在高温使用中，如何对耐火材料进行系统保护(二)
冶金和其他工业部门的热工设备，只有连续自动控制耐火材料内衬的状态和具有耐火材料的系统保护，才能使设备可靠地运转。除了上篇对内衬进行冷却外，以下几个方面也需要重点关注：
耐火材料内衬的喷补
在许多场合，喷补能明显提高内衬寿命。发展喷补（覆盖物）能够计算内衬用新泥料（按模型）浇灌没有破坏的用过部分。节省原材料。
降低侵蚀物的侵蚀性
这是耐火材料的保护的新方向。耐火材料使用破坏的侵蚀因素之一是渣。渣与耐火材料接触时间越长，内衬被破坏得越大。试验表明钢包内衬损毁与包中渣层厚度实际上有直线关系。因此，同一种耐火材料的包衬，用放渣方法使渣减少，使包衬寿命可以提高2~3倍。钢包中的渣层，用各种填料（次石墨，多孔烧结黏土，蛭石和其他材料）覆盖的方法也可以使渣的侵蚀性减小。
在这种场合，钢包渣不是首先与耐火材料内衬起反应，而是与填充的材料——中和剂起反应。
渣与耐火材料相互作用的动力学阶段，侵蚀性减小的理论前提是渣中实行硅，铝，铁等络合物状，用阳离子方法减少渣成分中游离O2-份额。在这种场合，形成复杂的阴离子AlxO2-y，SixO2-y，FexO2-y约束游离氧，减小渣的侵蚀性。发生渣熔体中和。例如，熔体中实行铁橄榄石成分，氧化铝在熔体中明显增加AlO3-数量，而减少游离氧的份额。
中和剂的另一方面作用是，它对侵蚀物黏度的影响。例如，氧化钙-硅酸盐渣中引入 CaO大于30%或 MgO20%或Cr2O37%能使渣的黏度提高到1Pa·s，造成耐火材料溶解减少得多。于是，氧化钙-硅酸盐渣中加入20%中和剂；1600℃时，黏土耐火材料的溶解强度为0.2mg/(cm2·s)，而原来渣为2.6mg/(cm2·s)。
规定温度和气体制度定额
炼钢生产的温度和供氧，这些重要的增强剂值，归根到底取决于经济计算。这些数据的最合适值带有折中性质。
保护耐火材料的措施有各种方法，循环作业性质的热工设备内衬要保持温度固定。例如钢包，转炉等，在装满之间的间歇要关上盖，如果更长时间间断，由专用燃烧器加温。
合理的耐火材料砌体结构
大体上与必须提高内衬的抗热震性有关系，因为传统的办法是对单个制品抗热震性的提高，往往不保证砌体的抗热震性。砌体中耐火材料的保护是用各种方法解决防止由于机械应力的破坏。
当一面热流固定时，按墙壁厚度温度梯度的线条法，内衬中产生的拉长热应力减小有效。线条温度梯度也许是通过造成可变气孔率结构的途径实现。
热应力可以减小，还靠热流方向中耐火材料内衬厚度精减。可是内衬厚度的变化，并不始终保证应力减小。此外，还造成热损失增大。如果没有渣的作用，合理的是用一种材料，按厚度选择相当的外形，由几层构成耐火材料墙壁结构。在固定的温度制度条件下，在多层的薄片中，热面为1400℃的指标，计算温度和应力分布。为了保证板片整体的抗热震性，必须用层厚度等于8mm，1.3mm和4mm 3层代替它。
借助于材料和砖缝厚度的选择，能做到实质性地减少砌体应力。提高耐火材料寿命的可能性较大，不仅在于改善砌体的结构，而且又有单个制品形状和尺寸的合理化。例如，用有效的方法减少镁质耐火材料在使用条件下剥落的趋向，当时制品一面的温度不变，而对面的明显变化，在个别片段，制品热面适当锯开深小于 10mm。
从应力分布均匀的观点，六面形状的制品与四面的比较，是更可取的，六面棱柱状制品在钢铁冶金设备中应该得到广泛应用。制造五面铁皮密不透风的不烧焦油镁白云石制品是合理的，还能举出许多类似的例子。
How to systematically protect refractory materials in high temperature use (2)
For thermal equipment in metallurgical and other industrial sectors, only continuous automatic control of the status of refractory lining and system protection with refractory materials can make the equipment operate reliably. In addition to cooling the lining in the previous part, the following aspects also need to be focused on:
2 The spraying of refractory lining
In many cases, spraying can significantly improve the lining life. The development of spray (mulch) can calculate the used part of the inner liner that has not been damaged by pouring new mud (as per model). Save raw materials.
