Gas-prone

The expulsion of gas is probably very efficient. Altebdumer (1982, in Cooles et al., 1986), for instance, showed that gas expulsion from the gas-prone Lias 5 shales, N.W. Germany, is very efficient with up to 95% of generated gas being expelled from the source rock. As outlined in Section 3.2.2.1, gas generation... 

Carboniferous shales in the Ghadames and Illizi Basins contain gas-prone humic kerogen and have TOC ranging from 1 to 4%. Because the thickness of Carboniferous shales is considerable in this province (from 500 to 1500 m in its central part), they may be considered as a good source for hydrocarbon generation. Present-day vitrinite reflectance ranges from 0.50 to 0.71% TTI = 7-110 Tables 6.6,6.7). 

Gas Prone Poor Potential Moderate Potential Good Potential Coalv Shales Excellent Potential ... 

Corrosion protection of metals can take many fonns, one of which is passivation. As mentioned above, passivation is the fonnation of a thin protective film (most commonly oxide or hydrated oxide) on a metallic surface. Certain metals that are prone to passivation will fonn a thin oxide film that displaces the electrode potential of the metal by +0.5-2.0 V. The film severely hinders the difflision rate of metal ions from the electrode to tire solid-gas or solid-liquid interface, thus providing corrosion resistance. This decreased corrosion rate is best illustrated by anodic polarization curves, which are constructed by measuring the net current from an electrode into solution (the corrosion current) under an applied voltage. For passivable metals, the current will increase steadily with increasing voltage in the so-called active region until the passivating film fonns, at which point the current will rapidly decrease. This behaviour is characteristic of metals that are susceptible to passivation. 

Erosion is the deterioration of a surface by the abrasive action of solid particles in a liquid or gas, gas bubbles in a liquid, liquid droplets in a gas or due to (local) high-flow velocities. This type of attack is often accompanied by corrosion (erosion-corrosion). The most significant effect of a joint action of erosion and corrosion is the constant removal of protective films from a metal s surface. This can also be caused by liquid movement at high velocities, and will be particularly prone to occur if the solution contains solid particles that have an abrasive action. 

A second factor determining module selection is resistance to fouling. Membrane fouling is a particularly important problem in Hquid separations such as reverse osmosis and ultrafiltration. In gas separation appHcations, fouling is more easily controlled. Hollow-fine fibers are notoriously prone to fouling and can only be used in reverse osmosis appHcations if extensive, costiy feed-solution pretreatment is used to remove ah. particulates. These fibers caimot be used in ultrafiltration appHcations at ah. 

At higher total flow rates, particularly when the Hquid is prone to foaming, the reactor is a pulsed column. This designation arises from the observation that the pressure drop within the catalyst bed cycles at a constant frequency as a result of Hquid temporarily blocking gas or vapor pathways. The pulsed column is not to be confused with the pulse reactor used to obtain kinetic data ia which a pulse of reactant is introduced into a tube containing a small amount of catalyst. 

The effeet of integration method and stepsize must be eheeked for every application where temperature runaway is possible. Those will be mostly oxidations, but other reaetions ean be very exothermie, too. During the 1973/74 oil erisis, when synthetie natural gas projeets were in vogue, one of the CO hydrogenation teehnologies was found to be very exothermie and prone to runaway also. 

The rates of gas-solid reaetions are surfaee area dependent, so finely-divided metals, eoal ete. may be prone to oxidation leading to spontaneous eombustion. A eombustible dust will burn mueh more rapidly than the bulk sold, and if dispersed in air eause a dust explosion (refer to Table 6.2). 

The most important hardware items appeared to be the detectors themselves. The gas detection system gave frequent spurious alarms, and on both platforms the ultraviolet (UV) fire detectors were also prone to spurious activation from distant hot work for example, and had a limited ability to detect real fires. The tmreliability of these systems had a general effect on response time and would, overall, lengthen the time to respond. The second aspect which was related to hardware was fimction and performance testing of the emergency blowdown systems. It is critical that the workers believe the systems will work when required, and this can only be achieved by occasional use or at least fimction testing. 

HCl shows no tendency to dissociate in the gas phas however, and HCl is less prone to dissociate in less pol solvents, such as methanol. 

Gas turbines and power stations are particularly prone to generate NOx and the search for the low-NOx burner that will operate at high efficiency (i.e. with low hydrocarbon emissions) continues. The principle of the low-NOx burner is to slow the rate of combustion by dividing it into several stages by the gradual mixing of the combustion gases with the stoichiometric air volume. 

Some crevice attack upon titanium can also occur in the presence of gaseous chlorine gas at temperatures below 100°C, but this is mainly confined to crevices formed between titanium and organic sealing compounds. Here again, the Ti-0- 15Pd alloy is less prone to attack. 

Cyclic Oxidation In many industrial applications it is particularly important for the component to be resistant to thermal shock for example, resistance-heating wires or blading for gas turbines. Chromia, and especially alumina, scales that form on nickel-base alloys are prone to spalling when thermally cycled as a result of the stress build-up arising from the mismatch in the thermal expansion coefficients of the oxide and the alloy as well as that derived from the growth process. A very useful compilation of data on the cyclic oxidation of about 40 superalloys in the temperature range 1 000-1 I50°C has been made by Barrett et... 

To prompt inhibitor addition to a gas scrubbing system solution prone to cause stress-corrosion cracking of carbon steel when the potential moves towards a value at which stress-corrosion cracking is known to occur. 

---