Hydrogen sulfide concentration

Hydrogen sulfide concentrates in refinery off gases. Before being used as fuel gas, the gas undergoes an amine (MEA, DEA, etc.) washing step in order to extract the H2S. 

An Alka-Seltzer tablet gives off carbon dioxide when dissolved in aqueous solution. The gas is used to drive hydrogen sulfide out of drilling fluid samples. The H S then reacts with lead acetate paper in the bottle cap. The degree of discoloration is related to hydrogen sulfide concentrations. 

A prestressed roller bearing is used to detect the presence of hydrogen sulfide, but more specifically it is used to test for hydrogen embrittlement tendency of the drilling fluid. When introduced to the environment, the bearing has sufficient residual stresses to cause failure if sufficient hydrogen sulfide concentration is present. 

Respiratory distress was noted in 2 workers exposed to >40 ppm hydrogen sulfide for <25 minutes (Spolyar 1951). Male volunteers were exposed to hydrogen sulfide concentrations up to 5 ppm for more than 16 minutes after graded exercise that was performed to exhaustion (Bhambhani and Singh 1991). 

Alterations in blood heme metabolism have been proposed as a possible indicator of the biological effects of hydrogen sulfide (Jappinen and Tenhunen 1990), but this does not relate to the mechanism of toxicity in humans. The activities of the enzymes of heme synthesis, i.e., delta-aminolevulinic acid synthase (ALA-S) and heme synthase (Haem-S), were examined in 21 cases of acute hydrogen sulfide toxicity in Finnish pulp mill and oil refinery workers. Subjects were exposed to hydrogen sulfide for periods ranging from approximately 1 minute to up to 3.5 hours. Hydrogen sulfide concentrations were considered to be in the range of 20-200 ppm. Several subjects lost consciousness for up to 3 minutes. 

Kimura K, Hasegawa M, Matsubara K, et al. 1994. A fatal disaster case based on exposure to hydrogen sulfide - an estimation of the hydrogen sulfide concentration at the scene. Forensic Sci Int 66 111-116. 

Leahey DM, Schroeder MB. 1986. Predictions of maximum ground-level hydrogen sulfide concentrations resulting from two sour gas well blowouts. J Air Pollut Control Assoc 36 1147-1149. 

The TLV-TWA for hydrogen sulfide gas is 10 ppm. Hydrogen sulfide gas is stored in a tank at 100 psig and 80°F. Estimate the diameter of a hole in the tank leading to a local hydrogen sulfide concentration equal to the TLV. The local ventilation rate is 2000 ft3/min and is deemed average. The ambient pressure is 1 atm. 

The release to the atmosphere is strongly dependent on the pH because only the molecular form and not the dissociated forms can be emitted, e.g., at a pH about 7, an equal amount of H2S and HS- exists in the water phase. Increase of the pH will, therefore, at equilibrium conditions and at a constant total sulfide concentration, reduce the hydrogen sulfide concentration in the overlying sewer atmosphere (Figure 4.1). Therefore, when applying Henry s law [Equation (4.8)], only the nondissociated molecular form, H2S, should be taken into account. 

Although the hydrogen sulfide concentration in the sewer atmosphere or the... 

TABLE 4.6. Levels of Total Hydrogen Sulfide Concentration in Wastewater of a Sewer System and Associated Problems in Terms of Malodors, Health and Corrosion. 

The volumetric rate of hydrogen sulfide formation in each of the two pipes multiplied with the residence time gives the hydrogen sulfide concentration in the wastewater at the outlet ... 

Ventilation of sewers may not only reduce the hydrogen sulfide concentration in the sewer atmosphere but also the moisture that is a fundamental requirement for establishment of microbial activity on the sewer walls. It is important that the ventilation be well controlled otherwise, odorous problems in the vicinity of the sewer network may occur. In some cases, operational procedures like treatment of the vented air, e.g., by wet oxidation, by chemical scrubbing or by passing a biofilter, may need to be considered. 

The simulations depicted in Figure 8.8 also show that arather low hydrogen sulfide concentration is predicted in the gravity sewer. Only minor problems related to hydrogen sulfide production may therefore arise. Until now, the WATS model did not include sulfide release to the sewer atmosphere, sulfide oxidation or sulfide precipitation that may further reduce the concentrations shown. The predicted sulfide concentrations are, therefore, maximum levels. In case a natural capacity of iron salts in the wastewater to precipitate sulfide is inadequate, the sulfide concentrations are considered at a level that can be relatively easily controlled. 

FIGURE 8.8. Model simulation of variations in the DO concentration, the OUR and the hydrogen sulfide concentration. The DO concentration of the wastewater inflow along the sewer line is estimated to be 2 g02 m-3. 

Carbon tetrachloride slowly reacts with hydrogen sulfide in aqueous solution yielding carbon dioxide via the intermediate carbon disulfide. However, in the presence of two micaceous minerals (biotite and vermiculite) and amorphous silica, the rate transformation increases. At 25 °C and a hydrogen sulfide concentration of 0.001 M, the half-lives of carbon tetrachloride were calculated to be 2,600, 160, and 50 d for the silica, vermiculite, and biotite studies, respectively. In all three studies, the major transformation pathway is the formation of carbon disulfide. This compound is... 

Although there is no ASTM specification for gasoline mercaptan or hydrogen sulfide levels, a copper corrosion specification does exist. Since mercaptans and hydrogen sulfide attack copper and copper-containing alloys such as brass and bronze, it is important to minimize fuel mercaptans and hydrogen sulfide concentrations. 

Alkanolamines. Gas sweetening, ie, removal of hydrogen sulfide and carbon dioxide, using alkanolamines was patented in 1930. Several amine solvents are available as of the mid-1990s. The most widely used are monoethanolamine [141-43-5], diethanolamine [111-42-2], diglycolamine [929-06-6], and methyldiethanolamine [105-59-9]. Amine processes are generally applicable when hydrogen sulfide concentration in the feed gas is relatively low (eg,... 

The reservoir gas in a wet gas reservoir has a specific gravity of 1.295, a hydrogen sulfide concentration of 20.9 mole percent, and a carbon dioxide concentration of 44.7 mole percent. Determine a value of z-factor for use at reservoir conditions of 5720 psig and 268°F. 

The phase equilibria data for binary guest mixtures are listed under the lighter component. For example, under the heading of binary guest mixtures of methane will be found data for methane + ethane, methane + propane, methane + isobutane, methane + n-butane, methane + nitrogen, methane + carbon dioxide, and methane + hydrogen sulfide. Concentrations are in mole percent or mole fraction in the gas phase, unless otherwise indicated. 

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