Carbon water system

G.P. Cunningham, G.A. Vidulich, R.L. Kay, Several properties of acetonitrile-water, acetonitrile-methanol, and ethylene carbonate-water systems, Journal of Chemical and Engineering Data 1 (2) (1967) 336-337. 

The pH dependence of the oxygen isotope composition in the carbonate-water system has important implications in the derivation of oxygen isotope temperatures. 

The absorption of vinyl chloride(VC) on surface-treated light-grade and nanoscale calcium carbonate was shown to obey the Langmuir isothermal equation in VC/calcium carbonate/water system. The absorption of VC on calcium carbonate was shown to increase with increase of the partial pressure of VC up to the saturation absorption and the absorption of VC on nanoscale calcium carbonate was greater than that of light-grade calcium carbonate at the same temp, and partial pressure of VC. The presence of calcium carbonate in VC suspension polymerisation system was found to influence the pressure/temp./ conversion(PTC) relationship of the reaction system. Based on the absorption of VC on calcium carbonate and VC distribution in vapour, water and polymer phases, a modified model to represent the PTC relationship of VC suspension polymerisation in the presence of calcium carbonate was proposed. 10 refs. 

Both quahtative and qnantitative data ate available. Only the qnantitative data can be nsed to obtain thermodynamic parameters, but the quahtative information can in some cases be nsed to corroborate the quantitative conclusions, e.g. concerning the stoichiometiy of complexes and the mode of coordination of the carbonate ligand. (Qnantitative determinations of the stoichiometiy and equilibrium constants are described in the following section. These studies are complicated by the formation of sparingly solnble sohd phases and the formation of ternary Th(lV)-hydroxide-carbonate species. This review will therefore begin with a short summary of the advantages and disadvantages of the varions methods nsed to deduce the stoichiometiy and eqnilibrinm constants in the temaiy Th(lV)-carbonate-water system. 

Figure 2. Calculated temperature dependence of the major species in the carbon-water system for a C H20 molar ratio of 1 1 at 100 MPa.

SEVERAL PROPERTIES OF ACETONITRILE-WATER, ACETONITRILE-METHANOL AND ETHYLENE CARBONATE-WATER SYSTEMS... 

ZA2 Zafarani-Moattar, M.T. and Nilgoo, D., Phase diagrams for liquid-liquid and liquid-solid equilibrium of the ternary polyfethylene glycol) dimethyl ether 2000 + sodium carbonate + water system, J. Chem. Eng. Data, 54, 2918, 2009. 

Lam, S. Y Benoit, R. L. Some thermodynamic properties of the dimediylsulfoxide-water and propylene carbonate-water systems at 25.deg.C. Can. J. Chem. 1974, 52, 718-722. 

Certain types of equipment are specifically excluded from the scope of the directive. It is self-evident that equipment which is already regulated at Union level with respect to the pressure risk by other directives had to be excluded. That is the case with simple pressure vessels, transportable pressure equipment, aerosols and motor vehicles. Other equipment, such as carbonated drink containers or radiators and piping for hot water systems are excluded from the scope because of the limited risk involved. Also excluded are products which are subject to a minor pressure risk which are covered by the directives on machinery, lifts, low voltage, medical devices, gas appliances and on explosive atmospheres. A further and last group of exclusions refers to equipment which presents a significant pressure risk, but for which neither the free circulation aspect nor the safety aspect necessitated their inclusion. 

The water—carbon slurry formed in the quench vessel is separated from the gas stream and flows to the carbon recovery system needed for environmental reasons and for better thermal efficiency. The recovered carbon is recycled to the reactor dispersed in the feedstock. If the fresh feed does not have too high an ash content, 100% of the carbon formed can be recycled to extinction. 

Cathodic Protection This electrochemical method of corrosion control has found wide application in the protection of carbon steel underground structures such as pipe lines and tanks from external soil corrosion. It is also widely used in water systems to protect ship hulls, offshore structures, and water-storage tanks. 

A test water box was installed during a 2-week trial to monitor corrosion and fouling in a utility cooling water system. A baffle plate from the test box was removed after the test. Small, hollow incipient tubercles dotted surfaces (Fig. 3.28). Small amounts of carbonate were present atop and around each tubercle. Each tubercle capped a small depression no deeper than 0.005 in. (0.013 cm) (Fig. 3.29). This indicated local average corrosion rates were as high as 130 mihy (3.3 mm/y). 

A wide variety of precipitates form in cooling water systems carbonates, silicates, sulfates, and phosphates are common. Below and slightly above 212°F (100°C), calcite, aragonite, gypsum, hydroxyapatite, magnesium phosphate, anhydrite, and serpentine are commonly encountered (see Table 4.1). 

Calcium carbonate makes up the largest amount of deposit in many cooling water systems (Fig. 4.16) and can be easily detected by effervescence when exposed to acid. Deposits are usually heavily stratified, reflecting changes in water chemistry, heat transfer, and flow. Corrosion may be slight beneath heavy accumulations of fairly pure calcium carbonate, as such layers can inhibit some forms of corrosion. When nearly pure, calcium carbonate is white. However, calcium carbonates are often intermixed with silt, metal oxides, and precipitates, leading to severe underdeposit attack. 

