共查询到20条相似文献,搜索用时 109 毫秒
1.
2.
生物质高温分解产物析出特性的试验研究 总被引:1,自引:0,他引:1
采用TG/MS联用仪对3种典型生物质(玉米秸秆、玉米芯和稻秆)在高温分解过程中气相产物的析出特性进行了试验研究,分析了温度、升温速率、氧浓度、生物质种类对其的影响.结果表明:轻质组分的析出集中于挥发分大量热解的温度区域,而焦油组分的析出没有明显的温度窗口;升温速率对各产物析出的影响有限,随着升温速率的增大,挥发分析出特性指数增大,活化能降低,更易于产物析出;有氧环境更有利于热解温度区产物的析出,相比有氧条件下氧浓度的改变,产物的析出对有、无氧更敏感;3种生物质的产物析出量受挥发分含量的影响由大到小依次为:稻秆>玉米芯>玉米秸秆. 相似文献
3.
《热能动力工程》2017,(4)
以城市污泥为研究对象,考察了其在不同升温速率下的热解特性、热解反应动力学特征以及重金属Pb和Cd在热解过程中的迁移规律。通过热解失重曲线图得出,污泥的热解过程可分为水分析出阶段、挥发分析出阶段和半焦分解阶段。提高升温速率会导致污泥的失重量减少,挥发分最大失重速率增加。根据Coats-Redfern积分法计算结果得到,挥发分析出的第1阶段和第2阶段的反应级数分别为1和2,且不同升温速率下挥发分析出的第1阶段和第2阶段下的活化能总体上变化不大。通过管式炉热解实验可知,在热解温度为400、500、600和700℃范围内,重金属Pb和Cd的残留率随热解温度的升高均表现为先上升后下降的规律。Cd的残留率在热解温度为500和700℃时分别达到最高(41.64%)和最低(2.92%),而Pb的残留率随温度变化不大,均为93%以上。热解温度为400~500℃,Cd和Pb挥发较少。 相似文献
4.
选取石化污泥和烟煤,将两者按不同比例混合。采用热重分析法,在相同升温速率下,对各混合样品进行热解实验,探讨石化污泥与烟煤热解特性的差异及其共热解时石化污泥对烟煤热解过程的影响。结果表明:石化污泥与烟煤的热解过程和反应特征参数差异很大,主要表现在样品的挥发分析出温度区间、总失重率及失重速率上。同时,石化污泥的挥发分综合释放特性指数D远优于烟煤;在石化污泥和烟煤的共热解过程中,石化污泥的添加对烟煤的热解起到一定促进作用,当石化污泥掺入比例为10%时,混合物的热解特性最好。 相似文献
5.
6.
《可再生能源》2021,39(9)
采用热重分析法对市政污泥、木屑及其不同比例的混合样品热解特性进行了分析,研究了升温速率和混合比例对热解过程的影响。对污泥和木屑进行单独热解时,木屑比污泥的反应活性更高;随着升温速率的增大,二者的挥发分析出指数D均有增大,但升温速率对污泥挥发分析出的影响更大;污泥与木屑共热解改善了污泥热解过程的综合热解释放特性,有利于热解反应的进行;随木屑添加比例的增加D值呈指数增长,在木屑添加比例为80%时,D达到最大值118.18×10-8,但仍低于理论值141.67×10-8,说明存在竞争作用。文章采用FWO(Flynn-Wall-Ozawa)和Starink方法,分别计算木屑添加比例为80%的共热解表观活化能。当转化程度α为0.1~0.8时活化能变化较小,α为0.9时活化能分别突增到761.64,786.12 kJ/mol。这说明共热解过程可分为150~520℃和520~1 000℃两个温度阶段,与污泥单独热解相比,降低了转化率达到90%时的终温。 相似文献
7.
生物质加压热重分析研究 总被引:12,自引:0,他引:12
对两种生物质木屑和松针进行了不同压力和升温速率下的热重分析试验,通过生物质热重失重率(TG)和失重速率(DTG)曲线,获得了相关热解特性参数,提出了生物质的挥发分综合释放特性指数D.并通过热分析数学方法求取了生物质热解动力学参数.试验结果表明,氮气气氛中,木屑与松针常压和增压下主要热解阶段可认为两段一级反应;热解压力的提高,将延迟生物质挥发分初析温度和DTG峰值温度,降低最大析出率和DTG峰值,生物质的挥发分综合释放特性指数D也减小,增加了生物质挥发分的析出难度,并改变了热解反应活化能和频率因子.同一压力下,提高热解升温速率,生物质综合特性指数D将增加. 相似文献
8.
采用热重分析法对1种煤样(C)和2种城市污水污泥(S1和S2)及其混合试样进行了燃烧特性试验研究.结果表明:污泥的失重主要为挥发分的析出与燃烧,升温速率提高有助于污泥的快速处理及热能的利用,但总失重率较小,减量化较差;污泥与煤样的混烧特性从总体上表现为污泥和煤样共同作用的结果,随着污泥所占比例的增加,试样的着火温度逐渐降低;当污泥的掺烧比为25%左右时,综合燃烧性能最好.采用Freeman-Carroll微分法确定污泥与煤混烧过程中化学动力学参数,结果显示污泥在温度较低时更易于反应,而煤则表现出相反的性质.根据对不同掺烧比下污泥燃烧性能参数及化学动力学等方面的分析,得出污泥S2更适合燃烧处理. 相似文献
9.
