【作者】 陈姝；

【导师】 马晓茜；

【作者基本信息】 华南理工大学 ， 电站系统及其控制， 2014， 博士

【摘要】 随着我国经济的发展和城镇化进程的推进，生活垃圾的产量呈逐年增大趋势，焚烧发电是处理城市生活垃圾无害化、减量化和资源化的有效手段。同发达国家和地区相比，我国生活垃圾含水量较大、热值较低，随季节和地区变化明显，国外引进设备无法适应高水分本土垃圾，导致焚烧效率降低。生活垃圾焚烧发电过程释放大量气体产物，其中氮氧化物等气体对环境和人体危害严重。实验研究广州城市生活垃圾的干燥特性和气体排放特性，为从源头上控制污染物排放、改进和设计适于本土垃圾的焚烧设备提供参考。本文对城市生活垃圾的干燥和燃烧过程进行了实验研究和理论分析，探讨了生活垃圾混合物及典型厨余组分的干燥特性并进行了动力学分析；讨论了炉膛温度、氮氧比、秸秆和煤的掺混比、催化剂种类及担载比、含水率等因素对垃圾燃烧气体排放特性的影响；采用数值模拟的方式研究了不同含水率和秸秆掺混比的城市生活垃圾在机械炉排炉内燃烧的热质传递过程。（1)模拟焚烧炉内干燥条件，以广州地区生活垃圾典型厨余组分和混合物为研究对象在干燥箱内进行实验研究，分析了温度对生活垃圾干燥特性的影响，获得了描述实验过程的最优干燥模型。结果表明：干燥温度越高，干燥时间越短，极值干燥速率越大，对应含水率越低； Modified page和Weibull Distribution模型均可较准确的描述实验过程；通过菲克扩散模型计算出实验范围内的水分有效扩散系数，由阿乌尼斯方程得出活化能。（2)在卧式管式炉内实验研究了生活垃圾混合物及主要单组分燃烧的气体排放特性，讨论了不同炉膛温度和燃烧气氛对垃圾混合物燃烧气体排放特性的影响，通过改变废布制品和树枝在垃圾混合物中的比例探讨组分比例对气体释放的影响。结果表明：生活垃圾混合物燃烧O2波谷与CO、CO2波峰位置一致， CO曲线呈单一释放峰，NO排放曲线出现双释放峰，其波谷与CO波峰出现时间接近；四种垃圾单组分相比，厨余对氧气消耗量最大，废布制品燃烧CO和CO2生成峰值浓度最高，厨余生成NO峰值浓度最高，是影响NO排放的主因；炉膛温度升高，残余率和CO峰值浓度随之降低，析出时间提前，CmHn峰值浓度则随之上升，NO峰值呈先降后升的趋势；实验气氛含氧量越高，NO双峰值和CO2峰值越高，CO和残余率则相反； CO峰值和NO挥发分释放峰值随垃圾中废布制品含量升高而提高，树枝含量比例越大，CO峰值浓度越高，NO峰值则无规律变化。（3)不同比例的秸秆和煤分别与生活垃圾混合物在卧式管式炉内混合燃烧，烟气分析仪实时收集主要气体排放浓度，对NO的生成量和N析出率进行数学模型研究，结果表明：生活垃圾与煤混燃不改变CO和NO排放曲线形状，增加煤的掺混比可缩短燃烬时间、降低CO峰值浓度、提高NO固定氮析出峰值和生成量；垃圾中掺混秸秆燃烧可改变CO曲线形状，对NO曲线形状无影响，随着秸秆掺混比的提高，焦炭氮峰值升高，燃烬时间提前，N析出率下降；NO生成量、N析出率和残余率由大到小的顺序为：与煤混燃>垃圾独燃>与秸秆混燃；建立了可描述秸秆、煤掺混比和NO生成量关系的数学模型，对实验数据非线性拟合证明Logistic数学模型拟合度较优。（4)将五种碱金属化合物以不同担载比与生活垃圾在管式炉内催化燃烧，分析主要气体产物释放特性，计算燃烬率，对N析出率进行数学模型研究。结果表明：生活垃圾担载催化剂燃烧促O2波谷浓度提高，CO2变化不大，CO曲线形状趋宽阔，NO曲线固定氮析出峰出现时间延迟，CO和NO峰值因催化剂的种类和担载比而异；15种实验样品相比，9%CaO、5%和7%K2CO3、7%和9%Na2CO3催化垃圾燃烧NO平均排放浓度和N析出率较低、燃烬率较高，是垃圾燃烧较理想的催化选择；Logistic数学模型模拟实验过程N析出率决定系数较高，其中描述Ba2CO3催化燃烧过程最为准确。（5)卧式管式炉内对不同含水率的原生生活垃圾进行燃烧实验，研究气体排放特性，建立N、C和H析出率的数学模型，计算残余率。结果表明：垃圾含水率越高，干燥段越长，气体析出越慢，O2波谷浓度和CO2波峰浓度越高；CO曲线出现双释放峰，挥发分C析出峰较高且随含水率的升高而降低；CmHn和NO曲线均呈单一释放峰，随着含水率的升高，CmHn峰值呈先升后降的现象，NO峰值则随之升高；C、N、H析出率随含水率的升高而增大。Logistic数学模型对N、C和H实时析出率的描述R2均大于0.99303，拟合度较优。（6)采用CFD方式对广州某实际运行炉排炉进行数值模拟研究，探讨垃圾含水率和秸秆掺混比对炉内焚烧效果的影响。结果表明：垃圾含水率降低和秸秆掺混比增大均可提高燃料热值，促进炉内温度上升，但在确保烟气在炉内停留时间和炉内温度维持高温的前提下，需相应提高过量空气系数，否则因氧气不足导致垃圾燃烧不完全，烟气中可燃气体和颗粒比重较高。更多还原