Carbon steel heat exchangers, cast iron water boxes, screens, pump components, service water system piping, standpipes, fire protection systems, galvanized steel, engine components, and virtually all non-stainless ferrous components are subject to significant corrosion in oxygenated water. 

A typical microbiological analysis in a troubled carbon-steel service water system is given in Table 6.2. Table 6.3 shows a similar analysis for a cupronickel utility main condenser that showed no significant corrosion associated with sulfate reducers. When biological counts of sulfate reducers in solid materials scraped from corroded surfaces are more than about 10, significant attack is possible. Counts above 10 are common only in severely attacked systems. 

Note that low carbon or stabilized grades of stainless steel do not possess intrinsically greater corrosion resistance than their unadjusted counterparts. Their sole value in typical cooling water systems results from their resistance to sensitization and potential weld decay that can result when the metals are welded. It is therefore not economically justifiable to specify low carbon or stabilized grades of stainless steel for typical cooling water system components that are not to be welded. 

Once a fire has started, control of the fire can be accomplished in several ways through water systems (by reducing the temperature), carbon dioxide or foam systems (by limiting oxygen), or through removal of the substrate (by shutting off valves or other controls). Chapter 4 provides detailed discussion on the theories of fire and specific information on hydrocarbons, as well as chemical specific fire characteristics. 

Applications of carbon adsorption go far beyond conventional water treatment applications which we will discuss in a general sense shortly. Table 8 provides a summary of the key applications of carbon adsorption systems for liquid phase applications. 

If the water system contains dissolved carbon dioxide, iron carbonate may form ... 

Figure 4-469 shows the effect on corrosion rates of 1020 steel in different water systems with dissolved hydrogen sulfide. The difference in corrosion rates is due to different corrosion products formed in different solutions. In solution I, kansite forms. Kansite is widely protective as the pyrrhotite coats the surface giving slightly more protection until a very protective pyrite scale is formed. In solution II, only kansite scale forms, resulting in continued increase in the corrosion rate. Finally, in solution 111, pyrite scale is formed as in solution I however, continued corrosion may be due to the presence of carbon dioxide. 

The effect of pH on the corrosion of zinc has already been mentioned (p. 4.170). In the range of pH values from 5 -5 to 12, zinc is quite stable, and since most natural waters come within this range little difficulty is encountered in respect of pH. The pH does, however, affect the scale-forming properties of hard water (see Section 2.3 for a discussion of the Langelier index). If the pH is below the value at which the water is in equilibrium with calcium carbonate, the calcium carbonate will tend to dissolve rather than form a scale. The same effect is produced in the presence of considerable amounts of carbon dioxide, which also favours the dissolution of calcium carbonate. In addition, it is important to note that small amounts of metallic impurities (particularly copper) in the water can cause quite severe corrosion, and as little as 0-05 p.p.m. of copper in a domestic water system can be a source of considerable trouble with galvanised tanks and pipes. 

Goodridue, F. and Bricknell, D.J. Trans. Inst. Chem. Eng. 40 (1962) 54. Interfacial resistance in the carbon dioxide-water system. 

Comparing equations 13.8 and 13.9, it is seen that the adiabatic saturation temperature i > equal to the wet-bulb temperature when s = h/hDpA. This is the case for most water vapour systems and accurately so when Jf = 0.047. The ratio (h/hopAs) = b is sometimes known as the psychrometric ratio and, as indicated, b is approximately unity for the air-water system. For most systems involving air and an organic liquid, b = 1.3 - 2.5 and the wet-bulb temperature is higher than the adiabatic saturation temperature. This was confirmed in 1932 by SHERWOOD and COMINGS 2 who worked with water, ethanol, n-propanol, n-butanol, benzene, toluene, carbon tetrachloride, and n-propyl acetate, and found that the wet-bulb temperature was always higher than the adiabatic saturation temperature except in the case of water. 

Wemer M, Mikolajewicz U, Hoffmann G, Heimann M (2000) Possible changes of in precipitation caused by a meltwater event in the North Atlantic. J Geophys Res 10 10161-10167 Whitehead NE, Ditchbmn RG, Wilhams PW, McCabe WJ (1999) Pa and contamination at zero age a possible hmitation on U/Th series dating of speleothem material. Chem Geol 156 359-366 Wigley TML, Plummer LN, Pearson FJ (1978) Mass transfer and carbon isotope evolntion in natural water systems. Geochim Cosmochim Acta 42 1117-1140... 

For effective volatilization using an enclosed mechanical aeration system, contaminated soil is mixed in a pug mill or rotary drum. The gasoline components are released from the soil matrix by the churning action of the air/soil contact. The induced airflow within the chamber captures the gasoline emissions and passes them through an air pollution control device (e.g., a water scrubber or vapor-phase carbon adsorption system) before they are discharged through a properly sized stack. 

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