Steam-water mixture

General In comparison with design information on blowdown drums and cyclone separators, there is very httle information in the open technical hterature on the design of quench tanks in the Chernies industry. What is available deSs with the design of quench tanks (Sso called suppression pools) for condensation of steam or steam-water mixtures from nuclear reactor safety vSves. Information and criteria from quench tanks in the nuclear industry can be used for the design of quench tanks in the chemicS industry. There have been sev-... 

Wet steam reservoirs are much more common than the simple dry type. Again, the field is full of very hot water, under such high pressure that it cannot boil. Wdien a lower-pressure escape route is provided by drilling, some of the water suddenly evaporates (flashes) to steam, and it is a steam-water mixture that reaches the surface. The steam can be used to drive a turbine. The hot water also can be used to drive a second turbine in a binai y cycle, described in the section Electricity Generation in this article. 

Various amines find application for pH control. The most commonly used are ammonia, morpholine, cyclohexylamine, and, more recently AMP (2-amino-2-methyl-l-propanol). The amount of each needed to produce a given pH depends upon the basicity constant, and values of this are given in Table 17.4. The volatility also influences their utility and their selection for any particular application. Like other substances, amines tend towards equilibrium concentrations in each phase of the steam/water mixture, the equilibrium being temperature dependent. Values of the distribution coefficient, Kp, are also given in Table 17.4. These factors need to be taken into account when estimating the pH attainable at any given point in a circuit so as to provide appropriate protection for each location. 

A boiler bank is also included. The boiler-bank tube bundle provides sufficient heat transfer surface area to provide the rated capacity for saturated steam. Boiler-bank tube spacing and dimensions are arranged so that a steam-water circulation subsystem connects the top and bottom drums with subcooled water passing down the tubes farthest from the furnace and returning as a steam-water mixture. 

In this design, the secondary circuit FW is again on the shell side, but recirculation takes place within the steam generator, resulting in the formation of a steam-water mixture that covers the top of the inverted U-tube bundle. Saturated (but not superheated) steam passes through high-efficiency moisture separators and from here is again distributed to the turbine. 

Reduced heat capacity to the extent of the partial pressure of the steam-water mixture... 

B18. Bertoletti, S., Gaspari, G. P., Lombardi, C., Peterlongo, G., Silvestri, M and Tacconi, F. A., Heat Transfer crisis with steam-water mixtures, Energia Nucl. (Milan) 12, 3 (1965). 

Lockhart and Martinelli (1949) suggested an empirical void fraction correlation for annular flow based mostly on horizontal, adiabatic, two-component flow data at low pressures, Martinelli and Nelson (1948) extended the empirical correlation to steam-water mixtures at various pressures as shown in Figure 3.27. The details of the correlation technique are given in Chapter 4. Hewitt et al. (1962) derived the following expression to fit the Lockhart-Martinelli curve ... 

Figure 3.27 Void fraction in saturated steam-water mixture. (From Martinelli and Nelson, 1948. Copyright 1948 by American Society of Mechanical Engineers, New York. Reprinted with permission.)... 

Lottes (1961) found that the predictions based on Romie s analysis shown above agreed with ANL data within 4% at 600 psia (4.1 MPa) and within 6% at 1,200 psia (8.2 MPa), for a natural-circulation boiling system. In addition, Lottes also found that Hoopes s data for flow of steam-water mixtures through orifices appeared to verify Romie s analysis for AJA2) — 0. 

Vessel blowdown. The previously mentioned relationships for the critical flow rate of a steam-water mixture can be employed with the conservation of mass and energy for a vessel of fixed volume to determine its time-dependent blowdown properties. The range of problems associated with coolant decompression in water-cooled reactors is quite broad. The types of hypothetical (some are even incredible) reactor accidents may be... 

Figure 3.63 Superposition of representataive oscilloscope pressure traces at locations 2 and 3 for compression and rarefaction pressure pulses in low-void-fraction steam-water mixtures. (From Grolmes and Fauske, 1969. Copyright 1969 by Elsevier Science SA, Lausanne, Switzerland. Reprinted with permission.)...

As was shown before, the Leidenfrost temperature is the second transformation of heat transfer mechanisms. Empirical correlations have been established by film boiling data obtained from water at high pressure levels. For a wide range of steam-water mixture velocities, the correlation for hFB reported by Bishop et al. (1965), as shown in Eq. (4-37), is recommended for use in design. 

The graphical correlation shown in Figure 5.30 was originally developed for a steam-water mixture of high quality. Coffield et al. (1967) extended its validity into the subcooled region by comparing their subcooled Freon-113 DNB data with... 

