An experimental study on the operation properties of a loop seal

摘要

Loop seal as a type of recycle device has been extensively used in circulating fluidized bed boilers for helping solids transfer from a low pressure region to a high pressure region and serving as a pressure seal. It is one of the most importantcomponents for the stable and reliable operation of circulating fluidized bed boilers. Despite its widespread use, its properties have not yet been well understood. This valve has only limited ability of solids flow control in comparison with controllable non-mechanical valves such as L-valve and J-valve. In order to solve the problems with regards to regulation and control, the operation properties of the loop seal used in this work, which is comprised of two chambers divided by a partition plate with an opening, two air boxes and side aeration nozzles, have been intensively studied on a cold circulating fluidized bed model and the effect of the fluidizing air rate, side aeration rate, the height of aperture between two chambers and the geometry of exit on solids flow rate were examined. The experimental results show that the height of aperture and the shape, size and height of the exit have a strong influence onsolids flow rate and operation stability of the loop seal. The side aeration air can help solids transport from the recycle device to the fluidized bed and the solids flow rate may be modulated by adjusting the side aeration rate.