Abstract:

The carbon conversion from the fluidized bed coal gasification is about 85%.The fluidized bed-entrained flow integrated coal gasifier was built with the aim to reuse the carbon in fly ash.A reactor network model was established by using the software CHEMKIN to study the reactions occurring in the integrated gasifier, and to investigate carbon re-gasification in fly ash.Based on experimental results on a 300 mm (i.d.) integrated gasifier, the raw materials inter-phase flow, mass and heat transfer in different zones and the hydrodynamic characteristics of the integrated coal gasifier were analyzed.This model is to simplify the unstable continuity process in the integrated gasifier into a combination of ideal reactors, attempting to avoid the non-convergence of the study on complex flow field with many reactions with the CFD model.This model could be significant in the accurate analysis of new reactor concepts with sufficient knowledge of the hydrodynamic characteristics of reactors.Through the model, the carbon conversion rate of fly ash in the integrated coal gasifier, temperature profile and residence time of materials were recorded and calculated respectively. It was concluded that carbon conversion rate of fly ash reached 64.1% in the entrained flow, and that the carbon in fly ash with low reactivity was re-gasified.Accordingly, the carbon conversion in the whole gasification system increased from 84.9% in the fluidized bed reactor to 92.2% in the integrated coal gasifier.