Alessandrini, A., S. Bertoletti, G. P. Gaspari, C. Lombardi, G. Soldrini, and R. Zavattarelli, 1963, Critical Heat Flux Data for Fully Developed Flow of Steam-Water Mixtures in Round Vertical Tubes with an Intermediate Nonheated Section, Centro Informationi Studi Esperienzi Rept. CISE-R-69, Milan, Italy. (5)... 

Bennett, A. W., G. F. Hewitt, H. A. Kearsey, and R. K. F. Keeys, 1967b, Heat Transfer to Steam Water Mixture in Uniformly Heated Tubes in Which the CHF Has Been Exceeded, UK Rep. AERE-R-5373, Harwell, England. (4)... 

Era, A., G. P. Gaspari, A. Hassid, A. Milani, and R. Lavattarelli, 1966, Heat Transfer Data in the Liquid Deficient Region for Steam-Water Mixtures at 70 kg/cm2 Flowing in Tubular and Annular Conduits, Rep. CISE-R-184, Milan, Italy. (4)... 

Rep. GEAP-5081, Joint US-EURATOM Research and Development Program. (5) Evangelisti, R., G. P. Gaspari, L. Rubiera, and G. Vanoli, 1972, Heat Transfer Crisis Data with Steam Water Mixture in a Sixteen Rod Bundle, Int. J. Heat Mass Transfer 55 387-402. (5)... 

Hewitt, G. F., 1970, Experimental Studies on the Mechanisms of Burnout in Heat Transfer to Steam Water Mixtures, Paper B6.6, in Heat Transfer 1970, Vol. 6, U. Grigull and E. Hahne, Eds., Elsevier, Amsterdam. (5)... 

Kays, W. M., and A. L. London, 1958, Compact Heat Exchangers, National Press, Palo Alto, CA. (3) Keeys, R. K. F., J. C. Ralph, and D. N. Roberts, 1971, Post Burnout Heat Transfer in High Pressure Steam Water Mixtures in a Tube with Cosine Heat Flux Distribution, UK Rep. AERE-R-6411, AEA, Harwell, England. (5)... 

Polomik, E. E., S. Levy, and S. G. Sawochika, 1960, Film Boiling of Steam-Water Mixture in Annular Flow at 800, 1100, 1400 psi, ASME Paper 62-WA-136, Winter Annual Meeting, ASME, New York. (4)... 

Tarasova, N. V., A. I. Leontiev, V. I. Hlopushin, and V. M. Orlov, 1966, Pressure Drop of Boiling Subcooled Water and Steam-Water Mixture Flow in Heated Channels, Proc. 3rd Int. Heat Transfer Conf, vol. 4, pp. 178-183, ASME, New York. (3)... 

Visual deflnitions of flow patterns in vertical flow appear to cause more diflBculty than do those in horizontal flow. As the gas rate increases at a constant liquid rate, a dispersed type of flow will be reached at lower gas velocities in a vertical tube than in a horizontal one because of the influence of gravity in causing back flow of liquid. Also, vertical flow patterns tend toward radial symmetry, which is not the case in horizontal flow. A classification of vertical flow patterns based largely on air-water mixtures is given below. Surprisingly little work has been carried out for the vertical upward flow of components other than these, or steam-water mixtures. 

Many of the void-fraction correlations which have been prepared for both vertical and horizontal flow of steam-water mixtures have recently been tested by Haywood et al. (H4) against their extensive experimental data for 1-in. and IJ-in. tubes. Additional valuable evaluation is given by others in the published discussion of this paper. 

Zuber (Z2) has reported that Russian workers have used a similar but simpler approach to correlate their void-fraction data successfully for steam-water mixtures. The modified Armand equation described in... 

Levy et al. (L5) have studied the effect of eccentricity on the bum-out flux in upward vertical annular flow. Eccentricity does not affect the burn-out flux until the annular separation is about 20% or less of its concentric value. Bum-out fluxes for great eccentricities are increased about 30%, which is ascribed to poor fluid mixing pressure-drop at the same conditions is reduced. The small effect of moderate eccentricity in downward annular flow of steam-water mixtures was also reported earlier by Stein et al. (Sll) in their study of pressure-drop and critical flow. 

JAEA conducted an improvement of the RELAP5 MOD3 code (US NRC, 1995), the system analysis code originally developed for LWR systems, to extend its applicability to VHTR systems (Takamatsu, 2004). Also, a chemistry model for the IS process was incorporated into the code to evaluate the dynamic characteristics of process heat exchangers in the IS process (Sato, 2007). The code covers reactor power behaviour, thermal-hydraulics of helium gases, thermal-hydraulics of the two-phase steam-water mixture, chemical reactions in the process heat exchangers and control system characteristics. Field equations consist of mass continuity, momentum conservation and energy conservation with a two-fluid model and reactor power is calculated by point reactor kinetics equations. The code was validated by the experimental data obtained by the HTTR operations and mock-up test facility (Takamatsu, 2004 Ohashi, 2006). 

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