MATERIALS SELECTION AND DEVELOPMENT FOR CENTRIFUGAL COMPRESSORS OPERATING IN EXTREME SOUR ACID GAS SERVICE

摘要

The rising demand for oil and gas has led us to exploit oil fields and gas reservoirs with increasing amounts of contaminants. Reserves of natural gas are abundant, but about 40% of the fields contain high concentrations of hydrogen sulfide, carbon dioxide, and chlorides. The harshening environment represents a challenge for the suitability of common classes of materials used for design and manufacturing of centrifugal compressor components. According to NACE MR0175/ISO15156, a fit-for-purpose approach has been extensively used to prove the steel's resistance in simulated field conditions and characterize the environmental limits of most martensitic and precipitation hardening stainless steels in terms of partial pressure of carbon dioxide, hydrogen sulfide, and chlorides. The literature available on the subject generally agrees that the contaminants' concentration levels exceed the possibility of risk presented by stainless steels to turbo-machine reliability, and in worst cases to operators' safety. Nickel-based alloys are the most robust solution to overcome the above limitations, guaranteeing high mechanical strength and resistance against stress corrosion cracking mechanisms in expected compressors' environments. This paper describes the advance in nickel-based alloys' application and production of centrifugal compressors (CC) for extreme sour and acid conditions, with work that reveals the development of alternative manufacturing routes for rotor and stator components in turbomachinery. A detailed explanation of nickel-based alloys' metallurgy, application and manufacturing capability is also given, along with recent developments of new alloys to bridge the gap between iron-base and nickel-base alloys, providing cost effective materials with enhanced corrosion resistance.