**2. Experiment**

The technique of dense-phase pneumatic conveying has been widespread applied in industry. Investigations on dense-phase pneumatic conveying usually include experimental research and theoretical research because of the complexity of flow in pneumatic conveying. But, both of the methods have limitation. In experimental research, calculation of some conveying parameters mostly depends on empirical equation based on experiments which leads to the limitation, and which are the same with its experimental condition commonly and generalized hardly.

Experimental research were carried on by changing feeding pressure on the positive pressure style pneumatic conveying pilot-scale experiment table. The conveying characteristics along pipeline were studied primarily.

Pneumatic conveying system in this paper was a circulating experiment system with longdistance pipeline, which consisted of an air compressor, a feeder, a conveying pipeline, and a set of measurement/control system, as shown in Fig.1.

The pipeline was made of seamless steel pipe with a length of 203 m and pipe diameter of 80 mm. Weight balance was installed to measure the fly ash discharge rate of the feeding bin. Gas mass flow meter was adopted to measure the mass flow ratio of the compressed air.

Numerical simulation technique improves rapidly with the advance of computer hardware. And it plays more and more important role in the research of dense-phase gas solid flow. This article gave the numerical simulation conclusions based on the experimental and theoretical research. By associating with experimental condition and the applicability of experimental equations, transport equation of Reynolds was deduced by using time averaged method based on instantaneous equation of gas and solid. The control equations of turbulent energy and turbulent dissipative ratio were formed, which considered reciprocity between gas and solid, collision of particles and interaction between particle and wall. The model included continuity equation, momentum equation, turbulent kinetic energy equation and turbulent kinetic energy ratio equation. Physical meaning of primary

Two-fluid model of gas-solid turbulence in process of dense-phase gas solid two phase flow was founded, so did the corresponding numerical solution and calculating flow. The model could mention reciprocity between gas and solid, collision of particles and interaction

The process of dense phase gas solid two phase flow in pipeline under experimental conditions was simulated with FLUENT software by founded model and corresponding arithmetic. Pressure distribution diagram, density distribution diagram and velocity vectogram etc. were given which displayed the flow alternation of dense-phase pneumatic conveying. And comparison between simulated result and experimental case showed good

In all, in this study, fluid mechanics characteristics of dense-phase gas solid two phase flow in pipeline were discussed by computational fluid dynamics method based on flow theory of gas-solid, and a series of significative results were obtained. The research showed that the numerical simulation of dense-phase pneumatic conveying can complement experimental and theoretical studies which had promoted effect on the application and development of

The technique of dense-phase pneumatic conveying has been widespread applied in industry. Investigations on dense-phase pneumatic conveying usually include experimental research and theoretical research because of the complexity of flow in pneumatic conveying. But, both of the methods have limitation. In experimental research, calculation of some conveying parameters mostly depends on empirical equation based on experiments which leads to the limitation, and which are the same with its experimental condition commonly

Experimental research were carried on by changing feeding pressure on the positive pressure style pneumatic conveying pilot-scale experiment table. The conveying

Pneumatic conveying system in this paper was a circulating experiment system with longdistance pipeline, which consisted of an air compressor, a feeder, a conveying pipeline, and

The pipeline was made of seamless steel pipe with a length of 203 m and pipe diameter of 80 mm. Weight balance was installed to measure the fly ash discharge rate of the feeding bin. Gas mass flow meter was adopted to measure the mass flow ratio of the compressed air.

suitable which illuminated the model had good accuracy and forecasting capacity.

item of control equation was discussed too.

dense-phase gas solid flow in pipeline technique.

characteristics along pipeline were studied primarily.

a set of measurement/control system, as shown in Fig.1.

between particle and wall.

**2. Experiment** 

and generalized hardly.

GP/DP transmitters were used to measure pressure of the feeder, setting points along pipeline and pressure drop of test segments.

Fly ash was transported from the feeder vessel into the receiver in dense phase. The material properties were shown in Table 1.

Fig. 1. Schematic diagram of experimental system. 1. air compressor 2. gas storage pot 3.oilwater segregator and air drier 4. gas adapter 5. gas inlet valve 6. gas flow meter 7. feeder 8. static pressure gauge 9. differential pressure gauge 10 dust catcher 11. collecting bin 12. weighing-appliance 13 data acquisition equipment 14. micro-computer 15. bleeder valve.

After being put into the feeder, fly ash was fluidized by compressed air. Then at a preset transporting pressure in the feeder, fly ash passed through the conveying pipeline and reached the collecting bin finally. Five test segments along horizontal pipeline were employed averagely to analyze the tendency of pressure drop along the pipeline. A differential pressure transmitter and a gauge pressure transmitter were assembled in the segments of 52.2 -53.4 m, 90.5 -91.7 m, 126.5 -127.7 m, 176-177.2 m. Gauge pressure transmitters were also installed at the terminal of pipeline (6) as well as the vent of feeder. In this experiment, operating condition was mainly controlled by changing the pressure of feeder The experiments under different operating conditions and each with several repetitions were carried out in total.


Table 1. Experimental material properties.
