Scrubber oxygen

Basic oxygen furnaces oxygen blowing Fumes, smoke, CO, particulates (dust) Proper hooding (capturing of emissions and dilute CO), scrubbers, or electrostatic precipitator... 

Other methods have been developed for the removal of oxygen (particularly from flowing streams). These include the use of electrochemical or chemical (zinc) scrubbers, nitrogen-activated nebulizers, and chemical reduction (by addition of sodium sulfite or ascorbic acid). Alternately, it may be useful to employ voltam-... 

The intrinsic kinetics of the reactions taking place in the scrubber, i.e. the reaction of NO with the iron chelate forming an iron nitrosyl complex (eq. 1) and the undesired oxidation reaction of the iron chelate (xanpla (eq. 2) wae deteimined in dedicated stirred cell contactors. Typical process conditions were T = 25-55 °C [Fe"(EDTA) "] = 1-100 mol/m [NO] = 1-1000 ppm pH = 5-8 and an oxygen level ranging between 1 and 20 vol%. 

Two new technologies have reduced the cost of alkali fuel cells to the point where a European company markets taxis that use them. One is the use of CO2 scrubbers to purify the air supply, making it possible to use atmospheric O2 rather than purified oxygen. The other is the development of ultrathin films of platinum so that a tiny mass of this expensive metal can provide the catalytic surface area needed for efficient fuel-cell operation. 

Oxygen-containing molecules cannot be tolerated in the ammonia synthesis, primarily because they form iron oxide that blocks the active surface. First the CO2 is removed, through a scrubber, by reaction with a strong base. The remaining CO (and CO2) is then removed by the methanation reaction, converting the CO into methane and water. Finally the water is removed by, for example, molecular sieves. Methane does not present problems because it interacts weakly with the catalyst surface. The gas mixture (Tab. 8.6) is compressed to the roughly 200 bar needed for ammonia synthesis and admitted to the reactor. 

From the quench scrubber (B) the gas passes to an absorption column (C) in which the acrylonitrile is absorbed in water to produce a 3 wt per cent solution. The carbon dioxide, unreacted propylene, oxygen, nitrogen and unreacted hydrocarbons are not absorbed and are vented to atmosphere from the top of column (C). 

Aqueous, alkaline fuel cells, as used by NASA for supplemental power in spacecraft, are intolerant to C02 in the oxidant. The strongly alkaline electrolyte acts as an efficient scrubber for any C02, even down to the ppm level, but the resultant carbonate alters the performance unacceptably. This behavior was recognized as early as the mid 1960 s as a way to control space cabin C02 levels and recover and recycle the chemically bound oxygen. While these devices had been built and operated at bench scale before 1970, the first comprehensive analysis of their electrochemistry was put forth in a series of papers in 1974 [27]. The system comprises a bipolar array of fuel cells through whose cathode chamber COz-containing air is passed. The electrolyte, aqueous Cs2C03, is immobilized in a thin (0.25 0.75 mm) membrane. The electrodes are nickel-based fuel cell electrodes, designed to be hydrophobic with PTFE. 

It is practical to place a washing bottle or scrubber in the gas line just before the manifold. The aqueous solution in this bottle contains a reductant for traces of molecular oxygen and at the same time wets the gas which will minimize a concentrating effect on the sample by drying. A practical solution is 1 mM zinc acetate, 1 pM TMP (meso-tctra(/V-methyl-4-pyridyl)porphinc-tetra-tosylate), 100 mM Na2EDTA, 100 mM Tris-HCl buffer at pH 10. The porphyrin complexates the Zn2+ and forms a light-sensitive compound that can be excited by near UV light from an 18 watt TL-tube. 

Most of the terephthalic acid is produced with a catalyst system developed by Scientific Design. It was purchased by Amoco and Mitsui and is referred to as the Amoco Oxidation. The solvent is acetic acid. Compressed air is used as the source for oxygen. The catalyst dissolved in acetic acid and the two reactants are continuously fed into the reactor. The temperature is around 200 °C and the pressure is approximately 25 bar. The reaction is very exothermic (1280 klrnoT1, calculation from data in Stull et al [16] often a much higher, erroneous value is cited). This heat of reaction is removed by evaporation/condensation of acetic acid and can be used in the solvent distillation/purification part of the plant. A scrubber washes the vent gases... 

As it enters the instrument, the sample is diverted by the valve into a chemical scrubber that changes any ozone present to oxygen. This... 

In addition to the oxygen and carbon dioxide exchanged here, this area of the lung is necessarily exposed to other gases (carbon monoxide, nitrogen, etc.) to fluid droplets and to particulates in the ambient air. The air in the lung is essentially saturated with water vapor as it passes through the nasal scrubber to the bronchi, bronchioles, and ducts to the air sacs. 

The principal off-gases (H->0 and CO2) were routinely collected in tared scrubbers and quantitatively determined by weighing. However, as each run progressed, 1-cc. gas samples were also withdrawn from time to time and analyzed by gas chromatography. Particular attention was paid to oxygen (to check the performance of the Beckman analyzer) and to carbon monoxide. At... 

Oxygen scrubbers, "moisture" traps, and the like in the carrier gas lines are almost always worth the effort, but see below. 

---