Experimental study on combustion characteristics of municipal solid waste

As incineration provides a relatively safe means of disposal, significant reduclaon ot welglat anti volume, ana energy recovery from the waste, it was adopted by many countries. For the experimental investigation on the combustion characteristics of municipal solid waste( MSW),a lab scale fluldized bed facility was constructed. Many kinds of combustion runs were conducted in this fluidized bed combustion facility. The examined parameters were bed temperature(773 to 1143K), form of fuels ( scrap or whole), moisture of fuels and so on. Concentration of CO2,CO,SO2, O2 and NOx in the flue gas were monitored and recorded every 5 seconds. The temperatttres along the reactor are recorded every 10 seconds. Experimental. results were given and analyzed.     

水蒸气对层流甲烷/空气扩散火焰中烟黑生成的影响

空气中水的存在会严重影响烷烃类扩散火焰中烟黑的生成,研究氧化剂流中水对烷烃类火焰的影响,对污染物控制及火灾扑救具有重要意义。模拟采用24步简化机理的有限速率化学反应模型、Moss-Brookes烟黑模型及Discrete Ordinates(DO)辐射模型,研究在空气中加入水对甲烷/空气层流伴流扩散火焰的影响,其中烟黑模型包括烟黑的成核、表面增长和氧化。结果表明,伴流空气中的水蒸气会降低火焰的温度、抑制烟黑的生成。这是因为:一方面,水蒸气降低了甲烷燃烧的温度,火焰温度的降低导致化学反应速率减慢,烟黑成核和表面生长速率随之降低,火焰中烟黑质量分数便减少;另一方面,由于水蒸气的加入使化学反应OH+H_2 H+H_2O(R(15))逆向反应加速,继而导致OH生成量增加。但由于氧气浓度降低使火焰体积增大,OH的浓度降低。从而导致烟黑的氧化速率降低,烟黑生成量增加。由于水蒸气的化学效应小于其温度效应,总体上烟黑质量分数降低。最后对比了模拟结果和试验结果。     

Emission control strategies of hazardous trace elements from coal-fired power plants in China

China's energy dependents on coal due to the abundance and low cost of coal. Coal provides a secure and stable energy source in China. Over-dependence on coal results in the emission of Hazardous Trace Elements (HTEs) including selenium (Se), mercury (Hg), lead (Pb), arsenic (As), etc., from Coal-Fired Power Plants (CFPPs), which are the major toxic air pollutants causing widespread concern. For this reason, it is essential to provide a succinct analysis of the main HTEs emission control techniques while concurrently identifying the research prospects framework and specifying future research directions. The study herein reviews various techniques applied in China for the selected HTEs emission control, including the technical, institutional, policy, and regulatory aspects. The specific areas covered in this study include health effects, future coal production and consumption, the current situation of HTEs in Chinese coal, the chemistry of selected HTEs, control techniques, policies, and action plans safeguarding the emission control. The review emphasizes the fact that China must establish and promote efficient and clean ways to utilize coal in order to realize sustainable development. The principal conclusion is that cleaning coal technologies and fuel substitution should be great potential HTEs control technologies in China. Future research should focus on the simultaneous removal of HTEs, PM, SOx, and NOx in the complex flue gas.     

IWO-PSO-SVR算法在甲烷检测中的应用

提出一种入侵杂草算法改进的粒子群算法（IWO-PSO）用于支持向量机（SVR）算法来快速实时检测甲烷气体浓度系统,气体红外激光差分吸收法检测系统基于甲烷气体分子在1650nm处泛频光谱吸收带,结合可调谐二极管吸收光谱（TDLAS）与波长调制光谱（WMS）.选择半导体激光器瞬时输出光功率变化范围5.0~10.6mW,瞬时波长变化范围1650~1651nm,瞬时调谐频率范围0.0048~0.0115nm/mA;采集山东淄博某农场2019年3月份全天气体样本,随机抽取15组样本作为训练集,建立以光谱峰面积作为输入值与气体浓度作为输出值的IWO-PSO-SVR、SVR、PSO-SVR和PSO-BP定量分析模型,对测试集4种浓度的甲烷分别进行预测;结果表明,通过IWO-PSO-SVR定量分析模型效果最佳,4种甲烷浓度预测值与真实值相对偏差分别为0.115%、0.109%、0.131%、0.120%,均低于0.0014;相关系数分别为0.9987、0.9966、0.9899、0.9975均高于0.98;预测时间分别为1.35、1.54、1.35和1.33s,模型经过1000次训练对气体的检测精度为10^-5,与同类别检测系统相比,具有很强的理论研究价值和工程应用价值.     

