Decarbonisation Technology - November 2021

New low carbon methanol production approach An innovative steammethane reformer-basedmethanol production process achieves significant reductions in atmospheric CO 2 emissions Dan Barnett BD Energy Systems, LLC

B D Energy Systems introduces TrueBlue Methanol, an innovative low carbon emission steam methane reformer (SMR)- based methanol production process to the industry. This process utilises proven techniques to achieve greater than 90% reduction in the emission of CO 2 from the stack of the SMR furnace while producing methanol with an overall energy consumption that is favourably competitive with even the newest operating SMR-based methanol plants. The TrueBlue process can be implemented not only on grassroot and relocated methanol plants but as an upgrade to many existing methanol plants for any natural gas fed process configuration. This process delivers a product CO 2 stream using an amine-based CO 2 removal system placed upstream of the methanol synthesis reactor. Doing so reduces the consumption of hydrogen in the methanol synthesis process, resulting in greater hydrogen availability for SMR fuel. Removal of hydrogen from the synthesis loop purge stream recovers hydrogen for use as SMR fuel, and recompression of the carbon containing tail gas allows recycle of most tail gas to the SMR feed. This recycle results in more complete conversion of incoming natural gas feed to synthesis gas, and use of hydrogen as the primary fuel effectively reduces SMR stack gas CO 2 emissions to a very low level. This article will present key flowsheet elements of the TrueBlue process and an overall performance contrast of the BDE process with conventional natural gas fed SMR-based methanol plants. Worldwide methanol production 1 is largely based on the use of natural gas feed, with

~65% of total methanol production based on natural gas, ~35% based on coal, and less than 1% currently based on renewables. Achieving significant reductions in atmospheric CO 2 emissions from natural gas-based methanol production is made possible with the approach outlined here. For the purposes of comparison, the ‘conventional’ SMR-based methanol plant is defined in general terms as one having a modern high efficiency SMR, an ‘isothermal’ methanol synthesis reactor, and combustion of the synthesis loop purge gas in the SMR. Overall energy consumption of a conventional SMR-based methanol plant is in the range of 27.0-28.0 MMBtu of total energy (LHV basis) per short ton of high purity methanol product. Total energy here is based on total natural gas, feed plus fuel, as well as net electric power import for the methanol plant and associated utility units. Use of natural gas (96-97% methane) as feed results in the production of more hydrogen than required for methanol synthesis. This excess hydrogen is typically purged from the methanol synthesis loop and burned as fuel in the SMR. This reduces the make-up natural gas fuel required for the SMR; however, required natural gas fuel make-up remains in the 7-8% range in terms of total required heat release. Further, the hydrogen containing purge gas from the methanol synthesis Conventional SMR-based methanol production loop also contains methane, carbon monoxide and carbon dioxide. Considering only the SMR fuel, not including fuel to a gas fired boiler or a gas turbine, the emission of CO 2 to atmosphere