SO2 gas

Owing to the cycHc nature of the TBRC operation, waste heat recovery from the off-gases is not practical and the SO2 content of the gas varies with the converter cycle. In order to supply a relatively uniform flow and strength SO2 gas to a sulfuric acid plant, a system has been installed at RonnskAr whereby the SO2 from fluctuating smelter gases is partially absorbed in water. During smelter gas intermption, SO2 is stripped with air and the concentrated gas deflvered to the acid plant. 

In general, plants using SO2 gas derived from metallic sulfides, spent acids, or gypsum anhydrite purify the gas stream before drying it by cold, ie, wet, gas purification. Various equipment combinations including humidification towers, reverse jet scmbbers, packed gas cooling towers, impingement tray columns and electrostatic precipitators are used to clean the gas. 

Plants that bum good quaUty elemental sulfur or H2S gas generally have no faciUties for purifying SO2. Before the advent of relatively pure Frasch or recovered sulfur, however, hot gas purification was frequentiy used in which the SO2 gas stream was passed through beds of granular soHds to filter out fine dust particles just prior to its entering the converter. 

SO2 gas is catalyticaHy oxidized to SO in a fixed bed reactor (converter) which operates adiabaticaHy in each catalyst pass. The heat of reaction raises the process gas temperature in the first pass to approximately 600°C (see Table 7). The temperature of hot gas exiting the first pass is then lowered to the desired second pass inlet temperature (430—450°C) by removing the heat of reaction in a steam superheater or second boiler. 

The curve in Figure 21 represents SO2 equiUbrium conversions vs temperature for the initial SO2 and O2 gas concentrations. Each initial SO2 gas concentration has its own characteristic equiUbrium curve. For a given gas composition, the adiabatic temperature rise lines can approach the equiUbrium curve but never cross it. The equiUbrium curve limits conversion in a single absorption plant to slightly over 98% using a conventional catalyst. The double absorption process removes this limitation by removing the SO from the gas stream, thereby altering the equiUbrium curve. 

The third major source of sulfur is pyrite and related sulfide minerals. The ore is roasted to secure SO2 gas which is then usually used directly for the manufacture of H2SO4 (p. 708). Again air pollution by vS02 gas emissions has been the subject of increasing legislation and control during the past three decades (p. 698). 

The vast majority of sulfur at any given time is in the lithosphere. The atmosphere, hydrosphere, and biosphere, on the other hand, are where most transfer of sulfur takes place. The role of the biosphere often involves reactions that result in the movement of sulfur from one reservoir to another. The burning of coal by humans (which oxidizes fossilized sulfur to SO2 gas) and the reduction of seawater sulfate by phytoplankton which can lead to the creation of another gas, dimethyl sulfide (CH3SCH3), are examples of such processes. 

Jupiter s moon lo on which a number of very active sulfur volcanoes have been discovered [64]. These volcanoes are powered by SO2 gas which forces the hquid sulfur from its underground deposits to the surface. 

C05-0112. A student proposes that SO2 gas contains a significant fraction of dimer with formula S2 O4. Describe a gas experiment that would verity or disprove this proposal. 

In contrast to the of hydrothermal solution for the vein, that of pyrite in hydrothermally altered rocks (Shimanto Shale) varies very widely, ranging from —5%o to - -15%o. Based on the microscopic observation, pyrite with low values less than 0%o is usually framboidal in form, suggesting that low 8 S was caused by bacterial reduction of seawater sulfate. There are two possible interpretations of high 8 " S values (+10%o to - -15%o). One is the reduction of seawater sulfate in a relatively closed system. The other one is a contribution of volcanic SO2 gas. As noted already, volcanic SO2 gas interacts with H2O to form H2SO4 and H2S. value of SO formed by... 

However, this mechanism seems to be unlikely, because hydrothermal solution originated from vapor phase does not contain appreciable amounts of base metals. The more likely process causing low pH is injection of volcanic SO2 gas. SO2 gas reacts with H2O to generate H+ by the reaction,... 

Series 8 in combination with earlier series was intended to provide data on the effects of total anion concentration. The results are internally consistant with the correlation, having a standard deviation of about 15% around the mean error. However the measured values of PSO2 were about 40% lower than the general correlation. An SO2 analyzer, rather than iodine titration, was used to determine SO2 gas concentration from the saturator. The analyzer was calibrated with dry SO2/N2 span gas. In later experiments it was shown that humid gas gives a lower analyzer response. With constant fraction neutralization increased anionic concentration increases PSO2 because pH decreases faster than effective bisulfite activity. 

Optimized steam requirement is relatively insensitive to solution pH. Solution capacity for SO2 absorption can reasonably vary from 0.1 to 0.4 g-moles S02/liter. The SO2 gas sensing electrode is an effective tool for vapor/liquid equilibrium at room temperature. 

A nonbiological reductant (8204 ) that has proven to be of immense value in converting uncomplexed and porphyrin-bound Fe(III) to the +2 oxidation state with the concomitant formation of two molecules of SO2 gas. Dithionite also reacts with heme-bound oxygen to produce deoxyhemoglobin, and treatment of intact red blood cells with dithionite can induce sickling in cells containing hemoglobin S. Dithionite also reduces NAD+ to NADH. 

Processes 4, 5 and 6 are all essentially one step oxidations of SO2 to SO3 and hence sulphuric acid. The first pair are modified versions of the traditional Contact and Chamber processes for sulphuric acid manufacture, with the principal change being in their ability to accept dilute SO2 gas streams as the feedstock. The use of Activated Carbon as an air oxidation catalyst has clearly received international attention, with success or failure depending to a large extent on subtle modifications in catalyst preparation and catalyst presentation to the reactant gases. Virtually every type of catalyst bed configuration has been explored. 

Oxides Vanadium monoxide VO, gray solid vanadium trioxide V2O3, black solid vanadium dioxide VO2, dark blue solid vanadium pentoxide V2O5, orange to red solid. The last is the most important oxide formed by the ignition in an of vanadium sulfide, 01 othei oxide, 01 vanadium used as a catalyzer, e.g., the reaction SO2 gas plus oxygen of air to form sulfur tnoxide. and the oxidation of naphthalene by air to form phthalie anhydride. 

Sulfur burns with a bluish flame to yield colorless SO2 gas. 

In the laboratory, the S0 gas concentration cell method using the solid electrolyte is considered to be a good technique for detecting the SO2 gas. However, in a practical utilization, the method is... 

The solid reference electrode technique is able to obtain almost the same results as the SO2 gas concentration cell method. The apparatus can be made more compact, simple and cheaper by using the solid reference electrode technique. The SO2 gas detection with solid reference electrode method is a promising technique for practical applications. 

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