Puffs

Steam is injected into a reservoir to reduce oil viscosity and make it flow more easily. This technique is used in reservoirs containing high viscosity crudes where conventional methods only yield very low recoveries. Steam can be injected in a cyclic process in which the same well is used for injection and production, and the steam is allowed to soak prior to back production (sometimes known as Huff and Puff). Alternatively steam is injected to create a steam flood, sweeping oil from injectors to producers much as in a conventional waterflood. In such cases it is still found beneficial to increase the residence (or relaxation) time of the steam to heat treat a greater volume of reservoir. 

Raise the temperature gradually to 200-250° until the mass finally forms large bubbles and puffs up into a voluminous mass. At this point allow the beaker to cool. Remove the brittle mass from the beaker as completely as possible and powder it in a mortar. 

A good compilation of the functions of fats in various food products is available (26). Some functions are quite subtle, eg, fats lend sheen, color, color development, and crystallinity. One of the principal roles is that of texture modification which includes viscosity, tenderness (shortening), control of ice crystals, elasticity, and flakiness, as in puff pastry. Fats also contribute to moisture retention, flavor in cultured dairy products, and heat transfer in deep fried foods. For the new technology of microwave cooking, fats assist in the distribution of the heating patterns of microwave cooking. 

The ribbon machine employs a puff-and-blow method to make incandescent light bulb envelopes (1200/min), dashbulb envelopes (2000/min), Christmas tree ornaments, and the like (Fig. 15). For larger articles, the turret chain machine also uses the puff-and-blow method, but produces less cuUet and uses individual glass gobs rather than ribbon. 

The dispersion model is typically used to determine the downwind concentrations of released materials and the total area affected. Two models are available the plume and the puff. The plume describes continuous releases the puff describes instantaneous releases. 

Another method of using CO2 is called cycHc CO2 stimulation or huff n puff (26). A limited amount of CO2 is iajected into a reservoir over hours or days. The well is then shut in for a soak period of days to weeks to allow the CO2 to interact with the cmde oil, swelling the oil and reducing its viscosity. 

The injection of large volumes of steam, steam flooding, is used to mobilize oil which is produced at offset production wells. Smaller volumes of steam are injected in the cycHc steam stimulation or huff n puff process (Eig. 2). Many wells are placed on several cycles of steam stimulation and then used as injection or production wells in steam flood projects. 

Eig. 2. Cychc steam stimulation of an oil well (a) steam, injected into a well over a period of days or weeks in a heavy oil reservoir, introduces heat (huff) that, coupled with (b), alternate soak periods lasting a few days to allow (c) a production phase of weeks or months (puff), thins the oil. This process may... 

Transfer occurs by sublimation, condensation, and diffusion (101). Printhead thermal dissipation causes donor dye to travel to the surface of the donor ribbon and convert directiy to a gas. Colorant puffs immediately strike the nearby receptor and soak in, assisted by residual printhead heat. 

Fig. 7. Comparison of various transport schemes for advecting a cone-shaped puff in a rotating windfield after one complete rotation (a), the exact solution (b), obtained by an accurate numerical technique (c), the effect of numerical diffusion where the peak height of the cone has been severely tmncated and (d), where the predicted concentration field is very bumpy, showing the effects of artificial dispersion. In the case of (d), spurious waves are...

Butter is used in some, usually more expensive, bakery foods, and is prized for its flavor contribution. Fats are used in some products such as pie cmst, croissants, or puff pastry, up to 60%, based on flour. StabiHty of fats and oils in perishable items such as breads, cakes, or pastries is of no consequence because shelf life is so limited that rancidity does not occur. In cookies and crackers, however, stable fats must be used in the formula since prolonged shelf life could lead to product deterioration with fats that develop rancidity. 

Eggs. Eggs are not used much in breadmaking, except for specialty egg breads. Egg whites are occasionally used on the surface of hard roUs to impart a crispy cmst. Yeast-leavened sweet doughs or danish doughs often contain egg, up to 20%, based on flour, to achieve richness and to influence color and flavor. Some bakery foods, eg, sweet goods, croissants, and puff pastry, are often washed with egg wash (a mixture of egg and water or milk)... 

