Pharmaceutical dichloromethane waste gas recovery compression condensation membrane separation technology

Pharmaceutical dichloromethane waste gas recovery compression condensation membrane separation technology

Dichloromethane is widely used as an extraction and crystallization solvent in the production of raw materials such as cephalosporins and amoxicillin in the pharmaceutical industry. Dichloromethane has low boiling point (about 40 ℃), fast volatilization, and belongs to halogenated hydrocarbon VOCs.waste gas treatmentIt is a recognized difficulty in the industry.

Processing difficulties and limitations of traditional processes

Methylene chloride waste gas treatment faces three main problems. One is the low boiling point, volatile fast at room temperature,activated charcoalAdsorption saturation speed, frequent carbon exchange, saturated carbon as a hazardous waste disposal cost is not low. Two is containing halogen, when the combustion method is used, it is easy to produce dioxin and other toxic by-products at high temperature, and hydrogen chloride will cause corrosion to the equipment. Third, the emission standards are strict, and the concentration exceeds the standard and faces the risk of environmental penalties.

In order to effectively liquefy methylene chloride, the traditional single condensation process needs to reduce the temperature to minus 20 ℃ or even lower, and the refrigeration energy consumption is high. The adsorption process is faced with the problems of rapid saturation, frequent carbon exchange and high cost of hazardous waste disposal.

Technical Route of Compression Condensation Membrane Separation

Compression-condensation membrane separation technology provides a mature recovery scheme for dichloromethane off-gas. The process uses a combination of "compression condensation membrane separation" to form a closed cycle.

The exhaust gas is first pressurized by the compressor to increase the partial pressure of dichloromethane and create conditions for subsequent condensation. The pressurized gas enters the multi-stage condensation unit, and most of the dichloromethane is changed from gaseous to liquid by gradual cooling, and the liquefied solvent is separated by the collection tank and can be directly recycled for production.

The tail gas after the condensation treatment still contains a small amount of methylene chloride that is not liquefied, and this part of the gas enters the membrane separation unit.gas separation membraneTaking advantage of the difference in permeation rate between dichloromethane molecules and air molecules in the membrane material-dichloromethane preferentially permeates 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. Air is trapped and discharged up to standard. Through the concentration cycle of the membrane unit, the system's capture efficiency of dichloromethane is significantly improved, the overall recovery rate can reach more than 95%, and the exhaust emission concentration after treatment can be stably controlled at a low level.

Process advantages

High security. Membrane separation is a purely physical process that involves no combustion or open flames, thereby eliminating the risk of dioxin formation at the source. The equipment operates without open flames and is well-suited for use in pharmaceutical explosion-proof workshops.

The operation cost can be controlled. It is driven by electric power, does not consume natural gas, does not replace consumables such as activated carbon, and does not produce hazardous waste. Compared with the traditional cryogenic technology, compression condensation combined with membrane separation can reduce the comprehensive energy consumption.

Resource recycling. The recovered dichloromethane has a high concentration and can be directly reused in the production line, reducing the cost of raw material procurement. There is no replacement of consumables for the equipment, and the daily maintenance is mainly to clean the heat exchanger and check the pressure difference of the membrane module.

Skid-mounted and automation

The equipment adopts a skid-mounted structure. The compressor, condenser, membrane module and control system are integrated on the 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 a PLC-based fully automatic control system, it automatically starts and stops based on the generation of exhaust gases, eliminating the need for dedicated personnel on duty.

LuoyangWohong PetrochemicalEquipment Co., Ltd. focuses on the field of VOCs membrane recovery, and can provide process design and equipment manufacturing services for compression condensation membrane separation technology according to the specific concentration, air volume, temperature and other working conditions of dichloromethane waste gas from pharmaceutical factories. Before selecting equipment, it is recommended to first complete a site condition assessment and let the data guide your decision.