H2S Scavenging, Or Gas Sweetening in Industries
Petroleum production and refining, sewer and wastewater treatment and mining industries most commonly produce hydrogen sulfide. The gas is produced as a result of the microbial breakdown of organic materials in the absence of oxygen. Hydrogen Sulfide is produced in process units that remove sulfur from petroleum at oil refineries. In the petroleum refining process, it is formed when Sulfur is removed from petroleum. Hydrogen sulfide is transported to a processing unit where it is made into Sulfur or Sulfuric acid. It is also a by-product of paper pulping.
Unutilized, waste toxic hydrogen sulfide (H2S) gas eliminated into the environment from the H2S-releasing industries pose a great danger to the environment and animal life. H2S levels of 100 ppm and above are considered instantly hazardous to health and life; a level of 500 or above can cause immediate unconsciousness. Its hazardous level is lower than many other toxic gases. The toxicity of H2S can cause rapid death. Other effects of this gas include breathlessness, convulsions, coma, shock, leading to loss of consciousness, and eventually death.
Neutralizing or scavenging H2S
Hydrogen sulfide is a colorless, flammable gas with a pungent “rotten egg” or “rotten cabbage” odor at room temperature. The gas has a low odor threshold below 1 ppm, the minimum perceptible odor being 0.13 ppm. At 30 ppm level, its peculiar odor becomes recognizable. Its leakage and presence in the atmosphere can. thus, be easily detected. Leaked H2S gas can be neutralized by spraying water down the gas and adding sodium bicarbonate, but it is not feasible when a large volume of gas is thrown by the industries in the environment. It articulates the significance of scavenging H2S in the atmosphere.
This article aims to focus on the effective methods to control H2S odor with environment-friendly processes in the Pulp and Paper, Landfill Gas, Wastewater, and Biogas Disaster industries. The greater focus is on eliminating or scavenge this gas. H2S scavenging, or “gas sweetening,” is both a safety-critical and economic concern for ensuring trouble-free upstream and downstream operations. Solid or liquid scavengers are often used for this purpose. Triazines are the most commonly used scavengers.
Liquid scavenger Triazine
Triazines are a class of nitrogen-containing heterocycles existing in three isomeric forms. Triazine is primarily used for removing less than 100 ppm levels of H2S gas. It is applied using a contact tower to increasing H2S removal efficiency up to two times. Triazine application is also an ideal solution when the acid gas stream contains high levels of carbon dioxide apart from H2S. Triazines react favorably with the H2S without inhibition by the CO2.
Aqueous solutions of Amine scavenger
Amine Systems, organic compounds derived from ammonia, are one of the most commonly used regenerative H2S scavengers in the Oil & Gas industry. Amine treating plants remove H2S and CO2 from natural gas. The process is known as gas sweetening or acid gas removal. Amine gas treating or amine scrubbing uses Amine Solution, the aqueous solutions of various alkylamines to remove the gas. The solution dissolves and removes the gas from the refinery sour gases, producing a sweet gas.