吸附剂对垃圾焚烧中重金属分布规律影响的热力学模拟研究

Effect of adsorbent on distribution of heavy metals in incineration of municipal solid waste:thermodynamic equilibrium analysis

通过吉布斯自由能最小热力学平衡法模拟研究了垃圾焚烧过程中重金属As,Cr,Cd和Pb的迁移和转化规律;考察了焚烧温度、空气过量系数、吸附剂(CaO,Al2O3和SiO2)的添加等主要焚烧工艺参数对重金属迁移和转化的影响。研究结果表明,焚烧温度对As,Cr,Cd和Pb的迁移转化有较大的影响,当温度高于800℃,重金属主要以CrAsO4,AsO(g),CrO2,CdO,CdCl2(g)和PbCl2(g)等形态存在。空气过量系数对重金属迁移转化影响较小。吸附剂的添加对重金属有一定的捕集作用。CaO的添加有利于降低As,Cr,Cd的挥发性;Al2O3的添加对As的捕集有很好的效果,但对Cr,Cd和Pb的挥发性影响较小;SiO2的添加对Pb的捕集有很好的效果,但对As,Cr和Cd的挥发性影响较小。

Incineration of municipal solid waste（MSW） can result in the reduction of waste volume and emission and the recycling of energy. The migration and transformation of heavy metals（As, Cr, Cd and Pb） during MSW incineration through thermodynamic equilibrium analysis is studied. The influence of incineration temperature, excess air ration and addition of adsorbent （CaO,A1203 and SiO2） on the migration and transformation of heavy metals were investigated. The results showed that heavy metals are affected by incineration temperature and excess air ratio distinctly. As the temperature increased from 800 ~C, these heavy metals is mainly present as CrAsO4, AsO （g）, CrO2, CdO, CdCl2（g） and PbC12（g）, respectively. The increase of excess air ration have little impact on the volatility of heavy metals. The heavy metals can be stabilized by the addition of adsorbent. The addition of CaO is beneficial for the stabilization of As, Cr and Cd. The addition of Al2O3 and SiO2 is beneficial for the stabilitation of As and Pb, respectively.