The influence of gas type (air, He, H2 and CO2) on the fluidization and discharge characteristics of the pulverized coal was investigated in this paper. It was concluded that the gas viscosity was dominant over the gas density in influencing the fluidization quality. The increase of gas viscosity improved the fluidization uniformity, delayed the visible bubbling and promoted the discharge stability. Compared with air, a higher proportion of H2 rises through the coal bed while a higher proportion of CO2 escapes through the hopper outlet during the discharge process. Experimental results show that the discharge rate increases with the addition of H2 in the whole experimental range and CO2 always corresponds to the minimum discharge rate. In spite of the very different effects produced by the various gases, the relationship between the discharge rate and the pressure difference does not change a lot. Nedderman's mode was used to predict the discharge rate, which agreed well with the experimental data with the error kept below 20% except individual points at low aeration rate.

Experimental studies were performed to describe the physical phenomena occurring in dense phase pneumatic conveying of the pulverize coal with a Laval nozzle installed in the pipeline. The maximal coal mass flow rate decreased from 0.87kg/s to 0.35kg/s and an obvious decrease in the solids loading ratio was revealed after the Laval nozzle was installed. In addition, the Laval nozzle showed a better capacity of resisting disturbance, which made it easier to control the coal mass flow rate precisely and promoted the stable conveying process. These specific physical phenomena were proved to result from the high pressure drop of the Laval nozzle. Thereby, a mathematic model was developed to predict the two-phase pressure drop across the Laval nozzle. The pressure drop model described the experimental data within the 15% deviation. The main influence factors contributing to the pressure drop of the Laval nozzle were discussed using the model. Then the effects of gas mass flow rate, solids loading ratio, convergence angle, throat diameter and throat length were revealed.

Based on electrical capacitance tomography technique,the flow regime of dense-phase pneumatic transportation of pulverized coal was investigated.Typical flow regimes in the horizontal pipe and riser were obtained.The study indicated that the flow regime in the horizontal pipe varied significantly with time and there existed several flow regimes,such as full pipe flow,settled layer flow,suspension flow,etc.Statistical analysis results revealed that there were obvious prevailing flow regimes,which changed with superficial gas velocity.An analysis on solids velocity and pressure signals showed that the flow regime correlated reasonably well with pressure signals,which proved the inherent instability of dense phase pneumatic conveying.On the other hand,the dynamic test result of the riser showed that the flow regime was mainly core-annulus structure.

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.

Taking pulverized coal and dry air or CO2 as the experimental materials,the blockage critical state of pulverized coal dense-phase pneumatic conveying with pipelines of 10 mm,15 mm and 20 mm(ID) were studied respectively.The blockage critical characteristics,such as solids gas ratio,transporting velocity,pressure signal were obtained through reducing gas flow rate.Characteristic parameters and characteristic frequency of different stages were obtained by analysis of pressure signal characteristics and power spectrum analysis.The results showed that the blockage critical velocity was related to pipeline diameter and carrying gas characteristics.A dimensionless equation describing the relationship between blockage critical velocity and aforementioned parameters was finally established.Fluctuation of pressure signal was significant and vibration frequency converted to low frequency near blockage critical state.The criterion for blockage was obtained by mathematical calculation of pressure signal.

Research on the performance of the new flow regulating valve in industrial scale bore size for pulverized coal is carried out on the dense phase pneumatic conveying experimental device.Through changing the parameters and operational conditions,the influence of the structures of valve trim on conveying characteristics is observed.On the basis of systematic tests and analysis for valves with different structure of valve trims,the optimal trim configuration is obtained.The results of research indicate that under the same flow rate of pulverized coal,the solid-gas ratios obtained under different valve trim configurations are basically equal;under optimal configuration,with throttle area changing from 12% to 100%,corresponding regulating range of flow for pulverized coal is 50% to 96%;the smaller the throttling area are,the poorer the stability of conveying is.

This paper presents the effects of particle size, moisture content, and coal type oil the flowability of Pulverized coals. A plexiglas hopper for visualizing the coal discharge and a Jenike-type shear apparatus for measuring friction characteristics were used to investigate the flowability. The fine coal displays weaker flowability because of its larger specific surface area and stronger agglomeration in comparison to the relatively large-size pulverized coal. The number of agglomerated particles C-0 increases with the decrease in the particle size, which is also confirmed by the scanning electron microscopy (SEM) images. Increasing the moisture content tends to make the pulverized coal more cohesive. Cohesive forces acting among wet coal particles are mainly due to capillary forces associated with liquid bridging, which increases with the moisture content. However, the moisture content to some extent may act as a lubricant and improve flow along the wall surface. The coal type also has it significant effect on the flowability because of the differences in their compositions and physical structures. The measuring results show that the nowability of pulverized coal improves with the increasing coal rank.

A pressure drop model of PCI system was developed for Baosteel No.4 blast furnace based on the additional pressure drop.The empirical expressions of solid phase friction coefficient for horizontal pipe,rising pipe and bends with different radius of curvature were established.The predicted pressure drop was in good agreement with the production data.The model provides not only effective reference for designing blast furnace PCI system but also theoretical support for energy saving on Baosteel No.4 blast furnace system.

Pressure drops are measured on different nozzles of various pipe sizes in dense phase pulverized coal pneumatic conveying. From the experimental results, we conclude that the effect of the gas phase nozzle pressure drop is negligible when comparing with the solid phase pressure drop in the experimental range. The main influence factors contributing to the nozzle pressure drop are gas and solid mass flow rate, solids loading ratio, and the diameters of the nozzle inlet and outlet. A new model was developed to predict the nozzle pressure drop in dense phase pneumatic conveying of pulverized coal based on the Barth's pneumatic conveying theory. The pressure drop predictions from the model are in good agreement with the experimental values. The model quantified the important influence factors of the nozzle pressure drop.

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.

The utility model relates to a discharging device which is under a feeding device for carbon solid powder materials. The discharging device is connected with the lower end of the main feeder body of the feeding device, whose upper end is equipped with a feed port, and whose lower end is equipped with a discharge port. The utility model is characterized in that there are least three discharge ports and cone guiders with the same geometric shape and size. A joint plate is connected between a plurality of discharge devices and the guiders. The upper end of the discharge device is equipped with a feed port while its lower end is equipped with a discharge port. All feed ports of the discharge devices are in the same horizontal and the neighboring two feed ports are basically tangential. The conical tip of the guider is upward equipped in the horizontal of the feed port and located in the horizontal among all feed ports. The utility model could make carbon solid powder evenly discharged from several discharge ports with a stable quality flow rate so as to make the carbon solid powder feeding supplied to reactor through a plurality of nozzles with a high transport concentration.

以粉煤为输送介质，干燥空气为载气在内径为20mm的水平管内，进行了低压下密相气固两相流流形的实验研究。运用R/S分析方法和Hurst指数的计算方法对水平管压力波动信号进行处理与分析，发现随着表观气速的增加，压力信号的周期性不断减弱并对应着两相流流形的逐渐演变。通过石英玻璃管观察，并结合高速摄像仪拍摄到的煤粉的流动形态，识别出其在低气速下为栓状流动，随着气速的增加逐渐转变为分层流动。