System Condition

The efficiency of the Rankine cycle itself can be increased by higher motive steam pressures and superheat temperatures, and lower surface condenser pressures in addition to rotating equipment selection. These parameters are generally optimized on the basis of materials of constmction as well as equipment sizes. Typical high pressure steam system conditions are in excess of 10,350 kPa (1500 psi) and 510 °C. 

Pollutant or system condition Limiting concentration Kind of pretreatment... 

The preferred ratio of cuprous to cupric ion ranges from 5 1 to 10 1, depending on system conditions. Too high a concentration of cuprous ion causes the system to disproportionate and form metallic copper (eq. 26) ... 

Any of these definitions of supersaturation can be used over a moderate range of system conditions. For example, a difference ia chemical potential A// = — fi is proportional to both c — c and T — T over a modest range of conditions. Of the five expressions given, however, the second is most... 

Analysis of equation 48 shows that a single sample taken either from inside the crystallizer or from the product stream will allow evaluation of nucleation and growth rates at the system conditions. Figure 12 shows a plot of typical population density data obtained from a crystallizer meeting the stated assumptions. The slope of the plot of such data maybe used to obtain the growth rate, and the product of the intercept and growth rate gives the nucleation rate. 

Supercriticalfluid solvents are those formed by operating a system above the critical conditions of the solvent. SolubiHties of many solutes ia such fluids often is much greater than those found for the same solutes but with the fluid at sub atmospheric conditions. Recently, there has been considerable iaterest ia usiag supercritical fluids as solvents ia the production of certain crystalline materials because of the special properties of the product crystals. Rapid expansion of a supercritical system rapidly reduces the solubiHty of a solute throughout the entire mixture. The resulting high supersaturation produces fine crystals of relatively uniform size. Moreover, the solvent poses no purification problems because it simply becomes a gas as the system conditions are reduced below critical. 

Most distillation systems ia commercial columns have Murphree plate efficiencies of 70% or higher. Lower efficiencies are found under system conditions of a high slope of the equiHbrium curve (Fig. lb), of high Hquid viscosity, and of large molecules having characteristically low diffusion coefficients. FiaaHy, most experimental efficiencies have been for biaary systems where by definition the efficiency of one component is equal to that of the other component. For multicomponent systems it is possible for each component to have a different efficiency. Practice has been to use a pseudo-biaary approach involving the two key components. However, a theory for multicomponent efficiency prediction has been developed (66,67) and is amenable to computational analysis. 

Typical experimental values of HETP for a random packing such as 50-mm PaH rings, and a stmctured packing, such as Intalox 2T of Norton Co., under the same system conditions, are shown in Figure 25. Many designers of packed columns prefer the use of HETP instead of but the latter is more fundamental and discrirninates between Hquid- and vapor-phase resistances. It should be noted that terms such as H and N are based on... 

The global geochemical background and enormous industrial environmental pollution have increased, thus, there are all the bases to speak about the beginning of biogeochemical formation development which has a direct influence on the ecological system condition in general as well as on the population health. 

As standard practice, this resistance is supplied with the relay by the relay manufacturer. It is of variable type, to. suit system conditions and the actual fault level. The... 

Suitable lor systems svhere fre( uenl switching is not likely and the system is I ree frotn harmonic generating sources. They are the sell-healing type and their output may become reduced with lime (bectiuse of railures of capacitor elements as a result of ssvitching inrush currents and. system harmonics). If the system conditions are not conducive, an inductor coil may be provided to limit the harmonic effects (Section 23.9). Some manufacturers, as standard practice, provide an inductor coil inside the shell to contain the inrush current and also dampen the harmonics. 

In contrast, variable air volume (VAV) systems condition supply air to a constant temperature and ensure thermal comfort by varying the airflow to occupied spaces. Most early VAV systems did not allow control of the outdoor air quantity, so that a decreasing amount of outdoor air was provided as the flow of supply air was reduced. More recent designs ensure a minimum supply of outdoor air with static... 

A liquid-gas mixture is to flow in a 3-in. Schedule 40 Kenics mixer. Estimate the pressure drop of the unit. The system conditions and physical properties are ... 

Isothermal A system condition in which the temperature remains constant. This implies that temperature increases and decreases that would otherwise occur are compensated for by sufficient heat exchange with die environment of die system. 

Protection is the branch of electric power engineering concerned with the principles of design and operation of equipment (called relays nr protective relays ) which detect abnormal power system conditions and initiate corrective action as quickly as possible in order to return the power system to its normal state. The quickness of response is an essential element of protective relaying systems—response times of the order of a few milliseconds are often required. Consequently, human intervention in the protection of system operation is not possible. The response must be automatic, quick, and should cause a minimum amount of disruption to the power system. 

Because flashing steam-condensate lines represent two-phase flow, with the quantity of liquid phase depending on die system conditions, these can be designed following the previously described two-phase flow methods. An alternate by Ruskin [28] uses the concept but assumes a single homogeneous phase of fine liquid droplets dispersed in the flashed vapor. Pressure drop was calculated by the Darcy equation ... 

The backup of clear liquid during flowing conditions must be determined in order to set the proper tray spacing. Tray spacing is usually set at twice the liquid height in the downcomer. This can be adjusted to suit the particular system conditions. 

Note Bhp values based on 75% overall efficiency. This is not exact, as efficiency changes with specific system conditions. (Plotted from data of Boteler, H. W. Natural Gasoline Supply Men s Engr. Data Book, 7 Ed., p. 40, 1957 and Huff, R. L. Petroleum Refiner, p. Ill, Feb. 1959.)... 

Head-Capacity Changes. For a given constant speed the characteristic operating curve is fixed. The pressure differential between discharge and suction will change with varying suction or system conditions. 

Curve 2-2 results from a decrease in the gas density as might be represented by the factors listed. Note that these Curves 1-1 and 2-2 might represent the new rated curve for a particular set of inlet operating conditions. Because most processes cannot fix the gas analysis and system conditions exacdy, it is important to recognize the possible implications of changes in the suction conditions on the compressor performance. 

Ash sluice pump Make-up water pump Pneumatic conveying system Conditioned ash conveyor Submerged ash conveyor... 

Data obtained from a vibration analyzer are not all that are required to evaluate machine-train or system condition. Variables such as load have a direct effect on the vibration profile of machinery and must be considered. Therefore, additional data should be acquired to augment the vibration profiles. 

Accuracy Decisions on machine-train or plant system condition will be made based on the data acquired and reported by the predictive maintenance system. It must be accurate and repeatable. Errors can be input by the microprocessor and software as well as the operators. The accuracy of commercially available predictive maintenance system varies. While most will provide at least minimum acceptable accuracy, some are well below the acceptable level. 

Alert and alarm limits The microprocessor should include the ability to automatically alert the user to changes in machine, equipment or system condition. Most of the predictive maintenance techniques rely on a change in the operating condition of plant equipment to identify an incipient problem. Therefore, the system should be able to analyze data and report any change in the monitoring parameters that were established as part of the database development. 

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