Let’s discuss what problems still remain unsolved with reciprocating machines
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Reciprocating compressors have many problems compared to speed-type compressors such as centrifugal compressors, which affect the further use of the units. Phenomena such as airflow pulsation or pressure fluctuations in the pipeline occur, and the main reason for this is that reciprocating compressors, being positive-displacement compressors, rely on changes in the volume of the cylinders to compress gas. In light of this, could improving the balancing pressure of the gas valves be considered as a solution? Another example: how to address the mutual interference in vibrations between various components of a reciprocating unit? Are there any good methods available at the moment that can be truly applied in practice? Let’s discuss the current problems existing in reciprocating machines, in order to provide some topics for scientific research and the expansion of applications for reciprocating compressors.
Here are my personal opinions: 1. The oil-free components currently widely used in reciprocating compressors (such as piston rings and support rings made of 4F material) have a very short lifespan (no more than one year at most), requiring shutdown for maintenance or replacement after a certain period of time. It has a significant impact on users. Are there any better materials? 2. For pipeline pulsation analysis, there are currently no particularly reliable and convenient methods; in many cases, it is done based on experience, which is not necessarily accurate. 3. Reciprocating compressors generally have low rotational speeds. If these speeds could be increased, the size and weight of the compressors could be reduced, which would lessen the space they occupy (land prices are quite high these days). Additionally, the associated components could also be made smaller, and there are many benefits in general. Currently, the technology used by domestic compressor manufacturers is mostly imported from abroad, with few investing in independent research and development efforts. . . Here, I support the original poster.
1. There are too many vulnerable components, and new materials for support rings and piston rings require further development and research. 2. The operating cycle is too short, requiring further research and development.
Reciprocating compressors currently lack any means of detection and analysis such as online condition monitoring
Reply to 4# Yanxibei Liu: It’s been around for a long time; you’re out of date. GE and Huada can both do it.
Sharing personal views: 1. Apart from its large size, reciprocating compressors have the advantage of inexpensive parts and low upfront investment； There are many disadvantages; the maintenance costs in the later stages are too high ； 2. There are too many vulnerable components, resulting in frequent maintenance, which directly affects the operation of the unit and production processes as well as the completion of production tasks ； 3. The noise generated by the units is high, having a significant impact on people and causing many difficulties in preventing occupational diseases ； 4. The unit experiences significant vibration; changes in the load at the connections of various equipment and pipelines can lead to intense vibrations, which may cause cracks in the welds and leaks of raw gas.
Reply to 6# xhx79: The labyrinth mechanism in reciprocating compressors does not have the characteristics mentioned above, haha
Compared to pure tetrafluoroethylene, the materials used for the piston rings and support rings in reciprocating compressors now contain certain elements that enhance their wear resistance; it is possible to specify these requirements regarding usage duration when placing orders with the manufacturer. The book \"Gas Flow Pulsation and Pipe Vibration in Piston Compressors\" written by Dang Xiqi provides some analysis methods for pipeline pulsation issues, though the calculations are quite complex. Additionally, software such as Fluent now offers simulation algorithms that can be utilized as a reference. Theoretically, the rotational speed of reciprocating compressors can be increased, but due to limitations such as the reciprocating impacts on components, temperature, materials, and the responsiveness of valves, further efforts are still needed to increase their speed. Nevertheless, this approach should provide a direction for the development of reciprocating compressors. Additionally, the vibration problem of reciprocating compressors has always been a significant issue affecting their operation. Due to the large number of components in such machines, it is not possible to achieve an optimal combination of the natural frequencies and their harmonics for each component; as a result, there are many different natural frequencies. This means that the compressor can encounter components whose frequencies are close to its own at any operating speed, leading to vibration. It is recommended that manufacturers, when designing reciprocating compressors, test or calculate the natural frequency of each component, and ensure that these frequencies are as far away as possible from the compressor’s own natural frequencies.
How are the diagnostic systems developed by GE and China University of Chemical Technology? I’ve heard of them before and have been in contact with China University of Chemical Technology; we haven’t adopted this system yet. If anyone is using it, could you share your experience – are there any issues? Do the two of them work on the same principle? Which one is better? The main approach involves installing a phase sensor on the flywheel, based on the unit’s operating cycle; using the unit’s angular velocity as the horizontal axis, changes in parameters such as vibration, pressure, and flow rate during the four stages of operation of the reciprocating compressor are used to monitor the unit’s condition. However, does it have strong analytical capabilities? Is it possible to determine what fault exists when certain conditions occur? In many cases, it is still necessary to rely on on-site observations for judgment.
The main areas that need to be studied are ensuring the long-term operation of the gas valves, addressing issues such as broken valve plates and springs, as well as environmental protection concerns; nitrogen-hydrogen compressors definitely cannot operate without oil lubrication
It is mainly because the domestic materials are of poor quality, which results in high repair costs for the compressors. The spare parts of the Polish and Danish units we use basically do not break.