混空轻烃燃气露点测试分析及控制

面对我国能源供求上日渐突出的问题,以及石化行业副产物种类繁多、利用不充分的现状,混空轻烃燃气技术作为一种行之有效的解决方法被提出来。利用Aspen plus软件对混空燃气露点进行计算,并根据轻烃原料中各组分的含量模拟出露点与空气流量及输出压力之间的关系;当空气中含有水分时,模拟出露点与输入空气中水分含量之间的关系。得到空气占比的增大以及输送压力的降低均会降低燃气露点,总结上述模拟结果,给出混空燃气在制造及运输过程中的相关建议。     

民用混空轻烃燃气燃烧研究

混空轻烃燃气用于民用必须解决在灶具上的燃烧问题。通过计算比较混空轻烃燃气和12T天然气的各种燃烧特性参数以及在天然气灶具上的火孔出口流速和点火,分析混空轻烃燃气在天然气灶具上的燃烧。     

混空轻烃燃气制备过程中的安全性分析

混空轻烃燃气是一种新型燃气,由空气和经过加热气化的轻烃在混合器内混合制成。混合器内不均匀的浓度分布,会产生处于爆炸极限的区域,影响了制备的安全性。本文利用Fluent软件,对混空轻烃燃气在混合器内4种不同工况下的混合过程进行三维仿真计算,得到混合器内不同位置混空轻烃燃气的浓度分布情况,对流场中不同浓度分布下的爆炸危险性进行分析,并提出相应的改进措施,为解决混空轻烃燃气制备过程中潜在的安全性问题提供参考依据。     

混空轻烃燃气发生装置制气工艺研究

混空轻烃燃气发生装置的工作原理是向装有液态轻烃燃料的储罐内鼓入空气,液态轻烃蒸发附着在空气泡表面形成混空燃气.对混空轻烃燃气发生装置的工艺流程进行模拟,确定空气流量、液态轻烃温度以及气化器内液位是混空燃气制气过程中最大的影响因素,轻烃体积分数随空气流量的增大而减小,随外界输入热量、液态轻烃流量的增大而增大.根据轻烃鼓泡...     

混空轻烃燃气气体分布器数值模拟及结构优化

混空轻烃燃气发生装置的工作原理是向装有液态轻烃燃料的储罐内鼓入空气,液态轻烃蒸发附着在空气泡表面形成混空燃气,其中气体分布器对轻烃气化过程起着决定性的作用,是气化装置内的核心部件.建立轻烃气化装置分布器的三维数值模型,模拟分布器内气液两相流过程,并针对现有气体分布器结构存在的缺陷提出相应的优化方案,分别对分布器支管尺寸...     

生物质粗燃气自热重整调变的热力学分析

运用吉布斯自由能最小化方法对生物质粗燃气自热重整过程进行了热力学分析,研究了重整反应过程中的温度,O2/CH4摩尔比及焦油摩尔分数等因素对平衡产物组成的影响规律。研究结果表明:低温有利于CO歧化与加氢反应,而高温促进了CH4和CO2的转化,提高合成气H2+CO摩尔分数,降低H2/CO摩尔比。O2/CH4摩尔比的增加有利于生物质燃气从部分氧化反应向完全氧化反应转变,促进了CH4的重整反应而抑制了CO2的转化;O2/CH4摩尔比的增加降低了合成气H2+CO摩尔分数,降低了H2/CO摩尔比,在重整后的生物质粗燃气中,n(H2)/n(CO)≈1。积碳量随温度升高和O2/CH4摩尔比的增加逐渐减少,随着焦油(C10H8)物质的量的增加而增加。焦油物质的量增加提高了合成气中H2与CO摩尔分数,是重整反应的重要原料。优化的生物质燃气自热重整反应条件为温度1 023 K,O2/CH4摩尔比0.7,焦油摩尔分数<1%。     

9F级燃气—蒸汽联合循环电厂空冷凝汽器与水冷凝汽器对全厂效率的技术及经济性影响对比分析

为分析空冷凝汽器(ACC)与水冷凝汽器对于9F级燃气—蒸汽联合循环电站全厂经济性指标的影响,通过引用9F级燃气—蒸汽联合循环电站方案的相关参数,建立ACC与水冷凝汽器方案对比分析模型。通过理论分析,并与实际项目方案和运行电站的经济性指标对比,验证了理论分析模型的可靠性。理论分析结果表明,ISO环境条件、纯凝无抽汽的工况下,采用ACC的9F燃气-蒸汽联合循环的全厂毛效率约为57.3482%~57.7869%,而采用水冷凝汽器的9F燃气-蒸汽联合循环的全厂毛效率约为58.4662%。ACC方案相对水冷凝汽器方案全厂效率降低约为0.6793%~1.1180%。     

