Evaluation of CO2 utilization for methanol production via tri-reforming of methane

This work evaluates the performance of a plant to produce 2000 tonnes per day of methanol using CH4 trireforming for syngas production. A sensitivity analysis is performed on the feed composition of a tri-reformer operating at 3000 kPa and 1000 degrees C to maximize its CO2 conversion and syngas stoichiometric number (SN). The optimum feed composition is determined as CO2: 0.20, H2O: 0.35, and O-2: 0.48 for each mole of CH4, resulting in a CO2 conversion of 50% and an SN of 1.57. Oxygen is injected at four locations along the length of the trireformer to manage the temperature profile of the reactor. A pressure swing adsorption unit with four columns and eight steps recovers hydrogen from unreacted gases to increase the syngas SN to 2.04, which is suitable for methanol synthesis. The net present value of the plant is $161 million for a 15-year economic life based on a methanol sale price of $390 per tonne. Monte-Carlo analysis of the plant economics indicates that there is an 84% chance for the plant to be viable considering the simultaneous uncertainties in influential economic parameters. The plant has net CO2 emissions of 0.91 kg CO2/kg methanol, which is 50% less than the conventional methanol plants based on the steam reforming of methane and 35% lower than other methanol plants based on CH4 tri-reforming.