| Serious environmental pollution has been caused because of the excessive discharge of sulfur dioxide for the past few years. In2011, the goverment implemented a new standard of air pollutants emission which’s more rigorous, and the recycling of the desulfurization by-products was required. The existing desulfurization technology has some shortcomings, such as the low desulfurization efficiency and the abandon of desulfurization product that causes the waste of sulphur resources. The desulfurization efficiency of wet flue gas desulfurization with organic amine technology is high, the absorber and the sulfur resources can be recycled, and it does not produce the secondary pollution such as waste water or waste residue, thus it is one of the development directions of flue gas desulfurization in the future.In order to find an efficient organic amine desulfurization system, this paper chose the suitable absorbent N-(2-hydroxyethyl) piperazine (HEP), adding sulfuric acid to constitute HEP/H2SO4desulfurization system, and studied the factors which can have influence on the SO2absorption and desorption process, recycling performance of the system, and the removing of thermal stability salt. The conclusions show that:(1) Among the five organic amines of diethanolamine, ethylene diamine, N-(2-hydroxyethyl) ethylenediamine, N-(2-hydroxyethyl) piperazine(HEP) and piperazine, the absorption capacity of SO2is33.32g/L, the desulfurization rate of HEP is near100%, the oxidation rate is0.78%, the first desorption rate is39.11%, the comprehensive performance of N-(2-hydroxyethyl) piperazine(HEP) is the best; When sulfuric acid is added to the HEP solution, the desulfurization rate can still stay at a high level, the first desorption rate significantly is increased to66.59%, recycling performance is improved;(2) The HEP/H2SO4desulfurization system has an excellent performance of SO2absorption and desorption, the desulfurization rate can be as high as99.97%, desorption rate can be higher than70%. Dealing with the simulated flue gas which has a0.05%～0.4%SO2content, the appropriate absorption conditions are:to deal with simulation flue gas in the scope of0.05%～0.4%of SO2concentration, initial pH is6-7, HEP concentration is0.3mol/L, the temperature is lower than50℃, the flow rate of flue gas is less than600mL/min, HEP/H2SO4solution can effectively purify SO2, SO2emission meet the standard; The appropriate SO2desorption conditions are:time is90min, the pH of rich amine liquid is4.5, temperature is90～95℃, the N2flow rate is600mL/min, the stirring speed is400r/min;(3) The HEP/H2SO4desulfurization system has a preferable recycling performance. The average desulfurization rate of eight continuous experimentis is higher than97.68%, the highest desorption rate is92.78%; With the cycle number increases, SO2absorption capacity reduced, the concentration of sulfuric acid root increased, parts of the thermal stability salt in absorbing liquid should be timely removed;(4) The thermal stability salt can be effectively removed by type D201resin. sulfate adsorption capacity is not affected by mixing speed and increases with the rising of temperature; when adding60mL wet resins to100mL absorb liquid at70℃, sulfate adsorption rate is87.38%; Eluting resin with4%NaOH solution, the elution rate of sulfuric acid can reach94.90%. |
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