Study On Injection Simulation And System Design Of Mercury Removal With Magnetospheres Sorbent In 50mw Coal-fired Unit

Mercury pollution is becoming more and more serious in China.Coal combustion is one of important sources of mercury in the atmosphere.At present,there is still no mature and better economic technology of mercury removal in China.There are a large number of disadvantages about existing mercury removal technology,such as high operating cost,cannot be recycled and so on.Based on the new idea of removing elemental mercury from flue gas by magnetospheres in coal fly ash,ejectors were designed,the diffusion of magnetospheres in flue were simulated,the distribution law of mercury in power plant was analyzed,and a mercury removal system with magnetospheres for coal-fired power plant 50 mw unit was designed and developed in this paper.First of all,the mathematical models,boundary conditions and geometric models of CFD numerical simulation are introduced in this paper.The simulation of the diffusion of magnetic beads in the flue mainly involves the mass conservation equation,momentum conservation equation,energy conservation equation,turbulence model,mass transport model and discrete phase model,and boundary conditions were set rightly.In order to compare the particle diffusion effect of injection device systematically,31 kinds of arrangements were simulated in this paper.When ejector with the baffle is adopted to inject particles,diffusion situation of the two or three nozzles are the best that the particle coverage of at least three sections reaches more than 80%,the pressure drop was 38.5 Pa and 54.3 Pa,respectively,and the residence time was about 2.0s.When the pipe with the multinozzles is used,the coverage of at least four sections of 3×4、4×4、4×5、4×6 is more than 70%,and the coverage rate of at least three sections of 4 × 6 is more than 81%.The particle residence time is about 2.0s.The pressure drop increases with the increase of nozzle number,and the maximum pressure drop is 15.45 pa,18.61 pa,respectively.When there are the same nozzles in every pipe,the pressure drop increases as the number of the pipes increases.Finally,based on 50 mw coal-fired power plant,this paper mainly studies the scheme design of mercury removal technology with magnetospheres sorbent.The distribution of mercury in coal-fired power plants is the basis of the entire technical scheme.Most of the mercury(96.71%)in the flue gas is absorbed with the fly ash,and the rest of mercury goes into the atmosphere.The largest mercury input and output production are coal and fly ash,which the ratio of both are above 98%.Mercury removal technology with magnetospheres sorbent contains main parts: the water pipeline;the materiel pipeline and the gas pipeline.For 50 MW power plant,the injection amount of magnetospheres sorbent is 230 kg / h,the fly ash treatment capacity of the field magnetospheres separation system is 10 t / h,and the single tank treatment capacity of magnetospheres impregnation equipment by chemical reagent is 250 kg/h.