Residual Sulfur Content Research Articles

Effect of sulfur removal on scale adhesion to PWA 1480

A commercial superalloy, PWA 1480, was annealed in hydrogen at 1000 ° to 1300 ° in order to remove a 10 ppmw sulfur impurity. This treatment was very successful above 1200 °, resulting in residual sulfur contents below 0.1 ppmw. The degree of scale adhesion in subse-quent 1100 ° cyclic oxidation tests was inversely related to residual sulfur content. Control of adhesion by desulfurization in the absence of reactive elements supports an adhesion mechanism based on oxide-metal bonding weakened by sulfur segregation. Attempts at sulfur purging and improving adhesion by repeated oxidation/polishing were not successful, in contrast to previous studies on NiCrAl.

Life cycle test of the NOXSO SO 2 and NO X flue gas treatment process: Process modeling

The NOXSO process uses a regenerable sorbent that removes SO 2 and NO X simultaneously from flue gas. The sorbent is a γ-alumina bead impregnated with sodium carbonate. The process was successfully tested at three different scales, equivalent to 0.017, 0.06, and 0.75 MW of flue gas generated from a coal-fired power plant. These test results were used to develop a mathematical model for the NOXSO fluid-bed adsorber (NOXSO Corp., Library, PA). The model predicts SO 2 and NO X removal efficiencies as a function of process conditions and sorbent properties. The spent sorbent was successfully regenerated with either hydrogen or natural gas. The presence of steam during regeneration helps to remove the residual sulfur, but the benefit of steam diminishes when its inlet concentration exceeds 25%. A design equation for a moving-bed regenerator using natural gas as the regenerant was developed from the 0.06 MW results. The adsorber model and the regenerator design equation were used together to determine the optimum residual sulfur content of the regenerated sorbent. It was concluded that the NOXSO LCTU (0.06 MW) would operate at the minimum cycle time of sorption and regeneration if the sulfur content of the regenerated sorbent was controlled at 0.8 wt%.

New catalysts for hydrotreating heavy distillates

Compares the activity of experimental-commercial batches of type GO catalysts with the activity of alumina-cobaltmolybdenum (ACM) and alumina-nickel-molybdenum silicate (ANMS) catalysts in the hydrodesulfurization of a 350-500C vacuum distillate from Romashkino crude containing 2% sulfur and 0.1% nitrogen by weight. Finds that the GO-115, GO-116, and GO-117 catalysts are promising materials for use in hydrotreating vacuum distillates because their activities are higher than those of the commercial ACM and ANMS catalysts. Notes that the GO catalysts will give effective processing of vacuum distillates down to residual sulfur contents below 0.3% by weight.

Effect of tensile stress on magnetic properties of oriented alloys with residual sulfur

Applied tensile stress was shown to reduce core loss in two types of experimetal (110) [001] oriented alloys with residual sulfur contents: continuously strip annealed 3% Si-Fe and iron-base alloys containing less than 2% Si textured by a primary recrystallization and normal grain growth mechanism. Application of 700 psi (5 MPa) to a 3% Si-Fe sample containing 0.018% S resulted in a decrease of Hc from 0.17 to 0.13 Oe and a decrease in 60 Hz, 15 kG core loss from 1.40 to 1.26 W/kg. Similar reductions in Hc and loss were obtained by the application of a ’’high stress’’ glass coating to the same sample. Reductions of Hc and core loss were observed in primary textured iron-base alloys with additions of 0.005% S. In highly textured material, loss decreases with tension included both reductions in hysteresis loss and domain loss.

Crosslinking of Starch Xanthate. V. Redox Grafting with Hydrogen Peroxide and Vinyl Monomers in Water

Soluble starch xanthate (SX) with a degree of substitution (D. S.) ranging from 0.09 to 0.56 reacted with vinyl monomers (acrolein, acrylamide, acrylic acid, acrylonitrile, methyl acrylate, or styrene) and hydrogen peroxide to form aqueous gels of crosslinked starch—poly(vinyl monomer) graft copolymer. The reaction progress was followed by viscometry while investigating the effects of varied D. S. and monomer and peroxide levels. Solids, precipitated from the gels by ethanol, were analyzed for nitrogen and sulfur and their compositions were calculated. The vinyl monomer polymerization ranged from 30 to 98% in the grafting. A residual sulfur content was equivalent to a remainder xanthate D. S. of 0.04 to 0.24. Infrared absorption spectra verified copolymer formations and indicated that homo-polymer formation was minimal.

Effect of annealing on the magnetic characteristics of iron-27% cobalt alloys

This paper describes the changes in magnetic properties of iron-27% cobalt alloys undergoing various annealing treatments. Two commercial heats (0.2 and 0.1 mm thick respectively) of similar compositions were studied. The anneals were carried out in both dry hydrogen and vacuum for a variety of temperatures up to 1200°C. After annealing, the magnetic properties were measured, the samples were examined metallographically, and the residual carbon and sulfur contents were determined. Results indicated that annealing in a dry hydrogen atmosphere was superior to heat treating under vacuum. The best annealing temperature to obtain good overall magnetic properties was 900°C. A slightly higher annealing temperature, 925°C, caused severe degradation in magnetic properties. It is suggested that the poorer properties are related to the presence of the alpha/gamma phase transformation at 925°C. Annealing at temperatures above 925°C caused improvement in some of the magnetic properties. Coercive force (H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> ) seemed most sensitive to annealing conditions, with a strong positive correlation being found between H <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">c</inf> and the carbon plus sulfur contents after annealing.