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煤炭仍然代表在美国，中国和欧洲的煤化工产业的发展，丰富的能源资源，焦炉煤气（COG）被广泛应用于流程工业和电力生产。作为广泛报道，煤可被定义为一个复杂的沉积岩中，已经过与沉积环境和成岩历史连接的化学变化更高的来自植物的有机材料的非均相混合物。由于煤是不均匀的物质，它的特点是在它的性能和组成的巨大差异。最常见的煤的分类是由等级，即，煤化度有机植物沉积物已经在从泥炭其变态达到接近石墨状材料[1]。如众所周知，焦炉气是一种副产品煤干馏焦炭中的哪一个共同产生在干馏过程[2]，它清楚地反映了母体煤的特性。通常情况下，1.25-1.65煤的叔产生1吨焦炭，在与大约COG（6-8 GJ /吨焦炭）的300-360立方米连接，而产生的焦炉煤气的目前20％-40％，通常用作燃料在实际焦炉[3]。作为参考，表1示出的能量平衡为典型的焦炭制造工厂以及不同的原材料和产物分布
Coal still represents an abundant energy resource in USA, China and Europe and with the development of the coal chemical industry, coke oven gas (COG) is widely used in the process industry and power production. As widely reported, coal can be defined as a complex sedimentary rock, a heterogeneous mixture of higher-plant-derived organic materials which have undergone chemical changes in connection with the depositional environment and the diagenetic history. Since coal is not a homogenous substance, it is characterized by wide variations in its properties and compositions. The most common coal classification is by rank, i.e., the degree of coalification that organic plant sediment has reached in its metamorphosis from peat to near-graphite-like material [1]. As well known, coke oven gas is a by-product of coal carbonization to coke which is co-generated during the dry distillation process [2] and it clearly reflects the characteristics of parent coal. Typically, 1.25–1.65 t of coal produces 1 t of coke, in connection with approximately 300–360 m3 of COG (6–8 GJ/t coke), while currently 20%–40% of produced COG is normally utilized as fuel in the actual coke oven [3]. As an indication, Table 1 shows the energy balance for a typical coke-making plant along with different raw materials and product distribution [4]. Notwithstanding the enforcement of ATEX EU Directives (94/9/EC of 23 March 1994) and safety management system application, explosions in the coal sector still claim lives and cause huge economic losses. Even a consolidated activity like coke dry distillation allows the opportunity of preventing explosion risk connected to fugitive emissions of coke oven gas. Considering accidental releases under semi-confined conditions, a simplified mathematical approach to the maximum allowed gaseous build-up is developed on the basis of the intrinsic hazards of the released compound. The results will help identifying and assessing low rate release consequences therefore to set-up appropriate prevention and control measures. The developed methodology was tested at the real-scale and validated by numerical computational fluid dynamics (CFD) simulations showing the effectiveness of the methodology to evaluate and mitigate the risk connected to confined hazardous releases.
The key principle of an inherently safer design approach is to reduce hazards associated with materials used and operations, instead of controlling them with add-on protective barriers. This approach is recently applied also in emerging fuel/energy technologies (e.g., [5,6]). Notwithstanding improvement in the design and process management, the steel industry is the largest energy consuming industrial sector worldwide, with an expected steel production raise during the next few decades [7], so that COG will continue to be produced in large quantities in the future, as coke cannot be substituted in the blast furnace. Therefore, despite the continuous move towards inherently safe materials, accidental releases of dangerous toxic/flammable gases still represent a serious concern in the coal processing industries. Even if the potential development of explosive atmospheres is generally typical of industries classified at major hazard, it is also possible in other industries where flammable materials are handling and requires quantitative methodologies based on a probabilistic risk assessment starting from a detailed knowledge of the analyzed system [8]. The composition of COG after leaving the coke oven is rather complex: after the cooling stage to separate tar and the scrubbing processes eliminating NH3, H2S and benzene, toluene, xylenes (BTX), the gas contains H2 (55%–60%), CH4 (23%–27%), CO (5%–8%), CO2 (<2%) with other hydrocarbons (HC) in small proportions [9].