生物质混燃锅炉受热面金属的腐蚀特性研究
发布时间：2018-12-12 00:18
【摘要】：化石能源的日益枯竭和环境的严重污染已成为人类面临的两大问题,因此能源的可再生性和对环境友好性是人们关注的焦点。生物质能作为一种可再生的清洁能源,具有分布广泛及数量巨大等特点,其在利用过程中能够实现碳的零排放,并且硫氮的排放量也较化石燃料燃烧少很多。现阶段,生物质燃烧发电是生物质能大规模利用的方式之一,而其与煤混合燃烧更能消除纯生物质电厂初期投资高、原料供应不稳定、规模容量受限以及经济效益不高等问题。但是生物质中钠、钾等碱金属元素及氯元素含量较高,煤中含有硫元素,在混燃过程中生成HCl、碱金属氯化物和碱金属硫酸盐等物质,在一定温度等条件下,这些物质非常容易导致锅炉受热面金属结渣、积灰和腐蚀等问题。本文研究不同组分合成灰对锅炉受热面金属的腐蚀特性,探究了不同工况下受热面金属腐蚀的特性规律。对合成灰腐蚀反应采用热分析动力学研究,定量表征合成灰腐蚀反应过程。探讨了几种常见添加剂对生物质混煤燃烧受热面金属腐蚀的影响规律。利用管式炉模拟生物质混煤燃烧锅炉过热器区域的反应条件,配制合成灰涂抹在金属20G表面,采用增重法,进行受热面金属氯腐蚀特性试验。结果表明生物质混燃锅炉受热面金属的腐蚀特性均符合抛物线规律,受热面金属的积灰对腐蚀的影响相当大,腐蚀速率比无灰增加40%多,同时积灰腐蚀生成的腐蚀产物中C1含量较高。不同组分合成灰对受热面金属的腐蚀程度不同。混合有氯化钠和氯化钾后合成灰的腐蚀性大大增加,但腐蚀性强弱与氯化钠和氯化钾混合的比例关系不大。碱金属硫酸盐的混合会降低腐蚀速率,远低于硫酸钠或者硫酸钾单独出现时的腐蚀速率。氯化钠和硫酸钠所产生的协同作用,会使合成灰对金属的腐蚀速率达到最大。当合成灰中氯化钾和硫酸钾的比例为1：1时,腐蚀速率最低,但随着钾盐比例的变化,腐蚀速率的变化未见明显的规律。随着HCl体积分数的增加,HCl更容易穿过氧化膜向金属基体渗透,与金属发生反应生成金属氯化物,腐蚀速率几乎成线性增加。随着反应温度由450℃升高到650℃时,腐蚀速率随着温度的升高成指数增加,符合阿伦尼乌斯定律。尤其温度从550℃升高到600℃,腐蚀速率急剧增大,温度对该温度区间腐蚀的影响幅度明显变大。采取定温法,对涂有合成灰的受热面金属腐蚀进行热分析动力学研究,表明腐蚀符合二维扩散模式,得到D2模式函数下的动力学方程：量的表征受热面金属腐蚀的反应过程。含有添加剂的合成灰对受热面金属的腐蚀过程也符合抛物线规律,含有添加剂的合成灰D17的腐蚀性大小顺序为：添加Al2O3D17添加SiO2添加CaO添加高岭土。试样表面腐蚀产物中Fe含量越高,金属基体被腐蚀的程度越大,Fe从金属中被置换到表面的腐蚀产物中。含有添加剂的碱金属氯化物的腐蚀性大小顺序为：添加SiO2D6添加CaO添加Al2O3添加高岭土,高岭土中含有的Al和Si元素会捕获碱金属氯化物,形成硅酸铝钾。硅酸铝和碱金属反应会生成更高熔点的碱金属硅铝酸盐,在燃烧中提升了积灰的熔点,可以有效地减缓腐蚀。综合看来,不同种类添加剂加入不同组分合成灰后,原合成灰的腐蚀性大小变化有所不同。添加剂Al2O3和高岭土相比于其他几种添加剂,对于降低腐蚀速率和减缓腐蚀有较好的效果。对于碱金属氯化物腐蚀,合成灰加入高岭土后,腐蚀速率降低16.1%。对于碱金属硫酸盐腐蚀、钠盐腐蚀和钾盐腐蚀,合成灰加入添加剂Al2O3后,腐蚀速率分别降低45.3%、13.1%和34.3%。
[Abstract]:The increasing depletion of the fossil energy and the serious pollution of the environment have become the two major problems facing mankind, so the renewable and environmental-friendly energy of the energy is the focus of the people's attention. As a kind of renewable clean energy, the biomass energy has the characteristics of wide distribution and large quantity, and can realize zero discharge of carbon in the utilization process, and the amount of sulfur and nitrogen is much less than that of the fossil fuel. At present, biomass combustion power generation is one of the ways of mass utilization of biomass energy, which can eliminate the problems of high initial investment of pure biomass power plant, unstable supply of raw materials, limited capacity of scale and high economic benefit. but the content of alkali metal elements and chlorine elements such as sodium and potassium in the biomass is high, sulfur elements are contained in the coal, and substances such as HCl, alkali metal chloride and alkali metal sulfate are generated in the mixed combustion process, and under the conditions of certain temperature and the like, the substances are very easy to cause the metal junction slag of the heating surface of the boiler, and the problems of ash deposit and corrosion and the like are solved. The corrosion characteristics of the metal in the heating surface of the boiler are studied in this paper, and the characteristics of the metal corrosion of the heating surface under different working conditions are investigated. The process of the synthetic ash corrosion reaction was quantitatively characterized by the thermal analysis kinetic study of the synthetic ash corrosion reaction. The effect of several common additives on the metal corrosion of the heated surface of the biomass mixed coal is discussed. The reaction conditions of the superheater area of the biomass mixed coal combustion boiler are simulated by a tubular furnace, and the synthetic ash is applied to the surface of the metal 20G, and the weight gain method is adopted to test the metal chloride corrosion characteristic of the heated surface. The results show that the corrosion characteristics of the metal in the heated surface of the biomass-mixed-burn boiler are in accordance with the law of the parabola, the effect of the deposition of the metal on the surface of the heated surface on the corrosion is quite large, the corrosion rate is more than 40% higher than that of the ash-free, and the content of C1 in the corrosion products generated by the corrosion of the ash is high. The degree of corrosion of different component synthetic ash to the metal of the heated surface is different. The corrosion of the synthetic ash after mixing with sodium chloride and potassium chloride is greatly increased, but the ratio of the corrosivity to the mixture of sodium chloride and potassium chloride is not small. The mixing of the alkali metal sulfates can reduce the corrosion rate, much lower than the corrosion rate at the time of the individual presence of sodium sulfate or potassium sulfate. The synergistic effect of sodium chloride and sodium sulfate can maximize the corrosion rate of the synthetic ash to the metal. When the ratio of potassium chloride and