Basic theory of pneumatic conveying Flow state of fiber medium in pipeline
Understanding the flow state or conveying flow situation of fiber media in pipelines is a basic issue in pneumatic conveying. The actual flow state of fiber media in pipelines is very complex. According to the study of solid particle relaxation in the flow field, it can generally be divided into three basic flow states, namely straight flow, jump flow and spiral flow. In a vertical pipe, when the airflow speed reaches a certain level, the particles will float upward; in a horizontal pipe, if the force that causes the particles to float is equal to the force that causes them to settle, the particles will fly in a straight line. In some cases (more often in horizontal pipes), jumping leisure occurs due to the periodic changes in the force that makes the particles suspend and settle, and the friction between the particles and the pipe wall caused by the contact with the pipe wall from time to time. The rotation of the fiber when flowing in the pipe is due to the different flow velocities of each point in the flow field, which causes the different relative speeds of each point along the length of the fiber to generate torque and rotate. Due to the rotation of the fibers, there is a tendency for the fibers to align with the flow direction during leisure.
In the pneumatic conveying process of general horizontal pipelines in ginning plants, due to the small settling speed of fibers or cotton blocks, the jump break is not very obvious. When the pipeline is long and the flow rate is low, jumping leisure occurs. In the general pneumatic conveying process, an uneven dispersion flow is often found. The larger the cotton block, the closer this flow is to the bottom of the pipe. In vertical pipes, when the cotton flow passes through the elbow, a spiral break is found.
AAAWQ32RDRGFJ
