Heat transfer and energy loss in bitumen batching system of asphalt mixing plant

Abstract

Bitumen should always be stored and handled at the lowest temperature possible, consistent with efficient use. At higher temperatures and lower viscosities pumping is optimized; whereas at lower temperatures and higher viscosities pumping efficiency decreases rapidly. Thus viscosity and its control by temperature is an important consideration in respect to all handling operations. The minimization of bituminous hardening during storing, transportation and mixing depends on careful control of binder temperature. TRA ASFALTAS 08 regulates maximum permitted storage temperatures of various bitumens. Heating equipment of periodical asphalt mixing plant (AMP) bitumen batching system (BBS) shall be designed to maintain the same temperature of the binder in the whole BBS. This article presents the study of heat transfer in bitumen storage tanks and identifies the most important factors influencing on energy loss. The test showed that energy loss in currently operated AMP is too high and may be reduced by changing technological parameters of bitumen heating, updating and upgrading separate heating equipment and improving temperature control and handling of heating equipment. The method of convection and radiation heat flow calculation in bitumen storage tank is presented. The findings obtained through the use of the described method of heat flow calculation correspond to the actual data of the consumed electrical power displayed on AMP computer.