Vessel design pressure and temperature

Process flow diagrams are more complex and show all main flow streams including valves to enhance the understanding of the process as well as pressures and temperatures on all feed and product lines within all major vessels and in and out of headers and heat exchangers, and points of pressure and temperature control. Also, information on construction materials, pump capacities and pressure heads, compressor horsepower, and vessel design pressures and temperatures are shown when necessary for clarity. In addition, process flow diagrams usually show major components of control loops along with key utilities. 

The reactor is a PWR type with forced circulation through the primary circuit. Reactor vessel design pressure and temperature are 16.2 MPa and 350°C respectively. The reactor vessel is made of thermal resistant, high strength feritic steel with corrosion-resistant cladding. The reactor vessel is 3.89 meters high and 2.22 m in diameter. 

The factors Uiat enter into tlie design of vessels include type of material, configuration, inetliod of construction, design stresses, and tliickness of Uie metal. As with any equipment, design pressures and temperatures should take into consideration Uie most severe combination of conditions anticipated. Vessels must be completely drainable. Liners and wear plates may be required to prevent corrosion. 

As with double-wall containment systems, a transfer vessel s construction materials, design pressure, and temperature rating should at least equal those of the equipment being protected. Construction materials can differ if the transfer vessel will only be exposed to the corrosive process for an acceptably short duration. 

Confirm relief protection philosophy, select location of major relief valves, and determine vessel and exchanger design pressure and temperatures. 

Mechanical Design of Process Vessels 621 Design Pressure and Temperature 623 Shells and Heads 624... 

A code provides only a basic framework of minimum acceptable practices with which compliance is necessary to obtain a vessel that is structurally safe at the design pressure and temperature. It is not a designer s handbook. The perfect code would be one which provides an optimum balance between a minimum number of mandatory requirements and maximum latitude within which the designer may exercise his technological expertise and good engineering judgment. A specification, on the other hand, is a consolidation of requirements drawn from applicable codes and standards. 

SEDS (solution-enhanced dispersion by supercritical fluids) The second modification of the gas antisolvent process known as solution-enhanced dispersion by SCFs was developed by the Bradford Universityt in order to achieve smaller droplet size and intense mixing of SCF and solution for increased transfer rates. Indeed the SCF is used both for its chemical properties and as spray enhancer by mechanical effect a nozzle with two coaxial passages allows the introduction of the SCF and a solution of active substance(s) into the particle-formation vessel where pressure and temperature are controlled (Figure 8.5). The high velocity of the SCF allows breaking up the solution into very small droplets. Moreover, the conditions are set up so that the SCF can extract the solvent from the solution at the same time as it meets and disperses the solution. Similarly, a variant was recently disclosed by the University of Kansas, where the nozzle design leads to development of sonic waves leading to very tiny particles, around 1 /rm. 

Design Pressure and Temperature The design pressure is the pressure used to determine the physical characteristics of the different components of the vessel. It usually is the sum of the maximum allowable pressure and the static head of the fluid in the vessel. The design temperature is the metal temperature coincident with the design pressure. 

These dimensions would allow the vessel to be fabricated from a piece of available steel pipe (or tubing), and so be relatively inexpensive. Recall that piping is sized by external diameter tubing is sized by internal diameter (Chapter 2, Endnote FF). Wall thickness of each is identified by a "schedule number." Since the adsorber bed does not have to be an ASME code pressure vessel (because the design pressure and temperature are very low), the wall thickness (calculated by Equations 2.3 and 2.4) can be quite thin. Also, code welding of end caps is not required (Chapter 2, Endnotes V and W). Pipe of the appropriate diameter and any schedule number can be used. Matching the exact numerical value of LTD noted above is not required. 

For flanges of nonstandard dimensions or for sizes beyond the scope of the approved standards, design shall be in accordance with the requirements of the ASME Boiler and Pressure Vessel Code, Sec. T11, except that requirements for fabrication, assembly, inspection testing, and the pressure and temperature hmits for materials of the Piping Code are to prevail. Countermoment flanges of flat face or otherwise providing a reaction outside the bolt circle are permitted if... 

The set burst pressure should be selected to permit a sufficiently wide margin between it and the vessel s used or design operating pressure and temperature to avoid premature failure due to fatigue or creep of metal or plastic coatings. 

For a new installation, establish pressure vessel normal maximum operating pressure, and temperature, and then the safe increment above this for vessel design conditions and determine the maximum allowable working pressure (MAWP) of the new vessel. (Have qualified fabricator or designer establish this. See pretious discussion of topic.)... 

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