Chapter 5: Dry Gas Seal Support Systems

Overview

Using dry gas seals in a centrifugal compressor requires a support system designed to supply sealing gas to the seal as the working fluid for the running gap. These gas seal support systems (sometimes referred to as gas seal "panels" because of their rack-mounted design) are normally supplied by the compressor manufacturer mounted on the compressor baseplate (fig. 5-1). The primary functions of the gas seal system are to

• Provide clean, dry seal gas to the dry gas seals

• Provide clean, dry separation gas to the barrier seals

• Monitor the health of the dry gas seals and barrier seals

Figure 5-1: Typical gas seal system

The gas seal system design recommendations, which are discussed in this chapter, are generally based on a beam-style compressor with tandem dry gas seals, as this is the most common configuration for process gas service. Where the requirements differ for double opposed gas seals or tandem seals with intermediate labyrinths, it is noted. Systems for single gas seals are not reviewed here because they are rarely applied in process gas centrifugal compressors. These system standards are typical and may not apply to all types of compressors and/or gas seal arrangements, but the basic design philosophies are applicable to most applications. The unique requirements for each application of dry gas seals should be evaluated on their own merits to assure the equipment is applied appropriately.