Dynamic Characteristics of a Pneumatic Conveying Pipe Line

Abstract

Measurement and control of the solid-gas mixture ratio in two phase flow were reported in the previous papers using a solid-gas two phase flowmeter1-25. However, dynamic characteristics of a pneumatic conveying pipe line could not be discussed because of large time-lags of primary means, manipulating device, etc. In this paper, therefore, pressure measuring elements having small time-lags are used and pressure changes are taken as photographs by use of a synchro-scope. Then, dynamic responses of pressure in a pneumatic conveying pipe line are discussed for a step change of flow rates of air and solids respectively. It is concluded that time-lags of the pressure responses can be neglected for change of air flow rate alone. There is a relation between pressure P and volumetric flow rate of air V as follows; where Z" and z* are impedances of a pipe line for air and solid flow respectively. The experiment shows that Z" is a constant irrespective of air flow rate, and that Zs is proportional to the hold-up of solids in a pipe line.