# Behavior Characteristics of Hazardous Gas and Scattering Coal Dust in Coal Storage Sheds
## 1 Introduction  
Recently, governments worldwide have been pushing for energy transformation to cope with severe climate change. Therefore, fossil-fuel use is decreasing, and eco-friendly energy use is increasing [1]. According to the 2019 statistics released by the US Energy Information Administration, South Korea ranked fifth among liquefied natural gas, coal, and petroleum fuel importers in the world, and ninth in energy consumption. As such, Korea is highly dependent on fossil fuels [2]. Changing the fossil-fuel-oriented energy industry in a short time is expensive. Therefore, actively solving the environmental problems of existing coal-fired power plants, while achieving energy conversion, is essential. Power companies and governments are expanding investment in environmental facilities to respond to environmental problems caused by coal-fired power plants. A typical example is a coal storage shed. In the past, coal was stored outdoors. However, a large volume of coal dust occurs caused by fine dust, generating civil complaints in the surrounding areas [3]. By storing coal indoors, the scattering of coal dust can be prevented due to airflow. The shapes of indoor coal storage areas are divided into shed, dome, and silo types. The shed-type indoor coal storage is a warehouse-type storage yard, with atriangular iron roof. Compared with other indoor coal storage methods, it has economic advantages and enables the efficient storage and management of coal [4]. However, there are many problems due to the characteristics of coal in an indoor coal yard built to reduce the scattering of coal dust [5]. The first problem is the spontaneous combustion of coal. Coal, the primary energy source for thermal power plants, absorbs oxygen from the air and slowly generates heat. Oxidation and exothermic reactions are accelerated, heating the inside of the coal pile, causing spontaneous ignition [6]. When coal spontaneously ignites in an indoor coal yard, harmful gases accumulate in the indoor silo, due to insufficient ventilation. Moreover, the concentration of carbon monoxide in the poisonous gases generated during spontaneous ignition increases rapidly. Carbon monoxide is 250 times stronger in binding with hemoglobin than oxygen in the blood, causing intermittent headaches, irritability, and mental confusion, and is fatal in high concentrations with a long exposure time [7]. The appropriate legal standard concentration of carbon monoxide in hazardous gas-generating facilities is managed at 30 ppm [8]. If this is exceeded, a worker cannot safely work. However, the spontaneous ignition of the indoor coal yard increases the carbon monoxide concentration by more than 30 ppm, making the field workers' work environment more dangerous. Second, coal dust is a problem that occurs when coal falls inside a coal storage shed. Coal arrives at the harbor on a coal carrier and is transported to an indoor coal yard using a ship unloader and conveyor belt. Coal is transported by the conveyor belt inside the indoor coal yard, and is stored by dropping it into each cell of the coal yard using a telescopic chute, installed about 11 m above the coal yard. During this time, a large amount of coal dust is scattered and a size of about 50 \(\upmu\)m or less is generated. It is difficult for indoor workers to access the site until the dust settles, and it is impossible to take emergency measures when spontaneous ignition occurs. Thus, the indoor coal storage facility, built to prevent dust scattering generated during outdoor coal storage, causes a massive problem in internal fieldwork, due to the characteristics of the internal coal. Many studies have been conducted to reduce hazardous gases and dust scattering in coal storage sheds. Typically, studies have been conducted to suppress the generation of harmful gases and coal dust in advance. Regarding the prevention of the natural ignition of coal, [PERSON] et al. [9] analyzed the effect of natural coal ignition on the surface of coal piles. The self-ignition barrier must be applied from the bottom.