柴油/甲醇组合燃烧(DMCC)减少重载柴油机烟度排放的试验研究

在一台满足国三排放法规要求的重载车用增压中冷电控单体泵柴油机上,将其改造成柴油/甲醇组合燃烧(DMCC)发动机并进行台架试验.利用电控单元控制向进气歧管喷射的甲醇量及其喷射时刻,原柴油机供油系统保持不变.试验主要研究在稳定工况时,不同的负荷以及不同的甲醇对柴油的比例情况下,经催化转化后发动机干炭烟烟度(415烟度)和不透光烟度(439烟度)排放的情况.试验结果表明,在燃用现有市售的燃油条件下,与原机相比,相同工况下采用DMCC的干炭烟烟度和不透光烟度都有大幅度的减少.干炭烟的最大降幅达95%,平均降幅达到50%以上.在柴油喷射量不变的情况下,增加甲醇喷射量,干炭烟烟度会持续减小,而不透光烟度呈先减少后增加的趋势.同负荷时的甲醇对柴油替代率为44.88%到56.73%时,不透光烟度存在最低点,并且发动机的烟度排放存在最优值.在同一工况下,随着柴油对甲醇的比例增加,发动机的干炭烟烟度和不透光烟度排放都逐渐增加.     

Sorption mechanism of naphthalene by diesel soot: Insight from displacement with phenanthrene/p-nitrophenol

The nonlinear sorption of hydrophobic organic contaminants (HOCs) could be changed to linear sorption by the suppression of coexisting solutes in natural system, resulting in the enhancement of mobility, bioavailability and risks of HOCs in the environment. In previous study, inspired from the competitive adsorption on activated carbon (AC), the displaceable fraction of HOCs sorption to soot by competitor was attributed to the adsorption on elemental carbon fraction of soot (EC-Soot), while the linear and nondisplaceable fraction was attributed to the partition in authigenic organic matter of soot (OM-Soot). In this study, however, we observed that the linear and nondisplaceable fraction of HOC (naphthalene) to a diesel soot (D-Soot) by competitor (phenanthrene or p-nitrophenol) should be attributed to not only the linear partition in OM-Soot, but also the residual linear adsorption on EC-Soot. We also observed that the competition on the surface of soot dominated by external surface was different from that of AC dominated by micropore surface, i.e., complete displacement of HOCs by p-nitrophenol could occur for the micropore surface of AC, but not for the external surface of soot. These observations were obtained through the separation of EC-Soot and OM-Soot from D-Soot with organic-solvent extraction and the sorption comparisons of D-Soot with an AC (ACF300) and a multiwalled carbon nanotube (MWCNT30). The obtained results would give new insights to the sorption mechanisms of HOCs by soot and help to assess their environmental risks.     

过渡金属掺杂对镧锡烧绿石催化碳烟燃烧性能的影响

催化燃烧是去除机动车排放碳烟颗粒物的有效方法之一.利用CTAB辅助法制备了不同过渡金属掺杂的镧锡烧绿石型La_2Sn_(1.8)TM_(0.2)O_7(TM为Sn、Mn、Fe、Co和Cu)复合氧化物催化剂.采用XRD、氮气吸脱附、SEM、FT-IR、H2-TPR和荧光光谱(PL)等手段表征了催化剂的理化性质,采用程序升温氧化(TPO)技术评价了其催化碳烟燃烧的活性.研究发现,催化剂经900℃焙烧后呈球形形貌,具有相对较大的比表面积(~20 m2·g~(-1)).低价过渡金属离子的掺杂使氧空位的整体浓度增加,有利于催化剂活化吸附氧分子,改变材料的氧移动和氧化还原性能.富氧气氛下,少量过渡金属掺杂提高了烧绿石催化碳烟燃烧的活性和选择性,这与氧空位浓度的增加以及氧化还原能力的提高有关,其中Co-LSO具有较好的催化性能,起燃温度(T10)为379℃,CO_2选择性接近100%;NOx气氛存在可以进一步提升催化剂氧化去除碳烟的活性.利用等温反应和碳烟厌氧滴定实验进行了活性氧浓度的定量和反应动力学分析,并计算出富氧气氛下催化反应的转化频率(TOF),其中Co-LSO样品的TOF值最大为3.20×10~(-3)s~(-1),基于TOF的活性顺序与TPO法得到的起燃性能的结果基本一致.     

