The liquefaction area representing the AP-X liquefaction process technology designed for use at the Qatargas 2–Train 4 LNG facility in Ras Laffan Industrial City, Qatar. Courtesy of Qatargas. Click to enlarge.

An LNG train is the unit that transforms natural gas into liquefied natural gas by cooling its temperature to -162 °C. This single LNG process train for the Qatargas 2 facility, located in Ras Laffan Industrial City, Qatar, is rated for an annual LNG production capacity of 7.8 million tons per year (MTY), making it the first in a coming series of the world’s largest LNG process trains involving Air Products’ technology.

The AP-X process cycle is an improvement to earlier cooled mixed refrigerant processes in that the LNG is subcooled using a simple, efficient nitrogen expander loop instead of the mixed refrigerant. In addition to improving the efficiency, the use of the nitrogen expander loop makes greatly increased capacity feasible. The nitrogen expander loop is a simplified version of the cycle employed by Air Products in hundreds of its air separation plants and nitrogen liquefiers worldwide.

The feed gas for the project will come from Qatar’s North Field, the largest offshore non-associated natural gas field in the world, with proven natural gas reserves in excess of 900 trillion cubic feet.

Air Products’ new AP-X technology is also being installed for three other LNG trains under construction for Qatargas in Ras Laffan, Qatar: Qatargas 2 (Train 5), Qatargas 3 (Train 6), and Qatargas 4 (Train 7). All of these process trains have a design capacity for an annual LNG production capacity of approximately 7.8 MTY.

A majority of the total worldwide LNG is produced with Air Products’ technology. Air Products has designed, manufactured and exported more than 75 LNG heat exchangers from its Wilkes-Barre, Pa., United States facility over the last four decades.

In support of the LNG industry, Air Products provides process technology and key equipment for the heart of the natural gas liquefaction process, and also nitrogen plants for the base-load LNG facility. Upstream, Air Products provides both nitrogen and natural gas dehydration membrane systems for offshore platforms. Downstream, Air Products provides dry inert gas generators for LNG carriers, shipboard membrane nitrogen systems, land-based membrane and cryogenic nitrogen systems for LNG import terminals, and process technology and equipment for small and mid-sized LNG plants, floating LNG plants and LNG peak shavers.

Resources

• Large Capacity Single Train AP-X Hybrid LNG Process