Vaporized sulfur

In a vacuum, uncoated molybdenum metal has an unlimited life at high temperatures. This is also tme under the vacuum-like conditions of outer space. Pure hydrogen, argon, and hehum atmospheres are completely inert to molybdenum at all temperatures, whereas water vapor, sulfur dioxide, and nitrous and nitric oxides have an oxidizing action at elevated temperatures. Molybdenum is relatively inert to carbon dioxide, ammonia, and nitrogen atmospheres up to about 1100°C a superficial nitride film may be formed at higher temperatures in the latter two gases. Hydrocarbons and carbon monoxide may carburize molybdenum at temperatures above 1100°C. 

The hydrocarbon gas feedstock and Hquid sulfur are separately preheated in an externally fired tubular heater. When the gas reaches 480—650°C, it joins the vaporized sulfur. A special venturi nozzle can be used for mixing the two streams (81). The mixed stream flows through a radiantly-heated pipe cod, where some reaction takes place, before entering an adiabatic catalytic reactor. In the adiabatic reactor, the reaction goes to over 90% completion at a temperature of 580—635°C and a pressure of approximately 250—500 kPa (2.5—5.0 atm). Heater tubes are constmcted from high alloy stainless steel and reportedly must be replaced every 2—3 years (79,82—84). Furnaces are generally fired with natural gas or refinery gas, and heat transfer to the tube coil occurs primarily by radiation with no direct contact of the flames on the tubes. Design of the furnace is critical to achieve uniform heat around the tubes to avoid rapid corrosion at "hot spots."... 

Since 1960 mass spectrometry has always been an important tool to investigate the molecular composition of sulfur vapor, sulfur melts, and the solid dlotropes [201]. Mostly spectra obtained by electron impact (El) ionization have been reported, except for one study in which the main species present in sulfur vapor (S2-Ss) were studied by photoionization mass spectrometry [202]. The following ionization potentials were reported (in eV) [202] ... 

Another method of probing sulfuric acid aerosols is to heat the sample intake sufficiently to vaporize sulfuric acid-water aerosols but not other particles such as those containing ash minerals the difference between the measured particles with and without intake heating provides a measure of the contribution of sulfuric acid-water. Using this technique, Deshler et al. (1992), for example, have shown that more than 90% of the stratospheric particles above Laramie, Wyoming, after the Mount Pinatubo eruption were composed of sulfuric acid-water mixtures. 

The requirement of chemical stability will be appreciated when it is considered that the catalyst is exposed during the cracking step to hydrocarbon vapors, sulfur and nitrogen compounds, and water vapor. During the regeneration step it is exposed to sulfur dioxide, carbon monoxide, carbon dioxide, water vapor, and possibly nitrogen compounds in addition to air. 

Flue gas The air coming out of a chimney after combustion in the burner it is venting. Flue gas includes, nitrogen oxides, carbon oxides, water vapor, sulfur oxides, particles, and many chemical pollutants. 

The fuel can be either inorganic such as hydrogen, carbon monoxide, ammonia, sulfur vapor, sulfur dioxide, or organic such as... 

Mineralogical phases formed at different temperatures for each coal sample are summarized in Table III. The major mineral phases detected by XRD in LTA samples are quartz, pyrite, bassanite, kaolinite and plagioclase. The processes responsible for subsequent mineral transformations include oxidation, vaporization, sulfur fixation, dehydration and solid-state Interactions. The temperatures at which specific transformations occur are assigned on the basis of previous experimental work by Mitchell and Gluskoter (4) and published chemical data in the Handbook of Chemistry and Physics ( ). In addition to mineral-mineral interactions it is believed that reactions between minerals and exchangeable cations occur (2) ... 

When two or more condensable species present simultaneously in the gas are strongly interacting, nucieation can take place at partial pressures much lower than those required for the nucieation of the pure vapors. A well-known example is the water vapor-sulfuric acid vapor system. The details of this process, known as helewmolerular nucieation, are beyond the scope of this text (Reiss, 1950). 

There is one other key point concerning sulfur mustard. Pure sulfur mustard (HD) freezes at about 58°F. Once frozen, essentially no mustard vapor is released. Consequently, electronic monitoring relying on detection of released mustard vapor would be useless, and contamination of persons exposed to frozen sulfur mustard would not be detected by this type of monitoring. Upon rewarming, both liquid and vapor sulfur mustard would be present on the contaminated clothing. 

Carbon and sulfur are reacted (Reaction 4.1) in the absence of air in oval or cylindrical vessels called retorts. The vessels are approximately 3 ft in diameter and 10 ft in height [117] and are constructed from chrome alloy steel or cast iron. Usually, 1-4 retorts are installed in a furnace [118]. The furnace is heated by coal, gas or oil. Coal is intermittently added from the top of the retort while vaporized sulfur is continuously fed in from the bottom. Carbon disulfide is formed while the sulfur vapor works its way through the hot coal (800—1000 C) to the top of the retort. The reacted gases exit the top of the retort through a duct. Nonreactive ash and coal dust are periodically removed as they make their way to the bottom while fresh coal is added. Deposits are also removed from the inside walls of the retort, usually on a monthly or bimonthly basis. Because of the corrosive sulfur vapor, the retorts must be replaced every 1—2 years. 

