Study On Structural Optimization Of Pneumatic Conveyiny System Of Pneumatic Shotcrete Machine

Shotcrete machine can be divided into two types, namely, pumping dense flow type and pneumatic rarefied flow type. With compressed air stream as the diving force, the pneumatic shotcrete machine sends the properly-mixed concrete through the pipeline in the form of rarefied flow to the spraying nozzle before casting on the application surface vertically at a high speed. The continuous collision between cement mortar and aggregates and mutual filling within the shooting flow in the spraying process press the mixture tight and make it possible to form various kinds of concrete structure.This paper introduces a study on the structure of pneumatic conveying system of pneumatic shotcrete machine. While taking TK600 wet shotcrete as the sample machine, studying the pneumatic conveying system of pneumatic shotcrete machine in parts, adopting pneumatic conveying theory and numeral simulation methods for the analysis, and carrying out demonstration experiments, the author has accomplished optimization to three parts of the system, namely, the mixing bunker of air and aggregate, air distributing valve and reducing pipe. The detailed approaches are as follows:☆Analysis on the structure and feeding activity of the air-aggregate mixing bunker; site investigation to find out that four places (air intake of the bunker, both ends of the kidney slot-the feed inlets, the larger end of the reducing pipe) in the mixing bunker are most likely to accumulate materials; and working out the parts of and way the structure can be improved through analysis of the inner fluid situation in numeral simulation method; ☆Simulated computing of ventilation amount and flow field of the air distributing valves of different structures with the FLUENT software; selection of the optimist proposal;☆Computing and analysis of the lines of moving particles in the reducing pipe in accordance with the theory of particle movement analysis to find out the relation between the speed of particle and the length of pipe; particle trajectory simulated by the FLUENT software is adopted to demonstrate the feasibility of the proposal of lengthening the reducing pipe.With the above mentioned research and analysis and experiments as the support, the structural optimization objective is reached: the format and quality of material flow of the pneumatic conveying wet-mixed concrete are improved; the material accumulation problem in the air-aggregate mixing process is primarily solved. Accordingly, the performance of wet shotcrete machine is promoted, paving a solid foundation for further research in future.