Potassium vapor pressure, high temperature

Liquid Metals. If operating temperatures rise above 250—300°C, where many organic fluids decompose and water exerts high vapor pressure, hquid metals have found some use, eg, mercury for limited appHcation in turbines sodium, especially its low melting eutectic with 23 wt % potassium, as a hydrauhc fluid and coolant in nuclear reactors and potassium, mbidium, cesium, and gallium in some special uses. 

Achener, P. Y., 1964, The Determination of the Latent Heat of Vaporization, Vapor Pressure, Enthalpy, and Density of Liquid Rubidium and Cesium up to 1,800°F, Proc. 1963 High Temperature Liquid Metal Heat Transfer Technology Meeting, Vol. 1, pp. 3-25 USAEC Rep. ORNL-3605. (2) Achener, P. Y, 1965, The Determination of the Latent Heat of Vaporization, Vapor Pressure of Potassium from 1,000-1,900°F, Aerojet-General Nucleonics Rep. AGN-8141. (2)... 

Bonilla, C. F., D. L. Sawhuey, and N. M. Makansi, 1962, Vapor Pressure of Alkali Metals III, Rubidium, Cesium, and Sodium-Potassium alloy up to 100 psia, Proc. 1962 High Temperature Liquid MetaI Heat Transfer Tech. Meeting, BNL-756, Brookhaven, NY. (3)... 

Illite -H2O-H2 System. Vaporization of potassium from the highly acidic illite system, in neutral atmospheres, is expected to provide a relatively insignificant source of alkali in most coal combustion systems. However, in the presence of reactive combustion gases, such as H2O and H2, thermodynamic considerations predict a significant KOH partial pressure. In addition, an increase in the K-pressure should result from a reduction in the O2 pressure, in the presence of H2. However, KMS experiments did not indicate formation of KOH or additional K in the presence of H2 gas. Thus, thermodynamic equilibrium does not appear to have been established in this heterogeneous system, even though the temperatures were sufficiently high to have normally ensured a rapid approach to equilibrium. 

Metallic potassium and sodium-potassium alloys (NaK) are manufactured by the reaction of high temperature sodium at atmospheric pressure with molten potassium chloride. Early operations of a batch process have been succeeded by a continuous one in which either pure potassium or sodium-potassium alloy of any desired composition can be produced. Molten potassium chloride is introduced into a packed column and brought in contact with ascending sodium vapors in a reaction zone to produce an equilibrium vapor of sodium and potassium. A fractionating column above the reaction zone separates the lighter boiling potassium to any degree of purity desired. The sodium chloride formed is continuously withdrawn from below the reaction zone. 

Among liquid metal candidates, mercury (Hg), sodium-potassium (NaK) alloy, sodium (Na), lead (Pb), and lead-bismuth eutectic (Pb-Bi) have been considered and used to build and operate liquid metal nuclear systems. However, liquid Na became the most smdied and used option mainly because it allowed, together with the selection of an appropriate fuel type (e.g., metal or oxide fuel), for a lower doubling time. On the other hand, hquid Hg was abandoned due to its toxicity, high vapor pressure and low boiling temperature as well as poor nuclear and heat transfer properties. More recently, in the framework of Generation IV, the development of fast reactors cooled with liquid metals considers hquid Na but also liquid Pb and liquid Pb-Bi as coolant... 

The AFC and PAFC are both liquid electrolyte solutions. The AFC, however, is based on an alkaline electrol3de solution of potassium hydroxide (KOH) in water. Other alkaline solutions can be used, notably sodium hydroxide (NaOH), but KOH is an inexpensive, easily handled solution that is used in other areas such as agriculture, so a distribution network already exists. The KOH solution molarity is typically between 30 and 80%, depending on the operating temperature. A higher molarity reduces the vapor pressure of the solution, and thus high-temperature systems require a high electrolyte concentration. 

Direct incorporation of metals in microporous supports by adsorption of metal vapors is possible in the case of alkali metals which have high vapor pressures. In an early piece of work, Rabo et al. [66] reported that faujasites are able to sta-bihze neutral or ionic sodium clusters by exposing the carefully dehydrated zeo-Htes to sodium vapors under vacuum. The technique was later improved and extended to other zeoHtes and other alkali metals. Harrison et al. [67] found that Na + clusters were located in sodalite cages. Another technique consists of using the decomposition of sodium azide (NaNj) as a source of sodium vapor [68]. Xu and Kevan [69,70] achieved a detailed characterization of clusters prepared by these methods. Sodium clusters can even be loaded at room temperature merely by stirring the zeoHte powder with sodium or potassium in the solid state or in a solution of tetrahydrofuran or hexane [71]. 

Ethyl Vinyl Ether. The addition of ethanol to acetylene gives ethyl vinyl ether [104-92-2] (351—355). The vapor-phase reaction is generally mn at 1.38—2.07 MPa (13.6—20.4 atm) and temperatures of 160—180°C with alkaline catalysts such as potassium hydroxide and potassium ethoxide. High molecular weight polymers of ethyl vinyl ether are used for pressure-sensitive adhesives, viscosity-index improvers, coatings and films lower molecular weight polymers are plasticizers and resin modifiers. 

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