Amount of Solvent Evaporated

If the boiling point is attained during runaway, a possible secondary effect of the evaporation of a solvent is the formation of an explosive vapor cloud, which in turn can lead to a severe explosion if ignited. In some cases, there is enough solvent present in the reaction mixture to compensate the energy release, allowing the temperature to stabilize at the boiling point. This is only possible if the solvent can be safely refluxed or distilled off into a catch pot or a scrubber. Moreover, the 

The amount of solvent evaporated can easily be calculated by using the energy of the reaction and/or of the decomposition as follows  

After a cooling failure, when boiling point is reached, a fraction of the energy released is used to heat the reaction mass to the boiling point and the remaining fraction of the energy results in evaporation. The amount of evaporated solvent can be calculated from the distance to the boiling point  

In Equations 2.9 and 2.10, the enthalpy of evaporation used is the specific enthalpy of evaporation, expressed in kjkg 1. These expressions only give the amount of solvent evaporated, which is a static parameter. They give no information about the vapor flow rate, which is related to the dynamics of the process, that is, the reaction rate (see Section 9.4). This aspect is discussed in the chapter on technical aspects of reactor safety. 

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Five or ten microliters of hexane containing a known amount of the analyte was injected into the sorbent bed in the vial. This amount of solvent evaporated rapidly. 

PSAs (readily soluble rubber systems) are also available in spray forms, making it possible to cover large areas with an adhesive film and to adapt the film thickness to the requirements at hand, whereby however large amounts of solvent evaporate. 

Molded urethane technology in the immediate future should not be limited by mold release considerations, but the role of the mold release in new systems should be considered early in the plans. Regulations for air quality control and worker safety are expected to create a continuing shift to water-based mold releases, or at least some means of greatly reducing the amount of solvent evaporated. Some progress seems likely in use of semi-permanent release coatings which can be renewed by periodic application of a top coat. 

The amount of volatiles formed during coating application is, as a rule, not very high and for most paints does not surpass 3-5 g per kg of paint used. This is hundreds of times less than the amount of solvents evaporating during liquid paint application. 

LEL is not applicable. The circulating gas can pick up as much solvent per pass as the limits set by product quality allow. A concentration of 10 times the LEL is typical of what can be achieved leaving the evaporation zone. Thus, for a given amount of solvent evaporated, a 30-fold reduction in gas to be handled in the evaporation zone is theoretically possible. 

To determine the crystal yield from a vacuum crystallizer (section 7.5.3) it is necessary to estimate the amount of solvent evaporated, V. This depends on the heat made available during the operation of the crystallizer, i.e. the sum of the sensible heat drop of the solution, which cools from the feed temperature to the equilibrium temperature in the vessel, and the heat of crystallization Kber-ated. The heat balance, therefore, will be... 

The physical properties of liquids, sueh as viseosity (Figure 7.1.23) and surface tension (Figure 7.1.24), also change during the evaporation proeess. The viscosity change for this system was a linear fimetion of the amount of solvent evaporated. This study on waterborne coatings showed that the use of a cosolvent (e.g. i-butanol) caused a reduction in... 

For gas separation applications, the feed stream is usually fed into the shell side of the module. This implies that the dense selective layer should be located on the outside of the polyaniline hollow fiber membrane. To achieve this desired morphology, the polyaniline hollow fiber was spun using an air gap between the spinneret and the coagulation bath. The residence time in the air gap influences the amount of solvent evaporation, which in turn governs the thickness of the dense separating layer on the outer surface of the hollow fiber. By adjusting the residence time from a few seconds to 30 s, the thickness of the dense separating layer on the outer surface of the hollow was successfully varied between 0.5 and 5 xm. 

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