Al2O3-Cr2O3复合砖 危废焚烧探索 brick research
医疗垃圾是指医疗机构在医疗、预防、保健以及其他相关活动中产生的具有直接或间接感染性、毒性以及其他危害性的废物。当今已有多种技术可用于对医疗垃圾的处置,焚烧法适用于各种传染性医疗垃圾,是医疗垃圾处理领域的主流技术。回转窑式垃圾焚烧炉即是其中一种焚烧处理设备,它能完全保证医疗垃圾的稳定化、安全化、减量化和无害化的环保要求,同时又符合当代医疗垃圾处理的发展趋势。
Medical waste refers to the waste that is directly or indirectly infectious, toxic, and other harmful produced by medical institutions in medical treatment, prevention, health care, and other related activities.Nowadays, there are a variety of technologies that can be used for the disposal of medical waste, and the incineration method is applicable to various infectious medical waste, which is the mainstream technology in the field of medical waste treatment.The rotary kiln waste incinerator is one of the incineration treatment equipment, which can fully ensure the stability, safety, reduction and harmless environmental protection requirements of medical waste, and is also in line with the development trend of contemporary medical waste treatment.
垃圾焚烧炉内温度通常在1400~1600℃,局部达1700℃;炉内与热面区接触的熔渣包含Na2O、K2O、Cl-、SO2-4等,碱度0.3~1.5;回转窑旋转方式为正反摆动;炉内气氛不断变化;垃圾种类、含水量等变化大。因此,需要耐火材料具有优良的抗熔渣侵蚀、渗透性,高强度,耐冲刷,耐磨损以及良好的抗热震性能,以适应机械应力和热应力的冲击。目前,垃圾焚烧炉使用的耐火材料主要有高铬、镁铬、铝铬、高铝、碳化硅等材质,但由于受炉内气氛、使用温度、炉渣内钙硅比的不确定性及垃圾种类的多变性,使得以上性能较好的材料很难达到其预期的使用效果。
The temperature in the garbage incinerator is usually 1400~1600℃, locally 1700℃; the slag contacting the heat surface area in the furnace includes Na2O, K2O, Cl-, SO2-4, base degree 0.3~1.5; the rotary kiln is positive and reverse swing; the atmosphere in the furnace is changing; the garbage type and water content change greatly.Therefore, refractory materials are required to have excellent resistance to slag erosion, permeability, high strength, erosion resistance, wear resistance and good thermal shock resistance to meet the impact of mechanical stress and thermal stress.At present, the refractory incinerator mainly use high chromium, magnesium chromium, aluminum and chromium, high aluminum, silicon carbide and other materials, but due to the atmosphere in the furnace, use temperature, the uncertainty of calcium and silicon ratio and the variability of garbage types, make the above performance of better materials is difficult to achieve the expected use effect.
在本研究中,制备出了结构致密、耐压强度高、抗热震性好的Al2O3-Cr2O3复合砖,并介绍了其在处理医疗垃圾的直筒型回转窑式焚烧炉上的应用情况。
In this study, Al2O3-Cr2O3 composite bricks with compact structure, high pressure resistance strength and good heat shock resistance were prepared and their application in straight cylinder rotary kiln incinerator for medical waste.
各层的内径分别为R1=1.83 m、R2=2.08 m、R3=2.15m,钢壳外半径为R=2.178 m,设各层的内表面温度分别为t1、t2、t3,钢壳外壁温度为tw,热导率分别为λ1=3.1 W·(m·K)-1,λ2=1.3 W·(m·K)-1,λ3=37.5 W·(m·K)-1,传热计算选取燃烧室附近的高温区域,工作温度约1 400℃,外界极限温度为t=40℃。
The inner diameter of each layer is R1=1.83 m, R 2=2.08 m, R3=2.15m, the steel shell outer radius is R=2.178 m, so that the inner surface temperature of each layer is t1, t2, t3, the temperature of the outer wall of the steel shell is tw, the thermal conductivity is 1=3.1 W · (m=K W-1,2=1.3 W · (3 · K) -1,3=37.5 W · (m · K) -1. The heat transfer calculation selects the high temperature area near the combustion chamber, the working temperature is about 1 400℃, and the external limit temperature is t=40℃.
采用迭代法,带入数据计算结果如下:
(1)当耐火砖基本无明显侵蚀剥落时,即工作面内径R1=1.83 m,此时外壁温度约为260℃。
(2)当耐火砖侵蚀剥落60 mm时,即工作面内径R1=1.89 m,此时外壁温度约为281℃。
(3)当耐火砖侵蚀剥落200 mm时,即工作面内径R1=2.03 m,此时外壁温度约为355℃。
由此计算可知,从理论来讲工作面耐火砖的选择完全能够满足使用要求;从回转窑运行情况来看,工作面耐火砖的损毁情况基本正常。按传热公式计算并结合窑外壁温度及理论上可使用的厚度计算推测,正常状况下,耐火砖再使用6~10个月没有问题。
Using iterative method, the data calculation are as follows:
(1) When the refractory brick is basically without obvious erosion, that is, the inner diameter of the working surface is R1=1.83 m, and the temperature of the outer wall is about 260℃.
(2) When the refractory brick is peeled off for 60 mm, the inner diameter of the working surface is R1=1.89 m, and the temperature of the outer wall is about 281℃.
(3) When the refractory brick eroded and strips 200 mm, the inner diameter of the working surface is R1=2.03 m, and the temperature of the outer wall is about 355℃.
It shows that the view of the operation of the rotary kiln, the damage of the working surface is basically normal.According to the heat transfer formula calculation and combined with the temperature of the kiln outer wall and the thickness theoretically available for use, it is speculated that under normal conditions, there is no problem with using the refractory bricks for another 6 to 10 months.
