Containment vapor

Partially filled reactors and storage vessels containing vapors of corrosive constituents should be vented or provided with either vacuum removal or with a condenser return to the system. 

Placing the fluid through the tubes is a consideration when special alloy materials aie needed for corrosion control, because the materials would be needed only on the tubes. If the corrosive material is in the shell, both the tubes and the shell would need to be protected with special alloy. It the fluid is at high pressure, it should be put in tubes because tubes can contain high pressure much more cheaply as they are much smaller in diameter than the shell. The low-pressure fluid would be in the shell. If the fluid contains vapor and non-condensable gases, heat transfer will be greater if it is placed in the tubes. If the fluid is scale forming it should be in the tubes, which can be reamed out. 

As vent collection systems normally contain vapor/air mixtures, they are inherently unsafe. They normally operate outside the flammable range, and precautions are taken to prevent them from entering it, but it is difficult to think of everything that might go wrong. For example, an explosion occurred in a system that collected flarmnable vapor and air from the vents on a number of tanks and fed the mixture into a furnace. The system was designed to run at 10% of the lower explosion limit, but when the system was isolated in error, the vapor concentration rose. When the flow was restored, a plug of rich gas was fed into the furnace, where it mixed with air and exploded [17]. Reference 34 describes ten other incidents. 

This specification is intended for flame arresters protecting systems containing vapors of flammable or combnstible liqnids where vapor tem-peratnres do not exceed 60°C (140°F). 

Flooded-bundle (kettle) Easy maintenance and cleaning. Convenient when heating medium is dirty. Equivalent to theoretical plate. Contains vapor disengaging space. Lower heat transfer rates. Extra piping and space required. High residence time in heated zone. Easily fouled. 

The tubes are usually 1 V4 -in. O.D. but never smaller than 1-in. O.D. because the flow contains vapor as well as liquid. The recirculation ratio i.e., liquid-to-vapor ratio in the outlet, is seldom less than 5 and more often is 10-15, sometimes reaching 50. 

To build a molecular model of the equilibrium between a liquid and its vapor we first suppose that the liquid is introduced into an evacuated closed container. Vapor forms as molecules leave the surface of the liquid. Most evaporation takes place from the surface of the liquid because the molecules there are least strongly bound to their neighbors and can escape more easily than those in the bulk. Howevei as the number of molecules in the vapor increases, more of them become available to strike the surface of the liquid, stick to it, and become part of the liquid again. Eventually, the number of molecules returning to the liquid each second matches the number escaping (Fig. 8.2). The vapor is now condensing as fast as the liquid is vaporizing, and so the equilibrium is dynamic in the sense introduced in Section 7.11 ... 

Flammability Vessel/enclosuie rupture following ignition of contained vapors + air Vapor cloud explosion Flash fire Pool fire... 

Equation 3-21 can be modified for container vapors that are not saturated with the volatile. Let represent this adjustment factor then,... 

CC6-containing vapor species, albeit at a lower rate, and the fact that the spinel does not fully cover the alloy surface during the early stages of oxidation [139],... 

The bladder pump is similar in concept, with a flexible membrane bladder attached to the air line inside the chamber. A bladder prevents operating air from contacting pumped fluids therefore, when air is released to the atmosphere it does not contain vapors. 

