共查询到20条相似文献，搜索用时 718 毫秒
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通过实验比较不同物性的液体在不同管径的换热管中的成膜流动情况,得到一种根据物性及工况条件选择换热管径的有效方法。不同配比的乙二醇水溶液有不同的密度、黏度及表面张力等物性,以此溶液为实验液体,进行垂直管内降膜冷模实验。观察记录不同流量下管内液膜流动稳定性,综合考虑液膜厚度等因素,选取最佳液膜流动状态。引入一个与黏度、表面张力、管内液膜流速有关的无量纲参数A,发现A值在(8.8~10.2)×10-2范围内时,管内液膜流动稳定、膜厚均匀、厚度适中。实践应用证明:根据A值范围选取换热管管径的方法是可行的。此方法为设计降膜式热交换器时选择管径提供了一种简便的新思路。 相似文献
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雷源才 《中学物理教学参考》1996,(7)
微小压强计的演示功能湖南省临武一中雷源才微小区强计主要是由一根Ｕ形玻璃管构成，管内注入适量的液体．若管内注入液体是密度较小的水或酒精，当Ｕ形管两边液面上存在较小的压强差时，两边液面将出现较明显的高度差，所以配合其它仪器可进行多种物理实验的演示．实验一... 相似文献
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《实验室研究与探索》2017,(10):31-35
对实验用板式精馏塔醇-水体系的实际操作效果与Aspen Plus软件模拟结果进行了对比分析,既从理论上推算实验用板式精馏塔的应用潜力,也实现了用实验数据对化工模拟软件的实际验证。首先在实验室中用内径68 mm、塔板数为10的筛板精馏塔对一定浓度的酒精溶液进行了连续精馏,获得了相关数据;然后用Aspen Plus软件对相同的体系进行了模拟计算,并把实测数据和模拟结果进行了对比分析。结果表明:实验测得的进出塔组成与Aspen Plus软件计算的组成有差别,但偏差处于合理范围之内。精馏段和提馏段的操作线、选用的实际回流比、实际的进料板位置与Aspen Plus软件计算结果比较符合。实验数据进一步验证了用Aspen Plus软件进行设计计算符合实际,结果可用。 相似文献
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李云倩 《现代远程教育研究》1994,(11)
一第六章蒸馏本章中要求重点掌握:双组分理想物系的气液相平衡,精馏原理,双组分连续精馏塔的计算及板式塔的简单结构、操作特性。一、双组分溶液的气液相平衡本节中重点掌握理想溶液的气液相平衡。 相似文献
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杜新满 《黄冈职业技术学院学报》2014,(2):95-97
目的通过分析人体心脏做功的过程及大小，为医学工作者提供更多的医学信息。近几年来．在高考物理试卷中偶尔见到这方面的近似计算题，也为这类问题提供理论依据。方法运用流体力学中实际液体的伯努利方程，分析在血液循环过程中，心脏做功的过程及其近似计算的方法。结果建立血液循环的物理模型，运用实际液体的伯努利方程进行分析，可以计算出人体心脏做功的大小。结论掌握和理解心脏做功的过程和计算方法．对预防心血管疾病的发生有重要的意义。 相似文献
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连通器中液面的高度差与连通器的构造、液体种类（同种或多种）、连通器中液面气体压强以及连通器的运动状态有关，不同的条件可得出不同的结论。１ 连通器静止，管口敞开与大气相接。且管内只有一种液体此时，各液面高度差为零（分析略）。２ 连通器静止且敞口，管中装有两种不相混的密度不同的液体如图（１），Ａ管中装有密度ρＡ的液体，Ｂ管中装有密度为ρＢ的另一种液体，且ρＡ＞ρＢ。由于同一静止液体在同一水平面上各处压强相等，我们可以取两液的界面处水平面为参考面，在Ａ管中取ａ点，Ｂ管中取ｂ点，则有Ｐａ＝Ｐｂ。由于Ｐａ… 相似文献
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CO还原CuO是初中化学中的一个重要实验。其操作步骤可简化为：一验纳二通气三加热四撤灯五停气。操作时应注意以下问题：1．在通入CO前,必须先检验纯度。CO为可燃性气体,若不纯,加热时可能发生爆炸。2．开始实验时,一定要向盛有CUO的玻管里先通CO一会儿,然后才能加热。这是为了排净玻管内的空气,避免CO与玻管内热的空气混合而可能发生爆炸的危险。3．玻管里的CllO要平铺于玻管内,以增大与CO的接触面积,使反应更快更完全。4．加热时,应先使玻管预热均匀,再把灯焰对着Cllo的部位加热,以免玻管受热不均匀而炸裂。5．实验完… 相似文献
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1．在解决问题的过程中，经历自主探索，并尝试将分步计算改写成不带括号的两级混合运算的过程。
2．理解两级混合运算的顺序，会进行两级混合运算。 相似文献
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Axialmixing ,or“longitudinaldispersion”and“backmixing”interminology,isanimportantnon idealflowphenomenoncommonlyoccurringinchemicalengi neeringprocess,suchasdistillation ,absorption,extrac tion,etc.Thisphenomenonrepresentsadeviationfrompistonflowandusuallyformsaparabolicaxialconcentra tionprofilealongtheflowdirection.Theunfavorableef fectofaxialmixingisthatitdecreasesthemasstransferdrivingforcesandfinallyleadstopoorerseparationeffi ciency.Instructuredpackedtower,althoughtheaxialmixingcanbe… 相似文献
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In this paper, the characteristics of fluid mixing time in a novel extra-loop fluidized bed were studied. The results showed that the mixing time was shortened with the increase of fluid velocity. All the discrete numbers of the reactor were above 0.2. The serial number n was 2.5 -3.0. It was judged accordingly that the reactor fluid state was continous stirred tank reactor （CSTR） mainly. When the inspiratory capacity increased the mixing time of the reactor was shortened. Thus the air input was beneficial for the fluid mixing. During the three phases mixing process, the mixing time of the reactor could be decreased by the n increase of carrier and air loading together, but the change was not significant. The parameters affecting the reactor fluid state were fluid velocity, inspiratory capacity and carrier. KLa could be increased with the air loading increase, and at the same gas/liquid ratio when the pressure drop was high, KL~ value was increased. The amount of carrier complex influence on KLa. As the carrier loading continued to increase, its value had been dropped but the changes was not significant, and optimization condition was found at above 800 1 000 g carrier loading （pouzzolane） or 600 g PVC. Under gas/liquid ratio of 0.8% -5.2%, KLa was （0.62-1.37）×10^-2· s^-1. 相似文献
