Process simulation of handling H2S gas leak using water scrubber and common materials based on safety Programmable Logic Controllers

摘要

Hydrogen sulfide is a gas that highly toxic, colorless, and heavier than air that is heavy with the kind of 1,152 kg/m3. The type of weight resulted in H2S gas at the bottom make it easy wafted by the human senses. The presences of H2S gas, often encounter in the process of exploration and drilling for natural gas and petroleum refining. Therefore, it's necessary to build a system design of H2S gas leak solution in the oil and gas industry. Thus, the system can maintain the security of environment and human resources in the industrial area. The system is mixing the concept of individual well with water scrubber method to generate multiple securities. Hence, it should be getting intensive treatment with quick response, so as not to cause damage to the industry, due to its very existence threatened workers. H2S Safety Instrument System consists of H2S sensor and Programmable Logic Controllers as a safety function components. PLC is often chosen for safety instrument system as a logic solver. PLC also gives appropriate action for set-point which has been programmed before. There are 4 stages of set-point in the H2S SIS. First, when the H2S levels reached 10 ppm, an actuator is a strobe light. Second, when simply applied the actuator reaches 20 ppm, a strobe light and siren. Third, when it reached 25 ppm, the actuator is vacuum compressor that integrated with the system of purification of water scrubber. Fourth, shutdown system for inactive throughout the process at this stage, the plant is used as a safety system double layer when the H2S safety instrument system is not functioning. The result of this research is decrease of Probability of Failure on Demand value from 7.997 E???01 to 1.17 E???03 and increase Safety Integrity Level from 1 to 3.