Experimental Investigation on Condensate Revaporization During Gas Injection Development in Fractured Gas Condensate Reservoirs

The gas field in the Bohai Bay Basin is a fractured metamorphic buried-hill reservoir with dual-media characteristics. The retrograde vaporization mechanism observed in this type of gas condensate reservoir differs significantly from that observed in sand gas condensate reservoirs. However, studies on improving the recovery of fractured gas condensate reservoirs are limited;thus, the impact of retrograde vaporization on condensate within fractured metamorphic buried-hill reservoirs remains unclear. To address this gap, a series of gas injection experiments are conducted in pressure-volume-temperature(PVT) cells and long-cores to investigate the retrograde vaporization effect of condensate using different gas injection media in fractured gas condensate reservoirs. We analyze the variation in condensate volume, gas-to-oil ratio, and condensate recovery during gas injection and examine the influence of various gas injection media(CO_(2), N_(2), and dry gas) under different reservoir properties and varying gas injection times. The results demonstrate that the exchange of components between injected gas and condensate significantly influences condensate retrograde vaporization in the formation. Compared with dry gas injection and N_(2) injection,CO_(2) injection exhibits a superior retrograde vaporization effect. At a CO_(2) injection volume of 1 PV, the percentage shrinkage volume of condensate is 13.82%. Additionally, at the maximum retrograde condensation pressure, CO_(2) injection can increase the recovery of condensate by 22.4%. However, the condensate recovery is notably lower in fractured gas condensate reservoirs than in homogeneous reservoirs, owing to the creation of dominant gas channeling by fractures, which leads to decreased condensate recovery. Regarding gas injection timing, the effect of gas injection at reservoir pressure on improving condensate recovery is superior to that of gas injection at the maximum retrograde condensation pressure. This research provides valuable guidance for designing gas injection development plans and dynamic tracking adjustments for fractured gas condensate reservoirs.

Magnesium vapor nucleation in phase transitions and condensation under vacuum conditions

Recent findings related to coagulable magnesium vapor nucleation and growth in vacuum were assessed critically, with emphasis on understanding these processes at a fundamental molecular level. The effects of magnesium vapor pressure, condensation temperature, and condensation zone temperature gradient on magnesium vapor nucleation in phase transitions and condensation from atomic collision and coacervation with collision under vacuum conditions were discussed. Magnesium powder and magnesium lump condensates were produced under different conditions and characterized by scanning electron microscopy （SEM） and energy-dispersive X-ray spectroscopy （EDS）. The right condensation zone temperature approach to the liquid transition primarily improved the magnesium vapor concentration rate. The gas-solid phase transition was primarily inhibited by setting a small condenser temperature gradient. Under the right condensation temperature and temperature gradients, increasing magnesium vapor partial pressure improved crystallization and reduced the oxidation rate.

Numerical investigation of condensation of gasoline vapor with turbulent flow in vertical tubes

To investigate the characteristics of the condensation in gasoline vapor condensation recovery,the condensation process of gasoline vapor with turbulent flow in a vertical tube is simulated based on the gas-liquid two-phase flow model.An effective diffusion coefficient is used to describe mass diffusion among the species of gasoline vapor.Several variables including temperature,pressure,liquid film thickness and the variation of the Nusselt number in the tube are simulated.The effects of the inlet-to-wall temperature difference and the Reynolds number on the condensation rate and the Nusselt number are obtained by modelling.The results show that heat transfer and condensation can be enhanced significantly by increasing the inlet Reynolds number.However,the increase in the inlet-to-wall temperature difference has little effect on the condensation rate.It is also found that the gasoline vapor condensation rate is influenced greatly by the mass transfer resistance.The comparison of results from the model with previous experiments shows a good agreement.

Antibacterial Characteristics of ZnO-CeO_2 Nano-Powder Prepared byLaser Vapor Condensation

Antibacterial activity of ZnO-CeO2 solid nano-powders was studied by measuring the change of sterilization efficacy to the bacterial. ZnO-CeO2 nano-powders were prepared by laser vapor condensation (LVC) with oxygen as loading gas. The size of the particle can be affected greatly by some reacting conditions such as the flow of loading gas and the reacting pressure. Rod-like powders with different molar ratios (Zn/Ce) and sizes were produced in the changed reacting conditions for studying the effects of sterilization efficacy to the bacterial. It is found that antibacterial activity of oxide powders increase with decreasing particle size and increasing ceria concentration. The changes of antibacterial action for S. aureus are similar to those for B.niger. Both the preparing mechanism of LVC and the sterilization assumption were proposed.

