A model for a residual hydrocracking unit combining a comprehensive kinetic model with efficient phase equilibrium calculation has been created. For chemical reactions the model uses actual well-defined chemical components (base components) and kinetically limited stoichiometric reactions. For the phase equilibrium calculations base components are combined to lumps in order to accelerate the calculations. The physical properties of lumped component are based on those of the base components. The novelty involved in the model is that the physical properties of the lumps are continuously updated when the composition of the base components changes. The advantage of the model is that it avoids the tedious iteration of phase equilibrium with the full base component set, whereas allows full component set in kinetics calculation. The model is computationally very efficient and is demonstrated to work with a system of 19 444 base components and 486 079 reactions. For vapor-liquid equilibrium (VLE) calculations the components are lumped to 42 lump components, and for vapor-liquid-liquid equilibrium (VLLE) calculations they are lumped to 162 components.