Views:1 Author:autower Publish Time: 2019-08-27 Origin:http://www.autower.cn/
Once we get to the gas station,we can always smell the pungent smell of gasoline.Not only do people who are refueling smell uncomfortable,they also pollute the city's air,and there are major security risks.Every time a refueling of a motor vehicle or every transfer of oil from a storage tank to a tanker,a large amount of oil and gas will be quietly volatilized into our air.In the process of loading and unloading gasoline and refueling the vehicle,the oil and gas recovery collects the volatile gasoline and oil,and transforms the oil and gas from a gaseous state to a liquid state through absorption,adsorption or condensation processes to achieve recycling.
1.The significance of oil and gas recovery
It is very important for oil and gas recovery at gas stations.First,oil and gas recovery is conducive to reducing environmental pollution.Gas stations,oil depots,and refineries emit large amounts of oil and gas during the process of unloading oil and refueling.Most of their main components are carcinogenic substances.After ultraviolet irradiation,they will undergo a series of photochemical reactions with other gases to form more toxic pollutants.Therefore,oil and gas recovery reduces the amount of harmful substances such as benzene in the air and protects the environment.Secondly,oil and gas recovery is conducive to increasing the safety of gasoline during storage and transportation.More than 55%of fire and explosion accidents during gasoline storage and transportation are caused by oil vapor.Strengthening the recovery and utilization of oil and gas can completely solve the safety hazard caused by oil and gas volatilization.Third,oil and gas recovery is conducive to energy conservation.The rapid growth of the economy and the rapid increase in car ownership have made China's oil energy supply increasingly tight.According to statistics,China’s crude oil imports have reached 100 million tons per year.In 2007,the country consumed 80 million tons of gasoline,and at least 350 million cubic meters of oil and gas were discharged during transportation,transfer and sales.More than 3 billion yuan.
2.Oil and gas recovery technology
2.1 Condensing oil and gas recovery technology
(1)Principle of condensing oil and gas recovery technology.
Gasoline is obtained by heating and distillation of crude oil.Usually,the initial boiling point is 40-60℃,and the final boiling point is 180-205℃.Therefore,it is possible for the oil vapor to return to the liquid state from the gaseous state as long as it is cooled below the initial boiling point.The test proves that for 42%oil and gas,the oil concentration is 29%at 5℃;the oil concentration is 20%at-15℃;the oil concentration is 15%at-20℃.Lower condensing temperatures are required for complete purification of oil and gas,but facility costs and operating energy consumption are increased several times,which is not economical.Combined with the use of adsorbents to adsorb oil and gas,manufacturing costs and operating costs can be greatly reduced.After the prototype and field test,the oil and gas emission concentration can be reduced to 1%to 4%.
The gasoline and oil gas inlet device is cooled by a collective assembled cold and heat exchange unit with a path of more than 120 meters to ensure that the temperature of the oil and gas flowing down from 40 to 500 L/min falls below-40℃,and more than 90%of the oil and gas condensate and liquefaction is separated and transformed.For gasoline,the oil and gas concentration drops below 10%.The remaining oil and gas enters the adsorption unit and flows through the adsorbent material from top to bottom,and the remaining 1%to 4%of the exhaust gas is discharged through the gas outlet pipe.The recovered gasoline enters the recovery container or the underground oil tank from the oil discharge pipe.
(2)Characteristics of condensing oil and gas recovery.
①Low temperature recovery gas does not need to be compressed,which is safer.
②Condensation and adsorption two treatment methods combined to form a"cold suction"oil and gas recovery and purification treatment device,both economic and environmental benefits.
③The operation is large,and it can operate in the range of 0~100%,especially suitable for intermittent loading.
④The whole device is cabinet type,covering an area of 2㎡,modular design and manufacture,and the whole is shipped to the user site,which is easy to install and easy to operate and maintain.
⑤It is only necessary to connect the air inlet of the device to the underground gasoline canister outlet of the gas station,and at the same time connect the return line of the recovered gasoline to operate.
⑥Adopt advanced technology design,automatic instrument control,import of key equipment,domestic matching,low cost.
⑦The device is designed and installed according to the safety and explosion protection specifications of the gas station,and the power consumption is not high,the maintenance is convenient,safe and reliable.
⑧The exterior of the device and the internal structure of the device are made of stainless steel,which is beautiful and has a service life of more than 10 years.
⑨Gasoline oil and gas recycling and utilization benefits are great.For example,a gas station that sells 20 tons of gasoline a day can recover equipment investment in just 2 years.
⑩It is a special treatment equipment for environmental protection,safety and fuel economy at gas stations.Reach the technical level of similar foreign products.
2.2 Adsorption method
The adsorption method utilizes the adsorbent to have different adsorption affinity for the hydrocarbon component in the oil and the air,and separates the hydrocarbon component from the air,thereby achieving the selection and recovery of the hydrocarbon component.The adsorption method usually uses activated carbon to adsorb and desorb oil molecules,thereby realizing the recovery and utilization of oil and gas.
In practical applications,due to the direct adsorption of oil and gas with a large concentration,the adsorbent material quickly saturates,which puts higher requirements on the life cycle of the adsorption equipment and the safety of the desorption process,so the application of the adsorption method is limited.limit.
2.3 Combination of condensation method and adsorption method
Generally,the second-stage condensation is used to condense the oil and gas to-40℃to 50℃.After the second-stage condensation,more than 85%of the oil and gas are liquefied,and the lower concentration of the non-condensed oil and liquid is passed through an adsorption system.Enrichment,the oil and gas concentration is greatly increased,and the volume is greatly reduced(the exhaust gas that has been separated by the adsorption system has been discharged),when the enriched oil and gas enters the third-stage condensation system for deep condensation,at this time,the third-stage condensation The power of the device is greatly reduced.
Advantages of this method:
(1)The advantages of the condensation method and the adsorption method are effectively combined.
(2)Since the oil and gas are enriched by the adsorption system,the oil and gas to be treated by the third-stage condensation is greatly reduced,and the energy consumption is also reduced.
(3)The oil and gas that has undergone secondary condensation is medium-low temperature oil and gas.The activated carbon bed does not generate high temperature hot spots,and the adsorption system also overcomes safety hazards.
2.4 Principle of membrane separation technology
At the gas station,the amount of oil and gas discharged from the car refueling and tanker unloading and the tank breathing process is also very large.The membrane separation method is characterized in that the special polymer membrane is preferentially permeable to hydrocarbons,so that the oil and gas mixture can be preferentially transmitted through the polymer membrane under the pressure of a certain pressure,and the air component is trapped.Emissions,enriched oil and gas are transported back to the tank or liquefied by other means.The advantages are advanced technology,relatively simple process,low emission concentration and high recovery rate.
The membrane separation method can be used as the exhaust gas discharge treatment device to remove the excess air pumped into the oil tank through the membrane recovery device to achieve the pressure balance of the oil tank,and also increase the gas-liquid volume ratio of the oil recovery pump.At 1.5,this will increase the system's oil and gas recovery rate to over 93%.
Gas stations are more distributed than oil depots,refineries and other places where oil is concentrated.The loading and unloading volume is also small and the site is limited.If the above process is adopted,it is more difficult to generate economic benefits.Gas station oil and gas recovery is a technology that benefits the country and the people,and is closely related to our daily lives.We must actively promote and develop oil and gas recovery technology,introduce advanced foreign technology and equipment,actively research and develop domestically produced advanced oil and gas recovery devices,strengthen the management of oil and gas recovery,and promote the rapid development of China's oil and gas recovery industry.
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