成型炭化过程对磷酸-污泥-木屑成型炭性能的影响

以杉木屑和污泥为原料,磷酸为添加剂,探讨成型温度（70~100 ℃）、成型压力（80~110 MPa）和炭化温度（300~600 ℃）对磷酸-污泥-杉木屑成型炭物理性能和产率的影响,并对物理性能最佳的成型炭进行燃烧特性分析和重金属分析。结果表明,成型温度与成型压力对成型炭物理性能的影响相似,随着成型压力的增大和成型温度的升高成型炭物理性能均先升高后下降,炭化温度对成型炭物理性能影响较复杂。经80 ℃和100 MPa成型后再经500 ℃炭化制得的成型炭表观密度与抗压强度最大,分别为1279.0 kg/m³和18.7 MPa,均远高于商用烧烤炭。成型炭产率随炭化温度的升高而减小,由300 ℃的72.0%减至600 ℃的52.2%。较高的成型炭物理性能和产率可在一定程度上降低储存和运输成本,实现生物质废弃物的高效利用。

EFFECTS OF DENSIFICATION AND CARBONIZATION PROCESS ON PROPERTIES OF CHARCOAL PELLETS PREPARED FROM SAWDUST AND SLUDGE WITH H3PO4 AS ADDITIVES

Forest and agricultural wastes are typical biomass materials, but it is costly to be stored and transported because of its loose structure and low energy density which can be improved by biomass charcoal pellets preparation through densification and sequent carbonization. In the paper, charcoal pellets are prepared from Chinese fir sawdust and sewage sludge with phosphoric acid as additives. The effects of the densification and carbonization process on the physical properties （apparent density and compressive strength） and yield of the resulted charcoal pellets are investigated. Meanwhile, the combustion characteristics and the ecological risk of the resulted charcoal pellets with better physical properties were also investigated. The results show that the die temperature and densification pressure have a similar impact on the physical properties of the charcoal pellets which arise first and then decrease with the die temperature and densification pressure increasing, while carbonization temperature has a complex impact on the physical properties of the charcoal pellets. The charcoal pellets produced under the die temperature of 80 ℃, die pressure of 100 MPa and carbonization temperature of 500 ℃ have the highest apparent density （1279.0 kg/m³） and compressive strength （18.7 MPa）, far higher than those of commercial barbecue charcoal pellets. The yield of the charcoal pellet was negatively correlated with the carbonization temperature, decreasing from 72.0% at 300 ^oC to 57.2% at 600 ℃. The high physical properties and yield of charcoal pellet preparation can promote the effective and efficient utilization of biomass wastes to a certain extent.