锅炉管道20万小时寿命探讨

本文通过对ASME标准和EN标准确定最大许用应力方法的比较,及EN标准100,000h和200,000h蠕变持久强度进行类比,得出ASME材料通过ASME标准进行设计制造的锅炉管道在高温稳压运行下,完全能够使用200,000h。经验已经证明,使用ASME标准设计的锅炉管道已经安全运行超过200,000h。     

一台进口异型锅炉的强度分析

文章采用有限元方法对一台进口异型锅炉进行了强度分析和评定 ,计算结果表明锅炉在设计条件下满足强度要求。通过进一步分析指出筋板的状况是保证该锅炉安全运行的关键因素 ,并对锅炉制造检验和定期检验提出了要求     

锅壳锅炉检查孔的布置

锅炉设计应本着安全、高效、低耗，的原则，从另一个角度讲还应好造、好修、好用，从锅炉设备本身的特点来讲，在正常运行条件下。锅炉元件所受的热应力，及高温腐蚀性介质同时作作在元件壁上。因此，锅炉受压元件的受载情况比一般机械零件要复杂得多。为保证锅炉的正常使用，     

全自动软水器的选型及应用

锅炉水处理设备是保证锅炉安全运行,节能减排的重要手段之一。全自动软水器是目前较为流行的锅炉水处理设备。本文阐述了全自动软水器的工作原理、工艺过程、选型方法以及在实际操作中应注意的问题,为广大锅炉水处理设备使用单位提供帮助和指导。     

冶金企业锅炉的运行维护与优化

在冶金企业的日常生产运行过程中,锅炉是其系统中的关键设备之一,锅炉的安全、高效、稳定运行,不仅关系到企业运行的效率,还影响着企业的环保效果和经济利益。锅炉是冶金生产中基本能量转换设备,为保证锅炉的正常运行,需要遵守一定的原则,并加强对锅炉及其设备的检查与维护,对影响锅炉使用的因素以及锅炉管道的材料选择进行分析,并探讨了具体的锅炉维护的策略和方法。     

循环流化床锅炉水冷排渣管的强度计算

给出了循环流化床锅炉水冷排渣管的强度计算方法,可供部件结构设计者参照使用,以便设计出更加经济、安全、合理的结构。     

高压换热器低循环疲劳强度的计算分析

为了较为准确的评估高压换热器在循环热冲击和压力冲击下交变应力对设备疲劳强度的影响,针对高压换热器,建立合理的三维有限元模型,分析三种典型启动工况下管板和管箱的温度场以及应力场分布,按照锅炉及压力容器规范ASME-Ⅷ-2进行应力强度评定与疲劳校核,结果表明高压换热器结构在全负荷工况下应力满足强度要求,并得到设备在三种典型循环启动工况下允许的循环次数,为高压换热器的安全运行提供依据.     

槽式太阳能光热电站辅助锅炉选型研究

辅助锅炉是光热电站不可或缺的辅机设备,与机组的启动耗时和运行安全息息相关。由于行业发展时间较短,我国现阶段并未就光热电站辅助锅炉的选型形成统一标准。针对槽式光热电站的运行特点,针对某槽式光热电站辅助锅炉的蒸汽参数和容量选择进行了研究。结果表明:可以在保证机组安全启停和运行的前提下,降低辅助锅炉的设计容量,节省投资。     

锅炉安全性比较及爆炸事故预防

截至2008年底，全国共有锅炉57．82万台，其中中小锅炉占有一定比例。中小锅炉的广泛使用，给人民生活带来了方便，但是由于部分中小锅炉存在着产品结构不合理，制造质量低劣，加之目前我国在中小锅炉七个环节（设计、制造、安装、修理、改造、使用和检验）以及人员素质等方面的技术规定和管理还不够完善，造成中小锅炉爆炸事故频发，严重地威胁着人民生命和财产安全。     

挥发性有机化合物余热锅炉的设计

介绍了一台VOCs余热锅炉的设计及运行,该余热锅炉采用烟管蒸发器和水管蒸发器相结合的结构进行热交换。锅炉设计蒸发量53 t/h,实际运行时因余热烟气量不足,锅炉蒸发量为47. 5 t/h。为消除运行中省煤器水击现象,将省煤器改成热水下进上出的型式,使锅炉运行安全、稳定。     

