Vent gas compressors fit in a category of positive displacement machines often used in low-cost petrochemical plants. As a general rule and compared with other available options, sliding vane compressors are selected for vent gas duty by user-purchasers whose emphasis is on low initial cost. If emphasis is placed on maintenance cost savings and long uninterrupted run length, screw compressors or even reciprocating machines are often preferred. Let’s consider here certain principles relating to experience checks and follow-up that carry over into asset selection in general, bearing in mind that reliability principles are universally applicable.
Emphasis Often Differs
Energy conservation is of ever-increasing importance to process plants of all sizes. Gas streams that were flared a decade ago are now often recompressed and recycled back to the suction vessel or sent to furnace heaters and other energy consumers. Depending on flow and compression ratio, a wide range of compressor configurations, both positive displacement and dynamic, could be considered. As a side comment, twin-screw “wet” rotary positive-displacement machines are in strong contention for many of these duties. Moreover, lobe-type machines are known to be suitable for many recompression duties.
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