The ConocoPhillips Optimized Cascade® process includes proprietary technology necessary to efficiently and effectively liquefy natural gas, while recovering heavier hydrocarbons as a separate product (prevents freezing), and removing nitrogen, if required. The methods we use to integrate the technologies result in a reduction of cost and maximize efficiency of the overall LNG plant.
The schematic below illustrates how the Optimized Cascade process produces LNG. The raw gas is first treated to remove carbon dioxide (CO2), Hydrogen Sulfide (H2S) and other sulfur compounds, water (H2O), organometallic mercury compounds, particulates, and other contaminates before it is routed to the liquefaction section of the plant. The treated gas is then chilled and condensed to approximately -162°C in successively colder heat exchangers, using pure propane (or propylene), ethylene, and methane as refrigerants. The LNG product is then pumped into insulated storage tanks where it remains until shipment. Boil-off gas and ship return vapors are captured and recycled through the Optimized Cascade process for efficient re‑liquefaction.
Key components of the Optimized Cascade process in use at Darwin LNG
Optimized Cascade® is a registered trademark of ConocoPhillips Company in the United States and certain other countries.