Flashing Flow analysis

Fig. 4.2 Improved flash distillation apparatus for continuous-flow analysis.

There are many equally valid techniques fot estimating two-phase flow rates. The nuclear industry has undertaken substantial analysis of critical two-phase flow of steam-water mixtures. The Nuclear Energy Agency (1982) has published a review of four models and summarized available experimental data. Klein (1986) reviews the one-dimensional DEERS model for the design of reUef systems for two-phase flashing flow. Three-dimensional models arc also available although litdc published information on their use is available. Additional complexity does not guarantee improved accuracy and can unnecessarily complicate the task of risk analysis. 

Tfre most frequently used techniques for a flash polymer analysis are infrared spectroscopy and SEC. Infrared spectroscopy provides information on the chemical substmctures present in the sample, while SEC gives a first indication of the molar mass range. Information on both molar mass and composition is obtained when SEC or a comparable chromatographic method is combined with an infrared detector. In the past, infrared detection of the SEC column effluent in liquid flow cells was used frequentiy. The problems related to... 

Often in plant operations condensate at high pressures are let down to lower pressures. In such situations some low-pressure flash steam is produced, and the low-pressure condensate is either sent to a power plant or is cascaded to a lower pressure level. The following analysis solves the mass and heat balances that describe such a system, and can be used as an approximate calculation procedure. Refer to Figure 2 for a simplified view of the system and the basis for developing the mass and energy balances. We consider the condensate to be at pressure Pj and temperature tj, from whence it is let down to pressure 2. The saturation temperature at pressure Pj is tj. The vapor flow is defined as V Ibs/hr, and the condensate quality is defined as L Ibs/hr. The mass balance derived from Figure 2 is ... 

In the laser flash method, the heat is put in by laser flash instead of electric current in the stepwise heating method mentioned above. Thus this method may be classified as a stepwise heating method. A two-layered laser flash method was developed by Tada et al. " The experimental method and the data analysis, including a case involving radiative heat flow, are described in detail in the review article by Waseda and Ohta. A thin metal plate is placed at the surface of a melt. A laser pulse is irradiated onto a metal plate of thickness / having high thermal conductivity. The sample liquid under the metal plate and the inert gas above the plate are designated as the third and first layers, respectively. The temperature of the second layer becomes uniform in a short time" and the response thereafter is expressed by... 

To find the optimized flash pressure that will give the most turbine power per unit geothermal hot-water mass flow rate, we use sensitivity analysis. A plot of power versus turbine inlet pressure is made as shown in Fig. 2.24b. The maximum power is found to be about 42 kW at a pressure of about 140 kPa. 

The mixture was extracted with diethyl ether (three times). The combined organic layers were washed with brine and dried over sodium sulfate. After concentration in vacuo, the residue was purified by silica gel flash column chromatography (hexane/ethyl acetate = 20/1-3/1) to give (5)-l (426.3 mg, 74%, 98% ee) as a colourless solid. The enantiomeric excess of (5)-l was determined by chiral stationary-phase HPLC analysis DAICEL CHIRALCEL OD-H, j-PrOH/hexane 1/4, flow rate l.OmLmin tR 14.0 min [(R)-isomer)] and 21.3 min [(5)-isomer), detection at 254 nm]. ... 

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