Hydrogen sulfide gas- threat to environment

Hydrogen sulfide gas is colorless, poisonous and highly flammable with the characteristic of unpleasant stench of rotten eggs. As gas is heavier than air, it can easily accrue at the base of poorly ventilated spaces. Even though it smells very pungent at first, the sense of odor quickly deadens, thus individuals might be unaware of its presence, which can result in an untimely death at a worst case.

H2S gas in even low concentrations can be deadly. The gas is commonly found in facilities across the US and is caused by decay of organic materials in sewerage systems. The concentration level of H2S is reduced through thermal oxidation to sulfur dioxide and sulfur trioxide for possible usage in various plant processes. Many H2S application experts and industrial engineers have worked on oxidizer systems that are usually used for the treatment of C2S and H2S pollutants. Some of them have even devoted time in R&D to design and make regenerative thermal oxidizers (RTOs) that work. Many a times, RTO’s are used to enhance fuel efficiencies and lower NOX production.

Most of the steel and mining industries that were utilizing direct fired systems earlier have realized that regenerative thermal oxidizers are a better alternative to lower fuel costs. While designing the RTO systems many limiting factors have to be considered, such as leaks causing premature degradation and reducing the overall life of the machinery, blocking of hydrogen sulfide from any leakage in the regenerative thermal oxidizer system, or blocking of H2S which is emitted directly into the atmosphere that results in safety and health issues.

Considerations should be given regarding the design and metal thickness to get high outlet temperatures, higher than any possible condensation levels of by products. This will minimize any formation of H2S within the exhaust system. With higher temperature the exhaust can be used to produce high steam pressure that is utilized in steam operations or to provide the energy to run a turbine generating offset electriciaty.

Taking into account the potential of high operating pressures, considerations should be made regarding the thickness of material used and flow design. Many of these systems that might have been installed without taking into consideration about the high pressure might result in fractured seams emitting and exposing higher levels of hydrogen sulfide gas.

Most commonly, the stack or the inlet process tubing is equipped with sampling ports to enable periodic stack testing. In certain areas, the standard regulations might also require constant observation of SO2 emissions. The assessment of whether to use or not apply waste heat resurgence to RTO systems generally depends on the size of plant and utility expenses. Economic assessment to compare regenerative thermal oxidizers with or without waste heat resurgence should be considered. Environmental compliance is another issue.

About: – Additionally to OSHA standards, higher levels of H2S gas can breach environmental standards too, and leaks from the damaged pipelines and interceptors can result in further environmental threats.

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