Flue gas desulfurization solution
1. Desulfurization technology for fluegas ejectedby liquid column
The desulfurization device for flue gasejected by liquid column is mainly composed of pulping system, reaction towersystem, product processing system, flue gas system, water system and controlsystem.
The undesulfured hot flue gas fromboiler induced-draft fan is sent to absorption tower after heat exchange offlue gas heat exchanger (GGH) and desulfurization at outlet of absorptiontower. During the ascending process and contact with desulfurizer andcirculating fluid in absorption tower, the SO2 in flue gas will have reactionwith desulfurizer and be removed through three-phase and effective blending andcontact with gas, liquid and solid. Under the effects of circulating pump, thecirculating fluid is sent to absorption tower through circulating pipeline andthe jet device (contact area) in the middle of absorption tower, ejected upwardfrom nozzle, scattered in upper part and then dropped to its circulating slotunder the effects of gravity. The mixers composed of lime powder (or lime),secondary products and water is sent to jet device from circulating slot of absorptiontower to have repeat circulation. The reaction tower has three working areas: thefirst part is washing and absorption area, where acid components like SO2 andSO3 are dissolved by water in slurry, SO2 will react with water to generateHSO3- and then have efficient reaction withlimestone slurry (or lime) to reach high desulfurization efficiency. The secondpart is circulating slot of absorption tower, where HSO3-can be oxidized to HSO4- andsulfite can be oxidized to sulfate by adding oxygen and mixing. The circulatingslot of absorption tower has many complex chemical processes includingdissolution of limestone (or lime), oxidation of sulfurous acid root andcrystallization of sulfate. The stay time, PH value and concentration of slurryin circulating slot of absorption tower are important parameters for forminghigh-quality gypsum crystals. The gypsum slurry extracted from absorption toweris sent to gypsum dehydration system. The third part is flue gas demist areaand two layers of high-efficiency demisters are installed at upper part ofabsorption tower to ensure safety operation and flue gas temperature of fluegas heat exchanger. The desulfurated cold flue gas at outlet of absorptiontower and undesulfured hot flue gas at inlet of absorption tower are dischargedafter heat exchange through flue gas exchanger (GGH).
2. Flue gas desulfurization technologyof circulating fluidized bed
The hot flue gas from boiler is sent tocirculating fluidized bed reaction tower through spray pipe at its bottom. TheCaO raw materials are prepared to qualified slurry with certain concentrationand particle size through pulping system, sent to desulfurization reactionsystem through efficient atomizing nozzle; the slurry drops will have efficientfluidization contact and mass transfer with flue gas and then become soluble inwater to generate HSO3-or SO32- to have fast chemical reaction withCa(OH)2 which is soluble in water and this process is called liquid phase masstransfer. In the meantime, the solid ashes with low water content will beformed by evaporation of water. The water atomization nozzle is vertically seton reaction tower to humidify the dry particles in flue gas and improve thereaction speed in desulfurization. Most of particles carried by flue gas arerecycled after passing dedusting and returning to tower. The flue gasdesulphurization technology is mainly composed of desulfurization reactiontower system, desulfurization, storage, preparation and supplying system, dustremover of desulfurization reaction tower and the material conveying system,water supplying system, compressed air and control system in collecting ash.