炼油厂高温泵机械密封的应用

为了提高炼油厂高温泵机械密封运行的可靠性和使用寿命,改善高温泵机械密封的使用条件,文章介绍了国内主要密封厂商的技术水平以及高温泵的机械密封选型原则,并从其原理、结构以及选材、加工过程、热处理、过程检测、出厂试验等关键环节进行分析,对如何建立一个可靠密封系统环境进行阐述,对应用中如何保证高温泵机械密封运行可靠性的关键技术...     

硫酸生产中高温蝶阀密封改进探索

分析了硫酸生产中高温蝶阀密封泄漏的实际情况。通过对填料函的间隙、填料材质、密封形式等进行改进探索,最终形成一种填料密封和干气密封相结合的方式,解决了硫酸生产中高温蝶阀在高温和高腐蚀的恶劣环境中频繁泄漏的问题。     

干气密封在高温泵上的应用

高温泵介质为高温导热油,轴封最初采用单端面机械密封,由于介质具有温度高、较脏等特点,导致机械密封频繁泄漏。经认真的分析研究和与干气密封厂家广泛的技术交流,并通过密封厂家设计和核算,把机械密封改造成双端面式干气密封+前置浮环结构。按照设计制造并改造的干气密封性能稳定可靠,泄漏问题得到解决。     

常减压装置高温油泵可靠性技术改造

针对近年来石油化工高温油泵频繁故障,导致着火的事故,本论文提出可靠性密封改造,金陵分公司常减压装置11台高温油泵进行了密封可靠性改造。2012技术改造中,采用了密封改造升级、改变冲洗方式、气动执行机构、在线振动监测技术等措施,改造后效果良好,降低了故障率,保证了高温油泵的安稳长运行。     

适用于高温热水工况的机械密封方案

在高温热水工况下,机械密封润滑性非常差,如果冷却效果不好,机械密封端面在不稳定的似汽相状态下工作,容易造成非正常失效。介绍了一种针对高温热水的工况下机械密封的解决方案,及机械密封的结构形式和材料选择。同时给出了机械密封系统的安装事宜和维护注意事项。     

优化工艺流程,延长多级离心泵机械密封使用寿命

塔里木油田哈六原油临时处理站三台外输泵(多级离心泵)自2013年10月10日投运至2016年5月初,频繁出现高、低压机械密封端高温而保护停机,机械密封端发生频繁刺漏和更换,严重影响了安全生产。为了解决机械密封频繁刺漏和更换问题,利用外输泵高、低压密封端和泵进口端存在的一定压力差,在泵体上制作了一套循环冷却、冲砂工艺流程,改造后机械密封运行良好,探索出了降低多级离心泵高、低压机械密封端高温,延长机械密封使用寿命的新途径。     

高温水泵机械密封泄漏分析与改造

结合实际使用工况,通过对高温水泵密封冲洗方案的分析比较,采用合适的冲洗方式,提出机械密封泄漏的解决方案,并对高温水泵进行了改造。     

垫片高温性能及其表示方法

实验研究了柔性石墨复合垫片、金属包覆垫片、非石棉纤维橡胶垫片、石棉橡胶垫片的常温和高温力学性能和密封性能,探讨了垫片高温密封的基本规律,提出了较好地表征垫片压缩回弹特性、基本密封特性和蠕变性能的公式,通过试验数据的回归分析,得到了公式中的各系数,为高温工况下密封件的选用、螺栓法兰连接设计和紧密性评定提供了依据。     

