Case 5 LNG Parallel Expanders

In MESA Ine. s faeility in Satanta, Kansas, expander/eompressor paekages (Eigure 8-4) give the operators a eost savings in horsepower on both ends of the eonfiguration, and a mueh lower initial installation outlay. Without the expanders they would have had the additional 

The Satanta plant went online in September 1993, processing natural gas from some 1,000 wells drilled in the Hugoton fields of southern Kansas. A day s production yields 13,000 bbl of liquified natural gas (LNG), 5.1 million Nm (190 MMscf) of residue natural gas, and 21,600 Nm (800,000 scf) of helium. 

LNG—consisting of ethane, propane, butane, and natural gasoline (condensate)—arrives at the plant for upgrading before it is sent to petrochemical plants and refineries as feedstock. Residue gas is sold to the interstate and intrastate pipeline network. MESA, one of the world s major crude helium producers, also delivers helium to a pipeline operated by the U.S. Bureau of Mines. 

Natural gas from MESA s wells flows into a gathering system where pressure is increased to 7 bar (100 psig). Multiple booster stations raise it to 34 bar (500 psig) before gas enters the plant for separation. When gas enters the LNG recovery unit, its pressure must be raised again to 66 bar (950 psig). It is then subjected to a molecular sieve process for moisture removal. A series of heat exchangers lowers the temperature to -34°C (-30°E). 

Instead of using conventional refrigeration and condensers to convert incoming gas into LNG, the system was designed to feed 2,340 Nm / day (86,800 scfd) into each of two expanders. Both are connected in parallel, with compressors attached at the back end. The compressors are connected in series to boost a single stream of returning gas. 

---