During the production stages such as feeding, reaction pressure relief, vacuum devolatilization, and displacement exhaust, chemical reaction vessels will continuously emit VOCs organic exhaust gas, which includes various organic solvents such as ketones, esters, alcohols, aromatic hydrocarbons, halogenated alkanes, etc. Most chemical reaction vessels follow batch process intermittent exhaust, and the exhaust conditions have significant pulse characteristics. At the moment of pressure relief, the gas flow rate and organic matter concentration sharply increase, and the exhaust volume rapidly decreases during the intermittent stage of the process. The fluctuation characteristics of the operating conditions are very prominent. The airflow discharged from the kettle often carries reaction material droplets, small solid particles, and saturated water vapor. Some halogenated solvents hydrolyze when they come into contact with water to produce acidic substances, which can cause corrosion to pipelines and equipment. Organic media are generally flammable and explosive, and pulse type concentration shocks also increase operational risks. High standards are proposed for the corrosion resistance, impact load resistance, and safety protection design of the recovery unit. Traditional treatment processes have insufficient adaptability to the pulse exhaust conditions of reaction vessels, making it difficult to simultaneously meet the dual needs of meeting exhaust emissions standards and organic solvent resource recovery.
The incineration process can achieve exhaust gas purification treatment, but a large amount of organic solvents with reuse value in the reaction kettle exhaust are directly burned, resulting in waste of raw material resources. Gas containing halogenated components will generate corrosive products after high-temperature incineration, which will corrode the back-end pipeline facilities. A complete exhaust gas post-treatment system is needed, and equipment investment and daily operation and maintenance costs will remain high for a long time.activated charcoalAdsorption is a pollutant transfer treatment method that cannot achieve solvent recovery. Faced with intermittent concentration shocks in the reaction kettle, the adsorption material is prone to rapid saturation and adsorption penetration, requiring frequent shutdown and replacement of adsorption consumables. The output of hazardous waste is large, continuously increasing the cost of material procurement and hazardous waste disposal for enterprises. The simple condensation process relies on low-temperature liquefied solvents, which are limited by the partial pressure of organic vapor. The recovery effect is only acceptable during periods of high exhaust concentration. When the exhaust concentration drops, the solvent recovery efficiency will significantly decrease, and the overall resource utilization treatment effect is not stable enough.
The compression condensation film coupling process belongs to a pure physical treatment path, with no combustion or chemical reactions throughout the process, and can adapt well to the pulse fluctuation working conditions of chemical reaction kettle exhaust. The exhaust first enters the pre-treatment unit and is filtered through a multi-stage foam removal structure to remove material droplets, solid impurities, and free water carried by the airflow, preventing impurities from entering the core unit at the rear end and causing blockage and damage to the heat exchanger and membrane components. After purification, the gas is sent to the compression unit to increase the organic vapor partial pressure and improve the solvent liquefaction conditions. It is then transported to the multi-stage gradient condensation module for gradient cooling based on the boiling point differences of different solvents. Most of the organic solvents liquefy and precipitate here, completing the initial recovery.
After condensation, the remaining tail gas still has some residual organic solvent, which will be sent to the organic membrane separation unit, and the component enrichment and separation will be completed by using the selective permeability characteristics of the membrane material to the organic solvent and air. The purified tail gas is discharged outward, and the enriched high-concentration organic gas stream flows back to the compressor inlet and re-enters the system for recycling. The closed-loop operation mode fully exploits the solvent recovery potential. After precipitation filtration and index detection, the recovered organic solvent can be returned to the production process for reuse after meeting the process requirements, recovering the solvent resources lost in the waste gas, reducing the generation of hazardous waste from the source, and reducing the comprehensive cost of raw material procurement and hazardous waste disposal.
In view of the working condition characteristics of the exhaust pulse fluctuation of the chemical reactor, the unit configuration design needs to conform to the actual production on site. Corrosion-resistant materials are selected for pipelines, valves and heat exchange components in contact with exhaust gas to resist acid corrosion caused by hydrolysis of halogenated media and ensure long-term continuous operation of the unit. The unit is equipped with complete overpressure, overtemperature, medium leakage monitoring and automatic interlocking protection mechanism to deal with pulse concentration impact and avoid potential safety hazards caused by flammable and explosive media. The automatic control system is equipped with frequency conversion control logic, which can dynamically adjust the operating load of the unit according to the instantaneous changes of exhaust air volume and concentration, adapt to the intermittent pulse exhaust characteristics of the reactor, avoid overload operation or invalid idling of the equipment, and control the overall energy consumption. The pre-pretreatment stage intercepts droplets and impurities, forms effective protection for precision parts such as membrane modules and heat exchangers, and prolongs the service life of the unit. Process design needs to collect on-site measured exhaust air volume, component ratio, concentration range, water content and other data to carry out customized accounting, can not directly apply general models, in order to ensure the stability of VOCs governance standards, and effectively realize the organic solvent resource recovery and cost reduction.
Mr. Li 13526990215
Hotline