印染污泥与木屑混燃特性及动力学 总被引:3,自引:0,他引:3
采用综合热重分析法,在不同升温速率及印染污泥与木屑不同比例混合条件下,对印染污泥、木屑及其混合物的燃烧特性进行了研究.结果表明,印染污泥的热重曲线存在4个明显的失重峰,分别与水分的析出、两个挥发分的析出以及固定碳的燃烧阶段相对应.混合试样燃烧过程中,污泥和木屑基本保持各自的挥发分析出特性,其燃烧曲线位于污泥和木屑燃烧曲线之间,且混合试样微熵热重曲线的变化趋势与组成比例较大的成分DTG曲线变化趋势较为接近.污泥与木屑混合后其综合燃烧特性指数SN有所增大,说明挥发分含量越高对应的燃烧特性越好;采用积分法(Coats-Redfern方程)计算得到各阶段燃烧反应的机理方程及相应的活化能参数,分析表明单一印染污泥燃烧的活化能较低,活化能的大小与试样的燃烧阶段是相对应的. 相似文献
10.
11.
《International Journal of Hydrogen Energy》2022,47(63):26789-26797
The issues related to the reliability of hydrogen engines of unmanned vehicles and increasing the efficiency of using hydrogen as fuel when using the method of its production during the decomposition of hydrogen-containing molecules of liquid-phase organic compounds in a plasma discharge under the action of intense ultrasonic exposure are considered. Experiments have shown that as a result of decomposition in the acoustoplasma discharge of liquid hydrocarbons, solid-phase carbon-containing products are formed, chemical transformations occur in the liquid phase and hydrogen-containing combustible gas is formed. Hydrogen-containing gas can be used as fuel immediately after synthesis, i.e. it does not require separation, since in addition to hydrogen it contains only impurities of CO2 and water vapor. The purpose of the study is to formalize the basic conditions for tightening the control of mutual compliance with the efficiency of hydrogen engines of the same series in the conditions of their mass production. Methods of mathematical statistics and hardware-software modeling were used in the study. The term “unerroric of quality mutual compliance control” is introduced to describe a set of hardware and software tools for such control. The principle of in-depth testing of the technical condition of such engines of one series is described in a multidimensional formulation of the quality control problem for three of their operating parameters at once. The conditions for increasing the mutual correspondence of the measured values of such parameters in the conditions of serial production of hydrogen engines are formalized. 相似文献
12.
13.
14.
Linear and nonlinear analyses of the instabilities and distortion of liquid streams injected into a gaseous media are discussed. The various fundamental mechanisms and the predictive capabilities for the distortions are emphasized. Round jets, planar sheets, annular sheets, and conical sheets are discussed in detail. The balance between capillary and inertial forces is primarily examined. The method for simplifying the analyses in the case of thin liquid sheets is discussed. The capabilities for representing the droplet size distribution that follows the stream disintegration are outlined. 相似文献
15.
基于《水工混凝土掺用氧化镁技术规范》中的Ⅰ型氧化镁(MgO),研究了该型MgO膨胀剂(MEA)细度对掺粉煤灰水泥浆体膨胀性能的影响。即采用X射线衍射分析(XRD)及同步热分析(TG DSC)分析了掺MEA水泥浆体中MgO的水化性。结果表明,养护温度相同时,MEA的细度对水泥浆体内MEA中MgO的水化和水泥浆体的膨胀无显著影响,产生的膨胀均能补偿水泥浆体的收缩;MEA的细度可从试验设计采用的45 μm筛筛余15%左右增加到30%左右,这将有利于MEA生产企业的节能降耗。 相似文献
16.
使用ANSYS8.0软件对高速列车车轮进行了三维有限元分析,计算出车轮在直线、曲线和道岔条件下牵引、制动共6种工况时孔边薄弱部位的应力,分别通过Mises等效平均应力方法、Sines平均主应力方法和应力分量中考虑平均应力方法计算出应力在极值位置时的等效应力幅、等效平均应力,从而进一步算出车轮的安全系数,对其疲劳强度进行评定,并对3种方法进行了比较研究。 相似文献
17.
M.R. Salimpour M. SharifhasanE. Shirani 《International Communications in Heat and Mass Transfer》2011,38(1):93-99
This paper documents the geometric optimization of an array of circular and non-circular ducts. The optimization was carried out numerically using finite volume method. As optimal dimensions were independent of the array configuration, the numerical simulation was performed on a unit cell. Numerical optimization for circular, square and isosceles right triangle cross-sections of channels was performed. Based on the results of this investigation, some correlations were proposed to predict the optimal hydraulic diameter and dimensionless heat transfer per unit volume. In addition to examining the effect of pressure drop on these parameters, it was showed that among the different geometries of this study, square cross-section has the most efficiency for a given volume. The numerical results of the present study were compared with approximate results reported in the literature which a good agreement was observed. 相似文献
18.
General expressions for the heat of vaporization of mixtures at constant pressure; at constant temperature; and at constant pressure, temperature, and composition are proposed. The last one is related to the liquid-vapor interface where steady vaporization or condensation is taking place. Numerical examples by the proposed expressions are shown for binary mixtures of HCFC22(R22) and (HCFC123(R123) © 1997 Scripta Technica, Inc. Heat Trans Jpn Res, 25(1): 12–24, 1996 相似文献
19.
本文对漫灰均温物体在常物性条件下对外辐射传热的Yong值计算建立了数学模型。通过与物体内能Yong公式的数值计算比较,得出了辐射能量的Yong值不大于内能Yong值的结论。从初步的热射Yong值计算公式发现。Yong与物体表面辐射率有关。 相似文献