potassium sulfate in the synthetic ash is 1: 1, the corrosion rate is the lowest, but with the change of the proportion of the potassium salt, the change of the corrosion rate is not obvious. With the increase of the volume fraction of HCl, HCl is more easily permeable to the metal matrix through the oxide film, and the metal chloride is generated by reaction with the metal, and the corrosion rate is almost linearly increased. As the reaction temperature increased from 450.degree. C. to 650.degree. C., the corrosion rate increased exponentially with the increase in temperature, in accordance with the Arrhenius law. in particular, that temperature increase from 550 DEG C to 600 DEG C, the corrosion rate is rapidly increase, and the influence of the temperature on the corrosion of the temperature range is obviously changed. The thermal analysis of the metal corrosion of the heated surface coated with the synthetic ash was studied by the method of constant temperature. The results show that the corrosion is in the two-dimensional diffusion mode, and the kinetic equation under the function of the D2 mode is obtained. The reaction process of the metal corrosion of the heated surface is characterized by the quantity. The corrosion process of the composite ash containing the additive to the metal of the heated surface is also in accordance with the parabolic law. The order of the corrosivity of the synthetic ash D17 containing the additive is as follows: adding the SiO2 to the Al2O3D17 to add the CaO and adding the kaolin. The higher the Fe content in the sample surface corrosion product, the greater the degree of corrosion of the metal matrix, and the removal of Fe from the metal to the corrosion product of the surface. The order of the corrosivity of the alkali metal chloride containing the additive is that the addition of SiO2 to the addition of CaO to the Al2O3 is added, and the Al and Si elements contained in the kaolin can capture the alkali metal chloride to form the potassium aluminum silicate. The reaction of the aluminum silicate and the alkali metal will produce a higher melting point alkali metal aluminosilicate, which increases the melting point of the ash deposit in the combustion and can effectively slow down the corrosion. It can be seen that different kinds of additives can be used to synthesize ash with different components, and the change of the corrosivity of the original synthetic ash is different. Compared with other additives, the additive Al2O3 and the kaolin have a better effect on the reduction of the corrosion rate and the reduction of corrosion. For alkali metal chloride corrosion, the corrosion rate is reduced by 16.1% after the synthetic ash is added to the kaolin. The corrosion rate of alkali metal sulfate, the corrosion of the sodium salt and the corrosion of the potassium salt, and the addition of the additive Al2O3, the corrosion rate was decreased by 45.3%, 13.1% and 33.4%, respectively.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM619
本文编号：2373513
[Abstract]:The increasing depletion of the fossil energy and the serious pollution of the environment have become the two major problems facing mankind, so the renewable and environmental-friendly energy of the energy is the focus of the people's attention. As a kind of renewable clean energy, the biomass energy has the characteristics of wide distribution and large quantity, and can realize zero discharge of carbon in the utilization process, and the amount of sulfur and nitrogen is much less than that of the fossil fuel. At present, biomass combustion power generation is one of the ways of mass utilization of biomass energy, which can eliminate the problems of high initial investment of pure biomass power plant, unstable supply of raw materials, limited capacity of scale and high economic benefit. but the content of alkali metal elements and chlorine elements such as sodium and potassium in the biomass is high, sulfur elements are contained in the coal, and substances such as HCl, alkali metal chloride and alkali metal sulfate are generated in the mixed combustion process, and under the conditions of certain temperature and the like, the substances are very easy to cause the metal junction slag of the heating surface of the boiler, and the problems of ash deposit and corrosion and the like are solved. The corrosion characteristics of the metal in the heating surface of the boiler are studied in this paper, and the characteristics of the metal corrosion of the heating surface under different working conditions are investigated. The process of the synthetic ash corrosion reaction was quantitatively characterized by the thermal analysis kinetic study of the synthetic ash corrosion