The problem of modeling a class of two-phase moving-bed tubular gasification reactors by means of a lumped (finite-dimensional) representation is addressed in this paper. A model is designed, as simple as possible, in the light of a specific - experimental, equipment, operation, monitoring or control - design task and the uncertainty of the underlying kinetics and transport parameters. First, the enforcement of quasi-steady state (QSS) gas-phase assumptions and stoichiometric considerations followed by spatial finite-difference approximation plus interpolation leads to a representation of the tubular reactor as a train of N continuous stirred tank reactors (CSTRs). Then, the number of tanks and their volumes are chosen according to the modeling objective. The proposed approach is illustrated with a case example, studied before with experiments and PDE-based simulations, finding that the dynamics of the tubular reactor can be modeled with three CSTRs (9-ODE). (C) 2013 Elsevier Ltd. All rights reserved.