Continuous Injection

The question then is, to what degree can the microscopic motions influence the macroscopic ones is there a flow of infonnation between them [66] Biological systems appear to be nonconservative par excellence and present at least the possibility that random thermal motions are continuously injecting new infonnation into the macroscales. There is certainly no shortage of biological molecular machines for turning heat into correlated motion (e.g. [67] and section C2.14.5 note also [16]). 

LDPE, also known as high pressure polyethylene, is produced at pressures ranging from 82—276 MPa (800—2725 atm). Operating at 132—332°C, it may be produced by either a tubular or a stirred autoclave reactor. Reaction is sustained by continuously injecting free-radical initiators, such as peroxides, oxygen, or a combination of both, to the reactor feed. 

Sour gas sweetening may also be carried out continuously in the flowline by continuous injection of H2S scavengers, such as amine-aldehyde condensates. Contact time between the scavenger and the sour gas is the most critical factor in the design of the scavenger treatment process. Contact times shorter than 30 sec can be accommodated with faster reacting and higher volatility formulations. The amine-aldehyde conden-... 

SCR units require handling, storage, and continuous injection of the reducing agent. The temperature level is critical because the SCR operates in a narrow temperature range between 550°-750°F (260°-399°C), and thus an exchanger is necessary to cool the exhaust stream. This leads to a complicated and costly process system that must be added to the engine exhaust. 

FIGURE 6.4 Steam flooding is one of two principal thermal methods for oil recovery and has been commercially applied since the early 1960s. A mixture of steam and hot water is continuously injected into the oil-bearing formation to displace mobilized oil to adjacent production wells. Reprinted with permission from Enhanced Oil Recovery. Copyright 1984 by the National Petroleum Council. 

Processes based on fluidized bed coating have been developed (49). In this process, the bioactive agent is dissolved in an organic solvent along with the polymer. This solution is then processed through a Wurster air suspension coater apparatus to form the final microcapsule product. A solvent partition technique based on continuous injection of a polymer-drug solution into flowing mineral oil has been reported (50). 

Thermal plasma-assisted decomposition (cracking) of heavy hydrocarbons is reported in Ref. 141. Decomposition of paraffinic hydrocarbons including C16H34 by Ar-H2 plasma was carried out by continuous injection of the hydrocarbon in the spouted-bed reactor. Controlling temperature, residence time, and H2 concentration allows reaching the... 

In the post-treatment of films or fibers, fluorine-containing gas is continuously injected into the reactor and gaseous by-products are removed. The other type of reactor for posttreatment is the batch process reactor, which consists of a suitably sized vacuum chamber provided with means of evacuation and injection. 

If water is caused to flow steadily through a transparent tube and a dye is continuously injected into the water, two distinct types of flow may be... 

Use of pulsed air injection rather than continuous air injection may improve performance at many sites. After a system has been operating for a period of time, the concentration of contaminant in the recovered air declines. Continued injection of the same volume of injected air recovers less VOC. Injection of air in a pulsed pattern allows time for reestablishment of a greater concentration gradient toward air channels and a more uniform concentration throughout the contaminant plume area. When the system is resumed, volatilization is again the predominant removal mechanism. 

On-line solvent injection. On-line solvent injection is very successful in various processes. The objective of this measure is to continuously inject a small amount of solvent to reduce the friction coefficient of the blade and impeller surface and thus prevent fouling of the surface. The injection should be done from the start otherwise, the foulant could be dislodged and moved downstream, creating a major problem. The downstream areas are much smaller so foulant lodging there could create a blockage. 

Recovery of oil sand bitumen by steam injection involves either cyclic or continuous injection of steam at high pressure into a well. In cyclic injection, steam is injected into the oil sand formation for a period of time ranging from weeks to months. The steam spreads or floods the formation creating heat or pressure. The steam is then turned off, and the well is sealed for weeks to months. When the well is reopened, a mixture of water and bitumen can be withdrawn. 

Continuous injection is accomplished by drilling two wells into the oil sand deposit, one injection well and one recovery well. Into the injection well, air is pumped at high pressure, and bitumen at the base of the well is ignited. Air injection continues and moves the combustion process along as temperatures of 660°F to 940°F (350°C to 450°C) are attained. The bitumen is thermally cracked and vaporized. The cracked oils, gases, and vapors are driven toward the production well by injected air and recovered. 

In liquid chromatography, liquid samples may be injected directly and solid samples need only to be dissolved in an appropriate solvent. The solvent need not to be the mobile phase, but frequently it is judiciously chosen to avoid detector interference, column/component interference or loss in efficiency. It is always best to remove particles from the sample by filtering, or centrifuging since continuous injection of particulate materials will eventually cause blockage of injection devices or columns. 

Perhaps the most direct experimental means of examining the relationship between emissions and air quality is to simulate atmospheric conditions using large chambers. Measured concentrations of the primary pollutants are injected into these environmental (or smog) chambers, as they are called. These are then irradiated with sunlight or lamps used to mimic the sun, and the time-concentration profiles of the primary pollutants as well as the resulting secondary pollutants are measured. The primary pollutant concentrations as well as temperature, relative humidity, and so on can be systematically varied to establish the relationship between emissions and air quality, free from the complexities of continuously injected pollutant emissions and meteorology, both of which complicate the interpretation of ambient air data. 

Clearly, environmental chamber studies are very useful tools in examining the chemical relationships between emissions and air quality and for carrying out related (e.g., exposure) studies. Use of these chambers has permitted the systematic variation of individual parameters under controlled conditions, unlike ambient air studies, where the continuous injection of pollutants and the effects of meteorology are often difficult to assess and to quantitatively incorporate into the data analysis. Chamber studies have also provided the basis for the validation of computer kinetic models. Finally, they have provided important kinetic and mechanistic information on some of the individual reactions occurring during photochemical smog formation. 

As an example. Fig. 18 shows CP/MAS NMR spectra recorded during the investigation of surface ethoxy species (7S) formed on acidic zeolite HY ( si/ Ai = 2.7) by a SF protocol. Figure 18a shows the CP/MAS NMR spectrum recorded after a continuous injection of C-1-enriched ethanol, CHI CHzOH, into the MAS NMR rotor reactor containing calcined zeolite HY. The ethanol was injected at room temperature for 10 min. Subsequently, the loaded zeolite was purged with dry nitrogen (200 mL/min) at room temperature for 2h. 

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