Comparison of pressure drops through different bends in dense-phase pneumatic conveying system at high pressure

• Pressure drops of different location and radius bends are studied.
• Effect of particle size and material category on pressure drop of the bend is examined.
• Pressure drop model through the bend is derived.

In order to investigate the effect material property, bend geometry and location on pressure drop through the bend, experiments of dense-phase pneumatic conveying are carried out at conveying facility with the pressure up to 4.0 MPa. Petroleum coke and anthracite powders with different particle sizes are applied to examine flow characteristics. The empirical correlations of pressure drop through the bend are obtained using Barth’s additional pressure theory and multi-variable linear regression. Results show that pressure drop through vertical downward bend is the least, followed by pressure drop through horizontal bend, pressure drop through vertical upward bend is the largest. Powders with larger size need consume more energy than that with smaller size at the same solid loading ratio and conveying velocity as gas–solid mixture flows across the same radius bend. Flow characteristics of petroleum coke and anthracite are analyzed and compared. Pressure drop through the bend with the long radius is greater than that with the short radius. While to unit length, pressure drop of long radius bend is less than that of short radius bend. The empirical correlations of pressure drop through the bend are derived and predicted results agree well with the experimental results. The flow characteristics of the bend offer the theoretical support for design, control and operation of dense-phase pneumatic conveying at high pressure.