Numerical study of the deep removal of R134a from non-condensable gas mixture by cryogenic condensation and de-sublimation

Nowadays,the limits on greenhouse gas emissions are becoming increasingly stringent.In present research,a two-dimensional numerical model was established to simulate the deep removal of 1,1,1,2-tetrafluoroethane(R134a)from the non-condensable gas(NCG)mixture by cryogenic condensation and de-sublimation.The wall condensation method was compiled into the Fluent software to calculate the condensation of R134a from the gas mixture.Besides,the saturated thermodynamic properties of R134a under its triple point were extrapolated by the equation of state.The simulation of the steam condensation with NCG was conducted to verify the validity of the model,the results matched well with the experimental data.Subsequently,the condensation characteristics of R134a with NCG and the thermodynamic parameters affecting condensation were studied.The results show that the section with relatively higher removal efficiency is usually near the inlet.The cold wall temperature has a great influence on the R134a removal performance,e.g.,a 15 K reduction of the wall temperature brings a reduction in the outlet R134a molar fraction by 85.43%.The effect of changing mass flow rate on R134a removal is mainly reflected at the outlet,where an increase in mass flow rate of 12.6% can aggravate the outlet molar fraction to 210.3% of the original.The research can provide a valuable reference for the simulation of the deep removal of various low-concentration gas using condensation and de-sublimation methods.

喷雾耦合降温强化旋风分离器脱除细颗粒物的研究

通过在冷凝换热器前耦合喷雾的方式,将雾化团聚和水汽相变团聚结合以提高旋风分离器对细颗粒物的脱除效果,用于湿式除尘器后近饱和高湿烟气的深度处理。通过开展实验室试验和某金属冶炼厂烟气旁路试验,考察了该技术对颗粒物的脱除特性。实验室研究结果表明,典型工况下喷雾耦合降温能够显著增强旋风分离器对颗粒物的脱除,比单独喷雾或降温具有更好的增强效果。提高喷雾量和换热器温降,细颗粒物脱除效率先升高后趋于稳定,在温降6℃、喷雾量0.046 L/m^(3)时达到最优脱除效果。烟气温度越高,湿度越接近饱和,细颗粒物脱除效率越高。工业烟气旁路试验表明,该系统适用于湿式除尘后的近饱和高湿烟气,且对波动工况的适应性强,当入口颗粒物浓度不超过2000 mg/m^(3)时,出口颗粒物浓度可保持在20 mg/m^(3)以内,平均脱除效率超过99.2%。

自然通风湿式冷却塔节水方案的数值研究

为降低自然通风湿式冷却塔的耗水量,本文采用一种可用于回收其蒸发损失的空气冷凝器结构,并通过数值模拟方法对其节水特性展开研究。首先基于空气运动控制方程和水蒸气冷凝模型,建立了用于分析空气冷凝器节水特性的数学模型,其次分析了冷却空气流速、空气冷凝器的结构尺寸和材质等因素对该冷凝器节水特性的影响。研究结果表明:空气冷凝器的单位面积节水量随着冷却空气流速以及冷凝器宽度的增大而增大,但随着冷凝器长度和高度的增大而减小;空气冷凝器的材质和壁厚对其单位面积节水量没有显著影响,空气冷凝器可采用重量轻和成本低的薄壁PVC来加工制造。

采用非共沸制冷剂的双喷气增焓两级压缩热泵循环研究

提出一种采用非共沸制冷剂的双喷气增焓两级压缩热泵循环(DVIC),该循环在普通喷气增焓循环(VIC)的基础上采用分液冷凝技术,并增加一组闪蒸器,减少系统不可逆损失,改善热力性能。采用R290/R1336mzz(Z)非共沸制冷剂,对DVIC进行研究,并与VIC进行比较。结果表明:在设定工况下,DVIC比VIC拥有更优的循环性能,系统COP和(火用)效率分别提高5.82%和8.41%,压缩机功耗降低6.39%;在较低蒸发温度或较高冷凝温度的运行工况下,DVIC性能的改善效果更加明显。

