The tertiary oil and gas recovery equipment is a complete set of devices used in storage and transportation links such as gas stations and oil depots to recondense and recover the oil and gas emitted from storage tanks. Based on the primary and secondary oil and gas recovery (closed recovery during oil unloading and refueling), it utilizes a combination of compression condensation and membrane separation processes to re-liquefy the oil and gas generated during storage into gasoline for recovery. This not only reduces consumption but also ensures emissions meet standards. It is currently one of the core devices in the compliant renovation of gas stations.
1. Which stage of oil and gas recovery is involved in the third recovery process
The generation of oil and gas at gas stations occurs throughout the entire storage and transportation process, and the recovery process is divided into three stages: primary recovery addresses the replacement of oil and gas between tank trucks and underground storage tanks during unloading; secondary recovery addresses the collection of oil and gas from vehicle fuel tanks during refueling; and tertiary recovery targets the oil and gas emitted from underground storage tanks during daily "large breathing" and "small breathing". The first two stages involve transfer, while the third stage is the actual reduction. Therefore, the performance of tertiary oil and gas recovery equipment directly determines the emission level of the entire station.
II. Composition and structure of the equipment
A typical set of tertiary oil and gas recovery equipment consists of oil and gas collection pipelines, compressor units, multi-stage condensation units, separation membrane components, control systems, and safety accessories. The oil and gas emitted from storage tanks first enter the condensation units for step-by-step cooling and liquefaction. The uncondensed low-concentration tail gas then enters the membrane separation components for further enrichment and recovery, and finally meets emission standards before being discharged.
III. Why combine condensation and membrane separation
Each single process has its own shortcomings: relying solely on condensation leads to a significant increase in energy consumption in the low-concentration range; relying solely on membrane separation imposes a heavy burden in the high-concentration range. Combining them allows for the best of each. Common process route comparisons are as follows:
| Process Route | Characteristics | Applicable scenarios |
|---|---|---|
| Single condensation | The structure is simple, and there is a noticeable increase in energy consumption at low concentration ranges | Venues with general emission requirements |
| Single membrane separation | It covers a small area, but the burden on the high-concentration section is relatively heavy | Auxiliary processing link |
| Condensation + membrane separation combination | Condensation and liquefaction in the high-concentration segment, and membrane enrichment in the low-concentration segment, resulting in a more balanced overall energy consumption and emissions | Gas stations, oil depots, and other places with high compliance requirements |
IV. What should be considered when selecting a model
When purchasing oil and gas recovery equipment for three times, it is recommended to follow four steps: first, sort out the tank scale and refueling volume of the station, and clarify the processing load range; second, confirm the emission implementation standards and local regulatory requirements; third, compare and select process routes, focusing on the energy consumption performance and maintenance convenience of combined processes; fourth, verify the manufacturer's on-site survey, installation and commissioning, and after-sales response capabilities. Before the equipment enters the site, ask the manufacturer to provide a plan and layout diagram specific to the station, which is more reliable than just looking at the parameter table.
Frequently Asked Questions
Q: Should the oil and gas recovery equipment be kept running all the time?
Answer: The equipment is usually started and stopped in conjunction with the tank pressure, and it automatically operates when the breathing emissions meet the set conditions, without the need for manual attendance.
Q: Can an old station be retrofitted?
Answer: Yes, it can. Skid-mounted equipment occupies a small area and requires limited pipeline modification, so most technical upgrades for old stations can be arranged. A site survey before mobilization is sufficient.
Question: Where does the recycled oil go?
Answer: The liquefied gasoline is returned to the storage tank, which is considered as resource recovery and reuse, and the loss is directly deducted.
This article is compiled by Luoyang Wohong Petrochemical Equipment Co., Ltd. If you need advice on scheme design and equipment selection for this site, please feel free to contact us.