Risk Assessment of The Above Ground Natural Gas Station – A Case Study for a Natural Gas Station in Taiwan

• Main Authors: WU, JIA-WUN, 吳家汶
• Other Authors: HSIEH, MING-HONG
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/3n8f8t

碩士 === 中臺科技大學 === 環境與安全衛生工程系碩士班 === 106 === Due to the characteristics of nature gas (NG) is lighter than the air, most of the natural gas stations are set up on the ground to avoid explosion hazard from the accumulation of leakage. To make their outlook more environmental friendly, they are usually covered with horticulture landscaping on the outside. Most of the studies of hazard analysis of natural gas stations were focused on the underground stations. As such, this research would explore the risk of NG stations on the ground by collecting and studying the process safety information (PSI) of NG station, processing a series steps, such as onsite survey, preliminary hazard analysis, and Hazard and Operability (HazOp) analysis and so on, to identify the hazard and to assess the risk of NG stations. Our study shows there are several major shortcomings found from the above ground NG stations which are: 1, P&ID of the gas suppling process of the NG station is not available; 2, emergency shut down mechanism of the electric-pressure control device in gas inlet is not appropriated; 3, natural gas, which is flammable and explosive, is used as instrument gas; 4, auto-shutdown is not functioning during gas leak; 5, there is no gas discharge system in the filtration system; 6, no auto-shutdown device in the backup piping system; 7, the release system for over-pressure is not installed; 8, the number of gas leakage detectors and infrared flame (IRL) detectors are insufficient settings; 9, no fire/explosion isolation zoning in place; 10, no sprinkler system installed; 11, some remote-sensing devices are installed in the RTU (Remote Telemetry Unit); 12, no emergency ventilation with interlinkage. Suggestions for improvement has been compiled based on the above analysis results. Originated from the above-mentioned risk analysis results, the items to improve for safety enhancement with priority are suggested: 1, to employ the air to replace NG for the gas used as instrument gas and the mode of operation set on the Air to open (AO) ; 2, to have the differential pressure gauge installed on the filtration system, along with having the gas discharge/ventilation measures added; 3, to remove the detection component especially the pressure transmitter in the RTU; 4, to have the auto-shutdown for over pressure in the backup piping, and to link with the auto-shutdown in the main pipe lines; 5, to add emergency discharge/ventilation measures for leaking, fire (flame), and to interlink with auto-startup and auto-shutdown system. Results of this study has been highly recognized by industries and has been accepted for new station construction. We are looking forward to having these research outputs incorporated in the safety design guideline of the NG station to further upgrade its safety protection and risk management so that the potential risk of the NG station can be further reduced and to prevent accident from happening.