Estimating vessels

Van Wees, R. M. M. 1989. Explosion Hazards of Storage Vessels Estimation of Explosion Effects. TNO-Prins Maurits Laboratory Report No. PML 1989-C61. Rijswijk, The Netherlands. 

Problem A mixture of hydrogen gas and the theoretical amount of air, at 25 C and a total pressure of 1 atm., is exploded in a closed vessel. Estimate the maximum explosion temperature and pressure, assuming adiabatic conditions. In order to simplify the calculation, the mean heat capacities of nitrogen (8.3 cal. deg. " mole " ) and of water vapor (11.3 cal. deg. " mole" ), for the temperature range from 25 to 3000 C, may be used they may be regarded as independent of the (moderate) pressure. 

Figure 7. Specific feeding rate plotted against the ratio of prey to predator in the second vessel, estimated in terms of absorbance at 560 nm divided by the predator biovolume density (ptn mL ). Other conditions as in Figure 6.

Assuming that dispersion of the two phases was uniform throughout the vessel, estimate the stage efficiency to be expected for a continuous process with the rate of flow of liquids = 8,000 cu. cm./20 min., in the same proportions and the same initial concentration for (a) one vessel and (h) for two vessels in series. 

The development of analytical methods for the determination of lead concentration in environmental and biological samples has been a turning point in our understanding of the more subtle adverse health effects of lead. Early attempts to measure lead in body fluids were crude. An early study on lead poisoning in welders engaged on dismantling naval vessels estimated lead in urine by precipitation of lead as the chromate and determination of chromate content. 

I he methyl iodide is transferred quantitatively (by means of a stream of a carrier gas such as carbon dioxide) to an absorption vessel where it either reacts with alcoholic silver nitrate solution and is finally estimated gravimetrically as Agl, or it is absorbed in an acetic acid solution containing bromine. In the latter case, iodine monobromide is first formed, further oxidation yielding iodic acid, which on subsequent treatment with acid KI solution liberates iodine which is finally estimated with thiosulphate (c/. p. 501). The advantage of this latter method is that six times the original quantity of iodine is finally liberated. 

Poiseuille was a physician-physiologist interested in the flow of blood through blood vessels in the body. Estimate the viscosity of blood from the fact that blood passes through the aorta of a healthy adult at rest at a rate of about 84 cm sec , with a pressure drop of about 0.98 mmHg m". Use 9 mm as the radius of the aorta for a typical human. 

Little error is introduced using the idealized stress—strain diagram (Eig. 4a) to estimate the stresses and strains in partiady plastic cylinders since many steels used in the constmction of pressure vessels have a flat top to their stress—strain curve in the region where the plastic strain is relatively smad. However, this is not tme for large deformations, particularly if the material work hardens, when the pressure can usuady be increased above that corresponding to the codapse pressure before the cylinder bursts. 

Thermal Stresses. When the wak of a cylindrical pressure vessel is subjected to a temperature gradient, every part expands in accordance with the thermal coefficient of linear expansion of the steel. Those parts of the cylinder at a lower temperature resist the expansion of those parts at a higher temperature, so setting up thermal stresses. To estimate the transient thermal stresses which arise during start-up or shutdown of continuous processes or as a result of process intermptions, it is necessary to know the temperature across the wak thickness as a function of radius and time. Techniques for evaluating transient thermal stresses are available (59) but here only steady-state thermal stresses are considered. The steady-state thermal stresses in the radial, tangential, and axial directions at a point sufficiently far away from the ends of the cylinder for there to be no end effects are as fokows ... 

Explosion-bonded metals are produced by several manufacturers in the United States, Europe, and Japan. The chemical industry is the principal consumer of explosion-bonded metals which are used in the constmction of clad reaction vessels and heat-exchanger tube sheets for corrosion-resistant service. The primary market segments for explosion-bonded metals are for corrosion-resistant pressure vessels, tube sheets for heat exchangers, electrical transition joints, and stmctural transition joints. Total world markets for explosion-clad metals are estimated to fluctuate between 30 x 10 to 60 x 10 annually. 

A vacuum system can be constmcted that includes a solar panel, ie, a leak-tight, instmmented vessel having a hole through which a gas vacuum pump operates. An approximate steady-state base pressure is estabUshed without test parts. It is assumed that the vessel with the test parts can be pumped down to the base pressure. The chamber is said to have an altitude potential corresponding to the height from the surface of the earth where the gas concentration is estimated to have the same approximate value as the base pressure of the clean, dry, and empty vacuum vessel. 

Example 5 Entrance Loss Water, p = 1000 kg/m, flows from a large vessel through a sharp-edged entrance into a pipe at a velocity in the pipe of 2 m/s. The flow is tiirhiilent. Estimate the pressure drop from the vessel into the pipe. 

A. Pikiilik and H. E. Diaz [Chem. Eng., 84, 106-122 (Oct. 10, 1977)] presented a graphical method for estimating the fabricated cost of distillation cohimns and pressnre vessels, storage tanks, fired heaters, pnmps and drivers, compressors and drivers, and vacnnm eqnipment. 

Contrac tors bids offer the most rehable information on cost. Order-of-magnitude costs, however, may be required for preliminary studies. One way of estimating them is to obtain cost information from similar facihties and scale it to the proposed installation. Costs of steel storage tanks and vessels have been found to vaiy approximately as the 0.6 to 0.7 power of their weight [see Happel, Chemical Process Economics, Wiley, 1958, p. 267 also Williams, Chem. Eng., 54(12), 124 (1947)]. AU estimates cased on the costs of existing eqiiipment must be corrected for changes in the price index from the date when the equipment was built. Considerable uncertainty is involved in adjusting data more than a few years old. 

The performances and estimating methods of welded PHEs match those of gasketed PHEs in most cases, but normally the Compabloc, with larger depth of corrugations, can be lower in overall coefficient. Some extensions of the design operating conditions are possible with welded PHEs, most notably is that ciyogenic applications are possible. Pressure vessel code acceptance is available on most units. 

Cost of Column The cost of the vessel, including heads, sldrt, nozzles, and ladderways, is usually estimated on the basis of weight. 

The power for agitation of two-phase mixtures in vessels such as these is given by the cuiwes in Fig. 15-23. At low levels of power input, the dispersed phase holdup in the vessel ((j)/ ) can be less than the value in the feed (( )df) it will approach the value in the feed as the agitation is increased. Treybal Mass Transfer Operations, 3d ed., McGraw-HiU, New York, 1980) gives the following correlations for estimation of the dispersed phase holdup based on power and physical properties for disc flat-blade turbines ... 

A further use of the Jenike method is its extension to the critical structural design of storage vessels. Because pressures can be calculated, it is possible to design for actual conditions rather than estimates. Also, flow-corrective devices may be designed by using his theoiy. 

Blast Characteristics Accurate calculation of the magnitude of the blast wave from an exploding pressure vessel is not possible, but it may be estimated from several approximate methods that are available. 

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