【Abstract】 With the development of economy and urbanization, production of municipal solidwaste(MSW) was gradually increasing. Incineration power generation is an effective meansof making MSW harmness,reduction and resource-oriented. Compared with developedcountry and district, MSW in China has of high moisture content, low heat value and changeswith season and district. Employing imported equipment in local MSW combustion reducedcombustion efficiency. Large amounts of gas products would be released from incinerationprocess, including nitrogen oxides and other gases harm to environment and human healthseriously. Experiments were conducted on drying characteristics and gas emissioncharacteristics of Guangzhou MSW. It is hoped to provide reference for controlling pollutantsemission from source, designing and improving incineration equipment suitable to local MSW.The experimental research and theoretical analysis on drying and combustion process ofMSW were carried on. The drying characteristics of MSW and typical kichen disposal werediscussed and the dynamic analysis was studied. The factors on gas emissions from MSWcombustion were investigated, such as furnace temperature, combustion atmosphere, blendingratio of straw and coal, catalyst type and blending rate, moisture content and so on. The heatand mass transfer process on MSW combustion in grate furnace, was simulated by CFD onthe condition of changing moisture content and blending rate of straw.（1)A series of drying experiments on municipal solid waste(MSW) in Guangzhou wereconducted in air dry oven，simulating the drying process in incineration. Temperatureinfluence on drying characteristics of MSW was analyzed. The optimal drying models wereobtained to predict experimental drying process. The results show that drying time is shorter,maximum drying rate is higher and the corresponding moisture content is lower with thehigher drying temperature. The experimental drying process could be described accurately byModified page and Weibull distribution models. The effective diffusivity of MSW wascalculated with fick’s diffusivity model. The MSW activation energy was determined throughArrhenius equation.（2)Experiments on gas emissions from municipal solid waste (MSW) and typicalelements combustion were conducted in a lab-scale electrically heated tubular furnace. Thegas emission characteristics were discussed on the factors of furnace temperature andatmosphere. MSW samples with different ratio of waste cotton and branch were taken asexperimental material in order to find the gas emission characteristics. The results indicatedthat the locations on the trough of O2, peaks of CO and CO2emerged simultaneously. The CO emission curves expressed single peak and NO curves had two peaks. Compared with fourwaste elements, waste cotton combustion produced highest peak concentration of CO andCO2, kitchen disposal combustion consumed maximum oxygen and brought highest NO peakvalue. It means that kitchen disposal is the main factor on NO emission. With the temperatureincreasing, the residual rates and CO peak values decreased, time of gas emission shiftedearlier, the peak value of CmHnincreased, NO peak values decreased first and then increased.The higher the oxygen content in atmosphere, the higher the two peak values of NO and CO2peak values, the lower the CO peak values and residual rates. CO peak values and the secondNO peak values were improved with the increasing mass ratio of waste cotton. CO peakvalues elevated with growing mass ratio of branch, but not for NO curves.（3)Experiments on MSW co-combustion with straw and coal were conducted in alab-scale electrically heated tubular furnace at850°C. The gas concentration was measuredwith gas analyzer. The mathematic models were researched on NO production and Nconversion rate. The following conclusions could be drawn: the shapes of NO and CO curveswere not affected by co-combustion with coal. The increasing blending ratio of coal resultedin shortening burning time, reducing CO peak value, improving NO second peak value andproduction. MSW co-firing with straw could change CO curves, but not for the NO curves.With the increasing blending ratio of straw, the second peak value of NO curve was increased,burning time was shortened and the N conversion rate was decreased. The sequence of NOproduction and N conversion rate was described as: co-combustion with coal>MSWcombustion> co-combustion with straw.Model of NO production could predict the value withdifferent straw and coal blending rate. The N conversion rate of experimental combustionprocess could be described accurately by Logistic model.（4)Five kinds of alkaline compounds with different blending rate were chosen ascatalysts applied in MSW combustion in terms of NO emission and burnout rate.Mathematical model were constructed on N conversion rate. The results showed that catalystaddiition in MSW combustion could increase O2trough concentration, change the CO2peakvalue little, make the CO curves broad and delay the location of NO second peak. The peakvalues and peak locations of CO and NO emission curves changed with catalyst type andblending ratio. In comparison with15samples,9%CaO、5%and7%K2CO3、7%and9%Na2CO3addition in MSW combustion could reduce NO average concentration and Nconversion rate, enhance burnout rate, so they could be the better choices as catalyst for MSWcombustion. There are higher determination coefficients utilizing Logistic model to simulateN conversion rate of experimental process, especially for Ba2CO3. （5)Combustion experiments on MSW with different moisture content were carried on at850°C. Gas emissions and the models describing N, C and H conversion rate were the mainpoints. The residual rates were calculated. It could be concluded that with higher moisturecontent, the drying process was longer, the process of gas emission was slower, the O2troughconcentration and CO2peak concentration were higher. There were two preaks in the COcurves and the first peak value decreased with the improved moisture content. The single peakappeared in the curves of CmHnand NO curves. With the higher moisture content, the NOpeak values enhanced, the peak concentration of CmHnascent firstly and then dropped. Thehigher moisture content, the higher C, N and H conversion rate. The Logistic model simulatedthe experimental process of C, N and H conversion rate accurately with R2more than0.99303.（6) The operating grate furnace in Guangzhou was simulated with the method of CFD.The effect of moisture content and blending rate of straw on combustion efficiency wasdisscussed. The following results could be concluded: the decreasing moisture content andincreasing blending rate of straw could improve heat value and temperature distribution in thefurnace. On the condition of satisfying the resistance time of flue gas and temperature level,the excess air ratio should be increased in order to avoid imcomplete combustion owing tolack of oxygen.更多还原