Boulaud, D., G. Madeleine, D. Vigla, and J. Bricard (1977). Experimental study on the nucleation of water vapor sulfuric acid binary system. J. Chem. Phys. 66, 4854-4860. 

A membrane whidx contains sulfide ions in a molten state will act to transport sulfide across to the anode where, in the simplest case, hydrogen can be supplied to form HjS. If the membrane is capable of preventing the division of hydrogen from the cathode side, an inert sweep gas such as N, can be used at the anode to carry away oxidized sulfide ions as vaporous sulfur, Sj. 

Tamaki, K. Kawamura, K. Yoshida, H. Katayama, T. and Kaido. C. Effects of temperature, water vapor, sulfur dioxide and ammonia on the discharge oxidation of nitrogen mox o tic NIHON KAGAKUKAISHl. 1979, 1597-1063... 

Cd has been emitted in greatly increased quantities after 1945 in the form of dusts and aerosols into the atmosphere, effluent into freshwater, and as solids from anthropogenic industrial activities (Stoeppler, 1991). Cd has a relatively high vapor pressure. The vapor is oxidized quickly to produce cadmium oxide in the air. When reactive gases or vapor, such as carbon dioxide, water vapor, sulfur dioxide, sulfur trioxide or hydrogen chloride, are present, the vapor reacts to produce cadmium carbonate, hydroxide, sulfite, sulfate or chloride, respectively. These salts may be formed in stacks and emitted into the environment (WHO, 1992b). 

Melting point (decomposes), ° C 770 Relative density (water=1) 2.7 Solubility in water good Relative molecular mass 2.2 Grossformula WHITE POWDER Decomposes when heated above 770 0, giving off corrosive vapors - sulfur Moxlde). In aqueous solution is a strong acid which reacts violently with bases and Is corrosive. ... 

Melting point (decomposes), °C 100 Relative density (water-1) 2.0 Solubility In water very good Relative molecular mass 238.1 Gross formula OgS2 COLORLESS CRYSTALS OR WHITE CRYSTALLINE POWDER Decomposes when heated or on exposure to air, giving off corrosive vapors (- sulfur dioxide end — sodium peroxide). Reacts violently with combustible substances and reducing agents, with risk of fire and explosion. ... 

The reaction equilibrium and thus also the achievable sulfur yield are heavily dependent upon simultaneous side reactions caused by such other sour gas components as CO2, NH3, HCN and, above all, by hydrocarbons producing COS, CS2, CO and similar substances. As Fig. 5.9 shows that temperatures of less than 300° C are already close to the dew point of vaporous sulfur, it is not possible to reach a 100 % sulfur yield. The limit for Claus units with two catalytic stages is 96 % it can be increased to something like 98 % by adding a third stage. Newly developed titanium oxide catalysts are expected to increase the sulfur yield to approximately 99% already in Claus units with only two catalytic stages [5.7]. 

The gases vented by the summit of Mt. Erebus consists primarily of water vapor, sulfur dioxide, carbon dioxide, as well as chlorine and fluorine (Rose et al. 1985). These gases and the associated particles are the principal volcanic contaminants of the atmosphere over Antarctica and therefore have been studied by sampling from aircraft and by remote sensing using satellites(e.g., Rothery and Oppenheimer 1994). 

Fig. 16.22 (a) The inner crater of Mt. Erebus is the source of gases that are discharged by the lava lake. These gases are composed primarily of water vapor, sulfur dioxide, and lesser amounts of carbon dioxide, chlorine, and fluorine, (b) The gases react with the exposed rocks and cause the deposition of different... 

Excessive entrainmentff poor design of deflector/liquid level above the tubes. [Foulingff sodium sulfate precipitates especially in the first effect/lignin precipitates especially in the first and second effect/vapor sulfurization and condensation in third and fourth effects/velocity too small. 

Carbon disulfide is used in viscose rayon and cellophane manufacture and in the production of carbontetrachloride. In the generally preferred process, vaporized sulfur is reacted with methane according to the reactions... 

Carbon monoxide is a colorless, odorless, flammable toxic gas. Liquid carbon monoxide is a cryogenic liquid, which exists at a temperature of -313°F (-192°C) and atmospheric pressure. It becomes a flammable vapor upon addition of heat. If inhaled, concentrations of 0.4 percent in air prove fatal in less than 1 hour, while inhalation of high concentrations can cause sudden collapse with little or no warning. Pure carbon monoxide has a negligible corrosive effect on metals at atmospheric pressures. Impure carbon monoxide, containing water vapor, sulfur compounds, or other impurities causes stress corrosion to ferrous metals at elevated pressures. 

SULFUR MONOCHLORIDE (VAPORS), SULFUR, HYDROCHLORIC ACID Unknown 200 X ... 

Exhaust Gases from evaporator — 50-355 10180 G entrained phosphoric acid, sulfuric acid vapor, sulfur trioxide, nitrous acid, sdicon tetrafluonde. water vapor sprayed with water containing pho ihoric acid 0.1%. sulfuric acid 0.06%. combined fluoride 0.1%. extensive aeration... 

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