柔性大波纹管换热器的阻垢自清洗特性实验研究

对柔性大波纹管、普通被纹管和光管换热器的阻垢性能和自清洗性能进行了实验对比。结果表明,柔性大波纹管比普通波纹管和光管结垢速度慢,稳定后传热系数高,其管内湍流程度较高,周期性的轴向流速脉动和管束自振动都明显阻碍了积垢的形成,其自清洗能力也高于普通光管,有利于延长换热器的使用寿命,且具有良好的强化传熱性能、阻垢和自清洗等性能,是一种石油化工工业中具有广泛应用前景的传热元件。     

浮头式废热锅炉存在的问题及其改进

介绍了浮头式废热锅炉的结构形式，对其存在的换热能力不足，管子易损坏，隔热衬里、衬筒变形等问题产生的原因进行了分析，从改善传热条件和改进结构方面提出了改进建议和实施措施。     

Study on pyrolysis of oil sludge with microalgae residue additive

The pyrolysis of oil sludge (OS) with microalgae residue (MR) additive was conducted with a TGA and a tube furnace. The pyrolysis process of OS with the MR additive can be divided into three stages: 1) water evaporation, 2) the release of light groups of hydrocarbon compounds, the cracking of heavy groups, and carbon decomposition, and 3) minerals decomposition. With the MR addition ratio increasing, the yield of oil and gas increased, and oil to gas ratio increased during OS pyrolysis. The MR addition improved the quality of pyrolysis oil and gas from OS pyrolysis. The proportion of light oil increased from 38 % with a 5 % MR addition ratio to 45 % with a 30 % addition ratio. Major components of pyrolysis gas included H₂, CO, CO₂, and C_xH_y. With the increase of the MR blending ratio, CO and CO₂ contents increased, while H₂ and C_xH_y contents decreased. Adding MR favoured the transformation of heavy hydrocarbons (C₆₊), resulting in a high content of light hydrocarbons. This work can help promote massive synergistic treatment of OS and microalgae biomass.

     

Generation of hydrogen under visible light irradiation with enhanced photocatalytic activity of Bi2WO6/Cu1.8Se for organic pollutants under Vis‐NIR light reign

To make better use of solar light, a new Bi₂WO₆/Cu_1.8Se photocatalyst active to visible and near‐infrared light has been synthesized by a facile hydrothermal method. The composites were characterized by X‐ray diffractometry (XRD), scanning electron microscopy (SEM), UV‐vis diffuse reflectance spectroscopy (DRS), and photoluminescene (PL). The photocatalytic activities of Bi₂WO₆/Cu_1.8Se are evaluated by degrading Congo red solution and hydrogen generation from water. It was found that the molar percentage of Cu_1.8Se had great effects on the morphology and photocatalytic property of the Bi₂WO₆/Cu_1.8Se heterojunctions, and the composite with suitable molar amount of Cu_1.8Se exhibits much enhanced photocatalytic activity for Congo red degradation under visible and near‐infrared light irradiation and for hydrogen generation under visible light compared to Bi₂WO₆. The significant improvement photocatalytic activity of the composite could be attributed to its good light absorption, suitable band gap structure, and effective separation of photogenerated electron‐hole pairs of Bi₂WO₆/Cu_1.8Se heterojunction. This work presents an efficient multifunction photocatalyst owning the activity both for water splitting under visible light and for organic contaminants decomposition under visible‐near‐infrared light.     

Metal cation removal by P(VC-r-AA) copolymer ultrafiltration membranes

A series of amphiphilic copolymers containing poly(vinyl chloride-r-acrylic acid) (P(VC-r-AA) ) was synthesized and used to prepare membranes via a nonsolvent induced phase separation method. The prepared membranes were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and water contact angle and zeta potential measurements. The copolymer P(VC-r-AA) chains did not dissolved in a coagulation bath, indicating that the AA segments were completely retained within the membrane. Enriching degree of AA segments in surface layer was 2 for copolymer membrane. In addition, the introduction of AA segments made the membrane electronegative and hydrophilic so that the membrane was sensitive to the solution pH. The fouling resistance, adsorption of Cu(II), Cr(III) and Ce(IV) ions and the desorption properties of the membranes were also determined. The copolymer membranes exhibited good antifouling performance with a fouling reversibility of 92%. The membranes also had good adsorption capacities for Cu(II), Cr(III) and Ce(IV) ions. The optimal pH for Cu(II) adsorption was 6 and the copolymer membrane has potential applications for low concentration Cu(II) removal.

