There are many different designs to produce Syngas and MeOH from natural gas. The efficiencies of these processes will vary +/- 10-15% but a “typical” Methanol plant balance is:

1 MMSCFD CH4 => 2.4 MMSCFD Syngas at 2/1 H2 to CO ratio (includes feed + Fuel)

2.4 MMSCFD Syngas => 0.8  MMSCFD MeOH

0.8 MMSCFD MeOH = 67,500 Lb/D MeOH = 243 BPD MeOH

Syngas  typically is 2H2 + 1 CO  but 3H2 + 1 CO2 will also work. because  the water gas shift reaction: CO + H2O CO2 + H2  is usually  near equilibrium in Methanol synthesis reactors.  

for those unfamiliar with British units: 379.5 SCF = 1Lb- Mole  = 453.9 g-mole

MM = 1000,000 (M could mean 1000 to some and 1000,000 to others)

An efficient steam methane reformer will require 350 MMbtu to produce 1 MMSCF of syngas.(after taking credit for High pressure (600 PSIG) steam production.

An older less efficient unit will require about 400 MMbtu

This catalyst vendor's description of the methanol synthesis process may be helpful. Similar material if available from other catalyst vendors and technology licensors.

This is a technological data that can only be obtained from the methanol producer.

Earlier, you have to give yourself some questions. What type of reactor, which catalyst and whether pure CO2, or mixed with CO. In addition, what source of hydrogen and CO2.

Modeling and simulation is another story. We have been working for many years on the kinetics of methanol synthesis from CO2 and separately from CO and CO2 in the presence of copper catalysts. We also modeled a multibed reactor with side injection of cold gas. But that's only a small part of the problem.

Regards,

Have a look at this paper:

https://doi.org/10.1016/j.apenergy.2015.07.067

Table 1 gives a summary of technological metrics. I can provide the CHEMCAD simulation which we utilized for the evaluation.

You need some red hot carbon for passing CO2 and steam. Then you can do the water gas shift reaction and commercial low pressure process for methanol.

Thank you all for your valuable comments. I wanted the variation of the power demand with different amount of methanol production. also the cost analysis which may vary non linear with the amount of methanol production. If anyone know a graph that present these relations I would be thankful.