Simulation and economic evaluation of a coupled thermal vapor compression desalination process for produced water management

Abstract

Produced water management at oil and gas fields is gaining vast attention due to its large volume, high salinity and high disposal cost. Opportunities for disposal by such methods as remote injection are shrinking and increasingly costly. On the other hand, gas flaring at the oil and gas fields wastes large amounts of thermal energy that could potentially be used to reduce the produced water disposal cost. In this paper, a coupled thermal vapor compression (TVC) desalination process powered by flare gas is proposed and rigorously simulated in Aspen Plus. Based on that, the energy intensity and unit product cost ($/vol. of product) are estimated and compared with multistage flash (MSF), multi-effect distillation (MED), mechanical vapor compression (MVC) and reverse osmosis (RO). Sensitivity analysis is also performed to obtain the ranges of energy intensity and production cost, which are influenced by the water salinity, boiling brine temperature, compression ratio, and motive steam pressure. Results indicate that the proposed TVC process is technically viable and cost-effective at most locations; it could also save roughly one-third of the disposal cost compared to the remote injection method.