南京第二热电厂制粉系统调整与节能

通过对制粉系统进行试验，提出了制粉系统合理运行方式，解决了该厂制粉出力不足的问题，取得较高的经济效益。     

负压中间储仓式制粉系统的安全性综合评价

哈三电厂200MW 机组采用的是负压中间储仓式制粉系统，由于其本身的设计缺 陷还有人为的不合理运行方式，多年来一直严重存在安全运行隐患。曾经多次发生制粉系统爆 破，数度造成设备报废，锅炉灭火，甚至于人身伤害。就其本身设计缺陷，及人为的不合理运行 方式所带来的安全隐患进行综合分析。     

齐鲁石化热电厂制粉系统的能耗分析

本文通过对齐鲁石化热电厂六台ＨＧ４１０／１００Ⅱ型锅炉配置的中储仓式制粉系统运行现状的评价，分析其电能损耗、金属材料损耗过程及方式，探索制粉系统及磨煤机的改进措施，并达到提高制粉系统出力，降低制粉系统能量损失的目的。     

中储式制粉系统的节能降耗综合治理

文章针对某电厂135MW机组中储式制粉系统存在的制粉电耗高等一系列问题．进行了优化调整试验,在此基础上分析了制粉电耗高的原因,并对部分设备进行了改造。通过试验调整得出制粉系统的最优运行参数,使该电厂的制粉电耗降低4．5kWh／t,取得了良好的综合治理效果。     

W火焰双拱型1025t／h无烟煤锅炉制粉系统的选择

本文通过对１０２５ｔ／ｈ无烟煤Ｗ火焰双拱型锅炉制粉系统的技术经济分析论证，提出了我国３００ＭＷ无 发电机机组锅炉制粉系统的选择意见。     

火力发电厂磨煤机及制粉系统选择设计应注意的问题

该文介绍了磨煤机的种类和比较，制粉系统的类别和比较。提出了火力发电厂设计磨煤机及制粉系统选择应注意的问题，强调了要注意遵守设计规程规范；煤质资料要准确齐全，磨煤机选择要考虑煤种变化，制粉系统选择要考虑煤种及锅炉燃烧要求，制粉系统选择要进行技术经济比较等。给出了火力发电厂选择不同磨煤机，不同制粉系统的实例供大家参考。     

F—35／39—Y／2型锅炉节能综合改造

某热电厂Ｆ－３５／３９－Ｙ／２型锅炉原设计煤种为烟煤，制粉系统干燥剂为热风－温风。而实际燃用煤种为褐煤，致使制粉系统干燥出力不足，一次风温仅为４０℃￣５０℃。煤粉水分高达１０％￣１５％，锅炉燃烧不稳，热效率不下降。把制粉系统干燥剂改为抽高温炉烟＋热风＋温风，并采用双通道旋流燃烧器后，一次风温提高到１１０℃￣１３０℃，煤粉水分下降到２．８％￣４．１％。锅炉热效率提高了５．０％，显著地改善了锅炉燃烧的     

基于自适应模糊控制的制粉系统运行优化与节能控制

针对巴陵石化热电装置制粉系统电耗偏高、煤粉细度不稳定、控制参数波动大等诸多问题,通过理论分析和实验相结合的方法,研究系统的最佳运行工况,再以非线性控制理论为基础,对整个制粉系统实施全局自动控制,确保制粉系统严格工作在最佳工况区域以及该制粉系统的长期可靠运行。有效地控制了煤粉的均匀度,降低了制粉电耗,减少了炉水排放,锅炉热效率提高1.62%。     

中储式制粉系统综合治理与节能降耗

通过对制粉系统的试验分析 ,探求了中储式制粉系统出力小、单耗高的原因 ,并通过优化调整试验 ,提出综合治理方案 ,达到了节能降耗的目的     

排粉机振动改造与节能运行

通过对某热电厂制粉系统排粉机及其出口风箱振动原因分析,实施了排粉机改造的治理措施,消除了制粉系统振动,保证了温风送粉系统正常投入运行,降低了锅炉排烟温度,提高了锅炉效率,节约了能源,为该厂锅炉长周期的安全经济运行奠定了良好基础。     

Thermoreactions between molten salts and water at high cooling rates

New experimental results of the investigations of “steam explosion” in ionic melts are described. The existence of a long lived local area of increased optical density is established. Caused by initial perturbation (like water droplet, laser beam, etc.), the area moves through the melt and disappears simultaneously with the explosion. Also, characteristic electromagnetic radiation is for the first time registered in the ultraviolet and infrared spectra during the time before the explosion. The results described show that although the water can trigger the process (in accordance with the “steam explosion” concept), the phenomena related to the explosion are intrinsic to the phase transformations in the melt. These phenomena can hardly be understood in the framework of the standard theory of the first-order phase transitions.     

