| dc.description.abstract |
The LED industry has been developing rapidly and vigorously all over the world. In Taiwan, as the yearly revenue of the LED industry lies within the world’s top three rankings, it has been considered as one of the industries with the highest potential over recent years. However, highly reactive substances with hazardous characteristics such as flammable, explosive and toxic are being used in such industry, highly threatening the safety and health of related personnel as well as property.
NH3 gas ranks as top one in terms of the amount being used during the LED epitaxial wafer production process. Since NH3 is characterized as flammable, irritant and polluting to the water environment, hazards from NH3 during the production process must be evaluated. Frequently seen process assessment methods are the what-if analysis, checklist analysis, hazard and operability study (HAZOP), failure mode and effect analysis and fault tree analysis, and each method is applied under specific conditions. As the study of this article focuses on the manufacturing plant during a production process, the HAZOP method is used to carry out the analysis, with each process node being analyzed based on process deviation factors in order to identify potential hazardous factors and possible risks. Effective control measures can then be designed and applied, and safety precautions for the NH3 supply system can be discussed in depth and advices can be proposed to prevent any accident from the gas system causing loss of property and business interruption.
The NH3 supply measures can be divided into three systems - the Iso tank system, BSGS and purifier, and the analysis is carried out based on hazards. 155 types of process deviation factors are analyzed from nodes, overall with 32 items over risk level three, among which the main possible hazard/consequence is fire and explosion, followed by gas leak which causes human inhalation injury. Protective systems against fire and explosion such as the fire sprinkler systems, water mist systems and fire compartments are evidently insufficient, to which corrective and preventive actions should be taken as priority. | en_US |