Incorporation of flare gas into methanol production: techno-economic feasibility on tri-reforming process modeling, simulation and heat integration

Abstract

The primary objective of this research is to evaluate the feasibility of producing methanol using syngas obtained from methane tri-reforming, incorporating flare gas as a raw material, through techno-economic analysis. The simulation of the tri-reforming reactor utilizes kinetic model developed by Borreguero et al. (2020), while the methanol reactor simulation is based on the kinetic model developed by Bussche and Froment (1996). A configuration involving three pre-reactors is utilized to convert the heavier hydrocarbons found in methane source raw materials. These heavier hydrocarbons could lead to catalyst deactivation in the tri-reforming reactor. Additionally, the pre-reactors are utilized to generate the energy needed for the steam reforming and dry reforming of methane reactions. A sensitivity analysis was conducted to examine how the feed composition, pressure, and temperature affect the syngas production process. The impact of temperature was investigated by maintaining a constant pressure of 1 atm and a feed H2O/CH4 ratio of 1.5 in the methane tri-reforming reactor, while varying the temperature between 250 °C and 950 °C. The influence of pressure was assessed by maintaining a constant reactor temperature of 850 °C and a specific H2O/CH4 ratio, while varying the pressure from 1 to 10 atm. The effect of the feed H2O/CH4 molar ratio was investigated by maintaining a constant reactor temperature of 850 °C and a specific pressure, while varying the feed H2O/CH4 ratio from 0.15 to 2. In the methanol production section, the effect of temperature was investigated by maintaining a constant pressure of 50 atm in the methanol reactor and a syngas H2/CO molar ratio of 2.81, while varying the temperature from 200 to 400 °C. The impact of pressure was examined by keeping the reactor temperature constant at 220 °C and the syngas H2/CO ratio at 2.81, while varying the pressure from 1 to 79 atm. The effect of the syngas H2/CO molar ratio on reactor performance was assessed by maintaining a constant pressure of 50 atm and a temperature of 220 °C, while varying the ratio from 0.12 to 3. The key economic parameters, such as net present value, internal rate of return, and payback period, were computed, demonstrating the economic viability of the process. Additionally, the potential energy savings resulting from the implementation of a heat energy network for the entire methanol production process were determined.