An arcuate multi-orifice distributor is designed and fixed in the front shell cover of a horizontal liquid-solid circulating fluidized bed heat exchanger to inhibit the particle deposition in the front shell cover and improve the particle distribution in the tube bundle. Polyformaldehyde (POM) particles and water are selected as the working mediums. The influence of the inclination angle of the distributor (-34-42 degrees) and the operating parameters such as the amount of added particles (0.5%-2.0%), circulation flow rate (7.9-19.9 m(3)/h), and particle diameter (3.15-5.5 mm) on the effect of the distributor is investigated by a charge-coupled device (CCD) system. The results show that the distributor can improve the particle distribution by 41%-90% at the optimal inclination angle of 27 degrees, with a small increment in pressure drop. The findings are beneficial to the application of the fluidized bed heat transfer technology to the heat exchanger with horizontal tube bundle. (C) 2020 Elsevier B.V. All rights reserved.