Corrosion resistance of compressors to hydrogen sulfide
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Will hydrogen sulfide present in the compressor feed gas cause corrosion to the compressor, and what is the allowable level of hydrogen sulfide for the compressor?
This requires setting conditions with the compressor manufacturer; 20,000 ppm should be no problem.
Generally speaking, it is meaningless to determine whether a compressor is resistant to H2S corrosion. The key lies in the material selection and sealing choices for the compressor during design and manufacturing, your process operating conditions (mainly pressure), and the concentration of H2S. For example, if machinery is made from materials resistant to hydrogen-induced cracking and sulfur stress corrosion, it will function fine within a certain range of H2S partial pressure levels; but once that concentration is exceeded, austenitic stainless steel must be used. But even with austenitic stainless steel, there is still an issue of a maximum partial pressure. The specifications for compressors are not very clear, but material selection can be based on Appendices G and H of API 610 for centrifugal pumps; it should be similar in that case.
The gas composition and operating conditions (pressure, temperature, flow rate, etc.) are provided to the compressor manufacturer, who will then select the appropriate materials and seals.
The allowable hydrogen sulfide level for compressors also depends on the material.
The compressor piston rod is prone to fracture due to hydrogen sulfide corrosion; generally, when the concentration exceeds 2000 ppm, it becomes necessary to consider upgrading the material. For piston rings and sealing rings with high hydrogen sulfide levels, it is necessary to consider upgrading them.
Is the same true for centrifugal compressors?