Combustible gases vapor pressure

The potential hazard of vapor cloud explosions following the leakage of combustible gas under pressure has been studied in experiments with turbulent jet release of propane, natural gas and hydrogen through orifices of different size. 

Observable Characteristics - Physical State (as normally shipped) Liquid Color Clear Odor. None. Physical and Chemical Properties - Physical State at 15 X and 1 atm. Liquid Molecular Weight 71 (solute only) Boiling Point at 1 atm. Data not available (Vapor Pressure 0.033 atm at 125 °C Freezing Point 183, 84, 357 Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.05 at 25 °C Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Lateru Heat of Vaporization Not pertinent Heat of Combustion Not pertinent Heat of Decomposition Not pertinent. 

Compressed air lines are very susceptible to a combustion gciienition e.xplosion, fueled by oil or cliar on tlie pipe walls. E.xplosions in pipelines c ui cause considerable damage. Pipelines witliin wliich gas, vapor, or dust explosions can occur must be designed to have sufficient mechanical streiigtli to withstand pressure or stress beyond tliat required by the application. 

The key point here is to determine if flammable or combustible materials are being processed under conditions of temperature and pressure such that, if a release occurs, a significant quantity of the material may be released into the air as either a gas, vapor, mist, or aerosol. If such conditions are present, the user should assume that the potential for a vapor cloud explosion exists. Otherwise, VCE hazards can be ignored. 

Thus, the technique can become counterproductive. A typical arrangement for selective non-catalytic reduction is shown in Figure 25.30. Aqueous ammonia is vaporized and mixed with a carrier gas (low-pressure steam or compressed air) and injected into nozzles located in the combustion device for optimum temperature and residence time10. NO, reduction of up to 75% can be achieved. However, slippage of excess ammonia must be controlled carefully. 

Fire prevention may include providing degassing boots/vent stacks to the top of risers where flammable combustible vapors can be entrained in the water system, i.e. water pressure lower than process pressure. Combustible gas detection at the top ofthe vent stacks can be used to detect flammable material presence in cooling tower. However, the hostile environment and difficult to access location makes the detection challenging to maintain. 

Reid vapor pressure is measured at 100°F (37.8°C) and is used to help ensure that gasoline will vaporize adequately and ignite within the combustion chamber of an engine. Vapor pressure is provided by volatile gasoline components such as dissolved butane gas and the presence of pentanes, hexanes, heptanes, and benzene. 

Husain and co-workers, for example (Husain, 1989 Husain et al., 1991 Husain and Dutkiewicz, 1992 Burkhard et al., 1995 Dutkiewicz et al., 1995), have developed techniques using Se, As, and Sb as tracers to follow the oxidation of S02 with time in clouds at Whiteface Mountain in New York State. The principle is based on the fact that the major sources of these metals are high-temperature combustion, e.g., of coal and oil. Thus these metals are found in particles (see Chapter 9) that act as condensation nuclei for cloud formation. These particles also contain sulfate formed from the gas-phase oxidation of S02. Because of the low vapor pressure of H2S04, it becomes associated with particles, either by homogeneous condensation or by condensing out on preexisting particles (see Chapter 9.C). As a result, the metals can be used as tracers for sulfate formed in the gas phase, as opposed to sulfate formed by the uptake of S02 into cloudwater followed by oxidation. 

Gas A state of matter defined as a fluid with a vapor pressure exceeding 40 psia at 100° F. Gasolines Mixture of volatile, flammable liquid hydrocarbons used in internal combustion engines. Typical flash point temperature is around -40 °C. 

Glass-Combustion Gas System. Certain combustion gas components can promote alkali vapor transport in glass systems. Such transport is important in glass melting. Also, glass had heen suggested as a medium for trapping particulate material in combustion gas clean-up processes, such as for pressurized fluidized bed combustion ( ). ... 

Using our experimental activity data for Na20 in glass, we have modeled the effect of a typical combustion gas mixture on alkali vaporization ( ). For this purpose we have acquired, and adapted to our computers, a code known as SOLGASMIX (7 ) which is unique in its ability to deal with non-ideal solution multicomponent heterogeneous equilibria. Previous attempts to model this type of problem have been limited to ideal solution assumptions ( ). As is demonstrated in Table III, if solution non-ideality is neglected, drastic errors result in the prediction of alkali vapor transport processes. Table III and Figure 21 summarize the predicted alkali species partial pressures. The thermodynamic data base was constructed mainly from the JANAF (36) compilation. Additional details of this study will be presented elsewhere. 

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