The calculation of an internal energy balance in the smelting of calcium carbide
The calculation of an internal energy balance in the smelting of calcium carbide
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发表时间：
1995-09
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通讯作者：
G. W. Healy
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作者：
G. W. Healy
电石的冶炼一直受到喷发的困扰，经常造成严重的伤害或生命损失。为了找到原因，作者使用1992年的数据计算了CaC 2和CaO的内部能量平衡，并使用较旧的数据计算了其余项目。炉料的热含量和在还原温度下形成的热气的热含量表明，这些气体只能提供其热含量的一小部分。将焦炭和非导电固体的细混合物的电阻率的实验室数据外推到商业碳化物装料，然后用于计算由电流从电极表面流过混合物到炉膛所产生的热量，在有利条件下，该热量足以使装料达到1900 K和更高，在该温度下可以发生还原。必要的条件是足够的导电性和自由的罚款。当不满足这些条件时，部分CaO可能被还原成钙蒸气而不是CaC 2。在2350 K左右，这种钙气体可以上升并与混合物中的碳发生化学反应，在其中形成固体CaC 2，为其余的电荷提供丢失的能量。不幸的是，这种高钙气体如果在低孔隙率的炉料中没有遇到足够的碳，可能会吹出一条通向炉顶的通道，并在那里与空气或水分反应，导致爆炸;或者可能从打开的出铁口吹出，伤害出铁工人。因此，最大限度地减少混合物中罚款的旧规则仍然是确保安全和有利可图的操作的基本方法。
The smelting of calcium carbide has always been plagued by eruptions, too often with serious injury or loss of life. To find their causes, the author calculated an internal energy balance using 1992 data for CaC2 and CaO, and older data for the remaining items. The heat content of the charge, and that of the hot gases formed at the reduction temperature, showed that only a fraction of its heat content can be supplied by these gases. Laboratory data on the electrical resistivity of fine mixtures of coke and non-conductive solids were extrapolated to a commercial carbide charge, and then used to calculate the heat produced by current flowing through the mix from the electrode surface to the hearth, which, under favourable conditions, sufficed to bring the charge to 1900 K and higher, at which temperatures reduction could take place. Necessary conditions were adequate conductivity and freedom from fines. When these conditions are not met, a part if the CaO may be reduced to calcium vapour rather than CaC2. At around 2350 K, this calcium gas can rise and react exothermically with carbon in the mix to form solid CaC2 within it, supplying the missing energy to the rest of the charge. Unfortunately, this high-calcium gas, if it fails to encounter enough carbon in a charge of low porosity, may blow a channel to the furnace top and react there with air or moisture to cause explosions; or else can blow out of an opened taphole, injuring the tapping crew. So the old rule to minimize fines in the mix is still the essential way to ensure a safe and profitable operation.