摘要
目前常用于控制SO_3的吸收剂在脱除SO_3的同时也会脱除SO_2,导致吸收剂用量大、成本高。针对该问题,考察了NaHSO_3、Na_2SO_3等7种常用吸收剂对SO_3的脱除率和选择性,筛选出可以高效选择性脱除SO_3的吸收剂NaHSO_3,并研究了烟气工况对NaHSO_3脱除SO_3效率和选择性的影响。结果表明:吸收剂NaHSO_3在温度为300℃,空速为60000 h~(-1)的烟气工况下经过1 h的连续反应后,对SO_3的脱除率维持在86.2%左右,其选择性为100%;通过升高温度、增大空速和增加入口SO_3浓度等方式,相同时间内SO_3的累积脱除量均有所提高。用颗粒内扩散模型和Elovich动力学模型对不同烟气工况下的实验结果进行拟合,结果表明颗粒内扩散不是控制脱除过程的唯一因素,而化学吸附可能是NaHSO_3脱除SO_3的主要途径。
Since the current common absorbents for SO_3 controlling will also remove SO_2 while removing SO_3, which results in the large consumption of absorbents and high cost, therefore, in order to solve this problem, the removal efficiency and selectivity of SO_3 by seven absorbents including NaHSO_3, Na_2SO_3, etc., were investigated and NaHSO_3 was screened out as the optimal one. The effect of flue gas conditions on the removal efficiency and selectivity of SO_3 was also studied with NaHSO_3. The results showed that after a continuous reaction for 1 h under 300 ℃ at a space velocity of 60000 h~(-1), the SO_3 removal efficiency by NaHSO_3 maintained at about 86.2% with selectivity of 100%; moreover, with the increase of temperature, space velocity, and SO_3 concentration at entrance, the cumulative removal amount of SO_3 increased within the same time. The intra-particle diffusion model and the Elovich kinetic model were used to fit the experimental results under different flue gas conditions, and the results showed that intra-particle diffusion was not the only factor to control the removal process, while chemical adsorption might be the main way for NaHSO_3 to remove SO_3.
引文
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