3.Educe the erosion of the erosion
This is the new direction of refractory protection. Slag is one of the corrosive factors of refractory failure. The longer the contact time between slag and refractory material, the greater the damage to the lining. The results show that there is a linear relationship between the damage of ladle lining and the thickness of slag layer in ladle. Therefore, the lining of the same refractory material is reduced by slagging method, so that the lining life can be increased by 2 to 3 times. The slag layer in the ladle, covered with various fillers (secondary graphite, porous sintered clay, vermiculite and other materials) can also reduce the erosion of the slag.
In this case, the ladle slag does not react first with the refractory lining, but with the filling material – the neutralizer.
In the dynamic stage of the interaction between slag and refractory, the theoretical premise of the erosion reduction is to implement the complex form of silicon, aluminum and iron in the slag, and reduce the free O2- share in the slag composition by cationic method. In this case, the formation of complex anions AlxO2-y, SixO2-y, FexO2-y to constrain the free oxygen, reduce the erosion of the slag. Neutralization in slag melt occurs. For example, when a ferroolivine composition is implemented in the melt, alumina significantly increases the amount of AlO3- in the melt, while reducing the share of free oxygen.
Another effect of the neutralizer is its effect on the viscosity of the erosion. For example, the introduction of CaO greater than 30% or MGO 20% or Cr2O37% in calcium oxy-silicate slag can increase the viscosity of the slag to 1Pa·s, resulting in much less refractory dissolution. Therefore, 20% neutralizer is added to calcium oxide-silicate slag; At 1600℃, the dissolution strength of the clay refractory is 0.2mg/(cm2·s), while the original slag is 2.6mg/(cm2·s).
4.The specified temperature and gas system quota steelmaking production temperature and oxygen supply, these important enhancer values, in the final analysis depends on economic calculations.
The most appropriate value for these data is a compromise.
There are various methods for protecting refractory materials, and the lining of thermal equipment with cyclic operation should keep the temperature fixed.
For example, ladle, converter, etc., the cover should be closed during the interval between filling, and if the interval is longer, the special burner should be heated.
5.Reasonable refractory masonry structure
In general, it is related to the need to improve the thermal shock resistance of the lining, because the traditional method is to improve the thermal shock resistance of a single product, often does not guarantee the thermal shock resistance of the masonry. The protection of refractory materials in masonry is solved by various methods to prevent damage due to mechanical stress.
When one side heat flow is fixed, the elongated thermal stress in the inner lining can be reduced effectively according to the line method of wall thickness temperature gradient.The linear temperature gradient may be achieved by creating a variable porosity structure.
The thermal stress can be reduced by the thickness of the refractory lining in the heat flow direction. However, the change of lining thickness does not always guarantee the reduction of stress. In addition, the heat loss increases. If there is no role of slag, it is reasonable to use a material, select a comparable shape according to the thickness, and constitute a refractory wall structure by several layers. Under a fixed temperature regime, the temperature and stress distribution are calculated on the hot surface of a multilayer sheet at 1400° C. In order to ensure the overall thermal shock resistance of the plate, it must be replaced by three layers with a thickness equal to 8mm, 1.3mm and 4mm.
With the choice of material and thickness of brick joint, the masonry stress can be substantially reduced. The possibility of improving the life of refractory materials is greater, not only in improving the structure of masonry, but also in rationalizing the shape and size of individual products. For example, using effective methods to reduce the trend of magnesium refractory peeling under the conditions of use, when the temperature of one side of the product is unchanged, and the obvious change on the opposite side, in individual fragments, the appropriate sawing depth of the hot side of the product is less than 10mm.
From the point of view of uniform stress distribution, it is more desirable to compare six-sided products with four-sided products, and six-sided prismatic products should be widely used in iron and steel metallurgy equipment. It is reasonable to make five-sided iron sheet impervious to air without burning oil magnesium dolomite products, and many similar examples can be cited.
