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Maximizing the profits of natural gas liquid recovery plants is a challenge. To improve the performance of an existing plant, three process schemes were compared and analyzed with Aspen HYSYS. A high‐pressure absorber (HPA) performed better owing to the added compressor and more reasonable cold energy utilization. The HPA was further optimized by establishing an objective function and identifying and adjusting the main variables on the basis of a new optimization algorithm. The propane recovery of the optimized HPA was 98.8 %, and the plant profitability increased by 3352 million $ a−1. Exergy analysis of the optimum process indicated that the column and air cooler contributed the most to the total exergy destruction. Suggestions for decreasing the exergy destruction of the process are also given.

The water-lubricated transportation of heavy oil seems to be an attractive method for crude oil production with significant savings in pumping power. With oil surrounded by water along the pipe, oil-water core-annular flow forms. In this paper, the characteristics of oil-water core-annular flow in a horizontal acrylic pipe were investigated. Plexiglas pipes (internal diameter = 14 mm and length = 7.5 m) and two types of white oil (viscosity = 0.237 and 0.456 Pa•s) were used. Flow patterns were observed with a high-speed camera and rules of flow pattern transition were discussed. A pressure loss model was modified by changing the friction coefficient formula with empirical value added. Totally 224 groups of experimental data were used to evaluate pressure loss theoretical models. It was found the modified model has been improved significantly in terms of precision compared to the original one. With 87.4% of the data fallen within the deviation of ±15%, the new model performed best among the five models.