The simulation and analysis of leakage and explosion at a renewable hydrogen refuelling station

The number of hydrogen refuelling stations (HRSs) is steadily growing worldwide. In China, the first renewable hydrogen refuelling station has been built in Dalian for nearly 3 years. FLACS software based on computational fluid dynamics approach is used in this paper for simulation and analysis on the leakage and explosion of hydrogen storage system in this renewable hydrogen refuelling station. The effects of wind speed, leakage direction and wind direction on the consequences of the accident are analyzed. The harmful area, lethal area, the farthest harmful distance and the longest lethal distance in explosion accident of different accident scenarios are calculated. Harmful areas after explosion of different equipments in hydrogen storage system are compared. The results show that leakage accident of the 90 MPa hydrogen storage tank cause the greatest harm in hydrogen explosion. The farthest harmful distance caused by explosion is 35.7 m and the farthest lethal distance is 18.8 m in case of the same direction of wind and leakage. Moreover, it is recommended that the hydrogen tube trailer should not be parked in the hydrogen refuelling station when the amount of hydrogen is sufficient.     

Comparison of the explosion characteristics of hydrogen,propane, and methane clouds at the stoichiometric concentrations

Numerical simulations were performed to study explosion characteristics of the unconfined clouds. The examined cloud volume was 4 m × 4 m × 2 m. The build-in obstruction inside the cloud was the 8 × 8 × 4 perpendicular rod array. The obstacle volume blockage ratio was 0.74. Three gases were considered: hydrogen/air at the stoichiometric concentrations, propane/air at the stoichiometric concentrations, and methane/air at the stoichiometric concentrations. The hydrogen/air cloud explosion has higher peak overpressure and the overpressure rises locally at the nearby region of the cloud boundary. The explosion overpressures of both methane/air and propane/air are lower, compared with the hydrogen/air, and decreases with distance. The maximum peak dynamic pressure is reached beyond the original cloud, which is clearly different from the explosion peak overpressure tends. Furthermore, dynamic pressure of a cloud explosion is of the same order as overpressure. The explosion flame region for the hydrogen/air cloud is approximately 1.25 times of the original width of the cloud. The explosion flame regions for propane/air or methane/air clouds are approximately 1.4 times of the original width of the cloud. Unlike the explosion overpressures, the explosion temperatures have little difference between the three mixture examined in this study. The higher energy of explosive mixture generates a high temperature hazard effect, but the higher energy of explosive mixture may not generate a larger overpressure hazard effect in a gas explosion accident.     

Experimental and numerical study of the influence of initial temperature on explosion limits and explosion process of syngas-air mixtures

To study the effect of initial temperature of 30, 60, 90, and 120 °C on the explosion limits and the explosion process of the syngas-air mixtures, the explosion limits were tested by the explosive limit instrument, and the flame propagation process in the spherical pressure vessel was recorded by the high-speed camera. The ANSYS Fluent 3D software was used to simulate the explosion behavior of syngas-air mixtures. The results showed that with the increase of the initial temperature, the lower explosion limit of syngas decreased and the upper explosion limit increased, and the effect of initial temperature on the upper explosion limit of syngas was greater than that on the lower explosion limit. The flame development process in the simulation was consistent with that in the experiment, propagating outward spherically until it filled the entire container. Both experimental and numerical results presented the same trend of accelerating the flame propagation speed with the increase of initial temperature. In addition, the simulation also obtained multi-dimensional transient explosion parameters that were difficult to obtain in the experiment. The explosion process of syngas was analyzed by the explosion parameters such as temperature and pressure field in the explosion area. An increase in temperature decreased the maximum explosion pressure and shortened the time to reach the maximum explosion pressure.     

电渣炉车间爆炸和窒息事故原因探讨及预防原则

爆炸是电渣炉车间破坏性最强的事故类型,电渣炉车间曾发生过惰性气体导致的窒息死亡较大事故。爆炸事故的直接原因是蒸汽爆炸,通过计算和理论分析描述了爆炸能量的主要来源。窒息事故的直接原因是机体缺氧,作业环境中惰性保护气体升高会导致氧含量和分压降低。分别从物的不安全状态、人的不安全行为和不良的作业环境三个方面探讨了电渣炉车间爆炸和窒息发生的间接原因。最后提出了电渣炉车间爆炸和窒息事故预防和控制的原则。     

Experimental and theoretical investigation on hydrogen cloud explosion subjected to external turbulence

