Abstract
Reported in the previous paper 2) are the measurement and control of solid-gas mixture ratio in two phase flow using a solid-gas two phase flowmeter. 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, a new measuring element for pressure was used and the pressure change was photographed by use of a synchroscope. Dynamic response of pressure in a pneumatic conveying pipe line was discussed for step change of flow rate of air and solids respectively. It was proved that time lags of the pressure response can be neglected for the change of air flow rate alone. There is a relation between pressure P and volumetric flow rate of air V as follows;
P=ZV2=(Za+ Zs) V2
where Za and Zs are impedances of pipe line for air flow and solid flow respectively. The experiment shows that Za is a constant irrespective of air flow rate and that Zs is proportional to the“hold up ”of solids in a pipe line. Therefore, dynamic characteristics of a pneumatic conveying pipe line can be represented by an electric circuit model which has a constant resistance Za and variable resistance Zs, where pressure and square of volumetric air flow rate are equivalent to electric voltage and electric current respectively.