摇摆运动下低流率蒸汽冷凝换热特性和气泡受力数值模拟

蒸汽直接接触冷凝具有高效的传热传质性能,广泛应用于核能安全等领域。低质量流率蒸汽直接接触冷凝具有低频压力振荡,易引发设备共振。相比陆地稳定工况,海洋条件下摇摆运动可能加剧气液界面振荡,进一步影响设备的安全运行。为此,通过数值模拟对摇摆条件下低流率蒸汽凝结过程进行研究,分析了摇摆条件下压力、换热特性和气泡受力的变化规律,结果表明压力和传热系数剧烈波动主要集中于气泡颈缩和脱离阶段,此时气泡受力也达到最大值,气泡主要受惯性力和凝结力作用。此外,对比静止工况和摇摆工况,发现摇摆条件下由气泡速度变化导致的惯性力部分增大,摇摆运动带来的附加摇摆速度强化了气液界面的换热性能,平均传热系数远高于静止工况。

平直翅片管式捕水器换热性能实验研究

为研究平直翅片管式捕水器换热性能,设计了一种真空捕水器实验系统,并对其换热性能进行测试,系统运行约450 s,真空室内的模拟热源温度从80℃降至25℃,凝结水量约2.9 kg。实验结果表明:蒸发动力越高,水蒸发越剧烈;捕水器凝结水蒸气的峰值制冷量为45.0 kW,峰值传热系数约为53.68 W/(m^(2)·K),平均传热系数为38.34 W/(m^(2)·K);相比光管折流板式捕水器,平直翅片管式捕水器所需冷却时间缩短17%,凝结水量提高7.41%。

基于降低碳排放量的凝析油稳定工艺能耗分析与优化研究

为了提高凝析油稳定工艺的能效水平,降低其在生产运行过程中的碳排放量,以某油田中央处理厂凝析油稳定工艺为研究对象,在确定碳排放源设备和碳排放类型的基础上,采用HYSYS软件分析了不同参数对碳排放量和凝析油产量的影响,并以最小碳排放总量为目标函数,对比了多种优化方法下的工艺变量调整方案。结果表明:碳排放源来自闪蒸气、不凝气的火炬燃烧排放,以及预换热器和重沸器所需的净购入电力排放,闪蒸气碳排放量占碳排放总量的绝大部分;采用序贯二次规划法优化后,凝析油产量提高了5.62%,凝析油饱和蒸气压满足产品品质的要求,碳排放总量降低了4.45%。该研究结果可为油气田企业的高效、低碳运行提供理论依据和实际参考。

油气回收技术在营口港仙人岛码头中的应用研究

原油成品油码头产生的油气具有毒性和爆炸性,作为主要的大气污染之一,严重影响港区及周边环境。随着环境管理体系不断完善,营口港仙人岛码头持续开展油气回收有效管控。文章介绍了营口港油气回收工艺应用情况,分析总结了油气污染物的形成、组成以及油气回收技术在营口港仙人岛码头的实际应用,以期帮助码头企业和相关工作者选择最佳技术方案,实现油气高效回收。

VOC废气的低温冷凝回收工艺的设计

根据VOC废气中的成分,查询和计算其饱和蒸气压参数和嗅阈值,基于国家和地方规定的排放标准,设计计算VOC废气排放达标所需的低温冷凝工艺温度参数,结果表明,在该低温冷凝温度条件下,VOC废气排放达标,有效遏制VOC污染物的外排,具有极大的环境和经济效益。

城市客车铝合金风道水蒸气凝聚的CFD仿真方法

建立水蒸气凝聚的仿真流程,并基于CFD软件进行某城市客车铝合金风道的共轭温度场仿真,同时评估铝箔隔热棉对城市客车铝合金风道盖板水蒸气凝聚的影响。

T型微细通道内含不凝气蒸汽直接接触凝结数值模拟研究

利用VOF多相流模型和大涡模拟LES湍流模型,结合“双阻力”模型和Fick定律,对微细通道内含不凝气蒸汽的直接接触凝结过程进行了数值模拟。开展了不凝气对蒸汽直接接触凝结过程中气羽形态、压力分布以及凝结速率的影响机制研究。结果表明:在少量不凝气存在的工况,汽液相界面仍呈现周期性变化,随不凝气含量增加,其在汽液界面处聚集形成的不凝气层厚度增加,气羽无周期性变化。此外,随着不凝气含量的升高,压力振荡强度减弱,凝结形成的负压值变小,凝结速率降低。

