Particular Liquids

The laboratory bench area was covered by a large hood connected to a third exhaust fan so that experimentally generated flammable gas from open rigs was vented separately out of the laboratory. 

The fan exits through the roof had to be positioned away from the edges so as to reduce the likelihood of a lightning strike during a thunderstorm. 

An additional multi-point access vent line, positioned all round the laboratory and exhausting into the fan entrance was used to take boil-off gas from experiments and storage vessels. 

These arrangements enabled liquid methane, LNG and liquefied ethane, propane and butane to be handled in both open-top and closed dewars, cryostats and containers, just like LIN. 

In this way, students were able to gain hands-on experience, and meet at first hand the limits of measurement with instrumentation, caused by some of the peculiar properties of LNG, with its foaming, spitting and Marangoni wall films. 

---

The secondary source of fine particles in the atmosphere is gas-to-particle conversion processes, considered to be the more important source of particles contributing to atmospheric haze. In gas-to-particle conversion, gaseous molecules become transformed to liquid or solid particles. This phase transformation can occur by three processes absortion, nucleation, and condensation. Absorption is the process by which a gas goes into solution in a liquid phase. Absorption of a specific gas is dependent on the solubility of the gas in a particular liquid, e.g., SO2 in liquid H2O droplets. Nucleation and condensation are terms associated with aerosol dynamics. 

When a liquid is dispersed into droplets the surface area is increased, which enhances the rates of heat and mass transfer. For a particular liquid dispersed at constant concentration in air the MIE varies with approximately the cube of surface average droplet diameter, hence the MIE decreases by a factor of about 8 when the surface average diameter D is halved (A-5-1.4.4). Ease of ignition is greatly enhanced for finely divided mists with D less than about 20 /rm, whose MIE approaches that of the vapor. Below 10 /rm a high flash point liquid mist (tetrahydronaphthalene) was found to behave like vapor while above about 40/rm the droplets tended to burn individually [ 142]. Since liquid mists must partially evaporate and mix with air before they ignite, the ease with which a liquid evaporates also affects MIE (Eigure 5-1.4.4). 

For services where ambient or inlet temperamres may fall below 0°C, flashback protection is provided by a special seal drum or loop seal in the inlet line. This equipment is designed specifically for the particular liquid and vapor materials being flared. In these cases a 150 mm minimum water layer is included in the bottom of the pit to prevent oil seepage into the ground, and the hydrocarbon inlet distributor is mounted 150 mm above the water surface. Details of the inlet distributor are shown in Figure 5. 

On other occasions tank trucks have been filled with the wrong material. In particular, liquid oxygen or liquid air has been supplied instead of liquid nitrogen. One incident, the result of confusion over labeling, was described in Section 4.1 (f). 

The Webre design as tested by Pollock and Work [14] showed (Figure 4-50C) that internal action in the separator was responsible for some of the entrainment, particularly liquid creep up the vessel walls. 

For a particular liquid-gas system and tower packing, performance indicates a region where the liquid phase becomes... 

When a pump is taking its suction from a tank, it should be located as close to the tank as possible in order to reduce the effect of friction losses on the NPSH available. Yet the pump must be far enough away from the tank to ensure that correct piping practice can be followed. Using a larger diameter line to limit the linear velocity to a level appropriate to the particular liquid being pumped can usually reduce pipe friction. Many industries work with a maximum velocity of about 5 feet per second, but this is not always acceptable. 

The corrosive effects to be considered (mainly simple corrosion of metals) are, as would be expected from the edible nature of foodstuffs which are not excessively either acidic or basic but which may contain sulphur, less severe than those often encountered with inedible materials containing reactive substances. The importance of corrosive efiects where foodstuffs are concerned lies not so much in the action of the foodstuffs on the metal involved as in the resultant metal contamination of the foodstuff itself, which may give rise to off-flavours, in the acceleration of other undesirable changes (by the Maillard reaction for example), and in the possible formation of toxic metallic salts. Metal ions generally have threshold values of content for incipient taste effect in different liquid foodstuffs. Except in the case of the manufacture of fruit juices and pickles, process plant failure through corrosion must be rare. Nevertheless all foodstuffs, particularly liquid ones, should be regarded as potentially corrosive and capable of metal pick-up which may be undesirable. 