Modification of CeO2-ZrO2 catalyst by potassium for NOx-assisted soot oxidation

Potassium-modified ceria-zirconia catalyst was synthesized by wetness impregnation method.The ageing treatment was performed in static air at 800°C for 20 hr to evaluate the thermal stability of the catalyst.The catalysts were characterized by X-ray diffraction,BET surface area,oxygen storage capacity,NOx-temperature programmed desorption and soot-temperature programmed oxidation measurements.By introduction of potassium,the maximum soot oxidation rate temperature(Tm) of the ceria-zirconia based catalyst de...     

MnOx和CeO2催化剂在含NO气氛中氧化模拟碳烟的研究

用沉淀法制备了MnOx和CeO2两种催化剂并用于氧化模拟碳烟.XRD、BET、O2-TPD和NO-TPD表征结果表明,CeO2的比表面积和NOx吸附容量更大,而MnOx则具有更多的氧物种(晶格氧O2-).TPO结果表明,气氛中引入的NO明显促进了碳烟的氧化.在无催化剂、加入CeO2和MnOx3种情况下,模拟碳烟的起燃温度Ti分别降低了38、41和101℃.DRIFTs结果表明,催化剂活性氧物种和反应过程中生成的NO3-是NO促进碳烟燃烧的关键因子.可能的反应路径为:低温富氧条件下气相中的O2吸附在催化剂表面上,丰富的活性氧物种(如O2-、O2-f和O-)得到激活和转化,进而将弱吸附NO2和活性NO2*氧化成NO3-;在高温时则释放出活性很强的NO2*和O-,因而能促进碳烟氧化,其中间产物为碳氧复合物C(O).     

2008北京残奥会期间大气黑碳气溶胶污染特征

利用单颗粒黑碳光度计(SP2)对2008年残奥会期间北京市黑碳(BC)气溶胶的质量浓度、粒径分布及单颗粒混合态进行连续在线观测.结果表明:观测期间BC浓度均值为1.65μg/m3,低于往年同期水平;质量粒径分布呈单峰型,峰值位于207nm;内混态BC比例平均为56.1%,高于其他国内外城市,说明本地源排放贡献相对较小.随大气边界层高度及本地源排放变化,BC浓度在上午8:00和午夜0:00出现2个峰值,内混态BC比例日变化趋势与之相反.风向风速分析表明,残奥会期间来自五环外未限行区域的机动车排放对市区BC浓度有明显影响.     

ENSG-30000-125可调频高声强声波吹灰器除垢机理分析

目前国内燃煤电厂湿法烟气脱硫装置常因为GGH堵塞而被迫停运,为了解决这个问题,介绍了一种利用高声强声波吹灰器结合高压水冲洗,彻底解决GGH结垢堵塞的方法,并对高声强声波吹灰器的除垢机理进行了分析,认为高强声波的推拉作用可使换热器表面的硬垢因声致疲劳而松动、脱落,同时,降低灰垢在换热器表面的附着力。另外,针对强声波对GGH的机械作用力进行了平衡分析,认为在强声波环境下GGH运行是安全的。     

包头市大气污染对人群健康的影响

包头市环境污染属典型的煤烟型污染，是国内少数几个污染严重的城市之一。笔者以多年的大气环境监测数据为基础，结合居民环境流行病学调查，定性或定量地给出了大气污染对人体健康（多项指标）造成的危害。经研究发现，包头市大气污染已对市区居民健康状况产生明显影响，除造成居民健康慢性损害外，还加剧此等病的病情、加速死亡。     

Simultaneous catalytic removal of NOx and diesel soot particulate over perovskite-type oxides and supported Ag catalysts

A series of perovskite-type oxides and supported Ag catalysts were prepared,and characterized by X-ray diffraction (CRD)and x-ray photoelectron spectroscopy(XPS).The catalytic activities of the catalysts as well as influencing factors on catalytic activity have been investigated for the simultaneous removal of NOx and diesel soot particulate.An increase in catalytic activity for the selective reduction of NOx was observed with Ag addition in these perovskite oxides,especially with 5% Ag loading.This catalyst could be a promising candidate of catalytic material for the simultaneous elimination of NOx and diesel soot.     

铁合金厂烟尘治理设施改造与运行结果分析

通过对铁合金厂电熔炉烟尘治理设施的诊断监测，分析研究了收尘设施长期不能运行的主要原因，提出改造方案。收尘设施经过改造后实现了与生产设施的协调，对存在的问题提出了工程优化意见。