加压厌氧反应系统的实验运行研究

介绍了在实验室采用自制的厌氧反应器,通过增加反应器内压力来模拟增加反应器高度后对厌氧处理有机物效果的影响,并着重分析了在中温（37±1℃）环境下,容积负荷稳定在10kgCOD/（m3.d）时,在不同压力条件下,出水有机物浓度和产气量的变化。研究结果表明,在压力0.8MPa以下时,随着压力的升高,COD去除率逐渐增加,出水VFA浓度略有下降,溶于水中的气体量逐渐增加,出水pH值降低,且随着压力的增加,下降的幅度越大,溶于水中而被出水带出的气体量越大。当压力在1.0MPa左右时,较压力为0.8MPa时COD的去除率下降,出水VFA浓度略升高,溶于水中的气体量继续增加,出水pH值进一步下降。     

加压厌氧反应系统的试验运行研究

介绍了在实验室采用自制的厌氧反应器,通过增加反应器内压力来模拟增加反应器高度后对厌氧处理有机物效果的影响,并着重分析了在中温（37±1℃）环境下,容积负荷稳定在10kgCOD/（m^3·d）时,不同压力条件下,出水有机物浓度和产气量的变化。研究结果表明：在压力0.8MPa以下时,随着压力的升高,COD去除率逐渐增加,出水VFA浓度略有下降。溶于水中的气体量逐渐增加,出水pH值降低,且随着压力的增加,下降的幅度越大,溶于水中而被出水带出的气体量越大。当压力在1.0MPa左右时,较压力为0.8MPa时,COD的去除率下降,出水VFA浓度略升高,溶于水中的气体量继续增加,出水pH值进一步下降。     

Transient analysis of a gas manifold system

In the present work, a numerical study has been carried out to predict transient gas flow and pressure behaviour in a gas manifold system. The start‐up and shutdown of the system, varying demands at the consumer ends, malfunctioning of compressors and valves are a few examples of common causes of transience in a gas delivery system. In particular, the sensitivity of oscillations in pressure and mass flux to variation in pipe dimensions, supply pressure and gas flow rate are ascertained under the aforementioned conditions of transience. The present results show that large pipe dimensions, high gas flow rate and high upstream pressure in the branch in which the disturbance is introduced, all cause greater amplitude in mass flux and pressure oscillations in the neighboring branches. The duration of oscillations is also found to be longer. The present study has practical importance in designing as well as in operating, a gas delivery system.     

螺旋内槽管内天然气-水-表面活性剂体系的水合物生成动力学计算

针对多组分气体（天然气）-水-表面活性剂体系在螺旋内槽管内的水合物生成过程,首先采用CFD方法结合群体平衡模型（PBM）,基于溶质渗透模型和Kolmogorov各向同性湍流理论对螺旋内槽管内气液传质系数进行了模拟;其次基于Kashchiev和Firoozabadi的经典水合物成核和生长理论,将其体系从单组分-水系统扩展到多组分气体（天然气-水-十二烷基硫酸钠）系统,同时结合经典结晶理论利用传质系数对水合物生长模型进行了修正,建立了适用于螺旋内槽管流动体系内天然气水合物生成动力学模型。通过模拟计算,获得不同水合物生产条件下天然气在水中的平均传质系数;进而利用Microsoft Visual C++编程计算得到不同条件下水合物生成动力学数据,在考察范围内,天然气水合物的成核速率随着反应体系有效表面能的增大而锐减,而水合物生成驱动力和生长速率未受影响,同时水合物生长速率随着流速和反应压力的增大及温度的降低而增大,成核速率随着压力的增大和温度的降低而增大。     

有机废物厌氧消化系统预处理装置工况优选的实验研究

现存于农村的厌氧消化装置大都是单相常温的,不但浪费原料而且产气量较低,难以保证用户供暖需求.研究设计了一套两相有机废物厌氧消化系统,针对预处理装置及其测控系统进行了实验研究,得出了可保证预处理装置原料利用率最高时的最优条件,使得后续厌氧消化系统的产气量得以保障.     

错流旋转填料床气相压降特性

旋转填料床的气相压降是旋转填料床应用和设计的一项重要指标。在气液两相错流流动条件下,利用空气-水系统对错流旋转填充床的气相压降进行分段模型化和实验研究。按照错流旋转填料床气体流动的路径将气相压降分为进口压降、填料层压降、集气段旋转动能转化压降和出气段压降。推导出压降与操作工况的关联式,其计算值与实测值吻合较好。实验表明错流旋转填料床的气相总压降与气体流量、旋转床转速、液体流量有关。在高转速和小气量的条件下,气相压降随气量增大先下降后上升;其他情况随气量增大而上升。错流旋转填料床气相压降随转速上升而下降,在小气量情况下转速对气相压降有明显影响。气相压降随进液量的增大而增大,当旋转填料床在低转速时进液量对气相压降有明显影响。     

Diamond films with preferred <110> texture by hot filament CVD at low pressure

The effects of gas pressure on the textured growth of diamond films were investigated in a hot filament chemical vapor deposition (HFCVD) system. Diamond thin film with the growth rate of 1.3 μm/h and with high <110> texture was obtained at 5 Torr when lowering the gas pressure from 40 Torr to 1 Torr. The formation of high density nanocrystalline diamond nuclei elongated along the <110> direction in the nucleation stage and its consequent growth at lower pressure were considered to be responsible for the formation of <110> textured diamond thin film.     

