Hydrogen Sulfide Contamination Research Articles

Transient Analysis of Hydrogen Sulfide Contamination on the Performance of a PEM Fuel Cell

A transient kinetic model for the anode catalyst layer of a proton exchange membrane (PEM) fuel cell is proposed to describe the performance loss introduced by the hydrogen sulfide contaminant. Reaction rates are considered as functions of cell current density and contamination level and are estimated based on the available experimental data. It is found that at a constant cell current density the surface coverage of Pt–S increases faster with time and the anode overpotential rises sharply when increasing the contamination level from , leading to a faster and more severe cell performance degradation. At a constant contamination level, the surface coverage of Pt–S also increases faster with time when increasing the cell current density from , resulting in faster and more severe cell performance degradation. Simulation shows that the contaminant surface coverage at steady state is governed by current density. With the same contaminant concentration, to maintain a higher current density output, a significant decrease of steady-state contaminant coverage is required, while at a lower current density, steady-state contaminants coverage increases significantly.

Hydrographic survey in the dying Aral Sea

We report the results of a hydrographic survey conducted in November, 2002, in the Uzbekistan part of the western basin of the dying Aral Sea. There were very few hydrographic measurements in this region since at least early 1990s. The salinity in the western deep basin of the Aral Sea varied from about 82 psu at the surface to over 94 psu at the bottom. The absolute lake surface level was about 30.5 m. Hence, the observed salinity values were much higher, and the level much lower, than expected according to earlier predictions. The density in the western basin exhibited an extremely strong stratification of ∼11 kg/m3 per ∼20 m in the bottom layer. The picnocline was accompanied by a temperature inversion whose magnitude was ∼4°C. The observed density stratification effectively isolating the lower part of the water column from surface exchanges may be responsible for the increase of summer SSTs and evaporation rates reported in previous studies. We discovered the hydrogen sulphide contamination in the bottom layer whose upper limit was at the depth of approximately 22 m. Estimates suggest that the western basin salinization occurs not only because of the local evaporation, but also because of the assimilation of the saltier eastern basin water in the course of the interbasin exchange through the connecting channel. The satellite imagery analysis, in particular the Maximum Cross‐Correlation method, suggests that the circulation pattern in the Aral Sea in its present limits is cyclonic under the eastern winds that are predominant in the region throughout the year.

Automatic microprocessor system for determining corrosivity of technological media

Corrosion damage, which attains roughly 4% of the national product in all industrially developed countries, can be reduced substantially (at least 25%) by using various corrosion-proofing media and methods and routine corrosion monitoring. In particular, in order to hold corrosivity of technological media in petroleum, refinery, petrochemical, and chemical industries at the admissible level, inhibitor proportioning or cathodic protection current strength should follow variation in corrosivity which depends on the ratio of the phases in the product being transported, rate and pattern of product flow, content of oxygen, hydrogen sulfide, salts, and various contaminants, and so on. The basic method for determining corrosivity of aqueous and water-oil media is massometric. Blank samples are inserted into pipelines, storage tanks, apparatuses, etc., and the metal corrosion rate is assessed from the weight loss over a fixed time. But because of its laboriousness, lengthly testing time, and lack of scope for automation of the measuring process, massometric method is unusable for continuous routine corrosion monitoring. Measurement of polarization resistance is the most convenient method for routine monitoring. The method is discussed.

Geologic Aspects of Reservoir Souring--Brent Group Sandstones, North Sea: The Use of Conventional and Laser Extraction Techniques in Sulfur Isotope Studies of Authigenic Pyrite

The Middle Jurassic Brent Group sandstones are prolific oil reservoirs in the North Sea. Recently, a number of Brent wells have experienced increased levels of hydrogen sulfide contamination during production. A study involving the characterization of all iron-bearing minerals to understand the controls of mineralogy on the nature and timing of souring has been undertaken. The potential of iron minerals to scavenge hydrogen sulfide and hence delay/inhibit souring by precipitation of pyrite has been investigated by determining its distribution, quantity, and origin. Authigenic pyrite occurs as disseminated (framboidal, cubic, and octahedral) crystals and as a pore-filling cement. The pyrite has formed throughout the diagenetic history of the sandstones. however, most of the pyrite is considered to be a late cement formed during burial diagenesis. Conventional separation and sulfur isotope analysis of the authigenic pyrite was conducted on samples from oil- and water-bearing sequences to give a bulk signature for all pyrite present. Subsequently, laser sulfur isotope analysis was used to characterize the signature and origin of the different pyrite morphologies present. The enhanced level of sulfur isotope signature characterization can be used to improve the knowledge of the origin and timing of the different pyrite morphologies. This allows closer reconciliationmore » of the isotopic data to the diagenetic history of the Brent sandstones. Calculations have been made using the known quantities of iron in these minerals and the hydrogen sulfide concentrations present. This indicates the effect of sulfide precipitation on the hydrogen sulfide levels remaining in the reservoir.« less

A continuously regenerated greensand filter for H2S removal from individual water supplies

Abstract Hydrogen sulfide contamination of individual home water supply is a frequent problem in areas with aquifiers in sedimentary rock. Commercially available systems for removal of H2S are often quite expensive. This paper describes the new design of a low cost oxidizing filter that has been successfully used to remove in excess of 99% of H2S (at concentrations of 1 to 5 mg/1) from the authors home water supply for over four years. The unit used continuously regenerated, parallel flow, greensand filters; the design is such that the system may be constructed from locally available materials with a total cost of 25% of existing commercial units.

The Effects of Hydrogen Sulphide Contamination on Silver and Silver Alloy Contact characteristics

The Effects of Hydrogen Sulphide Contamination on Silver and Silver Alloy Contact characteristics