Flashing processing conditions

Natural style juices that contain the cloud are increasing in popularity, especiaHy apple juices, because these retain more fresh flavor if processed carefuUy. Optimum processing conditions chill the fmit to 4°C before milling, add 500 ppm ascorbic acid to retard browning, press under nitrogen, and flash pasteurize the juice as quickly as possible (4). 

Important flammability characteristics are the lower and upper flammability limits, the flash point, the minimum ignition energy, the minimum oxygen concentration, and the autoignition temperature. Values of some of these properties are published for many compounds (NFPA, 1994). These numbers have typically been developed under standardized test conditions. Process conditions may influence their values. 

Methods that are used to prevent VCEs include keeping low inventories of volatile, flammable materials, using process conditions that minimize flashing if a vessel or pipeline is ruptured, using analyzers to detect leaks at low concentrations, and installing automated block valves to shut systems down while the spill is in the incipient stage of development. 

Can process conditions be changed to avoid handling flammable liquids above their flash points ... 

Adhesion Adhesion of the plastic dry-mix silica fume shotcrete, particularly in wet areas, is substantially improved. For example, adhesion in areas such as locks, dry docks, tunnels, and even leaking structures, can only be achieved through the use of high concentrations of shotcrete accelerators, to create a flash-setting condition, a process that is detrimental to the long-term durability of the hardened shotcrete. Silica fume has been found to promote excellent adhesion in such conditions with minimal or no accelerator addition. 

There are now several indications that the photolysis of hexafluoro-acetone is not as simple as it was originally supposed. Herzberg et al.,59 showed that the absorption spectrum of CF2 appeared under flash photolysis conditions and Kutschke60 has identified higher perfluoroalkanes in the normal photolysis, formed, it is supposed, by mechanisms analogous to those proposed for the 1,3-dichlorotetrafluoroacetone. The C F2 involved in all these reactions may arise from disproportionation reactions, possibly on the walls of the vessel, or may be produced in a molecular process from the ketone itself. 

The effect of wavelength upon the relative proportion of the products is very marked. When the 2537 A. line from a low-pressure mercury arc is used, the yield of all three ethanes is drastically reduced, while the yield of both halogenated methanes is enhanced. The 1,3-dichlorohexafluoropropane can no longer be detected. This effect is unlikely to be due to alternative primary processes, such as mercury photosensitization, since it is also observed under flash photolysis conditions. As before, it is considered that the additional energy given to the radicals at shorter wavelengths, increases the rate of abstraction and decreases the rate of combination because of the third-body restriction. Some evidence for this... 

A simple two-phase system at the valve inlet either flashing liquid and its vapour or non-flashing liquid with non-condensable gas. A noncondensable gas is a gas that cannot be condensed under the process conditions, typically air, nitrogen, hydrogen, carbon dioxide, carbon monoxide or hydrogen sulphide. 

The real criterion regarding flammable mixtures in air should be whether a flammable atmosphere can exist under the given process conditions, rather than whether a flammable liquid is at a temperature below its flash point. 

The product acetic acid and a majority of the light ends (methyl iodide, methyl acetate, water) are separated from the reactor catalyst solution and forwarded with dissolved gases to the distillation section by an adiabatic single-stage flash. This crude separation also functions to remove the exothermal heat of reaction. The catalyst solution is recycled to the reactor. Under the process conditions of the flash, the rhodium catalyst is susceptible to deactivation at the low CO partial pressure of the flash vessel [46]. 

These equations involve iterative solutions, usually based on the initial assumption of the UV or VtL ratios. It should be noted that the terms LJVJ(n and VJ(JL are used elsewhere in this book as the absorption factor A, and the stripping factor S , respectively. While Eqs. (5.3-8) and (5.3-9) are hasic to the equilibrium flash process, one should not overlook the implied use of an energy balance to obtain the temperature and pressure conditions of the flash. 

The gap between the treatment of binary and multicomponent mixtures is closed in Chap. 1. This chapter is initiated by presenting the fundamental relationships and techniques needed for making bubble-point and dew-point calculations, and it is concluded by the presentation of techniques for solving a variety of special types of problems such as the separation of a multicomponent mixture by a single-stage flash process and the separation of a multicomponent mixture by use of multiple stages at the operating condition of total reflux. 

A boiling type of evaporation process is one in which the heat is transferred as latent heat to liquid boiling at a substantially constant temperature. It is to be distinguished from a flash process, in which heat is added to the liquid under nonboiling conditions and hence stored as internal energy. Upon subsequent reduction of the pressure, the stored internal energy supplies the latent heat to evaporate a portion of the stream. 

Figure 1 represents the general flow diagram of the multistage flash evaporation process and the solar heat collector system. The process conditions shown are typical for operation with a brine temperature of 140° F., as would be the case during May, June, and August. 

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