Although the theory of fluidized bed technology is fairly well understood, non-premixed reactions in such beds have recently garnered considerable attention, particularly with respect to combustion applications, which still present a number of practical engineering and operational problems at start-up, during operation and at shutdown. While studies of such processes in fluidized beds remain essential to validating theoretical models, young researchers often perceive them as dirty and tedious experiments due to the complex operational concerns involved. Nevertheless, the planning and implementation of experiments, the analysis of the full array of interactions between system components and bed materials, internal surfaces and measurement devices, and interpretation of results to diagnose abnormal operating conditions present operators with a range of difficult intellectual challenges. Some of the important experimental issues involved in the operation of non-premixed reactions in fluidized beds are presented and discussed. In particular, widening the range of fluidized bed system operations to include direct fuel injection can expand the range of reactant compositions beyond those normally allowed by safety constraints. Therefore, the aim of this study is to understand the behaviour of non-premixed natural gas combustion in turbulent fluidized bed using various spargers under high temperature conditions. The results of this study can also provide insights into how volatiles bum inside fluidized bed reactors. (c) 2007 Elsevier B.V. All rights reserved.