Water steam

Sodium hydroxide solution cannot be used at this stage since it may produce benzoic acid by the Cannizzaro reaction (Section IV,123) from any unchanged benzaldehyde. If, however, the reaction mixture is diluted with 3-4 volumes of water, steam distilled to remove the unreacted benzaldehyde, the residue may then be rendered alkaline with sodium hydroxide solution. A few grams of decolourising carbon are added, the mixture boiled for several minutes, and filtered through a fluted filter paper. Upon acidifying carefully with concentrated hydrochloric acid, cinnamic acid is precipitated. This is collected, washed and purified as above. 

IIO)jCsH3 H HOAc, H2SO4, water, steam bath t hr 92.5 87, 484... 

Energy in the form of injected water or CO2 may be suppHed to increase the rate of production of light cmde oils. AppHcation of heat to the reservoirs, eg, using hot water, steam, heated CO2, fireflood, or in situ combustion, however, is generally associated with the production of heavier, viscid cmdes. 

There are two principal mechanisms of enhanced oil recovery increasing volumetric sweep efficiency of the injected fluid and increasing oil displacement efficiency by the injected fluid. In both, chemicals are used to modify the properties of an injected fluid whether water, steam, a miscible gas such as CO2 or natural gas, or an immiscible gas, usually nitrogen. Poor reservoir volumetric sweep efficiency is the greatest obstacle to increasing oil recovery (9). 

Fig. 4. In the Solar Two Project a molten salt system shown in the scheme replaces Solar One s water/steam system. In operation, "cold" molten salt is pumped from a storage tank to a receiver on a tower. Sunlight reflected from a field of sun-tracking mirrors heats the salt in the receiver to 1050°C. The heated salt then flows down into a hot storage tank where it is pumped to a heat exchanger to produce the steam that drives a turbine. Some of the hot molten salt can also be stored to produce steam on demand at a later time. Salt cooled to 550°C in the steam generator recirculates through the system and...

Based on the results of the Solar One plant. Southern California Edison formed a consortium that included DOE and EPRI to constmct a Solar Two Project. Solar Two will convert the idle Solar One central receiver plant from a water/steam system to a molten salt system, thereby improving efficiency and operating performance. With the molten salt technology, solar energy can be collected during the day and stored in the salt to produce electricity when needed. The three-year demonstration is scheduled to begin in late 1996. 

Molecular Nature of Steam. The molecular stmcture of steam is not as weU known as that of ice or water. During the water—steam phase change, rotation of molecules and vibration of atoms within the water molecules do not change considerably, but translation movement increases, accounting for the volume increase when water is evaporated at subcritical pressures. There are indications that even in the steam phase some H2O molecules are associated in small clusters of two or more molecules (4). Values for the dimerization enthalpy and entropy of water have been deterrnined from measurements of the pressure dependence of the thermal conductivity of water vapor at 358—386 K (85—112°C) and 13.3—133.3 kPa (100—1000 torr). These measurements yield the estimated upper limits of equiUbrium constants, for cluster formation in steam, where n is the number of molecules in a cluster. 

Udel is a slightly yellow but tianspaient engineering thermoplastic. It has low flammability and smoke emission and good electrical properties. It has excellent resistance to water, steam, and alkaline solutions. Specific uses for Udel iaclude microwave cookware, beverage dispensers, coffee brewers, cookware, hair dryers, com poppers, and steam table trays. Its steam resistance makes it particularly fit for a dishwasher environment. Properties of polysulfone resias ate given ia Table 11. 

Boiler Design Issues Boiler design involves the interaction of many variables water-steam circulation, fuel characteristics, firing systems and heat input, and heat transfer. The furnace enclosure is one of the most critical components of a steam generator and must be conservatively designed to assure high boiler availability. The furnace... 

PAFC systems are commercially available from the ONSI Corporation as 200-kW stationary power sources operating on natural gas. The stack cross sec tion is 1 m- (10.8 ft"). It is about 2.5 m (8.2 ft) tall and rated for a 40,000-h life. It is cooled with water/steam in a closed loop with secondary heat exchangers. The photograph of a unit is shown in Fig. 27-66. These systems are intended for on-site power and heat generation for hospitals, hotels, and small businesses. Another apphcation, however, is as dispersed 5- to 10-MW power plants in metropolitan areas. Such units would be located at elec tric utihty distribution centers, bypassing the high-voltage transmission system. The market entiy price of the system is 3000/kW. As production volumes increase, the price is projec ted to dechne to 1000 to 1500/kW. 

Copper To 1500 Properties depend on other construction materials and form of copper used. Packing made of copper foil over asbestos core resists steam and alkalies to lOOO F. Packing of braided copper tinsel resists water, steam, and gases to 1500 F. 

Hot corrosion is a rapid form of attack that is generally associated with alkali metal contaminants, such as sodium and potassium, reacting with sulfur in the fuel to form molten sulfates. The presence of only a few parts per million (ppm) of such contaminants in the fuel, or equivalent in the air, is sufficient to cause this corrosion. Sodium can be introduced in a number of ways, such as salt water in liquid fuel, through the turbine air inlet at sites near salt water or other contaminated areas, or as contaminants in water/steam injections. Besides the alkali metals such as sodium and potassium, other chemical elements can influence or cause corrosion on bucketing. Notable in this connection are vanadium, primarily found in crude and residual oils. 

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