100m高烟囱拆除爆破冲击振动测试与分析

在新乡电厂百米钢筋混凝土烟囱爆破拆除工程中,布置了不同方向的两条测线共9个测点,量测了爆破和烟囱倒塌触地引起的地面质点振速和主振频率。从实测数据的分析认识到:烟囱顶部落地产生的冲击力最大,线状震源正前方测点的振速比其侧向测点的振速要大;烟囱倒塌触地产生的振动是各段筒体所产生的振动的叠加,它与各分段体的质量、位置高度、材质强度等因素有关;高大建(构)筑物落地冲击地振动的频率一般比爆破引起的地振动的频率要低;铺设缓冲材料、分段爆破等措施可减小触地冲击引起的地面振动强度。此外,利用实测数据进行拟合,得出了适用于描述本工程烟囱倒塌触地冲击地振动衰减规律的经验公式。     

烟囱的烟气抬升高度的研究

在肯定了烟气抬升高度与整个烟云扩展层内环境平均风速成反比的基础上,对“国标公式”(指GB13223—91中的公式,以下同)进行了修正,推出了新的计算式,并用浙江某热电厂的实测资料进行了验证。经分析比较认为:利用修正后的公式进行计算,其计算的准确性优于“国标公式”。     

狭长区域内120m钢筋混凝土烟囱控制爆破拆除

在狭长区域内实施高烟囱定向爆破拆除,必须解决精确定向和落地冲击问题。本文结合峨眉铝业集团120m钢筋混凝土烟囱的爆破拆除,介绍了出灰口、后坐和偏心等几个重要问题的处理,提出了控制定向精度的方法和工艺手段。文中还介绍了爆破缺口参数的计算、震动安全距离的校核以及作者的体会。     

Wall and ceiling protection for heating appliances

An evaluation was made of the effects of radiant heat transfer from hot stove and chimney pipes to unprotected and protected room walls and ceilings. Pipe surface temperatures were 350° C (662° F) for normal operation, and 400–450° C (752–842° F) to simulate overfire conditions. Unprotected ceilings at 457 mm (18 in.) clearance met code recommended temperature rise limits for normal operation, but protection was needed for overfire exposures. Some protected walls allowed for clearance reductions to 76 mm (3 in.) for all exposures, while others needed at least 304 mm (12 in.) for normal and 457 mm (18 in.) for overfire exposures.Recommendations for model building code specifications for wall and ceiling protection are provided. Reference: Joseph J. Loftus and Richard D. Peacock, Wall and Ceiling Protection for Heating Appliances,Fire Technology, Vol. 21, No. 3, August 1985, p. 213.This paper is a contribution of the National Bureau of Standards and is not subject to copyright.     

80m高钢筋混凝土烟囱的定向爆破拆除

介绍了一座80m高的钢筋混凝土烟囱在定向爆破拆除设计和施工中,所采取的爆破方案、爆破参数和安全防护措施,并对爆破效果进行了分析和描述,对钢筋混凝土烟囱定向爆破拆除提出了一些看法,旨在为同类烟囱的爆破拆除积累成功的经验。     

150m高钢筋混凝土烟囱控制爆破拆除

采用两段两次控制爆破拆除了150m高钢筋混凝土烟囱。通过选用复式梯形爆破缺口和合理的爆破参数,并采用开挖减振沟及铺设缓冲垫层等安全防护措施,使烟囱爆破达到了定向准确、安全、破碎好的效果,可为类似爆破工程提供参考。     

不设GGH时的烟囱排烟筒设计

针对脱硫系统不设GGH时烟气对排烟筒的温度、压力、腐蚀作用,设计体积密度低、强度高、隔热性能好、耐腐蚀、抗渗能力强的耐酸砖砌体排烟筒,该排烟筒具有造价低、施工简单、维护方便的优点和良好的经济效益、社会效益.     

70m砖烟囱定向爆破拆除及结果分析

爆破拆除一座 70m高的砖结构烟囱时 ,该烟囱没有按预期的方向倾倒。文中介绍了设计方案、实际爆破参数以及爆破效果 ,并对爆破中烟囱的实际倒塌结果与设计要求不一致的原因作了详细的分析。     

某在建2Ф5m、高275m烟囱倒塌事故的解析与探讨

该烟囱为多管式烟囱,外筒为钢筋混凝土,内筒为2根直径为5．0m的钢质排烟筒。施工高达240m时瞬间倒塌。前所未有的施工阶段事故,震惊了全球土木工程界,特别是高耸结构设计、研究、施工界。本文结合事故实例,用“雷击原理”较合理地解释了该烟囱的倒塌过程及倒地后令人费解的种种现象。并深刻反省了国内烟囱避雷装置设计施工中现存的各种严重问题及留下的重大隐患,提出了解决对策,仅供烟囱结构、电气、设计研究和施工人员,以及相关规范修编时参考。     

Chimney-enhanced natural convection from a vertical plate: experiments and numerical simulations

This study deals with natural-convection heat transfer from a vertical electrically heated plate, which is symmetrically placed in a chimney of variable height. The heated plate serves as a thermal pump for ventilation of a symmetrical enclosure beneath the chimney.In order to provide a comprehensive picture of the phenomena, three main approaches are used in parallel: temperature and velocity measurements, flow visualization, and numerical simulation. Temperature measurements are done by thermocouples distributed inside the plate and through the chimney. Velocity measurements are performed by means of a precise anemometer. Visualization is performed using smoke of incense sticks, with video recording and consequent image processing. Computer simulations of unsteady flow and temperature fields are performed in 3D and compared with measurements and visualization, with special attention paid to velocity fluctuations. Analysis is presented on the dependence of the temperature distribution on the flow field. The air flow rate on the heating plate in the chimney increases with the chimney height and is adequately predicted by the numerical simulation of the system.