Hydrocarbon gas analysis

The development of a commercial mass spectrometer and its application to hydrocarbon gas analysis by the method of Washburn et al. (63) made gas analysis rapid, economical, and, what is even more important, inspired a confidence in the results of routine hydrocarbon gas analysis which was badly lacking. A complex gaseous mixture comprising the atmospheric gases, carbon monoxide, and Ci to C6 hydrocarbons required more than 20 hours of applied time by the previous methods of low temperature fractional distillation coupled with chemical absorption methods. With the mass spectrometer such an analysis is completed in 2 hours or less, about 15 minutes of which is consumed in the... 

Analysis of specific components or classes of components in refinery gases can be accomplished with single-column analyses. However, combinations of columns and valving are required for more complete analyses. The various aspects of hydrocarbon gas analysis have been discussed by Thompson (61). Applicable columns for these applications can also be found in column supplier catalogs and the reviews by Mindrup (62) and Leibrand (63). 

Acetylene Derived from Hydrocarbons The analysis of purified hydrocarbon-derived acetylene is primarily concerned with the determination of other unsaturated hydrocarbons and iaert gases. Besides chemical analysis, physical analytical methods are employed such as gas chromatography, ir, uv, and mass spectroscopy. In iadustrial practice, gas chromatography is the most widely used tool for the analysis of acetylene. Satisfactory separation of acetylene from its impurities can be achieved usiag 50—80 mesh Porapak N programmed from 50—100°C at 4°C per minute. 

For intermediate temperatures from 400-1000°C (Fig. 11), the volatilization of carbon atoms by energetic plasma ions becomes important. As seen in the upper curve of Fig. 11, helium does not have a chemical erosion component of its sputter yield. In currently operating machines the two major contributors to chemical erosion are the ions of hydrogen and oxygen. The typical chemical species which evolve from the surface, as measured by residual gas analysis [37] and optical emission [38], are hydrocarbons, carbon monoxide, and carbon dioxide. 

More sophisticated detection methods for gas chromatography are also employed in the analysis of hydrocarbons gas chromatography-mass spectrometry (EPA 8270C) and gas chromatography-Fourier transform infrared spectroscopy (EPA 8410). These procedures have a significant advantage in providing better characterization of the contaminants and thus are of particular use where some environmental modification of the hydrocarbons has taken place subsequent to soil deposition. 

Industrial analysis of hydrocarbon gases 25 years ago was limited almost to Orsat-type absorptions and combustion, resulting in crude approximations and inadequate qualitative information. The more precise method of Shepherd (56) was available but too tedious for frequent use. A great aid to the commercial development of hydrocarbon gas processes of separation and synthesis was the development and commercialization of high efficiency analytical gas distillation units by Podbielniak (50). In these the gaseous sample is liquefied by refrigeration, distilled through an efficient vertical packed column, the distillation fractions collected as gas and determined manometrically at constant volume. The operation was performed initially in manually operated units, more recently in substantially automatic assemblies. 

TJpdegraff, D. M., and W. B. Huckabay A Rapid Micro Gas Analysis System for Carbon Dioxide, Oxygen, Hydrocarbon Gases and Hydrogen. Anal. Bio-chem. 5, 28 (1963). 

Bridie et al. [27] have studied the solvent extraction of hydrocarbons and their oxidative products from oxidised and non-oxidised kerosine-water mixtures, using pentane, chloroform and carbon tetrachloride. Extracts are treated with Florasil to remove non-hydrocarbons before analysis by temperature programmed gas chromatography. From the results reported it is concluded that, although each of the solvents extracts the same amount of hydrocarbons, pentane extracts the smallest amount of non hydrocarbons. Florasil effectively removes non hydrocarbons from pentane extracts, but also removes 10-25% of aromatic hydrocarbons. However, as the other solvents are less susceptible than pentane to treatment with Florasil, pentane is considered by those workers to be the most suitable solvent for use in determining oil in water. 

Estrada-Pena, A. and Dusbabek, F. (1993). Cuticular hydrocarbon gas chromatography analysis of Argas vulgaris, A. polonicus, and their hybrids. Exp. Appl. Acarol., 17, 365-376. 

Some general applications of TG-FTIR are evolved gas analysis, identification of polymeric materials, additive analysis, determination of residual solvents, degradation of polymers, sulphur components from oil shale and rubber, contaminants in catalysts, hydrocarbons in source rock, nitrogen species from waste oil, aldehydes in wood and lignins, nicotine in tobacco and related products, moisture in pharmaceuticals, characterisation of minerals and coal, determination of kinetic parameters and solid fuel analysis. 

SO2, NOx, and total hydrocarbons. The mass spectrometric gas analysis is on a wet basis, as water vapor is not condensed out of the gas, while the analyzers at the sample port measure a gas stream dried using a permeation tube and refrigeration-type dryers in series. In addition to the measurements described above, surface temperature measurements of the boiler skin are made to estimate radiation losses, using the skin temperature, the room temperature and tabulated heat loss factors based on the temperature difference. Particulate mass emission rate and carbon content are measured for heat and mass balance purposes. At present, material deposited within the boiler during a test is collected but not factored into the heat or mass balances, because this deposition is considered to be negligible. Data taken are used to examine the heat balance for the 20-hp system. 

On-line analysis of the hydrocarbons in the vent gas was done on a 20-ft Porapak Q column with an internal standard. In many cases, the internal standard also allowed calculation of hydrogen by difference. A Beckman 3AM3 gas density balance provided a check on the vent gas analysis and the necessary parameter for calculating mass flow rates from orifice pressure drop data. Mass balance closure was typically better than it 2%. 

It is well known that most of the gaseous hydrocarbons of the aliphatic series when exploded with an excess of oxygen are converted into the end-products of combustion, carbonic acid and water. This fact is made use of in quantitative gas analysis. The combustion is often not complete intermediate products can be obtained if we start with hydrocarbon derivatives instead of the hydrocarbons themselves. 

In regard to the work of Wilson et al, (3) where the only hydrocarbons produced were ethylene and propylene and that of Swinnerton et al (4), we thought that an analysis of correlation between the unsaturated hydrocarbons and chlorophyll a for the entire cruise track would be beneficial. A correlation coeflBcient, R, of 0.56 was obtained using ethylene and propylene against chlorophyll a. A correlation coeflBcient of 0.59 was obtained between ethylene only and chlorophyll a. This latter correlation was done because the ethylene values are much greater than the propylene and also because ethylene was the prominent hydrocarbon gas produced in the work by Wilson et al (3). 

Polycyclic Aromatic Hydrocarbons. Gas chromatographio-mass spectrometric analysis of fractions 31-91 indicated the presence of various polycyclic aromatic hydrocarbons (PCAH) with molecular weights of 178-316. Because it is impossible to discuss in detail all die chromato-... 

---