液化天然气过程的热力学分析

利用R K S方程建立了天然气和液化天然气焓火用计算的热力学模型;对 2×104 m3 /d液化天然气液化过程进行了模拟计算;计算了各设备的火用损失和液化过程的火用效率;热力学计算分析结果表明,装置的最大火用损环节是循环压缩机,其次是透平膨胀机和气波制冷机。本装置利用自身所产尾气作为燃气发动机的燃料,进而利用燃气发动机带动循环压缩机,节省了大量电能,回收了排放尾气的能源,有效地解决了压缩机的高能耗问题。     

Nucleation curves of model natural gas hydrates on a quasi‐free water droplet

Heterogeneous nucleation probability distributions of gas hydrates on a water droplet that was supported by inert and immiscible perfluorocarbon oil, perfluorodecalin is studied. The guest gas used was a mixture of 90 mol % methane and 10 mol % propane. The probability distribution was measured using a high pressure automated lag time apparatus under the guest gas pressure range of 6.7–12.5 MPa and the cooling rate range of 0.002–0.02 K/s. Nucleation curves were derived for unit area of water surface. The nucleation rate per unit area of water surface that was contained in a glass sample cell, which differed significantly from that on a quasi‐free water droplet, is also derived. It is concluded that the nucleation curves in the presence of a solid wall should be normalized to the unit length of the three‐phase line at which water, guest gas, and the solid wall meet. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2611–2617, 2015     

Analysis of supersaturation and nucleation in a moving solution droplet with flowing supercritical carbon dioxide

A supercritical antisolvent (SAS) process is employed for production of solid nanoparticles from atomized droplets of dilute solution in a flowing supercritical carbon dioxide (SC CO₂) stream by attaining extremely high, very rapid, and uniform supersaturation. This is facilitated by a two‐way mass transfer of CO₂ and solvent, to and from the droplet respectively, rendering rapid reduction in equilibrium solubility of the solid solute in the ternary solution. The present work analyses the degree of supersaturation and nucleation kinetics in a single droplet of cholesterol solution in acetone during its flight in a flowing SC CO₂ stream. Both temperature and composition are assumed to be uniform within the droplet, and their variations with time are calculated by balancing the heat and mass transfer fluxes to and from the droplet. The equilibrium solubility of cholesterol with CO₂ dissolution has been predicted as being directly proportional to the Partial Molar Volume Fraction (PMVF) of acetone in the binary (CO₂–acetone) system. The degree of supersaturation has been simulated up to the time required to attain almost zero cholesterol solubility in the droplet for evaluating the rate of nucleation and the size of the stable critical nuclei formed. The effects of process parameters have been analysed in the pressure range of 7.1–35.0 MPa, temperature range of 313–333 K, SC CO₂ flow rate of 0.1136–1.136 mol s^?1, the ratio of the volumetric flow rates of CO₂‐to‐solution in the range of 100–1000, and the initial mole fraction of cholesterol in acetone solution in the range of 0.0025–0.010. The results confirm an extremely high and rapid increase in degree of supersaturation, very high nucleation rates and stable critical nucleus diameter of the order of a nanometre. Copyright © 2005 Society of Chemical Industry     

表面活性剂在瓦斯水合物生成过程中的热力学作用

在实验研究基础上,结合表面活性剂水溶液中瓦斯水合物生成微观机理,提出了表面活性剂改变水合物生成热力学条件物理作用假说,认为表面活性剂胶束对溶于其中的气体分子和吸附于其周围的水分子的束缚作用,相当于降低了体系的温度.利用T40（0.001 mol·L^-1）、T40（0.002 mol·L^-1）、T40/T80（0.001 mol·L^-1）分别组成的3种气 液 煤 水合物反应体系实验测定了水合物生成时的相平衡参数,与同样温度和压力条件下相平衡计算值比较,结果表明,表面活性剂的加入有效地改变了水合物生成的热力学条件.例如,在T40/T80（0.001 mol·L^-1）实验体系中,当压力为22.67 MPa时,水合物生成相平衡温度为22.6℃,比纯水中提高2.1℃.     

