Methanol Production from High CO2 Content Natural Gas

BENJAMÍN CAÑETE; BRIGNOLE, NÉLIDA B.; GIGOLA, CARLOS E.

San Diego

Simposio; PSE 2018; 2018

Computer Aided Chemical Engineering (CACHE)

A process for methanol production from natural gas containing 30-80% CO2 was analyzed. For this design a partial feed hydrogenation process is followed by a combined reforming operation and H2 injection in order to obtain syngas of appropriate quality. A methanol plant of 400,000 t/y that uses a Lurgi reactor for the synthesis reaction, was simulated to obtain mass and energy balances. Although the total amount of required H2 increases with the CO2 content up to H2/CO2 ≈ 2, it is considerably lower than the quantity required by direct CO2 hydrogenation processes. It was also demonstrated that the reformer size decreases and the global CO2 conversion to methanol increases leading to lower emissions. An economic analysis showed that this methanol process has lower investment costs, but higher operating costs in comparison with a methanol plant based on CH4 steam reforming. This is related to the high H2 cost, which was assumed to be obtained by water electrolysis. A preliminary financial analysis indicated that a positive net present value based on current H2 and methanol prices is obtained when the CO2 content is less than 50%.