碱预处理耦合零价铁强化含油污泥厌氧消化

含油污泥通常含较多的生物难降解性有机化合物,且污泥黏度大,乳化程度高,导致其厌氧消化潜力较低。污泥细胞破壁较慢,是污泥厌氧消化的限速步骤。本研究通过对含油污泥进行碱预处理,实现了污泥细胞破壁,并检测到胞内有机物质大量溶出,进而加快污泥水解为溶解态的小分子有机物,提高厌氧消化效率。另一方面,为了解决由预处理产生过量有机酸（如丙酸等）积累破坏厌氧系统内pH平衡的问题,本研究通过投加零价铁,促进丙酸等小分子向乙酸的转化,促进产甲烷,并最终使厌氧系统内pH保持平衡。研究结果表明：含油污泥经过碱预处理甲烷产量提高91.7%,同时污泥减量率提高了8%。碱预处理耦合零价铁粉,使得甲烷产量提高了105.4%,污泥减量率提高13%。进一步优化碱预处理pH条件,结果表明碱处理的最佳pH为9。     

Bubble growth in thermoplastic structural foams

The inflation and growth kinetics of bubbles in thermoplastic structural foams are discussed in some detail using a model which assumes the initial existence of very small voids in the pressurized polymer melt. The effects of a drop in external pressure, the presence of a distribution of bubble sizes, and the diffusion of gas between neighboring bubbles are considered. It is shown that at a given pressure the number of growing bubbles present in the melt at any onetime depends on the ratio of the critical radius to the average radius of the microvoids assumed to be present in the melt It is also demonstrated that gas diffusion between neighboring bubbles reduces the growth rate appreciably only when the interbubble distance is reduced to a micron or less.     

Effects of electrode arrangement and pressure on synthesis of diamond films by arc discharge plasma jet chemical vapor deposition

The setup and deposition conditions of electrode arrangement and pressure have been studied to synthesize diamond films at high growth rate on wide area efficiently by arc discharge plasma jet chemical vapor deposition. An apparatus has been used in which four plasma torches, one is used for cathode and the others for divided anodes, are arranged and the positions of these torches are changeable. Growth rate, deposition area and thickness of diamond films have increased with changing the electrode arrangements without improvement of thickness variation. Maximum growth rate of our apparatus has occurred at the pressure of 6.7 kPa and diamond films that have less variations of quality and surface roughness have been synthesized at lower pressure during deposition. Moreover, a high conversion rate, which is the ratio of carbon atoms that form diamond in supplied methane gas, of 16% has been obtained at the pressure of 6.7 kPa and methane concentration of 2%.     

高含固率污泥厌氧消化系统的启动方案与试验

高含固污泥厌氧消化技术是目前国内外的研究热点。该文以上海市白龙港污水处理厂脱水污泥稀释而成的含固率为10%的污泥作为研究对象,对高含固污泥厌氧消化技术进行了初步的探讨。试验结果表明,厌氧消化系统的进泥含固率升高至10%后,每投入1 m3的污泥产气约16~18 m3沼气,远高于现有浓缩污泥厌氧消化系统的产气率(8~10 m3沼气/m3污泥)。高含固率污泥厌氧消化系统推荐采用清水启动策略,即消化罐内介质的初始状态为清水(二沉池出水),之后以不同投配率投加原污泥,避免系统启动过程中的VFA的积累,尤其是丙酸含量的积累。该研究成果不仅可为该污水处理厂现有污泥厌氧消化系统未来的扩建改造服务,而且可为国内同类工程提供借鉴和示范。     