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气升式内环流反应器的液相流动混合模型 总被引：1，自引：0，他引：1
1Introduction Internalairliftloopreactor(AL)[1],originatedfrom bubblecolumn(BC)[2],isanefficientreactor.Itsspe cialsuperiorties,suchasthesimplicityofitsdesign andbettertransportrates,makeitveryattractivein fermentationengineering,wastewatertreatmentand cellsculture.Asisknown,themixinglevelofthe fluidisdirectlyaffectedbytheflowcharacteristicsof liquid.Thetwo phaseflowinreactorisverycomplex andincompletemixingbecauseofbackmixing,dead zone,bypassandtime lapse.Generally,theresearch isbasedontwoi… 相似文献
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RH和RH-KTB精炼过程中钢液流动和混合特性的研究 总被引：7，自引：0，他引：7
The flow and mixing characteristics of molten steel during the vacuum circulation refining,including RH(Ruhrstahl-Heraeus) and RH-KTB(Ruhrastahl-Heraeus-Kawasaki top blowing) processes,were investigated on a 1/5 linear scale water model of a 90t multifunction RH degasser,The circulation rate was directly and more accurately determined,using a new method by which the more reliable results can be obtained.The fluid flow pattern and flow field in the ladle were demonstrated,observed and analyzed.The mixing time of liquid in the ladle was measured using electrical conductivity method.The residence time distribution in the RH model was obtained by tracer response technique.The influence of the main technological and geometric factors,including the gas top blowing*(KTB) operation,was examined.The results indicated that the circulation rate of molten steel in the RH degasser can be fairly precisely calculated by the formula:Q1p=0.0333Qg^0.26Du^0.69Dd^0.80(t/min),where Qg-the lifting gas flow rate(NL/min);Du and Dd-the inner diameters of the up and down-snorkels(cm),respectively.The maximum value of circulation rate of molten steel in the case of the 30cm diameters either of the up-and down-snorkels for the RH degasser(the “Saturated” rate) is approximately 31 t/min.the corresponding gas flow rate is 900NL/min.Blowing gas into the vacuum chamber through the top lance like KTB operation does not markedly influence the circulatory flow and mixing charateristics of the RH process under the conditions of the present work.There exist a major loop and a large number of small vortices and eddies in the ladle during the RH refining process.A liquidliquid two-phase flow is formed between the descnding stream from the down-snorkel and the liquid around the stream.All of these flow situation and pattern will strongly influence and determine the mixing and mass transfer in the ladle during the refining.The correlation between the mixing time and the stirring energy density is τmε^0.50 for the RH degasser.The mixing time rapidly shortens with an increase in the lifting gas flowrate.At a same gas flow rate,the mixing times with the up-and down-snorkel diameters either of 6 and 7cm are essentially same.The 30cm diameters either of the up-and down-snorkels for the RH degasser would be reasonalble.The concentration-time curve showed that three circulation cycles are at least needed for complete mixing of the liquid steel in the RH degasser. 相似文献
