Abstract
A material-utilization diagram (MUD), which represents energy and exergy features of phenomena with concentration change, is applied to methanol synthesis. The ordinate of the MUD is ln pj or ln Kp, r, whereas the abscissa is njRT0 or γrRT0, where nj is the number of moles of component j and γr is the extent of r-th reaction. Hence, energy loss caused by the decrease in partial pressure and exergy gain caused by the increase in partial pressure of each individual component relevant to the chemical reaction are displayed by a rectangular area –nj, inRT0ln(pj, out/pj, in) on MUD. The graphical representation of features of chemical reactions gives us intuitive suggestions, which are helpful in improving the process. Based on the information shown on MUD, three improved systems, introduction of membrane separation, addition of CO2, and two-staged pressures for operation, are demonstrated.
