Experimental Study On New Type Semi-dry FGD Applied To Industrial Boilers

The semi-dry flue gas desulphurization technologies has advantages of low investment,high adaptability, less watetr consumption, simple equipment and unit transformationconvenient and so on,which is the one of main technologies in flue gas desulfurization.But thelow of desulfurization efficiency and desulfurization agent utilization rate is the genenralproblem for SDFGD. In order to enhance desulfurization efficiencyand desulfurization agentutilization rate, This article has presented a new type of semi-dry used in flue gasdesulfurization apply to low sulphur coal industrial boiler, and tries to build up experimentalplatform. By researching macro parameter, different desulphurizers,additive and differentslurry-supply have effect on semi-dry flue gas desulphurization efficiency, desulfurizationagent utilization rate and temperature distribution in the tower, including Ca/S, amount of fluegas, gas-liquid mass ratio, lime slurry concentration and different slurry-supply, the essayanalyzes the theory of hygroscopic additive has effect on desulfurization.We researched macro parameter effects on desulfurization efficiency in the hot testbench,it came to conclusion that desulfurization efficiency with Ca/S was almost straight up,Ca/S was less than1.2, when Ca/S was bigger than1.2, desulfurization efficiency was notaffected. Amount of flue gas had no effect on desulfurization efficiency,when lime slurryconcentration increases, desulfurization efficiency decreases, in other words, when the waterof spraying quantity increases, desulfurization efficiency would increase.It comes to conclusion by researching spray dry desulfurization process that: Thetemperature dorp and SO₂removal mainly occurs Near the nozzle for single double spraysystem; Two-stage spray system optimize the desulfurization tower space, when first andsecond stage nozzle slurry-supply content is60%and40%,the desulfurization efficiency oftwo-stage spray system increased by15.2%than than single stage spray system, and morethan68%the total temperature drop and accumulative total SO₂removal occur near heprimary nozzle atomization area;The desulfurization efficiency increase with gas liquid ratioenlargement within the certain scope, when the gas liquid ratio is0.1,slurry atomization isinadequate, and when gas liquid ratio is0.5the desulfurization efficiency have to decline.By the double alkali absorption agent research get: desulfurization efficiency increasewith Na/S for pure NaOH absorber,when Na/S is3desulfurization efficiency get91%; The effect of Into position of NaOH or Ca（OH）₂on the desulfurization efficiency was found to bemoderate.By researching additive NaOH and NaCl has effect on desulfurization efficiency，desulfurizing process，temperature distribution in the tower and SO₂removal share，it comesto conclusion that: when the volume of additive is less than0.8g/L, desulfurizationefficiency will straights up when volume of additive increases, when bigger than0.8g/L,when volume of additive increases, desulfurization efficiency doesn’t improve, and whenvolume of additive is0.8g/L, desulfurization efficiency will increase to13.7%and6.5%，additive can delay the evaporation of lime slurry droplet, increase evaporation height，andadditive NaOH make delay stronger.Through theoretical analysis of additive delay evaporation of lime slurry droplet，we cancome to conclusion that NaOH and NaCl can reduce water vapor partial pressure of slurrydroplet surface，and NaOH reduces greatly, water vapor partial pressure of slurry dropletsurface is inversely proportional to Lime dropletsize.By comparing desulfurization agent not utilization of several typical experimentcondition, we can see that optimization of tower and use of additive will enhancedesulfurization efficiency.The essay designed SDFGD of double alkali absorption agent and control project for2×75t/h circulating fluidized bed boiler of XinZhou clean power plant,Shanxi Province,andcalculates equipment of this project.