A Supercritical CO2 Combined Power and Liquefaction Cycle

Natural gas production has increased dramatically in recent years due to advances in horizontal drilling and hydraulic fracturing techniques. There are still challenges that must be addressed by industry to better utilize these abundant natural gas resources. For example, due to the cost and complexity with piping installations from remote well sites to processing facilities (should they exist), natural gas is often flared at the site whereas the liquid hydrocarbons are stored in holding tanks. For the natural gas that is recovered and processed, there are currently economic benefits to exporting the gas to international markets, provided that the gas can be liquefied and shipped. While the number of liquefaction facilities has increased in recent years, additional liquefaction plants are needed. This paper introduces a novel liquefaction cycle that utilizes a supercritical carbon dioxide (sCO2) power cycle to provide power and initial stages of refrigeration to a natural gas liquefaction cycle. The liquefaction cycle uses a flow of CO2 extracted from the power cycle as well as natural gas to provide several stages of refrigeration capable of liquefying the process stream. The combined sCO2 power and liquefaction cycle is described in detail and initial cycle analyses are presented. The cycle performance is compared to small-scale natural gas liquefaction cycles and is shown to provide comparable performance to the reviewed cycles. Due to the compact nature of the sCO2 power cycle equipment, the sCO2 liquefaction cycle described herein can provide small, modular liquefaction plants that can be employed at individual well sites to liquefy and store the natural gas as opposed to flaring the gas.