A drop-tube furnace with a novel double-tube configuration was successfully developed to directly determine char yields during the pyrolysis of a wide range of solid fuels (mallee wood; mallee leaf; rice husk; biosolid; and subbituminous, bituminous, and anthracite coal) at a gas temperature of 1573 K. The char yield from pyrolysis of mallee wood and mallee leaf is <5%, ∼13% for rice husk, ∼16% for biosolid, ∼45% for subbituminous and bituminous coal, and ∼75% for anthracite coal. The retentions of Na, K, Mg, and Ca in biomass chars are <50%. About 35% of Na and K and ∼66–85% of P and refractory species in biosolid are retained in the char. In contrast, the retentions of major inorganic species in coal chars are >85%. This study shows using total ash as ash tracer results in 45–220% overestimation of char yields for biomass fuels and 13–27% for coals due to partial evaporation of ash. Similarly, selecting Na and K results in overestimation of biomass char yields by at least 2.5 times and selecting P leads to overestimation of biomass char yields by at least 80% because of substantial release of these species during pyrolysis. Similarly, selecting Mg, Ca, Al, Fe, Ti, or Si as tracer also results in inaccurate estimation of char yields due to partial release of these elements during pyrolysis. It is noted that for Si, which is often used as a tracer, the overestimation of char yields is 9–16% for coals but can be substantial (17–50%) for the case of biomass samples because of the substantial Si release during the pyrolysis of biomass (especially mallee wood with ∼32% of Si released). Clearly, for the solid fuels studied, no single element can be reliably used as tracer for calculating char yield during pyrolysis at high temperature. The new experimental method developed in this study fills this critical gap and enables direct determination of char yield during solid fuel pyrolysis in drop-tube furnace at high temperature.

中文翻译：

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直接测定滴管炉高温固体燃料热解过程中焦炭收率的新方法及其与灰示踪法的比较

成功开发出了具有新型双管结构的滴管炉，可直接测定各种固体燃料（大麦木材；槌叶；稻壳；生物固体；亚烟煤，烟煤和无烟煤）的热解过程中的焦炭收率。 ）在1573 K的气体温度下。木槌木和木槌叶热解的焦炭产率小于5％，稻壳为〜13％，生物固体为〜16％，次烟煤和烟煤为〜45％，〜75 ％为无烟煤。Na，K，Mg和Ca在生物质炭中的保留量<50％。炭中保留了约35％的Na和K以及约66-85％的P和耐火物质。相比之下，煤焦中主要无机物的保留率> 85％。这项研究表明，使用总灰分作为灰分示踪剂的结果是，由于灰分的部分蒸发，高估了生物燃料的焦炭产率45-220％，高估了煤焦炭产率13-27％。同样，选择Na和K会导致生物质炭产率高估至少2.5倍，而选择P会导致生物质炭产率高估至少80％，因为这些物种在热解过程中会大量释放。类似地，由于热解过程中这些元素的部分释放，选择Mg，Ca，Al，Fe，Ti或Si作为示踪剂也会导致碳收率估算不准确。请注意，对于通常用作示踪剂的Si，煤炭的焦炭产率高估了9–16％，但对于生物质样品而言可能很高（17–50％），因为生物质热解过程中会释放出大量的硅（尤其是木槌木，其中约32％的Si会释放出来） ）。显然，对于所研究的固体燃料，没有一种元素可以可靠地用作示踪剂来计算高温热解过程中的焦炭收率。在这项研究中开发的新实验方法填补了这一关键空白，并能够在滴管式炉中在高温下进行固体燃料热解期间直接确定焦炭收率。