Study on the effect of lowering steam to carbon ratio in combined reforming of natural gas to the synthesis gas.

The objective of this research is to study the effect of lowering Steam to Carbon ratio
in a combine reformer to produce syngas in order to optimize the performance of the
combine reformer. A combine reformer in this project refers to the combination of
steam methane reformer (SMR) and autothermal partial oxidation reformer (POX).
Currently the steam to carbon molar ratio is maintaining at 3:1 ratio in order to
prevent carbon deposition on the nickel catalyst active surface. To achieve this, a
simulation model of the reformer unit using HYSYS simulation software version 3.01
was develops.
The preliminary stage of this research will focus on literature review of natural gas
reforming technology. Then second stage will focus on research for reaction kinetics
on the SMR and POX reaction. A simulation model will then be developed to further
analyze the reforming process by manipulating the operating condition and S/C ratio.
Finally the last stage of the research will focus on optimizing the operation of both
reformers.
Based on the simulation result and analysis on various S/C ratio, this project suggest
that operating the steam methane reformer using S/C molar ratio of 2:1 instead of 3:1
is favorable to methanol synthesis since carbon monoxide and carbon dioxide molar is
increased at S/C ratio of 2:1 and the amount of hydrogen produced is still in excess to
cope for the methanol synthesis requirement. However, since there is no physical
experiment to determine the actual carbon boundary, there is no strong basis to prove
that operating at S/C ratio at 2:1 will curb the carbon deposition problem. A
conservative suggestion will be to lower down the S/C ratio to 2.5:1, saving 14 tons
per hour of steam and its associated boiler feed water BFW treatment cost while
increasing methanol production. A detail experiment to determine the actual carbon
boundary is recommended since literature has been reported that optimum S/C ratio
between 1.9 and 4.5 for SMR.