Vapor release rate

The vapor mass flow rate is proportional to the heat release rate and can be calculated in a similar way, as explained in Section 9.4.2  

The vapor mass flow rate can be converted to a volume flow rate by using the vapor density calculated (Equation 10.10), which calculates the vapor velocity in the equipment using the section of the vapor tube  

The assessment of the equipment vapor flow capacity should also take the cooling capacity of the condenser into account. This can be directly compared to the heat release rate. Further, the swelling of the reaction mass, due to the presence of bubbles, may also become critical for high degrees of filling (see Section 9.4.4). When both vapor and gas are released, obviously the sum of both velocities must be used in the assessment. 

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FIG. 26-31 Estimated maximum downwind distance to lower flammable limit L, percent by volume at ground level in centerline of vapor cloud, vs. continuous dense vapor release rate at ground level. E atmospheric stability. Level terrain. Momentary concentrations for L. Moles are gram moles u is wind speed. (From Bodmtha, 1980, p. 105, by permission.)... 

All heat absorption from fire exposure is considered as latent heat and no credit is taken for the sensible heat capacity of the fluid in the vessel. The vapor release rate W is calculated from ... 

This is the continuation of Worked Example 3.1. If there is loss of control of an amination reaction, the temperature could reach 323 °C (MTSR), but the maximum allowed working pressure of 100 bar g would be reached at 249 °C (MTT). Thus, the question is If the reaction can be controlled by depressurizing the reactor before the safety valve opens, that is, before 240 °C is reached, what would the vapor release rate be To answer this question, information about the reaction kinetics is required. The only information is that at 180°C, a conversion of 90% is reached after 8 hours. If we consider the reaction to follow a first-order rate equation, justified by the fact that ammonia is in large excess, we can calculate the rate constant at 180 °C ... 

Modify the process to reduce the consequences of a release for example, use refrigerated rather than pressurized storage, which results in higher liquid release and lower vapor release rates (from the same hole size) and lower vapor generation rates from a pool dilute hazardous materials with inert or less hazardous material to reduce partial pressure or reduce operating pressures to reduce release rates. 

One steam curtain described in the literature (Guidelines for Vapor Release Mitigation, CCPS, 1988), is a 6-in. diameter pipe with a row of %2-in. holes spaced at 4-in. intervals. Steam was supplied to this curtain at 250 psig. It was effective in reducing concentrations by a factor of 30 when the steam flow rate was equal to the vapor release rate. 

Mitra et al. (1998) employed NSGA (Srinivas and Deb, 1994) to optimize the operation of an industrial nylon 6 semibatch reactor. The two objectives considered in this study were the minimization of the total reaction time and the concentration of the undesirable cyclic dimer in the polymer produced. The problem involves two equality constraints one to ensure a desired degree of polymerization in the product and the other, to ensure a desired value of the monomer conversion. The former was handled using a penalty function approach whereas the latter was used as a stopping criterion for the integration of the model equations. The decision variables were the vapor release rate history from the semibatch reactor and the jacket fluid temperature. It is important to note that the former variable is a function of time. Therefore, to encode it properly as a sequence of variables, the continuous rate history was discretized into several equally-spaced time points, with the first of these selected randomly between the two (original) bounds, and the rest selected randomly over smaller bounds around the previous generated value (so as... 

For alternative evaluations, the weight of flammable material in a vapor cloud can be calculated as the gas-release or vapor-release rate multiplied by the estimated time required to stop the release. For liquid releases, the vapor-release rate would be calculated from the liquid-release rate multiphed by twice the flashing fraction (to account for aerosol vaporization) or, for hquids released below the boiling point, as the rate of vaporization from a pool multiplied by the estimated time required to cover or dilute the pool. Also, a lower energy-conversion efficiency (such as 0.03) can be used in the calculation. 

Based on prior meteorological data, a transition from neutral to stable conditions could be anticipated during the period from just before until just after sunset at the Frenchman Flat site. This series of four CO2 vapor and tracer amounts of SFground level low-momentum source. 

If the diameter of the vapor tube is insuffident for a given vapor release rate, the... 

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