Why are reciprocating compressors generally used and screw compressors less so in torch recovery systems?
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For compressors used in torch recycling, are screw compressors better or reciprocating compressors? Why? The volume flow rate is 40 cubic meters per minute, with an outlet pressure of around 5 kilograms. The medium components include gas, H2S, etc.
I think that unless the pressure ratio is too high or the flow rate is too low, screw compressors should be given priority – not only because they are more reliable, but also because they are well-suited for handling various types of gases; they can work with dirty or moisture-containing gases as well
Generally, it depends on the cleanliness of the feed material; if it is gas from coking, a reciprocating type is preferable, while for other types, a screw type is better
This post was last edited by lovestory on 2012-3-10 at 11:52. Since flare gas contains a high level of dirt, with many solid particles or liquid droplets present, and reciprocating compressors require frequent maintenance, petrochemical companies such as CNPC and Sinopec now generally use screw compressors for their flare gas compression units.
Since flare gas contains a lot of dirt, with numerous solid particles or droplets present, many users opt for screw compressors to handle this gas. However, screw compressors encounter various problems in use. In recent years, thanks to the development of labyrinth compressors in China, many users have started using labyrinth compressors as a replacement for screw compressors.
Originally, reciprocating compressors were used, but now screw compressors are used in most cases.
We generally recommend using reciprocating compressors. This is because, in typical screw compressors with oil injection, the gas comes into contact with the oil. Firstly, impurities in the gas can contaminate the lubricating oil; Secondly, certain components present in the gas can react with the lubricating oil, causing its quality to deteriorate rapidly. Screw compressors have very high requirements regarding the quality of the oil used. Reciprocating compressors, on the other hand, can achieve non-contact between the lubricating oil and the gas, thereby preventing such situations from occurring; they are thus better suited to handle such operating conditions than screw machines.
The aforementioned discussions all focused on oil-injected screw compressors; in fact, process gas screw compressors are oil-free screw compressors, with the lubricating oil being separated by shaft seals and thus not coming into any contact with the process medium. Therefore, the dirtier the composition of the medium, the greater the advantage of process gas screw compressors. Currently, process gas screw compressors are being increasingly used in coke oven off-gas recovery projects due to their high reliability, long continuous operation time, small footprint, and the fact that they do not require backup units.
Reciprocating compressors require less investment and are relatively easy to maintain; however, where conditions permit, screw compressors are preferred. A filter can be installed in front of the compressor to remove impurities, and a gas-liquid separation tank can also be used.
Originally, reciprocating compressors were mostly used, but now screw compressors are predominantly used
Screw compressors have a long service life, are easy to maintain, and have few wear-prone parts; reciprocating compressors, on the other hand, require frequent repairs. The biggest advantage of screw compressors is their ability to transport multiple phases simultaneously; there are actually gaps between the rotor teeth, which allows them to withstand liquid impacts and to compress gases containing liquids or dust. Reciprocating compressors, on the other hand, do not have this capability.