(486f) Process Synthesis and Intensification for Upgrading Natural Gas Liquids in Shale Gas

Shale gas is a promising energy resource and chemical feedstock for the transition period towards a sustainable economy and has the potential to be a carbon source for the long term. However, huge amount of shale gas at remote shale gas basins is directly flared¹ due to the lack of infrastructure to transport the gas from the well head to the central processing plant. To avoid long distance transportation, it is essential to covert shale gas to value-added products on site at a distributed scale. The value-added products could be gasoline, diesel, aromatics, alcohols, or any other liquid chemicals which can be easily shipped. Unlike current shale gas process where large scales are preferred, simple and intensified processes with least processing steps and least pieces of equipment are favored for remote shale plays.

Natural gas liquids contained in shale gas are especially of our interest since they are comparably easier to activate and transform to liquid products. In the current work, novel processes are developed to achieve the upgrading process and more importantly, several key process intensification principles are summarized which can be potentially applied to any process that requires a modular and intensified design. While conventional shale gas processing usually follows a four-section hierarchy of “gas treatment - NGL recovery - NGL fractionation - NGL activation”, our innovative configurations provide a paradigm shift and result in much simpler and more intensified process designs, including NGL co-processing², integrated NGL recovery and activation, switched NGL recovery and activation, and eliminated NGL recovery. A two-step conversion of NGLs to liquid hydrocarbons via dehydrogenation followed by oligomerization is used as an example to show how these innovative process designs evolve. Simulation results show that the loss of ethane, the NGL component with the highest concentration, could be largely reduced by the innovative process configurations. At the same time, higher yield of liquid products, fewer processing steps, reduced pieces of equipment and elimination of energy and capital-intensive units can be achieved. The intensification of process here would benefit the modularization of shale gas plants and make it possible for onsite distributed production of liquid hydrocarbons for remote shale locations.

Reference

1. Natural centers for environmental information. Global gas flaring observed from space. https://ngdc.noaa.gov/eog/viirs/download_global_flare.html (accessed 04/06/20)
2. Ridha, T., Li, Y., Gençer, E., Siirola, J. J., Miller, J. T., Ribeiro, F. H., & Agrawal, R. (2018). Valorization of Shale Gas Condensate to Liquid Hydrocarbons through Catalytic Dehydrogenation and Oligomerization. Processes, 6(9), 139