Methane measurement

The compressibility factor z of methane is always less than 1.0 in normal temperature ranges (i.e., between —40° and 50° C). Furthermore, the compressibility factor decreases as the pressure rises or the temperature falls. Therefore, less energy is needed to pump a given volume of methane (measured at standard volume) at any given normal temperature than would be expected at that temperature if the methane were an ideal gas. This effect is more marked at higher pressures. Similarly, as the pressure is increased at a constant temperature, more methane (measured at standard volume) can be stored in a given volume than would be predicted from the ideal gas equation. 

Fig. 3.1.10 Molecular lifetimes xintra and. aii in H-ZSM-5 crystallites obtained using the NMR tracer desorption technique and calculated via Eq. (3.3.15), respectively. Tracing by probe molecules (methane, measurement at 296 K) after an H-ZSM-5 catalyst has been kept for different coking times in a stream of n-hexane (filled symbols) and mesitylene (open symbols) at elevated temperature. The inserts present the evidence provided by a comparison of xintra and r]1,]]], with respect to the distribu-...

Cicerone RJ, Shetter JD. Sources of atmospheric methane Measurements in rice paddies and a discussion. J. Geophys. Res. 1981 86 7203-7209. 

The next most likely possibility is cometary delivery of the atmosphere but again there are some problems with the isotope ratios, this time with D/H. The cometary D/H ratios measured in methane from Halley are 31 3 x 10-5 and 29 10 x 10-5 in Hayuatake and 33 8 x 10-5 in Hale-Bopp, whereas methane measurements from Earth of the Titan atmosphere suggest a methane D/H ratio of 10 5 x 10-5, which is considerably smaller than the ratio in the comets. The methane at least in Titan s atmosphere is not exclusively from cometary sources. Degassing of the rocks from which Titan was formed could be a useful source of methane, especially as the subnebula temperature around Saturn (100 K) is somewhat cooler than that around Jupiter. This would allow volatiles to be more easily trapped on Titan and contribute to the formation of a denser atmosphere. This mechanism would, however, apply to all of Saturn s moons equally and this is not the case. 

In any chain mechanism the steady-state hypothesis requires that the rate of initiation is equal to the rate of termination. The rate of reaction (5), as given by the rate of butane formation, is therefore also> a measure of the rate of the initiation reaction (1). Lin and Back have also made a study of the kinetics of butane formation, and have deduced from the results information about the initiation process. The conclusions agree with those obtained from the methane measurements. 

Jeanbaptiste P, Charlou JL, Stievenard M, Donval JP, Bougault H, Mevel C (1991) Helium and methane measurements in hydrothermal fluids from the Mid-Atlantic Ridge—The Snake Pit site at 23 °N, Earth Planet Sci Lett 106 1728... 

The number of cubic centimetres of methane, measured at STP, adsorbed on 1 g of charcoal at 0 °C and several different pressures is... 

Assume that 4.19 X 10 kJ of energy is needed to heat a home. If this energy is derived from the combustion of methane (CH4), what volume of methane, measured at STP, must be burned ... 

Since the velocity distribution of the sampled oxygen appears to be approximately independent of the time at which it was sampled, we can safely assume that this is also the case for methane. If we assume that the arrival time distribution for methane is approximately the same as that for oxygen except for the difference in the masses, the time scales of the methane measurement shown in... 

By plotting each component concentration as printed out from the integrator, the entire analytical system is checked out. That is the detector, separating system, and the integration software and normalization techniques are checked in the system as it will be used for BTU measurement. As a double check on the computer, the natural log of the BTU contribution of each component can be plotted against time and will yield the same graph as the concentration. Since all the components are normalized to 100%, this method also proves the linearity of the methane measurement. 

Approach to the boardwalks was made by airboat at a speed as slow as possible and with as little environmental disturbance as possible. Despite this caution, bubbles (that we now know are mainly methane) were sometimes observed from nearby sediments and we could smeU H2S immediately after we stopped the airboat at the boardwalk. The airboat approach path was always to the same end of the boardwalk, whereas the methane measurements were made from... 

Figures 2-4 show many collectors that have large ebullition events. Some occur during the first 5 min of methane accumulation. While it is possible that this may have been caused by the initial placement of the collectors on the surface of the water (between 4 and 8 cm deep depth determined after the methane measurements were completed), there are many examples of ebullition that were not associated with the initial placement of the collectors. During the...

Leventhal J. (1992) Modem methane measurements in marshes. U.S. Geol. Survey Open-File Report 92-445, 24 p. 

The rate of the initial dissociation of methane Measure-ments of the initial rate of dissociation have been described in detail elsewhere (19) and will be only briefly summarized here. 

Figure 5. Adsorption hysteresis of methane measured on a Hungarian hazardous high rank (bituminous) coal at 25°C [13]. o adsorption desorption.

Figure 8. Sorption isotherms of methane measured on high rank coal (Mecsek, Hungary) at temperature 120 K and 294 K [15]. o 120 K V 294 K.

FIG. 4 Direct measurement proves that in a high pressure range, the adsorption isotherm of methane measured on GAC activated carhon at 298 K decreases approximately linearly. (From Ref. 8.)... 

Figure 2 Rate coefficients for the reaction of Ol with methane measured as a function of average kinetic energy at several temperatures in a variable-temperature selected-ion flow drift tube (VT-SIFDT). Also shown are data taken with a high-temperature flowing afterglow (HFTA) and a drift tube. Reproduced with permission from Viggiano AA and Morris MA (1996) Journal of Physical Chemistry 100 19227-19240.

Where supervisors and first-line managers have defined responsibilities for monitoring the safety of conditions and/or activities (whether in the form of, for example, methane measurement, roof sounding, signing-off Permits to Work etc.) it is essential that their activities in delivering these responsibilities is actively and systematically supported by senior staff on the mine. 

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