冷凝+吸附油气回收技术应用与安全性探究

挥发性有机化合物(VOCs)的释放对自然生态系统和人类健康产生了严重的影响,引起了全球范围内的高度关注,从而使得VOCs的管理成为一个备受关注的问题。本文旨在探讨VOCs治理常用的工艺技术,并对油气回收工艺组合的应用实际和安全性进行探讨分析。首先,本文介绍了VOCs治理工艺技术和常见工艺组合;其次,以国内某炼油厂为实例,对冷凝+吸附工艺流程进行介绍;最后,通过综合分析,突显了VOCs治理和冷凝+吸附油气回收技术在提高空气质量、保护环境资源以及确保安全生产等方面的重要意义。

圆形截面凝汽器布管设计及换热性能分析

凝汽器是蒸汽动力系统重要的设备之一,其换热性能直接影响整个系统的运行效率。多领域对更高效凝汽器的需求不断涌现,针对凝汽器的结构设计迭代与换热性能优化的研究具有重要意义。文中在FLUENT计算平台中,基于多孔介质模型通过自定义函数嵌入管间换热模型、质量汇与阻力模型,分析了一种圆形截面凝汽器布管方式的换热性能。结果表明,相比于管内冷却水工况的变化,蒸汽流速变化引起的管外热阻变化更大程度地影响平均换热系数。依据实际运行工况参数范围,入口蒸汽流速为30~70 m/s,冷却水流速为0.72~2.15 m/s,冷却水温度为25~28℃,平均换热系数最大可达3562 W(/m^(2)·K),同时压降范围为211~525 kPa。该结构设计表现出较好的换热性能和较低的压力损失,但局部不凝结气体的积聚表明该结构仍有进一步改进的空间。

数据中心冷却用丁胞型扁管内冷凝传热和压降特性试验研究

针对丁胞型扁管内的冷凝传热和压降特性开展试验研究,分析干度、质量流速、饱和温度和热流密度对表面传热系数和摩擦压力梯度的影响。结果表明:在不同运行工况下,R245fa的表面传热系数均随干度的增大而增大;增大质量流速有利于提高表面传热系数,尤其是对于高干度区域;饱和温度改变对低干度区域的表面传热系数影响较小,但是当干度大于0.4时,饱和温度升高会导致表面传热系数略微下降;在整个干度区域内,不同热流密度对表面传热系数基本没有影响;质量流速和热流密度对摩擦压力梯度的影响与其对表面传热系数的影响相似,但是饱和温度升高会导致压降明显下降;丁胞型扁管的表面传热系数为常规流道的1.7~2.9倍,摩擦压力梯度为常规流道的4.3~10.9倍。

Formation regularity of phases in nanometer powders of Al-Fe alloy prepared by gas evaporation

Nanometer powders of Al Fe alloy were prepared by gas evaporation. The formation regularity of the phases in the as prepared powders and the morphology of the particles were examined. The experimental results show that chemical composition of the master alloy is the key factor which controls the chemical composition of the compound phases in nanometer powders at given evaporating temperature, the compound phases with high Fe mole fraction will form with increasing of Fe content in master alloy. Only Al 13 Fe 4, FeAl 2 and Al 2Fe compound phases form in nanometer powders in present experiment, changing of the pressure of Ar can only alter relative amounts of the compound phases in the powders. Nanometer particles with inhomogeneous tissue were obtained, which is very different from that of pure Al and Fe nanometer particles. When mole fraction of Fe in particles increases, the inhomogeneity is enhanced. [

Analysis on Concentration and Source Rate of Precursor Vapors Participating in Particle Formation and Growth at Xinken in the Pearl River Delta of China

Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign （PRD2004, October 2004） in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOx, 03, CO, non-methane hydrocarbon （NMHC） and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 × 10^7 to 2.17 × 10^8 molecules cm^-3, the corresponding source rate via reaction of OH and SO2 range between 2.37 × 10^6 and 1.16 × 10^7 molecules cm^-3 s^-1. Nucleation mode growth rate was derived from size spectral evolution during the events to be 6.8-13.8 nm h^-1. Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 × 10^8 to 2.80 × 10^8 molecules cm^-3 with corresponding source rate between 7.26 × 10^6 and 1.64 × 10^7 molecules cm^-3 s^-1. Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.