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1.
针对磁流化床中颗粒浓度高,相互作用强的特点,在双流体模型的基础上,引入颗粒流的动力学理论,对床内铁磁颗粒在不同工况下的流化特性进行数值模拟.计算结果表明:在无磁场或弱磁场作用下,床内多处产生气泡,颗粒呈鼓泡流化状态;在适度磁场作用下,磁场对颗粒的作用明显,可以抑制床内气泡生成,实现颗粒的稳定流化.增大气体表观流速比后,磁场的调节作用相对减弱,颗粒不能实现稳定流化.与试验数据比对,二者吻合较好,数值模拟结果较好地反映磁流化床中颗粒的流化行为.  相似文献   

2.
使用一种由磁场辅助控制流化的新型流化床反应体系——磁稳定床来进行生物质焦油模型化合物甲苯的水蒸气催化重整.为达到磁稳定床的效果,采用共沉淀-浸渍两步法,合成出具有磁性的Co-Fe/Al_2O_3催化剂.通过扫描电子显微镜(SEM)、X-射线衍射(XRD)、N_2吸脱附(BET)对催化剂进行表征.对催化剂进行冷态试验,确定其磁稳定床操作区间;之后在同一工况下使用同种催化剂,分别于固定床、流化床、磁稳定床内进行催化活性及稳定性测试;最后使用SEM、热重(TG)对催化剂进行表征,探讨其表面积碳.结果显示:在650℃、载气流量为320m L/min、水蒸气与碳的摩尔比为1.4的工况下,磁稳定床催化效率高达96.4%,高于固定床的82.6%以及流化床的86.6%;同时,磁稳定床与流化床积碳轻微,而固定床催化剂表面积碳较为严重,且有明显烧结现象.  相似文献   

3.
基于磁致伸缩材料模型,在不考虑体积伸缩的条件下,利用FEMLAB多物理场耦合软件,对悬臂铁磁板在横向磁场中的磁弹性屈曲问题进行了数值模拟,并将模拟得到的临界屈服磁感应强度与前人的实验结果进行了对比,得到了较好的一致性。数值模拟结果显示,随着铁磁板长厚比的增大,板屈曲失稳的临界屈服磁感应强度减小;采用的磁致应变系数越大,所得到的临界屈服磁感应强度越小;当磁致应变系数为1.3×10-4T-1时,计算结果与实验值吻合最好。数值分析结果表明,利用磁致伸缩材料模型来解释悬臂铁磁板在横向磁场中的磁弹性屈曲问题是合理的。  相似文献   

4.
在流化床模型实验台上使用萘升华热质类比技术对气粒两相间的传热特性进行了实验研究。实验考查了流化床床料重量、流化风风速和床料平均粒径对气体与颗粒间换热的影响,实验结果表明。在其它条件相同的情况下,流化床内气体和颗粒两相之间的表观传热传质系数随着流化风速的加大和床重的增加而增大,随着床料颗粒粒径的增加而减小。  相似文献   

5.
循环流化床烟气脱硫实验研究   总被引:5,自引:0,他引:5  
在中试装置中进行了循环流化床烟气脱硫的实验研究。该实验装置由燃烧器、高4.5m直径0.30m的反应器、旋风分离器、给料系统和物料回送系统组成。烟气流量和渡分别为200-325m^3/h和120-180℃。实验结果表明绝热饱和温差(△θ)、钙硫物质的量比(n(Ca)/n(S)、SO2进口质量浓度(ρin)和床内固定颗粒物质量浓度(ρs)对脱硫效率有较大的影响,而气体停留时间(t)的影响不明显。用石灰浆作脱硫剂,当△θ=14℃、n(Cn)/n(S)=1.5,ρin=1500mg/m^3、ρs=6kg/m^3,t=3.5s时,脱硫产率达85.3%。工业应用中△θ应控制在10-2℃。  相似文献   

6.
通过对气固流化床乳化相中颗粒群结构的进一步认识,建立了颗粒间的辐射换热模型,比较了不同颗粒直径、不同床层温度水平及不同流化工况下颗粒间辐射换热与通过气膜导热份额的大小,并预测了流化床反应器中反应颗粒与惰性床料之间的温差,对于流化床反应器选择合理的运行工况和进行操作参数优化具有参考价值.  相似文献   

7.
分别选用石英砂颗粒和高铝矾土颗粒作为循环流化床的床料,棉杆作为燃料,在0.2MW循环流化床上进行实验.实验结果表明,石英砂颗粒床料容易形成结渣,而高铝矾土颗粒床料使用情况良好.通过对长时间运行后的床料颗粒进行XRF和SEM/EDS分析,发现2种床料运行后的化学成分发生改变,随着运行时间的延长,碱金属在床料中富集度越来越高.通过对反应前后内部结构和成分进行比较,发现石英砂床料结渣主要是因为在颗粒的表面生成了低熔点的化合物,在高温条件下床料由于表面层相互粘结而产生结渣,而高铝钒土颗粒可以有效地防止低熔点化合物的生成,从而减少结渣.  相似文献   

8.
气固流化床颗粒间辐射换热模型   总被引:2,自引:0,他引:2  
通过对气固流化床乳化相中颗粒群结构的进一步认识,建立了颗粒间的辐射换热模型,比较了不同颗粒直径、不同床层温度水平及不同流化工况下颗粒间辐射换热与通过气膜导热份额的大小,并预测了流化床反应器中反应颗粒与惰性床料之间的温差,对于流化床反应器选择合理的运行工况和进行了操作参数优化具有参考价值。  相似文献   

9.
为研究铁磁材料的应力致磁各向异性的物理表现及其对应力的定量检测特性,搭建了交流磁化/检测实验装置.在单向加载条件下,对铁磁Q195平板试件施加了不同程度的弹性应力.并在保持每个弹性应力方向及大小不变前提下,施加了不同方向的不饱和交流外磁场,检测了其交流磁化曲线.通过对实验数据的频谱分析、磁滞回线的获取及磁特征参数的提取,分析和讨论了铁磁材料应力致磁各向异性定量特性、磁各向异性特征参数与应力的定量关系.研究结果表明:应力导致了铁磁Q195钢材表现出了磁各向异性特性;应力致磁各向异性磁特征参数随着应力增大而近似于线性增大,可以通过提取对应的参数进而求取对应的应力.研究结果对系统探究铁磁材料的应力致磁各向异性定量特性具有一定参考价值.  相似文献   

10.
采用循环流化床烟气脱硫技术,以钢铁企业烧结机烟气为脱硫对象,在一台处理烟气量5000m3/h的试验装置上开展工业性试验,分析研究喷雾增湿对脱硫性能的影响.研究结果表明:在本试验烟气温度范围内,烟气温度90℃以下时以喷水蒸气为宜,90℃以上时以喷水为宜,喷水有利于提高脱硫效果和钙利用率;在流化床入口前喷雾增湿时,有利于流化床的运行稳定和提高脱硫效率;出口烟气温度下降到70℃左右时,CFBA系统的脱硫效率达到90%以上.  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

15.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

16.
Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.  相似文献   

17.
以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.  相似文献   

18.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

19.
Quality traits in wheat (Triticum aestirum L.) were studied by quantitative trait locus (QTL) analysis in a recombinant inbred line (RIL) population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross (ChSh). Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.  相似文献   

20.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

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