In Problem 9.4.1, if insulation were absent what minimum flow rate could be tolerated? Compare the HP requirements in both cases. Assume 15 psi pump suction pressure.

Problem 9.4.1

An 8 in. nominal diameter pipe is used to move heavy crude oil from a heated storage tank to a refinery 12 miles away. The inlet temperature is 180°F and the crude oil has the following characteristics:

If the outlet temperature cannot drop below 150°F, what minimum flow rate needs to be maintained in the pipeline? Use the MIT equation and 0.002 in. pipe roughness, 70°F soil temperature, 36 in. burial depth, and 0.25 in. insulation, with K=0.02 Btu/hr/ft/°F. The K value for soil=0.6 Btu/hr/ft/ °F. Pipeline pressures are limited to ANSI 600 rating (1440 psi).