Fouling problems

This second reaction leads to the small amount of branching (usually less than 5%) observed in the alcohol product. The alpha olefins produced by the first reaction represent a loss unless recovered (8). Additionally, ethylene polymerisation during chain growth creates significant fouling problems which must be addressed in the design and operation of commercial production faciUties (9). 

Potential particulate fouling problems if not properly designed... 

Evaporators—These usually utilize a fin-tube design. Spirally finned tubes of 1.25 in to 2 in outer diameter (OD) with three to six fins per ineh are eommon. In the ease of unfired designs, earbon steel eonstruetion ean be used and boilers ean run dry. As heavier fuels are used, a smaller number of fins per ineh should be utilized to avoid fouling problems. 

Eliminating the oil gets rid of the disposal problem of the contarainat ed oil, which must be properly disposed of or cleaned up and recycled. It also eliminates the fouling problems in components downstream of the compressor. Despite all efforts to the contrary, oil from liquid buffered seals finds its way into the gas stream. 

The temperature difference between the exiting vapor-liquid mixture and the inlet shell-side steam or hot fluid should not exceed 75-82°F, primarily due to fouling problems and possible conversion in the tube to inefficient film boiling in the upper section of the tubes. 

Contaminants such as oil, magnesium phosphate, and hematite have a natural binding action that exacerbates the fouling problem and may result in the rapid agglomeration of tube deposits in WT boilers and fire-tube bridging in FT boilers. 

Innocuous sludges such as those resulting from using phosphate precipitation programs may cause severe fouling problems, especially when oil, saponifiable fats, or other deposit binders are present in the boiler. 

Higher rates of sludging also take place in the boiler vessel. In turn, this potential fouling problem requires additional maintenance time because more frequent internal surface cleaning, wash-down, and boiler vessel sludge removal usually is required. Carryover of contaminants into the steam also is more likely. 

In addition, the solids may cause fouling problems such as reduced deaerator venting, sticking check valves, and blocked feed pump. 

The condition of an exhausted resin bed is an ionically banded bed, with the most strongly held ions on the top of the bed. Iron is more strongly held than calcium, which may lead to iron fouling problems. Some practical considerations for a RW softener are ... 

A chemical treatment designed to condition BW precipitants in order to prevent their coagulation and the subsequent likely accumulation of sludges that can cause fouling problems. 

To circumvent high overvoltage and fouling problems encountered with the direct oxidation of NADH at conventional electrode (equation 6-11), much work has been devoted to the development of modified electrodes with catalytic properties for... 

Printed circuit heat exchangers, fouling problems 553... 

Cell-free translation system, used for the identification of cloned genes and gene expression, has been investigated extensively as a preparative production system of commercially interesting proteins after the development of continuous-flow cell-free translation system. Many efforts have been devoted to improve the productivity of cell-free system [1], but the relatively low productivity of cell-free translation system still limits its potential as an alternative to the protein production using recombinant cells. One approach to enhance the translational efficiency is to use a condensed cell-free translation extract. However, simple addition of a condensed extract to a continuous-flow cell-free system equipped with an ultrafiltration membrane can cause fouling. Therefore, it needs to be developed a selective condensation of cell-free extract for the improvement of translational efficiency without fouling problem. 

Some of the preferred tools used in natural microbial control programs are given in Table 8. The goal in nature is always to maintain control of a system, to avoid letting it foul until cleanup is the last resort. In nature, maintenance of a clean system is the only real hope for survival. Clean rarely, if ever, means sterile. The natural systems discussed in this paper, for example, are always comprised of vast microbial flora in close proximity to or actually a part of the protected portion of the system in which microbial fouling problems are actively managed by the animal or plant. 

With all membrane processes, there is a potential fouling problem that must be addressed when specifying the unit. With liquid feeds in particular, this usually means pretreating the feed to remove solids, potentially down to very fine particle sizes, as well as other pretreatments. Membranes... 

Normally, treatment of coproduced groundwater during hydrocarbon recovery operations will include, as a minimum, oil-water separation and the removal of dissolved volatile hydrocarbon fractions (i.e., benzene, toluene, and total xylenes). In addition, removal of inorganic compounds and heavy metals (i.e., iron) is often required. Dissolved iron, a common dissolved constituent in groundwater, for example, may require treatment prior to downstream treatment processes to prevent fouling problems in air-stripping systems. Heavy metals removal is normally accomplished by chemical precipitation. 

Callow, M.E. Ship fouling problems and solutions. Chemistry Industry. Vol. 

Where most utility installations are the lime or limestone processes, it can be seen from Table IV that a very small percentage of industrial installations are of this type. Most of these installations are the once-through sodium carbonate, sodium hydroxide, and double alkali processes. Where the utility installations have been plagued with corrosion, erosion, scaling and fouling problems, the industrial installations, have to date performed much better. A number of systems showed a process reliability of greater than 85%. 

A further level of sophistication is illustrated by a submersible UV/vis spectrometer, currently being developed for batch process analysis but potentially also applicable to continuous processes. This instrument also overcomes the sensor-fouling problem by using an auto cleaning system based on pressurised air [76]. 

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