The vapor pressure of a liquid dictates when a substance will boil. In fact, the boiling point of a substance is defined as the temperature at which the vapor pressure equals the external pressure. Typically, the external pressure is equal to atmospheric pressure, and we define the normal boiling point as the temperature when the vapor pressure equals 1 atmosphere. If we consider water heated on a stove, the bubbles that develop in the liquid contain water vapor that exerts a pressure at the specific vapor pressure of water at that temperature. For example, when water reaches 60°C, any bubbles that form will contain vapor at 149 mm Hg (see Table 9.4). At this pressure, and any other pressure below 760 mm Hg (1 atmosphere), the external pressure of 1 atmosphere causes the bubbles to immediately collapse. As the temperature of the water rises, the vapor pressure continually increases. At 100°C, the vapor pressure inside the bubbles finally reaches 760 mm Hg. The vapor pressure is now sufficient to allow the bubbles to rise to the surface without collapsing. At higher elevations where the external pressure is lower, liquids boil at a lower temperature. At the top of a 15,000-foot peak, water boils at approximately 85°C rather than 100°C. This increases the cooking time for items, as noted in the directions of many packaged food. If the external pressure is increased, the boiling temperature also increases. This is the concept behind a pressure cooker. The sealed cooker allows pressure to build up inside it... 

Some comments on dves Dyes can be a threat to both human health and environment. Focusing on the effect of dyes on human health, it should be pointed out that on exposure to an environment containing vapors of dyes, one would experience headaches and dizziness. After inhaling large portions of these vapors, limbs could get paralyzed and damage of the inner organs may take place. Nowadays, the risks associated with the use of such dyes have been widely recognized and many countries have posted many restrictions to their use. In Europe, the launch of a new standard called ISO 14000 has banned the import of all materials dyed with poisonous dyes. 

Another problem in the packaging of oral liquids is lack of cleanliness of the containers before filling. Fibers and even insects often appear as debris in containers, particularly in the plastic containers used for many of these products. Many manufacturers receive containers shrink-wrapped in plastic to minimize contamination from fiberboard cartons, and many manufacturers use compressed air to clean the containers. Vapors, such as oil vapors, from the compressed air have occasionally been found to present problems, and it is a good practice to use compressed gas from oil-free compressors. 

To secure the necessary temperature, the reacting mixture must be heated in a sealed tube, strong enough to resist the pressure of the contained vapors, which may amount to 10 or 12 atmospheres. 

This equation indicates that the shear force is equal to the net gravitational force, i.e., the gravitational force on the liquid less the gravitational force that would have acted on the control volume had it contained vapor and not liquid. 

The glove box atmosphere may contain vapors that are hazardous. When the vacuum chamber, which is filled with the glove box atmosphere, is opened outside, the user may be exposed to dangerous materials. It is therefore recommended that the vacuum chamber be evacuated and back-filled with fresh... 

At temperatnre Tq, all of the other tubes that still have both liquid and vapor present will contain vapor whose density is the same as that just calculated. The volume of vapor in each of these tnbes can be determined (= cross-sectional area X length of tube occupied by vapor). Therefore, the mass of CO2 present as vapor in each of these tubes can be fonnd (= density of vapor X volume of vapor). The mass of liquid CO2 in each tube can then be determined (= total CO2 vapor). Since the volume of the liquid in each tube can also be determined (= cross-sectional area X length of tube occupied by liquid), the density of the liquid phase can be found at temperature Tq. 

If Equations 9, 12, and 13 are substituted into Equation 8, a modified equilibrium relation containing vapor and liquid associations factors Z2 and r2 results ... 

Figure 21. Computer-calculated distribution of alkali-containing vapor species as a junction of temperature for the nonideal solution glass-combustion gas system...

As schematically shown in Figure 7a, initial PEVD reaction and product nucleation occurs at the three-phase boundary of solid electrolyte (E), working electrode (W) and the sink vapor phase (S) which contains vapor phase reactant (B). Only here are all reactants available for the half-cell electrochemical reaction at the sink side of a PEVD system. Although the ionic and electronic species can sometimes surface diffuse at elevated temperature to other sites to react with (B) in the vapor phase, the supply of the reactants continuously along the diffusion route is less feasible and the nuclei are too small to be stabilized under normal PEVD conditions. Only along the three phase boundary line are all the reactants available for further growth to stabilize the nuclei. Consequently, initial deposition in a PEVD process is restricted to certain areas on a substrate where all reactants for the sink electrochemical reaction are available. 

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