Detection of hazardous hydrogen sulfide (H2S) in petrochemical industries

The present paper describes an Electro-Optical Monitoring System developed for the real time in-situ remote sensing of H2S over large areas, at very low concentrations in air, well below the hazardous levels. Hydrogen Sulfide is a colorless, poisonous gas with the characteristic odor of rotten eggs, which poses an environmental, safety and health hazard. It is generated as a common by-product of many industrial manufacturing processes in: oil and gas exploration and production operations, desulfurization processes in petrochemical industry, sewage and various waste treatment plants, dyes and synthetic petroleum production plants, etc. The U.S Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for H2S is 10 ppm, which is 30 times lower than the "immediately dangerous to life and health" level of 300 ppm set by the U.S National Institute for Occupational Safety and Health (NIOSH). Despite a low human odor threshold for the gas in air(much less than 1ppm), H2S is considered to be an insidious poison because our sense of smell rapidly fatigues, and therefore, fails to provide a good warning of gas concentration. The paper describes the technology of open-path line-of-sight spectral analysis, uniquely developed to detect and distinguish between H2S and petrochemical aromatic gases usually found in the oil and gas industry. The H2S monitoring system analyzes the spectral "finger print" of the gas in the U.V spectral band and detects the poisonous gas at 5-10 ppm concentration in air over an open path of 50-100 m. The system offers warning and alarm signals set at the above low concentrations, thus providing protection to congested and crowded areas such as offshore and onshore oil and gas exploration and production facilities, where the gas unwanted release may have a fatal impact on the continuous operation of the facility. Several installations of the H2S monitoring system, field and laboratory test data as well as changing environmental condition influences (such as rain, snow and extreme temperatures) are discussed.