Carbon dioxide abatement by integration of methane bi-reforming process with ammonia and urea synthesis

Abstract

The use of thermal power plants has been increasing lately, despite its use being associated with high greenhouse gases emissions, especially carbon dioxide. In the context of the Paris Agreement of 2015, carbon dioxide capture, storage and utilization techniques must be increasingly employed to reduce environmental impacts. The utilization of carbon dioxide from a power plant flue gas as feedstock to other chemicals synthesis (such as ammonia and urea) arises as a good alternative to achieve near-zero carbon dioxide emissions. The aim of this work is to propose an alternative route, based on the bi-reforming of methane, for the synthesis gas section of ammonia and urea production plants, in order to promote carbon dioxide abatement, comparing this innovative route with the conventional and century-long existing process. Technical and environmental metrics of the proposed and conventional routes were compared. Aspen Plus® process simulator was used to simulate the bi-reforming process and both routes for ammonia and urea synthesis and choose the operational parameters. Simulation results show that for a target production of 2000 tonne/day of urea, the proposed alternative route has the potential to abate 745 tonne/day of carbon dioxide, while the conventional route emits 1156 tonne/day of carbon dioxide. Comparison of technical metrics of both routes shows that the proposed route requires an electricity usage of 0.27 MWh/tonne of products while the conventional route requires 0.47 MWh/tonne of products. However, hydrogen yield in the conventional route is higher than in its counterpart, with 0.41 and 0.22 tonnes of hydrogen produced for each tonne of inlet natural gas in the conventional and proposed routes, respectively. Comparison of economic metrics of both configurations show that none of the routes are economically viable, however, the alternative route has better economic indicators besides successfully promotes carbon dioxide abatement.