Boiling liquids mechanisms

Forster, H. K., and R. Greif, 1959, Heat Transfer to Boiling Liquid, Mechanism and Correlations, Trans. ASME, J. Heat Transfer 81 43 53. (2)... 

K. Engelberg-Forester and R. Greif, Heat Transfer to a Boiling Liquid—Mechanism and Correlations, J. Heat Transfer (81) 43-53,1959. 

K. E. Forster andR. Greif, Heat Transfer to a Boiling Liquid Mechanism and Correlations, ASME paper 58-HT-ll (1958). 

Place 84 g. of iron filings and 340 ml. of water in a 1 - 5 or 2-litre bolt-head flask equipped with a mechanical stirrer. Heat the mixture to boiling, stir mechanically, and add the sodium m-nitrobenzenesulphonate in small portions during 1 hour. After each addition the mixture foams extensively a wet cloth should be applied to the neck of the flask if the mixture tends to froth over the sides. Replace from time to time the water which has evaporated so that the volume is approximately constant. When all the sodium salt has been introduced, boU the mixture for 20 minutes. Place a small drop of the suspension upon filter paper and observe the colour of the spot it should be a pale brown but not deep brown or deep yellow. If it is not appreciably coloured, add anhydrous sodium carbonate cautiously, stirring the mixture, until red litmus paper is turned blue and a test drop upon filter paper is not blackened by sodium sulphide solution. Filter at the pump and wash well with hot water. Concentrate the filtrate to about 200 ml., acidify with concentrated hydrochloric acid to Congo red, and allow to cool. Filter off the metanilic acid and dry upon filter paper. A further small quantity may be obtained by concentrating the mother liquid. The yield is 55 g. 

Flooded evaporators require a constant liquid level, so that the tubes remain wetted. A simple float valve suffices, but must be located with the float outside the evaporator shell, since the surface of the boiling liquid is agitated and the constant movement would cause excessive wear in the mechanism. The float is therefore contained within a separate chamber, coupled with balance lines to the shell (see Figure 8.1). 

Figure 2.4 Saturated boiling liquid temperature variations within thermal sublayer, and bubble counts departing from heating surface. (From Dougall and Lippert, 1967. Copyright 1967 by American Society of Mechanical Engineers, New York. Reprinted with permission.)...

This equation was derived based on a sensible heat transport mechanism. When applied to boiling liquid metals, q"ril sat in this equation becomes "vap, which can be obtained by Eq. (2-128a). Substituting this into Eq. (2-142),... 

Laboratory Safety From a laboratory safety standpoint, both open and closed systems have mechanisms for the disposal of hazardous wastes, thus reducing the technician s exposure to potentially toxic materials. Performing HIAR online (closed system) as opposed to off-line mechanisms (microwave ovens or steamers) removes the possibility of being burned while handling hot containers or boiling liquids. 

The minimum design temperature should be the lowest temperature to which the tank will be subjected, taking into consideration the minimum temperature of material entering the tank, the minimum temperature to which the material may be autorefrigerated by rapid evaporation of low-boiling liquids or mechanically refrigerated, the minimum ambient temperature of the area where the tank is located, and any possible temperature reduction by endothermic physical processes or chemical reactions involving the stored material. API 620 provides for installations in areas where the lowest recorded 1-day mean temperature is 50°F (10°C). 

The superheat limit was first proposed in the late 1970s as a possible mechanism for explaining catastrophic vessel failures. Reid (1979), Jones (1985), Martinsen et al. (1986), Davenport (1988), and Dunn (1988) suggest that BLEVEs (Boiling Liquid Expanding Vapor Explosions) are superheat explosions and therefore are easily predicted by assessing the superheat limit for any pressurized liquid material. 

A Latin American chemical plant experienced a catastrophic fire and series of Boiling Liquid Expanding Vapor Explosions (BLEVEs) that resulted in the loss of one life and 5 million in direct damages (1977 dollars). The initial vapor cloud occurred as a maintenance mechanic started to remove a pneumatic actuator from the liquid discharge line below a tank of flashing flammable liquid that had a boiling point of 7° F (—14° C). 

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