhaust gas, combined with material droplets and impurities carried by the intake air, the adsorption packing is prone to gel blockage, quickly reaching adsorption saturation, requiring frequent shutdowns and replacement of adsorption consumables. The output of hazardous waste is large, and the later operation and maintenance burden of the enterprise is heavy. The simple condensation process relies on low temperature to achieve solvent liquefaction, and the recovery effect is ideal only under high concentration exhaust gas conditions. During product switching and equipment standby stages, the exhaust gas concentration decreases, the organic vapor partial pressure is insufficient, and the solvent recovery efficiency is greatly reduced. A large number of organic components are discharged with the exhaust gas, making it impossible to achieve all-weather stable resource treatment. A large number of project practices have shown that a single process mode is difficult to adapt to the real operating conditions of multi variety production with variable components and random fluctuations in working conditions. The equipment processing capacity is insufficient during high concentration impact, the process adaptability deteriorates during component switching, and the emission indicators in the low concentration stage are easily exceeded. It is impossible to simultaneously meet the multiple demands of safety production, environmental compliance, and solvent recovery benefits.

The compression condensation film is coupled with a complete set of physical treatment processes, which operate without combustion or chemical reactions, making it highly suitable for VOCs solvent recovery equipment in various production conditions of fine chemicals. After the exhaust gas generated by each production station is collected through a closed negative pressure gas collection pipeline network, it first enters the equipment pretreatment unit. The multi-stage filtration and foam removal structure is used to remove solvent droplets, solid particles, and free water carried by the airflow, avoiding impurities from entering the compressor, heat exchanger, membrane components and causing blockage, adhesion, and membrane element pollution. In response to the diverse types of impurities in the production waste gas of multiple varieties, a graded interception structure is adopted for pretreatment, which completes filtration and purification step by step according to the particle size of impurities, reducing the risk of contamination and damage to the precision core components at the back end and extending the service life of the entire equipment. After pre-treatment and purification, the exhaust gas enters the compression unit to increase the organic vapor partial pressure and create favorable conditions for solvent liquefaction. The gas is then sent to the multi-stage gradient condensation module, where gradient cooling is carried out based on the boiling point differences of various components inside the mixed solvent. Most of the organic solvents liquefy and precipitate, completing the preliminary solvent recovery work.

After condensation, the exhaust gas still retains some un liquefied organic components, which enter the organic membrane separation unit. With the help of polymer membrane materials, the difference in permeation rate between organic solvent molecules and air molecules is used to complete the enrichment and concentration of organic components. The exhaust gas that meets the standards is discharged to the outside, and the high concentration organic gas flow enriched on the membrane side is refluxed to the inlet of the compressor, forming a closed-loop system and further improving the overall recovery rate of multi-component solvents. The liquid mixed organic solvents obtained from recycling can be sent back to the production process for reuse after precipitation filtration and indicator testing, and the quality meets the production process requirements. Various solvent resources that were originally lost due to tail gas volatilization can be recovered, reducing the amount of hazardous waste generated from the source and lowering the cost of solvent procurement and hazardous waste disposal for enterprises. The entire set of equipment can adopt a modular integration mode, which is prefabricated in the factory and requires a small amount of on-site installation work. It can directly connect with the existing exhaust gas collection pipeline network in the workshop, greatly reducing the downtime of technological transformation and minimizing the interference caused by product rotation production operations.

The entire equipment is designed strictly in accordance with the fine chemical explosion-proof standards. All pipelines, valves, and heat exchange components that come into contact with the exhaust gas medium are made of corrosion-resistant materials to resist the acidic corrosion caused by the hydrolysis of halogenated media and ensure long-term continuous operation of the equipment. Equipped with complete overpressure, overtemperature, combustible gas detection and automatic interlocking protection mechanisms, it can respond to random concentration impacts caused by product switching, pressure relief and venting, and avoid various safety risks caused by flammable and explosive media. The intelligent variable frequency automatic control system can adjust the equipment operating load in real time according to the intake air volume, component changes, and concentration, adapt to the irregular emission characteristics of exhaust gas caused by multi variety batch production, avoid equipment overload operation or ineffective idling, and optimize the overall energy consumption level. Based on on-site measurements of exhaust gas flow rate, component variation range, concentration fluctuation range, impurity situation, pipeline layout, and workshop site conditions, customized design is completed. Without using standardized universal models, we can provide full process services including process design, equipment manufacturing and production, on-site installation and commissioning, operator training, and later operation and maintenance.Standardized production and manufacturing, standardized on-site construction, and regular inspection and maintenance ensure the long-term reliable operation of the complete set of VOCs solvent recovery equipment, achieving the dual goals of meeting exhaust standards for fine chemical multi variety production conditions and reducing costs for organic solvent resource recovery.