| The circulating fluidized bed combustion is one of the most popularclean combustion technologies. So it is necessary for our country which isrich in deposits of coal to develop this technology. And the solid recycledevice is an important part of CFB boiler. Nowadays, loop seal has becomethe major solid recycle device in commercial boilers, but the stability ofthis device is a key factor restricting its development. Coking and reverseflow in loop seal are two extreme cases that make the device lose itsstability.Firstly, the author has made experiments to study the gas-solid flow inthe loop seal. This research is focus on the effect of hg(height of slitbetween the delivery room and loose room) on the running of loop seal,and delivers a reasonable range for hgdesign.After that, the author applies the Eulerian-Eulerian two-fluid modelto simulate the movement in a loop seal. According to the numericalsimulation, the air velocity (u1) has been increased from moving bedcondition to fluidized bed condition in the recycle chamber, and therelationships between Hspand u1have been found different in bothconditions. Combining the simuation with the results of the experimentmade by the author as well as another researcher, the author also proposesthat the relationships between Hspand u1vary from range to range of hgsize. In addition, the fluctuation of the bed level in standpipe whichobserved in experiment has been verified and explained by numericalsimulation, and the solutions to its disavantage have been proposed.Moreover, coking study has been analyzed thorough considering the velocity of solid in loop seal. Compared with the experiment result ofanother auther, the "dead zones" of flow have been pointed out, and theimprovements of the design and operation of loop seal have been proposedat last. |
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