Driving force in first-order phase transitions and its application to gas hydrate nucleation from a single phase

Classical nucleation theories of general application are taken as starting point to analyze the driving force for multicomponent gas hydrate nucleation from a single homogeneous phase. It is shown that the ratio between the specific surface energy and the critical radius of nucleation has a single value irrespective of the analyzed driving force expression. From this result, two driving force expressions for multicomponent gas hydrate nucleation are derived in the context of the so-called generalized nucleation theory, and it is demonstrated that the driving force for gas hydrates can be estimated using the same information given for the determination of the incipient formation points of the dispersed phase from a saturated phase. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

Recovery enhancement of liquid hydrocarbons in dew point control unit of natural gas processing plant

ABSTRACT

The low temperature absorption method is currently used in a gas-processing unit to control the natural gas dew point. The major problem of this unit is the simultaneous absorption of high amount of methane within heavier hydrocarbons, which leads to low purity of ethane and propane streams. Considering the operational conditions, the mentioned method used in second and third phases, will control the dew point at ?23° c at the best condition. This temperature is not proper for dew point and shows very high amount of hydrocarbons in product gas. In this study, a new process has been introduced in order to drop the gas liquid dew point (natural gas liquid) to ?85° c by self-refrigeration technology. Due to the advanced nature of absorption process, the problem of methane existence in the product of gas liquids is noticeably overcome. In this process, natural gas enters the turbo expander after passing through a refrigeration cycle at ?37° c and it is then expanded in an isotropic process to 2896 kPa pressure. Expander outlet with reflux and condensate produced from a cold separator are fed to an absorption tower with a reboiler and the separation will occur. The advantage of this method is controlling the concentration of methane in the product streams. Simulation results show that the process can daily produce 22,280 barrels of gas liquids with a concentration of 0.5 mole% of methane. In addition, the recovery efficiencies of propane and butane in the newly proposed method are 97.3% and 99.99%, respectively, which show a remarkable advantage over the current trend.     

Comparative analysis of barium titanate thin films dry etching using inductively coupled plasmas by different fluorine-based mixture gas

In this work, the inductively coupled plasma etching technique was applied to etch the barium titanate thin film. A comparative study of etch characteristics of the barium titanate thin film has been investigated in fluorine-based (CF₄/O₂, C₄F₈/O₂ and SF₆/O₂) plasmas. The etch rates were measured using focused ion beam in order to ensure the accuracy of measurement. The surface morphology of etched barium titanate thin film was characterized by atomic force microscope. The chemical state of the etched surfaces was investigated by X-ray photoelectron spectroscopy. According to the experimental result, we monitored that a higher barium titanate thin film etch rate was achieved with SF₆/O₂ due to minimum amount of necessary ion energy and its higher volatility of etching byproducts as compared with CF₄/O₂ and C₄F₈/O₂. Low-volatile C-F compound etching byproducts from C₄F₈/O₂ were observed on the etched surface and resulted in the reduction of etch rate. As a result, the barium titanate films can be effectively etched by the plasma with the composition of SF₆/O₂, which has an etch rate of over than 46.7 nm/min at RF power/inductively coupled plasma (ICP) power of 150/1,000 W under gas pressure of 7.5 mTorr with a better surface morphology.     

硝基苯催化加氢制苯胺的热力学分析

用基团估算法计算了硝基苯的热力学数据。对硝基苯催化加氢制苯胺进行了比较详细的热力学分析,首次建立了该反应的反应焓变、Gihbs自由能以及反应平衡常数的变化与反应温度的关系。得出该反应为自发放热反应,反应温度越高,趋于热力学平衡程度越低。     

硝基苯催化加氢制苯胺的热力学分析

用基团估算法计算了硝基苯的热力学数据。对硝基苯催化加氢制苯胺进行了比较详细的热力学分析,首次建立了该反应的反应焓变、Gibbs自由能以及反应平衡常数的变化与反应温度的关系。得出该反应为自发放热反应,反应温度越高,趋于热力学平衡程度越低。     

乙炔和氯化氢混合气水分测定方法探讨

采用露点仪法和重量法对乙炔和氯化氢混合气中的水分进行测定。结果表明,露点仪法和重量法都可以作为中控混合脱水的分析方法,但重量法在准确度、精密度以及对分析人员的危害及环保方面都优于露点仪法。