Study of the Kinetics and Morphology of Gas Hydrate Formation

The kinetics and morphology of ethane hydrate formation were studied in a batch type reactor at a temperature of ca. 270–280 K, over a pressure range of 8.83–16.67 bar. The results of the experiments revealed that the formation kinetics were dependant on pressure, temperature, degree of supercooling, and stirring rate. Regardless of the saturation state, the primary nucleation always took place in the bulk of the water and the phase transition was always initiated at the surface of the vortex (gas‐water interface). The rate of hydrate formation was observed to increase with an increase in pressure. The effect of stirring rate on nucleation and growth was emphasized in great detail. The experiments were performed at various stirring rates of 110–190 rpm. Higher rates of formation of gas hydrate were recorded at faster stirring rates. The appearance of nuclei and their subsequent growth at the interface, for different stirring rates, was explained by the proposed conceptual model of mass transfer resistances. The patterns of gas consumption rates, with changing rpm, have been visualized as due to a critical level of gas molecules in the immediate vicinity of the growing hydrate particle. Nucleation and decomposition gave a cyclic hysteresis‐like phenomena. It was also observed that a change in pressure had a much greater effect on the rate of decomposition than it did on the formation rate. Morphological studies revealed that the ethane hydrate resembles thread or is cotton‐like in appearance. The rate of gas consumption during nucleation, with different rpm and pressures, and the percentage decomposition at different pressures, were explained precisely for ethane hydrate.     

Synthesis of CVD diamond at atmospheric pressure using the hot-filament CVD method

At low pressure, chemical vapor deposition (CVD) diamond growth by conventional techniques such as micro-wave plasma and hot-filament have been achieved by metastable precursor species. Moreover, bulk diamond at extremely high pressures and temperatures was consistently originated by the nature of diamond-graphite phase transition. CVD diamond growth has four problems with these conventional techniques. Excluding contaminated air from low pressure reactive systems has been problematic. It is very difficult to control the concentration of atomic hydrogen at high pressures. The growth rate is unsatisfactory and the running cost of gases are high.However, the hot-filament CVD technique at atmospheric pressure overcomes these problems. We have found that in order to control the concentration of atomic hydrogen, the residence time of the input gas and the methane-hydrogen concentration ratio needed to be varied at each pressure. The relationship between the quality of deposited diamond and the pressure have been also investigated by Raman spectroscopy and X-ray diffraction patterns (XRD).The growth rate at atmospheric pressure (106 000 Pa) was found to be greater than that at the conventional pressure (5000 Pa). At atmospheric pressure, the growth rate abruptly increases with the residence time. XRD analysis revealed that the quality of diamonds grown at atmospheric pressure was higher than that of diamonds produced at low pressures. Furthermore, high quality diamond growth was achieved with a long residence time of the input gas at atmospheric pressure.     

城市污水处理厂污泥中温两相厌氧消化的研究

采用中温两相厌氧消化处理西安市污水处理厂污泥,结果表明,污泥可在较短的停留时间(296 h,产酸相30 h,产甲烷相266 h),较高的有机负荷(约2.65 kg VS/m3.d)下稳定运行,系统VS去除率38.87%,pH≈7.5,产气速率6.33 L/L.d,单位VS产气率3.00 L/g。与单相厌氧消化处理结果对比,两相厌氧消化系统的停留时间可减少一半,而污泥有机负荷提高2倍,且有机物的去除率大,处理效果好,稳定性高,抗冲击负荷能力强,产气性良好。     

全透明高压反应釜甲烷水合物动力学实验

水合物的生长和分解规律对开发海洋天然气水合物资源,实现深水天然气水合物气液固多相管道输送都具有重要意义。为了进一步揭示水合物的生长和分解特性,本文采用高压全透明反应釜装置,进行了温度0～30℃、压力3.35～8.16MPa和搅拌速率200～1000r/min范围内的16组甲烷水合物生长和分解动力学实验研究。结果表明：实验过程可分为水合物诱导期、快速生长期、缓慢生长期以及分解期这4个阶段。在水合物快速生长阶段,获得了温度、压力、搅拌电机扭矩和水合物生长速率随时间的变化规律,观察到了水合物颗粒的均相和非均相分布状态。通过加热促使水合物分解,揭示了分解阶段温度、压力和分解速率等关键参数的变化规律以及水合物块的分解形态。分析表明,水合物颗粒的分布状态与水合物浆液的流动性直接相关;水合物块的静态分解过程受到分解气传质控制。     

泡沫铜强化甲烷水合物生成动力学实验研究

提高水合物生成速率和储气密度对天然气水合物技术应用非常重要。将三种孔密度的泡沫铜（CF）分别浸入十二烷基硫酸钠（SDS）溶液中构建水合储气强化体系,在高压静态反应釜中研究泡沫金属对甲烷水合物生成动力学特性。实验结果表明,泡沫铜骨架能为水合物生成提供充足的结晶点,同时可作为水合物生长过程水合热迁移的“高速公路”。甲烷水合物在SDS/CF体系中可快速生成,最大水合储气速率分布在19.24~21.04 mmol·mol^-1·min^-1之间,其中添加15 PPI泡沫铜的SDS溶液储气量最高（139 mmol·mol^-1）,且达到最大储气量90%所用时间最短（10.1 min）。在6.0~8.0 MPa压力下,相比SDS溶液,添加15 PPI泡沫铜的SDS溶液储气量提高了8.8%~35.6%,储气速率提高了4.7%~40.4%;特别在压力为5.0 MPa时,该孔密度SDS/CF体系储气量甚至比SDS溶液增加13倍,储气速率增加16倍。     

