1. Consider the associated gas flow rate
Small flow rate (several cubic meters/hour, several hundred cubic meters/hour): If the associated gas flow rate is small, such as in the recovery of associated gas from some small oil wells, reciprocating compressors are a more suitable choice. Although its flow rate is relatively small, it can effectively process this small flow of gas and compress it to the required pressure.
Medium flow situation (tens of cubic meters/hour, thousands of cubic meters/hour): For associated gas with medium flow, screw compressors are a good option. Its flow characteristics are relatively stable and can work well within this flow range, meeting the needs of associated gas recovery.
High flow conditions (several thousand cubic meters/hour, several hundred thousand cubic meters/hour): When the associated gas flow rate is large, such as in large oil and gas fields or natural gas processing plants, centrifugal compressors are the preferred choice. It can efficiently handle large-scale associated gas and ensure the smooth progress of the recycling process.
2. Based on the required pressure range
Low pressure and medium pressure range (discharge pressure less than 10MPa): If the required pressure after associated gas recovery is in the low to medium pressure range, centrifugal compressors or screw compressors can meet the requirements. Centrifugal compressors are suitable for processing high flow low-pressure and medium pressure associated gas; Screw compressors are more suitable for situations where the flow rate is moderate and the pressure ratio is not particularly high.
Medium pressure and high pressure range (discharge pressure greater than 10MPa): For situations where associated gas needs to be compressed to medium pressure and high pressure, such as long-distance transportation or special high-pressure processes, reciprocating compressors are more suitable. It can generate a high compression ratio and compress the associated gas to a higher pressure.
3. Combining efficiency and operating costs
In terms of efficiency:
If the associated gas recovery system operates under stable conditions for most of the time, both centrifugal compressors and screw compressors can provide high efficiency under their design conditions. Centrifugal compressors have significant efficiency advantages under high flow and medium low pressure conditions; Screw compressors have relatively stable efficiency over a wide range of operating conditions. The isentropic efficiency of reciprocating compressors can reach 70% to 90% under appropriate operating conditions, but it is greatly affected by changes in operating conditions.
For associated gas recovery scenarios with frequent changes in operating conditions, screw compressors may have more advantages because they can maintain relatively stable efficiency over a wide range of operating conditions, while centrifugal compressors may experience a significant decrease in efficiency when deviating from design operating conditions.
In terms of operating costs:
Due to its complex structure and numerous moving parts, reciprocating compressors have high maintenance costs, including regular replacement of piston rings, air valves, and other components. Additionally, their vibration and noise may require additional protective measures, which can also increase costs.
Centrifugal compressors have a simple structure and operate smoothly. Daily maintenance mainly involves cleaning the impeller and maintaining the bearings, which is relatively low-cost. However, if key components such as the impeller are damaged, the repair cost is relatively high.
The maintenance cost of screw compressors is between that of reciprocating and centrifugal compressors, mainly including rotor inspection, seal replacement, etc. At the same time, its operational stability helps to reduce long-term operating costs.
4. Consider intake quality and pre-treatment requirements
In the case of good intake quality: If the associated gas has undergone good pre-treatment and has low impurity content, centrifugal compressors, screw compressors, and reciprocating compressors can all be used normally. However, centrifugal compressors can better leverage their high efficiency advantages in this situation.
Poor intake quality: When the associated gas contains a large amount of impurities, reciprocating compressors and screw compressors have a certain tolerance. A reciprocating compressor can be treated by installing a simple filter at the inlet; Although screw compressors have a certain tolerance to impurities, excessive impurities can still affect their performance. Centrifugal compressors require high intake quality and require efficient pre-treatment equipment such as filters and separators to ensure pure intake, which increases equipment investment and operating costs.
5. Consider the site and installation conditions
In the case of limited space on the site: Screw compressors have a compact structure and small volume, which gives them advantages in situations where the site space is limited. Due to its complex structure, reciprocating compressors require a certain amount of space to arrange components such as pistons and connecting rods, while centrifugal compressors, although relatively simple in structure, also have larger equipment volumes for large flow processing.
In situations where high installation convenience is required: screw compressors are easy to install and have relatively low requirements for the foundation. When installing reciprocating compressors, it is necessary to consider the balance of piston motion and the impact on foundation vibration; During the installation process of a centrifugal compressor, it is necessary to ensure the precise installation of the impeller and the alignment of the shaft, which requires high installation technology and foundation.
It is difficult to definitively say which compressor is more commonly used in associated gas recovery, as it depends on multiple factors. However, centrifugal compressors and reciprocating compressors are widely used in practical applications.
1. Centrifugal compressor
Widely applicable scenarios: Centrifugal compressors are crucial equipment in large-scale oil and gas field extraction and natural gas processing plants. This is because the associated gas production in large oil and gas fields is enormous, with flow rates typically ranging from several thousand cubic meters per hour to several hundred thousand cubic meters per hour. For example, in some large offshore oil and gas platforms in the Middle East, the daily production of associated gas can reach millions of cubic meters. The use of centrifugal compressors can efficiently process these large amounts of associated gas to meet the needs of industrial production.
In line with the trend of industrial development: With the large-scale and centralized development of the oil and gas industry, the demand for high flow and efficient processing equipment continues to increase. The structural characteristics of centrifugal compressors enable them to adapt well to this trend. They can maintain relatively stable performance at high flow rates and continuously improve their technology, such as adopting efficient impeller design and advanced sealing technology, further enhancing their applicability in large-scale associated gas recovery.
Good operational stability: It runs smoothly with relatively low vibration and noise, which is very important for industrial applications that require long-term stable operation. In the continuous production of natural gas processing flow, reducing equipment failures and maintenance frequency can significantly improve production efficiency and reduce production costs.
2. Reciprocating compressor
High pressure applications are indispensable: In scenarios where it is necessary to compress associated gas to a medium pressure and high pressure range (discharge pressure greater than 10MPa), reciprocating compressors play a crucial role. For example, in some cases where associated gas is compressed and injected into underground gas storage or transported through long-distance pipelines, higher pressure is required, and reciprocating compressors can meet this high-pressure demand.
Mature and reliable technology: The development history of reciprocating compressors is long and the technology is mature. Many small oil wells are still widely used in situations where equipment reliability is high and technology updates are relatively slow. Its working principle is simple and easy to understand, and with operators and maintenance personnel familiar with the equipment performance, it can effectively carry out associated gas recovery work.