铸铁锅炉爆破压力的热态试验和理论分析

基于一次大规模热态爆破试验的结果,分别对方箱试件、球墨铸铁锅炉的爆破压力、灰口铸铁锅炉和灰口铸铁锅片的爆破压力进行了计算和分析,得出安全系数选取的推荐值。试验和分析表明,铸铁锅炉运行安全可靠。     

某船主锅炉过热器管束爆管原因分析及解决措施

针对某船主锅炉过热器管束的爆管问题,对管束材料、过热器结构及系统运行等方面进行试验、计算及分析讨论,明确了爆管产生的原因－过热器集箱隔板装置因运行操作不当,突然承受大的压差而变形,导致蒸汽短路而爆管。为此,提出了解决措施,消除了产生爆管的因素。     

1D plane numerical model for boiling liquid expanding vapor explosion (BLEVE)

The depressurization of a vessel containing saturated or subcooled liquid may occur in a variety of industrial processes and often poses a potentially hazardous situation. A 1D plane numerical model was developed for estimating the thermodynamic and the dynamic state of the boiling liquid during a boiling liquid expanding vapor explosion (BLEVE) event. Based on the choice of the initial nucleation sites density, the model predicts, simultaneously, the bubble growth processes in the liquid at the superheat-limit state, the front velocity of the expanding liquid, and the shock wave pressure formed by the liquid expansion through the air.Conditions of shock formation were found to be normally associated with high initial temperatures that can bring the liquid to its superheat-limit state during the initial depressurization. Furthermore, the high initial temperature also induces a generation of higher vapor pressures that forces a rapid mixture expansion.Model predictions of the shock wave strengths, in terms of TNT equivalence, were compared against those obtained by simple energy models. As expected, the simple energy models over predicts the shock wave strength. However, the simple model which accounts for the expansion irreversibility, produces results which are closer to current model predictions.     

400t/h燃煤锅炉粉仓爆炸的原因分析及防止对策

制粉系统煤粉自燃和爆炸直接影响锅炉机组安全与经济运行。本文结合某电厂1#炉制粉系统粉仓爆炸事件,对其原因进行分析,并提出了粉仓爆炸事故的预防及处理措施。     

The effect of vent burst pressure on a vented hydrogen–air deflagration in a 1 m3 vessel

A series of experiments are conducted to investigate the effect of vent burst pressure on stoichiometric hydrogen–air premixed flame propagation and pressure history in a 1 m³ rectangular vessel in this paper. Pressure buildup and flame evolution are recorded using piezoelectric pressure transducers and a high-speed camera, respectively. The results show typical pressure peaks of three different mechanisms for all vent burst pressures in the experiments. The first pressure peak, generated by the rupture of the vent cover, increases with the vent failure pressure, with the subsequent outflow inertia of combustion products giving rise to a negative pressure. The second pressure peak results from the constant bulk motion of the flame bubble (the Helmholtz oscillation), and the third is produced by the interaction between the combustion waves and the acoustic waves. The time interval between the first pressure peak and the second pressure transient remained nearly constant. The Helmholtz oscillation always appears as the vent ruptures and its magnitude increases with the vent burst pressure. Furthermore, the lower the vent failure pressure, the longer the Helmholtz oscillation is sustained. The peak of the acoustically enhanced pressure always occurs within several milliseconds of the flame front touching the vessel. From a theoretical perspective, Rasbash's equation models the relationship between the maximum reduced explosion overpressure and the vent burst pressure precisely. Also, it is observed that the maximum lengths of the external flames were found to be nearly identical in all tests, but the average propagation rate of the flame front increases with the vent burst pressure. It is interesting that a phenomenon of intense oscillation of internal flame bubble was observed with the increase of vent burst pressure.     

