【作者】 李秋荣；

【导师】 白明华；

【作者基本信息】 燕山大学 ， 机械设计及理论， 2008， 博士

【摘要】 脉冲放电低温等离子体技术的研究始于20世纪70年代末,是一种有效的烟气脱硫脱氮方法。迄今为止,各国的研究人员仍在不断探索,力求使该项技术趋于完善。本文利用所设计制造的除尘、脱硫脱氮的分立装置和除尘脱硫脱氮一体机进行了如下方面的试验研究:放电等离子体除尘脱硫的试验;网状转动极板除尘脱硫脱氮装置的设计和试验;低碳烃活化与电晕放电协同脱除NO的试验及热力学分析;催化剂与电晕放电协同脱硫脱氮的试验;金属氧化物脱硫反应的热力学计算及模型建立。通过试验和理论分析,获得如下研究结果。通过电晕放电脱硫的试验分析表明,脉冲电晕放电的脱硫效率高于负直流电晕放电脱硫,氨气和水蒸气从放电极喷出的烟气脱硫提高率高于氨气和水蒸气从烟气入口进入的状况。利用网状转动极板除尘脱硫脱氮一体机进行除尘脱硫脱氮的试验,结果表明,烟道中气流速度越大,除尘效率越低;当烟道里气流风速为2.1m/s时,转速越大,干法除尘效率越高,转速为12rpm时,除尘效率可达到99%;在转速为6rpm和通水的情况下,除尘效率可以达到99%以上。在通水或通氨的情况下,极板转动对脱硫脱氮没有影响;然而在发尘情况下,极板转动对脱硫效率影响,比固定极板提高5%。Cu-Cr-Al-Ni合金放电针在3.5%NaCl+4.5mol/L NH3溶液中腐蚀优先在Cu/Cr相交界处产生,在该条件磨损作用下Cu-Cr-Al-Ni合金中Cr相易从基体上剥离下来,外加载荷越大,Cr相剥离倾向越大。采用低碳烃与电晕放电协同脱除NO的实验结果与热力学分析计算一致,在298K下,甲烷、乙烷、乙烯、乙炔、丙烷和丙烯等低碳烃与NO反应的标准吉布斯函数变表明乙烷、乙炔、丙烷和丙烯的正向反应的趋势较大,其中丙烯的趋势最大。通过脉冲电晕放电与CuO/γAl2O3协同处理脱除烟气中SO2和NO的试验可知,脉冲电晕放电与CuO/γAl2O3协同处理脱除烟气中SO2和NO,脉冲电压达到40kV时,进口烟气温度为80℃,出口烟气温度为40℃,气体在烟道中的流速为1.3m/s,SO2的初始浓度为1400mg/m3,NO的初始浓度350 mg/m3,SO2的去除率达到85%以上,NO的去除率为30%;通过对催化剂的性能进行表征,发现催化剂与脉冲电晕协同处理后,在低温下也有较大的反应活性。运用化学热力学理论对常见金属氧化物脱硫剂(CuO,CaO,Fe2O3,MgO,CeO2)脱硫反应的吉布斯函数变(ΔG)和平衡时SO2的分压等进行计算。计算结果表明:金属氧化物脱硫剂的脱硫反应在常温下就有很大的正向进行趋势。由金属氧物脱硫剂有效反应温度范围内的脱硫反应SO2平衡分压可知:脱硫效率由高到低的顺序依次为:CeO2>CuO>MgO>CaO>Fe2O3。而且脱硫效率都有随温度升高而降低的趋势。本文还采用缩核模型和晶粒模型思想,对非催化的脱硫反应进行了宏观与微观联合建模。更多还原

【Abstract】 The technology of low temperature plasma from pulse corona discharge came into being at the end of 1970s, which is one efficient method of fuel desulphurization and denitrification. Since then, researchers of many countries have been working on it for making it perfect.In this paper, it is reported that the experiments have been made on both sectional and integrated equipment for dust collection and desulphurization denitrification, such as, desulphurization and dedust test by discharge plasma, design of the device with original rotating net plate and test of collecting dust and desulphurization denitrification, thermodynamic analysis on nitric oxide removal by low carbon hydrocarbons and corona discharge; synergistic treatment of SO2 and NO in fuel by pulse corona discharge and catalyst; thermodynamic functions calculation of metal oxides reacting with SO2 and the desulphurization reaction model. The main achievements and results are as follows: Through the test result of corona discharge desulphurization, It is shown that desulphurization efficiency of positive pulse corona discharge is higher than negative DC corona discharge’s, desulphurization efficiency of ammonia and steam coming in reactor from discharge polar is higher than that from fuel entrance.Tests are carried out , which are collection dust, desulphurization and denitration by using electrical precipitator with the original rotating net plate, result is shown that the lower collecting dust efficiency is, the higher wind speed of fuel pipe is. When wind speed is 2.1m/s, the bigger rotation speed is, the bigger collecting dust efficiency of dry method is, as rotation speed is 12 rpm, collecting dust efficiency is 99%. When rotation speed is 6 rpm and aerating water, collecting dust efficiency is more than 99%. Under the condition of aerating water or ammonia, rotation plate does not influence desulphurization and denitration efficiency. However, on the condition of making dust into reactor, desulphurization efficiency of rotation plate is higher than 5% in comparison with fixed plate. The corrosion of Cu-Cr-Al-Ni alloy discharge pole occurs first in the interface between Cu and Cr in 3.5%NaCl+4.5mol/L NH3 solution, and the Cr phase of Cu-Cr-Al-Ni alloy is more easy to flake off with the weight amount of load increasing. The morphology character of corrosive wear of Cu-Cr-Al-Ni alloy in 3.5%NaCl+4.5mol/L NH3 solution is mainly in form of cutting, and with corrosion, and the synergistic effect between corrosion and abrasion results in the increase of corrosive wear mass loss of alloy.The result from the test on NO removal by pulse corona discharge with low carbon hydrocarbons is identical with that from the thermodynamic analysis of nitric oxide removal by low carbon hydrocarbons. As 298K,ΔGθof reactions, which are the reaction of methane, ethane, ethylene, ethine, propane and propene with NO, it is indicated that positive reaction tendency of ethane, ethine, propane and propene is very strong, and that of propene is the strongest.The experiments show that SO2 and NO in the smoke can be removed efficientlyby pulse corona discharge together with CuO/γ- Al2O3.When pPulse voltage is 40kV, inlet fuel temperature is 80℃,outlet fuel temperature is 40℃,fuel flow velocity is 1.3m/s,initial concentration of SO2 is 1400mg/m3, and initial concentration of NO is 350 mg/m3, SO2 removal efficiency is above 85%, and NO removal efficiency is 30%. The surface structure of the catalyst has been investigated by IR and XRD, it is found that catalyst has better activity at low temperature by synergistic action with pulse corona discharge.By calculatingΔG, Kp of desulferization agents (CuO,CaO,Fe2O3,MgO ,CeO2) for desulferization reactions and partial pressure of SO2 at equilibrium state by the theory of chemical thermodynamics.The results are indicated that the positive tendency of desulferization reactions are evidencely at room temperature. From the partial pressure of SO2 at equilibrium state and optimum temperature, it is shown that the sequence of the SO2 removal activity is CeO2> CuO >MgO >CaO>Fe2O3. It is the same as the results of calculation by the method of thermodynamics. The reaction of desulphurization is non-catalysis, and its mechanism can be described by the concept of the shrinking core model and the grain model.更多还原