NGL Recovery Plant Technology: Ethane Recovery or Rejection for Changing Market Conditions

In the United States ethane has typically been recovered from natural gas due to its increased value as a petrochemical feed stock . The rapid increase in natural gas production from developing shale plays has resulted in a change from the norm. The increase in ethane supply is exceeding current demand, resulting in depressed ethane pricing; furthermore many of these new sources of natural gas are not well connected to the traditional ethane handling network resulting in high transport costs. In this new environment rejecting the ethane into the gas stream instead of recovering it will be a preferred option for some plants.  The rapid development of shale gas production has also led to extensive use of pre-engineered “standard cryo plants” which offer a shortened delivery time compared to a custom engineered plant. These “standard cryo plants” are typically designed to be as flexible as possible, but may not be optimum economic solution for each case. This paper will examine the typical requirements for ethane rejection, the typical performance of “standard cryo plants” and some of the alternate designs that maybe economically attractive for specific cases.