Experimental Study On Activity Of Calcium-Based Desulfurizer And Properties Of Slurry Preparation

At present, Flue gas desulfurization (FGD) is the most efficient and important technology to control acid rain and SO2 pollution. FGD can be classified as wet, semi-dry and dry methods. Calcium-based desulfurizer is the most extensive desulfurizer in application. The activity of desulfurizer and its flow behavior will affect the performance of the desulfurization efficiency and the cost of desulfurization equipments directly.A quicklime hydration experimental bench was established and equipments such as rotary viscometer and scanning electron microscope and so on were used to study the influences of operating parameters and different additives on quicklime hydration, the flow behavior of slurry and desulfurizer's structural properties. The influences of Ca(OH)2 slurry pulping processes on the flow behavior were also discussed.In the study of quicklime hydration processes, it mainly studied the influences of operating parameters including agitation intensity(200-800r/min), particle diameter(0.13-1.5mm), initial temperature of hydrating-water (20~60℃), mH2O/mCaO ratio(3~6) and stacking time (0~6 days) on quicklime hydration,the flow behavior of slurry and desulfurizer's structural properties. The best operating parameters of producing desulfurizer with highest activity in the corresponding experimental condition were: agitation intensity 600r/min, initial temperature of hydrating-water 40~50℃, H2O/CaO ratio 4~5, the smaller the particles were, the better they were for quicklime hydrating, and quicklime should be used immediately after smashing. Under the above conditions, quicklime hydrating process was faster with higher conversion rate, the particle diameter of desulfurizer was smaller, the specific surface area and the porosity of desulfurizer were bigger, and the viscosity of slurry was higher.Quicklime hydration process with different additives (MgO, SiO2, NaCl, Ca3(PO4)2,CaSO4 and other additives) under different amount of addition(1%, 2% and 4%) were also studied. It was mainly about the influence on quicklime hydration process,the flow behavior of slurry and desulfurizer's structural properties. Compared with those obtained without additives, the results showed that under the conditions(SiO2 4%, NaCl and Ca3(PO4)2 about 1%) quicklime hydration process was faster with higher conversion rate and the particle diameter of desulfurizer was smaller, the specific surface area and the porosity of the desulfurizer were bigger, the viscosity of slurry was higher. On the country, when MgO or CaSO4 was added, it was found that the quicklime hydration process and conversion rate were slower, and the particle diameter of desulfurizer was bigger, meanwhile, the specific surface area and the porosity of the desulfurizer were smaller. So they were inappropriate to add.The influence of Ca(OH)2 slurry concentration, water temperature, stacking time and additives on the viscosity of Ca(OH)2 slurry were tested. The smaller the concentration of Ca(OH)2 slurry was, the lower viscosity of Ca(OH)2 slurry would be; Along with the increasing of water temperature, the viscosity of Ca(OH)2 slurry became lower; and CaSO4 could reduce the viscosity of Ca(OH)2 slurry; With a dose of NaCl or Ca3(PO4)2 added at about 1%, the viscosity of Ca(OH)2 slurry became the lowest.There were great impacts on sorbent performance when operating parameters and addition agents were changed during the period of quicklime hydrating and preparation of Ca(OH)2 slurry. We can improve the desulfurization efficiency effectively and reduce operational cost based on these operating parameters and additives research and optimization.