Pentahydrate is reversibly converted to an amorphous dihydrate, at 88°C and 0.26 kPa (2 mm Hg) or by boiling with xylene (73,75). The heat of dehydration for the pentahydrate to tetrahydrate has been calculated to be 53.697 kj (12.834 kcal) per mole of water (74). Thermogravimetric analyses show that 2.75 moles of water are lost on heating to 140°C. Like borax, pentahydrate puffs when heated rapidly to give a product having a bulk density of 0.042 g/mL (79). 

When the bulk containing the binder is uniform, it is compressed on pneumatic, hydraulic, or ram-type presses. Compression can be carried out in presses provided with suitably designed cavities or in metallic pans. The pans ate filled with the powder mass, and a plunger with a cross-sectional shape similar to that of the pan is used to compress the tablet. The resulting tablets ate commonly used with powder puffs or cosmetic bmshes. 

Tinted dry powders form the second type of facial makeup. Commonly, the blended soHds are compressed into compacts. The finished products, sold as compressed powders, rouges, or blushers, are appHed to the face with the aid of powder puffs, bmshes, or similar devices. Facial makeup compositions have been pubHshed for rouge (57), powder (58), and makeup (59). 

PasquiU Atmo.spheric Diffusion, Van Nostrand, 1962) recast Eq, (26-60) in terms of the dispersion coefficients and developed a number of useful solutions based on either continuous (plume) or instantaneous (puff) releases, Gifford Nuclear Safety, vol, 2, no, 4, 1961, p, 47) developed a set of correlations for the dispersion coefficients based on available data (see Table 26-29 and Figs, 26-54 to 26-57), The resulting model has become known as the Pasquill-Gifford model. 

The puff model describes near-instantaneous releases of material. The solution depends on the total quantity of material released, the atmospheric conditions, the height of the release above ground, and the distance from the release. The equation for the average concentration for this case is (Growl and Louvar, 1990, p, 143) ... 

Stability classes for puff model A, B unstable C, D neutral E, F stable... 

The center of the puff is located at x = ut. Here x is the downwind direction, y is the crosswind direction, and z is the height above ground level. The initial release occurs at a height above the ground point at x,y,z) = (0,0,0), and the center of the coordinate system remains at the center of the puff as it moves downwind. 

FIG. 26 57 Vertical dispersion coefficient for Pasqiiill-Gifford puff model. These data are based only on the data points shown and should not he considered rehahle elsewhere. (Reprinted from D. A. Cr owl and J. F. Louvar Chemical Process Safety, Fiiudanieutals with Applications, 1990, p. 140. Used hy permission of Prentice Hall. )... 

Uniform mixing in the vertical to 1000 m and uniform concentrations across each puff as it expands with the square root of travel time are assumed. A 0.01 h transformation rate from SO2 to sulfate and 0.029 and 0.007 h" dry deposition rates for SO2 and sulfate, respectively, are used. Wet deposition is dependent on the rainfall rate determined from the surface obser% ation network every 6 h, with the rate assumed to be uniform over each 6-h period. Concentrations for each cell are determined by averaging the concentrations of each time step for the cell, and deposition is determined by totaling all depositions over the period. 

Gas velocihes can also be measured with anemometers (rotating vane, hot wire, etc.), from visual observations such as the velocity of smoke puffs, or from mass balance data (knowing the fuel consumption rate, air/ fuel ratio, and stack diameter). 

The solution to the above expression assumes no diffusion along the horizontal axis (i.e., no diffusion in the downwind (x) direction). This assumption makes the model applicable to a plume, but not to a puff of pollution. 

Models toxic gas releases. Two models available SHELL SPILLS and TRPUF (based on EPA PUFF). Graphical output. Requires 512K memory and 132 column printer. 

TOXIC, PUFF, SPILLS, INPUFF, AND INPUFF 2.0 Bowman Environmental Engineering P.O. Bo 29072 Dallas, TX 75229 (214) 241-1895 In ascending order of data complexity, these systems address toxic gas releases using models designed for each type of release, based on emission rate, facility characteristics and weather data. 

The diffusion of individual plume elements, according to Gifford (1959) can be deiernnned from the general Gaussian diffusion model. The model is usually in two basic forms, a puff release - appropriate for an accident, and a continuous release for "routine" release or an accident of long duration. 

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