The flow characteristics and pressure drop of gas-coal mixtures under high pressure and concentration through a Venturi with different structures

including diameter ratio(0.44

0.55

0.7)

convergence angle (2.5°

5°

9°)

diffuser angle (2.5°

8°

13°) and throat length (23d

43d

80d) were investigated in the dense phase pneumatic conveying of pulverized coal system. A similar trend but a varied degree in non-dimensional pressure distribution for the gas-coal mixture through different Venturis was observed. The most remarkable influence parameter was diameter ratio

which had the greatest influence on pressure drop. The increase in pressure drop of the Venturi and remarkable increase in pressure drop in the diffuser were observed with the decrease of diameter ratio. The major role of other structural parameters was to change pressure distribution inside the Venturi

while having little influences on total pressure drop. The greatest convergence pressure drop for the convergence angle series occurred in the 2.5°. There was little difference of convergence pressure drop between 5° and 9° under high pressure and concentration. The greatest throat pressure drop for the throat length series occurred in the 80d. The least diffuser pressure drop for the diffuser angle series occurred in the 8°. By introducing solids momentum flux

an empirical equation of pressure drop of gas-coal mixture through the Venturi was established. It showed good prediction with deviations from most experimental value within 30%.