硫酸盐硫在化学链燃烧过程中的迁移转化规律

Migration and Transformation of Sulfate Sulfur During the Chemical Looping Combustion

以2种典型的模型化合物(CaSO 4和FeSO 4)为研究对象,研究采用Cu基载氧体时,煤中硫酸盐硫在化学链燃烧(CLC)过程中的迁移转化规律。热力学模拟研究发现,反应温度及载氧体过氧系数均会对模型化合物中硫的气-固相分布造成影响。在低温和低载氧体过氧系数条件下,CuO易被硫化生成Cu 2S。与FeSO 4相比,CaSO 4具有更高的耐温性。进而以担载在活性炭中的模型化合物为研究对象,在小型流化床反应器中开展了CLC实验研究。结果表明,在还原反应阶段和氧化反应阶段,SO 2均为主要的含硫气体。在还原反应阶段的前20.5 min内,FeSO 4和CaSO 4中硫转化为气相组分的摩尔分数分别为83.16%和50.09%。对还原反应阶段后载氧体的物相组成进行分析,发现有Cu 2S存在。对一次还原-氧化反应后载氧体表面元素进行分析发现,表面有部分硫累积及残留。

Two typical inorganic model compounds(CaSO 4 and FeSO 4)were selected to study the the migration and transformation law of sulfate sulfur in the CLC process of coal by using the Cu-based oxygen carrier.The thermodynamic simulation of the reduction process shows that the temperatures and the excess coefficient of oxygen carrier affect the distribution of sulfur.CuO is sulfurized to form Cu 2S,especially under the conditions of low temperatures and low oxygen carrier peroxide coefficient.Compared with FeSO 4,CaSO 4 has a higher thermal resistance.Further more,CLC experiments were carried out in a small fluidized bed reactor with model compounds loading on activated carbon.The results show that SO 2 is the main sulfur gas in both reduction and oxidation stages.In the reduction stage(20.5 min),the molar fractions of sulfur in FeSO 4 and CaSO 4 converted into sulfurous gases reach 83.16%and 50.09%,respectively.The existence of Cu 2S is confirmed in the oxygen carrier after the reduction stage.The energy-dispersive X-ray spectroscopy(EDX)analysis reveals the accumulation of sulfur after one reduction-oxidation reaction.