The most important thing when selecting an oil and gas recovery device is to avoid making decisions based on guesswork: overestimating the gas volume can lead to doubled investment, underestimating it can result in long-term overload of the device, reporting a high concentration can deviate from the plan, and reporting a low concentration can lead to substandard recovery rates. The capacity design of the membrane separation device, membrane area, and stage configuration are all based on actual measured data. A round of on-site measurement may not take much effort, but it can avoid major rework later on, especially for renovation projects. The operating data of old devices themselves are valuable references. This article lists three sets of data, measurement methods, and purposes to be measured before selecting a model, which should be followed before making a plan.
Which sets of numbers should be measured
Three sets of data determine the plan: first, gas volume, which determines the processing capacity and pipe diameter of the device; second, concentration, which determines the process route and membrane area; third, operating conditions, including temperature, humidity, pressure fluctuation range, and on-site conditions of the discharge outlet. These three sets of data are interrelated - gas volume fluctuates with the rhythm of oil receiving and dispatching, concentration changes with seasons and tank liquid levels, and single-point data is prone to distortion. Each parameter should cover at least high, medium, and low operating conditions, and each measurement should be taken multiple times before obtaining the final data.
How to measure air volume
If the emission outlet is a centralized exhaust pipe, use a pitot tube or thermal flowmeter to measure the flow rate and convert it to gas volume. It is important to select the measuring point in a straight pipe section, avoiding disturbances from elbows and reducers. If the emission is through a breather valve, the gas volume changes dramatically with the oil loading and unloading operations. A reliable method is to follow a complete operation cycle and record two sets of data: peak values and average values. The design should be verified based on peak values and calculated for economy based on average values. Only by obtaining both sets of data can the device be cost-effective and effective.
How to measure concentration
The concentration is measured using a handheld hydrocarbon detector at the emission outlet, and recorded separately according to the operation stage. If conditions permit, gas samples are taken and sent to the laboratory for component analysis. The proportion of light components in gasoline vapor directly affects the configuration of membrane area and condensation temperature level. The concentration data should also be viewed in conjunction with the recovery target: the gap between the emission limit and the recovery rate target represents the work that the device needs to do. The larger the gap, the more attention should be paid to the configuration of membrane area and stage number.
The measurement itself also has several potential pitfalls: the measuring point must be fixed at the straight pipe section, as any change in position will render the data incomparable; the detector should be calibrated before use, and the expiration date of the calibration gas should be checked carefully; when recording, the operating conditions should be fully documented - whether it was during oil receiving or oil dispatching, what was the liquid level in the storage tank, and what was the ambient temperature. Without these operating conditions, the numbers lose their interpretative value. These rules may seem trivial, but they are the dividing line between usable and unusable data.
Actual measurement list
| data item | Measurement method | Where to use it in the scheme |
|---|---|---|
| Peak air volume | Record of homework cycle | Device capability verification |
| Mean air volume | Long-period statistics of flowmeter | Economic scale accounting |
| Concentration level | Segmented recording by the detector | Process route and stage number |
| component proportion | Take samples and send them to the laboratory | Membrane area and temperature level |
| temperature and humidity | Field instrument records | Preprocessing configuration |
| interface location | On-site investigation and archiving | Layout and piping design |
How to integrate data into the plan
- The peak gas volume determines the device capacity, while the average gas volume determines the economic scale. Both are combined to form a solution;
- Component analysis determines the condensation temperature range and the material selection direction for the membrane separation layer;
- Preprocessing configuration for temperature and humidity data is set, and the dehumidification section cannot be omitted in high humidity areas;
- The emission limit and recovery rate targets are set as acceptance indicators and included in the contract;
- On-site photos, pipe diameters, and joint locations are archived along with the data, eliminating the need for a second site visit for layout drawings.
Frequently Asked Questions
Should we conduct the test ourselves or ask the manufacturer to do it?
For sites with instruments and personnel, they can conduct a preliminary measurement round themselves and obtain initial data, which will be reviewed during the manufacturer's inspection. For sites without such conditions, the manufacturer should be directly invited to conduct on-site measurements. The plan will be determined after the data from both parties aligns, which is more reliable than relying on data from a single party.
Should measurements be taken in both winter and summer?
It is recommended to conduct at least one round of testing in each of two different seasons. Temperature has a significant impact on condensation load and membrane inlet conditions, and fluctuations in concentration and gas volume also exhibit seasonality. Data from two seasons can greatly enhance the adaptability of the plan.
Who will use the data after it is measured?
The three aspects of scheme design, investment estimation, and acceptance indicators are all utilized: design is based on data to determine configuration, estimation is based on capacity to determine investment, and acceptance includes limit values and recovery rate targets in the contract, with all three parties being responsible for the same set of data.
This article is compiled by Luoyang Wohong Petrochemical Equipment Co., Ltd. The company provides design and manufacturing, skid-mounted customization, installation and commissioning, as well as after-sales operation and maintenance services for three-time oil and gas recovery equipment to gas stations and oil depots. If you need on-site inspection or scheme configuration, please feel free to contact us for discussion.