Angola LNG has built one of the world’s most modern LNG processing facilities. It is located 350km north of Luanda, the capital of Angola, and at the mouth of the Congo River on the Atlantic Ocean. The plant is located on a 240 hectare site on Kwanda, an island within the delta estuary of the Congo River, which was established as a supply and support base for Angola’s offshore oil and gas industry.
Soyo was chosen for its potential for future development and its proximity to the offshore oil fields from which natural gas is sourced for the plant. Environmental impact studies also concluded that building the plant in Soyo would have the least environmental and socioeconomic impact, which has been a keen concern throughout development of Angola LNG.
Natural gas reaches the plant via a network of pipelines and is first treated to remove contaminants including carbon dioxide, water and mercury. This process not only purifies the gas but also removes anything that would freeze and cause blockages in the plant during refrigeration.
Lighter gases, such as propane and butane, are extracted to be sold separately or used later in the refrigerant process. Treated gas is then chilled to approximately minus 160°C (-260°F) in successively colder heat exchangers that use propane, ethylene and methane as refrigerants to produce Liquefied Natural Gas (LNG). This LNG is then pumped into insulated storage tanks before being exported by a fleet of long-term chartered ships to buyers around the world.
The Soyo plant is designed to process 1.1 billion cubic feet of natural gas per day and has the capacity to produce 5.2 million tons of LNG per annum – plus natural gas, propane, butane and condensate.
The plant represents an important step in the efficient use of Angola’s natural resources, and boasts a workforce which is now equipped with expertise in every facet of LNG production from plant construction, commissioning operations, and logistics.
The plant infrastructure includes storage tanks for LNG, propane, butane and condensate and an LNG loading jetty able to accommodate vessels up to 315m in length.
The production process is designed around a “two-train-in-one" reliability concept that allows the plant to continue operating at a reduced rate even when a compressor is offline, resulting in high plant availability.