Introduction to oil and gas recovery methods
1 adsorption method
The adsorption of oil and gas/air mixture by using adsorbents such as activated carbon, silica gel or reactive fiber can realize the separation of oil and gas and air.
The oil and gas passes through an adsorbent such as activated carbon, and the oil and gas component is adsorbed on the surface of the adsorbent, and then subjected to vacuum desorption or steam desorption, and the enriched oil and gas is pumped to the oil tank by a vacuum pump or liquefied by other methods; and the adsorbent such as activated carbon The adsorption of air is very small, and the unadsorbed tail gas is discharged through the exhaust pipe.
2 absorption method
The separation of oil and gas and air is carried out according to the solubility of each component in the mixed oil and oil in the absorbent.
Generally, lean oil such as diesel is used as an absorbent. Generally, the oil and gas are countercurrently contacted with the absorbent sprayed from the top of the absorption tower. The absorbent selectively absorbs the hydrocarbon components, the unabsorbed gas is discharged through the flame arrester, and the absorbent enters the vacuum desorption tank to desorb and enrich the oil and gas. Then use oil to absorb.
3 condensation method
The refrigeration technology is used to replace the heat of oil and gas, and the direct conversion of oil and gas components from the gas phase to the liquid phase is realized. The condensation method is a method that utilizes the difference in vapor pressure of hydrocarbon materials at different temperatures, reduces the vapor pressure of some hydrocarbons in the oil and gas to a supersaturated state by cooling, and condenses the supersaturated steam into a liquid state to recover oil and gas.
Generally, the multi-stage continuous cooling method is adopted to reduce the temperature of the oil and gas, and it is agglomerated into liquid recovery. The minimum of the condensing device is determined according to the composition of the volatile gas, the required recovery rate, and the concentration limit of the organic compound in the exhaust gas finally discharged into the atmosphere. temperature. Generally, it is implemented by steps such as pre-cooling and mechanical cooling.
The pre-cooler is a single-stage cooling device. In order to reduce the energy consumption of the recovery device, a technology that uses the refrigeration amount reuse technology has been developed to reduce the temperature of the gas entering the recovery device from ambient temperature to about 4 ° C. Most of the water vapor in the gas condenses into water and is removed. The gas enters the pre-cooler and enters the shallow cooling stage. The gas temperature can be cooled to -30 ° C ~ -50 ° C, and as needed, nearly half of the hydrocarbons in the oil and gas can be recovered. Leaving the shallow cold oil and gas into the deep cooling stage, it can be cooled to -73 ° C to -110 ° C, set the temperature according to different requirements and configure the compressor.
4 direct combustion method
In this method, the hydrocarbon-containing gas generated during storage and transportation is directly oxidized and burned, and the carbon dioxide, water and air generated by the combustion are directly discharged as the purified gas after the treatment. This method is only used as a treatment measure to control oil and gas emissions. It cannot recover oil products and has no economic benefits.
5 membrane separation method
The special polymer membrane has the characteristics of preferential permeability to hydrocarbons, so that the oil and gas and air mixture can be preferentially transmitted through the polymer membrane under the pressure of a certain pressure, and the air components are trapped and discharged. The oil and gas is transported back to the tank or liquefied by other means.
Our company's oil and gas recovery technology introduction technology overview
The collected oil and gas is sent into the adsorption tank, and the oil has a pore-filling absorbent such as activated carbon or molecular sieve zeolite or silica gel, and the oil and gas are first stored to separate the air from the oil and gas and reach the standard discharge. After the amount of oil and gas adsorption reaches a certain level, the oil and gas components are removed. The technology has certain advantages in controlling the exhaust gas to reach the standard. However, the direct adsorption of high concentration oil and gas on activated carbon is easy to generate adsorption heat and increase unsafe factors. Therefore, it is necessary to set a suitable cooling device in the fixed bed in order to remove the adsorption heat in time.
The adsorption of oil and gas/air mixture by using adsorbents such as activated carbon, silica gel or molecular sieve can realize the separation of oil and gas and air.
The oil and gas passes through an adsorbent such as activated carbon, and the oil and gas component is adsorbed on the surface of the adsorbent, and the adsorption force of the adsorbent such as activated carbon on the air is very small, and the unadsorbed tail gas is discharged through the exhaust pipe. When the adsorption gradually becomes saturated and the air discharge gradually approaches the limit, the oil and gas improves the fixed bed operation of another activated carbon; the fixed bed with the saturated adsorption is decompressed and decomposed, and the enriched oil and gas is pumped to the oil and gas absorption tower by the dry vacuum pump. The lower portion is absorbed in reverse contact with the absorbent from the upper portion of the column; the absorbent is generally gasoline. The two fixed beds are alternately operated to achieve oil and gas recovery and air discharge.
Process flow diagram
Compared with the traditional adsorption method for oil and gas recovery, the technology provides a uniform heat extraction device inside the fixed bed of the adsorption tank, which not only ensures the safety of the adsorption process, but also facilitates the continuous stability of the adsorption process.
Application case and performance
The technology focuses on petrochemical storage tanks, oil companies' oil storage, refueling stations, and storage tanks in petrochemical production facilities.
It is reported that one ton of gasoline from the refinery to the gas station retail, at least will emit 7m3 oil and gas, its concentration is 1~3kg/m3. Processing capacity of 500 m3 / oil and gas recovery unit, about 3 million yuan investment, oil and gas recovery rate ≥ 95%, recovery unit volume of oil and gas consumption is 0.15kW.h, annual operation and maintenance fee match with 160,000 yuan, investment cost recovery period 3 year.
Development prospects and trends of oil and gas recovery technology
With the further implementation of the national environmental protection law and the in-depth implementation of the tasks of energy conservation, emission reduction and smog control, under the strict supervision of the government, relevant enterprises will start from their own actual conditions, choose small application investment, high recovery rate, operation and maintenance costs. Low-cost oil and gas recovery technology that can bring more economic benefits to enterprises. To this end, on the basis of the original methods, how to develop a new technology or an effective combination of several technologies that meet the needs of enterprises will become the focus of technology development of various environmental protection companies.