LNG Liquefaction with a Dual-Expander Nitrogen Cycle

A dual-expander nitrogen refrigeration cycle for LNG liquefaction: natural gas (55 bar, ~20°C) is progressively cooled through three heat exchangers and throttled to produce LNG, while the pure nitrogen refrigerant is split after the first heat exchanger — one stream expands at a warmer level and the other is cooled further before expanding at a colder level — then mixed and returned through the cold sides of the exchangers, improving cooling curve matching compared to the single-expander variant.