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The effect of mixing on Co‐precipitation and evolution of microstructure of Cu‐ZnO catalyst

The influence of feeding point in conventional stirred tank reactor and flow characteristics in micro‐reactor on the microstructure of Cu‐ZnO catalyst was studied. Cu‐Zn distribution in co‐precipitate was characterized by EDS and Zn fraction in zincian malachite was estimated from the 20 peak shift in XRD pattern. The theory analysis and experimental results, combining with measurement of segregation index, show that the contact pattern and mixing of reactants in precipitation process determine the uniformity of Cu‐Zn distribution in initial co‐precipitates at the micro‐scale. The uniform Cu‐Zn distribution is favorable for the formation of zincian malachite with higher Zn fraction, whereas the uneven distribution could lead to either zincian malachite with lower Zn fraction or aurichalcite‐like nonmalachite. These differences in the precursor structure act on subsequent calcination and reduction, as well as their products. Along this path, mixing affects the evolution of the catalyst microstructure by means of Cu‐Zn distribution. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2647–2654, 2018     

旋风分离器排气管内流动分析及减阻机理

利用激光多普勒测速仪(LDV)对旋风分离器排气管内流场进行了全面系统的测量,发现气流的高速旋转、回流区的存在及湍流脉动是排气管内产生流动阻力损失的重要原因. 安装减阻杆改变了排气管内流场分布规律,使旋转动能降低、回流区消失以及湍流脉动减弱,从而降低了排气管内流动阻力损失. 减阻杆迎风截面宽度越大,绕流边缘越尖锐,排气管内切向速度就越小,轴向速度分布越均匀,分离器的减阻幅度也越大.     

A highly efficient Cu/ZnO/Al2O3 catalyst via gel-coprecipitation of oxalate precursors for low-temperature steam reforming of methanol

The impact of preparation methods on the structure and catalytic behavior of Cu/ZnO/Al₂O₃ catalysts for H₂ production from steam reforming of methanol (SRM) has been reported. The results show that the nanostructured Cu/ZnO/Al₂O₃ catalyst obtained by a novel gel-coprecipitation of oxalate precursors has a high specific surface area and high component dispersion, exhibiting much higher activity in the SRM reaction as compared to the catalysts prepared by conventional coprecipitation techniques. It is suggested that the superior catalytic performance of the oxalate gel-coprecipitation-derived Cu/ZnO/Al₂O₃ catalyst could be attributed to the generation of “catalytically active” copper material with a much higher metallic copper specific surface as well as a stronger Cu–Zn interaction due to an easier incorporation of zinc species into CuC₂O₄ · x H₂O precursors as a consequence of isomorphous substitution between copper and zinc in the oxalate gel-precursors.     

管壳式浓硫酸冷却器结垢原因分析及清洗

介绍浓硫酸冷却器的类型以及管壳式浓硫酸冷却器水侧和酸侧出现结垢的原因分析,并提出解决方法.管壳式浓硫酸冷却器水侧污垢主要成分是CaCO3,可采用酸清洗;酸侧污垢主要成分是硅溶胶,可采用热碱清洗.为防止浓硫酸冷却器结垢,应控制好循环水中钙、镁离子浓度及pH值和干吸系统补充水中二氧化硅质量浓度.对已结垢的酸冷却器进行正确清洗,可提高设备的使用周期及换热效率.     

立式花瓣管外空气螺旋流动传热及流阻性能研究

螺旋隔板花瓣管换热器具有优异的换热性能,但由于目前基础数据不足,螺旋隔板花瓣管换热器的应用还未能普及,研究花瓣管几何结构参数对换热过程的影响规律及传热机理,可为该类型换热器提供设计依据.今在实验中通过采用空气在缠绕金属螺旋片的换热管外套管环隙中的换热来模拟螺旋隔板换热器的换热过程,研究了空气在缠绕螺旋片的立式光滑管和不同翅片高度与间距的立式花瓣管外螺旋流动的传热与流阻性能,分析了花瓣管翅片高度和间距等主要几何结构参数以及管外空气流速对传热与流阻性能的影响.实验结果表明:翅片高1.5mm、间距1.0mm的花瓣管具有最佳的传热性能,花瓣管外空气对流换热系数是光滑管的1.48～3.24倍;在实验范围内,随着空气流速的增加,花瓣管外空气对流换热系数与流动阻力也相应增加,但综合换热性能下降并在空气流速为36.0～42.2m·s-1时达到最低值.