Abstract
To investigate the pneumatic conveying characteristics at high solid-gas loading ratios and high conveying pressures, the floating velocity of a polyester chip was measured at a pressure not exceeding 300kPa(gage). Pneumatic conveying experiments were carried out on a nearly practical scale within solid-gas loading ratios <45 and conveying pressures <214kPa(gage).
The floating velocity wf decreases gradually with the increase of pressure in the pipe, and at 300kPa(gage) falls to 50% of the value at atmospheric pressure. Pressure drop ratio α is proportional to the factor μ/Fr*Frwf, which consists of loading ratio μ, Froude number Fr* and Frwf, up to μ=40 as shown by Owen. The relationship between Froude number Fr* and the friction factor λk is nearly represented by the equation obtained by Morikawa et al. independent of the solid-gas loading ratio and pressure in the pipe. The solid-gas loading ratio μc at the choking limit increases exponentially to 45 independent of pipe inner diameter.
