Flowsheeting and optimisation of the BrOx cycle for CO2-free energy production from natural gas

The BrOx (Bromination-Oxidation) cycle is a novel process that enables energy generation from natural gas without concomitant CO2 emissions. The cycle's main units are two exothermic reactions and two separation steps that result in an overall process in which methane and oxygen yield water, solid carbon and energy. The flowsheeting of the process has been conducted and optimised with Aspen Plus®. The simulation of the reaction section shows that complete conversion of methane can be achieved during methane bromination while ensuring that brominated by-products are only present as traces. Additionally, a reaction configuration consisting of a thermal step (800 °- C 950 °C) and a catalytic one (350 °C) has proved to be optimal for conducting hydrogen bromide oxidation. A separation train consisting of one decanter, two distillation columns and a flash has been selected as the best option for the separation of the bromine-water stream. The use of chlorine has been in the cycle (ClOx) has been compared to the BrOx cycle resulting in lower energy efficiency and more equipment requirements thus demonstrating that bromine is the most suitable halogen for the process. After applying heat integration the efficiency of the process is 73.30%, showing the feasibility of the BrOx cycle.