Liquefied petroleum gases properties

The first step in a gas processing plant is to separate the components that are to be recovered from the gas into an NGL stream. It may then be desirable to fractionate the NGL stream into various liquefied petroleum gas (LPG) components of ethane, propane, iso-butane, or normal-butane. The LPG products are defined by their vapor pressure and must meet certain criteria as shown in Table 9-1. The unfractionated natural gas liquids product (NGL) is defined by the properties in Table 9-2. NGL is made up principally of pentanes and heavier hydrocarbons although it may contain some butanes and very small amounts of propane. It cannot contain heavy components that boil at more than 375°F. 

The term liquefied petroleum gas (LPG) is often used to describe those liquefied flammable gases that are derived from petroleum. The term LFG is preferred when the discussion applies to all liquefied flammable gases. It includes materials such as ethylene oxide, vinyl chloride, and methylamines, which behave similarly so far as their flashing and flammable properties are concerned. 

At 6 30 A.M. on June 21, 1970, fifteen railroad cars, including nine cars carrying liquefied petroleum gas (LPG), derailed in the town of Crescent City, Illinois. The derailment caused one of the tanks to be punctured, then release LPG. The ensuing fire, fed by operating safety valves on other cars, resulted in ruptures of tank cars, followed by projectiles and fireballs. No fatalities occurred, but 66 people were injured. There was extensive property damage. 

Liquefied gases. See also Liquefaction Cryogens and individual chemicals Liquefied Natural Gas (LNG), 263 physical properties, 295 precautions, 264, 292 vapour pressure, 294 Liquefied Petroleum Gas (LPG), 15, 287 hazards, 287 physical properties, 289 precautions, 292... 

Bulk physical property tests, such as density and heating value, as well as some compositional tests, such as the Orsat analysis and the mercuric nitrate method for the determination of unsaturation, are still used. However, the choice of a particular test is dictated by (1) the requirements of the legislation, (2) the properties of the gas under study, and (3) the selection by the analyst of a suitable suite of tests to meet the various requirements. For example, judgment by the analyst is necessary whether or not a test that is applied to liquefied petroleum gas is suitable for process gas or natural gas insofar as inference from the nonhydrocarbon constituents will be minimal. 

Extensive laboratory-scale studies have been conducted to investigate the triggering mechanism for RPTs when LNG, liquefied petroleum gas (LPG), and liquid refrigerants contact a hot liquid (usually water). These studies are covered in Sections III and VII. The evidence seems overwhelming that RPTs in these cases result from superheating of the cold, volatile liquid to its superheat-limit temperature where prompt homogeneous nucleation occurs in a time period of a few microseconds. (The properties of a superheated liquid and the concept of homogeneous nucleation are reviewed briefly in Section IX.)... 

Demirbas, A. 2002. Enel properties of hydrogen, liquefied petroleum gas (LPG), and compressed natural gas (CNG) for transportation. Energy Sources 24 601-610. 

Alternative fuels fall into two general categories. The first class consists of fuels that are made from sources other than crude oil but that have properties the same as or similar to conventional motor fuels. In this category are fuels made from coal and shale (see Fuels, SYNTHETIC). In the second category are fuels that are different from gasoline and diesel fuel and which require redesigned or modified engines. These include methanol (see Alcohol FUELS), compressed natural gas (CNG), and liquefied petroleum gas (LPG). 

Properties A colorless liquefied petroleum gas. Bp -6.3C, d 0.5951 (20/4C), fp approximately —185C, specific volume 6.7 cu ft/lb (70F), flash p -110F (-79C), autoign temp approx 700F (371C). Soluble in most organic solvents insoluble in water. 

Dimethyl ether (DME) has been used as a fuel and propellant. It is miscible with most organic solvents and is currently under study as a fuel additive for diesel engines due to its high volatility and high cetane number. DME, like other synthetically derived fuels, can be produced from syngas, is essentially sulfur free, contains nearly zero aromatic compounds, and is considered an excellent substitute for conventional diesel and liquefied petroleum gas (LPG). DME has several physical properties similar to those of LPG. 

CAS 106-97-8 EINECS/ELINCS 203-448-7 UN 1011 (DOT) INS943a E943a Synonyms Alkane C4 n-Butane Butyl hydride Diethyl Liquefied petroleum gas Methylethylmethane Classification Alkane hydrocarbon Empirical C4H10 Formula CH3CH2CH2CH3 Properties Colorless gas faint disagreeable odor easily liquefied under pressure R.T. sol. in ethanol, ether, chloroform si. sol. in water m.w. 58.12 sp.gr. 0.599 vapor pressure 1620 mm Hg (17 psig, 21 C) f.p. -138 C b.p. -0.5 C flash pt. (CC) -60 C... 

The compounds found in petroleum deposits cover a wide range of relative molecular mass, and the process of refining petroleum to produce usable fuels primarily serves to separate this complex mixture into narrower fractions (defined by boiling point, as described later) with properties suited to the end-use application. The lightest fraction is typically material that, while easily liquefied by pressure, is gaseous at ambient conditions. Called liquefied petroleum gas it will not be described in this section, but rather included in the discussion of gaseous fuels. 

In the first studyMollerup and Rowlinson found that it was possible to reproduce liquefied natural gas densities to within 0.2%, even down to reduced temperatures of 0.3. In 1975, Mollerup continued his study of liquefied natural gas properties and reported results for phase equilibria, densities and enthalpies in both the critical- and normal-fluid regions. The method was also applied to natural gas, liquefied petroleum gas and related mixtures in a 1978 investigation. Mixtures studied included methane through pentane and common inorganics such as N2, CO, CO2 and H2S. The paper reported density predictions to within 0.2%, dew- and bubble-point errors not exceeding those of good experimental data and errors in liquid-phase enthalpies which were less than 2kJ- kg . ... 

---