煤氧化特性与影响因素实验研究

为分析自热临界温度和采空区漏风风速对煤自燃的影响,在常温(30℃)、中温(60℃)、不同通气量等条件下对滕东煤矿3下煤层煤样进行了煤炭自燃氧化规律实验。结果表明:煤样在60℃氧化所放出的CO量较30℃时高3.4~4.1倍,煤炭氧化速率上升梯度约1.35 ppm/℃;在恒温变通气量条件下,CO气体浓度呈现先减小后稳定的趋势,CO的释放量随通气量的增大而减小;在通气量为50 mL/min(采空区漏风为0.1 m/min)的条件下,煤氧化释放的CO量最大且煤氧化能力最强,应加强最易发生自燃漏风区域的密封防护。     

曝气-电解生态浮床的净化效果与机理分析

为强化生态浮床对重污染河道水体的净化能力,采用曝气-电解生态浮床联合技术增强生态浮床的净化功能.试验考察了电流密度、曝气量和处理时间对模拟的高氮磷重污染水体的净化潜力,分析了电解反应对填料细菌群落结构组成和浮床水生植物黄菖蒲（Iris pseudacorus）生长的影响.结果表明：在进水NH₃-N浓度为10 mg·L^-1,PO₄^3--P浓度为0.8 mg·L^-1,电流密度为0.74 mA·cm^-2,水力停留时间为3 d的条件下,相比于电解生态浮床和传统的生态浮床,曝气-电解生态浮床有利于水体中NH₃-N的去除（p<0.001）,其NH₃-N浓度下降至（0.92±0.24）mg·L^-1,而电解生态浮床处理的水体NH₃-N浓度为（6.85±0.17）mg·L^-1,传统生态浮床处理水体中NH₃-N浓度高达（8.09±0.40）mg·L^-1,曝气促进了水体中NH₃-N向NO₂^--N和NO₃^--N的转化.电解有利于水体中PO₄^3--P的去除,电解生态浮床处理水体中的PO₄^3--P浓度下降至（0.43±0.02）mg·L^-1,曝气-电解生态浮床处理的水体中PO₄^3--P下降至（0.46±0.02）mg·L^-1,可见,电解促进了PO₄^3--P的去除.从对I.pseudacorus生理生化指标变化分析可知,曝气有利于减弱电解反应对I.pseudacorus的损伤;对基质生物膜的16S rDNA分析可知,电解反应增加了浮床基质中自养反硝化微生物数量.因此,曝气-电解生态浮床是一种有效的净化重污染水体的方法.     

Uranium speciation in coal bottom ash investigated via X-ray absorption fine structure and X-ray photoelectron spectra

Similar to chromium contamination, the environmental contamination caused by uranium in radioactive coal bottom ash (CBA) is primarily dependent on the chemical speciation of uranium. However, the relationship between uranium speciation and environmental contamination has not been adequately studied. To determine the relationship between uranium speciation and environmental contamination, X-ray absorption fine structure (XAFS) and X-ray photoelectron spectra (XPS) analyses were performed to determine the uranium speciation in CBA exposed to different chemical environments and simulated natural environments. The leachability of the different forms of uranium in the CBA was studied via a simulated acid rain leaching experiment, and the results showed that 57.0% of the total uranium was leached out as U(VI). The results of a linear combination fit (LCF) of the X-ray absorption near edge structure (XANES) spectrum revealed that in the raw CBA, the uranium mainly occurred as U3O8 (71.8%). However, in the iron-rich particles, the uranium mainly occurred as UO2 (91.9%) after magnetic separation. Magnetite is a ubiquitous ferrous-bearing oxide, and it was effective for the sorption of U(IV). The result of FeSO4 leaching experiment indicated that 96.57% of total uranium was reduced from U(VI) to U(IV) when infiltrated with the FeSO4 solution for 6 months. This result clearly demonstrated the changes in chemical valence of uranium in the coal ash and provided a conceptual principle for preventing uranium migration from ash to the surrounding soil and plants.     

