Spray workshop waste gas treatment compression condensation membrane separation and recovery of solvent, reduce coating costs

Spraying workshopwaste gas treatmentCompressed condensation membrane separation and recovery of solvent, reducing coating costs

Spraying workshop is the key place of VOCs waste gas treatment. Automobile, furniture, mechanical equipment and other products of the coating production line, the exhaust gas is characterized by large air volume, relatively low concentration, usually between 200 and 600 milligrams per cubic meter, containing toluene, xylene, ethyl acetate and other organic matter. traditional treatmentRTOCombustion is the main, the solvent is burned, and the annual gas cost of hundreds of thousands plus the disappearance of the solvent makes the coating cost high. The compression condensation membrane separation process provides a recovery route to recycle the solvent while meeting the discharge standards, directly reducing the coating cost.

Process Principle

The application logic of the compression condensation membrane separation process in the spraying workshop is "first concentration, then recovery". The exhaust gas is first pressurized by the compressor to increase the partial pressure of organic matter, and then enters the multi-stage condensation unit to cool down. The condensing unit adopts a hierarchical temperature control strategy, and the high boiling point components can be liquefied in a large amount in a higher temperature range, and the low boiling point components are trapped in a lower temperature range. The liquefied solvent is separated by the collection tank and can be directly used for coating blending.

The exhaust gas after condensation treatment still contains a small amount of organic matter that has not been liquefied, and this gas enters the membrane separation unit.gas separation membraneTaking advantage of the difference in permeation rate between organic molecules and air molecules in the membrane material, organic matter preferentially permeates through the membrane layer to form concentrated gas, which is sent back to the compressor inlet and mixed with fresh exhaust gas before entering the condensation process again. The air is trapped and discharged to the standard. Through the concentration cycle of the membrane unit, the capture efficiency of the system for organic matter is significantly improved.

Economic analysis

The spraying workshop adopts the compression condensation membrane separation process, and the economy is reflected in two aspects. First, the recovered solvent is directly reused in production, reducing the purchase of fresh solvents. Second, the equipment is driven by electricity and does not consume natural gas.activated charcoalSuch as replacement of consumables, does not produce hazardous waste. Taking the medium-scale coating line as an example, the annual consumption of solvent can reach tens of tons to hundreds of tons, and the recovery rate is calculated at 90%. Dozens of tons of solvent can be recovered every year, directly reducing the coating cost by hundreds of thousands of yuan. The process does not involve combustion, no open flame, and has good applicability in the explosion-proof place of the spraying workshop.

The equipment adopts a skid-mounted structure, and each unit is integrated on a steel base. The assembly and debugging are completed before leaving the factory. The site can be put into operation only by connecting the power supply and gas circuit. The installation period is short and the floor area is small. Equipped with PLC automatic control system, automatic start and stop according to the exhaust gas, no need for special personnel on duty.

Scope of application

The process is suitable for VOCs waste gas with high concentration and solvent recovery value in spraying workshop. For exhaust gas with low concentration or no solvent recovery value, other technical routes may be more appropriate. Before selection, the exhaust gas condition detection should be completed to obtain accurate basic parameters such as concentration, composition and air volume. LuoyangWohong PetrochemicalEquipment Co., Ltd. can provide process design and equipment manufacturing services according to the specific working conditions of the spraying workshop. First do the condition test, take the data to speak, according to the concentration, composition, air volume matching equipment specifications, to avoid excessive configuration, is the key to control investment and operating costs.