高温阀门阀杆填料密封技术探讨

分析了阀杆填料密封的原理和存在的问题,针对高温阀门的使用工况,说明了选择填料材料的方法,列举了几种典型的高温阀门阀杆填料密封结构,给出了安装填料密封的注意事项。     

高温重油泵用金属波纹管机械密封失效分析

分析了某石化公司常减压装置中高温重油泵用机械密封失效的主要原因,为其机械密封设计提供指导,实现了高温重油泵轴封的长周期安全运行。     

High-pressure synthesis of TaN compacts with high hardness and thermal stability

High-hardness TaN compacts with a diameter and height of 6 mm were synthesized through the phase transformation of CoSn-type into WC-type TaN under experimental conditions of high temperature and high pressure. The Vickers hardness of WC-type TaN compacts obtained at the pressure of 5 GPa and the temperature of 1873 K is found to be ~21.5 ± 1.5 GPa with a load of 3 Kg, which is comparable to that of the pure tungsten carbide compact (~20 GPa) and higher than those of ultrahigh temperature ceramics ZrB₂ and HfB₂ under the same load. The high hardness of WC-type TaN compacts presented in this work is attributed to the deviatoric strain and well-bonded nanograins. The synthesized WC-type TaN compacts also possess a high oxidation temperature (1072 K). These results suggest that the WC-type TaN with high hardness and high thermal stability holds great promise for industrial applications.     

高温高压锅炉在干熄焦工程中的应用

结合以往对各种干熄焦锅炉的标定数据以及在干熄焦锅炉选择过程中存在的制约因素,对干熄焦装置的生产能力、工程投资及企业现状等因素进行对比分析,为干熄焦锅炉炉型的选择提供了建议。同时针对高温高压自然循环干熄焦热力系统和中温中压联合循环干熄焦热力系统,在节能方面、锅炉效率、钢材消耗、系统电力消耗、发电量的差异以及锅炉的开工与运行方面的差异进行了对比分析,进而了解两种参数的热力系统在各方面的优缺点。     

Further insights into thermoelectric properties of nonstoichiometric titanium oxide fabricated by high pressure and high temperature

The present work explores the feasibility of advancing the thermoelectric properties of nonstoichiometric TiO_2?x through introducing more and more oxygen deficiencies. Compared with previous work, it is found that this compositional manipulation induces phase transition; in addition, the scattering mechanisms of both carrier and phonon have changed, resulting in the temperature-independent electrical resistivity, inferior electrical performance and an unexpected high thermal conductivity. As a consequence, a moderate zT value of 0.13 is obtained in TiO_1.72 at 600?℃. Through this work, we understand deeply about thermoelectric properties of nonstoichiometric titanium oxide by high pressure and high temperature, and further investigations about this system have been directed.     

Recrystallization behaviour of cubic boron nitride under high pressure

The recrystallization behaviour of micron-sized cubic boron nitride (cBN) was studied by analysing the grain size and morphology of samples treated at 8−16 GPa/1500–2200 °C. The results show that the recrystallization temperature of cBN under a pressure of 8 GPa is approximately 1650 °C and increases by approximately 100 °C with every 2 GPa increase in pressure. Once grain recrystallization starts, the grains grow abnormally quickly as the temperature rises, and the strengthening effects of grain refinement and defect structure are greatly weakened. The recrystallization behaviour of cBN at high pressure is helpful to understand the sintering mechanism and control the microstructure and mechanical properties of sintered polycrystalline cBN compacts. In addition, the melting curve for cBN under high pressure is inferred according to the empirical relationship between recrystallization temperature and melting temperature, and the phase diagram for boron nitride is revised based on this new melting curve.     

Adiabatic premixed combustion in a gaseous fuel porous inert media under high pressure and temperature: Novel flame stabilization technique

This work presents an experimental investigation to study the characteristics of combustion using a premixed methane-air mixture within a non-homogeneous porous inert medium (PIM) under high pressure and temperature. In order to obtain a stable flame under these operating conditions within PIM, a novel flame stabilization technique in porous inert media (PIM) combustion under high pressure and temperature has been developed and evaluated. The proposed technique avoids the draw backs of the hitherto developed techniques by properly matching the flow and flame speeds and, consequently, ensuring a stable combustion, for a wide range of operating pressure and temperature. The success of this technique permits the extension of PIM combustion to new applications such as gas turbines. The validity of this new technique has been assessed experimentally in detail by analyzing combustion inside a prototype burner. The effects of various operating conditions, such as initial preheating temperature and elevated pressure, have been examined for an output power range between 5 and 40 kW. The experiments covered a broad spectrum of operating conditions ranging from a mixture inlet temperature of 20 °C and pressure ratio of 1 up to a temperature of 400 °C and a pressure ratio of 9. Evaluation of the results revealed excellent flame stability with respect to both flashback and blow-out limits throughout all the operating conditions studied, including relative air ratios far beyond the normal lean limit. While the blow-out stability showed no significant dependence on pressure, it was strongly determined by the preheating mixture inlet temperature. A remarkable broadening of the stability range from 0.6 to 1.0 on preheating to 400 °C was observed. This reveals the potential of pre-heat temperature to improve the dynamic modularity of the burner.     

