Steam Promoter

Steam irons are intended to produce steam smoothly and efficiently by having drops of water fall on a small hot area of the metal sole plate called the steam chamber. The steam generated exits through holes in the bottom of the sole plate that is in contact with the fabric. However, when the iron is new, the clean metal surface of the steam chamber is likely to act like a metal griddle. The water droplet will dance around the surface on a thin layer of steam. The contact with the metal surface is minimal and so is the rate of steam production. 

Two criteria must be met in order to get an adherent layer of colloidal silica on the steam chamber  

In order to accomplish these criteria, the sole plates are cleaned before the material is applied. This can be done 

Another method of preparing interesting media for chromatography is to spray dry colloidal silica. During spray drying, water evaporates from the droplet surface and colloidal silica particles become more and more concentrated as the droplets become smaller in volume. At some point, the colloidal silica particles are concentrated 

Since sodium often acts as a catalyst poison, ammonia stabilized versions of colloidal silica are most often used in the preparation of catalysts. In some cases freshly deionized silicate is used as the silica source. This form of active silica is much higher in surface area and is therefore a more efficient binder. However, its use causes the 

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Vanadium is transferred by interpaiticle solid state transport. The combination of oxygen or air plus steam promotes surface migration and enrichment of vanadia species which are not crystalline V2O5. Interpaiticle contact is a requirement for vanadium transfer from particle to particle. Evidence for a volatile vanadic acid species could not be found. 

Steam also is blended with air in some gasification units to promote the overall process via the endothermic steam—carbon reaction to form carbon monoxide and hydrogen. This was common practice at the turn of the nineteenth century, when so-called producer gasifiers were employed to manufacture LHV gas from different types of biomass and wastes. The producer gas from biomass and wastes had heating values around 5.9 MJ /mr at... 

This reaction is first conducted on a chromium-promoted iron oxide catalyst in the high temperature shift (HTS) reactor at about 370°C at the inlet. This catalyst is usually in the form of 6 x 6-mm or 9.5 x 9.5-mm tablets, SV about 4000 h . Converted gases are cooled outside of the HTS by producing steam or heating boiler feed water and are sent to the low temperature shift (LTS) converter at about 200—215°C to complete the water gas shift reaction. The LTS catalyst is a copper—zinc oxide catalyst supported on alumina. CO content of the effluent gas is usually 0.1—0.25% on a dry gas basis and has a 14°C approach to equihbrium, ie, an equihbrium temperature 14°C higher than actual, and SV about 4000 h . Operating at as low a temperature as possible is advantageous because of the more favorable equihbrium constants. The product gas from this section contains about 77% H2, 18% CO2, 0.30% CO, and 4.7% CH. ... 

Naphtha desulfurization is conducted in the vapor phase as described for natural gas. Raw naphtha is preheated and vaporized in a separate furnace. If the sulfur content of the naphtha is very high, after Co—Mo hydrotreating, the naphtha is condensed, H2S is stripped out, and the residual H2S is adsorbed on ZnO. The primary reformer operates at conditions similar to those used with natural gas feed. The nickel catalyst, however, requires a promoter such as potassium in order to avoid carbon deposition at the practical levels of steam-to-carbon ratios of 3.5—5.0. Deposition of carbon from hydrocarbons cracking on the particles of the catalyst reduces the activity of the catalyst for the reforming and results in local uneven heating of the reformer tubes because the firing heat is not removed by the reforming reaction. 

Thermal cracking tends to deposit carbon on the catalyst surface which can be removed by steaming. Carbon deposition by this mechanism tends to occur near the entrance of the catalyst tubes before sufficient hydrogen has been produced by the reforming reactions to suppress the right hand side of the reaction. Promoters, such as potash, are used to help suppress cracking in natural gas feedstocks containing heavier hydrocarbons. Carbon may also be formed by both the disproportionation and the reduction of carbon monoxide... 

Reduction of sulfur dioxide by methane is the basis of an Allied process for converting by-product sulfur dioxide to sulfur (232). The reaction is carried out in the gas phase over a catalyst. Reduction of sulfur dioxide to sulfur by carbon in the form of coal has been developed as the Resox process (233). The reduction, which is conducted at 550—800°C, appears to be promoted by the simultaneous reaction of the coal with steam. The reduction of sulfur dioxide by carbon monoxide tends to give carbonyl sulfide [463-58-1] rather than sulfur over cobalt molybdate, but special catalysts, eg, lanthanum titanate, have the abiUty to direct the reaction toward producing sulfur (234). 

In the batchwise process the temperature can be raised to 80°C to promote levelness providing dyes not sensitive to reductive breakdown are used. In the continuous appHcation method the vat dye is padded onto fabric and dried under conditions that avoid migration, passed through a solution of sodium hydrosulfite and caustic, through a pad mangle, and then steamed in saturated steam for up to 60 s. 

Film-type condensation is more common and more dependable. Dropwise condensation normally needs to be promoted by introducing an impurity into the vapor stream. Substantially higher (6 to 18 times) coefficients are obtained for dropwise condensation of steam, but design methods are not available. Therefore, the development of equations for condensation will be for the film type only. 

Patent 3,384,154, May 21, 1968). Both of these tubes also had steam-side coatings to promote dropwise condensation—paryleue for tube 47 and gold plating for tube 39. 

Water contamination is a constant threat. The sources of water are many—atmospheric condensation, steam leaks, oil coolers, and reservoir leaks. Rusting of machine parts and the effects of rust particles in the oil system are the major results of water in oil. In addition, water forms an emulsion and, combined with other impurities, such as wear metal and rust particles, acts as a catalyst to promote oil oxidation. 

Amine strippers use heat and steam to reverse the chemical reactions with CO2 and H2S. The steam acts as a stripping gas to remove the COo and HjS from the liquid solution and to cairy these gases to the overhead. To promote mixing of the solution and the steam, the stripper is a trayed or packed tower with packing normally used for small diameter columns. 

Hasegawa, K., and Sato, K. 1977. Study on the fireball following steam explosion of n-pentane. Second International Symposium on Loss Prevention and Safety Promotion in the Process Industries, pp. 297-304. 

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