Author:
Q.K. Tran
International Committee for Study of Bauxite, Alumina & Aluminium, Zhengzhou, China, November 2010
Abstract
Upflow design of digestion flash vessels, with deflection of the incoming flow onto a controlled slurry level, allows the factors affecting three-phase flow to be managed more effectively when compared to downflow design. Upflow design results in lower rates of scale formation on vessel walls, and lower rates of particulate carry-over in the vapour. Downflow design is simpler from a fluid mechanics point of view, and the need for little or no control, makes it operationally attractive. This benefit however does not necessarily translate to lower capital and operating costs. Downflow designs are more capital intensive as they experience higher rates of wear on vessel walls and interconnecting piping.
