The calculation reliability of pressure drop and gas-solid drag force in horizontal dilute phase pneumatic conveying strongly depends on the accuracy of gas-solid velocity correlation. However, there are limited studies on the solid velocity in horizontal dilute phase pneumatic conveying and it is important to further validate suitability of existing correlation of gas-solid velocity, especially for fine particles (such as pulverized coal). Consequently, in this paper, a negative pressure pneumatic conveying test rig is set up and two kinds of powders with different sizes are adopted. Optical fiber probe (OFP) was used to measure the volumetric solid concentration and particle velocity. The volumetric solid concentration was also calculated by using the measured particle velocity. The results show that the solid concentrations obtained by the two methods have good agreement, and discrepancy is within +/- 20%. It was found the particle velocities are different in the upper and lower part of the cross-section in the horizontal pipe. However, the difference is generally no more than 2 m/s. The velocity difference will decrease with the increasing gas velocity, and increases with the solid mass flow rate. In the experimental condition of 0.06 mm

Keywords:Horizontal pneumatic conveying;Horizontal pipe;Dilute phase;Particle velocity;Optical-fiber probe (OFP)