This paper presents some experimental results of discharge characteristic of cohesive fine coal from aerated hopper. A plexiglas hopper was used to visualize the flow pattern of the coal discharge. Arch can be easily formed during the gravity discharge. The addition of gas can improve the stability and the flow rate of the discharge. At low gas flow rate, two kinds of flow pattern existed at the same time, mass flow and swirl flow. As the gas flow rate increased up to a high level, gas balanced arch occurred, and the discharge rate decreased sharply. In addition, the effect of aeration pattern and outlet diameter on the coal discharge has been studied. Different aeration position results in different flow pattern and stability. Controlling the gas flow rate can realize maximum discharge rate. During the aerated discharge, the influence of outlet diameter and bulk status is changed with the gas flow rate compared with the gravity discharge. According to this law, a new model has been developed to predict the mass flow rate.

The application of the capacitive solid mass flowmeter manufactured by Thermo Ramsey in the pneumatic conveying system of pulverized coal is presented.The influence on measurement accuracy resulting from setup of its intrinsic parameters,installation position in the pipeline,the concentration of pulverized coal calibration method is investigated.This is valuable to master the application and performance of flowmeter,and effective to provide reference for basic research of gas-solid dual-phase flow and industrial online measurement.

The flow characteristics of pulverized coal from a glass aeration silo was investigated.There existed a critical surface above the joint of bin and hopper during discharging.Plug flow was discovered above the critical surface in the experimental research,while pulverized coal flowed spirally under the critical surface randomly.The results showed that aeration gas had a great effect on mass flow rate and flow stability.There existed an appropriate location of aeration gas supply and superficial velocity.Gas pressure balance arching would form easily when the aeration gas supply was too low.Flow rate could be increased and flow stability could be improved by increasing silo pressure.Also increasing silo pressure could decrease the effect of the location of aeration gas supply and superficial velocity on flow rate and stability and could prevent the formation of gas pressure balance arching.

The effects of the air make-up mode,the hopper structure and the filling height on discharge stability of pulverized coal from bunker were investigated.The percentage of cross sectional area for effective coal flow in the hopper is the most important factor affecting discharge steadily.Using one or more outlets,a steady mass flow takes place in a properly structured multi-outlet hopper with combination of air flux in the different aeration sections.The filling height has only a minor effect on the stability of discharge.

Taking pulverized coal and dry air as the experimental materials,the flow properties of high-concentration gas-solids two-phase flow in an industrial scale horizontal stainless steel tube(I.D.39 mm)were studied.The main flow pattern was identified as stratified flow observed through a quartz glass tube.The test results indicated that the conveying characteristics were dependent on the relationship of the fluidizing gas and adjustment gas.Based on the comparison of test results of two conveying tubes(39 mm and 20 mm in diameter),some empirical expressions relating the larger tube's operating parameters,including system pressure,gas volume flow rate and solid mass flow rate,were presented.Comparisons of the two conveying tube's phase-diagrams showed:the mass flow rate of pulverized coal in the larger tube was affected by the system pressure more strongly than that in the smaller one;the larger tube had a higher superficial gas velocity at the pressure drop minimum point and a lower pressure drop if the solids mass flux rate was constant;and the change of pressure drop was less remarkably triggered by the change of solids mass flux rate.