System and Market Analysis of Methanol Production Using Compact Engine Reformers

Abstract

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.

The engine reformer: Syngas production in an engine for compact gas‐to‐liquids synthesis

“…The relationship between the molar composition and the parameters x H2 , x C2H6 , and f M when C 2 H 6 and H 2 are added to the feed is shown in Equation (5), and f HC can be computed using Equation (6). Note that f HC ¼ f M when x C2H6 ¼ 0, as expected.…”

“…This can promote partial oxidation (POX) to produce syngas, and can therefore be used in tandem with a liquids synthesis reactor to make liquid fuels such as methanol, as described in Acocella et al [6] The main role of the internal combustion engine in today's society is producing power by converting the chemical energy in fuel to useful work. In a conventional engine, complete combustion of a fuel such as CH 4 is desired to maximize combustion efficiency and minimize hydrocarbon emissions.…”

“…The economics of these technologies are also bound by the high capital investment required, while an engine performing non-catalytic partial oxidation may not be constrained in quite the same way. [6] Conventional GtL technologies are only economical on a large scale. For example, the Shell Pearl GtL plant in Qatar produces 140 000 barrels of oil equivalent per day (boe/d) of GtL products (equivalent to 850 TJ/d).…”

“…To illustrate the cost improvement, the capital cost of large methanol plants is estimated to be 700 $/t/a, [8] while a 30 t/day methanol plant using an engine reformer to produce syngas is projected to cost 360 $/t/a. [6] The use of air or O 2 as an oxidizer remains a point of debate. While O 2 improves performance by increasing the throughput of the plant, the air separation unit (ASU) adds cost and size, making it difficult to make the system portable.…”

Micro‐syngas technology options for GtL

“…Hydroformulation of olefins 8. Integrated gasification combined cycle [13] Steam methane reforming (SMR, Equation (1)), autothermal reforming (ATR, Equation (2)), partial oxidation (POX, Equation (3)), catalytic partial oxidation (CPOX), dry methane reforming (DMR, Equation (4)), plasma reforming, and an engine reformer [8] are options to produce syngas in the first step.…”