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Relief areas Sizing

When a runaway reaction occurs within a reactor vessel, two-phase flow should be expected during the relief process. The vent sizing package (VSP) laboratory apparatus described in chapter 8 provides the much needed temperature and pressure rise data for relief area sizing. [Pg.395]

The effects of turbulence must be taken into account when sizing a relief area. For example, the explosion violence of turbulent methane-air mixture is comparable to that of zero turbulence of hydrogen-air mi.xtures. From the investigations [54], the nomograms from Figure 7-63 can be applied for turbulent gas mixtures under the following conditions [54] ... [Pg.512]

Effects of performance changes, 201-203 Head curve for single pump, 198 Relations between head, horsepower, capacity and speed, 200 Temperature rise 207-209 Viscosity corrections, 203-207 Purging, flare stack systems, 535 Reciprocating pumps, 215—219 Flow patterns, 219 Specification form, 219 Relief areas, 437 External fires, 451, 453 Sizing, 434, 436... [Pg.629]

W. J. Boyle Jr., Sizing Relief Area for Polymerization Reactors, Chemical Engineering Progress (August 1967), 63(8) 61. [Pg.402]

As mentioned previously, two-phase flow discharges for fire scenarios are possible but not likely. To size the relief for fire and a single-vapor phase, use the heat input determined from Equations 9-36 to 9-38, and determine the vapor mass flow rate through the relief by dividing the heat input by the heat of vaporization of the liquid. This assumes that all the heat input from the fire is used to vaporize the liquid. The relief area is then determined using Equations 9-3 to 9-12. [Pg.415]

Boyle, W. J., "Sizing Relief Area for Polymerization Reactors," CEP Technical Manual, Loss Prevention, 1,78 (1967), American Institute of Chemical Engineers, New York, NY. [Pg.196]

In the catalyst preparation area where the fire occurred, aluminum alkyl and isopentane are mixed in a batch blending operation in three 8000-gallon kettles. The flow rates of components are regulated by an operator at the control room. Temperature, pressure, and liquid level within the kettles are monitored by the control room operator. The formulated catalyst is stored in four 12,000-gallon vertical storage tanks within this process unit. Aluminum alkyl is a pyrophoric material and isopentane is extremely flammable. Each vessel was insulated and equipped with a relief valve sized for external fire. [Pg.369]

In most cases, a two-phase (vapour/ liquid or gas/ liquid) mixture is vented from a reactor emergency relief system. The relief system required for a two-phase mixture is very often larger (by, in some cases, several times the flow area) than for gas or vapour alone. It is therefore essential to take account of two-phase relief to size a relief system properly. J ... [Pg.2]

Most of the relief sizing equations given in Chapters 6-8 yield the two-phase required relief rate, W. The two-phase mass flow capacity per unit area, G, is then needed in order to obtain the required relief area. Chapter 9 contains important background information about two-phase flow, and calculation methods for G. Some system types are special cases involving highly viscous (laminar) flow, solids and/or... [Pg.5]

The logic given in Figure 5.1 can be used to check that this section is the correct one for relief system sizing for any particular case. As explained in Chapter 5, the required relief rate, W, should first be calculated using the methods described in this Chapter. A two-phase mass flow capacity per unit area, G, should then be calculated using the methods described in Chapter 9 (or Chapter 10 in special cases). The required relief flow area can then be calculated using equation (5.1). [Pg.39]

Calculate relief area using alternative sizing method (see 6.4 and Annex 5 )... [Pg.40]

Is there reason to believe that an alternative sizing ( method would yield a lower relief area (see 6.4)... [Pg.40]

The flow rate used for this calculation should be the best estimate flow rate for the safety valve. BS 6759 19] requires that any safety factors used in determining G for relief system sizing, including the 10% de-rating of the safety valye discharge coefficient, should be removed. The actual flow area through the valve should be used., ... [Pg.94]

