某卷烟配送立体仓库火灾及烟气控制数值试验

发布时间：2019-03-12 09:27

【摘要】：烟草类仓库发生火灾时,不仅具有普通仓库火灾的特点,更由于其储存物有较强的可燃性,使得火灾一旦发生会在短时间内迅速蔓延不可控制,烧毁大量烟草产品和机器设备,造成巨大的经济损失。研究仓库火灾发生发展规律对于卷烟仓库的火灾危险的消除、控制和保护人员和财产损失具有重要意义。论文以某城市卷烟配送立体仓库为研究对象,运用FDS火灾模拟软件对其火灾及烟气运动和控制进行了数值试验。首先,选取仓库内典型成品卷烟作为样本进行热重分析,通过热解实验测得烟丝的着火温度、燃烧特性指数、活化能值,为数值试验参数设置提供依据。其次,根据仓库实体尺寸建立数值模型,运用FDS大涡模拟方法分别对其在无排烟措施下和自然排烟、机械排烟下的火灾场景进行模拟计算,得到各场景火灾烟气蔓延规律及温度分布情况,并对自然排烟和机械排烟效果进行对比。结果表明：自然条件下火势发展迅速,温度、CO浓度、能见度各参数很快达到人的危险耐受极限,人员安全疏散时间只有326s；自然排烟效果较好,机械排烟改善了火场的能见度并降低了CO含量,但由于机械负压作用将大量新鲜空气引入火场,使火灾加剧。按照NFPA92B中根据烟层高度和火灾强度计算方法设置的机械排烟量将烟层高度控制在4.5m处,相比《高层建筑防火设计规范》体积换气法设计更为合理。最后,按照数理统计原理将排烟口位置、排烟口数量、排烟口风速、排烟量四个因素排列组合,用FDS对组合条件下的火灾场景进行试验,讨论各因素对机械排烟效果的影响。结果表明：“顶棚”排烟优于“侧壁”排烟；在排烟量一定的情况下增加排烟口数量排烟效果较好；增大排烟量有利于烟气排出,但另一方面又会加剧火势；排烟口风速过大会造成烟气“吸穿现象”,降低排烟效率,因此应根据建筑的具体参数进行合理设置,过大过小都无法取得理想的排烟效果。
[Abstract]:When a fire occurs in a tobacco warehouse, it not only has the characteristics of a common warehouse fire, but also has a strong flammability of its storage, which makes the fire spread uncontrollably in a short period of time, and burns down a large number of tobacco products and machinery and equipment. Cause huge economic losses. It is of great significance to study the law of fire occurrence and development of warehouse for the elimination of fire danger, the control and protection of loss of personnel and property in cigarette warehouse. In this paper, the fire and smoke movement and control of a three-dimensional warehouse of cigarette distribution in a city are numerically tested by using FDS fire simulation software. Firstly, the typical cigarettes in the warehouse were selected as samples for thermogravimetric analysis. The ignition temperature, combustion characteristic index and activation energy of the tobacco were measured by pyrolysis experiment, which provided the basis for the setting of numerical test parameters. Secondly, according to the physical size of the warehouse, the numerical model is established, and the fire scene of the warehouse under non-exhaust measures and natural and mechanical exhaust smoke is simulated and calculated by using the FDS large eddy simulation method. The spread law and temperature distribution of fire smoke in each scene were obtained, and the effects of natural smoke exhaust and mechanical exhaust smoke were compared. The results showed that the fire developed rapidly under natural conditions, and the parameters of temperature, CO concentration and visibility reached the limit of human danger tolerance, and the evacuation time of personnel was only 326 s. The effect of natural exhaust smoke is better, the visibility of fire field is improved and the content of CO is reduced by mechanical exhaust smoke. However, because of mechanical negative pressure, a large amount of fresh air is brought into the fire field, which aggravates the fire. According to the calculation method of smoke layer height and fire intensity in NFPA92B, the height of smoke layer can be controlled at 4.5 m, which is more reasonable than that of "Code of Fire Protection Design for High-rise buildings > Volume ventilation method". Finally, according to the principle of mathematical statistics, the position of smoke outlet, the quantity of smoke outlet, the wind speed of exhaust outlet and the amount of smoke are arranged and combined. The fire scene under combination condition is tested with FDS, and the influence of each factor on the effect of mechanical exhaust smoke is discussed. The results show that the "ceiling" is superior to the "sidewall", the increase of the quantity of exhaust smoke is better than that of the side wall, and the increase of the quantity of exhaust smoke is beneficial to the discharge of flue gas, but on the other hand, it will aggravate the fire. The excessive wind speed at the exhaust outlet results in smoke "suction phenomenon" and reduces the smoke exhaust efficiency. Therefore, the reasonable setting should be carried out according to the specific parameters of the building, and the ideal exhaust effect cannot be achieved even when the smoke outlet is too large or too small.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：X932;TS48

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