Gas-to-Methanol Production at Lower Operating Conditions: Techno-economic Analysis of SMR, ATR, and DMR

Abstract

Methanol production is basically through the traditional methods of Steam Methane Reforming (SMR), Auto-Thermal Reforming (ATR), and Dry Methane Reforming (DMR). However, the process is usually energy intensive, up to 100 bar and 1000oC, leading to high associated and operating costs. This study investigates the techno-economic feasibility of methanol synthesis at lower temperatures and pressures, based on the equilibrium expression presented by Turton, et al. Three (3) methanol production routes were investigated; The Steam Methane Reforming (SMR), the Auto-Thermal Reforming (ATR), and the Dry Methane Reforming (DMR). The peculiarity in each production option was simulated using Aspen HYSYS v11 software. The process parameters were rigorously optimized using the optimizer tool in Aspen HYSYS V11, in order to achieve the most economical yield while meeting the acceptable quality benchmark for the product. The initial simulations were carried out using values from the upper end of the operating ranges as stated in literatures. While monitoring the product yield and quality, the process operating parameters which essentially are the pressures and temperatures point to point through the flow schemes, were reduced to either the lower end of the operating ranges or even much lower provided, an optimum product yield rate and quality was obtained as output. The involved process equipment was sized on a preliminary level in order to estimate the plant cost using the same feed rate of 100MMscf/d of natural gas for all three cases. The simulation results showed that methanol synthesis was optimized at 40o C and 15 bar. a. Furthermore, the ATR option gave the most methanol throughput at 5128.8 MTPD, the SMR option produced 4802.4 MTPD, while the DMR had the least output at 3434.4 MTPD. All three cases proved profitable, with a payback period ranging between 4.82 to 6.52 years. Despite requiring the most capital investment of USD2.136 billion, the ATR option is the most viable technology for this production scale and the quickest to pay back invested capital (4.82 years). As such, it is the most recommended option.