Low-oxygen system

A low-oxygen system is ideal for many flavouring products It reduces the risk of powder explosions and/or of oxidation of sensitive products, and the release of exhaust air to the environment is very small compared to the air volume needed in the drying process. The reduced airstream, leaving the plant, can be deodorized or detoxicated by incineration. 

Rail cars, tank trucks, and some reactors and storage tanks were cleaned manually by personnel who entered the vessel fatalities occurred from unexpected or undetected low oxygen content or toxicity. An inherently safer system is a rotating pressurized water spray head that does the cleaning without vessel entry. 

Another problem in high-temperature corrosion can be the effect of the formation of volatile metallic halides which can, in turn, disrupt the integrity of a protective surface oxide. Figure 7.73 shows that in the Ti-O-Cl system at very low oxygen potentials, volatile TiClj can be formed directly from TiO and Ti, whereas from Fig. 7.74 it is clear that in the system U-O-Cl at 450°C the volatile chloride cannot be formed directly from the oxides. 

Mixed conditioning has also been used. In this, one part of the circuit (usually the low-pressure system) is dosed conventionally, e.g. with hydrazine/ammonia, whilst the high-pressure system is subjected to oxygenated conditions. 

All boiler system waterside surfaces need the protection given by the smooth, hard, tenaciously adherent magnetite layer. The magnetite film sometimes may sparkle because of the precipitation of fine magnetite crystals onto the metal-oxide surface. Magnetite film formation is best achieved under stable, low-oxygen content operating conditions at a pH level of 10.5 to 11.5 (possibly up to 12.0). 

The vapor pressures of the monoxides in the niobium-oxygen and tantalum-oxygen systems are much higher as compared to those of the pure metals, even at oxygen concentrations as low as 0.1 at-%. The R values are, therefore, very large. This implies that these metals are very amenable to sacrificial deoxidation. 

Peck DH, Miller M, and Hilpert K. Phase diagram study in the Ca0-Cr203-La203 system in air and under low oxygen partial pressure. Solid State Ionics 1999 123,47-57. 

Aerobic treatment, develop low energy, low oxygen input systems. Develop systems which prevent odour regeneration after treatment to allow storage for optimum use by crops. 

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