In-situ synchrotron x-ray study of phase transitions in melamine under high pressures and high temperatures

We report a synchrotron energy-dispersive x-ray diffraction study of melamine at high pressure and high temperature. Pressure was generated using a Paris-Edinburgh cell to employ larger sample volumes for weakly scattering organic samples. High temperatures were created using a resistive/graphitic cup surrounding the sample. The PT phase diagram was explored by first pressurizing the sample to 3.5 GPa at room temperature and then heating it up to 1197 K with a concomitant pressure increase to just above 5 GPa. Above 4.85 GPa and 967 K, an irreversible phase transition was observed. Upon cooling the sample, another phase transition was observed which is likely associated with polymerization observed in earlier ex-situ HPHT experiments.     

Liquid phase assisted high pressure sintering of dense TiC nanoceramics

To address the difficulty of achieving high density while effectively suppressing grain growth in the fabricating of nanoceramics, this paper demonstrates a novel integrated approach, consisting of a solid-liquid reaction, high pressure and low temperature sintering, to prepare dense nanocrystalline TiC ceramics. Using Si as the additive, a low-viscosity Si liquid phase is formed under the sintering condition of 1200?°C/4.5?GPa. It is shown that both of the sintering aid and high pressure are crucial in achieving high density nanostructured TiC ceramics and controlling their microstructure and thus their mechanical properties. The pure TiC can be sintered to reach 95.3% of its theory density and, with the assistance of liquid Si additive, it can be sintered to full densification without grain growth by high pressure technique.     

Microstructure and luminescence properties of the high pressure high temperature sintered AlN–TiN ceramics

Composite ceramics of titanium nitride grains incorporated in an aluminium nitride matrix have been synthesized by high pressure high temperature treatment of a mechanical mixture of AlN–TiN (3 mol % TiN) powders. The microstructure of the samples analysed by means of electron beam microanalysis and Raman spectroscopy shows that the formation of cubic AlN in the composite begins near titanium nitride grains. The areas of mixed chemical composition, which can be assigned to the formation of the solid solutions Al_1?xTi_xN, have been observed at the phase interfaces. The luminescence properties of AlN–TiN ceramics have been considered focusing on the choice of high pressure and high temperature treatment conditions. Three main components at 2.0 eV, 2.4 eV and 3.1 eV are revealed in the cathodoluminescence spectra analysed quantitatively. The observed emission originates from the radiative transitions with participation of valence band states, oxygen-vacancy centres (V_Al–O_N), nitrogen vacancies V_N, and shallow donors which form a complex system of energy levels in the bandgap of the wurtzite-type AlN.     

Flow characteristics in an acoustic bubbling fluidized bed at high temperature

The pressure fluctuation of the quartz sand and SiO₂ particles was investigated using pressure transducer in high temperature fluidized bed with sound assistance. The effects of bed temperature, sound wave frequency, and sound pressure level (SPL) on the pressure fluctuation were examined. It indicates that the minimum fluidization velocity decreases with an increase in sound pressure level at the same sound frequency. At the same SPL and bed temperature, there always exists an optimal frequency range achieving good fluidization quality. As the sound frequency increases, the minimum fluidization velocity decreases firstly and then increases. Based on the statistical analysis of pressure signals, the effect of sound frequency on the fluidization quality at high-temperature fluidized bed was presented. On basis of discrete wavelet transform, an original signal was resolved into five-detailed scale signal. Furthermore, the peak frequency for Scale 3 detail signal represents the bubbling frequency.     

高温高压蒸汽分支管线的变幅值热疲劳裂纹扩展寿命研究

研究了一条高温高压蒸汽分支管线失效面上周向焊缝外表面裂纹在１７级温度载荷谱作用下的变幅值热疲劳裂纹扩展寿命。计算中涉及到管子周向焊缝外表面裂纹Ｋ的求取、超载模型的选用及谱载下裂纹扩展寿命计算等