ASSESSMENT OF THE PNEUMATIC SEPARATION QUALITY IN THE PROCESS OF GRAIN MULTILAYER FEEDING

The design of a pneumatic separator with the feeding device for grain multilayer feeding was suggested in this paper. The application of the device enables increasing the uniformity of the airflow field velocity and the quality separation indicators. In order to determine the impact of grain multilayer feeding on the quality of grain cleaning we conducted a quantitative distribution of light grain impurities in the operating separation area. As a result, a statistical model of the probability of light impurities passing through the grain layers in the process of grain multilayer feeding in pneumatic and separating channel was obtained and the influence of specific load on the quality of grain cleaning was analytically determined. РЕЗЮМЕ Запропоновано конструкцію пневмосепаратора з живильним пристроєм для багаторівневого введення зернового матеріалу, використання якого дозволяє підвищити рівномірність поля швидкостей повітряного потоку та якісні показники сепарації. З метою визначення впливу багаторівневого введення зернового матеріалу на якість очищення зерна проведено кількісний розподіл легких домішок в робочій зоні сепарації. В результаті отримано статистичну модель ймовірності проходження легких домішок через зернові шари при багаторівневому введенні зернового матеріалу в пневмосепаруючому каналі та аналітично визначено вплив питомого навантаження на якість очищення зерна. INTRODUCTION Today Ukraine is one of the leading countries in the production of grain and one of the three world exporters of grain crops (Materynska O.A., 2013). That requires introducing new production technologies that can provide high performance of grain cleaning and its compliance with the standards of cleanliness and humidity (Grabar I.G., 2013). The required quality of food grain can be achieved only through the effective and timely grain cleaning from impurities which substantially affect the terms of storage and selling conditions. In this case the pneumatic separation is very important. It separates a significant amount of impurities at various stages of grain cleaning (Vasylkovskyi M.I., 2006). Air separation is one of the most common ways of grain cleaning. This process is versatile due to the separation of any material – from the smallest grain (alfalfa, poppy, etc) to the largest (corn, beans) and can partially reduce its moisture content and minimize damage (Dryncha V.M., 2006). However, the efficiency of the air flow depends on many factors: the size of specific grain load, aerodynamic properties of the components, airflow velocity, geometrical parameters of the pneumatic separating channel and others. (Kroulík M., 2016, LukaszukJ., 2008). But, despite the widespread application and versatility of pneumatic separation, the efficiency of the air flow is significantly reduced due to uneven grain location in the operating separation area. The increase of grain specific feeding causes the increase of aerodynamic resistance in the area of grain input and output, which in its turn increases the uneven airflow velocity in the cross section of the pneumatic separating channel (KovrikovI.T., 2003, Burkov A.I., 2000). The increase of evenness of the air flow velocity field can be achieved by using the feeding devices of the pneumatic separating channels (Saitov A.V., 2015). This improves interaction of the grain components and the air flow, thereby increasing the quality of separation, which improves the efficiency of the air flow and the quality of grain cleaning (Panasiewicz M., 2008, Leshchenko S.M., 2008). Vol. 53, No. 3 /2017 66 Despite a large number of works on theoretical research of the pneumatic separation quality (Hamuev V.G., 2016, Leshchenko S.M., 2012), the problem of quality indicators analytic assessment is very important and requires a detailed analysis of the process especially in the conditions of grain contact interaction in the operating separation area. So, the research is to study the impact of grain interaction on pneumatic separation quality indicators while applying feeding devices. That will improve the air flow efficiency and reduce the power consumption for grain cleaning. MATERIAL AND METHOD The analysis of feeding devices operation led to the conclusion that the main disadvantage of active feeders used in the pneumatic grain cleaning machines is the additional energy, thereby increasing the power consumption and complexity of the pneumatic separating channel design. Therefore, among all types of feeders the gravity feeders are widely used due to their simplicity of design and reliability. These feeders are used in grain cleaning machines and some feeders became the result of scientific research (Baldanov V.B., 2015, LevdanskyiE.Yu., 2012, Doshi J.S., 2013). On the basis of the research analysis of pneumatic separation and of feeding devices designs, the Department of Agricultural Engineering of the Central Ukrainian National Technical University designed and manufactured a prototype of a new pneumatic separator with the feeding device for grain multilayer feeding (Patent of Ukraine No8058A, 2005) (Fig. 1). The design of the pneumatic separator ensures even distribution of grain material in the operating separation area and significantly reduces air flow resistance in the input and output zones and makes velocity field uniform (Nesterenko O.V., 2015).