Vapor evolution

A condensible blowdown tank, designed on a similar basis to that described above for phenol, may be provided in other services where a conventional condensible blowdown drum would not be acceptable (e.g., due to effluent water pollution considerations). Examples of such cases are methyl ethyl ketone (MEK) and dimethyl formamide (DMF). A suitable absorbing material is specified (e.g., a lube oil stock for MEK water for DMF), and the design must include consideration of maximum permissible operating temperatures to prevent excessive vapor evolution or the boiling of water. 

Rupture disk released combustible vapors from reactor after it overpressured due to cleaning vapor evolution from residual heat in the vessel. Vapors ignited causing an explosion which severely damaged the facilities. 23,000,000... 

Unexpected Process Chemical Reactions Unexpected chemical reactions which result in heat or vapor evolutions may produce overpressures that have not been planned for. 

Drying Rates. Drying a frozen material proceeds initially at a constant rate with rapid evolution of water vapor. As Ihe sublimation interface recedes within the product, water-vapor evolution decreases. This is the start of the falling-rate period. When only bound water remains within the cellular structure of the product, the desorption period begins. During the constant-rate period, the sublimation rate can be expressed in terms of the heat of sublimation of ice and the heat-rale equation ... 

Reactions. When a hazardous material reacts with another substance, either it will become neutralized, or it will form a compound that is less volatile and ideally harmless. For example, reacting a spilled volatile acid with limestone placed around a storage tank or in a collecting sump will neutralize the acid and form a calcium salt. The neutralization reaction will generate heat that could just increase temperature or cause a short increase in vapor evolution. 

Moorhouse, J and R. J. Carpenter. 1986, Factors Affecting Vapor Evolution Rates from Liquefied Gas Spills. British Gas Corporation, Midlands Research Station. 

None cold vapor evolution, absorbance cell used. 

Piccoli PM, Candela PA (1988) Trends in apatite chemistry from El Chichon implications for vapor evolution. Geol Soc Am Arm Meet, Progr Abstr 20 194-195... 

Valves are often used to reduce the pressure of a gas or liquid process stream. By replacing the valve with a turbine, called an expander, turboexpander, or expansion turbine in the case of a gas and a liquid expander or radial-infiow, power-recovery turbine in the case of a liquid, power can be recovered for use elsewhere. Power recovery from gases is far more common than from liquids because for a given change in pressure and mass flow rate, far more power can be recovered from a gas than from a liquid because of the lower density of the gas. Equations for f.o.b. purchase costs of power recovery devices are included in Table 16.32 in terms of horsepower that can be extracted. Typical efficiencies are 75-85% for gases and 50-60% for liquids. Condensation of gases in expanders up to 20% can be tolerated, but vapor evolution from liquid expansion requires a special design. Whenever more than 100 Hp for a gas and more than 150 Hp for a liquid can be extracted, a power recovery device should be considered. 

The average pool temperature, radius, and vapor evolution rates in the three regimes... 

The cloud behavior is affected mostly by the wind speed, the vapor evolution rates from the pool, the atmospheric stability class, and the atmospheric relative humidity (Kapias, 1999 Kapias and Griffiths, 1999a). In the majority of the cases, the cloud will initially be denser... 

In Figs. 37.8 and 37.9, the dangerous toxic load (DTL) concentration, equal to around 147 mg m for a period of 10 minutes, and the ERPG-3 (for exposures up to 60 minutes), equal to 30 mg m , are also shown for comparison. The exposure duration for calculating the DTL concentration was chosen equal to the spreading period of about 10 minutes because it is the period of main exposure (higher vapor evolution rates). 

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