上升管中严重段塞流的流型和压力波动特性

During the exploitation of offshore oil and gas, it is easy to form severe slugging which can cause great harm in the riser connecting wellheads and offshore platform preprocessing system. The flow pattern and pressure fluctuation of severe slugging were studied in an experimental simulation system with inner diameter of 0.051 m. It is found that severe slugging can be divided into three severe slugging regimes: regime I at low gas and liquid flow rates with large pressure fluctuation, intermittent flow of liquid and gas in the riser, and apparent cutoff of liquid phase, regime II at high gas flow rate with non-periodic fluctuation and discontinuous liquid outflow and no gas cutoff, regime III at high liquid flow rate with degenerative pressure fluctuation in form of relatively stable bubbly or plug flow. The results indicate that severe slugging still occurs when the declination angle of pipeline is 0&#730;, and there are mainly two kinds of regimes: regime I and regime II. As the angle increases, the formation ranges of regime I and regime III increase slightly while that of regime II is not affected. With the increase of gas superficial velocity and liquid superficial velocity, the pressure fluctuation at the bottom of riser increases initially and then decreases. The maximum value of pressure fluctuation occurs at the transition boundary of regimes I and II.     

严格厌氧发酵体系在线尾气监测系统的设计及在梭菌生产生物能源丁醇的应用

目前关于有氧或微氧的乙醇发酵的尾气检测系统已经建立,但是对于丙酮丁醇梭菌等严格厌氧菌发酵尾气的在线监测鲜见文献报道。因此,本研究以丙酮丁醇梭菌生产丁醇的严格厌氧发酵体系为研究对象,研究了传统有氧或微氧尾气检测方法在丙酮丁醇梭菌厌氧发酵体系中的检测结果,设计并建立了适合厌氧菌发酵的尾气在线监测系统,对丙酮丁醇梭菌的发酵过程实时监测。在建立有效的厌氧发酵尾气分析系统的条件下,比较了丙酮丁醇梭菌在游离细胞条件下和高细胞密度条件下的发酵性能。相比较于游离发酵,高细胞密度发酵的发酵周期明显缩短,丁醇生产强度显著提高。丁醇最高产量为15.4g/L,生产强度0.64g/（L·h）,分别比对照组提高了12.4%和106%,CO₂和H₂最高产气速率分别提高60%和9%,产气量分别提高了20.7%和41.3%。尾气分析系统采集的气体数据为丙酮丁醇梭菌的代谢分析提供了重要依据。     

A combined chemico-biological treatment of waste waters from coal depyritization with production of elemental sulphur

A combined chemico-biological process has been developed to remove sulphate and heavy metal ions from waste waters after microbial depyritization of coal. The waters are initially neutralized to a pH of about 3.5, diluted with pure water and then treated in an anaerobic bioreactor for microbial sulphate reduction in which nutrients are added to support the growth of bacteria. In the bioreactor the sulphate ions are reduced to hydrogen sulphide and the heavy metals are precipitated as the relevant insoluble sulphides. The process then involves H₂S stripping from the anaerobic bioreactor using nitrogen as a carrier gas, sulphur production from H₂S oxidation by bacterially produced ferric ions, aerobic solution polishing by microbial degradation of the organics, and secondary anaerobic processing. The product solution is rich in carbonate and may be recycled to the sulphate reduction stage or to the ferric ions production stage or may be discharged from the system.     

Low temperature and large area deposition of nanocrystalline diamond films with distributed antenna array microwave-plasma reactor

Diamond films grown at low temperature (< 400 °C) on large area of different substrates can open new applications based on the thermal, electrical and mechanical properties of diamond. In this paper, we present a new distributed antenna array PECVD system, with 16 microwave plasma sources arranged in a 2D matrix, which enables the growth of 4-inch nanocrystalline diamond films (NCD) at substrate temperature in the range of 300–500 °C. The effect of substrate temperature, gas pressure and CH₄ concentration in the total gas mixture of H₂/CH₄/CO₂ on the morphology and growth rate of the NCD films is reported. The total gas pressure is found to be a critical deposition parameter for which growth rates and crystalline quality both increasing with decreasing the pressure. Under optimized conditions, the process enables deposition of uniform (~ 10%) and high purity NCD films with very low surface roughness (5–10 nm), grain size of 10 to 20 nm at growth rates close to 40 nm/h. Nanotribology tests result in the friction coefficient of the NCD films close to that obtained for the standard tetrahedral amorphous carbon coatings (ta-C) indicating the suitability of this low-temperature diamond coating for mechanical applications such as bearing or micro-tools.