NGL/LPG Extraction from Marcellus Shale Gas
This process describes a design in which 6 million metric tons per annum of Marcellus Shale Gas is separated into its components through heat exchangers, pressure drops, and, finally, flowing through distillation columns. The goal was essentially to remove all of the methane gas as the overhead product of the heavy removal column and use the subsequent columns to fraction off heavier hydrocarbons. Heat exchangers could not remove sufficient heat from the feed prior to entering the columns and as a result, the overhead product for the heavy removal column consists of 84% by mole of methane and 15% by mole of ethane. Essentially all of the methane is being removed with the overhead product of the HRC but 85% of ethane is being removed here as well. By selling the major product (ethane) and the byproducts (propane and butane), our process design solution yields a net present value of $166.0 million, with an internal rate of return of 32.3%. The high profitability is secured in a sensitivity analysis on the ethane selling price, the total permanent investment, and the total fixed cost.