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Simplified Fractionation Cases for LNG Liquefaction

IP.com Disclosure Number: IPCOM000241298D
Publication Date: 2015-Apr-14
Document File: 6 page(s) / 128K

Publishing Venue

The IP.com Prior Art Database

Abstract

Liquid natural gas (LNG) plants often have a fractionation system that serves multiple purposes which may include (a) obtaining components for mixed refrigerant (MR) makeup; (b) removing heavy components to prevent freeze-out in the liquefaction unit; (c) removing heavy components to maintain the LNG product specification and/or facility fuel balances; and/or (d) making light petroleum gas (LPG) and/or natural gas liquid (NGL) products.

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Simplified Fractionation Cases for LNG Liquefaction

Liquid natural gas (LNG) plants often have a fractionation system that serves multiple purposes which may include (a) obtaining components for mixed refrigerant (MR) makeup; (b) removing heavy components to prevent freeze-out in the liquefaction unit; (c) removing heavy components to maintain the LNG product specification and/or facility fuel balances; and/or (d) making light petroleum gas (LPG) and/or natural gas liquid (NGL) products.

If there is no MR makeup and/or LPG/NGL product requirement, the fractionation system can be simplified.

Fig. 1A

Fig. 1 shows a configuration where there is no need to make NGL/LPG products. Natural gas feed (FD) is introduced to a scrub column (SC). SC bottoms product is fed to the stabilizer column (STB). It may or may not be cooled prior to introduction to STB. Partial condenser may use both and ambient heat sink (such as water or air) and below-ambient utility (such as propane: C3, or any suitable refrigerant such as used in a packaged chiller) to produce reflux. Vapor product containing ethane is re-injected into the liquefaction system. It may be further cooled by another stage of C3. The bottoms condensate product (CND) contains the heavy components.

Fig. 1B

Fig. 1B shows an optional configuration of the stabilizer column (STB). The partial condenser is cooled by the ambient heat sink. The vapor product is further cooled by below-ambient utility such as propane to produce below-ambient vapor and/or liquid products that can re-injected or pumped.

Fig. 2

Fig. 2 shows an option where the SC bottoms product is cold, for example when the SC is a stripp...