Tuning the natural gas dew point by Joule-Thomson and Mechanical Refrigeration processes: A comparative energy and exergy analysis

Abstract

In this study, to adjust the dew point of natural gas, two methods of Joule-Thomson and mechanical refrigeration have been analyzed in terms of technical, energy and exergy. The basis of design was a natural gas feed with an intensity of 1743 kgmole/h. The initial dew point of the feed before processing was equal to 9.65 °C. Comparison of the results showed that the mechanical refrigeration method had much better performance and the energy efficiency in this system was 99.84%, while this value was 97.8% for the Joule-Thomson method. Furthermore, the intensity of gas condensate production, as one of the products of dew point adjustment unit, for mechanical refrigeration that uses propane refrigerant for natural gas refrigeration was estimated as 1842 barrels/day. This value exhibited an increase of 185% compared to Joule-Thomson method. The dew points of produced gas through Joule-Thomson and Mechanical refrigeration processes were −8.4 and −24.91 °C, respectively. It implies that the quality of hydrocarbons dew point in the produced gas was much lower for Joule-Thomson unit compared to mechanical refrigeration. However, in terms of exergy analysis, the mechanical refrigeration method had an efficiency of 88.69%, while the exergy destruction rate for this method was 15.78% less than the Joule-Thomson process.