Ameen argues that “expanders are used to expand various gases efficiently from high to low pressures to obtain refrigeration” (Ameen 2006 p. 142). Jumonville asserts that in spite of variations in specific processes, “almost all turboexpanders are used to remove energy from a gas stream, thereby producing power and cooling the gas” (Jumonville 2010 p. 1
48). In the process of expanding high pressure gas across the turbine, the extraction of most of the gas’s energy potential occurs (Gopalakrishnan & Hardeveld n.d. Mokhatab & Poe 2012). The energy extracted is then transmitted to the shaft and the compressor (Bloch 2006). Consequently, an enormous reduction of pressure in the gas occurs. This consequential fall in pressure together with efficient energy extraction creates refrigeration, which is essential for cryogenic processing of gas (Sapali 2009). Therefore, the use of expanders in a cryogenic plant is to expand high pressure gas thereby leading to temperature fall. This decline in temperature results into refrigeration, which is essential for liquefaction of gases in a cryogenic plant (Finley 2013. Mokhatab & Poe 2012). Jumonville (2010) argues that “in most applications, the turboexpander normally runs faster and operates with colder temperatures than any other equipment in the plant” (Jumonville 2010 p.147). The turbine Expanders converts the cryogenic fluid stream hydraulic energy into electric energy (Habets & Kimmel 1999).
The expander used in a cryogenic plant is usually associated with numerous benefits. The use expanders in cryogenic plants ensures optimum efficiency, reduces operation cost and also offer reliable and strength augmentation (Kerry 2010). The cryogenic turbine expanders’ efficiency (thermodynamic efficiency) can be observed by obtaining the difference in enthalpy at the inlet and the exit.