Static pressure recovery

Static pressure recovery method. The diameters are selected in such a way that the same static pressure is available before every connection. The duct reduction is selected in such a way that the gain of static pressure is in balance with the friction losses up to the next connection point. This method may result in fewer control devices at connection points or outlets. Low velocities and large diameters at the end of the system may be the result of this design approach. 

From an aerodynamic point of view it is well-known that a discharge volute may be represented as a diffusing flow, whose main performance is given in terms of a static pressure recovery coefficient (Cp ) and a total pressure loss coefficient ( ) as defined by Eq. (la, lb)... 

What is different for a discharge volute compared to a standard diffuser is the flow pattern because the flow velocity is not perpendicular to the flow passage areas, hence a swirl angle miist be defined at each section and this plays a fundamental role in the aerodynamic behavior and the performance of the volute as shown in Fig.(3) and the static pressure recovery coefficient must be modified as shown in Eq. (2)... 

The utihty iadustry utilizes fans typically from 6.7—10 m diameter ia banks of 8 to 12 fans ia wet cooling towers. These towers cool the water used to condense the steam from the turbiaes. Many towers may be needed ia large plants requiring as many as 50 to 60 fans 12 m in diameter. These fans typically utilize velocity recovery stacks to recoup some of the velocity pressure losses and convert it to useful static pressure work. 

Determination. GC two different SFE systems are compared high temperature method in some cases yields a more exhaustive extraction, but also less clean extracts whereas medium temperature may sometimes cause problems with quantitative recoveries, but it yields very clean extracts The use, advantages and disadvantages of silica sorbents, polymeric, functionalized, carbon-based and mixed available sorbents are discussed Determination. LC—MS best conditions, extraction solvent methanol—acetone (1 1, v/v) temperature 50°C pressure 1500 psi two static cycles recoveries >10%. LOD between 1 to 5 /ag/kg loss of volatile molecules is produce at elevated temperatures Determination GC-MS Best conditions extractant methanol temperature lOffC, pressure 100 atm combined with 15 min static and then 10 min dynamic recovery 111% (RSD 4%) and 106% (RSD 5%) extraction efficiency of the PLE was compared with conventional Soxhlet and bath ultrasonication GC-MS an extraction time of 1 h was employed. 

Document the existing exhaust air systems to determine what exhaust fan modifications wiU be needed with the addition of exhaust air filters and energy recovery water coEs. These changes will have been identified in the original ECM assessment and would take into account the changing out of fan motor, motor starter size, etc., based on exhaust fan curves, performance data, and increase in fan system static pressure... 

The dynamic pressure stored in the swirling motion in the vortex finder can be quite significant. As mentioned, if no pressure recovery or flow rectify-ing/straightening device is installed in the gas outlet tube, wall friction, along with turbulence and mixing created by downstream bends, expansions, valves, etc., will eventually dissipate it without much recovery of static pressure. 

One way out of these difficulties lies in the observation that the static pressure at the wall is close to the cross-sectional mean of the static pressure plus the dynamic pressure stored in the swirl (Hoffmann et al., 1992). Or said in another way the static pressure measured at the wall is close to the static pressure that would be measured after an ideal rectifier (or pressure recovery diffuser ), which would convert all the swirl dynamic pressme into static pressme. We emphasize that this is not necessarily so, it only happens to be so because the static pressure in the vortex finder happens to be very nearly a linear function of the radius. Thus, in the absence of pressme recovery devices, the static pressure measured at the wall of the outlet tube minus the static pressme at the inlet gives the true dissipative loss between inlet and the measurement point in the outlet. One should be aware, though, that further dissipation of dynamic swirl pressure will take place in the downstream piping as the spin decays due to friction with the pipe wall, bends, etc. 

Pressure-recovery type vortex tubes, along with pressure-recovery type diffusers set atop the roof of the cyclone, are occasionally used to convert some of the rotational energy of the exiting gas back into static pressure. Based on data presented by Muschelknautz and Bruimer (1967), a modest amount of pressure recovery (15 to 20% reduction in vortex core pressure loss) can be achieved with a simple conically shaped vortex tube, such as that shown in frame g. More efficient recovery (35 to 40% loss reduction) is possible with a well-designed internal conical insert, such as that shown in frame h. Normally, such a vortex tube is directly connected to a wide-bodied outlet diffuser or exit scroll which sits atop the cyclone roof. 

To illustrate the effect of radial release interactions on the structure/ property relationships in shock-loaded materials, experiments were conducted on copper shock loaded using several shock-recovery designs that yielded differences in es but all having been subjected to a 10 GPa, 1 fis pulse duration, shock process [13]. Compression specimens were sectioned from these soft recovery samples to measure the reload yield behavior, and examined in the transmission electron microscope (TEM) to study the substructure evolution. The substructure and yield strength of the bulk shock-loaded copper samples were found to depend on the amount of e, in the shock-recovered sample at a constant peak pressure and pulse duration. In Fig. 6.8 the quasi-static reload yield strength of the 10 GPa shock-loaded copper is observed to increase with increasing residual sample strain. 

