If you notice a decline in recovery rate during operation, don't rush to draw conclusions. Recovery rate is a result of the entire chain from collection to discharge. Any issues in the collection port leakage, increased pipeline resistance, condensation temperature deviation, or impeded liquid discharge will ultimately be reflected in this figure. A more effective approach is to investigate segment by segment: first confirm the reliability of the data itself, and then narrow down the scope section by section.
First, let's clarify the data caliber
Before conducting an investigation, it is essential to confirm that the "decrease" is genuine. Factors such as whether the measurement method has changed, whether the statistical periods are comparable, and whether the feed load is significantly different can make the numbers appear to have decreased without any actual deterioration in the system. By comparing recent data with historical data from the same period under similar loads and eliminating discrepancies in calculation methods, we can determine the extent and onset of the decrease, providing a clear starting point for the investigation.
The starting time is of great value. Whether the decline is gradual or sudden corresponds to different reasons: gradual decline is often related to slow changes in component performance, such as scaling on the heat exchange surface or wear of seals; sudden decline is often associated with a specific event, such as after maintenance, a sudden change in weather, or after an abnormal operating condition.
The idea of investigating by segmenting according to different links
Break down the system into four sections: collection, conveyance, condensation, and drainage, and confirm each section from front to back. For each section, answer two questions: Has there been any change in the parameters compared to normal operation? Is the state at the junction between this section and the next section normal? After going through each section, the scope will naturally narrow down to specific parts.
Six steps of investigation
- Check the measurement and statistical standards to confirm that the decrease is due to real changes in working conditions rather than changes in recording methods;
- Check the sealing status of the collection end: the return port of the fuel nozzle, the unloading interface, and the tank accessories;
- Inspect the conveying pipeline: check the valve opening along the way and inspect the pipeline for signs of fluid accumulation and blockage;
- Check the temperature level and temperature difference performance of the condensation section, and compare them with the normal operation records;
- Inspect the liquid drainage and collection processes: check the liquid level, frequency of drainage, and whether the quality of the recovered liquid is abnormal;
- Summarize and compare the inspection results of each section, identify the abnormal section, and then further pinpoint the specific location.
Common reasons in the collection and transportation links
The most common issue at the collection end is seal failure. Aging of the seal ring at the return port, wear of the quick connector, and loosening of the tank accessories can all allow oil and gas to escape before entering the pipeline. Although the device itself operates normally, the amount collected decreases. Most of the problems in this area can be detected through visual inspection and simple leak testing, which also has the lowest troubleshooting cost. It is recommended to address these issues first.
A typical issue in the conveying process is increased resistance. Liquid accumulation at low points in the pipeline, misoperation of valves resulting in changes in their opening, and obstruction of foreign matter at elbows can all impede gas phase flow, leading to a decrease in the collection efficiency of the preceding section. During inspection, focus on the state of valves and low points in the pipeline, especially those that have been recently tampered with.
Common causes of condensation and drainage issues
The gradual change in performance of the condensation section is often related to the state of the heat exchange surface. When the heat exchange surface becomes dirty or fouled, the temperature level achieved for the same refrigeration output will deviate, and the recovery degree of condensable components will decrease accordingly. Such issues manifest gradually, and comparing the temperature difference with normal operating records is the easiest way to identify them.
Poor drainage is another common cause. When the liquid level in the collection tank is too high and the drainage valve malfunctions, the condensed liquid cannot be drained out, and when it accumulates to a certain extent, it will adversely affect the condensation effect. Checking the liquid level and drainage action can usually confirm the issue quickly.
| link | Common reasons | inspection method |
|---|---|---|
| Collection terminal | Aging of sealing rings, wear of joints, and loosening of accessories | Conduct a visual inspection for leakage, with a focus on the air return port and connections |
| Conveying pipeline | Low-point fluid accumulation, incorrect valve opening, and foreign object obstruction | Check the valve status and inspect the low points in the pipeline |
| Condensation section | Dirty and scaled heat exchange surface, temperature deviation | Compare the temperature difference performance with the normal operation records |
| Drainage process | The liquid level is too high, and the action of the drainage valve is abnormal | Check the liquid level and discharge action |
| Measurement link | Changes in caliber and incomparability of statistical periods | Compare with similar loads and historical data from the same period |
| environmental conditions | Sudden changes in temperature affect operating conditions | Comprehensive judgment based on seasonal conditions during the same period |
Handling and recording after investigation
After identifying the specific causes, the handling can be divided into two categories: those that can be handled on-site should be dealt with immediately and subsequent data observed, such as re-fastening connectors and cleaning low-point fluid accumulation; those that require downtime or component replacement should be included in the maintenance plan and the time for review should be specified. Regardless of the category, it is recommended to record the troubleshooting process and results in the operation log: where to start the investigation, what was discovered, how it was handled, and the data recovery status after handling. After several accumulations, the parts of the equipment that are most prone to problems will become clear, and the next time troubleshooting can start directly from the high-risk areas, significantly improving efficiency.
Frequently Asked Questions
Is the decline in recovery rate necessarily due to equipment issues?
Not necessarily. Changes in measurement calibers, different feed loads, and differences in environmental conditions can all cause variations in numbers. Confirming the comparability of data before conducting equipment troubleshooting can prevent normal fluctuations from being mistakenly treated as malfunctions.
Which paragraph should we start with for troubleshooting?
It is recommended to start with confirming the data caliber, and then investigate from the collection end to the condensation end section by section. Most issues at the collection end can be detected through visual inspection and leak testing. Investigating this section first is the least costly and fastest way to eliminate a wide range of possibilities.
How can I confirm the restoration after processing is completed?
After processing, continuously observe the operational data for a period of time and compare it with the normal range before the decline. If the data rebounds, it indicates that the cause has been correctly identified; if it remains low, it suggests that there are still undiscovered issues, and continue to investigate further using a segmented approach.
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.