New energy plants coming online must be both economical and efficiently balanced to satisfy demanding requirements in the future. A balance of plant analysis was performed to determine the techno-economic feasibility of a 100 barrel oil equivalent (boe) per day, compact Gas to Liquid (GTL) methanol plant. Methanol itself is emerging as a possible alternative to gasoline; but it is also the precursor to dimethyl ether (DME), which has recently received a lot of attention as a low emitter of particulate matter and nitrous oxides, which can replace diesel in trucking applications and liquefied petroleum gas (LPG) in domestic applications. Production of synthesis gas (syngas) from methane gas was modeled via partial oxidation of fuel-rich mixtures in engine cylinders using GT-ISE. Two ignition modes were studied: spark ignition (SI) and homogeneous charge compression ignition (HCCI). The use of the engine as a compressor was also studied in order to reduce net compression requirements and therefore capital and operating costs. The low brake mean effective pressure (BMEP) allowed in HCCI operation substantially limits both the throughput and capability to produce high-pressure syngas. The use of mechanical power generated by the engine reformer to power other components such as compressors and the air separation unit (ASU) have been studied. The waste heat produced from the engine and methanol synthesis reactors was also considered in the analysis. Integration of all components in the system was performed in Aspen Plus.
To inform plant design, a survey was performed of vendors with small-scale methanol synthesis technologies that could integrate an engine reformer. Aspen Process Economic Analyzer (APEA) was also used to generate estimates of plant component costs. A study of the profitability and payback period of the technology was performed to determine the cost to produce methanol based on the balance of plant analysis. The results of this analysis were used to gauge the technology’s feasibility and therefore provided constructive feedback to guide future plant design.