Liquefied gases boiling point

The procedure applies to stabilized, i.e., debutanized, crudes, but can be applied to any petroleum mixture with the exception of liquefied petroleum gas, very light naphtha, and those fractions having boiling points over 400°C. 

Chlorine has a boiling point of 238 K and is a greenish-yellow diatomic gas at room temperature. It can be liquefied by cooling or by a pressure of a few atmospheres at room temperature. 

The liquefied gas must be maintained at or below its boiling point. Refrigeration can be used, but the usual practice is to cool by evaporation. The quantity of liquid evaporated is minimized by insulation. The vapor may be vented to the atmosphere (wasteful), it may be compressed and reliquefied, or it may be used. 

A liquefied gas or any mixture of liquefied gases, which is flammable in air and has a boiling point <0°C (measured at 1 bar absolute), when held under refrigeration or cooling at a pressure <1.4 bar absolute. 

This will generally be tr-ue as we proceed to look at other alkanes as the number of carbon atoms increases, so does the boiling point. All the alkanes with four car bons or less are gases at room temperature and atmospheric pressure. With the highest boiling point of the three, propane is the easiest one to liquefy. We are all faniliar- with propane tanks. These are steel containers in which a propane-rich mixture of hydrocar bons called liquefied petroleum gas (LEG) is maintained in a liquid state under high pressure as a convenient clean-burning fuel. 

To remain a liquid at a reasonably low pressure, liquefied natural gas (LNG) must be maintained at below at least -117°F. Insulated storage tanks alone cannot maintain these very cold temperatures. LNG is stored at its boiling point to take advantage of autorefrigeration. Just as the temperature of water does not rise above its boiling point (212°F) with increased heat (it is cooled by evaporation), LNG is kept near its boiling point if kept at a constant pres-... 

Helium is a monatomic gas and, as yet, no stable compounds of helium have been found. The attractive forces between the atoms of helium are unusually weak, as shown by the normal boiling point. To liquefy helium, it must be cooled to — 268.9°C or 4.2°K. No other element or compound has a boiling point as low. Helium has another distinction which reflects these weak forces it is the only substance known which cannot be solidified at any temperature unless it is subjected to pressure. Helium becomes solid at 1.1 °K at a pressure of 26 atmospheres. 

In the graph above, we see that for the real gas B, the volume drops to nearly zero at about 50°C. This is because the gas must have liquefied at that temperature, i.e., its boiling point must be about 50°C. Since liquids are much more dense than gases, the volume would have decreased greatly at that temperature. 

A further aspect of volatility that receives considerable attention is the vapor pressure of petroleum and its constituent fractions. The vapor pressure is the force exerted on the walls of a closed container by the vaporized portion of a liquid. Conversely, it is the force that must be exerted on the liquid to prevent it from vaporizing further (ASTM D323). The vapor pressure increases with temperature for any given gasoline, liquefied pefioleum gas, or other product. The temperature at which the vapor pressure of a liquid, either a pure compound or a mixture of many compounds, equals 1 atm pressure (14.7 psi, absolute) is designated as the boiling point of the liquid. 

Colorless gas when pure often appears bluish because of impurities density 2.176 g/L liquefies at -56°C density of hquid 1.326g/mL at its boiling point solidifies at -134°C density of sobd 1.719 g/cm reacts with water. 

Dinitrogen tetroxide is available from suppliers of reagent gases. It is a poisonous gas and should only be handled in a well-ventilated hood. Since its boiling point is 21°C, the cylinder in which the material is supplied may be cooled to 0°C and the cold liquefied dinitrogen tetroxide may be poured into the desired cold solvent. Usually the solvent is kept at — 20°C. The density of dinitrogen tetroxide at 0°C is 1.5 gm/ml [45],... 

Cryogenic Liquid A cryogenic liquid is a refrigerated liquefied gas having a boiling point colder than -130 °F at one atmosphere, absolute. A material that meets this definition is subject to the same requirements tor compressed gases widrout regard to whether it meets the standard definition of a compressed gas. 

Gas fraction, boiling point up to 40°, contains normal and branched alkanes from Cj to C5. Natural gas is mainly methane and ethane. Bottled gas (liquefied petroleum gas) is mainly propane and butane. 

The simplest method of liquefying a gas is to immerse a sample in a bath kept at a temperature lower than the boiling point of the substance (Fig. 4.31). Temperatures as low as about 196 K (—77°C) can be reached by adding chips of solid carbon dioxide to a low-freezing-point liquid, such as acetone. 

The ideal gas law is valid only for ideal gases. All gases can be liquefied at sufficiently high pressure and low temperature and gases become nonideal as they approach liquefaction. However, almost all gases behave nearly ideally at temperatures significantly above their boiling points and at pressures of a few atmospheres or less. 

Propane (CH3CH2CH3, melting point -189.7°C, boiling point -42.1°C, density 0.5853) is also a constituent of liquefied petroleum gas along with butane (CH3CH2CH2CH3), and propane can be used for the manufacture of aromatics by reforming (Fig. 1). 

Hydrogen chloride is a colourless and poisonous gas with an acid taste and fuming in air. It is relatively stable. Thermal decomposition sets only above 1700 °C. Its critical temperature is 51.3 °C, its critical pressure fequals 81.6 atm. for this reason it liquefies easily (e. g. at 10 °C under 40 atm., at 0°C under 26.2 atm.). Under a pressure of 1 atm., the boiling point of liquid hydrogen chloride is — 83 °C and the freezing point — 111 °C. 

---