Example 4.5 2-Propanol (isopropanol) and water form an azeotropic mixture at a particular liquid composition that results in the vapor and liquid compositions being equal. Vapor-liquid equilibrium for 2-propanol-water mixtures can be predicted by the Wilson equation. Vapor pressure coefficients in bar with temperature in Kelvin for the Antoine equation are given in Table 4.113. Data for the Wilson equation are given in Table 4.126. Assume the gas constant R = 8.3145 kJ-kmol 1-K 1. Determine the azeotropic composition at 1 atm. 

Gas-Liquid Chromatography. In gas-liquid chromatography (GLC) the stationary phase is a liquid. GLC capillary columns are coated internally with a liquid (WCOT columns) stationary phase. As discussed above, in GC the interaction of the sample molecules with the mobile phase is very weak. Therefore, the primary means of creating differential adsorption is through the choice of the particular liquid stationary phase to be used. The basic principle is that analytes selectively interact with stationary phases of similar chemical nature. For example, a mixture of nonpolar components of the same chemical type, such as hydrocarbons in most petroleum fractions, often separates well on a column with a nonpolar stationary phase, while samples with polar or polarizable compounds often resolve well on the more polar and/or polarizable stationary phases. Reference 7 is a metabolomics example of capillary GC-MS. 

Equation 4.5 gives the system total head at a particular liquid flow rate. 

Another important physical property of liquids is the refractive index. Since the refractive index is a constant for a particular liquid at a given temperature, it can be used to help identify substances, check for purity, and measure concentrations. One type of detector found in some liquid chromatograph instruments (Chapter 13) uses refractive index. 

Plastisols allowing the use of particular liquid-state processing techniques casting, roto-moulding, dipping, coating... 

In Ramsay s experiments the forms of apparatus used were capable of sustaining pressures up to 100 atmospheres. The wide and narrow tubes were concentric the wide tube was therefore annular in shape, and the allowance for the capillary rise in it becomes difficult to calculate. Ramsay did not make a sufficient allowance for the rise in the annular tube and in consequence all his values, and those of later workers who have adopted his figures for purposes of calibration for surface tensions are too low. Sugden has used an approximate method of correcting for the rise in the annulus, in which he considers a capillary tube of circular bore which gives an identical rise at a particular temperature and for a particular liquid, and assumes that the rise in the two tubes will be the same for all other temperatures and liquids. By this means he has, with the help of later measurements, corrected all Ramsay s values for which sufficient data are given in the original papers. 

Only activated aryl halides (e.g. 2,4-dinitrochlorobenzene and picryl chloride) react with pyridine, and the facility of these reactions is subject to much the same steric and electronic controls as alkylation. Picryl chloride forms characteristic yellow TV-picryl derivatives with pyridines. These have been used to help separate, purify and characterize particular liquid pyridines. Pyridine also undergoes quaternization with diphenyliodonium fluoroborate (equation 19). Treatment of pyridine 1-oxides with arenediazonium salts yields aryloxy quaternary salts (equation 20). 

Although the viscosity values of a particular liquid alone may not furnish much insight into its structure, a comparison between a large number... 

Answer—yes But why Well, the liquid is cooled by 5°F after it leaves the drum. The cooled liquid is not in equilibrium with the vapor in the drum. It has been subcooled by 5°F. This means that the bubble-point liquid has been cooled, without altering its composition. The vapor pressure of the liquid has been reduced. As can be seen in Fig. 25.3, subcooling this particular liquid by 5°F reduces its vapor pressure by about 2 psi. As the specific gravity of the liquid is 0.58, this is equivalent to an increase in the NPSH by 8 ft. Once again, our objective is to increase the flow from 250 to 300 GPM. Figure 25.2 tells us that the required NPSH increases from 20 to 26 ft. However, when we subcool the liquid by 5°F, the available NPSH increases from 20 to 28 ft. As the available NPSH now exceeds the required NPSH by 2 ft, the flow can be increased without risk of pump cavitation. 