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The batch extractive distillation (BED) process has the advantages of both batch and extractive distillation. It is one of the most promising means for the separation of azeotropic and close-boiling point systems. However, so far this process has not been applied in industry due to its over-complexity. A new shortcut model was proposed to simulate the operation of the batch extractive distillation operations. This algorithm is based on the assumption that the batch extractive distillation column can be considered as a continuous extractive distillation column with changing feed at any time. Namely, the whole batch process is simulated as a succession of a finite number of steady states of short duration, in which holdup is considered as constant mole. For each period of time the batch extractive distillation process is solved through the algorithm for continuous extractive distillation. Finally, the practical implementation of the shortcut model is discussed and data from the laboratory and literature are presented. It is found that this model has better adaptability, more satisfactory accuracy and less calculative load than previous rigorous model. Hence the algorithm for simulating BED is verified. 相似文献
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多物料混合放热反应系统的设计与实现对化工、食品、医疗、冶金制药等行业具有一定的应用价值。反应器中涉及的温度、压力、液位、催化剂及抑制剂等变量直接关系着反应的转化程度及生产安全,因此对被控对象在进行工艺特性分析基础上设计了DCS控制系统,采用西门子PCS7软件与SMPT1000实验仿真设备探究系统可行性,并利用PCS7集成的WinCC完成监控画面组态。通过在半实物仿真实验装置上进行调试,系统满足了控制工艺要求并提高了控制精度。 相似文献
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严涛 《福建工程学院学报》2012,(4):318-321
从钻进成孔搅拌、提钻杆复喷、张拉锚索3个层面,描述了某基坑支护工程预应力旋喷搅拌锚桩技术,并通过基坑坡顶水平位移和坡顶沉降监测,结果说明,自钻式预应力旋喷搅拌锚桩加冲钻孔灌注围护桩的基坑支护形式,具有基坑开挖施工便捷、基坑边位移小和总体造价低等优点,在周边场地允许的情况下,对于大跨度深基坑支护有很好的适用性和经济性。 相似文献
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A coal slurry mixing tank is a key piece of equipment in the preparation of coal slurry for direct coal liquefaction.It is a gas-liquid-solid three-phase mixing device.Based on the performance of the existing coal slurry mixing equipment,a type of test equipment for horizontal continuous coal slurry preparation was developed,but to this point has limited research results.The test equipment consists of a mixing cylinder,mixer,stirring impeller and other components.Slurry mixing experiments were undertaken using the prototype,testing the performance of the device.A mathematical model was proposed specifically for the operation of a coal slurry mixing tank that is horizontally operated with high slurry concentration and rotary flow.The flow field in the horizontal coal mixing tank was simulated with the computational fluid dynamic （CFD） method.The experimental results match well with the CFD simulation results.Results show that the test device of a coal slurry mixing tank can be used to model the mixing of pulverized coal and the solvent oil.A strong correlation was obtained. 相似文献
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A new empirical correlation has been presented for the effect of entrainment on distillation tray efficiency based on the results of numerical solution given by Lockett,et al.The calculated results are in good agreement with those of the numerical solution given by Lockett,et al.The average deviation is 1.14% and the maximum deviation is 4.76% for the ranges of 0相似文献
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马俊林 《十堰职业技术学院学报》2000,13(2):10-15
探讨了环管反应器中高粘度催化剂的混合特征，研究了液体循环速率、催化剂粘度对混合过程的影响，并对混合过程进行了观察分析，建立了该过程的教学模型，模型值和实验值吻合较好。 相似文献