Air and Power Requirements for the Pneumatic Transport of Crushed Coal in Vertical Pipelines

Abstract

Empirical equations were developed giving minimum air and power requirements for the vacuum and pressure transport of crushed coal through vertical pipelines. Data used in the development were obtained from transport tests in a 50-ft vertical 6-in.-dia pipeline and in a system of 2-, 4-, 6-, and 8-in.-dia horizontal pipelines, each preceded by a short vertical run. The air and power requirements are dependent upon coal rate and specific gravity, upon pipe diameter and length, and upon the ratio of cross-sectional area of the coal pickup section to the pipe. Coal size was not a variable, but the largest lumps could not exceed four-tenths of the pipe diameter. The highest throughput achieved in the 50-ft vertical pipeline was 27 tons per hr of 2-1/2- by 0-in. coal rejects of 2.9 specific gravity. In this experiment with a pickup-to-pipe area ratio of 4.6 to 1, about 1750 actual cu ft per min of air was required at the pipeline entrance to keep the coal moving without floating, and the pressure drop across the pipeline was 2.5 psi. Extrapolation of the equations can be used for designing larger and higher capacity vertical pipeline systems. For example, assuming a pressure drop of 20 psi and a pickup-to-pipe area ratio of 3 to 1, extrapolation indicates 65 tons per hour of 5- by 0-in. coal (sp. gr. 1.40) could be transported through 1000 ft of vertical 12-in.-dia pipe by 7300 actual cu ft of air per min (17,200 standard cu ft per min) at the pipeline entrance at the expense of 1080 theoretical horsepower.