Gas-Liquid Equilibrium GLE

Gas solubilities can be calculated using Henry coefficients, //,j In contrast to VLE, the value of the activity coefficient y approaches unity, when x, becomes zero. For small solubilities and low gas pressure, the activity coefficient and the fugacity coefficient can be neglected and Equation (7) can be simplified  

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Several investigations of these petrochemical processes address the question of co-current versus countercurrent operation [1, 9, 10]. Whereas reactive distillation is a countercurrent operation by definition, in HDS, HC and HDN countercurrent operation is favorable because the gas-liquid equilibrium (GLE) of H2S and ammonia lies to high extent on the gas side. However, this cannot be generalized. As shown in Fig. 8.3, an internal loop can occur if the gas flow, which stripped the... 

In all cases, the selective solvents (entrainers) have the task of altering the partition coefficients in a way that high separation factors and selectivities for the different phase equilibria (extractive distillation vapor-liquid equilibrium (VLE), extraction liquid-liquid equilibrium (LLE), absorption gas-liquid equilibrium (GLE)) are achieved, resulting in a separation of compounds. The required partition coefficients, separation factors and selectivities can be calculated with the help of thermodynamic models (g -models, equations of state). 

We start with gas-liquid equilibrium (gle). For simple mixtures of similar components, gas-liquid coexistence states are observed at a wide range of T and p that are bounded at the high-temperature side by the critical states and at the low-temperature side by the formation of solids. In mixtures of large difference in molecular attractive forces, liquid immiscibility takes place. On the high-temperature side, liquid-liquid equilibrium (lie) either merges into gas-liquid equilibrium (gle) or becomes bounded by separate critical states. With extremely dissimilar molecules, the liquid-liquid coexistence phenomenon persists without limit to high temperature, where it turns into gas-gas equilibrium (gge). 

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