Low Cost Solution to Increase the C2 & C3 Product Recovery from LNG Feed

An operating methane/ethane recovery plant from Liquefied Natural Gas (LNG) feed was facing limitations to process design throughput due to a variation in operating parameter of LNG feed. About 92% of design capacity of LNG feed is only being processed as flooding is observed inside the Demethanizer column, eventually leading to tripping of the plant. The limitations in the throughput has direct implication on the revenue as lesser throughput reduces the product generation. Various field trials were attempted within the existing setup to increase the throughput to the plant, however the throughout could not be increased. Operating an LNG plant is comparatively complex due to its unique characteristics, as even one degree change in the temperature has effect on the liquid vaporization. To achieve the design feed throughput rate, as a permanent solution, the temperature of the feed before entering the demethanizer column has to be increased. Various locations for increasing the temperature in the plant were studied in this paper. The identification of location for preheating plays an important role in the costing. For every one degree Celsius increase in the feed temperature, the duty of the exchanger increases three folds. This paper explains the low cost solutions to increase the throughput to the plant, thereby increasing the product generation of C2, C3 products from LNG feed prior to regasification.