In the fine chemical solvent recovery workshop, solvent storage tank, distillation device, desolubilization kettle, mother liquor transfer tank, hazardous waste solvent temporary storage tank and other points will continuously release mixed organic waste gas, which collects various organic solvent components such as ketones, esters, alcohols, halogenated alkanes and the like. The production conditions of the workshop are complex. Affected by operations such as rectification feed, solvent transfer, storage tank respiration, material pouring and equipment flushing, the air volume, components and concentration of exhaust gas are in a dynamic state. During the operation of material transfer and tank pouring, the concentration of exhaust gas instantly increases, the concentration drops during the static storage stage of equipment, and various solvents are mixed and discharged, which belongs to typical multi-component mixed VOCs exhaust gas. Exhaust gas flow will carry solvent droplets, a small amount of colloid, solid residue and water vapor. Halogenated solvent will hydrolyate with water vapor to generate corrosive medium, which is easy to cause scaling and corrosion of gas gathering pipeline and internal components of equipment. The solvent recovery workshop belongs to Class A and Class B explosion-proof control areas, with a wide variety of media, and puts forward strict requirements on the multi-component compatible processing capability of complete sets of equipment, anti-random concentration impact performance, impurity gum tolerance, explosion-proof interlocking protection system, and long-term stable operation capability under mixed conditions.
The traditional waste gas treatment process has obvious limitations under the condition of mixed organic waste gas in solvent recovery workshop. The incineration process can decompose organic pollutants, but all kinds of organic solvents with recycling value in the waste gas are directly incinerated, and the material loss is huge. When the exhaust gas contains halogenated hydrocarbon components, high-temperature combustion will produce corrosive and toxic by-products, requiring a complex flue gas treatment supporting system, equipment investment, fuel consumption and daily operation and maintenance costs remain high.activated charcoalAdsorption is a pollutant transfer treatment method, and solvent recovery cannot be realized. In the face of mixed exhaust gas with changeable components and random fluctuation of concentration, and superposition of mist droplets and colloidal impurities carried by intake air, the adsorption filler is easy to gel and block, and the adsorption is rapidly saturated. Frequent downtime is required to replace consumables. The output of hazardous waste is large, and the enterprise has a heavy burden on operation and maintenance. The simple condensation process relies on low-temperature liquefied solvent, only in the high concentration range of exhaust gas recovery effect is better, the static storage stage exhaust gas concentration is low, the organic vapor partial pressure is insufficient, the solvent recovery efficiency is greatly reduced, a large number of organic components with the exhaust gas emptying, can not achieve the full-time stable resource treatment. A large number of project practice has proved that a single process mode is difficult to adapt to the actual conditions of mixed waste gas components and large fluctuations in working conditions in the solvent recovery workshop, the processing capacity of high concentration impact equipment is insufficient, the emission of low concentration working conditions is easy to exceed the standard, and the multiple objectives of safe production, environmental protection compliance and solvent recovery income cannot be taken into account.
The compression condensing film is coupled with a complete set of full physical treatment process, without combustion and chemical reaction, which is very suitable for the complete set of equipment for mixing organic waste gas in the fine chemical solvent recovery workshop. The mixed waste gas generated at each production and waste point in the workshop is collected and transported to the complete set of equipment through the negative pressure closed pipe network. The waste gas first enters the pretreatment unit, relying on the multi-stage filtration defoaming structure to remove the solvent droplets, colloidal residues, solid particles and free moisture carried by the airflow, so as to prevent impurities from entering the back-end compressor, heat exchanger and membrane module, causing blockage, glue formation and membrane element pollution. In view of the complex and diverse working conditions of mixed exhaust gas impurities, the pretreatment unit adopts a hierarchical interception structure, and the filtration and purification are completed step by step according to the impurity particle size, which effectively protects the precision core components of the back end and prolongs the service life of the entire equipment. After pretreatment and purification, the waste gas enters the compression unit to increase the partial pressure of organic vapor and create favorable conditions for solvent liquefaction. The gas is sent to the multi-stage gradient condensation module to carry out gradient cooling based on the difference of boiling points of various solvents, and most organic solvents are liquefied and separated, thus completing the preliminary solvent recovery.
After condensation, the tail gas still contains some unliquefied organic components, which then enter the organic membrane separation unit. There, the difference in permeation rates between organic solvent molecules and air molecules through the polymeric membrane material is utilized to enrich and concentrate the organic components. The treated exhaust gas is discharged to the atmosphere, while the high-concentration organic gas stream enriched on the membrane side is recirculated back to the compressor inlet, forming a closed-loop system that further enhances the overall recovery rate of various mixed solvents. The recovered liquid mixed organic solvent can be returned to the solvent recovery process for reuse after the quality meets the production process requirements of the workshop after precipitation filtration and index detection, so as to recover all kinds of solvent resources originally lost with the volatilization of waste gas, reduce the amount of hazardous waste generated from the source, and reduce the enterprise's solvent procurement cost and hazardous waste disposal expenses. The whole set of equipment supports the skid-mounted integration mode, the factory completes prefabrication, and the on-site installation work is small, which can directly connect with the original gas gathering pipe network of the workshop, greatly reducing the shutdown cycle of technological transformation and reducing the interference to the continuous production operation of the solvent recovery workshop.
The whole set of equipment is designed in strict accordance with the fine chemical explosion-proof specifications. All pipelines, valves and heat exchange components in contact with exhaust gas medium are made of corrosion-resistant materials to resist acid corrosion caused by hydrolysis of halogenated medium and ensure long-term continuous operation of the equipment. Equipped with a complete overpressure, overtemperature, combustible gas detection and automatic interlocking protection mechanism, it should deal with the random concentration impact caused by material inversion and material transfer, and avoid various safety risks caused by flammable and explosive media. The intelligent frequency conversion automatic control system adjusts the operating load of the equipment in real time according to the intake air volume and concentration, adapts to the emission characteristics of the mixed exhaust gas without regular fluctuation, avoids the overload operation of the equipment or the ineffective idling, and optimizes the overall energy consumption level. Customized design is completed according to the on-site measured exhaust gas air volume, component composition, concentration fluctuation interval, colloidal impurity content, pipe network layout and workshop site conditions. Standardized general-purpose models are not applied, and the whole process service from process scheme design, equipment manufacturing and production, on-site installation and debugging, operator training to later operation and maintenance can be provided. Standardized production and manufacturing, standardized on-site construction and regular inspection and maintenance ensure the long-term reliable operation of the complete set of mixed organic waste gas equipment, and realize the dual goals of standard treatment of exhaust gas in fine chemical solvent recovery workshop and cost reduction of organic solvent resource recovery.
Mr. Li 13526990215
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