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Centrifugal Compressor in Gas Liquefaction Train

Centrifugal Compressor in Gas Liquefaction Train

Image of Vanessa LNG-1

General Process Information

Centrifugal compressors are main components of the gas liquefaction train. These are typically a multi-stage compression of refrigerants necessary to ensure that natural gas reaches its liquid state for storage and transport. The entire refrigeration cycle, in short, relies on robust compressors to ensure uninterrupted LNG production.

Image of Vanessa LNG-2

Surge Protection

Application: Hot gas bypass valves perform a major protection function by remaining usually closed until a signal to discharge pressure is produced. Such signal prompts the opening of the valve in order to recirculate the flow from the intermediate compressor to the compressor suction and avoid surging with potential mechanical failures.

Challenges: Centrifugal compressors in LNG liquefaction trains are used to pressurize the refrigerant gas mix which must avoid pollutant and dangerous emission of VOC. This represents an important challenge for several manufacturers, and fugitive emission testing for valves has become an important component for the choice of the most appropriate product. For example, Emerson has been awarded an order from a leading Oil & Gas end user for class 600, NPS 20 and NPS 24 Series 30,000 valves to be used for a hot gas bypass application in a gas liquefaction train (LNG) centrifugal compressor. Vanessa valves were chosen after close scrutiny by the OEM, the EPC contractor and ultimately by the end user instead of the originally specified globe valves. Vanessa valves, well-known for tight shutoff performance, largely exceeded the originally specified leakage class for globe valves. Furthermore, Emerson Vanessa's triple offset valve credentials in the reduction of fugitive emissions, acknowledged by the fulfillment of international standards and its ability to perform in-house testing, proved to be extremely valuable assets that can bring satisfaction to any customer.

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