Studies on Grain-Straw Separation by Air Stream for Combine

本文设计了一种新型的气流分离系统。它可以替代传统的秸秆架和联合收割机。首先对秸秆架的分离特性进行了实验研究。为了研究吹气分离的特性，在间歇式分离系统上进行了基础实验。得到了实际系统的基本设计参数。随后，开发了原型分离系统，并对该系统的可行性进行了讨论。所得结果总结如下：在秸秆架中，当秸秆被输送到机器的后端时，谷物从谷物-秸秆混合物中分离出来。虽然需要一定数量的秸秆才能顺利输送，但随着秸秆用量的增加，分离效果越来越差。秸秆架的曲柄运动可以加速秸秆的分离，但同时也会使秸秆层凝结，从而干扰秸秆的分离。结果表明，在秸秆进料量为2700 ~ 5400kg /h时，秸秆架的分离率为92.8 ~ 97.3%。所开发的分离系统通过将筛网输送机输送的混合料层提升和松动来加速分离。不使用振动机构。在接近实际的物质条件下，可以获得可靠的分离率。筛网输送机入口和末端的自由落体也能有效提高分选率。在双级实用系统上进行了试验，在秸秆进给量为3600 kg/h时，分离率可达96%以上。

In this studies, a new separation system using air stream was devised. It could alternate a conventional straw rack of combine. In the beginning, separation characteristics of straw rack were clarified experimentally. In order to investigate the characteristics of separation by blown up air, basic experiments were conducted by a batch separation system. The basic design parameters for a practical system were obtained. Subsequently, the prototype separation system was developed, and the feasibility of this system was discussed. The summary of results obtained were as follows;In a straw rack, as straws are conveying to the rear end of machine, grains are separated from the grain-straw mixtures. Although a certain amount of straw was required for smooth conveyance, the separation performance became worse as straw amount increased. A crank motion of straw rack could accelerate the separation, but at the same time also might interfere with separation by condensing the straw layer. It was showed that the separation rate of the straw rack was 92.8 - 97.3% at straw feed rate of 2,700 - 5,400kg/h.The developed separation system accelerate the separation by lifting up and loosening the mixture layer which is conveyed by screen conveyer. No vibrating mechanism is used. In near-practical material conditions, reliable separation rate could be obtained. Free-falls at the entrance and the end of screen conveyer were also effective to increase the separation rate. In a trial on the double stage practical system, the separation rate was expected more than 96% at straw feed rate of 3,600kg/h.