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What is the oil and gas recovery adsorption+absorption treatment process?
In the fields of petrochemical industry, printing, artificial leather, electronic components, baking varnish and medicine, volatile organic compounds (VOCs) are usually used as solvents. If these organic solvents volatilize into the atmospheric environment, they will not only cause serious pollution to the atmospheric environment, but also cause harm to human health after the human body breathes in the polluted gas. For example, benzene volatilizes into the atmospheric environment as a solvent, which can not only be absorbed by human skin, but also enter the human body through the respiratory system, causing chronic or acute poisoning. Benzene compounds will not only cause certain damage to the central nervous system of the human body, but also may cause disorders of the nervous system. After entering the human body, they will also harm blood and hematopoietic organs, and may even have bleeding symptoms or suffer from septicemia. Under the action of oxidation, benzene can be oxidized into phenol in the organism, resulting in abnormal liver function, which is very detrimental to the growth and development of bone, and induces aplastic anemia. Therefore, ACGIH listed benzene as a potential carcinogen. Halogenated hydrocarbon compounds can cause neurological syndrome, thrombocytopenia, hepatosplenomegaly and other adverse conditions, and are likely to cause cancer.
Therefore, we must control VOC emissions and do a good job in oil and gas recovery. This is not only responsible for the environment, but also for our life and health.
At present, oil and gas recovery and VOC waste gas treatment technologies mainly include condensation+adsorption treatment process, absorption+adsorption treatment process and membrane separation technology.
The absorption+adsorption treatment process uses the porous structure of adsorbent (granular activated carbon and activated carbon fiber) to capture VOC in waste gas. Activated carbon can be desorbed and regenerated. The process of dry vacuum pumping is adopted. The desorbed oil and gas are recycled through the absorption tower. The absorbent used in the absorption tower is low-grade gasoline or light diesel oil in the storage tank area, and kerosene can also be used. The organic waste gas containing VOC is passed through the activated carbon bed, where VOC is absorbed by the adsorbent, and the waste gas is purified and discharged into the atmosphere. The treatment process of absorption+adsorption method is mainly used in places where the temperature is not high, the humidity is not high, and the exhaust volume is large, such as fat and aromatic hydrocarbons, most chlorinated solvents, common alcohols, some ketones and esters, paint spraying, printing, adhesives, etc., especially for the purification and recovery of halides.
Condensation+adsorption treatment process is after the waste gas is separated by absorption and adsorption treatment process. A small amount of oil and gas after desorption is returned to the system inlet for circulation. The exhaust gas leaving the condenser still contains quite high concentration of VOC, which cannot meet the environmental emission standards. Because most VOC is flammable and explosive gas, the VOC content in the gas will not be too high due to the limitation of the explosion limit, so to achieve a high recovery rate, it is necessary to use a very low temperature condensing medium or high pressure measures, and use the condensation+adsorption treatment process. This treatment method is mainly applicable to the treatment of organic waste gas with high concentration and low temperature.
The basis of membrane separation technology is the use of polymer membranes with selective permeability to organic matter. This membrane is easier to penetrate 10-100 times than air to achieve the separation of organic matter. The simplest membrane separation is a single-stage membrane separation system, which directly makes compressed gas pass through the membrane surface to realize VOC separation. The single-stage membrane is difficult to meet the separation requirements due to its low separation degree, while the multi-stage membrane separation system will greatly increase the equipment investment, so there is still a lot of research space for this technology. The membrane separation process is suitable for the recovery of high-concentration and high-value organics, and its equipment cost is high.
Absorption+adsorption treatment process and condensation+adsorption treatment process are the two main treatment methods used in oil and gas recovery on the market at present. Both of them have their own characteristics. Activated carbon adsorbent has strong adsorption capacity, high hardness, and small pressure drop, thus keeping the adsorption capacity stable. Absorption+adsorption adopts imported dry vacuum pump and its accessories