(386e) Ethane/Ethylene Liquefaction – Cutting Edge Processes to Take the Fuel to the World

Our world as it is today is still largely dependent on fossil fuels for power, transportation and production of consumer goods. Statistics are available that distinguish between commercial, industrial, power generation, residential and transportation sectors to track the consumption of energy forms available. The 6 major energy forms consumed these days are coal, petroleum, natural gas, nuclear, hydroelectric and other renewables. In the US, traditional fossil fuels like coal and petroleum have recently experienced a drastic decline in demand. This was mainly driven by advances in drilling technology and the corresponding increase in natural gas production. Horizontal drilling and fracking technology enabled producers to go after hydrocarbon reservoirs that were beyond reach previously. Shale plays such as Bakken, Eagle Ford, Haynesville and Marcellus, to name only the 4 largest, became targets of intense development for oil & gas production. Unleashed in 2005, natural gas derived from shale plays is projected to provide 50% of gas produced in the US by 2035.

The fact that these fossil fuel reservoirs are concentrated in certain areas of the world like the Middle East, Russia, Australia and North America poses a particular problem to the industry. Consumers are not always close to the source. Large consumers like Japan, South Korea and Western Europe have no way of producing the amount of fossil fuels they need to satisfy local demand. Accordingly, technologies and networks need to be developed to make the fuels available at the consumerâ??s doorstep. That was the case for crude oil in the past, the LNG infrastructure is currently coming on line. The overabundance of Ethane coincident with increasing shale gas production is challenging the industry now to rapidly develop means to bring the Ethane from the remote areas of production to the consumer.

The technology for the liquefaction of Natural Gas to LNG is well established and a large number of papers about the liquefaction processes applied have been published. The processes for liquefaction of Ethane or Ethylene have not been described in nearly as much detail as LNG liquefaction processes. This paper will focus on how LNG refrigerant cycles such as conventional, expander or mixed refrigerant can be adapted for the liquefaction of Ethane and Ethylene. A new process for the liquefaction of Ethane and Ethylene will be presented featuring significantly reduced power consumption and lower equipment count. Essential for this process is the optimal choice of refrigerant components and optimization depending on feed conditions. The process will be compared against other available processes with respect to power consumption and equipment size and, in addition, the paper will give guidelines for the selection of the optimal process design depending on the liquefaction plant capacity.