In this manner, it was possible to investigate the efficiency of various types of zeolite with a particular liquid system and also to investigate the effect of equilibrium water concentration on static adsorption capacity. 

With the viscosity of a liquid we mean the resistance to flow of that particular liquid. This resistance is caused by internal friction and other interactions between the particles. Among other things, viscosity is dependent on temperature, the solid volume fraction and the properties of the particles. The viscosity of normal liquids, solutions and lyophobic colloids which are not too concentrated and contain symmetrical particles is measured by allowing a certain volume to flow through a capillary and measuring the time required by the liquid to flow through it. In figure 5.10 you can see the instrument which is used for this measurement the Ostwald viscometer. 

Abstract It is well known that spontaneous deracemization or spontaneous chiral resolution occasionally occurs when racemic molecules are crystallized. However, it is not easy to believe such phenomenon will occur when forming liquid crystal phases. Spontaneous chiral domain formation is introduced, when molecules form particular liquid crystal phases. Such molecules possess no chiral carbon but may have axial chirality. However, the potential barrier between two chiral states is low enough to allow mutual transformation even at room temperature. Therefore the systems are essentially not racemic but nonchiral or achiral. First, enhanced chirality by doping chiral nematic liquid crystals with nonchiral molecules is described. Emphasis is made on ester molecules for their anomalous behavior. Second, spontaneous chiral resolution is discussed. Three examples with rod-, bent-, and diskshaped molecules are shown to give such phenomena. Particular attention will be paid to controlling enantiomeric excess (ee). Actually, almost 100% ee was obtained by applying some external chiral stimuli. This is very noteworthy in the sense that we can create chiral molecules (chiral field) without using any chiral species. 

Supercritical Fluid Extraction. Conditions can be generated that allow materials to behave differently from their native state. For example, boiling points are defined as that temperature at which a liquid changes to a gas. If the liquid is contained and pressure exerted, the boiling point changes. For a particular liquid, a combination of pressure and temperature will be reached, called the critical point, at which the material is neither a liquid nor a gas. Above this point exists a region, called the supercritical region, at which increases in both pressure and temperature will have no effect on the material (i.e., it will neither condense nor boil). This so-called supercritical fluid will exhibit properties of both a liquid and a gas. The supercritical fluid penetrates materials as if it were a gas and has solvent properties like a liquid. 

A particle containing a given volume of dry material will have its smallest possible frictional coefficient, /0, in a particular liquid when it is in the form of an unsolvated sphere. The frictional ratio, flfQ (i.e. the ratio of the actual frictional coefficient to the frictional coefficient of the equivalent unsolvated sphere) is, therefore, a measure of a combination of asymmetry and solvation. 

How to determine any HC liquid viscosity. For the viscosity of most any HC, see Fig. A-3 in Crane Technical Paper No. 410 [3], If your particular liquid is not given in this viscosity chart and you have only one viscosity reading, then locate this point and draw a curve of cP vs. temperature, °F, parallel to the other curves. This is a very useful technique. I have found it to be the more reliable, even when compared to today s most expensive process simulation program. Furthermore, I find it to be a valuable check of suspected errors in laboratory viscosity tests. If you don t have the Crane tech paper (available in any technical book store), then get one. You need it. I have found that most every process engineer I have met in my journeys to the four corners of the earth has one on their bookshelf, and it always looks very used. 

In particular, liquid-liquid extractions, wastewater treatments, gas absorption and stripping, membrane, and osmotic distillation, are the processes more studied. For example, the VOCs removal, the extraction of aroma compounds and metal ions, the concentration of aqueous solutions, the acid-gases removal, the bubble-free oxygenation/ozonation, have been successfully carried out by using membrane contactors [1, 2]. 

---