Criteria in Vessel Design

Stresses resulting from bending and torsion an more complex, and a large number of texts have lK en written on the subject of the evaluation of such stresses (2 ). 30. 31, 32). 

typical ifreti-ftrain curvas for voriout metalt. 

I ypicai. Hj. resH-straia cur ves for few selected nn l,erials are. shciwn in Fif . 2. . (Note that two scales are um l on the abscissa in order to enlarge the elastic region of the curves.) 

Consider an tieii. dx, of a t uin having a uniform cros section, supporl ing a distributed load of w pounds per inch of length of the beam as indicated in Fig. 2.2. The total lofid acting on the element is w (dx). If uf is considered positive when the load acts downward and if dx is positive, the differential shear force, dV, must be negative. By summation of vertical forces Vz — V w dx) == 0, or 

Taking a. summation of bending moments about pt int A gives  

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In Effects of Motion on Design of Process Facilities for Floating Systems" Rice provides a theoretical analysis coupled with motion-simulation work in an effort to understand fluid motion inside process equipment on floating vessels. This work has led to the establishment of process-equipment sizing criteria for all types of vessel motion transmitted from the marine vessel. Design of internal baffling and other internals to dampen and control the fluid motion is reviewed. 

With these criteria in mind, various reactors have been designed to satisfy the needs of the hydroprocesses, including hydrodesulfurization (McEvoy, 1996). Thus, reactors may vary from as little as 4 ft. in diameter to as much as 20 ft. in diameter and have a wall thickness anywhere from 4.5 to 10 in. or so. These vessels may weigh from 150 tons to as much as 1000 tons. Obviously, before selecting a suitable reactor, shipping and handling requirements (in addition to the more conventional process economics) must be given serious consideration. 

From the customer point of view, the criteria for the design of a pressure vessel are determined in terms of costs (initial and subsequent) and output of a product (quantity and quality). While the initial cost of a pressure vessel is simply the price for purchasing and installation, subsequent costs are far more difficult to judge, because they depend on life time expectancy, reliability in service and effort for maintenance. 

These needs are defined by three criteria. All are employed in the design of the adsorber vessel, and are that the vessel (1) has adequate capacity for internal transfer of heat from the adsorbent to the moving air , (2) holds up the moving air stream for an adequate time to allow for adsorption to be complete, and (3) contains a sufficient quantity of activated carbon to provide service forwhatever long-term period is desired. 

Modjeski and Masters. 1984. Criteria for The Design of Bridge Piers with Respect to Vessel Collision in Louisiana Waterways , Report preparedfor Louisiana Department of Transportation and Development and the Federal Highway Administration, Mechanicsburg, PA. 

It is recommended that pilot testing be used in developing design criteria for the site-specific conditions and MF/UF product selection. Both pressure-type MF/UF systems, where the membranes are encased in pressiue vessels, and vacuum-type systems, where the membrane are immersed in tanks open to atmosphere and use fUtrate/permeate pumps to create the driving force, may be used for seawater pretreatment. 

Codes Standards approved the estabUshment of a Special Working Group for high pressure vessels under the ASME Subcommittee on Pressure Vessels (Section VIII). The main design criteria, which are likely to be incorporated in a new Division of Section VIII, have been set out (149). 

Depending upon the design criteria of the installed suppression system, an unsuppressed explosion overpressure of around 7 to 10 bar is reduced to a suppressed reduced explosion overpressure which lies in the range of Fred,max = 0-2 to 1 bar. Thus, vessels need to be explosion resistant for an overpressure of maximum 1 bar (ISO Standard 6184/4, Explosion Protection Systems Paii 4 Determination of Efficacy of Explosion Suppression Systems, Geneva, 1985). 

In some cases, it is possible to combine the functions of blowdown and disengaging drums in one vessel. However, PR devices discharging liquid hydrocarbons lighter than pentane should not be connected into the drum if there is a possibility that such liquids could accumulate and be released to the sewer through the seal leg. Also, the drum vent should be sized to prevent pressure buildup due to vaporization. In these applications, the design criteria for both services must be met and special attention should be paid to potential hazards and problems which may be introduced, such as ... 

Figure 8 is a schematic flow diagram for the hydrolysis of waste newsprint. Most of the process design criteria and the economic evaluations of the saccharification process have been based on newsprint as substrate. Notable analyses are those of Wilke and co-workers (21) and Humphrey (22). In the hydrolysis, the substrate is first pretreated (milling), to make it more accessible to the enzyme. Saccharification takes place in a reaction vessel, where the substrate is contacted with the enzyme solution from the fermentation vessel. Glucose solution is separated from unreacted substrate at the outlet of the vessel and the solution passes on to a concentration stage before the sugar is used in the yeast fermentation to produce alcohol. 

As a result, three secondary design criteria were developed that the vessel he built and installed quickly, that it be reasonably priced, and that it be durable in the... 

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