Rethinking “BLEVE explosion” after liquid hydrogen storage tank rupture in a fire

The underlying physical mechanisms leading to the generation of blast waves after liquid hydrogen (LH2) storage tank rupture in a fire are not yet fully understood. This makes it difficult to develop predictive models and validate them against a very limited number of experiments. This study aims at the development of a CFD model able to predict maximum pressure in the blast wave after the LH2 storage tank rupture in a fire. The performed critical review of previous works and the thorough numerical analysis of BMW experiments (LH2 storage pressure in the range 2.0–11.3 bar abs) allowed us to conclude that the maximum pressure in the blast wave is generated by gaseous phase starting shock enhanced by combustion reaction of hydrogen at the contact surface with heated by the shock air. The boiling liquid expanding vapour explosion (BLEVE) pressure peak follows the gaseous phase blast and is smaller in amplitude. The CFD model validated recently against high-pressure hydrogen storage tank rupture in fire experiments is essentially updated in this study to account for cryogenic conditions of LH2 storage. The simulation results provided insight into the blast wave and combustion dynamics, demonstrating that combustion at the contact surface contributes significantly to the generated blast wave, increasing the overpressure at 3 m from the tank up to 5 times. The developed CFD model can be used as a contemporary tool for hydrogen safety engineering, e.g. for assessment of hazard distances from LH2 storage.     

Lower limit of homogeneous nucleation boiling explosion for water

In this paper, the lower limit for the occurrence of homogeneous nucleation boiling explosion during water heating at atmospheric pressure has been determined by applying a new theoretical model proposed by the authors. Two different cases of water heating have been considered for the study of homogeneous nucleation boiling explosion. In one case, the liquid on the surface is linearly heated at a rate of 10 K/s to 10⁹ K/s. In another case, the liquid suddenly contacts with a high temperature surface such as in case of quenching with impinging jet or droplet. With the assumption of liquid boiling without any cavity or surface effect, the liquid temperature limit at which homogeneous boiling explosion occurs essentially corresponds to a value of 302 °C even though the surface is heated very slowly. On the other hand, during water contact with hot surfaces, the occurrence of the homogeneous boiling explosion within a characteristic time period of 1 ms is obtained at a maximum liquid temperature of 303 °C for a limiting steady state boundary temperature of about 304 °C. From the definition of the steady-state interface boundary temperature of two 1-D semi-infinite body contact problem, the lower limiting surface temperatures for the occurrence of the homogeneous nucleation boiling explosion have been determined for water contact with various solid surfaces at different initial liquid temperatures ranging from 0 °C to 100 °C. The effects of the parametric variation in the boundary heating conditions on various characteristics of the homogeneous boiling explosion such as liquid temperature and time of boiling explosion, heat-flux across the liquid–vapor interface at the boiling explosion, etc. are determined and compared with other results reported in the literature.     

External overpressure of vented hydrogen-air explosion in the tube

Vented explosion experiments involving hydrogen-air mixtures are performed in a 2 m-long cylindrical tube under the influences of the hydrogen concentration and vent burst pressure. Photos of the external flame shot by a high-speed camera show that the jet flame was expelled outside the vessel, and the relation between the flame propagation and external overpressure is summarized. The internal peak overpressure increases and then decreases with increasing hydrogen concentration. In contrast, the external peak overpressure exhibits the opposite correlation in comparison with the internal peak overpressure. The variations in the pressure peaks of the internal pressure curves are also discussed. When the hydrogen concentration is lower than 40 vol %, the second pressure peak plays a more dominant role than the other pressure peaks. However, when the hydrogen concentration is higher than 40 vol %, the third pressure peak becomes more dominant.     

燃煤电站锅炉塌灰落渣引发灭火的爆燃机理分析

对于某些燃用高挥发份,高灰份且易结渣煤的电站锅炉,在正常运行中,频繁发生因炉膛上部较大体积的掉渣或塌灰而造成锅炉瞬间灭火事故,在排除其它有的因素外,提出炉膛下部发生可燃气体爆燃的推测,并结合锅炉的实际运行工况对发生爆燃引起灭火的机理进行了初步分析,能够比较合理地解释灭火的原因,并具有新颖听理论价值,对采取相应的解决措施有比较重要的参考价值。     

分层对液化石油气储罐热响应的影响

由于液化气热分层的存在，LPG储罐内的压力增长加快。同时，还可能影响到蒸汽爆炸。液化石油气温度越高，泄压时产生的气泡量就越大。当温度接近过热极限时变化更加剧烈。所以研究蒸汽爆炸，不可能不考虑分层。对液化石油气储罐内的热分层现象进行了数值模拟，并分析了分层现象对蒸汽爆炸等响应过程的影响。