There are various process routes for VOCs organic gas treatment equipment, including adsorption, absorption, condensation, and membrane separation, each with its own applicable scenarios. However, gas station oil and gas recovery is increasingly using a combination of membrane separation and compression condensation routes. Single processes often neglect one aspect over the other in terms of processing capacity, recovery rate, and operating costs, while combined processes complement each other's strengths and weaknesses. This article starts from the actual working conditions of gas stations, compares mainstream VOCs treatment processes, and explains why the combination route is more worthwhile to choose.
Adsorption method is usedactivated charcoalWhen the adsorbent is used to enrich oil and gas, the treatment effect is good, but it is prone to saturation under high concentration and high flow conditions, requiring frequent regeneration and replacement; The condensation method can directly recover liquid oil products, but to achieve very low emission concentrations, extremely low temperatures are required, and energy consumption increases exponentially with emission requirements; Simple membrane separation can separate oil and gas from air, but the load and processing cost of membrane components are closely related to concentration and flow rate. Gas stations have large fluctuations in gas concentration and high instantaneous flow rates, making it difficult to balance the three goals of recovery rate, energy consumption, and emission concentration with any single process.
The idea of combining membrane separation with compression condensation is segmented relay. The compression condensation section is located in the front, and the bulk oil and gas are condensed and recovered by pressurization and cooling, converting most of the hydrocarbons back to liquid state in one step; The remaining is low concentration exhaust gas, which then enters the membrane separation section for concentration. The membrane module utilizes the difference in permeability between hydrocarbons and air to further enrich residual oil and gas, which is then returned to the front stage for circulation treatment and discharged as clean air. Two stages of division of labor ensure high recovery rates while reducing the concentration of non methane total hydrocarbons to below 10 grams per cubic meter, avoiding the high energy consumption of solely relying on condensation to catch up with low temperatures.
The energy-saving point of the combination process is to control the condensation target temperature relatively loosely, and the rest is covered by membrane separation. Compared to relying solely on condensation to achieve extremely low emissions, the combined route has lower energy consumption and more controllable operating costs under the same emission targets. At the same time, the liquid oil recovered by condensation is directly returned to the tank, and the oil and gas concentrated by membrane separation are circulated again, with almost no resource waste. In the scenario of gas stations running automatically in standby mode around the clock, this segmented operation mode is more in line with actual working conditions and easier to predict maintenance cycles.
Evaluate the process of VOCs organic gas treatment equipment, focusing on five key aspects: first, the treatment depth corresponding to the target emission concentration; The second is the instantaneous processing capacity during peak hours; Thirdly, adaptability to fluctuations in oil and gas concentration; Fourth, long-term energy consumption during operation; The fifth is the cost and cycle of replacing vulnerable parts, especially membrane components. By comparing these five items in the same table, the differences between different process routes become clear at a glance. The WHSH series tertiary oil and gas recovery device is divided into stages based on a processing capacity of 4 to 20 cubic meters per hour, making it convenient to match according to actual working conditions.
Gas station emissions have the characteristics of high concentration, large instantaneous quantity, and significant fluctuations, which are suitable for combining processes to leverage their respective advantages. Compression condensation is responsible for bulk recovery, while membrane separation is responsible for deep separation. The two stages work together to achieve both recovery and compliance. For new governance projects and old station renovations, adopting a mature combination process route ensures more stable equipment operation, greater assurance of compliance, and more cost-effective long-term accounting.
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