腐殖酸影响剩余污泥厌氧消化过程实验研究

以实验室培养、几乎不含腐殖质和金属离子的剩余污泥作为研究对象,选择与市政污泥中腐殖酸特征相近的市售腐殖酸为外加填充物,实验研究污泥中所含腐殖质对污泥厌氧消化过程的抑制作用.通过设置腐殖酸不同投加比例(0、5%、10%、15%和20%,以VSS计),探究腐殖酸对厌氧消化不同过程的影响.实验结果表明,腐殖酸抑制厌氧消化生物气产气量.填加15%腐殖酸时对厌氧消化产气量抑制作用最为明显,较未添加腐殖酸对照组产气量下降了35%;但并未对生物气中CH_4体积比产生太大影响,说明抑制影响是对生物气整体性的.腐殖酸亦可抑制厌氧水解过程,投加20%腐殖酸实验组实验结束时残留于上清液中的溶解性多糖、蛋白质浓度分别是对照组的2.2和1.6倍.然而,腐殖酸作为外源电子受体,可以在一定程度上促进酸化过程,其程度在填加20%腐殖酸实验组表现最高,较对照组VFAs提高了11.3%.腐殖酸投加未对系统pH产生明显影响,各实验组pH值均在7.09~7.54间变化.     

不同基质配比对农村生活垃圾厌氧发酵效率及稳定性的影响

以典型农村生活垃圾餐厨垃圾(Food Waste,FW)与纸类垃圾(Paper Waste,PW)为基质,通过中温(35℃)批次厌氧共发酵试验,探明不同配比的基质在厌氧共发酵4阶段(水解阶段、酸化阶段、乙酸化阶段、产甲烷阶段)的动力学特性,再结合挥发性脂肪酸(Volatile fatty acids,VFAs)在系统运行过程中的变化,确定FW与PW的最佳配比。结果表明,水解阶段是纸类垃圾的主要限速步骤,而VFAs积累限制了餐厨垃圾甲烷化进程的提高,且VFAs积累主要以丙酸与丁酸为主。当w(FW)≥35%时,产甲烷速率随VFAs质量浓度增大而线性减小,过高的VFAs质量浓度抑制了产甲烷菌的活性。FW与PW最佳基质配比为35∶65(质量比),在此条件下反应速率最为突出,系统运行高效,VFAs能及时被产甲烷菌利用,无有机酸积累,系统运行平稳。     

中温碱解预处理促进剩余污泥厌氧产甲烷的研究

采用4 mol/L NaO H碱液在中温下处理城市生活污水处理厂剩余污泥6 h,对比原剩余污泥和中温碱解污泥厌氧消化产甲烷的能力,分析了中温碱解及厌氧消化过程中剩余污泥胞内物质的释放规律,结果表明:碱解预处理有效促进了有机物、氨氮的释放,对磷酸盐释放促进作用不明显。原剩余污泥的沼气转化效率为387.5 L/kg(以VS计,下同),中温碱解处理组的沼气转化效率为402.5 L/kg;中温碱解处理组沼气转化效率比原剩余污泥组高3.87%;中温碱解预处理提高了污泥减量化程度及甲烷产量。改进的Gompertz模型结果表明:碱解处理后剩余污泥最大甲烷产量为1 480.7 mL,最大产甲烷速率为77.8 mL/d,细菌产甲烷的延迟时间为3.38 d。