EQUILIBRIUM-ANALYSIS OF SYNTHESIS GAS WITH COMPOSITION-DEPENDENT DEGREES OF FREEDOM

An analysis is presented of the equilibrium composition of syngas mixt ures parametrized in terms of the syngas ratio and the hydrogen mole f raction, for fixed values of pressure and temperature. Conditions for the existence of single or multiple carbon-free solutions are determin ed by analysis of the carbon affinity equation, formulated by the meth od of atomic potentials. The system is characterized by two curves des cribing the maximum possible mole fraction of hydrogen, and the mole f raction of hydrogen at unit carbon affinity. These curves are tangent to each other at a single contact point. The unit carbon affinity curv e consists of two branches, corresponding either to the higher or to t he lower carbon affinity root becoming equal to one. These branches jo in together at the contact point of the maximum bounding and unit carb on affinity curves. The syngas ratio at the contact point is pressure- independent and is expressed as a function of temperature. A single ca rbon-free solution is obtained in the region below both branches of th e unit carbon affinity curve. It is shown, however, that two distinct carbon-free solutions can be constructed in the region enclosed betwee n the maximum bounding curve and the right branch of the unit carbon a ffinity curve.