(181a) Development of Adsorption-Based Process for Heavy Hydrocarbon Removal from Lean Natural Gas

To prevent freezing of the heavies in LNG (Liquefied Natural Gas) production, one of the requirements in the pretreatment step is the removal of heavy hydrocarbons (C6+). Traditionally, this is done using a distillation approach by a scrub column. If the gas is rich, NGL (Natural Gas Liquid) can also be produced from the bottom of the scrub column. However, when the gas becomes lean in C2 or C3+, the scrub column can easily dry out due to insufficient liquid reflux. The possible solution for providing the needed cold liquid is either from the downstream cold box or/and feed gas expansion. Both options are very energy inefficient for the scrub column operation when it comes to the lean gas.

UOP has developed an alternative solution for the heavy hydrocarbon removal from the lean natural gas, called SeparSIV.  The adsorption-based process is built on commercially proven technology for water and heavy hydrocarbons removal to meet pipeline gas specifications. To further meet the more stringent specification for LNG, UOP’s SeparSIV adsorption system uses a mix of adsorbents capable of removing C6+ and BTEX to 1 ppm level from lean gas.  This system operates at a high pressure with a low pressure drop and does not require gas expansion and recompression commonly found in an NGL extraction unit. The adsorption system is also very selective for the heavy hydrocarbons without removing lighter ones. Other benefits of this new process will be discussed in this presentation.