(657d) Heavy Hydrocarbon Removal Using Adsorptive Separation Technology for LNG Liquefaction Facilities

The North American facilities of liquefied natural gas (LNG) producers use pipeline quality gas as feed, wherein most of the valuable natural gas liquids (NGLs) have been recovered, making the feed gas lean. However, the lean feed gas has trace amounts of C5+ heavy hydrocarbons (HHCs), which must be removed before the liquefaction process to prevent freezing and plugging in exchanger. For such compositions, the conventional pre-treatment options such as expansion, scrub columns etc. pose risks since the gas does not have enough heavies to create efficient reflux. This may result in reduced capacity, high economic lifecycle costs (ELC) and may require external NGL imports to the plant. The traditional methods are also prone to operational challenges due to fluctuations in feed gas composition.

For the greenfield facilities adsorption-based separation process can offer lifecycle cost advantage compared to conventional heavies removal unit (HRU). In addition to that, such technologies can also have debottlenecking issues related to lean gas which are observed in conventional HRU. One such technology present in Honeywell UOP’s portfolio is the temperature swing adsorption (TSA) based SeparSIV^TM technology. This technology enables removal of multiple impurities in the lean feed gas such as water and HHCs in a single adsorption system, resulting in simplified process design and cost savings.

This study presents Honeywell UOP’s SeparSIV^TM technology’s application in US baseload small-scale LNG plants. The case studies highlight SeparSIV^TM technology’s capability to successfully debottleneck the challenges faced by these facilities, such as heavies freezing in the coldbox, which result in financial loss and production disruption, while exceeding the adsorbent life expectations.