中国南方典型农业生物质结渣特性实验研究

摘要

The combustion slagging characteristics experiments were carried out for bagasse, sugarcane leaf and rice straw, the typical agricultural biomass in Guangdong province. GB/T212-2001 and ASTM E1755 were adopted as standards to the ashing experiments respectively. Both pyramid method and one-step experimental method were carried out to measure the ash melting charateristics of the biomass. Ashing experiments results confirmed that the ASTM standard with low ashing temperature is more suitable for the biomass materials with high inorganic salt contents. The alkali metal oxide content in rice straw reached more than 20%, which is the main factor to cause ash melting and slagging. In the pyramid method, part of alkali metal and chlorine were transformed and precipitated in advance, so the test result was far higher than the actual combustion melting temperature. Compared with pyramid method, one-step method was more intuitive and instructional. And by one-step experimental, the critical slagging temperature of rice straw was at 700oC~750oC, bagasse at 850oC ~ 900oC, sugarcane leaves at 900oC ~ 950oC. Adding CaO and Al2O3 into the biomass material had a certain resistance effect on the slagging function. CaO can react with SiO2(s) to produce the high melting point solid Ca3Si2O7(s) and MgOCa3O3Si2O4(s), so able to consume the SiO2(s) around the biomass material and inhibiting the co-fusion in low temperature. While Al2O3 can generate high melting point solid KAlSiO4 and KAlSi2O6, slowing down the eutectic phenomenon in low temperature.%实验研究了广东省典型农业生物质稻杆、甘蔗渣/叶的燃烧结渣特性。采用GB/T212-2001和ASTM E1755标准进行灰化实验，采用角锥法和一步法检测生物质的熔融特性。实验结果证实 ASTM 的低温灰化标准更适合稻杆类高无机盐含量的生物质原料。稻杆中碱金属氧化物含量达20%以上，是导致灰渣粘结和熔融的主要因素。由于角锥法灰熔点检测法提前将部分碱金属和Cl元素转化和析出，导致检测结果远高于实际燃烧的熔融温度；相比而言，一步法更具有直观性和指导作用。通过一步法实验获得稻杆临界结渣温度为700℃~750℃，甘蔗渣为850℃~900℃，甘蔗叶为900℃~950℃。CaO和Al2O3添加剂对于生物质燃烧过程具有一定的抗结渣功能，CaO通过与SiO2(s)反应生成高熔点的固态Ca3Si2O7(s)和MgOCa3O3Si2O4(s)，因此能消耗物料周围的SiO2(s)，抑制低温共融；Al2O3则通过生成高熔点温度的固态KAlSiO4和固态KAlSi2O6，减少低温共熔现象的发生。