This work is to experimentally and theoretically explore the hydrogen cloud explosion subjected to external turbulence. In the experiments, the flame characteristics and explosion pressure are obtained using high-speed camera and pressure sensor. In the theoretical calculation, the peak explosion pressure is obtained using LM, LMIET and TM method. The results indicated that most flame characteristics in the experiments are located in the zone of wrinkled flamelets. The explosion-related parameters including flame propagation velocity, peak explosion pressure and peak rate of pressure rise continue to increase as the gear level increases from G0 to G3, increase firstly and then decrease as the equivalence ratio increases from Φ = 0.5 to Φ = 3.0. Due to ignoring flame acceleration propagation induced by flame instabilities, external turbulence and flame-induced turbulence, the peak explosion pressure obtained using experimental method is significantly larger than that obtained using LM method. Owing to considering the limit value of flame wrinkling level induced flame instabilities and flame-induced turbulence, the peak explosion pressure obtained using experimental method is significantly lower than that obtained using LMIET and TM method.     

Dynamic couplings of hydrogen/air flame morphology and explosion pressure evolution in the spherical chamber

This paper aims at exploring the dynamic couplings of flame morphology and explosion pressure evolution experimentally and theoretically. In the experiment, flame morphology and explosion pressure evolution under diffusional-thermal and hydrodynamic instability are recorded using high-speed schlieren photography and pressure transducer. In the theoretical calculation, the effects of cellular flame on the explosion pressure evolution are conducted using smooth flame, D = 2.0566, 2.1 and 7/3. The results demonstrate that the cellular flame formation of various equivalence ratios could be attributed to the fact Lewis number is less than unity on the lean side. The flame destabilization of Φ = 0.8 and 3.0 with increasing initial pressure is due to the decreasing flame thickness regardless of unchangeable thermal expansion ratio. Much smaller cells formation on the cellular flame surface as the explosion pressure rises could be attributed to the joint effect of the diffusional-thermal and hydrodynamic instability. Note that the explosion pressure evolution in spherical chamber is obviously underestimated assuming the flame surface is smooth during the hydrogen/air explosion. But the explosion overpressure is overpredicted significantly with D = 7/3. The theoretical overpressure with D = 2.1 is in satisfactory agreement with experimental results.     

On the explosion limit of syngas with CO2 and H2O additions

In this study, the pressure-temperature explosion limits of H₂/CO/O₂/CO₂/H₂O mixtures are analyzed computationally and theoretically. The result indicates that with the increase of H₂O and CO₂ mole fractions, the explosion temperatures are increased around all the three explosion limits. Furthermore, the increase of the explosion temperature is higher with the addition of H₂O compared with the addition of CO₂ near the second explosion limit. In addition, the increase of the explosion temperature near the first and third explosion limit is almost the same for the addition of these two inter gases. The single-limit expression analysis shows that the first explosion limit is mainly controlled by the changing of the oxygen concentration with the addition of inert gas; the changing of the second explosion limit is caused by the changing of the reaction rate of H + O₂ (+M)→HO₂ (+M), which is indirectly through the Chaperon efficiency of the third body recombination reaction, and the effect of inert gas addition on the third explosion limit is mainly caused by the changing of the hydrogen concentration.     

Effects of mesh aluminium alloys and propane addition on the explosion-suppression characteristics of hydrogen-air mixture

Accidents involving hydrogen explosions occur frequently, yet systematic methods of explosion suppression have not been investigated and applied. Therefore, this paper studied the deflagration characteristics in hydrogen with the addition of propane in the tube filled with mesh aluminium alloys (MAAs). The effects of different propane contents and different filling densities (the mass of MAAs per unit volume in a vessel) on the explosion suppression of the premixed gas are examined. The results show that propane and MAAs can effectively suppress the hydrogen-air explosion. However, MAAs have multiple suppression/promotion effects on the propane-hydrogen explosion. Based on the mathematical model, the dominant effect of MAAs changes abruptly toward the promoting effect when the hydrogen content exceeds 72.26% of the premixed gas stoichiometric concentration. It is also found that an increase in filling density would have a beneficial effect on explosion suppression. The study results provide references for preventing hydrogen and hydrogenated hydrocarbon fuels explosions and optimizing the performance of MAAs.     

Effects of turbulence on dust explosions

An inherent part of the dust explosion problem is understanding and dealing with the influence of turbulence on explosion development. This paper reviews effects of turbulence on the following dust explosion parameters: flame propagation rate, maximum explosion pressure, maximum rate of pressure rise, flammability or explosibility limits and minimum ignition energy. The discussion is substantiated with quantitative data and, in the absence of any such data, qualitative observations are presented. Reasons for the discrepancies among test results from large- and small-scale explosion vessels are given.