Natural gas, properties

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 . ... 

The American Gas Association equation AGA8 for natural gas properties (as an alternative to the Helmholtz model). 

C. It occurs in natural gas. May prepared by reduction of ethene or ethyne by hydrogen under pressure in the presence of a nickel catalyst, or by the electrolysis of a solution of potassium elhanoate. It has the general properties of the paraffins. Used in low-temperature refrigeration plant. 

At one time thiols were named mercaptans Thus CH3CH2SH was called ethyl mercaptan according to this system This nomenclature was abandoned beginning with the 1965 revision of the lUPAC rules but is still sometimes encountered When one encounters a thiol for the first time especially a low molecular weight thiol its most obvious property is its foul odor Ethanethiol is added to natural gas so that leaks can be detected without special equipment—your nose is so sensitive that it can detect less than one part of ethanethiol m 10 000 000 000 parts of arr The odor of thiols weakens... 

Natural gas and its combustion properties appear to have been known since early times (2). Some early temples of worship were located in areas where gas was seeping from the ground or from springs, and it is reported that Julius Caesar saw a phenomenon called the "burning spring" near Grenoble, France. Gas wells were drilled in Japan as early as 615 AD and in 900 AD the Chinese employed bamboo tubes to transport natural gas to their salt works, where the heat was used to evaporate water from salt brine. The existence of natural gas in the United States was reported by early setders who observed gas seeps and columns of fire in the Ohio Valley and the Appalachian area in 1775 (3). 

The physical properties of the principal constituents of natural gas are Hsted in Table 5. These gases are odorless, but for safety reasons, natural gas is odorized before distribution to provide a distinct odor to warn users of possible gas leaks in equipment. Sulfur-containing compounds such as organic mercaptans, aUphatic sulfides, and cycHc sulfur compounds are effective odorants at low concentrations and are added to natural gas at levels ranging from 4 to 24mg/m. ... 

Alternative fuels fall into two general categories. The first class consists of fuels that are made from sources other than cmde 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 Hquefted petroleum gas (LPG). 

Applications. The high heat tolerance and good salt compatibiUty of welan gum indicate its potential for use as an additive in several aspects of oil and natural gas recovery. Welan also has suspension properties superior to xanthan gum, which is desirable in oil-field drilling operations and hydraulic fracturing projects. It is compatible with ethylene glycol, and a welan—ethylene glycol composition that forms a viscous material useful in the formulation of insulating materials has been described (244). 

There are two principal mechanisms of enhanced oil recovery increasing volumetric sweep efficiency of the injected fluid and increasing oil displacement efficiency by the injected fluid. In both, chemicals are used to modify the properties of an injected fluid whether water, steam, a miscible gas such as CO2 or natural gas, or an immiscible gas, usually nitrogen. Poor reservoir volumetric sweep efficiency is the greatest obstacle to increasing oil recovery (9). 

Furthermore, appreeiahle differenees ean arise from simply using different sourees of data on gas properties. There are very few ealeu-lated power requirements for a easeade proeess under praetieal operating eonditions that have been published and, therefore, available for a direet eomparison between the two proeesses. Additionally, published figures on the aetual power requirements for many easeades are aetually for natural gas, whereas the ealeulated figures are based on the liquefaetion of pure methane. 

An alternate approach to fuel washing is to utilize a vaporized fuel oil system (VFO). This technology was developed as a method for converting natural gas fuel systems to liquid fuel. The process involves mixing steam with the liquid fuel and then vaporizing the mixture. The vaporized mixture exhibits the same combustion properties as natural gas. 

VFO works well in gas turbines. In a nine-month test program, the combustion properties of VFO were studied in a combustion test module. A gas turbine was also operated on VFO. The tests were conducted to study the combustion characteristics of VFO, the erosive and corrosive effects of VFO, and the operation of a gas turbine on VFO. The combustion tests were conducted on a combustion test module built from a GE Frame 5 combustion can and liner. The gas turbine tests were conducted on a Ford model 707 industrial gas turbine. Both the combustion module and gas turbine were used in the erosion and corrosion evaluation. The combustion tests showed the VFO to match natural gas in flame patterns, temperature profile, and flame color. The operation of the gas turbine revealed that the gas turbine not only operated well on VFO, but its performance was improved. The turbine inlet temperature was lower at a given output with VFO than with either natural gas or diesel fuel. This phenomenon is due to the increase in exhaust mass flow provided by the addition of steam in the diesel for the vaporization process. Following the tests, a thorough inspection was made of materials in the combustion module and on the gas turbine, which came into contact with the vaporized fuel or with the combustion gas. The inspection revealed no harmful effects on any of the components due to the use of VFO. 

Predicting the appropriate level of duetile fraeture resistance involves an analysis of fluid properties, operating conditions, and material properties. For natural gas pipelines containing mostly methane with very... 

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