Fire and explosion hazards during filling/emptying of tanks

Loading and unloading operations produce 8% of all accidents which occur in process plants and in the transportation of hazardous materials. A survey of 738 accidents was performed, allowing the identification of the accident type distribution and of their cause. Some considerations on flammable mixtures are also presented, and the procedures to avoid these mixtures occurring when filling or emptying a tank are briefly discussed.     

Assessment of explosion risks caused by cone discharges when filling silos and containers with pellets

It is well known that during the filling of silos and containers with bulk material, so-called cone discharges can occur because of electrostatic charges. Whether or not cone discharges occur at all depends on whether the breakdown field strength of air under atmospheric conditions of 3 MV/m is reached at the silo and container inner wall. This in turn depends on the charge to mass ratio of the bulk, the bulk resistivity, the bulk density, the relative permittivity of the bulk material, the silo or container diameter and the filling rate. If cone discharges can't be avoided, the energy of cone discharges can be estimated according to the equation given in the relevant guidelines TRGS 727 (2016) and IEC/TS 60079-32-1 (2013). Therefore, the coarse fraction must be considered. As soon as the energy of the cone discharge is greater than or equal to the minimum ignition energy of the bulk material introduced, there is a risk of dust explosion. Here the fine fraction of the bulk material is relevant.The investigations described are a practical example how computer models can be used to assess the occurrence of cone discharges. It is calculated for which silo and container diameters and filling rates the critical field strength of 3 MV/m is reached. In these calculations the charge relaxation during pneumatic filling with bulk material is taken into account. The results of the computational modelling together with operational boundary conditions serve as a decision basis whether exclusion of incendive ignition sources is an adequate safety measure or whether further explosion protection measures must be considered. Finally, a brief overview of other possible explosion protection measures is given.     

Fire accident investigation of an explosion caused by static electricity in a propylene plant

This study investigated a 2010 fire and explosion that occurred at a polypropylene (PP) and copper-clad laminate high-tech plant in Taiwan. Liquid acetone leakage caused the fire and explosion. One person was killed and five were injured; property damage was estimated at US$20 million. In contrast to conventional plants, high-tech plants have sophisticated instrumentation, highly complex pipelines, and confined spaces. In addition, the floor area in a high-tech plant is large and frequently contains a channel through the ground floor to the second or third floor. This channel design enables the fire compartment to be destroyed. Therefore, the system cannot confine the fire to a specific area, thus hindering fire-relief operations. In this study, the original fire outbreak occurred in the PP processing area on the ground floor. The acetone storage tank was located on the third floor. The investigation conducted at the fire site of the situations of the burning (bursting) loss determined that the acetone liquid leaked and dripped from floor cracks and tunnel oven to the PP processing area. Because the PP manufacturing process rapidly generates static electricity, the flammable liquids made contact with the source of ignition, which caused the explosion and fire. Various procedures, such as those involving the operating environment of production, packaging, and processing in a high-tech plant, are likely to produce static electricity in a workplace. Improved electrostatic management can prevent the loss of property and lives, liquid acetone leakage, and loss of equipment caused by static electricity fire.     

静电喷漆作业的防火防爆

静电喷漆工艺应用普及很快,但其生产过程的火灾危险性属甲类。其火灾危险主要在于使用的漆料或有机溶剂,喷漆作业中存在电火花、静电火花、高温热表面、自然发热等引火源。为防止火灾爆炸发生,要注重防火防爆安全管理和强化必要的安全技术措施。     

粉尘爆炸特征和预防措施探讨

随着现代工业的发展,粉末技术得到了广泛应用,使得粉末产物日益增多.许多粉体加工企业对粉体的相关危害知识没有深刻的认识,这些物质在安全生产、储存、运输和应用过程中,安全管理比较混乱,没有做到很好的防护,缺乏必要的防火防爆设施,再加上操作人员思想上的麻痹大意.粉尘爆炸的危险性大大增加,粉尘爆炸的事故也频繁发生.粉尘爆炸具有很强的破坏力,往往造成重大人员伤亡和严重损失,已经越发成为工业安全不可忽视的重要问题.本文从粉尘爆炸的基本特征出发,论述了粉尘爆炸的机理、条件、特点.根据粉尘爆炸需要的条件,从可燃物、助燃物和点火源三个方面,提出了在实际生产中,预防粉尘爆炸的一些具体措施,以期指导安全生产.     

中药制药过程的职业危害与控制措施

建国以来,我国中药制药生产技术发生了巨大的变化,经历了上个世纪六七十年代的中药生产“机械化”、八十年代的中药制药“工业化”和九十年代提出的以“现代化”为目标的三个阶段。目前中药行业正处于传统工艺与现代技术相结合的新发展阶段,制药工艺复杂,制药工序中潜在的职业危害因素较多。本文通过分析常见的中药制药过程,找出其中可能产生职业危害的工序、环节,并提出了相应的控制措施,以期达到降低或消除制药行业作业职业危害的目的。     

三氯化氮排放槽爆炸事故原因分析及预防处理措施

对某化工厂液氯包装工序三氯化氮排放槽爆炸事故进行了分析 ,提出了预防及处理措施     

Electrostatic ignition hazards in insulating or dissipative tubes and hoses for pneumatic transfer of powders—Measurements and model calculations

When transferring powder through pipes or hoses made from insulating material, propagating brush discharges cannot be excluded. To calculate the limit value of the resistivity of the insulating material, below which no propagating brush discharges will occur, the charging current due to the powder transfer must be known. This charging current has been determined experimentally. Based on analytical calculations and computer models limit values for the resistivity of the hose material are derived from these experiments.