Numerical Study of Load Characteristics of a CFB Coal Gasifier by Using the Generalized Drag Model

The load characteristics of a large circulating fluidized bed (CFB) coal gasifier were simulated by using the Eulerian–Eulerian method with the generalized drag model, QC-EMMS. The simulations predicted the gas–solid two-phase flows and coal gasification in a 60 m high CFB gasifier for 50, 80, and 100% loads. The results show that the simulated pressure drop, temperatures, and syngas compositions at the 50% load agree well with the field test data. The solid mass circulation rate and the H₂/CO ratio then increase linearly with the increasing load. The average temperature in the riser decreases slightly by 4% with the increasing load. The yield of effective syngas per ton coal stabilizes at 465 Nm³/t for loads over 80%. The study verifies that the QC-EMMS drag model can be used to accurately simulate the complicated gas–solid reaction processes in a large industrial CFB.