ANALYSIS OF ENERGY MODELS IN PNEUMATIC TRANSPORTATION: a systematic review
Pneumatic conveying is widely used by various industrial segments. Its advantages include flexibility in transport routes, transport over long distances, reduction of pollutants, when compared to mechanical transport. Among its disadvantages, it is possible to highlight its high energy consumption due to the use of large amounts of compressed air. Studies to improve the efficiency of pneumatic transport systems are constantly carried out, but the lack of unified models indicates the need to analyze several models. Among these studies, studies that impact energy consumption, pressure drop and gas velocity stand out. A systematic literature review was carried out by collecting articles from three academic bases and grading them according to key words in order to obtain experimental equations predictive of velocity, pressure drop and the friction factor of solids. Experimental data were collected with a pneumatic transport system with a prototype solid feeder developed by Zeppelin Systems Latin America, called a pressurized Batchpump ejector. This prototype is similar to a small pressure vessel, for transporting material in 100L batches. The transport facility consisted of a 133m long, 3 inch diameter pipe, 5 90° bends and a 180° bend, all long radius, for transporting ground calcite limestone. The equations collected in the bibliography were compared, identifying what each author considered directly or inversely proportional, and it was identified that most of the equations converged in this regard, even with a change in the intensity of this influence, as they were experimental equations. The experimental coefficients of each solids friction equation were calculated and the inadequacy of using this solids friction factor as a constant was found, being necessary to use behavior prediction equation based on other variables, such as solids ratio and velocity. This change implied a reduction in the average error from 35% to 10%, which impacts on the prediction capacity of a transport system and consequently on the optimization of this system, with a greater possibility of working in points of greater energy efficiency.