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Air/solid-injectors are used as feeding devices for many pneumatic transport applications. The disadvantage of using such injectors is that the energy consumption may exceed what required for the actual conveying of the solids. In order to achieve an optimum design for good energy efficiency and satisfactory performance, the development of an injector performance analysis model based on the knowledge of pressure distribution and velocities of solid particles in the injector is essential. While the design and performance analysis models for gas/solids-injector can be found in existing publications, correlation between design parameters and injector performance is not clearly presented. In this thesis, one-dimensional equations to model the flows of solids and the transporting air were established. The design equations were coded as a computer program for computational purposes. Two laboratory scale air/solid-injectors with adjustable design parameters were constructed. The measured quantities include the pressure profiles and solid velocity distributions in the injector. The model predictions are compared with test results under cold conditions. One important design parameter is the exit-to-inlet distance, that is the distance between the exit of the primary nozzle and the inlet of the secondary nozzle.Test results indicated that there is an optimum exit-to-inlet distance that can produce a maximum solid flow. If the exit-to-inlet distance is too large, a positive pressure may develop in the region near the primary nozzle exit, which could cause solids blowout.On the other hand, when the exit-to-inlet distance is too small, the area for solids flow may be seriously restricted. Both extremes would cause a drop in solids flow rate. The ratio of primary nozzle and mixing tube diameter were also found important in conveying distance, the value of this nozzle ratio between 0.4 to 0.9 were suitable for general conveying,if need longer conveying distance, higher ratio of this two nozzle diameter was suggested. If we need larger solids velocity, lower value of it should be chosen. In this thesis, Design parameters were divided into two groups. One included central parameters and the other one included minor parameters. Different conveying tasks should focus on different design parameters first. If solids mass flow rate was important, primary and secondary exit-to-inlet distance and primary-mixing diameter ratio should first be decided. If conveying distance is crucial, diffusing tube's length and its diverging angle should first be decided.
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