In case of well-head gas, the process starts with the pre-treatment of the raw gas to bring in to the optimal quality for the liquefaction process. Depending on the gas composition, this may include removal of heavy pollutants such as VOC, ammonia, chlorides as well as the bulk of hydrogen sulfide. The modular pre-treatment plants are assembled to address the specific characteristics and volumes of gas handled, and may comprise of scrubbers, carbon beds or other solutions, all of which will be mobile and skid-mounted.
As a stand-alone operation, the pre-treatment step helps oil and gas producers create self- sustaining operations by optimizing raw natural gas for maximum electricity generation efficiency on site.
As a next step, gas polishing unit allows to refine the purity of methane to make it conform to the liquefaction specifications: in order to avoid the formation of dry ice and the onset of corrosion phenomena, the concentrations of carbon dioxide and moisture content they must be in the range of 50 and 1 ppm respectively.
The process of gas treatment and polishing results in meaningful amounts of Boil Off Gas (BOG), which in some practices is vented into the atmosphere. OneLng redirects this gas to the genset that power the entire processes at the site. In case of excess power generation, excess can be sold to the grid and offered to auxiliary services such as crypto currency mining.
In areas that are rich in gas with high content of valuable components (e.g. helium), the treatment system is designed to capture and collect such components for additional revenue streams