| Semi-dry flue gas desulfurization technology has a wide prospect of development and application which has the following characteristics:simple techniques, low investment, small floor space, low operation cost, and so on. MCFBA technology is a kind of semi-dry FGD that is based on circulating fluidized bed technology. The gas-solid contact condition has a significant effect on the desufurisation efficiency and it is intimately related with the solid concentration distribution in the CFB reactor. To understand the rule of solid concentration distribution in the reactor, we built a3-dimension and2-dimension experimental setup according to the three dimensionless groups for practicable similarity of CFBs. The rule of solid particle concentration distribution on the radial and lateral dimension in the reactor has been studied by using optical fibre probe and high-speed photography. It is also been studied that the effect of internal components on the solid concentration distribution. We have put forward an effective scheme on the installation of internal components.The results showed that the flow structure in the reactor is an annular-core flow field with the solid concentration near the wall being dense and the one in the center of reactor being thin. The solid concentration ε3near the wall is8times of that in the centre region which is only0.002. The solid concentration near the wall decreases heavily making the curve steep, while the concentration in the centre region is very low and stay at a same level. On the lateral direction, the solid concentration distribution has a trend of dense upward region and loose in the low region. The dense region with highest solid concentration is the junction of riser and venturi tube. Under the same operating condition, the uniformity of solid concentration distribution on the radial direction decrease with the height of riser decreasing.The effect of internal components on solid particle concentration distribution has been studied. It is found that the solid concentration increase with the increasing of external solids flux Gs or the decreasing of superficial velocity Uo. The local solid concentration in any profile will increase and the same as the average cross-sectional solid concentration.It is effective to get a more uniform distribution of solids concentration in the riser with installing internals. Under the height installed internal, there will be a more uniform distribution in the radial direction, i.e. decreased solids concentration close to the wall and increased solids concentration in the centre area. Also the ring-shape internals will make average cross-sectional solids concentration in the region above the internal more dense, it will be helpful to enhance the desulfurization efficiency. To improve the desulfurization efficiency of the reactor, we put forward a scheme of installing internal components with the ring-shape internal components being installed at the height of h/H=0.2and h/H=0.28. This will raise the position of dense-phase zone in the reactor and it will maximize the humidify effect of the first-rate nozzle. This will also improve the radial distribution uniformity of solid particles in the reactor.The results of this thesis provide an instruction for the design of MCFBA and the optimization by installing internal components. |
PDF Full Text Request