reaction. The effect of several common additives on the metal corrosion of the heated surface of the biomass mixed coal is discussed. The reaction conditions of the superheater area of the biomass mixed coal combustion boiler are simulated by a tubular furnace, and the synthetic ash is applied to the surface of the metal 20G, and the weight gain method is adopted to test the metal chloride corrosion characteristic of the heated surface. The results show that the corrosion characteristics of the metal in the heated surface of the biomass-mixed-burn boiler are in accordance with the law of the parabola, the effect of the deposition of the metal on the surface of the heated surface on the corrosion is quite large, the corrosion rate is more than 40% higher than that of the ash-free, and the content of C1 in the corrosion products generated by the corrosion of the ash is high. The degree of corrosion of different component synthetic ash to the metal of the heated surface is different. The corrosion of the synthetic ash after mixing with sodium chloride and potassium chloride is greatly increased, but the ratio of the corrosivity to the mixture of sodium chloride and potassium chloride is not small. The mixing of the alkali metal sulfates can reduce the corrosion rate, much lower than the corrosion rate at the time of the individual presence of sodium sulfate or potassium sulfate. The synergistic effect of sodium chloride and sodium sulfate can maximize the corrosion rate of the synthetic ash to the metal. When the ratio of potassium chloride and potassium sulfate in the synthetic ash is 1: 1, the corrosion rate is the lowest, but with the change of the proportion of the potassium salt, the change of the corrosion rate is not obvious. With the increase of the volume fraction of HCl, HCl is more easily permeable to the metal matrix through the oxide film, and the metal chloride is generated by reaction with the metal, and the corrosion rate is almost linearly increased. As the reaction temperature increased from 450.degree. C. to 650.degree. C., the corrosion rate increased exponentially with the increase in temperature, in accordance with the Arrhenius law. in particular, that temperature increase from 550 DEG C to 600 DEG C, the corrosion rate is rapidly increase, and the influence of the temperature on the corrosion of the temperature range is obviously changed. The thermal analysis of the metal corrosion of the heated surface coated with the synthetic ash was studied by the method of constant temperature. The results show that the corrosion is in the two-dimensional diffusion mode, and the kinetic equation under the function of the D2 mode is obtained. The reaction process of the metal corrosion of the heated surface is characterized by the quantity. The corrosion process of the composite ash containing the additive to the metal of the heated surface is also in accordance with the parabolic law. The order of the corrosivity of the synthetic ash D17 containing the additive is as follows: adding the SiO2 to the Al2O3D17 to add the CaO and adding the kaolin. The higher the Fe content in the sample surface corrosion product, the greater the degree of corrosion of the metal matrix, and the removal of Fe from the metal to the corrosion product of the surface. The order of the corrosivity of the alkali metal chloride containing the additive is that the addition of SiO2 to the addition of CaO to the Al2O3 is added, and the Al and Si elements contained in the kaolin can capture the alkali metal chloride to form the potassium aluminum silicate. The reaction of the aluminum silicate and the alkali metal will produce a higher melting point alkali metal aluminosilicate, which increases the melting point of the ash deposit in the combustion and can effectively slow down the corrosion. It can be seen that different kinds of additives can be used to synthesize ash with different components, and the change of the corrosivity of the original synthetic ash is different. Compared with other additives, the additive Al2O3 and the kaolin have a better effect on the reduction of the corrosion rate and the reduction of corrosion. For alkali metal chloride corrosion, the corrosion rate is reduced by 16.1% after the synthetic ash is added to the kaolin. The corrosion rate of alkali metal sulfate, the corrosion of the sodium salt and the corrosion of the potassium salt, and the addition of the additive Al2O3, the corrosion rate was decreased by 45.3%, 13.1% and 33.4%, respectively.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM619
【引证文献】
相关会议论文 前1条
1 张军;盛昌栋;魏启东;;生物质燃烧过程中受热面的腐蚀性机理和防范措施[A];长三角清洁能源论坛论文专辑[C];2005年
，本文编号：2373513
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