Methanol Production from Natural Gas (Combined Reforming)

The process under analysis comprises three major sections: (1) syngas generation; (2) Methanol synthesis; and (3) purification.

Syngas generation. Natural gas feedstock is treated then converted to syngas in two steps in series: steam reformer and autothermal reformer (ATR). In the steam reformer, methane reacts catalytically with steam, generating CO and H2. In the ATR, methane is converted to CO and H2 using oxygen as the reforming agent. The ATR outlet stream is then cooled and the condensed water is separated from the syngas.

Methanol synthesis. The syngas is compressed and mixed with recycle gas and fed to the methanol-synthesis reaction system, where CO and CO2 react with hydrogen to generate methanol. The system outlet gas is mainly comprised of methanol, water vapor, unconverted hydrogen, CO and CO2. This stream is cooled, and methanol and water are separated from the gases by condensation. The separated gas is recycled with a small purge. The water-methanol condensate stream is sent to be purified.

Purification. The purification area is composed of three distillation columns. The topping column removes the dissolved gases from the crude methanol stream. In the pressurized methanol column, part of the methanol produced is obtained from the top of the column while the bottoms, still containing methanol, is sent to the atmospheric column to recover the remaining methanol.