An investigation of the effect of particle size on discharge behavior of pulverized coal

• The packing properties of the pulverized coals were described by ρb(σz) function.
• The flow properties of the simples were described by linear consolidation function.
• The discharge behaviors were predicted by a new approach, and verified by experiments.

In this paper, pulverized coal from industry was used as the experimental material. In order to study the effect of particle size, the pulverized coal was sieved into seven samples with different particle sizes. Firstly, the material properties as packing, incipient flow and wall friction properties were evaluated. Meanwhile, a transparent Perspex hopper was used to monitor the change of discharge behavior of pulverized coal caused by the increase of particle size. From the visual observation of discharge test, a progressive transition from blocking to unstable flow and to mass flow was found as the particle size increased. Hence, a complete set of physically based equations for compressibility, flowability and powder consolidation has been derived. Then, a new method, taking into account the stress state in the hopper, is introduced to assess the discharge behaviors of pulverized coal. The validity of this new method has been confirmed by comparing theoretical and experimental discharge behavior for pulverized coals. The theoretical approach based on stress state analysis, is able to provide results which correlate well with the experiments.

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