Reconstruction of gas valve for natural gas reciprocating compressor at wellhead

The customer is building a new LNG station in a county in Xinjiang, and their raw material gas compressor comes from a company in Southwest China. Overall, there is no problem with the compressor being large, except for the short service life of the gas valve. The three-stage gas valve is usually used for only one month. Due to the original compressor manufacturer's failure to improve the air valve, which seriously affected production, the customer has requested a modification of the air valve.

After technical communication, we have learned that the compressor medium is natural gas from the wellhead, containing 2% hydrogen sulfide but saturated water vapor. In terms of hydrogen sulfide content alone, a content of 2% is not high, but saturated water vapor causes severe corrosion of the compressor's gas valve. In addition, the design of each stage separator is relatively small, with poor separation capacity. The gas compressed in the third stage has the highest water content and is most severely corroded by hydrogen sulfide. Therefore, the service life of the third stage gas valve is significantly lower than that of the first and second stage gas valves

In response to the above situation, our company has redesigned all levels of air valves based on the original compressor design parameters and valve installation dimensions, and improved the materials and processes of each component, with a focus on enhancing sulfur resistance performance. The improved air valve, after more than a year of use, has a much better effect than the original machine air valve. The third level of corrosion is the most severe, and the service life of the air valve can reach three months. The user is very satisfied. In various LNG stations around the county, the compressor start-up status of this customer ranks first and the benefits are good

We are not satisfied with the current situation and will further improve the three-stage air valve. We will first trial produce a batch of three-stage air valve springs and send them to users. It has been almost a year, but we have not received any feedback on the effectiveness. Recently, engineers at the customer's site reported that the three-stage air valve with new springs has a lifespan of over 6000 hours, which is nearly three times longer than the first improved air valve! Request that in the future, other levels of air valves and springs be supplied according to the latest improved specifications

This case illustrates the importance of materials for the core components of a compressor. When dealing with certain difficult and complicated problems, there is no breakthrough in materials, and the product performance is difficult to improve