Spherical polymer pellets with a diameter of 1/8 in. and an SG of 0.96 are to be transported pneumatically using air at 808F. The pipeline is horizontal, 6 in. ID and 100 ft long, and discharges at...

Spherical polymer pellets with a diameter of 1/8 in. and an SG of 0.96 are to be transported pneumatically using air at 808F. The pipeline is horizontal, 6 in. ID and 100 ft long, and discharges at atmospheric pressure. It is desired to transport 15% by volume of solids, at a velocity that is 1 ft/s above the minimum deposit velocity.

(a) What is the pressure of the air that is required at the entrance to the pipe to overcome the friction loss in the pipe? (Note: An additional pressure gradient required to accelerate the particles after contacting with the air, but your answer should address only the friction loss.)

(b) If a section of this pipe is vertical, (1) what would the choking velocity be in this line and (2) what would the pressure gradient (in psi/ft) be at a velocity of 1 ft/s above the choking velocity?