The present study investigates the adsorption and trapping of polymer molecules in flow experiments through unconsolidated oil field sands. Static tests on both oil sand and Ottawa sand indicates that mineralogy plays a major role in the observed behavior. Effect of a surfactant slug on polymer-rock interaction is also reported. Corroborative studies have also been conducted to study the anomalous pressure behavior and high tertiary oil recovery in surfactant dilute-polymer systems(ll,12). 

Kreisselmeier and Diirbeck [28] extracted alkylphenols, NPEO and OPEO by SFE using methanol as a modifier. The extraction pressure had to be set as high as possible (>450 atm), with a dynamic extraction time of 30 min. Neither an elevation of the temperature from 100 to 150°C nor an extension of the static extraction time improved the recovery. Comparable results were even obtained at 30°C while omitting the static extraction step. The modifier proved again to be quite important, as the recoveries increased by 20% with the addition of 27.5% methanol. Problems arose with the extraction of aged samples, for which the extractability was reduced by 40% for NPEO and NP, and 22% for OPEO. 

Phospholipid-derived fatty acids are often used to identify bacteria by capillary GC analysis after liquid solvent extraction, concentration steps, and chemical derivatization to their methyl esters. Our initial investigations attempted to extract the intact phospholipids, but no significant recoveries were achieved using pure C02. Even if SFE conditions were developed that could extract intact phospholipids, an additional derivatization step would be required before GC analysis of the fatty acid components. For these reasons, chemical derivatization/SFE was investigated in an effort to eliminate the lengthy conventional liquid solvent extractions as well as to combine (and shorten) the extraction and derivatization steps. The derivatization/SFE procedure was performed on samples of whole bacteria using 0.5 mL of 1.5% TMPA in methanol. The static derivatization step was performed for 10 minutes at 80°C and 400 atm C02, followed by dynamic SFE for 15 minutes at a flow rate of ca. 0.5 mL/min of the pressurized C02. Extracts were collected in ca. 3 mL of methanol and immediately analyzed by capillary GC without any further sample preparation. 

Samples of sand spiked with 36 nitroaromatic compounds, 19 haloethers, and 42 organochlorine pesticides, and a standard reference soil (certified for 13 polynuclear aromatic hydrocarbons, dibenzofuran, and pentachlorophenol) were extracted with supercritical carbon dioxide in a two- or four-vessel supercritical fluid extractor to establish the efficiency of the extraction and the degree of agreement of the parallel extraction recoveries. Furthermore, the many variables that influence the extraction process (e.g., flowrate, pressure, temperature, moisture content, cell volume, sample size, extraction time, modifier type, modifier volume, static versus dynamic extraction, volume of solvent in the collection vessel, and the use of glass beads to fill the void volume) were investigated. 

When the experiments were performed at the same pressure, temperature, and moisture content but with toluene as modifier and with a static extraction time of 15 or 30 min prior to the dynamic extraction step, then recovery was most affected by moisture content (sum of ranks 88) followed by pressure (sum of ranks 70) and the toluene volume (sum of ranks 68). The fourth variable to influence was the static extraction time (sum of ranks 57). Temperature, volume of collection solvent, and the presence/absence of glass beads were the least important. Figure 6 shows the relative changes in recovery for each compound and for each of the seven variables investigated in Test 2. 

Figure 6. Relative change in percent recovery (when going from low to high) for the 15 target compounds identified in Table IX (test 2). The variables are identified as follows pressure (P), temperature (D), volume of toluene as modifier (F), volume of collection solvent (G), moisture (M), glass beads (B) and static extraction time (E). The 15 compounds are those listed in Table DC...

Since many herbicides are crop-specific, herbicide concentrations in farmer s fields are routinely monitored to determine herbicide carry-over. Residual herbicides from the previous year adversely affect alternate crops grown to be grown during the subsequent season. There has been a limited amount of literature describing the successful SFE of herbicides such as sulfonylureas, diruron, linuron, and s-triazines spiked on various solid matrices with COj and methanol modified C02 (1,8-11). Summarized here are the differences in recovery of atrazine from an actual farmer s soil sample as a function of extraction temperature and pressure using both CO2 and methanol modified COj. Also shown are comparisons of recoveries from real vs. spiked samples and also static vs. dynamic modifier addition techniques. 

Studied in this chapter. In particular, we adjusted an exponential decay to the first 10 seconds of the recovery at all 6 pressures, and we found a thermal isomerization rate for PMMA-DRl in the range 0.17 - 0.23 s, with no particular dependence on pressure. This result rules out pressure-induced static effects and reinforces the friction effects discussed it also shows that if trans has enough sweep volume to isomerize to cis, cis will also have enough sweep volume to isomerize back, a feature supported by the more compact and globular, i.e., twisted, conformation of the cis- versus the trans-DRl. 

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