A growing number of computer codes are available for relief system sizing or for the evaluation of the flow capacity (and hence the mass relief capacity per unit area, G) for a given relief system. The types of code available are discussed below under the following headings ... [Pg.153]

In order to use the sizing method, the reactor, void fraction, aD, at which total vapour/ liquid disengagement is expected at the maximum accumulated pressure, must first be evaluated. This may be done by level swell calculation (see Annex 3) or by small-scale experiment with the same vapour superficial velocity as will occur at plant-scale (see Annex 2). Equation (A5.7)can then be used to find the relief area ... [Pg.168]

This is a little more than the temperature of 411 at the maximum accumulated pressure of 2.6 bara. Thus the tguessed relief size of 0.04 m2 is slightly too small. The calculation needs to be repeated with a slightly larger estimate of the relief area. For this example, the simplified method provided in A5.7 gives a very similar result to this more rigorous method. [Pg.180]

This suggests that, provided the reactor fills with a homogeneous two-phase mixture (inherently foamy fluid behaviour), the relief system size can be greatly reduced from the area of 0.0136 m2 calculated using the DIERS method (neglecting, mass loss during relief) given in Chapter 7.. ... [Pg.182]

This shows that the required relief area has been reduced from the value of 0.0136 m2 calculated, with no account taken for mass loss, in 7.6. This method gives less reduction in relief size than is given by Singh s method (see A5.9.2 above). The two methods give closer agreement when the initial void fraction is higher than in this example. [Pg.183]

Relief sizing for single-phase relief can be done assuming steady-state, i.e. the gas/ vapour needs to be removed by the pressure relief system at the rate at which it is generated by the reaction. A required relief rate, Wg, can be specified, and the relief system can be sized to give a capacity which exceeds it. If the capacity is expressed as mass capacity per unit flow area, Gg, then the required relief area can be obtained from ... [Pg.191]

The minimum required relieving area (in2) can now be calculated using the following equation for gas and vapour relief valve sizing (lbs/h) ... [Pg.25]

Figure 5. 3D model of gamma-fields of bottom sediments and bottom relief in NS K-159 sinking area (area size 2.5-2.5 km, the submarine is located between the points indicated at the upper projection... [Pg.156]

The relief valve selected should be one with equal or greater area than calculated using equation 13.105. Relief valve sizes are given in API Standard 526. Sizing equations for subcritical flow of vapors, liquids, steam, and two-phase mixtures are given in API RP 520. [Pg.1048]

The required orifice area for a relief valve sizing for air at constant back pressure is ... [Pg.352]

Boyle [15] and Huff [16] first accounted for two-phase flow with relief system design for runaway chemical reactions. A computer simulation approach to vent sizing involves extensive thermokinetic and thermophysical characterization of the reaction system. Fisher [17] has provided an excellent review of emergency relief system design involving runaway reactions in reactors and vessels. Fauske [18] has developed a simplified chart to the two-phase calculation. He expressed the relief area as ... [Pg.366]

Many emergency relief vents are therefore connected to a disposal system which may include knock-out dmms. quench tanks, flare stacks and scrubbers. The size and capacity of such systems needs to be checked once the relief area has been calculated, particularly where a new reaction is being sited in an existing reactor unit. In addition, consideration has to be given to the possibility of the reaction continuing in the disposal system. [Pg.121]

VILl.l Vapor pressure relief device sizing at sonic flow Calculate required PRV oriflce area or rupture disk area by follow equation ... [Pg.155]


See other pages where Relief areas Sizing is mentioned: [Pg.876]    [Pg.973]    [Pg.1020]    [Pg.542]    [Pg.642]    [Pg.643]    [Pg.542]    [Pg.17]    [Pg.41]    [Pg.80]    [Pg.94]    [Pg.187]    [Pg.973]    [Pg.1020]    [Pg.375]    [Pg.383]    [Pg.389]    [Pg.702]    [Pg.876]    [Pg.224]    [Pg.2291]   
See also in sourсe #XX -- [ Pg.434 , Pg.436 ]




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