Managing Waxes and Paraffins
Filtration and Separation Basics by JCI
Separating hydrocarbon liquids from natural gas is common in many compressor stations and processing facilities. The type of filtration and separation equipment used for a given application depends on several factors. A few of these factors include the downstream equipment, liquid particle distribution, gas/liquid ratio, flow regime, and desired efficiency.
Standard separators, scrubbers, and filter designs found in these facilities rely on the interception and impaction separation mechanisms to capture and remove liquid particles from a natural gas stream. Consider a Horizontal Inlet Separator or Slug Catcher that is designed to separate natural gas and liquid at the inlet of a gas plant. Hydrocarbon liquid mist is removed using a mesh pad or vane pack mounted near the gas outlet nozzle. Refer to Figure 1 which depicts a standard horizontal separator configuration.
These standard designs are sufficient for many applications, resulting in reliable, efficient separation. However, many liquid-rich natural gas streams contain a wide spectrum of hydrocarbon components. Heavier hydrocarbon components (i.e. waxy hydrocarbon components or paraffin) tend to stick to the separation and filtration media. The wax or paraffin builds up over time, resulting in the need to prematurely repair or replace the separation device or filter element, and worse yet, resulting in lost production from an unplanned shutdown. Refer to the photos in Figures 2a, 2b, 2c, and 2d showing some examples of fouled separation devices and filter media.
Figure 1 - Typical configuration of an inlet separator or slug catcher.
Figure 2a – Damaged mesh pad.
Figure 2b - Plugged mesh pad.
Figure 2c - Plugged vane pack.
Figure 2d - Plugged filter cartridge.
It is not always known in advance that waxes or paraffins will be prevalent. The owner can only rely on their operating experience in a specific formation or with nearby facilities. However, if known in advance or if discovered after a facility has been commissioned and in operation, there are designs that can be employed that manage these waxy hydrocarbon liquids and paraffins, resulting in reliable, low maintenance operation, maximizing production and minimizing operational costs.