Optimization and experiment on the dual nitrogen expansion liquefaction process with pre-cooling

In this study, a small-scale natural gas liquefaction device was built to verify the feasibility of optimization results of the dual nitrogen expansion natural gas liquefaction process with pre-cooling. From the thermodynamics perspective, the feasibility of using R22 instead of propane as a pre-cooling refrigerant, and nitrogen instead of natural gas as the feed gas was verified. Furthermore, a genetic algorithm was used to optimize the operational parameters of the dual nitrogen expansion liquefaction process. The operational performance and adaptability of the process were evaluated based on sensitivity experiments. The experimental results revealed that the relative error of the key node parameters between the experimental and simulation results was within 10%. Moreover, the experimental device and liquefaction process had a relatively large processing capacity (approximately between 35% and 130%), which is suitable when gas field production attenuation is relatively fast. The experimental device was insensitive to the pressure and temperature of the feed gas, and exhibited excellent adaptability.